Initial results of a mouse brain PET insert with a staggered 3-layer DOI detector

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Small animal positron emission tomography (PET) demands submillimeter resolution for precise radiopharmaceutical quantification.
• Depth-of-interaction (DOI) detection is crucial for maintaining spatial resolution and sensitivity in PET scanners.
• Previous work developed a staggered 3-layer DOI detector but lacked full ring imaging performance demonstration.

Purpose of the Study:

• To present initial imaging results from a mouse brain PET prototype incorporating a staggered 3-layer DOI detector.
• To evaluate the imaging performance of the DOI detector in a full ring geometry for small animal brain studies.
• To demonstrate the capability of the prototype for visualizing fine anatomical details in the mouse brain.

Main Methods:

• Developed a PET scanner prototype with a 53 mm inner diameter and 11 mm axial field-of-view, using 16 staggered 3-layer LYSO DOI detectors.
• Each detector featured a 1 mm crystal pitch and was coupled to a 4x4 silicon photomultiplier array.
• Evaluated physical performance using the NEMA NU 4 2008 protocol, including spatial resolution and sensitivity measurements.

Main Results:

• Achieved spatial resolutions of 0.67 mm at the center and 1.56 mm at a 15 mm radial offset using filtered-back-projection.
• Recorded a peak absolute sensitivity of 0.74% within a 400-600 keV energy window.
• Demonstrated clear visualization of submillimeter rod patterns (0.75 mm) using ordered-subset expectation maximization and inter-crystal scatter rejection.

Conclusions:

• Successfully developed a mouse brain PET insert prototype utilizing a staggered 3-layer DOI detector.
• The prototype achieved high contrast and clearly identified detailed mouse brain structures like the cortex and thalamus.
• The DOI detector technology is effective for high-resolution small animal brain imaging.