High‐resolution MR‐imaging of the liver with T2‐weighted sequences using integrated parallel imaging: Comparison of prospective motion correction and respiratory triggering

Abstract

Purpose:To compare high-resolution T2-weigthed images of the liver with and without integrated parallel acquisition techniques (iPAT) using either breath-hold sequences in combination with prospective acquisition motion correction (PACE) or respiratory triggering. Materials and Methods:Ten volunteers and 10 patients underwent each four different high-resolution fast spin echo (FSE) T2-weigthed sequences with 5 mm slice thickness and a full 320 matrix: a multi-breath-hold FSE sequence with and without iPAT and PACE and a respiratory-triggered FSE sequence with and without iPAT. Image quality was rated with a five-point scale by two independent readers. Signal intensity measurements were performed on a water phantom. Results:The sequences with iPAT required a substantially shorter acquisition time without loss of image quality. Overall image quality was rated equal for all sequences by both readers. Image time for nine slices with iPAT was 13 seconds (19 seconds without iPAT) with multi-breath-hold and on average 4:00 minutes (7:02 minutes without iPAT) with respiratory triggering. Imaging with the PACE technique resulted in more correct positioning of the image stacks.Conclusion: T2-weighted fast imaging with iPAT is feasible and results in high-quality images within a short acquisition time. Overall image quality is not negatively affected by iPAT.

Navigator‐triggered prospective acquisition correction (PACE) technique vs. conventional respiratory‐triggered technique for free‐breathing 3D MRCP: An initial prospective comparative study using healthy volunteers

“…Movement of the abdominal wall is commonly monitored by a special belt rolled around the upper abdomen to monitor respiratory motion (6). This method can monitor the respiratory cycle easily.…”

“…The navigator-triggered technique has recently been applied to another motion correction method (5)(6)(7)(8)(9). This technique can reduce respiratory motion artifacts by directly monitoring the movement of the right diaphragm with navigator echoes (5)(6)(7)9).…”

“…This technique can reduce respiratory motion artifacts by directly monitoring the movement of the right diaphragm with navigator echoes (5)(6)(7)9). It has mainly been used for cardiac imaging, called the navigator technique or 1D-prospective acquisition correction (1D-PACE) technique (9 -12).…”

“…For these reasons, the 2D-PACE technique has been used for imaging the abdominal area (5)(6)(7)(8). Its superiority to conventional RESP technique for 2D sequences of the upper abdominal area has been reported (6,7).…”

“…Its superiority to conventional RESP technique for 2D sequences of the upper abdominal area has been reported (6,7). However, judging from many past reports about 3D whole-heart coronary magnetic resonance angiography (9 -12), such an improved motion correction technique will be even more valuable for 3D sequences.…”