Abstract WP117: Quantitative Susceptibility Mapping (QSM) and Vessel Wall Imaging (VWI) MRI Sequences in Identifying Subjects With Intracranial Aneurysms Who Have Microbleeds

Abstract

Background and Purpose: Sentinel symptoms of aneurysm’s micro - hemorrhage such as sentinel headache or cranial nerve (CN) neuropathies are associated with an increased risk of subarachnoid hemorrhage (SAH). We tested a new MRI protocol that may aid the identification of microbleeds associated with sentinel symptoms in patients with negative head CTs and lumbar punctures. Methods: Twenty-eight consecutive subjects with a total of 35 aneurysms were enrolled in this pilot study between March/2018 to July/2018. All subjects presented with sentinel symptoms, no evidence of SAH on head CT or spinal puncture. The MRI protocol included: MRA with gadolinium, high-resolution MR vessel wall imaging (MRI-VWI) and MR imaging quantitative susceptibility mapping (MRI-QSM). Two blinded neuroimaging experts reviewed every image to determine evidence of vessel-wall enhancement or positive MRI-QSM signal. A third adjudicator intervened in case of disagreement. Statistical differences were determined by Student t-test, as well as Mann-Whitney U test for non-parametric variables. Results: 35 CAs (100%) were analyzed with MR-VWI, whereas only 24 CAs (77.1%) on MRI-QSM due artifact form the skull base bone ( P =0.005). Fifty percent (50%) of anterior communicating artery aneurysm were not visualized on MRI-QSM. Four subjects presented with typical sentinel headache and twenty four with some cranial neuropathy. Interobserver agreement was 100% for MRI-QSM, while 83.9% in MRI-VWI (P=0.06). Disagreements derived from the differentiation between mild and no contrast enhancement in MR-VWI. MRI-QSM had a sensitivity of 100% and a specificity of 100% in micro-hemorrhage identification. Whereas, MRI-VWI had sensitivity of 100% and specificity of 51.9%. Conclusions: MRI-QSM is a valuable tool in identifying micro-hemorrhage in patients who present with sentinel symptoms. However, its main limitation is bone artifact in aneurysms close to bone structures.