Prostate cancer ablation with transrectal high-intensity focused ultrasound: assessment of tissue destruction with contrast-enhanced US.

PURPOSE: To assess contrast material-enhanced ultrasonographic (US) findings seen after high-intensity focused ultrasound (HIFU) ablation of prostate cancer and correlate the US findings with post-HIFU biopsy findings. MATERIALS AND METHODS: The study was ethics committee approved. Written informed consent was obtained from all patients. Twenty-eight patients referred for HIFU prostate cancer ablation underwent contrast-enhanced prostate US before treatment, gadolinium-enhanced magnetic resonance (MR) imaging and repeat contrast-enhanced US 1-3 days after treatment, and contrast-enhanced US-guided biopsy 30-45 days after treatment. The contrast-enhanced US enhancement patterns of the biopsy sites--assigned a score of S0 for no enhancement, S1 for mild and/or patchy enhancement, or S2 for marked enhancement--were compared with corresponding biopsy findings, which were assigned a score of B0 for necrosis and/or fibrosis without viable prostate gland tissue, B1 for vascularized tissue without viable gland tissue, or B2 for viable gland tissue (benign or malignant). Then, six additional patients underwent contrast-enhanced prostate US 15-30 minutes and 1 day after HIFU ablation, and the results of these two US examinations were compared. RESULTS: Contrast-enhanced US performed on days 1-3 and days 30-45 after HIFU ablation depicted a large devascularized zone with peripheral enhancing areas that were localized anteriorly in all 28 patients, posteriorly in nine, laterally in five, and at the apex in 20 patients. MR findings were concordant. At biopsy, viable gland tissue was found at nine (6.2%) of 146 S0 sites, 10 (34%) of 29 S1 sites, and 44 (60%) of 73 S2 sites. The odds ratios for finding viable tissue (score B1 or B2) at S1 and S2 sites as opposed to S0 sites were 21 (95% confidence interval [CI]: 6, 71) and 73 (95% CI: 22, 243), respectively (P < .0001). Contrast-enhanced US performed 15-30 minutes and 1 day after treatment in the six additional patients had similar findings. CONCLUSION: Contrast-enhanced US is a promising tool for distinguishing between ablated (devascularized) and viable (enhancing) tissue immediately after HIFU treatment.

Imaging of prostate cancer local recurrences: why and how?

OBJECTIVE: Because prostate cancer local recurrences can be efficiently treated by salvage therapies, it becomes critical to detect them early. METHODS: The first alert is the rise of the prostate specific antigen (PSA) level after the post-treatment nadir, which can correspond to a distant recurrence, a local recurrence or both. This so-called biochemical failure (BF) is defined as PSA level > 0.2 ng/ml after radical prostatectomy (RP) and PSA level > nadir + 2 ng/ml after radiotherapy. There is no consensual definition of BF after cryotherapy, high-intensity focused ultrasound (HIFU) ablation or brachytherapy. RESULTS: Local recurrences after RP are treated by radiotherapy, those after radiotherapy by RP, cryotherapy, brachytherapy or HIFU ablation. Recurrences after cryotherapy or HIFU ablation can be treated by a second session or radiotherapy. Recurrences after brachytherapy are difficult to treat. In patients with BF, MRI can detect local recurrences, whatever the initial treatment was. Dynamic contrast-enhanced MRI seems particularly accurate. The role of spectroscopy remains controversial. Ultrasound-based techniques are less accurate, but this may change with the advent of ultrasonic contrast media. CONCLUSION: These recent advances in imaging may improve the outcome of salvage therapies (by improving patient selection and treatment targeting) and should open the way to focal salvage treatments in the near future.

Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI.

The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies ("routine biopsies"); operator 2 obtained up to three cores per suspicious lesion on MRI ("targeted biopsies"). Seventy-seven suspicious lesions were detected on DCE images (n = 52), T2w images (n = 2) or both (n = 23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p = 0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p < 0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05-3.64) and 1.38 (95% CI 1.13-1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue.

Evaluation of T2-weighted and dynamic contrast-enhanced MRI in localizing prostate cancer before repeat biopsy.

