腰椎退变性滑脱临床与影像学分型的可信度与可重复性分析

【摘要】 目的：探讨腰椎退变性滑脱临床与影像学（CARDS）分型的可信度与可重复性,分析其临床应用价值。方法：以CARDS分型为标准,由5位研究者对2010年1月~2013年12月在我院就诊的49例退变性腰椎滑脱患者进行独立分型,1个月后再次独立分型。收集结果,分别行不同观察者间可信度和同一观察者内可重复性分析,计算Kappa值与Spearman相关系数。结果：共计490例次分型中,包括A型74例次（15%）,B型167例次（34%）,C型187例次（38%）和D型62例次（13%）。5位研究者在第1次测试中对椎间隙高度、后凸畸形、滑脱距离及最终分型判断一致的百分比分别为77.6%~93.9%（89.6%）、69.4%~91.8%（86.6%）、67.3%~81.6%（77.5%）和65.3%~81.6%（74.1%）;可信度Kappa值分别为、0.764、0.719、0.596和0.641;Spearman相关系数分别为0.564、0.612、0.576和0.589。同一研究者前后两次测试中对椎间隙高度、后凸畸形、滑脱距离及最终分型判断一致的百分比分别为85.7%~98.0%（94.7%）、89.8%~95.9%（92.1%）、77.6%~91.8%（87.5%）和75.5%~87.8%（82.4%）;其可重复性Kappa值分别为0.857、0.842、0.779和0.804;Spearman相关系数分别为0.714、0.702、0.689和0.645。结论：CARDS分型应用于退变性腰椎滑脱患者具有较高的可信度与极佳的可重复性,值得临床推广应用。     

Intestinal microdialysis--applicability, reproducibility and local tissue response in a pig model.

BACKGROUND AND AIMS: Microdialysis has been applied to the intestinal wall for the purpose of monitoring local ischemia. The aim of this study was to investigate the applicability, reproducibility and local response to microdialysis in the intestinal wall. MATERIALS AND METHODS: In 12 pigs two microdialysis probes were inserted into the ileal wall, one in the peritoneal cavity and one in the psoas muscle. Relative recovery was measured for all probes by the no net flux method. Metabolic measurements of glucose, lactate and glycerol were performed over six hours. The ileal wall segments containing the probes were processed for histological examination. RESULTS: Large intra- and inter-group differences in the relative recovery were found between all locations. Absolute values of metabolites showed no significant changes during the study period. The lactate in blood was 25-30% of the intra-tissue values. A severe inflammatory reaction was seen in the ileal wall around all probes. CONCLUSION: Measurement of the relative recovery is essential for valid measurements of metabolites when using microdialysis. The inflammatory reaction around the probe in the intestinal wall is likely to affect metabolism and measurements hereof. Therefore intestinal wall microdialysis seems confined to experimental research, and future studies should consider the intra-peritoneal approach.     

The value of combining single photon emission computerised tomography and computerised tomography in the investigation of spondylolysis

The aim of this study was to assess the diagnostic value of combining single photon emission computerised tomography (SPECT) with reverse gantry computerised tomography (rg-CT) in the investigation of spondylolysis. Patient characteristics and imaging results in 118 patients, aged 8–44 years, with low back pain (LBP) were analysed. SPECT showed increased scintigraphic uptake in 80 patients, and spondylolysis was identified on rg-CT in 53. The Cohen Kappa ratio of 0.362 (95% CI: 0.198–0.526) suggests only fair agreement for the result of increased scintigraphic activity with the finding of spondylolysis on rg-CT. We conclude that these investigations give mutually exclusive information, which leads to four diagnostic categories. When there was increased scintigraphic activity on SPECT, 58.8% (95% CI: 48.0–69.5%) of patients had spondylolysis on rg-CT. With rest from provoking activities, these lesions may heal. We interpret the findings of increased scintigraphic activity, but no spondylolysis demonstrated on rg-CT as indicating a bone stress response. These also require rest from provoking activity to prevent a stress fracture developing. In this study, 84.2% (95% CI: 72.67–95.8%) of those patients without increased activity on SPECT had no spondylolysis identified on rg-CT. These patients may need further investigations such as magnetic resonance imaging (MRI) to diagnose pathology, which typically does not involve the posterior elements—but rest from sport may not be so important. There were five patients in our study, without increased scintigraphic activity, but in whom bilateral chronic-appearing (wide separation, smooth sclerotic bone margins) spondylolyses were identified at L5. These all were anticipated from previous plain radiographs or MRI. This group will almost certainly not heal, and if the spondylolyses are the cause of pain these vertebrae will need stabilisation by surgery if physiotherapy fails.     

