The Research Value Of Gemstone Spectral CT In The Diagnosis For Bone Non-union

Objective:Along with the progressing development of societal development, four-limb fractures caused by high-energy violent force such as traffic injuries and falling are now increasing rapidly.Such severe postoperative complications as bone non-union is alsoincreased because of the increasing of surgical treatment,the incident rate has reached 5-10% statistically. At present, the definition of bone non-union is ambiguous,diagnostic criteria and options of therapeutic method had always been the problems facing orthopedic surgeons.This study was designed to research on the value of HDCT in the diagnosis of bone non-union through gemstone spectral CT HD750(HDCT) scan on patients suspiciously diagnosed as delayed union or bone non-union and images and data post-processing with comparative analysis.Methods: To retrospectively research 27 cases of patients, in the admission to orthopedic department of the first affiliated hospital to Dalian Medical University, from Nov. 2011 to Jan. 2015 diagnosed as delayed union or bone non-union through HDCT scan and 3D re-constructive information, 19 cases of which are male,8 female, aging from 19 to 82, 48.3±16.6 on average.The period of time from post-operation to reexamined in our hospital is 4 to 108 months, 19.4±24.1 on average. The primary injury mechanism: 12 cases of tumbling, 8 cases of traffic injuries, 3 cases of falling and 4 cases of other forms.Fixations: 16 cases of plating,7 cases of intramedullary nailing,3 cases of external fixations and one case of cannulated screw.Fracture spot: 15 cases of femural fracture, 9 cases of tibial fracture and 3 cases of other spot fracture. Infectious bone non-union(clinicaldiagnosis of chronic osteomyelitis) have 3 cases, non-infectious bone non-union have 24 cases. The proliferative bone non-union have 5 cases, there are 13 cases of ischemic bone non-union, atrophic bone non-union have 5 cases.Bone malunion have 1 case. By observations during the operation, the necrotic bone tissue and normal bone tissue were chosen as Region Of Interest in the HDCT post-processing work station GE AW4.5, and analyzed by GSI Viewer software,to measure the calcium( water) concentration, and then construct the corresponding ROI spectral curve and compare the difference bewteen calcium( water)concentration and spectral curve.Through collecting X-ray and HDCT images,bone non-union was scored to perform Kappa analysis and decided final diagnosis by two groups of clinicians(each group includes two experienced clinicians),and “Golden Standard ” was assessed during the operation to obtain diagnosis testing result(sensitivity and positive predictive value) on the basis of X-ray and HDCT images.Results:The fracture necrotic bone tissue and adjacent normal of bone calcium(water) density value is not accord with normal distribution and homogeneity of variance,by Mann-Whitney rank-sum test,the results show that Z=-3.868,P= 0.00< 0.05,shows that there is significant difference between the two sets of data,which shows that the fracture end sclerotic bone calcium(water) higher than that of the adjacent normal bone calcium(water) density value.The difference between the energy spectrum results show significant difference between the two groups showed that the average CT value, fracture bone sclerosis CT value is higher than the adjacent normal bone CT value.The results from Kappa analysis:(1)Kappa analysis based on X-rayed images: It has shown a consistency on diagnostic results after two groups of surgeons observed AP and lateral X-rayed(AP:K=0.664, Lateral:K=0.669),but to make a comprehension of two X-rayed results that whether there is an incidence of non-union or not,kappa = 0.419,which shows only a moderate consistency.(2) based on kappa HDCT image analysis results: Observations from the two groups of surgeons are exactly the same, the observation on HDCT coronal image for diagnosis of fracture nonunion patients accounted for 92.6%(25 / 27), the observation on sagittal plane for the diagnosis of fracture nonunion patients accounted for 96.3%(26 / 27), Through HDCT three-dimensional reconstruction, 22 cases of patients can be diagnosed as nonunion of fractures, accounting for 81.5%(22 / 27).The results from statistic evaluations on diagnostic experiments:(1) To integrate X-rayed images by two groups of surgeons, a consensus has been made to diagnose for 24 patients with nonunion of fracture, 88.9%(24 / 27), P = 88.9%(indicating the prior probability of X-ray diagnosis was 88.9%) were calculated to observe the X-ray diagnosis sensitivity of SE = 0.8800 ± 0.0650, showing the judgement that the probability of a positive result is about 88%, the positive predictive value of PV+ = 0.8757, that is to judge the positive results of the accurate rate was 87.6%, showing the positive diagnosis results of probability is low, the possibility of diagnostic errors is larger, and the judgment of positive results accuracy rate is relatively low.(2) To integrate the information from HDCT scanning and three-dimensional reconstruction image and two groups of surgeons, a consensus on diagnosis has been made fracture healing in 26 patients, accounting for 96.3%(26 / 27), P = 96.3%(said prior probability of HDCT patient image diagnosis was 96.3%). Calculation for observations through HDCT image indicates diagnostic sensitivity of SE = 0.9600 ± 0.0392,which assesses the probability of positive results about 96%, reaching 99.92%, the positive predictive value of PV+ = 0.9615, showing that positive results of accuracy is up to 96.15%, indicating that the positive diagnostic power can be strong, i.e., the possibility of diagnostic errors is quite small and the accuracy of positive results is relatively high.Conclusion:Through metal artifact reduction system, maximum intensity projection,volume reconstruction,multiple planar reconstruction and monochromatic energy images etc.Gemstone spectral CT, compared to ordinary X-ray,general CT and other images, could be more effective in the diagnosis of bone non-unions,it can be more accurate,clear and intuitively reflect bone healing within the fracture site,even itcan help to determine the subsequent treatments.As for those patients who can’t be precisely diagnosed through images from observations,the diagnosis to judge whether fracture is non-union or not should be measured by Gem spectral CT statistics combined with the measurement upon CT values and characteristics of HDCT including the energy spectrum curve and calcium(water)concentration.