Diagnostic accuracy of CT angiography with matched mask bone elimination for detection of intracranial aneurysms: comparison with digital subtraction angiography and 3D rotational angiography

Abstract

Background and purpose: Our aim was to determine the diagnostic accuracy of multisection CT angiography combined with matched mask bone elimination (CTA-MMBE) for detection of intracranial aneurysms compared with digital subtraction angiography (DSA) and 3D rotational angiography (3DRA).

Materials and methods: Between January 2004 and February 2006, 108 patients who presented with clinically suspected subarachnoid hemorrhage underwent both CTA-MMBE and DSA for diagnosis of an intracranial aneurysm. Two neuroradiologists, independently, evaluated 27 predefined vessel locations in the CTA-MMBE images for the presence of an aneurysm. After consensus, diagnostic accuracy of CTA was calculated per predefined location and per patient. Interobserver agreement was calculated with kappa statistics.

Results: In 88 patients (81%), 117 aneurysms (82 ruptured, 35 unruptured) were present on DSA. CTA-MMBE detected all ruptured aneurysms except 1. Overall specificity, sensitivity, positive predictive value, and negative predictive value of CTA-MMBE were 0.99, 0.90, 0.98, and 0.95 per patient and 0.91, 1.00, 0.97, and 0.99 per location, respectively. Sensitivity was 0.99 for aneurysms >/=3 mm and 0.38 for aneurysms <3 mm. Interobserver agreement for aneurysm detection was excellent (kappa value of 0.92 per location and 0.80 per patient).

Conclusion: CTA-MMBE is accurate in detecting intracranial aneurysms in any projection without overprojecting bone. CTA-MMBE has limited sensitivity in detecting very small aneurysms. Our data suggest that DSA and 3DRA can be limited to the vessel harboring the ruptured aneurysm before endovascular treatment, after detection of a ruptured aneurysm with CTA.

Fig 1.

Illustration of a MMBE procedure in a 44-year-old woman with a ruptured right middle cerebral artery (MCA) aneurysm. A–C, Axial images of nonenhanced low-dose CT, CTA, and CTA after MMBE. D, Axial MIP obtained after MMBE shows 2 right MCA aneurysms, 1 left MCA aneurysm, and a basilar tip aneurysm (arrowheads). E, Coronal MIP image of the left MCA shows a 2.8-mm MCA aneurysm (arrow) and deceptive thickening of the MCA bifurcation. F, DSA shows the same aneurysm (arrow) as in E, with an additional 1.6-mm MCA aneurysm (large arrowhead). G, 3DRA more clearly shows both MCA aneurysms (arrow and large arrowhead). H, Composite image of three 3DRAs of both ICAs and the right vertebral artery shows all 5 aneurysms (small arrowheads and large arrowhead).

Fig 2.

A 77-year-old woman with SAH and a false-positive-aneurysm finding on CTA. A, Axial CTA-MMBE image shows near complete bone removal as only the auditory ossicles (arrowheads) are not masked. B and C, Axial MIP and coronal MIP with small bone remnants of auditory ossicles (arrowheads), which do not hinder evaluation. D, Coronal MIP of a volume of interest with a small bulge of the right ICA interpreted as a small aneurysm (arrow). This infundibulum was mistaken for an aneurysm because the posterior communicating artery (PcomA) is not visible. E and F, DSA and 3DRA show the infundibulum of small PcomA (arrow).