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.
Original language | English (US) |
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Pages (from-to) | 1145-1150 |
Number of pages | 6 |
Journal | Magnetic resonance in medicine |
Volume | 56 |
Issue number | 5 |
DOIs | |
State | Published - Nov 2006 |
Keywords
- Contrast agent
- Echo planar imaging
- Human brain
- MRI
- Microvessel density
- Relaxation rate
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging