PMC7365897_01
Conventional MRI. Coronal T2w and axial FLAIR in a patients with MTLE: (a,c) at the onset, the MR shows hyperintense changes involving the hippocampal structures of the left side (asterisk and arrow) with associated cortical swelling. In the follow-up exam (b,d) the same features are less evident with hippocampal atrophic evolution.
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The MR exam showed moderate swelling and increased of T2w/FLAIR signal on the left hippocampus without contrast enhancement, DWI restriction or microbleeds in T2*w images (Fig. 1a,c). Afterwards, the patient's clinical condition stabilized, with complete response to the therapies, and a series of follow-up MR exams were planned (Fig. 1b,d).
Axial, Arterial spin labelling (a), fused 18FDG-PET/MRI (b) and fused 18F-DOPA-PET/MRI (c). Hyperperfusion (rCBF = 2) at the level of the left hippocampus (arrow); (b) Bilateral hypometabolism of the hippocampus more evident on the left side (asterisk). (c) Diffuse, mild tracer uptake of the left mesiotemporal region matching the MRI-FLAIR abnormalities (arrow).
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Advanced MRI, performed the next day, including spectroscopy and arterial spin labelling (ASL) sequences, showed only a mild decrease of NAA, but an hyperperfusion (rCBF = 2) at the level of the left hippocampus at ASL study (Fig. 2a). Cerebral 18FDG-PET done few days later to exclude limbic encephalitis, detected bilateral hypometabolism of the hippocampus more evident on the left side (Fig. 2b). The exam demonstrated an unexpected diffuse, mild increased tracer uptake of the left mesiotemporal region matching the MRI-FLAIR abnormalities (Fig. 2c).