Multi-view stereophotogrammetry for post-mastectomy breast reconstruction.

A multi-view three-dimensional stereophotogrammetry system was developed to capture 3D shape of breasts for breast cancer patients. The patients had received immediate unilateral breast reconstruction after mastectomy by the extended latissimus dorsi flap and without contralateral surgery. In order to capture the whole breast shape including the inframammary fold, the patients were introduced to the imaging room and leaned over the imaging rig to open up the inframammary fold and to expose the entire area of each breast. The imaging system consisted of eight high-resolution ([Formula: see text] pixels) digital cameras and four flash units. The cameras were arranged in four stereo pairs from four different view angles to cover the whole surface of the breasts. The system calibration was carried out ahead of every capture session, and the stereo images were matched to generate four range images to be integrated using an elastic model proposed. A watertight breast mesh model was reconstructed to measure the volume of the breast captured. The accuracy of using the developed multi-view stereophotogrammetry system for breast volume measurement was 11.12cc with SEM 7.74cc, comparing to the measurements of the water displacement method. It was concluded that the 3D stereophotogrammetry image system developed was more reliable than the method of water displacement.

The importance of the pose in three-dimensional imaging of the ptotic breast.

INTRODUCTION: 3D imaging of the breast has recently emerged as a new method for objective breast assessment. However in the ptotic breast shape, which is seen in the majority of cases, the sub-mammary fold remains obscured when the breast is captured in an upright body posture. METHOD: A self-designed positioning frame for 3D breast capture was utilized as a safe positioning aide. Six volunteers stood on an adjustable standing step, leaning with the hips against a soft-coated hip roll while stretching forward with the upper body extending to a nearly horizontal position and reaching with the arms forward resting on arm pads. 3D breast capture was conducted simultaneously with eight digital cameras that were positioned to capture the right, left, anterior and inferior views of the breast. Capture was repeated three times at different time intervals. The reproducibility of the pose, captures and 3D measurements were investigated. RESULTS: The custom-made positioning frame allowed the complete capture of the breast, even in the ptotic shapes. The investigation of the reproducibility revealed a 6.25% standard deviation of the pose; this being the variable with the smallest variation compared with the variations obtained for reproducibility of captures and 3D measurements. The difference between the first and second pose was not significant at 95% CI (-77.3; 11.9), p = 0.119. CONCLUSION: The presented system used a self-designed positioning frame, by which the complete capture of the ptotic breast in near horizontal upper body posture was achieved. Reproducibility of the pose for 3D capture was satisfactory.

Subjective versus objective assessment of breast reconstruction.

BACKGROUND: To date breast assessment has been conducted mainly subjectively. However lately validated objective three-dimensional (3D) imaging was developed. The study aimed to assess breast reconstruction subjectively and objectively and conduct a comparison. METHODS: In forty-four patients after immediate unilateral breast reconstruction with solely the extended latissimus dorsi flap the breast was captured by validated 3D imaging method and standardized 2D photography. Breast symmetry was subjectively evaluated by six experts who applied the Harris score giving a mark of 1-4 for a poor to excellent result. An error study was conducted by examination of the intra and inter-observer agreement and agreement on controls. By Procrustes analysis an objective asymmetry score was obtained and compared to the subjective assessment. RESULTS: The subjective assessment showed that the inter-observer agreement was good or substantial (p-value: <0.0001). There was moderate agreement on the controls (p-value: <0.0001) and fair (p-values: 0.159, 0.134, 0.099) to substantial (p-value: 0.005) intra-observer agreement. The objective assessment revealed that the reconstructed breast showed a significantly smaller volume compared to the opposite side and that the average asymmetry score was 0.052, ranging from 0.019 to 0.136. When comparing the subjective and objective method the relationship between the two scores was highly significant. CONCLUSION: Subjective breast assessment lacked accuracy and reproducibility. This was the first error study of subjective breast assessment versus an objective validated 3D imaging method based on true 3D parameters. The substantial agreement between established subjective breast assessment and new validated objective method supported the value of the later and we expect its future role to expand.

Investigation into variation and errors of a three-dimensional breast imaging system using multiple stereo cameras.

BACKGROUND: Errors derive from the variability seen in the repeat volume measurements for a particular individual. The aim of this study was to evaluate the variation and errors of a three-dimensional (3D) multiple stereo camera system for objective breast assessment. It was also investigated whether there was any correlation between these errors and the size of the breast. METHODS: A prototype eight camera multiple stereophotogrammetry system was utilized. The volumes of nine plaster breast models were determined by 3D imaging and the correlation between the size of the models and the variability of the measurements was investigated after ten repeats. The breasts of six live volunteers were examined following a specific protocol. The breasts were captured six times, three times each on two different occasions; from each breast capture a three-dimensional model was built and the breast volume was measured three times with breast analysis tool (BAT) software. This allowed for an assessment of the variability introduced at each stage of the measurement procedure. The correlation between the size of the breast and the variability of the measurements was investigated. Results of volume measurements by water displacement method, repeated ten times with the plaster models and six times with the live models, were used for comparison. RESULTS: The correlation between the size of the plaster models and the variability of the measurements revealed a significant correlation (p = 0.033), indicating that the larger the model, the more variable were the results. The correlation between the size of the breasts in the live models and the variability of the results revealed a non-significant correlation (p = 0.342), but there was a visible trend that the larger breasts showed more variable results. The average variation in the repeated measurements on each individual was found to be 32.95 cc across the two different poses, 19.43 cc across the various captures, and 28.32 across the different volume calculations with the BAT software. The error is less than what is clinically visible with the human eye, which is about 50 cc variation in volume by subjective assessment. As a proportion of the mean volume, namely 6.9%, 4.0% and 5.9% respectably, the values are small and indicate that the reproducibility of the system is good. CONCLUSION: The 3D imaging system using multiple stereo cameras revealed a positive correlation between the size of plaster models and the breasts of live models and the reproducibility of the measurements, indicating that the variation was higher for the larger sizes. The relationship was significant in the plaster models but not in the live models, although a trend was observed. The assessment of the variation and errors of the system was part of the necessary procedure that should be considered for the validation of any new measurement technology for breast assessment.

Objective evaluation of the latissimus dorsi flap for breast reconstruction using three-dimensional imaging.

BACKGROUND: The latissimus dorsi muscle flap is a common method for the reconstruction of the breast following mastectomy. The study aimed to assess the quality of this reconstruction using a three-dimensional (3D) imaging method. The null hypothesis was that there was no difference in volume between the reconstructed breast and the opposite side. METHODS: This study was conducted in forty-four patients who had had immediate unilateral breast reconstruction by latissimus dorsi muscle flap. The breast was captured using the 3D imaging system. Ten landmarks were digitised on the 3D images. The volume of each breast was measured by the application of Breast Analysis Tool software. The symmetry of the breast was measured using Procrustes analysis. The impact of breast position, orientation, size and intrinsic shape on the overall breast asymmetry was investigated. RESULTS: The null hypothesis was rejected. The reconstructed breast showed a significantly smaller volume when compared to the opposite side, p < 0.0001, a mean difference of 176.8 cc and 95% CI (103.5, 250.0). The shape and the position of the reconstructed breast were the main contributing factors to the measured asymmetry score. CONCLUSIONS: 3D imaging was efficient in evaluating the outcome of breast surgery. The latissimus dorsi muscle flap on its own for breast reconstruction did not restore the volume and shape of the breast fully lost due to complete mastectomy. The modification of this method and the selection of other or additional surgical techniques for breast reconstruction should be considered. The asymmetry analysis through reflection and Procrustes matching was a useful method for the objective shape analysis of the female breast and presented a new approach for breast shape assessment. The intrinsic breast shape and the positioning of the breast were major components of postoperative breast asymmetry. The reconstructed breast was smaller overall than the un-operated breast at a significant level when assessing the breast volume using the surface area. 3D imaging by multiple stereophotogrammetry was a useful tool for volume measurements, shape analysis and the evaluation of symmetry.

Investigation into accuracy and reproducibility of a 3D breast imaging system using multiple stereo cameras.

BACKGROUND: The aim of this study was to evaluate the validity of a three-dimensional (3D) multiple stereo camera system for objective breast assessment. METHODS: A multiple stereo camera system, which consisted of four pods and eight cameras, two cameras on each pod, developed by Glasgow University, was used. Nine specially shaped plaster breast models were captured once, 3Dmodels were constructed and the volume of each plaster model was measured 10 times by the breast analysis tool (BAT) software. A comparison was conducted with water displacement method, and measurements were repeated 10 times. The breast of six live volunteers was captured six times; from each breast capture, a 3D model was constructed and the volume was measured with BAT software. Breast volume assessment by the water displacement method was repeated six times. RESULTS: In all plaster casts, the discrepancies in volume measurements between 3D imaging and water displacement methods did not exceed 40 cc. The overall mean relative difference was 5%. The differences of the two methods were not significant at p = 0.189, overall mean difference: 11.1 cc and 95% confidence interval (CI) was (-6.732, 28.976). In the live models, the differences in breast volume measurements between the 3D imaging and water displacement methods were significant at p ≤ 0.017, overall mean difference: 207.05 cc and 95% CI (56.12, 357.98). Measurements by 3D imaging were consistently smaller. In the live models, 3D imaging overall was a more reproducible method for measuring breast volume than the water displacement method with a standard deviation of 36 units cc(-1) and 62.6 units cc(-1), respectively. CONCLUSIONS: The 3D breast imaging system using multiple stereo cameras was accurate for measuring the volumes of breast-shaped plaster models, and it was more reproducible than the water displacement method in live models. 3D imaging is a reliable method for the comparative assessment of breast volume.

Dorsal urethral fistula: case report and review of literature.

Urethral fistula is a rare, but recognized, entity. We report the case of a young diabetic patient who developed urethral fistula on the dorsum of penis after debridement for necrotizing fasciitis. This cause and location for urethral fistula is extremely rare, and we were unable to find a similar case in published studies. A brief literature search for various causes of urethral fistula was made, and the likely mechanisms for the cause of the fistula were explored.