Objective To investigate the value of magnetic resonance imaging-proton density fat fraction(MRI-PDFF)in evaluating hepatic steatosis in patients with chronic hepatitis B virus(HBV)infection.Methods The patients,aged>16 years,who visited the outpatient service or were hospitalized in Beijing Tsinghua Changgung Hospital from January 2018 to December 2022 and were diagnosed with chronic HBV infection were enrolled,and all patients underwent MRI examination of the liver in our hospital.The patients were divided into groups based on the presence or absence of liver cirrhosis,and the consistency in PDFF between different hepatic segments was compared between groups.The Kappa consistency test and intraclass correlation coefficient(ICC)were used for consistency analysis.Results A total of 76 patients treated with nucleoside analogues were enrolled,among whom 23(30.26％)had liver cirrhosis.For all patients,the simple arithmetic average of PDFF fluctuated between 1.49％and 30.93％.According to MRI-PDFF≥5％as the diagnostic criterion for fatty liver disease,there were 29 patients(38.16％)with fatty liver disease among all patients.For all 76 patients,the simple arithmetic average of PDFF was lower than the weighted average of PDFF for the whole liver,and there was no significant difference between the simple arithmetic average of PDFF,the weighted average of PDFF,and the PDFF values of the left and right lobes of the liver(F=0.39,P=0.76).The consistency test showed that the PDFF values of each hepatic segment and the left and right lobes of the liver had strong consistency with the weighted average and simple arithmetic average of PDFF,with an ICC of>0.75,but the consistency between the PDFF value of the right lobe and the weighted average of PDFF was higher than that between the PDFF value of the left lobe and the weighted average of PDFF.In the consistency test of differentiating fatty liver disease in patients with liver cirrhosis,there was poor consistency between the PDFF value of segment Ⅶ and the weighted average of PDFF(Kappa=0.39),with moderate consistency for the left lobe and the Ⅰ,Ⅱ,Ⅲ,Ⅴ,Ⅵ,and Ⅷ segments.For the patients with liver cirrhosis,the lowest consistency was observed between the PDFF value of Ⅶ segment and the weighted average of PDFF for the whole liver,and the highest consistency was observed between the PDFF value of Ⅵ segment and the weighted average of PDFF for the whole liver.For the patients without liver cirrhosis,the lowest consistency was observed between the PDFF value of Ⅱ segment and the weighted average of PDFF for the whole liver,and the highest consistency was observed between the PDFF value of Ⅴ segment and the weighted average of PDFF for the whole liver.Conclusion MRI-PDFF is more comprehensive in evaluating hepatic steatosis in patients with chronic HBV infection,and for the patients with liver cirrhosis,there is poor consistency between the PDFF value of each segment and the weighted average of PDFF.

Objective To compare the value of standard coronal MRI and multi-planar reconstruction(MPR)images for evaluation of anterolateral ligament(ALL).Methods Data of 130 patients who underwent knee joint MR examination were retrospectively analyzed,including standard coronal MRI and MPR images.ALL were identified on standard coronal MRI and MPR images and classified as fully visible,partially visible or invisible.The visibility of bilateral ALL on both standard coronal MRI and MPR images were compared,while Kappa test was used to evaluate the consistency on both kinds of images.Results Among 130 cases,on standard coronal MRI and MPR images,the left ALL was fully visible in 83 and 93 cases,partially visible in 21 and 12 cases but invisible cases in 26 and 25 cases,respectively,while the right side ALL was fully visible in 66 and 80 cases,partially visible cases in 29 and 15 cases but invisible cases each in 35 cases,respectively.Significant difference of visibility of bilateral ALL were found between standard coronal MRI and MPR images(both P＜0.05),both with excellent consistency(both Kappa＞0.80).Conclusion MPR could display bilateral ALL better than standard coronal MRI.If the scanning conditions for MPR could not be met,standard coronal MRI might be used to evaluate ALL rather accurately.

Objective To explore the prognostic value of neuroimaging score in patients with acute vertebrobasilar artery occlusion(VBAO)with successful revascularization.Methods A total of 83 patients with acute VBAO who underwent endovascular treatment with successful recanalization,modified thrombolysis for cerebral infarction grade 2b or 3 were retrospectively selected.Based on baseline diffusion weighted imaging(DWI)sequences,posterior circulation infarcts were assessed using the novel posterior circulation score(N-PCS),brainstem score(BSS),and posterior circulation Alberta stroke program early CT score(pc-ASPECTS).A 90 d modified Rankin scale(mRS)score ≤2 points was defined as functional independence.The predictive value of the three scores was assessed by the receiver operating characteristic(ROC)curve analysis.Results The N-PCS[median(interquartile range):2(1-2)vs 4(2-5)]was statistically significant between the functional independent group(50 cases)and the poor group(33 cases)(P＜0.001).Multifactorial logistic regression analysis showed that age[adjusted odds ratio(OR)1.08;95％confidence interval(CI)1.02-1.14;P=0.006],baseline National Institutes of Health Stroke Scale(NIHSS)(adjusted OR 1.12;95％CI 1.03-1.20;P=0.005),and N-PCS(adjusted OR 2.84;95％CI 1.30-6.19;P=0.009)were independent prognostic factors for a favorable prognosis.Conclusion The N-PCS based on DWI can predict the prognosis of acute VBAO patients with successful revascularization.

