Uremic Encephalopathy: MR Imaging Findings and Clinical Correlation

Abstract

Background and purpose: Uremic encephalopathy is a metabolic disorder in patients with renal failure. The purpose of this study was to describe the MR imaging findings of uremic encephalopathy.

Materials and methods: This study retrospectively reviewed MR imaging findings in 10 patients with clinically proved uremic encephalopathy between May 2005 and December 2014. Parameters evaluated were lesion location and appearance; MR signal intensity of the lesions on T1WI, T2WI, and T2 fluid-attenuated inversion recovery images; the presence or absence of restricted diffusion on diffusion-weighted images and apparent diffusion coefficient maps; and the reversibility of documented signal-intensity abnormalities on follow-up MR imaging.

Results: MR imaging abnormalities accompanying marked elevation of serum creatinine (range, 4.3-11.7 mg/dL) were evident in the 10 patients. Nine patients had a history of chronic renal failure with expansile bilateral basal ganglia lesions, and 1 patient with acute renal failure had reversible largely cortical lesions. Two of 6 patients with available arterial blood gas results had metabolic acidosis. All basal ganglia lesions showed expansile high signal intensity (lentiform fork sign) on T2WI. Varied levels of restricted diffusion and a range of signal intensities on DWI were evident and were not correlated with serum Cr levels. All cortical lesions demonstrated high signal intensity on T2WI. Four patients with follow-up MR imaging after hemodialysis showed complete resolution of all lesions.

Conclusions: The lentiform fork sign is reliable in the early diagnosis of uremic encephalopathy, regardless of the presence of metabolic acidosis. Cytotoxic edema and/or vasogenic edema on DWI/ADC maps may be associated with uremic encephalopathy.

Fig 1.

A 52-year-old man (patient 4) presented with seizure-like activity. A T2-weighted image (A) and diagrammatic illustration (B) show the lentiform fork sign. A bright hyperintense rim delineates the lateral (external capsule, long arrow) and medial boundaries (external medullary lamina [short arrow] and internal medullary laminae [thin arrow]) of both putamina. The globus pallidus is divided into 2 parts by the medial medullary laminae, which can be seen in pathologic conditions on MR images. A FLAIR image (C) shows multifocal relatively symmetric, gyriform high SI (arrows) in the cortex of bilateral frontal, parieto-occipital lobes and bilateral basal ganglia.

Fig 2.

A 67-year-old man (patient 5) presented with unsteadiness. DWI (A) and an ADC map (B) show diffuse mildly increased SI (long arrows) in the whole bilateral basal ganglia lesion on DWI with focal restricted diffusion (short arrow), corresponding to cytotoxic edema in the right globus pallidus.

Fig 3.

A 70-year-old man (patient 6) presented with involuntary movement. DWI (A) and an ADC map (B) show normal SI (long arrows) in the bilateral basal ganglia on DWI with restricted diffusion (short arrows) in the bilateral globus pallidus and left putamen, compatible with areas of cytotoxic edema in the lesions.

Fig 4.

A 56-year-old man (patient 3) presented with dysarthria. Initial T2WI (A) shows the lentiform fork sign in the bilateral basal ganglia. Six months later, follow-up T2WI (B) shows complete resolution of the lesions.