The role of functional MR imaging in patients with ischemia in the visual cortex

Citation
Yj. Lee et al., The role of functional MR imaging in patients with ischemia in the visual cortex, AM J NEUROR, 22(6), 2001, pp. 1043-1049
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Neurosciences & Behavoir
Journal title
AMERICAN JOURNAL OF NEURORADIOLOGY
ISSN journal
0195-6108 → ACNP
Volume
22
Issue
6
Year of publication
2001
Pages
1043 - 1049
Database
ISI
SICI code
0195-6108(200106/07)22:6<1043:TROFMI>2.0.ZU;2-E
Abstract
BACKGROUND AND PURPOSE: Functional MR (fMR) imaging is based on changes in regional blood how, The purpose of this study was to evaluate the role of f MR imaging for detection of a vascular compromised status in the occipital lobe in patients with ischemia in the visual cortex. METHODS: We performed fMR imaging in seven control subjects and seven patie nts with symptoms and signs of visual cortical transient ischemia and/or in farct, fMR imaging was performed using a gradient-echo sequence with the 2D fast low-angle shot technique, An axial slice including both visual cortic es was selected, and stimulation of the visual cortex was performed using a red photostimulator. The number of activated pixels in each primary visual cortex area were counted and an asymmetry ratio [AR (%) = 100 x (R-L)/(R+L )/2] was calculated. Patients and control subjects underwent visual field e xamination, conventional MR imaging, and vascular imaging (MR angiography i n all patients and control subjects, conventional catheter angiography in t wo patients). fMR imaging results were compared with the results of a visua l field examination, conventional MR imaging, and vascular imaging. RESULTS: fMR imaging of the patients showed significant activation asymmetr y (P < .05) compared with that of control subjects, Vascular abnormalities in the posterior circulation were found in all seven patients. By conventio nal MR imaging, five patients were found to have infarction in the occipita l lobe and the remaining two patients showed no abnormality. In visual fiel d examination, six of the seven patients showed homonymous hemi- or quadran tanopsia suggesting postchiasmic abnormalities, and the remaining patient h ad normal findings, fMR imaging showed decreased activity in the visual cor tices corresponding to vascular abnormalities (seven of seven patients), pe rmanent infarction (five of seven patients), or visual field defect (six of seven patients). Two patients with normal conventional MR imaging had vasc ular lesions in the posterior circulation, and fMR imaging showed decreased activity in the corresponding visual cortices, One patient with normal vis ual field examination had multifocal stenosis in the posterior cerebral art ery without infarction, and fMR imaging showed decreased activity in the co rresponding visual cortex. CONCLUSION: fMR imaging of the visual cortex may be a sensitive method for the detection of vascular-compromised status in the occipital lobe.