Design and characterization of a flat panel virtual-pinhole PET insert for zoom-in imaging applications

Objectives A flat panel virtual-pinhole (VP) PET insert is being developed to enable organ specific imaging applications without the need of dedicated PET scanners. This VP-PET insert works in conjunction with a clinical PET/CT scanner to provide whole body images with enhanced sensitivity and spatial resolution in the area close to the insert. This study characterizes a new prototype VP-PET insert device and demonstrates its imaging capability.

Methods The proposed panel consists of 32 detectors arranged in an 8 x 4 array. Each detector module consists of a 16 × 16 LYSO crystal array (1 × 1 × 3 mm³) read out by a 4 × 4 silicon photomultiplier array. The panel has an active sensing area of 13.4 × 6.6 cm² and is integrated into a Siemens Biograph 40 scanner that has modified readout electronics and coincidence logic to support the new functions.

Results All detector modules have excellent flood histogram, and have an average energy resolution of 10.19 ± 0.68% FWHM at 511 keV and a timing resolution of 0.95 ± 0.08 ns FWHM. Monte Carlo studies show spherical lesions of 4.0 mm in diameter and 10:1 lesion-to-background contrast can be clearly delineated. Experimental results will be presented at the conference.

Conclusions A flat panel VP-PET insert can be positioned against any region of interest in a patient to improve image resolution locally while maintaining the whole body imaging capability. This unique feature is otherwise unavailable by organ-specific PET systems. Immediate applications may include imaging of internal lymph nodes and tumor heterogeneity. Improvement in diagnostic accuracy and novel clinical applications will require further large scale imaging trials.

Research Support This research was supported in part by the U.S. NSF (DBI-1040498), DOE (DE-SC0005157) and NIH (CA136554).