Hybrid SPECT/CT

The last 20 years have seen the integration of computed tomography (CT) with positron emission tomography (PET) and single photon emission computed tomography (SPECT). CT represents a fundamental tool for medical diagnosis, but it only provides anatomical details. Since physiological activities can occur even in the absence of anatomical changes, it may be necessary to use an imaging technique able to reveal functional or metabolic modifications. The SPECT technique provides metabolic and functional information, allowing major insights into the patient's physiological condition. This technique produces tomographic images which depict the distribution of administered radiotracers that emits gamma-rays. Since the attenuation of gamma-rays within the patient can affect the accuracy of SPECT images, it becomes necessary to apply an attenuation correction. The advantages of integrating SPECT and CT are not only limited to obtaining accurate attenuation correction, indeed, the combined system allows better control of the patient's orientation. And above all, there is added value due to the presence of co-registered anatomical images which also allow complementary diagnostic studies. Therefore, the integration of SPECT and CT imaging has increasingly gained general interest and demonstrated its usefulness in the management of clinical patients. Moreover, hybrid SPECT/CT allows absolute quantification in terms of activity concentration. It is, therefore, a useful tool in developing personalized treatment strategies. The significant possibility of quantitative measurements will certainly be a valuable tool in the next era of healthcare, which is moving towards precision medicine and theranostic.