Clinical condition: ataxia

Duration of ataxia (adult or child)	MRI head	MRI cervical, thoracic and lumbar spine	MRI cervical spine	CT head	CT head without contrast	MRA head	MRA head and neck	MR spectroscopy head (MRS)	CTA head and/or neck
Slowly progressive or chronic^*	8	7^a	X	5	X	X	X	2	X
Acute (< 3 hours) as a suspected stroke^†	8^b^,^c	X	5^g	8^b^,^d	X	X	8^b	2	8^b
Acute or subacute as a suspected infection	8	X	6^a	5^e	4	5	X	6^f	5
Acute following head trauma^‡	8	X	X	6^e	9	X	6	X	6

Note:—Rating Scale: 1, least appropriate; 9, most appropriate.
* FDG-PET brain received a rating of 3.
† See the ACR Appropriateness Criteria topic for cerebrovascular disease.
‡ MRI neck received a rating of 6.
^a Ataxia can be of spinal origin. Consider if brain imaging is negative or inconclusive.
^b MR preferred if treatment is not unreasonably delayed. Combined vascular and cerebral evaluation should be considered.
^c Fat saturated T1 axial images.
^d CT perfusion is less accurate in the posterior fossa.
^e CT temporal bone may be useful when skull-based or middle ear disease suspected.
^f May help distinguish abscess from other masses.