Cystic renal mass evaluation: real-time versus static imaging

Fifty consecutive cystic renal masses in 43 patients were evaluated by both static scanning and real-time scanning techniques. Various parameters were evaluated and compared to ascertain whether the strict static scan cystic criteria were always present in comparable real-time evaluations. Four (8%) of the 50 masses were not classic cysts on real-time examinations, although the criteria were present on the static scans. Two had minimal acoustic enhancement and two had low-intensity internal echoes. Possible reasons for this difference were detailed and discussed. The potential problems in this observation were enumerated. Based on these observations, in certain cases when a cystic renal mass demonstrates poor acoustic enhancement or low-level internal echoes in real-time examination, static scanning may be helpful and may obviate the need for further studies.