Limited view reconstructions with transmission ultrasound tomography - clinical implications and quantitative accuracy

The ability to conduct 'partial field of view' scans in QT ultrasound transmission ultrasound is investigated. The standard tomographic data acquisition is typically conducted in a full 360 degree aperture, which may limit the possibility of real time intervention and/or patient positioning for medical imaging. Transmission ultrasound has many advantages over other imaging modalities such as, it does not emit ionizing radiation, does not require contrast agent, etc. A partial field of view data acquisition in this context is therefore attractive. Three scenarios are investigated: breast, whole body, and orthopedic imaging. A full suite of 180 views at 2 degree intervals and 192 mm in the vertical direction was collected from the QT ultrasound (TM) scanner in the orthopedic and whole body scenarios. The vertical extent of the breast image varied with breast size. Subsequent reconstructions were carried out with a subset of the views incorporated. The contiguous sector of missing angles varied from 8, 16, 32, 40, 60 and 92 degrees. The difference between the corresponding images was quantitatively and qualitatively analyzed and compared. It was found that a large lacuna (gap) of contiguous data did not significantly (clinically) degrade image quality, and the quantitative values, where relevant. The open acquisition scenario allows us to carry out medical intervention as well as potentially decrease patient anxiety. The quantitative nature of the degradation is noted and correlated with the missing sector angles for clinical scenarios, and the implications discussed.