PMC9426857_01
Brain MRI in an 11-year-old male castrated domestic shorthair cat (Case 1) 3 months after the diagnosis of systemic blastomycosis and after experiencing two seizures after the latest antifungal treatment. Transverse T2-weighted (A), (D), and (G), T1-weighted (B), (E), and (H), and postcontrast T1-weighted (C), (F), and (I) images. (A)-(C) A round  0.8-cm diameter nodule is associated with the ventral aspect of the left temporal lobe (arrows) which is iso-to slightly hypointense to gray matter, with a hyperintense rim on T2-weighted image (A), slightly hypointense on T1-weighted image (B), and has strong and homogeneous contrast enhancement (C). There is moderate indistinct perilesional T2 hyperintensity, consistent with perilesional edema. (D)-(E) A second well-circumscribed  0.4-cm diameter T2 hypointense (A) and T1 isointense (B) lesion is associated with the right cerebellar hemisphere and exhibits moderate ring enhancement (C) following contrast medium administration (arrowheads). (G)-(I) A third  0.2-cm diameter ring-enhancing lesion is noted in the cerebellar vermis [(I), arrowhead], not seen on the precontrast images.
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F1
On MRI of the brain, three separate intra-axial lesions were identified (Figure 1).
Repeat MRI examination of the cat in Figure 1 (Case 1), 4 years and 4 months after the initial MRI study. Transverse T2-weighted (A), T2-FLAIR (B), T1-weighted (C), diffusion-weighted imaging [DWI, (D)] and corresponding apparent diffusion coefficient (ADC) map (E), and postcontrast T1-weighted GRE with fat suppression (F) images at the level of the tympanic bullae and temporal lobes, and transverse T2-weighted (G), T2*-weighted GRE (H), and postcontrast T1-weighted (I) images at the level of the cerebellum. (A)-(F) There is a new finding of an  1.2 x 1.4 cm ovoid mass in the right temporal lobe (solid arrows) which is predominantly T2, T2-FLAIR, and T1 isointense to gray matter with a small centrally located T2 hyperintense and T1 hypointense focus which does not suppress on T2-FLAIR [(A)-(C)]. The lesion is hypointense both on DWI and ADC maps [(D), (E)]. There is marked perilesional T2 and FLAIR hyperintensity following the white matter tracts of the right cerebral hemisphere (*) with a moderate to marked mass effect characterized by compression of the right lateral ventricle, leftward midline shift, and compression of the mesencephalon (+). Following contrast medium administration, the mass displays marked heterogeneous contrast enhancement (F). Mild focal pachymeningeal contrast enhancement is identified adjacent to the lesion (dashed arrow). An incidental small amount of fluid is noted within the bilateral tympanic bulla. (G)-(I) An  0.2-cm diameter well-defined T2 hypointense ovoid nodule is observed in the region of the previously seen cerebellar hemispheric lesion and is decreased in size from previous [(G), arrowhead]. This lesion is associated with a susceptibility artifact on T2*-weighted images (H) and has mild rim contrast enhancement (I).
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F2
PMC9426857_02
Brain MRI in a 3-year-old domestic shorthair cat (Case 2) following a diagnosis of ocular blastomycosis and with concern for intracranial involvement. Transverse (A), dorsal (B), and midline sagittal (C) postcontrast T1-weighted images; transverse T2-weighted images [(D) and (G)], transverse T1-weighted images before [(E) and (H)] and after [(F) and (I)] contrast medium administration. There is severe thickening, diffuse heterogeneous alteration in signal intensity, abnormal contrast enhancement of the periocular and tissues, thickening and enhancement of the wall of the globe, and retinal detachment [(A) and (B)]. There is diffuse thickening of the right optic nerve [(B), arrow] and marked enlargement of the optic chiasm [* in (B), (C), (F), and (I)]. A round 0.5-cm diameter intra-axial nodule is associated with the caudal aspect of the right frontal lobe [arrowheads, (D)-(F)] and an irregularly shaped  0.8 cm x 0.7 cm nodule is associated with the left parietal lobe [(G)-(I), arrowheads]. Both lesions are iso- to mildly hypointense to gray matter on both T2 and T1-weighted images [(D), (E), (G), (H)]. Bordering the lesions and extending extensively throughout the cerebral white matter bilaterally, there are parenchymal hyperintensities consistent with vasogenic edema. There is evidence of increased intracranial pressure characterized by attenuation of the CSF signal in the cerebral sulci, compression of the lateral ventricles, a mild midline shift, and caudal transtentorial and foramen magnum herniations [(C), dashed arrows].
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F3
Due to concern for intracranial involvement, MRI of the brain was performed (Figure 3).
PMC9426857_03
Brain MRI in an estimated 7-year-old cat (Case 3) with presenting complaints of head pressing and progressive neurologic deficits. Transverse T2-weighted (A), T2-FLAIR (B), T2*-weighted GRE (C), T1-weighted (D), diffusion-weighted imaging [DWI, (E)] and corresponding ADC map (F), and postcontrast T1-weighted images in the transverse (G), dorsal (H), and sagittal (I) planes. (A)-(F) There is an  1-cm diameter mass associated with the periphery of the right temporal lobe, in contact with the dural surface (arrows). The lesion is T2, T2-FLAIR, and T1 iso- to mildly hypointense to gray matter [(A), (B), (D)], is not associated with susceptibility artifact on T2*-weighted image (C), and is hypointense both on DWI and ADC maps [(E) and (F)]. There is marked perilesional T2 hyperintensity extending along the white matter tracts of the right cerebral hemisphere, consistent with vasogenic edema, resulting in compression of the right lateral ventricle, and a midline shift toward the left. A small volume of fluid is present in the nasopharynx, considered incidental. (G)-(I) Following contrast medium administration, the mass shows strong and fairly homogeneous contrast enhancement. The majority of the lesion is centered on brain parenchyma, with acute angles between the ventral, rostral, and caudal aspects of the mass and the calvarium. At the dorsal aspect of the mass, there is mild focal thickening and contrast enhancement of the pachymeninges [(G), dashed arrow].
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F4
On MRI examination of the brain, there was an  1-cm diameter mass associated with the periphery of the right temporal lobe, in contact with the dural surface (Figure 4).