Prevalence and CT features of calyceal diverticula detected using Gd-EOB-DTPA-enhanced liver MR imaging.

PURPOSE: To investigate the prevalence of calyceal diverticulum (CD) among patients undergoing Gd-EOB-DTPA-enhanced liver MR imaging, and to report their CT features including size changes on follow-up examinations. METHODS: We conducted a retrospective review of 1,713 consecutive adult patients who underwent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced liver MR imaging for various indications. Hepatobiliary phase images were screened for the presence of CD by observing the renal parenchymal accumulation of Gd-EOB-DTPA. Two radiologists evaluated the CT features of the identified CDs and measured the changes in size of the CDs and associated calcifications between the initial and follow-up CT examinations. RESULTS: Seven patients had CD, resulting in a prevalence of 0.4%. The shape was round or oval in six CDs and lobulated in one. All of the CDs had a well-defined margin, and none had thickened walls or septa. All of the CDs had homogeneous internal density, with low density in six CDs and intermediate in one. Five CDs were in proximity to the renal sinus. Five calcifications were observed in four CDs: four of which were located on the posterior wall and one on the anterior wall. Follow-up examinations revealed a 28% decrease in the maximum diameter of one CD and a 14% decrease in another. The maximum diameter of the calcifications increased in all cases, with a mean increase of 24%. CONCLUSION: CDs were found in 0.4% of patients who underwent Gd-EOB-DTPA-enhanced liver MR imaging. Typical CT features of CDs were round- or oval-shaped, well-defined, homogeneous, low-density masses that abutted the renal sinus. When calcification was present, it was usually located on the posterior wall and was round or oval in shape. The size of CD may occasionally decrease over time, while associated calcifications tend to increase in size over time.