Role of noncontrast head CT in the assessment of vascular abnormalities in the emergency room

Abstract

Noncontrast CT of the head is a widely used noninvasive investigation for a variety of acute and chronic neurological conditions. Since CT head without contrast is usually the first and often the only investigation in the emergency room for many neurological symptoms, it is imperative to detect subtle vascular changes, which in many patients can be life-saving. The vascular abnormalities may present with increased density and/or size of the vessels, filling defects, and be associated with parenchymal and bony changes. In this article, we present examples of several vascular pathologies which can be identified on the noncontrast CT of the head, and learn imaging and interpretation techniques to help recognize what often are nebulous changes. While some of the findings are diagnostic by themselves and others subtle, any suspicious abnormality should be followed with dedicated vascular imaging such as CT/MR angiogram, venogram, or catheter angiogram for confirmation and better characterization.

Brain computerized tomography reading in suspected acute ischemic stroke patients: what are essentials for medical students?

“…Identify the image symmetry of the bilateral hemispheres Extra-axial lesions Epidural and subdural space [29] Interhemispheric fissure Sylvian fissure Ventricles Lateral ventricles Anterior and posterior horns of lateral ventricles Temporal horns of lateral ventricles Fourth ventricle Specific regions Cerebellopontine angle Sella lesion Vessels Hyperdense MCA sign [15] Hyperdense BA sign [14] Veins: Dense sinus signs of CVT [22] Orbital cavity (Ophthalmic vein enlargement, orbital mass) [17] Intra-axial lesion ACA territory PCA territory MCA territory, basal ganglia and thalamus [24] Borderzone areas [26] MCA-ACA border zone MCA-PCA border zone Temporal lobes Mass effect, mid-line shift, or herniation [25] Brain stem Mid-brain Pons Medulla Cerebellum: symmetry, hyperdensity, hypodensity of the cerebellar hemispheres.5. Identify abnormal densities on brain CT [27, 28] Identify hyper-density lesions Hematoma density Physiological calcification density Identify low density lesions Very low density (CSF and old lesions) Low density (edematous lesion and recent infarcts) Identify heterogeneous density lesions Hematoma with blended sign [18], whirl sign [19], spot sign [21], or black hole sign [20] Low density mixed with hyper-density (hemorrhagic infarct) Identify mass-like lesions ABBBC (Air-Blood-Bone-Brain-CSF) mnemonic [30] ACA anterior cerebral artery, CSF cerebrospinal fluid, CT computerized tomography, CVT cerebral venous thrombosis, ID identification, MCA middle cerebral artery, PCA posterior cerebral artery…”