HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Aschoff, A. J. Articles by Lewin, J. S. Search for Related Content PubMed PubMed Citation Articles by Aschoff, A. J. Articles by Lewin, J. S.

Femur: MR Imaging–guided Radio-frequency Ablation in a Porcine Model— Feasibility Study¹

¹ From the Departments of Radiology (A.J.A., E.M.M., C.A.P., J.L.D., J.S.L.), Pathology (S.N.E.), and Oncology (J.S.L.), University Hospitals of Cleveland/Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH 44106; Department of Diagnostic Radiology, University Hospital of Ulm, Germany (A.J.A., E.M.M.); and Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio (J.L.D.). From the 2000 RSNA scientific assembly. Received September 6, 2000; revision requested October 20; final revision received May 7, 2002; accepted May 29. Supported in part by grants from the Whitaker Foundation, American Cancer Society, National Institutes of Health (1R01 CA81431-01A1), and the German Research Foundation (DFG, As 116/1-1 and Me 1593/1-1), and by research collaborations with Siemens Medical Systems and Radionics. Address correspondence to J.S.L. (e-mail: lewin@uhrad.com).

View larger version (69K): [in a new window]   Figure 1. MR-compatible RF electrode and bone biopsy system. A = exposed tip of 17-gauge MR-compatible RF electrode. B = 11-gauge MR-compatible bone biopsy needle. After successful introduction into the bone, the trocar (C) is removed, and the canula (B) is used as a sheath for introduction of the RF electrode (A). Once the tip of the electrode is placed within the bone marrow, the sheath is withdrawn far enough to provide clearance for the 2-cm-long exposed tip (arrows) of the RF electrode. Ruler indicates centimeters.

View larger version (24K): [in a new window]   Figure 2. Line graph shows mean RF current versus time during RF ablation in 10 pig femurs. Error bars represent the SD of the mean. Note the continuous decrease in RF current during interstitial thermal therapy.

View larger version (29K): [in a new window]   Figure 3. Line graph shows mean impedance versus time during RF ablation in 10 pig femurs. Error bars represent the SD of the mean. Note the decrease in impedance in the 1st minute of ablation.

View larger version (92K): [in a new window]   Figure 4. Findings at 2 weeks after RF bone ablation in one pig femur. A, Sagittal contrast-enhanced T1-weighted MR image. B, Sagittal T2-weighted MR image. C, Sagittal STIR MR image (matrix, 123 x 256; field of view, 219 x 350 mm). D, Gross pathologic specimen. Arrows in A-D indicate necrosis, which is clearly visible in the MR images and corresponds to a sharply delineated thermal lesion on the gross specimen. The ruler on the left indicates inches. The ruler on the right indicates centimeters.

View larger version (168K): [in a new window]   Figure 5. Bilateral RF bone ablation. MR images of bilateral femurs were obtained immediately after ablation. Top row: Transverse sections through both lesions. Middle row: Sagittal views of right femur. Bottom row: Sagittal views of left femur. From left to right: contrast-enhanced T1-weighted, T2-weighted, and STIR (matrix of 123 x 256 and field of view of 219 x 350 mm) MR images. In the right femur, necrosis (arrows) is visible but not as sharply as in images obtained 2 weeks after ablation (Fig 4).

View larger version (36K): [in a new window]   Figure 6. Bar graph shows mean error of MR images in predicting the actual RF lesion size compared with gross pathologic findings in 10 pig femurs. White bars = day 0, gray bars = day 7, black bars = day 14. Error bars represent the SD of the mean. CE-T1 = contrast-enhanced T1 weighted, T2 = T2 weighted.

View larger version (154K): [in a new window]   Figure 7. Gross pathologic and histologic appearances of RF lesion in bone in one pig femur. (a) Gross pathologic specimen was obtained at 14 days after thermal coagulation. Note the sharp delineation of the lesion (arrows), which is surrounded by normal-appearing bone marrow. (b) Low-power photomicrograph. The electrode tract is to the right of this slice. The interface (arrows) between lesional and normal marrow is clearly demarcated. Metaphysis is on the lower left. (Hematoxylin-eosin stain; original magnification, x5.) (c) Photomicrograph of the interface between lesional and normal marrow. Thermally coagulated regions are sharply demarcated from the normal-appearing marrow. Postablation changes include focal hemorrhage and/or residual fat necrosis, dilation of blood vessels, and enlargement of endothelial nuclei. The marrow is severely pancytopenic, and there is replacement of the hematopoietic progenitors with a myxoid edematous stroma. Bone spicules also show reactive and involutional changes. These features are better visualized with higher magnification. (Hematoxylin-eosin stain; original magnification, x20.) (d) Photomicrograph at higher magnification clearly shows viable hematopoietic elements in the nonlesional marrow, including dilated postcapillary venules with reactive endothelial nuclei (dotted arrow), focal resorption of trabecular bone (solid arrow), and new bone formation (arrowheads). Again, note replacement of the normal marrow cells (major portion of the image) with myxoid edematous stroma. (Hematoxylin-eosin stain; original magnification, x80.)