Value Of Magnetic Resonance Elastography Research Articles

3D MR elastography-based stiffness as a marker for predicting tumor grade and subtype in cervical cancer

BackgroundIncreasing evidence has indicated that high tissue stiffness (TS) may be a potential biomarker for evaluation of tumor aggressiveness. PurposeTo investigate the value of magnetic resonance elastography (MRE)-based quantitative parameters preoperatively predicting the tumor grade and subtype of cervical cancer (CC). Study typeRetrospective. PopulationTwenty-five histopathology-proven CC patients and 7 healthy participants. Field strength/sequence3.0T, magnetic resonance imaging (MRI) (LAVA-flex) and MRE with a three-dimensional spin-echo echo-planar imaging. AssessmentThe regions of interest (ROIs) were manually drawn by two observers in tumors to measure mean TS, storage modulus (G′), loss modulus (G″) and damping ratio (DR) values. Surgical specimens were evaluated for tumor grades and subtypes. Statistical testsIntraclass correlation coefficient (ICC) was expressed in terms of inter-observer agreements. t-test or Mann-Whitney nonparametric test was used to compare the complex modulus and apparent diffusion coefficient (ADC) values between different tumor groups. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate the diagnostic performance. ResultsThe TS of endocervical adenocarcinoma (ECA) group was significantly higher than that in squamous cell carcinoma (SCC) group (5.27 kPa vs. 3.44 kPa, P = 0.042). The TS also showed significant difference between poorly and well/moderately differentiated CC (5.21 kPa vs. 3.47 kPa, P = 0.038), CC patients and healthy participants (4.18 kPa vs. 1.99 kPa, P < 0.001). The cutoff value of TS to discriminate ECA from SCC was 4.10 kPa (AUC: 0.80), while it was 4.42 kPa to discriminate poorly from well/moderately differentiated CC (AUC: 0.83), and 2.25 kPa to distinguish normal cervix from CC (AUC: 0.88), respectively. There were no significant difference in G″, DR and ADC values between any subgroups except for comparison of healthy participants and CC patients (P = 0.001, P = 0.004, P < 0.001, respectively). Data conclusion3D MRE-assessed TS shows promise as a potential biomarker to preoperatively assess tumor grade and subtype of CC.

Correlation analysis of MR elastography and Ki-67 expression in intrahepatic cholangiocarcinoma

BackgroundIntrahepatic cholangiocarcinoma (iCCA) is an aggressive primary liver cancer with dismal outcome, high Ki-67 expression is associated with active progression and poor prognosis of iCCA, the application of MRE in the prediction of iCCA Ki-67 expression has not yet been investigated until now. We aimed to evaluate the value of magnetic resonance elastography (MRE) in assessing Ki-67 expression for iCCA.ResultsIn the whole cohort, 97 patients (57 high Ki-67 and 40 low Ki-67; 58 males, 39 females; mean age, 58.89 years, ranges 36–70 years) were included. At the multivariate analysis, tumor stiffness (odds ratio (OR) = 1.669 [95% CI: 1.307–2.131], p < 0.001) and tumor apparent diffusion coefficient (ADC) (OR = 0.030 [95% CI: 0.002, 0.476], p = 0.013) were independent significant variables associated with Ki-67. Areas under the curve of tumor stiffness for the identification of high Ki-67 were 0.796 (95% CI 0.702, 0.871). Tumor stiffness was moderately correlated with Ki-67 level (r = 0.593, p < 0.001). When both predictive variables of tumor stiffness and ADC were integrated, the best performance was achieved with area under the curve values of 0.864 (95% CI 0.780–0.926).ConclusionMRE-based tumor stiffness correlated with Ki-67 in iCCA and could be investigated as a potential prognostic biomarker. The combined model incorporating both tumor stiffness and ADC increased the predictive performance.Critical relevance statementMRE-based tumor stiffness might be a surrogate imaging biomarker to predict Ki-67 expression in intrahepatic cholangiocarcinoma patients, reflecting tumor cellular proliferation. The combined model incorporating both tumor stiffness and apparent diffusion coefficient increased the predictive performance.Key points• MRE-based tumor stiffness shows a significant correlation with Ki-67.• The combined model incorporating tumor stiffness and apparent diffusion coefficient demonstrated an optimized predictive performance for Ki-67 expression.• MRE-based tumor stiffness could be investigated as a potential prognostic biomarker for intrahepatic cholangiocarcinoma.Graphical

