0.5 T MRI of small renal masses: value of T2-weighted and Gd-DOTA-enhanced images

We compared the value of T2-weighted and Gd-DOTA-enhanced T1-weighted images for the detection and characterisation of 33 small renal masses (14 clear cell carcinomas, 6 angiomyolipomas, 3 angiomyomas, 4 adenomas, 3 papillary carcinomas, 3 oncocytomas, 1 haemorrhagic cyst). Dynamic enhanced MRI was performed to study the tumoral vascular supply (19 cases). MRI depicted all the masses more than 1 cm in diameter, but missed all the lesions less than 1 cm (4 false-negative). The results of T2-weighted images and Gd-DOTA-enhanced images were similar as regards detection; however, Gd-DOTA-enhanced images depicted more clearly the tumours smaller than 2 cm (11 cases). MRI enabled the characterisation of only 3 masses (2 angiomyolipomas, 1 haemorrhagic cyst). New MRI features are described for oncocytomas (low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, early and marked enhancement on dynamic enhanced MRI). Dynamic enhanced MRI did not contribute to the differentiation of benign from malignant tumours.