Liver fibrosis detection and staging: a comparative study of T1ρ MR imaging and 2D real-time shear-wave elastography.

PURPOSE: To compare the results of T1ρ MR imaging and 2D real-time shear-wave elastography (SWE) for liver fibrosis detection and staging. METHODS: Twenty-nine rabbit models of CCl4-induced liver fibrosis were established and six untreated rabbits served as controls. T1ρ MR imaging and 2D real-time SWE examination were performed at 2, 4, 6, 8, 10, and 12 weeks. T1ρ values and liver stiffness (LS) values were measured. Fibrosis was staged according to the METAVIR scoring system. Correlation test was performed among T1ρ values, LS values, and fibrosis stage. Receiver operating characteristic (ROC) analysis was performed for assessing diagnostic performance of T1ρ and SWE in detection of no fibrosis (F0), substantial fibrosis (≥ F2), severe fibrosis (≥ F3), and cirrhosis (F4). RESULTS: There was moderate positive correlation between fibrosis stage and T1ρ values (r = 0.566; 95% CI 0.291-0.754; P < 0.0001), and LS value (r = 0.726; 95% CI 0.521-0.851; P = 0.003). T1ρ values showed moderate positive correlations with LS values [r = 0.693; 95% confidence interval (CI) 0.472-0.832; P < 0.0001]. Areas Under ROC (AUROCs) were 0.861 (95% CI 0.705-0.953) for SWE and 0.856 (95% CI 0.698-0.950) for T1ρ (P = 0.940), 0.906 (95% CI 0.762-0.978) for SWE and 0.849 (95% CI 0.691-0.946) for T1ρ (P = 0.414), 0.870 (95% CI 0.716-0.958) for SWE and 0.799 (95% CI 0.632-0.913) for T1ρ (P = 0.422), and 0.846 (95% CI 0.687-0.944) for SWE and 0.692 (95% CI 0.517-0.835) for T1ρ (P = 0.137), when diagnosing liver fibrosis with ≥ F1, ≥ F2, ≥ F3, and F4, respectively. There was moderate positive correlation between inflammatory activity and T1ρ values (r = 0.520; 95% CI 0.158-0.807; P = 0.013). CONCLUSION: T1ρ imaging has potential for liver fibrosis detection and staging with good diagnostic capability similar to that of ultrasonography elastography.

The value of DCE-MRI in assessing histopathological and molecular biological features in induced rat epithelial ovarian carcinomas.

BACKGROUND: To investigate dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for assessing histopathological and molecular biological features in induced rat epithelial ovarian carcinomas (EOCs). METHODS: 7,12-dimethylbenz[A]anthracene (DMBA) was applied to induce EOCs in situ in 46 SD rats. Conventional MRI and DCE-MRI were performed to evaluate the morphology and perfusion features of the tumors, including the time-signal intensity curve (TIC), volume transfer constant (Ktrans), rate constant (Kep), extravascular extracellular space volume ratio (Ve) and initial area under the curve (IAUC). DCE-MRI parameters were correlated with histological grade, microvascular density (MVD), vascular endothelial growth factor (VEGF) and fraction of Ki67-positive cells and the serum level of cancer antigen 125 (CA125). RESULTS: Thirty-five of the 46 rats developed EOCs. DCE-MRI showed type III TIC more frequently than type II (29/35 vs. 6/35, p < 0.001) in EOCs. The two types of TIC of tumors had significant differences in the histological grade, MVD, expression of VEGF and Ki67, and the serum level of CA125 (all p < 0.01). Ktrans, Kep and IAUC values showed significant differences in different histological grades in overall and pairwise comparisons except for IAUC in grade 2 vs. grade 3 (all p < 0.01). There was no significant difference in Ve values among the three grade groups (p > 0.05). Ktrans, Kep and IAUC values were positively correlated with MVD, VEGF and Ki67 expression (all p < 0.01). Ve was not significantly correlated with MVD, VEGF expression, Ki67 expression and the CA125 level (all p > 0.05). CONCLUSIONS: TIC types and perfusion parameters of DCE-MRI can reflect tumor grade, angiogenesis and cell proliferation to some extent, thereby helping treatment planning and predicting prognosis.

