Wuying Cheng

Brown Adipose Tissue Can Be Activated or Inhibited within an Hour before 18F-FDG Injection: A Preliminary Study with MicroPET

Brown adipose tissue (BAT) is emerging as a potential target for treating human obesity. It has been indicated that BAT is rich in innervations of sympathetic nerve control. Using 18F-FDG microPET imaging, this study aims at evaluating how factors related to sympathetic activation/inhibition changed BAT metabolism of mice. BAT 18F-FDG uptake were semiquantitatively evaluated in different groups of mice under temperature (cold or warm stimulus) or pharmacological interventions (norepinephrine, epinephrine, isoprenaline, or propranolol) and were compared with the corresponding controls. It was found that BAT activation can be stimulated by cold exposure (P = 1.96 × 10−4), norepinephrine (P = .002), or both (P = 2.19 × 10−6) within an hour before 18F-FDG injection and can also be alleviated by warming up (P = .001) or propranolol lavage (P = .027). This preliminary study indicated that BAT function could be evaluated by 18F-FDG PET imaging through short-term interventions, which paved the way for further investigation of the relationship between human obesity and BAT dysfunction.

Intense FDG activity in the brown adipose tissue in omental and mesenteric regions in a patient with malignant pheochromocytoma.

A 39-year-old man who had a history of surgical excision of left adrenal pheochromocytoma 3 years ago underwent an FDG PET/CT scan to evaluate possible metastatic/recurrent disease. In addition to multiple FDG-avid lesions typical of hypermetabolic malignant disease and the FDG uptake in regions rich in brown adipose tissue, there was also intense FDG activity in the omental and mesenteric regions, which are not common locations of elevated FDG activity. On the repeat FDG PET/CT scan 3 days later after the patient was prepared with propranolol, the omental and mesenteric FDG activity was diminished.

Endometrial and ovarian F-18 FDG uptake in serial PET studies and the value of delayed imaging for differentiation.

Purpose: This study was designed to characterize the physiological endometrial and ovarian F-18 FDG uptake through analysis of clinical patients with serial PET follow ups (group 1) or who underwent delayed imaging (group 2). Methods: Group 1 had 24 patients (14 premenopausal and 10 postmenopausal). Each patient underwent 2 to 4 serial FDG PET studies and summed to 57 studies. Group 2 included 15 premenopausal patients with delayed imaging 3 hours after injection. Ten of them showed endometrial uptake, and 8 showed intense uptake in 10 ovaries. Visual and semiquantitative methods were applied for analysis. Results: By analysis of serial PET studies, endometrial and ovarian uptake showed some specific characteristics. Surrounded by a relatively low-uptake uterine wall, the inverted cone-shaped endometrium showed 2 peaks of uptake, one in early menstruation and the other in midcycle. The ovarian uptake was more prominent in the midcycle, and the foci of uptake had an ovoid shape and located at the left and/or right side superior–posterior to the bladder. For the postmenopausal and amenorrhea women (35 studies), only one study in a woman within 1 year of menopause showed mild endometrial and ovarian uptake. Compared with the imaging 1 hour after injection, the standardized uptake value increased in 2 of 10 endometria and 4 of 10 ovaries in the delayed imaging. Conclusion: Physiological endometrial and ovarian uptake can be identified on PET alone by their specific shape and position as well as their relation to the menstrual state, whereas delayed imaging was of little value for differentiation in this preliminary study.

Hepatic paragonimiasis revealed by FDG PET/CT.

A 72-year-old asymptomatic man with a hepatic lesion incidentally detected by ultrasonography in routine examination undertook fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography for further evaluation. The images revealed increased FDG activity in the lesion, which was suggestive of malignancy. However, the pathologic examination demonstrated that the lesion was a granuloma caused by Paragonimus westermani, a lung fluke. Although increased FDG activity in the lung due to P. westermani infection is expected and reported previously, such lesion identified in the liver by FDG positron emission tomography/computed tomography is unusual.

