Diagnostic efficacy of virtual organ computer-assisted analysis in measuring the volume ratio of subchorionic hematoma with serum progesterone

BACKGROUND Subchorionic hematoma(SCH)is a common complication in early pregnancy characterized by the accumulation of blood between the uterine wall and the chorionic membrane.SCH can lead to adverse pregnancy outcomes such as miscarriage,preterm birth,and other complications.Early detection and accurate assessment of SCH are crucial for appropriate management and improved pregnancy outcomes.AIM To evaluate the diagnostic efficacy of virtual organ computer-assisted analysis(VOCAL)in measuring the volume ratio of SCH to gestational sac(GS)combined with serum progesterone on early pregnancy outcomes in patients with SCH.METHODS A total of 153 patients with SCH in their first-trimester pregnancies between 6 and 11 wk were enrolled.All patients were followed up until a gestational age of 20 wk.The parameters of transvaginal two-dimensional ultrasound,including the circumference of SCH(Cs),surface area of SCH(Ss),circumference of GS(Cg),and surface area of GS(Sg),and the parameters of VOCAL with transvaginal three-dimensional ultrasound,including the three-dimensional volume of SCH(3DVs)and GS(3DVg),were recorded.The size of the SCH and its ratio to the GS size(Cs/Cg,Ss/Sg,3DVs/3DVg)were recorded and compared.RESULTS Compared with those in the normal pregnancy group,the adverse pregnancy group had higher Cs/Cg,Ss/Sg,and 3DVs/3DVg ratios(P<0.05).When 3DVs/3DVg was 0.220,the highest predictive performance predicted adverse pregnancy outcomes,resulting in an AUC of 0.767,and the sensitivity,specificity were 70.2%,75%respectively.VOCAL measuring 3DVs/3DVg combined with serum progesterone gave a diagnostic AUC of 0.824 for early pregnancy outcome in SCH patients,with a high sensitivity of 82.1%and a specificity of 72.1%,which showed a significant difference between AUC.CONCLUSION VOCAL-measured 3DVs/3DVg effectively quantifies the severity of SCH,while combined serum progesterone better predicts adverse pregnancy outcomes.

Computer-assisted three-dimensional individualized extreme liver resection for hepatoblastoma in proximity to the major liver vasculature

BACKGROUND The management of hepatoblastoma(HB)becomes challenging when the tumor remains in close proximity to the major liver vasculature(PMV)even after a full course of neoadjuvant chemotherapy(NAC).In such cases,extreme liver resection can be considered a potential option.AIM To explore whether computer-assisted three-dimensional individualized extreme liver resection is safe and feasible for children with HB who still have PMV after a full course of NAC.METHODS We retrospectively collected data from children with HB who underwent surgical resection at our center from June 2013 to June 2023.We then analyzed the detailed clinical and three-dimensional characteristics of children with HB who still had PMV after a full course of NAC.RESULTS Sixty-seven children diagnosed with HB underwent surgical resection.The age at diagnosis was 21.4±18.8 months,and 40 boys and 27 girls were included.Fifty-nine(88.1%)patients had a single tumor,39(58.2%)of which was located in the right lobe of the liver.A total of 47 patients(70.1%)had PRE-TEXT III or IV.Thirty-nine patients(58.2%)underwent delayed resection.After a full course of NAC,16 patients still had close PMV(within 1 cm in two patients,touching in 11 patients,compressing in four patients,and showing tumor thrombus in three patients).There were 6 patients of tumors in the middle lobe of the liver,and four of those patients exhibited liver anatomy variations.These 16 children underwent extreme liver resection after comprehensive preoperative evaluation.Intraoperative procedures were performed according to the preoperative plan,and the operations were successfully performed.Currently,the 3-year event-free survival of 67 children with HB is 88%.Among the 16 children who underwent extreme liver resection,three experienced recurrence,and one died due to multiple metastases.CONCLUSION Extreme liver resection for HB that is still in close PMV after a full course of NAC is both safe and feasible.This approach not only reduces the necessity for liver transplantation but also results in a favorable prognosis.Individualized three-dimensional surgical planning is beneficial for accurate and complete resection of HB,particularly for assessing vascular involvement,remnant liver volume and anatomical variations.

