Conical crowns with electroplated gold copings: retention force changes caused by wear and combined off-axial load

The aim of this study was to examine the wear behavior of conical crowns of gold alloy and zirconium dioxide ceramics facing electroplated gold copings.

Resting-state EEG in schizophrenia: auditory verbal hallucinations are related to shortening of specific microstates

Abnormal perceptions and cognitions in schizophrenia might be related to abnormal resting states of the brain. Previous research found that a specific class (class D) of sub-second electroencephalography (EEG) microstates was shortened in schizophrenia. This shortening correlated with positive symptoms. We questioned if this reflected positive psychotic traits or present psychopathology.

Axial T2 mapping in intervertebral discs: a new technique for assessment of intervertebral disc degeneration

To demonstrate the potential benefits of biochemical axial T2 mapping of intervertebral discs (IVDs) regarding the detection and grading of early stages of degenerative disc disease using 1.5-Tesla magnetic resonance imaging (MRI) in a clinical setting.

Effect of shortening the barrel in contact shots from rifles and shotguns

In a suicidal gunshot fired to the chest from a carbine, the barrel of which had been shortened to half its original length, an unexpectedly large degree of destruction of the anterior thoracic wall with extensive undermining of the subcutis was found. This phenomenon was investigated for reconstructive purposes by firing test shots from two different long guns (caliber 7.92 x 57 repeating rifle with full-jacketed pointed bullet and caliber 12/70 single-barreled shotgun with shotgun slug) into blocks of soap (38 x 25 x 25 cm). The contact shots were fired before and after shortening the barrels (repeating rifle from 60 to 30 cm and single-barreled shotgun from 72 to 36 cm). The volume of the cavities in the simulant was visualized three-dimensionally with the help of a multislice computed tomography (CT) scanner and calculated sectionally. With the repeating rifle and the single-barreled shotgun, the shots from the sawed-off barrels produced significantly larger cavity diameters in the first section of the bullet track. This effect is attributable to the fact that, with a shortened barrel, the gas pressure at the muzzle is higher, thus, leading to increased expansion in the initial part of the wound track in contact shots.

Classification of intervertebral disk degeneration with axial T2 mapping

OBJECTIVE: The aim of this study was to establish an MRI classification system for intervertebral disks using axial T2 mapping, with a special focus on evaluating early degenerative intervertebral disks. MATERIALS AND METHODS: Twenty-nine healthy volunteers (19 men, 10 women; age range, 20-44 years; mean age, 31.8 years) were studied, and axial T2 mapping was performed for the L3-L4, L4-L5, and L5-S1 intervertebral disks. Grading was performed using three classification systems for degenerative disks: our system using axial T2 mapping and two other conventional classification systems that focused on the signal intensity of the nucleus pulposus or the structural morphology in sagittal T2-weighted MR images. We analyzed the relationship between T2, which is known to correlate with change in composition of intervertebral disks, and degenerative grade determined using the three classification systems. RESULTS: With axial T2 mapping, differences in T2 between grades I and II were smaller and those between grades II and III, and between grades III and IV, were larger than those with the other grading systems. The ratio of intervertebral disks classified as grade I was higher with the conventional classification systems than that with axial T2 mapping. In contrast, the ratio of intervertebral disks classified as grade II or III was higher with axial T2 mapping than that with the conventional classification systems. CONCLUSION: Axial T2 mapping provides a more T2-based classification. The new system may be able to detect early degenerative changes before the conventional classification systems can.

Traumatic extra-axial hemorrhage: correlation of postmortem MSCT, MRI, and forensic-pathological findings

PURPOSE: To evaluate the diagnostic accuracy of in situ postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) in the detection of primary traumatic extra-axial hemorrhage. MATERIALS AND METHODS: Thirty forensic neurotrauma cases and 10 nontraumatic controls who underwent both in situ postmortem cranial MSCT and MR imaging before autopsy were retrospectively reviewed. Both imaging modalities were analyzed in view of their accuracy, sensitivity, and specificity concerning the detection of extra-axial hemorrhage. Statistical significance was calculated using the McNemar test. kappa values for interobserver agreement were calculated for extra-axial hemorrhage types and to quantify the agreement between both modalities as well as MRI, CT, and forensics, respectively. RESULTS: Analysis of the detection of hemorrhagic localizations showed an accuracy, sensitivity, and specificity of 89%, 82%, and 92% using CT, and 90%, 83%, and 94% using MRI, respectively. MRI was more sensitive than CT in the detection of subarachnoid hemorrhagic localizations (P = 0.001), whereas no significant difference resulted from the detection of epidural and subdural hemorrhagic findings (P = 0.248 and P = 0.104, respectively). Interobserver agreement for all extra-axial hemorrhage types was substantial (CT kappa = 0.76; MRI kappa = 0.77). The agreement of both modalitites was almost perfect (readers 1 and 2 kappa = 0.88). CONCLUSION: CT and MRI are of comparable potential as forensic diagnostic tools for traumatic extra-axial hemorrhage. Not only of forensic, but also of clinical interest is the observation that most thin blood layers escape the radiological evaluation.

A patient-specific finite element methodology to predict damage accumulation in vertebral bodies under axial compression, sagittal flexion and combined loads

Due to the inherent limitations of DXA, assessment of the biomechanical properties of vertebral bodies relies increasingly on CT-based finite element (FE) models, but these often use simplistic material behaviour and/or single loading cases. In this study, we applied a novel constitutive law for bone elasticity, plasticity and damage to FE models created from coarsened pQCT images of human vertebrae, and compared vertebral stiffness, strength and damage accumulation for axial compression, anterior flexion and a combination of these two cases. FE axial stiffness and strength correlated with experiments and were linearly related to flexion properties. In all loading modes, damage localised preferentially in the trabecular compartment. Damage for the combined loading was higher than cumulated damage produced by individual compression and flexion. In conclusion, this FE method predicts stiffness and strength of vertebral bodies from CT images with clinical resolution and provides insight into damage accumulation in various loading modes.