1353240 - Highly-accelerated Real-time Cine MRI with Radial k-space Sampling and View Sharing and KWIC Filtering in Patients with a Cardiac Implantable Electronic Device

Breath-held (BH) cardiac cine MRI with gradient echo readout is the current standard for imaging patients with a cardiac implantable electronic device (CIED). Because these patients frequently have arrhythmias with limited BH ability, free-breathing real-time (FB-RT) cine MRI may be desirable to overcome image artifacts arising from arrhythmia and/or respiratory motion. We had previously described a 16-fold accelerated FB-RT cine using Cartesian k-space sampling and compressed-sensing (CS)[1], which produced accurate LV volumes and functional measurements. This pulse sequence, however, was limited by blurring artifacts arising from high data acceleration. We sought to develop and evaluate a 32-fold accelerated cine using a combination of radial k-space sampling, view-sharing (VS), and k-space weighted image contrast (KWIC)[2] filtering in patients with CIEDs.

Methods:

MRI: We enrolled 12 patients with a CIED (8 men, mean age=67.3 ± 10.5 yrs) and performed 3 different cine scans: standard clinical BH, previously described 16-fold accelerated FB-RT cine using Cartesian k-space sampling, and the proposed FB-RT cine using radial k-space sampling. All imaging was performed on a 1.5T MRI scanner (Avanto, Siemens). The relevant imaging parameters are shown in Figure 1-(a) and referred to [1,3] for other parameters.

Image Reconstruction: For radial cine, we applied 1) a VS to generate a total of 24 k-space projections per frame (ie, 9 shared projections before and after 6 native projections per frame) and 2) a KWIC filter to zero the central portions of shared k-space as shown in Figure 1-(b). We reconstructed cine images using CS [1,3] with a temporal total variation as sparsifying transform (refer to Figure 1-(b)).

Image Analysis: Cardiac contours were segmented using the automatic AI tools followed by manual correction in Circle (cvi42, v5.13.9). We recorded the quantitative results of cardiac function: EDV, ESV, SV, and LVEF. Two experienced raters (a cardiologist and a radiologist) visually evaluated the image quality using 5-point Likert scale (see Table 1). For statistical analysis, one-way ANOVA and Kruskal-Wallis tests were used to compare the quantitative and qualitative results, respectively, with Bonferroni correction.

Results:

Figure 2 shows representative short-axis images from clinical BH, FB-RT Cartesian, and FB-RT radial cines. LV functional results were not significantly different (p >0.05) between three cines. As summarized in Table 1, image quality scores were significantly better for FB-RT radial cine than Cartesian, where all four scores were ≥4 for radial.

Conclusion: 32-fold accelerated FB-RT cine using a combination of radial k-space sampling, VS, and KWIC filtering produces high image quality in patients with a CIED. While improved spatio-temporal resolution may not translate to improved ventricular functional measurements, it may be beneficial for evaluation of wall motion abnormalities associated with coronary artery disease or cardiomyopathies.