What’s new in Liver Imaging – September 2020

2 months ago

In this blog, we provide a synopsis of the latest in Liver Imaging published during the month of August 2020 in addition to an editorial comment by our guest editor for this month, Venkateswar R. Surabhi, MD, Professor of Radiology at the University of Texas Health Science Center at Houston.

 

Hepatocellular Carcinoma

Application of Liver Imaging Reporting and Data System version 2018 ancillary features to upgrade from LR-4 to LR-5 on gadoxetic acid-enhanced MRI

Lee S, Kim SS, Bae H, Shin J, Yoon JK, Kim MJ.

Application of Liver Imaging Reporting and Data System version 2018 ancillary features to upgrade from LR-4 to LR-5 on gadoxetic acid-enhanced MRI [published online ahead of print, 2020 Aug 18]. Eur Radiol. 2020;10.1007/s00330-020-07146-4.

https://doi.org/10.1007/s00330-020-07146-4

Keywords: Contrast media; Diagnosis; Liver neoplasms; Magnetic resonance imaging; Sensitivity and specificity.

Clinical question: Can we use MRI AFs to upgrade LR-4 to LR-5?

What was done: The diagnostic performance of the upgraded LR-5 (using AFs) was compared with the standard LR-5 category.

How was it done: Retrospective study of 280 patients at high risk for HCC who underwent Gd-MRI between 2015 and 2017. Independently significant AFs were identified. Upgraded LR-5 criteria were developed by combining independently significant AFs with LR-4 assigned by major features alone. Sensitivities and specificities of the diagnostic criteria were compared.

Findings and results: Four AFs (mild-to-moderate T2 hyperintensity and hepatobiliary phase hypointensity, nonenhancing “capsule”, and mosaic architecture) were independently significant features for diagnosing HCC. By using the upgraded LR-5 criteria, sensitivities were significantly increased (69.4-76.9%) compared with the standard LR-5 (66.2%), whereas specificities were not significantly different.

Conclusion: Independently significant AFs may be used to upgrade from LR-4 to LR-5 to improve sensitivity without impairing specificity on Gd-MRI.

Implications: Since the initial debut of LI-RADS, LR-5 category is only assigned based on MFs and AFs cannot be used to upgrade LR-4 to LR-5 to maintain the high specificity of LR-5 for HCC. This retrospective study provides proof of evidence that certain AFs can be used to upgrade LR-4 with improved sensitivity and maintained specificity.

 

Editorial comment:

A Potential Role for Ancillary Features in upgrading LR-4 observation to LR-5

The Liver Imaging Reporting and Data System (LI-RADS) uses an algorithm to assign categories that reflect the probability of hepatocellular carcinoma (HCC). LI-RADS also uses ancillary features (AFs) broadly classified as those favoring malignancy in general, those favoring HCC specifically, and those favoring benignity to refine the final category.  Ancillary features are used routinely by liver imaging experts to improve detection of observations, refine categorization of observations, and assess with higher level of confidence the probability of malignancy or benignity. Although ancillary features are currently an optional component of LI-RADS, awareness of their existence and familiarity in their application can enhance the level of expertise in liver imaging. Presence of one or more AFs favoring malignancy give radiologist an option to upgrade by one category up to LR4 whereas presence of one or more AFs favoring benignity give radiologist an option to downgrade by one category. AFs cannot be used to upgrade to LR5.

Lee et al investigated the diagnostic performance of the upgraded LR-5 (using AFs) compared with the standard LR-5 category in a cohort of 280 patients at high risk for HCC who underwent gadoxetic acid-enhanced MRI between 2015 and 2017.  A total of 366 observations including 281 HCCs were evaluated by two readers. Two readers evaluated major features and AFs for each observation and assigned a LI-RADS category. Four AFs (mild-to-moderate T2 hyperintensity and hepatobiliary phase hypointensity, nonenhancing “capsule”, and mosaic architecture) were identified through logistic regression analysis as independently significant features for diagnosing HCC.  Upgraded LR-5 criteria were developed by combining independently significant AFs with LR-4 assigned by major features alone. Sensitivities and specificities of the diagnostic criteria were compared. By using the upgraded LR-5 criteria, sensitivities were significantly increased (69.4-76.9%) compared with the standard LR-5 (66.2%), whereas specificities were not significantly different. Since the initial debut of LI-RADS, LR-5 category is only assigned based on MFs and AFs cannot be used to upgrade LR-4 to LR-5 to maintain the high specificity of LR-5 for HCC. This retrospective study provides proof of evidence that certain AFs can be used to upgrade LR-4 with improved sensitivity and maintained specificity.

