The value of gadobenate dimeglumine-enhanced hepatobiliary-phase MR imaging for the differentiation of scirrhous hepatocellular carcinoma and cholangiocarcinoma with or without hepatocellular carcinoma

Predictive factors of microvascular invasion in patients with intrahepatic mass-forming cholangiocarcinoma based on magnetic resonance images

PURPOSE

The aim of this retrospective study was to develop and validate a preoperative nomogram for predicting microvascular invasion (MVI) in patients with intrahepatic mass-forming cholangiocarcinoma (IMCC) based on magnetic resonance imaging (MRI).

METHODS

In this retrospective study, 224 consecutive patients with clinicopathologically confirmed IMCC were enrolled. Patients whose data were collected from February 2010 to December 2020 were randomly divided into the training (131 patients) and internal validation (51 patients) datasets. The data from January 2021 to November 2021 (42 patients) were allocated to the time-independent validation dataset. Univariate and multivariate forward logistic regression analyses were used to identify preoperative MRI features that were significantly related to MVI, which were then used to develop the nomogram. We used the area under the receiver operating characteristic curve (AUC) and calibration curve to evaluate the performance of the nomogram.

RESULTS

Interobserver agreement of MRI qualitative features was good to excellent, with κ values of 0.613-0.882. Multivariate analyses indicated that the following variables were independent predictors of MVI: multiple tumours (odds ratio [OR]) = 4.819, 95% confidence interval [CI] 1.562-14.864, P = 0.006), ill-defined margin (OR = 6.922, 95% CI 2.883-16.633, P < 0.001), and carbohydrate antigen 19-9 (CA 19-9) > 37 U/ml (OR = 2.890, 95% CI 1.211-6.897, P = 0.017). A nomogram incorporating these factors was established using well-fitted calibration curves. The nomogram showed good diagnostic efficacy for MVI, with AUC values of 0.838, 0.819, and 0.874 for the training, internal validation, and time-independent validation datasets, respectively.

CONCLUSION

A nomogram constructed using independent factors, namely the presence of multiple tumours, ill-defined margins, and CA 19-9 > 37 U/ml could predict the presence of MVI. This can facilitate personalised therapeutic strategy and clinical management in patients with IMCC.

Variant Hepatocellular Carcinoma Subtypes According to the 2019 WHO Classification: An Imaging-Focused Review

The 2019 5th edition of the WHO Classification of Digestive System Tumors estimates that up to 35% of hepatocellular carcinomas (HCCs) can be classified as one of eight subtypes defined by molecular characteristics: steatohepatitic, clear cell, macrotrabecular massive, scirrhous, chromophobe, fibrolamellar, neutrophil-rich, and lymphocyte-rich HCC. Due to their distinct cellular and architectural characteristics, these subtypes may not display the classic MRI features of HCC of arterial phase hyperenhancement (APHE) and washout appearance, creating challenges in noninvasively diagnosing such lesions as HCC. Moreover, certain subtypes with atypical imaging features have a worse prognosis than other HCCs. A range of distinguishing imaging features may help raise suspicion that a liver lesion represents one of these HCC subtypes. In this review, we describe the MRI features that have been reported in association with various HCC subtypes according to the 2019 WHO classification, with attention to current understanding of these subtypes' pathologic and molecular bases and relevance to clinical practice. Imaging findings that differentiate the subtypes from benign liver lesions and non-HCC malignancies are highlighted. Familiarity with these subtypes and their imaging features may allow the radiologist to suggest their presence, though histologic analysis remains needed to establish the diagnosis.

Scirrhous Hepatocellular Carcinoma: Systematic Review and Pooled Data Analysis of Clinical, Radiological, and Histopathological Features

Background

Aberrant subtypes of hepatocellular carcinoma (HCC) account for 20–30% of all HCCs and habitually present a challenge in diagnosis and treatment. Scirrhous hepatocellular carcinoma (s-HCC) is often misdiagnosed as cholangiocarcinoma, fibrolamellar hepatocellular carcinoma, or metastasis.

