Staging liver fibrosis with various diffusion-weighted magnetic resonance imaging models

BACKGROUND Diffusion-weighted imaging(DWI)has been developed to stage liver fibrosis.However,its diagnostic performance is inconsistent among studies.Therefore,it is worth studying the diagnostic value of various diffusion models for liver fibrosis in one cohort.AIM To evaluate the clinical potential of six diffusion-weighted models in liver fibrosis staging and compare their diagnostic performances.METHODS This prospective study enrolled 59 patients suspected of liver disease and scheduled for liver biopsy and 17 healthy participants.All participants underwent multi-b value DWI.The main DWI-derived parameters included Mono-apparent diffusion coefficient(ADC)from mono-exponential DWI,intravoxel incoherent motion model-derived true diffusion coefficient(IVIM-D),diffusion kurtosis imaging-derived apparent diffusivity(DKI-MD),stretched exponential model-derived distributed diffusion coefficient(SEM-DDC),fractional order calculus(FROC)model-derived diffusion coefficient(FROC-D)and FROC model-derived microstructural quantity(FROC-μ),and continuous-time random-walk(CTRW)model-derived anomalous diffusion coefficient(CTRW-D)and CTRW model-derived temporal diffusion heterogeneity index(CTRW-α).The correlations between DWI-derived parameters and fibrosis stages and the parameters’diagnostic efficacy in detecting significant fibrosis(SF)were assessed and compared.RESULTS CTRW-D(r=-0.356),CTRW-α(r=-0.297),DKI-MD(r=-0.297),FROC-D(r=-0.350),FROC-μ(r=-0.321),IVIM-D(r=-0.251),Mono-ADC(r=-0.362),and SEM-DDC(r=-0.263)were significantly correlated with fibrosis stages.The areas under the ROC curves(AUCs)of the combined index of the six models for distinguishing SF(0.697-0.747)were higher than each of the parameters alone(0.524-0.719).The DWI models’ability to detect SF was similar.The combined index of CTRW model parameters had the highest AUC(0.747).CONCLUSION The DWI models were similarly valuable in distinguishing SF in patients with liver disease.The combined index of CTRW parameters had the highest AUC.

Transient elastography and diffusion-weighted magnetic resonance imaging for assessment of liver fibrosis in children with chronic hepatitis C

BACKGROUND Chronic hepatitis C(CHC)is a health burden with consequent morbidity and mortality.Liver biopsy is the gold standard for evaluating fibrosis and assessing disease severity and prognostic purposes post-treatment.Noninvasive altern-atives for liver biopsy such as transient elastography(TE)and diffusion-weighted magnetic resonance imaging(DW-MRI)are critical needs.AIM To evaluate TE and DW-MRI as noninvasive tools for predicting liver fibrosis in children with CHC.METHODS This prospective cross-sectional study initially recruited 100 children with CHC virus infection.Sixty-four children completed the full set of investigations including liver stiffness measurement(LSM)using TE and measurement of apparent diffusion coefficient(ADC)of the liver and spleen using DW-MRI.Liver biopsies were evaluated for fibrosis using Ishak scoring system.LSM and liver and spleen ADC were compared in different fibrosis stages and correlation analysis was performed with histopathological findings and other laboratory parameters.RESULTS Most patients had moderate fibrosis(73.5%)while 26.5%had mild fibrosis.None had severe fibrosis or cirrhosis.The majority(68.8%)had mild activity,while only 7.8%had moderate activity.Ishak scores had a significant direct correlation with LSM(P=0.008)and were negatively correlated with both liver and spleen ADC but with no statistical significance(P=0.086 and P=0.145,respectively).Similarly,histopatho-logical activity correlated significantly with LSM(P=0.002)but not with liver or spleen ADC(P=0.84 and 0.98 respectively).LSM and liver ADC were able to significantly discriminate F3 from lower fibrosis stages(area under the curve=0.700 and 0.747,respectively)with a better performance of liver ADC.CONCLUSION TE and liver ADC were helpful in predicting significant fibrosis in children with chronic hepatitis C virus infection with a better performance of liver ADC.

