Intravenous contrast‐free standardized exercise perfusion imaging in diabetic feet with ulcers

Abstract

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

Deteriorated regional calf microcirculation measured by contrast-free MRI in patients with diabetes mellitus and relation with physical activity

“…In a previous report, the SMBF and SMOEF measured in calf muscles agreed well with literature values measured by using PET approaches. 15 However, direct validation in animal models and humans is still needed.…”

“…9 Impaired perfusion in lower extremities has also been observed in patients with DM, with and without foot complications, by utilizing several image modalities. [10][11][12][13][14][15] Insufficient tissue perfusion may be a critical factor limiting muscle…”

“… 9 Impaired perfusion in lower extremities has also been observed in patients with DM, with and without foot complications, by utilizing several image modalities. 10 – 15 Insufficient tissue perfusion may be a critical factor limiting muscle hypertrophy and regeneration in response to exercise and injury stimulus and over all muscle performance.…”

Low frequency oscillations assessed by diffuse speckle contrast analysis for foot angiosome concept

“…This implies that the analysis of Pearson's correlation coefficient also does not fully support to the foot angiosome concept. To date, regarding the angiosome concept, some studies have focused on assessment of peripheral tissue perfusion to identify the origin location of diabetic foot ulcers with bench-top optical modalities [29][30][31][32][33][34] , to evaluate the quantitative wound healing with high-resolution imaging modalities such as CT 35,36 , SPECT/CT 37,38 and MRI perfusion [39][40][41] , and to evaluate leg revascularization surgeries Table 6. Comparison of ranks between six cross-correlations and six Pearson's correlation (CORR) coefficients at zero lag and in supine posture according to baseline and release periods from one subject's foot.…”

A split‐label design for simultaneous measurements of perfusion in distant slices by pulsed arterial spin labeling

“…1 Although the lack of sensitivity of the technique to low perfusion values and the need for an exercise challenge have limited its widespread use in muscle so far, ASL remains nonetheless particularly relevant to the study of microvascular reactivity in disorders such as peripheral arterial disease or diabetes. [2][3][4] In these disorders, the muscle's ability to timely match the oxygen and energy demand during physical activity is compromised, leading to severe complications. Circulatory abnormalities have also been hypothesized to play a role in certain inherited neuromuscular disorders like Duchenne and Becker muscular dystrophies and polymyositis.…”