Implementation of Level-3 Autonomous Patient-Specific Quality Assurance with Automated Human Interactive Devices

Purpose: Patient-specific quality assurance (PSQA) requires manual operation of different workstations, which is time-consuming and error-prone. Therefore, developing automated solutions to improve efficiency and accuracy is a priority. The purpose of this study was to develop a general software interface with scripting on a human interactive device (HID) for improving the efficiency and accuracy of manual quality assurance (QA) procedures. Methods: As an initial application, we aimed to automate our PSQA workflow that involves Varian Eclipse treatment planning system, Elekta MOSAIQ oncology information system and PTW Verisoft application. A general platform, the AutoFrame interface with two imbedded subsystems—the AutoFlow and the PyFlow, was developed with a scripting language for automating human operations of aforementioned systems. The interface included three functional modules: GUI module, UDF script interpreter and TCP/IP communication module. All workstations in the PSQA process were connected, and most manual operations were automated by AutoFrame sequentially or in parallel. Results: More than 20 PSQA tasks were performed both manually and using the developed AutoFrame interface. On average, 175 (±12) manual operations of the PSQA procedure were eliminated and performed by the automated process. The time to complete a PSQA task was 8.23 (±0.78) minutes for the automated workflow, in comparison to 13.91 (±3.01) minutes needed for manual operations. Conclusion: We have developed the AutoFrame interface framework that successfully automated our PSQA procedure, and significantly reduced the time, human (control/clicking/typing) errors, and operators’ stress. Future work will focus on improving the system’s flexibility and stability and extending its operations to other QA procedures.

Real-Time Patient-Specific ECG Arrhythmia Detection by Quantum Genetic Algorithm of Least Squares Twin SVM

The automatic detection of cardiac arrhythmias through remote monitoring is still a challenging task since electrocardiograms(ECGs)are easily contaminated by physiological artifacts and external noises,and these morphological characteristics show significant variations for different patients.A fast patient-specific arrhythmia diagnosis classifier scheme is proposed,in which a wavelet adaptive threshold denoising is combined with quantum genetic algorithm(QAG)based on least squares twin support vector machine(LSTSVM).The wavelet adaptive threshold denoising is employed for noise reduction,and then morphological features combined with the timing interval features are extracted to evaluate the classifier.For each patient,an individual and fast classifier will be trained by common and patient-specific training data.Following the recommendations of the Association for the Advancements of Medical Instrumentation(AAMI),experimental results over the MIT-BIH arrhythmia benchmark database demonstrated that our proposed method achieved the average detection accuracy of 98.22%,99.65%and 99.41%for the abnormal,ventricular ectopic beats(VEBs)and supra-VEBs(SVEBs),respectively.Besides the detection accuracy,sensitivity and specificity,our proposed method consumes the less CPU running time compared with the other representative state of the art methods.It can be ported to Android based embedded system,henceforth suitable for a wearable device.

Influence of Clip Locations on Intraaneurysmal Flow Dynamics in Patient-specific Anterior Communicating Aneurysm Models with Different Aneurysmal Angle

To improve aneurysm treatment,this study examined the influence of clip locations on hemodynamic factors in patient-specific anterior communicating artery(ACoA)aneurysms with different aneurysmal angle.We proposed a simplified classification of ACoA aneurysms using aneurysmal angle,defined by the angle of pivot of the aneurysmal dome and the virtual two-dimensional plane created by both proximal A2 segments of anterior cerebral artery(ACA).ACoA aneurysms with three different aneurysmal angles,which are 15°,80°and 120°,were analyzed in our study.In this work,we obtained hemodynamics before and after clipping surgery with three clip locations based on clinical clipping strategies in three ACoA aneurysms with different aneurysm angles.Results showed that local high pressure occurs at impingement region of the ACoA aneurysm before clipping and new impingement region close to the clipping location after clipping treatment.For clipping the aneurysm with aneurysmal angle 15°and a wide neck,wall shear stress(WSS)distribution is more uniform when the clipping angle of two clips close to 180°comparing with other two angles.In addition,for clipping the aneurysm with aneurysmal angle 80°and 120°,local high pressure appears on new impingement region and high WSS distributes around the clipping location when the clip plane is normal to the direction of inflow of aneurysm from the dominance of A1 segment of ACA.Hence,we should avoid the impingement of inflow from the A1 segment and choose a favorable clipping location for the fastness of clip.The results of our study could preoperatively give a useful information to the decision of surgical plan.

