Evaluation of image-pro plus assisted superb microvascular imaging for differential diagnosis of renal masses

OBJECTIVE

Previous research on diagnostic assessment by superb microvascular imaging (SMI) were based on qualitative or semi-quantitative assessments of vascularity, which may be subjective and unrepeatable by different sonographers. This study aimed to evaluate diagnostic performance of SMI Image-pro Plus (IPP) based vascular index (VI) for malignant renal masses.

METHOD

We retrospectively reviewed 222 masses in 214 patients who underwent SMI between August 2019 and August 2022 in our study. We evaluated the diagnostic performance of blood flow via Alder grade, VI based on both IPP and SMI.

RESULTS

The kappa consistency of the Adler grade and VI for renal masses was classified among different observers were 0.765 and 0.824. The intra-observers correlation ecoefficiency (ICC) were 0.727 and 0.874. Benign renal masses were mainly Adler grade 0, grade I, and grade II, VI was 4.30 ± 4.27 (Range 0.98-16.42); while malignant masses were mainly Adler grade III, VI was 14.95 ± 10.94 (Range 0.79-56.89). VI was higher in malignant than benign masses (t = 15.638, P < 0.01). Among the malignant masses, the mean VI in clear cell renal cell carcinoma was higher than that in papillary renal cell carcinoma and chromophobe renal cell carcinoma (F = 30.659, P < 0.01). The sensitivity, specificity and accuracy of SMI were 80.00%, 71.15%, and 78.64%, respectively. The sensitivity, specificity, and accuracy were 60.59%, 88.46%, and 80.18% by using a VI of 7.95 as the cutoff value to identify malignant lesions from benign masses yielded. VI had better diagnostic efficiency than ultrasonic characteristics and Adler grade in benign and malignant differential diagnosis (Z = 4.851, P < 0.01; Z = 2.732, P < 0.01).

CONCLUSION

VI was higher in malignant than benign in renal masses. In malignant masses, VI in CCRCC was higher than that in papillary renal cell carcinoma and ChRCC. As a noninvasive examination, it had important clinical significance in the differential diagnosis of renal masses. VI from IPP may assist sonographer in distinguish renal malignances as a quantitative tool for vascularity.

Renal Function After CT-Guided Cryoablation of Small Renal Tumours in Patients with Solitary Kidney: An Analysis of European Multinational Prospective EuRECA Registry

PURPOSE

Treatment of renal cell carcinoma (RCC) in patients with solitary kidneys remains challenging. The purpose of this multicentre cohort study was to explore how renal function is affected by percutaneous image-guided cryoablation in patients with solitary kidneys.

MATERIAL AND METHODS

Data from the European Registry for Renal Cryoablation database were extracted on patients with RCC in solitary kidneys treated with image-guided, percutaneous cryoablation. Patients were excluded if they had multiple tumours, had received previous treatment of the tumour, or were treated with more than one cryoablation procedure. Pre- and post-treatment eGFR (within 3 months of the procedure) were compared.

RESULTS

Of 222 patients with solitary kidneys entered into the database, a total of 70 patients met inclusion criteria. The mean baseline eGFR was 55.8 ± 16.8 mL/min/1.73 m2, and the mean 3-month post-operative eGFR was 49.6 ± 16.5 mL/min/1.73 m2. Mean eGFR reduction was - 6.2 mL/min/1.73 m2 corresponding to 11.1% (p = 0.01). No patients changed chronic kidney disease group to severe or end-stage chronic kidney disease (stage IV or V). No patients required post-procedure dialysis.

CONCLUSION

Image-guided renal cryoablation appears to be safe and effective for renal function preservation in patients with RCC in a solitary kidney. Following cryoablation, all patients had preservation of renal function without the need for dialysis or progression in chronic kidney disease stage despite the statistically significant reduction in eGFR. LEVEL OF EVIDENCE 3: Observational study.

Usefulness of renal nephrometry scoring systems in the prediction of complications associated to percutaneous image-guided treatment for small renal masses

INTRODUCTION

Due to their increasing prevalence and complex management, renal tumors are challenging for health professionals. The study aims to evaluate the usefulness of R.E.N.A.L. and PADUA nephrometry scores in the prediction of complications after percutaneous cryoablation.

MATERIAL AND METHODS

The study prospectively analyzed 90 patients with 101 stage T1a renal cell carcinoma (RCC) tumors treated with cryoablation.

