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    Assessing the Effect of Various Blood Glucose Levels on 18F-FDG Activity in the Brain, Liver, and Blood Pool
    (Soc Nuclear Medicine Inc, 2019) Sarikaya, Ismet; Sarikaya, Ali; Sharma, Prem
    Studies have extensively analyzed the effect of hyperglycemia on F-18-FDG uptake in normal tissues and tumors. In this study, we measured SUV in the brain, liver, and blood pool in normoglycemia, hyperglycemia, and hypoglycemia to understand the effect of blood glucose on F-18-FDG uptake and to develop a formula to correct SUV. Methods: Whole-body F-18-FDG PET/CT images of adults were selected for analysis. Brain SUVmax, blood-pool SUVmean, and liver SUVmean were measured at blood glucose ranges of 61-70, 71-80, 81-90, 91-100, 101-110, 111-120, 121-130, 131-140, 141-150, 151-160, 161-170, 171-180, 181-190, 191-200, and 201 mg/dL and above. At each blood glucose range, 10 PET images were analyzed (total, 150). The mean (+/- SD) SUV of the brain, liver, and blood pool at each blood glucose range was calculated, and blood glucose and SUV curves were generated. Because brain and tumors show a high expression of glucose transporters 1 and 3, we generated an SUV correction formula based on percentage reduction in brain SUVmax with increasing blood glucose level. Results: Mean brain SUVmax gradually decreased with increasing blood glucose level, starting after a level of 110 mg/dL. The approximate percentage reduction in brain SUV max was 20%, 35%, 50%, 60%, and 65% at blood glucose ranges of 111-120, 121-140, 141-160, 161-200, and 201 mg/dL and above, respectively. In the formula we generated, measured SUV max is multiplied by a reduction factor of 1.25, 1.5, 2, 2.5, and 2.8 for the blood glucose ranges of 111-120, 121-140, 141-160, 161-200, and 201 mg/dL and above, respectively, to correct SUV. Brain SUV max did not differ between hypoglycemic and normoglycemic patients (P > 0.05). SUVmean in the blood pool and liver was lower in hypoglycemic patients (P < 0.05) and did not differ between hyperglycemic (P > 0.05) and normoglycemic patients. Conclusion: Hyperglycemia gradually reduces brain F-18-FDG uptake, starting after a blood glucose level of 110 mg/dL. Hyperglycemia does not affect F-18-FDG activity in the liver or blood pool. Hypoglycemia does not seem to affect brain F-18-FDG uptake but appears to reduce liver and blood-pool activity. The simple formula we generated can be used to correct SUV in hyperglycemic adults in selected cases.
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    F-18 fluoride uptake in primary breast cancer
    (Springer, 2018) Sarikaya, Ismet; Sharma, Prem; Sarikaya, Ali
    ObjectiveBone-specific radiotracers are known to accumulate in breast lesions. Tc-99m diphosphonates have been widely studied in differentiating breast lesions. In this retrospective study, we aimed to assess the uptake of the bone-specific PET radiotracer, F-18 fluoride (NaF), in primary breast cancers to determine its sensitivity and to identify any differences in NaF uptake between calcified and non-calcified tumors, histological subtypes, and patients with or without axillary lymphadenopathy.MethodsNaF positron emission tomography/computed tomography (PET/CT) images of 69 newly diagnosed breast cancer patients were reviewed. F-18 fluoride uptake as maximum standardized uptake value (NaF SUVmax) was measured in the primary tumor, enlarged axillary lymph nodes and contralateral normal/non-tumoral breast tissue. Low-dose CT images were reviewed to locate the primary tumor and grossly assess its calcification and check for ipsilateral axillary lymphadenopathy. Whole body NaF PET/CT images were reviewed to search for bone metastases. Eighteen patients also underwent F-18 fluorodeoxyglucose (FDG) PET/CT study.ResultsThe primary breast tumor was clearly seen as focal or diffuse uptake on NaF PET images in 27 of 69 patients (39%) (mean NaF SUVmax: 2.01.0). In the rest, there was only mild bilateral diffuse breast uptake. When analyzing images per histological subtype (42 patients, 43 tumors), 14 of 31 invasive ductal carcinomas (IDC) (45%) and 3 of 4 ductal carcinoma in situ (DCIS) were visible on PET. Five invasive lobular carcinomas, 2 invasive mammary carcinomas, and 1 mucinous carcinoma were not visible on PET. Mean NaF SUVmax of contralateral normal/non-tumoral breast tissue was 1.0 +/- 0.4. There was no significant difference in mean NaF SUVmax of primary tumor in cases with and without calcification or with and without axillary lymphadenopathy (p 0.892 and 0.957). There was no correlation between NaF SUVmax and FDG SUVmax values of the primary tumors (r 0.072, p 0.797, Pearson correlation).ConclusionNaF PET has relatively low sensitivity in detecting breast cancer. However, abnormal breast uptake on NaF PET requires further evaluation. F-18 fluoride uptake in the primary breast tumor does not seem to be correlated with axillary lymphadenopathy (metastasis potential), gross tumor calcification or metabolic activity of the tumor.