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The purpose of this study was to evaluate the predictive features of baseline F-18-fluorodeoxy-D-glucose positron emission tomography (18F-FDG PET)/computed tomography (CT) parameters in patients with dedifferentiated liposarcomas (DDLPSs) and well-differentiated liposarcomas (WDLPSs) receiving systemic treatment. A total of 24 patients with liposarcoma who underwent longitudinal 18F-FDG PET/CT in systemic therapy were included. All volumetric segmentation of each tumor section and semiquantitative imaging parameters were extracted from the axial field of view from both PET and CT images. Maximum, mean, and minimum standardized uptake values (SUVmax, SUVmean, and SUVmin), Hounsfield units (HUs), and their respective changes from baseline and posttreatment were calculated. The voxel values from unenhanced CT images were correlated with PET-derived parameters. The 18F-FDG uptake decreased by more than 56% on average in responders for both SUVmax and SUVmean in DDLPS. There was a decrease in HUmax in DDLPS among responders. Using AUC > 0.8 as a reasonable predictor, we found that the ratios of SUVmaxD/HUmean, SUVmaxD/HUmedian, and SUVmeanD/HUmedian at baseline were significant indicators of the response to treatment in patients with liposarcoma. The changes in SUVmean and not just SUVmax parameters could be considered as accurate tumor response indicators. For the first time, we introduced baseline SUV/HU ratios as a valuable diagnostic tool in predicting liposarcoma treatment outcomes. This ability was not revealed by classic semiquantitative PET or CT parameters at baseline. [ABSTRACT FROM AUTHOR]

Objective: We aimed to evaluate whether the degree of F-18 fluorodeoxyglucose (FDG) uptake in the lungs is associated with an increased risk of lung cancer and to develop lung cancer risk prediction models using metabolic parameters on F-18 FDG positron emission tomography (PET). Methods: We retrospectively included 795 healthy individuals who underwent F-18 FDG PET/CT scans for a health check-up. Individuals who developed lung cancer within 5 years of the PET/CT scan were classified into the lung cancer group (n = 136); those who did not were classified into the control group (n = 659). The healthy individuals were then randomly assigned to either the training (n = 585) or validation sets (n = 210). Clinical factors including age, sex, body mass index (BMI), and smoking history were collected. The standardized uptake value ratio (SUVR) and metabolic heterogeneity (MH) index were obtained for the bilateral lungs. Logistic regression models including clinical factors, SUVR, and MH index were generated to quantify the probability of lung cancer development using a training set. The prediction models were validated using a validation set. Results: The lung SUVR and lung MH index in the lung cancer group were significantly higher than in the control group (p < 0.001 and p < 0.001, respectively). In the combined prediction model 1, age, sex, BMI, smoking history, and lung SUVR were significantly associated with lung cancer development (age: OR 1.07, p < 0.001; male: OR 2.08, p = 0.015; BMI: OR 0.93, p = 0.057; current or past smoker: OR 5.60, p < 0.001; lung SUVR: OR 1.13, p < 0.001). In the combined prediction model 2, age, sex, BMI, smoking history, and lung MH index showed a significant association with lung cancer development (age: OR 1.06, p < 0.001; male: OR 1.87, p = 0.045; BMI: OR 0.93, p = 0.010; current or past smoker: OR 4.78, p < 0.001; lung MH index: OR 1.33, p < 0.001). In the validation data, combined prediction models 1 and 2 exhibited very good discrimination [area under the receiver operator curve (AUC): 0.867 and 0.901, respectively]. Conclusions: The metabolic parameters on F-18 FDG PET are related to an increased risk of lung cancer. Metabolic parameters can be used as biomarkers to provide information independent of the clinical parameters, related to lung cancer risk. [ABSTRACT FROM AUTHOR]

Objective:The role of baseline and post-treatment standardized uptake value (SUVmax) values in predicting pathological response in patients with breast cancer after neoadjuvant chemotherapy (NAC).Materials and Methods:Thirty patients with invasive ductal breast cancer were included in this retrospective study. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) examinations were performed before and after NAC. Pretreatment SUVmax (SUVmax I), post-treatment SUVmax (SUVmax II) and ΔSUVmax values of primary breast cancer were obtained. Breast tumor pathology preparations were examined for the evaluation of tumor response according to the Miller and Payne classification. Patients were grouped as responding to treatment (pCR) and unresponsive to treatment (nonpCR). In all analyses, p

Objective: The role of baseline and post-treatment standardized uptake value (SUVmax) values in predicting pathological response in patients with breast cancer after neoadjuvant chemotherapy (NAC). Materials and Methods: Thirty patients with invasive ductal breast cancer were included in this retrospective study. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) examinations were performed before and after NAC. Pretreatment SUVmax (SUVmax I), post-treatment SUVmax (SUVmax II) and ΔSUVmax values of primary breast cancer were obtained. Breast tumor pathology preparations were examined for the evaluation of tumor response according to the Miller and Payne classification. Patients were grouped as responding to treatment (pCR) and unresponsive to treatment (nonpCR). In all analyses, p<0.05 was considered statistically significant. Results: The mean age of the 30 patients included in the study was 51.2±11.98 years. In the study-defined grouping, 13 patients (43.3%) were nonresponders and 17 patients (56.7%) were responders. ΔSUVmax was significantly greater in the responders group compared to the nonresponders group, while SUVmax II was lower (p = 0.001 and p = 0.004, respectively). There was no significant difference between the responders and nonresponders in terms of age, tumor diameter, and SUVmax I values. Multivariate logistic regression analysis showed ΔSUVmax to be the only independent predictive factor for pCR. Conclusion: F-18 FDG PET/CT was an effective method in evaluating the treatment response after NAC in breast cancer, and ΔSUVmax and posttreatment SUVmax can be used to predict the response of the primary tumor to treatment. [ABSTRACT FROM AUTHOR]

Malignancy may lead to sarcoidosis, which is referred to as sarcoid reaction. This reaction is believed to be a host immune response to the release of soluble antigens from cancer cells. Studies have shown strong 2′-deoxy-2′-[F-18]fluoro-D-glucose (F-18 FDG) uptake in sarcoid reaction and in true sarcoidosis. Therefore, in patients with malignancy, sarcoid reactions can mimic metastasis or recurrence on F-18 FDG positron emission tomography/computed tomography (PET/CT). Herein, we report the case of a 58-year-old woman with a history of left breast cancer whose FDG PET/CT evaluated at 3 months after adjuvant chemotherapy presented hypermetabolic lymphadenopathy in the right supraclavicular and right mediastinal areas. We interpreted these as metastases because the involved lymph nodes were intensely hypermetabolic and appeared newly. Pathologic evaluation of the excised lymph node revealed noncaseating chronic granulomas without malignant cells, indicating a sarcoid reaction. After appropriate steroid therapy, both the size and metabolic activity of the lymphadenopathy substantially decreased. Most sarcoid reactions present as bilateral hilar and peribronchial lymphadenopathies. Our patient presents an atypical example that a sarcoid reaction can also present in a unilateral pattern, making its diagnosis challenging. When interpreting FDG PET/CT images, considering that the sarcoid reaction pattern can vary is crucial.

