The Clinical Value Of 99m Tc-MDP Whole Body Bone Imaging And Local SPECT/CT Tomography In The Diagnosis Of Debilitating Fractures

Part I Features of Insufficiency Fracture on Whole-body Bone Scan and SPECT/CTObjective:The clinical manifestation of insufficiency fracture is lack of specificity,and is easy to be misdiagnosed.To investigate the imaging characteristics on ^<sup>99m9m Tc-MDP whole-body scan and local SPECT/CT axial imaging of insufficiency fracture,improve the imaging understanding and diagnostic ability of insufficiency fracture.Methods:Thirty patients?10 males,20 females,age ranged 48⁸6 years,average age 68.8 years,median age 71years?with IF proved by imaging diagnosis and follow-up in the Affiliated Hospital of Southwest Medical University from June 2015 to June 2017 were enrolled.^99mTc-MDP whole-body bone scan and local SPECT/CT axial images of all the patients were analyzed retrospectively.Results:A total of 78 lesions were detected in 30 patients,of which 66.7%?20/30?were single bone lesion,and 33.3%?10/30?were multiple bone lesions.?1?Ribs:Twenty-one fractures rib were detected in 6 patients,including 20 fractures in the anterior/lateral of5th-9th rib,and 1 in the right posterior 12th rib.Among the 21 fractures,14presented as short linear intense activity perpendicular to the ribs,whereas 7 as nodular accumulation.The fracture lines mainly were vertical or oblique.In addition to no displacements or mild displacements,a small amount of callus could be observed.Moreover,5 fractures showed cortical distortion,and 6 had soft tissue swelling.?2?Spine:Seventeen spinal fractures were detected in 13patients,including 5 fractures in the thoracic spine and 12 in the lumbar spine.Among the 13 patients,9 cases presented as single and 4 as multiple.All lesions manifested short,horizontal banded activity,which lower than the height of normal vertebral body.On the CT,the spinal fractures is manifested in varying degrees of collapse,flattening,wedge-shaped or"fish-vertebral"-like changes in the vertebral bodies.Slight or unconspicuous rupture of the cortical bone,enlargement of the anteroposterior diameter,and banded sclerosis in the in the upper edge or middle of vertebral body could be observed,among which5 fractures had soft tissue mild swelling.?3?Pelvis:twenty-five fractures were detected in 11 patients including 10 fractures in the sacrum,13 in the pubis ramus and 2 in the ilium).in the 10 cases of sacral fractures,3 cases were manifested in a vertical intense activity in the unilateral sacral ala which parallel to the sacroiliac joint,7 caseswere characterized by bilateral vertical banded intense activity in both sacral ala which parallel to the sacroiliac joint and a horizontal banded intense activity in the body of the sacrum perpendicular to the sacroiliac joint,of which 5 cases presented as butterfly shape,2 as bowing.On the CT,both sacral ala and the body of the sacrum p respectively represented as the vertical or oblique fracture line of low density and/or sclerosis.The irregular fracture line is serrated in shape,and there is discontinuity,slight dislocation of the cortical bone and a few free bone fragments in the anterior sacral wing.Moreover,6 cases of pubic fracture presented as spindle-shaped intense activity on the involved site,corresponding to the?site of?rupture and dislocation of the cortical bone,free bone fragments and a small amount of callus in the pubic ramus with the surrounding soft tissue spindle-shaped swelling.1 case of iliac fracture showed banded intense activity in the iliac wing parallel to the sacroiliac joint,corresponding to the oblique banded sclerosis roughly parallel to the sacroiliac joint.?4?Lower extremities: Fifteen fractures were detected in 15 patients,of which all were single bone lesion.Among 15 patients,9 cases presented as banded intense activity,whereas 6 as nodular accumulation.Some lesions manifested varying degrees of bone sclerosis with horizontal or oblique sclerotic lines,including 4 lesions in the femur,3 in fibula,2 in calcaneus and 1 metatarsus.The other lesions manifested horizontal or oblique fracture line of low density with or without periosteal hyperplasia and formation of callus,including 2 