Consistent reconstruction of 4D fetal heart ultrasound images to cope with fetal motion

Purpose

4D ultrasound imaging of the fetal heart relies on reconstructions from B-mode images. In the presence of fetal motion, current approaches suffer from artifacts, which are unrecoverable for single sweeps.

Methods

We propose to use many sweeps and exploit the resulting redundancy to automatically recover from motion by reconstructing a 4D image which is consistent in phase, space, and time. An interactive visualization framework to view animated ultrasound slices from 4D reconstructions on arbitrary planes was developed using a magnetically tracked mock probe.

Results

We first quantified the performance of 10 4D reconstruction formulations on simulated data. Reconstructions of 14 in vivo sequences by a baseline, the current state-of-the-art, and the proposed approach were then visually ranked with respect to temporal quality on orthogonal views. Rankings from 5 observers showed that the proposed 4D reconstruction approach significantly improves temporal image quality in comparison with the baseline. The 4D reconstructions of the baseline and the proposed methods were then inspected interactively for accessibility to clinically important views and rated for their clinical usefulness by an ultrasound specialist in obstetrics and gynecology. The reconstructions by the proposed method were rated as ‘very useful’ in 71% and were statistically significantly more useful than the baseline reconstructions.

Conclusions

Multi-sweep fetal heart ultrasound acquisitions in combination with consistent 4D image reconstruction improves quality as well as clinical usefulness of the resulting 4D images in the presence of fetal motion.

     

Development of preoperative planning software for transforaminal endoscopic surgery and the guidance for clinical applications

Purpose

Preoperative planning is of great importance for transforaminal endoscopic techniques applied in percutaneous endoscopic lumbar discectomy. In this study, a modular preoperative planning software for transforaminal endoscopic surgery was developed and demonstrated.

Methods

The path searching method is based on collision detection, and the oriented bounding box was constructed for the anatomical models. Then, image reformatting algorithms were developed for multiplanar reconstruction which provides detailed anatomical information surrounding the virtual planned path. Finally, multithread technique was implemented to realize the steady-state condition of the software.

Results

A preoperative planning software for transforaminal endoscopic surgery (TE-Guider) was developed; seven cases of patients with symptomatic lumbar disc herniations were planned preoperatively using TE-Guider. The distances to the midlines and the direction of the optimal paths were exported, and each result was in line with the empirical value.

Conclusions

TE-Guider provides an efficient and cost-effective way to search the ideal path and entry point for the puncture. However, more clinical cases will be conducted to demonstrate its feasibility and reliability.

     

Labrumrekonstruktion – wie ist die Evidenz?

Background

The labrum is a biomechanically important structure of the hip joint. In the event of labral loss the new technique of labral reconstruction is aimed at restoring the anatomy and function of the labrum and thus prevention of joint degeneration.

Objective

The results and evidence relating to labral reconstruction are presented.

Material and methods

The currently available studies were evaluated and the biomechanical and clinical articles on labral reconstruction are discussed.

Results

There are a large number of different indications and surgical variants of this procedure. Biomechanical and clinical studies concerning labral defects show that the situation is improved by a reconstruction.

Discussion

As a result of the small number of cases and the low quality of the publications, there is as yet a lack of clinical evidence concerning this new surgical method. The biomechanical results suggest that reconstruction of a segmental labral defect is plausible for selected cases. Initial clinical results have to be confirmed by further studies in the long term.

     

Patient-specific catheter shaping for the minimally invasive closure of the left atrial appendage

Purpose

The minimally invasive closure of the left atrial appendage is a promising alternative to anticoagulation for stroke prevention in patients suffering from atrial fibrillation. One of the challenges of this procedure is the correct positioning and the coaxial alignment of the tip of the catheter sheath to the implant landing zone.

Method

In this paper, a novel preoperative planning system is proposed that allows patient-individual shaping of catheters to facilitate the correct positioning of the catheter sheath by offering a patient-specific catheter shape. Based on preoperative three-dimensional image data, anatomical points and the planned implant position are marked interactively and a patient-specific catheter shape is calculated if the standard catheter is not considered as suitable. An approach to calculate a catheter shape with four bends by maximization of the bending radii is presented. Shaping of the catheter is supported by a bending form that is automatically generated in the planning program and can be directly manufactured by using additive manufacturing methods.

