Optimal MR cholangiography in evaluation of hilar branching anatomy of living adult liver donors

Abstract

[한글]연구목적: 이 연구의 목적은 생체 부분 간이식 공여자의 술전 담문계 해부학적 변이 진단에 위해, Gd-BOPTA 조영증강 자기공명담관 조영술 (Gd-BOPTA MRC)과 T2 강조 삼차원 자기공명담관조영술(volumetric T2-MRC)의 임상적 유용성을 검증하고, 생체부분 간이식에 특화된 적정 자기공명영상기법을 정립하기 위해서이다.연구대상 및 방법:Part1: 확장되지 않은 담도 조영에 관한 Mn-DPDP자기공명담관조영술 (Mn-DPDP MRC)과 Gd-BOPTA MRC 비교: 88 간이식 후보자들이 조영증강 MRC를 시행 받았다 (Mn-DPDP MRC: n=36 과 Gd-BOPTA MRC: n=52). 질적 평가를 위해 두명의 영상의학과 의사가 MR영상을 판독하였으며 총담관, 우담관, 좌담관, 그리고 이차분지 별로 4점 척도로 점수를 기록하였다. 또한 양적 평가를 위해 Contrast to Noise비를 간실질과 총담관에서 측정하였다.Part2: 생체 부분 간이식 공여자의 술전 담문계 해부학적 변이 진단을 위한 Gd-BOPTA MRC의 임상적 적용: 우간엽 절제술을 시행받은 11명의 공여자를 대상으로 한명의 영상의학과 의사와 한명의 외과의사가 모든 MR영상을 판독하였고 그소견을 수술 소견과 수술 담도조영술과 비교하였다. 또한 두명의 다른 영상의학과 의사가 두가지 영상 조합 (기존의 T2-single section single shot RARE sequence (conventional T2-MRC)와 기존의 검사에 Gd-BOPTA MRC를 같이 판독)을 후향적으로 분석하였으며 각각의 해석에서 간문계 해부학적 변이와 그 진단신뢰도를 기록하였다.Part 3: 담도계 조영에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: 본 연구는 33명의 생체부분 간이식을 위해 우간엽 절제술을 시행받은 공여자를 대상으로 하였으며 모든 공여자는 세종류의 자기공명담도조영술을 시행받았다 (conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC). 세명의 영상의학과 의사가 각각의 검사에서 담도관의 visualization score와 artifact의 정도를 기록하였다.Part 4: 우간엽 절제시 얻어지는 담관구의 수 예측에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: Part 3와 동일한 환자군을 대상으로 세명의 영상의학과 의사가 비조합형 영상 (conventional T2-MRC)과 조합형 영상 (conventional T2-MRC 와 volumetric T2-MRC, conventional T2-MRC와 Gd-BOPTA MRC, 그리고 모든 검사의 조합)을 판독하였고, 각각의 영상에서 예상되는 담관구의 수와 진단 신뢰도를 기록하였다. 예상되는 담관구의 수는 수술소견과 비교하였으며 또한 각 영상의 평균 정확도와 그 신뢰도를 비교하였다.연구결과:Part 1: 확장되지 않은 담도 조영에 관한 Mn-PDP자기공명담관조영술 (Mn-DPDP MRC)과 Gd-BOPTA MRC 비교: Mn-DPDP MRC와 Gd-BOPTA MRC는 총담관에서 통계학적으로 차이없는 visualization score를 보였다 (p = .380, Mann-Whitney U test). 또한 branching duct에서는 Gd-BOPTA MRC가 Mn-DPDP MRC에 비해 유의하게 높은 점수를 보였다 (우담관: p = 0.016, 좌담관: p = 0.014, 우측 이차분지: p = 0.006, 좌측 2차 분지, p = 0.003). 양적분석에서도, Gd-BOPTA MRC 총담관/ 간실질의 CNR (38.90±24.50) 이 Mn-DPDP MRC의 CNR(24.14±17.98)보다 유의하게 높았다(p = .003, Student’s t test).Part 2: 생체 부분 간이식 공여자의 술전 담문계 해부학적 변이 진단을 위한 Gd-BOPTA MRC의 임상적 적용: 전향적 분석에서 두 공여자에서 담도계 병이를 확인하였고 이는 수술 소견과 일치하였으며 후향적 분석에서는 조합영상의 진단신뢰도가 conventional T2-MRC보다 유의하게 높았다 (p < 0.05).Part 3: 담도계 조영에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: 전체 담도의 평균 visualization score 는 conventional T2-MRC 와 volumetric T2-MRC가 Gd-BOPTA MRC보단 유의하게 높은 점수를 보였으며 의 conventional T2-MRC 와 volumetric T2-MRC비교에 있어서는 volumetric T2-MRC가 유의하게 높았다. 한편 Gd-BOPTA MRC는 다른 두검사기법에 비해 유의하게 적은 artifact를 보였다.Part 4: 우간엽 절제시 얻어지는 담관구의 수 예측에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: 조합영상간의 담관구의 수 예측에 있어 정확도와 진단신뢰도는 유의한 차이는 없었으나, 모든 조합형 검사는 conventional T2-MRC만을 시행한 경우보다는 높은 정확도와 진단신뢰도를 보였다.결론:Part 1: 확장되지 않은 담도 조영에 관한 Mn-PDP자기공명담관조영술 (Mn-DPDP MRC)과 Gd-BOPTA MRC 비교: Gd-BOPTA MRC는 담도 조영을 위한 기존의 Mn-DPDP MRC를 대체할 수 있다.Part 2: 생체 부분 간이식 공여자의 술전 담문계 해부학적 변이 진단을 위한 Gd-BOPTA MRC의 임상적 적용: Gd-BOPTA를 이용한 자기공명 영상은 간공여 후보자의 술전 진단에 있어서 혈관과 담관의 해부학을 같이 파악할 수 있는 포괄적 영상 기법이다.Part 3: 담도계 조영에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: volumetric T2-MRC는 담도계 조영에서 가장 높은 visualization score를 보이고 반면 Gd-BOPTA MRC는 가장 적은 artifact를 보인다.Part 4: 우간엽 절제시 얻어지는 담관구의 수 예측에 있어서 conventional T2-MRC, volumetric T2-MRC그리고 Gd-BOPTA MRC의 비교 분석: 기존의 conventional T2-MRC와 다른 두 영상기법의 조합은 생체부분간이식을 위한 공여자의 담도계 해부학의 술전 검사에서 적정 자기공명 영상기법으로 여겨 진다.

