Fiducial-based fusion of 3D dental models with magnetic resonance imaging

Purpose

Magnetic resonance imaging (MRI) is widely used in study of maxillofacial structures. While MRI is the modality of choice for soft tissues, it fails to capture hard tissues such as bone and teeth. Virtual dental models, acquired by optical 3D scanners, are becoming more accessible for dental practice and are starting to replace the conventional dental impressions. The goal of this research is to fuse the high-resolution 3D dental models with MRI to enhance the value of imaging for applications where detailed analysis of maxillofacial structures are needed such as patient examination, surgical planning, and modeling.

Methods

A subject-specific dental attachment was digitally designed and 3D printed based on the subject’s face width and dental anatomy. The attachment contained 19 semi-ellipsoidal concavities in predetermined positions where oil-based ellipsoidal fiducial markers were later placed. The MRI was acquired while the subject bit on the dental attachment. The spatial position of the center of mass of each fiducial in the resultant MR Image was calculated by averaging its voxels’ spatial coordinates. The rigid transformation to fuse dental models to MRI was calculated based on the least squares mapping of corresponding fiducials and solved via singular-value decomposition.

Results

The target registration error (TRE) of the proposed fusion process, calculated in a leave-one-fiducial-out fashion, was estimated at 0.49 mm. The results suggest that 6–9 fiducials suffice to achieve a TRE of equal to half the MRI voxel size.

Conclusion

Ellipsoidal oil-based fiducials produce distinguishable intensities in MRI and can be used as registration fiducials. The achieved accuracy of the proposed approach is sufficient to leverage the merged 3D dental models with the MRI data for a finer analysis of the maxillofacial structures where complete geometry models are needed.

     

Biomaterial characterization of off‐the‐shelf decellularized porcine pericardial tissue for use in prosthetic valvular applications

Fixed pericardial tissue is commonly used for commercially available xenograft valve implants, and has proven durability, but lacks the capability to remodel and grow. Decellularized porcine pericardial tissue has the promise to outperform fixed tissue and remodel, but the decellularization process has been shown to damage the collagen structure and reduce mechanical integrity of the tissue. Therefore, a comparison of uniaxial tensile properties was performed on decellularized, decellularized‐sterilized, fixed, and native porcine pericardial tissue versus native valve leaflet cusps. The results of non‐parametric analysis showed statistically significant differences (p < .05) between the stiffness of decellularized versus native pericardium and native cusps as well as fixed tissue, respectively; however, decellularized tissue showed large increases in elastic properties. Porosity testing of the tissues showed no statistical difference between decellularized and decell‐sterilized tissue compared with native cusps (p > .05). Scanning electron microscopy confirmed that valvular endothelial and interstitial cells colonized the decellularized pericardial surface when seeded and grown for 30 days in static culture. Collagen assays and transmission electron microscopy analysis showed limited reductions in collagen with processing; yet glycosaminoglycan assays showed great reductions in the processed pericardium relative to native cusps. Decellularized pericardium had comparatively low mechanical properties among the groups studied; yet the stiffness was comparatively similar to the native cusps and demonstrated a lack of cytotoxicity. Suture retention, accelerated wear, and hydrodynamic testing of prototype decellularized and decell‐sterilized valves showed positive functionality. Sterilized tissue could mimic valvular mechanical environment in vitro, therefore making it a viable potential candidate for off‐the‐shelf tissue‐engineered valvular applications.     

Effects of eight-week “gyroscopic device” mediated resistance training exercise on participants with impingement syndrome or tennis elbow

Background

Rehabilitation of injuries in the upper extremity and reestablishment of muscle strength throughout the range of motion in overhead movements, are the major concerns of athletes and coaches in the sports field.

Should patients with complex febrile seizure be admitted for further management?

Background and aims

Children with first complex febrile seizure (CFS) are often admitted for observation. The goals of this study were 1) to assess the risk of seizure recurrence during admission, 2) to determine whether early EEG affects acute management.

