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 NICE NG232. 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 NICE NG232; Mathisen & 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 NICE NG232; 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 NICE NG232; Calfee & Wispelwey 2000.
Key References
- NG232 - Head injury: assessment and early management
- NG128 - Stroke and transient ischaemic attack in over 16s: diagnosis and initial management
- NG99 - Brain tumours (primary) and brain metastases in over 16s
- (Mathisen and Johnson, 1997): Brain abscess.
- (Calfee and Wispelwey, 2000): Brain abscess.
- (Sharath Kumar et al., 2022): Role of imaging in CNS infections.