Contrast-enhanced ultrasound for the characterization of portal vein thrombosis vs tumor-in-vein in HCC patients: a systematic review and meta-analysis.
Chen J, Zhu J, Zhang C, Song Y, Huang P. European Radiology. 2020
Portal vein thrombosis (PVT) and tumor invasion of portal vein (TIV) are both possible complications of Hepatocellular carcinoma (HCC). The importance of differential diagnosis consists in different therapies that should be made. In fact, HCC patients with TIV are not eligible for resection or liver transplantation, but only for Sorafenib. The second approach negatively affects the median survival rate, that decreases from more than 60 months to less than 11 months in patients with TIV.
There are many evidences in literature that B-mode and Color Doppler ultrasound are functional for detecting HCC, as well as PVT. According to AASLD 2018 Practice Guideline these procedures are recommended biannually in cirrhosis patients as a screening for HCC. However, the accuracy of US for detecting TIV is not optimal [2-3].
This paper, published in European Radiology by Chen and coworkers in February 2020, aims to provide based evidence advice about the diagnostic value of Contrast-enhanced ultrasound (CEUS) in differentiating TIV from PVT in HCC patients.
Authors performed a systematic review and meta- analysis of seven studies (including 425 patients) selected from PubMed, Embase, Cochrane Library, and Web of Science, published up to the 5th of May 2019. The risk of biases within the studies included were evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADS 2) tool. The included studies showed a low risk of bias in patient selection and index test categories but might be at risk in the categories of reference standard and flow and timing.Heterogeneity was calculated by I2 index; publication bias was evaluated by Deek's funnel plot demonstrating a low risk of bias among studies, p=0.54 Diagnostic value of CEUS in differential diagnosis between TIV and PVT was evaluated by the receiver-operating characteristic (ROC) curve analysis and the computed cumulative value of area under the curve (AUC) was 0.97 (95% CI, 0.95-0.98). The pooled sensitivity and specificity of CEUS in diagnosing TIV were 0.94 (95% CI, 0.89-0.97) and 0.99 (95% CI, 0.80-1.0) respectively Combining the results of I2 and sensitivity analysis, the overall heterogeneity was acceptable.
The Fagan plot demonstrated that CEUS increases the probability of diagnosing TIV from 50 to 99% when positive and lowers the probability of malignancy to as low as 5% when negative.
This is the first meta-analysis that summarizes CEUS studies for the diagnosis of TIV and PVT in HCC patients, providing the best level of evidence actually available on this topic.
According with this paper CEUS demonstrated an excellent diagnostic accuracy. It showed a superior sensitivity and specificity than B mode and Color Doppler ultrasound.
Moreover, for its excellent safety profile and diagnostic accuracy in distinguishing between TIV and PVT, authors also suggested CEUS as alternative or substitute for CT and/or MRI. However, we believe that in this specific clinical scenario, more studies are still necessary before suggesting CEUS as alternative to CT or MRI, considering that a direct comparison between CEUS and TC or RM in the same patients’ population remains unsettled.
We should also consider the diagnostic accuracy of CEUS could vary depending on user’s proficiency and experience, and according to the presence of abdominal gas or patients’ body habitus.
Two limitations of the study should be mentioned: this meta-analysis included a limited number of studies; moreover, the reference standard was not consistent among studies and the time interval between CEUS and the standard reference was unclear.
REFERENCES
- Contrast-enhanced ultrasound for the characterization of portal vein thrombosis vs tumor-in-vein in HCC patients: a systematic review and meta-analysis.Chen J, Zhu J, Zhang C, Song Y, Huang P. European Radiology. 2020
- Tarantino L, Francica G, Sordelli I et al (2006) Diagnosis of benign and malignant portal vein thrombosis in cirrhotic patients with hepatocellular carcinoma: color Doppler US, contrast-enhanced US, and fine-needle biopsy. Abdom Imaging 31:537–544
- Dodd GD 3rd, Memel DS, Baron RL, Eichner L, Santiguida LA (1995) Portal vein thrombosis in patients with cirrhosis: does sonographic detection of intrathrombus flow allow differentiation of benign and malignant thrombus? AJR Am J Roentgenol 165:573–577
Dr. Elena Orlando is a first-year radiology resident on the “Sapienza, University of Rome” training scheme in Italy. She completed her undergraduate medical degree at “Sapienza, University of Rome” in 2018. She joined the Medical Imaging Department in 2019 where she in undertaking training in diagnostic and interventional radiology. Her main interests are abdominal and vascular diagnostic radiology.
Comments may be sent to dr.elenaorlando@gmail.com