Angiogram-negative subarachnoid hemorrhage in the era of three dimensional rotational angiography

BackgroundThree dimensional rotational angiography (3DRA) is a powerful method for depicting intracranial vascular lesions because of its 3D imaging capability. The purpose of this study was to analyse if 3DRA had reduced the incidence of angiogram-negative subarchnoid haemorrhage (SAH) and which type of aneurysm tended to be overlooked with conventional digital subtraction angiography.MethodAngiogram-negative SAH was defined as present in those patients with SAH who had no demonstrable lesion revealed by more than two adequate cerebral angiograms. From January 1, 1992, to December 31, 2004, angiography was performed on 247 patients at the Yamaguchi University Hospital. Digital subtraction angiography (DSA) alone was used for 105 patients (DSA group) from 1992 to 2000. After the technology of 3DRA was introduced to our hospital in 2000, 142 patients were evaluated by 3DRA and DSA together (3DRA group).FindingsThe incidence of angiogram-negative SAH was 9/105 (8.6%) in the DSA group and 6/142 (4.2%) in the 3DRA group. 3DRA revealed six aneurysms not depicted by the conventional DSA, including a basilar tip aneurysm, anterior cerebral artery aneurysm and a basilar tip aneurysm originating from a previously clipped aneurysm.ConclusionThree dimensional RA is more sensitive in detecting aneurysms, but in our study still produced a 4.2% rate of angiogram-negative SAH. Three diemensional RA has some advantages for evaluation, especially of complicated sites and previously clipped aneurysms because of its three dimensional imaging capability.