Ex Parte Uram

Patent Trial and Appeal Board

Jun 18, 2018

13314371 (P.T.A.B. Jun. 18, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE FIRST NAMED INVENTOR 13/314,371 12/08/2011 Martin Uram 35161 7590 06/18/2018 DICKINSON WRIGHT PLLC 1825 Eye St., NW Suite 900 WASHINGTON, DC 20006 UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www .uspto.gov ATTORNEY DOCKET NO. CONFIRMATION NO. 066814-00083 2232 EXAMINER NEWTON, ALEXANDRA L ART UNIT PAPER NUMBER 3779 MAIL DATE DELIVERY MODE 06/18/2018 PAPER Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte MAR TIN URAM Appeal2017-005250 Application 13/314,371 Technology Center 3700 Before JEFFREY N. FREDMAN, ULRIKE W. JENKS, and RICHARD J. SMITH, Administrative Patent Judges. FREDMAN, Administrative Patent Judge. DECISION ON APPEAL This is an appeal 1 under 35 U.S.C. § 134 involving claims to a single use surgical endoscope. The Examiner rejected the claims as obvious. We have jurisdiction under 35 U.S.C. § 6(b ). We affirm, but designate our affirmance as a New Ground of Rejection. Statement of the Case Background Prior art endoscopes "are reused after autoclaving or other sterilization. Reuse occurs in large part because of the expense of the endoscope. The most significant expense factor is the image guide which 1 Appellant identifies the Real Party in Interest as Beaver-Visitec International, Inc. (See App. Br. 1 ). Appeal2017-005250 Application 13/314,371 has a large number of micron size optical fibers" (Spec. ,r 4). "However, there is greater security from infection if the probe of the endoscope can be disposed of after each usage instead of being subject to the possibilities of human error in the sterilization process" (Spec. ,r 7). "[I]t is a key purpose of this invention to provide an endoscope design for which the cost is reasonable enough to permit and encourage disposal of the probe after each use rather then have recourse to sterilization" (Spec. ,r 8). The Claims Claims 18-20, 22-24, and 31 are on appeal. Independent claim 18 is representative and reads as follows: 18. A single use surgical endoscope comprising: a hand piece having a distal surface and first and second proximal surfaces; a laser and illumination first channel in said hand piece extending distally from said first proximal surface; an image second channel in said hand piece extending distally from said second proximal surface; a laser and illumination and image third channel in said hand piece extending proximally from said distal surface; said channels being in communication with each other within said hand piece; a probe extending distally from said third channel at said distal surface of said hand piece, said probe containing an illumination guide, a laser guide and an image guide, said illumination, laser and image guides extending into said third channel from a proximal end of said probe and terminating at a distal end of said probe; said first channel having a first axis; said second channel having a second axis; 2 Appeal2017-005250 Application 13/314,371 said third channel having a third axis; said second and third axes being substantially coaxial, said first axis having a non-zero angle relationship to said second and third axis; said illumination guide and said laser guide extending proximally from said probe to said first proximal surface of said hand piece, said laser guide extending further from said first proximal surface to a first proximal end adapted to be connected to a laser source, and said illumination guide extending further from said first proximal surface to a second proximal end adapted to be connected to an illumination source; said image guide extending proximally from said probe to said second proximal surface of said hand piece, said image guide having a third proximal end in said second channel at said second proximal surface of said hand piece, said image guide extending through said probe and said hand piece; wherein said hand piece is adapted to be detachably mounted to a camera assembly at said second proximal surface to couple said third proximal end of said image guide to said camera assembly, whereby when the camera assembly is detached from said hand piece, said first proximal end of said laser guide is detached from said laser source, and said second proximal end of said illumination guide is detached from said illumination sources, said probe, said hand piece, and said illumination, laser and image guides are disposable. The Issues A. The Examiner rejected claims 18-20, 22, and 31 under 35 U.S.C. § 103(a) as obvious over Biggs2 and Uram3 (Final Act. 2--4). B. The Examiner rejected claims 23 and 24 under 35 U.S.C. § 103(a) as obvious over Biggs, Uram, and Farris, III4 (Final Act. 4--5). 2 Biggs, US 5,868,665, issued Feb. 9, 1999. 3 Uram, US 5,121,740, issued June 16, 1992. 3 Appeal2017-005250 Application 13/314,371 A. 35 US.C. § 103(a) over Biggs and Uram The Examiner finds Biggs teaches a single use surgical endoscope comprising the elements recited in claim 18, except that "Biggs fails to teach a laser guide" (Final Act. 3--4 ). The Examiner finds "Uram teaches an analogous device comprising an illumination guide (26), a laser guide (22), and an image guide (24)" (Final Act. 4). The Examiner finds it obvious "to utilize the laser fiber of Uram with the endoscope of Biggs in order to provide a means of photocoagulation (column 1, line 44 ofUram)" (Final Act. 4). The issue with respect to obviousness is: Does the evidence of record support the Examiner's conclusion that the combination of Biggs and Uram renders claim 18 obvious? Findings of Fact 1. Biggs teaches "an endocoupler system consisting of an endocoupler connected to a myeloscope" (Biggs 3:35-37). 2. Figure 4 of Biggs is reproduced below: 4 Farris, III et al., US 2006/0276690 Al, published Dec. 7, 2006. 4 Appeal2017-005250 Application 13/314,371 Figure 4 "is a partial longitudinal cross sectional view of a myeloscope (210)" (Biggs 8:47--48). 3. The Examiner finds Biggs teaches: a hand piece (212, 216) having a distal surface ( distal end of 216) and first (proximal end of 220A) and second (proximal end of212A) proximal surfaces (FIG. 4); an illumination first channel in said hand piece extending distally from said first proximal surface (internal of 220A); an image second channel in said hand piece extending distally from said second proximal surface (internal of212A); an illumination and image third channel in said hand piece extending proximally from said distal surface (internal of 216); said channels being in communication with each other within said hand piece (FIG. 4); a probe (214) extending distally from said third channel at said distal surface of said hand piece, said probe containing an illumination guide (214BB) and an image guide (214BA), said illumination and image guides extending into said third channel from a proximal end of said probe and terminating at a distal end of said probe (FIG. 4); said first channel having a first axis (FIG. 4); said second channel having a second axis (FIG. 4); said third channel