Improving Detection of Iron Deposition in Cirrhotic Liver Using Susceptibility-Weighted Imaging With Emphasis on Histopathological Correlation.

OBJECTIVE: The aim of this study was to investigate the value of susceptibility-weighted imaging (SWI) for detection and quantification of iron deposition in cirrhotic liver. METHODS: Fifty-five cirrhotic patients underwent hepatic magnetic resonance imaging examination including SWI and multiecho T2*-weighted imaging (T2*WI). Detection of iron deposition and number of siderotic nodules were compared between SWI and T2*WI. Correlation among SWI phase value, T2* value, and hepatic iron concentration were determined. RESULTS: Susceptibility-weighted imaging significantly improved detection of iron deposition compared with T2*WI (90.7% vs 66.7%, P = 0.002), attributing to grade 1 (73.3% vs 26.7%, P = 0.027) and grade 2 (93.8% vs 56.3%, P = 0.037). Iron deposition of grade 3 and 4 could be detected by both SWI and T2*WI. The number of siderotic nodules visualized on SWI was significantly larger than that on T2*WI (107.5 ± 7.4 vs 62.7 ± 4.6, P = 0.002). There were significantly negative correlation between phase value and iron score (r = -0.803), and positive correlation between phase value and T2* value (r = 0.771). CONCLUSIONS: Susceptibility-weighted imaging can improve detection of minimal and mild iron deposition in cirrhotic liver.

Detection of Endogenous Iron Reduction during Hepatocarcinogenesis at Susceptibility-Weighted MR Imaging: Value for Characterization of Hepatocellular Carcinoma and Dysplastic Nodule in Cirrhotic Liver.

OBJECTIVE: To investigate the value of susceptibility-weighted imaging (SWI) for characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN). MATERIALS AND METHODS: Sixty-eight cirrhotic patients with 89 hepatocellular nodules underwent SWI. The radiological features of hepatocellular nodules on SWI were classified into three types: type A (iso- or hypointensity, and background liver siderosis), type B (hyperintensity, and background liver siderosis), or type C (hyperintensity, and no background liver siderosis). Intranodular and background liver iron content was quantified and correlated with SWI pattern. Prussian blue staining was performed to quantify intranodular and background liver iron content. RESULTS: Type A pattern (n = 12) contained 11 (91.7%) DNs and 1 (8.3%) HCC, Type B pattern (n = 66) comprised 1 (1.5%) DN and 65 (98.5%) HCCs (including 12 DN-HCCs and 53 overt HCCs), and type C pattern (n = 11) was exclusively seen in HCCs. The iron scores of DN-HCCs and overt HCCs were significantly lower than those of background livers [(0.091±0.30) VS (2.18±0.87), P = 0.000; (0.11±0.41) VS (2.16±0.97), P = 0.000; respectively]. There was no significant difference between iron scores of DNs and those of background livers [(1.92±0.29) VS (2.17±039), P = 0.191]. For lesion-based and patient-based analysis of HCCs (DN-HCCs and overt HCCs), type B pattern showed a sensitivity, specificity, accuracy, positive predicative value (PPV), and negative predicative value (NPV) of 84.4% and 84.4%, 91.7% and 75%, 85.4% and 83.8%, 98.5% and 98.2%, 47.8% and 23.1%, respectively. CONCLUSION: SWI can provide valuable information for characterization of HCC and DN based on endogenous iron reduction during hepatocarcinogenesis.

Visualizing Central Vessels of Hepatic Angiomyolipoma Devoid of Fat Using a 2D Multi-Breath-Hold Susceptibility-Weighted Imaging.

