Clinical And Related Basic Study Of Low-Dose Dual Energe CT In The Diagnosis Of Anterior Cruciate Ligament Injury

Objective:1.To assess low-dose scan parameters in dual-energy computed tomography(CT)for displaying the anterior cruciate ligament.2.To explore the molecular imaging basis of "diminution sign on dual-energy colour mapping" for the diagnosis of anterior cruciate ligament injury by dual-energy CT.Materials and methods:1.Dual-energy CT scans with low and standard dose parameters,respectively,were performed in nine human knee joint specimens.Statistical analysis was performed for signal-to-noise ratios of the CT images and subjective scores.2.35 patients who received DSCT dual-energy technique examination with the low-dose parameters before the arthroscopy were analyzed and compared with the results of the MRI and arthroscopy retrospectively.3.The hydroxylysine and hydroxyproline reagents were prepared into different concentrations of solutions and mixed according to different groups.Six groups of samples with different concentrations were obtained.The samples were scanned by dual-energy CT with low-dose and standard dose parameters,and the image post-processing was carried out.The dual-energy color mapping(dual-energy staining)was observed,and the CT value of the solution and the image signal-to-noise ratio were analyzed.Measurement and statistical analysis were performed.Results:1.Comparable signal-to-noise ratios and subjective image quality scores by evaluators in dual-energy CT anterior cruciate ligament images between the low and standard-dose groups were observed.2.22 cases of anterior cruciate ligament(ACL)injury were diagnosed by dual-energy staining diminution sign,18 of which were in accordance with arthroscopy results and 4 cases were misdiagnosed.13 cases of normal ACL were diagnosed,12 of which were in accordance with arthroscopy result and 1 case was misdiagnosed.The sensibility was 94.7%,the specificity was 75.%,the positive predictive value was 81.8%and the negative predictive value was 92.3%.The value of the Kappa test procedure was 0.836(good agreement).3.In the pure hydroxylysine concentration change group and hydroxyproline concentration change group with the increase of the concentration of hydroxylysine,the brightness and brilliance of the dual-energy color mapping of each test tube solution increased,and the CT value of the solution also increased.4.In the hydroxylysine and hydroxyproline concentration increasing synchronously group,with the increase of the concentration of the two kinds of amino acids,the brightness and brilliance of the dual-energy color mapping of each test tube solution increased,and the CT value of the solution also increased.5.In the group of reverse increase and decrease of hydroxylysine and hydroxyproline concentration(increase of hydroxylysine and decrease of hydroxyproline),the brightness and brilliance of the dual-energy color mapping of each test tube solution increased with the increase of the concentration of hydroxylysine,,and the CT value of the solution also increased.6.In the mixed solution group with increasing hydroxylysine concentration and fixed hydroxyproline concentration,the brightness and brilliance of the dual-energy color mapping of each test tube solution increased with the increase of the concentration of hydroxylysine,and the CT value of the solution also increased.7.In the mixed solution group with increasing hydroxyproline concentration and fixed hydroxylysine concentration,there was no significant change in the brightness and brilliance of the dual-energy color mapping of each test tube solution,and there was also no significant change in the CT value of the solution.Conclusion:1.Low-dose scan parameters do not compromise the outcomes of anterior cruciate ligament imaging and the diagnosis of the ACL injury.At the same time,it can effectively reduce the radiation dose of CT scan.2.The color mapping(dual-energy staining)of the dual-energy CT imaging in"tendon" mode is related to hydroxylysine and hydroxyproline.3.The changes of the concentration of hydroxylysine and/or hydroxyproline affect the degree of dual-energy color mapping,and there is a positive correlation between them.4.The two amino acids play different roles in dual-energy color mapping.Hydroxylysine plays the main role in dual-energy color mapping,hydroxyproline plays the minor role.The degree of dual-energy color mapping depends more on the change of hydroxylysine content.5.The change of dual-energy color mapping degree is accompanied by the change of CT value,and they are also positively correlated.