Minimizing the postoperative biliary complications in living donor liver transplantation,by utility of preoperative non-enhanced magnetic resonance cholangiopancreatography

Aim of the work

The aim of this study was to assess the utility of non-enhanced MRCP in reduction of biliary complications in LDLT donors and compare the results with IOC.

Intra-arterial magnetic resonance angiography of the iliac arteries: clinical experience using two different protocols

Purpose: To assess the feasibility of intra-arterial magnetic resonance angiography (iaMRA) with two different protocols.

Material and Methods: Twenty patients were prospectively examined after digital subtraction angiography. Contrast-enhanced iaMRA was performed using a 1.5T magnetic resonance imaging (MRI) system. Contrast agent (gadodiamide) was injected through a conventional angiography catheter placed in the abdominal aorta. The patients were randomized into two groups each comprising 10 patients. Group 1 was examined with a FLASH-3D (fast low-angle shot) sequence, allowing the center of the k-space to be acquired 0.5 s after initiation of the measurement. Group 2 was examined with the identical sequence, but the center of the k-space was acquired after 8.7 s. The increase in the intravascular signal intensity was determined and the diagnostic value of the angiograms was independently scored by 4 investigators using a 5-point scale.

Results: Nineteen of 20 MRAs were scored as diagnostic; only 1 was scored as non-diagnostic by 2 observers. The diagnostic value of the angiograms of group 2 was judged superior to that of group 1 owing to a more homogeneous intravascular contrast distribution.

Conclusion: Intra-arterial MRA is feasible. The diagnostic value of angiograms using a flash sequence with center of the k-space acquisition after 8.7 s ranged from good to excellent. This sequence is appropriate for iaMRA of iliac arteries to support MR guided intervention.     

Postoperative imaging of living donor liver transplantation complications

Background

There is no doubt that the role of Different diagnostic imaging is well established in the evaluation of patients who are being evaluated for potential liver transplantation but it plays a huge role in the success of transplanted liver operations. Technical advances in imaging equipment and techniques allow more accurate assessment of postoperative living donor transplantation complications.

MRI一站式综合扫描对活体肝移植的应用价值

 目的 研究MRI一站式综合扫描对活体肝移植的应用价值.方法 选择活体肝移植的患者及供体各20名.进行MRI扫描,包括3.0T磁共振采用常规血管四期增强扫描.磁共振平扫采用flash序列及TSE序列扫描.血管增强后选择与平扫相同的T,vibe压脂序列进行扫描.依据个体需要,在注射后40-120 min之间进行延迟扫描.以手术所见为参考标准,比较MRI平扫与一站式MRI综合扫描(MRI平扫+MRCP+血管增强+肝实质增强+延迟)对病灶检出的敏感度,评估其诊断价值.结果 MRI平扫对供体/受体血管变异、胆道变异和癌变的检出敏感性分别为40.0%、72.22%、75.0%.而一站式MRI扫描对病灶检出的敏感性都为100.0%,两种方法对后两种病变的敏感性比较差异有统计学意义(P<0.05).结论 在活体肝移植中一站式MRI综合扫描检查具有重要价值.     

Quantitative assessment of ventricular function using three-dimensional SSFP magnetic resonance angiography

PURPOSE: To evaluate three-dimensional (3D), free-breathing, steady-state free precession (SSFP) magnetic resonance angiography (MRA) for volumetric assessment of ventricular function. MATERIALS AND METHODS: In 18 subjects (mean age = 21.5 years) 3D datasets of the heart and great vessels were acquired using an ECG-triggered, free-breathing SSFP technique with a T2-preparation prepulse. Data were acquired during end-systole (ES) and end-diastole (ED) for assessment of stroke volumes (SVs). Through-plane flow measurements of the great arteries were performed as well as 2D-cine SSFP imaging for comparison. For image analysis of the 3D SSFP datasets a simplex mesh model was used. Papillary muscles were excluded from ventricular volumes using thresholds. Intra- and interobserver variability (Bland-Altman analysis) and correlations (Pearson's coefficient) between volumetric and flow measurements were assessed. RESULTS: ES and ED datasets were acquired successfully in all subjects. The best correlation was observed between flow vs. 3D SSFP SV for the LV (r = 0.85, mean difference = -1.0 mL) and the RV (r = 0.89, mean difference = -2.2 mL) with high intra- (LV: r = 0.93; RV: r = 0.94) and interobserver (LV: r = 0.91; RV: r = 0.93) reproducibility. CONCLUSION: 3D SSFP datasets combined with semiautomatic segmentation algorithms allow highly accurate and reproducible assessment of left (LV) and right ventricular (RV) SVs in free-breathing subjects.     