High-strain-rate brain injury model using submerged acute rat brain tissue slices

Blast-induced traumatic brain injury (bTBI) has received increasing attention in recent years due to ongoing military operations in Iraq and Afghanistan. Sudden impacts or explosive blasts generate stress and pressure waves that propagate at high velocities and affect sensitive neurological tissues. The immediate soft tissue response to these stress waves is difficult to assess using current in vivo imaging technologies. However, these stress waves and resultant stretching and shearing of tissue within the nano- to microsecond time scale of blast and impact are likely to cause initial injury. To visualize the effects of stress wave loading, we have developed a new ex vivo model in which living tissue slices from rat brain, attached to a ballistic gelatin substrate, were subjected to high-strain-rate loads using a polymer split Hopkinson pressure bar (PSHPB) with real-time high-speed imaging. In this study, average peak fluid pressure within the test chamber reached a value of 1584±63.3?psi. Cavitation due to a trailing underpressure wave was also observed. Time-resolved images of tissue deformation were collected and large maximum eigenstrains (0.03-0.42), minimum eigenstrains (-0.33 to -0.03), maximum shear strains (0.09-0.45), and strain rates (8.4×103/sec) were estimated using digital image correlation (DIC). Injury at 4 and 6?h was quantified using Fluoro-Jade C. Neuronal injury due to PSHPB testing was found to be significantly greater than injury associated with the tissue slice paradigm alone. While large pressures and strains were encountered for these tests, this system provides a controllable test environment to study injury to submerged brain slices over a range of strain rate, pressure, and strain loads.     

The Corneal EyeSys System: accuracy analysis and reproducibility of first-generation prototype

The EyeSyS Corneal Topography System manufactured by EyeSys Laboratories, Inc., Houston, Tex utilizes a unique data-acquisition design to perform rapid, cost-effective quantitative photokeratoscopy. We evaluated a first-generation prototype system. Repeated testing with this prototype demonstrated an accuracy and reproducibility to within 0.25 D on spherical surfaces. Similar results were obtained in testing aspherical surfaces without refocusing. Data from preliminary clinical studies are displayed for the following corneal conditions: normal, keratoconus, post-keratoplasty, and post-keratoplasty with wound ectasia. Advantages of the EyeSys System include rapid data analysis and display, ease of operation, and compact table-top size.     

MicroCT morphometry analysis of mouse cancellous bone: intra- and inter-system reproducibility

The agreement between measurements and the relative performance reproducibility among different microcomputed tomography (microCT) systems, especially at voxel sizes close to the limit of the instruments, is not known. To compare this reproducibility 3D morphometric analyses of mouse cancellous bone from distal femoral epiphyses were performed using three different ex vivo microCT systems: GE eXplore Locus SP, Scanco μCT35 and Skyscan 1172. Scans were completed in triplicate at 12 μm and 8 μm voxel sizes and morphometry measurements, from which relative values and dependence on voxel size were examined. Global and individual visually assessed thresholds were compared. Variability from repeated scans at 12 μm voxel size was also examined. Bone volume fraction and trabecular separation values were similar, while values for relative bone surface, trabecular thickness and number varied significantly across the three systems. The greatest differences were measured in trabecular thickness (up to 236%) and number (up to 218%). The relative dependence of measurements on voxel size was highly variable for the trabecular number (from 0% to 20% relative difference between measurements from 12 μm and 8 μm voxel size scans, depending on the system). The intra-system reproducibility of all trabecular measurements was also highly variable across the systems and improved for BV/TV in all the systems when a smaller voxel size was used. It improved using a smaller voxel size in all the other parameters examined for the Scanco system, but not consistently so for the GE or the Skyscan system. Our results indicate trabecular morphometry measurements should not be directly compared across microCT systems. In addition, the conditions, including voxel size, for trabecular morphometry studies in mouse bone should be chosen based on the specific microCT system and the measurements of main interest.     

Validation of tissue array technology in head and neck squamous cell carcinoma

BACKGROUND: The recent development of tissue array technology has potentiated large-scale retrospective cohort studies using archival formalin-fixed, paraffin-embedded tissues. This study evaluates the potential for using archival head and neck cancer tissue in such arrays. METHOD: Tissue array blocks were made from 184 head and neck cancer specimens. Three core tissue biopsies (0.6 mm x 3-4 mm) were taken from individual "donor" paraffin-embedded tumor blocks and arrayed into a new "recipient" paraffin block. Immunohistochemical (IHC) analyses were performed using antibodies recognizing cyclin-D1, Rb, and EGFR. IHC was scored on a 6-point scale for extent and a 3-point scale for intensity. We compared the staining of tissue array disks with staining of full tissue sections. RESULTS: Seventy-four percent (475 of 640) of samples placed into tissue arrays were confirmed to represent tumor tissue. The remaining samples were lost during processing or contained too few tumor cells. Only 6% of cases were completely lost, whereas 55%, 28%, and 11% of cases were judged on 3, 2, or 1 disk, respectively. Cohen's kappa coefficient was 0.66 for cyclin-D1, 0.40 for EGFR, and 0.41 for Rb. CONCLUSIONS: Tissue array technology is a rapid and efficient method for retrospective analysis of protein expression and is a promising tool for validation of prognostic markers in large series of head and neck squamous cell carcinomas. The agreement in scoring of the full section and the tissue arrays is reasonable. Discordance is probably due to intraobserver variation and lack of robustness of the scoring inherent of the proteins studied.     

The accuracy and reproducibility of radiographic assessment of stress-shielding. A postmortem analysis

BACKGROUND: Although periprosthetic bone loss remains a major concern in total hip arthroplasty, radiographic assessment of such loss is both difficult and subjective. In the present study, we assessed the ability of orthopaedic surgeons to reproducibly recognize changes in periprosthetic bone density on radiographs. We hypothesized that assessment of periprosthetic bone loss on plain radiographs is not reliable enough to justify its use in outcomes research. METHODS: Twenty-nine unilateral total hip replacements and the surrounding bone were retrieved at autopsy, and radiographs were made; radiographs of the contralateral, normal femur were also made after implantation of an identical prosthesis and used as a control. Three orthopaedic surgeons independently examined the specimen radiographs and classified bone loss in each of sixteen femoral zones. Bone loss was recorded as present if the bone of the femur that had had in vivo implantation showed evidence of cortical thinning, increased porosity, or decreased density (either cortical or trabecular) when compared with the control femur. The kappa coefficient was used to quantify interobserver and intraobserver reproducibility in determining bone loss for the 464 zones examined and in determining the Engh and Bobyn stress-shielding classification of each femur. In fourteen femoral pairs, bone loss was also quantified with dual-energy x-ray absorptiometry, and the resulting value was then compared with the bone-loss classification that had been determined radiographically. RESULTS: First, the surgeons agreed on the presence or absence of bone loss in 73 percent (337) of the 464 zones. The interobserver kappa value of 0.58 denoted only good reproducibility. The intraobserver reproducibility was better; the surgeon's initial evaluation of bone loss agreed with his second evaluation for 90 percent of the zones (kappa = 0.74). Second, the three surgeons agreed on the degree of stress-shielding, according to the Engh and Bobyn classification, in 66 percent (nineteen) of the twenty-nine femora. The kappa value for this comparison was only 0.27, indicating marginal reproducibility. Third, although there was some agreement among reviewers when there was 20 to 60 percent reduction in bone-mineral content as determined with dual-energy x-ray absorptiometry, excellent agreement among the examiners (kappa = 0.85) was not achieved until bone loss averaged 70 percent. CONCLUSIONS: On the basis of these results, we suggest caution in interpreting results from studies of femoral bone loss that have used plain radiographic analysis if the authors have not provided interobserver reliability data. We question the utility of evaluating periprosthetic bone loss on radiographs, since the loss is not reproducibly recognized until 70 percent of the bone is gone.     

Continuous transcutaneous oxygen measurement: reproducibility and trace analysis in healthy adults

One hundred and fourteen transcutaneous oxygen traces were obtained from 46 adults using a mass spectrometer. Such traces usually rise to a plateau about which they fluctuate. To estimate the plateau level, here called the asymptote, two models are described--a time-series model and a growth model. If yt is the trace measurement at time t, for the time-series model. yt + 1 = m + alpha (yt-m) + epsilon t, and for the growth model dyt/dt = beta (m-yt), where parameters alpha and beta represent the rate of approach to the asymptote m. Least squares estimates of these parameters were determined for every trace. For every trace, the estimated asymptotes are similar for both models but the other parameters show less agreement. Considering the traces for each person in pairs, each trace pair is allocated to one of four groups according as the traces were recorded on the same or different sites and on the same or different days. The correlation coefficient (r) between the estimated asymptotes is greatest for traces recorded on the same site and day (r greater than 0.94, P less than 0.001) and least for traces from different sites and days (r greater than 0.71, P less than 0.001). The time series estimates of the asymptote are more credible than the growth model.     