Purpose: The comparison of angiogenesis imaging (Ga-68-DOTA-Arginine-Glycine-Aspartic Acid [RGD]) positron emission tomography/computed tomography [PET/CT]) with metabolic imaging (F-18 fluorodeoxyglucose [FDG] PET/CT) in primary staging and response assessment to neoadjuvant chemotherapy (NACT) in locally advanced breast cancer (LABC) patients. Methods: In this prospective study, 85 female patients with LABC were subjected to two PET/CT studies (Ga-68-DOTA-RGD2 and F-18 FDG) within 1 week of each other. Thirty patients had repeat studies 4 weeks after completing eight cycles of NACT. Response assessment was done by RECIST 1.1 criteria. Results: Ga-68-DOTA-RGD2 and F-18 FDG uptake in the primary tumor were seen in all patients. Ipsilateral axillary and internal mammary lymph nodes were detected in 77 (90.5%) versus 80 (94.1%) and 22 (25.8%) versus 27 (31.7%) patients on Ga-68-DOTA-RGD2 and F-18 FDG scans, respectively. Ipsilateral supra-clavicular lymph nodes and skeletal lesions were noted in 17 (20%) versus 21 (24.7%) patients and 23 (27.0%) versus 24 (28.2%) patients on Ga-68-DOTA-RGD2 versus F-18 FDG studies, respectively. However, the Ga-68-DOTA-RGD2 did not show uptake in F-18 FDG avid liver lesions (LLs) in 10 patients, adrenal lesion in one patient, mediastinal lymph nodes in 2 patients, lung nodules, and pleural soft-tissue deposits, each in one patient. In response assessment, 23 and 25 patients had concordance with RECIST1.1 criteria on F-18 FDG and Ga-68-DOTA-RGD2 scans, respectively. However, there were discordant results in four patients on Ga-68-DOTA-RGD2 scan and two patients on F-18 FDG scans. Conclusion: Metabolic imaging is better in primary staging and chemotherapy response assessment than angiogenesis imaging in LABC patients. The latter may miss the metastatic soft-tissue deposits, adrenal, and LLs. [ABSTRACT FROM AUTHOR]

The aim of the current meta-analysis was to evaluate diagnostic accuracies of preoperative F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) for prediction of microvascular invasion (MVI) in hepatocellular carcinoma (HCC) patients. The scientific database such as PubMed, Cochrane, and Embase database were searched for studies evaluating diagnostic accuracies of preoperative F-18 FDG PET or PET/CT for prediction of MVI in HCC patients up to November 30, 2020. Fourteen eligible studies (1276 patients) were enrolled. The pooled sensitivity for F-18 FDG PET or PET/CT was 0.67 (95% CI; 0.57–0.76) with heterogeneity and a pooled specificity of 0.80 (95% CI; 0.74–0.85) with heterogeneity. Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 3.3 (95% CI; 2.5–4.5) and negative likelihood ratio (LR−) of 0.41 (95% CI; 0.31–0.55). The pooled diagnostic odds ratio (DOR) was 8 (95% CI; 5–14). Summary receiver operating characteristic (ROC) curve indicates that the area under the curve was 0.81 (95% CI; 0.78–0.84). The current meta-analysis showed a low sensitivity and moderate specificity of F-18 FDG PET or PET/CT for the prediction of MVI in HCC patients. F-18 FDG PET or PET/CT might not be useful for the preoperative prediction of MVI in HCC patients and should not be used to exclude MVI. Therefore, cautious application and interpretation should be paid to the F-18 FDG PET or PET/CT for the prediction of MVI in HCC patients preoperatively. • Predictive value of F-18 FDG PET/CT for MVI in HCC was assessed. • F-18 FDG PET/CT showed moderate diagnostic value for MVI in HCC patients. • F-18 FDG PET/CT might not be useful for prediction of MVI in HCC patients. [ABSTRACT FROM AUTHOR]

Objective: The purpose of the current study was to compare the diagnostic accuracies of F-18 FDG PET/CT and MRI for prediction of pathologic responses to neoadjuvant treatment (NAT) in locally advanced rectal cancer (LARC) patients based on a systematic review and meta-analyses. Methods: The PubMed, Cochrane, and Embase databases were searched to identify studies that conducted direct comparisons of the diagnostic performance of F-18 FDG PET/CT and MRI for the prediction of pathologic response to NAT in patients with LARC from the earliest available date of indexing up to July 31, 2020. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR + and LR −), and we constructed summary receiver operating characteristic curves. Results: In nine studies (427 patients), the pooled sensitivity of F-18 FDG PET/CT was 0.79 (95% CI 0.71–0.86) and the pooled specificity was 0.74 (95% CI 0.60–0.84). LR syntheses yielded an overall LR + of 3.1 (95% CI 1.9–5.0) and an LR − of 0.28 (95% CI 0.18–0.43). The pooled diagnostic odds ratio (DOR) was 11 (95% CI 5–26). The pooled sensitivity of MRI was 0.89 (95% CI 0.77–0.95) and the pooled specificity was 0.66 (95% CI 0.55–0.76). LR syntheses yielded an overall LR + of 2.6 (95% CI 1.9–3.6) and an LR − of 0.17 (95% CI 0.08–0.37). The pooled DOR was 15 (95% CI 6–42). In meta-regression analysis, no variable was identified as the source of the study heterogeneity. Conclusion: F-18 FDG PET/CT and MRI showed similar diagnostic performances for the prediction of pathologic responses to NAT in patients with LARC. However, each modality can be a complement to other rather than being used singly. [ABSTRACT FROM AUTHOR]

Introduction:Elastofibroma dorsi (ED) is a rare, benign and slowly growing connective tissue tumor that is frequently observed in the subscapular region in elderly people. It can be detected with various imaging modalities, such as computed tomography (CT), magnetic resonance imaging, ultrasonography and positron emission tomography (PET). In this retrospective study, the clinical features of EDs detected in PET/CT examinations performed for malignant or nonmalignant causes were evaluated.Methods:In this retrospective study, PET/CT examinations performed between May 2014 and December 2017 in a single institution for oncological and non-oncological diseases were evaluated retrospectively. Anatomical dimensions of the lesions were evaluated on axial CT sections. The metabolic activities or receptor expression status of the lesions were evaluated according to the SUVmax values obtained from the region of interests drawn on the lesions detected in PET scans.Results:A total of 7300 PET/CT reports were searched for term “ED” and the images of patients with ED were re-evaluated. ED was detected in 174 scans of 131 patients (97 female and 34 male; mean age: 62.13±8.6 years). The prevalence of ED was 1.79%. Bilateral ED was detected in 116 patients (88.5%) and 15 patients (11.5%) had unilateral ED. The mean diameter was 2.6x4.9±1.1x1.9 cm, and mean SUVmax value was 2.46±0.74. There were statistically significant differences regarding SUVmax values and measured dimensions (p=0.001).Conclusion:In this study, the prevalence and demographic patterns of ED were demonstrated with F-18 fluorodeoxyglucose and Ga-68 DOTATATE PET-CT. Knowledge of the distribution and uptake patterns of PET agents and their physiological uptake sites will prevent unnecessary procedures and interventions.