[영문]PURPOSE: The purpose of our study was to evaluate the clinical feasiblility of recently developed Gd-BOPTA enhanced MR cholangiography and T2 weighted three dimensional volumetric RARE sequence for hilar branching ductal anatomy evaluation of donor candidates for living-related liver transplantation and assess systematically the optimal cholangiography with the aim of developing a tailored approach for preoperative donor evaluation.MATERIALS AND METHODS:Part 1. Comparison of the efficacy of Mangafodipir trisodium (Mn-DPDP)-enhanced MR cholangiography and Gadobenate dimeglumine (Gd-BOPTA)-enhanced MR cholangiography in visualizing a non-dilated biliary system: Eighty-eight healthy liver donor candidates underwent contrast-enhanced T1-weighted MRC. Mn-DPDP and Gd-BOPTA was used in 36 and 52 patients, respectively. Two radiologists reviewed the MR images and rated the visualization of the common duct, the right and left hepatic ducts, and the second-order branches using a 4-point scale. The contrast-to-noise ratio (CNR) of the common duct to the liver in the two groups was also compared.Part 2. Clinical application of Gd-BOPTA-enhanced MR cholangiography in preoperative evaluation of hilar branching anatomy for living donor-related liver transplantation: Eleven right hepatic lobe donors underwent MRI examinations using T2-weighted MR cholangiography (MRC) and Gd-BOPTA-enhanced MR cholangiography. One radiologist and one surgeon prospectively reviewed all the images for biliary abnormalities and compared them with the surgical findings and intraoperative cholangiograms. In addition, two blinded reviewers evaluated the two sets of MRC (T2-weighted MRC set and T2-weighted MRC plus CE-T1-weighted MRC set) retrospectively and recorded the anatomic types of the hilar biliary branching pattern along with their confidence in the interpretation.Part 3. Biliary Tract Depiction: Comparison of T2 weighted single section single shot RARE sequence, T2 weighted volumetric RARE sequence, and Gd-BOPTA enhanced MR cholangiography: Between April 2003 and July 2006, 33 consecutive healthy candidates underwent right lobectomy for the living adult–to-adult right-lobe liver transplantation. All candidates underwent three kinds of MR cholangiography (T2 weighted single section single shot RARE sequence, T2 weighted volumetric RARE sequence, and Gd-BOPTA enhanced MR cholangiography). Three radiologists recorded the visualization score of biliary ducts and the degree of artifacts in each modality. Tests for significant differences in mean visualization scores of the biliary tracts of three examinations were performed using analysis of variance (ANOVA). The least significant difference test was used for multiple post hoc comparisons. The same statistical process was applied for the comparison of degree of artifacts in the three examinations.Part 4. Prediction of the number of orifices during harvesting right lobe with combination T2 weighted single section single shot RARE sequence, T2 weighted volumetric RARE sequence, and Gd-BOPTA enhanced MR cholangiography: Three radiologists independently reviewed the uncombined set (T2 weighted single section single shot RARE sequence) and the three kinds of combined sets (combined set of T2 weighted single section single shot RARE sequence and T2 weighted volumetric RARE sequence, combined set of T2 weighted single section single shot RARE sequence and Gd-BOPTA enhanced MR cholangiography, combined set of all three examinations) in random order. They recorded the predicted number of ductal orifices during right lobe harvesting and the diagnostic confidences on each imaging set. The MRI definitions of the predicted number of ductal orifices during right lobe harvesting were compared with the surgical findings and operative cholangiography. The Mean accuracies and mean confidences of three reviewers about predicting the number of orifices were compared between four imaging