The Value Of¹⁸F-FDG PET/CT In The Diagnosis Of Primary Central Nervous System Lymphoma

Objective：In this study, all diagnostic reference of18F-FDG PET/CT indifferential diagnosis PCNSL, were been statistically analyzed．The study alsoproved good clinical value of differential diagnosis PCNSL using18F-FDGPET/CT.Finally, it can provide scientific and standard diagnostic criterion fordiagnosis PCNSL and improve the accuracy of18F-FDG PET/CT in diagnosingPCNSL．Methods：1. All Cases came from our hospital.40patients those who have had18F-FDGPET/CT examination in our hospital were studied.Including10cases of PCNSLpatients,18cases of gliomas patients and12cases of patients with brain metastases,a total of78lesions. All lesions were confirmed by pathology or clinical follow-up.2. Imaging instrument was German Siemens Discovery16HR PET/CT.Firstspiral CT scan, acquisition conditions: tube voltage120kV, tube current of80mA,tube lap rotation time0.4s, thickness3.75mm. PET acquisition and reconstruction:3D acquisition, take six to eight beds, each bed of chest and abdomen is2min, andeach bed of brain is5min. After the data acquisition is completed to CT attenuationcorrection of the PET image, the computer software to automatically complete theCT image and the PET image reconstruction and fusion after correction, respectivelyget CT, PET and PET/CT images.The imaging results is common interpreted by two or three experiencednuclear medicine physicians and physicians of Radiology Imaging. 3.To analyze the imaging results of78lessions according to18F-FDG PET/CTimaging, and summarize the performance characteristics of PCNSL18F-FDG PET/CT imaging.4.The maximum standardized uptake value (SUVmax)and the meanstandardized uptake value(SUVmean), were the two mainly diagnostic references of18F-FDG PET, which were analyzed in this study. The statistical distribution ofSUVmax and SUVmean of78lesions were observed.Between-group differences inSUVmax and SUVmean of PCNSL with gliomas and brain metastases wereanalyzed.With an area under the ROC curve to analysis the best cut-off value of theSUVmax and SUVmean in diagnosing PCNSL.Finally the diagnostic value of thetwo references of PET had been evaluated．5.Statistical analysis: SPSS18.0statistical software for data analysis was used.The uptake degree of radiotracer SUVmean and SUVmax in PCNSL, gliomas andbrain metastases were represented by x±s. Independent sample t test between thegroups comparing were used; The Receiver Operating characteristics(ROC) Curvewas used to evaluate the diagnostic value of SUVmax and SUVmean for PCNSL,the area under the ROC curve was used to evaluate the diagnostic value of SUVmaxand SUVmean.Results:1. PCNSL was a kind of multiple tumor and mainly occur on the screen andmore occur in the deep brain. Its uptake of18F-FDG was significantly higher and thetracer inside the lesions was evenly.Otherwise, inside the lesions hemorrhage,necrosis, cystic degeneration and calcification were rare. And peritumoral edemawas rare, mainly in mild to moderate edema.2. The SUVmax in PCNSL was higher than gliomas, there was a significantdifference between the two sets of data(t=2.996, p=0.004); The SUVmax in PCNSLwas higher than brain metastases, there was a significant difference between the twosets of data(t=4.143, p=0.000).3. The SUVmean in PCNSL was higher than gliomas, there was a significant difference between the two sets of data(t=3.505, p=0.001); The SUVmean in PCNSLwas higher than brain metastases, there was a significant difference between the twosets of data(t=4.985, p=0.000).4. SUVmax>12.05and SUVmean>10.25was the optimal threshold for18F-FDG PET/CT imaging in the diagnosis of PCNSL.When SUVmax>12.05, thesensitivity for the diagnosis of PCNSL was83.1%, the specificity was66.7%. WhenSUVmean>10.25, the sensitivity for the diagnosis of PCNSL was81.0%, thespecificity was77.2%.Conclusions:1.18F-FDG PET/CT imaging can be used as an important reference for thediagnosis of PCNSL which had special findings.2. The SUVmax and SUVmean of PCNSL was significantly higher than that ingliomas and brain metastases.3. The optimal threshold value of18F-FDG in diagnosing PCNSL wasSUVmax>12.05and SUVmean>10.25, there is a high sensitivity and specificity inPCNSL diagnosis at this threshold.4. The diagnostic specificity of SUVmean is superior to that of SUVmax; thediagnostic sensitivity of SUVmaxis superior to that of SUVmean.