SIR 2024
Imaging
Rajesh Shah, MD
Director of Interventional Radiology
California Pacific Medical Center
Financial relationships: Full list of relationships is listed on the CME information page.
Sirish Kishore, MD
Interventional Radiologist
Palo Alto Veterans Affairs Healthcare System/Stanford University School of Medicine
Disclosure information not submitted.
Eugene Huo, MD
Interventional Radiology
VA Palo Alto Health Care System
Disclosure information not submitted.
Dale Marek, None
Manager Medical Affairs - Clinical Development
Canon
Disclosure information not submitted.
Yiemeng Hoi, PhD
Leader Medical Affairs, Vascular Business Unit
Canon Medical Systems USA, Inc.
Disclosure information not submitted.
To determine the feasibility of using CT perfusion with intra-arterial injection during treatment for hepatocellular carcinoma (HCC) using filtered back projection (FBP) and iterative reconstruction (ItR) algorithms while minimizing radiation dose.
Materials and Methods: This was a prospective observational study approved by the local institutional review board. Nine patients undergoing intra-arterial therapy (IAT) within Interventional Radiology (IR) for LI-RADS 5 HCC without treatment in the previous year were enrolled. Subjects underwent injection of a 50% dilution of Iohexol 300 mgI/mL from either the celiac artery at 3 mL/sec for a total volume of 24 mL for conventional hepatic arterial anatomy, or from the superior mesenteric artery (SMA) for replaced hepatic arterial anatomy at an increased rate of 5 mL/sec for a total volume of 40 mL to account for flow into mesenteric vessels. CT perfusion scanning was performed continuously for 11 sec, then every 2 sec until a total scan time of 40 sec to capture arterial, portal venous, and washout phases. To minimize radiation dose, scanning parameters were kept constant at 100 kV and 60 mA for each patient. Imaging was reconstructed using both the FBP method as well as the ItR method. Using a dedicated workstation, a region of interest (ROI) was drawn on the common hepatic artery, portal vein, spleen (celiac injections) or small bowel (SMA injections), and non-tumorous liver by a single Radiologist. Arterial blood flow (AF), portal venous blood flow (PVF), and perfusion index (PI) were calculated from an ROI drawn on a single index tumor 1.5 cm or larger in size that had no prior treatment. Descriptive statistics were derived. Comparison of perfusion values using ItR and FBP were performed using a paired t-test with p < 0.05 considered statistically significant.
Results: Using ItR, the mean (SD) for AF, PVF, and PI were 480 (± 107.1), 484.8 (± 524.1), and 63 (± 26.1) mL/min/100 mL, respectively. For FBP, the mean (SD) for AF, PVF, and PI were 495.2 (± 163), 574.8 (± 619.5), and 60 (±21.5) mL/min/100 mL, respectively. There was no significant difference in perfusion values between ItR and FBP for AF (p = 0.78), PVF (p = 0.56), and PI (p = 0.31) despite a qualitatively noisy appearance of the FBP images.
Conclusion: CT Perfusion is feasible using low dose imaging techniques using either of the two most widely used reconstruction algorithms. This may provide greater flexibility in use of perfusion during IR therapies such as tumor identification or treatment planning.