Introduction:F-18 radioisotope has higher photon energy when compared with other radioisotopes that are preferred in conventional imaging procedures in nuclear medicine. The aim of this study was to measure external radiation dose rate from patients injected with F-18 fluorodeoxyglucose (FDG) and to determine appropriate discharge time after F-18 FDG positron emission tomography/computed tomography (PET/CT) procedure.Methods:Our study included 29 (M/F=9/20) patients who were referred to nuclear medicine department for F-18 FDG PET/CT imaging. Dose rates were measured at a distance of 0, 0.5, 1, 1.5 and 2 m from patients via Geiger-Müller probe at 3 different time points: 1) Just after the intravenous injection of F-18 FDG, 2) before PET/CT imaging and 3) just before discharge of patients from PET/CT department. Statistical analysis was performed to evaluate the differences between measurements.Results:Patients were injected 291±62 megabecquerel (MBq) (range: 226-440 MBq) F-18 FDG via IV route. The patients stayed in nuclear medicine department for 70.3±13.8 min (range: 53 min-100 min) after injection of F-18 FDG. Radiation dose velocity measurements taken at a distance of 1 meter were 39.7±11.9 μSv/h just after the injection, 21.1±4.5 μSv/h before PET/CT examination and 14.3±2.9 μSv/h just before discharge.Conclusion:Although F-18 has high photon energy, its halflife is relatively short and this makes F-18 FDG an ideal radiopharmaceutical for PET/CT imaging. When the PET/CT scan is terminated, the dose rate measurements of the patients at a distance of 1 m are appropriate for discharge according to Turkish Atomic Energy Authority regulations. Therefore, patients can be safely discharged by explaining the necessary radiation safety measures after completing F-18 FDG PET/CT imaging.

Abstract Background The low sensitivity of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the evaluation of metastatic lymph nodes (LNs) is mainly due to the partial volume effect in patients with rectal cancer. This retrospective study evaluated the diagnostic accuracy of F-18 FDG PET/CT with optimal cut-off values of the maximum standardized uptake value (SUVmax), according to LN size, for the evaluation of regional LN in rectal cancer patients. Methods This study included 176 patients with rectal cancer who underwent F-18 FDG PET/CT for initial staging. Patients were classified based on the long-axis diameter of the regional LN on CT images as small (≤ 7 mm; n = 118) and large (> 7 mm; n = 58) LN groups. The optimal cut-off value of SUVmax was determined for each group, using receiver operating characteristic curve analysis. Areas under the curve (AUC) were compared by C-statistics using two methods: the cut-off value of SUVmax optimized according to LN size, and a fixed SUVmax cut-off value of 2.5. Results The optimal cut-off values of SUVmax for the small and large LN groups were 1.1, and 2.1, respectively. The sensitivity, specificity, and accuracy of F-18 FDG PET/CT using the optimal cut-off values were 90.6, 70.9, and 76.3% in the small LN group, and 68.6, 78.3, and 72.4% in the large LN group. The sensitivity, specificity, and accuracy of F-18 FDG PET/CT using the fixed cut-off value were 18.8, 100, and 78.0% in the small LN group, and 51.4, 87.0, and 65.5% in the large LN group. The AUC was significantly higher using the optimal cut-off values than the fixed cut-off value (0.808 vs. 0.594, p = 0.005) in the small LN group, but not in the large LN group (0.734 vs. 0.692, p = 0.429). Conclusions Application of the lower cut-off value of SUVmax improves the diagnostic performance of F-18 FDG PET/CT for the evaluation of small regional LNs in patients with rectal cancer.

F-18 FDG is the most widely used tracer in molecular imaging and it isapplied for many purposes mainly in malignant diseases. Incidental findingare common in FDG-PET/CT imaging and includes benign and malignantlesions. Among the rare tumors , adrenal oncocytomas are uncommonfindings and incidental findings of thyroid malignancies are not rare.Oncocytoma is a rare adrenocortical tumor and majority of bulky adrenaltumors are benign with uncertain incident of malignancy. In this study,we are reporting a 37-year-old man with two incidental malignanciesdetected by FDG-PET-CT. He has no symptoms has no blood and hormonalabnormalities.The scan demonstrated intense heterogeneous FDG uptake within thebulky oval shaped lesion in the left adrenal gland. Accordingly, openadrenalectomy was performed and diagnosis of adrenocortical carcinomaoncocytic type was established. Furthermore, a focal FDG uptake wasidentified in the right thyroid lobe and histopathology findings wereconsistent with well-differentiated papillary thyroid cancer. FDG playsa great role in identifying primary rare lesions and also detection ofincidental findings at unexpected sites.

Objective: The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for diagnosis of cardiac sarcoidosis (CS) through a systematic review and meta-analysis. Methods: The PubMed and EMBASE database, from the earliest available date of indexing through 31 March 31, 2018, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for CS. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR−), and constructed summary receiver operating characteristic (SROC) curves. Results: Across 17 studies (891 patients), the pooled sensitivity was 0.84 [95% confidence interval (95% CI) 0.71-0.91] with heterogeneity (I2 = 77.5) and a pooled specificity of 0.83 (95% CI 0.74-0.89) with heterogeneity (I2 = 80.0). Likelihood ratio (LR) syntheses gave an overall LR+ of 4.9 (95% CI 3.3-7.3) and LR− of 0.2 (95% CI 0.11-0.35). The pooled diagnostic odds ratio was 27 (95% CI 14-55). Hierarchical SROC curve indicates that the area under the curve was 0.90 (95% CI 0.87-0.92). Meta-regression showed that combined myocardial perfusion imaging was the source of heterogeneity. Conclusion: The current meta-analysis showed the moderate sensitivity and specificity of F-18 FDG PET or PET/CT for diagnosis of CS. The presence of combined myocardial perfusion imaging could improve diagnostic accuracy of F-18 FDG PET or PET/CT for diagnosis of CS. At present, the literature regarding the use of F-18 FDG PET for detection of CS remains limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of F-18 FDG PET for diagnosis of CS. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the differentiation of benign and malignant vertebral compression fractures (VCFxs) through a systematic review and meta-analysis. MEDLINE via PubMed, Cochrane, Scopus, and Embase database, from the earliest available date of indexing through September 30, 2019, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for the differentiation of malignant VCFxs. We determined the sensitivities and specificities across the studies, calculated the positive and negative likelihood ratios (LR+ and LR−, respectively), and constructed summary receiver operating characteristic curves. For the 5 studies (274 patients), the pooled sensitivity was 0.96 (95% confidence interval [CI], 0.82–0.99) without heterogeneity (I 2, 50.6) and 0.77 (95% CI, 0.56–0.89) with heterogeneity (I 2, 76.1). LR syntheses gave an overall LR+ of 4.1 (95% CI, 2.1–8.0) and LR− of 0.05 (95% CI, 0.01–0.23). The pooled diagnostic odds ratio (DOR) was 78 (95% CI, 19–316). The hierarchical summary receiver operating characteristic curve indicates that the areas under the curve was 0.94 (95% CI, 0.92–0.96). The results of the present meta-analysis have shown high sensitivity and moderate specificity for F-18 FDG PET and PET/CT for differentiation of malignant VCFxs. At present, the reported data regarding the use of F-18 FDG PET for differentiation of malignant VCFxs remain limited; thus, further large multicenter studies are necessary to substantiate the diagnostic accuracy of F-18 FDG PET for the differentiation of malignant VCFxs. [ABSTRACT FROM AUTHOR]

