Quantitative analysis of pancreatic echogenicity on transabdominal sonography: correlations with metabolic syndrome.

PURPOSE: To attempt a quantitative analysis of pancreatic echogenicity on transabdominal ultrasonography (US) and evaluate the correlation between pancreatic echogenicity and metabolic syndrome (MetS). METHODS: We retrospectively evaluated transabdominal sonograms from 286 subjects. Mean pancreatic body brightness, mean perihepatic fat brightness, and the pancreato-perihepatic fat index (PPHFI) were measured, and reproducibility was analyzed using intraclass correlation coefficients. Associations between the PPHFI and MetS components were analyzed. The optimal PPHFI cutoff value to predict MetS was calculated. RESULTS: Reproducibility was good for mean pancreatic body brightness, mean perihepatic fat brightness, and PPHFI with intraclass correlation coefficients of 0.98, 0.95, and 0.95, respectively. Each MetS component showed a significant association with PPHFI. Waist circumference had the strongest association (r = 0.55, p < 0.0001). PPHFI was significantly higher in the MetS (+) group than the MetS (-) group (p < 0.0001), and PPHFI was an independent factor predicting MetS (p = 0.02; odds ratio, 2.89). The best PPHFI cutoff value to predict MetS was 1.97, with a relatively high negative predictive value of 94.1%. CONCLUSIONS: We quantitatively analyzed pancreatic echogenicity using the PPHFI on US and found that an increased PPHFI was significantly correlated with MetS. Because increased PPHFI on US may indicate MetS, radiologists and clinicians need to be aware of its implications.

Gadoxetate disodium-enhanced MRI of mass-forming intrahepatic cholangiocarcinomas: imaging-histologic correlation.

OBJECTIVE: The purpose of this study was to describe the enhancement patterns of mass-forming intrahepatic cholangiocarcinomas on gadoxetate disodium-enhanced MR images using imaging-histologic correlation. MATERIALS AND METHODS: We retrospectively evaluated the preoperative gadoxetate disodium-enhanced MR images of 19 patients with mass-forming intrahepatic cholangiocarcinomas. Two readers independently interpreted enhancement patterns on arterial (globally high, rimlike), dynamic (washout, progressive), and hepatobiliary (target, nontarget) phase images. Dynamic enhancement was categorized as washout (hypoenhancement on later phase compared with arterial phase images) or progressive (persistent or gradually increased enhancement). Tumor enhancement ratio and tumor-to-liver signal difference curves were analyzed. The enhancement patterns were correlated with the extent of stromal fibrosis within the tumors. RESULTS: Rimlike arterial enhancement (89%, reader 1; 84%, reader 2) and a progressive dynamic pattern (89%, both readers) were predominant. Tumor enhancement ratio increased gradually from the arterial to the equilibrium phase then decreased in the hepatobiliary phase, but the tumor signal intensities were lower than liver signal intensity in all phases. The two lesions that both readers considered to have globally high arterial enhancement and a washout dynamic pattern presented with minimal or scattered stromal fibrosis. Target appearance in the hepatobiliary phase (reader 1, 42%; reader 2, 47%) was more commonly seen in tumors with central stromal fibrosis (reader 1, p = 0.025; reader 2, p = 0.001). CONCLUSION: Mass-forming intrahepatic cholangiocarcinomas may be characterized by rimlike enhancement and a progressive dynamic pattern on gadoxetate disodium-enhanced MR images, and these features seem related to the extent of stromal fibrosis in the tumor. Furthermore, mass-forming intrahepatic cholangiocarcinomas may have a pseudowashout pattern on gadoxetate disodium-enhanced MR images because of progressive background liver enhancement. Therefore, radiologists need to be aware of this pattern as a possible pitfall.

Hyperintense lesions on gadoxetate disodium-enhanced hepatobiliary phase imaging.

OBJECTIVE: The purpose of this article is to illustrate various focal hepatic lesions that may show hyperintensity on hepatobiliary phase images on gadoxetate disodium-enhanced MRI. CONCLUSION: Hyperintense lesions on gadoxetate disodium-enhanced MRI include focal nodular hyperplasia (FNH) or FNH-like nodules, hepatocellular adenoma, dysplastic nodules, and hepatocellular carcinoma. Understanding the contrast enhancement patterns on hepatobiliary phase images and other imaging findings is important to ensure correct diagnosis.

Hyperintense HCC on hepatobiliary phase images of gadoxetic acid-enhanced MRI: correlation with clinical and pathological features.

