Abstract
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Objectives: Hybrid SPECT/CT is a technology using an integrated Anger gamma camera and in-line CT to acquire co-registered functional and anatomic imaging datasets, that can be viewed in side-by-side or fused modes. Our goal is to present pediatric nuclear medicine scans with use of co-registered SPECT/CT that provide additional diagnostic information that help image interpretation. We discuss indications for using SPECT/CT in children, describe protocols and review the literature.
Methods: We reviewed radionuclide studies in which SPECT/CT had been performed in a problem-solving capacity at C.S. Mott Children’s and St Jude Children's Research hospitals with a Siemens Symbia T16/T6/T2/T Series. If requested, the patients were imaged with sedation or general anaesthesia administered by anesthesiology personnel. The planar or planar/SPECT images are initially reviewed by a Nuclear Medicine Physician and the decision made to acquire SPECT/CT through a field of view encompassing the radioactivity of interest. SPECT/CT provides invaluable localization of radioactivity to anatomic structures, and we selected exemplary cases demonstrating the incremental diagnosis value of SPECT/CT.
Results: SPECT/CT aided interpretation in a wide range of nuclear medicine studies including MIBG, bone, thyroid, thyroid cancer, Meckel scan, lymphoscintigraphy, parathyroid and miscellaneous studies. Localization of uptake to an organ structure aided characterization of uptake, increased diagnostic confidence and reduced need for additional CT correlation. Hybrid SPECT/CT has increasing evidence in the literature in adult populations for incremental diagnostic value, although has been slower to be utilized in pediatric studies due to concerns about appropriate indications, prolonging sedation, and avoiding unnecessary ionizing radiation exposure. Benefits include localization and characterization, reduction of equivocal findings, distinguishing physiological from pathological uptake, gains in sensitivity, specificity and reader confidence, surgical planning, and to avoid additional diagnostic CT. Concerns about ionizing radiation in children are that tissues are more radiosensitive and there is a longer life expectancy during which to manifest any potential consequences of radiation exposure. Unlike the SPECT acquisition in which the radiation exposure has already been received as part of the scan, CT adds additional modest exposure to the study. Yet the benefit of this non-diagnostic low-dose CT component is already accepted in PET/CT, such that no stand-alone PET scanners are in production. Therefore in pediatric diseases, use of SPECT/CT to achieve accurate characterization, localization, and evaluation of disease response may be desirable to facilitate proper management.
Conclusion: SPECT/CT is a valuable newer technology that can aid accurate diagnosis in the pediatric population. The incremental benefits for scan interpretation need to be balanced against the modest radiation exposure additional to the radionuclide radiotracer. Research Support: None