Value of diffusion-weighted imaging in lesions with different signals on T1WI in patients with anti-N-methyl-D-aspartate receptor encephalitis

Abstract Backgrounds Anti-N-methyl-D-aspartate (NMDA) lesions with different signals on T 1 WI might exhibit different imaging. This study investigated the ADC characteristics of the anti-NMDA lesions with different disease durations (DDs). Methods Retrospective analyses were performed on 66 defined patients with anti-NMDA receptor encephalitis in our hospital. All patients underwent conventional T 2 WI, T 1 WI, and DWI scans. The signal, distribution, and enhancement of the lesions on MRI were observed. Meanwhile, manifestations on DWI and corresponding apparent diffusion coefficient (ADC) images of these lesions were observed, and the ADC values were measured. Relationships between the ADC values and the DD and the modified ranking scale (mRS) scores were analyzed. Results Twenty-nine lesions were observed in only 22/66 patients. All the 29 lesions with different DDs showed diversified signals on T 1 WI and ADC maps. 19 lesions in 17 patients with relatively short DDs presented isointensity on T 1 WI, while hypointensity on the ADC maps. ADC values of the 19 lesions were lower than those of the contralateral normal brain tissues ( P < 0.001). Among the ten lesions observed in 5 patients with rather long DDs, seven lesions showed hypointensity and hyperintensity on ADC maps. The average ADC value of the ten lesions was higher than that of the contralateral normal brain tissue ( P < 0.05). The ADC values of the lesions showed a positive correlation with the patients’ DDs ( P > 0.05). Conclusion s The ADC images and ADC values of anti-NMDAR lesions in different DD are different, which are helpful to infer the pathological changes of this disease.