Indirect printing of hierarchical patient-specific scaffolds for meniscus tissue engineering

The complex meniscus tissue plays a critical role in the knee. The high susceptibility to injury has led to an intense pursuit for better tissue engineering regenerative strategies, where scaffolds play a major role. In this study, indirect printed hierarchical multilayered sca ffolds composed by a silk fibroin (SF) upper layer and an 80/20 (w/w) ratio of SF/ionic-doped β-tricalcium phosphate (TCP) bottom layer were developed. Furthermore, a comparative analysis between two types of sca ffolds pro- duced using di fferent SF concentrations, i.e., 8% (w/v) (Hi8) and 16% (w/v) (Hi16) was performed. In terms of architecture and morphology, the produced sca ffolds presented homogeneous porosity in both layers and no di fferences were observed when comparing both sca ffolds. A decrease in terms of mechanical performance of the sca ffolds was observed when SF concentration decreased from 16 to 8% (w/v). Hi16 revealed a static compressive modulus of 0.66 ± 0.05 MPa and dynamical mechanical properties ranging from 2.17 ± 0.25 to 3.19 ± 0.38 MPa. By its turn, Hi8 presented a compressive modulus of 0.27 ± 0.08 MPa and dynamical mechanical properties ranging from 1.03 ± 0.08 MPa to 1.56 ± 0.13 MPa. In vitro bioactivity studies showed formation of apatite crystals onto the surface of Hi8 and Hi16 bottom layers. Human meniscus cells (hMCs) and human primary osteoblasts were cultured separately onto the top layer (SF8 and SF16) and bottom layer (SF8/TCP and SF16/TCP) of the hierarchical sca ffolds Hi8 and Hi16, respectively. Both cell types showed good adhesion and proliferation as denoted by the live/dead staining, Alamar Blue assay and DNA quanti fication analysis. Subcutaneous implantation in mice revealed weak in flammation and sca ffold’s integrity. The hierarchical indirect printed SF sca ffolds can be promising candidate for meniscus TE sca ffolding applications due their suitable mechanical properties, good biological performance and possibility of being applied in a patient-speci fic approach.

Computerised tomography vs magnetic resonance imaging for modeling of patient-specific instrumentation in total knee arthroplasty

AIM: To summarise and compare currently available evidence regarding accuracy of pre-operative imaging, which is one of the key choices for surgeons contemplating patient-specific instrumentation(PSI) surgery.METHODS: The MEDLINE and EMBASE medical literature databases were searched, from January 1990 to December 2013, to identify relevant studies. The data from several clinical studies was assimilated to allow appreciation and comparison of the accuracy of each modality. The overall accuracy of each modality was calculated as proportion of outliers > 3% in the coronal plane of both computerised tomography(CT) or magnetic resonance imaging(MRI). RESULTS: Seven clinical studies matched our inclusion criteria for comparison and were included in our study for statistical analysis. Three of these reported series using MRI and four with CT. Overall percentage of outliers > 3% in patients with CT-based PSI systems was 12.5% vs 16.9% for MRI-based systems. These results were not statistically significant. CONCLUSION: Although many studies have been undertaken to determine the ideal pre-operative imaging modality, conclusions remain speculative in the absence of long term data. Ultimately, information regarding accuracy of CT and MRI will be the main determining factor. Increased accuracy of pre-operative imaging could result in longer-term savings, and reduced accumulated dose of radiation by eliminating the need for post-operative imaging and revision surgery.

