Intravoxel incoherent motion diffusion-weighted imaging for monitoring chemotherapeutic efficacy in gastric cancer

AIM: To assess intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for monitoring early efficacy of chemotherapy in a human gastric cancer mouse model.METHODS: IVIM-DWI was performed with 12 b-values (0-800 s/mm2) in 25 human gastric cancer-bearing nude mice at baseline (day 0), and then they were randomly divided into control and 1-, 3-, 5- and 7-d treatment groups (n = 5 per group). The control group underwent longitudinal MRI scans at days 1, 3, 5 and 7, and the treatment groups underwent subsequent MRI scans after a specified 5-fluorouracil/calcium folinate treatment. Together with tumor volumes (TV), the apparent diffusion coefficient (ADC) and IVIM parameters [true water molecular diffusion coefficient (D), perfusion fraction (f) and pseudo-related diffusion coefficient (D*)] were measured. The differences in those parameters from baseline to each measurement (ΔTV%, ΔADC%, ΔD%, Δf% and ΔD*%) were calculated. After image acquisition, tumor necrosis, microvessel density (MVD) and cellular apoptosis were evaluated by hematoxylin-eosin (HE), CD31 and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining respectively, to confirm the imaging findings. Mann-Whitney test and Spearman’s correlation coefficient analysis were performed.RESULTS: The observed relative volume increase (ΔTV%) in the treatment group were significantly smaller than those in the control group at day 5 (ΔTVtreatment% = 19.63% ± 3.01% and ΔTVcontrol% = 83.60% ± 14.87%, P = 0.008) and day 7 (ΔTVtreatment% = 29.07% ± 10.01% and ΔTVcontrol% = 177.06% ± 63.00%, P = 0.008). The difference in ΔTV% between the treatment and the control groups was not significant at days 1 and 3 after a short duration of treatment. Increases in ADC in the treatment group (ΔADC%treatment, median, 30.10% ± 18.32%, 36.11% ± 21.82%, 45.22% ± 24.36%) were significantly higher compared with the control group (ΔADC%control, median, 4.98% ± 3.39%, 6.26% ± 3.08%, 9.24% ± 6.33%) at days 3, 5 and 7 (P = 0.008, P = 0.016, P = 0.008, respectively). Increases in D in the treatment group (ΔD%treatment, median 17.12% ± 8.20%, 24.16% ± 16.87%, 38.54% ± 19.36%) were higher than those in the control group (ΔD%control, median -0.13% ± 4.23%, 5.89% ± 4.56%, 5.54% ± 4.44%) at days 1, 3, and 5 (P = 0.032, P = 0.008, P = 0.016, respectively). Relative changes in f were significantly lower in the treatment group compared with the control group at days 1, 3, 5 and 7 follow-up (median, -34.13% ± 16.61% vs 1.68% ± 3.40%, P = 0.016; -50.64% ± 6.82% vs 3.01% ± 6.50%, P = 0.008; -49.93% ± 6.05% vs 0.97% ± 4.38%, P = 0.008, and -46.22% ± 7.75% vs 8.14% ± 6.75%, P = 0.008, respectively). D* in the treatment group decreased significantly compared to those in the control group at all time points (median, -32.10% ± 12.22% vs 1.85% ± 5.54%, P = 0.008; -44.14% ± 14.83% vs 2.29% ± 10.38%, P = 0.008; -59.06% ± 19.10% vs 3.86% ± 5.10%, P = 0.008 and -47.20% ± 20.48% vs 7.13% ± 9.88%, P = 0.016, respectively). Furthermore, histopathologic findings showed positive correlations with ADC and D and tumor necrosis (rs = 0.720, P < 0.001; rs = 0.522, P = 0.007, respectively). The cellular apoptosis of the tumor also showed positive correlations with ADC and D (rs = 0.626, P = 0.001; rs = 0.542, P = 0.005, respectively). Perfusion-related parameters (f and D*) were positively correlated to MVD (rs = 0.618, P = 0.001; rs = 0.538, P = 0.006, respectively), and negatively correlated to cellular apoptosis of the tumor (rs = -0.550, P = 0.004; rs = -0.692, P < 0.001, respectively).CONCLUSION: IVIM-DWI is potentially useful for predicting the early efficacy of chemotherapy in a human gastric cancer mouse model.

