Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Identify Clear Cell Renal Cell Carcinoma in cT1a Renal Masses

Abstract

Purpose Detection of small renal masses is increasing with the use of cross-sectional imaging, although many incidental lesions have negligible metastatic potential. Among malignant masses, clear cell renal cell carcinoma is the most prevalent and aggressive subtype, and a method to identify such histology would aid in risk stratification. Our goal was to evaluate a likelihood scale for multiparametric magnetic resonance imaging in the diagnosis of clear cell histology. Methods Patients with cT1a masses who underwent MRI and partial or radical nephrectomy from December 2011 to July 2015 were retrospectively reviewed. Seven radiologists with different levels of experience and blinded to final pathology independently reviewed studies based on a predefined algorithm, and applied a clear cell likelihood score: 1) definitely not, 2) probably not, 3) equivocal, 4) probably, and 5) definitely. Binary classification determined the accuracy of clear cell versus ‘all other’ histologies, and inter-observer agreement was calculated with a weighted κ statistic. Results In total, 110 patients with 121 masses were identified. Mean tumor size was 2.4 cm and 50% were clear cell. Defining clear cell as scores ≥4 demonstrated sensitivity and specificity of 78% and 80%, respectively, while scores ≥3 were 95% and 58%, respectively. Inter-observer agreement was moderate to good, with a mean κ of 0.53. Conclusions A clear cell likelihood score with MRI can reasonably identify clear cell histology in small renal masses, and may reduce the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria are needed to improve inter-observer reliability.

Diagnostic Performance and Interreader Agreement of a Standardized MR Imaging Approach in the Prediction of Small Renal Mass Histology

“…Pathologic stage ≥T2, uninterpretable MRI due to poor image quality, and lack of essential MRI sequences per local institutional protocol (refer below) were excluded (Fig 1). This cohort was included in a previous study, although no overlap exists in the analyses performed (14). The previous study evaluated the diagnostic accuracy of a likelihood score for the prediction of clear cell histology (14).…”

“…This cohort was included in a previous study, although no overlap exists in the analyses performed (14). The previous study evaluated the diagnostic accuracy of a likelihood score for the prediction of clear cell histology (14). In contrast, the current study assesses the diagnostic performance and inter-reader agreement of a standardized diagnostic algorithm for the diagnosis of the most common malignant and benign histologic diagnoses in SRM and analyzes the contribution of individual imaging findings in achieving the correct diagnosis.…”

Identification and Validation of Radiographic Enhancement for Reliable Differentiation of CD117(+) Benign Renal Oncocytoma and Chromophobe Renal Cell Carcinoma

“…Gorin and colleagues has reported that a sestamibi scan has high sensitivity for renal oncocytoma but cannot reliably rule out ChRCC, which occasionally gives a positive result (38). Canvasser and colleagues reported recently an algorithm using MRI signal intensity to predict CcRCC histology (39). A total of 9 ChRCC and 7 renal oncocytoma tumors of unspecified CD117 status were studied and showed overlap in MRI enhancement.…”

Nephrectomy Avoided in a Patient with Lipid Poor Angiomylipoma with Radiological Features Suspicious for Renal Cell Carcinoma: A Case Report

“…Low signal intensity on T2 weighted imaging compared to the signal intensity of the renal cortex favours a diagnosis of lipid-poor AML rather than clear cell RCC [11]. However, papillary RCCs can also have low T2 signal intensity but these lesions typically have a lower level enhancement which is less prolonged than AMLs [12]. …”