Impact of tissue T₁on perfusion measurement with arterial spin labeling

Abstract

A low dose of Mn reduces the tissue T without modifying CBF. Heterogeneous T impacts the ASL estimate of CBF in a region-dependent way. In animals, and when T modifications exceed the accuracy with which the tissue T can be determined, an estimate of tissue T should be obtained when quantifying CBF with an ASL technique. Magn Reson Med 77:1656-1664, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Quantitative assessment of cerebral venous blood T2 in mouse at 11.7T: Implementation, optimization, and age effect

“…Measurement of venous oxygenation is a critical step toward noninvasive assessment of brain metabolism and energy consumption. To estimate CMRO 2 , one can combine TRUST MRI with additional measures of arterial oxygenation and cerebral blood flow (CBF), which can be obtained with phase‐contrast MRI or arterial‐spin‐labeling . Previous studies in humans have demonstrated the clinical utility of these techniques in several neurologic diseases such Alzheimer's disease and multiple sclerosis .…”

Interpulse phase corrections for unbalanced pseudo‐continuous arterial spin labeling at high magnetic field

“…The following sequences were used in this study, but not all for each animal (see “Experimental Protocols” subsection for more details): Anatomical T 2 ‐weighted (T 2w ) images were obtained through a spin‐echo sequence (TR/TE = 3346/33 ms, resolution = 0.137 × 0.137 × 0.8 mm 3 , number of averages (NA) = 2, acquisition time (T acq ) = 3 min 34 s). A T 1 map was acquired for cerebral blood flow (CBF) quantification using a nonselective inversion recovery sequence (TR/TE = 10000/19 ms, 18 inversion times (TIs) between 30 and 10000 ms, T acq = 4 min). Other EPI parameters were identical to the aforementioned ones. Label‐phase optimization prescan (T acq = 100 s).…”

“…To calculate quantitative CBF maps, we assumed a single compartment and used the standard kinetic model developed by Buxton et al . Assuming that the arterial transit time is equal to the postlabeling delay, and that , the magnetization of arterial blood at thermal equilibrium, may be approximated by , where is the magnetization of tissue at thermal equilibrium and λ the blood‐brain partition coefficient of water (0.9 mL/g) , we used the following equation pixel‐by‐pixel to quantify CBF (mL/100 g/min) : where is the signal difference between control and label acquisitions averaged over repetitions; is the apparent T 1 of tissue from the T 1 map; is the longitudinal relaxation time of blood (2430 ms at 9.4 T) ; and is the control image intensity of the ASL experiment multiplied by to correct for incomplete T 1 relaxation during the 4‐s TR.…”

Quantitative blood flow measurement in rat brain with multiphase arterial spin labelling magnetic resonance imaging

“…As a result of the above issues, a wide range of CBF measurements in rodents have been reported, often spanning ranges that are neither physiologically realistic (e.g. >300 mL/100 g/min 6–10 ), nor in agreement with gold-standard autoradiography measures of perfusion. 11 Thus, there is a need to improve the application of ASL MRI in rodents and to achieve a similar standardization to that now implemented clinically.…”