Methods

Electronic databases (PubMed, Web of Knowledge, Google Scholar, Cochrane Library, and WHO International Clinical Trials Registry Platform) were searched for publications on scirrhous hepatocellular carcinoma without date or language restrictions. Quality assessment was performed using a tool proposed by Murad et al for case reports and series. For observational studies, MINORS quality assessment tool was used. This study was registered at PROSPERO (CRD42020212323).

Results

S-HCC arises in patients with chronic hepatitis (hepatitis B in 60% and hepatitis C in 21%). S-HCC primarily affects men with a mean age of 55.8 years. Serum AFP is elevated above 20IU/mL in 66.7% of the patients. On ultrasound, s-HCC presents as hypoechoic or mosaic pattern lesions (47.6% each) and causes a retraction of the liver surface (70%) when near the capsule. Delayed enhancement of the tumor is evident in 87.0%. On MRI, 65.0% of s-HCCs show a target appearance. Histopathologic pattern is mostly irregular (97.6%). Lesions show a bulging appearance (100%), septae (85.6%) and a central scar (63.5%), and usually lack central necrosis (75%). Immunohistochemistry shows HepPar 1 positivity in 64.6%, CK7 in 40.7%, and EMA in 41.9%. The 5-year overall survival rate estimates 45.2% and 45.5% of the patients experience a recurrence after hepatectomy.

Conclusion

S-HCC is a rare subtype of HCC primarily arising in hepatitis- or cirrhosis-afflicted livers and incorporates atypical radiological and histopathological HCC features. Despite lower recurrence rates, overall survival of patients with s-HCC is poorer than generally for HCC, underlining the need for individualized treatment. Patients with atypical lesions of the liver should be referred to tertiary hospitals for interdisciplinary assessment and treatment.

Hepatobiliary phase signal intensity: A potential method of diagnosing HCC with atypical imaging features among LR-M observations

Herein, we assessed whether hepatobiliary phase (HBP) signal intensity (SI) can be used to differentiate HCC and non-HCC malignancies within LR-M observations. 106 LR-M patients based on LI-RADS v2018 who underwent gadoxetate-disodium magnetic resonance imaging and surgery from January 2009 to December 2018 were included. SI of LR-M observation on HBP was analyzed by two radiologists and categorized into dark, low and iso-to-high groups. Tumor was classified as dark when more than 50% of tumor showed hypointensity compared to spleen, as low when more than 50% of tumor showed hyperintensity compared to spleen but hypointensity compared to liver parenchyma, and as iso-to-high if there was even a focal iso-intensity or hyperintensity compared to liver parenchyma. Analysis of clinicopathological factors and association between imaging and histology was performed. Out of 106 LR-M, 42 (40%) were showed dark, 61 (58%) showed low, and 3 (3%) showed iso-to-high SI in HBP. Three iso-to-high SI LR-M were HCCs (P = 0.060) and their major histologic differentiation was Edmondson grade 1 (P = 0.001). 43 out of 61 (71%) low SI LR-M were iCCA or cHCC-CCA (P = 0.002). Inter-reader agreement of HBP SI classification was excellent, with a kappa coefficient of 0.872. LR-M with iso-to-high SI in HBP is prone to being HCC while LR-M with low SI in HBP is prone to being tumor with fibrous stroma such as iCCA and cHCC-CCA. Classification of LR-M based on HBP SI may be a helpful method of differentiating HCC from non-HCC malignancies.

Spectrum of liver lesions hyperintense on hepatobiliary phase: an approach by clinical setting

