X-ray imaging technique for in vitro tissue composition measurements using saline/iodine displacement

An in vitro radiographic technique has been developed to study the composition of arterial specimens, quantifying both the calcified and soft tissue components. In the authors´ new method, planar radiographs of a phantom were obtained when the phantom was immersed in: (a) a saline bath using a 45-kV, spectrum with no added filtration; and, (b) an iodine bath using a 100-kV, spectrum with 12.5 mm Al added filtration. These radiographs were then digitized and converted into bone-equivalent and Lucite images using calibration data obtained from images of Lucite and bone-equivalent step wedges. Thickness measurements from these images yielded average accuracies of ±300 μm for the bone-equivalent image, and ±80 μm for the Lucite image. The precision (one standard deviation) of the thickness measurements was 200 μm and ±150 μm for the bone-equivalent and the Lucite images respectively. Although the accuracy and precision of bone-equivalent thickness measurements were not as good as those obtained with dual-energy X-ray imaging, the accuracy and precision of the Lucite thickness measurements are shown to be much better. The high accuracy and precision of the Lucite thickness measurements make this technique a very good complement to dual-energy radiography (with its high accuracy and precision of bone-equivalent thickness measurement) to study the physical properties of excised arterial specimens