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

Abstract

Purpose:To confirm the superiority of the navigator-triggered prospective acquisition correction (PACE) technique over the conventional respiratory-triggered (RESP) technique, something that has been perceived experimentally but without definite evidence, for free-breathing three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) using healthy volunteers. Materials and Methods:Free-breathing 3D turbo spinecho MRCP using both PACE and RESP techniques were prospectively performed on 25 healthy volunteers. Quantitative analyses of acquisition time, signal-to-noise ratio, contrast-to-noise ratio, and contour sharpness index of each segment of the pancreaticobiliary tree were compared using the paired t-test. Qualitative analyses on a five-point scale (1, excellent; 5, poor) scored by two independent radiologists were compared using the Wilcoxon signed-rank test. Results:The subjective image quality and contour sharpness index of each segment of the PACE technique were found to be significantly better than those for RESP (P Ͻ 0.05). No significant difference was observed with regard to signal-to-noise and contrast-to-noise ratios except for the pancreatic duct. No significant difference in acquisition times between PACE and RESP techniques was observed. Conclusion:We confirmed the superiority of the image quality of the PACE technique compared to conventional RESP technique for free-breathing 3D MRCP in healthy volunteers.

Breath-held MR Cholangiopancreatography (MRCP) using a 3D Dixon fat–water separated balanced steady state free precession sequence

“…However, in patients with irregular or shallow respiratory rhythms, respiratory-gated acquisitions may fail to trigger correctly, prolonging scan times, or may result in images with substantial motion artifact. Several modifications of the standard respiratory-gated 3D FSE MRCP pulse sequence have been proposed, including parallel imaging [7], navigator triggering in place of respiratory triggering [8], navigator gating with prospective acquisition correction (PACE) [9,10], sampling perfection with application optimized contrasts using different flip angle evolutions (SPACE) [11–14], and respiratory compensation using a reference respiration model [15]. These techniques have all resulted in improved image quality and reduced artifact in small series; however, they are not all widely available, and have not succeeded in eliminating motion artifact in all patients.…”

Papel da ranitidina como meio de aprimorar a qualidade do exame de colangiopancreatografia por ressonância magnética

“…This may have compromised image quality in 3D acquisitions; on the other hand, considering that some patients are sensitive to scopolamine, avoiding the utilization of such type of drug increases the tolerance to the procedure. Finally, the new respiratory-triggered techniques by means of diaphragmatic motion monitoring (PACE) (27) seem to be superior to that utilized for the present study. This may have favored the 2D sequences in the present study, i.e., adopting more updated RT techniques might have improved the quality of the images obtained in 3D and make them better than those obtained with the breath-hold technique.…”

ECG-gated imaging of a mouse heart using a 40-MHz annular array

“…Although not described here, we also implemented software-based respiratory gating in order to eliminate axial respiratory-motion artifacts. Our implementation of respiratory gating is analogous to navigatortriggered-prospective-acquisition-correction techniques in clinical MRI [11] where respiratory motion is tracked without the need to add another layer of hardware.…”