High-resolution steady-state free precession coronary magnetic resonance angiography within a breath-hold: parallel imaging with extended cardiac data acquisition.

Coronary artery imaging data are conventionally acquired in a single imaging frame during mid-diastole. The data acquisition window must be sufficiently short to avoid cardiac motion artifacts. A short data acquisition window results in decreased imaging efficiency and limited spatial resolution. Parallel imaging may lessen these limitations, but requires highly accurate coil sensitivity. The purpose of this work was to increase the imaging efficiency and spatial resolution in coronary artery imaging using parallel imaging with an extended acquisition window. External coil calibration data were acquired before and after a short mid-diastolic period of accelerated imaging data acquisition. It was assumed that residual cardiac motion in the extended acquisition window would not impede accurate estimation of coil sensitivity since only low spatial frequency signals were acquired for coil calibration. Experimental studies were performed in five healthy volunteers at 3 T using steady-state free precession sequence. Statistical comparison was made between the proposed method and conventional data acquisition for visual quality of image and vessel sharpness. The proposed technique demonstrated higher visual grading and improved vessel sharpness. The proposed method is a new approach to enhance the imaging efficiency and spatial resolution in coronary artery imaging.     

The value of magnetic resonance cholangiography in the preoperative assessment of living liver donors

ObjectiveThe purpose of this study was to investigate the ability of magnetic resonance cholangiography (MRC) in the depiction of biliary anatomy of living liver donors by using intraoperative cholangiography (IOC) as a gold standard.Materials and MethodsBetween 2004 and 2006, 86 potential adult-to-adult living donor liver transplantation donors had preoperative MRC at our institution. Of these, 24 potential donors were excluded due to various clinical factors. A total of 62 of these individuals were selected for liver donation and included in the study. MRC was performed on a 1.5-T scanner with breath-hold, rapid acquisition with relaxation enhancement (RARE) sequence with half-Fourier acquisition (HASTE; Siemens) and free-breathing, three-dimensional turbo spin-echo sequence with respiratory triggering. Thin- and thick-slab imaging techniques were employed with half-Fourier RARE MRC. IOC was performed in all 63 cases. The images of IOC and MRC were classified according to a modified Huang classification, independently. The results of the MRC were then compared with the IOC results.ResultsIOC was used as the reference standard; a total of 43 (69.3%) liver donors were considered to have normal biliary anatomy, whereas 19 (30.7%) were considered to have variants of biliary anatomy. Compared with IOC, MRC correctly revealed biliary anatomy in 59 of 62 (95.1%) donors. The sensitivity, specificity, positive predictive value and negative predictive value of MRC in distinguishing normal and any type of variant biliary anatomy were 84.2%, 100%, 100%, and 93.4%, respectively.ConclusionMRC is an effective imaging technique for the preoperative evaluation of the biliary anatomy in living liver donors. However, MRC and IOC should be considered complementary to one another in order to avoid complications.     

Inaccurate preoperative imaging assessment on biliary anatomy not increases biliary complications after living donor liver transplantation

Backgrounds and aims

Accurate assessment of graft bile duct is important to plan surgical procedure. Magnetic resonance cholangiopancreatography (MRCP) has become an important diagnostic procedure in evaluation of pancreaticobiliary ductal abnormalities and has been reported as highly accurate. We aim to estimate the efficacy of preoperative MRCP on depicting biliary anatomy in living donor liver transplantation (LDLT), and to determine whether inaccurate preoperative imaging assessment would increase the biliary complications after LDLT.

