Diagnostic Utility of Diffusion-weighted Magnetic Resonance Imaging in Differentiating Small Solid Renal Tumors (≤4 cm) at 3.0T Magnetic Resonance Imaging

Abstract

Background:The aim of this study was to assess the performance of apparent diffusion coefficient (ADC) measurement obtained with diffusion-weighted magnetic resonance imaging (DW-MRI) to distinguish renal cell carcinomas (RCCs) from small benign solid renal tumors (≤4 cm).Methods:In this cross-sectional study, 49 consecutive patients with histopathologically confirmed small solid renal tumors, and seven healthy volunteers were imaged using nonenhanced MRI and DW-MRI. The ADC map was calculated using the b values of 0, 50, 400, and 600 s/mm2 and values compared via the Kruskal–Wallis and Mann–Whitney tests. The utility of ADC for differentiating RCCs and benign lesions was assessed using a receiver operating characteristic curve. Multiple nonenhanced MRI features were analyzed by Logistic regression.Results:The tumors consisted of 33 cases of clear-cell RCCs (ccRCCs) and 16 cases of benign tumors, including 14 cases of minimal fat angiomyolipomas and 2 cases of oncocytomas. The ADCs showed significant differences among benign tumors ([0.90 ± 0.52] × 10−3 mm2/s), ccRCCs ([1.53 ± 0.31] × 10−3 mm2/s) and the normal renal parenchyma ([2.22 ± 0.12] × 10−3 mm2/s) (P < 0.001). Moreover, there was statistically significant difference between high and low-grade ccRCCs (P = 0.004). Using a cut-off ADC of 1.36 × 10−3 mm2/s, DW-MRI resulted in an area under the curve (AUC), sensitivity, and specificity equal to 0.839, 75.8%, and 87.5%, respectively. Nonenhanced MRI alone and the combination of imaging methods led to an AUC, sensitivity and specificity equal to 0.919, 93.9%, and 81.2%, 0.998, 97%, and 100%, respectively. The Logistic regression showed that the location of the center of the tumor (inside the contour of the kidney) and appearance of stiff blood vessel were significantly helpful for diagnosing ccRCCs.Conclusions:DW-MRI has potential in distinguishing ccRCCs from benign lesions in human small solid renal tumors (≤4 cm), and in increasing the accuracy for diagnosing ccRCCs when combined with nonenhanced MRI.

The utility of ADC measurement techniques for differentiation of low- and high-grade clear cell RCC

“…However, we could not differentiate low- and high-grade ccRCCs with their ADC values concerning the size of ccRCC (small or large). In a study by Zhang et al ., ADC values of small RCCs were compared with benign renal masses, and they found higher ADC values for RCCs [13]. They found a value of 1.53 ±0.31 (×10 –3 mm 2 /s), similar to our Sel-ADC value on a 3.0 T MRI scanner.…”

“…Therefore, larger ccRCCs are expected to have lower ADC values. There are a limited number of studies focusing on the relation of the size and the grade of the ccRCC, and they mainly propose a significant correlation between the size and the nuclear grade of RCCs [9,12,13]. However, the mean size of ccRCCs did not differ and was inversely correlated among Fuhrman grades of ccRCC in our study.…”

“…This discrepancy can be related to the morphology of the tumours, ROI placement on an ADC map that was unclear, and the MRI scanner (a 3.0. T MRI) [13].…”

Metastatic Renal Cell Carcinoma Masquerading as Jugular Foramen Paraganglioma: A Role for Novel Magnetic Resonance Imaging

“…Diffusion weighted MRI is an emerging imaging technique that measures the movement of water molecules within tissue (Brownian motion), which is a function of the molecular properties of the tissue. 4,11 The ADC value quantifies the magnitude of diffusion present in the selected region of interest on the DW-MRI, which is inversely related to the cellularity of tissue; hypercellular lesions have lower ADC values. 4,6 Diffusion weighted MRI has been used to distinguish benign and malignant lesions without use of contrast; malignant lesions are more cellular and therefore associated with lower ADC values.…”

“…4,6 Diffusion weighted MRI has been used to distinguish benign and malignant lesions without use of contrast; malignant lesions are more cellular and therefore associated with lower ADC values. 4,6,11 Thresholds of 1.3 to 1.25 × 10 −3 mm 2 /s have been used to distinguish benign from malignant. 4 The ADC values for RCC associated with metastatic disease (1.06 ± 0.38 × 10 −3 mm 2 /s) are reported as lower than those for RCC without metastatic disease (3.02 ± 2.44 × 10 −3 mm 2 /s), despite no significant differences in T1 and T2 sequences.…”