Preclinical SPECT

High resolution 99mTc-MDP mouse scan acquired with a stationary SPECT system: animated image of rotating maximum intensity projections.

Preclinical or small-animal Single Photon Emission Computed Tomography (SPECT) is a radionuclide based molecular imaging modality for small laboratory animals[1] (e.g. mice and rats). Although SPECT is a well-established imaging technique that is already for decades in use for clinical application, the limited resolution of clinical SPECT (~10 mm) stimulated the development of dedicated small animal SPECT systems with sub-mm resolution. Unlike in clinics, preclinical SPECT outperforms preclinical coincidence PET in terms of resolution (best spatial resolution of SPECT - 0.25mm,[2] PET ≈ 1 mm[3][4] ) and, at the same time, allows to perform fast dynamic imaging of animals (less than 15s time frames[5]).

SPECT imaging requires administration of small quantities of γ-emitting radiolabeled molecules (commonly called "tracers") into the animal prior to the image acquisition. These tracers are biochemically designed in such a way that they accumulate at target locations in the body. The radiation emitted by the tracer molecules (single γ-photons) can be detected by gamma detectors and, after image reconstruction, results in a 3-dimensional image of the tracer distribution within the animal. Some key radioactive isotopes used in preclinical SPECT are 99mTc, 123I, 125I, 131I, 111In, 67Ga and 201Tl.

Preclinical SPECT plays an important role in multiple areas of translational research[6] where SPECT can be used for non-invasive imaging of radiolabeled molecules, including antibodies, peptides, and nanoparticles. Among major areas of its applications are oncology, neurology, psychiatry, cardiology, orthopedics, pharmacology and internal medicine.

  1. ^ Meikle SR, et al. Small animal SPECT and its place in the matrix of molecular imaging technologies. Phys Med Biol. 2005; 50(22):R45-61.
  2. ^ Ivashchenko et al. Quarter-Millimeter-Resolution Molecular Mouse Imaging with U-SPECT+. Mol Imaging. 2014.
  3. ^ Walker MD, et al. Performance Assessment of a Preclinical PET Scanner with Pinhole Collimation by Comparison to a Coincidence-Based Small-Animal PET Scanner. J Nucl Med. 2014; 55(8):1368-1374.
  4. ^ Tai Y, et al. Performance Evaluation of the microPET Focus: A Third-Generation microPET Scanner Dedicated to Animal Imaging. J Nucl Med. 2005; 46(3):455-463.
  5. ^ Vaissier PEB, et al. Fast spiral SPECT with stationary γ-cameras and focusing pinholes. J Nucl Med. 2012; 53(8):1292-9.
  6. ^ Bernsen MR, et al. The role of preclinical SPECT in oncological and neurological research in combination with either CT or MRI. Eur J Nucl Med Mol Imaging. 2014; 41(1):36-49.