Distance mapping of the foot and ankle joints using weightbearing CT: The cavovarus configuration

IntroductionThe goal of this study was to characterize the abnormal joint surface interaction at the ankle, hindfoot and midfoot joints of the cavovarus foot using distance mapping on weightbearing computed tomography (WBCT) images by comparing a series of cavovarus feet to a series of normally-aligned feet.MethodsIn this case-control study, ten feet (10 patients) with asymptomatic cavovarus shape (cases; N = 10) were compared to 10 matched-paired (by age, gender and body mass index) normally-aligned feet (10 patients) (controls; N = 10). Three-dimensional models were produced from the images and distance maps representing joint surface configuration were generated for the ankle, hindfoot and midfoot joints. The distance maps for each joint were then compared between the two groups and between regions in the same group.ResultsIn the cavovarus group there was a significant increase in surface-to-surface distance at the posterior tibiotalar joint and a reduced distance at the anterior part, together with a greater distance at the posterior half of the medial gutter. Also, a decrease in surface-to-surface distance on the anterior half of the anterior facet and an increased distance on the posterior quadrants of the posterior facet of the subtalar joint were found. At the sinus tarsi, the lateral aspect of the talonavicular joint, the naviculocuneiform and the tarsometatarsal joints there was a statistically significant increase in surface-to-surface distance in cavovarus patients as compared to controls.ConclusionDistance mapping analysis on WBCT images identified significant differences in surface-to-surface interaction at the foot and ankle joints between cavovarus and normally-aligned feet.Level of evidenceLevel III, case-control study.     

Pes cavovarus in Charcot-Marie-Tooth compared to the idiopathic cavovarus foot: A preliminary weightbearing CT analysis

BackgroundPes cavovarus is a foot deformity that can be idiopathic (I-PC) or acquired secondary to other pathology. Charcot-Marie-Tooth disease (CMT) is the most common adult cause for acquired pes cavovarus deformity (CMT-PC). The foot morphology of these distinct patient groups has not been previously investigated. The aim of this study was to assess if morphological differences exist between CMT-PC, I-PC and normal feet (controls) using weightbearing computed tomography (WBCT).MethodsA retrospective analysis of WBCT scans performed between May 2013 and June 2017 was undertaken. WBCT scans from 17 CMT-PC, 17 I-PC and 17 healthy normally-aligned control feet (age-, side-, sex- and body mass index-matched) identified from a prospectively collected database, were analysed. Eight 2-dimensional (2D) and three 3-dimensional (3D) measurements were undertaken for each foot and mean values in the three groups were compared using one-way ANOVA with the Bonferroni correction.ResultsSignificant differences were observed between CMT-PC or I-PC and controls (p < 0.05). Two-dimensional measurements were similar in CMT-PC and I-PC, except for forefoot arch angle (p = 0.04). 3D measurements (foot and ankle offset, calcaneal offset and hindfoot alignment angle) demonstrated that CMT-PC exhibited more severe hindfoot varus malalignment than I-PC (p = 0.03, 0.04 and 0.02 respectively).ConclusionsCMT-related cavovarus and idiopathic cavovarus feet are morphologically different from healthy feet, and CMT feet exhibit increased forefoot supination and hindfoot malalignment compared to idiopathic forms. The use of novel three-dimensional analysis may help highlight subtle structural differences in patients with similar foot morphology but aetiologically different pathology.Level of evidenceLevel III, retrospective comparative study.     

