TS-Net: Two-stage deformable medical image registration network based on new smooth constraints

Medical image registration can establish the spatial consistency of the corresponding anatomical structures between different medical images, which is important in medical image analysis. In recent years, with the rapid development of deep learning, the image registration methods based on deep learning greatly improve the speed, accuracy, and robustness of registration. Regrettably, these methods typically do not work well for large deformations and complex deformations in the image, and neglect to preserve the topological properties of the image during deformation. Aiming at these problems, we propose a new network TS-Net that learns deformation from coarse to fine and transmits information of different scales in the two stages. Two-stage network learning deformation from coarse to fine can gradually learn the large and complex deformations in images. In the second stage, the feature maps downsampled in the first stage for skip connection can expand the local receptive field and obtain more local information. The smooth constraints function used in the past is to impose the same restriction on the global, which is not targeted. In this paper, we propose a new smooth constraints function for each voxel deformation, which can better ensure the smoothness of the transformation and maintain the topological properties of the image. The experiments on brain datasets with complex deformations and heart datasets with large deformations show that our proposed method achieves better results while maintaining the topological properties of deformations compared to existing deep learning-based registration methods.

A pilot randomized controlled trial on ligation of intersphincteric fistula tract (LIFT) versus modified parks technique and two-stage seton in treatment of complex anal fistula

Complex anal fistula (CAF) is a challenging condition for surgeons. This randomized trial aimed to compare ligation of the intersphincteric fistula tract (LIFT), modified Parks technique, and two-stage seton in the treatment of complex anal fistula in terms of the success of treatment and complications. This was a pilot randomized trial conducted in the period of January 2019 to December 2019 on adult patients with CAF who were allocated to one of three groups: LIFT, modified Parks technique, and two-stage seton. The main outcome measures were healing rates, time to healing, complications, operation time, and quality of life. Sixty-six patients (75.7% males) of a mean age of 45.2 years were included. Mean operation time of LIFT was significantly shorter than the other two procedures (p < 0.0001). There was a significant difference between the three groups in terms of success rate (p = 0.04) but not in regard to complications (p = 0.59). The modified Parks technique had a significantly higher success rate than LIFT (95.2% vs 68.1%, p = 0.045) whereas the success rates of two-stage seton and LIFT were not significantly different (86.9% vs 68.1%, p = 0.16). The average time to healing after LIFT was significantly shorter than the other two procedures. The quality-of-life scores were comparable among the three groups. There was a significant difference in healing rates after the three procedures as the modified Parks technique achieved the highest success rate followed by two-stage seton and then the LIFT procedure. Time to complete healing after LIFT was significantly shorter than the other two procedures. The three procedures achieved similar quality of life and complication rates.

Estimation of the binomial probabilities in a two-stage phase II clinical trial with two co-primary endpoints

In cancer research, two-stage designs are usually used to assess the effect of a new agent in phase II clinical trials. Optimal two-stage designs with two co-primary endpoints have been proposed to assess the effects of new cancer treatments, such as cytostatic or molecularly targeted agents (MTAs), based on both response rate and early progression rate. Accurate estimation of response and early progression rates based on the data from the phase II trials conducted according to the optimal two-stage designs would be very useful for further testing of the agents in phase II trials. In this paper, we derive some estimation procedures, which include both standard and bias-corrected maximum likelihood estimates (MLE) and uniformly minimum variance unbiased estimate (UMVUE), for two binomial probabilities which are used to define the hypotheses for two co-primary endpoints tested in a two-stage phase II clinical trial. Simulation studies were performed to evaluate the performance of these procedures. These procedures are also applied to analyze the data from a phase II trial conducted by the Canadian Cancer Trials Group.

A comparative study of pre- or subpectoral expander position with the fenestrated Acellular dermal matrix anterior coverage, on drainage volume and Seroma Formation after Non-Nipple-Sparing Mastectomy

BACKGROUND

It has been reported that the use of the acellular dermal matrix (ADM) in expander-based breast reconstruction is related to an increase in seroma-related complications. The aim of this study is to compare the actual drainage volume, time to drain removal, and seroma formation rate in patients with prepectoral expander placement with anterior coverage of a fenestrated ADM to those patients with partial subpectoral expander placement with inferior coverage of a fenestrated ADM.