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.

Clinical study on improving the diagnostic accuracy of adult elbow joint cartilage injury by multisequence magnetic resonance imaging

BACKGROUND Due to frequent and high-risk sports activities,the elbow joint is susceptible to injury,especially to cartilage tissue,which can cause pain,limited movement and even loss of joint function.AIM To evaluate magnetic resonance imaging(MRI)multisequence imaging for improving the diagnostic accuracy of adult elbow cartilage injury.METHODS A total of 60 patients diagnosed with elbow cartilage injury in our hospital from January 2020 to December 2021 were enrolled in this retrospective study.We analyzed the accuracy of conventional MRI sequences(T1-weighted imaging,T2-weighted imaging,proton density weighted imaging,and T2 star weighted image)and Three-Dimensional Coronary Imaging by Spiral Scanning(3D-CISS)in the diagnosis of elbow cartilage injury.Arthroscopy was used as the gold standard to evaluate the diagnostic effect of single and combination sequences in different injury degrees and the consistency with arthroscopy.RESULTS The diagnostic accuracy of 3D-CISS sequence was 89.34%±4.98%,the sensitivity was 90%,and the specificity was 88.33%,which showed the best performance among all sequences(P<0.05).The combined application of the whole sequence had the highest accuracy in all sequence combinations,the accuracy of mild injury was 91.30%,the accuracy of moderate injury was 96.15%,and the accuracy of severe injury was 93.33%(P<0.05).Compared with arthroscopy,the combination of all MRI sequences had the highest consistency of 91.67%,and the kappa value reached 0.890(P<0.001).CONCLUSION Combination of 3D-CISS and each sequence had significant advantages in improving MRI diagnostic accuracy of elbow cartilage injuries in adults.Multisequence MRI is recommended to ensure the best diagnosis and treatment.

Fetal MRI Artifacts: Semi-Supervised Generative Adversarial Neural Network for Motion Artifacts Reducing in Fetal Magnetic Resonance Images

This study addresses challenges in fetal magnetic resonance imaging (MRI) related to motion artifacts, maternal respiration, and hardware limitations. To enhance MRI quality, we employ deep learning techniques, specifically utilizing Cycle GAN. Synthetic pairs of images, simulating artifacts in fetal MRI, are generated to train the model. Our primary contribution is the use of Cycle GAN for fetal MRI restoration, augmented by artificially corrupted data. We compare three approaches (supervised Cycle GAN, Pix2Pix, and Mobile Unet) for artifact removal. Experimental results demonstrate that the proposed supervised Cycle GAN effectively removes artifacts while preserving image details, as validated through Structural Similarity Index Measure (SSIM) and normalized Mean Absolute Error (MAE). The method proves comparable to alternatives but avoids the generation of spurious regions, which is crucial for medical accuracy.

Machine Learning-Based Models for Magnetic Resonance Imaging(MRI)-Based Brain Tumor Classification

In the medical profession,recent technological advancements play an essential role in the early detection and categorization of many diseases that cause mortality.The technique rising on daily basis for detecting illness in magnetic resonance through pictures is the inspection of humans.Automatic(computerized)illness detection in medical imaging has found you the emergent region in several medical diagnostic applications.Various diseases that cause death need to be identified through such techniques and technologies to overcome the mortality ratio.The brain tumor is one of the most common causes of death.Researchers have already proposed various models for the classification and detection of tumors,each with its strengths and weaknesses,but there is still a need to improve the classification process with improved efficiency.However,in this study,we give an in-depth analysis of six distinct machine learning(ML)algorithms,including Random Forest(RF),Naïve Bayes(NB),Neural Networks(NN),CN2 Rule Induction(CN2),Support Vector Machine(SVM),and Decision Tree(Tree),to address this gap in improving accuracy.On the Kaggle dataset,these strategies are tested using classification accuracy,the area under the Receiver Operating Characteristic(ROC)curve,precision,recall,and F1 Score(F1).The training and testing process is strengthened by using a 10-fold cross-validation technique.The results show that SVM outperforms other algorithms,with 95.3%accuracy.

