The Application Value Of The Third Generation Dual-source Dual-Energy CT In The Display And Evaluation Of Osteogenic Bone Metastases Of Vertebral Bodies

Objective:To explore the optimal single energy level of the third generation Dual-source dual-energy CT in displaying vertebral osteogenic bone metastases and the clinical value of virtual decalcification bone marrow imaging in evaluating vertebral osteogenic bone metastases.Materials and Methods:The vertebral bone metastasis of malignant tumor patients confirmed by clinical pathology was analyzed retrospectively,all patients underwent dual-source dual-energy CT imaging of chest and/or abdomen and ⁹⁹TC^m-MDP whole-body bone imaging at the same time.Histopathological biopsy or clinical follow-up were used as diagnostic criteria,osteogenic bone metastases were confirmed in vertebral bodies.Excluding patients with trauma,surgery or other pathological bone diseases.Firstly,the Mixed 0.5linear fusion image（referred to as"fused image"）and 40-140 keV single energy image（interval 10KeV）are obtained by CT scanning,two CT imaging physicians（reviewers 1and 2）independently selected high density lesions of vertebral body on the fusion image by double blind method.All high-density lesions missed by the two reviewers were taken as research objects,The signal to noise ratio（SNR）and contrast-to-noise ratio（CNR）of the fused image and each single-energy image are calculated respectively,and the SNR and CNR between each linear fused image and single-energy and each single-energy image are tested and compared by paired sample T test;According to the above results,the 40KeV and 60KeV images were reviewed by the same two doctors,and all high-density lesions of the vertebral body on the linear fusion image were reviewed again（each review interval was 3 weeks）,and corresponding scores were made（Scoring criteria:0 for positive non-osteogenic metastasis,1 for suspected osteogenic metastasis,2for high possibility of osteogenic metastasis,and 3 for confirmed osteogenic bone metastasis）,pearson chi-square test was used to compare the detection rate of high density lesions on different energy images of the two reviewers.Weighted Kappa analysis was used to examine the consistency of subjective scores of osteogenic bone metastases of vertebral bodies between the two reviewers on 40KeV,60KeV images and Mixed 0.5 linear fusion images.Secondly,selecting a bone marrow program to obtain a virtual noncalcium（VNCa）bone marrow imaging map,the other two CT imaging physicians（reviewers 3 and 4）read the films blindly,while the two nuclear medicine physicians independently judge the whole body bone imaging images,taking all vertebral bodies within the dual-source dual-energy CT scanning range as research objects,respectively calculate the accuracy,specificity,sensitivity,positive predictive value and negative predictive value of whole body bone imaging,conventional CT（i.e.Mixed0.5linear fusion image）and bone marrow imaging in the diagnosis of vertebral osteogenic bone metastases,and perform X2 test analysis to compare the diagnostic efficacy of the three different examination methods in vertebral osteogenic bone metastases;At the same time,bone marrow density（CT value）was measured on VNCa images.T test was used to compare the bone marrow CT value of vertebral metastases with that of normal vertebral bodies.ROC curve analysis was used to test bone marrow CT value and subjective score.All statistical results showed that p<0.05 was statistically significant.Results:1.The SNR of single energy images of 40KeV,50KeV,60KeV and 70KeV is higher than that of fused images,of which the SNR of single energy images of 60KeV is the highest,with significant difference with other energy images（p<0.05）;50KeV followed,with significant difference in SNR with 70KeV energy images（p<0.05）,but no significant difference in SNR among other energy images（p>0.05）.The CNR of40KeV,50KeV and 60KeV single energy images is higher than that of fused images,of which the CNR of 60KeV single energy images is the highest,with statistical difference between 50KeV single energy images and fused images（p<0.05）,and with no statistical difference between 40KeV single energy images（p>0.05）.2.On the same energy images,there was no significant difference in the detection rate of high density lesions between the two reviewers（p>0.05）;Compare that detection rate of self focus of two reviewers of different energy image,the detection rate of lesions in 60KeV single energy images was higher than that in fusion images,and the difference was statistically significant（P<0.05）.Kappa consistency analysis:the two reviewers had poor consistency in subjective scores of fused images（Kappa=0.13）,good consistency in subjective scores of 40KeV images（Kappa=0.73）,and very good consistency in subjective scores of 60KeV images（Kappa=0.80）.3.48 patients with 598 vertebral bodies,168 vertebral bodies with high density lesions were found,135 vertebral bodies diagnosed as osteogenic bone metastases.⁹⁹TC^m-MDP whole body bone imaging was diagnosed in 127 cases,conventional CT was diagnosed in 119 cases,bone marrow imaging was diagnosed in 129 cases.The bone marrow density of the metastatic focus of the diseased vertebral body is lower than that of the normal vertebral body（-588.96±332.37）HU vs（-55.03±75.62）HU,（P<0.01）.The AUC of bone marrow density was 0.99 with a cut-off value of-119.6 HU.Conclusion:1.Compared with Mixed0.5 fusion image,60KeV single energy image improves image quality and lesion display contrast;The detection rate of vertebral high density lesions is the highest on 60KeV single energy images,and the subjective scores of the two reviewers with different clinical experiences have good consistency on 60KeV single energy images.Research shows that 60KeV is the best single energy level.2.The third generation of dual-source dual-energy CT virtual decalcification bone marrow imaging can be used to evaluate vertebral osteogenic bone metastases,which is helpful to improve the diagnostic efficiency of CT for vertebral osteogenic bone metastases.