Rationale for, and recent progress in, 3D reconstruction of the heart and lungs

Three-dimensional information of the structure and function of the heart and lungs is needed for several reasons including the following: (a) An apparent change in shape or location of the imaged ventricular wall may either be due to the heart moving through the imaged region, or because it truly represents that change in geometry, or a mixture of the two. In addition, as diseases of the heart and lungs are often heterogeneous in their spatial distribution, we expect the structural and functional consequences to also be heterogeneous in their spatial distribution; (b) Comparison of a selected anatomic feature (e.g., a coronary artery stenosis or pulmonary opacity) at long time intervals may make detection and/or quantitation of lesion progression questionable. The use of a 3D reconstruction to calculate a projection image with a reproducible angle of view is a particularly powerful consequence of 3D image reconstruction; (c) Use of image information from one imaging modality helps improve the quantitative characteristics of an image generated with another imaging modality; (d) Radiation treatment planning requires knowledge of the 3D distribution of radiation attenuation coefficients so that 3D distribution of the regional deposition of radiation energy can be quantitated, (e) Allows for indirect estimation of the physiological dimensions of one aspect of an organ so that the degree of disease of that part of the organ can be assessed. This can be achieved by imaging contiguous and/or organs dependant on the structure of immediate interest; and (f) For heart or lung transplant the shape and volume of the anatomic space available for the new organ should be known to prevent the problem of compressing the organ or the adjacent tissues after placement of the organ.