Magnetic resonance elastography fornoninvasive detection of liver fibrosis: is there an added value of 3D acquisition?

(1) Assess the diagnostic performance of liver 3D magnetic resonance elastography (MRE) parameters (including stiffness, storage/loss modulus and damping ratio) compared to liver stiffness measured with 2D MRE for noninvasive detection of advanced liver fibrosis (F3-F4) and cirrhosis (F4) in patients with chronic liver disease. (2) Assess the value of serum markers (FIB-4) in detecting advanced liver fibrosis and cirrhosis in the same patients. This was a single center, prospective IRB-approved cross-sectional study that included 49 patients (M/F: 23/26, mean age 50.8 y) with chronic liver disease and concomitant liver biopsy. MRE was acquired at 1.5T using a spin echo-EPI sequence. The following parameters were measured: liver stiffness using 2D MRE (LS-2D) and 3D MRE parameters (LS-3D, liver storage, loss modulus and damping ratio). The Mann-Whitney U test, ROC curve analysis, Spearman correlation and logistic regression were performed to evaluate diagnostic performance of MRE parameters and FIB-4. LS-2D and LS-3D had similar diagnostic performance for diagnosis of F3-F4, with AUCs of 0.87 and 0.88, sensitivity of 0.71 and 0.81, specificity of 0.89 for both. For diagnosis of F4, LS-2D and LS-3D had similar performance with AUCs of 0.81 for both, sensitivity of 0.75 and 0.83, and specificity of 0.84 and 0.73, respectively. Additional 3D parameters (storage modulus, loss modulus, damping ratio) had variable performance, with AUC range of 0.59-0.78 for F3-F4; and 0.52-0.70 for F4. FIB-4 had lower diagnostic performance, with AUCs of 0.66 for F3-F4, and 0.68 for F4. Our study shows no added value of 3D MRE compared to 2D MRE for detection of advanced fibrosis and cirrhosis, while FIB-4 had lower diagnostic performance.

The combined use of DTI and MR elastography for monitoring microstructural changes in the developing brain of a neurodevelopmental disorder model: Poly (I:C)-induced maternal immune-activated rats.

Early neuropathology mechanisms in neurodevelopmental disorders are partially understood because routine anatomical magnetic resonance imaging (MRI) cannot detect subtle brain microstructural changes in vivo during postnatal development. Therefore, we investigated the potential value of magnetic resonance elastography (MRE) and diffusion tensor imaging (DTI) in a rat model of neurodevelopmental disorder induced by maternal immune activation. We studied 12 offspring of mothers injected with polyriboinosinic-polyribocytidylic acid (poly (I:C), 4 mg/kg) on gestational day 15, plus 8 controls. T2-weighted anatomical MR images, MRE (800 Hz) and DTI (30 gradient directions, b = 765.8 s/mm2, 5 images, b = 0 s/mm2) were collected when the rats were 4 and 10 weeks old, and results were compared with histological analysis performed at week 10. Ventricles were ~1.4 fold larger from week 4 in poly (I:C) rats than in controls. No other morphological abnormalities were detected in poly(I:C) rats. At week 4, larger ventricles were correlated with lower external capsule fractional anisotropy and internal capsule radial diffusion (Pearson, r = -0.53, 95% confidence intervals (CI) [-0.79 to -0.12], and r = -0.45, 95% CI [-0.74 to -0.01], respectively). The mean and radial diffusion of the corpus callosum, the mean and axial diffusion of the internal capsule and the radial diffusion properties in the external capsule increased with age for poly (I:C) rats only (Sidak's comparison, P<0.05). Cortical stiffness did not increase with age in poly (I:C) rats, in contrast with controls (Sidak's comparison, P = 0.005). These temporal variations probably reflected abnormal myelin content, decreased cell density and microglia activation observed at week 10 after histological assessment. To conclude, MRE and DTI allow monitoring of abnormal brain microstructural changes in poly (I:C) rats from week 4 after birth. This suggests that both imaging techniques have the potential to be used as complementary imaging tools to routine anatomical imaging to assist with the early diagnosis of neurodevelopmental disorders and provide new insights into neuropathology.