having a third axis (FIG. 4); said second and third axes being substantially coaxial, said first axis having a non-zero angle relationship to said second and third axis (FIG. 4); said illumination guide extending proximally from said probe to said first proximal surface of said hand piece, and said illumination guide extending further from said first proximal surface to a second proximal end (proximal end of 218A) adapted to be connected to an illumination source ( column 9, lines 35-38); said image guide extending proximally from said probe to said second proximal surface of said hand piece, said image guide having a third proximal end in said second channel at said 5 Appeal2017-005250 Application 13/314,371 second proximal surface of said hand piece, said image guide extending through said probe and said hand piece (FIG. 4); wherein said hand piece is adapted to be detachably mounted to a camera assembly (110) at said second proximal surface to couple said third proximal end of said image guide to said camera assembly ( column 7, lines 49-51 and 60-66), whereby, when the camera assembly is detached from said hand piece, said first proximal end of said laser guide is detached from said laser source, and said proximal end of said illumination guide is detached from said illumination sources, said probe, said hand piece, and said illumination, laser and image guides are disposable (capable of being thrown out). (Final Act. 2--4 ). 4. Biggs teaches the "myeloscope ACMI light port body attachment means (218A) is an industry standard fitting that is used to plug into a wide variety of manufactures illumination sources" (Biggs 9:35-38). 5. Biggs teaches the "endocoupler camera/eyepiece mount (112) comprises a viewing means positioned at a rear distal end. The viewing means can optionally be an endocoupler camera mounting means (112A). The endocoupler camera mounting means (112A) is used to connect to video couplers on video camera systems" (Biggs 7: 61---66). 6. Uram teaches "a small diameter endoscope used for medical purposes and more particularly to one in which illumination, viewing and laser operating functions are performed within a single relatively small diameter endoscope" (Uram 1 :9-13). 7. Uram teaches: "It is clearly preferable to apply a destructive element, such as a laser, directly to the ciliary processes .... It is a specific purpose of this invention to provide an intraocular endoscope that will be useful in photocoagulating any internal area of the eye" (Uram 1 :37--44). 6 Appeal2017-005250 Application 13/314,371 8. Uram teaches: "With the image in view and the probe 12 in position, the surgeon can then control the transmission of laser energy (usually pulses of laser energy) through the laser fiber 22 to the zone of the operation" (Uram 3: 1-5). 9. The Examiner finds: "Photocoagulation is a well-known treatment in the medical art. Treating spinal osteoid osteomas is one example of utilizing photocoagulation treatment in the spine, however providing an example is not meant to indicate that this would be the only way or reason for photocoagulation to be desirable" (Ans. 2-3). 10. Gangi5 teaches: "Percutaneous ILP [interstitial laser photocoagulation] of spinal osteoid osteoma is a promising, simple, precise, and minimally invasive technique and may be an alternative to traditional surgical and percutaneous ablations" (Gangi, abstract). 11. Laredo 6 teaches Osteoid osteoma is a benign osteoblastic tumor that affects mainly children and young adults. Treatment of choice used to be complete surgical excision. In recent years, several techniques of image-guided percutaneous treatments, mainly radiofrequency ablation and laser photocoagulation, have replaced surgical excision except in some locations such as the spme. (Laredo 998, col. 2; citations omitted). 5 Gangi et al., Percutaneous Laser Photocoagulation of Spinal Osteoid Osteomas under CT Guidance, 19 AJNR Am. J. Neuroradiol. 1955-8 (1998). 6 Laredo et al., Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous Treatment Using Two Different Biopsy Needles, 32 Cardiovasc. Intervent. Radiol. 998-1003 (July 2009). 7 Appeal2017-005250 Application 13/314,371 Principles of Law "The combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results." KSR Int'! Co. v. Teleflex Inc., 550 U.S. 398,416 (2007). Analysis We adopt the Examiner's findings of fact and reasoning regarding the scope and content of the prior art (Final Act. 2--4; FF 1-8) and agree that the claims are obvious. Appellant contends the Examiner alleges that one of ordinary skill in the art would have been motivated to make such a modification because "[i]t is well known in the art to utilize photocoagulation to treat spinal osteoid osteomas" (See Office Action at page 6). However, the Examiner does not provide any evidence of any "well known" prior art techniques utilizing an endoscope to perform imaging and photocoagulation to treat spinal osteoid osteomas. (App. Br. 11 ). Appellant contends "Biggs does not disclose or suggest photocoagulation. Thus, Appellant respectfully submits that the prior art of record does not support, but is contrary to the Examiner's [obviousness] conclusion" (id.; cf Reply Br. 2). We find this argument unpersuasive. In the Examiner's Answer, the Examiner clarifies that "[ t ]reating spinal osteoid osteomas is one example of utilizing photocoagulation treatment in the spine, however providing an example is not meant to indicate that this would be the only way or reason for photocoagulation to be desirable in the Biggs device" (Ans. 2-3; FF 9). The Examiner reasons that "[a]dding a laser fiber is desirable because it 8 Appeal2017-005250 Application 13/314,371 provides a means of photocoagulation, which is an additional desirable function, in case it is needed" (Ans. 3; cf Final Act. 6). The reasoning of the Final Office Action, that an ordinary artisan would have had reason to improve Biggs' endoscope with a laser coagulation feature found in Dram's endoscope is the essence of a combination of familiar elements that yields the predictable result of allowing Biggs' endoscope to perform laser coagulation. KSR, 550 U.S. at 416. Uram demonstrates that the ability to perform laser coagulation with an endoscope is sometimes a desirable surgical option (FF 7-8). However, because the Examiner did not provide evidence supporting the position that photocoagulation was commonly used in treatment of osteoid osteomas, we now have provided direct evidence that laser photocoagulation was a known technique for treatment of osteoid osteomas (FF 10-11). Specifically, Gangi, published in 1998, explains: "Percutaneous ILP [interstitial laser photocoagulation] of spinal osteoid osteoma is a promising, simple, precise, and minimally invasive technique" (FF 10). Thus, Gangi both evidences that laser photocoagulation is a known prior art technique for treatment of osteoid osteoma and provides reasons to use the technique in combination with prior art such as Biggs' endoscope to obtain a minimally invasive treatment. Laredo, published in 2009 and therefore also prior art, evidences regarding treatment of osteoid osteoma that "[i]n recent years, several techniques of image-guided percutaneous treatments, mainly radiofrequency ablation and laser photocoagulation, have replaced surgical excision" (FF 11 ). Thus, Laredo also evidences that laser photocoagulation was a known prior art technique (FF 11 ). 