Methods

The data of 118 cases LDLT were recorded. Information from preoperative MRCP was assessed using intraoperative cholangiography (IOC) as the gold standard. The possible risk factors of recipient biliary complications were analyzed.

Results

Of 118 donors, 84 had normal anatomy (type A) and 34 had anatomic variants (19 cases of type B, 9 cases of type C, 1 case of type E, 2 cases of type F and 3 cases of type I) confirmed by IOC. MRCP correctly predicted all 84 normal cases and 17 of 34 variant cases, and showed an accuracy of 85.6% (101/118). The incidence of biliary complications was comparable between cases with accurate and inaccurate classification of biliary tree from MRCP, and between cases with normal and variant anatomy of bile duct. While cases with graft duct opening ≤5 mm showed a significant higher incidence of total biliary complications (21.1% vs. 6.6%, P = 0.028) and biliary stricture (10.5% vs. 1.6%, P = 0.041) compared with cases with large duct opening >5 mm.

Conclusion

MRCP could correctly predict normal but not variant biliary anatomy. Inaccurate assessment of biliary anatomy from MRCP not increases the rate of biliary complications, while small-sized graft duct may cause an increase in biliary complications particularly biliary stricture after LDLT.     

Non-contrast enhanced magnetic resonance angiography techniques in candidates for kidney transplantation: A comparative study

AimDetailed knowledge of vessel status in potential candidates for kidney transplantation is essential for the surgeon. Contrast enhanced magnetic resonance angiography has previously been used intensively for assessing this, but the discovery that use of gadolinium based contrast agents in magnetic resonance imaging can cause Nephrogenic Systemic Fibrosis in patients suffering from severe kidney disease has lead to renewed interest in non-contrast enhanced magnetic resonance angiography. The aim of this study was to find a non-contrast enhanced magnetic resonance angiography method for preoperative evaluation of the pelvic vessels prior to kidney transplantation, providing a sufficient image quality.MethodIn a prospective study we consecutively included 54 patients undergoing examinations prior to kidney transplantation. The patients were examined with the following magnetic resonance angiography sequences: A 2D Time of flight (n = 54), 3D Time of flight (n = 52) patients, 3D Phase Contrast (n = 54), 3D Balanced Steady State Free Precession (n = 52) and a 2D TRiggered Angiography Non-Contrast Enhanced (TRANCE) (a Spin Echo sequence with subtraction) (n = 48). The sequences were evaluated with respect to contrast, diagnostic performance and artefact burden.ResultsEvaluating contrast, 3D Phase Contrast was significantly better than 2D Time of flight (p < 0.001). The 2D Time of flight was significantly superior to 3D Time of flight, 3D Balanced-Turbo Steady State Free Precession and the TRANCE sequences (p < 0.001). Rating diagnostic performance, the 3D Phase Contrast ranked better than the 2D Time of flight though no significant difference was found (p > 0.2). The 2D Time of flight was significantly better than the other sequences (p < 0.001) in all cases. The artefact score was lowest for the Phase Contrast images and significantly superior to the 2D Time of flight (p < 0.005). The 2D Time of flight was significantly better than the three other sequences (p < 0.001) in all cases.ConclusionNon-contrast enhanced magnetic resonance angiography offers a safe preoperative examination for assessment of vessel status before kidney transplantation. A combination of 2D Time of flight and 3D Phase Contrast acquisitions is recommended and can be performed within a reasonable scan time.     

