Radiation dosimetry of intraoperative cone-beam compared with conventional CT for radiofrequency ablation of osteoid osteoma.

735 C OPYRIGHT Ó 2014

BY

T HE J OURNAL

OF

B ONE

AND J OINT

S URGERY, I NCORPORATED

Radiation Dosimetry of Intraoperative Cone-Beam Compared with Conventional CT for Radiofrequency Ablation of Osteoid Osteoma Edward Y. Cheng, MD, Sameer M. Naranje, MBBS, MRCS(Glasgow), and E. Russell Ritenour, PhD Investigation performed at the Departments of Orthopaedic Surgery and Diagnostic Radiology, University of Minnesota, Minneapolis, Minnesota

Background: Radiofrequency (RF) ablation is the standard of care for the surgical treatment of non-spinal osteoid osteoma and has greatly reduced morbidity associated with surgical excision. Precise placement of the RF ablation probe is necessary to avoid incomplete ablation. Limiting radiation exposure is especially advantageous in the pediatric population in whom osteoid osteoma frequently occurs. The aim of this study was to compare the radiation dosimetry and clinical outcomes among patients treated with RF ablation using three different localization techniques. Methods: Case-control methods were used to analyze sixty-six cases. Patients were categorized into three treatment groups: (1) intraoperative three-dimensional cone-beam CT (computed tomography) imaging (O-Arm) with surgical navigation (StealthStation S7), (2) intraoperative three-dimensional imaging (O-Arm) only, and (3) radiology suite-based diagnostic CT imaging. Radiation dosimetry and clinical outcome were analyzed with use of the dose-length product and local-relapse-free survival, respectively. Results: Mean age was nineteen years for the twenty-three patients in group 1, twenty years for the seven patients in group 2, and nineteen years for the thirty-six patients in group 3. Mean follow-up was fifty-three months. The mean radiation dose for groups 1, 2, and 3 was 446.62, 379.78, and 1058.83 mGy-cm, respectively. Significant (p < 0.05) differences in the radiation dose existed between groups 1 and 3 and between groups 2 and 3, whereas no difference was found between groups 1 and 2. Local-remission-free survival at three years for groups 1, 2, and 3 was 84.7% (95% confidence interval [CI], 64.5% to 100%), 100% (95% CI, 100% to 100%), and 90.7% (95% CI, 80.7% to 100%), respectively. Fifty-eight (92%) of the sixty-three followed patients were asymptomatic at the latest follow-up visit. Conclusions: RF ablation using intraoperative cone-beam CT imaging, with or without surgical navigation, was associated with a significantly lower radiation dose compared with ablation using a radiology suite-based CT technique. Ablation using each of the three imaging techniques was equally effective in treating osteoid osteomas with a similar risk of relapse. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.

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irst described by Jaffe in 1953, osteoid osteoma is a benign bone lesion comprising 3% to 4% of all bone tumors and 11% to 12% of benign bone tumors1,2. It is typically seen in patients five to twenty years of age and is more common in males3-5. The most common site of occurrence is the diaphysis of long bones such as the femur and tibia. Various surgical

treatment options have been described for the management of painful, symptomatic osteoid osteoma that is recalcitrant to the first line of treatment, nonsteroidal anti-inflammatory drugs. These options include surgical excision of the nidus and radiofrequency (RF) ablation6-8. Surgery involves curettage, en bloc resection, or wide resection, with reported success rates of

Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. In addition, one or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

J Bone Joint Surg Am. 2014;96:735-42

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http://dx.doi.org/10.2106/JBJS.M.00874

736 TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O LU M E 96 -A N U M B E R 9 M AY 7, 2 014 d

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R A D I AT I O N D O S I M E T R Y O F I N T R A O P E R AT I V E C O N E -B E A M C O M PA R E D W I T H C O N V E N T I O N A L CT F O R R F A B L AT I O N