Epithelioid hepatic angiomyolipoma (Epi-HAML) is a rare benign mesenchymal tumor with malignant potential. Most of Epi-HAML contains no or only a minimal amount of adipose tissue and poses a diagnostic challenge. Central vessels are characteristic imaging finding of Epi-HAML, which usually were displayed by dynamic contrast imaging. In this paper, we displayed the central vessels of Epi-HAML invisible on conventional MR images using a new developed abdominal susceptibility-weighted imaging (SWI). To the best of our knowledge, this is the first description for the role of SWI in characterization of Epi-HAML.

Primary hepatic neuroendocrine carcinoma: MR imaging findings including preliminary observation on diffusion-weighted imaging.

PURPOSE: To investigate MR imaging findings of primary hepatic neuroendocrine carcinoma (PHNEC) including preliminary observations on diffusion-weighted imaging (DWI). MATERIALS AND METHODS: MR images of eight patients with pathologically confirmed PHNEC were retrospectively analyzed. The morphological characteristics and dynamic enhancement patterns were evaluated. RESULTS: One case showed a well-defined solitary nodule with homogenous hypointensity on T1-weighted imaging (T1WI) and hyperintensity on T2-weighted imaging (T2WI) and DWI. The remaining seven cases appeared as well-defined dominant masses with multiple satellite nodules. The dominant masses demonstrated heterogeneous hypointensity on T1WI and hyperintensity on T2WI, which all appeared as a marked enhancement at arterial phase and rapid washout at portal venous phase. Six cases demonstrated rim-like enhancement at equilibrium phase. The satellite lesions showed heterogeneous hypointensity on T1WI and marked hyperintensity on T2WI with variable enhancements, such as homogeneous, rim-like enhancement. All the dominant masses and satellite nodules appeared as markedly hyperintensity and reduced apparent coefficient (ADCs) values on DWI. The mean ADC value of the tumors was significantly lower than that of surrounding liver parenchyma (1.02 ± 0.57 vs. 2.24 × 10(-3) mm(2)/s, p = 0.000). CONCLUSION: PHNECs typically appear as a large dominant hypervascular mass accompanied by satellite nodules, with rapid washout and capsular enhancement on dynamic MR imaging and restricted diffusion on DWI.

Utility of diffusion-weighted imaging in differentiating malignant from benign thyroid nodules with magnetic resonance imaging and pathologic correlation.

OBJECTIVE: The objective of this study was to evaluate the role of magnetic resonance diffusion-weighted imaging (DWI) in differentiating malignant from benign thyroid nodules. METHODS: The prospective study included 111 consecutive patients with solitary thyroid nodules (23 malignant and 88 benign nodules) who underwent DWI. The DWI signal and apparent diffusion coefficient (ADC) values of the nodules were determined and correlated with the histopathologic findings. RESULTS: The majority (65%) of malignant thyroid nodules showed slightly hyperintense, and the majority (69%) of benign nodules were hyperintense on DWI (P < 0.01). The ADC values were lower in the thyroid cancer than in the adenoma and nodular goiter (P < 0.05). When the b factor was 500 s/mm, an ADC value of 1.704 × 10 mm/s can be threshold differentiating malignant from benign nodules, with 92% sensitivity, 88% specificity, and 87% accuracy. The higher cell density and more severe desmoplastic response were the causes of the lower ADC value of thyroid cancer. CONCLUSION: Diffusion-weighted imaging can be a promising noninvasive imaging to discriminate malignant from benign nodules.

Using a 2D multibreath-hold susceptibility-weighted imaging to visualize intratumoral hemorrhage of hepatocellular carcinoma at 3T MRI: correlation with pathology.