Computer-assisted rescue of the inferior mesenteric artery in a child with a giant ganglioneuroblastoma: A case report

BACKGROUND Ganglioneuroblastoma(GNB)is a peripheral neuroblastoma(NB)with malignant degree between highly malignant NB and benign ganglioma(GN).Pathology is the gold standard of diagnosis.Although GNB is not uncommon in children,biopsy alone may lead to an inaccurate diagnosis,especially for giant tumors.However,surgical resection may be associated with significant complications.Here,we report a case of computer-assisted surgical resection of a giant GNB in a child and successful rescue of the inferior mesenteric artery.CASE SUMMARY A 4-year-old girl was admitted to our department for a giant retroperitoneal lesion,which was considered to be an NB by her local hospital.The symptoms of the girl disappeared spontaneously without treatment.On physical examination,a mass of about 10 cm×7 cm could be palpated in her abdomen.Ultrasonography and contrast-enhanced computed tomography performed in our hospital also showed an NB,and there was a very thick blood vessel inside the tumor.However,aspiration biopsy revealed GN.Surgical resection is the best treatment option for this giant benign tumor.For precise preoperative evaluation,threedimensional reconstruction was performed.It was clear that the tumor was close to the abdominal aorta.The superior mesenteric vein was pushed forward,and the inferior mesenteric artery passed through the tumor.Because GN generally does not invade blood vessels,we split the tumor with a CUSA knife during the operation and found that there was indeed a straight and intact vascular sheath.Arterial pulsation was observed in the completely exposed inferior mesenteric artery.The pathologists interpreting the tissue finally diagnosed it as a mixed GNB(GNBi),which is more malignant than GN.However,both GN and GNBi usually have a good prognosis.CONCLUSION This was a case of successful surgical resection of a giant GNB,and aspiration biopsy underestimated the pathological staging of the tumor.Preoperative three-dimensional reconstruction assisted with the radical resection of the tumor and rescue of the inferior mesenteric artery.

Computer-assisted Surgery for Scaphoid Fracture

The computer-assisted surgery (CAS)has significantly improved the accuracy, reliability and outcomes of traumatic,spinal,nerve surgery and many other operations with a less invasive way.The application of CAS for scaphoid fractures remains experimental.The related studies are scanty and most of them are cadaver researches.Some intrinsic defects from the registration procedure,scan and immobilization of limbs may inevitably result in deviations. Some deviations become more obvious with operations of small bones (such as scaphoid)although they are acceptable for spine and other orthopedic surgeries.We reviewed the current literatures on the applications of CAS for scaphoid operation and summarized technical principles,scan and registration methods,immobilization of limbs and their outcomes.On the basis of the data,we analyzed the limitations of this technique and envisioned its future development.

Establishment and validation of a computer-assisted colonic polyp localization system based on deep learning

