PMC9794603_01
(A) DWI scan after first presentation (November 2021) showing a bright signal mainly in cortical regions; (B) Calculated ADC map of the first DWI scan shows minor alterations with reductions (cortex) and slight increases in the subcortical white matter; (C,E) DWI scan of new temporo-parietal lesion (second MRI scan); (D,F) Calculated ADC map of the second DWI scan (May 2022) revealing a similar pattern as the first MRI scan; (G) FLAIR scan (May 2022) of new temporo-parietal lesion showing prominent and extensive signal abnormalities, but only speckled lesions (arrow) in the previous acute left hemisphere lesion seen in November 2021; (H) Arterial Spin Labeling (ASL) blood flow study displaying hyperperfusion in the new right temporo-parietal lesion and hypoperfusion in the residual chronic lesion on the left hemisphere (arrow); (I) MR Spectroscopy obtained during the second presentation (May 2022). The green graph represents an ROI within the new right temporo-parietal region and the blue graph representing an ROI in a control, unaffected region of the brain. A large difference in the Lactate peak between affected and unaffected brain region can be seen.
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F1
Initially, it was thought that the lesion corresponded to the inferior division of the middle cerebral artery (MCA) (Figure 1A), but this was later revised and thought to not confirm to a particular vascular territory. Retrospective analysis of the Apparent Diffusion Coefficient (ADC) map showed only a mild reduction in the cortex by about 10% of normal (Figure 1B) with a possible small increase in diffusivity in the subcortical white matter region. Head CT and MRI confirmed a new right temporo-parietal lesion extending beyond one single vascular territory (Figure 1C). Although the DWI was bright, only minor alterations in either direction in the calculated ADC values were seen compared to normal brain tissue (Figure 1D). Of note, only small speckled residual T2 lesions were seen in the previous large left hemisphere lesion from November 2021 (Figure 1G, arrow). MR images revealed hyperperfusion (Figure 1H, circle) in the area of the new lesion on the right (Figures 1E,F). MR spectroscopy within the right hemispheric lesion showed a high tissue lactate level with slightly reduced NAA peaks compared to an unaffected region in the right frontal lobe (Figure 1I). The MR blood flow image showed also some heterogeneity reflecting old (Figure 1H, arrow) and new lesions (Figure 1H, circle).