Tuesday afternoon Columbus hall C papers 257–264. Clinical imaging: Soft-tissue neoplasms and infections
✍ Scribed by DL Burk; MB Zlatkin
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 514 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1053-1807
No coin nor oath required. For personal study only.
✦ Synopsis
High-speed MR imaging of F-19-labeled gases, administered via inhalation, was refined to assess regional cerebral blood flow (rCBF). This refinement has resulted in a twocompartment quantitative MR imaging assessment of rCBF. Ketamine/thiopental-anesthetized cats (n = 10) were intubated. paralyzed with Pavulon. and ventilated with 02:Nz:COz at a mixture ratio of 30:70:0 during normocapnia and 30:65:5 during hypercapnia. CBF-MR imaging was accomplished by substituting trifluoromethane (FC-23) for Nz under both normo-and hypercapnic conditions. FC-23 was administered in "pulses" of 3-minute duration, with each pulse separated by a 2-minute clearance interval. This pulsed input function (a total of 10 pulses) was used as a means to improve signal-to-noise ratio. Fast low-angle gradient refocused asymmetrical echo imaging (TR msec/ TE msec = 50/3) was used to image CBF (matrix = 16 X 16. FOV = 16 cm, section thickness = 2 cm). The imaging protocol consisted of the acquisition of 5,120 images obtained over a period of 70 minutes. Images were signal-averaged over blocks of 16 seconds (20 images), yielding a total of 256 images for rCBF estimates. The arterial input function of FC-23 was estimated by sampling the intubation tube ventilation gases with a doped semiconductor gas detector (Siemens]. High-resolution hydrogen-1 images were also acquired for localization and voxel registration. Mean singlecompartment normocapnic (pc02 = 39 torr f 3) and hypercapnic (pcoz = 61 torr f 5) rCBF was 55 mL/lOO g-min f 2 3 and 137 mL/100 g-min f 62, respectively. Sufficient signal-to-noise ratio in 8 of 10 animals permitted two compartment estimates. Mean normocapnic and hypercapnic fast-compartment flows for these animals were 147 mL/ 100 g-min f 29 and 227 mL/100 g-min f 53, respectively. A routine, atraumatic. nonradioactive quantitative imaging assessment of two-compartment flow in tissue volumes of 2 mL is described. This technique now appears ready for application in humans.