Influence of the reference scan and scan time on the arterial phase of liver magnetic resonance imaging.

Abstract

The controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique can decrease scan time. The purpose of this study was to determine whether an arterial phase scan can be performed in 5s using the CAIPIRINHA short-scan and a reference scanning technique. The generalized autocalibrating partially parallel acquisition (GRAPPA), the CAIPIRINHA routine (CAIPI-routine), and the CAIPIRINHA short-scanning (CAIPI-short) methods were compared. The scan time for each method was preset to 20s, 15s, and 10s, respectively. The reference scan had a scan time of 5s. A phantom study was used to compare the influence of artifacts during the reference scan. For comparison, the phantom was moved during the last 5s. In the clinical studies of suspected chronic liver diseases, magnetic resonance imaging of the liver is usually performed while the patient is breath-hold. The motion artifacts of each method were compared. Artifacts were reduced in reference scans using the CAIPIRINHA method. At 5s after initiation, the rate of change in the standard deviation value was within 30% compared to that of the original image. Motion artifacts due to the influence of the reference scan when a patient failed to hold their breath did not complicate image evaluation. The proportion of motion artifacts for each sequence was as follows: GRAPPA, 5.8%; CAIPI-routine, 1.9%; and CAIPI-short, 0.7%. The arterial phase can be scanned in 5s using the CAIPI-short and reference scan techniques.