Objective:To study the value of imaging features of extrapancreatic nerve plexus in predicting early postoperative recurrence of ductal adenocarcinoma of pancreatic head.Methods:The clinical, imaging and pathological data of patients with ductal adenocarcinoma of pancreatic head undergoing pancreati-coduodenectomy at the Hepatobiliary Pancreatic Center of Beijing Tsinghua Changgung Hospital, Tsinghua University from January 2014 to April 2022 were retrospectively analyzed. A total of 73 patients were included, including 51 males and 22 females, aged (66.1±9.0) years old. The patients were followed up by telephone or outpatient review, who were divided into two groups according to the recurrence within 6 months after surgery: the recurrence group ( n=26) and the non-recurrence group ( n=47). Streaks or soft-tissue densities in the distribution area of extrapancreatic nerve plexus, difference in CT values between the portal and arterial phases of the distribution area of extrapancreatic nerve plexus, maximum tumor diameter, and regional lymph node enlargement were compared between the two groups. Results:The incidences of streaks or soft-tissue densities showing in the distribution area of extrapancreatic nerve plexus were 80.8%(21/26) in the recurrence group and 51.1%(24/47) in the non-recurrence group, respectively. A CT value difference ≥15 HU between the portal and arterial phases of the distribution area of extrapancreatic nerve plexus occurred in 50.0%(13/26) patients of the recurrence group and 25.5%(27/47) of the non-recurrence group, respectively. Maximum tumor diameter ≥25 mm were found in 80.8% (21/26) patients of the recurrence group and 57.4% (27/47) of the non-recurrence group, respectively. ≥3 reginal lymph node enlargement showed in 65.4% (17/26) patients of the recurrence group and 31.9% (15/47) of the non-recurrence group, respectively (all P<0.05). The risk of early postoperative recurrence increased in patients with a CT value difference ≥15 HU between the portal and arterial phases of the distribution area of extrapancreatic nerve plexus ( OR=3.609, 95% CI: 1.099-11.855), and regional lymph node enlargement ≥ 3 ( OR=4.665, 95% CI: 1.400-15.545) (all P<0.05). And these two independent risk factors were combined to predict early postoperative recurrence of ductal adenocarcinoma of pancreatic head with an area under receiver operating characteristic curve of 0.748, sensitivity of 92.3%, and specificity of 48.9% ( P<0.001). Conclusion:≥ 15 HU CT value difference between the portal and arterial phases of the distribution area of extrapancreatic nerve plexus and ≥ 3 regional lymph node enlargement are independent risk factors for the early postoperative recurrence of pancreatic head ductal adenocarcinoma, which could provide more predictive information preoperatively.

Objective:To investigate the feasibility and clinical value of 4D flow magnetic resonance imaging (MRI) in evaluating hemodynamics of ischemic stroke patients with intracranial artery stenosis.Methods:Ischemic stroke patients with unilateral middle cerebral artery stenosis admitted from March 2017 to June 2018 in Beijing Tsinghua Changgung Hospital Stroke Center were prospectively enrolled. Time of flight magnetic resonance angiography was used to evaluate vascular stenosis, 4D flow MRI was used to measure net forward flow at the proximal of stenosis, and brain tissue perfusion was acquired simultaneously to validate flow.Results:A total of 33 patients with symptomatic middle cerebral artery stenosis were included [mean age: 56 years; male: 63.6% ( n=21)]. The flow rates among patients with stenosis of <30%, 30%-49%, 50%-69% and ≥70% were (3.56±1.08), (2.96±0.94), (3.72±0.60) and (2.50±1.03) ml/s individually, demonstrating a decreased flow in subjects with severe (≥70%) stenosis ( F=4.34, P=0.008). Further analysis about forward flow and brain tissue perfusion showed that the significant negative correlation between absolute flow rate or relative flow rate and relative time to peak could only be established in subjects with poor collateral (collateral score: 0-2), with r=-0.76 and -0.61 individually, both P<0.05. Conclusion:4D flow MRI could be used as a quantitative flow assessment in subjects with intracranial artery stenosis, and its association with distal brain tissue perfusion depends on collateral status.

