From the Guidelines
Get a Computed Tomography (CT) scan for dementia diagnosis when MRI is not available or contraindicated, as CT head without IV contrast is usually appropriate as the initial imaging in patients with cognitive decline and suspected dementia, including Alzheimer's disease, vascular dementia, and frontotemporal dementia 1.
Key Indications for CT Scan
- Onset of cognitive signs/symptoms within the past 2 years, regardless of the rate of progression
- Unexpected and unexplained decline in cognition and/or functional status in a patient already known to have dementia
- Recent and significant head trauma
- Unexplained neurological manifestations (new onset severe headache, seizures, Babinski sign, etc.), at onset or during evolution
- History of cancer, in particular if “at risk” for brain metastases
- Subject at risk for intracranial bleeding
- Symptoms compatible with normal pressure hydrocephalus
- Significant vascular risk factors
CT Scan Protocol
- Non-contrast CT is recommended 1
- Coronal reformations are encouraged to better assess hippocampal atrophy 1
Interpretation of CT Scans
- Semi-quantitative scales, such as the medial temporal lobe atrophy (MTA) scale, Fazekas scale, and global cortical atrophy (GCA), are recommended for routine interpretation of CT scans 1
- Quantification software is not recommended for routine clinical use pending larger studies demonstrating the added diagnostic value of these tools 1
From the Research
Computed Tomography (CT) Scan for Dementia Diagnosis
- A CT scan can be used to detect secondary, sometimes treatable causes of cognitive impairment, such as intracranial masses 2.
- The use of CT scans in dementia diagnosis is mainly for structural assessment of vascular lesions and degenerative changes 2.
- CT scans are recommended in selected cases to rule out treatable causes of dementia or to rule in cerebrovascular disease 3.
- CT scans can be used to exclude reversible and treatable causes of dementia, such as subdural hematoma and tumor 4.
- The finding of cortical or subcortical atrophy on CT does not necessarily indicate Alzheimer's disease (AD) 5.
- Hippocampal atrophy on CT provides a useful early marker for AD, although further study is required 5.
- CT brain imaging has a place in the diagnosis of dementia, particularly in atypical cases 6.
- Clinical guidelines can be developed for the application of CT in the diagnosis of dementia, with CT scans being more useful in cases where the diagnosis is uncertain or atypical 6.