Role of diffusion-weighted magnetic resonance imaging in the differential diagnosis of focal hepatic lesions

AIM： To evaluate the utility of diffusion-weighted imaging （DWl） in screening and differential diagnosis of benign and malignant focal hepatic lesions. METHODS： Magnetic resonance imaging （MRI） examinations were performed using the Signa Excite Xl Twin Speed 1.5T system （GE Healthcare, Milwaukee, Wl, USA）. Seventy patients who had undergone MRI of the liver [29 hepatocellular carcinomas （HCC）, four cholangiocarcinomas, 34 metastatic liver cancers, 10 hemangiomas, and eight cysts] between April 2004 and August 2008 were retrospectively evaluated. Visualization of lesions, relative contrast ratio （RCR）, and apparent diffusion coefficient （ADC） were compared between benign and malignant lesions on DWl. Su- perparamagnetic iron oxide （SPIO） was administered to 59 patients, and RCR was compared pre- and postadministration.RESULTS： DWI showed higher contrast between malignant lesions （especially in multiple small metastatic cancers） and surrounding liver parenchyma than did contrast-enhanced computed tomography. ADCs （mean±SD × 10^-3 mm2/s） were significantly lower （P 〈 0.05） in malignant lesions （HCC： 1.31 ± 0.28 and liver metastasis： 1.11 ± 0.22） and were significantly higher in benign lesions （hemangioma： 1.84 ± 0.37 and cyst： 2.61 ± 0.45） than in the surrounding hepatic tissues. RCR between malignant lesions and surrounding he- patic tissues significantly improved after SPIO administration, but RCRs in benign lesions were not improved.CONCLUSION： DWI is a simple and sensitive method for screening focal hepatic lesions and is useful for differential diagnosis.

Acute pancreatitis successfully diagnosed by diffusion-weighted imaging: A case report

Diffusion-weighted imaging (DWI) is an established diagnostic method of acute stroke. The latest advances in magnetic resonance imaging (MRI) technology have greatly expanded the utility of DWI in the examination of various organs. Recent studies have revealed the usefulness of DWI for imaging of the liver, kidney, ovary, and breast. We report a patient with acute pancreatitis detected by DWI and discussed the efficacy of DWI in diagnosing acute pancreatitis. A 50-year old man presented with a primary complaint of abdominal pain. We performed both DWI and computed tomography (CT) for this patient. The signal intensity in a series of DWI was measured and the apparent diffusion coefficient (ADC) values were calculated to differentiate inflammation from normal tissue. Two experienced radiologists evaluated the grade of acute pancreatitis by comparing the CT findings. Initially, the pancreas and multiple ascites around the pancreas produced a bright signal and ADC values were reduced on DWI. As the inflammation decreased, the bright signal faded to an iso-signal and the ADC values returned to their normal level. There was no difference in the abilities of DWI and CT images to detect acute pancreatitis. However, our case indicates that DWI can evaluate the manifestations of acute pancreatitis using no enhancement material andhas the potential to replace CT as a primary diagnostic strategy for acute pancreatitis.

Hepatocellular carcinoma: Can LI-RADS v2017 with gadoxetic-acid enhancement magnetic resonance and diffusion-weighted imaging improve diagnostic accuracy?

