page_title: Preclinical SPECT
section_title: Multimodality imaging
hierarchical_section_title: Preclinical SPECT / Basic imaging principle of preclinical SPECT / Multimodality imaging
caption_attribution_description: English: The matrix of medical imaging and comparative performance of different imaging modalities
context_page_description: Preclinical or small-animal Single Photon Emission Computed Tomography is a radionuclide based molecular imaging modality for small laboratory animals. Although SPECT is a well-established imaging technique that is already for decades in use for clinical application, the limited resolution of clinical SPECT 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 and, at the same time, allows to perform fast dynamic imaging of animals.
  SPECT imaging requires administration of small quantities of γ-emitting radiolabeled molecules 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 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.
context_section_description: Medical imaging encompasses many different imaging modalities, which can roughly be divided into anatomical and functional imaging. Anatomical modalities (e.g. CT, MRI) mainly reveal the structure of the tissues and organs, while the functional modalities (SPECT, PET and optical imaging) mainly visualize the physiology and function of the tissue. Because none of the existing imaging modalities can provide information on all aspects of structure and function, an obvious approach is to either alter one imaging modality to the task (e.g. special imaging sequences in MRI) or to try to image a subject using multiple imaging modalities. Following the multimodality approach, in recent years the combination of a SPECT/CT system became a standard molecular imaging modality combination in both the pre-clinical and clinical fields, where the structural information of CT complements the functional information from SPECT. Nevertheless, integration of SPCECT with other imaging modalities (e.g. SPECT/MR, SPECT/PET/CT) is not uncommon.
caption: The matrix of medical imaging and comparative performance of different imaging modalities
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