Liver intravoxel incoherent motion diffusion-weighted imaging for the assessment of hepatic steatosis and fibrosis in children

AIM To evaluate the correlation between intravoxel incoherent motion(IVIM) diffusion-weighted imaging(DWI) parameters and the degree of hepatic steatosis and fibrosis in children.METHODS This retrospective study was approved by the institutional review board. The children(≤ 18 years) who underwent liver IVIM DWI with 8 b-values under the suspicion of hepatic steatosis or fibrosis from February 2013 to November 2016 were included. Subjects were divided into normal, fatty liver(FAT), and fibrotic liver(FIB) groups. The slow diffusion coefficient(D), fast diffusion coefficient(D*), perfusion fraction(f), and apparent diffusion coefficient(ADC) were measured. MR proton density fat fraction(PDFF), MR elastography(MRE), and IVIM values were compared.RESULTS A total of 123 children(median age of 12 years old, range: 6-18 years) were included, with 8 in the normal group, 93 in the FAT group, and 22 in the FIB group. The D* values were lower in the FIB group compared with those of the normal(P = 0.015) and FAT(P = 0.003) groups. The f values were lower in the FIB group compared with the FAT group(P = 0.001). In multivariate analyses, PDFF value was positively correlated with f value(β = 3.194, P < 0.001), and MRE value was negatively correlated with D* value(β =-7.031, P = 0.032). The D and ADC values were not influenced by PDFF or MRE value.CONCLUSION In liver IVIM DWI with multiple b-values in children, there was a positive correlation between hepatic fat and blood volume, and a negative correlation between hepatic stiffness and endovascular blood flow velocity, while diffusion-related parameters were not affected.

Evaluation Value of Intravoxel Incoherent Motion Diffusion-Weighted Imaging on Early Efficacy of Magnetic Resonance-Guided High-Intensity Focused Ultrasound Ablation for Uterine Adenomyoma

To investigate the evaluation value of intravoxel incoherent motion diffusion-weighted imaging(IVIM-DWI)on the early efficacy of magnetic resonance-guided high-intensity focused ultrasound(MRgFUS)ablation for uterine adenomyoma.The clinical and magnetic resonance imaging(MRI)data of 36 patients with uterine adenomyoma before and after MRgFUS treatment in our hospital from January 2018 to December 2018 were retrospectively analyzed.All the 36 patients underwent MRI examination one day before operation and immediately after operation using GE Discovery MR7503.0T MRI,including conventional sequences(T1WI,T2WI,and T2 fat suppression sequences)plain scan,IVIM-DWI sequences with 9 b values,and contrast enhanced-MRI sequences.The IVIM-DWI quantitative parameters(true diffusion coefficient D,perfusion related diffusion coefficient D*,and perfusion fraction f)of double-exponential model were obtained by using GE ADW 4.7 functool,a postprocessor.SPSS 24.0 software was used to analyze the difference in parameter between the ablation and non-ablation areas of uterine adenomyoma.DWI signal in the ablation area of uterine adenomyoma was increased,and manifested as heterogeneous diffuse high signal,with low central signal and high edge signal.Values of D,D*and f in the ablation area of uterine adenomyoma were significantly lower than those in the non-ablation area,and there was statistical difference between the two(P<0.05).The areas under receiver operating characteristic(ROC)curve of D,D*and f values in the ablation area of uterine adenomyoma were 0.854,0.898 and 0.924,respectively;the optimal thresholds for the diagnosis of ablation area of uterine adenomyoma were 0.81×10−3 mm2/s,4.99×10−3 mm2/s and 0.24,respectively;the diagnostic sensitivity was 80.6%,72.2%and 94.4%,respectively;and the specificity was 91.7%,97.2%and 94.4%,respectively.IVIM-DWI has a certain clinical value in the evaluation on early efficacy of MRgFUS ablation of uterine adenomyosis.

Intravoxel incoherent motion diffusion-weighted magnetic resonance imaging for predicting histological grade of hepatocellular carcinoma:Comparison with conventional diffusion-weighted imaging