BACKGROUND The Liver Imaging Reporting and Data System(LI-RADS), supported by the American College of Radiology(ACR), has been developed for standardizing the acquisition, interpretation, reporting, and data collection of liver imaging examinations in patients at risk for hepatocellular carcinoma(HCC). Diffusionweighted imaging(DWI), which is described as an ancillary imaging feature of LI-RADS, can improve the diagnostic efficiency of LI-RADS v2017 with gadoxetic acid-enhanced magnetic resonance imaging(MRI) for HCC.AIM To determine whether the use of DWI can improve the diagnostic efficiency of LIRADS v2017 with gadoxetic acid-enhanced magnetic resonance MRI for HCC.METHODS In this institutional review board-approved study, 245 observations of high risk of HCC were retrospectively acquired from 203 patients who underwent gadoxetic acid-enhanced MRI from October 2013 to April 2018. Two readers independently measured the maximum diameter and recorded the presence of each lesion and assigned scores according to LI-RADS v2017. The test was used to determine the agreement between the two readers with or without DWI. In addition, the sensitivity(SE), specificity(SP), accuracy(AC), positive predictive value(PPV), and negative predictive value(NPV) of LI-RADS were calculated.Youden index values were used to compare the diagnostic performance of LIRADS with or without DWI.RESULTS Almost perfect interobserver agreement was obtained for the categorization of observations with LI-RADS(kappa value: 0.813 without DWI and 0.882 with DWI). For LR-5, the diagnostic SE, SP, and AC values were 61.2%, 92.5%, and71.4%, respectively, with or without DWI; for LR-4/5, they were 73.9%, 80%, and75.9% without DWI and 87.9%, 80%, and 85.3% with DWI; for LR-4/5/M, they were 75.8%, 58.8%, and 70.2% without DWI and 87.9%, 58.8%, and 78.4% with DWI; for LR-4/5/TIV, they were 75.8%, 75%, and 75.5% without DWI and 89.7%,75%, and 84.9% with DWI. The Youden index values of the LI-RADS classification without or with DWI were as follows: LR-4/5: 0.539 vs 0.679; LR-4/5/M: 0.346 vs 0.467; and LR-4/5/TIV: 0.508 vs 0.647.CONCLUSION LI-RADS v2017 has been successfully applied with gadoxetate-enhanced MRI for patients at high risk for HCC. The addition of DWI significantly increases the diagnostic efficiency for HCC.

Characteristics and pathological mechanism on magnetic resonance diffusion-weighted imaging after chemoembolization in rabbit liver VX-2 tumor model

AIM: To investigate dynamic characteristics and pathological mechanism of signal in rabbit VX-2 tumor model on diffusion-weighted imaging (DWI) after chemoembolization. METHODS: Forty New Zealand rabbits were included in the study and forty-seven rabbit VX-2 tumor models were raised by implanting directly and intrahepatically after abdominal cavity opened. Forty VX-2 tumor models from them were divided into four groups. DWI was performed periodically and respectively for each group after chemoembolization. All VX-2 tumor samples of each group were studied by pathology. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance between different time groups, different area groups or different b-value groups was calculated by using SPSS12.0 software. RESULTS: Under b-value of 100 s/mm2, ADC values were lowest at 16 h after chemoembolization in area of VX-2 tumor periphery, central, and normal liver parenchyma around tumor, but turned to increase with further elongation of chemoembolization treatment. The distinction of ADC between different time groups was significant respectively (F = 7.325, P < 0.001; F = 2.496, P < 0.048; F = 6.856, P < 0.001). Cellular edema in the area of VX-2 tumor periphery or normal liver parenchyma around tumor, increased quickly in sixteen h after chemoembolization but, from the 16th h to the 48th h, cellular edema in the area of normal liver parenchyma around tumor decreased gradually and that in the area of VX-2 tumor periphery decreased lightly at, and then increased continually. After chemoembolization, Cellular necrosis in the area of VX-2 tumor periphery was more significantly high than that before chemoembolization. The areas of dead cells in VX-2 tumors manifested low signal and high ADC value, while the areas of viable cells manifested high signal and low ADC value. CONCLUSION: DWI is able to detect and differentiate tumor necrotic areas from viable cellular areas before and after chemoembolization. ADC of normal liver parenchyma and VX-2 tumor are influenced by intracellular edema, tissue cellular death and microcirculation disturbance after chemoembolization.

