Radiologic Evaluation of Small Renal Masses (II): Posttreatment Management

Abstract

The increase in the detection of small renal masses (SRMs) and their best knowledge leads to a change in the therapeutic management of these lesions. The use of a less aggressive surgical technique or even an expectant attitude is the current tendency, in order to preserve as much renal function as possible. Imaging techniques are essential in the followup of these lesions. It allows us to know the postsurgical changes and possible complications due to treatment and the presence of local recurrence and metastases. Furthermore, a close radiological followup of SRM related to ablative treatments is mandatory. The purpose of this article is to reveal the imaging features of complications due to surgical or ablative treatments, local recurrence and metastasis, as well as their followup.

High-Intensity Focused Ultrasound in Small Renal Masses

“…Microbubbles increased the ablation efficiency and the visibility of tissue destruction attending to the appearance of hyperechoic regions within the targeted tissue [ 6 ]. As with the rest of the nonablative techniques, definitive follow-up protocols are missing [ 37 ], and the role of the biopsy in contrast-enhanced lesions has to be investigated [ 38 ].…”

Sonographically Identified Echogenic Renal Masses Up to 1 cm in Size Are So Rarely Malignant They Can Be Safely Ignored

“…The sonograms of these lesions were then reviewed independently by 3 radiologists (R.O.B., A.P., and M.I., a radiology fellow), who each recorded 3 orthogonal diameters (length and 2 perpendicular transverse diameters) for only those lesions that had both sagittal and axial video clips. The 3 initially independent observers then met in consensus to apply the following exclusion criteria: (1) all lesions in which 3 orthogonal diameters could not be measured; (2) lesions that were more linear than spherical or ellipsoid in shape, defined as lesions with a short-to-long axis ratio of less than 0.5; (3) lesions that appeared to be more than 50% exophytic from the cortex (if the mass was mostly extracortical, the adjacent echogenicity of retroperitoneal fat may have obscured the margins of the mass and limited the accuracy of the lesion measurements); (4) lesions that shadowed or that produced twinkle or ring-down artifacts, implying that they were, or may have been, calculi even when this finding was not mentioned in the report; (5) lesions that visually appeared to be, by volume, less than 50% echogenic (ie, hypoechoic mass with a partial echogenic component); (6) lesions that were not truly cortical masses but instead were extensions of sinus fat into the cortex; and (7) lesions with a measured largest diameter of greater than 1 cm. The 3 reviewers, also in consensus, compared lesion measurements.…”

“…A 5-year period of lesion stability was considered adequate proof of benignity because although renal tumors can be very slow growing, it is now accepted that a lack of growth for 5 years for small renal masses is adequate proof that such masses are benign. 5,6 The criteria used to define an angiomyolipoma on CT were based on attenuation measurements. As this issue still is a topic of debate, [7][8][9] we elected to use conservative criteria to have higher specificity for angiomyolipoma detection.…”