Three-dimensional evaluation of the relationship between nasopharyngeal airway shape and adenoid size in children

Objective

To evaluate the shapes and sizes of nasopharyngeal airways by using cone-beam computed tomography and to assess the relationship between nasopharyngeal airway shape and adenoid hypertrophy in children.

Methods

Linear and cross-sectional measurements on frontal and sagittal cross-sections containing the most enlarged adenoids and nasopharyngeal airway volumes were obtained from cone-beam computed tomography scans of 64 healthy children (11.0 ± 1.8 years), and the interrelationships of these measurements were evaluated.

Results

On the basis of frontal section images, the subjects' nasopharyngeal airways were divided into the following 2 types: the broad and long type and the narrow and flat type. The nasopharyngeal airway sizes and volumes were smaller in subjects with narrow and flat airways than in those with broad and long airways (p < 0.01). Children who showed high adenoid-nasopharyngeal ratios on sagittal imaging, indicating moderate to severe adenoid hypertrophy, had the narrow and flat type nasopharyngeal airway (p < 0.01).

Conclusions

Cone-beam computed tomography is a clinically simple, reliable, and noninvasive tool that can simultaneously visualize the entire structure and a cross section of the nasopharyngeal airway and help in measurement of adenoid size as well as airway volume in children with adenoid hypertrophy.

Optimization of nano-phosphor synthesis by including sensitizer doping for medical X-ray imaging

Medical radiation imaging systems employ phosphors such as CaWO4 as X-ray receptor materials. Unfortunately, the conversion efficiencies of these materials are rather low (approx. 5%). Alternatives that comprise a bulk structure have been fabricated from rare earth metals, but they are not efficient enough to produce high quality images. Nano-phosphors do not suffer from the limitations inherent to the bulk structures of conventional phosphors. We examined the effects of sensitizer doping conditions on the optical characteristics and morphology of the rare earth phosphor Gd2O3:Eu to fabricate a novel type of nano-phosphor. We optimized a temperature solution-combustion procedure for producing phosphors doped with 5 wt% Eu. Scanning electron microscopy images showed that the phosphors were 20-30 nm in diameter and X-ray diffraction analysis revealed that they underwent polycrystalline growth upon the addition of a sensitizer, similar to the polycrystalline growth of bulk phosphors. In addition, the phosphors exhibited a strong peak at 613 nm and luminescence similar to conventional phosphors. Phosphors that were produced using citric acid as a sensitizer showed more than double the level of luminescence and could be used to produce higher quality images compared to non-sensitized phosphors. The phosphors also exhibited a high degree of luminescence stability.

Post-operative soft tissue changes in patients with mandibular prognathism after bimaxillary surgery

PURPOSE

The objective of this study was to evaluate the three-dimensional soft tissue changes observed over time after bimaxillary surgery for mandibular prognathism using cone-beam computed tomography (CBCT) superimposed imaging.

MATERIALS AND METHODS

CBCT scans were obtained for 25 patients before bimaxillary surgery (T0), at 2 months after surgery (T1) and at 6 months after surgery (T2). Cephalometric variables from the reoriented volumetric images were measured and compared at T0, T1, and T2. The quantitative surface displacement in the middle and the lower third of the facial soft tissue using CMF tools was assessed by superimposing the T0 and T1 or T0 and T2 3D images.

RESULTS

The soft tissue in middle third of face moved forward at T1 and significantly moved backward from T1 to T2 (Ch-Al, p < 0.001; Al, p < 0.05; Pn, p < 0.05). Most of the soft tissue changes from T1 to T2 were not correlated with the hard tissue changes (p > 0.05), while the cheeks were positively correlated with the soft tissue around them (Exo-Al, p < 0.01; Ch-Al, p < 0.01).

CONCLUSION

Post-operative soft tissue changes occurred in the middle third of the face and are considered to be more complex than the changes in the lower third of face. Therefore, soft tissue assessment at least 6 months after surgery is desirable.

Three-dimensional changes in pharyngeal airway in skeletal class III patients undergoing orthognathic surgery

PURPOSE

It has often been hypothesized that mandibular setback surgery causes narrowing of the pharyngeal airway. We examined whether the pharyngeal airway narrowed after orthognathic surgery in patients undergoing either mandibular setback surgery or bimaxillary surgery and whether the amount of narrowing of the pharyngeal airway was any different after mandibular setback surgery or bimaxillary surgery.

MATERIALS AND METHODS

Cone-beam computed tomography scans were obtained for 21 patients who were assigned to either mandibular setback surgery or bimaxillary surgery. The anteroposterior dimension, lateral width, cross-sectional area, and volume of each subject's pharyngeal airway were measured before and after surgery.

RESULTS

The pharyngeal airway showed significant narrowing after both mandibular setback surgery and bimaxillary surgery. The amount of change in the anteroposterior dimension and cross-sectional area on the posterior nasal spine plane and the length of the pharyngeal airway showed significant differences between the 2 groups.

CONCLUSION

The amount of narrowing of the pharyngeal airway was smaller in patients undergoing bimaxillary surgery than in the patients undergoing mandibular setback surgery.

Training environment for inferior vena caval filter placement

This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the Laboratory for Advanced Computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.