Non-contrast-enhanced magnetic resonance venography using magnetization-prepared rapid gradient-echo (MPRAGE) in the preoperative evaluation of living liver donor candidates: Comparison with conventional computed tomography venography

ObjectiveTo compare the diagnostic performance of non-contrast-enhanced magnetic resonance venography using magnetization-prepared rapid gradient-echo (MPRAGE-MRV) and conventional computed tomography venography (CTV) in preoperative evaluation of venous tributaries for living donor liver transplantation.Materials and methodsInstitutional review board approval and written informed consent were obtained for this prospective study of 73 donor candidates. Of these, 23 underwent right-sided graft hepatectomy without middle hepatic vein. One or more tributaries, other than the right hepatic vein, were reconstructed for 20 of the 23 grafts. For these 20 grafts, the number and location of the tributaries requiring reconstruction were evaluated based on venography, and diagnostic performance was analyzed using surgical records as a reference standard. For each candidate, the number of small tributaries directly joining the inferior vena cava was counted in each venographic image; a paired-sample t-test was used to assess differences. The severity of respiratory artifacts in MPRAGE-MRV was qualitatively evaluated, and compared using Wilcoxon's rank-sum test.ResultsAll reconstructed venous tributaries were prospectively identified using both methods. MPRAGE-MRV tended to provide a greater number of small tributaries than conventional CTV (mean: 2; 95% CI: [1.66, 2.34], and 1.74; [1.44, 2.04], respectively), although the difference was not significant (P = 0.10); MPRAGE-MRV was superior or equal to CTV in 52 subjects (71.2%), and inferior in 21 subjects (28.8%). Respiratory artifacts were significantly less severe in the former subjects (P < 0.0001).ConclusionsMPRAGE-MRV has the potential to replace conventional CTV in the preoperative evaluation of living liver donor candidates.     

Magnetic resonance imaging of the elbow

With the current popularity of racket and throwing sports, the number of individuals seeking medical care for elbow pain and dysfunction has increased. Elbow dysfunction may be related to acute or chronic injury to the soft tissue or osseous components of the elbow. With magnetic resonance imaging (MRI), it is now possible to accurately determine the nature and extent of the pathological changes in ligaments, tendons, muscles, and osseous structures of the elbow joint. This information facilitates the choice of the appropriate therapeutic regimen.     

Laser Doppler velocimetry (LDV) and 3D phase-contrast magnetic resonance angiography (PC-MRA) velocity measurements: validation in an anatomically accurate cerebral artery aneurysm model with steady flow

PURPOSE: To verify the accuracy of velocity mapping with three-dimensional (3D) phase-contrast magnetic resonance angiography (PC-MRA) for steady flow in a realistic model of a cerebral artery aneurysm at a 3T scanner. MATERIALS AND METHODS: Steady flow through an original geometry model of a cerebral aneurysm was mapped at characteristic positions by state-of-the-art laser Doppler velocimetry (LDV) as well as 3D PC-MRA at 3T. The spatial distributions and local values of two velocity components obtained with these two measurement methods were compared. RESULTS: The 3D PC-MRA velocity field distribution and mean velocity values exhibited only minor differences to compare to the LDV measurements in straight artery regions for both main and secondary velocities. The differences increased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the main flow direction. CONCLUSION: 3D PC-MRA can provide reliable measurements of velocity components of steady flow in small arteries. The accuracy of such measurements depends on the artery size and the measurement plane positioning.     

Morphological manifestations of nonpuerperal mastitis on magnetic resonance imaging

Purpose:

To investigate the morphological features of nonpuerperal mastitis on magnetic resonance imaging (MRI).

Materials and Methods:

MRI results of 27 patients diagnosed with nonpuerperal mastitis were retrospectively analyzed according to the Breast Imaging Reporting and Data System (BI‐RADS).

Results:

According to the enhanced MRI results, 22 cases presented as nonmass‐like enhancements and five cases presented as masses. For the 22 nonmass‐like enhancement lesions, one case showed as a homogeneous enhancement and 21 cases showed as heterogeneous enhancements. In the 21 heterogeneous enhancement cases, 13 contained lesions of rim‐like enhancement. With regard to the number of lesions with rim‐like enhancement, 11 presented as multiple and two as single. In the five mass lesions, three presented as rim enhancements. Indications of rim or rim‐like enhancement accounted for 59% (16/27) of all cases. For the 16 cases that presented with signs of rim or rim‐like enhancement, the central hypointensity area surrounded by enhanced rim or rim‐like entity showed as hyperintensity in 14 cases and hypointensity or heterointensity in two cases on T2‐weighted imaging.