Withdrawn: Bing-Tian Dong, Yu-Ping Chen, Guo-Rong Lyu, Hua-Ming Wang, Guo-Fu Lin and Jiong-Hui Gu; Diagnostic accuracy of two-dimensional shear wave elastography and magnetic resonance elastography for staging liver fibrosis in patients with chronic hepatitis B: A systematic review and meta-analysis.

An accurate assessment of liver fibrosis is critical for the management of chronic hepatitis B (CHB) patients. Two-dimensional shear wave elastography (2D-SWE) and magnetic resonance elastography (MRE) have recently been proposed to diagnose liver fibrosis. To determine the optimal noninvasive method for diagnosing fibrosis in CHB, we conducted a meta-analysis to compare the performance of 2D-SWE and MRE for diagnosing fibrosis in patients with CHB. Literature databases were searched until January 1st 2021. Three measures, the summary area under the receiver operating characteristic curve (AUSROC), the summary diagnostic odds ratios, and the summary sensitivities and specificities, were used to assess the performance of 2D-SWE and MRE for detecting liver fibrosis. Twenty-four studies with 5126 CHB patients were included. The summary sensitivities and specificities of 2D-SWE and MRE were 82% and 81%, 91% and 94%, respectively, for detecting significant fibrosis, 88% and 85%, 93% and 93%, respectively, for detecting advanced fibrosis, and 89% and 87%, 92% and 92%, respectively, for detecting cirrhosis. The AUSROC value of MRE (0.97) in predicting significant fibrosis was significantly higher than those of 2D-SWE (0.88, P < 0.001). The AUSROC values of 2D-SWE and MRE were 0.93 and 0.98, respectively, for the diagnosis of advanced fibrosis, and 0.94 and 0.97, respectively, for the diagnosis of cirrhosis. MRE and 2D-SWE are excellent tools for staging fibrosis in patients with CHB. MRE probably exhibit the better diagnostic accuracy in detecting significant fibrosis as compared to 2D-SWE.

Two-Step Strategy, FIB-4 Followed by Magnetic Resonance Elastography, for Detecting Advanced Fibrosis in NAFLD

A two-step strategy combining a serum marker and magnetic resonance elastography (MRE) for detecting advanced fibrosis (stage 3-4) among patients with nonalcoholic fatty liver disease (NAFLD) has been proposed, but its diagnostic accuracy has not been evaluated. In this multicenter study, we aimed to investigate the diagnostic accuracy of a two-step strategy including Fibrosis-4 (FIB-4) followed by MRE. In this multicenter study, 806 patients with biopsy-proven NAFLD who underwent contemporaneous MRE were enrolled and randomly assigned to training and validation cohorts. As a first step, patients with FIB-4 <1.3 were defined as test negative regardless of MRE. As a second step, among patients with FIB-4 ≥1.3, MRE <3.6 and ≥3.6 kPa were defined as test negative and positive. The primary outcome was the diagnostic accuracy for advanced fibrosis comparing MRE alone versus the two-step strategy. Area under the receiver characteristic curves of MRE alone and the two-step strategy were 0.840 and 0.853 in the training cohort (P= .4) and 0.867 and 0.834 in the validation cohort (P= .2), respectively, and the diagnostic accuracy was comparable between the 2 methods. In the entire cohort, negative predictive value (NPV) and positive predictive value (PPV) of MRE for advanced fibrosis were 92.2% and 73.7%, respectively, whereas NPV at the first and second step and PPV at the second step were 90.9%, 84.4%, and 77.0%, respectively. The diagnostic accuracy of the two-step strategy was comparable to MRE and could reduce cost by reducing excessive MRE. Therefore, the two-step strategy could be used as a screening method in a large population.

Diagnostic value of magnetic resonance elastography in cirrhotic portal hypertension

Diagnostic value of magnetic resonance elastography in cirrhotic portal hypertension

Staging liver fibrosis on multiparametric MRI in a rabbit model with elastography, susceptibility-weighted imaging and T1ρ imaging: a preliminary study.

Magnetic resonance elastography (MRE), susceptibility-weighted imaging (SWI), and T1ρ are three techniques for staging of liver fibrosis (LF). To assess the value of MRE, SWI, and T1ρ imaging in staging LF. Sixty rabbits were injected with 50% CCl4oil solution, whereas 20 rabbits were given normal saline. All rabbits underwent pathological examination to determine LF stages. The liver stiffness (LS), liver-to-muscle signal intensity ratio (SIR), and T1ρ values were measured from MRE, SWI, and T1ρ imaging, respectively. The number of rabbits was 14, 11, 10, 9, and 11 for F0, F1, F2, F3, and F4, respectively. LS (r = 0.91) and T1ρ (r = 0.51) positively correlated with LF stages, while negative correlation was present for SIR (r = -0.81). Among the three parameters, the LS values revealed the best diagnostic efficacy in staging LF, with an AUC value of 0.95 for ≥F1, 0.95 for ≥F2, 0.99 for ≥F3, and 0.98 for ≥F4. The combination of LS and SIR could best predict LF stages ≥F1, ≥F2, ≥F3 and ≥F4, with AUC values of 0.97, 0.98, 0.99, and 0.99, respectively, which were greater than those of the other two-paired parameters. A multiparametric analysis showed that the combination of all three parameters had AUC values of 0.97, 0.98, 1.00, and 1.00 for staging ≥F1, ≥F2, ≥F3, and ≥F4, respectively. Multiparametric MR imaging was superior to individual imaging for LF staging.

Non-Invasive Assessment of Graft Fibrosis After Living Donor Liver Transplantation: Is There Still a Role for Liver Biopsy?

Non-invasive methods have evolved as a surrogate for liver biopsy such as indirect markers (aspartate transaminase to platelet ratio index, fibro-α score), transient elastography (TE), and magnetic resonance elastography (MRE).The aim of this study is to prospectively compare the value of MRE, TE, and indirect markers in detecting and staging allograft fibrosis compared to liver biopsies in patients who have undergone living donor liver transplantation for complications related to hepatitis C virus.A total of 31 living donor liver transplantation recipients with hepatitis C virus recurrence underwent a liver biopsy, TE, and MRE within 3 months of a liver biopsy. Fibrosis was assessed according to the biopsy and staged according to Metavir criteria.There was a significant correlation between both MRE and fibro-α scores, as well as histologic classification by liver biopsy (P = .02, .002). The diagnostic accuracy of MRE and fibro-α scores in diagnosing significant fibrosis (F ≥ 3) was measured as the area under the curve (.708 and .833, respectively). Both methods showed good diagnostic performance. TE and aspartate transaminase to platelet ratio index were insignificantly correlated with the degree of fibrosis in liver biopsy (P value of .134, .535). At a cutoff value of 5.5 kPa, MRE predicted graft fibrosis (Metavir stage ≥ 3) with 71.43% sensitivity, 75% specificity, 45.5% positive predictive value, and 90% negative predictive value; at a cutoff value > 1.47, fibro-α scores predicted significant graft fibrosis (Metavir stage ≥ 3) with 85.7% sensitivity and 70.83% specificity, with a positive predictive value of 46.2% and a negative predictive value of 94.4%. These data suggest that non-invasive methods could be considered a reliable tool in assessing significant graft fibrosis post-living donor liver transplantation.

