Effect of Propranolol on 18F-Fluorodeoxyglucose Uptake in Brown Adipose Tissue in Children and Young Adults with Neoplastic Diseases.

PURPOSE: To evaluate the effectiveness of propranolol at mitigating FDG uptake in brown adipose tissue (BAT) of pediatric patients with known or suspected malignancies. METHODS: PET/CT scans of 3 cohorts of patients treated from 2005 to 2017 were scored for the presence of FDG uptake by BAT at 7 sites: right or left neck/supraclavicular area, right or left axilla, mediastinum, posterior thorax, and abdomen/pelvis. Uptake was scored as follows: 0, none; 1, mild uptake < liver; 2, moderate uptake = liver; and 3, intense uptake > liver. Group 1 consisted of 323 patients (630 scans) who had no specific preparation to mitigate FDG uptake by BAT. Group 2 consisted of 345 patients (705 scans) who underwent only warming in an uptake room with a fixed temperature at 24 °C. Group 3 consisted of 622 patients (1457 scans) who underwent warming. In group 3, patients 8 years and older, 471 patients (1114 scans), were also pre-medicated with oral propranolol 60 min before injection of FDG. Generalized estimation equation, using the logit link method, was used to model the relationship between the incidence of BAT score > 0, in any site, as a function of age, sex, seasonal effect, and body surface area (BSA). RESULTS: In patients aged 8 years or older, the incidence of BAT uptake was 35-44 % and declined to 15 % with propranolol. BAT was most frequent in the neck (26 %), axilla (18 %), posterior thorax (18 %), mediastinum (14 %), and abdomen/pelvis (8 %); BAT was less common in warm months (p = 0.001). No substantial benefit was shown with pre-injection warming alone. No significant effect was found for age, sex, or BSA separately. When BAT uptake was present, it was usually intense. CONCLUSION: Propranolol preparation minimizes FDG uptake by BAT and should be considered routine for pediatric FDG PET/CT cancer-related protocols in children, adolescents, and young adults.

PTEN hamartoma of the soft tissue: the initial manifestation of an underlying PTEN hamartoma tumor syndrome in a 4-year-old female.

A 4-year-old female was referred to pediatric orthopedic surgery for left leg pain and limping for 3 months following a motor vehicle collision. Recently, the patient's mother had noted left knee swelling and dragging of the left leg when walking. Past medical history was significant for hip dysplasia with slight leg length discrepancy. The patient was otherwise healthy. Physical examination was remarkable for left pre-patellar soft tissue fullness with normal range of motion. There was no warmth or tenderness. Subsequent ultrasound revealed a heterogeneous soft tissue mass superior and medial to the patella with a moderate degree of internal vascularity. MR exhibited a heterogeneous soft tissue mass with heterogeneous signal on both T1- and T2-weighted images centered within the vastus medialis obliquus muscle infiltrating the quadriceps tendon. Excisional biopsy was performed with a histopathologic diagnosis of fibroadipose tissue with anomalous vessels, suggestive of phosphatase and tensin homolog (PTEN) hamartoma of the soft tissue (PHOST). The patient was found to be positive for the PTEN gene mutation on genetic testing. The child was also determined to be macrocephalic, a major criterion for PTEN hamartoma tumor syndrome (PHTS). The geneticist advised the patient to undergo yearly physical examinations and early, routine surveillance for several malignancies occurring with PHTS. This case report presents the ultrasound and MRI appearance of a rare benign tumor typically appearing in pediatric patients. The strong association between PHOST and other soft tissue malignancies and the resulting need for life-long surveillance make PHOST an important pathology to recognize.

Quantitative comparison between regularized time-of-flight and OSEM PET reconstructions for small 18F-FDG-avid lesions.

OBJECTIVE: We seek to quantitatively assess the relationship between lesion size and maximum standard uptake value (SUVmax) differences for small fluorine-18-fluorodeoxyglucose-avid lesions through the comparison of regularized time-of-flight (R-ToF) PET and standard ordered subset expectation maximization (OSEM) PET reconstructions. PATIENTS AND METHODS: Data from 30 patients (male to female ratio 8 : 7, 15 different primary malignancies) who underwent noncontrast PET-CT in October 2015 through February 2016 were evaluated. For each patient, multiple reconstructions of the PET data, including R-ToF, time-of-flight (ToF), and non-ToF, were constructed using OSEM of three iterations and 24 subsets. Volumes of interest were contoured for lesions up to 3 cm in size, and SUVmax measurements and lesion size were recorded for a total of 64 lesions. Liver measurements were also recorded for background analysis. A comparative statistical analysis was subsequently carried out. RESULTS: R-ToF showed the highest SUVmax for all 64 lesions and the highest SUVmax mean (P<0.0001) among all lesions, followed by ToF and non-ToF. R-ToF also showed a statistically significant negative correlation (P<0.001) between lesion size and SUVmax versus ToF and non-ToF PET; the smaller the lesion, the greater the disparity. R-ToF also showed the largest mean background signal to noise ratio (P<0.0001), mean lesion signal to noise ratio (P<0.001), and mean lesion signal to background ratio (P<0.0001) versus ToF and non-ToF PET. CONCLUSION: R-ToF shows higher SUVmax values than standard OSEM reconstructions for all fluorine-18-fluorodeoxyglucose -avid lesions, with greater differences for increasingly smaller lesions. R-ToF offers improved suppression of background noise versus OSEM and therefore increased signal to noise and background ratios. These findings offer potential for improved small lesion visibility and characterization.

Increased 18F-FDG Uptake Associated With Gastric Banding Surgical Mesh on PET/CT.

Surgical mesh was used in the 1980s and early 1990s for vertical banded gastroplasty as treatment for morbid obesity. This procedure was replaced by the more popular laparoscopic gastric banding in the mid-1990s. Surgical mesh, commonly used in hernioplasty, has been associated with increased F-FDG uptake related to an inflammatory foreign body reaction and is a known cause of false-positive PET scans. We present a case of increased F-FDG uptake related to surgical mesh in a patient who had undergone vertical banded gastroplasty.