Journal of nuclear medicine : official publication, Society of Nuclear Medicine
-
Cigarette smoke is thought to promote local lung inflammation that leads to lung dysfunction. Lung neutrophilic inflammation is known to result in increased pulmonary uptake of (18)F-FDG. Using a sheep model of localized exposure to cigarette smoke, in this study we tested whether PET-imaged changes in regional intrapulmonary distribution of (18)F-FDG uptake are related to changes in regional lung function as assessed with the infused (13)NN-saline method. ⋯ Substantial interanimal variability and spatial heterogeneity in lung function and (18)F-FDG uptake seem to characterize the response to smoke exposure. The highest levels of local (18)F-FDG uptake were associated with differences in V/Q matching and shunt fraction among animals. The data also suggest that preexisting heterogeneity in V/Q could have been responsible for the large interanimal variability by affecting the heterogeneity and strength of the acute response to smoke inhalation.
-
Dopamine transporter (DAT) imaging with (123)I-FP-CIT ((123)I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl)nortropane) SPECT is frequently used to detect loss of nigrostriatal cells in parkinsonism. Recent (123)I-beta-CIT ((123)I-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane) studies have shown a significant increase in striatal-to-nonspecific beta-CIT binding ratios after treatment with selective serotonin reuptake inhibitors (SSRIs). Due to similarities between (123)I-beta-CIT and (123)I-FP-CIT (both are derived from cocaine and show relatively high affinity for the DAT and the serotonin transporter [SERT]), we hypothesized that quantification of striatal (123)I-FP-CIT binding may be influenced by SSRIs. Moreover, we hypothesized that (123)I-FP-CIT in humans binds not only to DATs but also to central and peripheral SERTs. ⋯ In this study we show that the quantification of striatal (123)I-FP-CIT binding to DAT is significantly increased by the SSRI paroxetine in humans. To our knowledge, this is the first study which shows that (123)I-FP-CIT binds in vivo in humans not only to DATs but also to central SERTs and SERTs in lung tissue.
-
Results from a new PET/CT scanner using lutetium-yttrium oxyorthosilicate (LYSO) crystals for the PET component are presented. This scanner, which operates in a fully 3-dimensional mode, has a diameter of 90 cm and an axial field of view of 18 cm. It uses 4 x 4 x 22 mm(3) LYSO crystals arranged in a pixelated Anger-logic detector design. This scanner was designed to perform as a high-performance conventional PET scanner as well as provide good timing resolution to operate as a time-of-flight (TOF) PET scanner. ⋯ The Gemini TF whole-body scanner represents the first commercially available fully 3-dimensional PET scanner that achieves TOF capability as well as conventional imaging capabilities. The timing resolution is also stable over a long duration, indicating the practicality of this device. Excellent image quality is achieved for whole-body studies in 10-30 min, depending on patient size. The most significant improvement with TOF is seen for the heaviest patients.
-
PET using 18F-FDG has been shown to effectively detect various types of cancer by their increased glucose metabolism. The aim of this study was to evaluate the use of coregistered PET and CT (PET/CT) in patients with suspected thyroid cancer recurrence. ⋯ Coregistered 18F-FDG PET/CT can provide precise anatomic localization of recurrent or metastatic thyroid carcinoma, leading to improved diagnostic accuracy, and can guide therapeutic management. In addition, the findings of this study suggest that further assessment of 131I WBS-negative, thyroglobulin-positive patients by 18F-FDG PET/CT may aid in the clinical management of selected cases regardless of the thyroglobulin level.
-
Imaging with 18F-FDG PET is increasingly accepted as a valuable tool for lymphoma management. A recent shift in the use of PET and PET/CT in medical practice has become evident. We selected aggressive lymphomas as a platform for the discussion of these imaging modalities in oncology patients and the resulting management questions. ⋯ PET/CT improves the accuracy of staging and response assessment over that of CT alone. A negative midtreatment PET result does not indicate the absence of a viable tumor or that therapy can be abbreviated or reduced in intensity. Similarly, a positive PET result does not necessarily indicate a viable tumor or that extending or intensifying treatment will benefit the patient. In assessing response, it is possible that prognosis rests not only on whether the PET result is positive or negative but also on the intensity of the signal. Although the prognostic value of PET for lymphoma is now clear, how to tailor therapy accordingly is a separate matter that requires further investigation.