Contact Stability and Contact Safety of a Magnetic Resonance Imaging-Guided Robotic Catheter Under Heart Surface Motion.

Contact force quality is one of the most critical factors for safe and effective lesion formation during catheter based atrial fibrillation ablation procedures. In this paper, the contact stability and contact safety of a novel magnetic resonance imaging (MRI)-actuated robotic cardiac ablation catheter subject to surface motion disturbances are studied. First, a quasi-static contact force optimization algorithm, which calculates the actuation needed to achieve a desired contact force at an instantaneous tissue surface configuration is introduced. This algorithm is then generalized using a least-squares formulation to optimize the contact stability and safety over a prediction horizon for a given estimated heart motion trajectory. Four contact force control schemes are proposed based on these algorithms. The first proposed force control scheme employs instantaneous heart position feedback. The second control scheme applies a constant actuation level using a quasi-periodic heart motion prediction. The third and the last contact force control schemes employ a generalized adaptive filter-based heart motion prediction, where the former uses the predicted instantaneous position feedback, and the latter is a receding horizon controller. The performance of the proposed control schemes is compared and evaluated in a simulation environment.

Rhinoscintigraphic analysis of nasal mucociliary function in patients with Bell's palsy.

OBJECTIVE: Mucociliary transport (MCT) is an important defense mechanism of the respiratory tract. One of the major factors determining MCT is the ciliary activity of the respiratory epithelium. Rhinoscintigraphy is the most commonly used method for the analysis of mucociliary activity. The aim of this study was to investigate the effect of facial paralysis on the nasal mucociliary clearance. MATERIALS AND METHODS: This study included 38 Bell's palsy patients as the study group and 10 subjects without any history of paranasal sinus disease or facial paralysis as the control group. A drop of technetium 99m-labeled macroaggregated albumin (Tc-99m MAA) was placed posterior to the head of the inferior turbinate and followed with a gamma camera. MCT rate was measured as the velocity of Tc-99m MAA drop. RESULTS: The mean MCT rate was 4.27 ± 0.76 millimeters per minute (mm/min) on 20 sides of 10 healthy controls, 4.11 ± 2.91 mm/min on the affected sides of the patients with Bell's palsy, and 6.03 ± 3.13 mm/min on the nonparalyzed sides of the patients. MCT rate was statistically significantly faster in the nonparalyzed side when compared to the paralyzed side in Bell's palsy patients (P = 0.001). MCT rates were not significantly different in the control group and paralyzed sides of the Bell's palsy patients (P = 0.810). The MCT rate was statistically significantly faster in the nonparalyzed sides of Bell's palsy patients when compared to the controls (P = 0.017). CONCLUSION: This study showed a faster MCT rate on the nonparalyzed side in Bell's palsy patients when compared to the paralyzed side and the control subjects. A compensatory mechanism could be the underlying reason for faster MCT on the nonparalyzed side. Further studies on larger patient groups are needed to investigate the effect of facial paralysis on the MCT and changes of facial nerve function on the opposite, nonparalyzed side of the face.

Novel ITGB6 mutation in autosomal recessive amelogenesis imperfecta.

OBJECTIVE: Hereditary defects in tooth enamel formation, amelogenesis imperfecta (AI), can be non-syndromic or syndromic phenotype. Integrins are signaling proteins that mediate cell-cell and cell-extracellular matrix communication, and their involvement in tooth development is well known. The purposes of this study were to identify genetic cause of an AI family and molecular pathogenesis underlying defective enamel formation. MATERIALS AND METHODS: We recruited a Turkish family with isolated AI and performed mutational analyses to clarify the underlying molecular genetic etiology. RESULTS: Autozygosity mapping and exome sequencing identified a novel homozygous ITGB6 transversion mutation in exon 4 (c.517G>C, p.Gly173Arg). The glycine at this position in the middle of the ßI-domain is conserved among a wide range of vertebrate orthologs and human paralogs. Clinically, the enamel was generally thin and pitted with pigmentation. Thicker enamel was noted at the cervical area of the molars. CONCLUSIONS: In this study, we identified a novel homozygous ITGB6 mutation causing isolated AI, and this advances the understanding of normal and pathologic enamel development.