We assessed the accuracy of T2-weighted (T2w) and dynamic contrast-enhanced (DCE) 1.5-T magnetic resonance imaging (MRI) in localizing prostate cancer before transrectal ultrasound-guided repeat biopsy. Ninety-three patients with abnormal PSA level and negative prostate biopsy underwent T2w and DCE prostate MRI using pelvic coil before repeat biopsy. T2w and DCE images were interpreted using visual criteria only. MR results were correlated with repeat biopsy findings in ten prostate sectors. Repeat biopsy found prostate cancer in 23 patients (24.7%) and 44 sectors (6.6%). At per patient analysis, the sensitivity, specificity, positive and negative predictive values were 47.8%, 44.3%, 20.4% and 79.5% for T2w imaging and 82.6%, 20%, 24.4% and 93.3% for DCE imaging. When all suspicious areas (on T2w or DCE imaging) were taken into account, a sensitivity of 82.6% and a negative predictive value of 100% could be achieved. At per sector analysis, DCE imaging was significantly less specific (83.5% vs. 89.7%, p < 0.002) than T2w imaging; it was more sensitive (52.4% vs. 32.1%), but the difference was hardly significant (p = 0.09). T2w and DCE MRI using pelvic coil and visual diagnostic criteria can guide prostate repeat biopsy, with a good sensitivity and NPV.

Transient MR elastography (t-MRE) using ultrasound radiation force: theory, safety, and initial experiments in vitro.

The purpose of our study was to assess the feasibility of using ultrasound radiation force as a safe vibration source for transient MR elastography (t-MRE). We present a theoretical framework to predict the phase shift of the complex MRE signal, the temperature elevation due to ultrasound, and safety indicators (I(SPPA), I(SPTA), MI). Next, we report wave images acquired in porcine liver samples in vitro. MR thermometry was used to estimate the temperature elevation induced by ultrasound. Finally, we discuss the implications of our results with regard to the feasibility of using radiation force for t-MRE in a clinical setting, and a specific echo-planar imaging (EPI) MRE sequence is proposed.

Radiofrequency ablation of renal tumors with an expandable multitined electrode: results, complications, and pilot evaluation of cooled pyeloperfusion for collecting system protection.

The objective of this study was to retrospectively evaluate the results of radiofrequency ablation (RFA) of renal tumors with an impedance-based system using an expandable multitined electrode. Twenty-two patients (30 tumors) were treated with RFA over a 7-year period, percutaneously (16 tumors) or intraoperatively (14 tumors). Follow-up imaging was performed at 1-3, 6, and 12 months and yearly thereafter. Twenty-seven of 30 tumors (19/22 patients) showed no residual tumor on the first imaging control. Two residual tumors were successfully ablated by a second RFA procedure. Our mean follow-up period was 35 months (range, 3-84 months). Two tumors that had been completely ablated based on imaging criteria recurred 11 and 48 months after RFA. One was treated by partial nephrectomy. The other one was not treated because the patient developed bone metastases. One patient had nephrectomy because of an RFA-induced ureteropelvic junction stricture. Nine patients (11 sessions) had a pyeloperfusion of cooled saline during RFA. None developed symptomatic complications, even though in three patients the ablation zone extended to the closest calyx (3-5 mm from the tumor). We conclude that RFA of renal tumors is promising, but serious complications to the collecting system must be taken into consideration. Prophylactic per-procedural cooling of the collecting system is feasible but needs further assessment.

Intratesticular varicocele: an easy diagnosis but unclear physiopathologic characteristics.

OBJECTIVE: Intratesticular varicocele (ITV) is an uncommon sonographic finding with controversial data concerning its prevalence and physiopathologic characteristics. The goal of this study was to determine the prevalence of ITV in a urogenital imaging department and to describe its sonographic features. METHODS: All identified cases of ITV were prospectively collected in the same imaging department. RESULTS: Intratesticular dilated veins (>2 mm) with a positive response to the Valsalva maneuver were referred to as ITV. Nine cases of ITV were detected in 8 patients (mean age, 60 years; range, 30-85 years) in a series of 1832 scrotal sonographic examinations performed over 5 years (0.4%). A history of homolateral scrotal surgery was found in 5 cases. In most cases, ITV was left sided (6/9) and located in the mediastinum testis (6/9) with associated extratesticular varicocele (8/9) and testicular hypotrophy (7/9). Five of the 7 hypotrophic testes had other causes of hypotrophy. CONCLUSIONS: Although variations do exist in the sonographic appearance of ITV, its specific sonographic and Doppler appearance should enable the radiologist to obviate further study. Intratesticular varicocele is often associated with ipsilateral testicular atrophy, but whether it is a cause or a consequence of testicular atrophy remains unclear.