A Systematic Approach for Making 3D-Printed Patient-Specific Implants for Craniomaxillofacial Reconstruction

Craniomaxillofacial reconstruction implants,which are extensively used in head and neck surgery,are conventionally made in standardized forms.During surgery,the implant must be bended manually to match the anatomy of the individual bones.The bending process is time-consuming,especially for inexperienced surgeons.Moreover,repetitive bending may induce undesirable internal stress concentration,resulting in fatigue under masticatory loading in v iv o and causing various complications such as implant fracture,screw loosening,and bone resorption.There have been reports on the use of patient-specific 3D-printed implants for craniomaxillofacial reconstruction,although few reports have considered implant quality.In this paper,we present a systematic approach for making 3D-printed patientspecific surgical implants for craniomaxillofacial reconstruction.The approach consists of three parts:First,an easy-to-use design module is developed using Solidworks®software,which helps surgeons to design the implants and the axillary fixtures for surgery.Design engineers can then carry out the detailed design and use finite-element modeling(FEM)to optimize the design.Second,the fabrication process is carried out in three steps:0 testing the quality of the powder;(2)setting up the appropriate process parameters and running the 3D printing process;and (3)conducting post-processing treatments(i.e.,heat and surface treatments)to ensure the quality and performance of the implant.Third,the operation begins after the final checking of the implant and sterilization.After the surgery,postoperative rehabilitation follow-up can be carried out using our patient tracking software.Following this systematic approach,we have successfully conducted a total of 41 surgical cases.3D-printed patient-specific implants have a number of advantages;in particular,their use reduces surgery time and shortens patient recovery time.Moreover,the presented approach helps to ensure implant quality.

Patient-specific instrumentation in total ankle arthroplasty

The recent increase in the adoption of total ankle arthroplasty(TAA)reflects the improvements in implant designs and surgical techniques,including the use of preoperative navigation system and patient-specific instrumentation(PSI),such as custom-made cutting guides.Cutting guides are customized with respect to each patient's anatomy based on preoperative ankle computed tomography scans,and they drive the saw intra-operatively to improve the accuracy of bone resection and implant positioning.Despite some promising results,the main queries in the literature are whether PSI improves the reliability of achieving neutral ankle alignment and more accurate implant sizing,whether it is actually superior over standard techniques,and whether it is cost effective.Moreover,the advantages of PSI in clinical outcomes are still theoretical because the current literature does not allow to confirm its superiority.The purpose of this review article is therefore to assess the current literature on PSI in TAA with regard to current implants with PSI,templating and preoperative planning strategies,alignment and sizing,clinical outcomes,cost analysis,and comparison with standard techniques.

Patient-Specific QA of Spot-Scanning Proton Beams Using Radiochromic Film

Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. A calibration using an EBT3 film, exposed by a 6-level step-wedge plan on a Proteus®PLUS proton system (IBA, Belgium), was performed at depths of 18, 20, 24 cm using Plastic Water®(CIRS, Norfolk, VA). The calibration doses ranged from 65 - 250 cGy (RBE) (relative biological effectiveness) for proton energies of 170 - 200 MeV. A clinical prostate + nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using one-scan protocol (one-scan digitization of QA film and at least one film exposed to a known dose). The gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film and IBA MatriXX-PT, versus the RayStation TPS calculations were analyzed and compared. The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ~95% for 2%/2 mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, for relative dosimetry (calibration is not done at the time of experiment), it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. The use of a proton step-wedge for calibration of EBT3 film potentially increases efficiency in patient-specific QA of proton beams.

MRI-Based Patient-Specific Left Ventricular Model to Determine the Effects of Trabeculae Carneae on the Diastolic and Systolic Functions