Objective: Langerhans cell histiocytosis (LCH) is a very rare disease. The use of F-18 FDG PET/CT in LCH has recently become widespread. In this study, we aimed to investigate the role of F-18 FDG PET/CT in LCH cases. Material-Method: Eleven patients (mean age 23.09±19.02 (1-56); 6 males, 5 females) who underwent F-18 FDG PET/CT histopathologically diagnosed as LCH between 2014-2019 were included in the study. A total of 27 F-18 FDG PET/CT images were evaluated. SUVmax values of hypermetabolic lesions were calculated automatically. F-18 FDG PET/CT findings and other imaging methods (bone scintigraphy, computed tomography and magnetic resonance imaging) were compared. Results: F-18 FDG PET/CT was positive in 8/11 patients. The SUVmax mean value was calculated as 5.80±1.97. Seven (63.6%) patients were in single system (SS) and 4 (36.4%) were in multiple system-risk organ (MS-R) group. No statistically significant difference was observed between the single system-single lesion (SS-SL) and single systemmultiple lesion (SS-ML)/ML-R subgroups in terms of SUVmax values of the lesions (4.67±1.34 and 6.48±2,09, p=0.23). F-18 FDG PET/CT shows bone, bone marrow, skin, lymph node, lung, pituitary, kidney and pancreas involvement. While F-18 FDG PET/CT was concordant with other imaging methods in 5/11 patients, F-18 FDG PET/CT was found to be superior to other imaging methods in 4/11 patients. F-18 FDG PET/CT was also false negative in 2/11 patients. Partial/complete metabolic response was detected in 6 patients who underwent F-18 FDG PET/CT after treatment, and reactivation was detected in 2 patients. Conclusions: F-18 FDG PET/CT can be used for staging, response to treatment and reactivation in LCH patients. In particular, it is superior to other imaging modalities except for small and cystic lung lesions in the differentiation of active/inactive lesions. [ABSTRACT FROM AUTHOR]

Abstract Background Breast lesions closer than 2 cm to the chest wall are difficult to position in the field of view of dedicated breast PET (db-PET) systems. This inability to detect such lesions is a significant limitation of these systems. The primary objective of this study was to determine if modifications to the design of the imaging table and detector used for a db-PET system would enable improved visualization of breast tissue close to the chest wall. All studies were performed on a commercially available db-PET system (Mammi-PET). A central square section of the imaging table, containing the standard 180-mm circular aperture, was modified such that it could be removed and replaced by thinner sections with a larger aperture. Additional changes were made to the cover plate of the detector array and the patient mattress. A total of 60 patients were studied. After administration of F-18 FDG, 30 patients were imaged with a 220-mm-diameter aperture and the standard aperture, and 30 patients with a 200-mm aperture and the standard aperture. On all scans, the length of breast tissue in the field of view was measured as the greatest extent of tissue from the nipple back to the posterior edge of the breast. Image quality and patient comfort were recorded. Results Averaged over both breasts, relative to the standard aperture, the increase in breast length was 12.5 + 7.7 mm with the 220-mm aperture, and 12.3 + 6.5 mm with the 200-mm aperture (p

Eccrine carcinoma is an extremely rare malignant skin cancer arising from eccrine sweat glands with a high metastatic potential. It mainly occurs in the elderly, with equal incidence in both sexes. It usually spreads to regional lymph nodes, with liver, lungs, and bones being the most common sites of distant metastasis. Because of tumor rarity, little is known about the value of F18- FDG PET/CT in evaluating this disease. Our case report aims to increase current knowledge of F18- FDG PET/CT in eccrine sweat gland carcinoma as a noninvasive imaging tool for assessing the extension of the disease and detecting distant metastases. We reported a -96year-old man who presented with as lowly progressive, ill-margined erythematous papules and nodules with a crusted and eroded involving multiple sites of groin, scrotum, penis, left pelvic wall, left hip and left thigh for >3 years, which became extensive in the past 2 months. The histologic investigation confirmed the diagnosis of an eccrine carcinoma. He was performed F18- FDG PET/CT to further evaluate the lesions. FDG PET/ CT imaging revealed FDG uptake at the extensive skin lesion, involvement of lymph nodes, and multiple FDG-avid of liver, skeletal and lung metastases.

F-18 fluorodeoxyglucose (F-18 FDG) PET/CT plays an increasing role in the diagnostic workup of large vessel vasculitis (LVV); however, information on the relationship between immunosuppressive drugs and vessel wall uptake is limited. In 94 patients with a confirmed diagnosis of LVV, the vessel wall-to-liver ratio (VLR) was assessed in eight vessel segments. Patients were grouped according to intake of immunomodulatory drugs (Group 1, prednisone; Group 2, prednisone + methotrexate; and Group 3, prednisone + others) and compared to treatment-naïve individuals. A total of 54/94 (57.4%) were treated with immunomodulatory drugs (Group 1, 29/49 (53.7%); Group 2, 9/54 (16.7%); Group 3, 11/54 (20.4%); and Group 4, 5/54 (9.3%)), whereas the remainder received no therapy (40/94 (42.6%)). The mean VLR of the arterial segments correlated significantly with the hematopoietic organs (r ≥ 0.22, p ≤ 0.05), c-reactive protein (r ≥ 0.25, p ≤ 0.05), and prednisone dosage (r ≥ −0.4, p ≤ 0.05). Relative to treatment-naïve patients, a significantly lower VLR was recorded in 5/8 (62.5%) of the investigated vessel segments in Group 1 (p ≤ 0.02), in 6/8 of the vessel segments in Group 2 (75.0%, p ≤ 0.006), and in 7/8 of the segments in Group 3 (87.5%, p ≤ 0.05). In LVV, the F-18 FDG uptake in vessel wall as a marker of inflammatory activity was attenuated by immunomodulatory drugs, which provides a foundation for future serial monitoring of treatment efficacy.