The use of magnetic resonance elastography in differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma: A preliminary study

PurposeTo assess the value of magnetic resonance elastography (MRE) in patients with autoimmune pancreatitis (AIP) and in the differentiation of AIP from pancreatic ductal adenocarcinoma (PDAC). Method and materialsThis prospective study included 14 AIP patients, 26 PDAC patients, and 14 healthy volunteers. All participants underwent pancreatic MRE (40-Hz; 3 T scanner) at enrollment, and 7 AIP patients underwent a second MRE after initiation of steroid therapy. Pancreatic stiffness values were obtained by MRE and a new logistic regression model (the calculated Rad score) was used to combine pancreatic stiffness and the distribution and shape of high-stiffness areas for differentiation of AIP and PDAC. The area under the curve (AUC) was calculated for all parameters using receiver operating characteristic (ROC) analysis. ResultsPancreatic stiffness was significantly higher (2.67 kPa [interquartile range, 2.24–3.56 kPa]) in AIP than in healthy pancreas (1.24 kPa [1.18–1.24 kPa]) and significantly lower in AIP than in PDAC (3.78 kPa [3.22–5.11 kPa]; both P < 0.05). Diffuse (n = 4 vs 1; P = 0.043) and multiple (n = 3 vs 0; P = 0.037) lesions were more common in AIP, while solitary (n = 25 vs 7; P = 0.001) and nodular lesions (n = 18 vs 2; P = 0.002) were more frequent in PDAC. Rad scores outperformed individual imaging parameters in distinguishing AIP from PDAC (AUC, 0.948 vs 0.607 to 0.782; all P < 0.05), with 84.6% specificity and 92.9% sensitivity. Pancreatic stiffness in AIP decreased significantly, from 2.66 kPa [2.29 to 3.05 kPa] to 1.55 kPa [1.43 to 1.67 kPa] (P = 0.016), during treatment. ConclusionsMRE shows promise as a quantitative imaging method for differentiating AIP from PDAC and for monitoring the treatment response in AIP.

Differentiation of pancreatic ductal adenocarcinoma from inflammatory mass: added value of magnetic resonance elastography

To examine whether incorporating magnetic resonance elastography (MRE) with contrast-enhanced computed tomography (CE-CT) or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can provide a benefit in differentiating pancreatic ductal adenocarcinoma (PDAC) from inflammatory mass (IM). Thirty patients with IM and 56 patients with PDAC confirmed by histopathology were identified retrospectively via a prospectively maintained database. All patients underwent CE-CT or DCE-MRI together with dual-frequency MRE at 40 and 60Hz. A five-point scale for likelihood of pancreatic malignancy was used by two experienced radiologists in consensus. Diagnostic accuracy of CE-CT/DCE-MRI, MRE, and their combination (modeled by logistic regression analysis) was estimated using receiver operating characteristic (ROC) analysis with a leave-one-out cross validation. Accuracies for determination of PDAC by 60-Hz MRE, 40-Hz MRE, CE-CT/DCE-MRI, and the combination of CE-CT or DCE-MRI and 60- and 40-Hz MRE, were 70.2%, 77.4%, 83.3%, 75%, and 92.9%, respectively. CE-CT or DCE-MRI combined with 40-Hz MRE significantly improved diagnostic performance versus CE-CT or DCE-MRI alone (area under the ROC curve [AUC]: 0.937 versus 0.783, p<0.01) by increasing specificity (96.9% versus 62.1%, p=0.002) without a significant loss of sensitivity (90.9% versus 94.6%, p=0.727), while combined CE-CT or DCE-MRI with 60-Hz MRE did not significantly change diagnostic performance versus CE-CT/DCE-MRI alone (AUC: 0.760 versus 0.783, p=0.697). Combined assessment by 40-Hz MRE with CE-CT/DCE-MRI may help to differentiate PDAC from IM in a relatively non-invasive fashion.

