Detection and Evaluation of Intracranial Aneurysms in the Posterior Fossa by Multidetector Computed Tomography Angiography – Comparison with Digital Subtraction Angiography

INTRODUCTION: Posterior fossa hemorrhages are not so frequent but as posterior cranial fossa space is narrow and has many vital structures, even a small amount of bleed can lead to compression of brain stem and serious consequences. Identification and planning management of cause of bleed requires angiogram. Digital subtraction angiography (DSA) being invasive modality but is gold standard, so noninvasive computed tomography angiography (CTA) is compared to detect cause of bleed in the posterior fossa in this study. MATERIALS AND METHODS: From January 2017 to October 2018, all patients with posterior fossa bleed who underwent CTA and DSA for evaluation were compared regarding identification of aneurysm as cause of bleed. RESULTS: A total of 49 patients were evaluated in this study during study duration, of which 26 (53%) were male and 23 (47%) were female. Out of 49 patients evaluated, 47 patients had aneurysms detected on DSA. Of 25 patients who underwent both procedures, 23 patients had aneurysms, and correct diagnosis was made with CTA in 24 out of 25 aneurysms. One aneurysm missed by CTA was close to bony structure. DISCUSSION: With advancement of CTA technology, sensitivity of detecting intracranial aneurysms has increased to >96%. The overall sensitivity in detecting aneurysms is 96% with sensitivity in detecting aneurysms >4 mm being 100%. The sensitivity of CTA for smaller sized aneurysms is low which is attributed partially to lower spatial resolution of CT compared to DSA. CONCLUSION: CTA is a simple, fast, and noninvasive imaging modality that can be used to detect and characterize intracranial aneurysms in the posterior fossa.