AIM To compare intravoxel incoherent motion(IVIM)-derived parameters with conventional diffusion-weighted imaging(DWI) parameters in predicting the histological grade of hepatocellular carcinoma(h CC) and to evaluate the correlation between the parameters and the histological grades.METHODS A retrospective study was performed. Sixty-two patients with surgically confirmed h CCs underwent diffusion-weighted magnetic resonance imaging with twelve b values(10-1200 s/mm^2). The apparent diffusion coefficient(ADC), pure diffusion coefficient(D), pseudo-diffusion coefficient(D*), and perfusion fraction(f) were calculated by two radiologists. The IVIM and conventional DWI parameters were compared among the different grades by using analysis of variance(ANOVA) and the Kruskal-Wallis test. Receiver operating characteristic(ROC) analysis was performed to evaluate the diagnostic efficiency of distinguishing between low-grade(grade 1, G1) and high-grade(grades 2 and 3, G2 and G3) hC C. The correlation between the parameters and the histological grades was assessed by using the Spearman correlation test. Bland-Altman analysis was used to evaluate the reproducibility of the two radiologists' measurements.RESULTS The differences in the ADC and D values among the groups with G1, G2, and G3 histological grades of HCCs were statistically significant(P < 0.001). The D* and f values had no significant differences among the different histological grades of h CC(P > 0.05). The ROC analyses demonstrated that the D and ADC values had better diagnostic performance in differentiating the low-grade h CC from the high-grade h CC, with areas under the curve(AUCs) of 0.909 and 0.843, respectively, measured by radiologist 1 and of 0.911 and 0.852, respectively, measured by radiologist 2. The following significant correlations were obtained between the ADC, D, and D~* values and the histological grades: r =-0.619(P < 0.001), r =-0.628(P < 0.001), and r =-0.299(P = 0.018), respectively, as measured by radiologist 1; r =-0.622(P < 0.001), r =-0.633(P < 0.001), and r =-0.303(P = 0.017), respectively, as measured by radiologist 2. The intra-class correlation coefficient(ICC) values between the two observers were 0.996 for ADC, 0.997 for D, 0.996 for D*, and 0.992 for f values, which indicated excellent interobserver agreement in the measurements between the two observers.CONCLUSION The IVIM-derived D and ADC values show better diagnostic performance in differentiating high-grade hC C from low-grade hC C, and there is a moderate to good correlation between the ADC and D values and the histological grades.

Intravoxel Incoherent Motion Diffusion Weighted Imaging for the Therapeutic Response of Transarterial Chemoembolization for Hepatocellular Carcinoma

Background: Intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) can not only observe the diffusion of tissue water molecules but also reflect the blood perfusion information of tissue microcirculation. IVIM-DWI has been applied in many clinical areas. However, few studies have addressed the use of IVIM-DWI for the evaluation of transarterial chemoembolization (TACE) response in hepatocellular carcinoma (HCC) patients. Objectives: The purpose of the present study was to explore the role of IVIM-DWI for the therapeutic response of TACE for HCC. Materials and Methods: Twenty patients underwent IVIM-DWI scan on a 3.0T magnetic resonance imaging instrument 1 - 3 days before and 30 to 40 days after TACE. The values of IVIM-DWI parameters, including standard apparent diffusion coefficient (ADC), pure diffusion coefficient (Dslow), pseudo-diffusion coefficient (Dfast) and perfusion fraction (f) were measured. The values of IVIM-DWI parameters before and after TACE were compared using paired t tests. The values between responsive and non-responsive groups were compared using independent-samples t test. P 0.05 indicated statistical significance. Results: After TACE, the ADC and Dslow values in the tumors increased significantly, and the values of Dfast decreased significantly, while the values of f value did not change obviously. The ADC values in responsive group were remarkably higher than those in non-responsive group, the Dfast values in responsive group were significantly lower than those in non-responsive group, but the values of Dslow and f between the two groups were not different significantly. Conclusions: IVIM-DWI parameters can be used as potential markers for the therapeutic response of TACE for HCC.

Intravoxel incoherent motion magnetic resonance imaging for diagnosis of cervical cancer and evaluation of response of uterine cervical cancer to radiochemotherapy: A pilot study

Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uterine cervical cancer to radiochemotherapy(CRT).Methods This prospective study was approved by the institutional review board, and informed consent was obtained from all patients. A total of 23 patients with primary cervical cancer who were undergoing CRT and 16 age-matched healthy subjects were prospectively recruited for IVIM(b = 0–800 s/mm2) and standard pelvic MRI. Bi-exponential analysis was performed to derive f(perfusion fraction), D*(pseudo-diffusion coefficient), and D(true molecular diffusion coefficient) in cervical cancer(n = 23) and the normal cervix(n = 16). The apparent diffusion coefficient(standard ADC) was calculated. The independent-samples t-test and paired-samples t-test were used for comparisons.Results Pre-treatment cervical cancer had the lowest standard ADC(1.15 ± 0.13 × 10-3 mm2/s) and D(0.89 ± 0.10 × 10-3 mm2/s) values, and these were significantly different from the normal cervix and posttreatment cervical cancer(P = 0.00). The f(16.67 ± 5.85%) was lowest in pre-treatment cervical cancer and was significantly different from the normal cervix and post-treatment cervical cancer(p = 0.012 and 0.00, respectively). No difference was observed in D*.Conclusion IVIM is potentially promising for differentiating between the normal cervix and cervical cancer because pre-treated cervical cancer has low perfusion and diffusion IVIM characteristics. Further, the standard ADC, D, and f of cervical cancer showed a tendency to normalize after CRT; thus, IVIM may be useful for monitoring the response to CRT in cervical cancer.

Value of multiple models of diffusion-weighted imaging to predict hepatic lymph node metastases in colorectal liver metastases patients

BACKGROUND About 10%-31% of colorectal liver metastases(CRLM)patients would concomitantly show hepatic lymph node metastases(LNM),which was considered as sign of poor biological behavior and a relative contraindication for liver resection.Up to now,there’s still lack of reliable preoperative methods to assess the status of hepatic lymph nodes in patients with CRLM,except for pathology examination of lymph node after resection.AIM To compare the ability of mono-exponential,bi-exponential,and stretchedexponential diffusion-weighted imaging(DWI)models in distinguishing between benign and malignant hepatic lymph nodes in patients with CRLM who received neoadjuvant chemotherapy prior to surgery.METHODS In this retrospective study,97 CRLM patients with pathologically confirmed hepatic lymph node status underwent magnetic resonance imaging,including DWI with ten b values before and after chemotherapy.Various parameters,such as the apparent diffusion coefficient from the mono-exponential model,and the true diffusion coefficient,the pseudo-diffusion coefficient,and the perfusion fraction derived from the intravoxel incoherent motion model,along with distributed diffusion coefficient(DDC)andαfrom the stretched-exponential model(SEM),were measured.The parameters before and after chemotherapy were compared between positive and negative hepatic lymph node groups.A nomogram was constructed to predict the hepatic lymph node status.The reliability and agreement of the measurements were assessed using the coefficient of variation and intraclass correlation coefficient.RESULTS Multivariate analysis revealed that the pre-treatment DDC value and the short diameter of the largest lymph node after treatment were independent predictors of metastatic hepatic lymph nodes.A nomogram combining these two factors demonstrated excellent performance in distinguishing between benign and malignant lymph nodes in CRLM patients,with an area under the curve of 0.873.Furthermore,parameters from SEM showed substantial repeatability.CONCLUSION The developed nomogram,incorporating the pre-treatment DDC and the short axis of the largest lymph node,can be used to predict the presence of hepatic LNM in CRLM patients undergoing chemotherapy before surgery.This nomogram was proven to be more valuable,exhibiting superior diagnostic performance compared to quantitative parameters derived from multiple b values of DWI.The nomogram can serve as a preoperative assessment tool for determining the status of hepatic lymph nodes and aiding in the decision-making process for surgical treatment in CRLM patients.

Application Progress of Intravoxel Incoherent Motion Diffusion Weighted Magnetic Resonance Imaging in Pancreatic Cancer

Intravoxel incoherent motion imaging (IVIM), on the traditional diffusion weighted imaging (DWI) technology, uses the biexponential model and adopts the multi-b-value analysis to obtain the perfusion information of water molecule diffusion and microcirculation without the use of contrast agent. It is more and more used in pancreatic diseases, which is of great significance for the diagnosis and identification of pancreatic cancer. This article will review the principles of IVIM imaging and its application in pancreatic diseases, especially in pancreatic cancer diagnosis, the prediction of pathological grade of pancreatic ductal adenocarcinoma, the judgment of lymph node metastasis, and differentiation of pathological classification.

Reproducibility study of intravoxel incoherent motion and apparent diffusion coefficient parameters in normal pancreas

BACKGROUND The consistency of pancreatic apparent diffusion coefficient(ADC)values and intravoxel incoherent motion(IVIM)parameter values across different magnetic resonance imaging(MRI)devices significantly impacts the patient’s diagnosis and treatment.AIM To explore consistency in image quality,ADC values,and IVIM parameter values among different MRI devices in pancreatic examinations.METHODS This retrospective study was approved by the local ethics committee,and informed consent was obtained from all participants.In total,22 healthy volunteers(10 males and 12 females)aged 24-61 years(mean,28.9±2.3 years)underwent pancreatic diffusion-weighted imaging using 3.0T MRI equipment from three vendors.Two independent observers subjectively scored image quality and measured the pancreas’s overall ADC values and signal-to-noise ratios(SNRs).Subsequently,regions of interest(ROIs)were delineated for the IVIM parameters(true diffusion coefficient,pseudo-diffusion coefficient,and perfusion fraction)using post-processing software.These ROIs were on the head,body,and tail of the pancrease.The subjective image ratings were assessed using the kappa consistency test.Intraclass correlation coefficients(ICCs)and mixed linear models were used to evaluate each device’s quantitative parameter values.Finally,a pairwise analysis of IVIM parameter values across each device was performed using Bland-Altman plots.RESULTS The Kappa value for the subjective ratings of the different observers was 0.776(P<0.05).The ICC values for interobserver and intra-observer agreements for the quantitative parameters were 0.803[95% confidence interval(CI):0.684-0.880]and 0.883(95%CI:0.760-0.945),respectively(P<0.05).The ICCs for the SNR between different devices was comparable(P>0.05),and the ICCs for the ADC values from different devices were 0.870,0.707,and 0.808,respectively(P<0.05).Notably,only a few statistically significant inter-device agreements were observed for different IVIM parameters,and among those,the ICC values were generally low.The mixed linear model results indicated differences(P<0.05)in the f-value for the pancreas head,D-value for the pancreas body,and D-value for the pancreas tail obtained using different MRI machines.The Bland-Altman plots showed significant variability at some data points.CONCLUSION ADC values are consistent among different devices,but the IVIM parameters’repeatability is moderate.Therefore,the variability in the IVIM parameter values may be associated with using different MRI machines.Thus,caution should be exercised when using IVIM parameter values to assess the pancreas.

