Intraoperative MRI with a rotating, tiltable surgical table: A time-use study and clinical results in 122 patients

OBJECTIVE. The objective of our study was to evaluate intraoperative low-field MRI for the frequency and duration of imaging sessions needed during surgery, the direct additional procedure time attributable to imaging, and the proportion of cases in which information provided by intraoperative MRI led to a change in the procedure or otherwise was deemed valuable by operating surgeons. MATERIALS AND METHODS. One hundred twenty-two patients (65 males, 57 females; age range, 6-77 years; mean age, 43.8 years) underwent 130 neurosurgical and ENT procedures (106 craniotomies, 17 transsphenoidal pituitary resections, three biopsies, three intracranial cyst aspirations or injections, and one skull base resection) in a specially designed surgical MRI suite equipped with a 0.2-T imager and a prototype rotating, tiltable surgical table. The intraoperative MR sequences included free induction with steady-state precession (fast imaging with steady-state precession [FISP]), steady-state free precession T2-weighted, reverse fast imaging with steady-state free precession (PSIF), FLASH, spin-echo T1-weighted, turbo spin-echo (TSE) T2-weighted, and TSE FLAIR. Each case was analyzed for the number of imaging sessions, duration of each session, total imaging time during surgery, and impact of imaging information on procedure. RESULTS. Each patient underwent between one and five intra- or postoperative imaging sessions. Imaging times were 1.7 seconds-8 minutes 31 seconds per sequence. The mean total imaging time was 35 minutes 17 seconds per surgical procedure. Imaging was continuous during biopsy and cyst aspiration procedures and averaged 200.67 and 54.66 minutes, respectively. Additional surgical resection based on intraoperative imaging findings was performed in 72.8% of the cases. CONCLUSION. Intraoperative low-field MRI provides valuable information for surgical decision making that is predominantly related to detection of residual tumor and the exclusion of complications. The benefits of this technology surpass the time cost associated with its implementation when using proper imaging strategies.