Intravenous contrast-free standardized exercise perfusion imaging in diabetic feet with ulcers.
BACKGROUND
Impaired foot perfusion is a primary contributor to foot ulcer formation. There is no existing device nor method that can be used to measure local foot perfusion during standardized foot muscle exercise in an MRI environment.


PURPOSE
To develop a new MRI-compatible foot dynamometer and MRI methods to characterize local perfusion in diabetic feet with ulcers.


STUDY TYPE
Prospective.


POPULATION/SUBJECTS
Seven participants without diabetes and 10 participants with diabetic foot ulcers.


FIELD STRENGTH/SEQUENCE
3.0T, arterial spin labeling (ASL).


ASSESSMENTS
Using a new MRI-compatible foot dynamometer, all participants underwent MRI ASL perfusion assessment at rest and during a standardized toe-flexion exercise. The participants without diabetes were scanned twice to assess the reproducibility of perfusion measurements. The absolute perfusion and perfusion reserve values were compared between two groups and between regions near ulcers (peri-ulcer) and away from ulcers (away-ulcer).


STATISTICAL TESTS
Bland-Altman methods for the calculation of coefficient of repeatability (CR) and two-sided and unpaired Student's t-test to compare multiple differences.


RESULTS
The perfusion reserves measured had the best reproducibility (CR in medial region: 1.6, lateral region: 0.9). The foot perfusion reserve was significantly lower in the participants with diabetes compared with the participants without diabetes (1.34 ± 0.32, 95% confidence interval [CI]: 1.1, 1.58 vs. 1.76 ± 0.31, 95% CI: 1.53, 1.98, P = 0.02). Both peri-ulcer exercise perfusion (8.7 ± 3.9 ml/min/100g) and perfusion reserve (1.07 ± 0.39, 95% CI: 0.78, 1.35) were significantly lower than away-ulcer exercise perfusion (12.7 ± 3.8 ml/min/100g, P = 0.02) and perfusion reserve (1.39 ± 0.37, 95% CI: 1.11, 1.66, P = 0.03), respectively.


DATA CONCLUSION
This study demonstrates intravenous contrast-free methods for local perfusion in feet with ulcers by standardized exercise-based MRI. Ischemia regions around foot ulcers can be quantitatively distinguished from normal perfused muscle regions.


LEVEL OF EVIDENCE
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:474-480.
['Edalati|Masoud|M|', 'Hastings|Mary K|MK|', 'Muccigrosso|David|D|', 'Sorensen|Christopher J|CJ|', 'Hildebolt|Charles|C|', 'Zayed|Mohamed A|MA|', 'Mueller|Michael J|MJ|', 'Zheng|Jie|J|']
D000368:Aged D003287:Contrast Media D017719:Diabetic Foot D005080:Exercise Test D005260:Female D016523:Foot Ulcer D006801:Humans D007091:Image Processing, Computer-Assisted D007262:Infusions, Intravenous D018810:Magnetic Resonance Angiography D008297:Male D008875:Middle Aged D010477:Perfusion D055420:Perfusion Imaging D011446:Prospective Studies D015203:Reproducibility of Results D013113:Spin Labels
exercise perfusion foot ulcer diabetes mellitus magnetic resonance imaging