Subarachnoid Hemorrhage CT Scanning: Key Considerations and Best Practices

When diagnosing subarachnoid hemorrhage (SAH), non-contrast computed tomography (CT) of the brain remains the gold standard imaging modality. Early and accurate detection is critical, as timely intervention can significantly improve patient outcomes. Radiologists and clinicians must pay close attention to specific imaging features that indicate bleeding within the subarachnoid spaces.

Key Imaging Features to Evaluate

One of the primary indicators of SAH on a CT scan is hyperdensity observed in the cerebral sulci, gyri, and basal cisterns. These areas may show a "cast-like" or "fused" appearance due to blood accumulation—commonly referred to as subarachnoid cast formation. This pattern is especially noticeable in the anterior interhemispheric fissure, Sylvian fissures, and around the brainstem.

Assessing for Associated Intracranial Abnormalities

Besides identifying subarachnoid blood, it's essential to evaluate for other potential complications. Look for signs of epidural or subdural hemorrhage, which may present as lens-shaped or crescent-shaped hyperdensities, respectively. Changes in ventricular morphology, such as compression or distortion, could suggest increased intracranial pressure or hydrocephalus—a common secondary effect of SAH.

Another crucial aspect is assessing midline shift. Any deviation of the brain's midline structures may indicate mass effect from hematoma expansion or cerebral edema, both of which require urgent neurosurgical evaluation.

Clinical Correlation is Essential

Imaging findings should always be interpreted in conjunction with the patient's clinical history. Sudden onset of a severe headache—often described as "the worst headache of my life"—along with nausea, vomiting, or altered mental status, strongly supports the diagnosis of SAH. A detailed patient history, including trauma, hypertension, or known aneurysms, further guides diagnostic accuracy.

Patient Safety During Transport and Imaging

Patient handling during transport to and from the CT suite requires special care. Avoid abrupt movements or excessive jostling, as these can increase intracranial pressure and potentially worsen the hemorrhage. Use a stretcher with proper head support and ensure continuous monitoring of vital signs throughout the process.

During the scan, maintain constant observation of the patient's neurological status. Any deterioration—such as decreased responsiveness or respiratory changes—should prompt immediate medical intervention.

Optimizing Diagnostic Accuracy

To enhance detection, radiologists should adjust window settings appropriately to better visualize subtle blood deposits. Delayed scans may be necessary if initial imaging is inconclusive but clinical suspicion remains high. In such cases, lumbar puncture or CT angiography (CTA) may be warranted to confirm the diagnosis and identify potential sources like cerebral aneurysms.

In summary, a systematic approach to CT imaging in suspected subarachnoid hemorrhage—combining precise image analysis, clinical correlation, and careful patient management—plays a pivotal role in ensuring rapid diagnosis and effective treatment planning.