Signa lx

All MR images were acquired using a 3.0-Tesla General Electric Signa LX scanner (General Electric Medical Systems, Waukesha, WI) equipped with an eight-channel receiver head coil and body quadrature transmit radiofrequency coil. Cardiorespiratory monitoring during scanning was performed with a pulse oximeter and respiratory bellows equipment at a sampling rate of 40 Hz. Anatomical scans were acquired using a high-resolution spoiled gradient recalled (SPGR) acquisition technique consisting of 120 sagittal whole brain 1.2 mm thick slices over a 240 mm field of view and 256 × 256 within-slice pixel resolution. These high-resolution anatomic images were used for subsequent superposition of cortical maps derived from the echo planar BOLD contrast images.

Six-lead electrocardiography (MAC 1600, Hewlett-Packard, CA) was performed in all resting animals at baseline, immediately post-infarction and at twelve weeks with analysis of waveform components. Transthoracic and transepicardial echocardiography with color flow Doppler was performed with a 7-MHz transducer (Acuson, CA). Magnetic resonance imaging (MRI) (Signa LX, GE Healthcare, UK) acquisition and analysis of cardiac hemodynamics were generated for each animal at selected timepoints. Evaluation of cardiac cycles was obtained with cardiac MRI software (//segment.heiberg.se/).

All studies were performed on a 1.5-T clinical scanner (Signa LX, GE Healthcare, Milwaukee, WI). Conventional axial and sagittal T1-weighted, axial T2-weighted, axial T2-weighted FLAIR, axial diffusion-weighted, and axial and coronal/ sagittal contrast-enhanced T1-weighted MR images were obtained. Single-voxel ¹H MRS spectra of the tumors were acquired before administration of contrast agent by using a point-resolved spectroscopy sequence (PRESS) with a short TE of 35 ms, a TR of 1500 ms, and 128 signal intensity averages. When the size of the lesion permitted, a second spectrum from a slightly different region of interest was acquired using the same parameters. Approximately 5 min was required for each spectral acquisition. The sizes of the regions of interest ranged from 5 to 10 cm³. Fully automated LCModel software (Stephen Provencher Inc., Oakville, Ontario, Canada) was used for processing and to generate printouts provided to physicians for review.

All images were acquired with either a 3T or 1.5T Signa LX scanner (GE Healthcare, Milwaukee, Wisconsin) with an 8-channel head coil. For fMRI data acquisition, we used the following imaging sequence: gradient-echo echo-planar (TR, 4000 ms; TE, 30 ms [for 3T] and 40 ms [for 1.5T]; matrix, 128 × 128; flip angle, 90°; 4.5-mm section thickness with no gap; FOV, 240-mm; 32–36 axial sections covering whole brain). T1-weighted spin-echo (TR/TE, 600/8 ms; matrix, 256 × 256; flip angle, 90°; 4.5-mm section thickness with no gap; FOV, 240 mm up to 36 sections) and axial FLAIR images (TR/TE/TI, 9000/125/2250 ms; matrix, 512 × 512; flip angle, 90°; 4.5-mm section thickness with no gap; FOV, 240 mm; up to 36 axial sections) were obtained in the same axial orientation as the fMRI data. 3D T1-weighted anatomic images were also acquired with a spoiled gradient-recalled sequence (TR/TE, 22/4 ms; matrix, 256 × 256 matrix; flip angle, 30°; 1.5-mm thickness; FOV, 240 mm). Head motion was minimized in a standard head coil by using straps and foam padding. Gadopentetate dimeglumine (Magnevist; Bayer HealthCare Pharmaceuticals, Wayne, New Jersey) was injected through a peripheral angiocatheter (18–21 ga) at a standard dose (0.2 mL/kg body weight; maximum, 20 mL).