Hepatobiliary MRI contrast agents are increasingly being used for liver imaging. In clinical practice, most focal liver lesions do not uptake hepatobiliary contrast agents. Less commonly, hepatic lesions may show variable signal characteristics on hepatobiliary phase. This pictorial essay reviews a broad spectrum of benign and malignant focal hepatic observations that may show hyperintensity on hepatobiliary phase in various clinical settings. In non-cirrhotic patients, focal hepatic observations that show hyperintensity in the hepatobiliary phase are usually benign and typically include focal nodular hyperplasia. In patients with primary or secondary vascular disorders, focal nodular hyperplasia-like lesions arise as a local hyperplastic response to vascular alterations and tend to be iso- or hyperintense in the hepatobiliary phase. In oncologic patients, metastases and cholangiocarcinoma are hypointense lesions in the hepatobiliary phase; however, occasionally they may show a diffuse, central and inhomogeneous hepatobiliary paradoxical uptake with peripheral rim hypointensity. Post-chemotherapy focal nodular hyperplasia-like lesions may be tricky, and their typical hyperintense rim in the hepatobiliary phase is very helpful for the differential diagnosis with metastases. In cirrhotic patients, hepatocellular carcinoma may occasionally appear hyperintense on hepatobiliary phase.

MRI features of combined hepatocellular- cholangiocarcinoma versus mass forming intrahepatic cholangiocarcinoma

BACKGROUND

Combined hepatocellular-cholangiocarcinoma (cHCC-CC) is a rare primary liver tumor, which has overlapping imaging features with mass forming intra-hepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC). Previous studies reported imaging features more closely resemble ICC and the aim of our study was to examine the differential MRI features of cHCC-CC and ICC with emphasis on enhancement pattern observations of gadolinium enhanced MRI.

METHODS

Institutional review board approval with consent waiver was obtained for this retrospective bi-centric study. Thirty-three patients with pathologically proven cHCC-CC and thirty-eight patients with pathologically proven ICC, who had pre-operative MRI, were identified. MRI images were analyzed for tumor location and size, T1 and T2 signal characteristics, the presence/absence of: cirrhosis, intra-lesional fat, hemorrhage/hemosiderin, scar, capsular retraction, tumor thrombus, biliary dilatation, degree of arterial enhancement, enhancement pattern, pseudocapsule and washout. Associations between MRI features and tumor type were examined using the Fisher's exact and chi-square tests.

RESULTS

Strong arterial phase enhancement and the presence of: washout, washout and progression, intra-lesional fat and hemorrhage were all strongly associated with cHCC-CC (P < 0.001). While cHCC-CC had a varied enhancement pattern, the two most common enhancement patterns were peripheral persistent (n = 6) and heterogeneous hyperenhancement with washout (n = 6), compared to ICC where the most common enhancement patterns were peripheral hypoenhancement with progression (n = 18) followed by heterogeneous hypoenhancement with progression (n = 14) (P < 0.001).

CONCLUSION

The cHCC-CC enhancement pattern seems to more closely resemble HCC with the degree of arterial hyperenhancement and the presence of washout being valuable in differentiating cHCC-CC from ICC. However the presence of washout and progression, in the same lesion or a predominantly peripheral /rim hyperenhancing mass were also seen as important features that should alert the radiologist to the possibility of a cHCC-CC.

Role of Contrast in MR Imaging

Magnetic resonance (MR) contrast agents have been widely used over the last 3 decades in routine clinical practice. Paul Lauterbur recognized the presence of these contrast agents, which act as paramagnetic catalysts that accelerate the T1 relaxation process. The first MR contrast agent to be approved for clinical use was in 1988, and since then, it is estimated that 200 million doses have been administered worldwide. These contrast agents have diverse clinical as well as research applications, involving almost all the body organs. This review will cover some existing as well as many new applications that have emerged over the last few decades. MR imaging now has the potential of being used to monitor enzymatic activity, gene expression, metal ion homeostasis, and cell death in vivo. In future, newer contrast agents will develop and become commercially available, expanding the current clinical applications of MR contrast media.

Biphenotypic hepatic tumors: imaging findings and review of literature

PURPOSE

To describe imaging findings in biphenotypic hepatic tumors (BPT) and a proposal for new imaging classification based on contrast-enhanced imaging.

METHODS

Retrospective review of CT, MRI, PET/CT, and ultrasound findings in 39 patients with histologically confirmed BPT was performed. Tumor markers including AFP, L3 fraction, CA 19.9, CA 125, and CEA were recorded. Based on the dynamic enhancement features, BPT were categorized into 4 enhancement patterns (Types 1-4). Enhancement patterns were correlated with other imaging findings and tumor markers. Imaging features and tumor markers that were not consistent with diagnosis of hepatocellular carcinoma or intrahepatic cholangiocarcinoma based on enhancement pattern were considered discordant findings.

