Magnetic resonance images of the head were taken in five monozygotic and seven dizygotic twins in order to calculate bilaterally masseter muscle cross-sectional areas and total volume. Comparing correlation coefficients between cotwins, genetic influences could be expected for maximal cross-sectional area but not for volume measurements. Model fitting revealed that additive genetic factors explained 93.9% of the variance for the left and 82.4% for the right maximal masseter muscle cross-sections. It is anticipated that while the number of masseter muscle fibers is under strong genetic control, the length of individual fibers can be influenced by specific environmental factors. In the second part of the investigation, cephalometric measurements from lateral headplates were compared with these masseter muscle values in 10 twin pairs. Only three of the 15 angular and five (three vertical, one transversal, and one sagittal measurement) of the 20 linear measurements were significantly correlated with masseter muscle values.

Face↗

PubMedDate not supplied

Pycnodysostosis of Maroteaux and Lamy. Osteopetrosis acro-osteolytica.

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Child, Preschool↗

PubMedDate not supplied

Diagnostic accuracy of ultrasonography and surgical decision-making in patients referred for suspicion of appendicitis.

Two groups of patients referred for suspicion of acute appendicitis were compared to evaluate the accuracy of preoperative ultrasonography (US) and surgical decision-making. In one retrospective study, US was performed by trainees using a 3.5 MHz probe (219 patients). In the second prospective study, US was performed by a resident radiologist using a 5 MHz probe (144 patients). US accuracy rose from 65% to 90%, especially due to an improved negative predictive value (from 52% to 92%). The positive predictive value of US was 89%. The sonographically adjusted clinical decision to operate was correct in 85%. Thus, all patients with positive US should be operated. In contrast, clinical judgment must prevail in case of negative US findings in order to prevent surgical delay in about 11%. The negative laparotomy rate decreased by 5% only. This is probably due to the limited influence of negative US findings on surgical decision. US is to be recommended in all patients suspected for acute appendicitis when performed with an appropriate probe by an experienced ultrasonographist. However, it may not, on it self, reduce the rate of unnecessary operative procedures.

Adolescent↗

PubMedDate not supplied

Computer-assisted planning of oral implant surgery: a three-dimensional approach.

A planning system for oral implant surgery based on a true three-dimensional approach is described. This system allows the interactive placement and adjustment of axial-symmetric models representing implants in the jawbone structures visible on computerized tomographic volume data. Simultaneous visualization is possible on two-dimensional reformatted images and on three-dimensional-derived bone surface representations. This approach largely outperforms the manual planning practice based on two-dimensional dental computerized tomographic images printed or on film.

Computer Simulation↗

PubMedDate not supplied

Computerised axial tomography of abdominal aortic aneurysm. Report of 5 cases.

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Aged↗