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22. European Stroke Conference 238 Brain imaging Stent recanalization improves delayed hemodynamic response and amplitude of the BOLD signal in patients with severe carotid stenosis. K. C. Mazzetto Betti1, R. F. Leoni2, L.H Castro-Afonso3, A. C. Santos4, D. G. Abud5, J. P. Leite6, O. M. Pontes-Neto7 University of Sao Paulo, Ribeirao Preto, BRAZIL1, University of Sao Paulo, Ribeirao Preto, BRAZIL2, University of Sao Paulo, Ribeirao Preto, BRAZIL3, University of Sao Paulo, Ribeirao Preto, BRAZIL4, University of Sao Paulo, Ribeirao Preto, BRAZIL5, University of Sao Paulo, Ri-beirao Preto, BRAZIL6, University of Sao Paulo, Ribeirao Preto, BRAZIL7 Background and Purpose: Cerebrovascular reactivity (CVR) has been suggested as an independent predictor of stroke in patients with severe carotid stenosis. Functional MRI (FMRI) can be used to assess CVR in the anterior territory at the microvasculature level, by the analysis of temporal param-eters and amplitude of BOLD signal. We aim to analyse BOLD signal from the ipsilateral (IH) and contralateral hemispheres (CH) induced by auditory stimulus patients with symptomatic carotid ste-nosis, under three different levels of hypercapnic stress before and after stenting recanalization. Methods: We evaluated twenty patients with unilateral severe symptomatic carotid stenosis. FMRI protocol was undertaken one week before and three months after the endovascular intervention. Subjects were submitted to auditory stimulus (3s) under normocapnia (baseline) and with EtCO2 increase of 5 and 10mmHg. The images were acquired with a 3T Philips MR, pre-processed and the BOLD parameters were analysed. Results: Before the stent, the averaged BOLD signal hemodynamic response of the IH was delayed compared to the CH. The BOLD signal amplitude in IH was diminished at baseline and at the first level of hipercapnia (p<0.05). Area under the BOLD curve from IH was decreased compared to CH. After stenting, all the temporal parameters of the hemodynamic response improved in IH compared to the pre-stent condition: onset (p<0.05); full width at half a maximum (p<0.05); and time to peak (p<0.05). Amplitude and area under curve of BOLD signal increased in both the first (p<0.05) and second level (p<0.05) of hipercapnia. The BOLD signal differences between the hemispheres disap-peared 412 © 2013 S. Karger AG, Basel Scientific Programme after stenting. Conclusion: Stent recanalization of severe carotid stenosis improve delayed hemodynamic response and decreased amplitude of the ICH BOLD signal, suggesting that improving cerebrovascular vaso-reactivity may be an important mechanism to decrease the risk of stroke after carotid revasculariza-tion procedures. 239 Brain imaging Advanced MRI sequences in the acute evaluation of transient ischaemic attack (TIA) – a com-parison between DTI, DWI and ASL including 8 weeks follow-up scans: pre-liminay results from the Copenhagen TIA-MRI-study. H. Christensen1, J. Marstrand2, C. Ovesen3, J. Damm4, A. Christensen5 Bispebjerg hospital, Copenhagen, DENMARK1, Bispebjerg hospital, Copenhagen, DENMARK2, Bispebjerg hospital, Copenhagen, DENMARK3, Bispebjerg hospital, Copenhagen, DENMARK4, Bispebjerg hospital, Copenhagen, DENMARK5 Background: DWI detects ischaemia in app. 30 % of patients with clinical TIA. We aimed to compare the sensi-tivity of DTI, DWI and ASL in the detection of acute ischaemia and further to investigate if chronic ischaemic changes after 8 weeks in the form of gliosis always follow. Methods: The first 40 consecutive patients included during first 3 months of an MRI-protocol (DWI, DTI and ASL within 72 hours of symptoms) and 8 weeks follow-up protocol (T2 and DWI). Patients were included by stroke consultants. Lesion volumes on DWI, DTI and follow-up T2 were compared. Hyper-or hypoperfusion on ASL was recorded. One senior neuro-radiologist assessed the sequences in random order to prevent bias. Results: Fourteen patients had acute ischaemic lesions: 2 in the posterior fossa and 12 in the cerebral hemi-spheres corresponding to 35% of referred patients. Thirteen of these developed gliosis in the affect-ed area and of these 1 was noted only on DTI and 1 only as post ischemic hyper perfusion on ASL. The mean lesion volume was 1.2mL. Mean difference between volume on DWI and gliose volume (T2) was 0.42mL =71% and between DTI and gliose volume (T2) 0.29 mL=40% ; this difference was significant (p=0.042). Conclusions: These preliminary results indicate that TIA causes a gliosis lesion consistently, and that the initial lesion as well as the extent of the permanent changes is better described using DTI. ASL seems to be able to contribute to the detection of TIA as perfusion changes may be the sole MRI-sign in some patients increasing detection rates with 5%.


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