Multimodality Imaging Characteristics of the Common Renal Cell Carcinoma Subtypes: An Analysis of 544 Pathologically Proven Tumors

Abstract

Objectives:The objective of this study was to define the characteristic imaging appearances of the common renal cell carcinoma (RCC) subtypes.Materials and Methods:The Institutional Review Board approval was obtained for this HIPAA-compliant retrospective study, and informed consent was waived. 520 patients (336 men, 184 women; age range, 22–88 years) underwent preoperative cross-sectional imaging of 544 RCCs from 2008 to 2013. The imaging appearances of the RCCs and clinical information were reviewed. Data analysis was performed using parametric and nonparametric statistics, descriptive statistics, and receiver operating characteristic analysis.Results:The RCC subtypes showed significant differences (P < 0.001) in several imaging parameters such as tumor margins, tumor consistency, tumor homogeneity, the presence of a central stellate scar, T2 signal intensity, and the degree of tumor enhancement. Low T2 signal intensity on magnetic resonance imaging (MRI) allowed differentiation of papillary RCC from clear cell and chromophobe RCCs with 90.9% sensitivity and 93.1% specificity. A tumor-to-cortex ratio ≥1 on the corticomedullary phase had 98% specificity for clear cell RCC.Conclusion:The T2 signal intensity of the tumor on MRI and its degree of enhancement are useful imaging parameters for discriminating between the RCC subtypes while gross morphological findings offer additional value in RCC profiling.

Diagnostic Accuracy of MRI for Detection of Papillary Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

“…The results from the QUADAS-2 analysis are presented in Table 2. The risk of bias in patient selection was classified as unclear for six studies [4, 16–20]. Each of these studies included only patients whose pathologic confirmation was performed via surgical resection.…”

“…In terms of risk of bias related to the index test (MRI interpretation), most studies were designated low risk. One study had a potentially high risk of bias related to the index test because the interpreting radiologists were not blinded to clinical or laboratory information [4].…”

“…In most cases, this designation was given because the pathologic specimens in these studies were obtained via a combination of percutaneous biopsy or surgical resection. In three other studies, the reference standard had a potentially high risk of bias [4, 16, 19]. In these studies, the pathologic specimens were not independently assessed by a single pathologist; instead, the pathologic reports were reviewed and the authors did not mention whether the pathology reviewer was blinded to the imaging interpretation.…”

“…Despite these differences among histologic subtypes in the potential to metastasize and the incidental discovery of most renal tumors at an early stage (i.e., clinical T1a), the standard of care remains surgical resection with either partial nephrectomy or nephrectomy. As alternative treatment approaches gain acceptance, noninvasive subtype differentiation may potentially help guide management decisions [4, 5]. Urologic oncologists may include the subtype information in weighing the oncologic risks of active surveillance or thermal ablation against surgery in patients with medical comorbidities or advanced age.…”

Needle track seeding in renal mass biopsies

“…Another approach would be to use preoperative imaging to select those patients who have features of papillary renal cell carcinoma and only use the smaller needles when performing biopsies in these patients. Distinguishing imaging characteristics have been described on computed tomography (enhancement and attenuation values), magnetic resonance imaging (T2‐weighted hyperattenuation and of low signal on T2‐weighted images and apparent diffusion coefficient), positron emission tomography (standardized uptake value maximum), and contrast‐enhanced ultrasound (speed and extent of enhancement, washout) . It is unknown whether adding some form of ablative agent or gel to the biopsy site before removing the needle would reduce the possibility of tumor cells being drawn backward into the needle track, although preliminary animal studies have suggested it may be possible …”