Activated clotting time (ACT) testing: analysis of reproducibility

Activated Clotting Time (ACT) has been the standard for monitoring heparin anticoagulation in cardiac surgery for three decades. Although a 10% coefficient of variation (CV) is the referenced standard for the test, no recent reports of precision are available. The precision of Hemochron FTCA510 (celite) and KACT (kaolin) ACT test tubes was evaluated using a retrospective analysis of results from both laboratory studies and routine clinical usage. Laboratory studies of reproducibility included analysis of the CV from repetitive testing using multiple lots of ACTs. Substrates used included 40 consecutive lots of control plasma and freshly heparinized donor blood. Across the lots of control plasma, the celite ACT yielded an average CV of 5.4% for the normal control level and 4.0% in the abnormal control level (range 3.6-9.7% and 2.7-6.3%, respectively). The KACT showed similar performance for the normal (mean = 4.5%, range 2.2-7.8%) and abnormal (mean = 3.8%, range 2.0-10.0%). These values, significantly less than 10%, reflect the combined variability of both the ACT tests and the lyophilized, single use vial, control material. Fresh whole blood samples exhibited improved ACT precision when compared to this artificial substrate. CVs for the celite ACT range from 0.6-6.0% at one unit heparin/ml blood to 2.4-11.6% at 5 units/ml where clotting times exceed 650 sec. The KACT showed even lower CVs at all heparin levels, with values of 2.4-7.0%. Clinical evaluations included samples (N = 56) collected from cardiac surgery patients with celite ACT values ranging to 744 sec. Duplicate values differed by an average of 7.5 sec or 1.8%. There was only one clinically significant difference in paired values; a 376 sec paired with a 406 sec, 400 sec being the clinical target time. This retrospective data analysis demonstrates that Hemochron ACT variability is significantly less than 10%.     

Validation of a mathematical model for laser-induced thermotherapy in liver tissue

The purpose of the study was to develop a simulation approach for laser-induced thermotherapy (LITT) that is based on mathematical models for radiation transport, heat transport, and tissue damage. The LITT ablation was applied to ex vivo pig liver tissue. Experiments were repeated with different laser powers, i.e., 22–34 W, and flow rates of the cooling water in the applicator system, i.e., 47–92 ml/min. During the procedure, the temperature was measured in the liver sample at different distances to the applicator as well as in the cooling circuit using a fiber optic thermometer. For validation, the simulation results were compared with the results of the laser ablation experiments in the ex vivo pig liver samples. The simulated and measured temperature curves presented a relatively good agreement. The Bland-Altman plot showed an average of temperature differences of –0.13 ^°C and 95%-limits-of-agreement of ±7.11 ^°C. The standard deviation amounted to ±3.63 ^°C. The accuracy of the developed simulation is comparable with the accuracy of the MR thermometry reported in other clinical studies. The simulation showed a significant potential for the application in treatment planning.     

Evaluation of a computerised polysomnography system.

BACKGROUND: Manual analysis of sleep, breathing, and oxygenation records is the "gold standard" for diagnosing sleep abnormalities but is time consuming and cumbersome. The accuracy and cost of a computerised sleep analysis system have therefore been investigated. METHODS: Manual and computerised (CNS Sleep Lab) scores from 43 consecutive clinical sleep studies were prospectively compared for accuracy and the time and costs were recorded. RESULTS: There were good correlations and no systematic differences between manual and computer scoring for total sleep time, sleep onset latency, and duration of REM sleep. There was a small but clinically insignificant systematic difference in breathing pattern analysis, the number of hypopnoeas/hour being lower with manual than with computer scoring (13 (SE 3) v 15 (SE 3)/hour). There was no difference between computer and manual scoring of the frequency of apnoeas, so the frequency of apnoeas + hypopnoeas was clinically insignificantly higher with computer scoring with a highly significant correlation between the two techniques. The time taken to perform the analyses was not different between the two methods (manual 83 (SE 8) v computer 86 (SE 8) minutes). The computer system was six times more expensive than the manual system and annual running costs, including full maintenance contract and 15% depreciation, were twice as great. CONCLUSION: The CNS Sleep Lab is sufficiently accurate for use in clinical sleep studies but is significantly more expensive and does not save technician time.     

Coronal and sagittal reconstruction in computerised tomography.

As useful and dramatic as axial computed tomograms are, severe limitations have been encountered. Most of these involve the accurate location of masses and, as in angiography, projections in several planes are essential. Recent advances in both hard and softward allow three millimeter slice thicknesses at low radiation dosage. Coronal and sagittal reconstructions are practical and obtained with ease. The computerized tomogram is invaluable in complementing standard neuroradiological procedures and, in some cases, allows definitive diagnosis. This degree of accuracy is not possible without multiplane reconstructions.     

Radiographic signs of union of scaphoid fractures. An analysis of inter-observer agreement and reproducibility

Inter-observer agreement and reproducibility of opinion were assessed for the radiographic diagnosis of union of scaphoid fractures on films taken 12 weeks after injury. Weighted kappa statistics were used to compare the opinions of eight senior observers reviewing 20 sets of good quality radiographs on two occasions separated by two months. There was poor agreement on whether trabeculae crossed the fracture line, whether there was sclerosis at or near the fracture and on whether the proximal part of the scaphoid was avascular. As a consequence, agreement on union also was poor; it appears that radiographs taken 12 weeks after a scaphoid fracture do not provide reliable and reproducible evidence of healing.