PURPOSE: To assess the value of 2D multibreath-hold susceptibility-weighted imaging (SWI) for visualizing intratumoral hemorrhage of hepatocellular carcinoma (HCC) and correlate with pathological results. MATERIALS AND METHODS: Fifty-eight patients with 65 HCCs underwent T1-, T2-, T2-weighted imaging and SWI. The ability to detect intratumoral hemorrhage for each imaging technique was evaluated. A radiologic-pathological correlation was performed. RESULTS: The area under the receiver operator characteristic (ROC) curve (Az value) for SWI (Az = 0.941) was significantly greater than that for T1WI (Az = 0.748) and T2WI (Az = 0.700) (P = 0.000). When compared with T2, SWI had slightly higher sensitivity and equal specificity, but the Az value was not significantly different (P = 0.768). The total number of hemorrhages detected by SWI was greatest by factors of 13.3, 6.7, and 2.2 compared to T1WI, T2WI, and T2, respectively. SWI detected more microbleeds (585 in 25 HCCs) than T1WI (13 in 5 HCCs), T2WI (66 in 11 HCCs), and T2 (238 in 21 HCCs). CONCLUSION: SWI can accurately visualize internal hemorrhages and provide valuable information regarding the internal architecture of HCC.

Standardized ultrasound hepatic/renal ratio and hepatic attenuation rate to quantify liver fat content: an improvement method.

Accurate measures of liver fat content are essential for investigating the role of hepatic steatosis in the pathophysiology of multiple metabolic disorders. No traditional imaging methods can accurately quantify liver fat content. [(1)H]-magnetic resonance spectroscopy (MRS) is restricted in large-scale studies because of the practical and technological issues. Previous attempts on computer-aided ultrasound quantification of liver fat content varied in method, and the ultrasound quantitative parameters measured from different ultrasound machines were hardly comparable. We aimed to establish and validate a simple and propagable method for quantitative assessment of liver fat content based on the combination of standardized ultrasound quantitative parameters, using [(1)H]-MRS as gold standard. Totally 127 participants were examined with both ultrasonography (US) and [(1)H]-MRS. Ultrasound hepatic/renal echo-intensity ratio (H/R) and ultrasound hepatic echo-intensity attenuation rate (HA) were obtained from ordinary ultrasound images using computer program. Both parameters were standardized using a tissue-mimicking phantom before analysis. Standardized ultrasound H/R and HA were positively correlated with the liver fat content by [(1)H]-MRS (r = 0.884, P < 0.001 and r = 0.711, P < 0.001, respectively). Linear regression analysis showed ultrasound H/R could modestly predict the amount of liver fat (adjusted explained variance 78.0%, P < 0.001). The addition of ultrasound HA slightly improved the adjusted explained variance to 79.8%. Difference of estimated liver fat contents between different ultrasound machines and operators was reasonably well. Thus, computer-aided US is a valid method to estimate liver fat content and can be applied extensively after standardization of ultrasound quantitative parameters.

Elevation of liver enzymes within the normal limits and metabolic syndrome.

1. Metabolic syndrome is frequently associated with elevated liver enzymes. However, the current 'normal' limits for liver enzymes often fail to identify patients with metabolic syndrome and the associated non-alcoholic fatty liver disease (NAFLD). 2. In the present study, 1503 participants, aged between 18 and 95 years, were recruited from the physical examination centre of Shanghai Zhongshan Hospital and Shanghai Changfeng Community Health Centre. The association between liver enzymes within the 'normal' range and metabolic syndrome was investigated and optimal cut-off values for liver enzymes in metabolic syndrome were determined. We further compared the diagnostic performance of the new cut-off values for liver enzymes in metabolic syndrome and NAFLD with the traditional 'normal' range for liver enzymes. 3. Serum liver enzymes within the traditional 'normal' limits, especially alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (GGT), were correlated with most of components of the metabolic syndrome, as determined by Spearman's partial correlation analysis. Logistic regression analysis revealed that within the 'normal' range of liver enzymes, the frequency of metabolic syndrome was significantly increased in the higher quintile for ALT and GGT compared with the lowest quintile. Receiver operating characteristic curve analysis revealed that the optimal cut-off values for ALT, aspartate aminotransferase and GGT to identify metabolic syndrome were 26, 25 and 29 U/L, respectively, in men and 20, 23 and 21 U/L, respectively, in women. These values were much more effective in detecting patients with potential metabolic syndrome and NAFLD than the traditional cut-off values. 4. A slight elevation of liver enzymes within the 'normal' limits, especially ALT and GGT, indicates the presence of metabolic syndrome and NAFLD. Revision of the current normal limits for liver enzymes is advisable so that patients with potential metabolic disorders can be identified.

