PET versus SPECT: strengths, limitations and challenges

Abstract

The recent introduction of high-resolution molecular imaging technology is considered by many experts as a major breakthrough that will potentially lead to a revolutionary paradigm shift in health care and revolutionize clinical practice. This paper intends to balance the capabilities of the two major molecular imaging modalities used in nuclear medicine, namely positron emission tomography (PET) and single photon emission computed tomography (SPECT). The motivations are many-fold: (1) to gain a better understanding of the strengths and limitations of the two imaging modalities in the context of recent and ongoing developments in hardware and software design; (2) to emphasize that certain issues, historically and commonly thought as limitations of one technology, may now instead be viewed as challenges that can be addressed; (3) to point out that current state of the art PET and SPECT scanners can (greatly) benefit from improvements in innovative image reconstruction algorithms; and (4) to identify important areas of research in PET and SPECT imaging that will be instrumental to further improvements in the two modalities. Both technologies are poised to advance molecular imaging and have a direct impact on clinical and research practice to influence the future of molecular medicine.

The Use of Anatomical Information for Molecular Image Reconstruction Algorithms: Attenuation/Scatter Correction, Motion Compensation, and Noise Reduction

“…In SPECT, unlike PET, different attenuation values should be assigned to the pairs between each LOR and all voxels in that LOR [66]. Thus, the decomposition of the matrix P can be done by a component-wise multiplication P = A G where A is not a diagonal matrix anymore [67].…”

Vitamin B12–Metal Conjugates for Targeted Chemotherapy and Diagnosis: Current Status and Future Prospects

“…However, SPECT techniques typically have lower sensitivity and resolution than PET, which is widely used for quantitative analysis of radiopharmaceuticals in vivo. [80] For this purpose, the use of copper-64 (t 1/2 = 12.6 h), primarily as PET tracer but also as a radiotherapeutic, has been increasing strongly over the last 20 years. Its favorable decay characteristics, together with its well-established coordination chemistry, have led to the development of 64 Cu-labeled biological molecules for tumor targeting by use of monoclonal antibodies and peptides.…”

Advances in multimodality molecular imaging of bone structure and function

“…Similarly, positron emission tomography (PET) is based on the coincidence detection of two gamma rays that formed through the annihilation of positrons emitting from the radionuclide and electrons in the host tissue, allowing localizing biological signals of interest. 13 Optical imaging techniques rely on the detection of photons and include near-infrared fluorescence imaging, fluorescence molecular tomography (FMT) and bioluminescence imaging (BLI). For near-infrared fluorescence imaging and FMT, fluorophores, consisting of a fluorochrome bound to a reporter construct that allows binding of the probe to a biological signal of interest, are administrated.…”