Motion compensated renal diffusion weighted imaging

Abstract

To assess the effect of respiratory motion and cardiac driven pulsation in renal DWI and to examine asymmetrical velocity-compensated diffusion encoding waveforms for robust ADC mapping in the kidneys. Methods: The standard monopolar Stejskal-Tanner pulsed gradient spin echo (pgse) and the asymmetric bipolar velocity-compensated (asym-vc) diffusion encoding waveforms were used for coronal renal DWI at 3T. The robustness of the ADC quantification in the kidneys was tested with the aforementioned waveforms in respiratory-triggered and breath-held cardiac-triggered scans at different trigger delays in 10 healthy subjects. Results: The pgse waveform showed higher ADC values in the right kidney at short trigger delays in comparison to longer trigger delays in the respiratory triggered scans when the diffusion gradient was applied in the feet-head (FH) direction. The coefficient of variation over all respiratory trigger delays, averaged over all subjects was 0.15 for the pgse waveform in the right kidney when diffusion was measured in the FH direction; the corresponding coefficient of variation for the asym-vc waveform was 0.06. The effect of cardiac driven pulsation was found to be small in comparison to the effect of respiratory motion. Conclusion: Short trigger delays in respiratory-triggered scans can cause higher ADC values in comparison to longer trigger delays in renal DWI, especially in the right kidney when diffusion is measured in the FH direction. The asym-vc waveform can reduce ADC variation due to respiratory motion in respiratory-triggered scans at the cost of reduced SNR compared to the pgse waveform.

Motion‐induced phase‐corrected homodyne reconstruction for partial Fourier single‐shot diffusion‐weighted echo planar imaging of the liver

“…The proposed mpc‐hdyne method has been presently studied in pF DWI of the liver. However, similar benefits from using the proposed homodyne method would also be expected in other DWI applications where nonlinear motion‐induced phase errors introduce k‐space dispersion and pF encoding is of interest, including pancreas, 45 kidney, 46 and potentially heart DWI 47 …”

“…Third, this study did not explore motion-compensated diffusion-encoding waveforms, which can mitigate motion-induced phase and consequently pF artifacts. [37][38][39][40][41]46,53,54 Fourth, the present work did not provide a thorough analysis of an optimal pF factor that should be used in liver DWI to optimize image quality. A larger validation study with patient data using the proposed methodology should be employed to study the robustness of pF for liver ss-DW-EPI in clinical routines.…”

Distortionless, free‐breathing, and respiratory resolved 3D diffusion weighted imaging of the abdomen

“…M1‐nulled diffusion gradients reduce the resolution of the imparted spatially varying phase, and vastly improves phase navigator estimation since the signal energy remains closer to the center of k‐space. The benefits of M1‐nulled diffusion encoding has been shown for cardiac triggering in the heart 19 and pancreas, 20 respiratory triggering in renal imaging, 21 and free‐breathing, 22 and breath‐holding in the liver 23 . The twice refocused preparation that satisfies the Carr‐ Purcell‐ Meiboom‐ Gill (CPMG) condition has reduced B1 sensitivity compared to single refocusing schemes, 24 and little echo time penalty compared to single refocused M1‐nulled waveforms.…”

Robust multishot diffusion‐weighted imaging of the abdomen with region‐based shot rejection

“…The spleen moves relatively little during respiration, and will have fewer cycles of imparted phase from diffusion gradients compared to the pancreas, which is susceptible to cardiac motion. 6 velocity-or acceleration-compensated diffusion encoding [28][29][30][31][32][33] reduces the resolution of the imparted phase for a modest TE penalty. The imparted phase also depends on the method used for managing respiratory motion.…”