Accurate and efficient separation of left and right lungs from 3D CT scans: A generic hysteresis approach

Nearly 20% of Total knee Arthroplasty patients remain dissatisfied. This is a major concern in twenty-first century arthroplasty practice. Accurate implant sizing is shown to improve the implant survival, knee balance and patient reported outcome. Aim of the current study is to assess the efficacy of pre-operative three-dimensional (3D) CT scan templating in a robot-assisted TKA in predicting the correct implant sizes and alignment. Prospectively collected data in a single center from 30 RA-TKAswas assessed. Inclusion criterion was patients with end stage arthritis (both osteoarthritis and rheumatoid arthritis) undergoing primary TKA. Patients undergoing revision TKA and patients not willing to participate in the study were excluded. Preliminary study of ten patients had indicated almost 100% accuracy in determining the implant size and position. Sample size was estimated to be 28 for 90% reduction in implant size and position error with α error of 0.05 and beta error of 0.20 with power of study being 80. Post-operative radiographs were assessed by an independent observer with respect to implant size and position. The accuracy of femoral and tibial component sizing in the study was compared with the historic control with Chi-squared test. The p value < 0.05 was considered significant. The pre-operative CT scan 3D templating accuracy was 100% (30 out of 30 knees) for femoral component and 96.67% (29 out of 30 knees) for tibial component. The implant position and limb alignment was accurate in 100% of patients. The accuracy of femoral component and tibial component sizing is statistically significant (Chi-squared test, p value 0.0105 and 0.0461, respectively). The study results show the effectiveness of pre-operative 3 D CT scan planning in predicting the implant sizes and implant positioning. This may have a potential to improve the implant longevity, clinical outcomes and patient satisfaction.

IntroductionAccurate glenoid component placement is crucial for anatomic (TSA) or reverse (RSA) total shoulder arthroplasty. Preoperative glenoid assessment by using CT scans with or without planning software seems to be the established method to plan implant positions. MRI scans can also display the glenoid bone for preoperative assessment while reducing radiation exposure. Therefore, the objective of this study was to manually assess the glenoid version and inclination in 2D MRI and CT scans in cases with degenerative shoulder pathologies. The results were compared to those of an automated 3D planning software to validate the imaging modality for preoperative glenoid assessment. MethodsMRI and CT scans of 146 patients (n=41 aTSA; n=105 RSA) were included in this retrospective, single-center study. Glenoid version and inclination were measured manually according to Friedman et al and Maurer et al on CT and MRI scans by two observers. Subsequently, the results were compared to the automated measurements performed by a planning software. A repeated-measures analysis of variance (ANOVA) was performed to compare the measured angles and interobserver and intraobserver reliability was calculated using the intraclass correlation coefficients. The level of significance was set p<0.05. ResultsThe average glenoid inclination measured in CT scans was 7.94°±7.33°, in MRI scans 8.56°±7.34° and in automated planning software 7.87°±7.60°. The ANOVA analysis revealed significant differences in mean inclination between 2D MRI and 2D CT (p<0.0005) and between MRI and automated software (p=0.011). No significant difference was found between 2D CT scans and automated planning software (p=1.000). Mean glenoid version measured in 2D CT scans was -7.94°±10.86°, in 2D MRI scans it was -8.04°±10.80° and -8.32°±11.53° by the automated planning software. There was no significant difference in between measurement methods (p = 0.339). Interobserver error analysis showed no statistical differences between the two observers. All measurements had excellent intraobserver reliability. ConclusionPreoperative assessment of glenoid version and inclination is crucial in ensuring precise implant positioning and orientation in TSA and RSA. This study observed a significant level of concordance between manual and automated measuring techniques utilizing MRI and CT scans. Mean glenoid inclination exhibited a statistically significant difference of less than 1° across the assessment modalities and no difference for glenoid version was noted. It seems to be questionable if this finding is clinically relevant. MRI may serve as a viable and safe option for assessing glenoid morphology, version and inclination if CT scans are not available.