9 Appeal2017-005250 Application 13/314,371 Therefore, the prior art supports the Examiner's position that laser photocoagulation was a known technique for treatment of osteoid osteomas and that the ordinary artisan would have had reason to modify Biggs' endoscope with the laser photocoagulation elements of Uram in order to allow laser photocoagulation of osteoid osteoma as a simple, precise and minimally invasive treatment (FF 10). Because these supporting evidentiary prior art references were not previously cited, we designate this affirmance as a New Grounds of Rejection. Appellant contends: "With regard to modification of Biggs to include a laser fiber to deliver ablative energy of Uram, clearly such a modification would change the principle of operation of Biggs system for viewing the pathology of the epidural space in the lower spine region, which provides only for imaging and illumination" (App. Br. 13). We find this argument unpersuasive because any obviousness position requires some reconstruction of the starting device, and Appellant does not identify any reason why Biggs' principle of operation requires only imaging and illumination and excludes laser coagulation. Our position finds substantial support in the underlying facts of the KSR decision itself, where the Supreme Court was not persuaded by the Federal Circuit's reliance upon a statement from an "expert that claim 4 was nonobvious because, unlike in Rixon, the sensor was mounted on the support bracket rather than the pedal itself." KSR, 550 U.S. at 415. That is, like the current case where improvement of Biggs' endoscope with the laser coagulation feature of Dram's endoscope would have been obvious, some reconstruction of the prior art elements in KSR amounting to a change in the principle of operation of the pedal sensor from mechanical to electrical would have been required 10 Appeal2017-005250 Application 13/314,371 to arrive at the claimed invention. The Court, however, found that "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious unless its actual application is beyond his or her skill." Id. at 417. Just as the improvement of a pedal from a mechanical to electrical sensor did not destroy the "principle of operation," so too, Appellant provides no evidence that improvement of an endoscope to include a laser coagulation feature found in another endoscope destroys any principle of operation. Conclusion of Law The evidence of record supports the Examiner's conclusion that the combination of Biggs and Uram render claim 18 obvious. B. 35 USC§ 103(a) over Biggs, Uram, and Farris, III Appellant does not separately argue this obviousness rejection, instead relying upon their arguments to overcome the combination of Biggs and Uram (see App. Br. 14). The Examiner provides sound fact-based reasoning for combining Farris, III with Biggs and Uram (see Final Act. 4--5). Having affirmed the obviousness rejection of claim 18 over Biggs and Uram for the reasons given above, we also find that the further combination renders the rejected claims obvious for the reasons given by the Examiner. SUMMARY In summary, we affirm the rejection of claim 18 under 35 U.S.C. § 103(a) as obvious over Biggs and Uram as evidenced by Gangi and Laredo. Claims 19, 20, 22, and 31 fall with claim 18. 11 Appeal2017-005250 Application 13/314,371 We affirm the rejection of claims 23 and 24 under 35 U.S.C. § 103(a) as obvious over Biggs, Uram, and Farris, III as evidenced by Gangi and Laredo. Because we cite new evidentiary prior art, we designate our affirmance as a new ground pursuant to 37 C.F.R. § 4I.50(b). Section 4I.50(b) provides "[a] new ground of rejection pursuant to this paragraph shall not be considered final for judicial review." Section 4I.50(b) also provides: When the Board enters such a non-final decision, the appellant, within two months from the date of the decision, must exercise one of the following two options with respect to the new ground of rejection to avoid termination of the appeal as to the rejected claims: ( 1) Reopen prosecution. Submit an appropriate amendment of the claims so rejected or new Evidence relating to the claims so rejected, or both, and have the matter reconsidered by the examiner, in which event the prosecution will be remanded to the examiner. The new ground of rejection is binding upon the examiner unless an amendment or new Evidence not previously of Record is made which, in the opinion of the examiner, overcomes the new ground of rejection designated in the decision. Should the examiner reject the claims, appellant may again appeal to the Board pursuant to this subpart. (2) Request rehearing. Request that the proceeding be reheard under§ 41.52 by the Board upon the same Record. The request for rehearing must address any new ground of rejection and state with particularity the points believed to have been misapprehended or overlooked in entering the new ground of rejection and also state all other grounds upon which rehearing is sought. Further guidance on responding to a new ground of rejection can be found in the Manual of Patent Examining Procedure§ 1214.01. 12 Appeal2017-005250 Application 13/314,371 No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a)(l )(iv). AFFIRMED; 37 C.F.R. § 4I.50(b) 13 Application/Control No. Applicant(s)/Patent Under Reexamination 13/314,371 Martin Uram Notice of References Cited Examiner Art Unit 3700 Alexandra Newton U.S. PATENT DOCUMENTS * DOCUMENT NO. DATE NAME CLASS SUBCLASS D A D B D C D D D E D F D G D H D I D J D K D L D M FOREIGN PATENT DOCUMENTS * DOCUMENT NO. DATE COUNTRY NAME CLASS SUBCLASS D N D 0 D p D Q D R D s D T NON-PATENT DOCUMENTS * DOCUMENT (Including Author, Title Date, Source, and Pertinent Pages) D u Gangi et al., Percutaneous Laser Photocoagulation of Spinal Osteoid Osteomas under CT Guidance, 19 AJNR Am. J. Neuroradiol. 1955-8 (1998). Laredo et al., Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous D V Treatment Using Two Different Biopsy Needles, 32 Cardiovasc. Intervent. Radiol. 