Hepatic cavernous hemangioma: temporal peritumoral enhancement during multiphase dynamic MR imaging

Discontinuous peripheral enhancement of focal liver lesions on CT and MRI: outside the box of typical cavernous hemangioma

The discontinuous peripheral enhancement is a pattern of enhancement usually attributed to typical cavernous hemangioma, that is the most common benign solid lesion of the liver. The discontinuous peripheral enhancement, however, may be encountered in many other benign and malignant focal liver lesions as an atypical presentation or evolution, and hemangiomas with discontinuous peripheral hyperenhancement on hepatic arterial phase may not always have the typical post-contrast pattern on portal venous and delayed phases. Therefore, abdominal radiologists may be challenged in their practice by lesions with discontinuous peripheral enhancement. This pictorial essay aims to review the spectrum of benign and malignant focal liver lesions that may show discontinuous peripheral enhancement. A particular point of interest is the diagnostic tree pathway that may guide the radiologists in the differential diagnosis.

Interventional treatments for hepatic hemangioma: A state-of-the-art review

Hepatic hemangiomas (HHs) are the most common benign tumors of the liver. These tumors are mainly asymptomatic and do not require treatment. Nevertheless, there are some special cases that require therapeutic intervention, and surgery and intervention are currently the primary treatment modalities. Despite significant advances in the development of minimally invasive techniques and their popularization, interventional treatment of HH is still the preferred choice. In the present review, we discuss the pathological properties, type of blood supply, and treatment indications for HH and assess the status and progress of the existing interventional treatments.

Hepatic sclerosed hemangioma and sclerosing cavernous hemangioma: a radiological study

Purpose

To investigate and compare the CT and MRI features of hepatic sclerosed hemangioma (HSH) and sclerosing cavernous hemangioma (SCH).

Materials and methods

Twelve HSH cases and 36 SCH cases were included, the imaging findings on CT (9 HSH and 34 SCH) and MRI (8 HSH and 10 SCH) were analyzed. Qualitative image analysis included the location, size, shape, capsular retraction, density, calcification, signal intensity on T₁-weighted image (T₁WI) and T₂-weighted image (T₂WI), presence of diffusion restriction, apparent diffusion coefficient (ADC) map, transient hepatic attenuation difference around the lesion, and the dynamic enhancement patterns.

Results

The presence of liver cirrhosis in patients with HSH (3/12) was higher than SCH (1/36) (P = 0.043). The morphology appearance before enhancement showed no significant difference between HSH and SCH. Moreover, SCH had a stronger trend of centripetal enhancement patterns of cavernous hemangiomas (83.3%) compared to HSH (25%) (P < 0.001). Due to more frequent atypical enhancement features, containing rim-like enhancement, no enhancement, and peripheral heterogeneous enhancement, the misdiagnosis rate of HSH (75%) was significantly higher than that of SCH (16.7%) (P < 0.001). Furthermore, the ADC values of HSH and SCH were both higher than that of the surrounding liver parenchyma (P = 0.009, P = 0.002); however, there was no significant difference in ADC values between themselves (P = 0.613).

Conclusion

SCH showed the same trend of centripetal enhancement characteristics as typical hemangioma, while HSH exhibited atypical enhancement features due to complete sclerosis. Higher ADC values might contribute to the identification of atypical HSH and SCH from malignancies.

The humbling hemangioma: uncommon CT and MRI imaging features and mimickers of hepatic hemangiomas

Cavernous hemangiomas are among the most common liver lesions encountered in abdominal imaging. While classical imaging characteristics usually aid the radiologist in confidently arriving at its diagnosis, atypical hemangiomas can prove to be difficult to distinguish from other more worrisome hepatic lesions such as metastases and hepatocellular carcinoma. Furthermore, some malignant lesions can display features that simulate hemangiomas. The radiologist must be aware of these pitfalls to make an accurate diagnosis, when possible.

Cavernous Sinus Hemangioma: Imaging Diagnosis and Surgical Considerations

BACKGROUND

Cavernous sinus hemangiomas (CSHs) are extraaxial vascular malformations that tend to bleed during surgery.

METHODS

We reviewed 12 magnetic resonance imaging scans with CSH, 5 of them biopsy proven.

RESULTS

In our review, CSH commonly presented as a lobulated mass with high, uniform signal intensity on T2-weighted images, a dumbbell shape, and a sellar extension. Two thirds presented a "filling-in" pattern of enhancement on dynamic imaging. These features should lead to a correct preoperative diagnosis, which is essential for surgical planning and avoiding hemorrhagic complications.

CONCLUSIONS

A combination of low signal on T1, high signal on T2 and fluid-attenuated inversion recovery, no diffusion restriction and homogenous enhancement should place CSH at the top of the list of differential diagnoses. This is especially true when there is a "filling-in" pattern on dynamic or delayed imaging. Doing so may alert surgeons to the possibility of copious intraoperative bleeding and therefore avoid complications of hemorrhage.

Sclerotic changes of cavernous hemangioma in the cirrhotic liver: long-term follow-up using dynamic contrast-enhanced computed tomography

PURPOSE

To determine the intra- and extralesional factors that predict sclerotic degeneration of hepatic hemangiomas in the cirrhotic liver on long-term follow-up computed tomography (CT) examinations.

MATERIALS AND METHODS

Fifty-seven hepatic hemangiomas (> 5 mm in diameter) in 41 cirrhotic patients, recruited over a 5-year period (January 2005-December 2009), were subjected to CT to determine which factors predict sclerotic contraction or degeneration in hemangiomas. Prior and follow-up CT examinations (from 2000 to 2018) were included to observe time-related changes. The patients' gender, age, cause of cirrhosis, progression of background liver cirrhosis, lesion size/location/contrast enhancement pattern, and serum aspartate transaminase to platelet ratio index were correlated with sclerotic changes of each lesion.

RESULTS

According to the dynamic CT features, 36 of 57 (63%) hemangiomas were determined to have sclerotic changes during the follow-up period (1.1-14.4 years, median: 7.8 years), including 28 lesions (49%) reduced by ≥ 20% in diameter. In univariate analysis, age (p = 0.047) and morphological progression of background cirrhosis (p = 0.013) were significantly related to sclerotic change of hemangiomas. In the logistic regression analysis, only morphological progression of background liver cirrhosis independently predicted sclerotic change (odds ratio: 4.88, p = 0.007). With the exception of exophytic location free from size reduction (p = 0.023 in multivariate analysis), no other analyzed factors were significantly correlated with sclerotic changes.

CONCLUSION

Overall, sclerotic changes of hepatic cavernous hemangioma followed the morphological progression of background liver cirrhosis, while exophytic lesions tended to be free of size reduction.

Differentiation of Hepatic Sclerosed Hemangiomas From Cavernous Hemangiomas Based on Gadoxetic Acid-Enhanced Magnetic Resonance Imaging Features

OBJECTIVE

The objective of this study was to evaluate the imaging features of a hepatic sclerosed hemangioma by comparing them with those of a cavernous hemangioma using magnetic resonance imaging with gadoxetic acid enhancement.

METHODS

Nine patients with hepatic sclerosed hemangiomas and 36 patients with cavernous hemangiomas (control group) who underwent gadoxetic acid-enhanced magnetic resonance imaging were included. Qualitative values (imaging findings and enhancement pattern [typical vs atypical enhancement]) and quantitative values (apparent diffusion coefficient) were evaluated.