RUNX2 mutations in cleidocranial dysplasia.

The runt-related transcription factor 2 gene (RUNX2), which is also known as CBFA1, is a master regulatory gene in bone formation. Mutations in RUNX2 have been identified in cleidocranial dysplasia (CCD) patients. CCD is a rare autosomal dominant skeletal dysplasia that is characterized by delayed closure of cranial sutures, aplastic or hypoplastic clavicle formation, short stature, and dental anomalies, including malocclusion, supernumerary teeth, and delayed eruption of permanent teeth. In this study, we recruited three de novo CCD families and performed mutational analysis of the RUNX2 gene as a candidate gene approach. The mutational study revealed three disease-causing mutations: a missense mutation (c.674G>A, p.Arg225Gln), a frameshift mutation (c.1119delC, p.Arg374Glyfs*), and a nonsense mutation (c.1171C>T, p.Arg391*). Clinical examination revealed a unique dental phenotype (no typical supernumerary teeth, but duplication of anterior teeth) in one patient. We believe that this finding will broaden the understanding of the mechanism of supernumerary teeth formation and CCD-related phenotypes.

Heart Motion Prediction Based on Adaptive Estimation Algorithms for Robotic Assisted Beating Heart Surgery.

Robotic assisted beating heart surgery aims to allow surgeons to operate on a beating heart without stabilizers as if the heart is stationary. The robot actively cancels heart motion by closely following a point of interest (POI) on the heart surface-a process called Active Relative Motion Canceling (ARMC). Due to the high bandwidth of the POI motion, it is necessary to supply the controller with an estimate of the immediate future of the POI motion over a prediction horizon in order to achieve sufficient tracking accuracy. In this paper, two least-square based prediction algorithms, using an adaptive filter to generate future position estimates, are implemented and studied. The first method assumes a linear system relation between the consecutive samples in the prediction horizon. On the contrary, the second method performs this parametrization independently for each point over the whole the horizon. The effects of predictor parameters and variations in heart rate on tracking performance are studied with constant and varying heart rate data. The predictors are evaluated using a 3 degrees of freedom test-bed and prerecorded in-vivo motion data. Then, the one-step prediction and tracking performances of the presented approaches are compared with an Extended Kalman Filter predictor. Finally, the essential features of the proposed prediction algorithms are summarized.

Deformable cardiac surface tracking by adaptive estimation algorithms.

This study presents a particle filter based framework to track cardiac surface from a time sequence of single magnetic resonance imaging (MRI) slices with the future goal of utilizing the presented framework for interventional cardiovascular magnetic resonance procedures, which rely on the accurate and online tracking of the cardiac surface from MRI data. The framework exploits a low-order parametric deformable model of the cardiac surface. A stochastic dynamic system represents the cardiac surface motion. Deformable models are employed to introduce shape prior to control the degree of the deformations. Adaptive filters are used to model complex cardiac motion in the dynamic model of the system. Particle filters are utilized to recursively estimate the current state of the system over time. The proposed method is applied to recover biventricular deformations and validated with a numerical phantom and multiple real cardiac MRI datasets. The algorithm is evaluated with multiple experiments using fixed and varying image slice planes at each time step. For the real cardiac MRI datasets, the average root-mean-square tracking errors of 2.61 mm and 3.42 mm are reported respectively for the fixed and varying image slice planes. This work serves as a proof-of-concept study for modeling and tracking the cardiac surface deformations via a low-order probabilistic model with the future goal of utilizing this method for the targeted interventional cardiac procedures under MR image guidance. For the real cardiac MRI datasets, the presented method was able to track the points-of-interests located on different sections of the cardiac surface within a precision of 3 pixels. The analyses show that the use of deformable cardiac surface tracking algorithm can pave the way for performing precise targeted intracardiac ablation procedures under MRI guidance. The main contributions of this work are twofold. First, it presents a framework for the tracking of whole cardiac surface from a time sequence of single image slices. Second, it employs adaptive filters to incorporate motion information in the tracking of nonrigid cardiac surface motion for temporal coherence.

