Room: Exhibit Hall | Forum 9
Purpose: Recently a low dose CT perfusion (CTP) method has been introduced that is able to reduce radiation dose by 75% based on projection view sharing using the K-space weighted image contrast (KWIC) reconstruction (Martin 2018). The purpose of this study is to validate this method on a CTP phantom that is designed to mimic the injection of a contrast bolus and generate precise time-attenuation curves of differing velocities.
Methods: A CTP phantom (Gammex, Inc) was scanned on a Ceretom CT (Neurologica, Inc) using a standard CTP protocol (10mm slice, 100kV, 6mA, 1sec/turn, 360 projections per half turn (180 degrees), 30 images, 328mGy). The CTP phantom is ACR and FDA compliant and generates arterial, venous, and tissue curves to simulate a typical CTP scan. Filtered back projection (FBP) with all the projections per half turn was used as baseline. A â€œfull doseâ€? scan was defined as using all the projections from the CT acquisition per half turn. Reduced dose cases were retrospectively down-sampled by reducing the number of projections from 360 to 180, 90, and 45. KWIC reconstruction was performed for each undersampling. The area-under-the-curve (AUC) and full-width-half-maximum (FWHM) of arterial, venous, and tissue curves were measured and compared to those by FBP.
Results: Figure 1 shows that the KWIC reconstruction preserves the image quality with reduced dose, while streaking artifacts are present in FBP images with reduced projections. The FWHM and AUC were not significantly affected by the KWIC reconstruction (Table 1). The time plots also show good agreement of the contrast uptake between the different reconstructions (Figure 2).
Conclusion: This study validates that low dose CTP with projection view sharing and KWIC reconstruction preserves image quality and semi-quantitative perfusion metrics up to 75% reduced dose projections, using an ACR/FDA compliant CTP phantom. Its clinical utility requires further evaluation.
Funding Support, Disclosures, and Conflict of Interest: Funding for the study was from R41-EB024438 Thomas Martin and Danny Wang are inventors of a patent on low-dose CTP held by UCLA. Thomas Martin and Danny Wang hold shares in Hura Imaging, LLC.
Not Applicable / None Entered.