RESULTS

Patients with sclerosed hemangiomas showed significantly more irregular tumor margin on hepatobiliary phase images, peritumoral arterial enhancement, and a lower proportion of hyperintensity on heavily T2-weighted images compared with controls (all P values <0.05). In addition, the sclerosed hemangioma group had significantly more frequent atypical enhancement patterns than did the control group (88.9% vs 33.3%; P = 0.006). However, the mean apparent diffusion coefficient value of hemangiomas was not significantly different between the 2 groups (P = 0.639).

CONCLUSIONS

Gadoxetic acid-enhanced magnetic resonance images can help in differentiating between hepatic sclerosed hemangiomas and cavernous hemangiomas.

Hepatic hemangioma with arterioportal shunt: Prevalence and lesion characteristics based on DSA, CT and MR imaging

PURPOSE

To evaluate the prevalence and lesion characteristics of hepatic hemangioma (HH) with arterioportal shunt (APS) based on digital subtraction angiography (DSA), computed tomography (CT) and magnetic resonance (MR) imaging.

METHOD

Ninety-eight consecutive patients with 189 HHs who underwent DSA, CT and/or MR imaging of the liver between January 2014 and December 2017 were included. The diagnosis of APS was established by DSA. APS was categorized as peripheral and central shunt based on imaging findings. The incidence and appearance of APS on DSA were compared with those on CT/MR images. Eleven possible lesion characteristics associated with APS were compared between HHs with and those without APS. Multiple logistic regression modeling was used to identify the independent lesion characteristics associated with APS.

RESULTS

APS was diagnosed in 103 (103/189, 54.5%) HHs on DSA, of which 96 lesions appeared as peripheral APS and 7 appeared as central. In contrast, APS was detected only in 57 HHs (57/103, 55.34%) on CT/MR imaging, of which 50 (50/96, 52.08%) appeared as peripheral APS while 7 (7/7, 100%) appeared as central. Lesion size (P <  .001), enhancement rapidity (P =  .031), and vascularization degree (P <  .001) were found to be significant independent imaging characteristics associated with APS.

CONCLUSIONS

APS can occur in HH with high frequency. DSA was superior to CT/MR imaging in detection of APS, particularly for the peripheral APS. Lesion size, enhancement rapidity and vascularization degree were associated with the presence of APS.

Evaluation of quantitative parameters of dynamic contrast-enhanced magnetic resonance imaging in qualitative diagnosis of hepatic masses

BACKGROUND

To explore the value of parameters of multiphase dynamic contrast-enhanced magnetic resonance imaging (MDCE-MRI) in the qualitative diagnosis of hepatic masses.

METHODS

Eighty patients with hepatic masses were retrospectively analyzed. All the patients underwent MDCE-MRI at 3.0 T MR before treatment. Mean enhancement time (MET), positive enhancement integral (PEI), a maximum slope of increase (MSI), and a maximum slope of decrease (MSD) were measured.

RESULTS

There were significant differences between benign and malignant hepatic masses with respect to MET, PEI, and MSI values. The PEI and MSI values between hemangiomas, hepatocellular carcinomas (HCCs), cholangiocarcinomas, and metastatic tumors had significant differences. The MSD value between metastatic tumors, HCCs, and hemangiomas were significantly different. The area under the curve (AUC) values of the receiver operator characteristic curves for MET, PEI, and MSI were 0.70, 0.72, and 0.80, respectively. The specificity of MET, PEI, and MSI were all 77%, and the sensitivities of MSI was the highest, of which was 82.40%. Logistic regression analysis showed the regression equation to be P = 1/[1 + e^{0.008 × 1 + 0.007 × 2-6.707}], and taking the Youden index maximum points as a diagnostic point was 0.2946.

CONCLUSION

Some parameters of MDCE-MRI have significant roles in differentiating hepatic masses.

Hepatic sclerosed hemangioma with special attention to diffusion-weighted magnetic resonance imaging

BACKGROUND

A hepatic sclerosed hemangioma (HSH) is a very rare benign liver tumor. The correct preoperative diagnosis of HSH is very difficult because its features of imaging are similar to those of intrahepatic cholangiocarcinoma or colorectal liver metastasis.

CASE PRESENTATION

We experienced five patients who were diagnosed histologically with HSH. The preoperative diagnoses were HSH in two patients, cavernous hemangioma in one, intrahepatic cholangiocarcinoma in one, and colorectal liver metastasis in one. All patients were treated with hepatectomy (one laparoscopic and four laparotomies), and the diagnosis was completed by histological investigation of the resected specimen. In particular, we investigated the apparent diffusion coefficient (ADC) mean value using diffusion-weighted sequences of magnetic resonance imaging (DW-MRI). The average of the ADC mean (ADC_mean) value of HSH was 1.94 × 10^-3 mm²/s (range 1.73-2.10 × 10^-3 mm²/s), which was higher than the value of common malignant liver tumors. Interestingly, the ADC_mean values were almost the same between the degenerate (1.90 ± 0.17 × 10^-3 mm²/s) and the non-degenerate areas (1.95 ± 0.26 × 10^-3 mm²/s) in HSH.

CONCLUSIONS

The ADC_mean value seemed to be quite useful to preoperatively distinguish HSH from other malignant liver tumors.

Beyond hepatic hemangiomas: the diverse appearances of gastrointestinal and genitourinary hemangiomas

Hemangiomas are common lesions, best known for their appearance in the liver. Their appearance in less common locations, such as the gastrointestinal and genitourinary tracts, is less well known. We will review the typical and atypical appearance of hemangiomas in these locations on sonography, CT, and MRI.

Perilesional enhancement of liver cavernous hemangiomas in magnetic resonance imaging

OBJECTIVE

To evaluate on magnetic resonance imaging (MRI) the occurrence rate of temporal perilesional parenchymal enhancement (PPE) associated with hepatic hemangiomas in a large consecutive series and to determine which aspects are associated with this observation.

MATERIALS AND METHODS

Institutional review board approved this retrospective study. A computerized search of the MRI database was performed for consecutive patients between January 2008 and January 2012. The study population included 513 liver hemangiomas in 224 patients (104 males and 120 females; mean age of 55.2 ± 13.5 years; age range 24-89 years). Two readers independently reviewed the frequency of PPE, size, speed of enhancement and location of each hemangioma. Marginal models with generalized estimating equation were used. Wald test was applied to verify if the model coefficients were significant.

RESULTS

80/513 (15.6%) hemangiomas showed PPE. The incidence of PPE was significantly higher (p < 0.05) in hemangiomas with Type1 speed of enhancement (51/80, 63.8%) than in those with Type2 or Type3. 66/80 (82.5%) hemangiomas with PPE were subcapsular (p < 0.05). Conversely, the majority (280/433, 64.7%) of hemangiomas without PPE were deep in location (p < 0.001). Lesser proportion of hemangiomas with PPE was located in segment IVa (p < 0.05).

CONCLUSION

PPE is not uncommonly seen along with hepatic hemangiomas. This appearance is most frequently observed in rapidly enhancing small lesions with a subcapsular location.

The ins and outs of liver imaging

Different imaging modalities including ultrasonography, computed tomography (CT), and MR imaging may be used in the liver depending on the clinical situation. The ability of dedicated contrast-enhanced liver MR imaging or CT to definitively characterize lesions as benign is crucial in avoiding unnecessary biopsy. Liver imaging surveillance in patients with cirrhosis may allow for detection of hepatocellular carcinoma at an earlier stage, and therefore may improve outcome. This article reviews the different imaging modalities used to evaluate the liver and focal benign and malignant hepatic lesions, and the basic surveillance strategy for patients at increased risk for hepatocellular carcinoma.

Cavernous sinus cavernous hemangioma: imaging features and therapeutic effect of Gamma Knife radiosurgery

OBJECT

To investigate the imaging features of cavernous sinus cavernous hemangioma (CSCH) and evaluate the therapeutic effect of Gamma Knife radiosurgery (GKRS) in treatment of CSCH.

METHODS AND MATERIALS

Fifteen patients with CSCH treated by GKRS in our institute, including 6 males and 9 females, age range 20-77 years old, were analyzed retrospectively. Three of them were given craniotomies as the initial therapy. All cases had performed conventional and contrast-enhanced MRI and 5 patients underwent dynamic enhanced MRI preoperatively. In 6 cases, the multi-directional continuous data of axial, coronal and sagittal enhanced MRI were acquired. Three cases performed digital subtraction angiography (DSA) simultaneously. The diagnoses of lesions were determined mainly depending on typical imaging features. In 3 patients, the diagnoses of CSCH were confirmed histopathologically. The radiation dosimetry was done with a goal of conformal and selective coverage of the lesion with a 50% prescription isodose line. The mean marginal dose constituted 13.4 Gy (range 10-16 Gy). After GKRS was performed, all patients were arranged regular clinical and MRI follow-up every 6 months during the first 12 months, and once per year thereafter.

RESULTS

On MRI, the lesions were typically demonstrated as iso/hypo-intensities on T1WI and remarkable hyper-intensities on T2WI, and apparent homogeneous enhancement. The phenomenon of dynamic enhancement was found in 11 cases. The progressive enhancing process from heterogeneous to uniform was displayed in the 5 patients performed same-slice dynamic MRI, including imaging characteristics of 'edge to center' enhancement in 2 case. In the other 6 cases, the delayed homogeneous enhancement of lesion was observed. Ten patients obtained radiological follow-up results after GKRS. Reviewing the follow-up data of 8 patients during the period of 3-6 months, the lesions were apparently shrunk in 5 patients with shrinkage rate of 20.8-46.8%. In 4 patients with imaging follow-up during the period of 6-12 months, the lesions of 3 patients were remarkably shrunk with shrinkage rate of 53.5-81.7%. Four patients had imaging follow-up data over 12 months, and all their lesion sizes were reduced with shrinkage rate of 19-83.6%. The clinical presentations of all patients after GKRS were followed up during the period of 1-30 months. In 7 of 9 cases with headache, the symptom was improved; in 5 of 6 cases, facial hypesthesia was improved; in 6 of 9 cases with visual impairments, the visions were markedly improved; and in 8 cases with preoperative diplopia, the symptoms were all resolved.

CONCLUSION

Although bright hyper-intensities on T2WI and significant homogeneous enhancement on contrast-enhanced T1WI are considered as typical imaging characteristics of CSCH, the dynamic process of progressive delayed enhancement on contrast-enhanced MR is more persuasive in diagnosis. According to our study, GKRS could be chosen as an effective and safe alternative treatment for CSCH. We consider that using relatively low marginal dose may get better effects in tumor shrinkage and protection of cranial nerves.

MR imaging of benign focal liver lesions

Focal liver lesions (FLLs) are commonly encountered on routine imaging studies. Most lesions detected are benign, but many are indeterminate at the time of initial imaging. This article reviews the important role of MR imaging for the detection and characterization of various benign FLLs while illustrating typical imaging appearances and potential pitfalls in interpretation. The utility of diffusion-weighted imaging and hepatocyte-specific contrast agents is also discussed.

Role of Perfusion CT Differentiating Hemangiomas from Malignant Hepatic Lesions

Objective:

The purpose of the study was to determine the role of computed tomography (CT) perfusion in differentiating hemangiomas from malignant hepatic lesions.

Materials and Methods:

This study was approved by the institutional review board. All the patients provided informed consent. CT perfusion was performed with 64 multidetector CT (MDCT) scanner on 45 patients including 27 cases of metastasis, 9 cases of hepatocellular carcinoma (HCC), and 9 cases of hemangiomas. A 14 cm span of the liver was covered during the perfusion study. Data was analyzed to calculate blood flow (BF), blood volume (BV), permeability surface area product (PS), mean transit time (MTT), hepatic arterial fraction (HAF), and induced residue fraction time of onset (IRFTO). CT perfusion parameters at the periphery of lesions and background liver parenchyma were compared.

Results:

Significant changes were observed in the perfusion parameters at the periphery of different lesions. Of all the perfusion parameters BF, HAF, and IRFTO showed most significant changes. In our study we found: BF of more than 400 ml/100 g/min at the periphery of the hemangiomas showed sensitivity of 88.9%, specificity of 83.3%, positive predictive value (PPV) of 57.1%, and negative predictive value (NPV) of 96.7% in differentiating hemangiomas from hepatic malignancy; HAF of more than 60% at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3% and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy; IRFTO of more than 3 s at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3%, and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy.

Conclusion:

Perfusion CT is a helpful tool in differentiating hemangiomas from hepatic malignancy by its ability to determine changes in perfusion parameters of the lesions.

Indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography: assessment of the additional diagnostic value of contrast-enhanced ultrasound in the non-cirrhotic liver

OBJECTIVE

To assess the additional diagnostic value of contrast-enhanced ultrasound (CEUS) in the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography (CT).

METHODS

Fifty-five solid hepatic lesions (1-4 cm in diameter) in 46 non-cirrhotic patients (26 female, 20 male; age±SD, 55±10 years) underwent CEUS after being detected on contrast-enhanced CT which was considered as non-diagnostic after on-site analysis. Two blinded independent readers assessed CT and CEUS scans and were asked to classify retrospectively each lesion as a malignant or benign based on reference diagnostic criteria for the different hepatic lesion histotypes. Diagnostic accuracy and confidence (area--Az--under ROC curve) were assessed by using gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging (n=30 lesions), histology (n=7 lesions), or US follow-up (n=18 lesions) as the reference standards.

RESULTS

Final diagnoses included 29 hemangiomas, 3 focal nodular hyperplasias, 1 hepatocellular adenoma, and 22 metastases. The additional review of CEUS after CT images improved significantly (P<.05) the diagnostic accuracy (before vs after CEUS review=49% [20/55] vs 89% [49/55]--reader 1 and 43% [24/55] vs 92% [51/55]--reader 2) and confidence (Az, 95% Confidence Intervals before vs after CEUS review=.773 [.652-.895] vs .997 [.987-1]--reader 1 and .831 [.724-.938] vs .998 [.992-1]--reader 2).

CONCLUSIONS

CEUS improved the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced CT by identifying some specific contrast enhancement patterns.