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.

Value of intravoxel incoherent motion in detecting and staging liver fibrosis: A meta-analysis

BACKGROUND Liver fibrosis(LF) is a common pathological feature of all chronic liver diseases.With the accumulation of extracellular matrix in the fibrotic liver, true molecular water diffusion and perfusion-related diffusion are restricted. Intravoxel incoherent motion(IVIM) can capture the information on tissue diffusivity and microcapillary perfusion separately and reflect the fibrotic severity with diffusion coefficients.AIM To investigate the diagnostic performance of IVIM in detecting and staging LF with histology as a reference standard.METHODS A comprehensive literature search was conducted to identify studies on the diagnostic accuracy of IVIM for assessment of histologically proven LF. The stages of LF were classified as F0(no fibrosis), F1(portal fibrosis without septa),F2(periportal fibrosis with few septa), F3(septal fibrosis), and F4(cirrhosis)according to histopathological findings. Data were extracted to calculate the pooled sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio, as well as the area under the summary receiver operating characteristic curve(AUC) in each group.RESULTS A total of 12 studies with 923 subjects were included in this meta-analysis with 5 studies(n = 465) for LF ≥ F1, 9 studies(n = 757) for LF ≥ F2, 4 studies(n = 413) for LF ≥ F3, and 6 studies(n = 562) for LF = F4. The pooled sensitivity and specificity were estimated to be 0.78(95% confidence interval: 0.73-0.82) and 0.81(0.74-0.86)for LF ≥ F1 detection with IVIM;0.82(0.79-0.86) and 0.80(0.75-0.84) for staging F2 fibrosis;0.85(0.79-0.90) and 0.83(0.77-0.87) for staging F3 fibrosis, and 0.90(0.84-0.94) and 0.75(0.70-0.79) for detecting F4 cirrhosis, respectively. The AUCs for LF≥ F1, F2, F3, F4 detection were 0.862(0.811-0.914), 0.883(0.856-0.909), 0.886(0.865-0.907), and 0.899(0.866-0.932), respectively. Moderate to substantial heterogeneity was observed with inconsistency index(I2) ranging from 0% to 77.9%. No publication bias was detected.CONCLUSION IVIM is a noninvasive tool with good diagnostic performance in detecting and staging LF. Optimized and standardized IVIM protocols are needed to further improve its diagnostic accuracy in clinical practice.

Assessing the Early Response of Advanced Cervical Cancer to Neoadjuvant Chemotherapy Using Intravoxel Incoherent Motion Diffusion-weighted Magnetic Resonance Imaging： A Pilot Study

Background： Diffusion-weighted imaging （DWI） with the intravoxel incoherent motion （IVIM） model has shown promising results for providing both diffusion and perfusion intbrmation in cervical cancer; however, its use to predict and monitor the efficacy ofneoadjuvant chemotherapy （NACT） in cervical cancer is relatively rare. The study aimed to evaluate the use of DWl with 1VIM and monoexponential models to predict and monitor the efficacy of NACT in cervical cancer. Methods： Forty-two patients with primary cervical cancer underwent magnetic resonance exams at 3 time points （pre-NACT, 3 weeks after the first NACT cycle, and 3 weeks after the second NACT cycle）. The response to treatment was determined according to the response evaluation criteria in solid tumors 3 weeks after the second NACT treatment, and the subjects were classified as two groups： responders and nonresponders groups. The apparent diffusion coefficient （ADC）, true diffusion coefficient （D）, perfusion-related pseudo-diffusion coefficient （D＊）, and perfusion fraction （f） values were determined. The differences in IVlM-derived variables and ADC between the different groups at the different time points were calculated using an independent samples t-test. Results： The D and ADC values were all significantly higher for the responders than tbr the nonresponders at all 3 time points, but no significant differences were observed in the D＊ and fvalues. An analysis of the receiver operating characteristic （ROC） curves indicated that a D value threshold 〈0.93 × 10 3 mm2/s and an ADC threshold 〈1.11× 10 3 mm2/s could differentiate responders from nonresponders at pre-NACT time point, yielding area under the curve （AUC） of which were 0.771 and 0.806, respectively. The ROC indicated that the AUCs of D and ADC at the 3 weeks after the first NACT cycle and 3 weeks after the second NACT cycle were 0.823, 0.763, and 0.787, 0.794, respectively. The AUC values of D and ADC at these 3 time points were not significantly different （P = 0.641, 0.512, and 0.547, respectively）. Conclusions： D and ADC values may be useful for predicting and monitoring the efficacy of NACT in cervical cancer. An IVIM model may be equal to monoexponential model in predicting and monitoring the efficacy of NACT in cervical cancer.