BACKGROUND Artificial intelligence in colonoscopy is an emerging field,and its application may help colonoscopists improve inspection quality and reduce the rate of missed polyps and adenomas.Several deep learning-based computer-assisted detection(CADe)techniques were established from small single-center datasets,and unrepresentative learning materials might confine their application and generalization in wide practice.Although CADes have been reported to identify polyps in colonoscopic images and videos in real time,their diagnostic performance deserves to be further validated in clinical practice.AIM To train and test a CADe based on multicenter high-quality images of polyps and preliminarily validate it in clinical colonoscopies.METHODS With high-quality screening and labeling from 55 qualified colonoscopists,a dataset consisting of over 71000 images from 20 centers was used to train and test a deep learning-based CADe.In addition,the real-time diagnostic performance of CADe was tested frame by frame in 47 unaltered full-ranged videos that contained 86 histologically confirmed polyps.Finally,we conducted a selfcontrolled observational study to validate the diagnostic performance of CADe in real-world colonoscopy with the main outcome measure of polyps per colonoscopy in Changhai Hospital.RESULTS The CADe was able to identify polyps in the test dataset with 95.0%sensitivity and 99.1%specificity.For colonoscopy videos,all 86 polyps were detected with 92.2%sensitivity and 93.6%specificity in frame-by-frame analysis.In the prospective validation,the sensitivity of CAD in identifying polyps was 98.4%(185/188).Folds,reflections of light and fecal fluid were the main causes of false positives in both the test dataset and clinical colonoscopies.Colonoscopists can detect more polyps(0.90 vs 0.82,P<0.001)and adenomas(0.32 vs 0.30,P=0.045)with the aid of CADe,particularly polyps<5 mm and flat polyps(0.65 vs 0.57,P<0.001;0.74 vs 0.67,P=0.001,respectively).However,high efficacy is not realized in colonoscopies with inadequate bowel preparation and withdrawal time(P=0.32;P=0.16,respectively).CONCLUSION CADe is feasible in the clinical setting and might help endoscopists detect more polyps and adenomas,and further confirmation is warranted.

Glutathione Peroxidase Revisited—Simulation of the Catalytic Cycle by Computer-Assisted Molecular Modelling

Glutathione peroxidase, the first example of selenoproteins identified in mammals, was subjected to force field calculations and molecular dynamics in order to enable a clearer comprehension of enzymatic selenium catalysis. Starting from the established X-ray structure of bovine GPX, all kinetically defined intermediates and enzyme substrate complexes were modelled. The models thus obtained support the hypothesis that the essential steps of the catalysis are three distinct redox changes of the active site selenium which, in the ground state, presents itself at the surface of selenoperoxidases as the center of a characteristic triad built by selenocysteine, glutarnine and tryptophan. In GPX, four arginine residues and a lysine residue provide an electrostatic architecture which, in each reductive step, directs the donor substrate GSH towards the catalytic center in such a way that 1ts sulfhydryl group must react with the selenium moiety. To this end, different equally efficient modes of substrate binding appear possible. The models are consistent with substrate specificity data, kinetic pattern and other functional characteristics of the enzyme. Comparison of molecular models of GPX with those of other members of the GPX superfamily reveals that the cosubstrate binding mechanisrns are unique for the classical type of cytosolic glutathione peroxidases but cannot operate e. g. in plasma GPX and phospholipid hydroperoxide GPX. The structural differences between the selenoperoxidases, shown to be relevant to their specificities, are discussed in terms of functional diversification within the GPX superfamily

A comparison of conventional and computer-assisted semen analysis.（CRISMAS software） using samples from 166 young Danish men

The aim of the present study was to compare assessments of sperm concentration and sperm motility analysed by conventional semen analysis with those obtained by computer-assisted semen analysis （CASA） （Copenhagen Rigshospitalet Image House Sperm Motility Analysis System （CRISMAS） 4.6 software） using semen samples from 166 young Danish men. The CRISMAS software identifies sperm concentration and classifies spermatozoa into three motility categories. To enable comparison of the two methods, the four motility stages obtained by conventional semen analysis were, based on their velocity classifications, divided into three stages, comparable to the three CRISMAS motility categories： rapidly progressive （A）, slowly progressive （B） and non-progressive （C＋ D）. Differences between the two methods were large for all investigated parameters （P〈0.001）. CRISMAS overestimated sperm concentration and the proportion of rapidly progressive spermatozoa and, consequently, underestimated the percentages of slowly progressive and non-progressive spermatozoa, compared to the conventional method. To investigate whether results drifted according to time of semen analysis, results were pooled into quarters according to date of semen analysis. CRISMAS motility results appeared more stable over time compared to the conventional analysis; however, neither method showed any trends. Apparently, CRISMAS CASA results and results from the conventional method were not comparable with respect to sperm concentration and motility analysis. This needs to be accounted for in clinics using this software and in studies of determinants of these semen characteristics.

