Gated listmode acquisition with the quadHIDAC animal PET to image mouse hearts.

Purpose: The aim of this study was to develop ECG and respiratory gating in combination with listmode acquisition for the quadHIDAC small-animal PET scanner.

Methods: ECG and respiratory gating was realized with the help of an external trigger device (BioVET) synchronized with the listmode acquisition. Listmode data of a mouse acquisition (injected with 6.5 MBq of 18F-FDG) were sorted according to three different gating definitions: 12 cardiac gates, 8 respiratory gates and a combination of 8 cardiac and 8 respiratory gates. Images were reconstructed with filtered back-projection (ramp filter), and parameters like left ventricular wall thickness (WT), wall-to-wall separation (WS) and blood to myocardium activity ratios (BMR) were calculated.

Results: Cardiac gated images show improvement of all parameters (WT 2.6 mm, WS 4.1 mm, BRM 2.3) in diastole compared to ungated images (WT 3.0 mm, WS 3.4 mm, BMR 1.3). Respiratory gating had little effect on calculated parameters.

Conclusion: ECG gating with the quadHIDAC can improve myocardial image quality in mice. This could have a major impact on the calculation of an image-derived input function for kinetic modelling.