The MINIFLOW Study: evaluating non-invasive imaging modalities for follow-up of flow diverter treated cerebral aneurysms

BACKGROUND: This study aimed to evaluate subtraction CT angiography (sCTA) and MR angiography (MRA) as potential non-invasive alternatives for digital subtraction angiography (DSA) for the follow-up of intracranial aneurysms treated with flow diverter stent (FDS). METHODS: Forty patients with intracranial aneurysms treated with FDS were enrolled between August 2019 and November 2024 to evaluate the diagnostic performance of sCTA and MRA in assessment of aneurysm occlusion after FDS treatment. All patients were scheduled to undergo sCTA, MRA and DSA within 24 hours. sCTA was performed on a 160-row detector ultra-high resolution CT scanner. TOF MRA pre- and post-contrast, DWI and T1 sequences were acquired using a 3T MRI scanner. All studies were assessed by two blinded observers. Sensitivity, specificity, negative and positive predictive values were calculated for aneurysm occlusion. Interrater variability was assessed using the Cohen?s kappa. RESULTS: Compared to DSA, specificity for evaluation of complete aneurysm occlusion was high for sCTA (88%), TOF MRA (92%) and post-contrast TOF MRA (83%). Post-contrast TOF MRA had the highest sensitivity (93%) and negative predictive value (95%). Interrater variability was good to excellent for all three modalities. Complications associated with DSA were observed in five patients; in one case, a 24-hour hospital admission was necessary for observation. CONCLUSION: sCTA, pre- and post- contrast TOF MRA seem to be appropriate for evaluating aneurysmal occlusion after FDS treatment, considering the high specificity and negative predictive value and non-invasive nature.