F. Cornelis

De Novo Renal Tumors Arising in Kidney Transplants: Midterm Outcome after Percutaneous Thermal Ablation

PURPOSE To retrospectively evaluate the midterm outcome of patients treated for primary renal cell carcinomas arising in kidney transplants with minimally invasive techniques. MATERIALS AND METHODS The institutional review board of each participating institution approved this retrospective study and waived informed consent. This study was HIPAA compliant. A request for cases through the European Society of Urogenital Radiology network was made to institutions for patients who fit the requirements outlined by the authors, and a prospective follow-up of recipients was performed. Twenty-four tumors were identified that developed in the renal allograft of 20 patients from 11 institutions who were treated with radiofrequency ablation (n = 19) or cryoablation (n = 5) between 2003 and 2010. Maximal diameter of masses was 6-40 mm (median, 19.5 mm). Twenty masses were solid, and four were type 4 cystic masses. Preablation biopsy was performed for solid tumors only. All images and biologic and biopsy reports were retrospectively reviewed. Significant differences were determined by using a paired t test before and after ablation. RESULTS Mean follow-up was 27.9 months (range, 7-71 months). Histopathologic examination revealed papillary carcinoma in 17 patients and clear cell carcinoma in three. Tumors were successfully treated with ultrasonographic guidance in six patients, with computed tomographic guidance in 10 patients, and with both in four patients. One case of infection of the tumor site and one case of transitory genitofemoral nerve injury were the only reported complications. No significant change of renal function was noted. Subsequent imaging follow-up did not reveal any case of recurrence in the ablative site. CONCLUSION Percutaneous thermal ablation of renal tumors occurring in renal grafts is effective, with low morbidity. .

Embolization of Polycystic Kidneys as an Alternative to Nephrectomy Before Renal Transplantation: A Pilot Study

In autosomal polycystic kidney disease, nephrectomy is required before transplantation if kidney volume is excessive. We evaluated the effectiveness of transcatheter arterial embolization (TAE) to obtain sufficient volume reduction for graft implantation. From March 2007 to December 2009, 25 patients with kidneys descending below the iliac crest had unilateral renal TAE associated with a postembolization syndrome protocol. Volume reduction was evaluated by CT before, 3, and 6 months after embolization. The strategy was considered a success if the temporary contraindication for renal transplantation could be withdrawn within 6 months after TAE. TAE was well tolerated and the objective was reached in 21 patients. The temporary contraindication for transplantation was withdrawn within 3 months after TAE in 9 patients and within 6 months in 12 additional patients. The mean reduction in volume was 42% at 3 months (p = 0.01) and 54% at 6 months (p = 0.001). One patient required a cyst sclerosis to reach the objective. The absence of sufficient volume reduction was due to an excessive basal renal volume, a missed accessory artery and/or renal artery revascularization. Embolization of enlarged polycystic kidneys appears to be an advantageous alternative to nephrectomy before renal transplantation.

Multiparametric magnetic resonance imaging for the differentiation of low and high grade clear cell renal carcinoma

AbstractPurposeTo retrospectively evaluate the ability of magnetic resonance (MR) imaging to differentiate low from high Fuhrman grade renal cell carcinoma (RCC).Materials and methodsMR images from 80 consecutive pathologically proven RCC (57 clear cell, 16 papillary and 7 chromophobe) were evaluated. Double-echo chemical shift, dynamic contrast-enhanced T1- and T2-weighted images and apparent diffusion coefficient (ADC) maps were reviewed independently. Signal intensity index (SII), tumour-to-spleen SI ratio (TSR), ADC ratio, wash-in (WiI) and wash-out indices (WoI) between different phases were calculated and compared to pathological grade and size. The Fuhrman scoring system was used. Low grade (score ≤2) and high grade (score ≥3) tumours were compared using univariate and multivariate analyses.ResultsNo associations between grade and imaging factors were found for papillary and chromophobe RCCs. For clear cell RCCs, there was a significant association between the grade and parenchymal WiI (WiI2) (P = 0.02) or ADCr (P = 0.03). A significant association between tumour grade and size (P = 0.01), WiI2 (P = 0.02) and ADCr (P = 0.05) remained in multivariate analysis.ConclusionsMultiparametric MRI can be used to accurately differentiate low Fuhrman grade clear cell RCC from high grade. High Fuhrman grade (≥3) RCCs were larger, had lower parenchymal wash-in indices and lower ADC ratios than low grade.Key Points• Fuhrman grade of clear cell RCC can be differentiated with multiparametric MR imaging. • Fuhrman grade significantly differed for size, parenchymal wash-in index and ADC ratio. • No significant associations were found for papillary and chromophobe renal cell carcinoma.