Introduction Trabeculae carneae are irregular structures that cover the endocardial surfaces of both ventricles of human heart and account for a significant portion of the ventricular mass.However,the role of trabeculae carneae in left ventricular(LV)function is not well understood.Previous reports suggested that trabeculae help squeeze blood from the apical region during systole[1].Our recent study suggests that trabeculae carneae hypertrophy and fibrosis contribute to increased LV stiffness in patients with diastolic heart failure,and severing free-running trabeculae carneae may improve diastolic compliance of the LV[2].Objective To understand the role of trabeculae carneae in the left ventricular diastolic and systolic functions using anatomically detailed patient-specific finite element models of the human LV.Methods(1)Image acquisition An explanted human heart was collected from a 63 year old female donor with a history of stroke and congestive heart failure within 24 hours postmortem from South Texas Blood and Tissue Center(San Antonio,TX).The heart was de-identified in accordance with Institutional Review Board(IRB)requirements and informed consent for research was obtained from the donor’s family.Three-dimensional MRI scanning was conducted on a 3T(128 MHz)MRI system(TIM Trio,Siemens Medical Solutions),comprised of a superconducting magnet with a 60 cm diameter accessible bore,when the heart was submerged in a saline filled plastic container.(2)Finite element analysis Three distinct LV models were derived from the MR images.The first model was the intact trabeculated model(TM)which contained all trabeculae carneae and papillary muscles.This high-resolution anatomically detailed 3D model of the LV was segmented from 2D MR images in DICOM format using Mimics(Materialise NV,Leuven,Belgium).The second model was the papillary model(PM),in which the papillary muscles remain intact but most of the trabeculae carneae were excluded in the smoothing process.The third model was the smooth model(SM)in which the trabeculae carneae and papillary muscles were excluded during image segmentation.Finite element(FE)models of the TM,PM and SM were created by meshing 3D reconstructions of the acquired MR images using tetrahedral elements(ICEM,Ansys Inc.,Canonsburg,PA).The mesh size was selected after a pilot study on mesh sensitivity.The passive cardiac muscle was characterized as a hyperelastic,incompressible,transversely isotropic material with a Fung exponential strain energy function.The material constants were determined by matching the end-diastolic pressure-volume relationship with the empirical Klotz relation[3].A rule-based myocardial fiber algorithm was adopted to generate the myofiber directions [4].The active contraction(i.e.,systolic contraction)was modeled by the time varying'Elastance'active contraction model.The contractile parameter Tmax was determined and calibrated so that the FE predicted ejection fraction(EF)of TM matched the EF of a normal human heart at the specified end-systolic pressure[3].The analysis of the TM,PM,and SM models were implemented using the open-source finite element package FEBio(www.febio.org).In all models,the rigid body motion was suppressed by constraining the base from moving in all directions.The end-diastolic and end-systolic pressure-volume relationships(EDPVR and ESPVR)were obtained and characterized by an exponential function and the slope,respectively.Results Our simulation results showed that independent of the material model,the EDPVR curve shifts to the right in PM and SM compared to TM.However,the ESPVR curve may shift to the right or left in PM compared to TM,while shifting tothe right in SM for all material models.EDPVR was steeper in TM compared to PM and SM;however,ESPVR was found to be steeper in PM than in TM and SM.The predicted parameters of EDPVR and ESPVR showed lower average exponential term in PM and SM compared to TM,indicating a significant improvement in the compliance and global diastolic function of less trabeculated LV models(P<0.01).Similarly,the higher average elastance EEs and lower volume intersect in PM compared to TM,suggests that mild cutting of trabeculae carneae slightly improves the global systolic function of the LV(P=0.89).However,cutting all trabeculae carneae and papillary muscles in SM had a significant adverse effect on the global systolic function(P<0.01).Discussion and conclusions Most patient-specific LV studies in the literature have used smoothed ventricular geometries.We used high resolution MRI to capture the endocardial details of the LV.Though reproducing very fine trabeculae carneae was restricted by the MRI resolution,our results demonstrated the importance of considering endocardial structures,i.e.papillary muscles and trabeculae carneae,in the assessment of LV global function in patient-specific computational LV models.The present work is consistent with the observation that diastolic performance improved after severing trabeculae carneae due to a reduction in LV stiffness[2].Furthermore,our results also suggest that severing trabeculae carneae(without affecting papillary muscle)may improve LV systolic function.Our model results are consistent with experimental measurements using ex vivo rabbit heart perfusion [5].This improvement would be greater in hypertrophic hearts because trabeculae carneae are also hypertrophic and more fibrotic.Left ventricular hypertrophy is often associated with heart failure with preserved ejection fraction(HFpEF).There is no effective treatment for HFpEF,which is characterized by impaired diastolic relaxation due to increased LV stiffness.Our results indicate that trabecular cutting could be an effective treatment for HFpEF.

Study of Effect of Boundary Conditions on Patient-Specific Aortic Hemodynamics

Cardiovascular computational fluid dynamics(CFD)based on patient-specific modeling is increasingly used to predict changes in hemodynamic parameters before or after surgery/interventional treatment for aortic dissection(AD).This study investigated the effects of flow boundary conditions(BCs)on patient-specific aortic hemodynamics.We compared the changes in hemodynamic parameters in a type A dissection model and normal aortic model under different BCs:inflow from the auxiliary and truncated structures at aortic valve,pressure control and Windkessel model outflow conditions,and steady and unsteady inflow conditions.The auxiliary entrance remarkably enhanced the physiological authenticity of numerical simulations of flow in the ascending aortic cavity.Thus,the auxiliary entrance can well reproduce the injection flow fromthe aortic valve.In addition,simulations of the aortic model reconstructed with an auxiliary inflow structure and pressure control and the Windkessel model outflow conditions exhibited highly similar flow patterns and wall shear stress distribution in the ascending aorta under steady and unsteady inflow conditions.Therefore,the inflow structure at the valve plays a crucial role in the hemodynamics of the aorta.Under limited time and calculation cost,the steady-state study with an auxiliary inflow valve can reasonably reflect the blood flow state in the ascending aorta and aortic arch.With reasonable BC settings,cardiovascular CFD based on patient-specific ADmodels can aid physicians in noninvasive and rapid diagnosis.

Application of 3D printed patient-specific instrumentation in distal tibial tuberosity-high tibial osteotomy

Objective:To observe the clinical efficacy and advantages of 3D printed patient-specific instrumentation(PSI)assisted distal tibial tuberosity-high tibial osteotomy in the treatment of medial compartment knee osteoarthritis.Methods:75 patients with medial compartment knee osteoarthritis were included in the study performed DTT-HTO in our hospital from August 2017 to August 2019.The patients were divided into the PSI group(n=39)and conventional group(n=36)According to whether PSI was used in surgery.The differences of lateral cortical fracture rate,time of intraoperative X-ray exposure,intraoperative blood loss,operative time,weight bearing line(WBL),Posterior tibial slope(PTS)and Caton-Deschamps index(CDI)were compared between the two groups.Visual analogue scale(VAS)scores and Hospital for Special Surgery(HSS)scores were recorded to evaluate knee pain and function before surgery and after surgery at 3 months and 12 months.Results:All 75 patients were followed up for more than 12 months,the ranged from 12-26(18.74±6.21)months.Three lateral cortical fractures in the conventional group and no fracture in PSI group.The lateral cortical fracture rate,time of intraoperative X-ray exposure,intraoperative blood loss,operative time in PSI group were lower than those in conventional group(p敿0.05).WBL in two groups were significantly improved after surgery(p敿0.05),and PTS,CDI were no statistically improved after surgery(p>0.05).While there was no statistically significant difference with WBL,PTS and CDI between two groups(p>0.05).At 1 months,3 months and 12 months after surgery;VAS and HSS scores in both groups were significantly improved compared with that before surgery(p0.05),and were no statistically significant difference between two groups.Conclusion:3D printed patient-specific instrumentation assisted DTT-HTO has significant clinical efficacy,and effectively standardized surgical procedures,meanwhile reduced the time of intraoperative X-ray exposure,intraoperative blood loss and risk of lateral cortical fracture.

<i>In vitro</i>measurement of tibiofemoral kinematics after patient-specific unicompartmental knee replacement

It is suggested that unicompartmental knee replacement (UKR) offers the potential to restore normal knee kinematics better than total knee replacement (TKR) because of retaining the cruciate ligaments, and better preservation of the overall geometry. It was hypothesized that patient-specific UKR would restore normal knee kinematics even better because of a customised articular shape. A comparative kinematics study was conducted on three cadaver limbs using two different test setups, a loaded ankle rig and an unloaded ankle rig. Kinematics was compared between a patient-specific UKR and a conventional fixed-bearing UKR. Both the UKRs showed similar kinematic patterns to the normal knee using both the test apparatus. The patient-specific UKR showed good results and with the other benefits it shows potential to dramatically improve clinical outcomes of knee replacement surgery.