METHODS

This is a single-surgeon retrospective review of patients who underwent prepectoral expander-based breast reconstruction following non-nipple-sparing mastectomy. Patient demographics, operative data, and complications were analyzed and multivariate linear regression analyses were conducted to evaluate the significance of factors that influences total volume of fluid formation.

RESULTS

A total of 89 breasts from 87 patients were included in the study. Twenty-seven breasts had prepectoral expander reconstruction and 62 breasts had partial subpectoral expander reconstruction. Mean total volumes of fluid formation (total drainage volume + additional aspirated volume) were not significantly different (p = 0.190) in the two groups. In the subpectoral group only, high body mass index (BMI) was correlated with the total volume of fluid formation among the independent factors. (p = 0.017) CONCLUSIONS: Although total drainage volume was not significantly different between prepectoral and subpectoral groups, prepectoral positioning of the expander can be a protective factor against seroma formation in high BMI patients. Further definitive studies with larger patient numbers are warranted to corroborate these data and draw definitive conclusions.

Two-stage maximum likelihood approach for item-level missing data in regression

Psychologists use scales comprised of multiple items to measure underlying constructs. Missing data on such scales often occur at the item level, whereas the model of interest to the researcher is at the composite (scale score) level. Existing analytic approaches cannot easily accommodate item-level missing data when models involve composites. A very common practice in psychology is to average all available items to produce scale scores. This approach, referred to as available-case maximum likelihood (ACML), may produce biased parameter estimates. Another approach researchers use to deal with item-level missing data is scale-level full information maximum likelihood (SL-FIML), which treats the whole scale as missing if any item is missing. SL-FIML is inefficient and it may also exhibit bias. Multiple imputation (MI) produces the correct results using a simulation-based approach. We study a new analytic alternative for item-level missingness, called two-stage maximum likelihood (TSML; Savalei & Rhemtulla, Journal of Educational and Behavioral Statistics, 42(4), 405-431. 2017). The original work showed the method outperforming ACML and SL-FIML in structural equation models with parcels. The current simulation study examined the performance of ACML, SL-FIML, MI, and TSML in the context of univariate regression. We demonstrated performance issues encountered by ACML and SL-FIML when estimating regression coefficients, under both MCAR and MAR conditions. Aside from convergence issues with small sample sizes and high missingness, TSML performed similarly to MI in all conditions, showing negligible bias, high efficiency, and good coverage. This fast analytic approach is therefore recommended whenever it achieves convergence. R code and a Shiny app to perform TSML are provided.

The results of screw augmentation of acetabular cement spacers for the treatment of periprosthetic hip joint infection

Introduction

Prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) is widely used in two-stage revision arthroplasty in periprosthetic joint infection (PJI) after total hip arthroplasty (THA). In our institution, we encountered several cases of acetabular cement spacer dislodgement. The aim of this study was to compare the results of two-stage revision arthroplasties with antibiotic-loaded cement spacers with or without screws on the acetabulum for PJI.

Patients and methods

This retrospective study included 44 patients who underwent a two-stage revision THA for PJI from June 2007 to May 2017. We divided the patients into two groups: group 1 consisted of 21 patients (21 hips) who underwent two-stage revision arthroplasty with screw augmentation, while group 2 consisted of 23 patients (23 hips) who underwent the same surgery without screw augmentation at the acetabular cement spacer. We compared the migration and dislodgement of the acetabular cement spacer between the two groups.

Results

Before the second-stage surgery, there was less vertical migration of the cement spacer in group 1 compared to group 2 (1.2 mm vs 3.1 mm, p < 0.001). There was also less medial migration of the cement spacer in group 1 (0.6 mm vs 1.6 mm, p = 0.001). After the first stage, the mean Harris Hip score was significantly higher in group 1 than in group 2 (75 vs 65, p = 0.033). Cement spacer rotation or total movement out of the acetabular area occurred in six patients, all in group 2. After first stage reinfection occurred in two patients, one in each group.