MR-guided Focused Ultrasound for Uterine Fibroids: A Preliminary Study of Relationship between the Treatment Outcomes and Factors of MR Images Including Elastography

We evaluated the value of magnetic resonance elastography (MRE) for the prediction of response to magnetic resonance-guided focused ultrasound (MRgFUS) for uterine fibroids. Eleven patients were enrolled. A fractional change of >30% in Symptoms Severity Score (SSS) was defined as a ‘substantial symptomatic improvement’ at 12 months after treatment. The fractional stiffness value reduction in the patients with a substantial improvement in SSS was significantly higher than that in those without (P = 0.0446).

Value of whole breast magnetic resonance elastography added to MRI for lesion characterization.

The purpose of this work was to assess the diagnostic value of magnetic resonance elastography (MRE) in addition to MRI to differentiate malignant from benign breast tumors, and the feasibility of performing MRE on the whole breast. MRE quantified biomechanical properties within the entire breast (50 slices) using an 11min acquisition protocol at an isotropic image acquisition resolution of 2×2×2mm3 . Fifty patients were included. Finally, 43 patients (median age 52) with a suspect breast lesion detected by mammography and/or ultrasound were examined by MRI and MRE at 1.5T. The viscoelastic parameters, i.e. elasticity (Gd ), viscosity (Gl ), the magnitude of the complex shear modulus Gd2+Gl2, and the phase angle y=2πatanGlGd, were measured via MRE and correlated with MRI Breast Imaging-Reporting and Data System (BI-RADS) score, histological type, and histological grade. Stroma component and angiogenesis were also correlated with viscoelastic properties. In the 43 lesions, Gd decreased and y increased with the MRI BI-RADS score (pGd =0.02, py =0.002), whereas (Gl ) and y were increased in malignant lesions (pGl =0.045, py =0.0004). The area under the curve increased from 0.84 for MRI BI-RADS alone to 0.92 with the MRI BI-RADS and y (AUC increase +0.08; 95% CI (-0.003; 0.16)). Lesion characterization using the y parameter increased the diagnostic accuracy. The phase angle y was found to have a significant role (p=0.01) in predicting malignancy independently of the MRI BI-RADS. Interestingly, histological analysis showed no correlation between viscoelastic parameters and percentage and type of stroma, CD34 quantification of vessels, or histological grade. The combination of MRE and MRI improves the diagnostic accuracy for breast lesions in the studied cohort. In particular, the phase angle y was found to have a significant role in predicting malignancy in addition to BI-RADS.

Magnetic resonance elastography is accurate in detecting advanced fibrosis in autoimmune hepatitis.

AIMTo assess the value of magnetic resonance elastography (MRE) in detecting advanced fibrosis/cirrhosis in autoimmune hepatitis (AIH).METHODSIn this retrospective study, 36 patients (19 treated and 17 untreated) with histologically confirmed AIH and liver biopsy performed within 3 mo of MRE were identified at a tertiary care referral center. Liver stiffness (LS) with MRE was calculated by a radiologist, and inflammation grade and fibrosis stage in liver biopsy was assessed by a pathologist in a blinded fashion. Two radiologists evaluated morphological features of cirrhosis on conventional magnetic resonance imaging (MRI). Accuracy of MRE was compared to laboratory markers and MRI for detection of advanced fibrosis/cirrhosis.RESULTSLiver fibrosis stages of 0, 1, 2, 3 and 4 were present in 4, 6, 7, 6 and 13 patients respectively. There were no significant differences in distribution of fibrosis stage and inflammation grade between treated and untreated patient groups. LS with MRE demonstrated stronger correlation with liver fibrosis stage in comparison to laboratory markers for chronic liver disease (r = 0.88 vs -0.48-0.70). A trend of decreased mean LS in treated patients compared to untreated patients was observed (3.7 kPa vs 3.84 kPa) but was not statistically significant. MRE had an accuracy/sensitivity/specificity/positive predictive value/negative predictive value of 0.97/90%/100%/100%/90% and 0.98/92.3%/96%/92.3%/96% for detection of advanced fibrosis and cirrhosis, respectively. The performance of MRE was significantly better than laboratory tests for detection of advanced fibrosis (0.97 vs 0.53-0.80, P < 0.01), and cirrhosis (0.98 vs 0.58-0.80, P < 0.01) and better than conventional MRI for diagnosis of cirrhosis (0.98 vs 0.78, P = 0.002).CONCLUSIONMRE is a promising modality for detection of advanced fibrosis and cirrhosis in patients with AIH with superior diagnostic accuracy compared to laboratory assessment and MRI.