MRI Distortion Correction and Robot-to-MRI Scanner Registration for an MRI-Guided Robotic System.

Magnetic resonance imaging (MRI) guided robotic procedures require safe robotic instrument navigation and precise target localization. This depends on reliable tracking of the instrument from MR images, which requires accurate registration of the robot to the scanner. A novel differential image based robot-to-MRI scanner registration approach is proposed that utilizes a set of active fiducial coils, where background subtraction method is employed for coil detection. In order to use the presented preoperative registration approach jointly with the real-time high speed MRI image acquisition and reconstruction methods in real-time interventional procedures, the effects of the geometric MRI distortion in robot to scanner registration is analyzed using a custom distortion mapping algorithm. The proposed approach is validated by a set of target coils placed within the workspace, employing multi-planar capabilities of the scanner. Registration and validation errors are respectively 2.05 mm and 2.63 mm after the distortion correction showing an improvement of respectively 1.08 mm and 0.14 mm compared to the results without distortion correction.

Localization of Point-of-Interest Positions on Cardiac Surface for Robotic-Assisted Beating Heart Surgery.

One of the critical components of robotic-assisted beating heart surgery is precise localization of a point-of-interest (POI) position on cardiac surface, which needs to be tracked by the robotic instruments. This is challenging as the incoming sensor measurements, from which POI position is localized, might be noisy and incomplete. This paper presents two Bayesian filtering based localization approaches to localize POI position online from sonomicrometer measurements. Specifically, extended Kalman filter (EKF) and particle filter (PF) localization algorithms are explored to estimate the state of POI position. The estimations of upcoming heart motion generated by the generalized adaptive predictor, which is demonstrated in the authors' past work, are also incorporated to generate an improved motion model. The proposed methods are validated with prerecorded in-vivo heart motion data.

A review of functionalised bacterial cellulose for targeted biomedical fields.

Bacterial cellulose (BC), which can be produced by microorganisms, is an ideal biomaterial especially for tissue engineering and drug delivery systems thanks to its properties of high purity, biocompatibility, high mechanical strength, high crystallinity, 3 D nanofiber structure, porosity and high-water holding capacity. Therefore, wide ranges of researches have been done on the BC production process and its structural and physical modifications to make it more suitable for certain targeted biomedical applications thoroughly. BC's properties such as mechanical strength, pore diameter and porosity can be tuned in situ or ex situ processes by using various polymer and compounds. Besides, different organic or inorganic compounds that support cell attachment, proliferation and differentiation or provide functions such as antimicrobial effectiveness can be gained to its structure for targeted application. These processes not only increase the usage options of BC but also provide success for mimicking the natural tissue microenvironment, especially in tissue engineering applications. In this review article, the studies on optimisation of BC production in the last decade and the BC modification and functionalisation studies conducted for the three main perspectives as tissue engineering, drug delivery and wound dressing with diverse approaches are summarized.

A study on neonatal factors and eruption time of primary teeth.

OBJECTIVE: The purpose of this study was to determine the time of the eruption of the first primary tooth (FPT) in infants and to assess the effects of neonatal factors on the timing of the eruption. BASIC RESEARCH DESIGN: The dental and medical records of healthy infants were reviewed to gather data on birth weight (BW), gestational age (GA), prenatal history, and the time of the eruption of the FPT. Additionally, the mothers of these infants were asked to identify their smoking habits and/or caffeine consumption during pregnancy through face-to-face interviews. The resulting data were statistically analysed with the Student's t, Tukey, and Pearson correlation tests. RESULTS: The mean eruption times (MET) for girls and boys were 7.25 +/- 2.47 and 7.07 +/- 1.66 months respectively (p > 0.05). The MET of the FPT in infants with a GA of less than 34 weeks, 34 to 37 weeks, or over 37 weeks were 8.0 +/- 2.0, 8.29 +/- 2.97, 6.93 +/- 1.87 months, respectively. The MET in infants with a BW of 1500 to 2500g was 8.28 +/- 2.28 months, while the MET for the infants with a BW of over 2500g was 6.99 +/- 1.94 (p = 0.014). CONCLUSION: A significant difference was found in the METs of infants with low and normal BWs. No significant differences were observed in the MET as related to other neonatal factors.

