Radiation dose reduction in computer assisted navigation for functional endoscopic sinus surgery--cadaver head experiments and clinical implementation

Computed tomography based navigation for endoscopic sinus surgery is inflationary used despite of major public concern about iatrogenic radiation induced cancer risk. Studies on dose reduction for CAS-CT are almost nonexistent. We validate the use of radiation dose reduced CAS-CT for clinically applied surface registration.

Outcome of computer-assisted surgery in patients with chronic rhinosinusitis

To compare the complication rates and outcome of computer-assisted versus non-computer-assisted functional endoscopic sinus surgery.

Optimizing heroin-assisted treatment (HAT): Assessment of the contribution of direct ethanol metabolites in identifying hazardous and harmful alcohol use

Heavy alcohol consumption may accelerate the progression of hepatitis C-related liver disease and/or limit efforts at antiviral treatment in opioid-dependent patients receiving heroin-assisted treatment (HAT). Our study aims to assess alcohol intake among HAT patients by self-reports compared to direct ethanol metabolites.

Is computer-assisted telephone triage safe? A prospective surveillance study in walk-in patients with non-life-threatening medical conditions

Background Patients often establish initial contact with healthcare institutions by telephone. During this process they are frequently medically triaged. Purpose To investigate the safety of computer-assisted telephone triage for walk-in patients with non-life-threatening medical conditions at an emergency unit of a Swiss university hospital. Methods This prospective surveillance study compared the urgency assessments of three different types of personnel (call centre nurses, hospital physicians, primary care physicians) who were involved in the patients' care process. Based on the urgency recommendations of the hospital and primary care physicians, cases which could potentially have resulted in an avoidable hazardous situation (AHS) were identified. Subsequently, the records of patients with a potential AHS were assessed for risk to health or life by an expert panel. Results 208 patients were enrolled in the study, of whom 153 were assessed by all three types of personnel. Congruence between the three assessments was low. The weighted κ values were 0.115 (95% CI 0.038 to 0.192) (hospital physicians vs call centre), 0.159 (95% CI 0.073 to 0.242) (primary care physicians vs call centre) and 0.377 (95% CI 0.279 to 0.480) (hospital vs primary care physicians). Seven of 153 cases (4.57%; 95% CI 1.85% to 9.20%) were classified as a potentially AHS. A risk to health or life was adjudged in one case (0.65%; 95% CI 0.02% to 3.58%). Conclusion Medical telephone counselling is a demanding task requiring competent specialists with dedicated training in communication supported by suitable computer technology. Provided these conditions are in place, computer-assisted telephone triage can be considered to be a safe method of assessing the potential clinical risks of patients' medical conditions.

Real-Time Multimodal Retinal Image Registration for a Computer Assisted Laser Photocoagulation System

An algorithm for the real-time registration of a retinal video sequence captured with a scanning digital ophthalmoscope (SDO) to a retinal composite image is presented. This method is designed for a computer-assisted retinal laser photocoagulation system to compensate for retinal motion and hence enhance the accuracy, speed, and patient safety of retinal laser treatments. The procedure combines intensity and feature-based registration techniques. For the registration of an individual frame, the translational frame-to-frame motion between preceding and current frame is detected by normalized cross correlation. Next, vessel points on the current video frame are identified and an initial transformation estimate is constructed from the calculated translation vector and the quadratic registration matrix of the previous frame. The vessel points are then iteratively matched to the segmented vessel centerline of the composite image to refine the initial transformation and register the video frame to the composite image. Criteria for image quality and algorithm convergence are introduced, which assess the exclusion of single frames from the registration process and enable a loss of tracking signal if necessary. The algorithm was successfully applied to ten different video sequences recorded from patients. It revealed an average accuracy of 2.47 ± 2.0 pixels (∼23.2 ± 18.8 μm) for 2764 evaluated video frames and demonstrated that it meets the clinical requirements.

Retraining of interjoint arm coordination after stroke using robot-assisted time-independent functional training

We have developed a haptic-based approach for retraining of interjoint coordination following stroke called time-independent functional training (TIFT) and implemented this mode in the ARMin III robotic exoskeleton. The ARMin III robot was developed by Drs. Robert Riener and Tobias Nef at the Swiss Federal Institute of Technology Zurich (Eidgenossische Technische Hochschule Zurich, or ETH Zurich), in Zurich, Switzerland. In the TIFT mode, the robot maintains arm movements within the proper kinematic trajectory via haptic walls at each joint. These arm movements focus training of interjoint coordination with highly intuitive real-time feedback of performance; arm movements advance within the trajectory only if their movement coordination is correct. In initial testing, 37 nondisabled subjects received a single session of learning of a complex pattern. Subjects were randomized to TIFT or visual demonstration or moved along with the robot as it moved though the pattern (time-dependent [TD] training). We examined visual demonstration to separate the effects of action observation on motor learning from the effects of the two haptic guidance methods. During these training trials, TIFT subjects reduced error and interaction forces between the robot and arm, while TD subject performance did not change. All groups showed significant learning of the trajectory during unassisted recall trials, but we observed no difference in learning between groups, possibly because this learning task is dominated by vision. Further testing in stroke populations is warranted.