Evaluation of Patient-Specific Quality Assurance for Carbon Ion Radiotherapy Using Full Energy Scanning Method at QST Hospital

Purpose: Patient-specific QA (PSQA) measurements for carbon ion radiotherapy (CIRT) are critical components of processes designed to identify discrepancies between calculated and delivered doses. We report the results of PSQA conducted at the QST Hospital during the period from September 2017 to March 2018. Methods: We analyzed PSQA results for 1448 fields for 10 disease sites with various target volumes, target depths and number of energy layers. For the PSQA, all the planned beams were recalculated on a water phantom with treatment planning software. The recalculated dose distributions were compared with the measured distributions using a 2D ionization chamber array at three depths, including 95% of the area of the prescription dose. These recalculated dose distributions were evaluated using the 3%/3mm gamma index with a passing threshold of 90%. Results: The passing rates for prostate, head and neck, and bone and soft tissue were 96.8%, 99.3%, and 91.7%, respectively. Additionally, 94.7% of lung plans with low energy beams passed. Overall, the CIRT in the QST Hospital reached a high passing rate of more than 95%. Although the remaining 5% failed to pass, there was no dependence between measurement depth and disease sites in these failures. Conclusion: Using PSQA measurements, we confirmed consistency between the planned and delivered doses for CIRT using the full energy scanning method.

Computer-Assisted Surgery for Mandibular Reconstruction Using a Patient-Specific Titanium Mesh Tray and Particulate Cancellous Bone and Marrow

Craniomaxillofacial surgery is difficult due to the complexity of the regional anatomy. Computer-assisted surgery is a promising tool aiming to improve the safety and precision of such surgery. A computer-assisted surgical navigation approach for reconstruction of mandibular defects using a patient-specific titanium mesh tray and particulate cancellous bone and marrow (PCBM) harvested from bilateral anterior ilia is proposed. This case report involves a large multicystic ameloblastoma affecting the right mandible of a 31-year-old male patient. Following detailed clinical examination, radiological interpretation, and histopathological diagnosis, computer-assisted surgical simulation with a virtual 3-dimensional (3-D) model was designed using surgical planning software based on the pre-operative computed tomography data. Long-span segmental resection of the mandible was planned, and the defect was analyzed for reconstruction using a patient-specific reconstruction titanium mesh tray mediated with computer-aided design and manufacturing (CAD/CAM) techniques. During the actual surgery, the ultrasonic bone cutting instrument in the surgeon’s hand was connected to the navigation system to touch an anatomical position on the patient. Therefore, osteotomies were performed finely and smoothly according to the navigation images of the cutting bone line by sequentially moving the instrument. Finally, a CAD/CAM-mediated titanium mesh tray condensed by PCBM was adapted to the remaining mandibular fragments. Six months postoperatively, the patient had a good mandibular configuration and facial contour. Integration of different technologies, such as software planning and 3-D surgical simulation, combined with intraoperative navigation and CAD/CAM techniques, provides safe and precise mandibular reconstruction surgery.

Postoperative Mechanical Axis Alignment and Components Position after Conventional and Patient-Specific Total Knee Arthroplasty

Introduction: Accurate postoperative alignment and implant positioning are determinant factors for successful total knee arthroplasty (TKA). Patient-specific template (PST) is a technique that uses computer technology for the planning, deigning and production of cutting guides. This study aims to compare PST to conventional technique in terms of mechanical axis alignment and component positioning. Patients and method: 109 TKA were performed for 78 patients in 2 groups. Group A included 69 conventional TKA in 55 patients and Group B included 40 patient-specific TKA in 23 patient. Postoperative long-film X-rays were done for all patients to observe the mechanical axis, anatomical axis, lateral distal femoral mechanical angle and medial proximal tibial angle. Results: No statistically significant difference was found between the two groups regarding alignment or component positioning. Conclusion: Both techniques have shown similar results in restoring the mechanical axis and alignment after TKA. However, PST had the advantages of reduced blood loss and shorter operative time.

