Pseudoenhancement of renal cysts: influence of lesion size, lesion location, slice thickness, and number of MDCT detectors.

Objective: The purpose of this study was to determine the effect of renal cyst size and location on pseudoenhancement in human subjects.

Methods: Simple renal cysts obtained with 16-, 40-, and 64-MDCT scanners were analyzed for the presence of pseudoenhancement. Cyst size, location, and attenuation in the unenhanced and nephrographic phases were recorded. Pseudoenhancement was defined as an attenuation increase of 10 HU or more on nephrographic phase compared with unenhanced images.

Results: The pseudoenhancement rate was 22% (51/233). There was a statistically significant increase in the pseudoenhancement rate of lesions smaller than 10 mm (38/233) compared with those 10 mm and larger (13/233) (odds ratio, 6.4; p<0.0001). Twelve of 62 cysts measuring 10-14 mm exhibited pseudoenhancement. There was a statistically significant increase in the pseudoenhancement rate of central (39/53) compared with peripheral (12/51) cysts (odds ratio, 2.7; p<0.0001). The pseudoenhancement rates for the 16-, 40-, and 64-MDCT scanners were 20%, 19%, and 26% with no statistically significant difference between them.

Conclusions: Pseudoenhancement of renal cysts significantly correlates with size smaller than 1 cm and central location. Although pseudoenhancement increases with larger numbers of detectors, the correlation was not statistically significant. Cysts in the 1- to 1.5-cm range have a 19% likelihood of pseudoenhancement.