lesions in tibia and 2in fibula.One femoral fracture was manifested in subarticular collapse and subarticular osteosclerosis of the lateral condyle of the femur.All of the 30cases presented osteoporosis in different degrees.Neither bone destruction nor soft mass was detected.Conclusion:The features of insufficient fracture were somewhat specific on the ^99mTc-MDP whole-body scan and the SPECT/CT axial images,which were significant both in the early diagnosis and differential diagnosis of insufficiency fracture.Part II The clinical value of ⁹⁹ m Tc-MDP whole body bone scan combined with SPECT/CT for diagnosing sacral insufficiency fractureObjective: Pelvis,especially the sacrum is the most common site of insufficiency fracture?IF?.The main purpose of our study is to compare the clinical value among CT,MRI,⁹⁹ m Tc-MDP whole-body bone scan and SPECT/CT for diagnosing sacrum insufficiency fracture.Methods : Our study retrospectively analyzed 55 patients?14 males,41 females,age ranged 46⁹1years,average age 70.6 years,median age 73 years?with highly suspected sacrum insufficiency fracture at affiliated hospital of southwest medical university from June 2015 to June 2017.all participates underwent further CT,MRI,whole body bone scan and SPECT/CT.Definitive diagnosis were based on clinical information,imaging features and follow-up.Statistical analyses were made to evaluate the diagnostic conformance between definitive diagnosis and the imaging diagnosis.Mc Nemar's test was performed on differences among CT,MRI and bone scan.Receiver operating characteristic analysis was used to compare the diagnostic value among CT,MRI and bone scan.Results:31 of 55 patients were finally diagnosed as sacrum insufficiency fracture.in these 31 patients,21 cases?67.7%?located at bilateral sacral wings,7?22.6%?cases located at unilateral sacral wing while 3 cases?10.7%?located at only the body of sacral vertebrae.14 cases?66.7%?of the bilateral sacral wings fracture occurred with vertebral body fracture while 4 cases?57.1%?of the unilateral sacral wings fracture occurred with vertebral body fracture.different degree of osteoporosis could be seen in all patients.of the 31 patients,there existed no obvious fracture line in 6 cases,only focal hyperostosis or osteosclerosis in two cases.another 23 cases showed fracture as longitudinal fracture line at sacral wing or laterigrade fracture line at vertebral body.the fracture line revealed as low-density line or sclerosis region.there could exist cortical fracture,mild malposition and a few dissociative bone chips at the edge of sacral wing or not.these lesions could reveal as focal or diffuse low or slightly low intensity on T1 WI while asymmetry high or slightly high intensity or heterogeneous intensity on T2 WI.all lesions showed obvious high intensity on T2-SPAIR that reflected different degree of edema while 6 cases of them showed linear low intensity on all scan serials at the abnormal intensity region.another one case showed effusion in the fracture region.the region with increased uptake on SPECT/CT conflicted with the fracture region.6 cases only showed abnormal radiotracer uptake without obvious fracture line or sclerosis region on CT.the14 cases with bilateral sacral wings and vertebral body simutaneous involvement showed distinctive "H"-like,"butterfly"-like or "arch"-like increased uptake on bone scan.the sensitivity,specificity,accuracy,positive predictive value and negative predictive value of CT for diagnosing IF were74.2%,87.5%,80%,88.5% and 72.4%,respectively.for MRI,these value were80.6%,91.7%,85.5%,92.6% and 78.6%,respectively.while for bone scan,these value were 100%,83.3%,92.7%,88.6% and 100%,respectively.the area under the ROC curve?AUC?of CT,MRI and bone scan for diagnosing IF were0.808±0.061?95% CI,0.688 0.929?,0.862±0.054?95% CI,0.757 0.967?,0.917±0.046?95% CI,0.816¹?,respectively.there were statistical significance between bone scan and CT?P=0.004?and between bone scan and MRI?P=0.039?for diagnosing IF.however,the difference between CT and MRI for diagnosing IF was not statistically significant?P=1?.Conclusion:⁹⁹mTc-MDP whole-body bone scan combined with SPECT/CT had more clinical value for diagnosing sacral IF than CT and MRI.