Real-time Contrast-enhanced Transrectal US-guided Prostate Biopsy: Diagnostic Accuracy in Men with Previously Negative Biopsy Results and Positive MR Imaging Findings

PURPOSE To retrospectively evaluate diagnostic accuracy of real-time contrast material-enhanced (CE) ultrasonography (US) transrectal US-guided biopsies in patients with persistently elevated prostate-specific antigen (PSA) levels, previous negative systematic transrectal US-guided biopsy results, and positive prostate multiparametric magnetic resonance (MR) findings. MATERIALS AND METHODS Institutional review board approval was obtained for this retrospective study. Informed consent was waived. From 2007 to 2011, 178 patients with increased PSA levels (mean, 10.7 ng/mL [10.7 μg/L]), previous negative findings of random biopsies, and targets depicted at multiparametric MR imaging underwent transrectal US-guided prostate biopsies after injection of sulfur hexafluoride microbubbles. CE US-targeted biopsies were performed systematically in cancer-suggestive regions, followed by random acquisition of 12 nontargeted cores in all other regions. Diagnostic accuracy of CE US-targeted biopsies was measured with sensitivity, specificity, and positive and negative predictive values. Fisher exact and Mann-Whitney U tests were used to compare subgroups of patients. Potential predictive variables were examined with a logistic regression model. RESULTS CE US findings were positive in a first group of 158 patients and negative in a second group of 20 patients. Prostate carcinoma (PCa) was detected in 75 patients in the first group (47.5%) and in eight of the second group (40.0%). Overall cancer detection rate was 46.6% (83 of 178). In the first group, PCa was detected with targeted biopsies alone in 18 patients (24%), with nontargeted biopsies alone in 23 (30.7%), and with both in 34 (45.3%). Mean number of CE US-targeted cores per cancer-suggestive region was 2.2. CE US-targeted biopsies had a positive overall detection rate of 30.9%, while it was 6.9% for 12-core nontargeted biopsies (P < .001). PSA level and Gleason score were associated with positivity of CE US-targeted biopsies (P = .031 and P = .015, respectively). CONCLUSION Real-time CE US-targeted transrectal US biopsy offers excellent sensitivity for PCa detection in men with previous negative biopsy results and positive findings at multiparametric MR imaging. It may be combined with conventional random biopsies to increase specificity.

Radiologically guided percutaneous cryotherapy for soft tissue tumours: A promising treatment

Studies of percutaneous cryotherapy in the treatment of benign or malignant soft tissue tumours are rare and mainly involve small populations. Nevertheless, results show cryotherapys potential in terms of local control of tumours, analgesic efficacy, reduced intra- and postoperative complications, and reduction in the length of convalescence after the procedure. The objective of this update is to set out the short-term prospects for this technique in the treatment of soft tissue tumours, so that it may be more widely offered in these indications.

Percutaneous Cryoablation of Symptomatic Localized Venous Malformations: Preliminary Short-term Results

Short-term outcomes after percutaneous image-guided cryoablation of symptomatic venous malformations in four consecutive patients (mean age, 42.5 y) are reported. Two patients had local recurrences after previous treatment. Mean preoperative pain was estimated on a visual analog scale at 5 (range, 3-7). Cryoablation was performed in a single session under general anesthesia. Postoperative pain and superficial edema disappeared within 2 weeks. No pain was subsequently reported, and magnetic resonance imaging demonstrated a significant volume decrease at 3 months (75%; P = .01) and at 6 months (95%; P = .01). Percutaneous cryoablation shows promising local control in patients with symptomatic venous malformations.

