Single breath-hold whole heart coronary MRA with isotropic spatial resolution using highly-accelerated parallel imaging with a 32-element coil array
Journal of Cardiovascular Magnetic Resonance volume 12, Article number: P47 (2010)
Whole heart coronary MRA (CMRA) is typically performed with navigator gating because of the extensive data acquisition needed to achieve an isotropic spatial resolution on the order of 1-2 mm3 with full anatomic coverage (10-16 cm). Previous studies have shown that whole heart CMRA can be performed with either a single  or double [2, 3] breath-hold (BH) approach using highly-accelerated parallel imaging. The single breath-hold approach  acquires the coil sensitivity data immediately before and after the coronary MRA data within the same cardiac cycle, whereas the double BH approach acquires coil sensitivity data in a separate BH. The single BH approach lengthens the time between the T2 and fat suppression pulses to the image acquisition, and the double BH approach may suffer from misregistration. We propose to acquire the coil sensitivity and coronary MRA data in two separate cardiac phases (early systole and mid diastole, respectively) both within a single BH, in order to circumvent the aforementioned problems.
To develop a robust single BH whole heart CMRA scan with isotropic spatial resolution.
Experimental studies were performed in 2 healthy volunteers on a 1.5 T scanner (Siemens;Avanto). The relevant steady state free precession (TrueFisp) pulse sequence parameters are: FOV 360 × 360 × 102 mm3, Matrix 224 × 224 × 64, slice thickness 1.6 mm, the voxel size is 1.6 × 1.6 × 1.6 mm3, interpolated to 0.8 × 0.8 × 0.8 mm3, acceleration-factor 4 × 2 (4 in PE and 2 in PA direction), segment 42, TR 3 ms, TE 1.4 ms, partial Fourier in both PE and PA directions (6/8), slice oversampling-rate 12.5%, T2 and fat-suppression preparation pulses were used. Image reconstruction was performed using the 2D GRAPPA technique. Using identical parameters, we compared two cases: 1) double BH approach and 2) single BH approach where the coil sensitivity and image data are acquired at early systole and mid diastole, respectively (Figure 1). To investigate the inter-study variability, we repeated the image acquisitions for both subjects.
Figure 2 shows representative images that demonstrate improvement using the single BH approach. The new single BH approach produced less "pseudo-noise" artifacts than the double BH approach, owing to improved registration and consistently improved image quality compared with the double BH approach in both subjects during repeated sessions.
We demonstrate the feasibility of performing single BH whole heart CMRA with isotropic spatial resolution. Compared with the double BH approach, the new single BH approach yielded less "pseudo-noise" artifacts in the GRAPPA reconstruction. This approach has the potential to improve diagnostic accuracy for rapid volumetric CMRA.
Jaeseaok Park et al: High-resolution steady-state free precession coronary magnetic resonance angiography within a breath-hold: parallel imaging with extended cardiac data acquision. Magnetic Resonance in Medicine. 2005, B54B: 1100-1106.
Thoralf Niendorf et al: Toward a single breath-hold whole-heart coverage coronary MRA using highly accelerated parallel imaging with a 32-channel MR system. Magnetic Resonance in Medicine. 2006, 56: 167-176. 10.1002/mrm.20923.
Jian Xu et al: Feasibility of five-minute comprehensive cardiac MR examination using highly accelerated parallel imaging with a 32-element coil array. ISMRM Honolulu. 2009, 725-
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Xu, J., Kim, D., Otazo, R. et al. Single breath-hold whole heart coronary MRA with isotropic spatial resolution using highly-accelerated parallel imaging with a 32-element coil array. J Cardiovasc Magn Reson 12 (Suppl 1), P47 (2010). https://doi.org/10.1186/1532-429X-12-S1-P47