Objective:To evaluate the metal artifacts reduction effect of multi-acquisition variable-resonance image combination (MAVRIC-SL) after total knee arthroplasty by comparing with two-dimensional fast spin-echo metal artifact reduction sequence (2D FSE MARS).Methods:A total of 78 patients (101 knees) who underwent total knee arthroplasty in Beijing Tsinghua Changgung Hospital from December 2018 to December 2020 were prospectively collected. All patients underwent 3.0 T MR examination within 2 weeks after surgery. The sequences included axial, sagittal, and coronal 2D FSE MARS and MAVRIC-SL. The ranges of prosthesis artifacts were measured, and the scores of the prosthesis clarity, anatomical structure clarity, and joint effusion diagnosis confidence were evaluated by Likert scale. Paired t test was used to compare the difference of artifact range between 2D FSE MARS and MAVRIC-SL. The Wilcoxon signed rank-sum test was used to compare image quality scores and joint effusion diagnosis confidence scores. Results:In 101 knees, the ranges of prosthesis artifacts in axial, sagittal, and coronal 2D FSE MARS were (63.3±8.5), (60.0±7.4) and (62.1±8.7) cm 2, while those of MAVRIC-SL were (49.5±5.8), (44.1±6.6) and (46.1±7.5) cm 2. The differences were statistically significant ( t=20.021, 21.834, 25.472, all P<0.001). The subjective scores of femoral prosthesis clarity, tibial prosthesis clarity, and anatomical structure clarity of MAVRIC-SL were significantly higher than those of 2D FSE MARS (all P<0.001). Confidence scores of 2D FSE MARS and MAVRIC-SL for diagnosing joint effusion were 2 (1, 3) and 3 (2, 3), respectively, and the difference was statistically significant ( Z=6.549, P<0.001). Conclusion:Compared with 2D FSE MARS, MAVRIC-SL can further reduce the metal artifacts in total knee arthroplasty and improve the diagnostic confidence of joint effusion.

Objective To investigate the value of preoperative intravoxel incoherent motiondiffusion weighted imaging (IVIM-DWI) in predicting early recurrence of hepatocellular carcinoma (HCC)after curative hepatectomy.Methods The clinical data of 51 HCC patients who underwent curative hepatectomy at Beijing Tsinghua Changgung Hospital,Tsinghua University from December 2014 to March 2017 were retrospectively analyzed.The study included 45 males and 6 females,aged 56.4 ± 10.1.The patients were divided into the early-recurrence group (21 patients) and the non-recurrence group (30 patients) according to whether there was HCC recurrence within 1 year after curative hepatectomy.The parameters of the lesions were measured and calculated:the apparent diffusion coefficient (ADC) value,true diffusion coefficient (D) value,perfusion-related diffusion coefficient (D *) value and perfusion fraction (f) value.Receiver operating characteristic curves (ROC) were used to evaluate the prediction efficiency of the parameters.Results The ADC and D values of the early-recurrence group were significantly lower than the non-recurrence group.The differences were statistically significant (P ＜ 0.05).In predicting early recurrence of HCC after curative hepatectomy,the ADC values showed the area under ROC was 0.713 (95％ CI:0.572 ～0.855),the sensitivity was 0.857 and specificity was 0.567 when the optimal threshold value was 1.24 × 10-3mm2/s.The D values in predicting early recurrence demonstrated the area under ROC was 0.740 (95％ CI:0.602 ～ 0.877),the sensitivity was 0.905 and specificity was 0.600 when the optimal threshold value was 1.03 × 10-3 mm2/s.Conclusions The ADC and D values of IVIMDWI could provide evidence in predicting early recurrence of HCC after curative hepatectomy.The D values had a higher prediction efficiency.

Objective To investigate the value of gadobenate dimeglumine (Gd-BOPTA) enhanced MRI in evaluation of reserved liver function.Methods Totally 68 patients were included among 143 patients who underwent Gd-BOPTA en hanced MRI.The enhancement ratios of SNR and CNR of right lobe,left lobe and caudal lobe were calculated on the ima ges from liver acquisition with volume acceleration flex sequence (LAVA-Flex) of hepatobiliary phase.The average values of right and left lobes and of three lobes were calculated and compared.According to Child-TurcottePugh (CTP) classification,the patients were divided into Class A and Class B.Integrated model of end-stage liver disease (iMELD) was applied to divide the patients into iMELD≤30 and iMELD＞30.The differences of SNR and CNR enhanced ratios were com pared,and the relationship between enhancement ratios and iMELD scores was analyzed.Results There were no significant differences in the enhancement ratios of SNR and CNR among each lobe,the average of two or three lobes (all P＞0.05).The SNR and CNR enhancement ratios of Class A were higher than those of Class B (both P＜0.05).The SNR and CNR enhancement ratios of iMELD≤≤30 were higher than those of iMELD＞30 (both P＜0.05).The SNR and CNR enhancement ratios showed negative correlations with iMELD scores (SNR:r=0.29,P-0.02;CNR:r=-0.32,P=0.01).Conclusion The intracellular uptake of Gd-BOPTA decreases with impaired liver function.Measurement of the de gree of parenchymal enhancement of any lobe or the whole liver on the images of Gd-BOPTA enhancement MRI in the hepatobiliary phase might reflect the reserved liver function.

Objective To summarize MRI features of anterior cruciate ligament graft tear and to explore the differences of MRI findings between acute tear and chronic tear, and compare the diagnostic ability of MRI and clinical examinations for graft tear. Methods MR images of 43 patients (44 knees) with anterior cruciate ligament graft tear(40 complete tear, 4 partial tear)confirmed by secondary arthroscopy were retrospectively analyzed. There were 18 acute tear and 26 chronic tear. Primary and secondary signs reported with conventional anterior cruciate ligament tear were adopted to evaluate graft tear. The exact probability method was used to compare the prevalence difference between various direct and indirect signs and the χ2 test was used to compare the accuracy between MRI and physical examination. Results The primary signs in MR images of anterior cruciate ligament graft tear included graft discontinuity in 13 kness, graft thickening with edematous high signal intensity in 12 knees, decreased slope of graft fibers in 6 kness, graft disappearing in 5 knees, and distinct graft atrophy in 3 knees. The secondary signs included kissing bone contusion in 4 knees, posteriorcruciate ligament buckling in 3 knees, increased anterior tibial displacement in 2 knees, bone contusion of the lateral condyle of femur, and bone contusion of thetibia condyle in 1 knee, respectively. There were no significant differences regarding the proportion of each sign between acute and chronic graft tear. Accuracy of MRI, Lachman test, and anterior drawer test were 87.5%(35/40), 95.0%(38/40)and 95.0%(38/40), respectively, which were all significantly higher than that of pivot shift test(42.5%,17/40) with significant differences(χ2=17.80, P<0.0083). Conclusions MRI is sensitive for diagnosing anterior cruciate ligament graft tear, the primary signs is the main evidence for the diagnosis of ACL graft tear, but it is hard to distinguish acute and chronic graft tear based on MR findings. The diagnostic accuracy has no statistically significant differences among MRI, Lachman test, and anterior drawer test, but they are all higher than pivot shift test.

Objective To determine the value of MR in the diagnosis of the medial and lateral meniscal posterior root tears.Methods One hundred and twenty one patients underwent arthroscopy and MR of knee examinations were retrospectively reviewed,and all of them did not have the history of knee surgery before the MR examination.MR images were double-blinded,independently,retrospectively scored by radiology residency (doctor 1) and attending radiologist (doctor 2).The likelihood of the meniscus posterior root tear was scored on basis of arthroscopic findings constituted the gold standard.Sensitivity,specificity and accuracy of MR diagnosis of the lateral and medial meniscus posterior root tear by two physicians were calculated,and the consistency of diagnosis results by two physicians was evaluated using the Kappa statistics.Reasons leading to misdiagnosis or missed diagnosis were discussed.Results Thirty three of the 121 patients were diagnosed with meniscus posterior root tears by arthroscopy,including 14 cases of lateral tears and 19 cases of medial tears.The sensitivity,specificity and accuracy in the diagnosis of posterior lateral meniscus root tears (PLMRT) for doctor 1 were 71.4％ (10/14),82.2％ (88/107) and 81.0％ (98/121),respectively,and for doctor 2 were 71.4％ (10/14),86.0％ (92/107) and 84.3％ (102/121).The sensitivity,specificity and accuracy in the diagnosis of posterior medial meniscus root tears (PMMRT) for doctor 1 were 100.0％ (19/19),88.2％ (90/102) and 90.1％ (109/121),respectively,and for doctor 2 were 100.0％ (19/19),95.1％ (97/102) and 95.9％ (116/121),respectively.The Kappa statistics for PLMRT and PMMRT were 0.67 and 0.81,respectively,demonstrating a good interobserver agreement (P＜0.05).The misdiagnosed cases of the PMMRT were 12 for doctor 1 and 5 for doctor 2.There were 4 cases being commonly misdiagnosed by the two doctors,and there were no any missed cases in this study.For the PLMRT,the misdiagnosed cases were 19 for doctor 1 and 15 for doctor 2.Eleven cases were misdiagnosed and 4 were missed by the two physicians.Conclusion MR is a reliable diagnostic tool for detecting posterior root tears of the medial and lateral meniscus.