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  • Oral presentation
  • Open Access

Fast three-dimensional black-blood MR imaging for carotid artery intra-plaque haemorrhage using DANTE-prepared FLASH (3D-DASH)

  • 1,
  • 2, 3,
  • 3,
  • 2,
  • 3,
  • 4 and
  • 1
Journal of Cardiovascular Magnetic Resonance201416 (Suppl 1) :O75

https://doi.org/10.1186/1532-429X-16-S1-O75

  • Published:

Keywords

  • Longitudinal Magnetization
  • Isotropic Resolution
  • Double Inversion Recovery
  • Vessel Wall Imaging
  • Oxford Biomedical Research

Background

DANTE (Delays Alternating with Nutation for Tailored Excitation) pulse trains are a rapid series of low flip angle RF pulses interspersed with gradients. We have previously demonstrated that when using DANTE pulse trains as a preparation module prior to imaging readout, the longitudinal magnetization of flowing spins is substantially attenuated, whereas the longitudinal magnetization of static tissue/fluid is mostly preserved [1]. In this study we introduce a new DANTE-prepared 3D FLASH T1 weighted (T1w) sequence (denoted '3D-DASH')[2] that is able to generate 0.6 mm isotropic resolution images with an average imaging speed better than 2 sec/slice.

Methods

6 healthy volunteers (males, 24 to 35 years) underwent (i) DIR (double inversion recovery)-prepared 2D-TSE, (ii) 3D-DASH and (iii) comparison MSDE prepared FLASH, 3D-MERGE, imaging[3]. 4 symptomatic patients (age range, 54-86) scheduled for carotid endarterectomy (> 70% stenosis measured by ultrasound) underwent the same vessel wall imaging protocol. Written informed consent was obtained from all subjects. All scans were acquired using a 3T Siemens Verio scanner. A pair of dual-channel surface coils (Machnet, The Netherlands) were used. Cardiac gating was used for comparison DIR-prepared black blood scans. Protocol: axial imaging acquisition, identical 3D FLASH readout sequences for 3D-DASH and 3D-MERGE, FOV = 150 × 150 mm, matrix size 256 × 252, interpolated to 512 × 512, partition thickness = 0.6 mm, Number of averages = 2, iPat = 2, slices = 128, FLASH flip angle α = 10°, slice resolution = 63%, phase and slice partial FT = 6/8, Fat suppression = water excitation-fast, TRinternal = 10 ms, BW = 130 Hz/pixel, resolution = 0.6 mm isotropic. Parameters for the DANTE module: flip angle (FA) α = 15°; Number of pulses Np = 150; time duration between DANTE pulses, tD = 1 ms; Gx, y, z = 20 mT/m; gradient duration≈1 ms.

Results

Examples of the T1w image quality for the 3D-DASH sequence with 0.6 mm isotropic resolution versus the gold standard single-slice DIR-TSE sequence with slice thickness 2 mm are shown in Figure 1. The 3D-DASH scan acquisition time was 198 seconds, with > 6 cm coverage (128 slices). The hyper-intense signal on the T1w images indicates the presence of fresh intra-plaque haemorrhage (IPH) confirmed by histological examination shown in Figure 2. Compared with the current best 3D black blood (BB) technique (results were not shown), 3D-MERGE, 3D-DASH allows 75%-100% improvement in contrast-to-noise efficiency, CNReff.
Figure 1
Figure 1

T1w 3D-DASH images obtained from a patient with intra-plaque haemorrhage. a) 24 contiguous-slice whole plaque coverage from 3D-DASH images with isotropic 0.6 mm resolution. b) 3D-MPR sagittal view of the left carotid arteries reconstructed from the full 128-slice 3D-DASH dataset. c) 3D-MPR sagittal view reconstructed from the 3D-TOF data for comparison. d) Axial view slices of 3D-DASH and e) DIR-prepared 2D-TSE images taken from the same slice positions for direct comparison.

Figure 2
Figure 2

This histology figure confirms the presence of intra-plaque haemorrhage of the patient plaque in Fig. 4. a) Hematoxylin and eosin stain(H&E). * lumen; § fibrous cap; +surgical artefacts. b) Maisson's trichrome staining of serial 5 μm plaque sections. These images show a large lipid-rich necrotic core (LRNC) within an eccentric carotid atherosclerotic plaque with recent intra-plaque haemorrhage (IPH). c) Fibrin (in blood) stained bright pink in H&E and bright red in trichrome. Background lipid core seen as cholesterol clefts. Collagen stained green in trichrome. Calcification stained blue by haematoxylin and remained pale/unstained in trichrome. d) Image taken from section location 6 mm above bifurcation.

Conclusions

3D-DASH is a promising new sequence for 3D isotropic (0.6 mm) fast black-blood T1 weighted imaging of the carotid arteries with high sensitivity to intra-plaque haemorrhage.

Funding

We thank the NIHR Oxford Biomedical Research Centre, BHF, and Dunhill Medical Trust for grant funding.

Authors’ Affiliations

(1)
Department of Clinical Neurosciences, University of Oxford, Oxford, UK
(2)
Department of Medicine, University of Oxford, Oxford, UK
(3)
Acute Vascular Imaging Centre, University of Oxford, Oxford, UK
(4)
Department of Surgery, University of Oxford, Oxford, UK

Copyright

© Li et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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