Which imaging modalities are most effective for diagnosing a brain abscess in primary care settings?

In primary care settings, the most effective initial imaging modality for suspected brain abscess is a contrast-enhanced computed tomography (CT) scan. CT scanning is widely accessible, rapid, and effective at detecting ring-enhancing lesions typical of brain abscesses, making it the preferred first-line investigation when clinical suspicion arises ¹. Magnetic resonance imaging (MRI) with contrast is more sensitive and specific than CT for diagnosing brain abscesses, particularly in early stages and for differentiating abscesses from other intracranial lesions, but it is less readily available in primary care and often requires referral to secondary care. Therefore, MRI is generally reserved for cases where CT findings are inconclusive or for further characterisation after initial CT ¹; (Mathisen and Johnson, 1997). Ultrasound is not effective for diagnosing brain abscesses due to poor penetration of the skull and limited resolution for intracranial pathology. Thus, it is not recommended in this context ¹; (Sharath Kumar et al., 2022).

In summary, primary care clinicians should prioritise urgent referral for a contrast-enhanced CT scan when a brain abscess is suspected based on clinical features, with MRI reserved for specialist evaluation. This approach balances accessibility, diagnostic accuracy, and timeliness in the primary care setting ¹; (Calfee and Wispelwey, 2000).