Preliminary study of MRI in diagnosis of heat stroke

Abstract

Objective To investigate MRI features of heat stroke (HS) and 1H-MRS in monitoring clinical outcome.Methods Six cases(4 males,2 females) of HS patients,aged 43-75 years old were retrospectively studied.The patients were divided into 4 severe cases (2 cases with coma for 4 hours,2 patients with persistent coma) and 2 moderate cases according to initial Glasgow coma scale (GCS) at the time of hospital admission.All patients underwent T1WI,T2WI,FLAIR,DWI,SWI,multi voxel 1H-MRS scans and the ratios of NAA/Cr,Cho/Cr,and NAA/Cho were calculated.One case of severe coma died on the next day.Follow-up imaging and brain 1H-MRS were performed on other 5 patients on the 7th and 15th day after the first examination.The imaging results were compared with clinical outcome.Results MRI features of HS for severe coma patients were iso-intensity on T1WI,hyper-intensity on T2WI,FLAIR and DWI,heterogeneous signal intensity on ADC.The infratentorial lesions distributed in the cerebellum,dentate nucleus and cerebellar arm (3 cases),and the supratentorial lesions distributed in the parahippocampal gyrus (2 cases),parietal lobe (2 cases),and temporal lobe (1 cases).The lesions could be multiple,and the cerebellum and the parahippocampal gyrus were most common involved.SWI showed focal hemorrhage in 2 cases,which located in the brainstem and parietal lobe.No obvious MRI abnormality was found in 2 cases of moderate coma patients.The ratios of NAA/Cr,Cho/Cr,and NAA/Cho for severe coma patients were 0.67 ±0.09,0.94 ±0.16 and 0.70±0.12,respectively,which for moderate coma patients were 0.87±0.12,0.95±0.13,and 0.94±0.08,respectively.The NAA/Cr and NAA/Cho ratios decreased and Cho/Cr mild decreased in the severe coma patients when compared with the moderate coma patients.One patient with persistent coma had expanded lesions on follow-up study.NAA/Cr,NAA/Cho and Cho/Cr were 0.63± 0.07,0.67 ±0.10,and 0.96 ±0.05,respectively.Two cases had smaller lesions on follow-up study with NAA/Cr and NAA/Cho ratio increased,which were 1.02±0.13 and 0.96±0.11,respectively.GCS was turned to 14.NAA/Cr and NAA/Cho for moderate coma patients were 1.17±0.10 and 1.21 ±0.07,respectively.Conclusions Severe HS patients present with cerebral edema and hemorrhage.1H-MRS can be an important index for monitoring the severity of HS.The longer the duration of coma,the worse prognosis may happen. Key words: Heat stroke; Magnetic resonance imaging; Magnetic resonance spectroscopy