Bilateral lower limb edema caused by compression of the retrohepatic inferior vena cava by a giant hepatic hemangioma

Hemangiomas are the most common benign primary tumors of the liver and their prevalence ranges from 0.4% to 20%. Approximately 85% of hemangiomas are clinically asymptomatic and are incidentally detected in imaging studies performed for other causes. In a very small minority of patients, nausea, vomiting, abdominal pain, distension, palpable mass, obstructive jaundice, bleeding, and signs and symptoms of Budd-Chiari syndrome may develop due to compression of bile duct, hepatic vein, portal vein, and adjacent organs. Occasionally, external compression of inferior vena cava may lead to edema and/or indirect symptoms such as deep vein thrombosis of the lower limbs. In this report, we present a case of giant hepatic hemangioma that completely filled the right lobe of the liver. The patient presented with bilateral lower limb edema and pain. A computed tomography scan detected a 9 × 11 × 12 cm mass indicative of a hemangioma in the right lobe of the liver that compressed the inferior vena cava. The patient refused treatment initially but returned 6 months later presenting with the same symptoms. At that time, the mass had increased in size and a hepatectomy was performed, preserving the middle hepatic vein. By postoperative month 13, the swelling in the lower extremities had decreased significantly and the inferior vena cava appeared normal.

Hepatic cavernous hemangiomas: relationship between speed of intratumoral enhancement during dynamic MRI and apparent diffusion coefficient on diffusion-weighted imaging

Objective

To investigate the relationships between the apparent diffusion coefficients (ADCs) on diffusion-weighted imaging (DWI) and the speed of contrast-enhancement in hepatic hemangiomas.

Materials and Methods

Sixty-nine hepatic hemangiomas (≥ 1 cm) were evaluated with DWI, by using multiple b values (b = 50, 400, 800 s/mm²), followed by a gadolinium-enhanced dynamic MRI. The lesions were classified into three groups, according to the speed of contrast-enhancement on the portal phase. ADCs were measured on the ADC map automatically, and were calculated by using the two different b values (mADC_50-400 with b values = 50 and 400; mADC_400-800 with b values = 400 and 800 s/mm²).

Results

The mean ADCs (× 10^-3 mm²/s) were significantly higher in the rapid group (1.9 ± 0.44) than in the intermediate (1.7 ± 0.35, p = 0.046) or the slow groups (1.4 ± 0.34, p = 0.002). There were significant differences between the rapid and the slow groups in mADC_50-400 (2.12 vs. 1.48; p = 0.008) and mADC_400-800 (1.68 vs. 1.22, p = 0.010), and between the rapid and the intermediate groups in mADC_50-400 (2.12 vs. 1.79, p = 0.049). Comparing mADC_50-400 with mADC_400-800, there was a significant difference only in the rapid group (p = 0.001).

Conclusion

Higher ADCs of rapidly-enhancing hemangiomas may be related to richer intralesional vascular perfusion. Also, the restricted diffusion may be attributed to the difference of structural characteristics of hemangioma.

Fading hepatic hemangiomas on multiphasic CT

PURPOSE

To describe fading hemangiomas [substantially lower attenuation (>30 HU) than vascular pool in the portal venous phase (PVP)] and to determine their incidence and characteristics on multiphasic CT.

METHODS

The study population composed of 168 hemangiomas (≥5 mm) in 114 consecutive patients which were imaged on multiphasic CT and also proved by diagnostic findings on MRI. The size of hemangiomas and CT attenuation number of the enhancing area within the hemangioma, liver parenchyma, and portal vein were measured on both arterial phase (AP) and PVP images. The rapidity of enhancement (slow, <50%; rapid, 50%-99%; flash-filler, 100% filling in the AP) and association with arterioportal shunting (APS) were also determined by two independent reviewers. Imaging features were compared between fading and non-fading hemangiomas using Kruskal-Wallis test.

RESULTS

Of 168 hemangiomas, the enhancing area of 27 hemangiomas (16%, 27/168) showed substantially lower attenuation than that of PV (fading) in the PVP. When the attenuation difference was compared with the rapidity of enhancement, flash-fillers showed lower attenuation than PV in the PVP more frequently than both slow-fillers (P < 0.05) and rapid-fillers (P < 0.05). The proportion of fading hemangiomas was 52% (14/27) in flash-fillers, much more frequent than in rapid-fillers (4/27, 15%) as well as slow-fillers (9/27, 33.3%). The size of fading hemangiomas (17.9 ± 4.5 mm) was significantly smaller than that of non-fading (24.2 ± 3.6 mm) (P = 0.032). Although APS was more frequent in fading hemangiomas (55.6%, 15/27) than that of non-fading hemangiomas (37.6%, 53/141), there was no statistically significant difference (P = 0.086).

CONCLUSIONS

Sixteen percentage (27/168) of the hemangiomas in our study showed substantially lower attenuation than the portal vein in the PVP CT and this was more frequent in flash-fillers (52%, 14/27). The knowledge that fading does not preclude the diagnosis of hemangioma as well as of its high incidence in flash-fillers is important, as flash-filling hemangiomas with fading may cause a diagnostic challenge in patients suspected to have hypervascular malignancy.

Is hepatotropic contrast enhanced MR a more effective method in differential diagnosis of hemangioma than multi-phase CT and unenhanced MR?

BACKGROUND

Cavernous hemangiomas are the most frequent neoplasms of the liver and in routine clinical practice they often need to be differentiated from malignant tumors and other benign focal lesions. The purpose of this study is to evaluate whether diagnostic accuracy of magnetic resonance imaging (MRI) of hepatic hemangiomas, showing atypical pattern on US, improves with the use of Gd-BOPTA in comparison with contrast-enhanced multi-phase computed tomography (CT).

METHODS

178 consecutive patients with ambiguous hepatic masses showing atypical hyperechoic pattern on grey-scale US, underwent unenhanced and contrast-enhanced multi-phase multi-detector CT and MR (1.5T) with the use of liver-specific contrast medium gadobenate dimeglumine (Gd-BOPTA). After intravenous contrast administration arterial (HAP), venous-portal (PVP), equilibrium phases (EP) both in CT and MR and additionally hepatobiliary phase (HBP) in MR were obtained. 398 lesions have been detected including 99 hemangiomas and 299 other lesions.

RESULTS

In non-enhanced MDCT examination detection of hemangiomas was characterized by sensitivity of 76%, specificity of 90%, PPV of 71%, NPV of 92% and accuracy of 86%.Non-enhanced MR examination showed sensitivity of 98%, specificity of 99%, PPV of 99%, NPV of 99% and accuracy of 99%.After intravenous administration of contrast medium in MR the mentioned above parameters did not increase significantly.

CONCLUSION

Gd-BOPTA-enhanced MR in comparison with unenhanced MRI does not improve diagnostic accuracy in discriminating hemangiomas that show non-specific appearance in ultrasound examination. Unenhanced MR as a method of choice should directly follow US in course of diagnostic algorithm in differentiation of hemangiomas from other liver tumors.

Use of two-dimensional multiple-slice magnetic resonance hydrography for diagnosis of hepatic hemangiomas and cysts

BACKGROUND/PURPOSE

Although hepatic hemangiomas and cysts display very high signal intensities on conventional T2 images, their appearances are quite distinct using magnetic resonance hydrography (MRH). We examined the feasibility of using MRH in distinguishing hepatic cysts from hemangiomas.

METHODS

We recruited 97 patients with hepatic hemangiomas and 65 with hepatic cysts. All patients underwent magnetic resonance imaging (including two-dimensional multiple slice MRH, TR/TE: 8000/800) and the results were reviewed independently by two radiologists. The signal intensities of the lesions were measured. For each lesion, the variation in signal to noise ratio between MRH and the fat-saturated T2-weighted images was calculated, and the results were validated using a receiver operating characteristic curve.