The Effect of Customized and Silicon Insoles on Mid- and Hindfoot in Adult Flexible Pes Planovalgus

BackgroundFlexible flat foot or pes planovalgus is a common foot deformity, and silicone and customized insole are commonly used as a non-operative treatment modality of flexible planovalgus. However, there are inadequate data and limited evidence available regarding the immediate effects of their use in midfoot and hindfoot of adults. The aim of this study is to quantify and compare the radiological parameters immediately on weightbearing with silicon and customized insoles and without them to assess the effect on midfoot and hindfoot of the flexible planovalgus in adults.MethodsA total number of 11 (8 females and 3 males) subjects with flexible pes planovalgus deformity without any other foot deformity were included in the study. Each patient was assessed three times in a random sequence without and with use of either silicon insoles or customized insole. The radiographic parameters without insole, with silicon insole, and with customized insole conditions were calculated using online available computer software Kinovea.ResultsOne-way ANOVA analysis was performed between groups (without insole, with silicone insole and with customized insole). The hindfoot parameters depicted that calcaneal inclination angle (CIA) was significant increased (P = 0.000) and talar declination angle (TDA) was significantly decreased (P = 0.003) only with the use of customized insole compared to without insole. The midfoot parameters depicted that the first metatarsal angle (FMA) and talonavicular coverage angle (TCA) were significantly lower with customized insole (P = 0.00) as compared to other two groups and significantly lower with silicone insole (P = 0.00) as compared to without insole group.ConclusionThe results imply that the compressibility of the insole material affects the forefoot and hindfoot biomechanics differently. This study concludes that silicone insole affects only the midfoot which bears 45% of bodyweight and customized insole affects both midfoot and more importantly the hindfoot which bears 55% of bodyweight.     

Extraarticular Subtalar Arthrodesis for Pes Planovalgus: An Interim Result of 50 Feet in Patients with Spastic Diplegia

Background

There are no reports of the pressure changes across the foot after extraarticular subtalar arthrodesis for a planovalgus foot deformity in cerebral palsy. This paper reviews our results of extraarticular subtalar arthrodesis using a cannulated screw and cancellous bone graft.

Methods

Fifty planovalgus feet in 30 patients with spastic diplegia were included. The mean age at the time of surgery was 9 years, and the mean follow-up period was 3 years. The radiographic, gait, and dynamic foot pressure changes after surgery were investigated.

Results

All patients showed union and no recurrence of the deformity. Correction of the abduction of the forefoot, subluxation of the talonavicular joint, and the hindfoot valgus was confirmed radiographically. However, the calcaneal pitch was not improved significantly after surgery. Peak dorsiflexion of the ankle during the stance phase was increased after surgery, and the peak plantarflexion at push off was decreased. The peak ankle plantar flexion moment and power were also decreased. Postoperative elevation of the medial longitudinal arch was expressed as a decreased relative vertical impulse of the medial midfoot and an increased relative vertical impulse (RVI) of the lateral midfoot. However, the lower than normal RVI of the 1st and 2nd metatarsal head after surgery suggested uncorrected forefoot supination. The anteroposterior and lateral paths of the center of pressure were improved postoperatively.

Conclusions

Our experience suggests that the index operation reliably corrects the hindfoot valgus in patients with spastic diplegia. Although the operation corrects the plantar flexion of the talus, it does not necessarily correct the plantarflexed calcaneus and forefoot supination. However, these findings are short-term and longer term observations will be needed.     

Retrospective chart review: Weightbearing CT scans and the measurement of the Lisfranc ligamentous complex

BackgroundLisfranc Ligamentous Complex (LLC) injuries are commonly misdiagnosed due to their unreliable projection on plain films. Weightbearing CT (WBCT) scans are a relatively new imaging modality that has not yet been utilized to establish widely referenced baseline anatomic positions.MethodsA retrospective chart review was conducted of patients who had undergone weightbearing CT of the bilateral lower extremities with one-hundred and twelve being included (56 patients). Measurements of the Lisfranc joint were collected by two independent reviewers. Uninjured symmetric anatomy was used to describe a baseline for normal anatomic variation and to evaluate for sex-based or age-related differences. These measurements were then compared against the injured side.ResultsIn patients without Lisfranc injury, the 1st metatarsal base to 2nd metatarsal base distance (Base M1-M2) was 2.7 + /? 0.7 mm; 2nd metatarsal base to medial cuneiform (M2-C1) was 3.7 + /? 0.7 mm; intercuneiform distance was 1.2 + /? 0.3 mm; and sagittal descent 12.2 + /? 5.4 mm. Patients with injury to LLC had a larger M1-M2 base distance (Δ = 0.5903, p < 0.0001) and M2-C1 interval (Δ = 1.8008, p < 0.0001) compared to uninjured side. Males had significantly higher M2-C1 (p = 0.0031), intercuneiform distance (p = 0.0039), and sagittal descent (p = 0.0008) compared to female patients. No significant differences were found between left versus right side in any of the measurements. Intercuneiform distance (p = 0.0039) was found to significantly decrease as age increased, while sagittal descent significantly increased with increased age (p = 0.0066).ConclusionWeightbearing CT has high utility in identification of Lisfranc injuries particularly when comparing injured and uninjured sides, which may be its greatest utility in defining injuries. This is evident in the excellent diagnostic ability of the M2-C1 measurement. By defining baseline anatomic measurements for Lisfranc complex parameters in our patient population, we provide normal parameters for comparison when evaluating potential subtle injuries.Level of evidenceIII     