PURPOSE: To retrospectively determine whether the hyperintense hepatocellular carcinomas (HCCs) seen on the hepatobiliary phase of gadoxetic acid-enhanced MR imaging (EOB-MRI) might have different histologic characteristics from usual hypointense HCCs. MATERIALS AND METHODS: Two hundred three surgically proven HCCs from 192 patients who underwent preoperative EOB-MRI were analyzed. The demographic and histologic characteristics of hyperintense HCCs were compared with usual hypointense HCCs by using the t-test or Fisher's exact test. RESULTS: By visual assessment, 18 (8.8%) tumors were classified as hyperintense HCCs. Patients with hyperintense HCC were significantly (p<0.05) older (60.1 vs. 55.2 years) than those with hypointense HCCs. Hyperintense HCCs showed significantly lower rate of microvascular invasion (27.8% vs. 53.5%) and significantly higher rate of peliosis (61.1% vs. 30.8%). Hyperintense HCCs were more frequently expanding type, and none showed infiltrative type or scirrhous histologic pattern. CONCLUSIONS: Hyperintense HCCs seem to have clinical and histologic features that might be related with more favorable outcomes.

Detection of liver metastases using gadoxetic-enhanced dynamic and 10- and 20-minute delayed phase MR imaging.

PURPOSE: To assess the incremental value of hepatobiliary phase images in gadoxetate disodium-enhanced magnetic resonance imaging (MRI), and to compare diagnostic accuracy and lesion conspicuity on 10- and 20-minute delayed images for preoperative detection of hepatic metastases with subgroup analysis according to size and history of chemotherapy. MATERIALS AND METHODS: Forty-six patients with 107 metastases who underwent surgery after gadoxetate disodium-enhanced MRI were evaluated. Four observers independently interpreted three sets: dynamic set comprising precontrast T1-, T2-weighted, and dynamic images; 10-minute set comprising dynamic set and 10-minute delayed; 20-minute set comprising 10-minute set and 20-minute delayed. Diagnostic accuracy was compared with subgroup analysis. Liver-to-lesion signal ratio (SR) was calculated using the region of interest method and compared. RESULTS: Mean A(z) and sensitivities were significantly higher for 10- (A(z) = 0.894, sensitivity = 95.6%) and 20-minute (0.910, 97.2%) than dynamic set (0.813, 79.9%) (P < 0.001), with no significant difference between 10- and 20-minute sets (P = 0.140). In patients with small (≤1 cm) metastases and a history of chemotherapy, sensitivities were significantly higher with 10- (88.2%) and 20-minute (91.6%) sets than dynamic set (48.6%) (P < 0.001). SR was significantly higher for 10- and 20-minute delayed than precontrast and dynamic, with significantly higher SR on 20- than 10-minute delayed. CONCLUSION: Regardless of size or prior chemotherapy, detection of hepatic metastases was significantly improved by adding hepatobiliary phase images without significant differences between 10- and 20-minute delayed.

MRI features of hepatocellular carcinoma expressing progenitor cell markers.

BACKGROUND & AIMS: To determine whether magnetic resonance (MR) imaging features differ between hepatocellular carcinomas (HCCs) with and without expression of progenitor cell markers, such as cytokeratin (CK) 19 and epithelial cell adhesion molecule (EpCAM). METHODS: Sixty-three patients with 71 HCCs who underwent surgery after preoperative gadoxetic acid-enhanced MR imaging were evaluated. HCCs expressing progenitor cell markers were defined as showing CK19 or EpCAM expression. MR imaging features, including the fat component, arterial enhancement (global vs. peripheral), dynamic enhancement (washout vs. progressive or persistent), nodule-in-nodule appearance and MR gross morphology (expanding vs. non-expanding), were compared between HCCs with and without progenitor cell markers expression. Lesion-to-liver signal intensity ratio (SIR) and apparent diffusion coefficient values were compared using an independent samples t-test. Early recurrence rates were also compared. RESULTS: HCCs expressing progenitor cell markers were more commonly of the non-expanding type (P = 0.016), more frequently had a progressive or persistent dynamic enhancement pattern (P = 0.008) and less frequently demonstrated a nodule-in-nodule appearance (P = 0.009). HCCs expressing progenitor cell markers had significantly higher SIRs on diffusion-weighted images (DWIs) (b = 50 and 800, P < 0.001; b = 400, P = 0.001) and a significantly lower SIR on hepatobiliary phase images (P = 0.024). The early recurrence rate was significantly higher in patients with prior HCCs that expressed progenitor cell markers (P = 0.045). CONCLUSIONS: HCCs expressing progenitor cell markers can be characterized according to their non-expanding MR gross morphology, persistent or progressive dynamic enhancement patterns, higher SIRs on DWIs, lower SIRs on hepatobiliary phase images and less frequent nodule-in-nodule appearance.