Signa echospeed

Cardiac systolic and diastolic functions and LV muscle mass (LVMM) were measured using MDCT, as previously described [22 (link), 28 (link)]. Images were analyzed with Analyze™. In brief, Early (E) and late (A) LV filling rate were measured from the positive slopes of volume/time curves and E/A ratio calculated using MATLAB® (MathWork, Natick, MA, USA) [29 (link), 30 (link)]. Myocardial perfusion was calculated from time-attenuation curves obtained from the anterior cardiac wall before and during a five-minute intravenous infusion of adenosine (400 μg/kg/minute) [31 (link)]. Myocardial oxygenation was assessed using BOLD-MRI on a 3 T, Signa EchoSpeed (GE Medical Systems, Milwaukee, WI, USA) scanner, as previously described [5 (link)]. For MRI, animals were anesthetized with 1% to 2% isoflurane and scans performed during suspended respiration before and after 400 μg/kg/minute of intravenous adenosine. The relaxivity index R2*, which inversely correlates with tissue oxygenation, was calculated in each voxel by fitting the MR signal intensity versus echo times to a single exponential function. For data analysis, regions of interest were traced in the septum in each slice and images analyzed using MATLAB 7.10 (MathWorks), as previously described [32 (link)].

MRI was performed using a 3.0-T GE Signa Echo-Speed MR scanner (GE Medical Systems, Milwaukee, WI, USA). All MRI images in this study were obtained in the afternoon to minimize the diurnal variation of T2 values in the IVDs [24] (link).
Sagittal T1-weighted fast spin echo (FSE) and sagittal, transversal, and axial T2-weighted FSE sequences were used for morphological MRI (for detailed sequence parameters see Table 1). The sagittal T2 weighted images (WIs) were used for visual Pfirrmann grading of IVD degeneration. Next, a T2 map was created using the T2 values in the midsagittal section from sagittal sections centered on the cervical midline region with optimized 8 echo multi-spin echo (Repetition time /first,last time echo time, TR/(fTE, lTE), 1500/8.5, 17.0, 25.5, 34, 42.4, 50.9, 59.4, 67.9, field of view (FOV)  = 20 mm×20 mm, section thickness  = 3.0 mm, matrix  = 256×160, number of signal intensity acquisitions  = 1, and total examination time 4 min and 27 s) obtained using an ADW 4.3 workstation (Functool, GE Medical Systems, Milwaukee WI, USA). However, the first echo from the multi-spin system was excluded to minimize the effect of the stimulated echo [14] (link). A single midline sagittal section was positioned parallel to each cervical IVD from C2–3 to C6–7. The T2 maps were computed in each pixel from the SI in the respective TE using the following formula: SI  = e^−TE/T2.