Objective To review the examination techniques and the current research progress of the magnetic resonance diffusion weighted-imaging (DWI) used in liver. Methods The recent and relevant literatures about the principles and the current study situation of liver DWI were scrutinized and analyzed retrospectively. In addition, the existing problems of liver DWI were discussed. Results DWI could demonstrate the normal and abnormal structure and function through measuring the diffusion motions of water molecule in the liver. With the improving technology and better understanding of diffusion dynamics, DWI has been used for the diagnosis and differential diagnosis for hepatic diseases. Conclusion DWI as a non-invasive examine method, may provide valuable functional information for clinical diagnosis and treatment.
ObjectiveTo summarize the application of magnetic resonance imaging (MRI) in the evaluation of pancreatic exocrine function.MethodIn this paper, we reviewed and summarized the related literatures about the application of MRI in the field of pancreatic exocrine function evaluation in recent years.ResultsA variety of MRI techniques could be used to detect the pancreatic exocrine function. In addition to conventional MRI techniques, there were also MRI stimulated by pancreatic secretions, cine (dynamic) cholangiopancreatography based on space selective reverse recovery pulse, and so on.ConclusionThe new MRI techniques have potential for semi-quantitative and quantitative evaluation of pancreatic exocrine function.
ObjectiveTo investigate the utility of stretched exponential model diffusion-weighted imaging (DWI) for diagnosing of advanced liver fibrosis.MethodsThe patients with chronic liver disease complicated with vary degrees of fibrosis confirmed by pathological examination underwent DWI using different b-values (0, 50, 600 s/mm2) at the First Affiliated Hospital of Chengdu Medical College from June 2015 to February 2020 were collected. In addition, patients who underwent upper abdominal MRI examination in the same hospital at the same time and had no liver disease or disease affecting liver function were collected as a control group. The apparent diffusion coefficient (ADC) was calculated by using a mono-exponential model. The distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) were calculated by using a stretched exponential model. The fibrosis stage was evaluated by using the Metavir scoring system. The ADC, DDC, and α among different fibrosis groups were compared. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic efficacy of these three quantitative parameters for advanced liver fibrosis.ResultsA total of 42 patients with chronic liver disease were collected in this study, including mild liver fibrosis (S1–S2, n=16) and advanced liver fibrosi (≥S3, n=24); 15 patients in the control group. The values of ADC, DDC, and α of the patients with mild liver fibrosis and advanced liver fibrosis were significantly lower than those of the control patients (P<0.05). The area under the ROC curve of ADC, DCC, and α in diagnosing liver fibrosis (≥S1) was 0.915, 0.974, and 0.835, respectively, which in diagnosing advanced liver fibrosis (≥S3) was 0.744, 0.869, and 0.758, respectively. However, further the area under ROC curve among these three metrics had no statistical differences (P>0.05).ConclusionDDC based on stretched exponential model is valuable for diagnosis of advanced liver fibrosis.
ObjectiveTo explore the value of magnetic resonance diffusion weighted imaging (DWI) in preoperative Bismuth-Corlette classification of hilar cholangiocarcinoma (HCCA). MethodsA total of 53 HCCA patients confirmed by postoperative pathology were retrospectively included. The accuracy of two sequence combinations, namely dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) + magnetic resonance cholangiopancreatography (MRCP) and DCE-MRI + MRCP + DWI, in evaluating the longitudinally involved bile duct segments and Bismuth-Corlette classification of HCCA was compared. Additionally, the correlation between apparent diffusion coefficient (ADC) values and tumor Bismuth-Corlette classification as well as degree of differentiation was analyzed. ResultsThere were 318 bile duct segments in 53 HCCA patients. The accuracy rate of DCE-MRI + MRCP was 93.7% (298/318), the sensitivity was 91.5% (161/176), and the specificity was 96.5% (137/142); The accuracy rate of DCE-MRI + MRCP + DWI was 96.5% (307/318), the sensitivity was 96.0% (169/176), and the specificity was 97.2% (138/142). The accuracy of DCE-MRI + MRCP + DWI was higher than that of DCE-MRI + MRCP, with a statistically significant difference (χ2=275.902, P<0.001). Receiver operating characteristic (ROC) curve analysis showed that the area under the ROC curve (AUC) of DCE-MRI + MRCP + DWI was 0.966 [95%CI (0.940, 0.983), P＜0.000 1], and its diagnostic efficacy was superior to that of DCE-MRI + MRCP [AUC=0.940, 95%CI (0.908, 0.963), P＜0.000 1]. The DeLong test indicated a statistically significant difference in AUC between the two sequences (Z=2.633, P=0.008 5). The accuracy rates of preoperative Bismuth-Corlette classification of HCCA evaluated by DCE-MRI + MRCP and DCE-MRI + MRCP + DWI were 86.8% (46/53) and 94.3% (50/53), respectively. After adding the DWI sequence, the consistency between Bismuth-Corlette classification results and surgical pathological classification results (Kappa=0.922, P<0.001) was higher than that of DCE-MRI + MRCP sequence (Kappa=0.820, P<0.001), with a statistically significant difference (χ2=160.370, P<0.001). In addition, the ADC value of HCCA was negatively correlated with tumordegree of differentiation (rs=–0.524, P<0.001), but had no significant correlation with its Bismuth-Corlette classification (rs=–0.058, P=0.682). ConclusionsDCE-MRI + MRCP + DWI sequence can effectively improve the accuracy in preoperative evaluation of the involvement of bile duct segments and Bismuth-Corlette classification of HCCA, which provides guidance for precise preoperative surgical planning in clinical practice. In addition, the ADC value can provide additional information required for non-invasive preoperative prediction of the prognosis of HCCA patients.