Diagnostic value of magnetic resonance elastography for detecting and staging of hepatic fibrosis: A meta-analysis

A meta-analysis was performed to evaluate the diagnostic value of magnetic resonance elastography (MRE) in detecting and staging hepatic fibrosis. A systematic search of PubMed, EMBASE, Web of Science, and Cochrane Library Database up to October 2013 was undertaken to find studies on the evaluation of MRE in patients suspected of hepatic fibrosis. Data from the articles were analysed using Meta-disc 1.4 and Stata 12.0 software. The sensitivity, specificity, and area under the summary receiver operating characteristic (ROC) curve (AUROC) were pooled for all stages of hepatic fibrosis (F ≥ 1, F ≥ 2, F ≥ 3, and F = 4). Publication bias was assessed through the Deeks' funnel plot asymmetry tests. Thirteen studies comprising 989 patients met the inclusion criteria. The pooled sensitivity and specificity for F ≥ 1, F ≥ 2, F ≥ 3, and F = 4 were 0.87 (95% CI = 0.84-0.89) and 0.92 (95% CI = 0.87-0.96), 0.87 (95% CI = 0.84-0.90) and 0.92 (95% CI = 0.89-0.95), 0.88 (95% CI = 0.85-0.91) and 0.91 (95% CI = 0.88-0.93), 0.91 (95% CI = 0.87-0.94) and 0.92 (95% CI = 0.89-0.94), respectively. The pooled AUROC for F ≥ 1, F ≥ 2, F ≥ 3, and F = 4 were 0.9502, 0.9663, 0.9644, and 0.9768, respectively. The non-significant slope of Deeks' funnel plot asymmetry tests indicated that no significant bias was found. MRE has a high diagnostic accuracy for the quantitative detection and staging of hepatic fibrosis.

MRI-based staging of hepatic fibrosis: Comparison of intravoxel incoherent motion diffusion-weighted imaging with magnetic resonance elastography

To evaluate the use of intravoxel incoherent motion (IVIM) imaging for staging hepatic fibrosis, and compare its staging ability with that of magnetic resonance elastography (MRE). This study included 129 patients with pathologically staged liver fibrosis, and 53 patients with healthy livers. All patients underwent both MRE and IVIM imaging. Four diffusivity indices were calculated with 11 b-values; slow diffusion coefficient related to molecular diffusion (D), fast diffusion coefficient related to perfusion in micro-vessels (D*), perfusion-related diffusion fraction (f), and apparent diffusion coefficient (ADC). Receiver operating characteristic curve analysis was performed to determine the accuracy of IVIM imaging and MRE for staging hepatic fibrosis. D*, f, and ADC values decreased significantly with fibrosis stage (P < 0.0124), and liver stiffness increased (P < 0.0001). The Az value of MRE was significantly higher than that of D* for all fibrosis stages (D* vs. MRE for ≥ F1, 0.851 vs. 0.992 [P < 0.0001]; ≥ F2, 0.898 vs. 0.998 [P = 0.0003]; ≥ F3, 0.904 vs. 0.995 [P = 0.0004]; F4, 0.885 vs. 0.996 [P < 0.0001]). IVIM imaging is a useful technique for evaluating hepatic fibrosis, but MRE is better able to discriminate fibrosis stages than IVIM imaging.

