Advances in pulmonary nuclear medicine.

Nuclear medicine plays a major role in the diagnosis of pulmonary embolism as well as in other lung diseases. Important innovations have concerned in recent years the equipment and radiopharmaceuticals. In ventilation studies the use of technegas, a monodisperse aerosol able to supply images of the same quality or even superior to gas images, is widespread in the clinical practice. Significant clinical results in the evaluation of acute thromboembolism have been achieved with antifibrin monoclonal antibodies and radioactive peptides specific for activated platelet receptors. Primary lung cancer and its metastases can now be visualized with tracers used for the study of myocardial perfusion (sestaMIBI, tetrofosmin) or labeled ocreotide, a molecule able to recognize lung tumors with somatostatin receptors. 99mTc-NR-LU-10 Fab immunoscintigraphy was shown to be very sensitive for tumors, while the major role of PET in the differential diagnosis of solitary pulmonary nodule, in the initial staging and in the response assessment to lung cancer therapy, is confirmed. SPECT is widespread in the clinical field with the use of 2-3 head gamma cameras and the possible combined imaging with CT or MRI. The use of PET with common gamma cameras with appropriate collimation systems or coincident recording without collimation is being studied. PET is used in the study of tumor metabolism as well as in the evaluation of intra-and extravascular lung water, regional blood flow and pulmonary vascular permeability. PET studies of vascular lung physiology as well as of receptor physiology, amine accumulation and clearance and drug transport to the areas of healthy or impaired lung, were also shown to be fundamental.