Application of Intravoxel Incoherent Motion in Clinical Liver Imaging: A Literature Review.

Intravoxel incoherent motion (IVIM) modeling is a widely used double-exponential model for describing diffusion-weighted imaging (DWI) signal, with a slow component related to pure molecular diffusion and a fast component associated with microcirculatory perfusion, which compensates for the limitations of traditional DWI. IVIM is a noninvasive technique for obtaining liver pathological information and characterizing liver lesions, and has potential applications in the initial diagnosis and treatment monitoring of liver diseases. Recent studies have demonstrated that IVIM-derived parameters are useful for evaluating liver lesions, including nonalcoholic fatty liver disease (NAFLD), liver fibrosis and liver tumors. However, the results are not stable. Therefore, it is necessary to summarize the current applications of IVIM in liver disease research, identify existing shortcomings, and point out the future development direction. In this review, we searched for studies related to hepatic IVIM-DWI applications over the past two decades in the PubMed database. We first introduce the fundamental principles and influential factors of IVIM, and then discuss its application in NAFLD, liver fibrosis, and focal hepatic lesions. It has been found that IVIM is still unstable in ensuring the robustness and reproducibility of measurements in the assessment of liver fibrosis grade and liver tumors differentiation, due to inconsistent and substantial overlap in the range of IVIM-derived parameters for different fibrotic stages. In the end, the future direction of IVIM-DWI in the assessment of liver diseases is discussed, emphasizing the need for further research on the stability of IVIM-derived parameters, particularly perfusion-related parameters, in order to promote the clinical practice of IVIM-DWI. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Focal hepatic lesions in acid sphingomyelinase deficiency: Differential diagnosis between foamy macrophages aggregates and malignancy.

Acid sphingomyelinase deficiency (ASMD) is a rare metabolic disorder due to biallelic mutation in the SMPD1 gene. The defect leads to the accumulation of sphingomyelin within the cells of the reticulo-endothelial system, particularly in the spleen, liver, lungs, and bone marrow causing hepato-splenomegaly, lung disease and hematological abnormalities. At present, data on abdominal imaging in ASMD are limited. Here we describe the characteristics of focal liver lesions observed in a 30 years old female. During the Magnetic Resonance follow up an increase in number and size of the lesions, showing T1 hypointensity and T2 hyperintensity with contrast enhancement, was observed. Contrast enhanced ultrasound evidenced rapid wash-in and steady isoecogenicity without appreciable wash-out at 80 seconds. The main lesion was biopsied to rule out the presence of a hepatocellular carcinoma, and showed to be a benign foamy macrophages aggregate. In this report, we discuss the possible pathogenesis of focal hepatic lesions in ASMD and their differential diagnosis.

Value of shear wave elastography with maximal elasticity in differentiating benign and malignant solid focal liver lesions.

BACKGROUND: It is important to differentiate benign and malignant focal liver lesions (FLLs) accurately. Despite the wide use and acceptance of shear wave elastography (SWE), its value for assessing the elasticity of FLLs and differentiating benign and malignant FLLs is still investigational. Previous studies of SWE for FLLs used mean elasticity as the parameter to reflect the stiffness of FLLs. Considering the inhomogeneity of tumor stiffness, maximal elasticity (Emax) might be the suitable parameter to reflect the stiffness of FLLs and to differentiate malignant FLLs from benign ones. AIM: To explore the value of SWE with Emax in differential diagnosis of solid FLLs. METHODS: We included 104 solid FLLs in 95 patients and 50 healthy volunteers. All the subjects were examined using conventional ultrasound (US) and virtual touch tissue quantification(VTQ) imaging. A diagnosis of benign or malignant FLL was made using conventional US. Ten VTQ values were acquired after 10 consecutive measurements for each FLL and each normal liver, and the largest value was recorded as Emax. RESULTS: There were 56 cases of malignant FLLs and 48 cases of benign FLLs in this study. Emax of malignant FLLs (3.29 ± 0.88 m/s) was significantly higher than that of benign FLLs (1.30 ± 0.46 m/s, P < 0.01) and that of livers in healthy volunteers (1.15 ± 0.17 m/s, P < 0.01). The cut-off point of Emax was 1.945, and the area under the curve was 0.978. The sensitivity and specificity of Emax were 92.9% and 91.7%, respectively, higher (but not significantly) than those of conventional US (80.4% for sensitivity and 81.3% for specificity). Combined diagnosis of conventional US and Emax using parallel testing improved the sensitivity to 100% with specificity of 75%. CONCLUSION: SWE is a convenient and easy method to obtain accurate stiffness information of solid FLLs. Emax is useful for differential diagnosis of FLLs, especially in combination with conventional US.

Contraste hepatobiliar: diagnóstico diferencial das lesões hepáticas focais, armadilhas e outras indicações / Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications

A caracterização das lesões hepáticas focais é muito importante. A ressonância magnética é considerada o melhor método de imagem para a avaliação destas lesões, mas não permite o diagnóstico em todos os casos. Os contrastes hepatobiliares aumentam a acurácia diagnóstica da ressonância magnética e diminuem o número de lesões hepáticas indefinidas. Suas principais indicações são a diferenciação entre hiperplasia nodular focal e adenoma, caracterização de carcinoma hepatocelular em pacientes cirróticos, detecção de metástases hepáticas pequenas, avaliação da anatomia biliar e identificação de fístulas biliares pós-operatórias. A utilização dos contrastes hepatobiliares pode reduzir a necessidade de procedimentos diagnósticos invasivos e de avaliação complementar por outros exames de imagem, além de diminuir a necessidade de exames de acompanhamento.

The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions. The main indications for the method include: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up.

Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications.

The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions. The main indications for the method include: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up.

A caracterização das lesões hepáticas focais é muito importante. A ressonância magnética é considerada o melhor método de imagem para a avaliação destas lesões, mas não permite o diagnóstico em todos os casos. Os contrastes hepatobiliares aumentam a acurácia diagnóstica da ressonância magnética e diminuem o número de lesões hepáticas indefinidas. Suas principais indicações são a diferenciação entre hiperplasia nodular focal e adenoma, caracterização de carcinoma hepatocelular em pacientes cirróticos, detecção de metástases hepáticas pequenas, avaliação da anatomia biliar e identificação de fístulas biliares pós-operatórias. A utilização dos contrastes hepatobiliares pode reduzir a necessidade de procedimentos diagnósticos invasivos e de avaliação complementar por outros exames de imagem, além de diminuir a necessidade de exames de acompanhamento.

To compare the role of Gd-EOB-DTPA dynamic contrast-enhanced MRI with multi-detector row computed tomography (MDCT) in patients with focal liver lesions / 中华肝胆外科杂志

Objective To compare the role of Gd-EOB-DTPA dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with multi-detector row computed tomography (MDCT),and to determine the sensitivity,specificity and accuracy in focal hepatic lesions.Methods A retrospective analysis was conducted on 32 patients with focal hepatic lesions who had undergone MRI and MDCT examinations.These patients were divided into two groups:the CT group and the MRI group.The results were analysed using receiver operating characteristic (ROC) curves.Result There were 185 focal hepatic lesions.The sensitivity,specificity and the area under the ROC curve (AUC) were 86.5％,90.9％,0.855,respectively for the MRI group and they were significantly higher than the CT group (63.6％,54.5％,0.532).For detection of lesions ＜1 cm,the sensitivity,specificity and the area under the ROC curve (AUC) for the MRI group were 90％,86.6％,0.886,respectively,which were also significantly higher than the CT group (50.5％,45.5％,0.500).When combined with pathological findings and follow-up,the diagnostic accuracy was 40.6％ using Gd-EOB-DTPA DCE-MRI.Conclusion Gd-EOB-DTPA DCE-MRI has a higher detection rate,better accuracy and diagnostic value for focal liver lesions (＜1 cm) than MDCT.

Diagnostic Value of Contrast-Enhanced CT Patterns in Focal Hepatic Lesion / 实用放射学杂志

Objective To study the diagnostic value of contrast-enhanced CT patterns in focal hepatic lesions.Methods Contrast-enhanced CT patterns in 44 patients with focal hepatic lesions (54 foci) were retrospectively analysed.Results (1)78% of the hepatocellular carcinoma presented "rapid-filling and rapid-washout" feature.(2)All hepatic hemangioma presented "rapid-filling and slow-washout", progressive opacification from the periphery to center. (3)All cholangiocarcinoma presented "slow-filling and slow-washout" .(4)Metastatic hepatocarcinoma in 14 cases and hepatic abscesses in 5 cases were presented a enhanced ring around the lesion, metastatic hepatocarcinomas showed single ring,however, hepatic abscesses showed multi-ring. (5)Focal nodular hyperplasia in 3 cases and hepatic adenomas in 1 case presented "rapid-filling and slow-washout".Conclusion The contrast-enhanced patterns at spiral CT can fully reflect the blood supply of focal hepatic lesions, it has significant value in diagnosing focal hepatic lesions.