Small hypervascular hepatocellular carcinomas: value of diffusion-weighted imaging compared with "washout" appearance on dynamic MRI

The clinical value of dual-energy computed tomography and diffusion-weighted imaging in the context of liver cancer: A narrative review

The dual-energy computed tomography (DECT) and diffusion-weighted magnetic resonance imaging (DWI-MRI) are used to diagnose liver cancer. The clinical value of these two examination methods needs to be further summarized. We collected and summarized relevant literature published from 2011 to 2021. The diagnostic performance of DECT was assessed between conventional computed tomography and DWI-MRI. DWI-MRI had a 69% sensitivity for detecting small hepatocellular carcinoma (HCC) lesions and a 60% diagnostic specificity for differentiating between types of HCC lesions. DECT had a sensitivity to small liver lesions (<1 cm) of 69%, and the diagnostic specificity for HCC and metastasis was about 60%. DWI was more sensitive (90.3% vs. 74.9%) and accurate (91.9% vs. 76.9%) in diagnosing HCC compared with conventional MRI sequencing. With the aid of contrast media, DWI-MRI had 90.0% specificity for detecting small HCCs (smaller than 1 cm). Furthermore, DWI-MRI not only provided physicians with valuable diagnostic information but also delivered histological grading information, with 78% accuracy for all benign lesions and 71% for solid lesions. DECT had relatively high sensitivity and required a lower contrast medium dose. With standardized quantitative parameters, it can be an extremely useful tool for HCC surveillance. DWI-MRI is the preferred imaging process as it produces high-contrast images for supporting an early diagnosis (high sensitivity and specificity) and provides histological information using non-ionizing radiation.

Magnetic resonance imaging for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma occurs mostly in people with chronic liver disease and ranks sixth in terms of global incidence of cancer, and third in terms of cancer deaths. In clinical practice, magnetic resonance imaging (MRI) is used as a second-line diagnostic imaging modality to confirm the presence of focal liver lesions suspected as hepatocellular carcinoma on prior diagnostic test such as abdominal ultrasound or alpha-fetoprotein, or both, either in surveillance programmes or in clinical settings. According to current guidelines, a single contrast-enhanced imaging study (computed tomography (CT) or MRI) showing typical hallmarks of hepatocellular carcinoma in people with cirrhosis is considered valid to diagnose hepatocellular carcinoma. The detection of hepatocellular carcinoma amenable to surgical resection could improve the prognosis. However, a significant number of hepatocellular carcinomas do not show typical hallmarks on imaging modalities, and hepatocellular carcinoma may, therefore, be missed. There is no clear evidence of the benefit of surveillance programmes in terms of overall survival: the conflicting results can be a consequence of inaccurate detection, ineffective treatment, or both. Assessing the diagnostic accuracy of MRI may clarify whether the absence of benefit could be related to underdiagnosis. Furthermore, an assessment of the accuracy of MRI in people with chronic liver disease who are not included in surveillance programmes is needed for either ruling out or diagnosing hepatocellular carcinoma.

OBJECTIVES

Primary: to assess the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma of any size and at any stage in adults with chronic liver disease. Secondary: to assess the diagnostic accuracy of MRI for the diagnosis of resectable hepatocellular carcinoma in adults with chronic liver disease, and to identify potential sources of heterogeneity in the results.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic Test of Accuracy Studies Register, the Cochrane Library, MEDLINE, Embase, and three other databases to 9 November 2021. We manually searched articles retrieved, contacted experts, handsearched abstract books from meetings held during the last 10 years, and searched for literature in OpenGrey (9 November 2021). Further information was requested by e-mails, but no additional information was provided. No data was obtained through correspondence with investigators. We applied no language or document-type restrictions.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease, with cross-sectional designs, using one of the acceptable reference standards, such as pathology of the explanted liver and histology of resected or biopsied focal liver lesion with at least a six-month follow-up.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened studies, extracted data, and assessed the risk of bias and applicability concerns, using the QUADAS-2 checklist. We presented the results of sensitivity and specificity, using paired forest plots, and we tabulated the results. We used a hierarchical meta-analysis model where appropriate. We presented uncertainty of the accuracy estimates using 95% confidence intervals (CIs). We double-checked all data extractions and analyses.