Introduction:Reliability is the study of internal consistency, reproducibility (intraobserver and interobserver), and agreement. Reproducibility studies that classify tibial plateau fractures have used plain radiography and two-dimensional (2D) CT scans and three-dimensional (3D) printing. The objective of this study was to evaluate the reproducibility of the Luo Classification of tibial plateau factures and the surgical approaches chosen for these fractures based on 2D CT scans and 3D printing.Methods:A reliability study was performed at the Universidad Industrial de Santander, Colombia, that evaluated the reproducibility of the Luo Classification of tibial plateau fractures and the choice of surgical approaches based on 20 CT scans and 3D printing, with five evaluators.Results:For the trauma surgeon, reproducibility was better when evaluating the classification using 3D printing, with a kappa of 0.81 (95% confidence interval [CI], 0.75-0.93; P < 0.01) than when using CT scans, with a kappa of 0.76 (95% CI, 0.62-0.82; P < 0.01). When comparing the surgical decisions made by the fourth-year resident with those of the trauma surgeon, a fair reproducibility was obtained using CT, with a kappa of 0.34 (95% CI, 0.21-0.46; P < 0.01), which improved to substantial when using 3D printing, with a kappa of 0.63 (95% CI, 0.53-0.73; P < 0.01).Discussion:This study found that 3D printing provided more information than CT and decreased measurement errors, thereby improving reproducibility, as shown by the higher kappa values that were obtained.Conclusion:The use of 3D printing and its usefulness are helpful to decision making when providing emergency trauma services to patients with intraarticular fractures such as those of the tibial plateau.

Introduction Odontoid fractures (OF) are frequent in the trauma population, and there is no universally accepted single method of management. The objective of this study was to evaluate the epidemiology and management of type II OF in Latin America treated either with rigid cervical orthosis or surgery. Patients and Methods A total of 83 patients treated conservatively or by surgery were enrolled in this retrospective study. Medical charts, imaging studies, and outcomes of patients were analyzed in the pretreatment period and at the last medical evaluation. The fractures were assessed using conventional radiographs, three-dimensional computed tomographic (3D-CT) scans, and magnetic resonance images. Fracture gaps, the direction and the degree of displacement of the odontoid process, the fracture line anatomy, the degrees of atlantoaxial instability, the comminuted fracture, and the surface contact area were analyzed. The decision for operative or nonoperative treatment was based on anesthesia risk, and patient's choice of the nonoperative treatment. The nonoperative management generally consisted of a rigid cervical orthosis for 3 months. The type of surgery to be performed was chosen by the surgeon. The solid bony union was defined as the presence of bony bridges and the definite continuity of cortical bone. Fibrous union was considered present when no degree of motion was evident in dynamic radiographs despite persistent cortical bone discontinuity within a fracture gap on 3D CT scans. Nonunion was defined as a definite fracture gap with abnormal motion of the fractured dens on dynamic radiographs and on a 3D CT scan. Results A total of 83 patients were included in this study. The patients were 78.3% men, the mean age = 44.98 ( ± 23.20 years) years. Traffic accidents (66.3%) were the most common cause of trauma. The main symptom was pain (85.5%) in the posterior cervical region. The median time elapsed from accident to surgery was 7 days (P25: 2/P75: 27.5). Median follow-up was 23.66 ( ± 25.43 months) months. Conservative treatment with cervical orthosis, for example, Miami J collar or halo-vest was used in 20.5% of the cases. Odontoid screw technics (57.6%) were the most common surgical treatment adopted as primary surgical treatment. Symptomatic nonunion was observed in two cases with conservative treatment and three cases after odontoid screw fixation. All the patients were referred to posterior C1–C2 fixation. The posterior fixation tended to be used after conservative failed therapy, after nonunion anterior screw surgery, and in fractures with greater displacement. The most common radiological feature was no displacement of the odontoid process in relation to the body of C2, horizontal fracture line, gap fracture &lt; 2 mm, no subluxation across each C1–C2 facet joint and no comminuted fracture. Conclusion The patients treated nonoperatively with a rigid collar may have an overall favorable outcome compared with surgical treatment. A well-designed prospective study is needed to better elucidate optimal treatment algorithms from both an outcomes and cost-effectiveness perspective.