Patient-Specific Instruments Based on Knee Joint Computed Tomography and Full-Length Lower Extremity Radiography in Total Knee Replacement

Background： Restoring good alignment after total knee replacement （TKR） is still a challenge globally, and the clinical efficiency of patient-specific instruments （PSIs） remains controversial. In this study, we aimed to explore the value and significance of three-dimensional printing PSls based on knee joint computed tomography （CT） and full-length lower extremity radiography in TKR. Methods： Between June 2013 and October 2014, 31 TKRs were performed using PSIs based on knee joint CT and full-length lower extremity radiography in 31 patients （5 males and 26 females; mean age： 67.6 ± 7.9 years, body mass index [BMI]： 27.4 ±3.5 kg/m2）. Thirty-one matched patients （4 males and 27 females; mean age： 67.4± 7.2 years; mean BM 1：28.1 ± 4.6 kg/m2） who underwent TKR using conventional instruments in the same period served as the control group. The mean follow-up period was 38 months （31-47 months）. Knee Society Score （KSS）, surgical time, and postoperative drainage volume were recorded. Coronal alignment was measured on full-length radiography. Results： Twenty-three （74.2%） and 20 （64.5%） patients showed good postoperative alignment in the PSI and control groups, respectively, without significant difference between the two groups （χ2 = 0.68, P = 0.409）. The mean surgical time was 81.48± 16.40 rain and 72.90 ± 18.10 min for the PSl and control groups, respectively, without significant difference between the two groups （t = 0.41, P = 0.055）. The postoperative drainage volume was 250.9 ± 148.8 ml in the PSI group, which was significantly less than that in the control group （602. 1± 230.6 ml, t = 6.83, P 〈 0.001）. No significant difference in the KSS at the final follow-up was found between the PSI and control groups （91.06 ± 3.26 vs. 90.19±3.84, t= 0.95, P=0.870）. Conclusions： The use of PSls based on knee joint CT and standing full-length lower extremity radiography in TKR resulted in acceptable alignment compared with the use of conventional instruments, although the marginal advantage was not statistically different. Surgical time and clinical results were also similar between the two groups, However, the PSI group had less postoperative drainage.

NON-NEWTONIAN COMPUTATIONAL HEMODYNAMICS IN TWO PATIENT-SPECIFIC CEREBRAL ANEURYSMS WITH DAUGHTER SACCULES

Hemodynamic factors play important roles in the formation, progression and rupture of cerebral aneurysms, and the Wall Shear Stress （WSS） and Oscillatory Shear Index （OSI） on the aneurysms are considered to be correlated with their growth and rupture. In this article, two computational models based on patient-specific cerebral aneurysms with daughter saccule are constructed from 3D-RA image data, one is lateral aneurysm located in middle cerebral artery （CA1） and the other is terminal aneurysm located in anterior communicating artery （CA2）, The corresponding models of the two aneurysms by removing daughter saccule are established in order to investigate the initiation and growth of the daughter saccule. The flow patterns and the distributions of hemodynamic factors in the two aneurysms before and after daughter saccule is removed are obtained by solving the governing equations with the commercial CFD software Ansys CFX11.0 under the non-Newtonian fluid assumption. By analyzing the flow patterns, it is concluded that the aneurysms with daughter saccules have more complex and unstable flow patterns and hence are prone to rupture. By comparing the distribution of OSI, a hypothesis that a high OSI causes the growth of the daughter saccule is presented.

