PMC4718303_01
61-year-old woman after suffering a stroke. (A) Axial PET images revealed a marked reduction in cortical and subcortical glucose metabolism in the right hemisphere. (B) On axial DWI, the frontal lesion demonstrated high signal illustrating a significant diffusion restriction (arrow). (C) Axial FDG PET fused with FSE T2WI of this patient showed the right hemispheric infarction with hypometabolism. (D) Fused PET/MRI images demonstrated hypometabolism in the contralteral cerebellar hemisphere (arrow). (E) Fused PET/CT images also demonstrated hypometabolism in the contralteral cerebellar hemisphere but with low soft-tissue resolution. (F) Axial FSE T2WI confirmed no significant changes or sign of atrophy in the cerebellum. CT = computed tomography, DWI = diffusion-weighted imaging, FDG = fluorodeoxyglucose, FSE = fast spin echo, MRI = magnetic resonance imaging, PET = positron emission tomography.
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F1
Axial PET images revealed a marked reduction in cortical and subcortical glucose metabolism in the right hemisphere (Figure 1A). On axial diffusion-weighted image, the frontal lesion demonstrated high signal illustrating a significant diffusion restriction (Figure 1B). FDG PET fused with FSE T2 images of this patient showed the infarction of right hemispheric (Figure 1C). Fused PET/MRI (Figure 1D) and PET/CT (Figure 1E) images demonstrated hypometabolism in the contralteral cerebellar hemisphere. T2 image confirmed no significant changes or sign of atrophy in the cerebellum (Figure 1F). The patient was eventually proved to acute cerebral infarction associated with CCD.
PMC4718303_02
A 49-year-old man confirmed recurrence after a resection of frontal lobe glioma. (A) Axial CT images revealed ill-defined hypodensity in the surgical site (arrow), and that scattered calcified speckles around the lesion (arrowhead). (B) Postoperative site showed predominantly reduced uptake as seen on the axial PET/CT image, with a small focus of mildly increased uptake within. (C) T1-weighted CE-MRI exhibited in the bilateral frontal lobe an area of contrast enhancing lesion suggestive for recurrence of glioma. (D) Fused PET/MRI images demonstrated focal hypermetabolism in the frontal lobe which corresponds to lesion after enhancement of gadolinium. (E) Axial FDG PET fused with T1-weighted CE-MRI of this patient also showed hypometabolism in the homolateral basal nuclei and thalamus (arrow). (F) Coronal PET/MRI images show a marked reduction in cortical and subcortical glucose metabolism in the right cerebellar hemisphere (arrowhead) associated with a hypometabolism of the contralateral hemisphere (arrow). CT = computed tomography, FDG = fluorodeoxyglucose, MRI = magnetic resonance imaging, PET = positron emission tomography.
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F2
Axial CT images revealed ill-defined hypodensity in the surgical site, and that scattered calcified speckles around the lesion (Figure 2A). Postoperative site showed predominantly reduced uptake as seen on the axial 18F-FDG fused PET/CT image, with a small focus of mildly increased uptake within (Figure 2B). T1-weighted CE-MRI of the brain (Figure 2C), subsequently performed with hybrid PET/CT-MRI scanner, exhibited in the bilateral frontal lobe an area of contrast enhancing lesion suggestive for recurrence of glioma, which corresponds to lesion uptake of radiotracer in the fused PET/MRI image (Figure 2D). T2 image and FLAIR MRI done at the same time demonstrated no significant change (not shown). Coronal PET/MRI images show a marked reduction in cortical and subcortical glucose metabolism in the right cerebellar hemisphere associated with a hypometabolism of the contralateral hemisphere (Figure 2F), which also confirmed a mild degree of cerebella atrophy, as slight widening of the right cerebellar hemisphere sulci. The recurrent glioma was confirmed on postoperative histopathology.
PMC4718303_03
A 73-year-old woman confirmed the diagnosis of brain metastases. (A) Axial fused PET/CT showed a ring-like area of 18F-FDG uptake in the left frontal lobe with ill-defined margin (arrow). (B) Axial FSE T2WI exhibited in the left frontal lobe an area of high signal suggestive for perilesional edema (arrowhead). (C) Axial FDG PET fused with FSE T2WI showed the corresponding peritumoral edema with hypometabolism. (D) The axial FDG PET/MRI image of this patient showed hypometabolism in the homolateral basal nuclei (arrowhead) and thalamus (arrow). (E) Fused PET/MRI images show a marked reduction in cortical and subcortical glucose metabolism in the right cerebellar hemisphere. (F) The ASL perfusion image done at the same time also showed the right cerebellar hypoperfusion (arrow), in keeping with the phenomenon of CCD. ASL = arterial spin-labeling, CCD = crossed cerebellar diaschisis, FDG = fluorodeoxyglucose, MRI = magnetic resonance imaging, PET = positron emission tomography.
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F3
Transaxial fused PET/CT showed a ring-like area of 18F-FDG uptake in the left frontal lobe with ill-defined margin, and glucose metabolism in the bilateral cerebral cortex appear to be similar (Figure 3A). The axial FSE T2 image (Figure 3B), performed with hybrid PET/CT-MRI scanner, exhibited in the left frontal lobe an area of high signal suggestive for perilesional edema, which corresponds to low uptake of radiotracer in the fused PET/MRI image (Figure 3C). FDG PET fused with T2-weighted image of this patient also showed hypometabolism in the homolateral basal nuclei and thalamus (Figure 3D), whereas the T2-weighted image alone demonstrated no specific tumor infiltration and atrophy of cortex (not shown). Fused PET/MRI images show a marked reduction in cortical and subcortical glucose metabolism in the right cerebellar hemisphere (Figure 3E). In particular, the ASL (arterial spin-labeling) perfusion image done at the same time also showed the right cerebellar hypoperfusion, in keeping with the phenomenon of crossed cerebellar diaschisis (Figure 3F).