TMJ response to mandibular advancement surgery: an overview of risk factors

Objective: In order to understand the conflicting information on temporomandibular joint (TMJ) pathophysiologic responses after mandibular advancement surgery, an overview of the literature was proposed with a focus on certain risk factors. Methods: A literature search was carried out in the Cochrane, PubMed, Scopus and Web of Science databases in the period from January 1980 through March 2013. Various combinations of keywords related to TMJ changes [disc displacement, arthralgia, condylar resorption (CR)] and aspects of surgical intervention (fixation technique, amount of advancement) were used. A hand search of these papers was also carried out to identify additional articles. Results: A total of 148 articles were considered for this overview and, although methodological troubles were common, this review identified relevant findings which the practitioner can take into consideration during treatment planning: 1- Surgery was unable to influence TMJ with preexisting displaced disc and crepitus; 2- Clicking and arthralgia were not predictable after surgery, although there was greater likelihood of improvement rather than deterioration; 3- The amount of mandibular advancement and counterclockwise rotation, and the rigidity of the fixation technique seemed to influence TMJ position and health; 4- The risk of CR increased, especially in identified high-risk cases. Conclusions: Young adult females with mandibular retrognathism and increased mandibular plane angle are susceptible to painful TMJ, and are subject to less improvement after surgery and prone to CR. Furthermore, thorough evidenced-based studies are required to understand the response of the TMJ after mandibular advancement surgery

Demonstration of correlations between clinical and physical image quality measures in chest and lumbar spine screen-film radiography

The ability to predict clinical image quality from physical measures is useful for optimization in diagnostic radiology. In this work, clinical and physical assessments of image quality are compared and correlations between the two are derived. Clinical assessment has been made by a group of expert radiologists who evaluated fulfilment of the European image criteria for chest and lumbar spine radiography using two scoring methods: image criteria score (ICS) and visual grading analysis score (VGAS). Physical image quality measures were calculated using a Monte Carlo simulation model of the complete imaging system. This model includes a voxelized male anatomy and was used to calculate contrast and signal-to-noise ratio of various Important anatomical details and measures of dynamic range. Correlations between the physical image quality measures on the one hand and the ICS and VGAS on the other were sought. 16 chest and 4 lumbar spine imaging system configurations were compared in frontal projection. A statistically significant correlation with clinical image quality was found in chest posteroanterior radiography for the contrast of blood vessels in the retrocardiac area and a measure of useful dynamic range. In lumbar spine anteroposterior radiography, a similar significant correlation with clinical image quality was found between the contrast and signal-to-noise ratio of the trabecular structures in the L1-L5 vertebrae. The significant correlation shows that clinical image duality can, at least in some cases, be predicted from appropriate measures of physical image quality

The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria.

The Commission of the European Communities (CEC) research project Predictivity and optimisation in medical radiation protection" addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization or a radiographic process and (2) whether significant differences in image quality based on these criteria could be detected in a controlled project with well known physical and technical parameters, In the present study. chest radiographs on film were produced using healthy volunteers. Four physical/technical parameters were varied in a carefully controlled manner: tube voltage ( 102 kVp and 14 1 kVp). nominal speed class (160 and 320). maximum film density (1.3 and 1.8) and method of scatter reduction (grid (R = 12) and air gap). The air kerma at the entrance surface was Measured for all patients and the risk-related dose H-Golem, based on calculated organ-equivalent dose conversion coefficients and the measured entrance air kerma values. was calculated, Image quality was evaluated by a group of European expert radiologists using a modified version of the CEC quality criteria. For the two density levels. density level 1.8 was significantly better than 1.3 but at the cost of a higher patient radiation exposure. The correlation between the number of fulfilled quality criteria and H-Golem was generally poor. An air gap technique resulted in lower doses than scatter reduction with a grid but provided comparable image quality. The criteria can be used to highlight optimum radiographic technique in terms of image quality and patient dose, although not unambiguously. A recommendation for good radiographic technique based on a compromise between image quality and risk-related radiation dose to the patient is to use 141 kVp. an air gap, a screen-film system with speed 320 and an optical density of 1.8.