Purpose: F-18 florapronol (FPN) is the commercially recognized beta-amyloid positron emission tomography (PET) radiotracer in Korea. This study compared the early F-18 florapronol PET with F-18 fluorodeoxyglucose (FDG) PET between healthy controls (HC) and Alzheimer's dementia (AD) patients. Methods: A total of 29 subjects (15 HC and 14 AD subjects) underwent F-18 FPN PET and F-18 FDG PET. F-18 FDG PET image was acquired from 30 to 60 min and F-18 FPN PET for 0 to 10 min. F-18 FPN and F-18 FDG images were spatially normalized with transformation matrices obtained from individual CT images and standardized uptake value ration (SUVR) from cerebellum area, and the global mean was calculated using PMOD 3.6. Pearson's correlation coefficients between F-18 FDG and early F-18 FPN for predefined cortical brain regions were calculated. Results: We compared the F-18 FDG and F-18 FPN for SUVR of a specific region in global mean normalization and cerebellum normalization, and most of the correlation coefficient was higher in global mean normalization. In global mean normalization, the correlation coefficient for SUVR of HC was higher than that of AD in all brain regions. Conclusions: Early F-18 FPN study can be used as a proxy marker for the F-18 FDG PET. [ABSTRACT FROM AUTHOR]

Background: Metabolic patterns on brain F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) can predict the decline in amnestic mild cognitive impairment (aMCI) to Alzheimer's disease dementia (AD) or other dementias.Objective: This study was undertaken to evaluate the diagnostic accuracy of baseline F-18 FDG-PET in aMCI for predicting conversion to AD or other dementias on follow-up.Patients and Methods: A total of 87 patients with aMCI were enrolled in the study. Each patient underwent a detailed clinical and neuropsychological examination and FDG-PET at baseline. Each PET scan was visually classified based on predefined dementia patterns. Automated analysis of FDG PET was performed using Cortex ID (GE Healthcare). The mean follow-up duration was 30.4 ± 9.3 months (range: 18-48 months). Diagnosis of dementia at follow-up (obtained using clinical diagnostic criteria) constituted the reference standard, and all the included aMCI patients were divided into two groups: the aMCI converters (MCI-C) and MCI nonconverters (MCI-NC). Diagnostic accuracy of FDG PET was calculated using this reference standard.Results: There were 23 MCI-C and 64 MCI-NC. Of the 23 MCI-C, 19 were diagnosed as probable AD, 1 as frontotemporal demetia (FTD), and 3 as vascular dementia (VD). Of the 64 MCI-NC, 9 had subjective improvement in cognition, and 55 remained stable. The conversion rate for all types of dementia in our series was 26.4% (23/87) and for Alzheimer's type dementia was 21.8% (19/87). The of PET-based visual interpretation was 91.9%. Sensitivity, specificity, positive predictive value, and negative predictive value for FDG-PET-based prediction of dementia conversion were 86.9% [confidence interval (CI) 66.4%-97.2%)], 93.7% (CI 84.7%-98.2%), 83.3% (CI 65.6%-92.9%), and 95.2% (CI 87.4%-98.9%), respectively. Kappa for agreement between visual and Cortex ID was 0.94 indicating excellent agreement. In the three aMCI patients progressing to VD, no specific abnormality in metabolic pattern was noted; however, there was marked cortical atrophy on computed tomography.Conclusion: FDG-PET-based visual and cortex ID classification has a good accuracy in predicting progression to dementia including AD in the prodromal aMCI phase. Absence of typical metabolic patterns on FDG-PET can play an important exclusionary role for progression to dementia. Vascular cognitive impairment with cerebral atrophy needs further studies to confirm and uncover potential mechanisms. [ABSTRACT FROM AUTHOR]

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Objective: The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the prediction of v-Ki-ras-2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in colorectal cancer (CRC) patients through a systematic review and meta-analysis. Methods: The PubMed and EMBASE database, from the earliest available date of indexing through April 30, 2018, were searched for studies evaluating the diagnostic performance of F-18 FDG PET/CT for prediction of KRAS mutation in CRC patients. Results: Across 9 studies (804 patients), the pooled sensitivity for F-18 FDG PET/CT was 0.66 (95% CI 0.60–0.73) without heterogeneity (I2 = 34.1, p = 0.14) and a pooled specificity of 0.67 (95% CI 0.62–0.72) without heterogeneity (I2 = 1.63, p = 0.42). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 2.0 (95% CI 1.7–2.4) and negative likelihood ratio (LR−) of 0.5 (95% CI 0.41–0.61). The pooled diagnostic odds ratio (DOR) was 4 (95% CI 3–6). Hierarchical summary receiver operating characteristic (ROC) curve indicates that the areas under the curve were 0.69 (95% CI 0.65–0.73). Conclusion: The current meta-analysis showed the low sensitivity and specificity of F-18 FDG PET/CT for prediction of KRAS mutation in CRC patients. The DOR was very low and the likelihood ratio scatter-gram indicated that F-18 FDG PET/CT might not be useful for prediction of KRAS mutation and not for its exclusion. Therefore, cautious application and interpretation should be paid to the F-18 FDG PET/CT for prediction of KRAS mutation in CRC patients. [ABSTRACT FROM AUTHOR]

Copyright of Istanbul Medical Journal is the property of Galenos Yayinevi Tic. LTD. STI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 77‐year‐old woman underwent F‐18 FDG PET/CT for evaluation of fever focus. Diffuse and intense hepatosplenic uptake was noted and lymphoma or tuberculosis was proposed. Liver biopsy revealed chronic granulomatous inflammation with Langerhans‐type giant cells and necrosis. A follow‐up PET/CT after anti‐tuberculosis treatment revealed that the hepatosplenic uptake had resolved. [ABSTRACT FROM AUTHOR]

F-18 FDG is the most widely used tracer in molecular imaging and it is applied for many purposes mainly in malignant diseases. Incidental finding are common in FDG-PET/CT imaging and includes benign and malignant lesions. Among the rare tumors, adrenal oncocytomas are uncommon findings and incidental findings of thyroid malignancies are not rare. Oncocytoma is a rare adrenocortical tumor and majority of bulky adrenal tumors are benign with uncertain incident of malignancy. In this study, we are reporting a 37-year-old man with two incidental malignancies detected by FDG-PET-CT. He has no symptoms has no blood and hormonal abnormalities. The scan demonstrated intense heterogeneous FDG uptake within the bulky oval shaped lesion in the left adrenal gland. Accordingly, open adrenalectomy was performed and diagnosis of adrenocortical carcinoma oncocytic type was established. Furthermore, a focal FDG uptake was identified in the right thyroid lobe and histopathology findings were consistent with well-differentiated papillary thyroid cancer. FDG plays a great role in identifying primary rare lesions and also detection of incidental findings at unexpected sites. [ABSTRACT FROM AUTHOR]

