Improved accuracy of breast volume calculation from 3D surface imaging data using statistical shape models

Background Three-dimensional (3D) scanning is an established method of breast volume estimation. However, this method can never be entirely precise, since the thoracic wall cannot be imaged by the surface scanner. Current methods rely on interpolation of the posterior breast border from the surrounding thoracic wall. Here, we present a novel method to calculate the posterior border and increase the accuracy of the measurement. Methods Using principal component analysis, computed tomography images were used to build a statistical shape model (SSM) of the thoracic wall. The model was fitted to 3D images and the missing thoracic wall curvature interpolated (indirect volumetry). The calculations were evaluated by ordinary least squares regression between the preoperative and postoperative volume differences and the resection weights in breast reduction surgery (N = 36). Also, an SSM of the breast was developed, allowing direct volumetry. Magnetic-resonance images (MRI) and 3D scans were acquired from 5 patients in order to validate the direct 3D volumetry. Results Volumetry based on a SSM exhibited a higher determination coefficient (R2 = 0,737) than the interpolation method (R2 = 0,404). The methods were not equivalent (p = 0.75), suggesting that the methods significantly differ. There was no influence of BMI on the correlation in either method. The MRI volumetry had a strong correlation with the 3D volumetry (R2 = 0,978). Conclusion The SSM-based method of posterior breast border calculation is reliable and superior to the currently used method of interpolation. It should serve as a basis of software applications aiming at calculation of breast volume from 3D surface scanning data.

Improved accuracy of breast volume calculation from 3D surface imaging data using statistical shape models

BackgroundThree-dimensional (3D) scanning is an established method of breast volume estimation. However, this method can never be entirely precise, since the thoracic wall cannot be imaged by the surface scanner. Current methods rely on interpolation of the posterior breast border from the surrounding thoracic wall. Here, we present a novel method to calculate the posterior border and increase the accuracy of the measurement.MethodsUsing principal component analysis, computed tomography images were used to build a statistical shape model (SSM) of the thoracic wall. The model was fitted to 3D images and the missing thoracic wall curvature interpolated (indirect volumetry). The calculations were evaluated by ordinary least squares regression between the preoperative and postoperative volume differences and the resection weights in breast reduction surgery (N=36). Also, an SSM of the breast was developed, allowing direct volumetry. Magnetic-resonance images (MRI) and 3D scans were acquired from 5 patients in order to validate the direct 3D volumetry.ResultsVolumetry based on a SSM exhibited a higher determination coefficient (R2=0,737) than the interpolation method (R2=0,404). The methods were not equivalent (p=0.75), suggesting that the methods significantly differ. There was no influence of BMI on the correlation in either method. The MRI volumetry had a strong correlation with the 3D volumetry (R2=0,978).ConclusionThe SSM-based method of posterior breast border calculation is reliable and superior to the currently used method of interpolation. It should serve as a basis of software applications aiming at calculation of breast volume from 3D surface scanning data.

Evaluation measure of 3d volumetry of masseter hypertrophy: association with modalities of imaging

Masseteric hypertrophy is a benign condition, asymptomatic and rare, characterized by the excessive development of the masseter muscle, which usually results in aesthetic complaints. The imaging exams for differential diagnosis of pathologies in the parotid-masseteric region is always recommended. This work aims the imaging characterization of masseteric hypertrophy through the report of two clinical cases combining different imaging modalities: panoramic radiography, magnetic resonance imaging, computed tomography, ultrasonography and 3D volumetry. Two male subjects with no family history of masseteric hypertrophy were referred to a diagnostic center in dentomaxillofacial radiology due to an increase in bilateral facial volume in the masseteric region. Images of the panoramic radiography showed an increase of the bilateral mandibular angle in both cases. Using computerized tomography, bilateral masseter muscle hypertrophy was demonstrated in the patients, and magnetic resonance scan and ultrasound examination were performed for better visualization and muscle measurement. 3D volumetry assessment of musculature showed as additional tool to evaluate the status of the masseter muscles in patients with Masseteric hypertrophy. Therefore, the association of imaging examinations allowed to perform the imaging characterization of masseteric hypertrophy with presence of bone exostosis.