Elsevier

European Journal of Radiology

Volume 81, Issue 9, September 2012, Pages 2075-2079
European Journal of Radiology

CT hepatic perfusion measurement: Comparison of three analytic methods

https://doi.org/10.1016/j.ejrad.2011.07.003Get rights and content

Abstract

Objectives

To compare the efficacy of three analytic methods, maximum slope (MS), dual-input single-compartment model (CM) and deconvolution (DC), for CT measurements of hepatic perfusion and assess the effects of extra-hepatic systemic factors.

Materials and methods

Eighty-eight patients who were suspected of having metastatic liver tumors underwent hepatic CT perfusion. The scans were performed at the hepatic hilum 7–77 s after administration of contrast material. Hepatic arterial and portal perfusions (HAP and HPP, ml/min/100 ml) and arterial perfusion fraction (APF, %) were calculated with the three methods, followed by correlation assessment. Partial correlation analysis was used to assess the effects on hepatic perfusion values by various factors such as age, sex, risk of cardiovascular diseases, arrival time of contrast material at abdominal aorta, transit time from abdominal aorta to hepatic parenchyma, and liver dysfunction.

Results

Mean HAP of MS was significantly higher than DC. HPP of CM was significantly higher than MS and CM, and HPP of MS was significantly higher than DC. There was no significant difference in APF. HAP and APF showed significant and moderate correlations among the methods. HPP showed significant and moderate correlations between CM and DC, and poor correlation between MS and CM or DC. All methods showed weak correlations between HAP or APF and age or sex. Finally, MS showed weak correlations between HAP or HPP and arrival time or cardiovascular risks.

Conclusions

Hepatic perfusion values arrived at with the three methods are not interchangeable. CM and DC are less susceptible to extra-hepatic systemic factors.

Introduction

Because various liver diseases lead to significant changes in hepatic microcirculation, quantification of hepatic perfusion can improve the assessment and management of liver diseases. Various imaging techniques, such as xenon-enhanced computed tomography (CT), isotope scintigraphy, and Doppler ultrasound, as well as positron emission tomography using oxygen-15 labeled water, have been used for evaluation of hepatic perfusion. However, their acceptance and clinical application are limited due to high cost, low spatial resolution, or poor reproducibility [1], [2].

CT perfusion with cine imaging and administration of contrast media is a relatively new method of hepatic perfusion analysis in which quantitative maps of tissue perfusion can be created from cine CT data and displayed by using a color scale, which allows for quantification of perfusion in absolute units at high spatial resolution [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]. This method is reportedly useful for evaluation of liver damage or severity of hepatic fibrosis associated with chronic liver disease [3], [4], [5], [6], assessment of hepatic tumor perfusion [7], [8], prediction of tumor response to therapies [9], [10], and evaluation of hepatic perfusion changes after surgical or radiological interventions [11], [12].

However, some problems remain with using this method, such as long breathholding for portal flow measurement, limited cranio-caudal scan range, separation of arterial and portal blood flow, standardization of analytic methods, and unknown effects of extra-hepatic factors [1], [2]. Our study dealt with the latter two problems.

The purpose of this study was thus to compare the efficacy of three analytic methods, maximum slope (MS), dual-input single-compartment model (CM), and deconvolution (DC), for CT measurements of hepatic perfusion and assess the effect of systemic and local factors on hepatic perfusion-related values estimated by CT perfusion. The three methods were the most widely used when this study was started.

Section snippets

Patients

We considered 104 consecutive patients at high risk for malignant liver tumor as candidates in this study. Eight-five of these were suspected to have or had lung cancer, and abdomino-pelvic CT examinations were performed for preoperative systemic survey. CT hepatic perfusion was performed as the baseline study for early detection of liver metastasis in the post-operative period. The other 19 were suspected to have primary malignant liver tumor by ultrasonography or tumor markers done prior to

Results

Mean HAPs, HPPs, and APFs calculated using the three methods were shown in Table 1. Mean HAP of MS was significantly higher than that of DC (p < 0.005). Mean HPP of CM was significantly higher than that of MS (p < 0.0001) or CM (p < 0.0001), and mean HPP of MS was significantly higher than that of DC (p < 0.001). There was no significant difference in APF among the three methods.

Correlation coefficients for the three methods are shown in Table 2. The three methods showed significant and moderate

Discussion

Hepatic CT perfusion is a minimally invasive method and has the advantage of providing highly reliable quantification of hepatic perfusion at low cost. Although many researchers have stressed the clinical usefulness of this technique, some problems remain. Two of these, standardization of analytic methods and evaluation of unknown effects of extra-hepatic factors, which we evaluated in this study, are essential for effective routine clinical use of this technique. The problems in

Conclusion

Perfusion values estimated by means of MS, CM, and DC are not interchangeable. Differences between these analytic methods should be noted. CM and DC are less sensitive than MS to extra-hepatic factors.

Conflicts of interest

Takeshi Yoshikawa: Toshiba Corporation research grant and Koninklijke Philips Electronics NV research grant.

Yoshiharu Ohno: Toshiba Corporation research grant, Koninklijke Philips Electronics NV research grant, Bayer AG research grant, DAIICHI SANKYO Group research grant, Eisai Co., Ltd research grant, Mitsubishi Chemical Holdings Corporation research grant, and Terumo Corporation research grant.

Kazuro Sugimura: Toshiba Corporation research grant, Koninklijke Philips Electronics NV research

Acknowledgements

The authors wish to thank Yoshikazu Kotani, M.D., Yoshihiro Nishimura, M.D., Ph.D. (Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine), and Yoshimasa Maniwa, M.D., Ph.D., Wataru Nishio, M.D. (Division of Thoracic Surgery, Department of Surgery, Kobe University Graduate School of Medicine) for their contributions to this work.

The authors also wish to express special thanks to Hiroyasu Inokawa, M.S., Nao Kishitani, B.S., Yasuko

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