Virtual portal pressure from anatomic CT angiography
Authors: Xiaolong Qi, Mingxin Xu, Zhiwei Li, Changqing Yang
Journal: Journal of Hepatology (2014)

Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinomaJournal of HepatologyVol. 60Issue 5PreviewLiver resection is generally restricted to patients without clinically significant portal hypertension (Hepatic Venous Pressure Gradient – HVPG – ⩽10 mmHg) and several teams perform transjugular HVPG measurements as part of the pre-operative work-up. The present study investigates whether a non-invasive Computed Tomography (CT)-based assessment could be as accurate as the invasive transjugular measurement. Full-Text PDF Reply to: “Virtual portal pressure from anatomic CT angiography”Journal of HepatologyVol. 61Issue 1PreviewWe thank Qi et al. [1] for their interest in our study proposing a non-invasive computed tomography (CT)-based model predicting the level of hepatic venous pressure gradient (HVPG): HVPG score = 17.37–4.91 * ln(Liver/Spleen ratio) + 3.8 [if presence of peri-hepatic ascites], entitled “Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinoma” [2]. Full-Text PDF Open Access We read with great interest the paper “Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinoma”, which proposed a novel CT-based model in the prediction of hepatic venous pressure gradient (HVPG) [[1]Iranmanesh P. Vazquez O. Terraz S. Majno P. Spahr L. Poncet A. et al.Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinoma.J Hepatol. 2014; 60: 969-974Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar]. By combining liver/spleen volume ratio and the presence of peri-hepatic ascites, this non-invasive model had a very good accuracy in predicting HVPG >10 mmHg [[1]Iranmanesh P. Vazquez O. Terraz S. Majno P. Spahr L. Poncet A. et al.Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinoma.J Hepatol. 2014; 60: 969-974Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar]. Although HVPG is the most accurate method to evaluate portal hypertension, this technique is invasive and not routinely performed in all centers. Therefore, emerging non-invasive techniques have been proposed to measure portal pressure. More recently, index computed from CT angiography has created good diagnostic performance compared with “golden standard”. For instance, in the cardiovascular field, fractional flow reserve (FFR) derived from CT angiography (FFRCT) has evolved to become a potential alternative to FFR, an invasive, lesion-specific and well-validated parameter to detect functionally significant coronary artery stenosis. The diagnostic value of FFRCT has been confirmed by landmark multicenter studies, the DISCOVER-FLOW (Diagnosis of Ischemia-Causing Stenoses Obtained Via Non-invasive Fractional Flow Reserve) study [[2]Koo B.K. Erglis A. Doh J.H. Daniels D.V. Jegere S. Kim H.S. et al.Diagnosis of ischemia-causing coronary stenoses by non-invasive fractional flow reserve computed from coronary computed tomographic angiograms. Results from the prospective multicenter DISCOVER-FLOW (Diagnosis of Ischemia-Causing Stenoses Obtained Via Non-invasive Fractional Flow Reserve) study.J Am Coll Cardiol. 2011; 58: 1989-1997Abstract Full Text Full Text PDF PubMed Scopus (927) Google Scholar] and the DeFACTO (Determination of Fractional Flow Reserve by Anatomic Computed Tomographic AngiOgraphy) trial [[3]Min J.K. Leipsic J. Pencina M.J. Berman D.S. Koo B.K. van Mieghem C. et al.Diagnostic accuracy of fractional flow reserve from anatomic CT angiography.JAMA. 2012; 308: 1237-1245Crossref PubMed Scopus (848) Google Scholar]. Our previous study also established a novel non-invasive method for quantifying FFR through three-dimensional modeling from coronary CT data [[4]Qi X. Lv H. Zhou F. Zhao J. Xu J. Xiang L. et al.A novel non-invasive method for measuring fractional flow reserve through three-dimensional modeling.Arch Med Sci. 2013; 9: 581-583Crossref PubMed Scopus (9) Google Scholar]. All the results mentioned above suggested that non-invasive assessment of arterial pressure from CT angiography was feasible and reliable [[5]Taylor C.A. Fonte T.A. Min J.K. Computational fluid dynamics applied to cardiac computed tomography for non-invasive quantification of fractional flow reserve: scientific basis.J Am Coll Cardiol. 2013; 61: 2233-2241Abstract Full Text Full Text PDF PubMed Scopus (825) Google Scholar]. Like the FFRCT to alternate the invasive procedure of FFR, non-invasive techniques for evaluating portal hypertension are established to replace the invasive procedure. Parameters computed from CT angiography are a promising track to follow. The CT-based model conducted by Iranmanesh et al. is of clinical significance with good performance in prediction of HVPG >10 mmHg, with sensitivity, specificity, and positive and negative predictive values of 92%, 79%, 91%, and 81%, respectively [[1]Iranmanesh P. Vazquez O. Terraz S. Majno P. Spahr L. Poncet A. et al.Accurate computed tomography-based portal pressure assessment in patients with hepatocellular carcinoma.J Hepatol. 2014; 60: 969-974Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar]. However, a flaw of the model, like most of non-invasive methods for assessing portal pressure, is that it can effectively only identify severe portal hypertension (HVPG >10 mmHg) but with a poor diagnostic performance in predicting moderate or mild portal hypertension (HVPG ⩽10 mmHg). The discrimination of prediction performance between patients with an HVPG> or ⩽10 mmHg might be due to the presence of peri-hepatic ascites. Therefore, a method assessing moderate or mild portal hypertension is still under investigation. Our preliminary results of the VIRGIN (VIRtual Portal Vein Pressure AGainst INvasive Evaluation) study suggested that the virtual portal pressure by finite element analysis and computational fluid dynamics over three-dimensional CT-model might offer another prediction of moderate or mild portal hypertension without the need of invasive measurement [[6]Qi X. Li Z. Zhou F. Xiao C. Yu L. Ding T. et al.Virtual portal vein pressure from anatomic CT angiography results from the prospective multicenter VIRGIN (VIRtual Portal Vein Pressure AGainst INvasive Evaluation) study.Hepatology. 2013; 58: 986AGoogle Scholar]. In conclusion, we appreciate the ingenuity of the study by Iranmanesh et al. The novel assessment will now be optimized with greater patient numbers and more complex cases. Portal pressure derived from CT angiography data either formula or computational fluid dynamics is promising for liberating patients from invasive procedures. This study was supported by the National Natural Science Foundation of China (81070343); National Natural Science Foundation of China (81370559); Shanghai Science and Technology Innovation Action Plan (12431901002). The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.