Application of a novel computer-assisted surgery system in percutaneous nephrolithotomy:A controlled study

BACKGROUND Most complex renal stones are managed primarily with percutaneous nephrolithotomy(PCNL).However,PCNL is still a great challenge for surgeons because of poor comprehension on complex adjacent structures.Novel techniques are required to assist in planning and navigation.AIM To apply and evaluate the Hisense computer-assisted surgery(CAS)system in PCNL.METHODS A total of 60 patients with complex renal stones were included.Thirty patients in the CAS group had three-dimensional(3 D)virtual models constructed with the CAS system.The model assisted in planning and navigating in the CAS system.Thirty patients in the control group planned and navigated as standard PCNL,without the application of the CAS system.Success rate of one attempt,operation time,initial stone-free rate,decrease in hemoglobin,and complications were collected and analyzed.RESULTS There were no statistically significant differences in the baseline characteristics or planning characteristics.The success rate of one puncturing attempt(90%vs 67%,P=0.028)and the initial stone-free rate(87%vs 63%,P=0.037)were significantly higher in the CAS group.However,there were no statistically significant differences in the operation time(89.20±29.60 min vs 92.33±33.08 min,P=0.859)or in the decrease in hemoglobin(11.07±8.32 g/L vs 9.03±11.72 g/L,P=0.300)between the CAS group and the control group.No statistically significant differences in the incidence of complications(Clavien-Dindo grade≥2)were found.CONCLUSION Compared with standard PCNL,CAS-assisted PCNL had advantages in terms of the puncturing success rate and stone-free rate.The Hisense CAS System was recommended to assist in preoperative planning and intraoperative navigation for an intuitive,precise and convenient PCNL.

Application of computer-assisted navigation in treating congenital maxillomandibular syngnathia:A case report

BACKGROUND Congenital maxillomandibular syngnathia is an extremely rare disorder characterized by craniofacial malformations and inability to open the mouth adequately, which leads to problems with feeding, swallowing, and breathing as well as temporomandibular joint ankylosis. The main goal of the surgery is to release the ankylosis, establish functioning mandible, and prevent re-fusion.However, surgical procedures for this disease are rarely reported.CASE SUMMARY Here, we report a 7-mo-old girl with bilateral maxillomandibular syngnathia. The patient presented with difficulty in feeding, breathing, sounding, and swallowing and had developmental dysplasia. For treatment, we performed bone isolation by computer-assisted navigation and used silicone to fix the wound surface to prevent refusion of bone. To our knowledge, this is the only syngnathia case in the literature treated using computer-assisted navigation. With the guidance of precise navigation, we were able to minimize operation time by at least one hour,the patient's blood vessels, nerves, and tooth germs were well protected, and excessive bleeding was avoided. After six weeks, the patient showed improvement in mouth opening and no major issues of feeding.CONCLUSION Application of computer-assisted navigation can significantly improve accuracy,effectiveness, and surgical safety in correcting congenital maxillomandibular syngnathia.

Novel computer-assisted method for revision arthroplasty of the knee

AIM: To introduce the navigation system of software and instruments designed specifically for revision total knee arthroplasty(TKA).METHODS: We present an imageless navigation system for revision TKA,with optical point and tracker identification to assess kinematic and anatomical landmarks.The system automatically positions the cutting guides with a motorized cutting unit.The cutting unit is placed on the distal femur with a femoral clamp and acts as a rigid body and the base for all femoral cuts.The surgical technique for using the navigation system for revision TKA is based on the technique used in primary TKA.However,there are some important differences.The most notable are:(1) differences in estimation of the position of the primary implant relative to the bone and the mechanical axes;(2) the specific possibilities the revision navigation software offers in terms of optimal joint level positioning; and(3) the suggested "best fit" position,in which the clock position,stem position and offset,femoral component size,and mediolateral position of the femoral component are taken into account to find the optimal femoral component position.We assessed the surgical technique,and accompanying software procedural steps,of the system,identifying any advantages or disadvantages that they present.RESULTS: The system aims to visualize critical steps of the procedure and is intended as a tool to support the surgeon in surgical decision-making.Combining a computer-assisted cutting device with navigation makes it possible to carry out precise cuts without pinning.Furthermore,the femoral clamp provides a stable fixation mechanism for the motorized cutting unit.A stable clamp is paramount in the presence of periarticular bony defects.The system allows the position of the primary implant relative to the bone and mechanical axes to be estimated,at which point any malalignments can be corrected.It also offers an optimal joint level position for implantation,and suggests a "best fit" position,in which the clock position,stem position and offset,femoral component size,and mediolateral position of the femoral component are considered.The surgeon can therefore make decisions intraoperatively to maximise alignment and,hence,outcomes.Based on the intraoperative findings of joint stability,the surgeon can modify the preoperative plan and switch from a constrained condylar system to a hinged version,or vice versa.CONCLUSION: The system is flexible and easy to learn and allows improvements in workflow during TKA.

