Dark-rim Artifacts Research Articles

Myocardial First Pass Perfusion Imaging With Gadobutrol

To implement parallel imaging algorithms in fast gradient recalled echo sequences for myocardial perfusion imaging and evaluate image quality, signal-to-noise ratio (SNR), contrast-enhancement ratio (CER), and semiquantitative perfusion parameters. In 20 volunteers, myocardial perfusion imaging with gadobutrol was performed at rest using an accelerated TurboFLASH sequence (TR 2.3 milliseconds, TE 0.93 milliseconds, flip angle [FA] 15 degrees) with GRAPPA, R=2. A nonaccelerated TurboFLASH sequence with similar scan parameters served as standard of reference. Artifacts were assessed qualitatively. SNR, CER, and CNR were calculated and semiquantitative perfusion parameters were determined from fitted SI-time curves. Phantom measurements yielded significant higher SNR for nonaccelerated images (P<0.001). CER was equal; differences in CNR were statistically nonsignificant. The evaluation of semiquantitative perfusion parameters yielded significantly higher peak signal intensities in nonaccelerated images (P<0.001). Differences in maximum upslope were statistically nonsignificant. A qualitative examination of all images for artifacts by 2 board-certified radiologists yielded a significant reduction in dark rim artifacts with GRAPPA, R=2 (P<0.001). The application of GRAPPA with an acceleration factor of R=2 leads to a significant reduction of dark rim artifacts in fast gradient recalled echo sequences.

High-resolution myocardial perfusion imaging at 3 T: comparison to 1.5 T in healthy volunteers

The purpose of this study was to evaluate high-resolution (HR) myocardial first-pass perfusion in healthy volunteers at 3 T compared to a typical clinical imaging protocol at 1.5 T, with respect to overall image quality and the presence of subendocardial dark rim artifacts. Myocardial first-pass rest perfusion studies were performed at both field strengths using a T1-weighted saturation-recovery segmented k-space gradient-echo sequence combined with parallel imaging (Gd-DTPA 0.05 mmol/kg). Twenty-six healthy volunteers underwent (1) a HR perfusion scan at 3 T(pixel size 3.78 mm(2)) and (2) a standard perfusion approach at 1.5 T(pixel size 9.86 mm(2)). The contrast enhancement ratio (CER) and overall image quality (4-point grading scale: 4: excellent; 1: non-diagnostic) were assessed, and a semiquantitative analysis of dark rim artifacts was performed for all studies. CER was slightly higher (1.31 +/- 0.32 vs. 1.14 +/- 0.34; p<0.01), overall image quality was significantly improved (3.03 +/- 0.43 vs. 2.37 +/- 0.39; p<0.01), and the number of dark rim artifacts (139 +/- 2.09 vs. 243 +/- 2.33; p<0.01) was significantly reduced for HR perfusion imaging at 3 T compared to the standard approach at 1.5 T. HR myocardial rest perfusion at 3 T is superior to the typical clinical perfusion protocol performed at 1.5 T with respect to the overall image quality and presence of subendocardial dark rim artifacts.

On the dark rim artifact in dynamic contrast‐enhanced MRI myocardial perfusion studies

A dark band or rim along parts of the subendocardial border of the left ventricle (LV) and the myocardium has been noticed in some dynamic contrast-enhanced MR perfusion studies. The artifact is thought to be due to susceptibility effects from the gadolinium bolus, motion, or resolution, or a combination of these. Here motionless ex vivo hearts in which the cavity was filled with gadolinium are used to show that dark rim artifacts can be consistent with resolution effects alone.