Charlie Fife Michael Pitcairn ,Michal Kawka ,

Department of Medicine, Imperial College London, South Kensington Campus, London SW7 2AZ, UK

TotheEditor:

We would like to congratulate Tian and colleagues on their recent article:Diagnosticvalueofcontrast-enhancedultrasonographyforintrahepaticcholangiocarcinomawithtumordiameterlarger than5cm [1].They argued that,despite not being included in the American Association for the Study of Liver Diseases (AASLD)guidelines for the diagnosis of liver diseases,contrast-enhanced ultrasonography (CEUS) can be of use for diagnosis of large (>5 cm),mass-forming intrahepatic cholangiocarcinoma (ICC).We would like to highlight the added value that CEUS can present in low-resource settings,where other diagnostic modalities may be neither cost-effective nor readily available.

Although its incidence is rising,ICC remains a rare cancer in the Western countries.However,it is a cause of significant morbidity and mortality in East Asia,where its etiology is associated with chronic liver fluke infection.In some regions,such as North-East Thailand,the incidence can be as high as 85 per 100000 people [2].Furthermore,the prognosis of cholangiocarcinoma(CCA) patients is poor since the disease is initially asymptomatic,and thus seldom diagnosed before it has progressed to an advanced stage [3].As such,early and accurate diagnosis is paramount to improving CCA survival,which is extremely low (5-year survival of 7%-20%) [3].

Multiple diagnostic modalities are available for the detection of ICC,ranging from biomarkers (CA19-9) to imaging techniques such as CT,MRI,cholangiography or PET scans [4].Even though these techniques can be accurate,they might not be readily available in the regions where CCA incidence is the highest.These regions are also often those with limited access to healthcare resources,especially sophisticated imaging infrastructure [5].

CEUS has been previously shown to be effective in identifying mass-forming ICC and differentiating it from hepatocellular carcinoma,as ICC exhibits a characteristic peripheral rim-enhancement and quick contrast washout (less than 60 s) [6–8].What is more,economic evaluation of CEUS (average cost €85.44 per scan) has demonstrated its cost-effectiveness relative to CT ( €155.03) and MRI ( €174.58) scans,which is of particular value in resource-poor regions [9].

With an expanding evidence base for the use of CEUS in the detection and characterisation of ICC,its role in focal liver disease diagnostics is likely to increase.This,coupled with the relative costeffectiveness of its implementation and subsequent day-to-day utilization,makes CEUS an important diagnostic tool in low-resource settings,where the use of more expensive techniques such as MRI,CT or PET can be limited.

Acknowledgments

None.

CRediTauthorshipcontributionstatement

CharlieFifeMichaelPitcairn:Conceptualization,Writing -original draft,Writing - review ＆ editing.MichalKawka:Conceptualization,Writing - original draft,Writing - review ＆ editing.

Funding

None.

Ethicalapproval

Not needed.

Competinginterest

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.