Three-dimensional joint bright, gray, and black blood magnetic resonance imaging technique for multi-parametric imaging of carotid artery: A feasibility and repeatability study

Figures

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  Fig. 1. Schematic overview of the proposed 3D joint bright, gray, and black blood imaging technique for multi-parametric imaging of carotid artery. Six scans in 3D multi-shot SPGR acquisition with SPIR fat suppression were sequentially acquired and retrospectively registered. VFA (α1,2,3 = 18°, 12°, 6°), ViMSDE (TEprep = 0, 13, 25 ms), and VTE (TE = 3.3, 9.4, 15.5, 21.6 ms) mapping strategies were applied to acquire images with varying contrast, further generating T1, T2, and T2* maps. The natural inflow enhancement and blood suppression module were incorporated to acquire bright blood, gray blood, and black blood images. A B1-specific dictionary was simulated and matched to the measured signal to generate T1 and T2 maps while least square fitting was applied for T2* estimation. 3D three-dimensional, SPGR spoiled gradient-recalled echo, SPIR spectral presaturation with inversion-recovery, VFA varying flip angles, iMSDE improved motion-sensitized driven equilibrium, ViMSDE variable duration of iMSDE prepulse, TE time of echo, TEprep TE preparation, VTE varying time of echo, MR magnetic resonance, IPH intraplaque hemorrhage, LRNC lipid-rich necrotic core, LM loose matrix

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  Fig. 2. Multi-parametric maps and regression lines of phantom study. (a) T1, T2, and T2* maps estimated by the standard mapping sequences (T1: IR-SE, T2: ME-SE, T2*: ME-GRE), reference sequences (T1: MOLLI, T2: GraSE, T2*: ME-TFE) and proposed technique. (b) Linear regression of T1, T2, and T2* measured by the proposed technique and reference sequences against the standard mapping sequences. IR-SE inversion-recovery spin echo, ME-SE multi-echo spin echo, ME-GRE multi-echo gradient echo, MOLLI modified Look-Locker inversion-recovery, GraSE gradient and spin echo, ME-TFE multi-echo turbo field echo

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  Fig. 3. Bland-Altman plots of measured T1 (a), T2 (b), and T2* (c) value of cervical muscle in the proposed and reference sequences (T1: MOLLI; T2: GraSE; T2*: ME-TFE) on eight healthy volunteers. The blue solid lines indicate the measurement bias: T1 bias = 4.8%; T2 bias = −3.3%; T2* bias = −0.6%. MOLLI modified Look-Locker inversion-recovery, GraSE gradient and spin echo, ME-TFE multi-echo turbo field echo, SD standard deviation

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  Fig. 4. Multi-contrast (a) and multi-parametric (b) images acquired and estimated using the proposed technique, shown in CPR and axial views of a 64-year-old woman with 9% stenosis. The CPR images exhibiting the longitudinal view were reconstructed from manually extracted vessel centerline on scan 4 (slices in distal bifurcation region were excluded due to poor image quality). Representative axial slices from common carotid artery, bifurcation, and internal carotid artery are shown. Typical LM (yellow arrow, hyper-intense on scans 4 and 5, and high T2 value on T2 map) and LRNC (white arrow, hypo-intense on scans 4 and 5, and low T2 value on T2 map) signal characteristics and mapping values can be observed in the slice from common carotid artery. CPR curved-planar reformation, LM loose matrix, LRNC large lipid-rich necrotic core

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  Fig. 5. Discrepancies in lumen boundary interpretation between the incorporated blood contrast and black blood contrast groups. The blue solid line, red solid line, and yellow dashed line stand for vessel wall contour, lumen contour identified by the incorporated blood contrast group, and lumen contour identified by the black blood contrast group, respectively. The cases (a-c) showed that the black blood contrast group tended to underestimate LA when incomplete blood suppression occurred. The cases (d, e) showed that the black blood contrast group tended to overestimate LA when superficial CA existed. LA lumen area, CA calcification

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  Fig. 6. The visibility of different types of CA on the gray blood and black images. Scans 3 and 4 were shown as the representative contrasts for the incorporated blood contrast and black blood contrast group, respectively. The solid arrow stands for the visible CA, while the hollow arrow stands for the invisible CA. CA (case a) presence inside the vessel wall was detected by both the gray blood and black blood images. Superficial CA (case b-d) existing on the junction region of lumen and vessel wall was clearly depicted on gray blood image rather than black blood image with an ambiguous boundary. The small CA (case e-h), which was used to be overlooked in the black blood image, was clearly visualized on gray blood images. CA calcification

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  Fig. 7. Multi-contrast and multi-parametric images of an IPH and CA coexistent 64-year-old man with stenosis ratio of 8%. The IPH and CA were first identified on multi-contrast images (T1w, T2w, and TOF), then mapped to the reconstructed 2-mm images of proposed technique for quantitative parameter estimation. CA (yellow arrow, excluded from quantitative parameters estimation) was recognized as dark signal on both images, especially TOF and scans 1-3. IPH (white arrow, T1: 528.1 ms; T2: 38.2 ms; T2*: 18.1 ms) was recognized as hyper-intense on T1w and scans 1 and 2, as well as low value on T1 and T2* map. IPH intraplaque hemorrhage, TOF time of flight, CA calcification

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  Fig. 8. Multi-contrast and multi-parametric images of a LM and LRNC coexistent 83-year-old man with stenosis ratio of 90%. The LM and LRNC were first identified on multi-contrast images (T1w, T2w, and TOF), then mapped to the reconstructed 2-mm images of the proposed technique for quantitative parameter estimation. LM (yellow arrow, T1: 1065.1 ms; T2: 45.4 ms; T2*: 30.5 ms) was recognized as hyper-intense on T2w and scans 4 and 5, as well as high value on T2 map. LRNC (white arrow, T1: 1082.5 ms; T2: 29.7 ms; T2*: 20.9 ms) was recognized as hypo-intense on T2w and scans 4 and 5, as well as low value on T2 map. LM loose matrix, LRNC large lipid-rich necrotic core, TOF time of flight