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PURPOSE:Changes in the microcirculation of the diabetic foot are important in the development and subsequent failure to heal existing. This study is to assess the dynamic enhanced process related to microcirculation of gangrene and high risk foot in diabetes usingmultiphase dynamic contrast enhanced MR imaging.
METHOD AND MATERIALS：Multiphase dynamic contrast enhanced MRI was performed on bilateral feet of 13 patients with unilateral diabetic foot (4 women, 9 men; mean age, 69 years; of them 2 cases with dry gangrene, 6 with humid gangrene, 3 with mixed gangrene and 2 with high risk foot). All the examinations were performed on a 1.5T MR scanner (Avanto). A 5mm-thick axial section through the middle of both naviculars was imaged using a T1-weighted 2D-FLASH sequence (2s per image). Following 5 baseline acquisitions, a bolus of Gd-DTPA (0.1mmol/kg, 4.0mL/s) was administered and then 245 image acquisitions were obtained. The percent MR signal enhancement of the ROI (mean area of 2.5cm2) in bilateral feet soft tissue was plotted and the signal intensity- time curve and parameters (arrive time, enhancement peak height and the changing rates in signal intensity at 10s and 30s) were calculated and analyzed.
RESULTS: The ratios of the values (arrive time, peak height, changing rates at 10s and 30s) of the affected foot to that of unaffected foot were described as follows: foot with humid gangrene, 0.97±0.08, 1.55±0.66, 1.77±0.78, 1.21±0.43; foot with mixed gangrene, 0.98±0.10, 1.23±0.37, 2.14±1.44, 1.54±0.59; foot with dry gangrene, 1.04±0.06, 0.74±0.02, 0. 62±0.07, 0.66±0.02; high risk foot, 0.96±0.06, 0.88±0.10, 0.85±0.11,0.79±0.08, respectively. In all types of diabetic foot, there was no significant difference on Arrive Time in bilateral feet. However, foot with humid and mixed gangrene showed increased peak height and the changing rates at 10s and 30s than those of the unaffected foot in the same patient, while foot with dry gangrene or high risk foot had the inverse results.
CONCLUSION: Multiphase contrast enhanced MR imaging provides a noninvasive means of quantifying perfusion-related changes of diabetic foot and should be potential on monitoring the therapy effects and estimating the prognosis of diabetic foot.
Those with humid or mixed gangrene trended higher perfusion than the unaffected foot, but the foot with dry gangrene or high-risk foot had lower perfusion than the unaffected foot in this preliminary study.
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