Relationship Between Proprioception and Endurance Functionality of the Cervical Flexor Muscles in Chronic Neck Pain and Asymptomatic Participants

Objective

The purpose of this study was to compare the relationship between flexion endurance capacity and joint position error in participants with or without chronic neck pain (CNP).

Positive guaiac and bloody stool are poor predictors of intussusception

Background

Currant jelly stool is a late manifestation of intussusception and is rarely seen in clinical practice. Other forms of GI bleeding have not been thoroughly studied and little is known about their respective diagnostic values.

Psychometric properties of Persian version of the Caregiver Burden Scale in Iranian caregivers of patients with spinal cord injury

Purpose: To investigate the psychometric properties of the Persian version of Caregiver Burden Scale (CBS) in caregivers of patients with spinal cord injury.

Methods: This is a cross-sectional study. After a forward–backward translation, the CBS was administered to 110 caregivers of patients with spinal cord injury (men?=?60, women?=?50). Factor structure was evaluated by confirmatory factor analysis. The Internal consistency and test–retest reliability of the CBS were examined using Cronbach’s α and the intraclass correlation coefficient, respectively. Construct validity was assessed by examining the relationship among CBS and the World Health Organization Quality of Life, and the Beck Depression Inventory.

Results: The results of confirmatory factor analysis provided support for a five-factor model of CBS. All subscales of CBS revealed acceptable internal consistency (0.698–0.755), except for environment subscale (0.559). The CBS showed adequate test–retest reliability for its subscales (0.745–0.900). All subscales of CBS significantly correlated with both Beck Depression Inventory and World Health Organization Quality of Life, confirming construct validity.

Conclusions: The Persian version of the CBS is a valid and reliable measure for assessing burden of care in caregivers of patients with spinal cord injury.

• Implications for Rehabilitation

• Spinal cord injury leads to depression, high levels of stress and diminished quality of life due to the high physical, emotional, and social burdens in caregivers.

• Persian version of the Caregiver Burden Scale is a valid and reliable tool for assessing burden in Iranian caregivers of patients with spinal cord injury.

     

Private finance of services covered by the National Health Insurance package of benefits in Israel

Background

Private health expenditure in systems of national health insurance has raised concern in many countries. The concern is mainly about the accessibility of care to the poor and the sick, and inequality in use and in health. The concern thus refers specifically to the care financed privately rather than to private health expenditure as defined in the national health accounts.

Objectives

To estimate the share of private finance in total use of services covered by the national package of benefits. and to relate the private finance of use to the income and health of the users.

Methods

The Central Bureau of Statistics linked the 2009 Health Survey and the 2010 Incomes Survey. Twenty-four thousand five hundred ninety-five individuals in 7175 households were included in the data. Lacking data on the share of private finance in total cost of care delivered, we calculated instead the share of uses having any private finance—beyond copayments—in total uses, in primary, secondary, paramedical and total care. The probability of any private finance in each type of care is then related, using random effect logistic regression, to income and health state.

Results

Fifteen percent of all uses of care covered by the national package of benefits had any private finance. This rate ranges from 10 % in primary care, 16 % in secondary care and 31 % in paramedical care. Twelve percent of all uses of physicians’ services had any private finance, ranging from 10 % in family physicians to 20 % in pulmonologists, psychiatrists, neurologists and urologists. Controlling for health state, richer individuals are more likely to have any private finance in all types of care. Controlling for income, sick individuals (1+ chronic conditions) are 30 % in total care and 60 % in primary care more likely to have any private finance compared to healthy individuals (with no chronic conditions).

Conclusions

The national accounts’ “private health spending” (39 % of total spending in 2010) is not of much use regarding equity of and accessibility to medical care by the population. The mean share of uses financed privately in 2010, a more relevant measure, is 15 % with large variation between types of care and physicians. While, as under national health insurance, richer persons contribute more into the finance of (private) medical care , and sicker persons are more likely to use it, the solidarity principle—cross subsidization from the rich to the sick, which is a fundamental principle of national health insurance systems, is clearly violated.