Flourine-18 fluorodeoxyglucose positron emission tomography imaging exhibits increased SUVmax at the level of the spinal intumescence in normal dogs

Comparison of sedation and general anesthesia protocols for 18F-FDG-PET/CT studies in dogs and cats: Musculoskeletal uptake and radiation dose to workers

In veterinary medicine, PET/CT scans are generally performed with the patient under general anesthesia. The aim of this prospective crossover study was to compare the musculoskeletal uptake of 18F-FDG and radiation doses to workers during PET/CT studies of healthy dogs and cats between sedation and general anesthesia. Volume and maximal standard uptake values (SUVmax) values of abnormal 18F-FDG uptake in the skeletal musculature, presence of misregistration artifact, and radiation doses to workers for each PET/CT study were recorded. Sedation was associated with increased volume of 18F-FDG uptake in the musculature of the thoracic limbs (p = .01), cervical (p = .02), and thoracic (p = .03) spine. Increased volume and SUVmax of the musculature assessed altogether were associated with the lighter degree of sedation (p = .04 for both). A significant decrease in the odds of misregistration artifact was observed for anesthetized animals in comparison with sedated (OR: 0.0, 95% CI: 0.0-0.0, p = .01). Radiation doses to workers were significantly higher for sedation compared with general anesthesia (p = .01) and for the anesthesia technician compared with the nuclear medicine technologist (p = .01). Use of sedation for PET/CT studies in dogs and cats is feasible. However, it is associated with increased physiologic musculoskeletal uptake of 18F-FDG in the thoracic limbs, cervical, and thoracic spine, with increased frequency of misregistration artifact, and with increased radiation doses to workers. These limitations can be overcome by recognition of the uptake pattern and monitoring/rotation of the involved staff at institutions where a high caseload is expected.

Imaging techniques in veterinary medicine. Part II: Computed tomography, magnetic resonance imaging, nuclear medicine

Radiography and ultrasonography are the most used techniques in veterinary clinical practice, due to organizational, managerial and, mostly, economic reasons. However, in the last decades, Computed tomography (CT), Magnetic Resonance Imaging (MRI) and, to a lesser extent, Nuclear Medicine (MN) are increasingly used. As we said in the previous article, all the Diagnostic Imaging techniques are actually "indispensable" in Veterinary Medicine, where many patients do not show any symptoms.This second part describes Computed Tomography (CT), Magnetic Resonance (MRI) and Nuclear Medicine techniques in Veterinary Medicine are described.

Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography for staging of canine insulinoma: 3 cases (2019-2020)

OBJECTIVES

Canine insulinomas are uncommon malignant functional pancreatic neuroendocrine tumours with a high metastatic rate. Diagnostic imaging aids with staging and surgical planning of these tumours; however, identification is unpredictable across modalities. High-grade human pancreatic neuroendocrine tumours display increased avidity on ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT.

MATERIALS AND METHODS

Dogs with clinicopathologic findings consistent with pancreatic insulinoma were prospectively enrolled. Patients underwent ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT and CT angiography, followed by exploratory laparotomy.

RESULTS

Three patients met the inclusion criteria and had histologically confirmed insulinomas. Both metastatic lesions in patient 1 were mildly avid (SUV_max 2.79 and 3.01). In patient 2, the primary pancreatic insulinoma was minimally avid (SUV_max 2.16). The primary pancreatic lesion in patient 3 had similar avidity to normal pancreatic parenchyma (SUV_max 1.54) and was undetected on ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT. Insulinomas demonstrated variable attenuation and contrast enhancement patterns on CT angiography and certain lesions were more conspicuous than on ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT. Two metastatic lesions not visible on either imaging modality were discovered in patient 2 at surgery.

CLINICAL SIGNIFICANCE

Canine insulinomas were inconsistently avid on ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT. This finding is likely attributable to the confounding clinicopathological features and multifaceted transformation of these tumours, in addition to the influence of variable tumour size, composition and vascularity. Unpredictable tumoural avidity limits the value of ¹⁸ F-fluorodeoxyglucose positron emission tomography-CT for staging canine insulinomas.