Hindfoot alignment of adult acquired flatfoot deformity: A comparison of clinical assessment and weightbearing cone beam CT examinations

BackgroundClinical assessment of hindfoot alignment (HA) in adult acquired flatfoot deformity (AAFD) can be challenging and weightbearing (WB) cone beam CT (CBCT) may potentially better demonstrate this three-dimensional (3D) deformity. Therefore, we compared clinical and WB CBCT assessment of HA in patients with AAFD.MethodsIn this prospective study, we included 12 men and 8 women (mean age: 52.2, range: 20–88) with flexible AAFD. All subjects also underwent WB CBCT and clinical assessment of hindfoot alignment. Three fellowship-trained foot and ankle surgeons performed six hindfoot alignment measurements on the CT images. Intra- and Inter-observer reliabilities were calculated using intra-class correlation (ICC). Measurements were compared by paired T-tests, and p-values of less than 0.05 were considered significant.ResultsThe mean of clinically measured hindfoot valgus was 15.2 (95% confidence interval [CI]: 11.5–18.8) degrees. It was significantly different from the mean values of all WB CBCT measurements: Clinical Hindfoot Alignment Angle, 9.9 (CI: 8.9–11.1) degrees; Achilles tendon/Calcaneal Tuberosity Angle, 3.2 (CI: 1.3–5.0) degrees; Tibial axis/Calcaneal Tuberosity Angle, 6.1 (CI: 4.3–7.8) degrees; Tibial axis/Subtalar Joint Angle 7.0 (CI: 5.3–8.8) degrees, and Hindfoot Alignment Angle 22.8 (CI: 20.4–25.3) degrees. We found overall substantial to almost perfect intra- (ICC range: 0.87–0.97) and inter-observer agreements (ICC range: 0.51–0.88) for all WB CBCT measurements.ConclusionsUsing 3D WB CBCT can help characterize the valgus hindfoot alignment in patients with AAFD. We found the different CT measurements to be reliable and repeatable, and to significantly differ from the clinical evaluation of hindfoot valgus alignment.Level of evidence: Level II—prospective comparative study.     

Combined weightbearing CT and MRI assessment of flexible progressive collapsing foot deformity

BackgroundThe objective of this study was to evaluate the correlation between Weightbearing CT (WBCT) markers of pronounced peritalar subluxation (PTS) and MRI findings of soft tissue insufficiency in patients with flexible Progressive Collapsing Foot Deformity (PCFD). We hypothesized that significant correlation would be found.MethodsRetrospective comparative study with 54 flexible PCFD patients. WBCT and MRI variables deformity severity were evaluated, including markers of pronounced PTS, as well as soft tissue degeneration. A multiple regression analysis and partition prediction models were used to evaluate the relationship between bone alignment and soft tissue injury. P-values of less than .05 were considered significant.ResultsDegeneration of the posterior tibial tendon was significantly associated with sinus tarsi impingement (p = .04). Spring ligament degeneration correlated to subtalar joint subluxation (p = .04). Talocalcaneal interosseous ligament involvement was the only one to significantly correlate to the presence of subfibular impingement (p = .02).ConclusionOur results demonstrated that WBCT markers of pronounced deformity and PTS were significantly correlated to MRI involvement of the PTT and other important restraints such as the spring and talocalcaneal interosseus ligaments.LEVEL OF EVIDENCE: Level III, Retrospective comparative study.     

