Time-of-flight quantitative measurements of blood flow in mouse hindlimbs.

Purpose: To evaluate the feasibility of using time-of-flight (TOF) imaging to directly measure hindlimb blood flow in a mouse model of peripheral vascular disease.

Materials And Methods: Four tubes were imaged simultaneously (diameters = 0.39 mm, 0.59 mm, and two at 1.46 mm) with a 1.0 mM copper sulfate solution for 19 flow velocities. In vivo measurements were performed in the hindlimbs of three mouse strains-C57BL/6 (N = 5), BALB/c (N = 5), and 129S2/Sv (N = 5)-three weeks after femoral artery ligation with a calibration standard.

Results: The flow phantom showed that the intensity was linear (r2 = 0.92) over the pertinent blood flow velocities in the mouse hindlimbs. Measurements of the blood flow in the distal hindlimbs in different strains of mice (combination of both the venous and arterial flows) were obtained 21 days after right-sided femoral artery occlusion. The results showed that under similar conditions of anesthesia and temperature, SV129 mice on the nonligated side had the highest flows (0.50 +/- 0.07 mL/minute), followed by C57BL/6 (0.28 +/- 0.04 mL/minute) and BALB/c (0.23 +/- 0.05 mL/minute), P < 0.02. The ligated side measurements (SV129, 0.31 +/- 0.05 mL/minute (P = 0.02); C57BL/6, 0.21 +/- 0.02 mL/minute (P = 0.13); and BALB/c, 0.12 +/- 0.02 mL/minute (P= 0.06)) showed a trend in BALB/c and C57BL/6 and significant differences in SV129 for incomplete recovery three weeks after surgery, compared to the nonligated side.

Conclusion: Two-dimensional TOF imaging permits quantitative in vivo measurements of hindlimb blood flow in a mouse model of peripheral vascular disease without the need of contrast injection, offering advantages of serial imaging not limited by tissue penetration.