The fusion of anatomic and physiologic imaging in the management of patients with cancer

Dual-Modality Imaging: More Than the Sum of its Components

“…The anatomical information from PET/CT improves the differentiation of physiological (normal) uptake of FDG and other radiopharmaceuticals from that associated with disease, and thereby can reduce false positive errors in comparison to lesion characterization when radionuclide imaging is used alone. By providing high-resolution anatomical information from CT, dual-modality imaging also correlates functional and anatomical data to improve disease localization 14,38,39,41,61 and facilitates treatment planning for radiation oncology 12,72 or surgery. 68,73,74 3.…”

“…A significant success of PET/CT has been the improved image quality of FDG images for tumour localization. 38,39,41,61 The major use of SPECT/ CT has been in reducing attenuation artefacts and improving the quality of myocardial perfusion imaging with 99m Tc-sestamibi. 21,59,[62][63][64] SPECT/CT also has demonstrated advantages for oncologic imaging with single-photon agents.…”

“…[33][34][35] Similarly, SPECT/CT systems use conventional dual-headed scintillation cameras suitable for planar scintigraphy or tomographic imaging of single-photon radionuclides, or coincidenceimaging of PET radiopharmaceuticals. The first-generation clinical SPECT/CT scanners used a low-resolution CT detector 40,41,70,105 that offered relatively modest scan times (i.e., approximately 20 seconds per slice). However, newer SPECT/CT scanners now are becoming available that incorporate state-of-the-art multislice helical CT scanners identical to those used for diagnostic CT procedures.…”

“…This can be achieved in several ways. In first generation SPECT/ CT systems, 40,41,70,105 the SPECT detectors and CT imaging chain were mounted on the same rotating platform and were used sequentially while rotated around the patient. This limited the rotational speed of the x-ray and radionuclide imaging chains to approximately 20 sec per rotation, but also had the advantage that it could be performed using a gantry similar to that used with a conventional scintillation camera.…”

“…21,59,[62][63][64] SPECT/CT also has demonstrated advantages for oncologic imaging with single-photon agents. 12,25,40,41,[65][66][67][68][69][70] Both SPECT/CT and PET/CT have demonstrated their ability to facilitate attenuation correction using an x-ray based patientspecific attenuation map that can be produced faster and more accurately than attenuation maps generated with external radionuclide sources. 10,34 Clinical studies are underway to evaluate the applicability of x-ray based correction of photon attenuation, 71 and early results demonstrate improvement in sensitivity, specificity, and predictive accuracy in comparison to SPECT perfusion studies reconstructed without correction for photon attenuation.…”