The Effect of Gd-EOB-DPTA on the Stiffness Value of Magnetic Resonance Elastography in Evaluating Hepatic Fibrosis

Purpose : To evaluate the effect of gadoxetic acid on the measurement of the stiffness value of MR elastography (MRE) used to evaluate hepatic fibrosis (HF). Materials and Methods: MRE was obtained in 32 patients with clinically suspected chronic liver disease, both before and after injection of gadoxetic acid. Two independent reviewers measured the stiffness values of the liver parenchyma on elastograms. The mean liver stiffness values were compared in the pre- and post-contrast MREs using the paired t-test. Intra-rater and inter-rater correlation was assessed using the intraclass correlation coefficient (ICC). The accuracy, sensitivity, and specificity of both pre- and post-contrast MREs was evaluated for the diagnosis of significant HF ( F2) using cut off value of 3.1 kPa. Results: There were no significant differences in the stiffness values of the liver parenchyma on pre- and post-contrast MREs (p = 0.15 and 0.38 for each reader, respectively). Regarding intra-rater correlation, excellent agreement was noted on rater 1(ICC = 0.998) and rater 2 (ICC = 0.996). Excellent correlation regarding the measured stiffness values was noted on both pre- and post-contrast MREs (ICC = 0.988 for pre-contrast, ICC = 0.993 for post-contrast). The accuracy, sensitivity, and specificity of the pre- and post-contrast MREs for differentiating significant HF ( F2) from F1 were same as 71%, 60%, and 100%, respectively. Conclusion: As there was no significant difference in the stiffness measurements seen on MREs before and after administration of gadoxetic acids, it is therefore acceptable to perform MRE after contrast injection in order to evaluate HF. Index words : Chronic liver disease∙Hepatic fibrosis∙MR elastogaphy∙Gadoxetic acid∙Stiffness value

Multifrequency inversion in magnetic resonance elastography

Time-harmonic shear wave elastography is capable of measuring viscoelastic parameters in living tissue. However, finite tissue boundaries and waveguide effects give rise to wave interferences which are not accounted for by standard elasticity reconstruction methods. Furthermore, the viscoelasticity of tissue causes dispersion of the complex shear modulus, rendering the recovered moduli frequency dependent. Therefore, we here propose the use of multifrequency wave data from magnetic resonance elastography (MRE) for solving the inverse problem of viscoelasticity reconstruction by an algebraic least-squares solution based on the springpot model. Advantages of the method are twofold: (i) amplitude nulls appearing in single-frequency standing wave patterns are mitigated and (ii) the dispersion of storage and loss modulus with drive frequency is taken into account by the inversion procedure, thereby avoiding subsequent model fitting. As a result, multifrequency inversion produces fewer artifacts in the viscoelastic parameter map than standard single-frequency parameter recovery and may thus support image-based viscoelasticity measurement. The feasibility of the method is demonstrated by simulated wave data and MRE experiments on a phantom and in vivo human brain. Implemented as a clinical method, multifrequency inversion may improve the diagnostic value of time-harmonic MRE in a large variety of applications.

Magnetic resonance elastography of brain tumors: preliminary results

To investigate the potential value of magnetic resonance elastography (MRE) in evaluating the consistency of brain tumors. Six patients with known solid brain tumor underwent brain MRE studies. Consistency of brain tumors was evaluated at surgery. Correspondence of MRE evaluation with operative result was studied. The elasticity of tumors in six patients evaluated by MRE agreed with the tumor consistency given by the operative results. MRE could be used as an imaging technique for noninvasive assessment of the consistency of brain tumor in vivo.