Results

The feasibility of the planning and shaping of the catheter could be successfully shown using six data sets. The patient-specific catheters were tested in comparison with standard catheters by physicians on heart models. In four of the six tested models, the participating physicians rated the patient-individual catheters better than the standard catheter.

Conclusion

The novel approach for preoperatively planned and shaped patient-specific catheters designed for the minimally invasive closure of the left atrial appendage could be successfully implemented and a feasibility test showed promising results in anatomies that are difficult to access with the standard catheter.

     

Interactive virtual stent planning for the treatment of coarctation of the aorta

Purpose

The coarctation of the aorta (CoA), a local narrowing of the aortic arch, accounts for 7 % of all congenital heart defects. Stenting is a recommended therapy to reduce the pressure gradient. This procedure is associated with complications such as the development of adverse flow conditions. A computer-aided treatment planning based on flow simulations can help to predict possible complications. The virtual stent planning is an important, intermediate step in the treatment planning pipeline. We present a novel approach that automatically suggests a stent setup and provides a set of intuitive parameters that allow for an interactive adaption of the suggested stent placement and induced deformation.

Methods

A high-quality mesh and a centerline are automatically generated. The stent-induced deformation is realized through a deformation of the centerline and a vertex displacement with respect to the deformed centerline and additional stent parameters. The parameterization is automatically derived from the underlying data and can be optionally altered through a condensed set of clinically sound parameters.

Results

The automatic deformation can be generated in about 25 s on a consumer system. The interactive adaption can be performed in real time. Compared with manual expert reconstructions of the stented vessel section, the mean difference of vessel path and diameter is below 1 mm.

Conclusion

Our approach enables a medical user to easily generate a plausibly deformed vessel mesh which is necessary as input for a simulation-based treatment planning of CoA.

     

Thumb collateral ligament injuries in the athlete

Purpose of review

The purpose of this review is to identify current principles in the diagnosis and treatment of collateral ligament injuries of the thumb in the athlete.

Recent findings

Cadaver studies have clearly identified the ulnar and radial collateral ligaments origin and insertion footprints for repair or reconstruction.

Summary

Ulnar and radial collateral ligament injuries are common in athletics. History and physical examination are paramount in determining partial versus complete tear. When surgical treatment is indicated, placing the repair/reconstruction in the anatomic footprint restores stability while maintaining motion. The senior author’s preferred techniques are reported.

     

Entropy-based particle correspondence for shape populations

Purpose

Statistical shape analysis of anatomical structures plays an important role in many medical image analysis applications such as understanding the structural changes in anatomy in various stages of growth or disease. Establishing accurate correspondence across object populations is essential for such statistical shape analysis studies.

Methods

In this paper, we present an entropy-based correspondence framework for computing point-based correspondence among populations of surfaces in a groupwise manner. This robust framework is parameterization-free and computationally efficient. We review the core principles of this method as well as various extensions to deal effectively with surfaces of complex geometry and application-driven correspondence metrics.

Results

We apply our method to synthetic and biological datasets to illustrate the concepts proposed and compare the performance of our framework to existing techniques.

Conclusions

Through the numerous extensions and variations presented here, we create a very flexible framework that can effectively handle objects of various topologies, multi-object complexes, open surfaces, and objects of complex geometry such as high-curvature regions or extremely thin features.

     

Olanzapine vs haloperidol: treating delirium in a critical care setting

Objective

To compare the safety and estimate the response profile of olanzapine, a second-generation antipsychotic, to haloperidol in the treatment of delirium in the critical care setting.

Design

Prospective randomized trial

Setting

Tertiary care university affiliated critical care unit.

Patients

All admissions to a medical and surgical intensive care unit with a diagnosis of delirium.

Interventions

Patients were randomized to receive either enteral olanzapine or haloperidol.

Measurements

Patient’s delirium severity and benzodiazepine use were monitored over 5 days after the diagnosis of delirium.