Purpose: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is emerging to be a useful tool in supporting the diagnosis of AIE. In this study, we describe the metabolic patterns on F-18 FDG PET imaging in AIE. Methods: Twenty-four antibody-positive patients (anti-NMDA-15, anti-VGKC/LGI1-6, and anti-GAD-3), 14 females and 10 males, with an age range of 2-83 years were included in this study. Each PET study was evaluated visually for the presence of hypometabolism or hypermetabolism and semiquantitatively using Cortex ID (GE) and Scenium (Siemens) by measuring regional Z-scores. These patterns were correlated with corresponding antibody positivity once available. Results: Visually, a pattern of hypometabolism, hypermetabolism, or both in various spatial distributions was appreciated in all 24 patients. On quantitative analysis using scenium parietal and occipital lobes showed significant hypometabolism with median Z-score of −3.8 (R) and −3.7 (L) and −2.2 (R) and −2.5 (L) respectively. Two-thirds (16/24) showed significant hypermetabolism involving the basal ganglia with median Z-score of 2.4 (R) and 3.0 (L). Similarly on Cortex ID, the median Z-score for hypometabolism in parietal and occipital lobes was −2.2 (R) and −2.4 (L) and −2.6 (R) and −2.4 (L) respectively, while subcortical regions were not evaluated. MRI showed signal alterations in only 11 of these patients. Conclusion: There is heterogeneity in metabolic topography of AIE which is characterized by hypometabolism most commonly involving the parietal and occipital cortices and hypermetabolism most commonly involving the basal ganglia. Scenium analysis using regional Z-scores can complement visual evaluation for demonstration of these metabolic patterns on FDG PET. [ABSTRACT FROM AUTHOR]

Background: Breast lesions closer than 2 cm to the chest wall are difficult to position in the field of view of dedicated breast PET (db-PET) systems. This inability to detect such lesions is a significant limitation of these systems. The primary objective of this study was to determine if modifications to the design of the imaging table and detector used for a db-PET system would enable improved visualization of breast tissue close to the chest wall. All studies were performed on a commercially available db-PET system (Mammi-PET). A central square section of the imaging table, containing the standard 180-mm circular aperture, was modified such that it could be removed and replaced by thinner sections with a larger aperture. Additional changes were made to the cover plate of the detector array and the patient mattress. A total of 60 patients were studied. After administration of F-18 FDG, 30 patients were imaged with a 220-mm-diameter aperture and the standard aperture, and 30 patients with a 200-mm aperture and the standard aperture. On all scans, the length of breast tissue in the field of view was measured as the greatest extent of tissue from the nipple back to the posterior edge of the breast. Image quality and patient comfort were recorded. Results: Averaged over both breasts, relative to the standard aperture, the increase in breast length was 12.5 + 7.7 mm with the 220-mm aperture, and 12.3 + 6.5 mm with the 200-mm aperture ( p < 0.05 for both apertures). In ~ 5% of cases, the larger apertures resulted in some degradation in image quality due to closer proximity to cardiac/hepatic activity. In 10-20% of cases, movement of the breast tissue was observed as the detector ring was moved to scan the anterior region of the breast. The patient survey indicated no significant difference in the comfort level between the standard aperture and either of the prototype apertures. Conclusions: Modifications to the image table and system resulted in a significant gain in the volume of breast tissue that could be imaged on the db-PET system and should allow better visualization of lesions close to the chest wall. [ABSTRACT FROM AUTHOR]

Primary hepatic neuroendocrine tumors (PHNETs) are extremely rare neoplasms. Herein, we report a case of a 70-year-old man with a hepatic mass. The non-contrast computed tomography (CT) image showed a low-density mass, and dynamic CT images indicated the enhancement of the mass in the arterial phase and early washout in the late phase. F18- fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and fused PET/CT images showed increased uptake in the hepatic mass. Whole-body 18F-FDG PET images showed no abnormal activity except for the liver lesion. Presence of an extrahepatic tumor was also ruled out by performing upper gastrointestinal endoscopy, total colonoscopy, and chest and abdominal CT. A posterior segmentectomy was performed, and histologic examination confirmed a neuroendocrine tumor (grade 1). The patient was followed up for about 2 years after the resection, and no extrahepatic lesions were radiologically found. Therefore, the patient was diagnosed with PHNET. To the best of our knowledge, no previous case of PHNET have been detected by 18F-FDG PET imaging.

Combined positron emission tomography (PET) and computed tomography (CT) scans are widely used in the staging and monitoring of most malignancies. The differential for PET-positive cutaneous lesions includes primary skin cancers, infections, cutaneous metastases from distant malignancies, and benign neoplasms. In dermatology, PET/CT scans have been most widely studied in patients with melanoma and Merkel cell carcinoma. The role of PET/CT scans in the management of other cutaneous malignancies is less clear, but it has shown great promise in the management of patients with squamous cell carcinoma and cutaneous lymphoma. This review seeks to address the usefulness of PET/CT scans in nonmelanoma skin cancer and to provide guidance regarding the management of patients with incidental PET-positive nodules. Currently, there is limited experience with PET/CT scans for staging and monitoring of non-head and neck metastatic basal cell and squamous cell carcinomas, and results show limited sensitivity and specificity. We also address the evidence for management of an incidental PET-positive cutaneous nodule and recommend obtaining a biopsy specimen in patients with a known noncutaneous malignancy, a history of primary skin cancer, or a high risk of either cutaneous or noncutaneous malignancy. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study was to evaluate the clinical usefulness of additional low-dose high-resolution lung computed tomography (LD-HRCT) combined with 18F-fluoro-2-deoxyglucose positron emission tomography with CT (18FFDG PET/CT) compared with conventional lung setting image of 18F-FDG PET/CT for the detection of metastatic lung nodules from colorectal cancer. Methods From January 2011 to September 2011, 649 patients with colorectal cancer underwent additional LD-HRCT at maximum inspiration combined with 18F-FDG PET/CT. Forty-five patients were finally diagnosed to have lung metastasis based on histopathologic study or clinical follow-up. Twenty-five of the 45 patients had =5 metastatic lung nodules and the other 20 patients had >5 metastatic nodules. One hundred and twenty nodules in the 25 patients with=5 nodules were evaluated by conventional lung setting image of 18FFDG PET/CT and by additional LD-HRCT respectively. Sensitivities, specificities, diagnostic accuracies, positive predictive values (PPVs), and negative predictive values (NPVs) of conventional lung setting image of 18F-FDG PET/CT and additional LD-HRCT were calculated using standard formulae. The McNemar test and receiver-operating characteristic (ROC) analysis were performed. Results Of the 120 nodules in the 25 patients with =5 metastatic lung nodules, 66 nodules were diagnosed as metastatic. Eleven of the 66 nodules were confirmed histopathologically and the others were diagnosed by clinical follow-up. Conventional lung setting image of 18F-FDG PET/CT detected 40 of the 66 nodules and additional LD-HRCT detected 55 nodules. All 15 nodules missed by conventional lung setting imaging but detected by additional LDHRCT were<1 cm in size. The sensitivity, specificity, and diagnostic accuracy of the modalities were 60.6 %, 85.2 %, and 71.1 % for conventional lung setting image and 83.3 %, 88.9 %, and 85.8 % for additional LD-HRCT. By ROC analysis, the area under the ROC curve (AUC) of conventional lung setting image and additional LDHRCT were 0.712 and 0.827 respectively. Conclusion Additional LD-HRCT with maximum inspiration was superior to conventional lung setting image of 18F-FDG PET/CT for the detection of metastatic lung nodules from colorectal cancer (P<0.05). [ABSTRACT FROM AUTHOR]