Combined Late Gadolinium- Enhanced and Double-Echo Chemical-Shift MRI Help to Differentiate Renal Oncocytomas With High Central T2 Signal Intensity From Renal Cell Carcinomas

OBJECTIVE The purpose of our study was to evaluate the combination of dynamic contrast-enhanced T1-weighted and double-echo gradient-echo MR imaging to distinguish renal oncocytoma with high T2 signal intensity centrally from renal cell carcinoma (RCC). MATERIALS AND METHODS Between 2006 and 2011, 63 renal tumors (59 patients) presenting with a high signal intensity (SI) central area on T2-weighted sequences were imaged with dynamic contrast-enhanced sequences, including phases later than 5 minutes after contrast injection, and double-echo chemical-shift sequences were selected from our institutional database. Two experienced radiologists visually assessed presence and distribution of signal enhancement of central areas after injection and measured SI changes on opposed-phase images for calculation of the SI index and tumor-to-spleen ratio. Cutoff values were derived from the receiver operating characteristic (ROC) curve. RESULTS There were 19 oncocytomas (16 patients), 43 RCCs (42 patients), and one leiomyoma. Complete late enhancement of the central area was observed in 14 oncocytomas (74%) and in five RCCs (12%) (p = 0.05). The combination of complete enhancement and SI index lower than 2% (p = 0.02) or tumor-to-spleen ratio higher than -6% (p = 0.001) provided sensitivity of 36% and 55%, specificity of 95% and 97%, positive predictive value of 67% and 86%, and negative predictive value of 84% and 88%, respectively, for diagnosis of oncocytomas. CONCLUSION Absence of central area SI inversion or presence of a signal drop on chemical-shift imaging may rule out the diagnosis of oncocytoma.

Double-echo gradient chemical shift MR imaging fails to differentiate minimal fat renal angiomyolipomas from other homogeneous solid renal tumors.

OBJECTIVES The purpose of this retrospective study was to evaluate the diagnostic performance of double-echo gradient chemical shift (GRE) magnetic resonance (MR) imaging for the differentiation of angiomyolipomas with minimal fat (mfAML) from other homogeneous solid renal tumors. METHODS Between 2005 and 2010 in two institutions, all histologically proven homogenous solid renal tumors imaged with computed tomography and MR imaging, including GRE sequences, have been retrospectively selected. A total of 118 patients (mean age: 61 years; range: 20-87) with 119 tumors were included. Two readers measured independently the signal intensity (SI) on GRE images and calculated SI index (SII) and tumor-to-spleen ratio (TSR) on in-phase and opposed-phase images. Intra- and interreader agreement was obtained. Cut-off values were derived from the receiver operating characteristic (ROC) curve analysis. RESULTS Twelve mfAMLs in 11 patients were identified (mean size: 2.8cm; range: 1.2-3.5), and 107 non-AML tumors (3.2cm; 1-7.8) in 107 patients. The intraobserver reproducibility of SII and TSR was excellent with an intraclass correlation coefficient equal to 0.99 [0.98-0.99]. The coefficient of correlation between the readers was 0.99. The mean values of TSR for mfAMLs and non-mfAMLs were -7.0±22.8 versus -8.2±21.2 for reader 1 and -6.7±22.8 versus -8.4±20.9 for reader 2 respectively. No significant difference was noticed between the two groups for SII (p=0.98) and TSR (p=0.86). Only 1 out of 12 mfAMLs and 11 of 107 non-AML tumors presented with a TSR inferior to -30% (p=0.83). CONCLUSION In a routine practice, GRE sequences cannot be a confident tool to differentiate renal mfAMLs from other homogeneous solid renal tumors.

