Differentiation of renal masses with multi-parametric MRI: the de Silva St George classification scheme.

PURPOSE: To develop a system for multi-parametric MRI to differentiate benign from malignant solid renal masses and assess its accuracy compared to the gold standard of histopathological diagnosis. METHODS: This is a retrospective analysis of patients who underwent 3 Tesla mpMRI for further assessment of small renal tumours with specific scanning and reporting protocol incorporating T2 HASTE signal intensity, contrast enhancement ratios, apparent diffusion coefficient and presence of microscopic/macroscopic fat. All MRIs were reported prior to comparison with histopathologic diagnosis and a reporting scheme was developed. 2 × 2 contingency table analysis (sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV)), Fisher Exact test were used to assess the association between suspicion of malignancy on mpMRI and histopathology, and descriptive statistics were performed. RESULTS: 67 patients were included over a 5-year period with a total of 75 renal masses. 70 masses were confirmed on histopathology (five had pathognomonic findings for angiomyolipomas; biopsy was therefore considered unethical, so these were included without histopathology). Three patients were excluded due to a non-diagnostic result, non-standardised imaging and one found to be an organising haematoma rather than a mass. Therefore 72 cases were included in analysis (in 64 patients, with seven patients having multiple tumours). Unless otherwise specified, all further statistics refer to individual tumours rather than patients. 52 (72.2%) were deemed 'suspicious or malignant' and 20 (27.8%) were deemed 'benign' on mpMRI. 51 cases (70.8%) had renal cell carcinoma confirmed. The sensitivity, NPV, specificity and PPV for MRI for detecting malignancy were 96.1%, 90%, 85.7% and 94.2% respectively, Fisher's exact test demonstrated p < 0.0001 for the association between suspicion of malignancy on MRI and histopathology. CONCLUSION: The de Silva St George classification scheme performed well in differentiating benign from malignant solid renal masses, and may be useful in predicting the likelihood of malignancy to determine the need for biopsy/excision. Further validation is required before this reporting system can  be recommended for clinical use.

RESIRT: A Phase 1 Study of Selective Internal Radiation Therapy Using Yttrium-90 Resin Microspheres in Patients With Primary Renal Cell Carcinoma.

INTRODUCTION: Selective internal radiation therapy (SIRT) is a potential treatment of primary renal cell carcinoma (RCC) deemed unsuitable for conventional therapy. RESIRT is the first-in-human study to evaluate safety and feasibility of SIRT for primary RCC. PATIENTS AND METHODS: Patients with RCC, unsuitable for, or who declined conventional therapy, were eligible. A single transfemoral micro-catheter administration of yttrium-90 (Y-90) resin microspheres (SIR-Spheres) was delivered super selectively via the renal artery to the tumour at intended radiation doses of 75, 100, 150, 200, 300 Gy and a final cohort with a procedural endpoint of "imminent stasis," in a dose-escalation design. Post-SIRT follow-up was 12 months. Study endpoints included safety and toxicity 30-days and 12-months post-SIRT and tumour response (RECIST v1.1). RESULTS: In total, 21 patients were enrolled, mean (SD) age was 75 (9.3) years, WHO performance status was 0 in 81%, 12 (57%) had stage 3 chronic kidney disease, and 7 (33%) had prior contralateral nephrectomy. Overall, 71% of patients completed 12 months of follow-up. Intended doses were delivered without any dose-limiting toxicity. Seventeen out of 21 (81%) patients experienced an adverse event (AE) from any cause within 30 days post-SIRT; all SIRT-related AEs were grade 1 to 2. Best overall tumour responses were partial response 1/21 (4.8%), stable disease 19/21 (90.5%) and progressive disease 1/21 (4.8%). CONCLUSION: This study demonstrated good tolerability of SIRT at all dose levels including "imminent stasis" in treating primary tumours in RCC patients otherwise unsuitable for conventional therapy. SIRT with Y-90 resin microspheres may be a feasible treatment option for RCC.

The diagnostic utility of diffusion weighted MRI imaging and ADC ratio to distinguish benign from malignant renal masses: sorting the kittens from the tigers.

BACKGROUND: MRI is playing an increasing role in risk stratification and non-invasive diagnosis of the undifferentiated small renal mass. This study was designed to assess the reliability of MRI in diagnostic evaluation of renal masses, specifically characterising lesions with diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) values. METHODS: This is a retrospective analysis of patients undergoing MRI as part of their clinical workup for a renal mass suspicious for renal cell carcinoma (RCC) on CT or ultrasound followed by biopsy and/or surgical excision. All cases were conducted on 3 Tesla MRI, with conventional breath-held sequences, DWI and dynamic contrast enhanced phases. Tumour regions of interest were evaluated on ADC maps and compared with T2 weighted and post-contrast images. RESULTS: Of the 66 renal tumours included, 33 (50.0%) were Clear Cell RCC, 11 (16.7%) were Oncocytoma, nine (13.6%) were Angiomyolipoma (AML), nine (13.6%) were Papillary RCC and four (6.1%) were Chromophobe RCC. Oncocytoma had the largest ADC values, significantly larger than AMLs and all RCC subtypes (p < 0.001). The average ADC value was also significantly larger in Clear Cell RCCs compared to AMLs, and other RCC subtypes (p < 0.001). CONCLUSIONS: MRI with DWI/ADC imaging may aid the differentiation of oncocytomas from RCCs and stratify RCC subtypes, Further studies are required to validate these findings. TRIAL REGISTRATION: Not applicable/retrospective study.

