PET/CT Imaging of Infectious Diseases: Overview of Novel Radiopharmaceuticals.

Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases.

PET Molecular Imaging: Old Habits Do Not Die, They Only Evolve into New Applications.

The first studies on human applications of radioisotopes for the in vivo targeting of pathophysiological processes began in the late 1930s in Western Europe and the USA with 99mTc [...].

Situs Inversus Totalis and Cholangiocarcinoma of the Gallbladder Detected by 18F-FDG PET/CT.

A 72-year-old woman was examined by F-FDG PET/CT, showing pathologic tracer uptake in the gallbladder. PET/CT also depicted condition of situs inversus totalis, with dextrocardia, liver on the left side and spleen on the right side of the body. These findings were essential to plan and develop laparoscopic cholecystectomy, which diagnosed cholangiocarcinoma. The recognition of anatomical variants and abnormalities by means of hybrid PET/CT imaging is essential in order to plan the best therapeutic approach.

Ictal 18F-FDG PET/MRI in a Patient With Cortical Heterotopia and Focal Epilepsy.

A 19-year-old man with epilepsy underwent ictal F-FDG PET/MRI, showing a 5 mm heterotopic nodule in the periventricular white matter, adjacent to the frontal horn of the left lateral ventricle (SUVmax, 5.5; glucidic cerebral metabolic rate, 0.317 µmol/mL). A repeated F-FDG PET/MRI, during seizure freedom, showed, at visual analysis, subtle decrease of the nodule metabolism. SUVmax and glucidic cerebral metabolic rate were clearly reduced to 3.7 and 0.226, respectively. Ictal F-FDG PET/MRI could be useful in epilepsy because of the added value of SUVmax and cerebral metabolic rate of glucose analysis to understand the relationship between heterotopy and epilepsy.

18F-DOPA PET/CT Physiological Distribution and Pitfalls: Experience in 215 Patients.

PURPOSE: F-DOPA PET/CT is potentially helpful in the management of patients with low-grade brain tumors, movement disorders, and somatic neuroendocrine tumors. We describe the whole-body physiological distribution of F-DOPA uptake. PATIENTS AND METHODS: We examined 215 patients with F-DOPA PET/CT. Among these, 161 had brain scans and 54 had whole-body scans. RESULTS: Physiological distribution was negligible in the brain, with the exception of basal ganglia, whereas greatest activity was noted in the liver, pancreas, other exocrine glands, and the urinary system. Incidental tracer uptake sites were identified in 5.5% of patients. Some of these findings were due to inflammation, whereas in most cases, uptake was seen in benign tumors of the brain or in the endocrine or exocrine glands. CONCLUSIONS: F-DOPA uptake may be seen in inflammatory tissue or benign tumors. Correlations with history, physical examination, laboratory examination, CT, MRI, and histology are necessary for optimal diagnosis.

18F-DOPA PET/CT and MRI Findings in a Patient With Multiple Meningiomas.

A 56-year-old man was referred to our Department for a 2-year story of upper limb tremor, severe headache, and episodes of confusion. Brain F-DOPA PET/CT showed multiple areas of tracer uptake in the two hemispheres of the brain. Subsequent MRI displayed demyelinating foci with high contrast enhancement. Histological specimen confirmed the diagnosis of multiple meningiomas.

A case of colon cancer incidentally detected by 18F-choline PET/CT.

A 65-year-old man had restaging of prostate cancer with an 18F-choline PET/CT, which revealed focal uptake in a thickened posterior wall of sigmoid colon. Biopsy demonstrated colon cancer. Incidental colorectal 18F-choline uptake should be further investigated with histological analysis.