Volumetric late gadolinium-enhanced myocardial imaging with retrospective inversion time selection.

PURPOSE: To develop and validate a novel free-breathing 3D radial late gadolinium-enhanced magnetic resonance imaging technique (3D LGE-MRI) with isotropic resolution and retrospective inversion time (TI) selection for myocardial viability imaging.
MATERIALS AND METHODS: The 3D radial LGE-MRI method featuring an interleaved and bit-reversed radial k-space trajectory was evaluated in 12 subjects that also had clinical breath-hold Cartesian 2D LGE-MRI. The 3D LGE-MRI acquisition requires a predicted TI and a user-controlled data acquisition window that determines the sampling width around the predicted TI. Sliding window reconstructions with update rates of 1× the repetition time (TR) allow for a user selectable TI to obtain the maximum nulling of the myocardium. The retrospective nature of the acquisition allows the user to choose from a range of possible TI times centered on the expected TI. Those projections most corrupted by respiratory motion, as determined by a respiratory bellows signal, were resampled according to the diminishing variance algorithm. The quality of the left ventricular myocardial nulling on the 3D LGE-MRI and 2D LGE-MRI was assessed using a 4-point Likert scale by two experienced radiologists. Comparison of image quality scores for the two methods was performed using generalized estimating equations.
RESULTS: All 3D LGE-MRI cases produced similar nulling of myocardial signal as the 2D LGE-MRI. The image quality of myocardial nulling was not significantly different between the two acquisitions (mean nulling of 3.4 for 2D vs. 3.1 for 3D, and P = 0.0645). The average absolute deviation from mean scores was also not determined to be statistically significant (1.8 for 2D and 0.4 for 3D and P = 0.1673). Total acquisition time was ∼9 minutes for 3D LGE-MRI with voxel sizes ranging from 1.6(3) to 2.0(3) mm(3) . Conversely, the total imaging time was twice as long for the 2D DCE-MRI (>17 minutes) with an eight times larger voxel size of 1.4 × 2.2 × 7.0 mm.
CONCLUSION: The 3D LGE-MRI technique demonstrated in this study is a promising alternative for the assessment of myocardial viability in patients who have difficulty sustaining breath-holds for the clinical standard 2D LGE-MRI.