Neuroimaging of Hemorrhage and Vascular Defects

Abstract

Summary: Intracranial hemorrhage is the third most common cause of stroke and involves the accumulation of blood within brain parenchyma or the surrounding meningeal spaces. Accurate identification of acute hemorrhage and correct characterization of the underlying pathology, such as tumor, vascular malformation, or infarction, is a critical step in planning appropriate therapy. Neuroimaging studies are required not only for diagnosis, but they also provide important information on the type of hemorrhage, etiology, and the pathophysiological process. Historically, computed tomography (CT) scan has been the diagnostic imaging study of choice; however, there is growing evidence suggesting that magnetic resonance imaging (MRI) is at least as sensitive as CT to detect intraparenchymal hemorrhages in the hyperacute setting, and actually superior to CT in the subacute and chronic settings. Unique MRI and CT characteristics differentiate secondary causes of hemorrhage from the more common hypertensive hemorrhage. Baseline and serial studies can be used to identify patients who might benefit from acute interventions. In addition, new imaging modalities, (such as magnetic resonance spectroscopy, diffusion tensor imaging, and 320-row CT) are promising research techniques that have the potential to enhance our understanding of the tissue injury and recovery after intracranial hemorrhages.

The Active Extravasation of Contrast (Spot Sign) Depicted on Multidetector Computed Tomography Angiography Might Predict Structural Vascular Etiology and Mortality in Secondary Intracranial Hemorrhage

“…The ICH is accompanied by high rates of mortality, disability, and neurological sequelae. 1,2 Primary ICH is usually caused by systemic arterial hypertension (SAH) or amyloid angiopathy. However, several conditions other than SAH and amyloid angiopathy can also promote ICH.…”

“…These conditions are known as secondary hemorrhage and include arteriovenous malformation (AVM), aneurysm, venous thrombosis, arteriovenous fistula, vasculitis, brain tumours, thrombolytic therapy, coagulation disorders, and drug abuse. 2 In both primary and secondary ICH, several features have been described as predictors of functional outcome after ICH, including the hematoma volume on presentation, midline shift, infratentorial location, intraventricular extension, and hydrocephalus. 3,4 The widespread availability, fast acquisition, and lower cost of multidetector computed tomography (MDCT) has made this technique the preferred method for detecting ICH and, more recently, has also allowed the prognoses of ICH patients to be assessed.…”

Neuroimaging in Intracerebral Hemorrhage

“…The varied components of the hematoma give it a heterogeneous appearance. The atenuation of blood with a normal hematocrit (45%) is much higher (56 Hounsield units-HU) than gray mater (37-41 HU) and white mater (30-24 HU) resulting in the 'brighter' or 'whiter' region in patients with a normal hematocrit [4] (Table 1, Figure 1). …”

The role of advanced neuroimaging in intracerebral hemorrhage

“…These properties also permit the potential assessment of the risk of hemorrhage prior to ictus based on tissue health and provide another modality for use in the diagnosis of hemorrhagic strokes of unclear etiology or type. 43 In this article we discuss the current and potential uses for functional imaging as it pertains to ICH ( Table 1).…”