Reliability of distal tibio-fibular syndesmotic instability measurements using weightbearing and non-weightbearing cone-beam CT

BackgroundTo investigate the reliability and reproducibility of syndesmosis measurements on weightbearing (WB) cone-beam computed tomography (CBCT) images and compare them with measurements obtained using non-weightbearing (NWB) images.MethodsIn this IRB-approved, retrospective study of 5 men and 9 women with prior ankle injuries, simultaneous WB and NWB CBCT scans were taken. A set of 21 syndesmosis measurements using WB and NWB images were performed by 3 independent observers. Pearson/Spearman correlation and intra-class correlation (ICC) were used to assess intra- and inter-observer reliability, respectively.ResultsWe observed substantial to perfect intra-observer reliability (ICC = 0.72–0.99) in 20 measurements. Moderate to perfect agreement (ICC = 0.45–0.97) between observers was noted in 19 measurements.ConclusionMeasurements evaluating the distance between tibia and fibula in the axial plane 10 mm above the plafond had high intra- and inter-observer reliability. Mean posterior tibio-fibular distance, diastasis, and angular measurement were significantly different between WB and NWB images.     

足踝手术患者静脉血栓栓塞的评估与预防

静脉血栓栓塞（VTE）包括深静脉血栓（DVT）和肺栓塞（PE）。创伤及手术是VTE形成的危险因素,在血栓形成后若不能及时诊断和处理,血栓形成后遗症将长时期影响患者的生活和工作质量;少数并发肺栓塞,造成严重后果。在骨科围手术期正确认识、评估和预防VTE的发生对患者的预后非常重要。     

Automatic measurement of polyethylene modification in metal-backed artificial hip joints using three-dimensional CT

A new method has been developed for automatic measurement of polyethylene linear modification using three-dimensional CT in total hip arthroplasty (THA) and bipolar hemiarthroplasty (BHP). We obtained a three-dimensional digital image of the metal components by widening the maximum window width, adjusting the proper cutoff threshold level, and removing the metal artifact. The centric coordinates of both the metal-backed cup and the femoral head were calculated from this image. Modification was defined as a change in distance between those two points from their original interval. Phantom studies of the accuracy and reproducibility of the method indicated that the average error ranged from 0.02 to 0.12mm and the standard deviation ranged from 0.01 to 0.05mm. Clinical in vivo measurement was performed without error of computer software on 19 hips in which modification of highly cross-linked polyethylene components was significantly large.     

Subtalar arthroereisis in pediatric flexible flat foot: Functional and radiographic results with 5 years of average follow-up

The aim of this retrospective study is to evaluate the clinical-functional and radiographic results in pediatric patients with painful and disabling Flexible Flat Foot (FFF) refractory to conservative treatment who underwent percutaneous subtalar arthroereisis with a Maxwell Brancheau Arthroereisis® (MBA) implant. Patients aged 8–14 years old with a minimum follow-up of 24 months were included. A pre and postoperative radiographic evaluation was carried out analyzing Meary's angle, internal Moreau-Costa-Bartani´s angle, Talar declination angle, Calcaneal Pitch, Kite's angle, Talar-1st metatarsal angle, and Talonavicular coverage angle. In those patients with more than 5 years of follow-up, the development of subtalar osteoarthritis was evaluated. A clinical-functional evaluation was carried out using the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot rating scale. Pre and postoperative pain was evaluated using the visual analog scale (VAS). Postoperative complications were described. Fourteen patients (19 feet) met the inclusion criteria. The mean age at surgery was 12 years old with a mean follow-up of 68.26 months. All radiographic angles improved significantly. No signs of subtalar osteoarthritis were identified. The mean pre and postoperative pain according to VAS was 7.05 and 0.77 respectively. The mean pre and postoperative AOFAS was 75.42 and 97.05 respectively. One female patient had persistent pain in both feet (VAS = 4). However, she was able to do sports and daily life activities without restrictions. None of the implants needed to be removed due to intolerance or pain. Subtalar arthroereisis seems to be effective to improve the clinical-functional and radiographic parameters in moderate pediatric FFF.     