RESULTS

There was a significant difference between the signal to noise ratio of hepatic hemangiomas and cysts using MRH (p < 0.001). This difference could be identified by visual inspection. The receiver operating characteristic curve revealed that the ideal cut-off value for the signal intensity reduction ratio between hepatic cysts and hemangiomas was -0.1. Using this ratio, the derived sensitivity was 95.4%, specificity 99.0%, and accuracy 99.7%.

CONCLUSION

Hepatic hemangiomas and cysts have significantly different signal intensities on non-contrast two-dimensional multiple-slice MRH. This approach uses a non-invasive, reliable, and accurate imaging technique to differentiate the two diagnoses.

Hemangioma hepático subcapsular com realce perilesional: achados de RM

OBJETIVO: Descrever os achados de imagem de RM no hemangioma hepático com realce perilesional. MATERIAIS E MÉTODOS: Realizou-se uma pesquisa no banco de dados da unidade de RM para identificar todos os casos de hemangioma hepático com realce perilesional entre março de 2008 e julho de 2009. Todos os pacientes foram submetidos a RM pré-contraste em imagens ponderadas em T1 e T2 e em imagens dinâmicas após injeção de gadolínio. Características do hemangioma e do realce perilesional foram avaliadas nas imagens de RM. RESULTADOS: Sete hemangiomas em sete pacientes (cinco homens, duas mulheres; faixa etária entre 41-69 anos; média de 57 anos) foram incluídos no presente estudo. O tamanho das lesões variou de 7 a 20 mm (média de 12,4 mm). Na fase dominante arterial hepática, todos os sete hemangiomas mostraram realce perilesional cuneiforme que se atenuou nas imagens dois minutos após injeção de gadolínio. Quatro dessas lesões demonstraram realce capsular adjacente. CONCLUSÃO: Todos os hemangiomas hepáticos com realce perilesional eram lesões capsulares medindo menos que 2 cm. Tal localização sugere que esses hemangiomas podem recrutar vasos capsulares responsáveis pelo realce perilesional

Acoustic radiation force impulse elastography for the evaluation of focal solid hepatic lesions: preliminary findings

This study was designed to investigate the potential usefulness of acoustic radiation force impulse (ARFI) elastography to evaluate focal solid hepatic lesions. In total, 51 patients with 60 focal hepatic lesions, which included 17 hemangiomas, 25 hepatocellular carcinomas (HCCs), 15 metastases and three cholangiocarcinomas, underwent ARFI elastography. The lesions were classified into three groups: Group I consisted of metastatic liver tumors and cholangiocarcinomas, group II consisted of HCCs and group III consisted of hemangiomas. The stiffness and conspicuity of the tumors as depicted on ARFI elastography and the echogenicity and conspicuity of the tumors on corresponding B-mode images were analyzed. Shear wave velocity was obtained to quantify stiffness for 36 focal hepatic lesions: 11 hemangiomas, 17 HCCs and eight other malignant lesions. On ARFI elastography images, group I tumors (n=18) appeared stiffer than the background liver for 13 lesions (72%), softer for two lesions and had identical stiffness in three lesions compared with the background liver. For group II tumors (n=25), 13 lesions (52%) appeared stiffer than the liver, six lesions appeared softer than the liver and the remaining six lesions showed the same stiffness as the liver. For group III tumors (n=17), six lesions (35%) appeared stiffer than the liver, seven lesions appeared softer and the remaining four lesions showed the same stiffness as the liver. There were no statistical differences among the three groups in terms of tumor stiffness as seen on ARFI elastography images (p>0.05). Of the 60 lesions, 41 (68%) displayed a clearer or equivalent margin on the ARFI elastography compared with that seen on B-mode images. The shear wave velocities were: Group I, 2.18+/-0.96 m/s (mean value+/-SD); group II, 2.45+/-0.81m/s; group III, 1.51+/-0.71 m/s (p=0.012). With a cut-off value of 2m/s for the shear wave velocity, the positive predictive value and specificity for malignancy were 89% and 81%, respectively. Images obtained with ARFI elastography provided additional qualitative information regarding the stiffness and tumor margin of liver tumors. By measuring shear wave velocity, quantification of stiffness was made possible and showed the potential to differentiate malignant hepatic tumors from hepatic hemangiomas.

Nontumorous arterioportal shunts in the liver: CT and MRI findings considering mechanisms and fate

The intrahepatic non-tumorous arterioportal shunt (APS) is one of the important causes of transient hepatic enhancement differences (THED) on dynamic CT or MRI. Most small APSs are located in the peripheral portion of the liver. Because of the parenchymal distortion in the advanced cirrhotic liver, many small APSs tend to show an amorphous or nodular appearance, making them difficult to distinguish from hypervascular tumors. In addition to the use of dynamic CT or MRI, iso-attenuation densities or iso-intensities on pre-contrast and equilibrium phases, MRI using a liver-specific contrast agent can be useful to characterize the hypervascular pseudolesions. Because there is no difference in water diffusion in the hepatic parenchyma in the region of the APS, diffusion-weighted MRI also has great potential to distinguish non-tumorous shunts from true focal lesions. Larger (>2 cm) APSs of direct arterio-portal venous fistulas from extrinsic insults show typical subcapsular wedge-like THEDs that are only temporarily depicted several months after the traumatic event; most of these THEDs gradually decrease in size or vanish completely. By understanding the nature of non-tumorous APSs, radiologists will be able to provide a more accurate assessment of many THEDs during daily interpretations of CT or MR images of the liver.

Undetermined focal liver lesions on gray-scale ultrasound in patients with fatty liver: characterization with contrast-enhanced ultrasound

BACKGROUND AND AIM

The purpose of this study was to assess the clinical value and potential impact of contrast-enhanced ultrasound (CEUS) in the characterization of undetermined focal liver lesions (FLLs) in patients with fatty liver.

METHODS

Fifty-two patients (34 men, 18 women) with fatty liver with 67 FLLs (size range, 1-8.6 cm; mean, 4.1 +/- 3.1 cm) undetermined at baseline ultrasound (US) underwent contrast-enhanced US. CEUS examinations were analyzed by two experienced sonologists blinded to the final diagnosis. Readers evaluated by consensus the baseline echogenicity, the dynamic enhancement pattern in comparison with peripheral liver parenchyma. The final diagnosis was based on consensus interpreting of all examinations by another two expert observers with access to histological data. The characterization accuracy, sensitivity, and specificity of CEUS in characterizing the lesion as benign or malignant, and as the correct pathologic type, were analyzed.

RESULTS

After CEUS, two hemangiomas, three inflammatory pseudotumors, and one hepatocellular carcinoma were misdiagnosed. The overall characterization accuracy, sensitivity and specificity of CEUS were 91% (61/67), 91.7% (11/12), and 90.9% (50/55), respectively. Forty-three benign lesions were diagnosed as the correct pathologic type. The portal venous phase and late phase were important in the characterization of the lesions. The characterization accuracy had no relationship with the size of FLLs.

CONCLUSION

CEUS can improve the characterization of undetermined FLLs arising from fatty liver.

Dynamic enhancement features of cavernous sinus cavernous hemangiomas on conventional contrast-enhanced MR imaging

BACKGROUND AND PURPOSE

The reported MR imaging characteristics of cavernous sinus cavernous hemangiomas (CSCHs) in the literature are nonspecific. The purpose of our study was to explore dynamic enhancement features of CSCHs on conventional contrast-enhanced MR imaging and to correlate these features with histopathologic subtypes.