Transrectal high-intensity focused ultrasound ablation of prostate cancer: effective treatment requiring accurate imaging.

Transrectal HIFU ablation has become a reasonable option for the treatment of localized prostate cancer in non-surgical patients, with 5-year disease-free survival similar to that of radiation therapy. It is also a promising salvage therapy of local recurrence after radiation therapy. These favourable results are partly due to recent improvements in prostate cancer imaging. However, further improvements are needed in patient selection, pre-operative localization of the tumor foci, assessment of the volume treated and early detection of recurrence. A better knowledge of the factors influencing the HIFU-induced tissue destruction and a better pre-operative assessment of them by imaging techniques should improve treatment outcome. Whereas prostate HIFU ablation is currently performed under transrectal ultrasound guidance, MR guidance with real-time operative monitoring of temperature will be available in the near future. If this technique will give better targeting and more uniform tissue destruction, its cost-effectiveness will have to be carefully evaluated. Finally, a recently reported synergistic effect between HIFU ablation and chemotherapy opens possibilities for treatment in high-risk or clinically advanced tumors.

Influence of perfusion on high-intensity focused ultrasound prostate ablation: a first-pass MRI study.

Our aim was to evaluate the influence of regional prostate blood flow (rPBF) on high-intensity focused ultrasound (HIFU) treatment outcome. A total of 48 patients with clinically localized prostate cancer were examined by dynamic contrast-enhanced (DCE)-MRI prior to HIFU therapy. A prostate-specific antigen (PSA) nadir threshold of 0.2 ng/ml was used to define the populations of responders and nonresponders. A dedicated tracer kinetic model, namely "monoexponential plus constant" (MPC) deconvolution, was implemented to provide quantitative estimates of rPBF. The results were compared with those obtained by semiquantitative (steepest slope, mean gradient) and quantitative (Fermi deconvolution) approaches. Of the four methods studied, quantitative rPBF obtained by MPC deconvolution proved the most sensitive to the perfusion changes encountered in this study. Furthermore, blood-flow values obtained with MPC deconvolution in the prostate and muscle (12 +/- 8 and 5 +/- 3 ml/min/100 g, respectively) were in good agreement with literature data. The mean pretreatment rPBF obtained with MPC deconvolution was significantly higher in nonresponders compared to responders (16 +/- 9 vs. 10 +/- 6 ml/min/100 g), suggesting a correlation between baseline perfusion and treatment outcome. The present work describes and validates the use of dynamic MRI to estimate rPBF in patients, which in the future may help to refine the conduct of HIFU therapy.

Prostate dynamic contrast-enhanced MRI with simple visual diagnostic criteria: is it reasonable?

UNLABELLED: The purpose of this study was to evaluate the accuracy of prostate cancer localization with simple visual diagnostic criteria using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). A total of 46 consecutive patients with biopsy-proven prostate cancer underwent prostate 1.5 T MRI with pelvic phased-array coils before prostatectomy. Besides the usual T2-weighted sequences, a 30-s DCE sequence was acquired three times after gadoterate injection. On DCE images, all early enhancing lesions of the peripheral zone were considered malignant. In the central gland, only early enhancing lesions appearing homogeneous or invading the peripheral zone were considered malignant. Three readers specified the presence of cancer in 20 prostate sectors and the location of distinct tumors. Results were compared with histology; p < 0.05 was considered significant. For localization of cancer in the sectors, DCE imaging had a significantly higher sensitivity [logistic regression, odds ratio (OR): 3.9, p < 0.0001] and a slightly but significantly lower specificity (OR: 0.57, p < 0.0001). Of the tumors >0.3 cc, 50-60% and 78-81% were correctly depicted with T2-weighted and DCE imaging, respectively. For both techniques, the depiction rate of tumors >0.3 cc was significantly influenced by the Gleason score (most Gleason

Nonmetastatic renal-cell carcinoma: is it really possible to define rational guidelines for post-treatment follow-up?

Defining rational follow-up guidelines in patients treated for cancer is important, from both a medical and an economical perspective. Renal-cell carcinoma is reputed to be unpredictable in its course and only a few, and often contradictory, follow-up guidelines exist for patients treated for nonmetastatic renal-cell carcinoma. Recent advances in tumor biology have contributed to a better understanding of this cancer and have indicated that personalized follow-up regimens, based on tumor and host molecular characteristics, might be possible in the near future.