MAIN RESULTS

We included 34 studies, with 4841 participants. We judged all studies to be at high risk of bias in at least one domain because most studies used different reference standards, often inappropriate to exclude the presence of the target condition, and the time interval between the index test and the reference standard was rarely defined. Regarding applicability, we judged 15% (5/34) of studies to be at low concern and 85% (29/34) of studies to be at high concern mostly owing to characteristics of the participants, most of whom were on waiting lists for orthotopic liver transplantation, and due to pathology of the explanted liver being the only reference standard. MRI for hepatocellular carcinoma of any size and stage: sensitivity 84.4% (95% CI 80.1% to 87.9%) and specificity 93.8% (95% CI 90.1% to 96.1%) (34 studies, 4841 participants; low-certainty evidence). MRI for resectable hepatocellular carcinoma: sensitivity 84.3% (95% CI 77.6% to 89.3%) and specificity 92.9% (95% CI 88.3% to 95.9%) (16 studies, 2150 participants; low-certainty evidence). The observed heterogeneity in the results remains mostly unexplained. The sensitivity analyses, which included only studies with clearly prespecified positivity criteria and only studies in which the reference standard results were interpreted without knowledge of the results of the index test, showed no variation in the results.

AUTHORS' CONCLUSIONS

We found that using MRI as a second-line imaging modality to diagnose hepatocellular carcinoma of any size and stage, 16% of people with hepatocellular carcinoma would be missed, and 6% of people without hepatocellular carcinoma would be unnecessarily treated. For resectable hepatocellular carcinoma, we found that 16% of people with resectable hepatocellular carcinoma would improperly not be resected, while 7% of people without hepatocellular carcinoma would undergo inappropriate surgery. The uncertainty resulting from the high risk of bias in the included studies and concerns regarding their applicability limit our ability to confidently draw conclusions based on our results.

Diagnostic accuracy of gadoxetic acid-enhanced MR for small hypervascular hepatocellular carcinoma and the concordance rate of Liver Imaging Reporting and Data System (LI-RADS)

Background & aims

To assess diagnostic accuracy of gadoxetic acid–enhanced MR for small hypervascular hepatocellular carcinoma (HCC) detected by C-arm CT and concordance rate of Liver Imaging Reporting and Data System (LI-RADS).

Methods

In this retrospective study, we recruited 4,544 patients suspected of having HCC underwent C-arm CT from November 2008 to May 2013. Among these patients, gadoxetic acid–enhanced MR was performed in 167 patients with HCC (n = 379; 257 > 1 cm, 122 ≤ 1 cm). HCC was confirmed by MR, CT, or follow-up images. Two radiologists graded likelihood of HCC and assessed MR features. Jackknife alternative free-response receiver operating characteristic (JAFROC) analysis was performed. All HCCs were evaluated concordance rate of LI-RADS.

Results

Mean JAFROC figure of merit for large (>1-cm) HCC was 0.948, while that for small HCC was 0.787 with fair agreement (κ = 0.409). Mean sensitivity and positive predictive value (PPV) were 91% and 90% for large HCC versus 63.0% and 79% for small HCC, respectively. Seventeen of 122 small HCCs (13.9%) were not visible on MR. Among 379 HCCs, 99 met LR-5, and 259 met LR-4. Common features for small HCC included arterial enhancement (81.9%), hepatobiliary phase hypointensity (80.3%), and delayed washout (72.9%).

Conclusion

Diagnostic accuracy of gadoxetic acid–enhanced MR imaging for small, hypervascular HCCs (Mean figure of merit = 0.787) was still low compared with large HCC (Mean figure of merit = 0.948). LR-5 and LR-4 covered 94% (358/379) of the HCCs.

Differentiation of small (≤2 cm) hepatocellular carcinomas from small benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted magnetic resonance images

OBJECTIVE

To identify imaging characteristics that differentiate small (≤2 cm) HCCs from small (≤2 cm) benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted (DW) magnetic resonance (MR) images.

MATERIALS AND METHODS

On gadoxetic acid-enhanced and DW MR images, we analysed signal intensity of 222 small HCCs and 61 benign nodules (diameter, 0.5-2 cm) at each sequence and rim enhancement during portal or equilibrium phases. Univariate and multivariate logistic regression analyses identified predictors of HCC. Combinations of significant MR findings in multivariate analysis were compared with American Association for the Study of Liver Disease (AASLD) practice guidelines.

RESULTS

In multivariate analysis, arterial enhancement (adjusted odds ratio [aOR], 8.6), T2 hyperintensity (aOR, 5.8), and hyperintensity on DW images (aOR, 3.8) were significant for differentiating small HCCs from benign nodules (p ≤ 0.004). When two or all three findings were applied as diagnostic criteria for differentiating small HCCs from benign nodules, sensitivity and accuracy were significantly higher compared with AASLD practice guidelines (91% vs. 78% and 89% vs. 81%, respectively; each p < 0.0001).

