Wolfgang M. Thaiss, Presenter: Nothing to Disclose

Ulrike Haberland, Abstract Co-Author: Employee, Siemens AG

Konstantin Nikolaou MD, Abstract Co-Author: Speakers Bureau, Siemens AG Speakers Bureau, Bracco Group Speakers Bureau, Bayer AG

Marius Horger MD, Abstract Co-Author: Nothing to Disclose

Alexander Sauter, Abstract Co-Author: Nothing to Disclose

Iodine-related attenuation (IRA) acquired with dual energy CT is regarded as a perfusion surrogate marker. The purpose of the study was to compare this technique with Volume Perfusion CT (VPCT) in HCC patients.

After approval, 20 patients (mean age 69.2) with untreated HCC were enrolled in a liver perfusion at 80 kV, using a Siemens Somatom Definition AS+. VPCT evaluation and ROI measurements – encompassing the maximum tumor outline - were carried out using a dedicated postprocessing software (syngo Volume Perfusion CT Body, Siemens). 20 lesion were evaluated. Next, the time-resolved perfusion scans were split in single time points. IRA maps were calculated for the time points in 3.5 sec steps starting at the peak enhancement of the abdominal aorta. Finally, the same VPCT-tumor-ROI was drawn and iodine concentration (IC) values were calculated for the 80 kV scans.  

VPCT perfusion parameters were as follows: (tumor): blood flow (BF) 51.7 ± 17.0 (mL/100 mL/min), blood volume (BV) 12.6 ± 4.3 (mL/100 mL); (liver): arterial liver perfusion (ALP) 42.4 ± 15.0 (mL/100 mL/min), portal-venous perfusion (PVP) 10.3 ± 9.1 (mL/100 mL/min), hepatic arterial perfusion index (HPI) 84.4 ± 12.6. Peak enhancement in the lumen of the aorta was reached at 17.6 ± 4.4 sec. Tumor IC (mg/dL) for the different time points: 65.9 ± 41.2 (at peak enh. aorta), 110.6 ± 65.3 (p. enh. a. + 3.5 sec), 129.1 ± 61.7 (+ 7 sec), 131.6 ± 56.0 (+ 10.5 sec), 126.9 ± 46.6 (+ 14 sec), 115.6 ± 44.1 (+ 17.5 sec). Highest time-point correlations between perfusion parameters and IC: BF & IC r = 0.683 at peak enh. ao. + 7 sec (P = 0.001), BV & IC r = 0.640 peak enh. ao. (P = 0.003), ALP & IC r = 0.802 (+ 7 sec) (P < 0.001), PVP & IC no correlation, HPI & IC r = 0.477 peak enh. ao. (P = 0.003).  

In HCC, the evaluated tumor IC are not as robust as VPCT measurements, reflected by higher standard deviations. Good correlations between IC values and BF, BV, ALP could be found. If dual-energy iodine maps should reflect BV or HPI, a scan 7 seconds after the aortic peak enhancement is recommended. However, VPCT with kinetic modeling allows for the differentiation of various perfusion parameters.

The significance of IRA as a perfusion surrogate from dual-energy is unclear. Therefore we’ve performed a comparison with VPCT in HCC, showing a good correlation but lack of robustness of IRA as compared to quantitative VPCT.

Thaiss, W, Haberland, U, Nikolaou, K, Horger, M, Sauter, A, Elucidation of the Perfusion Characteristics of Dual-energy Iodine-related Attenuation in Hepatocellular Carcinoma Using Volume Perfusion CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009071.html