The objective of this study is to measure the accuracy of multidetector CT angiography (MD CTA) in the detection of vascular abnormalities in patients <or=40 years with spontaneous intraparenchymal hemorrhage (IPH) presenting to the emergency department. After institutional review board approval, a retrospective study was performed of 43 consecutive patients <or=40 years, who presented to our emergency department with IPH and that were evaluated with MD CTA. MD CTA images were reviewed by a neuroradiologist to determine IPH location, presence of a vascular abnormality, and associated extraparenchymal hemorrhage. Diagnostic accuracy was measured comparing it to the available reference standards, which included conventional catheter angiogram (CCA), surgical macroscopic findings, and pathology results. Medical records were reviewed for risk factors and correlation with final diagnosis. MD CTA demonstrated an accuracy of 97.7%, with a sensitivity of 96.4% (95% CI 0.79-0.99) and a specificity of 100% (95% CI 0.74-0.99) for the detection of vascular abnormalities in young patients with IPH. Additionally, MD CTA had a PPV of 100%, and the NPV 93.8% in this population. Of the 43 patients included in the study, 28 patients (65%) had a causative vascular etiology for the IPH. Among the 28 patients with vascular etiologies for the IPH, 11 had an AVM (39.2%), nine a ruptured aneurysm (32.14%), seven dural venous sinus thrombosis (25%), and one had vasculitis (3.57%). MD CTA is highly accurate in the detection of vascular abnormalities in the setting of IPH, which as a group represents the most frequent etiology of IPH among patients age <or=40 years. MD CTA performed in the Emergency Department provides accurate, rapid and critical presurgical and premedical treatment information in young patients with IPH.