Brown adipose tissue (BAT) is an attractive therapeutic target to combat diabetes and obesity due to its ability to increase glucose expenditure. In a genetic rat model (ZDF fa/fa) of type-2 diabetes and obesity, we aimed to investigate glucose utilization of BAT by 18F-FDG PET imaging. Male Zucker diabetic fatty (ZDF) and Male Zucker lean (ZL) control rats were studied at 13 weeks. Three weeks prior to imaging, ZDF rats were randomized into a no-restriction (ZDF-ND) and a mild calorie restriction (ZDF-CR) group. Dynamic 18F-FDG PET using a dedicated small animal PET system was performed under hyperinsulinemic-euglycemic clamp. 18F-FDG PET identified intense inter-scapular BAT glucose uptake in all ZL control rats, while no focally increased 18F-FDG uptake was detected in all ZDF-ND rats. Mild but significant improved BAT tracer uptake was identified after calorie restriction in diabetic rats (ZDF-CR). The weight of BAT tissue and fat deposits were significantly increased in ZDF-CR and ZDF-ND rats as compared to ZL controls, while UCP-1 and mitochondrial concentrations were significantly decreased. Whitening and severely impaired insulin-stimulated glucose uptake in BAT was confirmed in a rat model of type-2 diabetes. Additionally, calorie restriction partially restored the impaired BAT glucose uptake.

The diagnostic performances of individual SUVmax and texture parameters were relatively low. However, combining these parameters can significantly increase diagnostic performance when differentiating between relatively large low- and high-risk F-FDG-avid TETs. Advances in knowledge: Combined use of SUVmax and texture parameters can significantly increase the diagnostic performance when differentiating between low- and high-risk TETs.

The combined use of SUV and texture parameters has a potential to significantly increase the diagnostic performance to differentiate between large FDG-avid BATs and MATs.

Precise regional quantitative assessment of renal function is limited with conventional Tc-labeled renal radiotracers. A recent study reported that the PET radiotracer 2-deoxy-2-F-fluorosorbitol (F-FDS) has ideal pharmacokinetics for functional renal imaging. Furthermore, F-FDS is available via simple reduction from routinely usedF-FDG. We aimed to further investigate the potential of F-FDS PET as a functional renal imaging agent using rat models of kidney disease. Two different rat models of renal impairment were investigated: induction of acute renal failure by intramuscular administration of glycerol in the hind legs, and induction of unilateral ureteral obstruction by ligation of the left ureter. At 24 h after these procedures, dynamic 30-min F-FDS PET data were acquired using a dedicated small-animal PET system. UrineF-FDS radioactivity 30 min after radiotracer injection was measured together with coinjected Tc-diethylenetriaminepentaacetic acid urine activity. Dynamic PET imaging demonstrated rapid F-FDS accumulation in the renal cortex and rapid radiotracer excretion via the kidneys in healthy control rats. On the other hand, significantly delayed renal radiotracer uptake (continuous slow uptake) was observed in acute renal failure rats and unilateral ureteral obstruction kidneys. Measured urine radiotracer concentrations ofF-FDS and Tc-diethylenetriaminepentaacetic acid correlated well with each other ( = 0.84, < 0.05). F-FDS PET demonstrated favorable kinetics for functional renal imaging in rat models of kidney diseases.F-FDS PET imaging, with its advantages of high spatiotemporal resolution and simple tracer production, could potentially complement or replace conventional renal scintigraphy in select cases and significantly improve the diagnostic performance of renal functional imaging.

PET/CT features of primary tumours for predicting the risk of recurrence in thyroid cancer after total thyroidectomy: potential usefulness of combination of the SUV-related, volumetric, and heterogeneous texture parameters.