Quantitative assessment of cerebral venous blood T 2 in mouse at 11.7T: Implementation, optimization, and age effect

Purpose To develop a non–contrast‐agent MRI technique to quantify cerebral venous T 2 in mice. Methods We implemented and optimized a T 2 ‐relaxation‐under‐spin‐tagging (TRUST) sequence on an 11.7 Tesla animal imaging system. A flow‐sensitive‐alternating‐inversion‐recovery (FAIR) module was used to generate control and label images, pair‐wise subtraction of which yielded blood signals. Then, a T 2 ‐preparation module was applied to produce T 2 ‐weighted images, from which blood T 2 was quantified. We conducted a series of technical studies to optimize the imaging slice position, inversion slab thickness, post‐labeling delay (PLD), and repetition time. We also performed three physiological studies to examine the venous T 2 dependence on hyperoxia ( N  = 4), anesthesia ( N  = 3), and brain aging ( N  = 5). Results Our technical studies suggested that, for efficient data acquisition with minimal bias in estimated T 2 , a preferred TRUST protocol was to place the imaging slice at the confluence of sagittal sinuses with an inversion‐slab thickness of 2.5‐mm, a PLD of 1000 ms and a repetition time of 3.5 s. Venous T 2 values under normoxia and hyperoxia (inhaling pure oxygen) were 26.9 ± 1.7 and 32.3 ± 2.2 ms, respectively. Moreover, standard isoflurane anesthesia resulted in a higher venous T 2 compared with dexmedetomidine anesthesia ( N  = 3; P  = 0.01) which is more commonly used in animal functional MRI studies to preserve brain function. Venous T 2 exhibited a decrease with age ( N  = 5; P  < 0.001). Conclusion We have developed and optimized a noninvasive method to quantify cerebral venous blood T 2 in mouse at 11.7 T. This method may prove useful in studies of brain physiology and pathophysiology in animal models. Magn Reson Med 80:521–528, 2018. © 2017 International Society for Magnetic Resonance in Medicine.