Diffusion-weighted magnetic resonance imaging to predict response of hepatocellular carcinoma to chemoembolization

AIM: To investigate whether intra-procedural diffusion- weighted magnetic resonance imaging can predict response of hepatocellular carcinoma (HCC) during trans- catheter arterial chemoembolization (TACE). METHODS: Sixteen patients (15 male), aged 59 ±11 years (range: 42-81 years) underwent a total of 21 separate treatments for unresectable HCC in a hybrid magnetic resonance/interventional radiology suite. Ana- tomical imaging and diffusion-weighted imaging (b = 0, 500 s/mm2) were performed on a 1.5-T unit. Tumor enhancement and apparent diffusion coefficient (ADC, mm2/s) values were assessed immediately before and at 1 and 3 mo after TACE. We calculated the percent change (PC) in ADC values at all time points. We compared follow-up ADC values to baseline values using a paired t test (α = 0.05). RESULTS: The intra-procedural sensitivity, specificity, and positive and negative predictive values (%) for detecting a complete or partial 1-mo tumor response using ADC PC thresholds of ±5%, ±10%, and ±15% were 77, 67, 91, and 40; 54, 67, 88, and 25; and 46, 100, 100, and 30, respectively. There was no clear predictive value for the 3-mo follow-up. Compared to baseline, the immediate post-procedure and 1-mo mean ADC values both increased; the latter obtaining statistical significance (1.48 ± 0.29 mm2/s vs 1.65 ± 0.35 × 10-3 mm2/s, P < 0.014). CONCLUSION: Intra-procedural ADC changes of > 15% predicted 1-mo anatomical HCC response with the greatest accuracy, and can provide valuable feedback at the time of TACE.

Diffusion-weighted imaging of biliopancreatic disorders:Correlation with conventional magnetic resonance imaging

Diffusion-weighted magnetic resonance imaging(DWI)is a well established method for the evaluation of intracranial diseases,such as acute stroke.DWI for extracranial application is more difficult due to physiological motion artifacts and the heterogeneous composition of the organs.However,thanks to the newer technical development of DWI,DWI has become increasingly used over the past few years in extracranial organs including the abdomen and pelvis.Most previous studies of DWI have been limited to the evaluation of diffuse parenchymal abnormalities and focal lesions in abdominal organs,whereas there are few studies about DWI for the evaluation of the biliopancreatic tract.Although further studies are needed to determine its performance in evaluating bile duct,gallbladder and pancreas diseases,DWI has potential in the assessment of the functional information on the biliopancreatic tract concerning the status of tissue cellularity,because increased cellularity is associated with impeded diffusion,as indicated by a reduction in the apparent diffusion coefficient.The detection of malignant lesions and their differentiation from benign tumor-like lesions in the biliopancreatic tract could be improved using DWI in conjunction with findings obtained with conventional magnetic resonance cholagiopancreatography.Additionally,DWI can be useful for the assessment of the biliopancreatic tract in patients with renal impairment because contrast-enhanced computed tomography or magnetic resonance scans should be avoided in these patients.

Diffusion-weighted magnetic resonance imaging for predicting the response of rectal cancer to neoadjuvant concurrent chemoradiation