The purpose of CT simulation in radiotherapy is to acquire patient geometrical information and to build a patient geometrical model for treatment planning. Errors in patient model caused by motion artifacts will influence all treatment fractions and therefore should be handled carefully. Due to the tumor respiratory motion, the captured tumor position and shape can be heavily distorted. The distortions along the axis of motion could result in either a lengthening or shortening of the target. The center of the imaged target can be displaced by as much as the amplitude of the motion.A newly developed technique that can reduce motion artifacts and provide patient geometry throughout the whole breathing cycle is called respiration‐correlated or 4D CT scan. The basic idea for 4D CT scan is that, at every position of interest along patient's long axis, images are over‐sampled and each image is tagged with breathing phase information. After the scan is done, images are sorted based on the corresponding breathing phase signals. Thus, many 3D CT sets are obtained, each corresponding to a particular breathing phase, and together constitutes a 4D CT set that covers that the whole breathing cycle. 4D CT scan has been developed at various institutions with slightly different flavors. In this lecture, we will provide an overview of various implementations of 4D CT scan.4D CT scan can be used to account for respiratory motion to generate images with less distortion than 3D CT scan. 4D images also contain respiratory motion information of tumor and organs that is not available in a 3D CT image. This technology can be used for respiratory‐gated treatment to identify the patient‐specific phase of minimum tumor motion, determine residual tumor motion within the gate interval, and compare treatment plans at different phases. It can also be used for non‐gated treatment planning to define ITV by combining gross tumor volume at all breathing phases or using a method called maximum intensity projection. Of course 4D CT will also play a vital role in the futuristic 4D radiotherapy where the tumor is tracked dynamically during the treatment using multi‐leaf collimator.Existing problems for 4D CT scan include the increased imaging dose, CT tube heating, and data management. More importantly, one has to keep in mind that 4D CT scan is not really 4D. Temporal information is mapped into one breathing cycle. Irregular respiration will cause artifacts in 4D CT images. Patient coaching can improve the regularity of breathing pattern and thus reduce the residual artifacts. However this issue still deserves further studies.Educational Objectives:1. Understand the origin and magnitude of motion artifacts in free breathing helical CT scan.2. Understand how 4D CT scan works.3. Understand how 4D CT can be used in radiotherapy.4. Understand the remaining artifacts in 4D CT scan and possible future improvements.

The purpose of CT simulation in radiotherapy is to acquire patient geometrical information and to build a patient geometrical model for treatment planning. Errors in patient model caused by motion artifacts will influence all treatment fractions and therefore should be handled carefully. Due to the tumor respiratory motion, the captured tumor position and shape can be heavily distorted. The distortions along the axis of motion could result in either a lengthening or shortening of the target. The center of the imaged target can be displaced by as much as the amplitude of the motion. A newly developed technique that can reduce motion artifacts and provide patient geometry throughout the whole breathing cycle is called respiration‐correlated or 4D CT scan. The basic idea for 4D CT scan is that, at every position of interest along patient's long axis, images are over‐sampled and each image is tagged with breathing phase information. After the scan is done, images are sorted based on the corresponding breathing phase signals. Thus, many 3D CT sets are obtained, each corresponding to a particular breathing phase, and together constitutes a 4D CT set that covers that the whole breathing cycle. 4D CT scan has been developed at various institutions with slightly different flavors. In this lecture, we will provide an overview of various implementations of 4D CT scan. 4D CT scan can be used to account for respiratory motion to generate images with less distortion than 3D CT scan. 4D images also contain respiratory motion information of tumor and organs that is not available in a 3D CTimage. This technology can be used for respiratory‐gated treatment to identify the patient‐specific phase of minimum tumor motion, determine residual tumor motion within the gate interval, and compare treatment plans at different phases. It can also be used for non‐gated treatment planning to define ITV by combining gross tumor volume at all breathing phases or using a method called maximum intensity projection. Of course 4D CT will also play a vital role in the futuristic 4D radiotherapy where the tumor is tracked dynamically during the treatment using multi‐leaf collimator. Existing problems for 4D CT scan include the increased imagingdose,CT tube heating, and data management. More importantly, one has to keep in mind that 4D CT scan is not really 4D. Temporal information is mapped into one breathing cycle. Irregular respiration will cause artifacts in 4D CTimages. Patient coaching can improve the regularity of breathing pattern and thus reduce the residual artifacts. However this issue still deserves further studies. Educational Objectives: 1. Understand the origin and magnitude of motion artifacts in free breathing helical CT scan. 2. Understand how 4D CT scan works. 3. Understand how 4D CT can be used in radiotherapy. 4. Understand the remaining artifacts in 4D CT scan and possible future improvements.