RESULTS

Enhancement patterns in 29 patients (CT/MR) included 23 Type 2 (continuous peripheral rim of late arterial hyperenhancement with washout or fade in portal venous and/or delayed phases, ±delayed central enhancement) and 2 of each Types 1, 2, and 3. Discordant imaging findings were present in two patients with Type 2 pattern and in one patient with Type 1 pattern. Both AFP and CA 19.9 were elevated in 15 of 33 of patients. Tumor markers AFP and CA 19.9 were discordant in 17 of 21 patients with Type 2 pattern, two of two patients with Type 3 pattern. Most BPTs were markedly PET avid with average SUV max of 8.2. Most frequent ultrasound appearance is peripheral hypoechogenicity and central hyperechogenicity.

CONCLUSIONS

BPT most commonly present with imaging features similar to cholangiocarcinoma or metastases. BPT can be suggested when imaging findings or tumor markers are discordant with the most likely diagnosis based on enhancement pattern.

Intrahepatic mass-forming cholangiocarcinoma: enhancement pattern on Gd-BOPTA-MRI with emphasis of hepatobiliary phase

PURPOSE

To describe the Gd-BOPTA MRI findings of intrahepatic mass-forming type cholangiocarcinomas (IMCs), with emphasis on the hepatobiliary phase (HBP).

METHODS

We reviewed retrospectively 29 IMC patients who underwent Gd-BOPTA-MRI between June, 2004 and June, 2014. Images were acquired prior to, and after, administration of 15-20 mL of Gd-BOPTA in the dynamic phase (arterial phase, portal venous phase, and 3-5 min phase), 10-15-min late phase, and 2-3 h HBP phase.

RESULTS

In the dynamic phase, 27 (93%) lesions showed a peripheral rim-like enhancement in the arterial and portal venous phases, followed by progressive filling-in on the delayed images. In 14 (56%) cases, a hypointense peripheral rim was identified in the 10-15-min late phase, delineating a target pattern. In the HBP, the cholangiocarcinoma showed a diffuse, mainly central and inhomogeneous enhancement (cloud of enhancement) in 28 (96%) patients; in 23 (79%) cases, there was an association between cloud appearance and a hypointense peripheral rim, showing a target pattern.

CONCLUSIONS

Gd-BOPTA MRI pattern of IMC on dynamic study is similar to that of conventional extracellular agents, that is peripheral enhancement with progressive and concentric filling of contrast material on delayed phases. At 10-15 min delayed phases, IMC shows often a peripheral hypointense rim consistent with a target appearance. In the HBP, due to progressive central enhancement (cloud) and peripheral hypointense rim, an higher number of tumors show a target appearance; this pattern is not specific and would also be expected to be seen in metastases from adenocarcinoma.

Differentiation of intrahepatic mass-forming cholangiocarcinoma from hepatocellular carcinoma on gadoxetic acid-enhanced liver MR imaging

OBJECTIVES

To determine the different imaging features of intrahepatic mass-forming cholangiocarcinoma (IMCC) from hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

METHODS

This retrospective study was institutional review board approved and the requirement for informed consent was waived. Patients who underwent gadoxetic acid-enhanced MRI with histologically confirmed IMCCs (n = 46) or HCCs (n = 58) were included. Imaging features of IMCCs and HCCs on gadoxetic acid-enhanced MRI including T2- and T1-weighted, diffusion weighted images, dynamic study and hepatobiliary phase (HBP) images were analyzed. Univariate and multivariate logistic regression analyses were performed to identify relevant differentiating features between IMCCs and HCCs.