Main results

Delirium Index decreased over time in both groups, as did the administered dose of benzodiazepines. Clinical improvement was similar in both treatment arms. No side effects were noted in the olanzapine group, whereas the use of haloperidol was associated with extrapyramidal side effects.

Conclusions

Olanzapine is a safe alternative to haloperidol in delirious critical care patients, and may be of particular interest in patients in whom haloperidol is contraindicated.

     

Combination of texture and shape features to detect pulmonary abnormalities in digital chest X-rays

Purpose

To improve detection of pulmonary and pleural abnormalities caused by pneumonia or tuberculosis (TB) in digital chest X-rays (CXRs).

Methods

A method was developed and tested by combining shape and texture features to classify CXRs into two categories: TB and non-TB cases. Based on observation that radiologist interpretation is typically comparative: between left and right lung fields, the algorithm uses shape features to describe the overall geometrical characteristics of the lung fields and texture features to represent image characteristics inside them.

Results

Our algorithm was evaluated on two different datasets containing tuberculosis and pneumonia cases.

Conclusions

Using our proposed algorithm, we were able to increase the overall performance, measured as area under the (ROC) curve (AUC) by 2.4 % over our previous work.

     

Retrograde Hindfoot Nailing for Acute Trauma

Purpose of Review

The role of retrograde hindfoot nailing in the treatment of acute orthopedic trauma is explored.

Recent Findings

Tibio-talar calcaneal (TTC) nailing is an acceptable treatment alternative for the low-demand geriatric patient with peri-articular ankle trauma permitting immediate weight-bearing with low rates of complication and return to functionality. Hindfoot nailing can be used for limb salvage in the younger active patient; yet, joint-preserving reconstruction is preferred when feasible.

Summary

Retrograde TTC nailing is a reliable option for hindfoot/distal tibia stabilization especially in the elderly frail population. Hindfoot nailing is reserved for a select subset of active patients when severity of bone, joint, and soft tissue injury are not amenable to more conventional reconstruction.

     

Tomosynthesis implementation with adaptive online calibration on clinical C-arm systems

Purpose

Cone beam computed tomography (CBCT) systems offer physicians crucial 3D and 2D imaging capabilities during interventions. However, certain medical applications only require very specific information from the CBCTs (e.g., determination of the position of high-contrast objects). In diagnostics, tomosynthesis techniques can be used in these cases to minimize dose exposure. Therefore, integrating such techniques on CBCT systems could also be beneficial for interventions. In this paper, we investigate the performance of our implementation of circular tomosynthesis on a CBCT device.

Methods

The tomosynthesis scan trajectory is realized with step-and-shoot on a clinical C-arm device. The online calibration algorithm uses conventionally acquired 3D CBCT of the scanned object as prior knowledge to correct the imaging geometries. The online calibration algorithm was compared to an offline calibration to test its performance. A ball bearing phantom was used to evaluate the reconstructions with respect to geometric distortions. The evaluation was done for three different scenarios to test the robustness of our tomosynthesis implementation against object deviations (e.g., pen) and different object positioning.

Results

The circular tomosynthesis was tested on a ball bearing and an anthropomorphic phantom. The results show that the calibration is robust against isocenter shifts and object deviations in the CBCT. All reconstructions used 100 projections and displayed limited angle artifacts. The accuracy of the positions and shapes of high-contrast objects were, however, determined precisely. (The maximal center position deviation is 0.31 mm.)

Conclusion

For medical procedures that primarily determine the precise position of high-contrast objects, circular tomosynthesis could offer an approach to reduce dose exposure.

     

Platelet-Rich Plasma and the Knee—Applications in Orthopedic Surgery

Purpose of Review

To consolidate and synthesize the most recent evidence on the effects of platelet-rich plasma (PRP) in the knee with respect to osteoarthritis, meniscal injuries, ACL reconstruction, total knee arthroplasty (TKA), and high tibial osteotomy.

Recent Findings

PRP has been shown to be more beneficial in the context of knee osteoarthritis compared to both placebo and hyaluronic acid. Direct comparison with corticosteroid injections has been sparsely studied. It has also been shown to improve the clinical postoperative course in meniscal injuries and to a lesser extent TKA. Radiographic improvements without clinically significant benefits have been observed with ACL reconstructions treated with PRP.

Summary

PRP injections may be more beneficial than other current non-surgical management options for specific knee pathologies. Further research should broaden the knowledge of PRP effects on the knee, and identify the type of PRP, growth factor distribution, and route of administration associated with the most benefit.

     

Low dose quetiapine induced galactorrhoea: a case report

Background

Quetiapine causes less prolactin elevation and/or galactorrhoea than other atypical antipsychotics.

Case Presentation

Ms AB had galactorrhoea and raised prolactin levels at only 100 mg of quetiapine daily.

Conclusion

Low dose quetiapine can also cause galactorrhoea.

     

Dense soft tissue 3D reconstruction refined with super-pixel segmentation for robotic abdominal surgery

Purpose

Single-incision laparoscopic surgery decreases postoperative infections, but introduces limitations in the surgeon’s maneuverability and in the surgical field of view. This work aims at enhancing intra-operative surgical visualization by exploiting the 3D information about the surgical site. An interactive guidance system is proposed wherein the pose of preoperative tissue models is updated online. A critical process involves the intra-operative acquisition of tissue surfaces. It can be achieved using stereoscopic imaging and 3D reconstruction techniques. This work contributes to this process by proposing new methods for improved dense 3D reconstruction of soft tissues, which allows a more accurate deformation identification and facilitates the registration process.

Methods

Two methods for soft tissue 3D reconstruction are proposed: Method 1 follows the traditional approach of the block matching algorithm. Method 2 performs a nonparametric modified census transform to be more robust to illumination variation. The simple linear iterative clustering (SLIC) super-pixel algorithm is exploited for disparity refinement by filling holes in the disparity images.

Results

The methods were validated using two video datasets from the Hamlyn Centre, achieving an accuracy of 2.95 and 1.66 mm, respectively. A comparison with ground-truth data demonstrated the disparity refinement procedure: (1) increases the number of reconstructed points by up to 43 % and (2) does not affect the accuracy of the 3D reconstructions significantly.

Conclusion

Both methods give results that compare favorably with the state-of-the-art methods. The computational time constraints their applicability in real time, but can be greatly improved by using a GPU implementation.

     

Anonymisieren oder personalisieren?

Background

The subjective state of health with respect to pain and psyche was surveyed utilizing validated pain questionnaires in patients undergoing special pain therapy and represents the basis for targeted treatment measures.

Objective

The purpose of this study was to investigate the possible distortion of answers due to social desirability of responses in chronic pain patients.

Material and methods

During two survey periods assessing patient satisfaction using both anonymized and personalized questionnaires, the effects arising from socially desirable response patterns were analyzed. The sample consisted of chronic pain patients being treated in an inpatient therapy setting.

Results

In both periods of observation no significant impact on the response behavior of chronic pain patients was found in personalized or anonymized questionnaires.

Conclusion

The results of the study suggest that the responses of chronic pain patients with respect to their subjective state of health are not influenced by social desirability. Thus, scoring systems such as the German pain questionnaire will not be influenced by social desirability in chronic pain patients and can therefore be used as a part of diagnostics and therapy planning.

     

<Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript> Regularization for Bioluminescence Tomography Based on the Split Bregman Method

Purpose

Bioluminescence tomography (BLT) is a promising in vivo optical imaging technique in preclinical research at cellular and molecular levels. The problem of BLT reconstruction is quite ill-posed and ill-conditioned. In order to achieve high accuracy and efficiency for its inverse reconstruction, we proposed a novel approach based on L _p regularization with the Split Bregman method.

Procedures

The diffusion equation was used as the forward model. Then, we defined the objective function of L _p regularization and developed a Split Bregman iteration algorithm to optimize this function. After that, we conducted numerical simulations and in vivo experiments to evaluate the accuracy and efficiency of the proposed method.

Results

The results of the simulations indicated that compared with the conjugate gradient and iterative shrinkage methods, the proposed method is more accurate and faster for multisource reconstructions. Furthermore, in vivo imaging suggested that it could clearly distinguish the viable and apoptotic tumor regions.

Conclusions

The Split Bregman iteration method is able to minimize the L _p regularization problem and achieve fast and accurate reconstruction in BLT.