Conclusions

Screw augmentation to the acetabulum in the first-stage surgery provides better stability of acetabular antibiotic cement spacers without increasing reinfection rate.

Total Knee Periprosthetic Joint Infection in the Setting of Hematologic Malignancy: Considerations for Management

Patients with malignancy are often profoundly immunocompromised due to chemotherapy, placing them at potential increased risk for periprosthetic joint infection (PJI). However, there is little information regarding PJI management in these patients. We describe 4 patients with a history of primary total knee arthroplasty followed by diagnosis of multiple myeloma or Waldenström macroglobulinemia who received chemotherapy within 4 months prior to PJI. The Musculoskeletal Infection Society major and minor criteria and either debridement, antibiotics, and implant retention or a 2-stage approach appear to be effective for acute or chronic PJI, respectively. We recommend an anticoagulant be administered concomitantly with antineoplastics that significantly increase deep vein thrombosis risk, and we recommend long-term oral suppressive antibiotics postoperatively, especially if chemotherapy will be resumed. Additional studies are needed to investigate risks and benefits of PJI prophylaxis during chemotherapy and long-term suppressive antibiotics after PJI treatment.

The Changing Face of Infection, Diagnosis, and Management in the United Kingdom

Prosthetic joint infection is still a rare but devastating complication following total hip and knee arthroplasty. The incidence of prosthetic joint infection ranges from 2% to 4% in primary procedures as opposed to nearly 20% in revisions. The challenges that arise here include mainly diagnostic uncertainty, management in immunocompromised patients, recurrent infection, infection around a well-fixed implant, and substantial bone loss, and require careful preoperative assessment and well-defined management plans. This article summarizes recent developments in the diagnosis and management of this increasingly prevalent issue specifically focusing on outcomes following debridement, antibiotics, and implants retention and one-stage revision procedures.

Tests for predicting reimplantation success of two-stage revision for periprosthetic joint infection: A systematic review and meta-analysis

BACKGROUND

Several tests are used before reimplantation to detect persistent infection in patients with periprosthetic joint infection (PJI) undergoing two-stage revision. However, there is no consensus as to the optimal tests for excluding persistent infection or predicting successful reimplantation by stage. We aimed to determine the accuracy of different tests used to detect persistent infection after the first stage, and/or predicting failure following reimplantation in patients with PJI.

METHODS

We conducted a systematic review and meta-analysis of PubMed, Embase and the Cochrane Library databases. Two reviewers independently conducted quality assessments and data extractions to estimate pooled sensitivity and specificity, diagnostic odds ratio and area under the receiver operating characteristic curves (AUSROC) for each test.

RESULTS

We included 24 studies published between May 1999 and September 2017. Synovial fluid polymorphonuclear neutrophils (PMN)% had the highest sensitivity of 0.70, followed by serum erythrocyte sedimentation rate (0.57) and spacer sonication fluid culture (0.53). Synovial fluid culture had the highest specificity of 0.97, followed by frozen section (0.93) and the Musculoskeletal Infection Society criteria (0.92). Spacer sonication fluid culture was the most accurate test with an AUSROC of 0.8089, followed by synovial fluid culture (0.7749) and frozen section (0.7819).

DISCUSSION

Spacer sonication fluid culture had a relatively high diagnostic accuracy. We emphasize that no test can be used alone to exclude persistent infection beyond the first stage and/or predict failed reimplantation beyond the second stage.

LEVEL OF EVIDENCE

II, systematic review and meta-analysis of level 2 to level 4 studies with inconsistent results.

Infection and failure rates following total hip arthroplasty for septic arthritis: a case-controlled study

INTRODUCTION

Total hip arthroplasty (THA) is performed as a 2-stage or single stage procedure in patients with a history of septic arthritis of the native hip joint. The decision is based on whether the infection is active or quiescent in the joint. The aim of this study was to compare the outcomes of total hip arthroplasty for septic arthritis of the native hip to a control series of patients treated for primary osteoarthritis of the hip with standard THA.