Hemodynamics in Transplant Renal Artery Stenosis and its Alteration after Stent Implantation Based on a Patient-specific Computational Fluid Dynamics Model

Background： Accumulating studies on computational fluid dynamics （CFD） support the involvement of hemodynamic factors in artery stenosis. Based on a patient-specific CFD model, the present study aimed to investigate the hemodynamic characteristics of transplant renal artery stenosis （TRAS） and its alteration after stent treatment. Methods： Computed tomography angiography （CTA） data of kidney transplant recipients in a single transplant center from April 2013 to November 2014 were reviewed. The three-dimensional geometry of transplant renal artery （TRA） was reconstructed from the qualified CTA images and categorized into three groups： the normal, stenotic, and stented groups. Hemodynamic parameters including pressure distribution, velocity, wall shear stress （WSS）, and mass flow rate （MFR） were extracted. The data of hemodynamic parameters were expressed as median （interquartile range）, and Mann-Whitney U-test was used for analysis. Results： Totally, 6 normal, 12 stenotic, and 6 stented TRAs were included in the analysis. TRAS presented nonuniform pressure distribution, adverse pressure gradient across stenosis throat, flow vortex, and a separation zone at downstream stenosis. Stenotic arteries had higher maximal velocity and maximal WSS （2.94 [2.14, 3.30] vs. 1.06 /0.89, 1.15] m/s, 256.5 [149.8, 349.4] vs. 41.7 [37.8, 45.3] Pa at end diastole, P - 0.001 ; 3.25 [2.67, 3.56] vs. 1.65 [ 1.18, 1.72] m/s, 281.3 [ 184.3,364.7] vs. 65.8 [61.2, 71.9] Pa at peak systole, P - 0.001 ） and lower minimal WSS and MFRs （0.07 [0.03, 0.13] vs. 0.52 [0.45, 0.67] Pa, 1.5 [1.0, 3.0] vs. 11.0 [8.0, 11.3] g/s at end diastole, P = 0.001 ; 0.08 [0.03, 0.19] vs. 0.70 [0.60, 0.81] Pa, 2.0 [1.3, 3.3] vs. 16.5 [13.0, 20.3] g/s at peak systole, P 0.001） as compared to normal arteries. Stent implantation ameliorated all the alterations of the above hemodynamic factors except low WSS. Conclusions： Hemodynamic factors were significantly changed in severe TRAS. Stent implantation can restore or ameliorate deleterious change of hemodynamic factors except low WSS at stent regions.

Patient-specific modeling of left ventricle mechanics

We present a computational framework for the study of cardiac motion.The bio-mechanical model captures the passive and active properties of the cardiac tissue as well as the fiber architecture.We focus on the analysis of deformations of a beating left ventricle(LV),comparing numerical simulations with real data acquired by echocardiography.The goal is to determine the clinical relevance of the LV strains pattern and to investigate the relationships between that pattern and the arrangement of myocardial fibers.The proposed framework could in principle be used for a wide range of clinical applications.

Image Registration Technique for Assessing the Accuracy of Intraoperative Osteotomy for Pelvic Tumors by 3D-Printed Patient-Specific Templates

The study aimed to explore the feasibility of an image registration technique for assessing the accuracy of intraoperative osteotomy of pelvic tumors by 3-dimensional(3D)-printed patient-specific templates.Patients with malignant pelvic tumors who were admitted to our hospital between March 2014 and December 2020 were retrospectively enrolled.Patients underwent hemi-pelvic resection and reconstruction by 3D-printed individualized prostheses.The registration between the designed model and the postoperative segmented model of the prosthesis was used to obtain the intraoperative osteotomy plane and reduce metal artifacts in postoperative computed tomography(CT)images.The distance and angle between the planned and actual osteotomy planes were then used to assess the accuracy of the intraoperative osteotomy.Eight patients with 13 osteotomy planes were enrolled,including four males and four females.The median age at the time of imaging examination was 44 years(range,33–54 years).All intraoperative osteotomy planes were assessed successfully.The mean distance between the planned and true intraoperative osteotomy planes was−0.69 cm(−7.5–7.35 cm),and the mean angle was 6.57°±3.36°(1.05°–11.88°).This new assessment method of registering the designed model and the postoperative CT segmented model of the prosthesis may be used to assess the accuracy of intraoperative osteotomy for pelvic tumors,using 3D printed patient-specific templates.