The Influence of Combining Computer-Assisted Language Learning With Instruction on Chinese College Students’L2 Pragmatic Ability

In the area of computer-assisted language learning(CALL),although a number of studies have adopted various CALL-based devices(e.g.,blogs,gaming,and synthetic environments)to foster second language(L2)acquisition,the vital component of instruction has received little attention.The present study explored the usefulness of CALL-based communication in conjunction with instruction on EFL learners’L2 pragmatic development.Sixty-two EFL students from a university in China were recruited for the current research.The experimental group communicated with a native English speaker through synchronous messaging via Skype and had two instructional sessions pertinent to compliment responses,while the control group interacted with a native English speaker via Skype without having the teaching intervention.Findings from an independent samples t-test demonstrated that the experimental group produced significantly more proper compliment responses in the immediate posttest than the control group(p<.001).Moreover,a significant difference(p<.001)was found for the experimental group between the preintervention and delayed post-intervention mean scores,suggesting that CALL coupled with teaching intervention had a long-term impact on learners’L2 pragmatic development.These findings enrich our understanding of the beneficial and lasting influence of combining CALL with instruction on EFL students’pragmatic development.In addition,pedagogical implications for deploying CALL paired with L2 pragmatics instruction are provided.

A Computer-Assisted Corpus Analysis （CACA） of Professional Discourse

This paper presents CACA （computer-assisted corpus analysis） conducted by using a compiled representative corpus. As a descriptive study, it explores the written communicative events produced by engineers in the petroleum industry in Malaysia. Language use is commonly analyzed for competence and performance. Competence is best described as the internalized linguistic knowledge as acquired by the learners while the notion of＂performance＂ is best defined as the external evidence of language competence. Therefore, the core of this paper is reflecting actual language use of the language learners in Malaysia. The data are drawn from a sample corpus compiled from the written communicative events in three companies of the petroleum industry in Malaysia. The methodology applied is fundamental as it tends to investigate the linguistic constitutions in the genre-specific corpus of the professional discourse produced. Computer-based syntactical studies are limited as they require hard work and long hours in order to key-in the data and then there is the complex analytic method of describing the findings. In contrast, this paper will demonstrate an uncomplicated method of analysis and also encourage the use of existing POS （part-of speech） tagging software available online.

Models for Teaching Culture in Computer-Assisted Language Learning

CALL （computer-assisted language learning） has tremendously transformed the teaching of language, with its wide application in many aspects of language teaching. However, how to integrate CALL into the teaching of culture is still rarely discussed. The purpose of the paper is to explore feasible models for teaching culture in CALL and their effects on students＇ acquisition process. Based on two fundamental pedagogical approaches （participatory pedagogy and multiliteracies pedagogy） for teaching culture, this paper proposes three pedagogical models （problem-posing model, web-quest model, and computer-supported collaborative learning model） for teaching culture in CALL. In the end, this paper illustrates a combination of the three models in real CALL setting by a cultural teaching case. A questionnaire survey and interviews are conducted to reflect on students＇ feedback, which gives an insight into possible adjustments in teaching models and the paper also proposes future possibilities in applying these models into teaching culture

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.