Conclusion:

On contrast‐enhanced MRI, most nonpuerperal mastitis presented as nonmass‐like lesion with heterogeneous signal intensity. The observation of signs of rim or rim‐like enhancement on contrast‐enhanced MRI with central hypointensity areas showing as hyperintensity on T2‐weighted imaging is suggestive of the possibility of nonpuerperal mastitis. J. Magn. Reson. Imaging 2011;33:1369–1374. © 2011 Wiley‐Liss, Inc.     

Role of MRCP in assessment of biliary variants in living donor liver transplantation

Introduction

Liver transplantation can be done by three different methods: Cadaveric, heterotopic and living donor liver transplantation (LDLT). In LDLT usually the right lobe of a donor liver is transplanted into the patient after proper volumetric studies. The native patient bile ducts are connected to the biliary tree of the transplanted liver segment.

Patients and methods

From January 2010 to August 2011, 50 potential LDLT donors were evaluated with preoperative MRCP.

Results

The radiologist evaluated the visualization of the common duct, right and left intra-hepatic ducts, and insertion of the right posterior lobe duct. The data were classified according to Huang and Hakki classifications. According to the more detailed classification of Hakki 13 patients (26%) were Type K1; 15 patients (30%) were Type K2a; three patients (6%) were Type K2b; 11 patients (22%) Type K3a; four patients (8%) were Type K3b; two patients (4%) were Type K4 and no patients were Type K5. Two patients with unclassified anatomical biliary pattern were encountered. In conclusion, this study has shown an extremely high accuracy of MRCP in preoperative assessment of live hepatic donors, which aided in the style and procedure of the operation and ultimately to a high success rate of the transplantation procedures.     

Apparent diffusion coefficient measurements with diffusion-weighted magnetic resonance imaging for evaluation of hepatic fibrosis

PURPOSE: To evaluate the use of apparent diffusion coefficient (ADC) measurements based on diffusion-weighted MRI (DWI) to assess stage of liver disease. MATERIALS AND METHODS: A total of 31 patients who underwent both a liver biopsy and DWI and 132 patients who only underwent DWI were enrolled. Biopsy specimens were scored for fibrosis and necroinflammation according to the Knodell histology activity index (HAI). The 31 patients consisted of 21 patients with chronic hepatitis and 10 with cirrhosis (Child-Pugh stage A in nine and stage B in one), and the 132 patients consisted of 56 patients with cirrhosis (Child-Pugh stage A in 41, stage B in 10, and stage C in five), 42 with chronic hepatitis, and 34 with normal liver function. The ADCs in the liver parenchyma were measured using DWI with relatively low b factors (b = 0.01 and 128.01 seconds/mm(2)) and were compared among the HAI scores and among patients with cirrhosis, chronic hepatitis, and normal liver function. RESULTS: The ADCs decreased as the fibrosis score in the HAI increased, and the correlation was statistically significant (P < 0.0001). No relationship between the ADCs and the necroinflammation scores in the HAI was found. The ADCs decreased as the stage of liver disease progressed or as the Child-Pugh stage progressed, and these relationships were statistically significant (P < 0.0001). CONCLUSION: ADC measurements are potentially useful for the evaluation of fibrosis staging in the liver.     

Evaluation of the keyhole technique applied to the proton resonance frequency method for magnetic resonance temperature imaging

Purpose:

To evaluate the temporal and spatial resolution of magnetic resonance (MR) temperature imaging when using the proton resonance frequency (PRF) method combined with the keyhole technique.

Materials and Methods:

Tissue‐mimicking phantom and swine muscle tissue were microwave‐heated by a coaxial slot antenna. For the sake of MR hardware safety, MR images were sequentially acquired after heating the subjects using a spoiled gradient (SPGR) pulse sequence. Reference raw (k‐space) data were collected before heating the subjects. Keyhole temperature images were reconstructed from full k‐space data synthesized by combining the peripheral phase‐encoding part of the reference raw data and the center phase‐encoding keyhole part of the time sequential raw data. Each keyhole image was analyzed with thermal error, and the signal‐to‐noise ratio (SNR) was compared with the self‐reference (nonkeyhole) images according to the number of keyhole phase‐encoding (keyhole‐data size) portions.