Where Are We Now? To justify widespread adoption of any classification scheme, a high degree of inter- and intraobserver reliability must be demonstrated. The reliability of assessing proximal humerus fracture patterns using widely-held classification systems such as that of Neer and Hertel based on plain radiographs has been fairly low, though the addition of advanced imaging such as two-dimensional (2-D) and three-dimensional (3-D) CT scans appears to improve both inter- and intraobserver reliability [4]. More recently, using 3D printed models alone in the surgical planning process has been found to improve interobserver reliability over plain radiographs and both 2D and 3D CT scans using the Neer system, though the observed agreement with the printed models was only moderate [2]. In these studies, where the kappa values using the guidelines of Landis and Koch were reported as "substantial" and "moderate," respectively, we must recognize that a high proportion of cases will still be misclassified. As a consequence, clinical outcomes research based on these classifications may result in misleading results. A recent meta-analysis [7] based on randomized trials comparing fracture fixation of various anatomic sites both with and without the use of 3D-printed models determined that blood loss, surgical time, fluoroscopy use, clinical outcomes, and achievement of anatomic reduction all favored 3D modeling. A limitation of this study was the inclusion of multiple fracture types and the small number of patients in several included studies. Furthermore, the effect size for many of the surgical outcome measures could be quite small based on the reported 95% confidence intervals. The only included study involving complex three- and four-part proximal humerus fractures [8] found a reduction in operative time, blood loss, and fluoroscopy time, though the clinical outcomes at final follow-up were similar. It is not clear, however, whether the mean 15-minute decreased operative time and approximately 55 cc decreased blood loss with 3D models is clinically significant. A retrospective study [3] comparing conventional preoperative planning using plain radiographs and both 2D and 3D CT scans with both computer-assisted virtual planning and 3D-printed models found shorter operative time, less blood loss, and less fluoroscopy in the latter groups compared to the conventional group. Planning time was shorter in the computer-assisted planning group compared with the 3D model group. Once again, the reported differences in the surgical parameters were small. Whether these differences justify the direct and indirect costs of routine use of 3D models, including the creation (personnel, software, hardware), storage, and potential sterilization, remain unclear [5]. In their current study, Spek and colleagues [6] examined 20 adult patients with complex three- and four-part proximal humerus fractures that were deemed difficult to classify and determined that the addition of 3D-printed handheld models to a series of plain radiographs and both 2D and 3D CT scan images did not improve interobserver reliability for the majority of fracture characteristics being studied. Additionally, the handheld models did not improve fracture classification using either the Neer or Hertel system. There was also no difference in agreement between residents and attending orthopaedic surgeons as to whether the 3D models aided in fracture pattern classification. These findings suggest that the routine use of 3D-printed models may not be beneficial for classifying proximal humeral fracture patterns beyond the information gained from currently available imaging modalities. Specifically, use of these models as the sole determinant for recommending surgical intervention based on fracture displacement should probably be avoided at this time based on the results of the current study. What is particularly concerning about the findings of the current study is that the addition of the 3D-printed models did not improve the ability of attending surgeons to identify particular fracture characteristics and classify patterns above that of the surgeons in-training. This would seem to indicate that a level of subjectivity exists within the classification systems themselves. Based on the results of the study, we should invest fewer resources determining whether handheld models improve preoperative fracture classification. The answer, according to Spek et al. [6], is a resounding "no." Where Do We Need To Go? The current study raises some important questions that warrant further study, namely: (1) In what capacity does the use of the 3D-printed model provide benefit to care for patients with proximal humerus fractures who have already been indicated for surgery? (2) What is the potential role of preoperative computer-assisted virtual surgical planning for proximal humerus fractures both with and without 3D model printing? In the only published randomized study that I am aware of assessing the surgical utility of 3D modeling for three- and four-part proximal humerus fractures [8], patients underwent preoperative planning using either two orthogonal radiographs and a thin-cut 2D CT scan versus plain radiographs, a 3D CT reconstruction with simulated fracture reduction using specialized software, and a handheld 3D-printed model. The use of 2D CT images in the control group represents a difference from the current paper, though a prior study [1] found that the use of 3D CT did not offer improvement in classification or treatment recommendations over 2D CT, except among junior residents. Regardless, to fully demonstrate the positive influence of the handheld models independently, researchers should ensure that both study groups are provided with all of the imaging modalities generally available today, including 3D CT images. Furthermore, future studies should determine whether these improvements can be replicated among surgeons of all levels of experience or if those with less experience would demonstrate greater benefit. Finally, we need a better understanding of the costs associated with the computer-assisted software and the model creation in light of the minimal—14-minute—surgical time difference reported. Computer-assisted planning can involve virtual reduction of the fracture and selection/placement of implants even without the use of 3D handheld models. One study [3] reported improved operative parameters for the virtual planning and 3D model group compared to the conventional planning group, though it is not entirely clear whether the differences are clinically significant. From a cost perspective, more data are needed to determine whether the 30 minutes of virtual planning is cost-efficient with the 18 minutes of reduced operative time. Computer planning time may be even higher for surgeons performing a lower volume of proximal humerus fracture surgery. How Do We Get There? The primary potential advantage of 3D-printed models likely will be realized in more complex proximal humerus fracture patterns that have already been indicated for surgical intervention. Specifically, the 3D models can provide the surgeon with a tactile modality for planning fracture reductions and correct placement of hardware. Future studies for determining the utility of the 3D models in the clinical realm should be designed based on objective surgical parameters such as operative time, duration of fluoroscopy use, estimated blood loss, adequacy of fracture reduction, and perhaps most importantly, on patient outcomes. Given the dearth of available evidence, the utility of 3D models versus computer-assisted fracture planning alone needs to be validated. The reported differences in these parameters have been fairly small in the literature so far and, therefore, justification for utilizing either technology necessarily requires demonstrating larger, more clinically relevant differences. Furthermore, future studies must assess whether surgeons with extensive experience with proximal humerus fracture fixation will derive any meaningful benefit from these technologies. A comparative study of this type needs to be performed in a high-volume Level 1 trauma center to achieve sufficient patient numbers. Only three-part and four-part fractures should be included and should be randomized either to planning through the use of standard imaging including 2D and 3D CT or to planning with additional use of the 3D-printed model versus computer-assisted planning. To determine which surgeons would most benefit from either the 3D model or computer-assisted planning, surgical data need to be stratified for surgeon volume and/or clinical experience. There will be a learning curve for use of the planning software, which should be taken into account regarding planning time. Innovation can often be costly, and cost benefits with both of these technologies must be demonstrated, either by calculating operating time savings compared with increased planning time and/or by reduced intraoperative implant wastage. As there are no currently defined minimal clinically important differences for surgical parameters such as intraoperative blood loss, surgical time, and use of fluoroscopy, any potential benefit must be considered in light of a rigorous cost-benefit analysis. Finally, any comparison of patient-reported functional outcomes should be viewed in light of minimal clinically important differences.