MATERIALS AND METHODS

Twenty-one patients (8 male and 13 female; age range, 13-63 years; average age, 42.6 years) with surgically confirmed CSCHs were retrospectively investigated. Preoperative MR study was performed in all cases, consisting of T1-weighted axial imaging, T2-weighted axial imaging, T1-weighted sagittal imaging, and contrast-enhanced T1-weighted axial, sagittal, and coronal images.

RESULTS

There were 4.8% (1/21) that showed homogeneous enhancement on all 3 contrast-enhanced sequences, whereas 95.2% (20/21) demonstrated heterogeneous enhancement on the first contrast-enhanced sequence. Among the 20 lesions, on subsequent contrast-enhanced sequences, 55.0% (11/20) showed homogeneous enhancement, whereas 35.0% (7/20) of lesions showed progressive contrast "filling in." The remaining 10% (2/20) exhibited no apparent enhancement changes. The 95.2% (20/21) of lesions with heterogeneous enhancement on the first contrast-enhanced sequence correlated with type B or type C pathologic findings, whereas 4.8% (1/21) with homogeneous enhancement correlated with type A pathologic findings. Among the 20 type B or type C lesions, 80% (16/20) achieved total or near-total resection.

CONCLUSION

Progressive contrast "filling in" in the tumors on conventional contrast-enhanced MR images can aid in differentiating between cavernous sinus lesions and suggest the diagnosis of cavernous hemangiomas.

Research progress on transient hepatic peritumoral enhancement

Multi-slice computed tomography (MSCT) has been widely used in the clinical examination for livers. CT can not only complete scanning in a short time, but also achieve multi-phase scanning, so MSCT has unique advantages in the diagnosis of abnormal hepatic perfusion, showing as transient hepatic peritumoral enhancement (THPE). Based on this, in combination with the mechanism of THPE, the image characteristics of MSCT and clinical data, MSCT can make great contribution to identify the causes of THPE and diagnose the lesion property.

Contrast-enhanced ultrasound of histologically proven liver hemangiomas

Differentiation of small and atypical hemangiomas from other hepatic masses using imaging methods can be difficult, especially in patients with underlying malignant disease. Therefore, contrast-enhanced ultrasound was assessed in patients with histologically confirmed hemangiomas with respect to contrast-enhancing kinetics and tumor characteristics. In 58 patients with indeterminate hepatic lesions demonstrated with at least 2 imaging methods (ultrasound/computed tomography/magnetic resonance imaging), ultrasound-guided liver biopsy revealed hemangioma. In all patients a hepatic neoplasm had been suspected because of underlying malignant disease (n=41), liver cirrhosis (n=15), or growth of the lesion (n=2). All patients underwent nonlinear, low mechanical index real-time contrast-enhanced ultrasound scanning with bolus injections of SonoVue. Peripheral nodular arterial enhancement was detected in 43 patients (74%), whereas the typical metastatic peripheral rim-like enhancement was not observed at all. Strong homogenous arterial enhancement was found in 9 of 58 (16%) patients. In 6 patients (10%), the arterial contrast enhancement pattern could not be determined because of the very small size of the lesions or fibrotic nodules. Forty-five (78%) of the hemangiomas showed homogenous centripetal filling within 180 seconds.

CONCLUSION

Contrast-enhanced ultrasound demonstrates typical hemangioma imaging characteristics, that is, peripheral nodular contrast enhancement and iris-diaphragm sign in a high percentage of patients with undetermined lesions. This technique may therefore improve noninvasive functional characterization and differentiation of hemangiomas.

Analysis of neuroendocrine tumour metastases in the liver using contrast enhanced ultrasonography

BACKGROUND

Imaging of liver tumours might be improved by contrast-enhanced ultrasonography, which allows much better demonstration of the microvascular system. The aim of this study was to assess the sonographic morphology and vascularity of neuroendocrine liver metastases.

METHODS

Forty-eight patients with histologically proven neuroendocrine tumours (NET) and suspected liver metastases--as well as 50 consecutive patients with liver metastases of other origins--were included in a prospective study to evaluate tumour characteristics using B-mode, colour Doppler (CDI) and contrast-enhanced ultrasound (CEUS).

RESULTS

In 4/48 patients with NET, liver biopsy revealed hemangiomas. The typical B-mode appearance was that of both echo-rich and echo-poor combined, also inhomogeneous depending on the size, and often centrally cystic. With CDI, neuroendocrine metastases appeared hypervascular (66%) or isovascular (34%). Metastases of another origin were hypovascular in 82%. With CEUS, neuroendocrine metastases showed increased arterial enhancement in 38 patients and hypoechoic appearance in the portalvenous phase in 39 patients. In liver metastases of another origin, the sensitivity for malignancy due to a hypoechoic appearance during the portalvenous phase was 100%. In liver metastases of NET origin the sensitivity for malignancy was 39/48 (82%).

CONCLUSIONS

Neuroendocrine tumour metastases might show characteristics which are similar to hemangiomas. In patients with liver cirrhosis and severe fatty liver disease the identification of NET with CEUS as a malignant lesion is more difficult. The sensitivity of CEUS in identifying malignancy based on the lack of portalvenous enhancement is higher for metastases of other origin.

Gadolinium-enhanced multiphasic 3D MRI of the liver with prospective adaptive navigator correction: phantom study and preliminary clinical evaluation

OBJECTIVE

The purpose of this study was to determine whether prospective adaptive navigator correction improves slice position invariability while maintaining image quality and enables efficient cine display observation on gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver.

MATERIALS AND METHODS

The study consisted of two parts: a phantom study and a clinical study. To explore the effect of navigator correction, a phantom was imaged in the resting state and in continuous movement. In the clinical study, gadolinium-enhanced four-phase 3D spoiled turbo field-echo images (3-mm thickness with no intersectional gap, 60 slices for whole liver) were retrospectively assessed. The subjects were 83 patients with 130 focal hepatic lesions randomized into two groups: with (n = 45) and without (n = 38) navigator correction. Images were qualitatively assessed by two blinded radiologists using a three-point slice position invariability scale for liver and focal hepatic lesions. Image degradation due to motion or artifacts was qualitatively assessed.

RESULTS

Phantom images were obtained with excellent slice position invariability while image quality was maintained with navigator correction. Navigator correction substantially degraded the quality of the images of two patients (one with a large amount of ascites and the other with a large hepatic cyst). In the other 81 patients, the degree of slice position invariability for the liver was greater (p < 0.001) with (score, 2.84 +/- 0.43 [SD]) than without (score, 2.37 +/- 0.75) navigator correction. For focal hepatic lesions, slice position invariability also was greater (p < 0.0001) with (score, 2.95 +/- 0.21) than without (score, 2.18 +/- 0.88) navigator correction. No difference in degree of image degradation was found with or without navigator correction.

CONCLUSION

Prospective navigator correction improves slice position invariability for cine display observation while preserving image quality for gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver.

Liver haemangioma: common and uncommon findings and how to improve the differential diagnosis

Haemangiomas are common focal liver lesions, generally detected in the work-up of asymptomatic patients. From the pathological point of view, they can be classified as small (capillary) or large, with cavernous vascular spaces that may show thrombosis, calcifications and hyalinisation. The polymorphic imaging appearance of haemangiomas depends on their histological features and flow pattern. The widespread use of cross-sectional imaging has allowed an increased detection rate and a better characterisation of this benign tumour. Recent developments of ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) providing high spatial and temporal resolution, together with the use of new contrast agents and/or pulse sequences has broadened the spectrum of imaging findings, contributing to diagnostic refinement in difficult cases. The scope of the present article is to provide an overview of the range of appearances of haemangiomas, explored with recent cross-sectional imaging modalities, emphasising its atypical findings as explored by temporally resolved contrast-enhanced imaging.

