Background and Purpose 3D black blood (BB) MRI using a T1 sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) sequence allows high resolution, vessel wall imaging to evaluate the intracranial arterial wall and its associated pathologies. We investigated the diagnostic features and accuracy of 3D BB MRI in the detection of intraluminal arterial thrombosis.
Material and Methods We retrospectively identified fifteen patients with intracranial arterial thrombosis that underwent 3D BBMRI with non-enhanced and contrast enhanced high resolution T1 SPACE sequences. 3D BBMRI findings were evaluated by 2 independent neuro-radiologists blinded to all other angiographic studies, conventional MRI sequences, and clinical indications for imaging. Nineteen total intracranial vessel segments (ICA terminus, A1/A2 ACA, M1/M2 (superior and inferior division) MCA, vertebral, basilar, and P1/P2 PCA) per patient were evaluated and graded on a three-point scale (grade 0–2) [Table] for intraluminal TI SPACE hyperintensity and contrast enhancement. Images were considered positive for arterial thrombosis when focal intraluminal T1 SPACE hyper-intense signal and/or enhancement on 3D BBMRI was graded as 1 or 2 by the independent readers. Arterial occlusion was confirmed by digital subtraction angiography (DSA) or computed tomographic angiography (CTA). In limited cases (n=4) without DSA/CTA availability, susceptibility weighted imaging (SWI) in combination with time of flight (TOF) MR angiography (MRA) confirmed the diagnosis of complete vessel occlusion.
Results Fifteen patients (6M:9F, mean age 63±10 years, range 39–77 years) with 18 intracranial arterial occlusions were studied. The median interval between presentation and BBMRI scanning was 8 days (range 0–270 days). Fair inter-observer agreement for intraluminal T1 SPACE hyperintensity (unweighted Kappa=0.50) and excellent inter-observer agreement for contrast enhancement (unweighted Kappa=0.84) was noted. The sensitivity and specificity for intracranial arterial thrombosis of intraluminal T1 hyperintensity was 88.89% and 100% respectively and that of contrast enhancement was 94.45% and 100% respectively, taking Observer 1 as gold standard and Observer 2 as test when both partial and clear visualization (combined grades 1 and 2) suggested vessel thrombosis/occlusion.
Conclusion 3D BBMRI with T1 SPACE imaging is a valuable sensitive and specific technique for the evaluation of intracranial arterial thrombosis. This technique provides an adjunctive mechanism to confidently diagnose complete arterial occlusions in the setting of low resolution conventional MRI findings and absent flow enhancement on TOF-MRA imaging prone to overestimation.
Disclosures A. Al-Smadi: None. A. Elmokadem: None. A. Shaibani: None. M. Hurley: None. M. Potts: None. B. Jahromi: None. S. Anasari: None.
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