# Wavelia Breast Imaging: The Optical Breast Contour Detection Subsystem
## 3 Results and Discussion
### D Breast Surface Reconstruction: Indicative Results from the First Ten Patient Scans
For the purpose of the quality check, two versions of the breast surface are reconstructed using two interlaced and non-overlapping subsets of the full set of recorded azimuthal samples (Subset 1: camera at the azimuthal positions {0:60:300}\({}^{\circ}\), Subset 2: camera at the azimuthal positions {30:60:330}\({}^{\circ}\)). The OBCD scan is validated, as long as the RMS distance between the two surfaces is inferior to 0.8 mm. The OBCD scans of all the patients participating in the first clinical investigation so far have been validated with this criterion, which indicates that if sub-millimetric precision has been demonstrated in the case of static breast phantoms, the same level of precision can be maintained during the OBCD scan of a real breast. Obviously, before the scan starts, the patient is instructed by the research assistant to stay still, avoid heavy breathing and maintain a relaxed position during the total duration of the scan, which lasts approximately 1 min. Waelia OBCD Breast Surface Reconstruction: Towards Development of a Real-Time Support Tool for the Waelia MBI Examination and Breast Cancer Diagnosis  
As specified in the introduction, in the first prototype of the Waelia breast imaging medical device, the OBCD and MBI subsystems are integrated in two separate examination tables on which the two scans are sequentially performed, while the patient positions herself in approximately the same way during both examinations. The OBCD scan is performed while the breast is hanging in the air, while the MBI scan is performed with the breast being immersed in a coupling (or transition) creamy liquid, which is opaque. Given this implementation, at this stage of development of the Waelia system, the breast surface reconstruction using the OBCD subsystem serves to define the amount of transition liquid to be used for the MBI scan and also to define the length of the vertical scan of the pendulum breast with the MBI system. In the context of the first-in-human clinical study of the Waelia breast imaging medical device, it has also served to verify the correspondence of the breast anatomy, as retrieved using two distinct imaging modalities (Waelia OBCD and MBI), tested for the first time on humans. Rigid registration is performed to match the reconstructed breast surfaces, as computed during the two scans (OBCD and MBI). The ultimate objective of this operation is to exploit the sub-millimetric level of detail of the OBCD-derived breast surface, as a high-quality envelope for the MBI-derived breast abnormality detections for breast cancer diagnosis. It is recalled that due to the physically limited spatial resolution that can be achievable at the microwave frequency range, the exact orientation of the pendulums breast under scan, as well as details such as the nipple location, cannot be defined using the MBI-derived reconstruction of the breast surface alone. With no access to such level of detail, the annotation of the breast quadrant and clock-position at which an abnormality has been detected with MBI cannot be very accurate either, when using the MBI system stand-alone. Given the potential deformation of the breast when submerged in the transition liquid, the exploitation of the OBCD breast surface for refined localization of the detected breast abnormalities with MBI is possible only in the case of minimally deformed breasts, in the actual implementation. In Figure 36a, the example of a young patient (37 years old) with medium-sized breasts, which have not been significantly deformed when immersed in the transition liquid, is shown. For such a patient, the registered OBCD contour can be safely used as envelope for the breast abnormalities, as detected with MBI. In Figure 36b, the example of an elderly patient (68 years old) with large breasts, which have been significantly deformed when immersed in the transition liquid, is shown.