Comparison Of ¹⁸F-FCH And ¹⁸F-FDG PET/CT Dual Tracerimaging In The Grading Ofcerebral Gliomas

ObjectiveCerebral Glioma is themost common type of primary tumor inthe central nervous system, the incidence accounting for more than a half of primary intracranial malignant tumors and has increased year by year,the five years mortality rate ofmalignant gliomas only less than pancreatic cancer and lung cancer, ranked third of all malignancies, serious harm to human health. Accurate preoperative diagnosis and assessment of malignant lesions have great value to the selection oftreatment regimen and prognostic. Positron emission tomography?PET? as a noninvasive molecular imaging technique that uses different tracers to reflect physiological and biochemical changes in tumor tissue at the molecular level, which is more intuitive, more fully reflect the biological characteristics of the tumor, it has been widely used in gliomas preoperative diagnosis and classification. ¹⁸F-FDG as a glucose analogue, is the most commonly agent used in clinical PET imaging currently, and the metabolism of tumor lesions displayed high uptake, it is an effective method for the diagnosis and grading of gliomas. Brain energy metabolism is particular compared with other tissues, glucose as the sole source of energy and the demand for glucose is greater thanother organizations with same weight, so FDG PET imaging showed high background withpoor contrast of tumor and normal brain tissues. Under physiological conditions, choline is not an energy source of the brain, the uptake ofcholine is low in normal brain tissue, ¹⁸F-FCH as a cholineanalogue tracer, can it be compensate the deficiencies of¹⁸F-FDG imaging, has become a new research direction. in this study, wecompare the value of the gliomas grading by ¹⁸F-FDGand¹⁸F-FCH PET/CT to provide more reliable information for the clinical treatment. Materials and Methods?1? The subject of the present study selected 33 cases with suspected brain glioma underwent PET/CTexamination from September 2014 to February 2016 in our nuclear medicine department.Patients with no history of other cancer, no radiotherapy or chemotherapy, no history of mental illness. Of which 18 males and 15 females, aged 17-67 years, mean age 50.4 years.?2? Thirty-three patients underwent ¹⁸F-FDG PET/CT imaging confirmed no other concurrenttumor or other diseases withabnormal concentration of ¹⁸F-FDG. 31 patientsunderwent dual-phase¹⁸F-FCH PET/CT imaging inthe next day, Acquisition time were 10 minutesand40 minutesrespectivelyafterinjection ofimaging tracer.Patients signed informed consent before the ¹⁸F-FCH PET/CT examination. PET data conducted in the Syngo workstation and attenuation correction by CT, then iterative reconstruction, reconstruction data obtained CT, PET and fusion of both images and 3D maximum intensity projection image?MIP?.?3? All images analyzedby visual and semi-quantitative.?1?Visual analysis: Detection of lesions according to the position, shape and the density of the abnormal uptake foci. Comparing the radioactive concentration level of lesion area and the surrounding normal brain tissue or contralateral site. If the radioactive concentration level higher than the surrounding normal brain tissue or contralateral corresponding site is defined as the positive; reverse defined as negative.?2? Semi-quantitative analysis: SUVmaxofthe fused imagefocus on themost metabolicallyactivepart of andcomputing the lesion to the contralateral white matter ratio?L/WM?. Use TPS software outline tumor boundary along the CT images to obtain the tumor volume.?4? Thirty patients underwent craniotomy resection or stereotactic biopsy after PET/CT examination,specimens diagnosed by immunohistochemistry and pathology, and test Ki-67 index. One patient underwent cerebrospinal fluid puncture, two cases were followed up.?5? Compare PET/CT findings and pathology or follow-up results of patients. Calculated the sensitivity, specificity and accuracy of ¹⁸F-FDG and ¹⁸F-FCH in the gliomas grading, compare theSUVmax and L/WM of both imaging tracers in each grade gliomas, calculated the correlation between semi-quantitative indicators and Ki-67 index fortwo tracers respectively, and to compare the semi-quantitative indicators change of delay and normal phasein ¹⁸F-FCH imaging. Statistical analysis using SPSS 21.0 software, P <0.05 was considered statistically significant. Result?1? Pathology and follow-up results of 33 patients, 28 cases confirmed of gliomas: the number of grade ?,? and ? were9,8 and11 cases,respectively; 4 cases of non-glioma lesions: one case of grade ? meningioma,one case of cerebral gliosis, inflammation in one case, one follow-up was benign calcified lesions, and one with white matter demyelination, respectively.?2? Visualanalysis: in distinction between high-grade and low-grade gliomas, ¹⁸F-FDG and ¹⁸F-FCH sensitivity are as follows: 89.47% and 100%, specificity of 88.89% and 88.89%, accuracy of 89.28% and 96.30%.?3? Semi-quantitative analysis of ¹⁸F-FDG imaging in each grade gliomas SUVmax are greater than ¹⁸F-FCH, the differences were statistically significant?P <0.05?. The L/WMof¹⁸F-FCH imagingwere higher than ¹⁸F-FDG group in each grade gliomas. The SUVmax and the L/WM of both tracers were significant differences between HGG and LGG. There were significant differences in the grade ? and ? gliomas?P <0.05? by the ¹⁸F-FCH imaginganalysis. The concentration of both tracersin gliomas correlated with tumor grade but with not the volume. ¹⁸F-FDG and ¹⁸F-FCH semi-quantitative parameters SUVmax and L/WM werepositive correlated with Ki-67 index.?4? The SUVmax of HGGin delay phase ¹⁸F-FCH PET/CT imaging were higher compared with normal phase, in grade ? gliomas the SUVmax was significantly higher than normal phase?P=0.013?; L/WM values increased in delay phase, but the difference was not statistically significant. Conclusion?1? ¹⁸F-FDGand¹⁸F-FCH PET/CTvisual analysishas a highvalueto distinguish high-gradeandlow-grade gliomas.?2? Semi-quantitative analysis, ¹⁸F-FDG uptakes was more than¹⁸F-FCH in each grade glioma, butthe contrast of¹⁸F-FCHimagingwere better than¹⁸F-FDG.Both tracers can distinguish high-gradefromlow-grade gliomas.It haspotential value that¹⁸F-FCH metabolic parameters to distinguish ? and ? grade gliomas.The concentration of both tracersin gliomas correlated with tumor grade but with not the volume. ¹⁸F-FDG and ¹⁸F-FCH semi-quantitative parameters were positive associated with Ki-67 index.?3? The uptake of ¹⁸F-FCH in delay phase was higher inhigh-grade gliomas than normal phase, particularly in grade ?; the increased concentration of ¹⁸F-FCH in delayed phase considered as a high degree of malignancy, it needs a further study.