Magnetic resonance cholangiopancreatography image enhancement for automatic disease detection

AIM:To sufficiently improve magnetic resonance cholangiopancreatography(MRCP) quality to enable reliable computer-aided diagnosis(CAD).METHODS:A set of image enhancement strategies that included filters(i.e.Gaussian,median,Wiener and Perona-Malik),wavelets(i.e.contourlet,ridgelet and a non-orthogonal noise compensation implementation),graph-cut approaches using lazy-snapping and Phase Unwrapping MAxflow,and binary thresholding using a fixed threshold and dynamic thresholding via histogram analysis were implemented to overcome the adverse characteristics of MRCP images such as acquisition noise,artifacts,partial volume effect and large inter-and intra-patient image intensity variations,all of which pose problems in application development.Subjective evaluation of several popular pre-processing techniques was undertaken to improve the quality of the 2D MRCP images and enhance the detection of the significant biliary structures within them,with the purpose of biliary disease detection.RESULTS:The results varied as expected since each algorithm capitalized on different characteristics of the images.For denoising,the Perona-Malik and contourlet approaches were found to be the most suitable.In terms of extraction of the significant biliary structures and removal of background,the thresholding approaches performed well.The interactive scheme performed the best,especially by using the strengths of the graphcut algorithm enhanced by user-friendly lazy-snapping for foreground and background marker selection.CONCLUSION:Tests show promising results for some techniques,but not others,as viable image enhancement modules for automatic CAD systems for biliary and liver diseases.

Clinical significance of magnetic resonance cholangiopancreatography utilizing half-Fourier acquisition single-shot fast spin-echo in diagnosing bile duct diseases

Objective: To investigate the clinical significance of magnetic resonance cholangiopancreatography (MRCP) utilizing half-Fourier acquisition single-shot fast spin-echo (HASTE) in the diagnosis of bile duct diseases. Methods: Forty-three patients with obstructive jaundice and 4 without were enrolled in this study. The underlying diseases included bile duct calculi ( 13 cases) , chronic cholangitis ( 14 cases) malignant tumors (18 cases) and congenital biliary cysts (2 cases). All patients underwent examinations with magnetic resonance imaging (MRI) and MRCP, and 39 were also examined with B-type ultrasonography, 33 with CT and 25 with ERCP and PTC. Three-dimensional image reconstruction was performed using volume-rendered technique ( VRE) on the basis of the data obtained by MRCP. Results: The biliary calculi were displayed as circular filling defects in MRCP images, with the proximal end of dilated bile duct taking the form of the mouth of a cup. The bile duct of patients with chronic cholangitis showed distal end dilation and thinner proximal end without discontinuity. Interception of the bile ducts was most frequent (72. 2% ) in cases of malignant bile duct obstruction, in which the ducts may also be mastoid or resembling rat tails. 72. 2% of the cases had severe dilation of the bile ducts, which occur in only 16. 0% of the benign cases, with significant difference between them (P <0. 01) . In images of intrahepatic biliary cyst, intrahepatic duct dilated in the shape of a bursa in connection with the duct. By MRCP, 20 malignant obstructions of the bile ducts were identified with 2 misdiagnoses, and in 25 cases of benign obstructions identified by MRCP, only 1 misdiagnoses occurred. Thus MRCP had the sensitivity, specificity and accuracy of 90.0% , 96.3% and 93.6% respectively in discriminating benign and malignant diseases of the bile ducts, showing a total diagnostic accuracy of 94. 0% that was similar to that of ERCP (92.0% ) but significantly higher than those of both CT (75. 0% ) and B-type ultrasonic examination (74. 0% ). Conclusion: In diagnosing obstructive jaundice, HASTE MRCP is similar to ERCP but better than CT and B-type ultrasonography , with the merits of fast imaging and high resolution as an ideal sequence for MRCP imaging.

Magnetic resonance cholangiopancreatography study of pancreaticobiliary maljunction and pancreaticobiliary diseases

AIM: To discuss the imaging anatomy about pancreaticobiliary ductal union, occurrence rate of pancreaticobiliary maljunction (PBM) and associated diseases in a Chinese population by using magnetic resonance cholangiopancreatography (MRCP).

^(18)F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice

BACKGROUND： The various origins of obstructive jaundice make the diagnosis of the disease difficult. This study was undertaken to evaluate the role of 18F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice and to quantify the added value of 18F-FDG PET/CT over conventional imaging（enhanced CT and/or MRI）.METHODS： Eighty-five patients with obstructive jaundice who underwent 18F-FDG PET/CT within 2 weeks after enhanced CT and/or MRI were reviewed retrospectively. All 18F-FDG PET/CT images were independently evaluated by 2 nuclear medicine physicians who were unaware of other imaging data; differences were resolved by consensus of the physicians. All conventional imaging interpretations, according to the medical records, were reviewed by 2 radiologists to determine the potential value. Final diagnoses were based on histological or surgical findings.RESULTS： Sixty-six patients were diagnosed with malignancies, and 19 patients with benign lesions. The maximum standardized uptake values for malignant and benign lesions causing biliary obstruction were 8.2±4.4 and 4.0±5.0, respectively（P〈0.05）. The sensitivity, specificity, and overall accuracy for differentiating malignant from benign origins with 18F-FDG PET/CT were 86.4%（57/66）, 73.7%（14/19）, and 83.5%（71/85）, respectively. 18F-FDG PET/CT in conjunction with conventional imaging changed the sensitivity, specificity, and overall accuracy of conventional imaging alone from 75.8%（50/66） to 95.5%（63/66）（P〈0.05）, 68.4%（13/19） to 57.9%（11/19）（P〉0.05）, and 74.1%（63/85） to 87.1%（74/85）（P〈0.05）, respectively.CONCLUSIONS： 18F-FDG PET/CT is of great value in differentiating malignant from benign origins of obstructive jaundice and is a useful adjuvant to conventional imaging. 18F-FDG PET/CT should be recommended for further etiological clarification.

Magnetic resonance imaging techniques for lithium-ion batteries:Principles and applications

Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear magnetic resonance(NMR)techniques.This review provides a comprehensive overview of the recent applications and advancements of non-invasive magnetic resonance imaging(MRI)techniques in LIBs.It initially introduces the principles and hardware of MRI,followed by a detailed summary and comparison of MRI techniques used for characterizing liquid/solid electrolytes,electrodes and commercial batteries.This encompasses the determination of electrolytes'transport properties,acquisition of ion distribution profile,and diagnosis of battery defects.By focusing on experimental parameters and optimization strategies,our goal is to explore MRI methods suitable to a variety of research subjects,aiming to enhance imaging quality across diverse scenarios and offer critical physical/chemical insights into the ongoing operation processes of LIBs.

A modified method for locating parapharyngeal space neoplasms on magnetic resonance images: implications for differential diagnosis

The parapharyngeal space(PPS) is an inverted pyramid-shaped deep space in the head and neck region, and a variety of tumors, such as salivary gland tumors, neurogenic tumors, nasopharyngeal carcinomas with parapharyngeal invasion, and lymphomas, can be found in this space. The differential diagnosis of PPS tumors remains challenging for radiologists. This study aimed to develop and test a modified method for locating PPS tumors on magnetic resonance(MR) images to improve preoperative differential diagnosis. The new protocol divided the PPS into three compartments: a prestyloid compartment, the carotid sheath, and the areas outside the carotid sheath. PPS tumors were located in these compartments according to the displacements of the tensor veli palatini muscle and the styloid process, with or without blood vessel separations and medial pterygoid invasion. This protocol, as well as a more conventional protocol that is based on displacements of the internal carotid artery(ICA), was used to assess MR images captured from a series of 58 PPS tumors. The consequent distributions of PPS tumor locations determined by both methods were compared. Of all 58 tumors, our new method determined that 57 could be assigned to precise PPS compartments. Nearly all(13/14; 93%) tumors that were located in the pre-styloid compartment were salivary gland tumors. All 15 tumors within the carotid sheath were neurogenic tumors. The vast majority(18/20; 90%) of trans-spatial lesions were malignancies. However, according to the ICA-based method, 28 tumors were located in the pre-styloid compartment, and 24 were located in the post-styloid compartment, leaving 6 tumors that were difficult to locate. Lesions located in both the pre-styloid and the post-styloid compartments comprised various types of tumors. Compared with the conventional ICA-based method, our new method can help radiologists to narrow the differential diagnosis of PPS tumors to specific compartments.

Application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis

Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods In the outpatient department of our hospital(Sichuan Cancer Hospital,Chengdu,China),60 patients diagnosed with prostate disease were selected randomly and included in a prostate cancer group,60 patients with benign prostatic hyperplasia were included in a proliferation group,and 60 healthy subjects were included in a control group,from January 2013 to January 2017.Using Siemens Avanto 1.5 T high-field superconducting MRI for DCE-MRI and MRS scans,after the MRS scan was completed,we used the workstation spectroscopy tab spectral analysis,and eventually obtained the crest lines of the prostate metabolites choline(Cho),creatine(Cr),citrate(Cit),and the values of Cho/Cit,and(Cho+Cr)/Cit.Results Participants who had undergone 21-s,1-min,and 2-min dynamic contrast-enhanced MR revealed significant variations among the three groups.The spectral analysis of the three groups revealed a significant variation as well.DCE-MRI and MRS combined had a sensitivity of 89.67%,specificity of 95.78%,and accuracy of 94.34%.Conclusion DCE-MRI combined with MRS is of great value in the diagnosis of prostate cancer.

Role of diffusion-weighted magnetic resonance imaging in the diagnosis of extrahepatic cholangiocarcinoma

AIM: To determine the clinical value of diffusion-weight- ed imaging (DWI) for the diagnosis of extrahepatic cholangiocarcinoma (EHCC) by comparing the diagnostic sensitivity of DWI and magnetic resonance cholan-giopancreatography (MRCP). METHODS: Magnetic resonance imaging examination was performed in 56 patients with suspected EHCC. T1- weighted imaging, T2-weighted imaging, MRCP and DWI sequence, DWI using single-shot spin-echo echoplanar imaging sequence with different b values (100, 300, 500, 800 and 1000 s/mm2), were performed. All cases were further confirmed by surgery or histopathological diagnosis. Two radiologists jointly performed the analysis of the DWI and MRCP images. Apparent diffusion coefficient (ADC) value and signal-noise ratio were calculated for EHCC. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value were tested using DWI with a b value of 500 s/mm2 and MRCP images, respectively. RESULTS: Histopathological diagnosis confirmed that among the 56 cases, 35 were EHCC (20 hilar and 15 distal extrahepatic), 16 were cholangitis, and 5 were cal-culus of bile duct. Thirty-three out of the 35 EHCC cases were detected by DWI. EHCC exhibited differential levels of high signal intensity in DWI and low signal intensity in the ADC map. The mean value for ADC was (1.31 ± 0.29) × 10-3 mm2/s. The detection rate of EHCC was significantly higher by DWI (94.3%) than by MRCP (74.3%) (P < 0.05). There was a significant difference in sensitivity (94.3% vs 74.3%), specificity (100% vs 71.4%), accu- racy (96.4% vs 73.2%), positive predictive value (100% vs 81.3%), and negative predictive value (91.3% vs 62.5%) between DWI and MRCP in diagnosing EHCC. CONCLUSION: DWI has a high sensitivity for the detection of EHCC as it shows the EHCC lesion more unambiguously than MRCP does. DWI can also provide additional clinically important information in EHCC patients when added to routine bile duct MR imaging protocols.

Generalized Nonconvex Low-Rank Algorithm for Magnetic Resonance Imaging (MRI) Reconstruction

In recent years,utilizing the low-rank prior information to construct a signal from a small amount of measures has attracted much attention.In this paper,a generalized nonconvex low-rank(GNLR) algorithm for magnetic resonance imaging(MRI)reconstruction is proposed,which reconstructs the image from highly under-sampled k-space data.In the algorithm,the nonconvex surrogate function replacing the conventional nuclear norm is utilized to enhance the low-rank property inherent in the reconstructed image.An alternative direction multiplier method(ADMM) is applied to solving the resulting non-convex model.Extensive experimental results have demonstrated that the proposed method can consistently recover MRIs efficiently,and outperforms the current state-of-the-art approaches in terms of higher peak signal-to-noise ratio(PSNR) and lower high-frequency error norm(HFEN) values.

Computer-aided differential diagnosis system for Alzheimer’s disease based on machine learning with functional and morphological image features in magnetic resonance imaging

Alzheimer’s disease (AD) is a dementing disorder and one of the major public health problems in countries with greater longevity. The cerebral cortical thickness and cerebral blood flow (CBF), which are considered as morphological and functional image features, respectively, could be decreased in specific cerebral regions of patients with dementia of Alzheimer type. Therefore, the aim of this study was to develop a computer-aided classification system for AD patients based on machine learning with the morphological and functional image features derived from a magnetic resonance (MR) imaging system. The cortical thicknesses in ten cerebral regions were derived as morphological features by using gradient vector trajectories in fuzzy membership images. Functional CBF maps were measured with an arterial spin labeling technique, and ten regional CBF values were obtained by registration between the CBF map and Talairach atlas using an affine transformation and a free form deformation. We applied two systems based on an arterial neural network (ANN) and a support vector machine (SVM), which were trained with 4 morphological and 6 functional image features, to 15 AD patients and 15 clinically normal (CN) subjects for classification of AD. The area under the receiver operating characteristic curve (AUC) values for the two systems based on the ANN and SVM with both image?features were 0.901 and 0.915, respectively. The AUC values for the ANN-and SVM-based systems with the morphological features were 0.710 and 0.660, respectively, and those with the functional features were 0.878 and 0.903, respectively. Our preliminary results suggest that the proposed method may have potential for assisting radiologists in the differential diagnosis of AD patients by using morphological and functional image features.

Brain Tumor Classification in Magnetic Resonance Images Using Deep Learning and Wavelet Transform

A brain tumor is a mass of abnormal cells in the brain. Brain tumors can be benign (noncancerous) or malignant (cancerous). Conventional diagnosis of a brain tumor by the radiologist is done by examining a set of images produced by magnetic resonance imaging (MRI). Many computer-aided detection (CAD) systems have been developed in order to help the radiologists reach their goal of correctly classifying the MRI image. Convolutional neural networks (CNNs) have been widely used in the classification of medical images. This paper presents a novel CAD technique for the classification of brain tumors in MRI images. The proposed system extracts features from the brain MRI images by utilizing the strong energy compactness property exhibited by the Discrete Wavelet Transform (DWT). The Wavelet features are then applied to a CNN to classify the input MRI image. Experimental results indicate that the proposed approach outperforms other commonly used methods and gives an overall accuracy of 99.3%.

Reduced Imaging Time and Improved Image Quality of 3D Isotropic T2-Weighted Magnetic Resonance Imaging with Compressed Sensing for the Female Pelvis

This study is to compare three-dimensional(3D)isotropic T2-weighted magnetic resonance imaging(MRI)with compressed sensing-sampling perfection with application optimized contrast(CS-SPACE)and the conventional image(3D-SPACE)sequence in terms of image quality,estimated signal-to-noise ratio(SNR),relative contrast-to-noise ratio(CNR),and the lesions’conspicuous of the female pelvis.Thirty-six females(age:51,28-73)with cervical carcinoma(n=20),rectal carcinoma(n=7),or uterine fibroid(n=9)were included.Patients underwent magnetic resonance(MR)imaging at a 3T scanner with the sequences of 3D-SPACE,CS-SPACE,and twodimensional(2D)T2-weighted turbo-spin echo(TSE).Quantitative analyses of estimated SNR and relative CNR between tumors and other tissues,image quality,and tissue conspicuity were performed.Two radiologists assessed the difference in diagnostic findings for carcinoma.Quantitative values and qualitative scores were analyzed,respectively.The estimated SNR and the relative CNR of tumor-to-muscle obturator internus,tumor-to-myometrium,and myometrium-to-muscle obturator internus was comparable between 3D-SPACE and CS-SPACE.The overall image quality and the conspicuity of the lesion scores of the CS-SPACE were higher than that of the 3D-SPACE(P<0.01).The CS-SPACE sequence offers shorter scan time,fewer artifacts,and comparable SNR and CNR to conventional 3D-SPACE,and has the potential to improve the performance of T2-weighted images.

Obstacles Facing the Implementation of Functional Magnetic Resonance Imaging （fMRI） of Brain in Jeddah City

fMRI （Functional Magnetic Resonance Imaging） is a relatively new technique that uses MRI （Magnetic Resonance Imaging） to measure the hemodynamic response （change in blood flow） related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.

MAGNETIC RESONANCE IMAGES OF THE HYPOTHALAMIC-PITUITARY AREA IN IDIOPATHIC GROWTH DEFICIENCY

In order to describe the magnetic resonance imaging (MRI) findings in hypothalamic-pituitary area and its clinical relevance in patients with idiopathic growth hormone deficiency (IGHD), the MR imagings of 26 patients with IGHD were analyzed. On MRI, 24 out of 26 cases (92. 3%) showed apparent pituitary upper margin depression; 8 out of 26 cases (30. 8%) showed definite pituitary stalk transection; 22 out of 26 cases (84. 6%) showed absence of the normal posterior pituitary bright spot. The bright lipidlike signal on T1W1 images at the median eminence distal to the breaking point (so-called ectopic posterior lobe) was found in 4 out of 26 cases (15. 4%). According to the MRI findings of the pituitary stalks, the 26 cases were divided into three groups; group A of 8 cases (31%) characterized by the definite transaction of stalk; group B of 13 cases (50%) defined by the possible stalk transection; and group C of 5 cases (19%) with no definite stalk transection.MRI findings were consistent with the clinical and endocrine tests. The stalk transection was statistically significantly difference in insulin test, L-dopa/p test, and height standard deviation score (P< 0.05). The MRI of hypothalamic-pituitary area may differentiate partial IGHD form stalk-transected, doubtful transection and without transection.

Gd-EOB-DTPA-enhanced magnetic resonance imaging for bile duct intraductal papillary mucinous neoplasms

AIM: To investigate gadolinium-ethoxybenzyldiethylenetriamine-pentaacetic acid(Gd-EOB-DTPA)-enhanced magnetic resonance imaging(MRI) of intraductal papillary mucinous neoplasms of the bile duct(IPMN-B). METHODS: The imaging findings of five cases of IPMN-B which were pathologically confirmed at our hospital between March 2012 and May 2013 were retrospectively analyzed. Three of these cases were diagnosed by duodenal endoscopy and biopsy pathology, and two cases were diagnosed by surgical pathology. All five patients underwent enhanced and non-enhanced computed tomography(CT), magnetic resonance cholangiopancreatography, and Gd-EOB-DTPA-enhanced MRI; one case underwent both Gd-EOB-DTPA-enhanced MRI and positron emission tomography-CT. The clinical data and imaging results for these cases were compared and are presented.RESULTS: Conventional imaging showed diffusedilatation of bile ducts and multiple intraductal polypoid and papillary neoplasms or serrated changes along the bile ducts. In two cases, Gd-EOB-DTPA-enhanced MRI revealed dilated biliary ducts and intraductal tumors, as well as filling defects caused by mucin in the dilated bile ducts in the hepatobiliary phase. GdEOB-DTPA-enhanced MRI in one case clearly showed a low-signal tumor in the hepatobiliary phase, similar to what was seen by positron emission tomographyCT. In two patients, routine inspection was unable to discern whether the lesions were inflammation or tumors. However, Gd-EOB-DTPA-enhanced MRI revealed a pattern of gradual enhancement during the hepatobiliary phase, and the signal intensity of the lesions was lower than the surrounding liver parenchyma, suggesting tissue inflammation in both cases, which were confirmed by surgical pathology. CONCLUSION: Gd-EOB-DTPA-enhanced MRI reveals the intraductal mucin component of IPMN-B in some cases and the extent of tumor infiltration beyond the bile ducts in invasive cases.

Current and future applications of magnetic resonance imaging and spectroscopy of the brain in hepatic encepha-lopathy

Hepatic encephalopathy （HE） is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestations of HE are widely variable and involve a spectrum from mild subclinical disturbance to deep coma. Research interest has focused on the role of circulating gut-derived toxins, particularly ammonia, the development of brain swelling and changes in cerebral neurotransmitter systems that lead to global CNS depression and disordered function. Until recently the direct investigation of cerebral function has been difficult in man. However, new magnetic resonance imaging （MRI） techniques provide a non-invasive means of assessment of changes in brain volume （coregistered MRI） and impaired brain function （fMRI）, while proton magnetic resonance spectroscopy （^1H MRS） detects changes in brain biochemistry, including direct measurement of cerebral osmolytes, such as myoinositol, glutamate and glutamine which govern processes intrinsic to cellular homeostasis, including the accumulation of intracellular water. The concentrations of these intracellular osmolytes alter with hyperammonaemia. MRS-detected metabolite abnormalities correlate with the severity of neuropsychiatric impairment and since MR spectra return towards normal after treatment, the technique may be of use in objective patient monitoring and in assessing the effectiveness of various treatment regimens.

Targeted prostate biopsy： value of multiparametric magnetic resonance imaging in detection of localized cancer

Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound （TRUS）-guided biopsy has been used for the diagnosis of prostate cancer for over 2 decades, but the technique is usually blind to cancer location. Moreover, the false negative rate of TRUS biopsy has been reported to be as high as 47%. Multiparametric magnetic resonance imaging （mp-MRI） includes T1- and T2-weighted imaging as well as dynamic contrast-enhanced （DCE） and diffusion-weighted imaging （DWI）. mp-MRI is a major advance in the imaging of prostate cancer, enabling targeted biopsy of suspicious lesions. Evolving targeted biopsy techniquesmincluding direct in-bore biopsy, cognitive fusion and software-based MRI-ultrasound （MRI-US） fusion--have led to a several-fold improvement in cancer detection compared to the earlier method. Importantly, the detection of clinically significant cancers has been greatly facilitated by targeting, compared to systematic biopsy alone. Targeted biopsy via MRI-US fusion may dramatically alter the way prostate cancer is diagnosed and managed.

Magnetic resonance imaging for prostate cancer clinical application

As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In clinical practice, magnetic resonance imaging （MRI） is one of the imaging tools for the evaluation of prostate cancer, the fusion of MRI or dynamic contrast-enhanced MRI （DCE-MRI） with magnetic resonance spectroscopic imaging （MRSI） is improving the evaluation of cancer locafon, size, and extent, while providing an indication of tumor aggressiveness. This review summarizes the role of MRI in the application of prostate cancer and describes molecular MRI techniques （including MRSI and DCE-MRI） for aiding prostate cancer management.

Nasopharyngeal adenoid cystic carcinoma: magnetic resonance imaging features in ten cases

Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 cases of NACC and summarized the magnetic resonance imaging (MRI) features. MR images of 10 patients with histologically validated NACC were reviewed by two experienced radiologists. The location, shape, margin, signal intensity, lesion texture, contrast enhancement patterns, local invasion, and cervical lymphadenopathy of all tumors were evaluated. Clinical and pathologic records were also reviewed. No patients were positive for antibodies against Epstein-Barr virus (EBV). The imaging patterns of primary tumors were classified into two types as determined by location, shape, and margin. Of all patients, 7 had tumors with a type 1 imaging pattern and 3 had tumors with a type 2 imaging pattern. The 4 tubular NACCs were all homogeneous tumors, whereas 3 (60%) of 5 cribriform NACCs and the sole solid NACC were heterogeneous tumors with separations or central necrosis on MR images. Five patients had perineural infiltration and intracranial involvement, and only 2 had cervical lymphadenopathy. Based on these results, we conclude that NACC is a local, aggressive neoplasm that is often negative for EBV infection and associated with a low incidence of cervical lymphadenopathy. Furthermore, MRI features of NACC vary in locations and histological subtypes.

Biliary complications after liver transplantation:A computed tomography and magnetic resonance imaging pictorial review

Biliary complications are the most common complications after liver transplantation.Computed tomography(CT)and magnetic resonance imaging(MRI)are cornerstones for timely diagnosis of biliary complications after liver transplantation.The diagnosis of these complications by CT and MRI requires expertise,mainly with respect to identifying subtle early signs to avoid missed or incorrect diagnoses.For example,biliary strictures may be misdiagnosed on MRI due to size mismatch of the common ducts of the donor and recipient,postoperative edema,pneumobilia,or susceptibility artifacts caused by surgical clips.Proper and prompt diagnosis of biliary complications after transplantation allows the timely initiation of appropriate management.The aim of this pictorial review is to illustrate various CT and MRI findings related to biliary complications after liver transplantation,based on time of presentation after surgery and frequency of occurrence.