Initial study of biexponential model of intravoxel incoherent motion magnetic resonance imaging in evaluation of the liver fibrosis

Background The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging.Intravoxel incoherent motion （IVIM） can be used to investigate both diffusion and perfusion changes in tissues.This study was designed to determine the value of IVIM in the diagnosis and staging of liver fibrosis.Methods IVIM examinations were performed on a GE 3.0T MR scanner in 25 patients with liver fibrosis and 25 healthy volunteers as the control group.Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of F0-4.The standard ADC values and the values of a biexponential model （slow ADC （Dslow）,fast ADC （Dfast） and fraction of fast ADC （FF）） were measured in three liver regions per person.The mean standard ADC values,Dslow values,Dfast values and FF values from the study group were compared among the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Receiver Operating Characteristic （ROC） curves and independent-samples t-tests were used to calculate the mean standard ADC values,Dslow values,Dfast values and FF values from the study group and the control group.Spearman rho correlation analysis was used for the stage of liver fibrosis.The liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 were compared.Results Among the liver fibrosis,there was no significant difference in the mean standard ADC values,Dslow values,Dfast values,and FF values obtained from the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Using ROC analysis,the Area Under the Curve （AUC） values of standard ADC,Dslow,Dfast,FF were all between 0.7 to 0.9.The mean standard ADC values,Dslow values,Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group （P ＜0.05）.As the stage of the fibrosis increased,the values decreased by Spearman rho correlation analysis.The mean values （standard ADC,Dslow,Dfast,and FF） of liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 showed significant differences （P＜0.05）.Conclusions IVIM can reflect the conditions of perfusion and diffusion in liver fibrosis and thus distinguish between normal liver and liver fibrosis.The IVIM technique may serve as a valuable tool for detecting and characterizing liver fibrosis,and monitoring its progression in a noninvasive manner.

Advanced imaging techniques in the therapeutic response of transarterial chemoembolization for hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is one of the major causes of morbidity and mortality in patients with chronic liver disease. Transarterial chemoembolization(TACE) can significantly improve the survival rate of patients with HCC and is the first treatment choice for patients who are not suitable for surgical resections. The evaluation of the response to TACE treatment affects not only the assessment of the therapy efficacy but also the development of the next step in the treatment plan. The use of imaging to examine changes in tumor volume to assess the response of solid tumors to treatment has been controversial. In recent years, the emergence of new imaging technology has made it possible to observe the response of tumors to treatment prior to any morphological changes. In this article, the advances in studies reporting the use of computed tomography perfusion imaging, diffusionweighted magnetic resonance imaging(MRI), intravoxel incoherent motion, diffusion kurtosis imaging, magnetic resonance spectroscopy, magnetic resonance perfusionweighted imaging, blood oxygen level-dependent MRI, positron emission tomography(PET)/computed tomography and PET/MRI to assess the TACE treatment response are reviewed.

Advances in the imaging of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms comprise a heterogeneous group of tumors that differ in their pathogenesis,hormonal syndromes produced,biological behavior and consequently,in their requirement for and/or response to specific chemotherapeutic agents and molecular targeted therapies.Various imaging techniques are available for functional and morphological evaluation of these neoplasms and the selection of investigations performed in each patient should be customized to the clinical question.Also,with the increased availability of cross sectional imaging,these neoplasms are increasingly being detected incidentally in routine radiology practice.This article is a review of the various imaging modalities currently used in the evaluation of neuroendocrine neoplasms,along with a discussion of the role of advanced imaging techniques and a glimpse into the newer imaging horizons,mostly in the research stage.

