Feasibility of coronary artery wall thickening assessment in asymptomatic coronary artery disease using phase-sensitive dual-inversion recovery MRI at 3T

Abstract

Objectives: The purpose of this study was to (a) investigate the image quality of phase-sensitive dual-inversion recovery (PS-DIR) coronary wall imaging in healthy subjects and in subjects with known coronary artery disease (CAD) and to (b) investigate the utilization of PS-DIR at 3T in the assessment of coronary artery thickening in subjects with asymptomatic but variable degrees of CAD.

Materials and methods: A total of 37 subjects participated in this institutional review board-approved and HIPAA-compliant study. These included 21 subjects with known CAD as identified on multidetector computed tomography angiography (MDCT). Sixteen healthy subjects without known history of CAD were included. All subjects were scanned using free-breathing PS-DIR magnetic resonance imaging (MRI) for the assessment of coronary wall thickness at 3T. Lumen-tissue contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and quantitative vessel parameters including lumen area and wall thickness were measured. Statistical analyses were performed.

Results: PS-DIR was successfully completed in 76% of patients and in 88% of the healthy subjects. Phase-sensitive signed-magnitude reconstruction, compared to modulus-magnitude images, significantly improved lumen-tissue CNR in healthy subjects (26.73±11.95 vs. 14.65±9.57, P<.001) and in patients (21.45±7.61 vs. 16.65±5.85, P<.001). There was no difference in image CNR and SNR between groups. In arterial segments free of plaques, coronary wall was thicker in patients in comparison to healthy subjects (1.74±0.27 mm vs. 1.17±0.14 mm, P<.001), without a change in lumen area (4.51±2.42 mm2 vs. 5.71±3.11mm2, P=.25).

Conclusions: This is the first study to demonstrate the feasibility of successfully obtaining vessel wall images at 3T using PS-DIR in asymptomatic patients with known variable degrees of CAD as detected by MDCT. This was achieved with a fixed subject-invariant planning of blood signal nulling. With that limitation alleviated, PS-DIR coronary wall MRI is capable of detecting arterial thickening and positive arterial remodeling at 3T in asymptomatic CAD.

Keywords: 3T; Atherosclerosis; Black blood MRI; Coronary artery imaging; Dual-inversion recovery; Phase sensitive; Vessel wall.

Figure 1

The sequence diagram for free-breathing navigator-guided PS-DIR utilizing 2D spiral imaging of the coronary vessel wall with double inversion recovery black blood preparation and phase-sensitive lumen reconstruction. Every cardiac cycle the black blood preparation is directly followed by a navigator-restore pulse to restore the inverted magnetization at the navigator site. A navigator signal is acquired before data acquisition to accept or reject data. Data acquisition starts at the subject-specific rest period trigger delay (TD) using the water-selective pulse followed by a single shot spiral interleaf.

Figure 2

Coronary arterial wall PS-DIR images of healthy and CAD subjects. Signed-magnitude PS-DIR reconstruction (top row) successfully restores lumen-wall contrast. The bright artifact signals in the middle of arterial lumen (middle row, broken arrows) were successfully suppressed using the phase information (bottom row) during reconstruction of the PS-DIR images (solid arrows).

Figure 3

Healthy subjects and CAD patients’ box-and-whisker diagrams of the right coronary artery (a) vessel wall thickness, (b) vessel wall thickness with the healthy subjects’ measurements adjusted for age, and (c) lumen area.

Figure 4

Coronary wall thickness and area in CAD patients vs. healthy subjects. Results represent mean values ± 1 standard deviation.