Correlation between the degree of malignancy of pheochromocytoma and the maximum standardized uptake value measured by 18F-FDG PET/CT

Abstract

Objective To analyze the correlation of 18F-FDG SUVmax with plasma free metanephrines (MN),normetanephrine (NMN) and 131 I-meta-iodobenzylguanidine (MIBG) scintigraphy,and to explore the role of 18 F-FDG PET/CT in distinguishing between benign pheochromocytoma (BPCC) and malignant pheochromocytoma (MPCC).Methods 18F-FDG PET/CT,plasma MN and NMN,and 131 I-MIBG SPECT were studied in 19 patients with pheochromocytoma confirmed by postoperative pathology,including 11 benign and 8 malignant cases.ROC curve was drawn,and 18 F-FDG SUVmax of patients with MN (NMN) positive and negative results was compared using two independent sample t-test by SPSS 17.0.Results Both BPCC and MPCC showed positive findings on 18F-FDG PET/CT.SUVmax of MPCC ( 19.40 ± 7.39)was significantly higher than that of BPCC (7.44 ± 4.47; t =-4.40,P ＜ 0.01 ).Using a cut-off value of 8.85 on the ROC curve for determining BPCC and MPCC,the sensitivity,specificity and accuracy was 8/8,81.8％ (9/11 ) and 89.5％ (17/19),respectively.SUVmax of adrenal lesions ( 19.75 ± 8.64) was significantly higher than that of extra-adrenal lesions (9.12 ± 5.83 ; t =- 3.18,P ＜ 0.05 ).The difference of SUVmax between new and recurrent lesions was not significant (t =-1.68,P ＞0.05).SUVmaxof MN negative cases ( 13.57 ±8.61 ) was significantly higher than that of MN positive cases (6.63 ±2.42; t =2.70,P＜0.05 ).The difference of SUVmax between NMN negative and positive cases was not significant (t =-0.93,P ＞0.05).Seven patients underwent 131 I-MIBG SPECT,among which one case with BPCC and four cases with MPCC were negative.The 18F-FDG PET/CT results were positive in all seven patients.Conclusions 18F-FDG PET/CT can be used as a second-line diagnostic tool for patients with negative MN or indeterminate 131 I-MIBG SPECT findings.The degree of FDG uptake has potential in the differentiation of benign from malignant pheochromocytoma. Key words: Pheochromocytoma ; Tomography, emission-computed; Tomography, X-ray computed; Deoxyglucose; Epinephrine ; Norepinephrine