体素内不相干运动直方图参数预测直肠癌神经周围浸润

目的观察体素内不相干运动(IVIM)直方图参数预测直肠癌神经周围浸润(PNI)的价值。方法回顾性分析55例直肠癌患者,根据有无PNI将其分为阳性组(n=23)与阴性组(n=32);基于MR IVIM图像分别获取表观扩散系数(ADC)、灌注分数(f)、真实扩散系数(D)及伪扩散系数(D^(*))直方图参数,包括均值(mean)、偏度(skewness)、峰度(kurtosis)、熵(entropy),以及第25、50、75百分位数(25th、50th、75th),并进行组间比较。将组间差异有统计学意义的参数纳入二元逐步logistic回归分析,筛选预测直肠癌PNI状态的独立因素,构建联合参数模型;绘制受试者工作特征曲线,计算曲线下面积(AUC),评估各IVIM直方图参数及联合参数模型预测直肠癌PNI的效能。结果阳性组ADC_(mean)、ADC_(25th)、ADC_(50th)、ADC_(75th)、f_(mean)、f_(25th)、f_(50th)、f_(75th)及D_(entropy)^(*)均低于阴性组(P均<0.05);以上述参数预测直肠癌PNI阳性的AUC分别为0.693、0.665、0.701、0.675、0.831、0.847、0.835、0.722及0.785。基于f_(25th)及D_(entropy)^(*)构建的联合参数模型预测直肠癌PNI阳性的敏感度、特异度及AUC分别为95.65%、65.63%及0.897。结论利用IVIM直方图参数可有效预测直肠癌PNI。

基于体素内不相干运动扩散加权成像的虚拟磁共振弹性成像在髌下脂肪垫中的可重复性分析

目的探讨基于体素内不相干运动扩散加权成像(intravoxel incoherent motion diffusion weighted imaging,IVIM-DWI)的虚拟磁共振弹性成像(virtual magnetic resonance elastography,vMRE)测量髌下脂肪垫(infrapatellar fat pad,IPFP)硬度的可重复性。材料与方法共50名受试者接受了两次使用10个b值的IVIM-DWI检查,检查间隔为30~60 min,采用18通道膝关节线圈。从两组不同的b值(200~800 s/mm^(2)和200~1500 s/mm^(2))中计算出移位表观扩散系数(shift apparent diffusion coefficient,sADC),随后转换为基于IVIM-DWI的虚拟剪切模量(μdiff_800和μdiff_1500)。两名观察者独立地在v MRE硬度图上勾勒出整个IPFP的感兴趣区(region of interest,ROI),以获得μdiff的平均值和标准差(standard deviation,SD)。使用组内相关系数(intra-class correlation coefficient,ICC)、变异系数(coefficient of variation,CoV)和Bland-Altman一致性界限(limits of agreement,LoA)评估短期重测可重复性、观察者内和观察者间一致性。结果μdiff_1500的平均值和SD值的观察者内和观察者间一致性优异(ICC≥0.90,P<0.001),SD值观察者内Co V>10%。μdiff_800平均值的观察者内和观察者间ICC分别为0.926和0.910(P<0.001),而μdiff_800的SD值的ICC分别为0.841和0.855(P<0.001),所有Co V>10%。与μdiff_800相比(ICC=0.886;Co V=13.7%),μdiff_1500的平均值重测可重复性优异(ICC=0.932;Co V=7.5%)。μdiff_1500的两次扫描间的平均偏差及SD为-0.01(0.37),而μdiff_800的两次扫描间的平均偏差及SD为0.05(0.79);μdiff_1500的95%LoA为-0.88~0.87,而μdiff_800的95%LoA为-0.63~0.73。结论基于IVIM-DWI的v MRE在评估IPFP组织弹性方面具有显著的潜力,b值组合为200~1500 s/mm^(2)所拟合的虚拟弹性值具有更好的观察者内、观察者间一致性和短期重测可重复性。

肿瘤及直肠系膜IVIM参数预测直肠癌同时性肝转移的价值研究

目的通过体素内不相干运动(intravoxel incoherent motion,IVIM)研究肿瘤及直肠系膜对直肠癌同时性肝转移(synchronous rectal liver metastasis,SRLM)的预测价值。材料与方法回顾性分析经病理确诊为直肠癌的112例患者资料。其中42例为SRLM,将患者分为SRLM组(n=42)和非SRLM组(n=70)。在肿瘤最大层面勾画3个感兴趣区(region of interest,ROI),分别位于肿瘤、近肿瘤区直肠系膜(ROI距肿瘤<5 mm)和远肿瘤区直肠系膜(ROI距肿瘤>10 mm),测量IVIM参数表观扩散系数(apparent diffusion coefficient,ADC)、纯扩散系数(pure diffusion coefficient,D)、灌注相关扩散系数(pseudo-diffusion coefficient,D*)、灌注分数(perfusion fraction,f)。采用Mann-Whitney U检验和Wilcoxon检验分别比较两组间和各组内参数差异是否有统计学意义,并采用受试者工作特征(receive operating characteristic,ROC)曲线评价组间差异有统计学意义参数的预测效能。结果与非SRLM组相比,SRLM组远肿瘤区ADC、D、f增高(P<0.001),近肿瘤区D、f增高(P<0.05),肿瘤参数差异均无统计学意义(P>0.05)。组内比较后两组远肿瘤区ADC均低于对应近肿瘤区参数和肿瘤参数(P<0.05),D均低于对应近肿瘤区参数和肿瘤参数(P<0.001),但近肿瘤区ADC、D与对应肿瘤参数差异无统计学意义(P>0.05)。远肿瘤区f虽低于近肿瘤区f,但在SRLM组中差异无统计学意义(P>0.05)。远肿瘤区ADC、D、f预测SRLM的曲线下面积(area under the curve,AUC)分别为0.769(95%CI:0.675~0.862)、0.745(95%CI:0.644~0.845)、0.733(95%CI:0.635~0.831)。结论远肿瘤区直肠系膜IVIM参数ADC、f、D,可作为预测发生SRLM的影像学指标,对及时明确SRLM、发现隐匿性和高风险肝转移患者有重要的临床意义。

基于扩散加权成像及MRI对四肢软组织肿瘤的诊断价值

目的 探讨基于扩散加权成像及MRI对四肢软组织肿瘤(soft tissue tumors,STTs)的诊断价值。方法 选取本院经病理证实的四肢STTs患者74例,其中良性46例(良性组)、恶性28例(恶性组),均行常规MRI、DWI、IVIM及DKI扫描,分析两组常规MRI检查征象及诸参数差异,包括表观扩散系数(ADC)、真实扩散系数(D)、灌注相关扩散系数(D~*)、灌注分数(f)、平均扩散峰度值(MK)和平均扩散率(MD);运用ROC曲线分析其诊断效能。结果 恶性组肿瘤边界多不清且呈浸润性生长,以团块状为主,瘤周水肿、筋膜尾征多见,50.0%瘤内可见分隔,两组间差异有统计学意义(P<0.05)。恶性组ADC、D和MD值小于良性组,而MK值高于良性组,差异具有统计学意义(P<0.05)。D~*和f值两组差异无统计学意义(P>0.05)。ADC、D、MD、MK值在鉴别四肢STTs良恶性方面均具有一定诊断效能:AUC≥0.688,敏感度≥63.0%,特异度≥67.9%,准确度≥64.9%,其中MD值的诊断效能、特异度最高。ADC+D+MD+MK联合后,AUC为0.887,诊断效能均高于单一参数(Z=1.978~3.101;P<0.05),敏感度为76.1%,特异度为92.9%,准确度78.4%。结论 基于扩散加权成像及MRI对四肢STTs良恶性有较好的判断价值,值得临床推广。

动态增强磁共振联合体素内不相干运动成像对三阴性乳腺癌的诊断价值

目的 探讨动态增强磁共振成像(DCE-MRI)联合体素内不相干运动(IVIM)对三阴性(TNBC)及非三阴性乳腺癌的鉴别诊断价值。方法 回顾性分析本院经病理证实的乳腺癌患者180例,TNBC组49例,非TNBC组131例,所有患者均行DCE-MRI及IVIM及检查。分析两组间的临床病理资料、常规MRI征象和IVIM、 DCE-MRI模型诸定量参数。结果 TNBC组的病灶不规则形较非TNBC组少见,强化多不均匀,环形强化占比较大,两组间差异有统计学意义(P=0.001,P=0.007)。TNBC组的Ve值小于非TNBC组(P<0.001),呈低度负相关(r=-0.439,P<0.001);TNBC组的D、f、K_(ep)值高于非TNBC组(P=0.002~0.016),呈低度正相关(r=0.186~0.257,P<0.05)。D^(*)、K^(trans)值在两组间差异不具有统计学差异(P>0.05)。D≥0.86×10^(-3)mm^(2)/s、f≥38.1%、K_(ep)≥0.359/min、V_(e)≤0.589为鉴别TNBC和非TNBC的独立影响因素,其中Ve值的AUC为0.784,大于其他定量参数(Z=2.201~2.752,P=0.006~0.028)。DC E-MRI模型AUC为0.817,大于IVIM模型(AUC=0.657)和常规MRI模型(AUC=0.689),差异具有统计学意义(Z=2.657;P=0.008;Z=2.516,P=0.012)。联合DCE-MRI、IVIM模型,AUC为0.862,诊断效能均高于单一模型(Z=2.194~4.649,P<0.05),敏感度为83.7%,特异度为74.8%,准确度为80.0%。结论 DCE-MRI、IVIM模型可用于TNBC的诊断,其中DCE-MRI模型的Ve值诊断效能最高,IVIM联合DC E-M RI模型对鉴别TN BC及非TN BC的诊断效能优于单一模型。