Development of respiratory motion-resolved hepatobiliary phase cine-magnetic resonance imaging for stereotactic body radiotherapy in liver tumor

Cine-magnetic resonance imaging (MRI) has been used to track respiratory-induced motion of the liver and tumor and assist in the accurate delineation of tumor volume. Recent developments in compressed sensitivity encoding (SENSE; CS) have accelerated temporal resolution while maintaining contrast resolution. This study aimed to develop and assess hepatobiliary phase (HBP) cine-MRI scans using CS. Phantom was imaged using cine-MRI and signal intensity (SI) and contrast ratio (CR) measured to determine the optimal flip-angle turbo field echo (TFE) prepulse delay. We performed cine-MRI in 20 patients for one minute, with images taken every 0.5 s after administration of gadoxetic acid contrast agent. Acquired images had three different acceleration factors (SENSE, CS without denoising [CS-no], and CS with strong denoising [CS-strong]). The image quality of the HBP cine MRI was quantitatively and qualitatively analyzed. In the phantom study, a flip angle of 30 degrees and TFE prepulse delay of 150 ms were optimal for clinical imaging. In a clinical study, CS-strong showed the highest signal-to-noise ratio and comparable contrast ratio among the three sequences. The CS-strong group showed a significantly higher image quality (P < 0.01), except for motion smoothness (P = 0.11). CS with denoising improved the tumor-to-liver contrast and image quality in high-temporal-resolution HBP cine MRI.