MR findings of lithium-related kidney disease: preliminary observations in four patients.

PURPOSE: To describe MR features of the kidney in patients on chronic lithium therapy and to correlate findings with the level of renal impairment.

METHOD: In this retrospective HIPPA compliant study, a search was performed in our institutional clinical and radiological computerized database for subjects with lithium-related kidney disease between August 1, 2009 and May 30, 2010. Four patients (2 male and 2 females, mean age 64.75 ± 3.5) with a total of eight kidneys fulfilled the search criteria. T2-weighted images were used to evaluate the presence, size, and distribution of renal cysts. T1-weighted images were used to evaluate kidney length, parenchymal thickness, and cortico-medullary differentiation (CMD).

RESULTS: All kidneys displayed multiple, very abundant, small size (1-2 mm) cysts. The distribution of the cysts was symmetric in renal cortex and medulla and the number of cysts was similar in both kidneys. Sparse, asymmetrical parenchymal renal cysts >3 mm in diameter were also observed. The size and parenchyma thickness of both kidneys was considered normal in all patients. The CMD differentiation was preserved only in patients with normal laboratory kidney findings (n = 2), but was lost in patients with chronic renal failure.

CONCLUSIONS: Multi-microcystic kidney disease secondary to long-term lithium therapy can be detected with MR imaging regardless of known renal impairment. Preservation of renal CMD was observed in both patients with normal kidney function. The results of our preliminary study suggest the possible role of MR imaging for the screening of early manifestations of nephropathy in patients undergoing chronic lithium therapy.