Functional-anatomical image fusion in neuroendocrine tumors

Nuclear medicine provides physiologic and functional data for normal and pathologic organs but often the clear definition of the sites of radiotracers' uptake are difficult. Radiological methods are able to identify structural changes in a detailed way, but do not give precise information on function of organs or pathologic lesions. The registration and fusion of nuclear medicine studies with structural information obtained by radiological exams allows the precise correlation of functional and anatomical data. Software-based fusion of independently performed nuclear medicine and morphologic studies is uncertain of success and the alignment procedures are labor intensive. Recently, a new imaging device combining a dual-head, variable angle gamma camera with a low-dose x-ray tube has been introduced; the acquired single-photon emission computed tomography (SPECT) and x-ray computed tomography (CT) images are coregistered by means of the hardware in the same session. This new technology can be particularly useful when applied to scintigraphic procedures in neuroendocrine tumors. In-111 pentetreotide and radio-labeled MIBG play an important role in the study of patients with these tumors; the addition of anatomical maps provides a precise localization of SPECT findings and allows the exclusion of disease in sites of physiologic tracer uptake. SPECT/CT fused images are able to provide additional information that improves the accuracy of SPECT interpretation and leads to changes in therapeutic options, so enhancing the clinical role of nuclear medicine in evaluating patients with neuroendocrine tumors.