Results:

In applied keyhole temperature images, smaller keyhole‐data sizes led to more temperature error increases, but the SNR did not decreased comparably. Additionally, keyhole images with a keyhole‐data size of <16 had significantly different temperatures compared with fully phase‐encoded self‐reference images (P < 0.05).

Conclusion:

The keyhole technique combined with the PRF method improves temporal resolution and SNR in the measurement of the temperature in the deeper parts of body in real time. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Computed tomography and magnetic resonance imaging findings in cerebral hydatid disease

Purpose: The purpose of this study was to describe the discriminative computed tomography (CT) and magnetic resonance imaging (MRI) features of cerebral hydatid disease.Methods: The CT and MRI findings of four cases of surgically proven cerebral hydatid cysts were retrospectively reviewed. Results: CT demonstrated well-defined cystic lesions with no perilesional oedema and no contrast enhancement in all cases except one recurrent disease that showed both peripheral oedema and rim enhancement. MR images revealed well-defined cystic lesions with a quite clear rim that showed relative hypointensity limited to some aspects of the cyst walls on T2-weighted images. The cysts were spherical and obvious mass effect was observed on both CT and MR examinations. Conclusions: Although the cystic nature of intracranial hydatid disease could be equally well demonstrated on CT and MR examinations, CT is superior in detecting calcification of the cyst wall or septa, when present, and MR is better in demonstrating cyst capsule, detecting multiplicity and defining the anatomic relationship of the lesion with the adjacent structures and helps in surgical planning.     

Pictorial review: magnetic resonance imaging of colonic diverticulitis

Magnetic resonance imaging (MRI) is rapidly emerging as a useful imaging modality for the evaluation of the gastrointestinal tract. Increasingly rapid sequences and improving hardware have significantly improved the visualisation of diseases of the colon. MRI has a major advantage over CT in that there is no ionising radiation. In our institution, MRI has increasingly been used as a complimentary imaging modality to CT in the diagnosis and evaluation of diverticulitis and its complications. In this review article, we illustrate the emerging role of MRI in the diagnosis and evaluation of colonic diverticulitis.     

Preoperative evaluation of patients awaiting liver transplantation: comparison of multiphasic contrast-enhanced 3D magnetic resonance to helical computed tomography examinations

PURPOSE: To determine the feasibility of using a multiphasic magnetic resonance (MR) examination to evaluate the hepatic arterial anatomy and parenchyma in patients awaiting orthotopic liver transplantation (OLT). MATERIALS AND METHODS: Twenty consecutive patients awaiting OLT underwent multiphasic MR (using a T1-weighted 3D gadolinium-enhanced gradient-echo (GRE) sequence and two separate injections of contrast material) and computed tomography (CT) imaging; both imaging studies were performed within a 1-week period for each patient. Quantitative and qualitative assessment of the hepatic arterial system on MR data was performed. Two independent observers classified the hepatic arterial anatomy and evaluated the hepatic parenchyma from the MR data. The prospective CT interpretation was used as the gold standard. RESULTS: Overall qualitative rating of hepatic arterial system-to-background contrast on MR data was good to excellent (average pooled score of 2.00 +/- 0.27), with no significant difference between the two observers after the first or second injections of contrast material. Classification of hepatic arterial anatomy by MR angiography (MRA) and CT angiography (CTA) was concordant in 85% (17/20) of patients and discordant in 15% (3/20) of patients. Focal parenchymal lesions were detected in 25% (5/20) of patients by MR and CT; however, two lesions in one patient with multiple lesions were detected only with MR. CONCLUSION: Multiphasic T1-weighted 3D gadolinium-enhanced MR examination can provide comprehensive evaluation of the hepatic arterial anatomy and parenchyma in patients awaiting OLT. MR may offer an advantage over CT in the detection of focal parenchymal lesions.