998- 1003 (2009). D w D X .. *A copy of this reference 1s not being furnished with this Office action. (See Manual of Patent Examining Procedure, Section 707.05(a).) **APS encompasses any electronic search i.e. text, image, and Commercial Databases. U.S. Patent and Trademark Office Page 1 of 1 DOCUMENT SOURCE** APS OTHER D D D D D D D D D D D D D D D D D D D D D D D D D D DOCUMENT SOURCE** APS OTHER D D D D D D D D D D D D D D DOCUMENT SOURCE** APS OTHER D D D D D D D D AJNRAmJ Neuroradiol l9:l955-l958, November 1998 Percutaneous Laser Photocoagulation of Spinal Osteoid Osteomas under CT Guidance Afshin Gangi, Jean-Louis Dietemann, Stephan Guth, Laurent Vinclair, Jean Sibilia, Reza Mortazavi, Jean Paul Steib, and Catherine Roy BACKGROUND AND PURPOSE: Spinal osteoid osteomas are rare; when they occur, they are usually treated by surgical or percutaneous excision. The aim of percutaneous inter- stitial laser photocoagulation (ILP) of osteoid osteomas under CT guidance is thermal destruction of the nidus using low-power laser energy, thus precluding bone resection and open surgery. METHODS: Three cases of spinal osteoid osteomas were treated with percutaneous ILP of the nidus. Under CT guidance, the needle was positioned in the center of the nidus, at least 8 mm from neurologic structures. Using a high-power semiconductor diode laser (805 nm) with a 400-µm optical fiber, we delivered 600 to 800 joules to the nidus, depending on its size. The procedure was performed with the patient under neuroleptanalgesia and required overnight hospitalization. RESULTS: Complete pain relief was obtained in all three patients within 24 hours of the procedure, and no major complications were incurred. Follow-up ranged from 20 months to 60 months. CONCLUSION: Percutaneous ILP of spinal osteoid osteoma is a promising, simple, precise, and minimally invasive technique and may be an alternative to traditional surgical and percutaneous ablations. Osteoid osteoma is a benign bone lesion with distinc- tive radiologic and clinical characteristics. Vertebral osteoid osteomas are rare (6%) and usually arise from the posterior elements, with the base of the transverse process, the lamina, and the pedicle being the most common sites (1-3). Conventional treat- ment of osteoid osteoma is surgical or percutaneous excision of the nidus. Promising results have been obtained with percutaneous radio-frequency ablation ( 4, 5). Interstitial laser photocoagulation (ILP) is a new technique based on in vitro and experimental animal studies. These investigation have shown prom- ising results, with the production of well-demarcated coagulations ( thermal necrosis) of predictable size in solid tissue with the use of a low-power laser technique (6). Optical fibers are inserted percuta- neously into the tumors, which are then coagulated and destroyed by direct heating. This technique has Received April 21, 1998; accepted after revision August 25. From the Departments of Radiology (A.G., J-L.D., S.G., L.V., C.R.), Rheumatology (J.S.), Anesthesiology (R.M.), and Orthope- dic Surgery (J.P.S.), University Hospital of Strasbourg, Strasbourg, France. Address reprint requests to Afshin Gangi, MD, PhD, Depart- ment of Radiology B, University Hospital of Strasbourg, 1, place de l'hopital, Strasbourg 67091, France. © American Society of Neuroradiology 1955 been applied clinically to treat tumors of the liver, pancreas, prostate, brain, breast, and lymph nodes (7-12). Experimental work has shown that a reproducible, well-defined area of coagulative necrosis is obtained around the precharred fiber tip in bone, with good correlation between energy delivered and lesion size (13). Carbonization of the fiber tip before ILP (pre- charring) makes the effect more predictable. The temperatures at 8 mm around the fiber tip exceed the threshold for osteocyte necrosis (50°C) at 1000 to 1200 joules (13). The e)..1:ent of thermal necrosis de- pends on the laser wavelength, the energy deposited, the power used (tip temperature), the thermal and optical properties of the target tissue, and the type of optical fiber used (6, 9). The size of osteoid osteomas falls within the range of those that can be effectively coagulated, and the nidus can be identified precisely on CT scans. The transmission of heat within bone is sharply limited by blood flow and by the fact that high temperatures cannot be sustained over great dis- tances (13-15). The purpose of this study was to evaluate percuta- neous ILP of spinal osteoid osteomas under CT guid- ance with the use of low-power laser energy as a means of effecting thermal destruction of the nidus without bone resection and open surgery. 1956 GANGI F1G 1. 25-year-old man with back pain for 18 months, which was dramatically relieved by aspirin. Radiographic findings were normal. A, Bone scintigram shows an area of increased activity in the transverse process of T8. B, CT scan shows a lucent area in the right transverse process (a/Tows) of T8 with a small focus of calcification within it. Sclerosis surrounding the lesion was noted and a diagnosis of osteoid osteoma was suggested. C, Under CT guidance, an 18-gauge spinal needle was placed by a posterior approach in the center of the nidus. A 400-µm fiber was introduced into the lesion through the canula of the spinal needle. D, Follow-up CT scan obtained 21 months after the procedure shows replace- ment of the lucent area (nidus) by a normal medullary cavity (a/Tows). AJNR: 19, November 1998 ::::::····· rtr :_)_f_,_·.:.:,J_,.1_, .. _:._, __ :: __ 1:._J:,\_,.1_,_i_,.i_'.l_,.~_=.i_:_)_:_]_:_(_,.1_,_)_,.=_.'.·:. ::<<<<·:•:•:•:• ·::::::::::(ff :mttm:1111:: , r Summary of Patients Who Underwent Percutaneous Interstitial Laser Photocoagulation of Spinal Osteoid Osteomas Age (y)/ Nidus Location/ Nidus Distance to Case Nearest Neural Sex Region Size (mm) Strncture (mm) 26/F Sacrum laminae/cortex 5 10 2 25/M Transverse process T8/ 5 8 medullary cavity 3 27/M Articular process C3/ 7 12 cortex Methods From June 1993 to February 1998, we encountered four cases of spinal osteoid osteoma. Percutaneous ILP guided by CT (Fig 1) was performed in three patients (two men and one woman, 25 to 27 years old). Nidus location and patient data are reported in the Table. One patient with osteoid osteoma of the lamina was not treated with ILP. In this case, the distance between the nidus and dura mater was onlv 3 mm, and the risk of neurologic damage was high (Fig 2). ILP was not performed if doubt persisted as to the diagnosis of osteoid osteoma or if the nidus was too near neurologic structures (the center of the nidus must be positioned at least 8 mm from dura mater and/or nerve roots) (Fig 3). The temperature at 8 mm around the fiber tip exceed 50°C at 1000 to 1200 joules (13). Patients with spinal osteoid osteoma were hospitalized for 1 night after the procedure. ILP was performed by using a con- tinuous-wave semiconductor portable diode laser (Diomed 25 laser, Cambridge, UK) with a wavelength of 805 nm. A steril- ized, single, freshly cleaved, 400-µm fiber with polymer clad- ding was used with a bare tip to deliver laser energy to the tumor (7, 13). After Treatment Needle Energy Deposited Pain Relief/ Type/Gauge (joules) Time Required Follow-up Recurrence (days) (mo) Ostycut/14 600 Complete/I 60 No Spinal/18 600 Complete/I 32 No Spina!i18 800 Complete/I 20 No F1G 2. CT scan obtained in a 12-year-old boy shows an osteoid osteoma of the lamina. ILP was rejected because the nidus was too near the dura matter. AJNR: 19, November 1998 A l l ' ' ' ' '+-->' 0 B A CT scanner was used to assure precise needle placement and to detect carbonization (gas inside the nidus ). Penetration of the needle into the nidus