title: X-ray imaging technique for in vitro tissue composition measurements using saline/iodine displacement: experimental verification.
abstract: A novel in vitro radiographic technique using saline/iodine displacement, which can be used to study the bone-equivalent and soft-tissue-equivalent thicknesses within vessel walls, was applied to imaging of arterial specimens. Results concerning the accuracy and precision of the bone-equivalent and soft-tissue-equivalent thickness measurements obtained with this technique are reported and discussed. Planar radiographs of a phantom were obtained under two different conditions: (1) when it is immersed in an isotonic saline solution using a 45-kVp spectrum with no added filtration, and (2) when it is immersed in a concentrated iodine solution using a 100-kVp spectrum with 12.5-mm aluminum-added filtration. Calibration step wedges made out of bone-mimicking and soft-tissue-mimicking materials are imaged simultaneously to generate calibration curves that are used to convert the radiographs into bone-equivalent and total-thickness images. A soft-tissue-thickness image is obtained from the subtraction of the bone-equivalent image from the total-thickness image. Thickness measurements obtained from these images yielded average accuracies of +/- 110 microns for both the bone-equivalent and the soft-tissue-equivalent images. The precision (one standard deviation) of the thickness measurements was +/- 60 and +/- 90 microns for the bone-equivalent and the soft-tissue-equivalent images, respectively. In conclusion, since calcified plaque can become as thick as 3-4 mm, the saline/iodine displacement technique has the potential to be a very useful technique for ex vivo studies of the progression of atherosclerosis because of its high accuracy and precision.
authors.affiliation: Imaging Research Laboratories, John P. Robarts Research Institute, London, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Moreau
authors.forename: P J
authors.initials: PJ
authors.lastname: Dunmore-Buyze
authors.forename: D W
authors.initials: DW
authors.lastname: Holdsworth
authors.forename: A
authors.initials: A
authors.lastname: Fenster
mesh_terms: D000792:Angiography / Q000295:instrumentation / Q000379:methods*; D001158:Arteries / Q000378:metabolism*; D001161:Arteriosclerosis / Q000000981:diagnostic imaging* / Q000378:metabolism*; D055592:Biophysical Phenomena; D001703:Biophysics; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007455:Iodine; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012965:Sodium Chloride; D013679:Technology, Radiologic / Q000295:instrumentation
chemical_list: D012965:Sodium Chloride; D007455:Iodine