| Part 1 The feasibility study of FSD SPACE in evaluating iliac vein compressionObjective: To explore the feasibility of magnetic resonance venography(FSD SPACE)in iliac vein imaging and measurement by comparing the subjective score of image quality and the diameter and stenosis rate of objective measurement of iliac vein compression between magnetic resonance imaging sequence FSD SPACE and lower limb direct CTV.Materials and methods: 88 Patients with chronic venous disease and highly suspected iliac vein compression syndrome in cardiovascular surgery of our hospital from April 2019 to October 2020 were scanned with Siemens superconducting magnetic resonance Magnetom Prisma 3.0T within 2 days before or after direct CTV of lower extremities.The sequence includes True-fisp,FSD SPACE and SPACE FLOW.The image quality of FSD-SPACE and CTV was subjectively scored with four-point method by two senior attending doctors in our hospital.The consistency of image quality score between the two radiologists was evaluated by kappa test.The subjective score differences between the two groups were compared.Two physicians measured the shortest diameter of the maximum compression of the common iliac vein(point A),the shortest diameter of the contralateral common iliac vein(point B),the shortest diameter of the distal common iliac vein(point C)and the shortest diameter of the contralateral common iliac vein(point D).The stenosis rate was calculated according to(1-the shortest diameter of the maximum compression of the common iliac vein / the shortest diameter of the contralateral common iliac vein)× 100%.The diameters of the four points and the stenosis rate measured by FSD SPACE and CTV were compared,and the Bland-Altman diagram was used to evaluate the consistency of the two methods in measuring the stenosis rate.Results: 85 patients were enrolled in the group finally.The subjective scores of the two physicians were consistent in CTV image quality(Kappa value: 0.65),and in FSD SPACE image quality(Kappa value: 0.78).The quality of CTV image was higher than that of FSD SPACE image.There was significant difference between them(P < 0.05),but the score of FSD SPACE image was 3 or more,which can meet the needs of clinical diagnosis.The diameters of point A,B,C and D measured by FSD SPACE were significantly different from those in group CTV.The diameter of 4 points in FSD SPACE group was lower than that in CTV group.The diameter of point A:(5.82 ± 2.62)mm vs(6.79 ± 3.08)mm,P < 0.05;point B:(10.32 ± 2.49)mm vs(12.21 ± 2.83)mm,P < 0.05;point C:(10.17 ± 2.34)mm vs(11.97 ± 2.68)mm,P < 0.05;point D:(11.00 ± 2.14)mm vs(12.82 ± 2.74)mm,P < 0.05.However,there was no significant difference in the stenosis rate between FSD SPACE and CTV.The stenosis rate was(46.91 ±21.72)% vs(46.49 ±22.48)%,P = 0.72.There is a good agreement between CTV and FSD SPACE in measuring the degree of iliac vein stenosis by Bland-Altman.Conclusion: Non-contrast enhanced magnetic resonance venography(FSD SPACE)has the advantage of no ionizing radiation and no contrast agent,it can clearly show the compression of iliac vein,and is consistent with CTV in evaluating the degree of iliac vein stenosis.It provides data and anatomical reference for clinical diagnosis of IVCS.Part 2 Clinical factors related to IVCS and the application of FSD SPACE in the diagnosis of IVCSObjective: To explore the related clinical factors of IVCS and the diagnostic efficiency of FSD SPACE in IVCS.Materials and methods: The patients with chronic venous disease and highly suspected iliac vein compression syndrome in cardiovascular surgery of our hospital from April 2019 to October 2020 were collected.The general clinical data and clinical CEAP grade were recorded.Non-contrast enhanced magnetic resonance imaging was performed within 2 days before DSA.The scanning sequence included True-fisp,FSD SPACE and SPACE FLOW.The patients were divided into IVCS group and non-IVCS group according to the gold standard of DSA.The general data of the two groups were compared,including male / female ratio,age,height,weight,BMI index,smoking history,drinking history,diabetes mellitus and hypertension.The correlation between CEAP grade and IVCS is explored by using chi-square test.The shortest diameter of the maximum compression of iliac vein(point A),the shortest diameter of the contralateral iliac vein at the same plane(point B),the shortest diameter of the distal common iliac vein(point C),the shortest diameter of the contralateral common iliac vein(point D)and the anteroposterior diameter of iliac artery at the same plane of iliac vein(point E)were measured.The stenosis rate was calculated,and the diameter and stenosis rate were compared between the two groups.The formation of DVT in iliac vein was observed on FSD SPACE images.FSD SPACE sequence combined with SPACE FLOW was used to observe the formation of collateral vessels in the pelvis.ROC curve was used to compare the value of stenosis rate combined with collateral vessels and stenosis rate alone in the diagnosis of IVCS.The diagnostic efficacy of non-contrast enhanced magnetic resonance angiography in the diagnosis of IVCS(sensitivity,specificity,positive predictive value,negative predictive value and coincidence rate)is evaluated.Results: There were 83 patients who met the inclusion criteria.62 cases of IVCS and 21 cases of non-IVCS were diagnosed by DSA.There was no significant difference in age,height,weight,BMI index,smoking history,drinking history,diabetes mellitus and hypertension history between IVCS group and non-IVCS group,P > 0.05.There was no significant correlation between the occurrence of IVCS and clinical CEAP grade,P=0.68.The diameters of 5 points in the two groups were compared,and there was a significant difference in the diameters of point A and point C,the diameter of point A:(4.91 ± 2.38)mm vs(7.91 ± 1.84)mm,P < 0.05;point C:(9.96 ± 1.89)mm vs(11.54 ± 2.22)mm,P < 0.05.There was no significant difference in the diameters of points B,D and E between the two groups.The diameter of point B:(10.13 ±2.29)mm vs(10.99 ±2.38)mm,P=0.15;point D:(10.88 ± 2.02))mm vs(11.67 ± 2.18)mm,P=0.13;point E:(8.01 ± 1.48)mm vs(8.81 ± 1.87)mm,P=0.09.There was significant difference in the stenosis rate between the two groups,the stenosis rate was(54.27 ± 21.10)% vs(32.26 ± 10.42)%,P < 0.05.DVT formation in iliac vein was found in 3 of the 62 IVCS patients during DSA examination,and DVT was also found in the same patient during FSD SPACE examination.It was found that the area under the curve of the stenosis rate(≥ 50%)combined with collateral vessels in diagnosing IVCS was larger than that of the stenosis rate(≥ 50%)alone by using the ROC curve,and the AUC values were 0.90 and 0.78 respectively.Collateral angiogenesis can be used as an indirect sign for the diagnosis of IVCS.According to the rate of iliac vein stenosis ≥ 50% combined with collateral angiogenesis or any one of them used as an index for the diagnosis of IVCS,the sensitivity,specificity,positive predictive value,negative predictive value and coincidence rate of diagnosing IVCS in non-contrast enhanced magnetic resonance venography examination were 85.5%,95.24%,98.15%,69.97% and 87.95%.Conclusion: FSD SPACE technique can clearly show the compression of iliac vein and it has high diagnostic efficiency in IVCS,especially combined with collateral vessels.There was no correlation between IVCS and clinical factors such as sex,age,body weight and CEAP.Non-enhanced magnetic resonance venography provides imaging basis for clinical diagnosis and has irreplaceable advantages over other examinations.It is worth popularizing in clinic. |
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