is always painful and the interven- tion was performed with the patient under neuroleptanalgesia. The lesion was located precisely on CT scans and the dimen- sions of the nidus established. The nidus's largest diameter was used to determine the energy necessary to coagulate the tumor (Fig 3A). The current protocol is as follows: nidus diameter «; 4 mm, 500 joules; nidus diameter = 5 mm, 600 joules; nidus diameter = 6 mm, 800 joules; and nidus diameter 2> 8 mm, 1000 to 1200 joules (13, 16). The experimental work has proved that maximal width extent (14 to 16 mm) is reached after 1000 to 1200 joules of energy delivery. Larger lesions require the insertion of multiple fibers for complete ablation. The needle was guided by means of CT (16, 17) (Fig lC). Subperiosteal niduses or cortical niduses without major ossifi- cation (n = 2) were punctured directly with an 18-gauge spinal needle (Becton Dickinson, Rutherford, NJ). In one case, cor- tical perforation was accomplished with a 14-gauge bone biopsy needle (Ostycut, Angiomed/Bard Karlsruhe, Germany). A co- axial biopsy was not considered because the small size of the needles does not allow sufficient material to be obtained to confirm the diagnosis. In all cases, the fiber was inserted into an 18-gauge spinal needle, which served to protect the fiber from breakage. The 18-gauge needle tip was inserted into the center of the nidus. The 400-µm precharred fiber was inserted through the needle and the needle was withdrawn about 5 mm, so that the tip of the bare fiber lay within the tumor. Precharring the fiber tip was performed clinically by firing the fiber into a few milliliters of the patient's own blood just before introduction. The diode laser (805 nm) was turned on in continuous-wave mode at a power of 2W for 300 to 400 seconds (total energy, 600 to 800 joules). The energy delivered depended on nidus size (9, 13, 14, 16, 17) (Table). Results Percutaneous ILP was successful in all patients, producing relief of pain within 24 hours of the pro- cedure and allowing a prompt return to normal ac- tivities. After the procedure, one patient ( case 2) had a moderate headache for 1 week (Fig 2). Follow-up ranged from 20 to 60 months (mean, 37 months), SPINAL OSTEOID OSTEOMAS 1957 F1G 3. Drawings show the technique of measurements and coagulation of spinal osteoid osteoma. A, Osteoid osteoma of the lamina. The largest diameter (/) of the nidus is mea- sured to determine the energy necessary to coagulate the tumor. The distance (d) from the center of the nidus to neural structures and dura matter is measured. A distance of at least 8 mm is mandatory to avoid neural damage, particularly in front of the fiber. B, Introduction of the needle and inser- tion of the fiber into the center of the ni- dus. Coagulation (spherical regions of marrow and cortical necroses, arrows) is present around the fiber tip. The longitu- dinal diameter of coagulation (along the fiber track) is greater than the axial diameter. during which time the patients remained pain-free without evidence of recurrence. Follow-up CT exam- inations were performed in all patients. After a pe- riod of 6 to 24 months, the lucent area of the nidus was replaced by normal bone (Fig lD) or sclerosis. No late complications or recurrences were observed. Discussion Many techniques have been proposed to treat osteoid osteoma, including surgical resection, percu- taneous trocar extraction, alcoholization, and ther- mocoagulation by radio frequency and laser ( 4, 5, 16-26). Surgical or percutaneous excision of the ni- dus is not free from risk, particularly surgical excision. Patients treated by wide excisional margin have an average hospital stay of 5 days (23). Weakening of bone from surgical removal of a portion of the cortex is particularly problematic in weight-bearing bones. This risk is lower with percutaneous extraction of the nidus, but the use of a large drill (7-mm diameter) and the need to make several passes to complete the resection on weight-bearing bones impose limitations on activity for up to 3 months (20, 25). In patients with spinal osteoid osteoma, the use of such large instruments incurs the risk of neurologic and vascular injury. ILP has been performed in experimental models to determine the feasibility of bone photocoagulation using an 805-nm diode laser and to define the param- eters that influence lesion size and shape (13). This experimental work has shown that a reproducible, well-defined area of coagulative necrosis can be ob- tained around the precharred fiber tip in bone, with good correlation between energy delivered and lesion size. The use of precharred fiber allows a more re- producible coagulation size, independent of location on the bone. This work has also proved that maximal extent is reached after delivery of 1000 to 1200 joules 1958 GANGI (13). More energy deliverance at the same position does not modify the coagulation size. This finding is consistent with previous studies that showed that the transmission of heat within bone is sharply limited (14, 15). Forty-seven patients with osteoid osteoma in various locations were treated with percutaneous ILP of the nidus under CT control without major compli- cations. The procedure required only overnight hos- pitalization and did not limit normal activity. The drawback of this technique is the lack of his- tologic verification. In procedures involving resec- tional and radio-frequency ablation with systematic biopsy, confirmation of osteoid osteoma is obtained in 57% to 79% of cases (5, 20, 24). The joint decision to proceed with ILP was made by a team of rheuma- tologists, neurosurgeons, orthopedic surgeons, skele- tal radiologists, and interventional radiologists. ILP of osteoid osteoma was only performed in patients with typical lesions. If any doubts persisted in the diagnosis of osteoid osteoma, ILP was not done. Conclusion ILP of spinal osteoid osteoma under CT guidance is a minimally invasive technique in which an 18- gauge to maximum 14-gauge needle is used to intro- duce the fiber into the nidus. The ability to precisely control the treated area, a high degree of precision, applicability in joints, and excellent dose-response characteristics may make ILP and radio-frequency ablation preferable to alcoholization and other in situ tissue ablation techniques (4, 5, 16-19, 22). The pro- cedure is performed with the patient under neuro- leptanalgesia and requires only overnight hospitaliza- tion. ILP is not appropriate for the treatment of osteoid osteoma when the nidus is too near neural structures, as a minimum distance of 8 mm is man- datory to avoid neural damage. Otherwise, ILP is a safe and effective way to treat this benign tumor. Acknowledgment We thank Stephen Ferron for his assistance with this work. References 1. Kransdorf MJ, Stull MA, Gilkey FW, Moser RP Jr. Osteoid os- teoma. Radiographies 1991;11:671-696 2. Resnick D, Kyriacos M, Greenway GD. Tumor and tumor-like lesions of bone: imaging of specific lesions. In: Resnick D, Ni- wayama G, eds. Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia: Saunders; 1995:3629 3. Runge M. Osteome osteo,de vertebral: Interet diagnostique de !'examen scanographique. J Radiol 1986;67:885-889 4. Rosenthal DI, Alexander A, Rosenberg AE, Springfeld D. Ablation AJNR: 19, November 1998 of osteoid osteomas "ith a percutaneously placed electrode, a new procedure. Radiology 1992;183:29-33 5. Rosenthal DI, Springfield DS, Gebhardt MC, Rosenberg AE, Man- kin HJ. Osteoid osteoma: percutaneous radio-frequency ablation. Radiology 1995;197:451-454 6. Bown SG. Phototherapy of tumors. World J Surg 1983;7:700-709 7. Amin Z, Buonaccorsi GA, Mills TN, et al. Interstitial laser photo- coagulation in rat liver: importance of fibre type, laser wavelength and tissue charring. In: Jacques SL, ed. Proceeding of the Society for Photo-optical Instrumentation Engineers (SPIE): Laser-Tissue Inter- action fl/. Washington, DC: SPIE; 1993;1882:172-183 8. Amin Z, Donald JJ, Masters A, et al. Hepatic metastases: intersti- tial laser photocoagulation "ith real-time lIS monitoring and dy- namic CT evaluation of treatment. Radiology 1993;187:339-347 9. Dachman AH, Smith MJ, Burris JA, VanDeMerve WP. Interstitial laser ablation in experimental models and clinical use. Semin Inter Radial 1993;10:101-112 10. Harries SA, Amin Z, Smith MEF, et al. Interstitial laser photoco- agulation as a treatment for breast cancer. Br J Surg 1994;81:1617- 1619 11. Kahn T, Schwabe B, Bettag M, et al. Mapping of the cortical motor hand area "1th functional MR imaging and MR imaging-guided laser-induced interstitial thermotherapy of brain tumors. Radiol- ogy 1996;200:149-157 12. Nolsoe P, Torp-Pedersen S, Burchart F, et al. Interstitial hyper- thermia of colorectal liver metastases "1th a ES-guided Nd:YAG laser "1th a diffuser tip: a pilot clinical study. Radiology 1993;187: 333-337 13. Gangi A, Gasser B, De Unamuno S, et al. New trends in interstitial laser photocoagulation of bones. Semin Afuscu!oskeleta! Radial 1997;1:331-337 14. Lundskog J. Heat and bone tissue. Scand J Plast Reconstr Surg 1972;Suppl 9:1-80 15. Tillotson CL, Rosenberg AE, Rosenthal DI. Controlled thermal injury of bone report of a percutaneous technique using radiofre- quency electrode and generator. Invest Radio! 1989;24:888-892 16. Gangi A, Dietemann JL, Gasser B, et al. Percutaneous laser pho- tocoagulation of osteoid osteomas. Semin Afusculoskeletal Radio! 1997;1:273-279 17. Gangi A, Dietemann JL, Gasser B, et al. Percutaneous laser pho- tocoagulation of osteoid osteomas "1th use of CT guidance. Radi- ology 1997;203:843-848 18. Abe E, Sato K, Okada K, Mizutani Y, Ishizawa N, Suzuki T. Selective en bloc resection of osteoid osteoma of the superior articular process of the sacral spine: a case report. Spine 1993;18: 2336-2339 19. Adam G, Neuerburg J, Vorwerk D, Forst J, Gunther RW. Percu- taneous treatment of osteoid osteomas: combination of drill biopsy and subsequent ethanol injection. Semin Afusculoskeletal Radial 1997;1:281-284 20. Assoun J, Railhac JJ, Bonnevialle P, et al. Osteoid osteoma: per- cutaneous resection with CT guidance. Radiology 1993;188:541-547 21. Doyle T, King K. Percutaneous removal of osteoid osteomas using CT control. Clin Radiol 1989;40:514-517 22. Kohler R. Treatment of osteoid osteoma by percutaneous drill resection with CT control: a study of 12 cases. J Pediatr 1992;2: 78-82 23. Lindner NJ, Scarborough M, Ciccarelli JM, Enneking WF. Die CT-gesteuerte Thermokoagulation des Osteoidosteomas im Ver- gleich zu traditionellen verfahren. Z Orthop 1997;135:522-527 24. Mazoyer JF, Kohler R, Bossard D. Osteoid osteoma: CT-guided percutaneous treatment. Radiology 1991;181:269-271 25. Parlier-Cuau C, Nizard R, Champsaur P, Harnze B, Laredo JD. Percutaneous resection of osteoid osteomas. Semin Afusculoskeletal Radial 1997;1:257-264 26. Voto SJ, Cook AJ, Arrington G, Weiner IDS, Ewing JW. Treat- ment of osteoid osteoma, by computed tomography guided excision in a pediatric patient. J Pediatr Orthop 1990;10:510-513 Cardiovasc Intervent Radio! (2009) 32:998-1003 DOI 10.1007 /s00270-009-9635-2 Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous Treatment Using Two Different Biopsy Needles Jean-Denis Laredo· Bassam Hamze · Riadh Jeribi Received: 20 December 2008 / Accepted: 20 May 2009 / Published online: 31 July 2009 © Springer Science+Business Media, LLC and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2009 Abstract Biopsy is usually performed as the first step in percutaneous treatment of osteoid osteomas prior to laser photocoagulation. At our institution, 117 patients with a presumed diagnosis of osteoid osteoma had a trephine biopsy before a percutaneous laser photocoagulation. Biopsies were made using two different types of needles. A Bonopty biopsy needle (14-gauge cannula, 16-gauge tre- phine needle; Radi Medical Systems, Uppsala, Sweden) was used in 65 patients, and a Laurane biopsy needle (11- gauge cannula, 12.5-gauge trephine needle; Laurane Medical, Saint-Arnoult, France) in 43 patients. Overall biopsy results were positive for osteoid osteoma in 83 (70.9%) of the 117 cases. The Laurane needle provided a significantly higher positive rate (81.4%) than the Bonopty needle (66. l %; p < 0.05). This difference was not due to the size of the nidus, which was similar in the two groups (p < 0.05) and may be an effect of differences in needle caliber (12.5 vs. 14 gauge) as well as differences in needle design. The rate of positive biopsy results obtained in the present series with the Laurane biopsy needle is, to our knowledge, the highest rate reported in series dealing with percutaneous radiofrequency ablation and laser photoco- agulation of osteoid osteomas. Keywords Osteoid osteoma · Biopsy · Laser coagulation 1.-D. Laredo (2) · B. Hamze · R. Jeribi Service de Radiologie, Hopital Lariboisiere, 2 rue Ambroise Pare, 75010 Paris, France e-mail: jean-denis.laredo@lrb.aphp.fr; jean-denis.laredo@uphs.upenn.edu J.-D. Laredo Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA ~ Springer Introduction Osteoid osteoma is a benign osteoblastic tumor that affects mainly children and young adults. Treatment of choice used to be complete surgical excision. In recent years, several techniques of image-guided percutaneous treatments, mainly radiofrequency ablation [l-5] and laser photocoagulation [6-8], have replaced surgical excision except in some locations such as the spine. Some authors consider the clinical and radiological pre- sentation characteristic enough to bypass histological confinnation [ l]. However, other authors still perform biopsy as the first step in percutaneous treatment, to rule out other lesions such as Brodie's abscess [9], chon- droblastoma [10], and intracortical hemangioma [l [], which may mimic osteoid osteoma. The percentage of pathological confirmation among series and with the type and caliber of biopsy needles used [2, 5, 8, 12, 13]. We report here our clinical experience with pretherapeutic biopsy of osteoid osteomas with two different needles and compare the percentages of positive histological results obtained. Materials and Methods Patients lnstimtional review board approval was obtained for this retrospective study. From November 2000 to March 2006, 117 patients with a presumed diagnosis of osteoid osteoma were treated at our institution with percutaneous laser photocoagulation. From November 2000 to December 2004, biopsies were made in 65 patients using a 14-gauge Bonopty biopsy needle with a 16-gauge Bonopty trephine J.