Neuromelanin‐Sensitive Magnetic Resonance Imaging Using DANTE Pulse

Abstract

Background Neuromelanin‐sensitive magnetic resonance imaging techniques have been developed but currently require relatively long scan times. The aim of this study was to assess the ability of black‐blood delay alternating with nutation for tailored excitation‐prepared T1‐weighted variable flip angle turbo spin echo (DANTE T1‐SPACE), which provides relatively high resolution with a short scan time, to visualize neuromelanin in the substantia nigra pars compacta (SNpc). Methods Participants comprised 49 healthy controls and 25 patients with Parkinson's disease (PD). Contrast ratios of SNpc and hyperintense SNpc areas, which show pixels brighter than thresholds, were assessed between DANTE T1‐SPACE and T1‐SPACE in healthy controls. To evaluate the diagnostic ability of DANTE T1‐SPACE, the contrast ratios and hyperintense areas were compared between healthy and PD groups, and receiver operating characteristic analyses were performed. We also compared areas under the curve (AUCs) between DANTE T1‐SPACE and the previously reported gradient echo neuromelanin (GRE‐NM) imaging. Each analysis was performed using original images in native space and images transformed into Montreal Neurological Institute space. Values of P < 0.05 were considered significant. Results DANTE T1‐SPACE showed significantly higher contrast ratios and larger hyperintense areas than T1‐SPACE. On DANTE T1‐SPACE, healthy controls showed significantly higher contrast ratios and larger hyperintense areas than patients with PD. Hyperintense areas in native space analysis achieved the best AUC (0.94). DANTE T1‐SPACE showed AUCs as high as those of GRE‐NM. Conclusions DANTE T1‐SPACE successfully visualized neuromelanin of the SNpc and showed potential for evaluating PD. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Longitudinal Changes in Neuromelanin MRI Signal in Parkinson's Disease: A Progression Marker

“…Experienced raters can achieve good reproducibility of measurements, as it was in our case, in line with those reported in previous studies 18,23,30,39,44‐46,48,66 . Second, 2‐dimensional acquisitions using a relatively thick slice are prone to partial voluming, and the use of 3‐D acquisitions may improve the accuracy of the results 78 . Third, improved CNR in SN compared with background signal may be obtained by using different acquisition schemes like magnetization transfer 11,37,72 or double inversion T1‐weighted imaging, although improved CNR offered by these MRI protocols comes at the expense of acquisition times.…”

“…17,29 SN volume appears highly variable when measured using MRI. 11,12,30,31 Many factors contribute to this variability such as the type of sequence that was used including T2*-weighted imaging at 7 T, 32 driven equilibrium single-pulse observation of T1, 33 Fast Gray Matter Acquisition T1 Inversion Recovery, 34 DANTE T1-SPACE, 35 and short-echo-time magnitude image derived from quantitative susceptibility mapping, 11,12,23,31,36,37 Previous studies using NM-sensitive images have also measured variable SN volumes ranging from about 110 to 500 mm 3 . 11,12,23,30,31 These measurements depended on the method used for volume calculation, the number of image slices used for SN segmentation, and the imaging parameters such as slice thickness, which determined the amount of partial voluming in images.…”

“… 18 , 23 , 30 , 39 , 44 , 45 , 46 , 48 , 66 Second, 2‐dimensional acquisitions using a relatively thick slice are prone to partial voluming, and the use of 3‐D acquisitions may improve the accuracy of the results. 78 Third, improved CNR in SN compared with background signal may be obtained by using different acquisition schemes like magnetization transfer 11 , 37 , 72 or double inversion T1‐weighted imaging, although improved CNR offered by these MRI protocols comes at the expense of acquisition times. Fourth, direct quantitative methods, including T1 mapping 79 or magnetization transfer, remains to be evaluated.…”

Deep Learning‐Based Neuromelanin MRI Changes of Isolated REM Sleep Behavior Disorder

“…As a result, experienced raters can deliver highly reproducible segmentations. 37,38 Second, the implementation of 3D acquisitions may possibly increase the accuracy of the results 39 by enabling isotropic voxel acquisitions, reducing partial voluming and eliminating or reducing artifacts (eg, caused by cross-talk between slices in 2D sequences). Moreover, more clinical assessments are warranted to understand the clinical significance of SNc neuromelanin loss in iRBD.…”

Vessel wall MR imaging in neuroradiology

“…CSF is known to affect vessel walls [ 27 ]. DANTE pulse is also used for intravascular signal suppression of arterial spin labeling [ 28 ], detection of brain metastasis [ 29 ], and neuromelanin-sensitive MRI due to certain magnetization transfer (MT) effect [ 30 ]. With acceleration of parallel imaging, high-resolution vessel wall imaging using DANTE pulse can be available in clinically feasible scan time [ 30 , 31 ].…”