Reflection mode diffraction tomography is expected to reconstruct a higher resolution image than transmission mode. Its image reconstruction problem, however, in the many cases of practical uses becomes ill-posed one. In this paper, a new reconstruction method of limited angle reflection mode diffraction tomography using maximum entropy method is proposed. Results of simulation showed that the method was able to reconstruct the better quality images than IR method poposed by Kak, et al.

This paper describes a novel discrimination method of pulmonary nodules based on statistical analysis of thoracic computed tomography (CT) scans. Our previous Computer-Aided Diagnosis (CAD) system can detect pulmonary nodules from CT scans, but, at the same time, yields many false positives. In order to reduce the false positives, the method proposed in the present paper uses a relationship between pulmonary nodules, false positives and image features in CT scans. The trend of variation of the relationships is acquired through statistical analysis of a set of CT scans prepared for training. In testing, by use of the trend, the method predicts the appearances of pulmonary nodules and false positives in a CT scan, and improves the accuracy of the previous CAD system by modifying the system's output based on the prediction. The method is applied to 218 actual thoracic CT scans with 386 actual pulmonary nodules. The receiver operating characteristic (ROC) analysis is used to evaluate the results. The area under the ROC curve (Az) is statistically significantly improved from 0.918 to 0.931.

Technique of Measuring 3-D velocity vector components is important for the correct diagnosis of the blood flow pattern and quantitative assessment of intratumor perfusion. However, present equipment based on ultrasonic Doppler can not provide us true 3-D velocity. To overcome the problem, we previously proposed a new method of 3-D velocity vector measurement. The method uses 2-D array probe and enable us to obtain three components of velocity vector with real time by integrating the Doppler phase shift on the each element with the relative small single aperture compared with conventional method. Basic performance of the method has been evaluated by computer simulation. In this paper, to evaluate the feasibility of the proposed method, experimental investigation using a simple ring array probe and a phantom were carried out. Three components of velocity vector for different velocity magnitude and flow direction were measured. Experimental results validated its ability of measuring 3-D velocity and its feasibility.

A digest is provided of work carried out at the Institute of Cancer Research to develop freehand elastography and apply it to breast investigations. Topics covered include the development of freehand elastography and its relationship to other methods, a description of the system for off-line clinical evaluation of the freehand method, comparison of the physical performances of freehand and mechanical elastography, early clinical results on 70 breast tumours, real-time imaging, quantitative elastography and psychophysical aspects of the detection and assessment of elastic lesions. Progress in developing this new medical imaging modality is occurring rapidly throughout the world and its future looks promising.