A limitation of this study is assessment on only gadoxetic acid-enhanced MRI. Hepatobiliary phase hypointensity is a feature that can only be assessed on gadoxetic acid – enhanced MRI. Thus, the utility of MRI ancillary features to upgrade to LR5 needs further validation using extracellular agent- MRI. The generalizability of ancillary features to upgrade to LR5 category also needs further validation for with different causes of cirrhosis as underlying etiology is Hepatitis B in 90 % of patients in this study. Nevertheless, a significant increase in sensitivity without sacrificing specificity and substantial reductions in the use of the LR 4 category via use of ancillary features on gadoxetic acid–enhanced MRI scans will be welcome change if validated on additional studies.

 

Venkateswar R. Surabhi, MD

Professor of Radiology

Department of Abdominal Imaging

University of Texas Health Science Center at Houston

Diagnostic Performance of LI-RADS Treatment Response Algorithm for Hepatocellular Carcinoma: Adding Ancillary Features to MRI Compared with Enhancement Patterns at CT and MRI

Park, S., Joo, I., Lee, D. H., Bae, J. S., Yoo, J., Kim, S. W., & Lee, J. M. (2020).

Diagnostic performance of LI-RADS treatment response algorithm for hepatocellular carcinoma: adding ancillary features to MRI compared with enhancement patterns at CT and MRI. Radiology, 192797.

https://doi.org/10.1148/radiol.2020192797

Clinical question: To compare the diagnostic performance of MRI ancillary features in category adjustment with the LR-TR algorithm in CT and MRI for the detection of tumor viability.

How was it done: Retrospective study between 2014 and 2017 of 138 patients with HCC treated with LRT followed by surgical resection or liver transplantation. Treatment response categories were assigned, for each treated observation, based on the LR-TR algorithm in CT and MRI, and according to the MRI-modified TR algorithm with the application of MRI AFs for category adjustment.

Findings and results: The sensitivity and specificity of CT LR-TR viable and MRI LR-TR viable categories for predicting tumor viability were 73% versus 76% and 90% versus 83%, respectively. MRI-modified TR viable category had higher sensitivity (84%) than CT or MRI LR-TR viable category, without difference in specificity.

Conclusion: The application of MRI AFs to the LI-RADS TR algorithm resulted in higher sensitivity and no change in specificity compared with CT or MRI enhancement patterns alone in the prediction of pathologic tumor viability.

Implications: Given the increased sensitivity of LI-RADS TR algorithm with the addition of MRI AFs, next updates of LI-RADS might include the optional use of MRI AFs for improved diagnostic accuracy.

 

 

 

LIVER IMAGING TECHNIQUES

 

Contrast-enhanced US with Sulfur Hexafluoride and Perfluorobutane for the Diagnosis of Hepatocellular Carcinoma in Individuals with High Risk

Kang, H. J., Lee, J. M., Yoon, J. H., Lee, K., Kim, H., & Han, J. K. (2020).

Contrast-enhanced US with Sulfur Hexafluoride and Perfluorobutane for the Diagnosis of Hepatocellular Carcinoma in Individuals with High Risk. Radiology, 200115.

Advance online publication: https://doi.org/10.1148/radiol.2020200115

Clinical question: Is Perfluorobutane (PFB)-enhanced US superior to Sulfur Hexafluoride (SHF)-enhanced US in diagnosing HCC?

What was done: The diagnostic performance of CEUS LI-RADS v2017 was compared when using PFB as a contrast agent versus SHF.

How was it done: Prospective study of 59 patients at high risk for HCC with suspicious hepatic observations (LR-3, LR-4, LR-5 and LR-M) who underwent same-day PFB-enhanced US and SHF-enhanced US. APHE, washout time and degree, and echogenicity in the Kupffer phase were evaluated and categorized using CEUS LI-RADS v2017. Diagnostic performance of both techniques was compared.

Findings and results: APHE was identically observed with both contrast agents. Late and mild washout were more frequent with PFB-enhanced US. The washout time for HCCs was later at PFB-enhanced US than at SHF-enhanced US. Sensitivity (79%) was higher with PFB-enhanced US than with SHF-enhanced US (54%). Specificity was 100% with both.

