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4D-CT Simulation Using Individually Optimized Contrast Enhancement (CE): A Phantom Study

M Xue

M Xue1*, W D'Souza1, G Lasio1, P Klahr2, W Lu1, (1) University of Maryland Baltimore, Baltimore, MD, (2) Philips Healthcare

TU-C-213CD-5 Tuesday 10:30:00 AM - 12:30:00 PM Room: 213CD

Purpose: Contrast-enhanced (CE) 4D-CT has the advantage of both visualizing an abdominal tumor and estimating its motion in a single scan. Considering the large variation in the peak CE time from one patient to another, we propose to optimize the contrast injection delay time for individual patients so that the CE is maximized when scanning the tumor region in CE 4D-CT.

Methods: We designed a flow phantom simulating the contrast enhancement and washing out in an organ. Peak CE time of a test injection (Tpeak.test) with 10 ml contrast was used to estimate the peak CE time of a full injection (Tpeak) with 140 ml contrast in the CE 4D-CT: Tpeak = Tpeak.test + (TID-TID.test), where TID.test and TID are the corresponding injection durations. We then computed an optimal contrast injection delay time, TIV = TO - Tpeak, where TO is the 4D-CT scan time from the starting position to the center of phantom. To verify that maximal CE is achieved with TIV, we performed five CE 4D-CT scans using an injection delay time of TIV + ΔT, where ΔT = +6, +3, 0, -3, and -6 s. The CE in a volume of interest at the center of the phantom was measured in each 4D-CT.

Results: The phantom showed good reproducibility about ±1 s in the peak CE time of both test injection and full injection. The 4D-CT using the optimal TIV (ΔT = 0) showed the maximum contrast enhancement. The larger deviation from TIV, the lower was contrast enhancement. These results verified that the estimated optimal injection time delay achieved maximum contrast enhancement.

Conclusions: It is feasible to estimate individually optimized injection delay time to maximally enhance a region or organ of interest in CE 4D-CT.

This study is supported in part by Philips Healthcare.

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