RESULTS

Multivariate analysis revealed heterogeneous T2 signal intensity and a hypointense rim on the HBP as suggestive findings of IMCCs and the wash-in and "portal wash-out" enhancement pattern as well as focal T1 high signal intensity foci as indicative of HCCs (all, p < 0.05). When we combined any three of the above four imaging features, we were able to diagnose IMCCs with 94 % (43/46) sensitivity and 86 % (50/58) specificity.

CONCLUSIONS

Combined interpretation of enhancement characteristics including HBP images, morphologic features, and strict application of the "portal wash-out" pattern helped more accurate discrimination of IMCCs from HCCs.

KEY POINTS

• Analysis of enhancement characteristics helped accurate discrimination of IMCCs from HCCs. • Wash-out should be determined on the PVP of gadoxetic acid-enhanced MRI. • A hypointense rim on the HBP was a significant finding of IMCCs.

Cancer stem cells in primary liver cancers: pathological concepts and imaging findings

There is accumulating evidence that cancer stem cells (CSCs) play an integral role in the initiation of hepatocarcinogenesis and the maintaining of tumor growth. Liver CSCs derived from hepatic stem/progenitor cells have the potential to differentiate into either hepatocytes or cholangiocytes. Primary liver cancers originating from CSCs constitute a heterogeneous histopathologic spectrum, including hepatocellular carcinoma, combined hepatocellular-cholangiocarcinoma, and intrahepatic cholangiocarcinoma with various radiologic manifestations. In this article, we reviewed the recent concepts of CSCs in the development of primary liver cancers, focusing on their pathological and radiological findings. Awareness of the pathological concepts and imaging findings of primary liver cancers with features of CSCs is critical for accurate diagnosis, prediction of outcome, and appropriate treatment options for patients.

Current update on combined hepatocellular-cholangiocarcinoma

Combined hepatocellular-cholangiocarcinoma is a rare but unique primary hepatic tumor with characteristic histology and tumor biology. Recent development in genetics and molecular biology support the fact that combined hepatocellular-cholangiocarcinoma is closely linked with cholangiocarcinoma, rather than hepatocellular carcinoma.

Combined hepatocellular cholangiocarcinoma tends to present with an more aggressive behavior and a poorer prognosis than either hepatocellular carcinoma or cholangiocarcinoma. An accurate preoperative diagnosis and aggressive treatment planning can play crucial roles in appropriate patient management.

Magnetic resonance imaging in cirrhosis: what's new?

Cirrhosis is the main risk factor for the development of hepatocellular carcinoma (HCC). The major causative factors of cirrhosis in the United States and Europe are chronic hepatitis C infection and excessive alcohol consumption with nonalcoholic steatohepatitis emerging as another important risk factor. Magnetic resonance imaging is the most sensitive imaging technique for the diagnosis of HCC, and the sensitivity can be further improved with the use of diffusion-weighted imaging and hepatocyte-specific contrast agents. The combination of arterial phase hyperenhancement, venous or delayed phase hypointensity "washout feature," and capsular enhancement are features highly specific for HCC with reported specificities of 96% and higher. When these features are present in a mass in the cirrhotic liver, confirmatory biopsy to establish the diagnosis of HCC is not necessary. Other tumors, such as cholangiocarcinoma, sometimes occur in the cirrhotic at a much lower rate than HCC and can mimic HCC, as do other benign lesions such as perfusion abnormalities. In this article, we discuss the imaging features of cirrhosis and HCC, the role of magnetic resonance imaging in the diagnosis of HCC and other benign and malignant lesions that occur in the cirrhotic liver, and the issue of nonspecific arterially hyperenhancing nodules often seen in cirrhosis.

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.

Differentiating hepatic abscess from malignant mimickers: value of diffusion-weighted imaging with an emphasis on the periphery of the lesion

PURPOSE

To evaluate the efficacy of diffusion-weighted imaging (DWI) in differentiating hepatic abscess from malignant mimickers with an emphasis on periphery of the lesions.

MATERIALS AND METHODS

Thirty-nine patients with hepatic abscess and 74 patients with malignant hepatic tumors were included, who underwent gadoxetic acid-enhanced MRI. For qualitative and quantitative analysis, signal intensities and apparent diffusion coefficient (ADC) values of the periphery were assessed. Two observers reviewed DWI and ADC maps rated using a 5-point scale. Diagnostic performance was evaluated using the receiver operating characteristics (ROC) curve analysis.