AIM:To evaluate the clinical value of diffusion-weighted magnetic resonance imaging(DW-MRI)in predicting the response of rectal cancer to neoadjuvant chemoradiation.METHODS:This prospective study was approved by our institutional review board,and informed consent was obtained from each patient.Fifteen patients(median age 56 years)with locally advanced rectal cancer were treated in our hospital from June 2006 to December 2007.All patients were stageⅢB-C according to the results of MRI and endorectal ultrasound examinations.All patients underwent pelvic irradiation with 45 Gy/25 fx per 35 days.The concurrent chemotherapy regimen consisted of capecitabine 625mg/m2,bid(Monday-Friday),and oxaliplatin 50 mg/m2,weekly.The patients underwent surgery 5-8 wk after the completion of neoadjuvant therapy.T downstaging was defined as the downstaging of the tumor from cT3to ypT0-2 or from cT4 to ypT0-3.Good regression was defined as TRG 3-4,and poor regression was defined as TRG 0-2.Diffusion-weighted magnetic resonance images were obtained prior to and weekly during the course of neoadjuvant chemoradiation,and the apparent diffusion coefficient(ADC)values were calculated from the acquired tumor images.RESULTS:Comparison with the mean pretreatment tumor ADC revealed an increase in the mean tumor ADC during the course of neoadjuvant chemoradiation,especially at the 2ndweek(P=0.004).We found a strong negative correlation between the mean pretreatment tumor ADC and tumor regression after neoadjuvant chemoradiation(P=0.021).In the T downstage and tumor regression groups,we found a significant increase in the mean ADC at the 2ndweek of neoadjuvant therapy(P=0.011;0.004).CONCLUSION:DW-MRI might be a valuable clinical tool to help predict or assess the response of rectal cancer to neoadjuvant chemoradiation at an early timepoint.

Abdominal applications of diffusion-weighted magnetic resonance imaging: Where do we stand?

Diffusion-weighted imaging (DWI) is one of the magnetic resonance imaging (MRI) sequences providing qualitative as well as quantitative information at a cellular level. It has been widely used for various applications in the central nervous system. Over the past decade, various extracranial applications of DWI have been increasingly explored, as it may detect changes even before signal alterations or morphological abnormalities become apparent on other pulse sequences. Initial results from abdominal MRI applications are promising, particularly in oncological settings and for the detection of abscesses. The purpose of this article is to describe the clinically relevant basic concepts of DWI, techniques to perform abdominal DWI, its analysis and applications in abdominal visceral MR imaging, in addition to a brief overview of whole body DWI MRI.

Apparent diffusion coefficient by diffusion-weighted magnetic resonance imaging as a sole biomarker for staging and prognosis of gastric cancer

Objective： To investigate the role of apparent diffusion coefficient （ADC） from diffusion-weighted magnetic resonance imaging （DW-MRI） when applied to the 7th TNM classification in the staging and prognosis of gastric cancer （GC）. Methods： Between October 2009 and May 2014, a total of 89 patients with non-metastatic, biopsy proven GC underwent 1.5T DW-MRI, and then treated with radical surgery. Tumor ADC was measured retrospectively and compared with final histology following the 7th TNM staging （local invasion, nodal involvement and according to the different groups -- stage Ⅰ, Ⅱ and Ⅲ）. Kaplan-Meier curves were also generated. The follow-up period is updated to May 2016. Results： Median follow-up period was 33 months and 45/89 （51%） deaths from GC were observed. ADC was significantly different both for local invasion and nodal involvement （P〈0.001）. Considering final histology as the reference standard, a preoperative ADC cut-offof 1.80×10-3 mm^2/s could distinguish between stages I and Ⅱ and an ADC value of ≤1.36-10-3 mm^2/s was associated with stage Ⅲ（P〈0.001）. Kaplan-Meier curves demonstrated that the survival rates for the three prognostic groups were significantly different according to final histology and ADC cut-offs （P〈0.001）. Conclusions： ADC is different according to local invasion, nodal involvement and the 7th TNM stage groups for GC, representing a potential, additional prognostic biomarker. The addition of DW-MRI could aid in the staging and risk stratification of GC.

Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

Diffusion-weighted magnetic resonance imaging(DWMRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer.It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DWMRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the nonmono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging(DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer.