90% to 100%3,8,9. The reported rate of complications associated with surgical treatment ranges from 20% to 45%, with a 4.5% prevalence of fractures3,8,9. Less invasive procedures using computed tomography (CT) or fluoroscopy to guide percutaneous resection have also been described, with reported success rates of 80% to 100% and complication rates of 4% to 24%8,10,11. More recently, CT-guided RF ablation has been established as a safe and effective minimally invasive treatment option that is preferable to surgical excision of nonspinal osteoid osteomas because of reduced morbidity5,12,13. Treatment failures with RF ablation are likely due to errors in localization leading to eccentric placement of the RF electrode14-16. The precision of RF ablation probe placement is facilitated by using CT for targeting the nidus17,18. Recent evidence has highlighted the importance of minimizing radiation exposure in the pediatric and adolescent population19-25. The National Cancer Institute has identified radiation exposure as a public health concern23, and this has led to the ‘‘Image Gently’’ campaign by an alliance of organizations formed by the Society for Pediatric Radiology 26. The introduction of three-dimensional navigation systems has enabled precise real-time intraoperative tracking of surgical instruments or implants within a bone, by means of virtual imaging, without any radiation exposure27-29. The aim of the present study was to compare (1) the radiation dosimetry associated with RF ablation using three different localization techniques, and (2) the clinical outcome of the treated patients.

Medtronic), (2) intraoperative three-dimensional imaging only (O-Arm without navigation), and (3) radiology suite CT imaging (Genesis LightSpeed QX/i [GE Healthcare], Somatom Sensation 40 [Siemens Healthcare USA, Malvern, Pennsylvania], or Somatom Plus 4 [Siemens]). Radiation dosimetry, expressed as the dose-length product, was calcu30,31 lated as described previously from scans stored in the PACS (picture archiving and communication system); scans of eight of the sixty-six patients were not retrievable. Clinical outcome was assessed with Kaplan-Meier life table estimates of local-relapse-free survival, defined as the time from treatment to local relapse (determined either clinically or radiographically) or the last follow-up; the logrank test was used to assess the significance of differences among the curves for 32 the treatment groups . One-way analysis of variance (ANOVA) with the Bonferroni correction was used to assess the significance of differences in radiation dose, procedure duration, and clinical outcome among the groups.

Materials and Methods

Surgical Navigation

I

The set of CT images is sent to the separate StealthStation surgical navigation computer workstation (Figs. 1-A and 1-B; see Appendix). The surgical instruments (e.g., pointer and Kirschner wire drill guide) to be tracked or navigated are registered to the StealthStation workstation. The workstation utilizes the three-dimensional data set collected, matches this with the surgical instruments, and displays both the bone and the instrument relative to each other on a screen separate from the O-Arm, thus creating a virtual image on the workstation that constantly updates in real time (Fig. 3).

nstitutional review board approval was obtained for this study. All procedures were performed under aseptic conditions in either the operating room or radiology department CT suite by either an orthopaedic surgeon or radiologist. Using case control methods, we analyzed sixty-six cases of osteoid osteoma treated with RF ablation from January 2000 to December 2012. Patients were categorized into three treatment groups, depending on the localization method: (1) intraoperative cone-beam CT three-dimensional imaging (O-Arm; Medtronic, Minneapolis, Minnesota) with surgical navigation (StealthStation S7;

Group 1 Setup, O-Arm Scan, and Image Analysis After induction of general anesthesia, the patient was placed on a radiolucent, fluoroscopy-capable operating table. The extremity was prepared and draped in a sterile manner. Percutaneous pins were used to affix an optical tracking array to the target bone at a site adjacent to the nidus. The O-Arm was rotated and closed around the target area of the bone. An intraoperative CT scan was performed with use of either a high or low-definition image sequence as determined by the surgeon (Figs. 1-A and 1-B-). The O-Arm has a fixed-width field of view. The imaging results are manipulated by the surgeon with use of a sterile, wireless remote mouse pointing device, and reconstructions in the axial, sagittal, and coronal plane are displayed on a separate, three-dimensional workstation (Fig. 2). The surgeon reviews all images and determines the approach and placement of the probe.

Fig. 1

Figs. 1-A and 1-B The intraoperative setup. Fig. 1-A The O-Arm is on the left side and the StealthStation with overhead infrared camera is on the right. The dashed red line indicates the wireless transfer of CT data from the O-Arm to the infrared camera of the StealthStation. Fig. 1-B The red oval outlines the O-Arm’s wireless data transmission sites to the surgical navigation StealthStation unit. These sites must not be obstructed by any overlying opaque material.


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Fig. 2

Intraoperative O-Arm screenshot. The three-dimensional imaging shows an osteoid osteoma in the tibial diaphysis with the probe in place. The pointer was used to determine the correct placement of the RF ablation probe (Cool-tip RF ablation system, Covidien, Mansfield, Massachusetts). Intraoperative virtual imaging using the navigation workstation

was utilized to identify the correct level in the bone. A skin stab incision was made and was dilated with a hemostat, creating a track down to the bone. The pointer was placed directly against the target site and was then exchanged for

Fig. 3

StealthStation screenshot. The three-dimensional imaging shows an osteoid osteoma in the tibial metaphysis and the position of the pointer.


