Distinction of hemangiomas from hepatic tumors with delayed enhancement by incremental dynamic CT

Dual-Source Contrast-Enhanced Multiphasic CT of the Liver Using Low Voltage (70 kVp): Feasibility of a Reduced Radiation Dose and a 50% of Contrast Dose

This study investigated the feasibility of both a reduced radiation dose and a 50% of contrast dose in multiphasic CT of the liver with a 70 kVp protocol compared with a standard-tube-voltage protocol derived from dual-energy (DE) CT (blended DE protocol) with a full-dose contrast-agents in the same patient group. This study included 46 patients who underwent multiphasic contrast-enhanced dynamic CT of the liver with both a 70 kVp and a blended DE protocols. For quantitative analysis, median CT values for the liver, aorta, and portal vein, as well as signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), were measured and calculated. In addition, as a qualitative analysis, the contrast effect and overall image quality of the abdominal organs were evaluated on a five-point scale. CNR and SNR of the hepatic parenchyma were not significantly different between the 70kV protocol and the Blended DE protocol in all phases. The 70 kVp protocol showed significantly better image quality compared with the blended DE protocol in the arterial phase (p = 0.035) and the equilibrium layer phase (p = 0.016). A 70 kVp CT protocol in combination with a reduced radiation dose and half-dose iodine load is feasible for multiphasic dynamic CT of the liver by maintaining the contrast enhancement effects and image quality in comparison with the blended DE CT protocol.

Peripheral low intensity sign in hepatic hemangioma: diagnostic pitfall in hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI of the liver

PURPOSE

To describe the presence of "peripheral low intensity sign" in hepatic hemangioma in the hepatobiliary phase (HP) of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and to compare the frequency of this sign between hepatic hemangiomas and hepatic metastases.

MATERIALS AND METHODS

The Institutional Review Board approved this study and waived the requirement for informed consent. Sixty-four patients with 51 hepatic hemangiomas (n = 31 patients) and with 58 hepatic metastases (n = 33 patients) underwent Gd-EOB-DTPA-enhanced MRI. In all hepatic hemangiomas, 41 lesions were the typical type and 10 were the high flow type. HP images were qualitatively evaluated for the frequency of peripheral low intensity sign in hepatic hemangiomas and hepatic metastases using a four-point scale. Statistical evaluations were performed with a Mann-Whitney U-test.

RESULTS

Peripheral low intensity signs were demonstrated in 24 (47%) of 51 hepatic hemangiomas, while they were seen in 27 (47%) of 58 hepatic metastases. There was no significant difference in the mean visual score of peripheral low intensity sign between all hepatic hemangiomas (0.84 ± 1.03) and hepatic metastases (0.76 ± 0.92). The mean visual score of peripheral low intensity sign in typical hemangiomas (1.02 ± 1.06) was significantly higher than that in high flow hemangiomas (0.10 ± 0.32) (P = 0.008).

CONCLUSION

Peripheral low intensity sign is not specific for malignant tumors, and can be seen even in hepatic hemangiomas on HP of Gd-EOB-DTPA-enhanced MRI.

Differential diagnosis of hepatic tumors with delayed enhancement at gadolinium-enhanced MRI: a pictorial essay

Hepatic lesions with delayed enhancement are sometimes encountered on gadolinium-enhanced MRI of the liver. This study illustrates the varied appearances of several pathologic entities with delayed enhancement, including hepatic hemangioma, hepatic metastases, intrahepatic cholangiocarcinoma, focal nodular hyperplasia, hepatic abscess, hepatocellular carcinoma, and hepatocellular carcinoma after transcatheter arterial chemoembolization, and presents the utility of arterial-phase dynamic MRI in the differential diagnosis of these lesions. Possible causes of these delayed enhancements are also discussed.

Hepatic parenchymal changes after ethanol injection in rabbits: correlation of conventional and dynamic MR imaging with pathologic findings

The purpose of this study is to clarify the changes of peripheral normal liver parenchyma before and after ethanol injection, with respect to MR appearances and pathologic findings and, in so doing, to clinically evaluate the therapeutic effectiveness of percutaneous ethanol injection (PEI) therapy. The normal liver in 12 rabbits was injected with ethanol. We performed conventional and dynamic MR imaging and prepared the histopathologic specimens 1 week (group 1), 2 weeks (group 2), and 1 month (group 3) after ethanol injection. On conventional MR images, coagulative necrosis in the normal liver was demonstrated as an area of low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in all groups. On dynamic MR images, contrast enhancement in the coagulative necrosis was not seen in groups 1 and 2; however, gradual and concentric enhancement was seen in the direction of the central necrotic portion from early-to-delayed phase image in group 3. Although signal intensity of the coagulative necrotic area in the normal liver after ethanol injection may mimic that of untreated or viable hepatocellular carcinoma (HCC) when clinically encountered on conventional MR images, coagulative necrosis of the normal liver parenchyma will be discriminated from viable HCC by using dynamic MR imaging.

Hepatic tumors: magnetization transfer MR imaging with gadolinium enhancement

Thirty patients with 15 hepatocellular carcinomas, 10 metastases, four hemangiomas, and one cholangiocarcinoma underwent magnetic resonance imaging at 1.5 T with T1-weighted, T2-weighted spin-echo (SE) images, gradient-echo (GRE) magnetization transfer (MT) images, and gadolinium-enhanced T1-weighted SE and MT-GRE images. The MT effect and lesion-liver contrast-to-noise ratio (C/N) were calculated and visual assessment (qualitative analysis) performed for unenhanced and enhanced MT-GRE images and enhanced T1-weighted SE images. The C/N values for hepatic adenocarcinomas (seven metastases and one cholangiocarcinoma) and hemangiomas were larger for enhanced MT-GRE images (adenocarcinoma, 8.4 +/- 2.3 [P < .01]; hemangioma 24 +/- 2.1 [P < .05]) than for enhanced GRE images (5.0 +/- 1.9 and 18 +/- 2.7, respectively). These enhancing tumors had the highest scores in the qualitative analysis. Enhanced MT-GRE images showed no advantage for depiction of hepatocellular carcinomas relative to the other images.