Nuclear medicine imaging can provide important complementary information in the management of pediatric patients with neurological diseases. Pre-surgical localization of the epileptogenic focus in medically refractory epilepsy patients is the most common indication for nuclear medicine imaging in pediatric neurology. In patients with temporal lobe epilepsy, nuclear medicine imaging is particularly useful when magnetic resonance imaging findings are normal or its findings are discordant with electroencephalogram findings. In pediatric patients with brain tumors, nuclear medicine imaging can be clinically helpful in the diagnosis, directing biopsy, planning therapy, differentiating tumor recurrence from post-treatment sequelae, and assessment of response to therapy. Among other neurological diseases in which nuclear medicine has proved to be useful are patients with head trauma, inflammatory-infectious diseases and hypoxic-ischemic encephalopathy. [ABSTRACT FROM AUTHOR]

Purpose: Primary bone lymphoma (PBL) is a rare type of malignant lymphoma. Few data have been reported regarding the utility of F-18 FDG PET/CT in this disease. The aim of this study was to assess the role of F-18 FDG PET/CT in the diagnosis and therapeutic effect evaluation of PBL.Materials and Methods: A total of 19 consecutive patients with PBL were enrolled. Whole-body PET/CT scan was performed for all patients. The diagnosis of PBL was established by histopathology and immunohistochemistry.Results: F-18 FDG PET/CT was positive in 94.7% (18/19) of patients. Uptake of FDG in lesions was intense with SUVmax of 15.14 ± 11.82. Multiple involved lesions were found in 47.4% (9/19) patients, while 52.6% presented with a single involved lesion. Based on the lesions, PET detected 98.9% (87/88) lesions. Among them, 71.6% (63/88) lesions were found to be located in axial skeleton and 28.4% (25/88) in the extremity skeleton. FDG PET/CT also found the lesions infiltrate to the surrounding soft tissue in 84.2% (16/19) patients. On the syn-modality CT, the bone destruction was noted in 43.2% (38/88) of the lesions, of which 50.0% lesions presented as slight change in bone density and 50.0% as severe change. The diagnostic sensitivity of PET was much higher than that of CT (98.9% vs. 43.2%, P=0.000). PET/CT was performed for evaluation of treatment response in 13 patients. In 12 patients with complete response(CR), PET/CT found the 25 lesions were F-18 FDG fully resoluted after treatment, however, bone destruction was still presented in 72.0% (18/25) lesions.Conclusions: The present study suggests that F-18 FDG PET/CT was a sensitive imaging modality for diagnosis and treatment response evaluation of PBL. [ABSTRACT FROM AUTHOR]

The integration of PET and CT has a lot of benefits the evaluation of oncologic patients. CT based attenuation correction is lead to shorter investigation time of PET/CT scan. There are significant improvement of sensitivity and specifity of diagnosis, staging, re-staging and radiotherapy planning in patienst with lung carcinoma by PET/CT hybrid imaging. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the correlation of primary tumor FDG uptake to clinicopathological prognostic factors in invasive ductal carcinoma of the breast. Methods: We retrospectively reviewed 136 of 215 female patients with pathologically proven invasive ductal breast cancer from January 2008 to December 2011 who underwent F-18 FDG PET/CT for initial staging and follow-up after curative treatment with analysis of estrogen receptor (ER), progesterone receptor (PR) and human epithelial growth factor receptor 2 (HER2). The maximum standardized uptake value (SUVmax) of the primary breast tumor was measured and compared with hormonal receptor and HER2 overexpression status. Results: The high SUVmax of primary breast tumors is significantly correlated with the clinicopathological factors: tumor size, histologic grade, TNM stage, negativity of ER, negativity of PR, HER2 overexpression and triple negativity. The recurrent group with non-triple negative cancer had a higher SUVmax compared with the non-recurrent group, though no significant difference in FDG uptake was noted between the recurrence and non-recurrent groups in subjects with triple-negative cancer. Lymph node involvement was the independent risk factor for cancer recurrence in the multivariate analysis. Conclusions: In conclusion, high FDG uptake in primary breast tumors is significantly correlated with clinicopathological factors, such as tumor size, histologic grade, TNM stage, negativity of the hormonal receptor, HER2 overexpression and triple negativity. Therefore, FDG PET/CT is a helpful prognostic tool to direct the further management of patients with breast cancer. [ABSTRACT FROM AUTHOR]

F-18 fluorodeoxyglucose (FDG) is a highly influential radiotracer that provides valuable information in many cancer types. However, the normal biodistribution of F-18 FDG is often variable and can be altered by intrinsic or iatrogenic factors. We report a case of diffuse symmetrically increased skeletal muscle uptake and relatively decreased hepatic uptake on F-18 FDG PET/CT in a 57-year-old female with pulmonary adenocarcinoma. Detailed clinical evaluation and retrospective radiologic evaluation revealed that she had been diagnosed with subacute thyroiditis 2 weeks ago. After 6 weeks, F-18 FDG distribution was normalized at the follow-up PET/CT study. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the clinical impact of the preoperative F-FDG PET/CT in the initial workup of breast cancer with clinically negative axillary nodes. Whether the status of the clinical axillary nodal involvement can be considered a parameter for making a decision to omit the preoperative F-FDG PET/CT in the situation reported herein was also determined. A total of 178 patients who had newly diagnosed breast cancer and for whom the conventional diagnostic modalities showed no sign of axillary node metastasis were retrospectively enrolled in this study. All the patients underwent preoperative F-FDG PET/CT. The images and histologic results that were obtained were analyzed. F-FDG PET/CT detected primary lesions in 156 of the 178 patients, with an overall sensitivity of 87.6 %, and false negative results were obtained for 22 patients (12.4 %). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of F-FDG PET/CT in the detection of axillary nodes were 20.8, 86.9, 37.0, 74.8, and 69.1 %, respectively. Extra-axillary node metastasis was identified in two patients (1.1 %) who had internal mammary nodes. There was no distant metastasis, but coexisting primary tumor was detected in five patients (2.8 %). In total, the therapeutic plan was changed based on F-FDG PET/CT in seven (3.9 %) of the 178 patients, but considering only the cases confined to breast cancer, the change occurred in only two patients (1.1 %). F-FDG PET/CT almost did not affect the initial staging and treatment plan in breast cancer with clinically negative axillary node. If the axillary node is clinically negative in the preoperative workup of breast cancer, then F-FDG PET/CT can be omitted. [ABSTRACT FROM AUTHOR]