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TABLE I Patient Demographics Group 1

Group 2

Group 3

19:4

4:3

23:13

Mean age (range) (yr)

19 (7-47)

20 (11-34)

19 (7-52)

Anatomical distribution (no. [%]) Periarticular Axial Long bone diaphyseal

5 (22) 1 (4) 17 (74)

1 (14) 1 (14) 5 (71)

8 (22) 2 (6) 26 (72)

Laterality (no. [%]) Left Right

10 (43) 13 (57)

5 (71) 2 (29)

17 (47) 18 (50)

1 (20) 1 (20) 1 (20) 1 (20) 0 (0) 1 (20) 0 (0)

0 (0) 0 (0) 0 (0) 0 (0) 1 (100) 0 (0) 0 (0)

1 (12) 0 (0) 5 (62) 1 (12) 0 (0) 0 (0) 1 (12)

0 (0) 1 (100) 0 (0) 0 (0)

0 (0) 0 (0) 1 (100) 0 (0)

1 (50) 0 (0) 0 (0) 1 (50)

6 (35) 2 (12) 2 (12) 7 (41)

2 (40) 1 (20) 0 (0) 2 (40)

10 (38) 2 (8) 4 (15) 10 (38)

Sex (M:F)

Bone distribution (no. [%]) Periarticular Calcaneus Costovertebral junction T10 Femoral neck Femoral head Great toe distal phalanx Talus Tibia Axial C6 Ilium L2 lamina Scapula Long bone diaphyseal Femur Fibula Humerus Tibia

the 0.0625-in (1.59-mm) soft-tissue sleeve and Kirschner wire insertion guide. The guide was navigated in real time on the virtual image until it was positioned directly over the target at the appropriate angle of insertion into the nidus. A 0.0625-in (1.59-mm) Kirschner wire was drilled into the central portion of the nidus while keeping the guide targeted on the nidus. A second wire could be used if the nidus was larger than 2 cm. (A 1-cm probe 33,34 tip typically has a 2-cm diameter of necrosis in cortical bone .) Another CT scan was performed to confirm the Kirschner wire placement. The three-dimensional images were reconstructed on the separate workstation, positioning of the Kirschner wire in the center of the nidus was confirmed, and a soft-tissue sleeve was used to exchange the Kirschner wire for the 1-cm RF probe tip. The 1-cm probe was placed at the appropriate depth within the lesion, and another CT scan was performed to confirm the probe placement.

Group 2 The setup and O-Arm scan were similar to those for group 1; however, no surgical navigation was utilized. Instead, the Kirschner wire insertion site was approximated with use of a radiopaque grid marker taped to the skin prior to the scan. The Kirschner wire was inserted, and an O-Arm scan was performed to check the position of the wire relative to the nidus. Adjustments, based on the surgeon’s estimation, were made as needed, and a new O-Arm scan was performed after each adjustment until the Kirschner wire was centered in the nidus. Depending on the accuracy of the initial Kirschner wire placement and subsequent adjustments, multiple O-Arm scans could be necessary. Once the Kirschner wire was in the nidus, it was exchanged for the RF ablation probe, another O-Arm scan was done to confirm its placement, and the RF ablation was performed as described above.

Group 3 RF Ablation The RF ablation probe tip was heated to 90°C. The temperature was monitored, and the power from the RF generator was adjusted as needed (usually between 2 and 7 W) to maintain a steady 90°C. After six minutes of ablation, the probe was withdrawn, the skin site was inspected for any burn injury, and the tracking device and half-pins were removed. The punctate incision sites were closed with Steri-Strips (3M, St. Paul, Minnesota), or with a suture if needed, and a bandage was applied. Identical RF ablation probe systems and settings (2 to 7 W at 90°C for six minutes) were used in the other two groups as well.

The patient was placed under general anesthesia in the radiology department diagnostic CTscanner suite used for interventional procedures. As in group 2, a radiopaque grid was applied to the skin over the target area and a CT scan to assess position was performed both prior to the initial wire placement and after each adjustment. The accuracy of the initial wire placement was assessed with a limited CT scan using a narrow field of view, with the width including only the necessary area of interest, thereby minimizing radiation exposure to the adjacent tissue. Adjustments to reposition the wire were made as needed. In each adjustment by the physician, the correct wire placement was estimated using


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TABLE II Dosimetry According to Treatment Group DLP* (mGy-cm) Group

Mean

1

446.6


lost to follow-up. The mean procedure duration was eighty minutes in group 1, seventy-five minutes in group 2, and eightyfour minutes in group 3; the difference among the groups was not significant.