RESULTS

Ninety patients with 101 small renal tumors who received cryoablative therapy were investigated. The mean age of the patients was 68 years and 74.4% were male. Most tumors were smaller than 4 cm (89.1%) and the mean PADUA and R.E.N.A.L. scores were 8.65 and 7.35, respectively. Complications were observed in 12 cases. PADUA and R.E.N.A.L. scores demonstrated moderate predictive power (AUC = 0.58 and AUC = 0.63, respectively) for post-cryoablation complications.

CONCLUSIONS

Percutaneous cryoablation is a safe and effective treatment for small renal tumors. The R.E.N.A.L. and PADUA renal nephrometry scores have moderate predictive power for complications associated with percutaneous cryoablation of renal tumors.

Reasons why referring doctors order renal ultrasound contrast studies

PURPOSE

To determine the indications for CEUS for renal mass evaluation.

METHODS

This retrospective, single-center, IRB-approved, HIPAA compliant study analyzed data from 303 consecutive patients scheduled for a renal CEUS to determine the indications for the examination. A chart review was performed from 05/01/2020 through 05/31/2021 on all patients who received a renal CEUS. The patient demographics were extracted as well as the motivating factor for ordering the examination.

RESULTS

From the 303 patients, 114 were referred because of an indeterminate mass seen on CT and 28 were referred for long-term follow-up of a mass defined as benign or malignant was identified on CT. 9 patients were referred for a CEUS follow-up due to an indeterminate mass on MRI and 6 patients were referred for long-term follow-up of a mass defined as benign or malignant on MRI. 34 patients were referred for follow-up for characterization of a lesion seen on unenhanced ultrasound. 48 patients and 21 patients were referred for long-term follow-up of a previously observed benign or malignant lesion, respectively, seen on CEUS. CEUS was ordered in 21 patients to follow-up a partial nephrectomy and 5 patients for follow-up of a thermal ablation. 7 patients were referred because of a clinical finding.

CONCLUSION

The main reason for a renal CEUS referral is to characterize a mass which could not be characterized on CT or MRI. Another main indication is for long-term follow-up of lesions to decrease radiation dose. Referrals due to inability to receive CT or MRI contrast or renal insufficiency were minor indications.

Predicting common solid renal tumors using machine learning models of classification of radiologist-assessed magnetic resonance characteristics

PURPOSE

Solid renal masses (SRM) are difficult to differentiate based on standard MR features. The purpose of this study was to assess MR imaging features of SRM to evaluate performance of ensemble methods of classifying SRM subtypes.

MATERIALS AND METHODS

MR images of SRM (n = 330) were retrospectively evaluated for standard and multiparametric (mp) features. Models of MR features for predicting malignant and benign lesions as well as subtyping SRM were developed using a training dataset and performance was evaluated in a test data-set using recursive partitioning (RP), gradient booting machine (GBM), and random forest (RF) methods.

RESULTS

In the test dataset, GBM and RF models demonstrated an accuracy of 86% (95% CI 75% to 93%) for predicting benign versus malignant SRM compared to 83% (95% CI 71% to 91%) for the RP model. RF had the greatest accuracy in predicting SRM subtypes, 81.2% (95% CI 69.5% to 89.9%) compared with GBM 73.4% (95% CI 60.9% to 83.7%) or RP 70.3% (95% CI 57.6% to 81.1%). Marginal homogeneity was reduced by the RF model compared with the RP model (P < 0.001), but not the GBM model (P = 0.135). All models had high sensitivity and specificity for clear cell and papillary renal cell carcinomas (RCC), but performed less well in differentiating chromophobe RCC, oncocytomas, and fat-poor angiomyolipomas.

CONCLUSION

Ensemble methods for prediction of SRM from radiologist-assessed image characteristics have high accuracy for distinguishing benign and malignant lesions. SRM subtype classification is limited by the ability to categorize chromophobe RCCs, oncocytomas, and fat-poor angiomyolipomas.

Reporting on Renal Masses, Recommendations for Terminology, and Sample Templates

Given the incidence of small renal masses, from benign cysts to malignancy, most radiologists encounter these lesions multiple times during their career. Radiologists have an opportunity to provide critical data that will further refine the understanding of the impact of these masses on patient outcomes. This article summarizes and describes recent updates and understanding of the critical observations and descriptors of renal masses. The templates and glossary of terms presented in this review article facilitate the radiology reporting of such data elements, giving radiologists the opportunity to improve diagnostic accuracy and influence management of small renal masses.

