An Evidence-Based Review of Quantitative SPECT Imaging and Potential Clinical Applications

Abstract

Learning Objectives: On successful completion of this activity, participants should be able to (1) review the current status of SPECT imaging, with an emphasis on clinical applications for quantitative interpretations; (2) consider the requirements for quantitative SPECT imaging-instrumentation, software, and image calibration; and (3) acquire knowledge of the capabilities of quantitative SPECT with a view to developing new clinical applications.Financial Disclosure: Dr. Bailey is an employee of NSW Health, University of Sydney, and an investigator for NHMRC, ARC, Cure Cancer Australia. Dr.Willowson is an employee of the University of Sydney and is supported by the Australian Research Council and the NSW Cancer Council in conjunction with the Cure Cancer Australia Foundation. The authors of this article have indicated no other relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, participants can access this activity through the SNMMI Web site (http:// www.snmmi.org/ce_online) through January 2016.SPECT has traditionally been regarded as nonquantitative. Advances in multimodality g-cameras (SPECT/CT), algorithms for image reconstruction, and sophisticated compensation techniques to correct for photon attenuation and scattering have, however, now made quantitative SPECT viable in a manner similar to quantitative PET (i.e., kBqÁcm 23 , standardized uptake value). This review examines the evidence for quantitative SPECT and demonstrates clinical studies in which the accuracy of the reconstructed SPECT data has been assessed in vivo. SPECT reconstructions using CT-based compensation corrections readily achieve accuracy for 99m Tc to within 610% of the known concentration of the radiotracer in vivo. Quantification with other radionuclides is also being introduced. SPECT continues to suffer from poorer photon detection efficiency (sensitivity) and spatial resolution than PET; however, it has the benefit in some situations of longer radionuclide half-lives, which may better suit the biologic process under examination, as well as the ability to perform multitracer studies using pulse height spectroscopy to separate different radiolabels.Key Words: SPECT (single-photon emission computed tomography); quantification; scatter correction; attenuation correction; validation Nucl Med 2013; 54:83-89 DOI: 10.2967/jnumed.112.111476 Quant itative emission tomography is a powerful investigative tool in clinical practice and biomedical research. The two principal forms of emission tomography using radionuclide-labeled compounds are SPECT and PET. Although PET has a tremendous sensitivity advantage and higher spatial resolutio...

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