The fellowship training of one of the authors (S.M.N.) was partially supported by the Orthopaedic Research and Education Foundation.

Radiation Dosimetry The radiation dose averaged 446.62, 379.78, and 1058.83 mGycm in groups 1, 2, and 3, respectively. The differences between groups 1 and 3 and between groups 2 and 3 were significant (p < 0.05) but the difference between groups 1 and 2 (the two intraoperative three-dimensional imaging groups) was not (Tables II and III). A twofold reduction in the mean radiation dose resulted when intraoperative three-dimensional imaging was used instead of conventional CT scanning (p < 0.05). A subgroup analysis according to anatomical location did not have sufficient power to demonstrate any significant differences in the radiation dose, as the subgroup sizes were small (e.g., only one patient in group 1 and one in group 2 had an osteoid osteoma in an axial location) (Table III).

Results roups 1, 2, and 3 included twenty-three, seven, and thirtysix patients, respectively (Table I). The mean age was nineteen years in group 1, twenty years in group 2, and nineteen years in group 3. The mean follow-up duration was fifty-three months overall and sixteen, forty-nine, and seventy-nine months in groups 1, 2, and 3, respectively. Three patients in group 3 were

Clinical Outcome Fifty-eight (92%) of sixty-three patients achieved excellent pain relief, being asymptomatic at their last follow-up visit. Three patients in group 3 and two in group 1 had a relapse. Local-relapse-free survival at three years was 84.7% (95% confidence interval [CI], 64.5% to 100%) in group 1, 100% (95% CI, 100% to 100%) in group 2, and 90.7% (95% CI, 80.7% to 100%) in group 3 (Fig. 4).

2

379.8†

3

1058.8‡

*DLP = dose-length product. †P = 1.000 vs. group 1. ‡P = 0.002 vs. group 1 and p = 0.032 vs. group 2.

the prior wire position as a landmark. After additional CT scans were performed to verify final placement of the probe in the nidus, the RF ablation was performed as described above.

Source of Funding

G

Fig. 4

Kaplan-Meier survival analysis of local-relapse-free survival in the three treatment groups.


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TABLE III Dosimetry According to Anatomical Location and Treatment Group

Group 1

2

3

Mean DLP* (mGy-cm)

No.

Periarticular

443.3

5

Axial

450.2

1

Long bone diaphyseal

447.3

17

Periarticular

254.1

1

Axial

450.2

1


390.8

5

Anatomical Location

Periarticular

930.1

8

Axial

1631.5

2


1052.3

18

*DLP = dose-length product.

Procedure Details and Complications Overall, fifty-two (79%) of the procedures required a single probe for the RF ablation, thirteen (20%) required two probes, and one (1%) required three probes (see Appendix). One patient from group 3 subsequently developed an infection that required irrigation and debridement and skin grafting. Discussion adiation exposure resulting from CT-guided RF ablation of osteoid osteoma is a safety concern, especially with the increased usage of such CT guidance. CT scanning is estimated to account for approximately 49% of the United States population’s collective radiation exposure from medical imaging23. Osteoid osteoma is most common in the pediatric age group, for whom radiation exposure concerns are of greater importance than for adults. Indeed, 56% of the patients in the present series were eighteen years old or younger. Children are more sensitive than adults are to the effects of ionizing radiation, by a factor of three at up to ten years of age22,24,35. The greater sensitivity of children to radiation is due to the presence of more dividing and differentiating cells as well as to the much longer remaining lifetime that children have in which to manifest the effects of radiation exposure22,24,26. Intraoperative three-dimensional imaging results in less radiation exposure compared with conventional CT scans, and new techniques using intraoperative three-dimensional imaging have started to emerge. However, to our knowledge, no studies involving RF ablation of osteoid osteoma have compared the radiation exposure from conventional CTscanning with that from intraoperative three-dimensional imaging. Many authors have described the use of intraoperative cone-beam CT scanning with navigation for excision of an osteoid osteoma. Okada et al. recently described treating an osteoid osteoma in the scapula using a three-dimensional fluoroscopic navigation system36. Rajasekaran et al. reported use of intraoperative Siremobil Iso-C 3D C-arm three-dimensional navigation (Siemens Medical Solutions, Erlangen, Germany) in