Evaluation of color Doppler in guiding prostate biopsy after HIFU ablation.

OBJECTIVE: Transrectal ultrasound cannot accurately depict early cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. We evaluated transrectal color Doppler (CD) in guiding post-HIFU prostate biopsy. METHODS: Prostate CD-guided sextant biopsies were obtained in 82 patients who had undergone prostate HIFU ablation for cancer, 24 of whom had hormone therapy before the treatment. At the time of biopsy, a subjective CD score was given to all biopsy sites (0=no flow; 1=minimal flow; 2=suspicious flow pattern). CD findings were compared with biopsy results. RESULTS: CD was a significant predictor of biopsy findings, according to univariate and multivariate site-by-site analysis. However, only 36 of 94 sites with residual cancer had positive CD findings, and thus, negative CD findings should not preclude random biopsy. There was a significant interaction between CD diagnostic capability and a history of hormone therapy before HIFU treatment. CD was a significant and independent predictor of biopsy findings in patients who had not received hormone therapy (odds ratio: 4.4; 95%CI: 2.5-7.9; p<0.0001), but not in those who had (odds ratio: 1.3; 95%CI: 0.5-3.4; p>0.5). CONCLUSION: Biopsy taken in CD-positive sites were 4.4 times more likely to contain cancer in patients who did not receive hormone therapy. CD could not reliably depict cancer recurrence in patients with history of hormone therapy.

Prostate MR imaging at high-field strength: evolution or revolution?

As 3 T MR scanners become more available, body imaging at high field strength is becoming the subject of intensive research. However, little has been published on prostate imaging at 3 T. Will high-field imaging dramatically increase our ability to depict and stage prostate cancer? This paper will address this question by reviewing the advantages and drawbacks of body imaging at 3 T and the current limitations of prostate imaging at 1.5 T, and by detailing the preliminary results of prostate 3 T MRI. Even if slight adjustments of imaging protocols are necessary for taking into account the changes in T1 and T2 relaxation times at 3 T, tissue contrast in T2-weighted (T2w) imaging seems similar at 1.5 T and 3 T. Therefore, significant improvement in cancer depiction in T2w imaging is not expected. However, increased spatial resolution due to increased signal-to-noise ratio (SNR) may improve the detection of minimal capsular invasion. Higher field strength should provide increased spectral and spatial resolution for spectroscopic imaging, but new pulse sequences will have to be designed for overcoming field inhomogeneities and citrate J-modulation issues. Finally, dynamic contrast-enhanced MRI is the method of imaging that is the most likely to benefit from the increased SNR, with a significantly better trade-off between temporal and spatial resolution.

Can color doppler predict the uniformity of HIFU-induced prostate tissue destruction?

BACKGROUND: Tissue blood perfusion influences the results of some hyperthermia and thermotherapy procedures, but its role in the outcome of prostate cancer treatment by high-intensity focused ultrasound (HIFU) has not been evaluated yet. We evaluated preoperative prostate color Doppler as a predictor of the efficacy of HIFU treatment. METHODS: Thirty-five patients underwent pre- and post-contrast color Doppler examination of the prostate before HIFU treatment. Specific software was used to calculate, on color Doppler images, the color pixel density (CPD), and the specific flow (SF, i.e., mean velocity x CPD) in different regions of interest. Post-treatment sextant biopsies were obtained in 31 patients, 5.8 +/- 2.8 months after HIFU treatment. RESULTS: No significant correlation was found between the uniformity of HIFU-induced tissue destruction observed on control biopsies and the pre-treatment CPD/SF values in any region of interest, either before or after contrast injection. On the other hand, history of radiation therapy was significantly associated with homogeneous tissue destruction and history of hormone therapy was significantly associated with incomplete tissue destruction. CONCLUSIONS: Color Doppler cannot predict the uniformity of HIFU-induced tissue destruction. History of radiation therapy was found to be a factor of favorable prognosis and history of hormone therapy was found to be a factor of poor prognosis in our population.

Recurrent prostate cancer after external beam radiotherapy: value of contrast-enhanced dynamic MRI in localizing intraprostatic tumor--correlation with biopsy findings.