Diffusion-weighted magnetic resonance imaging without bowel preparation for detection of ulcerative colitis

AIM: To evaluate the accuracy of diffusion-weighted imaging(DWI) without bowel preparation,the optimal b value and the changes in apparent diffusion coefficient(ADC) in detecting ulcerative colitis(UC).METHODS: A total of 20 patients who underwent 3T magnetic resonance imaging(MRI) without bowel preparation and colonoscopy within 24 h were recruited.Biochemical indexes,including C-reactive protein(CRP),erythrocyte sedimentation rate,hemoglobin,leucocytes,platelets,serum iron and albumin,were determined.Biochemical examinations were then performed within 24 h before or after MR colonography was conducted.DWI was performed at various b values(b = 0,400,600,800,and 1000 s/mm2).Two radiologists independently and blindly reviewed conventional- and contrast-enhanced MR images,DWI and ADC maps; these radiologists also determined ADC in each intestinal segment(rectum,sigmoid,left colon,transverse colon,and right colon).Receiver operating characteristic(ROC) analysis was performed to assess the diagnostic performance of DWI hyperintensity from various b factors,ADC values and different radiological signs to detect endoscopic inflammation in the corresponding bowel segment.Optimal ADC threshold was estimated by maximizing the combination of sensitivity and specificity.MRfindings were correlated with endoscopic results and clinical markers; these findings were then estimated by ROC analysis.RESULTS: A total of 100 segments(71 with endoscopic colonic inflammation; 29 normal) were included.The proposed total magnetic resonance score(MR-score-T) was correlated with the total modified Baron score(Baron-T; r = 0.875,P < 0.0001); the segmental MR score(MR-score-S) was correlated with the segmental modified Baron score(Baron-S; r = 0.761,P < 0.0001).MR-score-T was correlated with clinical and biological markers of disease activity(r = 0.445 to 0.831,P < 0.05).MR-score-S > 1 corresponded to endoscopic colonic inflammation with a sensitivity of 85.9%,a specificity of 82.8% and an area under the curve(AUC) of 0.929(P < 0.0001).The accuracy of DWI hyperintensity was significantly greater at b = 800 than at b = 400,600,or 1000 s/mm2(P < 0.05) when endoscopic colonic inflammation was detected.DWI hyperintensity at b = 800 s/mm2 indicated endoscopic colonic inflammation with a sensitivity of 93.0%,a specificity of 79.3% and an AUC of 0.867(P < 0.0001).Quantitative analysis results revealed that ADC values at b = 800 s/mm2 differed significantly between endoscopic inflamed segment and normal intestinal segment(1.56 ± 0.58 mm2/s vs 2.63 ± 0.46 mm2/s,P < 0.001).The AUC of ADC values was 0.932(95% confidence interval: 0.881-0.983) when endoscopic inflammation was detected.The threshold ADC value of 2.18 × 10-3 mm2/s indicated that endoscopic inflammation differed from normal intestinal segment with a sensitivity of 89.7% and a specificity of 80.3%.CONCLUSION: DWI combined with conventional MRI without bowel preparation provides a quantitative strategy to differentiate actively inflamed intestinal segments from the normal mucosa to detect UC.

Meta-analysis of Quantitative Diffusion-weighted MR Imaging in Differentiating Benign and Malignant Pancreatic Masses

There have been numerous studies done to explore the diagnostic performance of quanti- tative diffusion-weighted （DW） MR imaging to differentiate between benign and malignant pancre- atic masses. However, the results have been inconsistent. We performed a meta-analysis to investigate whether DW-MR imaging can differentiate between these two diseases. Databases including MEDLINE, EMBASE and Cochrane Library were utilized to find relevant articles published between January 2001 and January 2014. A Stata version 12.0 and a Meta-Disc version 1.4 were used to de- scribe primary results. Twelve studies with 594 patients, which fulfilled the inclusion criteria, were enrolled for the analysis. The pooled sensitivity and specificity of DW imaging was 0.91 （95% CI： 0.84, 0.95） and 0.86 （95% CI： 0.76, 0.93） respectively. The area under the curve of the summary re- ceiver operating characteristic was 0.95 （95% CI： 0.93, 0.96）. The results indicated that DW imaging might be a valuable tool for differentiating benign and malignant pancreatic masses.

