Evaluation of FDG uptake patterns in POEMS syndrome on 18-FDG PET/CT.

Objectives: The purpose of this study is to evaluate biodistribution of FDG uptake in the 18-FDG positron emission tomography/computed tomography (PET/CT) depending in POEMS syndrome.

Methods: We retrospectively analyzed 34 patients from Apr 2007 to Apr 2016 who underwent staging 18-FDG PET/CT for POEMS syndrome. Serum analysis (calcium, hemoglobin, creatinine, M protein and VEGF levels) obtained within 3 days of PET/CT were recorded. FDG PET/CT analysis of POEMS syndrome included SUV max and SUV mean data of liver, spleen, mesentery fat, subcutaneous tissue and mediastinal aorta. To compare FDG uptake patterns in POEMS, we compared age- and gender- matched FDG uptake in patients who underwent FDG PET/CT for medical observation and had no evidence of malignancy or overt systematic inflammation. To evaluate organomegaly, we measured maximal craniocaudal (cc), ventrodorsal (vd) and coronal liver diameter and craniocaudal (cc) diameter of spleen. Independent sample t-test was performed on clinical data and SUV data. Paired t-test was performed for POEMS patients and control group to evaluate for significant changes if FDG uptake distribution.

Results: Patients with POEMS syndrome showed significantly lower FDG uptake in the liver compared to control patients (SUVmean 1.68 ± 0.41 vs 2.29 ± 0.37, p<0.001). However, blood pool activity was also significantly decreased (SUVmean 1.28 ± 0.33 vs 1.61 ± 0.23, p<0.001). Within POEM patients, lower hepatic FDG uptake were seen in patients with hypocalcemia (serum calcium &#8804; 8.0 mg/dl) compared with POEMS syndrome patients with normal calcium levels (SUVmean = 1.49 ± 0.31 vs. 1.78 ± 0.41, p=0.05). Hypocalcemic patients also had increased mesenteric fat FDG uptake compared to normal calcium levels (SUVmean = 0.83 ± 0.33 vs. 0.57 ± 0.20, p=0.007). Hepatomegaly (liver volume > 2,000 ml) patients also shows lower hepatic FDG uptake compared with normal hepatic volume (SUVmean = 1.90 ± 0.27 vs. 1.57 ± 0.42, p=0.023). Other biochemical analysis were not significantly correlated with FDG uptake.

Conclusion: Patients with POEMS syndrome have lower FDG uptake in the liver and blood pool activity compared to normal population, - this lowered hepatic uptake is correlated with hypocalcemia and hepatomegaly. Lower mesenteric fat glycolysis is also correlated with hypocalcemia. Research Support: