Comparison of Morphology of Intracranial Aneurysms on Computed Tomography Angiography with Digital Subtraction Angiography and Intraoperative Findings-A Single Centre Experience

Introduction: Multi-Detector Computed Tomography (MDCT) angiography is a non-invasive technique in emergency screening of Subarachnoid Haemorrhage (SAH) for accurately detecting aneurysms. Digital Subtraction Angiography (DSA) remains the gold standard for diagnosis of intracranial aneurysm. Computed Tomography Angiography (CTA) is being increasingly used for this purpose and can presently replace DSA as the most reliable means to detect intracranial aneurysms in SAH. Aim: To characterise the morphology of intracranial aneurysms with CTA and to compare it with DSA and intraoperative findings. Materials and Methods: This analytical study includes patients suspected to have intracranial aneurysm and underwent CTA on 16 slice MDCT scanner. Post-processing Multiplanar Reconstructions (MPR), 3D Volume Rendering (VR) and Maximum Intensity Projection (MIP) were performed. The findings of CTA findings were compared with DSA and intraoperative/indocyanine angiography images obtained by Leica neurosurgical operating microscope, wherever possible. Morphological parameters: size (dome, neck, height, dome to neck ratio, aspect ratio in saccular and length, diameter in fusiform), shape, lobulation, tit, location, thrombosis/calcification, blood vessels arising, ruptured or not, grade of SAH (modified CT Fischer score) and vasospasm (grade, number/location of vasospastic segments) were assessed and compared with DSA and intraoperative findings. Results: In 71 patients, 97 intracranial aneurysms were studied. Saccular aneurysm was the most common and anterior communicating artery (ACOM) was the most common location. Significant correlation of dome: neck and aspect ratios between CTA and DSA (p=0.0089) was noted. The sensitivity, Positive Predictive Value (PPV) and accuracy of CTA for aneurysm >3 mm was 100%. Two aneurysms <3 mm were missed on CTA, but detected by DSA. Therefore, for aneurysms <3 mm in size, sensitivity was 92.86%, with a PPV and accuracy of 96.3% and 89.66%, respectively. Overall sensitivity of CTA irrespective of size was 97.9%, with 97.9% PPV and 95.9% accuracy was observed. Conclusion: MDCTA with 3D reconstructions and volume rendering is the ideal first line imaging modality in non-traumatic SAH for detection of aneurysm with a high degree of accuracy. DSA can be used to diagnose tiny aneurysms <3 mm if missed on CTA, if there is a high degree of suspicion.