Magnetic resonance imaging has a higher diagnostic yield.

In a retrospective chart review, investigators determined the diagnostic yield (acute and subacute findings) of head computed tomography (CT) in 448 adult patients who presented to a single urban academic emergency department (ED) with acute dizziness (vertigo, lightheadedness, disequilibrium, presyncope).

The overall diagnostic yield of head CT was 2.2%, with emergent findings detected on only 1.6% of the scans. Of the 448 patients, 104 underwent follow-up imaging, most often with magnetic resonance imaging or angiography (MRI/A; 78.7%). Seventeen patients (13%) had findings on follow-up imaging that changed or confirmed the diagnosis; most of the changes in diagnosis were ischemic stroke that was not identified on initial CT. MRI was the follow-up modality that most often led to a change in diagnosis (16% of the time).

Comment: These findings are consistent with the recommendation from the American College of Radiology and American College of Emergency Physicians that head CT be used in the evaluation of acute dizziness only when hemorrhage is the suspected cause. When an intracranial cause of dizziness is suspected (unless the patient presents with trauma or severe headache suspicious for hemorrhage), MRI is the test of choice.

Source: Journal Watch Emergency Medicine