COMPUTER-ASSISTED TESTING OF METALINGUISTIC COMPETENCE

The paper is devoted to the description of possible approaches to designing materials for computer-assisted testing of metalinguistic competence of the intending foreign language teachers. By metalinguistic competence we here mean the learners’ comprehension of such fundamental concepts of linguistic theory as: grammatical and lexical meanings and their types, the concepts of grammatical form and grammatical category, homonyms and synonyms,

Clinical application of improved 2D computer-assisted fluoroscopic navigation through simulating a 3D vertebrae image to guide pedicle screw internal fixation

Objective To study the effect of using improved 2D computer-assisted fluoroscopic navigation through simulating 3D vertebrae image to guide pedicle screw internal fixation.Methods Posterior pedicle screw internal fixation,distraction

Lumbar spine superior-level facet joint violations： percutaneous versus open pedicle screw insertion using intraoperative 3-dimensional computer-assisted navigation

Background Percutaneous pedicle screw use has a high rate of cranial facet joint violations （FVs） because of the facet joint being indirectly visualized.Computer-assisted navigation shows the anatomic structures clearly,and may help to lower the rate of FVs during pedicle screw insertion.This study used computed tomography （CT） to evaluate and compare the incidence of FVs between percutaneous and open surgeries employing computer-assisted navigation for the implantation of pedicle screw instrumentation during lumbar fusions.Methods A prospective study,including 142 patients having lumbar and lumbosacral fusion,was conducted between January 2013 and April 2014.All patients had bilateral posterior pedicle screw-rod instrumentation （top-loading screws） implanted by the same group of surgeons; intraoperative 3-dimensional computer navigation was used during the procedures.All patients underwent CT examinations within 6 months postoperation.The CT scans were independently reviewed by three reviewers blinded to the technique used.Results The cohort comprised 68 percutaneous and 74 open cases （136 and 148 superior-level pedicle screw placements,respectively）.Overall,superior-level FVs occurred in 20 patients （20/142,14.1％）,involving 27 top screws （27/284,9.5％）.The percutaneous technique （7.4％ of patients,3.7％ of top screws） had a significantly lower violation rate than the open procedure （20.3％ of patients,14.9％ of top screws）.The open group also had significantly more serious violations than did the percutaneous group.Both groups had a higher violation rate when the cranial fixation involved the L5.A 1-level open procedure had a higher violation rate than did the 2-and 3-level surgeries.Conclusions With computer-assisted navigation,the placement of top-loading percutaneous screws carries a lower risk of adjacent-FVs than does the open technique; when FVs occur,they tend to be less serious.Performing a single-level open lumbar fusion,or the fusion of the L5-S1 segment,requires caution to avoid cranial adjacent FVs.

Computer-assisted minimally invasive spine surgery for resection of ossification of the ligamentum flavum in the thoracic spine

Background Ossification of the ligamentum flavum （OLF） has been widely recognized as one of the main causes of thoracic spinal canal stenosis and thoracic myelopathy.Decompression is the only effective strategy for treating thoracic myelopathy caused by OLF.The purpose of this study was to describe the clinical outcomes of computer-assisted minimally invasive spine surgery （CAMISS） for posterior decompression in patients with thoracic myelopathy caused by OLF.Methods In all cases,the surgical procedure was performed with the assistance of an intraoperative three-dimensional navigation system.Decompression of the spinal cord was performed with a high-speed drill; the supraspinal ligaments and spinous process were partially preserved.The outcomes were evaluated by a modified Japanese Orthopedic Association （JOA） scoring system and recovery rates.Results The mean duration of follow-up for the 14 cases was 3.9 years.All patients experienced neurological recovery,the mean JOA score improving from 6.1 points preoperatively to 8.6 points at final follow-up and the mean rate of recovery being 52.7% （excellent in two cases,good in eight,fair in three,and unchanged in one）.Conclusion CAMISS is a safe and effective procedure for resection of the OLF in the thoracic spine.