OC-0378 HELICAL TOMOTHERAPY DYNAMICS ARE NOT AN ISSUE TO TREAT LUNG TUMORS FOR PATIENTS COACHED TO ENSURE REGULAR BREATHING

The Wrightington classification system of fracture-dislocations of the elbow divides these injuries into six subtypes depending on the involvement of the coronoid and the radial head. The aim of this study was to assess the reliability and reproducibility of this classification system. This was a blinded study using radiographs and CT scans of 48 consecutive patients managed according to the Wrightington classification system between 2010 and 2018. Four trauma and orthopaedic consultants, two post CCT fellows, and one speciality registrar based in the UK classified the injuries. The seven observers reviewed preoperative radiographs and CT scans twice, with a minimum four-week interval. Radiographs and CT scans were reviewed separately. Inter- and intraobserver reliability were calculated using Fleiss and Cohen kappa coefficients. The Landis and Koch criteria were used to interpret the strength of the kappa values. Validity was assessed by calculating the percentage agreement against intraoperative findings. Of the 48 patients, three (6%) had type A injury, 11 (23%) type B, 16 (33%) type B+, 16 (33%) Type C, two (4%) type D+, and none had a type D injury. All 48 patients had anteroposterior (AP) and lateral radiographs, 44 had 2D CT scans, and 39 had 3D reconstructions. The interobserver reliability kappa value was 0.52 for radiographs, 0.71 for 2D CT scans, and 0.73 for a combination of 2D and 3D reconstruction CT scans. The median intraobserver reliability was 0.75 (interquartile range (IQR) 0.62 to 0.79) for radiographs, 0.77 (IQR 0.73 to 0.94) for 2D CT scans, and 0.89 (IQR 0.77 to 0.93) for the combination of 2D and 3D reconstruction. Validity analysis showed that accuracy significantly improved when using CT scans (p = 0.018 and p = 0.028 respectively). The Wrightington classification system is a reliable and valid method of classifying fracture-dislocations of the elbow. CT scans are significantly more accurate than radiographs when identifying the pattern of injury, with good intra- and interobserver reproducibility. Cite this article: Bone Joint J 2020;102-B(8):1041-1047.