Elution of residual monomers from dental composite materials.

AIM: This study was designed to determine the type and amount of the monomers leached from the different particle sizes of the composite materials. MATERIALS AND METHODS: Three different disk sizes (2, 4, 6 mm) prepared for each material group (Filtek Flow, Filtek A110, Filtek P60 and Filtek Supreme) were polymerised by LED and halogen light; the specimens were then placed in artificial saliva. The monomer release in 30 min and 24 hrs from the specimens was analyzed in HPLC calibrated for the monomer extracts before. RESULTS: TEGDMA release was detected in all material groups after 30 min and after 24 hrs. BisGMA and BisEMA were not determined in any groups and UDMA was detected only in Filtek Supreme. Significant differences in release of TEGDMA and UDMA were obtained between the different sizes of discs. Significantly high amount of TEGDMA and UDMA monomer release was obtained in LED than Halogen groups. Lower amount of monomer release was obtained in species of 30 min than 24 hrs. CONCLUSION: Data has revealed that the monomer release could be detected significantly high from the composite materials polymerized by a lower output curing light device; and higher elution of monomers was determined as the composite thickness has increased. Therefore, the clinical applications of composite materials and the type of curing units have very important effects on the success of restorations and in the decrease of potential side effects.

Effects of subjective tinnitus on sleep quality and Mini Mental Status Examination scores.

OBJECTIVES: We investigated the effects of subjective tinnitus on sleep quality and Mini Mental Status Examination (MMSE) scores of participants. METHODS: The study group consisted of 15 patients, including 21 ears with tinnitus (6 bilateral, 9 unilateral). The control group consisted of 8 healthy patients with normal hearing and no tinnitus (16 ears). We assessed sleep quality using the Mini Sleep Questionnaire (MSQ) and mental health using the MMSE. RESULTS: Sleep delay (SD) was significantly higher in tinnitus patients (5.28 +/- 2.23) compared to controls (3.25 +/- 2.56) (p = 0.018). Subjective tinnitus loudness level (STLL) scores were higher and sleep quality was impaired in females, older patients, and patients with lower MMSE scores. Sleep quality was also worse in patients with longer tinnitus duration. In younger and well educated patients, MMSE scores were higher. Higher STLL scores and shorter tinnitus duration were associated with lower MMSE scores. Patients with newly developed tinnitus reported more disturbances and showed greater effects on mental and cognitive functioning. CONCLUSION: In subjective tinnitus patients, sleep delay values increased. Long tinnitus duration and high STLL scores may affects patients' cognitive functions as shown by decreased MMSE scores. Furthermore, mental status changes in tinnitus patients were frequently overlooked.

Differential Image Based Robot to MRI Scanner Registration with Active Fiducial Markers for an MRI-Guided Robotic Catheter System.

In magnetic resonance imaging (MRI) guided robotic catheter ablation procedures, reliable tracking of the catheter within the MRI scanner is needed to safely navigate the catheter. This requires accurate registration of the catheter to the scanner. This paper presents a differential, multi-slice image-based registration approach utilizing active fiducial coils. The proposed method would be used to preoperatively register the MRI image space with the physical catheter space. In the proposed scheme, the registration is performed with the help of a registration frame, which has a set of embedded electromagnetic coils designed to actively create MRI image artifacts. These coils are detected in the MRI scanner's coordinate system by background subtraction. The detected coil locations in each slice are weighted by the artifact size and then registered to known ground truth coil locations in the catheter's coordinate system via least-squares fitting. The proposed approach is validated by using a set of target coils placed withing the workspace, employing multi-planar capabilities of the MRI scanner. The average registration and validation errors are respectively computed as 1.97 mm and 2.49 mm. The multi-slice approach is also compared to the single-slice method and shown to improve registration and validation by respectively 0.45 mm and 0.66 mm.