A Laboratory CT scanner with a resolution of (0.1 mm)3 wasused to determine if storage up to 7 days in saline at 4°C and (or) repeated measurementswould alter the compliance, C, and incremental elastic modulus, Einc,of isolated porcine aortas. All specimens were obtained fresh, made pressure-tight, and thenmounted in the scanner, with humidified air used to produce adequate x-ray contrast. Thespecimens were imaged at pressures of 4, 8, 12, 16, 20, and 24 kPa, and vessel measurementswere then obtained with a computerized technique and analyzed. Seven thoracic aortas werestudied on days 0, 3, 5, and 7, with a significant change (p < 0.05) in compliance firstoccurring after three imaging studies (i.e., day 5). Compliance of the fresh thoracic aortas (mean± SD) was 0.90 ± 0.28 mm/kPa at 14.4 kPa and 0.85 ± 0.31 mm/kPa at 22.5 kPa.Six thoracic aortas were studied only on days 0 and 6 with no intermediate measurements. Theyshowed no change in either compliance (0.88 ± 0.07 mm/kPa at 14.4 kPa and 0.64 ±0.09 mm/kPa at 22.5 kPa) or Einc (0.46 ± 0.05 MPa at14.4 kPa and 0.88 ± 0.15 MPa at 22.5 kPa) from day 0 to day 6. Thus, number ofmeasurements rather than time appears to be the important factor. Six abdominal aortas werestudied similarly but on days 0, 3, and 6. No significant change occurred in compliance (0.15 ±0.06 mm/kPa at 14.4 kPa and 0.032 ± 0.026 mm/kPa at 22.5 kPa) butEinc showed a change, possibly due to their viscoelastic properties. Weconclude that this nondestructive CT measurement method is suitable for repeated studies onporcine thoracic aortas, but not abdominal aortas, if the measurement involves two consecutiveimaging sessions separated by no more than 6 days.Key words: compliance, incremental elastic modulus, porcine aorta,x-ray computed tomography.
Shadow imaging studies on laser-ablated foil target by using an X-ray laser
