London, United Kingdom 2013 4 Brain imaging A 15:00 - 15:10 DECREASED CEREBROVASCULAR REACTIVITY IN HEALTHY AGING: A BOLD-MRI Cerebrovasc Dis 2013; 35 (suppl 3)1-854 45 STUDY R.F. Leoni1, K.C. Mazzetto-Betti2, O.M. Pontes-Neto3, J.P. Leite4 Department of Neuroscience and Behavioral Science - FMRP, University of Sao Paulo, Ri-beirao Preto, BRAZIL1,Department of Neuroscience and Behavioral Science - FMRP, Univer-sity of Sao Paulo, Ribeirao Preto, BRAZIL2, Department of Neuroscience and Behavioral Sci-ence - FMRP, University of Sao Paulo, Ribeirao Preto, BRAZIL3, Department of Neuroscience and Behavioral Science - FMRP, University of Sao Paulo, Ribeirao Preto, BRAZIL4 Background: Cerebrovascular reactivity (CVR) has been shown to be affected by physiologic age-related changes1. Magnetic resonance imaging (MRI) based on blood oxygenation lev-el- dependent (BOLD) contrast emerged as a noninvasive tool to evaluate whole-brain CVR, when combined with a vasoactive stimulus2. In the present study, BOLD-MRI and CO2 in-halation were used to investigate CVR in elderly subjects to evaluate changes related with nor-mal aging. Methods: Thirty healthy young adults (16 male; 14 female; 18-40 years) and eleven healthy elderly adults (5 male; 6 female; 53-72 years) with no history of neurological diseases were scanned at a 3T Philips scanner, using an EPI sequence (TR=2s, FOV=230x230mm2, ma-trix= 128x128, 30 slices). For hypercapnic challenge, a home-built device was used to deliver 5L/min of CO2 mixed with medical air. The paradigm consisted of 5 epochs of hypercapnia (14s) intercalated by 6 epochs of normocapnia (30s). BOLD signal amplitude and CVR (BOLD amplitude/ΔEtCO2) were obtained and are given as mean ± standard deviation. Results: During hypercapnia (deltaEtCO2 = 12+/-4mmHg), global increase in BOLD response was ob-served. However, BOLD amplitude in gray matter was decreased for elderly subjects (Figure 1). Average CVR also differed between groups (young: 0.28+/-0.08%/mmHg, elderly: 0.21+/- 0.07%/mmHg; p<0.05, t-test). Conclusion: CVR was successfully investigated using a protocol that causes minimal or no discomfort for the subjects. Decreased CVR observed in the elderly group highlights the importance of considering differences in vascular physiology when evalu-ating older pacients in MRI studies. However, further studies are necessary to assess the predic-itive value of BOLD MRI on the identification of altered CVR in normal aging in comparison to more quantitative methods such as Arterial Spin Labeling. 1Gauthier CJ et al., Neurobiol Aging 2012; S0197-4580(12)00568-4. 2Leoni RF et al., Radiol Res Pract 2012; 2012:268483. 3 Brain imaging A 14:50 - 15:00 Infarct core volume on whole brain perfusion CT is predictive of haemorrhagic transfor-mation after stroke N. Yassi1, M.W. Parsons2, G.A. Donnan3, S. Christensen4, C.R. Levi5, P.M. Desmond6, S.M. Davis7, B. CV. Campbell8 Department of Neurology, Melbourne Brain Centre @ Royal Melbourne Hospital, Uni-versity of Melbourne, Parkville, AUSTRALIA1,Priority Research Centre for Translational Neuroscience and Mental Health, University of Newcastle and Hunter Medical Research Insti-tute, Newcastle, AUSTRALIA2, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, AUSTRALIA3, Department of Radiology, The Royal Melbourne Hos-pital, University of Melbourne, Parkville, AUSTRALIA4, Priority Research Centre for Transla-tional Neuroscience and Mental Health, University of Newcastle and Hunter Medical Research Institute, Newcastle, AUSTRALIA5, Department of Radiology, The Royal Melbourne Hospi-tal, University of Melbourne, Parkville, AUSTRALIA6, Department of Neurology, Melbourne Brain Centre @ Royal Melbourne Hospital, University of Melbourne, Parkville, AUSTRALIA7, Department of Neurology, Melbourne Brain Centre @ Royal Melbourne Hospital, University of Melbourne, Parkville, AUSTRALIA8 Background: Intracerebral haemorrhage is the most serious potential complication of stroke thrombolysis. MRI studies have shown that diffusion lesion volume predicts haemorrhagic transformation after stroke. We sought to determine the optimal CT perfusion (CTP) parameter for prediction of cerebral parenchymal haemorrhage (PH) in acute ischemic stroke. Methods: Patients with acute ischemic stroke with onset <9 hours had whole-brain CTP, fol-lowed by follow-up CT/MRI to determine presence or absence of haemorrhagic transformation. Receiver operator characteristic (ROC) analysis was performed to determine the optimal level of relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV) to predict PH. The best performing parameters were tested in a multivariate logistic regression model, which included other risk factors for haemorrhagic transformation. Results: Of 132 patients, 14 (10.6%) developed PH. Baseline National Institute of Health Stroke Scale (NIHSS) (p=0.018) and thrombolysis (p=0.002) were predictive of PH. ROC analysis revealed that rCBF<28% compared to the contralateral mean (area under curve 0.743, p=0.003) and rCBV<60% (area under curve 0.726, p=0.006) were the optimal thresholds and the Bayesian Information Criterion (+2.1) indicated that rCBF was more strongly associated with PH than rCBV. rCBF<28% volumes of >15mL allowed prediction of PH with sensitivi-ty 93%, specificity 48% and negative likelihood ratio 6.8. rCBF<28% volume (p=0.021) and thrombolysis (p=0.033), were both independently predictive of PH in a multivariate logistic regression model. CTP was less sensitive in regions of severe hypoperfusion, and hence thresh-olds for very low CBF or CBV were of limited utility. Conclusion: rCBF<28% was the CTP parameter most strongly associated with PH. This equates closely to CTP estimates of infarct core volume and is supportive of the hypothesis that larger core volumes are predictive of subsequent haemorrhage.
Karger_ESC London_2013
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