3D Transmission with 360 degree compounded reflection ultrasound has been shown effective as a basis for quantitative assessment of breast density on a continuous scale that is compatible with existing FDA approved methods. Breast density is an important risk factor in several breast cancer risk models. Unfortunately, methods utilizing projections (e.g. mammography) or even tomosynthesis do not fully represent the true topological diversity and complexity of the human breast. Presently, the use of the reflection image is important in delineation of the breast volume from the water bath. However, the reflection data and/or image may not be available in some scenarios due to scanner design or equipment malfunction. Furthermore, other data (such as levels of data) may be missing or not collected for specific, perhaps economic, reasons. The Spearman Rank coefficient for correlation of the 3D transmission and reflection ultrasound based quantitative breast density (QBD) was 93% which decreased to 91.5% when reflection image/data were removed. The Spearman r increased again to 95% when smoothing was applied to the speed and attenuation images. The results indicate that even without the reflection data information, the 3D transmission ultrasound characterization of the tissue yields QBD values commensurate with FDA approved methods. This may make the construction of certain quantitative breast estimator devices more economical and useful.