## 3 Results
### Breast Lesion Sizing: Correlation with Conventional Imaging and Post-Surgery Histology
The two ROIs are clearly visible in the raw MBI image shown in Figure 10. The ROI which was morphologically validated was located in the lower outer quadrant of the breast, had a maximal linear dimension of 24.5 mm and was associated with the invasive tumor in this analysis. The second ROI of volumetric size > 3 cm\({}^{3}\) and rather low solidity (\(\approx\)0.4) was present in the upper breast and could be, interestingly, associated with the extended zone of calcifications, as reported on the patient's mammogram. In the current version of the Havelia QIF, the ROI definition is based on the notion of pixel connectivity, thus \"discontinuous\" constellations such as the one highlighted on ultrasound for this patient case and concurring with the total tumor size (as confirmed with post-surgery histology) could not be revealed. This patient case represents a limitation, which may be addressed in subsequent versions of the Havelia semi-automated lesion sizing method. Discrimination between Malignant and Benign Breast Lesions in a 3-d Feature Space (Shape-Based and Texture-Based Feature Employment)  
While three narrow pc_fib search ranges are systematically used, together with the two wide pc_fib search ranges, to analyze the persistence of radar echoes for lesion detection, for the characterization of the detected lesions, i.e., sizing, shape and texture analysis, the wide pc_fib search ranges are mostly adequate to be employed, as they are expected to be associated with the most complete representations of the lesions in the available set of MBI images. In the course of the FiH clinical investigation of Havelia, mapping of the wide pc_fib search range detections in the 3-d feature space was performed and the posterior probability for each detection to be associated to \"Class #1 = Malignant lesion\" (i.e., probability of malignancy) was computed, as predicted by the trained QDA classifier. If a breast lesion was detected and validated in both wide pc_fib search range MBI images, two probabilities of malignancy were reported for the breast lesion, as depicted in  
Figure 10: Patient 029, IDC in the Left breast (Breast density: BIRADS Category c, VBD = 15.4%): Bilateral Mammogram, Ultrasound Scan and MBI test results of the Left Breast. Figure 11. The maximal probability of malignancy was ultimately considered to represent a unique MBI classification score for the lesion in the data analysis. Patient 027 was the only Group-1 patient (IDC) for whom the probability of malignancy was inferior to 50%, for both wide pc_fib search ranges. Patient 029 (IDC) was an ambiguous case, with a probability of malignancy 16.5% and 55.7% for the 2 wide pc_fib search ranges, correspondingly. As depicted in Figure 10, this was a patient with very dense breasts, thus rendering the ROI delineation sensitive to the specific parameterization of the MBI morphological detector (Wavelia QIF), in its current version. The probability of malignancy was superior to 95% for all the other Group-1 patients (invasive carcinomas), inferior to 38% for all the Group-3 lesion detections (biopsied benign lesions) and inferior to 14% for all the Group-2 lesion detections (c cysts). In Figure 12, four patient cases are used to illustrate the impact of the three selected features (solidity, correlation, busyness) on the MBI lesion classification score. The MBI morphological images (i.e., ROIs detected and validated based on morphological properties and persistence) are superimposed with the outer surface of the breast, as reconstructed using the auxiliary Wavelia Optical Breast Contour Detection (OBCD) subsystem, in Figure 12a for the four patient test cases. The Wavelia OBCD subsystem which is employed to reconstruct the external surface of the breast with high resolution, based on optical data, was earlier introduced in [12; 13; 16]. This superposition serves to better highlight the location of the MBI breast lesion detection with reference to the nipple of the breast, which is visible in the OBCD reconstruction.