Getting a clear picture of the brain - Neuroimaging in dementia

If you search online or talk to your doctor, you will find different ways to examine your brain. When you break your leg, the first exam that a doctor would think of is a conventional X-Ray. However, an X-ray works for bones, but it would not show brain tissue damage.

Neuroimaging with a head computed tomography (CT) or MRI scan is unequivocally more helpful in patients with cognitive impairment and/or neurologic deterioration.

The American Academy of Neurology recommends structural neuroimaging with either a non-contrast head CT or MRI in the routine initial evaluation of all patients with dementia. Although, some experts challenge the usefulness of neuroimaging as a standard examination tool. It is, in any case, advisable to obtain neuroimaging when you or your loved one have atypical symptoms, unusual neuropsychological test results, acute onset of symptoms, or when imaging helps rule out other causes of cognitive problems.

Neurologists, who may only see a person once or for a limited time, will usually obtain imaging on a patient referred from primary care. In contrast, a primary care clinician who has known the patient and their family for a while may order imaging more selectively.

MRI or CT?

In most cases, MRI is preferred over CT because it is more sensitive for a broad range of brain tissue changes. Additionally, MRI avoids exposure to potentially harmful radiation.

A CT scan is the best option when the patient is claustrophobic or has a pacemaker or ferromagnetic implant (i.e., hip implant). MRIs usually take longer, and patients must lie still during the exam. However, if necessary, patients who are anxious or restless can be sedated for MRI.

Contrast or Non-contrast imaging?

Noncontrast brain imaging is sufficient for the routine evaluation of patients with suspected dementia. Intravenous contrast poses risks of allergic reactions and can impair kidney function.