Signa hde

A 1.5-Telsa MRI scanner (Signa HDe, General Electric Healthcare, Milwaukee, WI, USA) was used to image the quadriceps muscle (dominant limb) from the anterior superior iliac spine to the knee joint space with T1 gradient echo scanning sequence. Scans were performed at the baseline and 48 h after the last exercise session. The following parameters were used: matrix = 512 × 512; slice thickness = 5 mm; time to echo = 15 ms; and time to repetition = 450–850 ms. The anatomical cross-sectional area of vastus lateralis, vastus intermedius, vastus medialis and rectus femoris was analysed and outlined in every fifth image (25 mm), starting from the most proximal image in which the muscle appeared. Visible intramuscular fat, blood vessels and connective tissue were omitted [22 (link)]. Cross-sectional areas were then multiplied by the scan thickness and summed to provide individual muscle volume. Total quadriceps volume (cm³) was calculated as the sum of individual muscle volumes. Osirix software (version 8, Pixmeo, Geneva, Switzerland) was used to analyse the MRI images. Finally, muscle quality was calculated by dividing leg 1RM strength (i.e., leg extension and leg step-up) in kg with quadriceps muscle volume (cm³) as measured by MRI [23 (link)].

We conducted magnetic resonance imaging (MRI) examinations at 6, 12, and 24 weeks after surgery. We used the 1.5 T GE Signa magnetic resonance imager (Signa HDe; GE) to perform a routine scan of the sagittal T2-weighted image (Sag 3D SPGR fat sat sequence) of rabbit's knee joint and scored according to the MOCART MRI evaluation standard.

Pelvic MRI was performed using a 3-T clinical scanner (Discovery MR750, GE Healthcare, Waukesha, WI) in 27 patients. To delineate the anatomy of the pelvis prior to pelvic DCE-MRI, T2-weighted imaging was performed in the sagittal, transaxial, and coronal planes. The following T2-weighted image parameters were used: TR 3200–6000 ms, TE 60–85 ms, section thickness 4 mm, interval 1 mm, flip angle 111°, FOV 240 × 240 mm, matrix 320 × 224, two excitations, echo train length 10, and bandwidth 62.5 kHz. For DCE-MRI, a sagittal 3D fast spoiled-gradient-recalled T1-weighted sequence using the Dixon method with fat suppression (LAVA Flex, GE Healthcare) was used with the following parameters: TR 5.0 ms, TE 1.3 ms, section thickness 3 mm, flip angle 12°, FOV 260 × 260 mm, matrix 320 × 192, 1 excitation, and bandwidth 166.7 kHz. After non-contrast images were acquired, 0.1 mmol/kg of gadolinium-diethylenetriamine pentaacetic acid were injected at a rate of 2 ml/s using a contrast injector, followed by a 20-ml saline flush. Image sets were acquired at multiple phases, at 45, 80 and 120 s after initiation of the injection. In nine patients, DCE-MRI was performed at other institutes using 1.5-T clinical scanners (Magnetom Aera, Siemens Healthineers, or Signa HDe, GE Healthcare).

Pelvic MRI was performed using a 3-T clinical scanner (Discovery MR750; GE Healthcare, Waukesha, WI, USA) in 49 patients. To delineate the anatomy of the pelvis, T2-weighted imaging was performed in the sagittal, transaxial, and coronal planes. The following T2-weighted image parameters were used: TR, 3200–6000 ms; TE, 60–85 ms; section thickness, 4 mm; interval, 1 mm; flip angle, 111°; FOV, 240 × 240 mm; matrix, 320 × 224; two excitations; echo train length, 10; and bandwidth, 62.5 kHz. In 23 patients, MRI was performed at other institutes using a 1.5-T clinical scanner (Magnetom Aera; Siemens Healthineers, or Signa HDe; GE Healthcare).

Functional MRI data were acquired with a 1.5T General Electric Signa HDe scanner at Parc Sanitari Sant Joan de Déu. A T2*-weighted functional echoplanar imaging sequence depicting BOLD contrast was obtained using a quadrature head coil. In total 270 volumes were collected with slices parallel to the AC-PC plane, resulting in an axial-oblique orientation. The following scanning parameters were used: 26 interleaved slices, 4 mm thickness, 1 mm gap, TR = 2000 ms, TE = 40 ms, 24 cm FOV, 64 × 64 acquisition matrix, flip angle = 90°. The first seven volumes in each run were discarded to allow for magnetic saturation effects. Visual stimuli were presented on a rear projection screen and viewed through a mirror mounted on the head coil, and all responses were collected with an MR-compatible response box (fORP, Current Designs, Inc., USA; www.curdes.com).