An Intra-individual Comparison between Free-breathing Dynamic MR Imaging of the Liver Using Stack-of-stars Acquisition and the Breath-holding Method Using Cartesian Sampling or View-sharing

Abstract

To compare the quality of dynamic imaging between stack-of-stars acquisition without breathholding (DISCO-Star) and the breath-holding method (Cartesian LAVA and DISCO).Methods: This retrospective study was conducted between October 2019 and February 2020. Two radiologists performed visual assessments of respiratory motion or pulsation artifacts, streak artifacts, liver edge sharpness, and overall image quality using a 5-point scale for two datasets: Dataset 1 (n = 107), patients with Cartesian LAVA and DISCO-Star; Dataset 2 (n = 41), patients with DISCO and DISCO-Star at different time points. Diagnosable image quality was defined as ≥ 3 points in overall image quality. Whether the scan timing of the arterial phase (AP) was appropriate was evaluated, and results between the pulse sequences were compared. In cases of inappropriate scan timing in the DISCO-Star group, retrospective reconstruction with a high frame rate (80 phases, 3 s/phase) was added. Results:The overall image quality of Cartesian LAVA was better than that of DISCO-Star in AP. However, noninferiority was shown in the ratio of diagnosable images between Cartesian LAVA and DISCO-Star in AP. There was no significant difference in the ratio of appropriate scan timing between DISCO-Star and Cartesian LAVA; however, the ratio of appropriate scan timing in DISCO-Star with high frame rate reconstruction was significantly higher than that in Cartesian LAVA in both readers. Overall image quality scores between DISCO and DISCO-Star were not significantly different in AP. There was no significant difference in the ratio of appropriate scan timing between DISCO-Star with high frame rate reconstruction and DISCO in both readers. Conclusion:The use of DISCO-Star with high frame rate reconstruction is a good solution to obtain appropriate AP scan timing compared with Cartesian LAVA. DISCO-Star showed equivalent image quality in all phases and in the ratio of appropriate AP scan timing compared with DISCO.

Pulse Sequences and Reconstruction in Fast MR Imaging of the Liver

“…47,48 Advancements in motion monitoring and motion correction opened the door to free-breathing liver T 1 dynamic acquisition. 30,32 Liver motion was monitored by external devices or navigator pulse sequence 49 for years; however, recent advanced radial k-space acquisition methods can detect motion information from acquired k-space data itself. 30 These advanced self-navigation radial pulse sequences allow us to acquire free-breathing T 1 dynamic MR imaging.…”

“…View-sharing technology that utilizes radial sampling, including golden-angle radial sparse parallel imaging (GRASP), 30 has been accepted in clinical settings. 31 , 32 Theoretically, apparent temporal resolution can be reached up to the acquisition time for a single radial kx-kz plane for radial k-space filling; however, it should be noted that a certain acquisition window length needs to be kept to obtain acceptable image quality.…”

Evaluation and Prediction of Treatment Response for Hepatocellular Carcinoma

“…[52][53][54] Dynamic contrast-enhanced MRI under free-breathing using a stack-of-stars technique was developed as a method to evaluate the blood perfusion over time, and may be applied in the future to evaluate the early therapeutic effect of HCC after lenvatinib administration. 55,56 Evaluation of Treatment Response after ICI (Fig. 5)…”

Clinical Significance of Liver MR Imaging

“…Inappropriate scan timing is also not an issue in free-breathing dynamic MRI with stack-of-stars acquisition because it is possible to obtain continuous images from the AP to the PVP and the transitional phase (TP) with one scan. 60 , 61 However, it is difficult for free-breathing dynamic MRI with stack-of-stars acquisition to outperform breath-holding Cartesian sampling and multiphasic AP imaging in terms of image quality in patients who can hold their breath for a prolonged period. Therefore, Cartesian sampling or multiphasic AP imaging may be better than stack-of-stars acquisition as a routine sequence.…”