Use of Contrast Ultrasound for Renal Mass Evaluation

An introduction to the expanding modality of contrast-enhanced ultrasound is provided, along with basics on contrast agents and technique. The contrast ultrasound findings of multiple renal tumors are reviewed with examples, including clear cell renal cell carcinoma, papillary renal cell carcinoma, chromophobe renal cell carcinoma, other rare renal cell carcinoma subtypes, oncocytoma, upper tract urothelial carcinoma, lymphoma, and angiomyolipoma, followed also by brief discussions of renal infections and pseudolesions.

Comparison of Monoexponential, Biexponential, Stretched-Exponential, and Kurtosis Models of Diffusion-Weighted Imaging in Differentiation of Renal Solid Masses

Objective

To compare various models of diffusion-weighted imaging including monoexponential apparent diffusion coefficient (ADC), biexponential (fast diffusion coefficient [D_f], slow diffusion coefficient [D_s], and fraction of fast diffusion), stretched-exponential (distributed diffusion coefficient and anomalous exponent term [α]), and kurtosis (mean diffusivity and mean kurtosis [MK]) models in the differentiation of renal solid masses.

Materials and Methods

A total of 81 patients (56 men and 25 women; mean age, 57 years; age range, 30–69 years) with 18 benign and 63 malignant lesions were imaged using 3T diffusion-weighted MRI. Diffusion model selection was investigated in each lesion using the Akaike information criteria. Mann-Whitney U test and receiver operating characteristic (ROC) analysis were used for statistical evaluations.

Results

Goodness-of-fit analysis showed that the stretched-exponential model had the highest voxel percentages in benign and malignant lesions (90.7% and 51.4%, respectively). ADC, D_s, and MK showed significant differences between benign and malignant lesions (p < 0.05) and between low- and high-grade clear cell renal cell carcinoma (ccRCC) (p < 0.05). α was significantly lower in the benign group than in the malignant group (p < 0.05). All diffusion measures showed significant differences between ccRCC and non-ccRCC (p < 0.05) except D_f and α (p = 0.143 and 0.112, respectively). α showed the highest diagnostic accuracy in differentiating benign and malignant lesions with an area under the ROC curve of 0.923, but none of the parameters from these advanced models revealed significantly better performance over ADC in discriminating subtypes or grades of renal cell carcinoma (RCC) (p > 0.05).

Conclusion

Compared with conventional diffusion parameters, α may provide additional information for differentiating benign and malignant renal masses, while ADC remains the most valuable parameter for differentiation of RCC subtypes and for ccRCC grading.

Renal Artery Embolization Before Radical Nephrectomy for Complex Renal Tumour: Which are the True Advantages?

Introduction

Renal artery embolization is performed before radical nephrectomy (RN) for renal mass in order to induce preoperative infarction and to facilitate surgical intervention through decrease of intraoperative bleeding. Moreover, in metastatic renal cancer it seems to stimulate tumour-specific antibodies, even if no established benefits in clinical response or survival have been reported. The role of preoperative renal artery embolization (PRAE) in management of renal masses has been often debated and its real benefits are still unclear. Nevertheless, in huge and complex renal masses, which are often characterized by a high and anarchic blood supply and rapid local invasion, radical nephrectomy can be challenging even for skilled surgeons. The aim of this prospective randomized study was to evaluate the effectiveness and safety of PRAE in complex masses by comparing perioperative outcomes of RN with and without PRAE.

Materials and methods

From December 2015 to May 2018 we enrolled prospectively 64 patients who underwent RN for localized (T2a-b) or locally advanced (T3 and T4) or advanced (N+, M+) renal cancers. Patients were divided in two groups. The first group included 30 patients who underwent PRAE; in the second group we enrolled 34 patients who did not undergo RN without PRAE. Perioperative outcomes in terms of operative time, blood loss, transfusion rate and length of hospitalization were evaluated. Statistical analysis was performed using GraphPad Prism 6.0 software.

Results

Median blood loss was 250 ml (50-500) and 400 ml (50-1000) in the first and second group, respectively, with a statistically significant difference (p=0.0066). Median surgical time was 200 min (90-390) and 240 min (130-390) in PRAE and No-PRAE group (p=0.06), respectively. No major complications occurred after embolization. Overall complication rate in Group 1 and 2 was 46.7% (14/30) and 50% (17/34), respectively (p=0.34). No major complications occurred in both groups. The mean follow up was 21,5 months.

Conclusions

Our results prove PRAE to be a safe procedure with low complications rate. To our experience, PRAE seems to be a useful tool in surgical management of a large mass and advanced disease.

Comparison of the Diagnostic Performance of Contrast-enhanced Ultrasound with That of Contrast-enhanced Computed Tomography and Contrast-enhanced Magnetic Resonance Imaging in the Evaluation of Renal Masses: A Systematic Review and Meta-analysis

CONTEXT

Contrast-enhanced ultrasound (CEUS) has the potential to be a valuable alternative to contrast-enhanced computed tomography (CECT) and contrast-enhanced magnetic resonance imaging (CEMR), the current gold standards in characterisation of renal masses.

OBJECTIVE

To systematically review all available evidence on the qualitative diagnostic performance of CEUS versus that of CECT and CEMR in the evaluation of benign and malignant cystic and solid renal masses.

EVIDENCE ACQUISITION

The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

EVIDENCE SYNTHESIS

After screening 1483 articles, six cohort studies and 10 descriptive studies were included. Pooling data from included studies with final diagnosis of benign or malignant renal masses by pathology showed a significant difference in the sensitivity of CEUS (0.96; 95% confidence interval [CI] 0.94-0.98) versus that of CECT (0.90; 95% CI 0.86-0.93). Pooling data from included studies with final diagnosis by pathology report or reaffirmed diagnosis by follow-up imaging without pathology report showed significant difference in the sensitivity of CEUS (0.98; 95% CI 0.94-1.0) versus that of CEMR (0.78; 95% CI 0.66-0.91).

CONCLUSIONS

Preliminary data imply that CEUS may perform at least as well as or better than CECT and CEMR in the diagnosis of renal masses. However, the evidence base is limited, and more high-quality, well-designed, adequately powered, and sampled studies are needed to reach definitive conclusions.

PATIENT SUMMARY

Early data suggest that contrast-enhanced ultrasound is a promising option for the evaluation of renal masses, but more reliable evidence is required.

Interactive virtual 3D models of renal cancer patient anatomies alter partial nephrectomy surgical planning decisions and increase surgeon confidence compared to volume-rendered images

Purpose

To determine whether the interactive visualisation of patient-specific virtual 3D models of the renal anatomy influences the pre-operative decision-making process of urological surgeons for complex renal cancer operations.

Methods

Five historic renal cancer patient pre-operative computed tomography (CT) datasets were retrospectively selected based on RENAL nephrectomy score and variety of anatomy. Interactive virtual 3D models were generated for each dataset using image segmentation software and were made available for online visualisation and manipulation. Consultant urologists were invited to participate in the survey which consisted of CT and volume-rendered images (VRI) for the control arm, and CT with segmentation overlay and the virtual 3D model for the intervention arm. A questionnaire regarding anatomical structures, surgical approach, and confidence was administered.

Results

Twenty-five participants were recruited (54% response rate), with 19/25 having > 5 years of renal surgery experience. The median anatomical clarity score increased from 3 for the control to 5 for the intervention arm. A change in planned surgical approach was reported in 19% of cases. Virtual 3D models increased surgeon confidence in the surgical decisions in 4/5 patient datasets. There was a statistically significant improvement in surgeon opinion of the potential utility for decision-making purposes of virtual 3D models as compared to VRI at the multidisciplinary team meeting, theatre planning, and intra-operative stages.

Conclusion

The use of pre-operative interactive virtual 3D models for surgery planning influences surgical decision-making. Further studies are needed to investigate if the use of these models changes renal cancer surgery outcomes.

Electronic supplementary material

The online version of this article (10.1007/s11548-019-01913-5) contains supplementary material, which is available to authorized users.

[No treatment of a renal cancer without biopsy anymore]

No treatment of a renal cancer without biopsy anymore. Imaging modalities are not accurate for histological diagnosis of renal masses. An histological diagnosis helps to choose the optimal management of a renal mass. Percutaneous biopsy of renal mass is an accurate procedure with low morbidity. It is performed with local anesthesia in an outpatient setting. The biopsy results and optimal management of the renal mass are discussed and validated during the multidisciplinary oncologic round. The patient can be properly and fully informed about the planned management. Because the benefit/risk ratio is in favor of renal tumor biopsy in most of cases, renal tumor biopsy must be discussed and proposed to patients harboring an undetermined renal mass.

Collaborative Review of Risk Benefit Trade-offs Between Partial and Radical Nephrectomy in the Management of Anatomically Complex Renal Masses

BACKGROUND

While partial nephrectomy (PN) is the recommended treatment for many small renal masses, anatomically complex tumors necessitate a clear understanding of the potential risks and benefits of PN and radical nephrectomy (RN).

OBJECTIVE

To critically review the comparative effectiveness evidence of PN versus RN; to describe key trade-offs involved in this treatment decision; and to highlight gaps in the current literature.

EVIDENCE ACQUISITION

A collaborative critical review of the medical literature was conducted.

EVIDENCE SYNTHESIS

Patients who undergo PN for an anatomically complex or large mass may be exposed to perioperative and potential oncologic risks that could be avoided if RN were performed, while patients who undergo RN may forgo long-term benefits of renal preservation. Decision-making regarding the optimal treatment with PN or RN among patients with anatomically complex or large renal mass is highly nuanced and must balance the risks and benefits of each approach. Currently, high-quality evidence on comparative effectiveness is sparse. Retrospective comparisons are plagued by selection biases, while the one existing prospective randomized trial, albeit imperfect, suggests that nephron-sparing surgery may not benefit all patients.

CONCLUSIONS

For anatomically complex tumors, PN preserves renal parenchyma but may expose patients to higher perioperative risks than RN. The risks and benefits of each surgical approach must be better objectified for identification of patients most suitable for complex PN. A prospective randomized trial is warranted and would help in directing patient counseling.

PATIENT SUMMARY

Treatment decisions for complex renal masses require shared decision-making regarding the risk trade-offs between partial and radical nephrectomy.

Follow-up after focal therapy in renal masses: an international multidisciplinary Delphi consensus project

PURPOSE

To establish consensus on follow-up (FU) after focal therapy (FT) in renal masses. To formulate recommendations to aid in clinical practice and research.

METHODS

Key topics and questions for consensus were identified from a systematic literature research. A Web-based questionnaire was distributed among participants selected based on their contribution to the literature and/or known expertise. Three rounds according to the Delphi method were performed online. Final discussion was conducted during the "8th International Symposium on Focal Therapy and Imaging in Prostate and Kidney Cancer" among an international multidisciplinary expert panel.

RESULTS

Sixty-two participants completed all three rounds of the online questionnaire. The panel recommended a minimum follow-up of 5 years, preferably extended to 10 years. The first FU was recommended at 3 months, with at least two imaging studies in the first year. Imaging was recommended biannually during the second year and annually thereafter. The panel recommended FU by means of CT scan with slice thickness ≤3 mm (at least three phases with excretory phase if suspicion of collecting system involvement) or mpMRI. Annual checkup for pulmonary metastasis by CT thorax was advised. Outside study protocols, biopsy during follow-up should only be performed in case of suspicion of residual/persistent disease or radiological recurrence.

CONCLUSIONS

The consensus led to clear FU recommendations after FT of renal masses supported by a multidisciplinary expert panel. In spite of the low level of evidence, these recommendations can guide clinicians and create uniformity in the follow-up practice and for clinical research purposes.

Growing Renal Mass: Lessons Learned on the Road From an Atypical Presentation to Successful Therapy

A 25 4/7 week boy was born with a prenatal diagnosis of polyhydramnios and enlarged left kidney. Over the next 2 months serial ultrasounds demonstrated abnormal growth of the kidney, with 28.9% split function. At gestational age 39 4/7, he underwent a left radical nephrectomy. Pathology revealed congenital mesoblastic nephroma with mixed classic and cellular features. This case was puzzling due to prenatally diagnosed renal enlargement in a premature infant and inconclusive post-natal ultrasonographic imaging. Although the patient had paraneoplastic signs of polyhydramnios and hypertension, the mass did not have a classic appearance of CMN; possibly due to severe prematurity.