Is Multiparametric MRI Useful for Differentiating Oncocytomas From Chromophobe Renal Cell Carcinomas

OBJECTIVE The purpose of this study was to retrospectively evaluate the diagnostic accuracy of multiparametric MRI to differentiate oncocytoma from chromophobe renal cell carcinoma (RCC). MATERIALS AND METHODS In this retrospective study, 26 histologically confirmed oncocytomas and 16 chromophobe RCCs that underwent full MRI examination were identified in 42 patients (25 men and 17 women) over a 6-year period. Demographic data were recorded. Double-echo chemical-shift, dynamic contrast-enhanced T1- and T2-weighted images, and apparent diffusion coefficient (ADC) maps were reviewed independently by two radiologists blinded to pathologic results. Signal-intensity index (SII), tumor-to-spleen signal-intensity ratio, ADC ratio, three wash-in indexes, and two washout indexes were calculated and compared using univariate and ROC analyses. Sensitivity and specificity analyses were performed to calculate diagnostic accuracy. RESULTS All carcinomas and nine oncocytomas were resected; the remaining 17 oncocytomas were biopsied. Patient age (for oncocytomas: mean, 68.2 years; range, 43-84 years; for RCCs: mean, 60.8 years; range, 20-79 years) and tumor size (for oncocytomas: mean, 35.5 mm; range, 12-98 mm; for RCCs: mean, 37.2 mm; range, 9-101 mm) did not differ significantly across groups (p = 0.132 and 0.265, respectively). Good interobserver agreement was observed for all measurements but four. Oncocytomas presented significantly higher ADC (p = 0.002) and faster enhancement (p = 0.007-0.012) but lower SII (p = 0.03) than carcinomas. This combination provided sensitivity of 92.3% (24/26), specificity of 93.8% (15/16), and accuracy of 92.9% (39/42) for the detection of oncocytomas. CONCLUSION Multiparametric MRI helps to accurately differentiate oncocytomas from chromophobe RCCs with high sensitivity and specificity.

18F-FDG PET/CT Is an Immediate Imaging Biomarker of Treatment Success After Liver Metastasis Ablation

The rationale of this study was to examine whether 18F-FDG PET/CT and contrast-enhanced CT performed immediately after percutaneous ablation of liver metastases are predictors of local treatment failure at 1 y. Methods: This Health Insurance Portability and Accountability Act–compliant, Institutional Review Board–approved retrospective study reviewed 25 PET/CT-guided thermal ablations performed from September 2011 to March 2013 on 21 patients (11 women and 10 men; mean age, 56.8 y; range, 35–79 y) for the treatment of liver metastases (colorectal, n = 23; breast, n = 1; and sarcoma, n = 1). One to 3 tumors (mean size, 2.3 cm; range, 0.7–4.6 cm; mean SUVmax, 22.7; range, 9.5–77.1) were ablated using radiofrequency (n = 16) or microwave (n = 9) energy in a single session. Immediate-postablation enhanced CT and PET/CT scans were qualitatively evaluated by 2 reviewers independently, and the results were compared with clinical and imaging outcome at 1 y. The PET/CT scans were also analyzed to determine tissue radioactivity concentration (TRC) from 3-dimensional regions of interest in the ablation zone, the margin, and the surrounding normal liver to calculate a TRC ratio, which was then compared with outcome at 1 y. Receiver operating characteristics (ROC) were used, and the maximal-accuracy threshold in predicting recurrence was calculated. Results: Eleven (44%) of the 25 tumors recurred within 1 y. Enhanced CT did not significantly correlate with recurrence (P = 0.288). Accuracy was 64% (16/25), and the area under the ROC curve was 0.601 (95% confidence interval [95% CI], 0.387–0.789). The accuracy of the qualitative analysis of 18F-FDG PET was 92% (23/25) (P < 0.001), and the area under the ROC curve was 0.929 (95% CI, 0.740–0.990). The mean TRC ratio was 40.6 in the recurrence group (SD, 9.2; range, 29.3–53.9) and 15.9 in the group without recurrence (SD, 7.3; range, 3–27.3). A TRC ratio of 28.3 predicted recurrence at 1 y with 100% accuracy (25/25) (P < 0.001), and the area under the ROC curve was 1 (95% CI, 0.863–1). Conclusion: Immediate PET/CT accurately predicts the success of liver metastasis ablation at 1 y and is superior to immediate enhanced CT.