Hepatic perfusion disorders: etiopathogenesis and related diseases

In this article, we have reviewed the hepatic perfusion disorder (HPD), etiopathogenesis of HPD and corresponding diseases. Review of the literature was based on computer searches (PubMed, Index Medicus) and personal experiences. We considered HPD reflects perfusion differences due to redistribution of arterial blood flow among segments, subsegments and lobes of the liver. The plain CT scan findings of HPD manifests as triangular or wedge-shaped areas of low attenuation. On contrast-enhanced CT scan, HPD manifests multiple (or single) transient wedge-shaped, rotundloid or irregular appearance, homogeneous hyperattenuation (in less cases, hypoattenuation) during the hepatic arterial phase (HAP) and isoattenuated or slightly hyperattenuated areas during the portal arterial phase. Dynamic enhanced magnetic resonance (MR) features are similar to enhanced CT scan. Angiographic findings include non-opacification of portal vein on portograms or wedge-shaped segmental staining in arterial and parenchymal phases on hepatic angiograms. The causes of HPD are arterioportal shunts (APS), intrahepatic vascular compressions and portal vein occlusion, steal phenomenon by hypervascular tumors, vascular variations and any other unknown reasons. It is very important for radiologists to be familiar with the various appearances of HPD to avoid false-positive diagnosis of pseudolesions and not to overestimate the extent of the disease.

Hepatic metastases: perilesional enhancement on dynamic MRI

OBJECTIVE

Our purpose was to determine whether the perilesional parenchymal enhancement of hepatic metastases could be correlated with tumoral enhancement on arterial phase images or tumor size on dynamic MRI.

MATERIALS AND METHODS

One hundred thirty-four lesions of hepatic metastases in 44 patients were subjected to a retrospective analysis of the dynamic MR images obtained with 3D spoiled gradient-echo sequences. The thickness of the enhancing rim on arterial phase images was regarded as a summation of the enhancing component of tumor periphery and perilesional enhancement, which were estimated by the tumor size on precontrast T1-weighted images. The presence of wedge-shaped perilesional enhancement was also correlated with the lesion size.

RESULTS

Except for 17 diffusely enhanced lesions, lesion size was comparable between the lesions with (n = 87; 26 +/- 19 [SD] mm) and without rim enhancement (n = 30; 27 +/- 23 mm) on the arterial phase dynamic MR images (p > 0.05). The degree of peripheral tumoral enhancement showed an inverse correlation (r = -0.389) with the thickness of the circumferential perilesional enhancement (p < 0.001). The mean size of the lesions with wedge-shaped perilesional enhancement (n = 44; 33 +/- 20 mm) was larger than that of the other lesions (n = 90; 25 +/- 19 mm) (p = 0.016).

CONCLUSION

The degree of circumferential perilesional enhancement of hepatic metastases on arterial phase dynamic MR images would be independent of the lesion size but inversely correlated with the degree of peripheral tumoral vascularity. An understanding of these features may help tumor characterization and should prompt hypotheses and studies of microvascular phenomena in tumoral and epitumoral environments.

Hepatic perfusion disorders: Etiopathogenesis and related diseases

In this article, we have reviewed the hepatic perfusion disorder (HPD), etiopathogenesis of HPD and corresponding diseases. Review of the literature was based on computer searches (PubMed, Index Medicus) and personal experiences. We considered HPD reflects perfusion differences due to redistribution of arterial blood flow among segments, subsegments and lobes of the liver. The plain CT scan findings of HPD manifests as triangular or wedge-shaped areas of low attenuation. On contrast-enhanced CT scan, HPD manifests multiple (or single) transient wedge-shaped, rotundloid or irregular appearance, homogeneous hyperattenuation (in less cases, hypoattenuation) during the hepatic arterial phase (HAP) and isoattenuated or slightly hyperattenuated areas during the portal arterial phase. Dynamic enhanced magnetic resonance (MR) features are similar to enhanced CT scan. Angiographic findings include non-opacification of portal vein on portograms or wedge-shaped segmental staining in arterial and parenchymal phases on hepatic angiograms. The causes of HPD are arterioportal shunts (APS), intrahepatic vascular compressions and portal vein occlusion, steal phenomenon by hypervascular tumors, vascular variations and any other unknown reasons. It is very important for radiologists to be familiar with the various appearances of HPD to avoid false-positive diagnosis of pseudolesions and not to overestimate the extent of the disease.

Nonspecificity of the fat-sparing ring surrounding focal liver lesion at MR imaging

RATIONALE AND OBJECTIVES

The presence of a fat-sparing ring surrounding focal liver lesions in patients with steatosis has been described only in malignant lesions. Our purpose is to evaluate whether this fat-sparing ring peripheral to tumors is a specific marker of malignancy.

MATERIALS AND METHODS

From 300 magnetic resonance examinations of focal liver lesions, 132 patients with a confirmed nature of the lesions were selected. There were 24 patients (18.2%) with lesions having a perilesional fat-sparing ring in the opposed-phase spoiled T1-weighted gradient echo images. All these livers had steatosis.

RESULTS

Perilesional fat-sparing rings were observed in 19 (21.6%) malignant and 5 (11.4%) benign lesions. Size of the lesion was not related to the presence of the fat-sparing ring (P=.6), neither was type of lesion (malignant versus benign) statistically related to the presence of the perilesional fat-sparing ring in the opposed-phase gradient echo magnetic resonance images (chi-square, P=.15). Fat-sparing rings were mainly seen in metastases (51.4% of metastases), but seldom in primary malignant tumors (1.9% of hepatocellular carcinomas). Hemangiomas also presented this finding (18.5% of hemangiomas).

CONCLUSIONS

We believe that the presence of this bright rim surrounding lesions on oppose-phase images in patients with steatosis mainly represent decrease portal flow, either because of compressed and atrophic hepatocyte cords with sinusoidal congestion in expanding metastatic lesions or the presence of arterioportal perfusion abnormalities in vascularized hemangiomas.

Liver masses

In summary, MR imaging is superior to other imaging modalities, including CT, for the work-up of liver masses. The current challenge is whether the superior performance of MR imaging translates into a beneficial effect on patient management, disease outcome, and health care costs. New MR sequences, phased-array surface coils, and tissue-specific MR contrast agents suggest that MR imaging may exceed further the diagnostic ability of CT.

Peritumoral fat-spared area is well correlated with the presence of temporal peritumoral enhancement in hepatic hemangioma in fatty liver

PURPOSE

To assess the relationship between temporal peritumoral enhancement and peritumoral focal fat sparing adjacent to hepatic hemangiomas.

MATERIALS AND METHODS

On the basis of MRI and sonographic imaging follow-up, 51 hepatic hemangiomas were identified in 37 patients, who had both hepatic hemangiomas and focal fat-sparing areas in fatty liver. Among them, 36 tumors were associated with peritumoral focal fat spares. The association between the temporal peritumoral enhancement in the early arterial phase of dynamic MRI and peritumoral fat sparing in the same hemangioma was investigated. Furthermore, the configuration of the temporal peritumoral enhancement was correlated with that of the peritumoral focal fat-sparing area. We used Chi square and Fisher's exact test for statistic analysis.

