title: Microvessel density estimation in the human brain by means of dynamic contrast-enhanced echo-planar imaging.
abstract: Animal studies have shown that in vivo estimates of microvessel density in the brain may be obtained from an MRI-measurable index (Q) provided that a sufficiently high dose of an intravascular paramagnetic contrast agent is employed. Q is determined from the shifts in the transverse relaxation rates induced by the contrast agent, and a high dose is required for the validity of analytic expressions relating Q to the microvessel density. However, the steady-state imaging techniques used in these prior investigations are not appropriate for humans, as the required contrast agent dose is too large. Here results of a pilot study with three subjects are reported. The results suggest that reliable Q measurements can be performed in the human brain at 1.5 T by using an interleaved spin-echo (SE)/gradient-echo (GE) echo-planar imaging (EPI) sequence and a bolus injection of a triple dose of Gd-DTPA. Lower- and upper-bound estimates for the microvessel density were derived from the Q-values, and were found to be in reasonable accord with previously cited values determined by histology.
authors.affiliation: Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016-3240, USA. jens.jensen@med.nyu.edu
authors.forename: Jens H
authors.initials: JH
authors.lastname: Jensen
authors.forename: Hanzhang
authors.initials: H
authors.lastname: Lu
authors.forename: Matilde
authors.initials: M
authors.lastname: Inglese
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000098:blood supply* / Q000473:pathology*; D003287:Contrast Media; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008833:Microcirculation / Q000473:pathology*; D009103:Multiple Sclerosis / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D013113:Spin Labels; D019786:Gadolinium DTPA