     

Image quality of Zr-89 PET imaging in the Siemens microPET Focus 220 preclinical scanner

Purpose

Zr-89 positron emission tomography (PET) is a valuable tool for understanding the biodistribution and pharmacokinetics of antibody-based therapeutics. We compared the image quality of Zr-89 PET and F-18 PET in the Siemens microPET Focus 220 preclinical scanner using different reconstruction methods.

Procedures

Image quality metrics were measured in various Zr-89 and F-18 PET phantoms, including the NEMA NU 4-2008 image quality phantom. Images were reconstructed using various algorithms.

Results

Zr-89 PET had greater image noise, inferior spatial resolution, and greater spillover than F-18 PET, but comparable recovery coefficients for cylinders of various diameters. Of the reconstruction methods, OSEM3D resulted in the lowest noise, highest recovery coefficients, best spatial resolution, but also the greatest spillover. Scatter correction results were found to be sensitive to varying object sizes.

Conclusions

Zr-89 PET image quality was inferior to that of F-18, and no single reconstruction method was superior in all aspects of image quality.

     

Robust extraction for low-contrast liver tumors using modified adaptive likelihood estimation

Purpose

Liver tumor extraction is essential for liver ablation surgery planning and treatment. For accurate and robust tumor segmentation, we propose a semiautomatic method using adaptive likelihood classification with modified likelihood model.

Methods

First, a minimal ellipse (or quasi-ellipsoid) that encloses a liver tumor is generated for initialization. Then, a hybrid intensity likelihood modification based on nonparametric density estimation is proposed to enhance local likelihood contrast and reduce its inhomogeneity. A prior elliptical (or quasi-ellipsoid) shape constraint is directly integrated into the likelihood to further prevent leakage of the algorithm into adjacent tissues with similar intensity. Finally, an adaptive likelihood classification is proposed for accurate segmentation of tumors with low contrast, high noise or heterogeneous densities.

Results

Experiments were performed on 3Dircadb and LiTS datasets. The average volumetric overlap errors of the 3Dircadb and LiTS datasets were 27.05 and 35.72%, respectively. The algorithm’s robustness was validated by comparing results of 5 operators with multiple selections on different tumors.

Conclusions

The proposed method achieved good results in different tumors, even in low-contrast tumors with blurred boundaries. Reliable results can still be achieved over different initializations by different operators using the proposed method.

     

CT-based automated planning of acetabular cup for total hip arthroplasty (THA) based on hybrid use of two statistical atlases

Purpose

This study describes the use of CT images in atlas-based automated planning methods for acetabular cup implants in total hip arthroplasty (THA). The objective of this study is to develop an automated cup planning method considering the statistical distribution of the residual thickness.

Methods

From a number of past THA planning datasets, we construct two statistical atlases that represent the surgeon’s expertise. The first atlas is a pelvis-cup merged statistical shape model (PC-SSM), which encodes global spatial relationships between the patient anatomy and implant. The other is a statistical residual thickness map (SRTM) of the implant surface, which encodes local spatial constraints of the anatomy and implant. In addition to PC-SSM and SRTM, we utilized the minimum thickness as a threshold constraint to prevent penetration.

Results

The proposed method was applied to the pelvis shapes segmented from CT images of 37 datasets of osteoarthritis patients. Automated planning results with manual segmentation were compared to the plans prepared by an experienced surgeon. There was no significant difference in the average cup size error between the two methods (1.1 and 1.2 mm, respectively). The average positional error obtained by the proposed method, which integrates the two atlases, was significantly smaller (3.2 mm) than the previous method, which uses single atlas (3.9 mm). In the proposed method with automated segmentation, the size error of the proposed method for automated segmentation was comparable (1.1 mm) to that for manual segmentation (1.1 mm). The average positional error was significantly worse (4.2 mm) than that using manual segmentation (3.2 mm). If we only consider mildly diseased cases, however, there was no significance between them (3.2 mm in automated and 2.6 mm in manual segmentation).

Conclusion

We infer that integrating PC-SSM and SRTM is a useful approach for modeling experienced surgeon’s preference during cup planning.