The Study Of Influences Of 2D And 3D DHTC On Nuclear Imaging

Objectives:1.Through model experiment,to determine the differences in imaging resolutions of 2D and 3D acquisition modes in Discovery-VH imaging system,and to understand the conformity of detection abilities in different positions of the detection visions.2.Through analysis of experimental data,to study whether there are any differences in the imaging results acquired from 2D and 3D modes by using Lesion/Background(L/B) ratios(a commonly used semi-quantitative index) in the Discovery-VH DHTC imaging system,and to explore the relationship between L/B ratios and radioactive concentrations and lesion sizes obtained by 3D mode,and to compare similarities between these results and the data from 2D mode.Based on 2D and 3D modes' data,try to optimize the acquisition time and minimize the usage of radioactive dosage for 3D acquisition mode.3.Experimental results will be implemented for preliminary clinical case studies,in order to guide clinical applications,to enhance efficiency of DHTC imaging system,and to improve clinical potentials of DHTC imaging.Materials and Methods:1.After preparation of ¹⁸F-FDG line source,quality control procedures in Discovery-VH DHTC imaging system was applied,then line sources were acquired after installation of the 2D and 3D devices respectively,finally, systemic resolutions of 2D and 3D modes were obtained.2.By using cylinder phantoms with homogeneous areas and cylindrical positive areas with different diameters,positioning phantoms with positive areas upwards,and then preparing different concentrations of radioactive drugs,model acquisition and data processing were carried out in 2D and 3D Discovery-VH DHTC imaging system.Imaging results under different initial conditions were obtained finally.Then visual judgments, L/B ratios,t tests,variance analyses,correlation and regression statistical analyses were done.We studied the relationships between phantom detection abilities,image qualities and radioactive concentration ratios,cylinder diameter in 2D and 3D mode. After that,we also compared phantom detection abilities and image qualities in 2D and 3D mode,and we then assessed the increasing folds in 3D mode compared with 2D mode under the same circumstances.3.6 cases of ¹⁸F-FDG tumor imaging by 2D and 3D mode were studied,L/B ratios in imaging data were analyzed and imaging results were compared under 2D and 3D mode.Results:1.There were no significant differences in systemic intrinsic spatial resolutions between 2D and 3D modes(P＞0.05).2.Under the condition of the same radioactive concentration ratios,central and marginal areas showed almost the same visually analytical classification in three acquisition time periods in 2D and 3D mode. Positive and negative judgments were the same.However,in case of low radioactive concentration ratios,visual analyses were different.3.There were no significant differences in L/B ratios in central areas between 2D and 3D modes under different radioactive concentration ratios in three acquisition time periods(P＞0.05).There were significant differences in L/B ratios in marginal areas between 2D and 3D modes under different radioactive concentration ratios in three acquisition time periods(P＜0.01).Radioactive concentration ratios and phantom cylindrical sizes significantly influenced the L/B ratios in 3D mode,which was in consistent with the results of 2D mode.4.Under 3D mode,positive correlations were found between L/B ratios and radioactive concentration ratios(P＜0.01) and linear regression equations were y=0.278+0.378x,y=0.263+0.262x,and y=0.540+0.166x for cylindrical diameters of 1.5cm,1.0cm,and 0.5cm,respectively.Similarly,positive correlations were found between L/B ratios and cylindrical diameters(P＜0.01) and linear regression equations were y=1.554+0.286x,y=0.829+0.199x,and y=1.012+0.074x for radioactive concentration ratios of 15:1,10:1,and 5:1,respectively.5.After total counts of coincidence detections were calculated,attenuation corrections were processed,the detection efficiency was 4 times higher in 3D mode than 2D mode.6. Clinical case studies showed:3D mode had the same imaging results with 2D mode for cervical and thoracic lesions,L/B ratios were roughly the same between these two modes,however,differences were much greater in abdominal lesions between these two modes.Conclusions:3D DHTC imaging mode can enhance detection efficiency,while imaging resolution and contrast were not significantly different from the traditional 2D mode.In clinical applications,3D DHTC imaging mode can decrease half of the drug dosage,and shorten acquisition time.Therefore,it is much more appropriate to adopt 3D DHTC imaging mode for ¹⁸F-FDG imaging of thoracic lesions.