3D CT scan is actually the gold standard for preoperative diagnosis of pelvic discontinuity (PD) in hip revision surgery. Aim of this study was to compare the accuracy of 3D-modeling with traditional and 3D CT scan. We retrospectively identified 56 patients who underwent total hip arthroplasty revisions with Paprosky Type-3 periacetabular bone defects. Preoperative X-rays, CT scans and 3D-models were blindly reviewed by two orthopedic surgeons to detect possible pelvic discontinuities. Results were compared with surgical notes. Independent sensitivities, specificities, positive predictive values and negative predictive values were calculated for X-rays, CT scan and 3D models. Analysis of interobserver reliability was performed. Fifty-six patients met inclusion criteria. In nine patients, surgical notes indicated a pelvic discontinuity. On 3D CT scans, PD was identified in 25 cases for observer 1 and in 24 cases for observer 2. Analyzing 3D-models, PD was identified in eleven patients by both observers. The nine patients, with PD reported on the surgical report, were all identified with both the techniques. The specificity of standard 3D CT was 0.66 for observer 1 and 0.68 for observer 2 and increased to 0.96 for both observers with the utilization of 3D-models. The positive predictive value increased from 0.36 (observer 1) and 0.38 (observer 2) with the CT evaluation to 0.82 in the 3D-models evaluation. The analysis of 3D models was characterized by a perfect intraobserver reliability (intraobserver correlation coefficient = 1). The observers showed substantial agreement for PD classification; the kappa values were 0.96 and 0.77, respectively, for CT scan and 3D-model evaluation. 3D-modeling showed higher specificity than traditional and 3D CT scans in identification of PD in Paprosky Type-3 periacetabular bone defects.

In many patients respiratory motion causes motion artifacts in CT images, thereby inhibiting precise treatment planning and lowering the ability to target radiation to tumors. The 4D Phantom, which includes a 3D stage and a 1D stage that each are capable of arbitrary motion and timing, was developed to serve as an end-to-end radiation therapy QA device that could be used throughout CT imaging, radiation therapy treatment planning, and radiation therapy delivery. The dynamic accuracy of the system was measured with a camera system. The positional error was found to be equally likely to occur in the positive and negative directions for each axis, and the stage was within 0.1 mm of the desired position 85% of the time. In an experiment designed to use the 4D Phantom's encoders to measure trial-to-trial precision of the system, the 4D Phantom reproduced the motion during variable bag ventilation of a transponder that had been bronchoscopically implanted in a canine lung. In this case, the encoder readout indicated that the stage was within 10 microns of the sent position 94% of the time and that the RMS error was 7 microns. Motion artifacts were clearly visible in 3D and respiratory-correlated (4D) CT scans of phantoms reproducing tissue motion. In 4D CT scans, apparent volume was found to be directly correlated to instantaneous velocity. The system is capable of reproducing individual patient-specific tissue trajectories with a high degree of accuracy and precision and will be useful for end-to-end radiation therapy QA.

