Neuroimagen en el ictus agudo: búsqueda de nuevos biomarcadores subrogados del pronóstico clínico

Abstract

Objectives: _x000D_ 1. To adapt and to validate a new sequence of dynamic magnetic resonance angiography (dMRA) in order to study arterial occlusion location, collateral status and venous drainage in acute stroke patients. _x000D_ 2. To examine the relation of the burden of intracranial carotid artery wall calcification with arterial revascularization and functional outcome in acute stroke patients treated with mechanical thrombectomy (MT). _x000D_ 3. To study the associations between the degree of reperfusion achieved immediately after MT according to the angiographic Thrombolysis in Cerebral Ischemia (TICI) grading system and according to perfusion MRI and to determine the value of reperfusion as a surrogate marker of functional prognosis in patients undergoing MT._x000D_ Methods: For experiments 1 and 2 we selected subjects from the prospective database of acute stroke patients of Germans Trias Hospital, while for the experiment 3 we designed a prospective study of serial neuroimaging in patients undergoing MT. Clinical data were prospectively recorded. Neuroimaging studies were anonymized and evaluated by two investigators blinded to clinical and other radiological data. For the experiment 1 baseline MR was evaluated including dMRA and angioRM TOF sequences; for experiment 2, the amount of calcium in the arterial wall of the intracranial carotid CT was calculated on the baseline CT. Regarding experiment 3 we evaluated both TICI grades on conventional angiography and perfusion MRI sequences before and after the intervention. We calculated reperfusion index (RI) as (TMax6s pre-MT xTMax6s post-MT)/TMax6s pre-MT._x000D_ Results:_x000D_ 1. Experiment 1: Inclusion of 25 patients; dRMA detected 3 tandem occlusions and 3 incomplete arterial occlusions that were not identified by TOF MRI. Complete collateral filling (n=12, 48%) was associated with smaller diffusion weighted imaging lesion volume (p = 0.039), smaller hypoperfused volume (p = 0.018) and lower hypoperfusion intensity ratio (0.018). Patients with symmetrical venous clearance (52%) were more likely to have complete collateral filling (p = 0.015)._x000D_ 2. Experiment 2: Inclusion of 194 patients. Larger volumes of calcium in the intracranial carotid wall were associated with incomplete arterial revascularization (adjusted OR 0.73 [95% confidence Interval, 0-57-0.93]) and with a poorer functional outcome (adjusted OR 1.31 [95%confidence interval, 1.04-1.66])._x000D_ 3. Experiment 3: We studied 53 patients. A higher post-procedural TICI grade was correlated with a smaller post-procedural hypoperfusion volume and a lower value of RI (p 90% had the highest global accuracy for predicting clinical outcome followed by TICI 2b-3, but TICI 2b-3 was more feasible._x000D_ Conclusions:_x000D_ 1. dMRA was feasible and reliable in patients with acute stroke. It allowed a better evaluation of the site of occlusion and the presence of anterograde flow through thrombus than conventional angioRM techniques and enabled the dynamic evaluation of arterial input and venous drainage._x000D_ 2. A larger amount of calcium in the intracranial carotid artery before MT in acute stroke patients was an indicator of worse postprocedural arterial revascularization and poorer functional outcome. _x000D_ 3. TICI angiographic grades and MR reperfusion were closely related. TICI2b-3 was the best surrogate of clinical prognosis by combining global accuracy and feasibility.

Date of Award	5 May 2017
Original language	Undefined/Unknown
Awarding Institution	Germans Trias i Pujol University Hospital
Supervisor	Antonio Davalos Errando (Director)