Table 2.

Specific MRI features evaluated during groups classification.

MRI features	Types	Evaluation method
Forebrain volume	Decreased	Subjectively defined as volume loss leading to enlargement of the ventricles and subarachnoid spaces, and decreased interthalamic height. Grading of the atrophy was performed subjectively ranging from mild to severe.
	Normal
	Increased	Increased brain volume or brain swelling was considered when there was loss of the normal T2W hyperintense signal from the CSF within the cerebral sulci; and/or when presence of transtentorial and cerebellar herniation.
Cerebellar volume	Decreased	Atrophy was defined subjectively as volume loss leading to enlargement of the fourth ventricle and increase conspicuity of the CSF between the cerebellar folia. Grading of the atrophy was performed subjectively ranging from mild to severe.
	Normal
	Increased	Increased cerebellar volume was considered when loss of the CSF signal within the cerebellar sulci, decreased size of the fourth ventricle and/or when there was the presence of cerebellar herniation or caudal displacement of the uvula.
Grey/white matter definition	Decreased	This was evaluated in general, but as reference the parietal lobes and basal nuclei were specifically noted.
	Normal
	Increased
Anatomical location	Grey matter	Detailed description of the anatomical location of the lesions within either the grey matter, white matter or both based on previously published veterinary neuroanatomy textbooks (27, 28).
	White matter
	Both
Distribution	Diffuse	Distribution was classified as diffuse when extensive involvement of the white or grey matter.
	Focal/multifocal	Distribution was classified as focal/multifocal when affecting a specific anatomical region.
Lesion margination	Well-defined	Lesion margination was characterised subjectively as well or poorly circumscribed.
	Ill-defined
Signal intensity	Hyperintense	Description of the signal intensity pattern of the lesions in all sequences compared to normal white matter (T2W, FLAIR, and T1W pre- and post-contrast).
	Isointense
	Hypointense
Contrast enhancement		Evidence of contrast enhancement (absent, mild, moderate, and severe) and its pattern (homogeneous, heterogeneous, and rim-like enhancement) were evaluated.
Meningeal enhancement	Pachymeningeal	Enhancement of the dura mater without extension into the cerebral sulci.
	Leptomeningeal	Enhancement of the arachnoid and pia mater which extends into the sulci.
Lentiform nuclei		The T1W signal intensity of the lentiform nuclei was compared between patients with hepatic encephalopathy to patients with other metabolic conditions.