Nuclear Medicine Imaging of Lung Infection

Sollini, Martina; Mariani, Giuliano

Acute or chronic infection of the upper or lower respiratory tract caused by microorganisms (bacteria, viruses, fungi, or parasites) causes discomfort and affects the day-to-day life of patients and can become severely complicated. The diagnosis of lung infection is generally based on clinical findings associated with the detection of parenchymal infiltrate at chest X-ray or CT scan. However, in some instances, radiological imaging alone cannot distinguish an acute exacerbation from sequela of a prior infection. Nuclear medicine imaging techniques have been extensively used in patients with lung infection, mostly for TB-associated or HIV-associated infections. Single-photon emitting agents used for identifying lung infection include (67)Ga-citrate, (111)In-oxine-leukocytes, (99m)Tc-HMPAO-leukocytes, preferably employing SPECT/CT imaging. More recently, the use of [(18)F]FDG for PET imaging (currently PET/CT) has been steadily growing and is now the preferred radionuclide imaging modality not only for identifying sites of lung infection but also for assessing the efficacy of therapy, especially in TB infection and in HIV-associated infections. PET/CT with [(18)F]FDG is also being increasingly used in patients with ventilator-associated pneumonia.