RESULTS

A total of 31 out of 36 hemangiomas (86.1%) showed both peritumoral focal fat spares and temporal peritumoral enhancement. The presence of temporal peritumoral enhancement is significantly related to that of peritumoral focal fat-sparing (P < 0.001). A total of 21 of the 31 tumors (67.7%) presented with similar configuration of the peritumoral focal fat-sparing area and temporal peritumoral enhancement area with respect to size and shape. The remaining 10 hemangiomas showed similar shape but slightly different size in these two imaging characteristics.

CONCLUSION

Temporal peritumoral enhancement seen in hepatic hemangioma might be related to focal fatty sparing adjacent to the hemangiomas.

Arterioportal shunt: prevalence in small hemangiomas versus that in hepatocellular carcinomas 3 cm or smaller at two-phase helical CT

PURPOSE

To compare the prevalence of arterioportal (AP) shunting associated with (a) small (< or =3 cm) hemangiomas and (b) hepatocellular carcinomas (HCCs) (< or =3 cm) at two-phase helical computed tomography (CT).

MATERIALS AND METHODS

Two-phase helical liver CT was performed in 107 patients (61 men, 46 women; age range, 25-73 years; mean, 48.6 years) with 169 small hemangiomas and in 384 patients (292 men, 92 women; age range, 18-82 years; mean, 58.3 years) with 598 HCCs 3 cm or smaller. Diagnosis of HCC was verified with histologic findings (n = 30) or typical imaging and clinical findings (n = 568); that of all hemangiomas was verified with typical imaging and clinical findings. Three radiologists retrospectively reviewed all CT images in consensus. Contrast material-enhanced CT scans were obtained during the hepatic arterial and portal venous phases. AP shunt was considered to be present when wedge-shaped or irregularly shaped homogeneous enhancement peripheral to tumor appeared at hepatic arterial phase CT and isoattenuation or slight hyperattenuation in that area appeared at portal phase CT. The prevalence of AP shunting associated with hemangiomas and that associated with HCCs were compared with multivariate model testing. Speed of lesion enhancement (rapid enhancement, when extent of intratumoral enhancement at hepatic arterial phase CT was >50%; slow enhancement, when extent of intratumoral enhancement was < or =50%) and presence of AP shunt were correlated with chi2 or Fisher exact testing.

RESULTS

AP shunts were more frequently found in hemangiomas (36 lesions [21.3%]) than in HCCs (25 lesions [4.2%]) (P <.001). Twenty-four (38%) of the 64 hemangiomas with rapid enhancement had AP shunts, whereas only 12 (11.4%) of the 105 hemangiomas with slow enhancement had AP shunts (P <.001). There was no significant difference between prevalence of AP shunt in the 573 HCCs with rapid enhancement (24 lesions, 4.2%) and that in the 25 HCCs with slow enhancement (one lesion, 4.0%).

CONCLUSION

AP shunts were more frequently seen at two-phase helical CT in small hepatic hemangiomas than in HCCs and thus represent a suggestive but not specific finding of hemangioma. Small hemangiomas with AP shunts tend to show rapid rather than slow enhancement.

Temporal Peritumoral Enhancement of Hepatic Cavernous Hemangioma

OBJECTIVE

To evaluate the occurrence rate of temporal peritumoral enhancement associated with hepatic cavernous hemangiomas and to correlate that with the speed of intratumoral contrast enhancement and tumor volume.

METHODS

Dynamic magnetic resonance imaging (MRI) of 69 consecutive patients with 136 hemangiomas was reviewed for peritumoral enhancement. Tumor volume was estimated by the largest diameter on T2-weighted images. Speed of intratumoral contrast enhancement was determined by portal phase image and was categorized as rapid (>75% of tumor volume), intermediate (25%-75% of tumor volume), or slow (<25% of tumor volume).

RESULTS

Temporal peritumoral enhancement was found in 37 (26.6%) of 136 hemangiomas. It was more common in hemangiomas with rapid enhancement (30 of 67 cases [44.8%]) than in those with intermediate (3 of 22 cases [13.6%]) and slow (4 of 47 cases [8.5%]) enhancement (P < 0.05). There was no statistically significant relation between lesion size and presence of temporal peritumoral enhancement (P > 0.05).

CONCLUSIONS

Temporal peritumoral enhancement is not uncommonly seen in hepatic cavernous hemangiomas at dynamic MRI. It is most commonly encountered in rapidly enhancing small lesions. There is no statistically significant relation between temporal peritumoral enhancement and tumor volume, however.

Magnetic resonance imaging of arterioportal shunts in the liver

Localized perfusional variations are being seen more frequently in magnetic resonance imaging (MRI) as the increased reliance of the optimized arterial-phase contrast-enhanced strategies has become more commonplace. Many of these findings are related to the various organic or functional arterioportal shunts in the liver. The associated alterations in physiologic flow, decreased or absent portal venous flow, and increased arterial flow result in a regional display of high signal intensity on arterial-phase dominant contrast-enhanced MRI. For accurate diagnosis and planning of patient management, the etiology of the shunt should be distinguished as tumor related or not, and it may need to be differentiated from a hypervascular tumor. Depending on the chronicity of diminished portal flow, substantial parenchymal changes may ensue, including focal fat sparing or the finding of functional infarct, either of which can be demonstrated on static MRI. This article reviews and illustrates the MRI findings of localized tumor-related and nontumorous arterioportal shunts in the liver.

Transient peritumoral enhancement during dynamic MRI of the liver: cavernous hemangioma versus hepatocellular carcinoma

PURPOSE

The purpose of this work was to compare the incidence and pattern of transient peritumoral parenchymal enhancement for cavernous hemangioma and hepatocellular carcinoma during dynamic MRI of the liver.

METHOD

Two hundred seven hemangiomas and 155 hepatocellular carcinomas up to 4 cm in size were retrospectively assessed. The peritumoral enhancement was comparatively analyzed in terms of the shape, extent, signal intensity, and dependence on the size and degree of contrast enhancement of each tumor.

RESULTS

For small lesions (<2 cm), hemangiomas (16/141; 11.3%) showed a higher incidence (p = 0.026) of peritumoral enhancement than hepatocellular carcinomas (3/87; 3.5%). For larger lesions (2-4 cm), there was no significant difference (p > 0.05) in the incidence of peritumoral enhancement of hemangiomas (15/66; 22.7%) and hepatocellular carcinomas (15/68; 22.1%). Nineteen (61.3%) of the 31 hemangiomas showed contrast agent filling the entire tumor volume at the phase of peritumoral enhancement.

CONCLUSION

In spite of the limited specificity, for a <2 cm small focal lesion with homogeneous contrast enhancement on early phase dynamic MR images in the liver, peritumoral enhancement could suggest a higher possibility of hemangioma rather than hepatocellular carcinoma.

MR imaging of hepatocellular carcinoma

In this article, MR imaging features of hepatocellular carcinoma (HCC) are described. To better understand the MR imaging features of HCC, recent progress regarding its etiology, treatment, carcinogenesis, histology, and gross pathology will be described. Currently, T2-weighted fast spin-echo with fat saturation, and multiphasic dynamic gadolinium-enhanced two-dimensional and three-dimensional T1-weighted gradient echo imaging provides excellent results for detection and characterization of HCC.