To compare the position, displacement, degree of inclusion (DI) and matching index (MI) of the gross tumor volume (GTV) for peripheral lung cancer based on 4-dimensional CT (4D CT) and 3-dimensional CT (3D CT) assisted with active breathing control (ABC). Eighteen patients with peripheral lung cancer underwent 4D CT simulation scan during free breathing and 3D CT simulation scans in end-inspiratory hold (CTEIH) and end-expiratory hold (CTEEH) in turn. The 4D CT images from each respiratory cycle were sorted into 10 phases. phase 0 was defined as end-inspiratory phase (CT0), and phase 50 was defined as end-expiratory phase (CT50). The GTVs were delineated separately on CT0, CT50, CTEIH and CTEEH images, and then GTV0, GTV50, GTVEIH and GTVEEH were constructed, respectively. The median distances between the centroids of GTV0 and GTVEIH, GTV50 and GTVEEH were 3.9 mm and 3.4 mm in all patients, 3.2 mm and 3.1 mm in the upper lobe group, and 5.0 mm and 4.7 mm in the lower lobe group, respectively. In the upper lobe group, the GTV0 and GTVEIH were 65.9% and 63.1%, and the median mutual DIs of GTV50 and GTVEEH were 67.5%, 63.1%, respectively. In the lower lobe group, the GTV0 and GTVEIH were 35.3% and 21.4%, and the median mutual DIs of GTV50 and GTVEEH were 27.8% and 24.8%, respectively. In the upper lobe group, the median MI of GTV0 and GTVEIH was 0.5, and the median MI of GTV50 and GTVEEH was 0.6. In the lower lobe group, the median MI of GTV0 and GTVEIH was 0.2, and the median MI of GTV50 and GTVEEH was 0.3. Whether in the upper or lower lobe groups, all the differences between displacements of centroid positions of GTVEIH and GTVEEH (ABC displacement) and GTV0 and GTV50 (4D displacement ) were <1 mm in three dimensional directions (all P>0.05). The target displacement of tumors based on 3D CT scanning in end-inspiratory hold and end-expiration hold can be used to construct internal target volume instead of that based on 4D CT scanning in extreme phase for peripheral lung cancers, but spatital mismatches of GTVs are obvious between extreme phases in 4D CT and corresponding phases in 3D CT assisted with ABC, especially for tumors of smaller volume and with larger motion amplitude.

In this paper we propose a new classification of neurogenic peri-articular heterotopic ossification (HO) of the hip based on three-dimensional (3D) CT, with the aim of improving pre-operative planning for its excision. A total of 55 patients (73 hips) with clinically significant HO after either traumatic brain or spinal cord injury were assessed by 3D-CT scanning, and the results compared with the intra-operative findings. At operation, the gross pathological anatomy of the HO as identified by 3D-CT imaging was confirmed as affecting the peri-articular hip muscles to a greater or lesser extent. We identified seven patterns of involvement: four basic (anterior, medial, posterior and lateral) and three mixed (anteromedial, posterolateral and circumferential). Excellent intra- and inter-observer agreement, with kappa values > 0.8, confirmed the reproducibility of the classification system. We describe the different surgical approaches used to excise the HO which were guided by the 3D-CT findings. Resection was always successful. 3D-CT imaging, complemented in some cases by angiography, allows the surgeon to define the 3D anatomy of the HO accurately and to plan its surgical excision with precision.

Inter-observer reliability of measurements performed on digital long-leg standing radiographs and assessment of validity compared to 3D CT-scan

BackgroundConcurrent chemoradiotherapy is considered curative intent treatment for patients with non-operative esophageal cancer. Radiation-induced heart damage receives much attention. We performed repeated four-dimensional computed tomography (4DCT) to detect changes in cardiac volume during radiotherapy for esophageal cancer patients, and explored potential factors responsible for those changes.MethodsForty-six patients with esophageal cancer underwent enhanced 4DCT and three-dimensional (3D) CT scans before radiotherapy and every 10 fractions during treatment. The heart was contoured on 3DCT images, 4DCT end expiratory (EE) images and 4DCT maximum intensity projection (MIP) images by the same radiation oncologist. Heart volumes and other relative parameters were compared by the SPSS software package, version 19.0.ResultsCompared with its initial value, heart volume was smaller at the 10th fraction (reduction = 3.27%, 4.45% and 4.52% on 3DCT, EE and MIP images, respectively, p < 0.05) and the 20th fraction (reduction = 6.05%, 5.64% and 4.51% on 3DCT, EE and MIP images, respectively, p < 0.05), but not at the 30th fraction. Systolic and diastolic blood pressures were reduced (by 16.95 ± 16.69 mmHg and 7.14 ± 11.64 mmHg, respectively, both p < 0.05) and the heart rate was elevated by 5.27 ± 6.25 beats/min (p < 0.05) after radiotherapy. None of the potential explanatory variables correlated with heart volume changes.ConclusionsCardiac volume reduced significantly from an early treatment stage and maintained the reduction until the middle stage. The heart volume changes observed on 3DCT and 4DCT were consistent during radiotherapy. The changes in heart volume, blood pressure and heart rate may be valuable indicators of cardiac impairment and target dose changes.