Abstract. Cancers of unknown primary origin (CUP) have poor prognosis and the median survival for patients with CUP is approximately 1 year. This survival can be extended by the identification of the primary origin and treating with specific therapy. F-18 FDG PET/CT scans of 75 patients (39 female, 36 male, mean age 60 ±12) with CUP referred to our clinic between January 2009 and January 2011 were evaluated retrospectively. Whole body images were obtained 60 minutes after the injection of approximately 370 MBq (10 mCi) F-18 FDG by PET/CT (Gemini-TOF-Philips). Emission scans were obtained for 1.5 min per bed position and transmission scans were obtained with low dose CT using 50 mA and 120 kvp. The tumor was identified histopathologically in 58 of 75 patients. 4 of 58 patients were treated as CUP. 17 of 75 patients could not be followed, so final diagnosis could not be made. In 54 patients, the primary was identified as 17 lung, 8 colorectal, 7 breast, 3 stomach, 3 pancreas, 2 endometrial, 2 nasopharynx, 2 gallbladder cancers, 2 lymphoma, 2 peritoneum, 1 maxillary sinus, 1 salivary gland carcinoma, 1 brain tumor, 1 leiomyosarcoma, 1 ovary cancer and 1 multiple myeloma. If reports are considered, F-18 FDG PET/CT helped to detect primary origin in 65% of these 58 patients, 38 of 54 primary sites were true positive (70%). There were 6 false positive sites (10.3%), 16 false negative (27.5%) results in F-18 FDG PET/CT. After the retrospective evaluation of the false negative patients, we have realized that primary sites were ignored in 5 of 14 patients, so actually F-18 FDG PET/CT helped in 74% of the patients showing 43 of 54 primary sites (80%). In first evaluation, F-18 FDG PET/CT missed 2 breast cancers, 1 lymphoma, 1 colon cancer and 1 intra maxillary sinus cancer. F-18 FDG PET/CT is an important imaging tool for detecting primary origin in the patients with CUP. F-18 FDG PET/CT helped in 74% of the patients showing the primary sites. In the patients with CUP, lung, breast, colon and the physiologic uptake areas should be scrutinized carefully for any tumor location. [ABSTRACT FROM AUTHOR]

The contribution that F-18 fluoro-2-deoxyglucose positron emission tomography/computed tomography (F-18 FDG) PET/CT makes to the diagnosis of malignancy in patients with hemophagocytic lymphohistiocytosis (HLH) is still uncertain. The aim of this study was to evaluate the diagnostic performance of F-18 FDG PET/CT for the detection of underlying malignancy, to investigate the correlation between PET and laboratory parameters, and to identify prognosis-related factors in patients with secondary HLH. We enrolled 14 patients who were diagnosed with HLH and referred for F-18 FDG PET/CT to exclude malignancy. The diagnostic performance of F-18 FDG PET/CT for malignancy detection was assessed. The correlations between PET and laboratory parameters were determined. The prognostic significance of the following factors was evaluated: PET and laboratory parameters, age in years, presence of underlying malignancy, and fever and splenomegaly. Six of the 14 patients had malignancies (four with lymphoma, one with multiple myeloma, and one with colonic malignancy). Sensitivity, specificity, and diagnostic accuracy of F-18 FDG PET/CT for malignancy detection were 83, 62.5, and 71.4 %, respectively. F-18 FDG uptake in the bone marrow and spleen was positively correlated with neutrophil count and C-reactive protein. All of the PET parameters, but none of the clinical or laboratory parameters, were significantly associated with patient outcome, as determined by univariate analysis. Given the small sample size, F-18 FDG PET/CT was useful for detecting underlying malignancy, and PET parameters correlated with laboratory parameters that reflected inflammatory status. F-18 FDG PET/CT might provide prognostic information for the management of patients with secondary HLH. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the characteristics of PET and CT features of mediastinal metastatic lymph nodes on F-18 FDG PET/CT and to determine the diagnostic criteria in nodal staging of non-small cell lung cancer. Methods: One hundred four non-small cell lung cancer patients who had preoperative F-18 FDG PET/CT were included. For quantitative analysis, the maximum SUV of the primary tumor, maximum SUV of the lymph nodes (SUVmax), size of the lymph nodes, and average Hounsfield units (aHUs) and maximum Hounsfield units (mHUs) of the lymph nodes were measured. The SUVmax, SUV ratio of the lymph node to blood pool (LN SUV/blood pool SUV), SUV ratio of the lymph node to primary tumor (LN SUV/primary tumor SUV), size, aHU, and mHU were compared between the benign and malignant lymph nodes. Results: Among 372 dissected lymph node stations that were pathologically diagnosed after surgery, 49 node stations were malignant and 323 node stations benign. SUVmax, LN SUV/blood pool SUV, and size were significantly different between the malignant and benign lymph node stations ( P < 0.0001). However, there was no significant difference in LN SUV/primary tumor SUV ( P = 0.18), mHU ( P = 0.42), and aHU ( P = 0.98). Using receiver-operating characteristic curve analyses, there was no significant difference among these three variables (SUVmax, LN SUV/blood pool SUV, and size). The optimal cutoff values were 2.9 for SUVmax, 1.4 for LN SUV/blood pool SUV, and 5 mm for size. When the cutoff value of SUVmax ≥2.9 and size ≥5 mm were used in combination, the positive predictive value was 44.2 %, and the negative predictive value was 90.9 %. When we evaluated the results based on the histology of the primary tumor, the negative predictive value was 92.3 % in adenocarcinoma (cutoff values of SUVmax ≥2.3 and size ≥5 mm) and 97.2 % in squamous cell carcinoma (cutoff values of SUVmax ≥3.6 and size ≥8 mm), separately. Conclusions: In the lymph node staging of non-small cell lung cancer, SUVmax, LN SUV/blood pool SUV, and size show statistically significant differences between malignant and benign lymph nodes. These variables can be used to differentiate malignant from benign lymph nodes. The combination of the SUVmax and size of lymph node might have a good negative predictive value. [ABSTRACT FROM AUTHOR]