[Problems and errors of magnetic resonance in the diagnosis of renal masses]

Since the impact of MRI on the diagnostic evaluation of renal masses is affected by the intrinsic complexity of the modality, the problems related to the specific knowledge, on the part of the radiologist, of the examination itself to make a correct diagnosis are carefully analyzed. The problems related to the technical features of the equipment are presented as well, with a special emphasis on the still inadequate spatial resolution of MRI, and on its long acquisition time and unfavorable signal-to-noise ratio. On the other hand, its good contrast resolution is mentioned, which will be further improved by the new gradient-echo sequence (GRE) and by the use of paramagnetic contrast media. As for diagnostic problems, the results are analyzed of a series of 62 patients showing US "solid" renal mass. MRI allowed lesion detection in 59/62 cases, with 95.1% sensitivity. False negatives were due solely to the poor image quality determined by motion artifacts. MRI did not provide significant information in the structural evaluation of the lesions when tissue characterization was concerned, but was helpful in the correct assessment of necrotic foci (thus allowing the calculation of viable neoplastic mass) and in the detection of collateral vessels. Finally, the spatial relationships of the mass could be easily assessed by MRI, thanks to both its multiplanarity and to its good capabilities in the visualization of vascular involvement.