Acute mesenteric ischemia induced by ligation of porcine superior mesenteric vein: multidetector CT evaluations.

RATIONALE AND OBJECTIVES: To evaluate multidetector computed tomography (MDCT) for detecting the early changes and dynamic evolution of acute mesenteric ischemia (AMI) induced by the ligation of superior mesenteric vein (SMV) in an experimental porcine model. MATERIALS AND METHODS: Twelve pigs were randomly assigned to three experimental groups, and one control group with three pigs in each group. After laparotomy, the SMV was separated and ligated in nine pigs and separated without ligation in three controls. MDCT pre- and postcontrast with arterial, venous, and delayed phase scans, and CT angiography reconstructions of mesenteric vessels were carried out at preoperation, 6 hours, 12 hours, and 18 hours after ligation. The findings of mesenteric vessels, bowel, abdominal cavity at pre- and postoperation, and dynamic evolution were correlated with pathology. RESULTS: AMI-induced pathological changes were identified in all nine experimental pigs. MDCT angiography clearly delineated main trunk of the SMV, peripheral major and minor tributaries up to brushy vasa recta, and the location and shape of ligations. The early ischemic findings were bowel wall thickening, mesenteric edema, ascites, and pronounced bowel enhancement. Superior mesenteric artery and its major branches appeared spasm with poor filling and delayed and prolonged visualization. SMV and its tributaries were poorly delineated with delayed opacification. We also saw thinning of bowel wall, dilatating bowel with fluid, aggravating mesenteric edema and ascites, and poor enhanced bowel over time. CONCLUSION: MDCT detects early changes of mesenteric ischemia and its evolution after ligation of porcine SMV, and may find application in early diagnosis of human venous occlusive AMI.

[Multidetector-row CT evaluation of acute bowel ischemia induced by embolization of superior mesenteric artery in experimental porcine models].

OBJECTIVE: To evaluate the application of multi-detector row CT (MDCT) and CT angiography (CTA) for detecting early signs of acute bowel ischemia (ABI) in experimental porcine models. METHODS: Twelve pigs were assigned to four groups with 3 in each group. The digital subtraction angiography of superior mesenteric artery (SMA) and the embolization of branches of SMA with gelatin sponge and blood clot were performed by percutaneous transfemoral artery puncture and catheterization. MDCT pre- and post-contrast scanning in the arterial, venous and delay phase and CTA with three-dimensional reconstruction were carried out at pre-operation, 3 h, 6 h, 9 h, and 12 h after occlusion. The normal mesenteric vascular anatomy, arterial occlusion, mesentery and bowel changes, and dynamic change were evaluated. RESULTS: ABI changes were identified pathologically in all the 12 experimental pigs, and the severity of ischemia increased over time after embolization. CTA showed all 57 embolized branches of SMA and 29 of 34 unoccluded arterial branches with 5 false-positive vessel occlusions. The sensitivity and specificity of CTA were 100% and 85.3%, respectively. Thin-slab maximum intensity projection (TSMIP) revealed the disappearance of distal comb-like vessel branches and brush-like vasa recta, which were clearly delineated in the normal bowel segments. Using this criterion, TSMIP correctly defined 23 of 24 ischemic bowel segments and all the 12 normal bowel segments with a sensitivity of 95.8% and a specificity of 100%. CONCLUSIONS: MDCT and CTA reliably define normal and occluded mesenteric vessels in the pig. It can easily detect ischemic bowel segment by identified early changes of ischemia. The early direct ischemic signs are occluded vessels, the disappearance of distal comb-like branches or brush-like vasa recta, and poor bowel enhancement. The early indirect sign is bowel dilatation with fluid collection.