Lymphoma total lesion glycolysis leads to hyperlactatemia and reduction of brain glucose utilization.

Clarifying the mechanism of lymphoma-associated hyperlactatemia could help identify patients at risk. Here, 129 non-Hodgkin's lymphoma patients suspected of blood lactate elevation underwent blood measurement and 18F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) on the same day. Blood lactate elevation was mild (1.0-2.5 mmol/L) in 60, moderate (2.5-4.0 mmol/L) in 46, and severe (≥ 4.0 mmol/L) in 23 subjects. Subjects with severe lactate elevation had higher lymphoma stage, worse IPI risk, poorer ECOG performance, and higher tumor TLG. Furthermore, there was a linear correlation between blood lactate concentration and lymphoma TLG (Spearman's r = 0.367; P < 0.0001). Brain FDG uptake was low (SUVave < 4.0) in 81 patients that were older, had greater stage and IPI risk, worse ECOG performance, and higher blood lactate. Brain SUVave showed inverse correlation with blood lactate (Spearman's r = - 0.564; P < 0.0001) and lymphoma TLG (Spearman's r = - 0.252; P = 0.0066), as well as with stage, ECOG score, and IPI risk. Multivariable regression analysis confirmed increased blood lactate and lymphoma TLG as significant explanatory variables for reduced brain SUVave (both P < 0.0001). Hence, blood lactate elevation in lymphoma patients is the result of glycolytic tumor burden. Since brain cells prefer lactate over glucose as energy source when blood lactate level is increased, this causes proportional reductions of brain FDG uptake. FDG PET/CT can therefore identify high glycolytic lymphoma burden at risk of hyperlactatemia and may provide estimates of its severity by reductions in brain uptake.

The role of 18F-fluorodeoxyglucose-positron emission tomography/computed tomography in the differential diagnosis of pericardial disease.

This study aimed to assess the role of 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18FDG-PET/CT) in the differential diagnosis of pericardial disease. The diagnosis is often troublesome because pericardial fluid analysis or biopsy does not always provide answers. 18FDG-PET/CT can visualize both inflammation and malignancy and offers a whole-body assessment. Patients who visited the Pericardial Disease Clinic of Samsung Medical Center with an 18FDG-PET/CT order code were extracted. Exclusion criteria were as follows: (1) the purpose of the differential diagnosis was not pericardial disease; (2) the patient had a known advanced-stage malignancy; (3) the patient already have confirmative diagnosis using a serology, pericardial effusion analysis or biopsy. The analysis included 107 patients. The most common final diagnosis was idiopathic (n = 46, 43.0%), followed by tuberculosis (n = 30, 28.0%) and neoplastic (n = 11, 10.3%). A maximum standardized uptake value (SUVmax) ≥ 5 typically indicates tuberculosis or neoplastic pericarditis except in just one case of autoimmune pericarditis); especially all of the SUVmax scores ≥ 10 had tuberculosis. The diagnostic yield of pericardial biopsy was very low (10.2%). Interestingly, all of the pericardium with an SUVmax < 4.4 had nondiagnostic results. In contrast, targeted biopsies based on 18FDG uptake demonstrated a higher diagnostic yield (38.7%) than pericardium. The sensitivity of 18FDG-PET/CT was 63.6%. The specificity was 71.9%. The positive predictive value was 20.6%. The negative predictive value 94.5%, and the accuracy was 71.0% for excluding malignancy based upon the FDG uptake patterns. It is possible to explore the differential diagnosis in some patients with difficult pericardiocentesis or pericardial biopsy in a noninvasive manner using on the SUVmax or uptake patterns. In addition, the biopsy strategy depending on 18FDG uptake is helpful to achieve biopsy more safely and with a higher yield. 18FDG-PET may enhance the diagnostic efficacy in patients with pericardial disease.

Inverse Prognostic Relationships of 18F-FDG PET/CT Metabolic Parameters in Patients with Distal Bile Duct Cancer Undergoing Curative Surgery.

PURPOSE: As there were few previous studies with a small number of subjects, the purpose of this was to evaluate the prognostic significance of 18F-FDG PET/CT in patients with distal bile duct cancer undergoing curative surgery. METHODS: The study included 40 patients (M/F = 24:16; age 68.0 ± 8.0 years) who underwent preoperative 18F-FDG PET/CT followed by curative surgical resection. The participant's age, sex, Eastern Cooperative Oncology Group performance-status score, baseline serum CA 19-9 level, stage, pathologic T and N stages, tumor size, tumor grade, tumor growth pattern, R0 resection, and adjuvant therapy were included as clinicopathological variables for predicting overall survival. The PET variables were maximum standardized uptake value (SUVmax), average SUV (SUVavg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the tumor. The Kaplan-Meyer method and Cox proportional hazards model were used for the survival analysis. RESULTS: A total of 15 of 40 patients (37.5%) died during the follow-up period. In univariate analysis, low SUVmax (≤ 2.7, p = 0.0005) and low SUVavg (≤ 2.6, p = 0.0034) were significant predictors of poor overall survival. In multivariate analyses, only low SUVmax (HR = 6.7016, 95% CI 1.9961-22.4993, p = 0.0047) was an independent prognostic factor associated with poor overall survival. CONCLUSION: The SUVmax of the primary tumor measured by 18F-FDG PET/CT was an independent significant prognostic factor for overall survival in patients with distal bile duct cancer. However, different results from a previous study warrant further large sample-sized study.

Intra-patient Variability of FDG Standardized Uptake Values in Mediastinal Blood Pool, Liver, and Myocardium during R-CHOP Chemotherapy in Patients with Diffuse Large B-cell Lymphoma.

PURPOSE: 18F-fluorodeoxyglucose (FDG) PET/CT is useful for staging and evaluating treatment response in patients with diffuse large B-cell lymphoma (DLBCL). A five-point scale model using the mediastinal blood pool (MBP) and liver as references is a recommended method for interpreting treatment response. We evaluated the variability in standardized uptake values (SUVs) of the MBP, liver, and myocardium during chemotherapy in patients with DLBCL. METHODS: We analyzed 60 patients with DLBCL who received rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) treatment and underwent baseline, interim, and final FDG PET/CT scans. The FDG uptakes of lymphoma lesions, MBP, liver, and myocardium were assessed, and changes in the MBP and liver SUV and possible associated factors were evaluated. RESULTS: The SUV of the liver did not change significantly during the chemotherapy. However, the SUVmean of MBP showed a significant change though the difference was small (p = 0.019). SUVmean of MBP and liver at baseline and interim scans was significantly lower in patients with advanced Ann Arbor stage on diagnosis. The SUVmean of the MBP and liver was negatively correlated with the volumetric index of lymphoma lesions in baseline scans (r = -0.547, p < 0.001; r = -0.502, p < 0.001). Positive myocardial FDG uptake was more frequently observed in interim and final scans than in the baseline scan, but there was no significant association between the MBP and liver uptake and myocardial uptake. CONCLUSIONS: The SUV of the liver was not significantly changed during R-CHOP chemotherapy in patients with DLBCL, whereas the MBP SUV of the interim scan decreased slightly. However, the SUV of the reference organs may be affected by tumor burden, and this should be considered when assessing follow-up scans. Although myocardial FDG uptake was more frequently observed after R-CHOP chemotherapy, it did not affect the SUV of the MBP and liver.