Range of motion of foot joints following total ankle replacement and subtalar fusion

BackgroundIn severe cases of ankle and subtalar arthritis, arthrodesis of the subtalar joint is performed in combination with ankle arthroplasty. In these special cases gait analysis reveals real motion at the replaced tibiotalar joint.MethodsTwenty-three patients affected by ankle and subtalar arthritis, treated either with a 3-component or a 2-component prosthesis in combination with subtalar arthrodesis, were clinically evaluated preoperatively and at a minimum of 1-year follow-up. Gait analysis was performed postoperatively using a multi-segment foot protocol. Foot kinematics were compared to corresponding data from a healthy control group.ResultsClinical scores significantly improved from preoperative to follow-up. The clinically measured passive ankle dorsiflexion/plantarflexion significantly improved at the follow-up. Patients’ normalized walking speed and stride length were significantly lower than those in control. With exception of the ankle frontal-plane motion, sagittal-plane mobility of foot joints was about 50% than that in healthy joints.ConclusionsImprovement in clinical scores was found for both prostheses. Normal spatio-temporal parameters were not restored. In these patients, fusion of the subtalar joint appeared to be compensated by larger frontal-plane motion at the tibiotalar joint.Level of evidenceLevel III- retrospective comparative study.The study was approved by the local Ethics Committee as protocol MAT (protocol registration at clinicaltrials.gov NCT03356951).     

The use of surgeon-performed ultrasound assessment in a foot and ankle clinic

BackgroundWe describe the first reported use of ultrasound examination performed by an orthopaedic surgeon in the setting of a foot and ankle clinic.MethodsThe senior author attended a course in musculoskeletal ultrasound and performed 100 examinations each checked against the results from a consultant radiologist. Records were kept of all examinations performed in the clinic over a 6-month period with results.ResultsOf the 622 patients seen, 91 had an ultrasound scan and 36 had guided injections. All patients had one hospital attendance spared, for most two. Time saved on the treatment pathway per patient was on average 6 weeks.ConclusionUltrasound assessment performed by a clinician during an outpatient clinic appointment reduces delay in treatment and cuts costs by reducing patient episodes.     

Simultaneous multi-section perfusion CT and CT angiography for the assessment of acute ischemic stroke

Summary Background. Introduction of helical computed tomography (CT) scanning has enabled rapid imaging of the vascular status by means of CT angiography and perfusion CT. By virtue of recent multi-detector technology, helical CT has the ability to perform both CT angiography and multi-section perfusion CT simultaneously. This study investigated the clinical feasibility of simultaneous assessment of perfusion CT and CT angiography in patients with acute ischemic stroke.Method. Perfusion CT and CT angiography were performed simultaneously in a series of consecutive 31 acute ischemic stroke patients. The time required for the entire processing was about 15 minutes. Contrast agent was used in a total dose of 100ml (35ml for perfusion CT and 65ml for CT angiography).Findings. Simultaneous perfusion CT scans and CT angiographies were of diagnostic quality for 29 patients (94%). In large territorial infarct patients, perfusion CT could predict all perfusion deficits of the final lesions (10 out of 10 lesions) and CT angiography could detect 9 of 10 occlusions of major cerebral arteries (90%). In patients with small lacunar or subcortical infarcts, perfusion CT could predict 9 out of 19 lesions (47.4%), and false-negative were encountered in small lesions (three patients) or in inadequate coverage of data acquisition (seven patients). Acute stage thrombolytic intervention could be carried out based on the findings, and the success of thrombolytic therapy could be demonstrated by follow-up study.Conclusions. Simultaneous perfusion CT and CT angiography is the very useful tool for the rapid and adequate diagnosis of almost all of the large territorial infarcts and some of non-territorial lacunar infarcts. It is an easy-to-perform and safe imaging technique to assess acute ischemic stroke.     

The accuracy of assessment of walking distance in the elective spinal outpatients setting

Self reported walking distance is a clinically relevant measure of function. The aim of this study was to define patient accuracy and understand factors that might influence perceived walking distance in an elective spinal outpatients setting. A prospective cohort study. 103 patients were asked to perform one test of distance estimation and 2 tests of functional distance perception using pre-measured landmarks. Standard spine specific outcomes included the patient reported claudication distance, Oswestry disability index (ODI), Low Back Outcome Score (LBOS), visual analogue score (VAS) for leg and back, and other measures. There are over-estimators and under-estimators. Overall, the accuracy to within 9.14 metres (m) (10 yards) was poor at only 5% for distance estimation and 40% for the two tests of functional distance perception. Distance: Actual distance 111 m; mean response 245 m (95% CI 176.3–314.7), Functional test 1 actual distance 29.2 m; mean response 71.7 m (95% CI 53.6–88.9) Functional test 2 actual distance 19.6 m; mean response 47.4 m (95% CI 35.02–59.95). Surprisingly patients over 60 years of age (n = 43) are twice as accurate with each test performed compared to those under 60 (n = 60) (average 70% overestimation compared to 140%; p = 0.06). Patients in social class I (n = 18) were more accurate than those in classes II–V (n = 85): There was a positive correlation between poor accuracy and increasing MZD (Pearson’s correlation coefficient 0.250; p = 0.012). ODI, LBOS and other parameters measured showed no correlation. Subjective distance perception and estimation is poor in this population. Patients over 60 and those with a professional background are more accurate but still poor.     

数字化摄影与多层螺旋CT在足踝部骨折及脱位的诊断价值比较

目的:比较数字化摄影(DR)与多层螺旋CT(MSCT)在诊断足踝部骨折及关节脱位的应用价值。方法:分析2010年8月至2012年8月收治的52例足踝部骨折及脱位患者(男37例,女15例,年龄15～49岁)的DR及MSCT资料,并与手术或出院诊断对比,比较两者诊断骨折数量、关节脱位的区别,采用R统计软件Wilcoxon符号秩检验(Wilcoxon signed rank test)进行统计学分析。结果:52例MSCT结果与术后或出院诊断结果完全相符。MSCT诊断骨折172处,DR诊断骨折98处,两者在骨折诊断中差异有统计学意义(V=1081,P<0.05);MSCT诊断关节脱位24例,DR诊断关节脱位16例,两者在关节脱位诊断中差异有统计学意义(V=21,P<0.05)。MSCT纠正DR骨折诊断定位6例。结论:MSCT对足踝部骨折及关节脱位的诊断优于DR。DR应首选2个部位的检查。当DR诊断结果不明确或与临床症状不相符时应选择MSCT及多平面重建(MPR)检查,可避免漏诊及误诊。     

Lymphoscintigraphy for sentinel node mapping using a hybrid single photon emission CT (SPECT)/CT system in oral cavity squamous cell carcinoma

BACKGROUND: We assessed the added clinical value of fused single photon emission computed tomography (SPECT) and low-dose CT images compared with planar images for sentinel node (SN) mapping in patients with oral cavity squamous cell carcinoma (SCC). METHODS: Twenty consecutive patients with newly diagnosed biopsy-proven SCC of the oral cavity were enrolled. Scintigraphy was performed using a hybrid gamma-camera/low-dose CT system. Planar images and fused SPECT/CT images were interpreted separately. All patients underwent a sentinel node biopsy (SNB) followed by a neck dissection. All SNs underwent meticulous pathologic examination and immunohistochemistry staining (cytokeratin complex) in addition to routine pathologic examinations of the neck dissection specimen. RESULTS: The sensitivity for the detection of nodal metastases was 87.5%. SPECT/CT improved SN identification and/or localization compared with planar images in 6 patients (30%). CONCLUSIONS: SPECT/CT SN mapping provides additional preoperative data of clinical relevance to SNB in patients with oral cavity SCC.     

多层螺旋CT足踝部隐匿性骨折的诊断价值

目的：通过对隐匿性骨折的诊断,提示足踝部外伤后X线检查阴性、临床高度怀疑有骨折的患者进行多层螺旋CT检查的必要性,以期减少漏诊、误诊。方法：收集2007年1月至2010年6月31例足踝部外伤病例,男18例,女13例;年龄21～67岁,平均35岁。均有明确外伤史,主要表现为足踝部疼痛,局部肿胀,压痛点固定,压痛明显,活动受限。31例X线检查均阴性,因临床高度怀疑骨折而行多层螺旋CT检查。结果：螺旋CT检查发现11例骨折,共累及17处。单发骨折6例,多发骨折5例。单发骨折中,外踝骨折1例,距骨骨折1例,足舟骨骨折1例,第5跖骨基底部骨折1例,跟骨骨折2例;多发骨折中,内、外踝骨折1例,内踝、跟骨、距骨骨折1例,距骨、足舟骨骨折1例,足第1、2楔骨骨折1例,第2、3跖骨基底部骨折1例。结论：足踝部外伤后X线片检查阴性、临床高度怀疑有骨折的患者进行多层螺旋CT检查,可明显提高隐匿性骨折的检出率,为临床治疗及司法鉴定提供可靠的影像学依据,具有重要的应用价值。     

多层螺旋CT在骨关节疾病诊断中的应用价值

目的探讨多层螺旋CT二维和三维重建技术在骨关节疾病诊断中的应用价值。方法对57例骨关节疾病患者进行多层螺旋CT扫描，并进行二维多平面重建（MPR）和容积再现重建（VRT），分析病变的情况。结果MPR对骨关节疾病细节显示满意，可以多平面观察骨的密度、形态、大小变化及发现邻近软组织改变；而Ⅵ汀三维重建对病变的定位和空间关系理解更直观、立体、准确，简化了思维。结论多层螺旋CT对骨关节疾病诊断具有很高的应用价值。作为轴位图像的重要补充，2D-MPR和3D-VRT重建能更直观和立体地显示病变，两者结合使用，对临床治疗方案和手术方案的制订具有重大的指导意义。     

Comparison between conventional CT and grayscale inversion CT images in the assessment of the post-operative spinal orthopaedic implants

AimTo compare the accuracy of the inverted greyscale CT versus the conventional CT in the assessment of post-operative spinal orthopaedic implants and osseous fusion.Methods50 patients who had CT as part of their routine spinal implant follow up were evaluated for the presence of fusion, fracture and loosening with conventional CT and with greyscale inverted CT images. 3 independent observers assessed the images 2 months apart. Diagnostic performance (sensitivity and specificity) of the conventional and greyscale inversion images relative to the reference standard were calculated. Agreement with the reference standard was assessed using Cohen's kappa for conventional and greyscale inversion images.ResultsCorrect classifications increased when using the greyscale inverted CT images for each reader compared to conventional CT images (40–46, 39 to 42 and 41 to 44 (out of 50)). Inverted images demonstrated better agreement with the reference standard than conventional grayscale images for assessment of fusion (kappa of 0.588 for inverted CT versus 0.484 for conventional CT) and loosening (kappa 0.386 for inverted versus 0.293 for conventional). Sensitivity was increased for assessment of fusion and loosening. McNemar's test performed for assessment of sensitivity differences showed statistical significance (p = 0.038 for fusion and p = 0.0313 for loosening).ConclusionGreyscale inversion CT is a useful adjunct which has advantages (improved sensitivity and better agreement) over conventional CT imaging in cases of fusion and loosening of metallic implants following spinal instrumentation. We recommend the use of both the greyscale inversion CT images and conventional CT imaging when assessing post-operative spinal orthopaedic implants.