R


excision of spinal osteoid osteomas in four patients. They suggested that intraoperative Iso-C three-dimensional navigation helped accurately localize and guide complete excision of spinal osteoid osteomas through a minimally invasive approach without compromising spinal stability37. The role of intraoperative three-dimensional C-arm-based navigation in percutaneous excision of osteoid osteoma of long bones in children has been described. In a study of five patients (mean follow-up, 3.2 years), the benefits of three-dimensional C-arm-based navigation were excellent localization, percutaneous excision, and intraoperative confirmation of adequate excision27. Kendoff et al. demonstrated the use of Siremobil Iso-C 3D C-arm-based navigation for percutaneous resection of osteoid osteomas in three patients38. Wang et al. studied the precision of osteoid osteoma resection using a computer navigation system in twenty-six patients (mean followup, 20.6 months)39. They found that intraoperative Iso-C threedimensional navigation was more useful for diaphyseal osteoid osteomas. To our knowledge, the present study is the first and largest to describe the use of navigation and intraoperative threedimensional imaging for RF ablation of osteoid osteoma and provides new information comparing the radiation exposure from intraoperative three-dimensional imaging with that from conventional CT scanning in this treatment. Many disadvantages associated with a radiography suitebased technique compared with an intraoperative technique have been described, such as poorer sterility, greater radiation exposure, poorer accuracy, and increased intraoperative and postoperative complications40,41. Use of conventional CT scanning for targeting osteoid osteoma and other bone lesions is based on in-plane trajectory planning on axial CT slices and freehand bone drilling under stepwise control imaging to confirm the needle track3,42. Freehand trajectory alignment and bone drilling are done without the benefit of real-time imaging and require a high level of skill to avoid positional and angular deviations. Although newer CT fluoroscopy units are capable of performing real-time cross-sectional imaging, radiation exposure remains a concern as radiation is emitted whenever the realtime imaging is activated, similar to the situation when a standard fluoroscopy machine is used. Missing the center of a nidus, which is usually smaller than 15 mm, may lead to inadequate targeting and thus to relapse. Intraoperative three-dimensional imaging with navigation facilitates the use of trajectories with arbitrary angulations and orientations; thus, out-of-plane targeting relative to conventional CT guidance is possible8. The navigation probe, the pointer, or a tracked bone drill can be guided along the plane with use of a real-time virtual image displayed on a surgical navigation screen43. This is especially useful in axial locations that are deep or difficult to palpate (see Appendix). Intraoperative three-dimensional imaging simultaneous with navigation overcomes the problem of time separation between CT imaging and insertion of the Kirschner wire or probe, and it is more accurate than using paired points and surface-matching techniques44. Our data did not show a significant decrease in the radiation dose when surgical navigation was added to O-Arm use compared with O-Arm use alone. There are two possible reasons


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for this lack of an observed difference. First, the small number of patients treated with the O-Arm alone (group 2) provided insufficient power for an analysis at the p = 0.05 level. The magnitude of the reduction in the radiation dose in group 1 would have been due mostly to use of the O-Arm’s cone-beam CT technology and to a lesser extent to surgical navigation. A prospective randomized trial of a larger group of patients would be required to show a reduction in exposure associated with the use of surgical navigation; however, such a trial would be extremely difficult if not impossible to conduct, as surgical navigation has greatly facilitated the surgeon’s confidence and accuracy in placement of the RF ablation probe. Second, we noted a learning curve when using navigation. We performed only seven procedures using O-Arm intraoperative CT without navigation compared with twenty-three such procedures with navigation. The radiation dose during the procedures with navigation decreased sequentially as we have gained experience in using navigation. Despite our inability to demonstrate a statistically significant reduction in the radiation dose between groups 1 and 2 because of the small numbers of patients, we believe that the benefits of using surgical navigation in RF ablation of osteoid osteoma will parallel those of using this technology in spinal pedicle screw placement; it has been the experience of spinal surgeons that radiation exposure during such procedures was reduced and accuracy was enhanced45. According to the ALARA (as low as reasonably achievable) principle for ionizing radiation, the kV and mAs instrument settings, the area of interest, and the number of control CT scans should be minimized in CT-guided interventions46. Internationally, more than sixtyseven professional societies have joined together as a coalition, the Alliance for Radiation Safety in Pediatric Imaging, to promote the importance of adjusting the radiation dose when imaging children26. The present study has shown that the radiation dose was significantly lower in the intraoperative three-dimensional imaging groups (groups 1 and 2) compared with the group that used the conventional CT-based technique (group 3). As discussed by Zhang et al., several factors may have caused the dose difference between the O-Arm in three-dimensional scan acquisition mode and the CT scanner31. First, the source-toisocenter distance differs between the two imaging systems; the longer distance in the O-Arm system would result in a radiation dose reduction of approximately 29%. Second, the fan-beam angle of the O-Arm is approximately 20°, whereas that of the CT system is approximately 45°. The smaller fan-beam angle in the O-Arm system compared with the CT scanner would also lead to a lower radiation dose. Third, the beam quality differs between the two systems; the CT scanner has a harder beam,