Improving Evaluation of Primary Gastric Malignancies by Distending the Stomach with Milk Immediately Before 18F-FDG PET Scanning

This study was designed to investigate the feasibility and effectiveness of a modified protocol for 18F-FDG PET that was proposed to improve the identification of primary gastric malignancies. Methods: In the modified protocol, patients were asked to drink 300–500 mL of cow milk to distend the stomach immediately before PET scans instead of fasting all along. For investigation of the influence of ingested milk on 18F-FDG distributions, 43 nondiabetic patients without documented gastric diseases underwent both empty- and distended-stomach PET scans (79 and 72 scans, respectively) in their serial follow-up studies. For the evaluation of proven gastric malignancies, 24 patients who underwent distended-stomach PET scans were compared with 17 patients who underwent conventional empty-stomach examinations. Results: Ingestion of milk nearly 1 h after 18F-FDG injection had no significant influence on distributions to the heart (P = 0.16), mediastinum (P = 0.50), and liver (P = 0.49), whereas the percentages of intense and moderate uptake in the stomach changed from 38.0% and 59.5% to 0% and 11.1%, respectively. With the normal gastric wall distended, malignant lesions were observed with higher contrast and clearer outlines, and some of them were detected at a small size (1.2 cm) at an early stage and with mild uptake. Conclusion: Gastric distention with milk just before 18F-FDG PET is a simple and effective method for improving the evaluation of primary gastric malignancies.

Activating brown adipose tissue for weight loss and lowering of blood glucose levels: a microPET study using obese and diabetic model mice.

Purpose This study aims at using 18F-FDG microPET to monitor the brown adipose tissue (BAT) glucose metabolism in obese and diabetic mouse models under different interventions, and study the therapeutic potential of BAT activation for weight loss and lowering of blood glucose in these models. Methods Obese mice were established by a high-fat diet for eight weeks, and diabetes mellitus(DM) models were induced with Streptozocin in obese mice. 18F-FDG microPET was used to monitor BAT function during obese and DM modeling, and also after BRL37344 (a β3-adrenergic receptor agonist) or levothyroxine treatment. The BAT function was correlated with the body weight and blood glucose levels. Results Compared with the controls, the obese mice and DM mice showed successively lower 18F-FDG uptake in the interscapular BAT (P = 0.036 and <0.001, respectively). After two-week BRL37344 treatment, the BAT uptake was significantly elevated in both obese mice (P = 0.010) and DM mice (P = 0.004), accompanied with significantly decreased blood glucose levels (P = 0.023 and 0.036, respectively). The BAT uptake was negatively correlated with the blood glucose levels in both obese mice (r = −0.71, P = 0.003) and DM mice (r = −0.74, P = 0.010). BRL37344 treatment also caused significant weight loss in the obese mice (P = 0.001). Levothyroxine treatment increased the BAT uptake in the control mice (P = 0.025) and obese mice (P = 0.013), but not in the DM mice (P = 0.45). Conclusion The inhibited BAT function in obese and DM mice can be re-activated by β3-adrenergic receptor agonist or thyroid hormone, and effective BAT activation may lead to weight loss and blood glucose lowering. Activating BAT can provide a new treatment strategy for obesity and DM.

FDG PET/CT detection of intussusception caused by aggressive fibromatosis.

A 55-year-old woman with worsening abdominal pain for 2 months underwent FDG PET/CT to evaluate possible malignancy. A focus of intense FDG uptake was observed in the region of the cecum and ascending colon on PET images, suspicious for malignancy. The corresponding CT images showed an ovoid-shape mass causing ileocolic intussusception. The intussusception was resolved by surgically dissecting the mass. The pathologic diagnosis was aggressive fibromatosis.

IV Leiomyomatosis on FDG PET/CT.

A 48-year-old woman presented with a 2-month history of right lower extremity edema. Clinical examination only showed right lower limb swelling. Routine laboratory examination revealed no abnormal results. Abdominal ultrasonography identified uterine leiomyoma and soft tissue masses. An abdominal CT demonstrated a continuous mass extending from the right internal and external iliac vein into the common iliac vein and inferior vena cava. To distinguish the mass from malignancy, the patient underwent PET/CT scan which showed increased FDG activity in the mass. However, histopathological examination proved the mass to be IV leiomyomatosis.