Warm air feedback system

All animal experiments were approved by Animal Care and Usage Committee in Vanderbilt University. Each rat was injected with 1 × 10⁵ 9L glioblastoma cells in the right brain hemisphere, and was then imaged after 2 to 3 weeks when brain tumor was formed. Seven rats bearing 9L tumor were immobilized and anesthetized with a 2%/98% isoflurane/oxygen mixture. Respiration was monitored to be stable, and a constant rectal temperature of 37°C was maintained throughout the experiments using a warm-air feedback system (SA Instruments, Stony Brook, NY).

Five healthy rats were immobilized and anesthetized with a 2%/98% isoflurane/oxygen mixture. Respiration was monitored and a constant rectal temperature of 37°C was maintained throughout the experiments using a warm-air feedback system (SA Instruments, Stony Brook, NY). All procedures were approved by the Animal Care and Usage Committee of Vanderbilt University.

2DG infusion experiments were performed on 4 healthy Sprague Dawley rats and 1 rat bearing 9L tumor. The rats were immobilized and anesthetized with a 2%/98% isoflurane/oxygen mixture. Respiration was monitored and adjusted to be stable, and a constant rectal temperature of 37°C was maintained throughout the experiments using a warm-air feedback system (SA Instruments, Stony Brook, NY). A polyethylene catheter (PE50) was inserted into the tail vein for 2DG infusion. 3 ml 0.5 M 2DG solution was injected to each rat through the catheter. This corresponds for a 250 gm rat to a dose of approximately 1 gm/kgm body weight. The solution was infused via the tail vein at a rate of 2 ml/h (90 minute infusion). All procedures were approved by the Institutional Animal Care and Use Committee at Vanderbilt University.

Three rats bearing 9L tumors were used for the in vivo validation of the proposed method in this study. Each rat was injected with 1 × 10⁵ 9L glioblastoma cells in the right brain hemisphere for the induction of brain tumor, and then imaged after 2 to 3 weeks. All rats were immobilized and anesthetized with 2-3% isoflurane and 97-98% oxygen during the experiments. Respiration rate was monitored to be in a range from 40 to 70 breaths per minute. Rectal temperature was maintained at 37°C using a warm-air feedback system (SA Instruments, Stony Brook, NY). All animal procedures were approved by the Animal Care and Usage Committee of Vanderbilt University Medical Center.

MR images were acquired on a 16-cm bore Bruker horizontal 7T magnet, using a Doty 38-mm inner diameter transceiver coil. For imaging, mice were immobilized and anesthetized (isoflurane 1.0–1.5%), and a constant rectal temperature of 37.5 °C was maintained throughout each imaging session using a warm-air feedback system (SA Instruments, Stony Brook, NY, USA). T₁-weighted images were acquired to guide data collection (Supporting Information Figure S1). A fast spin-echo sequence (TR = 5500 ms, RARE-factor = 4, resolution = 0.25 × 0.25 × 1 mm³, multiple echo times of 14, 42, 70, 98, 126 ms) was used to achieve T₂ contrast and calculate R₂(= 1/T₂) maps.
Spin-lock images were acquired in a transverse plane (Supporting Information Figure S1) using a fast spin echo sequence preceded by a conventional preparatory spin-lock cluster consisting of a 90° excitation pulse followed by a single rectangular locking pulse with duration of τ and a −90° excitation pulse (90_x – τ_y – 90_-x). Imaging parameters were TR/TE = 3000/24 msec, RARE factor = 8, resolution = 0.25 × 0.25 × 1 mm³. Sets of images were acquired with different spin-lock amplitudes SLB1 (locking frequencies at 200, 400, 600, 800, 1000, 1500, 2000, 2500 and 3000 Hz). Spin-lock times at each spin-lock amplitude were varied as 1, 5, 15, 25, 35, 55, 75 ms (Supporting Information Figure S1).

Three Sprague Dawley rats (250–300 grams) bearing 9L tumors were immobilized and anesthetized with a 2%/98% isoflurane/oxygen mixture. Respiration was monitored to be stable, and a rectal temperature of 37°C was maintained constant throughout the experiments using a warm-air feedback system (SA Instruments, Stony Brook, NY). All experiments were measured in 1 h after onset of isoflurane. For brain tumor induction, each rat was injected with 1 × 10⁵ 9L glioblastoma cells in the right brain hemisphere, and was then imaged after 2 to 3 weeks. All procedures were approved by the Institutional Animal Care and Usage Committee at Vanderbilt University.

Eight rats bearing 9L tumors were included in this study. For brain tumor induction, each rat was injected with 1 × 10⁵ 9L glioblastoma cells in the right brain hemisphere, and was then imaged after 2 to 3 weeks. All rats were immobilized and anesthetized with a 2%/98% isoflurane/oxygen mixture during data acquisition. Respiration was monitored to be stable, and a constant rectal temperature of 37°C was maintained throughout the experiments using a warm-air feedback system (SA Instruments, Stony Brook, NY, USA). All animal procedures were approved by the Animal Care and Usage Committee of Vanderbilt University Medical Center.