resulting in higher radiation dosages. Lastly, the effect of overbeaming from the multiple axial scans performed by the CT scanner results in a higher dose than that from a single rotation of the wider beam of the O-Arm31. This study has some limitations. First, a case-control comparison method potentially has greater bias than a method using a randomized sample. It is unlikely, however, that a randomized trial would have been feasible for this comparison study, given the rarity of the tumor and the differences between radiologist and surgeon-based procedures. Second, additional morbidity results from surgical navigation compared with the non-navigated techniques because the need for attachment of a tracking array to the target bone invariably involves another stab incision for percutaneous placement of an anchoring pin in the bone. However, this can usually be placed in a location that minimizes the risk of postoperative infection or fracture, and we had no complications in the group in which navigation was used (group 1). Finally, a cost analysis was not performed, although the use of navigation adds cost. In conclusion, both intraoperative cone-beam CT threedimensional imaging and conventional CT targeting techniques were equally efficacious clinically for the treatment of osteoid osteoma using RF ablation. However, the use of intraoperative three-dimensional (O-Arm) imaging was associated with a significantly lower radiation dose, approximately one-half that of the radiology suite-based CT technique. Appendix A table showing the number of probes used per patient in each group and additional figures showing intraoperative use of the O-Arm and StealthStation are available with the online version of this article as a data supplement at jbjs.org. n

Edward Y. Cheng, MD Sameer M. Naranje, MBBS, MRCS(Glasgow) Department of Orthopaedic Surgery, University of Minnesota, 2512 South 7th Street, R200, Minneapolis, MN 55454. E-mail address for E.Y. Cheng: [email protected]. E-mail address for S.M. Naranje: [email protected] E. Russell Ritenour, PhD Department of Diagnostic Radiology, University of Minnesota, MMC 292, Room B-275 Mayo, 420 Delaware Street S.E., Minneapolis, MN 55455. E-mail address: [email protected]

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Percutaneous radiofrequency ablation of spinal osteoid osteoma under CT guidance.

CT-guided radiofrequency ablation of osteoid osteoma using a novel battery-powered drill.

Evaluation of accuracy and precision of CT-guidance in Radiofrequency Ablation for osteoid osteoma in 86 patients.

Case report: late subtrochanteric fracture post radiofrequency ablation of osteoid osteoma.

Osteoid osteoma - radiofrequency ablation treatment guided by computed tomography: a case series.

Osteoid osteoma: CT-guided percutaneous treatment.

Arthroscopic ablation of osteoid osteoma in the wrist.

Effectiveness of Computed Tomography Guided Percutaneous Radiofrequency Ablation Therapy for Osteoid Osteoma: Initial Results and Review of the Literature.

Conventional radiofrequency catheter ablation compared to multi-electrode ablation for atrial fibrillation.

The distribution of heat in bone during radiofrequency ablation of an ex vivo bovine model of osteoid osteoma.

Osteoid osteoma.

Ultrastructure of osteoid osteoma.

Efficacy of magnetic thermoablation using SPIO in the treatment of osteoid osteoma in a bovine model compared to radiofrequency and microwave ablation.

Intra-articular osteoid osteoma.

Scintigraphic detection of osteoid osteoma.

Multifocal osteoid osteoma of tibia.

Juxta-articular osteoid osteoma.

Prostaglandins in osteoid osteoma.

Neurological manifestations of osteoid osteoma.

Evaluation of minimally invasive laser ablation in children with osteoid osteoma.

Osteoid osteoma: diagnosis and treatment.

Treatment of chronic radiation proctopathy with radiofrequency ablation (with video).

Osteoid osteoma leading to sciatica.

[Osteoid osteoma: about a case].