Radiofrequency ablation versus partial nephrectomy for treatment of renal masses: A systematic review and meta-analysis

Our study was to collect the data available in the literature on radiofrequency ablation (RFA) and partial nephrectomy (PN) and conduct a cumulative analysis on perioperative outcomes, renal function outcomes, and survival to evaluate the overall safety and efficacy of RFA versus PN for small renal cell cancer (SRCC). A literature search was carried out using various electronic databases. Data including age, tumor size, comorbid disease, operation duration, hospital stay, pre- and postoperative estimated glomerular filtration rate (eGFR), major and minor complications, and local tumor recurrence and metastasis were collected for meta-analysis. Sixteen studies were included for this meta-analysis. The age of patients treated with RFA was significantly older than that of patients treated with PN [weighted mean difference (WMD) = 5.07 years]. There were more patients with cardiovascular disease in RFA group as compared with PN group [odds ratio (OR) = 4.24] before treatment. RFA was associated with a shorter length of hospital stay compared with PN (WMD = -2.02 days). No significant difference was found in major and minor complications between the two groups (major: OR = 0.74; minor: OR = 0.45). Preoperative eGFR and eGFR decline in RFA patients was significantly lower than that in PN patients (WMD = -7.27 and -4.82, respectively), whereas there was no significant difference in postoperative eGFR (WMD = -1.18). The local tumor recurrence rate in RFA group was higher than that in PN group (OR = 1.81). However, the distant metastasis rate was no statistical difference between the two groups (OR = 1.63). RFA is a suitable therapeutic option for older patients and those at high risk for SRCC because of a low risk of operation and better preservation of renal function.

Renal leiomyoma: an uncommon differential diagnosis of renal masses with a clinical relevance

Renal leiomyomas are an extremely rare neoplasm which account for 1.5% of the benign lesions and 0.29% of all treated renal tumours, with autopsy evidence of 4.2% to 5.2%. Given their exceptional incidence, they are rarely included in the differential diagnosis of renal masses, despite their capacity to grow to a considerable size. The definitive diagnosis of a leiomyoma is only possible after histopathological examination, most of the times of a nephrectomy specimen. However, due to the rising number of diagnosis resulting from improved medical imaging and interventions, renal leiomyomas should gain importance in the differential diagnosis of renal masses, specialy with respect to kidney sparing surgery. Hereby, we report a case of 60-year-old male patient with a large well circumscribed left renal mass, diagnosed as Renal cell carcinoma on imaging.

Evaluation of indeterminate renal masses with contrast-enhanced US: a diagnostic performance study

PURPOSE

To determine the utility of contrast material-enhanced ultrasonography (US) in the characterization of indeterminate renal masses.

MATERIALS AND METHODS

This retrospective performance study was approved by the institutional review board and was HIPAA compliant, with waiver of informed consent. Patients included 721 individuals referred for contrast-enhanced US with 1018 indeterminate renal masses from 1999 to 2010, identified initially with an imaging study. Three hundred twenty patients (44.4%) were female, and 401 (55.6%) were male. Patient ages ranged from 17 to 95 years (mean ± standard deviation, 70 years ± 15). Lesion size varied from 2 to 161 mm (mean, 26.6 mm ± 19.5). Contrast-enhanced US enhancement patterns were used to characterize masses as benign or malignant. For lesions with a definitive diagnosis, 306 of 1018 (30.0%) were correlated with contrast-enhanced US findings: 167 (54.6%) were benign, and 139 (45.4%) were malignant. For lesions without a pathologic diagnosis, 712 (70.0%) were followed for as long as 10 years. Diagnostic accuracy measures were calculated by using pathologic diagnosis as the reference standard, as well as lesion stability at 3 and 5 years.

RESULTS

Contrast-enhanced US had a sensitivity of 100% (126 of 126; 95% confidence interval [CI]: 97.1%, 100%), specificity of 95.0% (132 of 139; 95% CI: 89.9%, 98.0%), positive predictive value (PPV) of 94.7% (126 of 133), and negative predictive value (NPV) of 100% (132 of 132). The five false-positive masses included three oncocytomas and two Bosniak category 3 cystic lesions. Of the 290 lesions that had follow-up of at least 36 months, none of the lesions demonstrated changes that necessitated lesion reclassification. If these lesions were included, assuming lesions classified as malignant were malignant, then of the 596 lesions, sensitivity was 100% (161 of 161), specificity was 96.6% (420 of 435), PPV was 91.5% (161 of 176), and NPV was 100% (420 of 420).

CONCLUSION

Contrast-enhanced US evaluation is a highly sensitive and specific method for characterization of indeterminate renal masses. Online supplemental material is available for this article.