METHODS

Between March 2000 and March 2013, 18 cases of septic arthritis of the hip treated with THA were retrospectively identified. During the same time period, 18 control cases of THA for degenerative osteoarthritis were identified. Cases and controls were comparable in age, gender, body mass index, type of anaesthesia and American Society of Anesthesiologists score.

RESULTS

11 and 7 cases received 2-stage and single stage total hip arthroplasty respectively for septic arthritis. There was a mean interval of 4 months between 1^st and 2^nd-stage operations. Cases and controls were followed up for a mean of 70 and 72 months respectively. There was no reinfection or implant failure in the cases, and comparable functional outcomes between cases and controls.

CONCLUSIONS

Two-stage and single-stage THA for active and quiescent native hip infection respectively, achieved similar outcomes to THA for primary osteoarthritis in controls.

Outcome following subluxation of mobile articulating spacers in two-stage revision total knee arthroplasty

INTRODUCTION

Infection after total knee arthroplasty (TKA) is a severe complication. It is usually treated with two-stage revision and implantation of a cement spacer. Few studies describe the complications associated with a mobile articulating spacer. This study examined the subluxation of articulating antibiotic spacers in knees and correlated it with prospectively collected early outcome scores after implantation of a revision prosthesis.

METHODS

Staged revisions for 72 infected primary total knee arthroplasties between 2004 and 2012 were examined. The mean age of the patients was 70.2 ± 10.8 years, with 40 right and 32 left knees. Sagittal and coronal subluxation was measured using radiographs prior to second-stage revision and grouped to be within (Group 1) or outside (Group 2) one standard deviation from the mean. Medical Outcomes Study Short Form-12 (SF-12), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Society Score (KSS) were obtained via patient-administered questionnaire. Statistical analysis was carried out to look at the correlation between subluxation and outcome.

RESULTS

Significant improvements were observed between the interim outcome scores prior to implantation of a revision prosthesis and scores obtained after second-stage revision. Debonding occurred in 5.6%, and one dislocation was found. Mean coronal subluxation was 4.8 ± 5.5% of the tibia width, in the lateral direction. Coronal subluxation did not affect SF12, WOMAC or KSS outcome scores. Mean sagittal subluxation was 6.1 ± 16.4% posteriorly. However, sagittal subluxation had a significant influence on Knee Society Scores, with Group 2 having a lower mean Knee Society Function Score of 39.3 than Group 1 (60.2) (p = 0.045). Sagittal subluxation did not affect SF12 or WOMAC scores.

CONCLUSION

Sagittal subluxation of the knee may influence the early to midterm outcome scores following a staged revision TKA for infection.

Delayed two-stage breast reconstruction with implants: The authors' recent experience

BACKGROUND

Presently, breast cancer detection is delayed in Poland and, thus, the only other option for patients is amputation and breast reconstruction (immediate or delayed). Reconstructive methods are based on using the patient's own tissue (pedicled or free myocutaneous flaps) or implants (a tissue expander, which is later exchanged for a prosthesis or an expandable implant).

OBJECTIVE

To evaluate the aesthetic results of a delayed two-stage breast reconstruction with the use of implants (expander and prosthesis) in patients who have previously undergone cancer-related mastectomy.

METHODS

From 2006 to 2009, 54 patients (34 to 65 years of age) underwent reconstruction at least one year after their mastectomy and adjuvant chemotherapy; three women also received x-ray therapy. All women underwent a two-stage treatment with a tissue expander, which was later exchanged for a prosthesis.

RESULTS

Outcomes of the surgery (evaluated by the physician and the patient at least six months after all stages of reconstruction) were found to be very good in 42 patients and good in 12 patients. After amputation and x-ray therapy in two cases, a fistula developed, which necessitated implant removal.

CONCLUSIONS

After amputation, breast reconstruction with implants (expander and prosthesis) provides good aesthetic results. The method is mildly burdening to the patient and does not cause severe scarring. Symmetrization of the second breast is often recommended; however, the cost is not covered by the national health system. In principle, earlier x-ray therapy disqualifies the application of implants. Dividing reconstruction into two stages (expander and prosthesis) allows for possible correction of prosthesis placement.