OBJECTIVES: To assess the accuracy and interobserver variability of T2-weighted (T2W) and contrast-enhanced dynamic (CE-Dyn) magnetic resonance imaging (MRI) in predicting the results of transrectal biopsy in patients with suspected recurrent prostate cancer after external beam radiotherapy. METHODS: A total of 22 patients with increasing prostate-specific antigen levels after external beam radiotherapy for prostate cancer underwent T2W and CE-Dyn MRI of the prostate. The CE-Dyn sequence (acquisition time 30 seconds) was repeated three times after the injection of gadolinium. All patients underwent subsequent transrectal biopsy. Three independent readers interpreted the MRI scans. The MRI and biopsy results were correlated in 10 prostate sectors (the sextants of the peripheral zone, the two transitional zones, and the two seminal vesicles). RESULTS: Biopsy cores were obtained in 147 prostate sectors. Of these, 63 were positive for cancer in 19 patients. On the T2W images, the three readers interpreted as positive for cancer 15, 15, and 13 of the 19 patients showing cancer at biopsy. They interpreted as negative 3, 0, and 1 of the 3 patients showing no cancer at biopsy. On CE-Dyn images, the three readers correctly classified all the patients as positive or negative for cancer. The T2W and CE-Dyn MRI findings were concordant with biopsy results in, respectively, 81 to 95 and 107 to 117 prostate sectors (P <0.001 and P <0.01 for readers 1 and 2 and was nonsignificant for reader 3). The interobserver agreement was better for CE-Dyn images (kappa = 0.63 to 0.70) than for the T2W images (kappa = 0.18 to 0.39). The MRI-calculated tumor volumes and the mean biopsy core invasion rates were significantly correlated on the CE-Dyn images for all readers. They correlated significantly on T2W images only for one reader. CONCLUSIONS: CE-Dyn MRI depicts the intraprostatic distribution of recurrent cancer after external beam radiotherapy more accurately and with less interobserver variability than T2W MRI.

[Results of transrectal focused ultrasound for the treatment of localized prostate cancer (120 patients with PSA < or + 10ng/ml]. / Résultats du traitement par ultrasons focalisés transrectaux du cancer localisé de la prostate (120 patients avec PSA < or = à 10 ng/ml).

OBJECTIVES: To evaluate the efficacy of high intensity focused ultrasound (HIFU) for the treatment of localized prostate cancer in a population of potentially curable patients. MATERIALS AND METHODS: 120 patients with clinical stage T1-T2 prostate cancer with an initial PSA < or = 10 ng/ml and not candidates for radical prostatectomy were treated by HIFU (ABLATHERM, EDAP S.A.). Clinical failure was defined by the need for adjuvant therapy (endocrine or external beam radiotherapy). Progressive disease (laboratory failure) was strictly defined by identification of residual cancer on follow-up biopsies (regardless of the PSA) or by 3 successive elevations of PSA (when follow-up biopsies were negative) with a velocity greater than 0.75 ng/ml/year. Progression-free survival rates were calculated according to the Kaplan-Meier method. Success rates stratified according to risk factors were compared by Log-rank tests. RESULTS: The patients presented the following characteristics on inclusion: mean age: 71.2 +/- 5.34 years, PSA: 5.67 +/- 2.47 ng/ml, prostatic volume: 33.6 +/- 16.5 cc, stage: T1:61, T2:59, Gleason score 2-6: 77, 7-10: 43. The mean number of HIFU session per patient was 1.5 +/- 0.7. The mean duration of catheterization was 9 days and the mean follow-up was 27 months (range: 3-96 months). Follow-up biopsies did not reveal any residual cancer in 103 patients (86%). A residual cancer was identified in 17 patients, but only 6 patients required adjuvant therapy (endocrine: n = 2, radiotherapy: n = 4), corresponding to a clinical success rate of 95%. Progression-free survival for the whole patient population was 76.9%. A significant difference (p < 0.05) was observed between patients with a Gleason score between 2 and 6 (85.4%) and patients with a Gleason score between 7 and 10 (61.3%). CONCLUSION: These results show that high intensity focused ultrasound is a treatment option achieving similar results to those of other non-surgical treatments for prostate cancer.

Characterization of time-enhancement curves of benign and malignant prostate tissue at dynamic MR imaging.