CONCLUSION

On gadoxetic acid-enhanced MR imaging, arterial enhancement and hyperintensity on T2-weighted and DW MR images are helpful for differentiating small HCCs from benign nodules in liver cirrhosis.

Atypical magnetic resonance imaging findings in hepatocellular carcinoma

Magnetic resonance imaging (MRI) is currently the modality of choice to evaluate liver lesions in patients with cirrhosis and hepatitis B and C. Hepatocellular carcinoma demonstrates typical imaging findings on contrast-enhanced MRI, which are usually diagnostic. Unfortunately, a subgroup of hepatocellular carcinoma presents with atypical imaging features, and awareness of these atypical presentations is important in ensuring early diagnosis and optimal patient outcomes. Herein, we review some of the more common atypical presentations with a focus on MRI.

Magnetic resonance imaging of a small vessel hepatic hemangioma in a cirrhotic patient with histopathologic correlation

The authors report and discuss a rare case of a small vessel hepatic hemangioma in a 59-year-old patient with liver cirrhosis, which was pre-procedurally characterized as indeterminate due to atypical magnetic resonance imaging (MRI) features. This manuscript reviews the MRI features with pathologic correlation, emphasizes the importance of accurate characterization of liver lesions, and discusses the role of biopsy. We believe this is the first reported case of a small vessel hemangioma in liver cirrhosis with imaging and histopathologic correlation.

Considerations regarding current diagnosis and prognosis of hepatocellular carcinoma

Hepatocellular carcinoma is a major health issue, ranked the fifth most common tumor and currently being responsible for a third of the cancer-related deaths globally, with an ever-increasing number of fatalities. Current advances in contrast-enhanced imaging techniques such as contrast-enhanced ultrasonography, multi-detector computed tomography and diffusion-weighted magnetic resonance imaging are improving the rate of hepatocellular carcinoma diagnosis. Contrast-enhanced ultrasonography has widely become the first choice in liver tumor assessment, as it is faster, simpler and safer than other forms of diagnostic imaging. On the other hand, cross sectional computed tomography is frequently employed when a hepatic formation is suspected of malignancy and allows a more accurate characterization of lesions through multiphasic multi-detector computed tomography technology. Diffusion weighted magnetic resonance imaging represents another addition to the wide range of diagnostic and prognostic techniques available for patients with hepatocellular carcinoma and is currently regarded as one of the best tools for the characterization of these lesions. Furthermore, groundbreaking biomarkers for hepatocellular carcinoma are being discovered, although alpha-fetoprotein remains one of the most frequently used serum test in the early stages. Nonetheless, further advances are required for the detection of small liver carcinomas.

Functional MR imaging of the abdomen

In this article, functional magnetic resonance (MR) imaging techniques in the abdomen are discussed. Diffusion-weighted imaging (DWI) increases the confidence in detecting and characterizing focal hepatic lesions. The potential uses of DWI in kidneys, adrenal glands, bowel, and pancreas are outlined. Studies have shown potential use of quantitative dynamic contrast-enhanced MR imaging parameters, such as K(trans), in predicting outcomes in cancer therapy. MR elastography is considered to be a useful tool in staging liver fibrosis. A major issue with all functional MR imaging techniques is the lack of standardization of the protocol.

Detection of small (≤2 cm) HCC in cirrhotic patients: added value of diffusion MR-imaging

OBJECTIVES

To evaluate the usefulness of the diffusion-weighted sequence in the detection of small (≤2 cm) hepatocellular carcinoma (HCC) in patients with cirrhosis.

METHODS

Seventy cirrhotic patients with 93 HCCs underwent MR-Imaging at 1.5 T. MR acquisitions comprised unenhanced T1- and T2-weighted images and post-contrast Gd-BOPTA-enhanced T1W GRE-3D images acquired after approximately 25, 60, 180 s (dynamic phases) and 90 min (hepatobiliary phase). DWI was performed by a SSEPI sequence (b values 0, 50, 400, 800 s/mm(2)). Quantitative analysis was performed to establish significant difference of ADC values of benign lesions compared with that of HCC. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of two different protocols with and without diffusion MRI sequence were also calculated and compared each other.

RESULTS

A good inverse correlation was found between reference standard and ADC values (ρ = -0.688). The mean ADC value of HCC was significantly lower than the mean value of benign focal liver lesions (p < 0.0001). No significant difference was reported in term of sensitivity, specificity, PPV, NPV and diagnostic accuracy between the two datasets. A trend to a better sensitivity was found when DWI images were considered.

CONCLUSIONS

The adjunction of DWI does not significantly improve the diagnostic accuracy in the detection of small HCC.

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.

Whole body MRI: improved lesion detection and characterization with diffusion weighted techniques

Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation.