1.5 tesla or 3 tesla mri scanner

MR imaging was performed within 1 week prior and after venous stenting. The study was performed on a 1.5 Tesla or 3 Tesla MRI scanner (GE Healthcare, Milwaukee, WI). 1.5T studies consisted of 3-D time of flight MR angiography and 2-D coronal time of flight MR venography with maximum intensity projection reconstructions of the large intracranial arteries and dural venous sinuses, respectively. 3T studies used 3-D time of flight MR angiography and venography. Quantitative flow measurements were made through the large intracranial arteries and dural venous sinuses using cardiac gated phase contrast MR angiography and venography with specialized software (Non-invasive Optimal Vessel Analysis; NOVA, VasSol Inc, Chicago, IL). The flow was measured along standard points of the arterial and venous sinus system and across the stenotic segment.
For this study, venous flow was reviewed at four locations: the superior sagittal sinus proximal to the stenotic segment, the region of stenosis, the jugular vein ipsilateral and downstream from the region of stenosis, and the contralateral jugular vein. The flow of the two jugular veins was added together to calculate the total jugular outflow. Flow measurements were made at the same location of each venous segment in preoperative and postoperative imaging.

Images were acquired at our institution with a 1.5 Tesla or 3 Tesla MRI scanner (GE Medical Systems, Milwaukee, WI) between 2010 and 2017 with standard pelvic MRI and dedicated sequences to evaluate the rectum with field of view from L5 to the anal verge (Table 1). A body coil was used for excitation, and a multi-channel phased-array coil (without endorectal coil) was used for signal reception. During the study period, the MRI parameters varied slightly as per the standard departmental protocol, as scans before August 24, 2013, included an axial T1-weighted non-fat suppressed sequence; 70% (803/1197) of scans, however, were obtained after this date.