Geometry-Aware Multiscale Image Registration via OBBTree-Based Polyaffine Log-Demons

Non-linear image registration is an important tool in many areas of image analysis. For instance, in morphometric studies of a population of brains, free-form deformations between images are analyzed to describe the structural anatomical variability. Such a simple deformation model is justified by the absence of an easy expressible prior about the shape changes. Applying the same algorithms used in brain imaging to orthopedic images might not be optimal due to the difference in the underlying prior on the inter-subject deformations. In particular, using an un-informed deformation prior often leads to local minima far from the expected solution. To improve robustness and promote anatomically meaningful deformations, we propose a locally affine and geometry-aware registration algorithm that automatically adapts to the data. We build upon the log-domain demons algorithm and introduce a new type of OBBTree-based regularization in the registration with a natural multiscale structure. The regularization model is composed of a hierarchy of locally affine transformations via their logarithms. Experiments on mandibles show improved accuracy and robustness when used to initialize the demons, and even similar performance by direct comparison to the demons, with a significantly lower degree of freedom. This closes the gap between polyaffine and non-rigid registration and opens new ways to statistically analyze the registration results.

PS-GANS: A Patient-Specific, Gravity Assisted Navigation System for Acetabular Cup Placement

In this paper we propose a new system that allows reliable acetabular cup placement when the THA is operated in lateral approach. Conceptually it combines the accuracy of computer-generated patient-specific morphology information with an easy-to-use mechanical guide, which effectively uses natural gravity as the angular reference. The former is achieved by using a statistical shape model-based 2D-3D reconstruction technique that can generate a scaled, patient-specific 3D shape model of the pelvis from a single conventional anteroposterior (AP) pelvic X-ray radiograph. The reconstructed 3D shape model facilitates a reliable and accurate co-registration of the mechanical guide with the patient’s anatomy in the operating theater. We validated the accuracy of our system by conducting experiments on placing seven cups to four pelvises with different morphologies. Taking the measurements from an image-free navigation system as the ground truth, our system showed an average accuracy of 2.1 ±0.7 o for inclination and an average accuracy of 1.2 ±1.4 o for anteversion.

Nanoshell assisted laser soldering of vascular tissue

Laser tissue soldering (LTS) is a promising technique for tissue fusion but is limited by the lack of reproducibility particularly when the amount of indocyanine green (ICG) applied as energy absorber cannot be controlled during the soldering procedure. Nanotechnology enables the control over the quantitative binding of the ICG. The aim of this study was to establish a highly reproducible and strong tissue fusion using ICG packed nanoshells. By including the chromophore in the soldering scaffold, dilution of the energy absorber during the soldering procedure is prevented. The feasibility of this novel nanoshell soldering technique was studied by assessing the local heating of the area and tensile strength of the resulting fused tissue.

Synthesis of Macrocyclic Polymers Formed via Intramolecular Radical Trap-Assisted Atom Transfer Radical Coupling

The synthesis of cyclic polystyrene (Pst) with an alkoxyamine functionality has been accomplished by intramolecular radical coupling in the presence of a nitroso radical trap Linear alpha,omega-dibrominated polystyrene, produced by the atom transfer radical polymerization (ATRP) of styrene using a dibrominated initiator, was subjected to chain-end activation via the atom transfer radical coupling (ATRC) process under pseudodilute conditions in the presence of 2-methyl-2-nitrosopropane (MNP). This radical trap-assisted, intramolecular ATRC (RTA-ATRC) produced cyclic polymers in greater than 90% yields possessing < G > values in the 0.8-0.9 range as determined by gel permeation chromatography (GPC). Thermal-induced opening of the cycles, made possible by the incorporated alkoxyamine, resulted in a return to the original apparent molecular weight, further supporting the formation of cyclic polymers in the RTA-ATRC reaction. Liquid chromatography-mass spectrometry (LC-MS) provided direct confirmation of the cyclic architecture and the incorporation of the nitroso group into the macrocycle RTA-ATRC cyclizations carried out with faster rates of polymer addition into the redox active solution and/or in the presence of a much larger excess of MNP (up to a 250:1 ratio of MNP:C-Br chain end) still yielded cyclic polymers that contained alkoxyamine functionality.

Cost-effectiveness of open versus laparoscopic versus robotic-assisted laparoscopic cystectomy and urinary diversion

To provide insight into the recently published cost comparisons in the context of open, laparoscopic, and robotic-assisted laparoscopic radical cystectomy and to demonstrate the complexity of such economic analyses.

Denosumab Significantly Increases DXA BMD at Both Trabecular and Cortical Sites: Results From the FREEDOM Study

Denosumab is an approved therapy for postmenopausal women with osteoporosis at high or increased risk for fracture. In the FREEDOM study, denosumab reduced fracture risk and increased bone mineral density (BMD). We report the spine and hip dual-energy X-ray absorptiometry (DXA) BMD responses from the overall study of 7808 women and from a substudy of 441 participants in which more extensive spine and hip assessments as well as additional skeletal sites were evaluated. Significant BMD improvements were observed as early as 1mo at the lumbar spine, total hip, and trochanter (all p<0.005 vs placebo and baseline). BMD increased progressively at the lumbar spine, total hip, femoral neck, trochanter, 1/3 radius, and total body from baseline to months 12, 24, and 36 (all p<0.005 vs placebo and baseline). BMD gains above the least significant change of more than 3% at 36 months were observed in 90% of denosumab-treated subjects at the lumbar spine and 74% at the total hip, and gains more than 6% occurred in 77% and 38%, respectively. In conclusion, denosumab treatment resulted in significant, early, and continued BMD increases at both trabecular and cortical sites throughout the skeleton over 36mo with important gains observed in most subjects.