Detectability and signal intensity of small renal cell carcinoma (< 3 cm) with Gadolinium-enhanced magnetic resonance

Imaging of renal cell carcinoma (RCC) with Gadolinium-DTPA enhanced MR (Gd-MR) was investigated in 61 patients with 66 neoplasms confirmed at surgery. The purpose of the study was to evaluate the accurancy of plain and Gadolinium enhanced MR imaging in detecting renal neoplasms according to the maximum diameter, to analyse the signal intensity of the lesions and to correlate plain and contrast enhanced patterns with the pathological components and architecture of the surgical specimens. Unenhanced MRI detected all large lesions (>3 cm) and 63% of small lesions (<3 cm), while Gd-MR detected all large and small RCC (100%). On Gd-MR small RCC appeared most frequently as lesions with a high intensity signal (45%), while large tumors appeared mostly as hypointense lesions (70%). No specific contrast enhanced MR pattern was observed according to the tumor architecture (alveolar, tubular or papillar) of non cystic lesions. On the contrary, cystic lesion appeared as an area of low signal intensity and the use of contrast media improved detection and characterization. The presence of a fibrohyalin component was strongly associated with the hyperintense pattern of the small RCC. The inhomogeneous signal-intensity increased the detectability of the lesion and therefore the use of Gadolinium increased the conspicuousness of tumors.