Pinhole SPECT: An approach to in vivo high resolution SPECT imaging in small laboratory animals

TLDR

The study presents the performance of pinhole SPECT and its application for investigating radiopharmaceutical localization in vivo in small laboratory animals. A rotating scintillation camera with a low‑energy pinhole collimator (1.0–3.3 mm apertures) acquires step‑and‑shoot projections around the animal, and images are reconstructed with a modified cone‑beam algorithm derived from fan‑beam filtered backprojection. With a 2.0‑mm pinhole, the system achieves 2.8 mm FWHM transaxial resolution and 0.086 c/s/kBq sensitivity, yielding spatial detail superior to conventional SPECT or PET and enabling accurate imaging of radiopharmaceutical uptake in tumors, organs, and tissues. The article contains 13 references and 8 figures.

Abstract

The performance of pinhole SPECT and the application of this technology to investigate the localization properties of radiopharmaceuticals in vivo in small laboratory animals are presented. System sensitivity and spatial resolution measurements of a rotating scintillation camera system are made for a low-energy pinhole collimator equipped with 1.0-, 2.0- and 3.3-mm aperture pinhole inserts. The spatial detail offered by pinhole SPECT for in vivo imaging was investigated in studies of the brain and heart in Fisher 344 rats by administering {sup 201}TlCl, {sub 99m}Tc-HMPAO, {sup 99m}Tc-DTPA and {sup 99m}Tc-MIBI. Image acquisition is performed using a rotating scintillation camera equipped with a pinhole collimator; projection data are acquired in conventional step-and shoot mode as the camera is rotated 360{degrees} around the subject. Pinhole SPECT images are reconstructed using a modified cone-beam algorithm developed from a two-dimensional fanbeam filtered backprojection algorithm. The reconstruction transaxial resolution of 2.8 mm FWHM and system sensitivity of 0.086 c/s/kBq with the 2.0-mm pinhole collimator aperture provide excellent spatial detail and adequate sensitivity for imaging the regional uptake of the radiophamaceuticals in tumor, organs and other tissues in small laboratory animals. The resolution properties of pinhole SPECT are superior to those which have been achieved thus farmore » with conventional SPECT or PET imaging technologies. Pinhole SPECT provides an important approach for investigating localization properties of radiopharmaceuticals in vivo. 13 refs., 8 figs.« less