sets using least significant difference test.RESULTS:Part 1: Mn-DPDP MRC and Gd-BOPTA MRC both showed similar visualization grades in the common duct (p = .380, Mann-Whitney U test). In the case of the proximal bile ducts, the median visualization grade was significantly higher with Gd-BOPTA MRC than with Mn-DPDP MRC (right hepatic duct: p = 0.016, left hepatic duct: p = 0.014, right secondary order branches: p = 0.006, left secondary order branches, p = 0.003). The common duct-to-liver CNR of the Gd-BOPTA MRC group was significantly higher (38.90±24.50) than that of the Mn-DPDP MRC group (24.14±17.98) (p = .003, Student’s t test).Part 2: Prospective analysis detected the biliary variants in two patients. All the MRI findings on the biliary anatomy were corroborated intraoperatively. Retrospective analysis showed that the mean diagnostic confidence in the combined set was significantly higher than that of the T2-weighted MRC alone by both reviewers (p < 0.05).Part 3: Mean visualization scores of common duct, branching ducts and overall ducts were significantly different on the basis of ANOVA test (common duct, p=0.0045; branching duct, p<0.0001 and overall ducts, p<0.0001). Mean visualization scores of branching ducts and overall ducts both for T2 weighted single section single shot RARE sequence and T2 weighted volumetric RARE sequence demonstrated significant higher results in comparison with Gd-BOPTA enhanced MR cholangiography. Mean visualization score of T2 weighted volumetric RARE sequence for overall duct and common duct was significantly higher with that of T2 weighted single section single shot RARE sequence.Part 4: Mean accuracies of predicting the number of orifices in the four sets of imaging modalities were significantly different on the basis of ANOVA test (p=0.0029). No significant difference was observed within the comparison of the combined sets (modality 2, 3, and 4) (p>0.05). In comparison between three combined sets and T2 weighted single section single shot RARE sequence, all combined sets showed significant higher accuracy than T2 weighted single section single shot RARE sequence (p<0.05). Mean confidences of the four modalities were significantly different on the basis of ANOVA test (p<0.0001). No significant difference was observed within the comparison of combined sets (modality 2, 3, and 4) (p>0.05). ). In comparison between the combined sets and T2 weighted single section single shot RARE sequence, all combined sets showed significant higher confidence than T2 weighted single section single shot RARE sequence (p<0.05) .CONCLUSION:Part 1: Gd-BOPTA, as a biliary contrast agent, may be a potential substitute for Mn-DPDP.Part 2: Obtaining both MRA and CE-T1-weighted MRC is feasible using a single dose of gadobenate dimeglumine. Therefore, gadobenate dimeglumine–enhanced MRI might play a role as a preoperative imaging technique for the vascular and biliary evaluation of potential living donors.Part 3: T2 weighted volumetric RARE sequence demonstrated significantly the highest mean visualization score for overall biliary ducts. However, Gd-BOPTA enhanced MR cholangiography showed significantly the lowest degree of artifacts.Part 4: The combined sets of all three examinations may be an excessive and the combined sets of two modalities (modality 2: T2 weighted single section single shot RARE sequence and T2 weighted volumetric RARE sequence, and modality 3: T2 weighted single section single shot RARE sequence and Gd-BOPTA enhanced MR cholangiography) may be optimal choices for preoperative evaluation of hilar branching anatomy of living adult liver donors.