Likert scales for the black blood state evaluation.

Likert scales for the black blood state evaluation.</p

Trace-weighted images at b = 50 s/mm².

Each column shows the same slice, same slices as in Fig 2. Bright blood signals are depicted by white arrows.</p

ADC values in the left and right liver lobe, averaged over all slices.

Error bars represent the standard deviation among all slices and volunteers. Brackets indicate significant differences.</p

Representative segmentations for signal calculation in the left and right liver lobe.

Representative segmentations for signal calculation in the left and right liver lobe.</p

Used diffusion encodings.

Note the slight difference in the duration of the single trapezoidal gradient pulses in row 3 to 5, which is necessary to achieve the different values of M1 and M2 weightings.</p

Sequence parameters.

PurposeThe study aims to develop easy-to-implement concomitant field-compensated gradient waveforms with varying velocity-weighting (M1) and acceleration-weighting (M2) levels and to evaluate their efficacy in correcting signal dropouts and preserving the black-blood state in liver diffusion-weighted imaging. Additionally, we seek to determine an optimal degree of compensation that minimizes signal dropouts while maintaining blood signal suppression.MethodsNumerically optimized gradient waveforms were adapted using a novel method that allows for the simultaneous tuning of M1- and M2-weighting by changing only one timing variable. Seven healthy volunteers underwent diffusion-weighted magnetic resonance imaging (DWI) with five diffusion encoding schemes (monopolar, velocity-compensated (M1 = 0), acceleration-compensated (M1 = M2 = 0), 84%-M1–M2-compensated, 67%-M1–M2-compensated) at b-values of 50 and 800 s/mm2 at a constant echo time of 70 ms. Signal dropout correction and apparent diffusion coefficients (ADCs) were quantified using regions of interest in the left and right liver lobe. The blood appearance was evaluated using two five-point Likert scales.ResultsSignal dropout was more pronounced in the left lobe (19%-42% less signal than in the right lobe with monopolar scheme) and best corrected by acceleration-compensation (8%-10% less signal than in the right lobe). The black-blood state was best with monopolar encodings and decreased significantly (p M1–M2-compensated encoding schemes could restore the black-blood state again. Strongest ADC bias occurred for monopolar encodings (difference between left/right lobe of 0.41 μm2/ms for monopolar vs. 2/ms for the other encodings).ConclusionAll of the diffusion encodings used in this study demonstrated suitability for routine DWI application. The results indicate that a perfect value for the level of M1–M2-compensation does not exist. However, among the examined encodings, the 84%-M1–M2-compensated encodings provided a suitable tradeoff.</div

ADC maps of one volunteer.

PurposeThe study aims to develop easy-to-implement concomitant field-compensated gradient waveforms with varying velocity-weighting (M1) and acceleration-weighting (M2) levels and to evaluate their efficacy in correcting signal dropouts and preserving the black-blood state in liver diffusion-weighted imaging. Additionally, we seek to determine an optimal degree of compensation that minimizes signal dropouts while maintaining blood signal suppression.MethodsNumerically optimized gradient waveforms were adapted using a novel method that allows for the simultaneous tuning of M1- and M2-weighting by changing only one timing variable. Seven healthy volunteers underwent diffusion-weighted magnetic resonance imaging (DWI) with five diffusion encoding schemes (monopolar, velocity-compensated (M1 = 0), acceleration-compensated (M1 = M2 = 0), 84%-M1–M2-compensated, 67%-M1–M2-compensated) at b-values of 50 and 800 s/mm2 at a constant echo time of 70 ms. Signal dropout correction and apparent diffusion coefficients (ADCs) were quantified using regions of interest in the left and right liver lobe. The blood appearance was evaluated using two five-point Likert scales.ResultsSignal dropout was more pronounced in the left lobe (19%-42% less signal than in the right lobe with monopolar scheme) and best corrected by acceleration-compensation (8%-10% less signal than in the right lobe). The black-blood state was best with monopolar encodings and decreased significantly (p M1–M2-compensated encoding schemes could restore the black-blood state again. Strongest ADC bias occurred for monopolar encodings (difference between left/right lobe of 0.41 μm2/ms for monopolar vs. 2/ms for the other encodings).ConclusionAll of the diffusion encodings used in this study demonstrated suitability for routine DWI application. The results indicate that a perfect value for the level of M1–M2-compensation does not exist. However, among the examined encodings, the 84%-M1–M2-compensated encodings provided a suitable tradeoff.</div

Examples for the evaluated properties “vessel visibility” and “bright blood signal”.

Examples for the evaluated properties “vessel visibility” and “bright blood signal”.</p

Fig 6 -

Signals (top) Mean signals in the left and right liver lobe for b = 50 and b = 800 s/mm2, normalized to the monopolar signal at b = 50 s/mm2 in the right lobe and averaged over all slices. The error bars represent the standard deviation of the averaged signals among slices and volunteers. (bottom) Ratio of the signal in the left and right liver lobe. Brackets indicate significant differences.</p

Averaged Likert scores for the blood appearance evaluation.

Averaged Likert scores for the blood appearance evaluation.</p