Vessel size imaging.
Vessel size imaging is a new method that is based on simultaneous measurement of the changes Delta R(2) and Delta R(2)(*) in relaxation rate constants induced by the injection of an intravascular superparamagnetic contrast agent. Using the static dephasing approximation for Delta R(2)(*) estimation and the slow-diffusion approximation for Delta R(2) estimation, it is shown that the ratio Delta R(2)/Delta R(2)(*) can be expressed as a function of the susceptibility difference between vessels and brain tissue, the brain water diffusion coefficient, and a weighted mean of vessel sizes. Comparison of the results with 1) the Monte Carlo simulations used to quantify the relationship between tissue parameters and susceptibility contrast, 2) the experimental MRI data in the normal rat brain, and 3) the histologic data establishes the validity of this approach. This technique, which allows images of a weighted mean of the vessel size to be obtained, could be useful for in vivo studies of tumor vascularization. Magn Reson Med 45:397-408, 2001.
Unité mixte INSERM/Université Joseph Fourier, Hôpital Albert Michallon, Grenoble, France.
I
I
Troprès
S
S
Grimault
A
A
Vaeth
E
E
Grillon
C
C
Julien
J F
JF
Payen
L
L
Lamalle
M
M
Décorps
D000818:Animals; D001921:Brain / Q000098:blood supply*; D002536:Cerebral Arteries / Q000473:pathology; D002550:Cerebral Veins / Q000473:pathology; D003198:Computer Simulation; D003287:Contrast Media; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007501:Iron; D018810:Magnetic Resonance Angiography; D058185:Magnetite Nanoparticles; D008297:Male; D008833:Microcirculation / Q000473:pathology; D010087:Oxides; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D014655:Vascular Resistance / Q000502:physiology
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide