Impact of Radial Percentage K-Space Filling and Signal Averaging on Native Lung MRI Image Quality in 3D Radial UTE Acquisition: A Pilot Study

Abstract

To assess the impact of radial percentage k-space filling and signal averaging on lung MRI image quality in 3D radial ultrashort echo-time (UTE) acquisition. In this IRB approved prospective study, 25 patients (10-30 years) referred for MRI examination for indications other than related to lungs were enrolled from January 2021 to November 2021. All the patients underwent lung MRI, using three different UTE sequence parameters with radial (R) percentage of 100 or 200 and number of signal averages (NSA) of one or two. Two radiologists independently assessed the images for the outline of pleural and mediastinal surface, visibility of lung parenchyma, major bronchi, and segmental bronchi. The quality of the images was assessed based on the degree of motion artifacts. For objective assessment, signal-to-noise ratio, contrast-to-noise ratio, and contrast ratio were calculated. The outline of pleural and mediastinal surface, lung parenchyma, and segmental bronchi were best demonstrated on R100_NSA2 sequence. The major bronchi were best demonstrated on R100_NSA2 and R100_NSA1 sequences. The intersequence difference was statistically significant for evaluating the pleural and mediastinal surface and segmental bronchi only (p < 0.05). Overall, the best image quality with least artifacts was seen with R100_NSA2 sequence. The objective assessment showed no statistically significant difference between the three sequences (p > 0.05). Interobserver agreement for different findings was substantial to almost perfect for R100_NSA2 and R200_NSA1 sequences. R100_NSA2 UTE sequence performed best for the evaluation of the different findings and showed the best image quality.