Feasibility of human spinal cord perfusion mapping using dynamic susceptibility contrast imaging at 7T: Preliminary results and identified guidelines

Abstract

Purpose: To explore the feasibility of dynamic susceptibility contrast MRI at 7 Tesla for human spinal cord perfusion mapping and fill the gap between brain and spinal cord perfusion mapping techniques. Methods: Acquisition protocols for high-resolution single shot EPI in the spinal cord were optimized for both spin-echo and gradient-echo preparations, including cardiac gating, acquisition times and breathing cycle recording. Breathing-induced MRI signal fluctuations were investigated in healthy volunteers. A specific image-and signalprocessing pipeline was implemented to address them. Dynamic susceptibility contrast was then evaluated in 3 healthy volunteers and 5 patients. Bolus depiction on slice-wise signal within cord was investigated, and maps of relative perfusion indices were computed. Results: Signal fluctuations were increased by 1.9 and 2.3 in free-breathing compared to apnea with spin-echo and gradient-echo, respectively. The ratio between signal fluctuations and bolus peak in healthy volunteers was 5.0% for spin-echo and 3.8% for gradient-echo, allowing clear depiction of the bolus on every slice and yielding relative blood flow and volume maps exhibiting the expected higher perfusion of gray matter. However, signal fluctuations in patients were increased by 4 in average (using spin-echo), compromising the depiction of the bolus in slice-wise signal. Moreover, 3 of 18 slices had to be discarded because of fat-aliasing artifacts. Conclusion: Dynamic susceptibility contrast MRI at 7 Tesla showed great potential for spinal cord perfusion mapping with a reliability never achieved thus far for single subject and single slice measurements. Signal stability needs to be improved in acquisition conditions associated with patients; guidelines to achieve that have been identified and shared.

Neurosurgical Implant Safety in 7 T MRI: A Scoping Review

“…Ultra-high-field MRI of the brain and spine has several clinical applications, including neoplasm, neurodegenerative disease, epilepsy, and spinal cord perfusion mapping. 1,[33][34][35] While the number of UHF MRI scanners is rapidly expanding in the United States and globally, 7 T scans may not be routinely performed, in part due to their similar level of reimbursement despite higher cost of equipment. A 7 T MRI is approved for clinical use by the FDA in extremities and the brain, but research must continue to demonstrate significantly Torque rated on a qualitative scale 0 (no torque) to 4 (very strong torque); 0, 1 (mild or low torque), and 2 (moderate torque) were considered acceptable.…”

“…Ultra‐high‐field MRI of the brain and spine has several clinical applications, including neoplasm, neurodegenerative disease, epilepsy, and spinal cord perfusion mapping 1,33–35 . While the number of UHF MRI scanners is rapidly expanding in the United States and globally, 7 T scans may not be routinely performed, in part due to their similar level of reimbursement despite higher cost of equipment.…”

A Systematic Review evaluating the role of the 7 T MRI in Neurosurgery: Unveiling Trends in the Literature So Far after Clinical Approval in 2017

“…Lastly, though we retrieved a total of 48 studies into our database, only 31 out of those have been referenced in this review in Table 1 since they were relevant to a specific pathology while the remaining have only been denoted in the figures (were used only for analysis and generation of the data) [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58].…”

7 Tesla and Beyond

“…Different groups have demonstrated the feasibility of high-resolution cervical spinal cord MRI at 7 T, including multiparametric quantitative MRI, 113 diffusion tensor imaging, 114 and dynamic susceptibility contrast imaging. 115 Three-dimensional dual-echo steady-state MRI at 7 T has been shown to allow precise assessment of the microanatomy of intraspinal cervical nerve roots. 116 …”

“…111 However, recent developments of novel coil technology (ie, 16-channel receive array as an add-on to multichannel transmit/receive RF coil configurations) have been demonstrated to increase SNR, lower g-factors, and thus improve 7 T spine MRI at 7 T. 112 Different groups have demonstrated the feasibility of highresolution cervical spinal cord MRI at 7 T, including multiparametric quantitative MRI, 113 diffusion tensor imaging, 114 and dynamic susceptibility contrast imaging. 115 Three-dimensional dual-echo steady-state MRI at 7 T has been shown to allow precise assessment of the microanatomy of intraspinal cervical nerve roots. 116…”