RESULTS

The periphery of hepatic abscesses was T1-hypointense, arterial hyperintense, and hypointense on hepatobiliary phase less frequently than that of malignant tumors (P < 0.05). No hepatic abscesses showed peripheral washout on 3-min late phase compared with malignant tumors (59.5%) (P < 0.001). Both groups showed hyperintense rims on DWI, but, 37(94.9%) abscesses revealed rims with high ADC values compared with one (1.4%) malignant tumor (P < 0.001). Mean ADC values of abscesses (1.47 × 10(-3) mm(2) /s ± 0.36 [standard deviation]) were significantly higher than those of malignancies (0.68 × 10(-3) mm(2) /s ± 0.20). Diagnostic performance (area under the ROC curve [Az]) of DWI in identifying hepatic abscess was 0.986 and 0.982 for each observer.

CONCLUSION

In addition to conventional MRI, DWI is helpful in differentiating hepatic abscess from malignant mimickers.

Use of magnetic resonance imaging contrast agents in the liver and biliary tract

This article presents an overview of liver and biliary contrast agents including their mechanisms of action, dosage and elimination, current clinical indications, and potential future uses.

Combined hepatocellular carcinoma-cholangiocarcinoma: report of MR appearance in eleven patients

PURPOSE

To describe the magnetic resonance imaging (MRI) appearance of hepatic combined hepatocellular-cholangiocarcinoma (cHCC-CC) in 11 patients.

MATERIALS AND METHODS

The database of the Department of Pathology was cross-referenced with the MRI database to identify patients with confirmed cHCC-CC who had undergone MRI. Eleven consecutive patients were included (seven female, mean age 57.6 years). All patients were Caucasian. Five of 11 had a clinical history of chronic liver disease. Two radiologists retrospectively analyzed the images in consensus.

RESULTS

cHCC-CC was a single mass in 10/11 patients. Margins were well-defined in 6/11. All tumors showed heterogeneous hyperintensity on T2. On postcontrast imaging, 6/11 showed early ring-enhancement (four noncirrhotic), with progressive enhancement in central portions, and 5/11 patients showed a diffuse heterogeneous early enhancement. Three of these five were cirrhotic and displayed partial washout with portions of contrast retention on later phases. Other findings included: late capsule enhancement (two patients), biliary dilatation (one), venous invasion (three), lymphadenopathy (six), and findings of cirrhosis (five).

CONCLUSION

cHCC-CC presents most commonly as a single mass. Five of 11 had MR findings of cirrhosis. Clues to the diagnosis were moderately high signal on T2, portions of tumor that show progressive enhancement/contrast retention, and frequent lack of capsule. Early enhancement patterns included early ring-enhancement and diffuse heterogeneous enhancement.

Clinicopathologic characteristics and long-term prognosis of scirrhous hepatocellular carcinoma

BACKGROUND

Clinicopathologic features and long-term outcomes in patients with scirrhous hepatocellular carcinoma (S-HCC) are not fully defined.

METHODS

We compared data of 37 patients with S-HCC and 604 with usual HCC (U-HCC) undergoing surgery.

RESULTS

The S-HCC group showed less HBV infection (78.4 vs. 92.0%, P = 0.02), low serum AFP level (2320 ± 6356 vs. 3297 ± 18690 ng/ml, P < 0.0001), less delayed washout during CT (72.7 vs. 90.7%, P = 0.004), and low usefulness of clinical diagnostic criteria (32.4 vs. 57.5%, P = 0.003), compared to the U-HCC group. More portal vein invasion (18.9 vs. 4.1%, P = 0.03) and less liver cirrhosis (35.1 vs. 65.1%, P = 0.001) and fibrous capsule (40.5 vs. 81.6%, P < 0.001) were noted in the S-HCC group than the U-HCC group. Long-term survival rates were similar between the S-HCC and U-HCC groups, even with subgroup analysis according to Child-Pugh score and modified UICC stage.

