Clinical Applications and Usefulness of Integrated Single Photon Emission Computed Tomography/Computed Tomography Imaging

Radiopharmaceuticals reflect physiologic and pathologic functions rather than anatomical abnormalities. In the clinical setting, it is often necessary to correlate these functional studies using anatomical imaging. The advent of single photon emission computed tomography (SPECT) and positron emission tomography (PET) provides tomographic images for direct correlation to anatomic modalities such as X-ray, computed tomography (CT) and magnetic resonance imaging. Correlation of anatomic and functional information can aid in the decision-making process by enabling better localization and definition of organs and lesions and improving the precision of surgical biopsies. The advantages of combining SPECT with CT are primarily due to the anatomical referencing and the attenuation correction capabilities of CT. Depending on the system design, there are varying technical issues surrounding the different SPECT/CT devices. The principle of the integrated SPECT/CT instrumentation and the use of attenuation correction and anatomical referencing are discussed in this review. The specific disease processes where SPECT/CT has had a positive impact on diagnostic accuracy will be illustrated in this review. Although it is starting more slowly than PET/CT, SPECT/CT has many existing and potential areas of clinical application and has significantly added to the diagnostic power of nuclear medicine. Through literature review and case presentation, the authors illustrate the applications and uses of SPECT/CT as experienced at Tzu Chi General Hospital. The most common uses of SPECT/CT were for the diagnoses of infections focused with gallium-67 citrate, 99mTc-sulfurcolloid sentinel lymph node mapping, thyroid cancer survey with 131I-sodium iodide, parathyroid scan with 99mTc-Sestamibi, abdominal diseases, and bone imaging with 99mTc-methylene diphosphonate. Through this review, the authors also highlight the current comprehensive clinical use of SPECT/CT in our hospital.