| Objective:To investigate the value of virtual monoenergetic imaging(VMI)with dual-energy CT(DECT)in the image quality optimization and stenosis evaluation of CT angiography(CTA)in head and neck.Methods:Forty patients underwent dual-energy CT head and neck CTA examination.The images of the linearblended 120 k Vp,non-linear blending and virtual monoenergetic reconstruction were obtained after post-processing.All attenuation and SD values of the common carotid artery(CCA),internal carotid artery(ICA),middle cerebral artery(MCA)and basilar artery(BA)were obtained within the same ROI.CNR for each artery were calculated using the formulas.Quantitatively analyze the objective image quality of the linearblended 120 k Vp group,the non-linear blending group and the VMI group on the head and neck CTA images,and find the VMI series with the highest CNR;Under the premise of the best objective image quality of VMI,qualitatively evaluate the difference in subjective scores between the linearblended 120 k Vp group and the non-linear blending group on the head and neck CTA images;Under the premise of the best objective image quality of VMI,compare it with the linearblended 120 k Vp group and the non-linear blending group for the differences in the stenosis assessment of the carotid bifurcation and siphon,and then the statistical analysis was performed.Results:1.In terms of quantitative image analysis,among the 4 groups of arteries measured,the highest CNR value of the VMI series appeared at 60 ke V;The difference in the attenuation of the linearblended 120 k Vp,non-linear blending and 60ke V VMI groups was statistically significant(P<0.001).In the 60 ke V VMI and non-linear blending groups,the arterial attenuation of the 4 groups were significantly greater than the linearblended 120 k Vp group(P<0.05),and the attenuation of the non-linear blending group was obviously lower than that of the 60 ke V VMI group(P<0.05);The CNR of the linearblended 120 k Vp,non-linear blending and 60 ke V VMI groups were statistically different(P<0.001).In the 60 ke V VMI and non-linear blending groups,the CNR of the 4 group arteries were significantly greater than the linearblended 120 k Vp group(P<0.05);In the 60 ke V VMI and non-linear blending groups,the CNR of the CCA and ICA were not statistically different(P>0.05);In the non-linear blending group,the CNR of the MCA and BA were greater than 60 ke V VMI group(P<0.05).2.In terms of qualitative image analysis,the subjective scores of the two observers for linearblended 120 k Vp,non-linear blending and 60 ke V VMI images quality are very consistent(k=0.862,P<0.001);The difference of subjective image quality scores among the three reconstruction methods was obviously significant(X~2=156.10,P<0.001).The subjective scores of 60 ke V VMI and non-linear blending images were better than those of the linearblended 120 k Vp group(Z=-8.17、Z=-8.11,P<0.001).However,no obviously significant difference in subjective scores between the two(Z=-1.73,P=0.083);The difference of diagnostic rate among the three reconstruction methods was obviously significant(X~2=107.75,P<0.001).The diagnostic rate of 60 ke V VMI and non-linear blending images were better than those of the linearblended 120 k Vp group(Z=-7.07、Z=-6.96,P<0.001).However,no obviously significant difference in diagnostic rate between the two(Z=-1.09,P=0.276);The difference of the excellence rate of the image among the three reconstruction methods was obviously significant(X~2=71.35,P<0.001).The excellence rate of 60 ke V VMI and non-linear blending images were better than those of the linearblended 120 k Vp group(Z=-6.33、Z=-6.25,P<0.001).However,no obviously significant difference in the excellence rate of the image between the two(Z=-5.78,P=0.564);3.In terms of stenosis assessment,no obviously difference was found among the reconstruction methods of the three groups in terms of the detection and grading of stenosis of the carotid bifurcation(P=1.00),and the diagnosis of stenosis among the two observers was consistent(k=0.891,P<0.001);No obviously difference was found among the reconstruction methods of the three groups in terms of the detection and grading of stenosis of the carotid siphon(P=1.00),and the diagnosis of stenosis among the two observers was consistent(k=0.828,P<0.001).Summary:1.60 ke V VMI provided better subjective and objective image quality for the evaluation of carotid and intracranial arteries,for the display of intracranial arteries,non-linear blending technology is better than VMI technology.2.The subjective image quality of 60 ke V VMI and non-linear blending images is better than that of the linearblended 120 k Vp group,and the diagnostic rate and excellence rate are also significantly improved,but the subjective score difference between the two is not obvious. |
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