Differential diagnosis of pancreatic cancer by single-shot echo-planar imaging diffusion-weighted imaging

AIM: To investigate the diagnostic ability of single-shot echo-planar imaging(EPI) diffusion-weighted imaging (DWI) to differentiate between malignant and benign pancreatic lesions. METHODS: A computerized search was performed on Pub Med, MEDLINE and EMBASE up to August 2014. Nine studies(10 sets of data) with a total of 304 malignant pancreatic lesions and 188 benign pancreatic lesions were included. The characteristics of each study included the study name, year of publication, magnetic resonance modalities used, patient population, strength of field, pulse time, repetition time, echo time(TE), maximum b factor, mean age, mean body weight, fat suppression, number of benign and malignant lesions, and true positive, true negative, false positive and false negative results. All analyses were performed using Meta-Di Sc and Stata 11.0.RESULTS: The pooled sensitivity and specificity of singleshot EPI DWI were 0.83(95%CI: 0.79-0.87) and 0.77(95%CI: 0.70-0.83), respectively. The positive likelihood ratio and negative likelihood ratio were 5.09(95%CI: 2.19-11.84) and 0.23(95%CI: 0.15-0.36), respectively. The P value for the χ2 heterogeneity for all pooled estimates was < 0.05. From the fitted summary receiver operating characteristic curve, the area under the curve and Q* index were 0.89 and 0.82, respectively. Publication bias was not present(t = 0.58, P = 0.58). Meta-regression analysis indicated that fat suppression, mean age, TE, and maximum b factor were not sources of heterogeneity(all P > 0.05). CONCLUSION: Single-shot EPI DWI is useful to differentiate between malignant and benign pancreatic lesions. Lesion size ≥ 2 cm is the limit for the diagnosis of early lesions.

Quantitative differentiation of malignant and benign thyroid nodules with multi-parameter diffusion-weighted imaging

BACKGROUND The value of conventional magnetic resonance imaging in the differential diagnosis of thyroid nodules is limited;however,the value of multi-parameter diffusion-weighted imaging(DWI)in the quantitative evaluation of thyroid nodules has not been well determined.AIM To determine the utility of multi-parametric DWI including mono-exponential,biexponential,stretched exponential,and kurtosis models for the differentiation of thyroid lesions.METHODS Seventy-nine patients(62 with benign and 17 with malignant nodules)underwent multi-b value diffusion-weighted imaging of the thyroid.Multiple DWI parameters were obtained for statistical analysis.RESULTS Good agreement was found for diffusion parameters of thyroid nodules.Malignant lesions displayed lower diffusion parameters including apparent diffusion coefficient(ADC),the true diffusion coefficient(D),the perfusion fraction(f),the distributed diffusion coefficient(DDC),the intravoxel water diffusion heterogeneity(α)and kurtosis model-derived ADC(Dapp),and higher apparent diffusional kurtosis(Kapp)than benign entities(all P<0.01),except for the pseudodiffusion coefficient(D*)(P>0.05).The area under the ROC curve(AUC)of the ADC(0 and 1000)was not significantly different from that of the ADC(0 and 2000),ADC(0 to 2000),ADC(0 to 1000),D,DDC,Dapp and Kapp(all P>0.05),but was significantly higher than the AUC of D*,f andα(all P<0.05)for differentiating benign from malignant lesions.CONCLUSION Multiple DWI parameters including ADC,D,f,DDC,α,Dapp and Kapp could discriminate benign and malignant thyroid nodules.The metrics including D,DDC,Dapp and Kapp provide additional information with similar diagnostic performance of ADC,combination of these metrics may contribute to differentiate benign and malignant thyroid nodules.The ADC calculated with higher b values may not lead to improved diagnostic performance.