Study On The Effect Of Injection And Scanning Protocols On The Image Quality Of Arterial Phase In MR-enhanced Of Liver With Gadoxetate Disodium

PurposeTo compare slow injection method and dilution method and four scanning protocols:dual AP images,triple AP images,quintuple AP images and single AP image,and evaluate which method has more late AP and less respiratory motion artifacts in optimal AP in the enhanced magnetic resonance imaging(MRI)of liver with gadoxetate disodium.Materials and methodsA total of 682 patients who underwent a magnetic resonance examination of liver in a continuous period from January 2017 to November 2018 were included in this study and divided into 5 subcohorts.Some failed examinations which cannot be diagnosed are excluded,and the patient needs to be re-examined.If the arterial phases captured by the technician based on experience,this kind of examination would be excluded.Our research is divided into two parts.First,in the case of different injection protocols,there were 145 patients at an injection rate of 1 ml/s,which was a slow injection subcohort,and 111 patients were injected at the rate of 2 ml/s as a dilution subcohort after the contrast agent was diluted to 50%.Scanning protocols were the same(dual AP).Second,according to different scanning protocols of the AP,patients were divided into 4 subcohorts when the same injection protocols(the contrast agent was diluted 50%,injection rate was 2ml/s)were used.Generalized auto calibration partially parallel acquisition(GRAPPA)with volumetric interpolated breath-hold examination(VIBE)was used in the subcohort of dual AP(n=111)and single AP(n=130).The combination of Controlled aliasing in parallel imaging results in higher acceleration(CAIPIRINHA)with time-resolved imaging with interleaved stochastic trajectories(TWIST)and VIBE,known as a prototype CDT-VIBE was used in the subcohort of triple AP(n=150)and quintuple AP(n=146).For the analysis of patient characteristics,t test,one-way analysis of variance(ANOVA)and?~2 test were used.To compare multiple AP with single AP,optimal AP mean artifact score rated by two observers using a five-point scale and frequency of transient severe motions(TSM)were evaluated.Frequency of acquisition of late AP was also assessed.Wilcoxon Mann-Whitney test was used to compare the optimal AP mean artifact score.?~2 test was used for the frequency of acquisition of late AP and incidence of TSM.ResultsIn the case of the contrast application protocols was different,there were less respiratory motion artifacts(1.62±0.87 vs 1.97±1.12,P=0.014)in optimal AP and lower TSM incidence[8.3%(12/145)vs 18%(20/111),P=0.02]in the slow injection subcohort than in the dilution subcohort.In the slow injection subcohort and the dilution subcohort,there was no significant difference in the frequency of acquisition of late AP[91%(132/145)vs 94.6%(105/111),P=0.282]or the mean artifact of AP1(1.26±0.57vs1.41±0.68,P=0.086)or AP2(1.91±1.00vs2.25±1.25,P=0.052)between the two subcohorts.In the case of the contrast application protocols was same(the contrast agent was diluted to 50%,injection rate was 2ml/s),GRAPPA-VIBE was used in both the subcohorts of dual AP and single AP,there was a significant difference in the frequency of acquisition of late AP[94.6%.(105/111)vs 86.9%(113/130)],optimal AP mean artifact scores(1.97±1.12 vs 1.52±0.76)and TSM incidence[18%(20/111)vs 1.5%(2/130)](P=0.043,0.003,<0.001).Both the subcohorts of triple AP and quintuple AP used CDT-VIBE,there was no significant difference in the optimal AP mean artifact scores(2.32±1.05 vs 2.09±0.94,P=0.64),but there were less late AP[91.3%(137/150)vs 97.3%(142/146)]and higher TSM incidence[30.7%(46/150)vs19.9%(29/146)]in the subcohort of triple AP than in quintuple AP.We further compared the subcohort of dual AP and quintuple AP in the frequency of acquisition of late AP(94.6%vs 97.3%),the optimal AP mean artifact scores(1.97±1.12 vs 2.09±0.94),and the incidence of TSM(18%vs 19.9%).There was no significant difference in all of these three aspects(P=0.442,0.98,0.709,respectively).ConclusionOur research shows that dual AP images with slow injection method have the best image quality.If the technician can capture the late arterial phase accurately,the single AP images will have the best image quality.