CONCLUSION

The S-HCC group showed distinct patient and tumor characteristics but similar long-term outcome.

Spectral CT in patients with small HCC: investigation of image quality and diagnostic accuracy

OBJECTIVE

To assess image quality and diagnostic accuracy of monochromatic imaging from spectral CT in patients with small HCC (≤3 cm).

METHODS

Twenty-seven patients with 31 HCC underwent spectral CT to generate conventional 140-kVp polychromatic images (group A) and monochromatic images with energy levels from 40 to 140 keV (group B) during the late arterial phase (LAP) and the portal venous phase (PVP). Two-sample t tests compared the tumour-to-liver contrast-to-noise ratio (CNR) and mean image noise. Lesion detection for LAP, reader confidence and readers' subjective evaluations of image quality were recorded.

RESULTS

Highest CNRs in group B were distributed at 40, 50 and 70 keV. Higher CNR values and lesion conspicuity scores (LCS) were obtained in group B than in group A (CNR 3.36 ± 2.07 vs. 1.47 ± 0.89 in LAP; 2.29 ± 2.26 vs. 1.58 ± 1.75 in PVP; LCS 2.82, 2.84, 2.63 and 2.53 at 40-70 keV, respectively, vs. 1.95) (P < 0.001). Lowest image noise for group B was at 70 keV, resulting in higher image quality than that in group A (4.70 vs. 4.07; P < 0.001).

CONCLUSION

Monochromatic energy levels of 40-70 keV can increase detectability in small HCC and this increase might not result in image quality degradation.

KEY POINTS

• Spectral computed tomography may help the detection of small hepatocellular carcinoma. • Monochromatic energy levels of 40-70 keV increase the sensitivity for detection. • Prospective study showed that monochromatic imaging provides greater diagnostic confidence. • Monochromatic energy level of 70 keV improves the overall image quality.

Differentiating mass-forming intrahepatic cholangiocarcinoma from atypical hepatocellular carcinoma using gadoxetic acid-enhanced MRI

AIM

To examine the differential features of mass-forming intrahepatic cholangiocarcinoma (ICC) from atypical hypovascular hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived informed patient consent. Seventy patients with pathologically proven ICCs (35) and hypovascular atypical HCCs (35) who had undergone preoperative gadoxetic acid-enhanced MRI were enrolled in this study. Images were analysed for the shape of the lesions and presence of hyperintensity on the T1-weighted image (T1WI) and hypo- or hyperintense areas on the T2-weighted image (T2WI). In addition, images were analysed for the presence of linear hyperintensity or multifocal, tiny, hyperintense foci on T2WI and the presence of rim enhancement during early dynamic phases and a central enhancement with a hypointense rim (target appearance) on the 10 and 20 min hepatobiliary phase images. The significance of these findings was determined by the X(2) test.

RESULTS

Univariate analysis revealed that the following significant parameters favour ICC or hypovascular HCC; the presence of T2 hypo- and hyperintense areas and target appearance on the 10 min hepatobiliary phase images favour ICC, and the presence of T2 linear hyperintensity and T2 multifocal hyperintense foci favour hypovascular HCC (p < 0.05). Multivariate analysis revealed that only target appearance on the 10 min hepatobiliary phase was predictive of ICC (p = 0.002) as 30 ICCs (85.7%) showed this feature. However, the target appearance was also observed in all six scirrhous HCCs.

CONCLUSION

A target appearance on the 10 min hepatobiliary phase images is the best predictor for identifying mass-forming ICC at gadoxetic acid-enhanced MRI.

Tumors of the liver and intrahepatic bile ducts: radiologic-pathologic correlation

Primary tumors of the liver can be classified pathologically based on their cell of origin into epithelial tumors, arising from hepatocytes or biliary epithelium, and nonepithelial tumors, including mesenchymal tumors and lymphoma. Characteristic findings on MR imaging can be seen in many cases. This article reviews the MR imaging appearance of these tumors with pathologic correlation.