Gradient nonlinearity correction in liver DWI using motion-compensated diffusion encoding waveforms

McTavish, Sean; Van, Anh T.; Peeters, Johannes M.; Weiss, Kilian; Makowski, Marcus R.; Braren, Rickmer; Karampinos, Dimitrios C.

doi:10.1007/s10334-021-00981-6

Cited by 11 publications

(19 citation statements)

References 36 publications

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“…One specific diffusion encoding may stand out in this respect: flow-compensated (FloCo) diffusion encoding [ 15 – 20 ]. It suppresses the effect of signal decays induced by ballistic motion [ 15 – 18 , 21 ] at the price of an increased minimally achievable echo time (TE) and a longer repetition time (TR).…”

Section: Introductionmentioning

confidence: 99%

Flow-compensated diffusion encoding in MRI for improved liver metastasis detection

et al. 2022

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Magnetic resonance (MR) diffusion-weighted imaging (DWI) is often used to detect focal liver lesions (FLLs), though DWI image quality can be limited in the left liver lobe owing to the pulsatile motion of the nearby heart. Flow-compensated (FloCo) diffusion encoding has been shown to reduce this pulsation artifact. The purpose of this prospective study was to intra-individually compare DWI of the liver acquired with conventional monopolar and FloCo diffusion encoding for assessing metastatic FLLs in non-cirrhotic patients. Forty patients with known or suspected multiple metastatic FLLs were included and measured at 1.5 T field strength with a conventional (monopolar) and a FloCo diffusion encoding EPI sequence (single refocused; b-values, 50 and 800 s/mm2). Two board-certified radiologists analyzed the DWI images independently. They issued Likert-scale ratings (1 = worst, 5 = best) for pulsation artifact severity and counted the difference of lesions visible at b = 800 s/mm² separately for small and large FLLs (i.e., < 1 cm or > 1 cm) and separately for left and right liver lobe. Differences between the two diffusion encodings were assessed with the Wilcoxon signed-rank test. Both readers found a reduction in pulsation artifact in the liver with FloCo encoding (p < 0.001 for both liver lobes). More small lesions were detected with FloCo diffusion encoding in both liver lobes (left lobe: six and seven additional lesions by readers 1 and 2, respectively; right lobe: five and seven additional lesions for readers 1 and 2, respectively). Both readers found one additional large lesion in the left liver lobe. Thus, flow-compensated diffusion encoding appears more effective than monopolar diffusion encoding for the detection of liver metastases.

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Section: Introductionmentioning

confidence: 99%

Flow-compensated diffusion encoding in MRI for improved liver metastasis detection

et al. 2022

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“…FloCo diffusion encodings rephase spins that move at a constant velocity so that they do not experience an erroneous dephasing and therefore, do not cause an undesired signal drop. [17][18][19][20][21][22] Indeed, FloCo diffusion encodings have been shown to strongly mitigate the severeness of the cardiac pulsation artifact. 7 With the rise of ever stronger gradient systems and optimized implementations, [23][24][25] the drawback of a reduced b-value efficiency 26 of FloCo diffusion encodings becomes negligible if one wants to maintain the echo times currently used in liver DWI.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reduction of the cardiac pulsation artifact and improvement of lesion conspicuity in flow‐compensated diffusion images in the liver—A quantitative evaluation of postprocessing algorithms

Führes

Saake

Lorenz

et al. 2022

Magnetic Resonance in Med

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Purpose To enhance image quality of flow‐compensated diffusion‐weighted liver MRI data by increasing the lesion conspicuity and reducing the cardiac pulsation artifact using postprocessing algorithms. Methods Diffusion‐weighted image data of 40 patients with liver lesions had been acquired at 1.5 T. These data were postprocessed with 5 different algorithms (weighted averaging, p‐mean, percentile, outlier exclusion, and exception set). Four image properties of the postprocessed data were evaluated for optimizing the algorithm parameters. These properties were the lesion to tissue contrast‐to‐noise ratio (CNR), the reduction of the cardiac pulsation artifact, the data consistency, and the vessel darkness. They were combined into a total quality score (Qtotal,$$ {Q}_{\mathrm{total}}, $$ set to 1 for the trace‐weighted reference image), which was used to rate the image quality objectively. Results The weighted averaging algorithm performed best according to the total quality score (Qtotal=1.111±0.067$$ {Q}_{\mathrm{total}}=1.111\pm 0.067 $$). The further ranking was outlier exclusion algorithm (Qtotal=1.086±0.061$$ {Q}_{\mathrm{total}}=1.086\pm 0.061 $$), p‐mean algorithm (Qtotal=1.045±0.049$$ {Q}_{\mathrm{total}}=1.045\pm 0.049 $$), percentile algorithm (Qtotal=1.012±0.049$$ {Q}_{\mathrm{total}}=1.012\pm 0.049 $$), and exception set algorithm (Qtotal=0.957±0.027$$ {Q}_{\mathrm{total}}=0.957\pm 0.027 $$). All optimized algorithms except for the exception set algorithm corrected the pulsation artifact and increased the lesion CNR. Changes in Qtotal$$ {Q}_{\mathrm{total}} $$ were significant for all optimized algorithms except for the percentile algorithm. Liver ADC was significantly reduced (except for the exception set algorithm), particularly in the left lobe. Conclusion Postprocessing algorithms should be used for flow‐compensated liver DWI. The proposed weighted averaging algorithm seems to be suited best to increase the image quality of artifact‐corrupted flow‐compensated diffusion‐weighted liver data.

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“…The sym-vc waveform is not optimal in terms of TE as there is a deadtime between the excitation and refocusing pulses that is not used for diffusion encoding when an EPI readout is used. Several different motion compensated diffusion encoding waveforms that use an asymmetric design for TE optimization have been proposed [28,29,[33][34][35][36][37][38][39][41][42][43][44]. A formulation was recently introduced for the on-the-scanner computation of a near TE-optimal motion-compensated diffusion waveform with concomitant field correction, labeled as the asymmetric velocity compensated diffusion encoding waveform (asym-vc), which allows for flexibility in DWI protocol optimization [35].…”

Section: Introductionmentioning

confidence: 99%

“…Motion‐compensated diffusion encoding gradient waveforms have recently been proposed as alternatives to overcome the effects of motion in DWI of other organs such as the heart [28–32], the liver [27,28,33–39], and the pancreas [40]. A symmetric bipolar velocity compensated waveform (sym‐vc) can be designed such that the gradient first moment (

{m}_1=\gamma \int tG(t) dt

) is equal to zero, meaning that spins which move with a constant velocity accumulate no extra phase and therefore no signal is lost.…”

Section: Introductionmentioning

confidence: 99%

Motion compensated renal diffusion weighted imaging

McTavish

Van

Peeters

et al. 2022

Magnetic Resonance in Med

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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.

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Gradient nonlinearity correction in liver DWI using motion-compensated diffusion encoding waveforms

Cited by 11 publications

References 36 publications

Flow-compensated diffusion encoding in MRI for improved liver metastasis detection

Flow-compensated diffusion encoding in MRI for improved liver metastasis detection

Reduction of the cardiac pulsation artifact and improvement of lesion conspicuity in flow‐compensated diffusion images in the liver—A quantitative evaluation of postprocessing algorithms

Motion compensated renal diffusion weighted imaging

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