The Influence Of CT Attenuation Correction On IQ-SPECT Myocardial Perfusion Imaging

Objective:To evaluate the impact of CT attenuation correction(AC)on IQ-SPECT myocardial perfusion imaging(MPI).Methods:Twenty five patients(16 males and 8 females)who underwent IQ-SPECT with CTAC and LEHR-SPECT with CTAC on the same day were enrolled in this study.The visual analysis,myocardial uptake and perfusion score of 5 myocardial segment(apical,anterior,lateral,inferior and septal walls)were compared before and after AC,IQ-NOAC and coordination.The original images of MPI and CT were analyzed,and the changes of X-axis,Y-axis and Z-axis after IQ-AC and IQ-coordination were compared.Results:1.Comparison of myocardial perfusion results between IQ group and LEHR group:Two nuclear medicine doctors were double-blind,7 cases were normal in IQ group and18 cases were abnormal patients;9 cases were normal in LEHR group and 16 cases were abnormal patients.There was no significant difference in myocardial perfusion between the two groups(?~2=0.368,p=0.544);the diagnosis was completely consistent by two nuclear medicine physicians.2.Visual analysis of AC on IQ and LEHR groups:15 patients'septal wall(60%,15/25)and 3 patients'(12%,3/25)anterior wall were weakened after AC.Only 5Patients'(20%,5/25)anterior wall were reduced in the LEHR group.The sparse rate of myocardial segments of the IQ group was 72%(15+3/25),which was much higher than that of the LEHR group by 20%(5/25),(?~2=13.61,p<0.001).3.Due to the high sparse rate myocardial segments of IQ,we analyzed the original image and manual reregistration the MPI and CT images.After re-coordination,the distribution of apical in the IQ group was sparse(16%,4/25),and the difference between the LEHR group(20%,5/25)was not statistically significant(?~2=0.136,p=0.713).4.The effect of AC on the myocardial uptake ratio(%)of IQ group and LEHR group:compared with the IQ-NOAC,there was a significantly decrease in the myocardial uptake among the apical(p=0.001),anterior wall(p<0.001)and septal wall(p<0.001)after AC;While the increased myocardial uptake were observed in septal wall(p<0.001)and inferior wall(p<0.001)of LEHR group after AC.After IQ registration,compared with NOAC,inferior wall(t=-5.86,p<0.001),septal wall(t=2.46,p=0.022)uptake values were observably increased.5.The influence of AC on the perfusion scores of IQ group and LEHR group:for the IQ group,the score of septal wall(p<0.001)increased after AC,but no differences were noticed in LEHR group before and after AC.Compared with NOAC after IQ coordination,the lateral were different(t=2.34,p=0.029),and the score was reduced after coordination.6.Changes in the x-axis,y-axis,and z-axis after IQ-AC and manual coordination:IQ-AC and post-coordinate x-axis(58.50±22.13 vs 11.62±2.70,p<0.001),y-axis(-3.33±7.35 vs 0.99±4.30,p=0.03)and z-axis(-15.10±13.25 vs 1.60±3.41,p<0.001),with the x-axis shift to the left,with an average of(46.87±2.50)mm,The y-axis direction is shifted back wards,with an average amplitude of(4.32±8.47)mm and a down ward shift of the z-axis direction(16.70±13.96)mm.Conclusions:1.The distribution of inferior and septal walls were supplemented by LEHR-SPECT AC.After AC,in the IQ-SPECT group,the inferior and septal walls were not replenished,however the apical,anterior and septal were sparsely distributed,The distribution is improved.2.After analyzing the original image,the image registration is mainly caused by the x-axis direction shifting to the left,the y-axis direction backward shifting,and the z-axis direction shifting downward.The x-axis right offset is the largest,and the z-axis is lower.The offset is second,and the y-axis back offset is the slightest.