-D. Laredo et al.: Percutaneous Biopsy of Osteoid Osteomas needle (Radi Medical Systems, Uppsala, Sweden). From January 2005 to March 2006, an I I -gauge Laurane biopsy needle (Laurane Medical, Saint-Arnoult. France), with a 12.5-gauge trephine needle was used for deep lesions (n = 43). During the same period, nine small superficial lesions were biopsied with a 16-gauge Franseen biopsy needle (International Medical Devices, Quistello, Italy) but are not included in this analysis. Imaging Techniques All patients were seen during a preinterventionnal consul- tation and investigated with conventional radiographs and CT scan. Cases were considered typical for osteoid oste- oma if they exhibited a round or ovoid central lucent nidus with well-defined margins and a cental calcification. In cases with equivocal CT findings (n = 19; central lucent nidus not round or ovoid or not sharply demarcated, absence of central calcification), MRI with nonenhanced and enhanced conventional sequences was obtained. In recent cases (n = 9), dynamic sequences after gadolinium injection were added. Case selection for percutaneous treatment was achieved by one of two experienced mus- culoskeletal radiologists (B.H. has 19 years and J.L. has 27 years of experience) on the basis of the clinical and radiological findings. Biopsy Techniques Biopsy was systematically performed during percutaneous laser photocoagulation treatment as the first step in the procedure. The procedure was carried out under CT guid- ance using either regional or general anesthesia and under strict aseptic conditions. Prior to the procedure, the approach and site of skin puncture were determined from I-mm-thick contiguous CT sections covering the whole lesion. The 14-gauge Bonopty set includes an external cannula and an internal drill, which are inserted together after local anesthesia and advanced into the bone up to the nidus mar- gin. The internal drill has an asymmetric tip, making a hole larger than its own size and allowing progressive advance- ment of the external cannula into the bone (Fig. 1 ). Once the nidus is reached, the internal drill is replaced by the 16-gauge biopsy trephine needle and the biopsy is performed. The I I -gauge Laurane needle includes an external cannula and an internal sharp stylet, which are inserted together after local anesthesia and advanced into the bone up to the nidus margin. In cases of very hard bone, the usual cannula and stylet are replaced by a special cutting cannula with a perforating drill (Fig. 2), which allows trephination of hard cortical bone. Once the nidus is reached, the drill is replaced by a 12.5-gauge trephine needle for biopsy (Fig. 3). 999 Fig. 1 The Bonopty biopsy needle set. From top to bottom: closeup of the tip of the eccentric drill, the 16-gauge eccentric drill with a white handle, and the 14-gauge external cannula, and its stylet, with their green handle. The eccentric drill has an asymmetrical tip, which allows it to make a hole larger than its own caliber. Therefore, the external cannula can be advanced progressively into the bone together with the drill To avoid a second needle approach to the patient, and considering our stringent selection criteria, results of the pathological examination of the biopsy specimens were not awaited and laser ablation was carried out in the same session as the biopsy. Pathological examination of the biopsy specimens was canied out by two pathologists specialized in musculoskeletal diseases (27 and 14 years of experience). Among the 108 patients treated. 4 were lost to follow-up before 6 months and 10 at between 6 and 24 months of follow-up. Median follow-up was 48 months (range: 1 to 97 months). Rate of treatment success, defined as no or minimal intermittent pain with no need for medication, was 94% (n = 98/104) at 6-month follow-up and 95% (n = 89/ 94) at 24-month follow-up. Results Lesion Location In the Bonopty group, the 65 lesions were located in the femur (head, n = I; neck, n = 20; diaphysis, n = 17), tibia (n = 11), acetabulum (n = 3), cervical spine (n = 1), tar- sal bones (n = 3), humerus (n = 2), carpal bones (n = 3), metacarpal bones (n = 2), and hand phalanges (n = 2). In the Laurane group, the 43 lesions were located in the femur (head, n = I; neck, n = IO; diaphysis, n = 7), tibia (n = 12), spine (n = 2), ischial tuberosity (n = 2), ace- tabulum (n = 1), fibula (n = 1), tarsal bones (n = 2), humerus (n = 2), carpal bones (n = 2), and metacarpal bones (n = 1). In 7 of the 43 lesions biopsied with the Laurane needle set, the cutting cannula and perforating drill for hard bone were needed to penetrate a sclerotic bone prior to the biopsy itself. ~ Springer 1000 Fig. 2 The I I-gauge Laurane biopsy needle set. A From left to right: distal extremities of the sharp stylet, perforating drill, and cutting cannula for hard bone. The latter two pieces are used together for hard cortical bone trephination. The cutting cannula for hard bone has two slots and two sharp helical cutting edges and may be used in combination with either the perforating drill or the sharp stylet. B Tip of the cutting cannula containing the perforating drill (above) or the sharp stylet (below). C Closeup of the tip of the 12.5-gauge trephine needle with five sharp semihelical teeth Results of Biopsy Bone samples from the central lucent area were obtained in 100% of the lesions biopsied with the Laurane needle and in 87.7% (n = 57/65) of the lesions biopsied with the Bonopty needle. In the remaining cases, no bone sample ~ Springer J.-D. Laredo et al.: Percutaneous Biopsy of Osteoid Osteomas • - C Fig. 3 Example of percutaneous biopsy with the 12.5-gauge trephine needle introduced into the I I -gauge Laurane needle in a case of osteoid ostemna of the posterior cortex of the femoral diaphysis in a 19 year-old boy. A Axial CT image showing the small nidus with a central calcification into the posterior cortex of the femoral diaphysis. B Axial multiplanar CT reformation. C Coronal multiplanar CT reformation. D Sagittal multiplanar CT reformation. B-D show that the tip of the trephine needle is actually into the nidus in all three planes. In this case, a lateral approach was selected rather than a direct posterior approach to avoid the sciatic nerve J.-D. Laredo et al.: Percutaneous Biopsy of Osteoid Osteomas 1001 Table 1 Biopsy results using two different trephine needles in a series of 117 osteoid osteomas Needle No. of Mean age Gender ratio, Mean nidus size (range), Positive biopsy Bonopty group Laurane group patients 65 43 (range) M/F 22 (6-49) 2.82 20 (6-47) 4.25 was obtained despite several attempts. Overall biopsy results were positive for osteoid osteoma in 78 (72.2%) of the 108 cases. Among the 30 negative cases, no bone sample was obtained in 8 cases and normal or nonspecific reactive bone was found in 22 cases. In the Bonopty group, the biopsy was positive in 43 (66.1 %) of 65 cases. In the Laurane group, the biopsy was positive in 35 (81.4%) of 43 cases (Table 1 ). There was no statistical difference in treatment outcome between patients with positive biopsy results and those with nonspecific pathological findings. Discussion Due to improvements in imaging guidance and treatment procedures, surgical treatment of osteoid osteomas has been progressively replaced by percutaneous treatments. Even in cases with characteristic clinical and radiological presentation, some of the authors still perform a biopsy during percutaneous treatment of osteoid osteomas [2, 8, 12-14] to rule out mimickers such as Brodie's abscess [9]. Percutaneous resection of osteoid osteomas has been performed using a large variety of trephine needles of large caliber, ranging from 3 to 9 mm [4, 5, 7, 8, 15-17], pro- viding larger specimens for histology in comparison with other ablative techniques [18]. Reported rates of positive findings in percutaneous resection of osteoid osteoma range from 48% to 100% (Table 2) [15, 17, 19-21]. mm results, % 7.31 (3-15) 66.1 8.52 (3-23) 81.4 Trephine needles of much smaller caliber ( 11-16 gauge) have been used to achieve radiofrequency ablation (Table 3). Reported confirmation rates at pathology range from 36% to 73% [2, 4, 5, I 2, 13]. A biopsy was not systematically performed in some of the reported series on CT-guided laser photocoagulation therapy [6, 7, 16]. In the study by Gangi et al. [8], a biopsy was performed in 88 of the 114 patients using a 14-gauge Bonopty needle (Radi Medical System, Uppsala, Sweden) or an 18-gauge spinal needle (Becton Dickinson, Rutherford, NJ, USA). The positive biopsy rate was 75%, a rate higher than the one we obtained in the present study with the same needle. At our institution, biopsy is systematically performed as the first part of the laser photocoagulation procedure. Since the positive biopsy result rate obtained with the Bonopty needle was relatively low (66.1 % ), we switched to the Laurane biopsy needle set, which provides larger samples and allows easy multiple sampling if needed. The positive biopsy rate obtained in the present series with the Laurane needle (81.4%) was significantly higher compared to that for the Bonopty needle. However, this may be simply an effect of differences in needle caliber (12.5 vs. 14 gauge) rather than in needle design. We agree that, due to the high specificity of imaging techniques, especially volumetric CT with three- dimensional reformations as well as nonenhanced and dynamic-enhanced MRI, a biopsy is not indispensable prior Table 2 Biopsy results in reported series of percutaneous resection of osteoid osteomas Reference No. of patients Instrument used Sans et al. [15] 38 7-mm Kohler trephine needlea or 3-mm-bore Laredo biopsy needle Towbin et al. [5] 9 5.5- or 7.9-mm Michel ttephine needleb Mazoyer et al. [24] 7 3-mm electrically driven drill or 4-mm toothed drillc Parlier et al. [8] 30 7-mm Kohler trephine needlea Kohler et al. [ 1 7] 27 7-mm Kohler trephine needlea Voto et al. [9] 9 Corb needle (variable size)d a Aesculap, Tuttlingen, Germany b Baxter/v. Mueller, Deerfield, IL, USA c Craig-Kogler vertebral biopsy instrument (Lawton, Tuttlingen, Germany) a Zimmer, Warsaw, IN, USA Positive biopsy results, no. 28 of 38 (74%) 5 of 9 (63%) 4 of 7 (57%) 23 of 30 (77%) 13 of 27 (48%) 9 of 9 (100%) ~ Springer 1002 J.-D. Laredo et al.: Percutaneous Biopsy of Osteoid Osteomas Table 3 Biopsy results in reported series of radiofrequency ablation of osteoid osteomas Reference No. of patients Instrument used Biopsy Rosenthal et al. [3] 263 Bonopty biopsy needle" (16 G) or OstyCut needleb (16 G) 197 of 271 (73%) Cribb et al. [6] 45 Bonopty biopsy needle (16 G) or RITA Starburst needle (14 G) 27 of 45 (60%) Vanderschueren et al. [12] 97 Jamshidi biopsy needlec (11 G) or Bonopty biopsy needle" (16 G) 21 of 56 (38%) Lindner et al. [2] 58 Jamshidi needle (11 G) or a 14-G drill systemd 4 of 11 (36%) a Radi Medical Systems, Uppsala, Sweden b Bard/ Angiomed, Karlsruhe, Germany c Sherwood Medical, Belfast, Northen Ireland d Richards Surgical Products, Kalamazoo, MI, USA to percutaneous treatment of osteoid osteomas. With such imaging techniques, the only conditions which can be confused with an osteoid osteoma are an osteoblastoma in the case of large lesions, a small chondroblastoma in cases located to a bone epiphysis or an equivalent skeletal location, and, less likely, a Brodie abcess or an eosinophilic granuloma. There is no inconvenience, however, to treat such lesions with percutaneous ablation except in the case of a Brodie's abcess, which requires adaptation of the antibiotic therapy to the responsible microorganism. In addition to this. we found that obtaining a pathological confirmation may help to decrease patient anxiety, espe- cially in the small percentage of cases who experience treatment failure or recurrence. Whatever the sampling technique of the nidus, biopsy or percutaneous or surgical resection, there is a substantial percentage of nondiagnostic biopsy findings in osteoid osteomas. For example, in two recent large series of osteoid osteomas treated percutaneously, the percentage of nondi- agnostic biopsy findings was 27% with radiofrequency coagulation [13] and 24% with laser photocoagulation [8]. Nondiagnostic biopsy results were common in reported series of osteoid osteomas treated surgically as well [22, 23]. One possible explanation for the absence of pathological features of osteoid osteoma at biopsy is that such lesions are not true osteoid osteomas. However. all the cases included in our series as well as in the series of Rosenthal et al. [13] had clinical and imaging features characteristic of osteoid oste- oma. In addition, there was no difference in outcome after treatment between these two subgroups in either series. Therefore. in agreement with previous authors [13, 23], we believe that the majority of our patients with nondiagnostic biopsy findings did have osteoid osteomas despite the neg- ative biopsy results, and the substantial rate of negative biopsy findings remains unexplained to date. Knowing that, with time, osteoid osteomas may involute and become painless, one possible explanation is that, in some cases, the osteoid tissue of the nidus may undergo progressive matu- ration into bone, making it undistinguishable from mature bone at histologic examination. ~ Springer Conflict of interest Two of the others (J.L. and B.H.) are co-inventors of the Laurane needle but guarantee that all the infor- mation provided in this article is completely realistic. References 1. 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Mazoyer JF, Kohler R, Bossard D (1991) Osteoid osteoma: CT- guided percutaneous treatment. Radiology 181:269-271 ~ Springer