Our objectives were to determine time-enhancement curves of prostate cancer, peripheral zone, and adenoma at gadolinium-enhanced MR imaging, and to determine if a high-spatial/low-temporal dynamic imaging could be accurate in depicting prostate cancer, or if a higher temporal resolution (and a lower spatial resolution) should be favored. Thirty-nine patients with prostate cancer underwent MR imaging before radical prostatectomy by using T1- and T2-weighted axial images and a single-slice dynamic gadolinium-enhanced sequence (40 images; one image per 6 s; injection of 20 ml at 2 ml/s). After analysis of the pathologic specimens, four region-of-interest (ROI) cursors (cancer, peripheral zone, adenoma, and muscle) were retrospectively placed on dynamic images. Time-enhancement curves of the ROIs were obtained. The theoretical accuracy of a 30-s dynamic multislice MR sequence in depicting cancer within peripheral zone and adenoma (ROC curves) was calculated from these curves. On average, prostate cancer enhanced more and earlier than peripheral zone and adenoma, but there were great interindividual variations. For start delays ranging from 12 to 84 s, the areas under the ROC curves ranged from 0.602 to 0.698 for the depiction of cancer within adenoma and from 0.614 to 0.827 for the depiction of cancer within peripheral zone. The best results were obtained with a 36-s start delay. In conclusion, we found a 30-s scanning window which seems to allow a good depiction of cancer within peripheral zone. Because of largely overlapping enhancement patterns, cancer will probably not be depicted within adenoma by dynamic imaging, at least by using low temporal resolution.

Acute thrombosis of renal transplant artery: graft salvage by means of intra-arterial fibrinolysis.

BACKGROUND: Arterial thrombosis in a transplanted kidney is a serious complication that usually leads to graft loss. The purpose of our study was to evaluate intra-arterial fibrinolysis as a treatment of acute renal transplant artery thrombosis and to determine the maximum period of occlusion allowing a reasonable chance of graft salvage. METHODS AND RESULTS: Four patients underwent intra-arterial fibrinolysis for acute transplant artery thrombosis. Transplantations had been performed 29 days to 10 years before the fibrinolysis. Fibrinolysis was carried out by using recombitant tissue plasminogen activator (n=1) or urokinase (n=3). In one patient, anuric for 13 hr at admittance, fibrinolysis could not revascularize the graft artery. In a second patient, anuric for 48 hr at admittance, fibrinolysis did revascularize the graft artery, but dialysis could not be discontinued. In the two remaining patients, anuric for 19 and 20 hr at admittance, the graft artery was successfully revascularized and dialysis could be discontinued 1 week later. One of these two patients returned to dialysis 71 months later because of chronic rejection. Thirty-four months after the acute episode, the remaining patient had a patent artery and did not require dialysis. CONCLUSIONS: Fibrinolysis seems an efficient treatment that may save transplants after up to 24 hr of the arterial occlusion.

[Treatment of renal tumors with radiofrequency: preliminary results]. / Traitement des tumeurs rénales par radiofréquence: résultats préliminaires.

OBJECTIVE: To study the feasibility and the innocuity of the treatment by radiofrequency of small renal tumours. MATERIAL AND METHODS: From June 2000 to September 2001, 10 renal tumours in 6 patients were treated by radiofrequency. The mean age of the patients was 57 years. The mean tumour diameter was 20 mm. Indications for partial surgery were 3 solitary kidneys, one patient with chronic renal failure, one patient with Von Hippel Lindau disease and one patient in whom several angiomyolipomas were discovered in the right kidney. 4 patients were treated via a lumbar incision and 2 were treated percutaneously (one with ultrasound guidance and the other with computed tomography guidance). Patients were reviewed by imaging (CT and/or MRI) with injection of contrast agent to demonstrate complete devascularization of the tumour. RESULTS: Treatment lasted an average of 180 minutes. The intraoperative complication rate was 16%. The mean hospital stay was 9 days (4 days for the percutaneous route). Nine tumours (5 patients) were devascularized after a single session. One patient (treated via the percutaneous route under ultrasound guidance) showed persistence of tumour tissue (identified by CT). A second session, performed 4 months later, allowed complete devascularization of the tumour. The mean follow-up is 13 months. CONCLUSION: This study demonstrates the feasibility and safety in terms of renal function of radiofrequency treatment of small renal tumours. However further studies are necessary to precisely define the radiological criteria of tumour necrosis and to evaluate the long-term results of this method (outcome of necrotic tumour tissue, metastatic risk, cancer recurrence along the needle track in the case of a percutaneous approach). This treatment must be reserved for selected patients.