Learning curve of computer-assisted navigation system in spine surgery

Background Spine surgery using computer-assisted navigation （CAN） has been proven to result in low screw misplacement rates, low incidence of radiation exposure and excellent operative field viewing versus the conventional intraoperative image intensifier （CⅢ）. However, as we know, few previous studies have described the learning curve of CAN in spine surgery.Methods We performed two consecutive case cohort studies on pedicel screw accuracy and operative time of two spine surgeons with different experience backgrounds, A and B, in one institution during the same period. Lumbar pedicel screw cortical perforation rate and operative time of the same kind of operation using CAN were analyzed and compared using CⅢ for the two surgeons at initial, 6 months and 12 months of CAN usage.Results CAN spine surgery had an overall lower cortical perforation rate and less mean operative time compared with CⅢ for both surgeon A and B cohorts when total cases of four years were included. It missed being statistically significant,with 3.3% versus 4.7% （P=0.191） and 125.7 versus 132.3 minutes （P=0.428） for surgeon A and 3.6% versus 6.4%（P=0.058）, and 183.2 versus 213.2 minutes （P=0.070） for surgeon B. in an attempt to demonstrate the learning curve,the cases after 6 months of the CAN system in each surgeon＇s cohort were compared. The perforation rate decreased by 2.4% （P=0.039） and 4.3% （P=0.003） and the operative time was reduced by 31.8 minutes （P=0.002） and 14.4 minutes （P=0.026） for the CAN groups of surgeons A and B, respectively. When only the cases performed after 12 months using the CAN system were considered, the perforation rate decreased by 3.9% （P=0.006） and 5.6% （P 〈0.001） and the operative time was reduced by 20.9 minutes （P 〈0.001） and 40.3 minutes （P 〈0.001） for the CAN groups of surgeon A and B, respectively.Conclusions In the long run, CAN spine surgery decreased the lumbar screw cortical perforation rate and operative time. The learning curve showed a sharp drop after 6 months of using CAN that plateaued after 12 months; which was demonstrated by both perforation rate and operative time data. Careful analysis of the data showed CAN is especially useful for less experienced surgeon to reduce perforation rate and intraoperative time, although further comparative studies are anticipated.

Pedicle screw placement in the thoracic spine： a randomized comparison study of computer-assisted navigation and conventional techniques

Objective： To evaluate the accuracy of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation techniques. Methods： Total 176 thoracic pedicle screws placed in 42 thoracic fracture patients were involved in the study randomly, 20 patients under conventional fluoroscopic control （84 screws） and 22 patients had screw insertion under three dimensional （3D） computer-assisted navigation （92 screws）. The 2 groups were compared for accuracy of screw placement, time for screw insertion by postoperative thincut CT scans and statistical analysis by χ^2 test. The cortical perforations were then graded by 2-mm increments： Grade Ⅰ （good, no cortical perforation）, Grade Ⅱ （screw outside the pedicle 〈2 mm）, Grade Ⅲ （screw outside the pedicle 〉2 mm）. Results： In computer assisted group, 88 （95.65%） were Grade Ⅰ （good）, 4 （4.35%） were Grade Ⅱ （〈2mm）, no Grade Ⅲ （〉2 mm） violations. In conventional group, there were 14 cortical violations （16.67%）, 70 （83.33%） were Grade Ⅰ （good）, Ⅱ （13.1%） were Grade Ⅱ （〈2 mm）, and 3 （3,57%） were Grade Ⅲ （〉2 mm） violations （P〈0.001）. The number （19.57%） of upper thoracic pedicle screws （ T1-T4 ） inserted under 3D computer-assisted navigation was significantly higher than that （3.57%） by conventional fluoroscopic control （P〈0.001）. Average screw insertion time in conventional group was （4.56 ±1.03） min and （2.54 ± 0.63） min in computer assisted group （P〈0.001）. In the conventional group, one patient had pleura injury and one had a minor dura violation. Conclusions： This study provides further evidence that 3D computer-assisted navigation placement ofpedicle screws can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly upper thoracic spine.