Conclusion: CEUS LI-RADS using PFB had a significantly higher sensitivity compared with SHF, without loss of specificity.

Implications: CEUS LI-RADS v2017 currently applies to pure blood-pool agents such as SHF, but not to combined blood-pool/Kupffer cell agents such as PFB. Although PFB is not yet approved for liver use in the United States, it provides a better diagnostic performance than the traditionally used SHF. Implementation of PFB-enhanced US in the United States might be needed in the near future.

 

Contrast-enhanced ultrasound liver imaging reporting and data system for diagnosing hepatocellular carcinoma: A meta-analysis

Shin, J., Lee, S., Bae, H., Chung, Y. E., Choi, J. Y., Huh, Y. M., & Park, M. S. (2020).

Contrast-enhanced ultrasound liver imaging reporting and data system for diagnosing hepatocellular carcinoma: A meta-analysis. Liver international: official journal of the International Association for the Study of the Liver, 10.1111/liv.14617.

Advance online publication: https://doi.org/10.1111/liv.14617

Keywords: diagnosis; liver neoplasms; microbubbles; sensitivity and specificity; ultrasound.

Clinical question: What is the diagnostic performance of CEUS LR-5 for HCC?

What was done: The diagnostic performance of CEUS LR-5 and the proportion of HCC in each CEUS LI-RADS category were evaluated.

How was it done: Meta-analysis of 11 studies including a total of 5535 observations, out of which 3983 were HCC. Random-effects model was used to determine summary estimates of the diagnostic performance of CEUS LR-5 and the pooled proportions of HCCs in each CEUS LI-RADS category. Risk of bias and concerns regarding applicability were evaluated.

Findings and results: The pooled per-observation sensitivity and specificity of LR-5 for diagnosing HCC were 69% and 92%, respectively. The pooled proportions of HCCs were 0% for LR-1, 1% for LR-2, 26% for LR-3, 77% for LR-4, 97% for CEUS LR-5 and 57% for LR-M.

Conclusion: LR-5 category showed moderate sensitivity and high specificity for diagnosing HCC.

Implications: CEUS LI-RADS can be confidently used to diagnose HCC.

 

LIVER: BASIC SCIENCE

 

Assessment of hepatitis and fibrosis using Gd-EOB-DTPA MRI in dogs.

Tanaka, T., Nishida, H., Mie, K., Yamazaki, H., Lin, L. S., & Akiyoshi, H. (2020).

Assessment of hepatitis and fibrosis using Gd-EOB-DTPA MRI in dogs. Veterinary record open, 7(1), e000371.

https://doi.org/10.1136/vetreco-2019-000371

Keywords: gadoxetate sodium; hepatocellular adenoma; hepatocellular carcinoma; liver function; magnetic resonance imaging (MRI); nodular hyperplasia.

Clinical question: Does contrast enhancement using Gd-EOB-DTPA MRI correlate with liver function in dogs?

What was done: Relative signal intensities (RSI) of the common bile duct and gall bladder were calculated, and their relationship with the biochemical parameters of liver function was evaluated. Relative contrast enhancement indices (RCEI) of the liver were calculated, and differences were assessed between normal and diseased liver.

How was it done: Retrospective study of 16 dogs with histologically proven liver disease (HCC, nodular hyperplasia, hepatocellular adenoma, liver fibrosis and hepatitis). RSI of the common bile duct and gall bladder were calculated. Mean SI in the liver was calculated during the hepatobiliary phase and used as the representative hepatic parenchyma SI. The relationship between these indices and liver function biochemical markers was evaluated. These markers consisted of total bilirubin, alanine transaminase, alkaline phosphatase and albumin.

Findings and results: RSI showed no significant differences between dogs without and with a histopathological diagnosis of liver disease, although they were significantly correlated with albumin (ρ=0.57) in dogs with a histopathological diagnosis of liver disease. RCEI was significantly higher in normal liver tissue than that in livers with hepatitis/fibrosis and HCC but not nodular hyperplasia/hepatocellular adenoma.

Conclusions: RSI of the common bile duct and gall bladder is influenced with albumin in dogs with liver disease. RCEI in the hepatobiliary phase in normal liver were higher than those in hepatitis and fibrosis.

Implications: Gd-EOB-DTPA MRI may be potentially useful in assessing hepatitis and hepatic fibrosis in dogs. However, further studies are needed with subsequent validation in humans.

References
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