Chemical shift imaging in the identification of those renal tumours that contain microscopic fat and the utility of multiparametric MRI in their differentiation.

INTRODUCTION: The aim of this study was to assess the qualitative and MRI findings of renal tumours, to determine which lesions contain microscopic fat, one of the potential differentiating factors between tumour types. METHODS: 73 patients who underwent 3 Tesla MRI including chemical shift imaging, with subsequent biopsy or excision for histopathological diagnosis, were included in the study. The images were reviewed for a decrease in signal intensity (SI) on the opposed phase compared with the in-phase gradient echo T1 images, indicating the presence of microscopic fat. The chemical shift index was then calculated as a percentage of SI change and compared with the pathological diagnosis. RESULTS: In total, 38 (52%) of lesions demonstrated a decrease in SI, consistent with microscopic fat. Microscopic fat was found in 28 (80%) clear cell renal cell carcinomas (RCCs), 6 (66.7%) angiomyolipomas, 2 (20%) papillary RCCs, 1 (20%) chromophobe RCC and 1 (9.1%) oncocytoma. Pairwise comparison of means indicated that the amount of microscopic fat was significantly larger only for angiomyolipomas compared with clear cell RCCs (P < 0.001) and other renal lesions (P < 0.001). CONCLUSIONS: A decrease in SI on opposed phase compared with in-phase chemical shift imaging favours the diagnosis of either clear cell RCC or an angiomyolipoma. When combined with other parameters in mpMRI, this may aid differentiation of benign from malignant tumours and differentiation of aggressive from indolent RCC subtypes. This may be of value where biopsy is non-diagnostic, not feasible due to location or in high-risk patients.

Frequency of Angiomyolipomas Among Echogenic Nonshadowing Renal Masses (> 4 mm) Found at Ultrasound and the Utility of MRI for Diagnosis.

OBJECTIVE: The purpose of this study is to evaluate what percentage of echogenic nonshadowing renal lesions larger than 4 mm found at ultrasound are angiomyolipomas (AMLs) and to review how to diagnose AMLs, with particular emphasis on the increasing role played by MRI. MATERIALS AND METHODS: The study data were obtained at a single institution over a period of 45 months. Although some patients were being reviewed for specific symptoms, such as hematuria, pain, or recurrent urinary tract infections, most of the findings were incidental. Follow-up data on 158 lesions in 132 patients were available. Confirmation of diagnosis was made with follow-up imaging or with histopathologic examination. RESULTS: Ninety-eight (62.0%) of the lesions were AMLs, eight (5.1%) were renal cell carcinomas, three (1.9%) were oncocytomas, 17 (10.8%) were artifacts, seven (4.4%) were fat, five (3.2%) were calculi, another eight (5.1%) were scars, and 12 (7.6%) were complicated cysts. The mean age of patients with AML was significantly lower than that of patients without AML (61.71 [SD, 13.25] years vs 68.80 [SD, 17.85] years; p = 0.005). There was a female association with AMLs (p < 0.001). CONCLUSION: Echogenic nonshadowing renal lesions larger than 4 mm seen at ultrasound should not be assumed to represent an AML without follow-up because a percentage of renal cell carcinomas will be missed. Although certain ultrasound features can be useful in differentiating an AML from a renal cell carcinoma and CT is frequently diagnostic, an understanding of MRI is important because it can potentially detect lipid-poor AMLs.

Histological Comparison of Kidney Tissue Following Radioembolization with Yttrium-90 Resin Microspheres and Embolization with Bland Microspheres.

BACKGROUND: Intra-arterial brachytherapy with yttrium-90 (90Y) resin microspheres (radioembolization) is a procedure to selectively deliver high-dose radiation to tumors. The purpose of this research was to compare the radioembolic effect of 90Y-radioembolization versus the embolic effect of bland microspheres in the porcine kidney model. METHODS: In each of six pigs, ~25-33 % of the kidney volume was embolized with 90Y resin microspheres and an equivalent number of bland microspheres in the contralateral kidney. Kidney volume was estimated visually from contrast-enhanced fluoroscopy imaging. Morphologic and histologic analysis was performed 8-9 weeks after the procedure to assess the locations of the microspheres and extent of tissue necrosis from 90Y-radioembolization and bland embolization. A semi-quantified evaluation of the non-acute peri-particle and perivascular tissue reaction was conducted. All guidelines for the care and use of animals were followed. RESULTS: Kidneys embolized with 90Y-radioembolization decreased in mass by 30-70 % versus the contralateral kidney embolized with bland microspheres. These kidneys showed significant necrosis/fibrosis, avascularization, and glomerular atrophy in the immediate vicinity of the 90Y resin microspheres. By contrast, glomerular changes were not observed, even with clusters of bland microspheres in afferent arterioles. Evidence of a foreign body reaction was recorded in some kidneys with bland microspheres, and subcapsular scarring/infarction only with the highest load (4.96 × 106) of bland microspheres. CONCLUSION: This study showed that radioembolization with 90Y resin microspheres produces localized necrosis/fibrosis and loss of kidney mass in a porcine kidney model. This result supports the study of 90Y resin microspheres for the localized treatment of kidney tumors.

Super selective radio embolization of the porcine kidney with 90yttrium resin microspheres: a feasibility, safety and dose ranging study.

PURPOSE: We determined whether super selective radio embolization of the porcine kidney was technically feasible and evaluated histopathological changes in the treatment target zone (upper or lower renal pole), adjacent nontargeted kidney, and adjacent and distant organs after administering (90)Y labeled vs bland resin microspheres. MATERIALS AND METHODS: We performed super selective radio embolization with (90)Y resin microspheres in 1 kidney and with an equivalent number of bland microspheres in the corresponding pole of the contralateral kidney as a control. The aim was to achieve radio embolization of a target zone equivalent to approximately a third of the kidney volume. A pathologist independently graded macroscopic and microscopic changes in the kidney, and adjacent and distant tissue resulting from incremental increases (0.15 to 0.35 GBq) in implanted activity in 6 pigs. RESULTS: We recorded grade 4 histological changes in the treatment target zone (upper or lower renal pole) in 5 of 6 pigs after injecting (90)Y resin microspheres with evidence of nephron sparing effects in the adjacent renal tissue at the lowest activity. At activity greater than 0.3 GBq increasing damage was noted to adjacent renal tissue beyond the treatment target zone. No toxicity was evident in adjacent or distant organs. CONCLUSIONS: Delivery of highly targeted intra-arterial radiotherapy to the kidney is feasible and safe in the pig model. Further evaluation is warranted as a potential treatment for advanced renal cell carcinoma or for localized disease in patients who are not candidates for surgery.

A case of iatrogenic ureteric injury presenting with headache.

BACKGROUND: A 33-year-old woman was referred to the renal outpatient clinic with a headache caused by severe hypertension. She had given birth 3 months previously by emergency caesarean section after a labor complicated by uterine rupture. She had delivered by caesarean section twice previously. INVESTIGATIONS: Full blood count, urinalysis, serum creatinine level, renal ultrasonography, antegrade and retrograde studies. DIAGNOSIS: Renal ultrasonography showed marked left hydronephrosis. Antegrade and retrograde studies showed a short ureteric stricture 3 cm proximal to the vesicoureteric junction causing complete obstruction and consistent with iatrogenic ureteric injury. MANAGEMENT: A left nephrostomy was placed and the patient was treated with nifedipine and prazosin. Her hypertension resolved and these drugs were discontinued 1 week later. The ureteric stricture was managed by entirely endourological means. A guidewire was manipulated across the stricture via a combined antegrade and retrograde approach. Ureterotomy was then undertaken using a holmium yttrium-aluminum-garnet laser, followed by placement of a endopyelotomy stent with the larger segment across the stricture site. A good result was seen at ureteroscopy following subsequent stent removal. The patient remains normotensive.

Osteoporosis and spinal fractures in men with prostate cancer: risk factors and effects of androgen deprivation therapy.

PURPOSE: We determined the risk factors for osteoporosis and spinal fractures in men with prostate cancer receiving androgen deprivation therapy. MATERIALS AND METHODS: We performed a retrospective analysis of 87 consecutive men with prostate cancer receiving androgen deprivation therapy referred for evaluation of osteoporosis. Data were comprised of lateral thoracolumbar radiographs, bone densitometry, serum biochemistry and a detailed assessment of osteoporotic risk factors. Multivariate regression analysis was used to determine the major risk factors for osteoporosis and spinal fractures. RESULTS: There were 38 (44%) men who were 74.5 years old with radiographic evidence of spinal fractures. They had an initial mean prostate specific antigen of 52.8 ng/ml and had received androgen deprivation therapy for a mean of 39.6 months (95% confidence interval 28.7 to 50.4). Mean spinal (quantitative computerized tomography t-score -4.2) and femoral neck bone mineral densities (dual energy x-ray absorptiometry t-score -2.1) were significantly lower than in men without spinal fractures (p < 0.001 for all measurements). In the regression analysis the duration of androgen deprivation therapy (p = 0.002), serum 25-hydroxyvitamin D levels (p = 0.003) and a history of alcohol excess (defined as more than 4 standard drinks daily, p = 0.04) were the main determinants of spinal fractures. CONCLUSIONS: Prolonged androgen deprivation therapy, low serum 25-hydroxyvitamin D levels and a history of alcohol excess are important risk factors for osteoporosis and spinal fractures in men with prostate cancer.