[Lower limb hemodynamic evaluation in patients with diabetic foot using 99mTc-methylene diphosphonate three-phase bone scintigraphy].

OBJECTIVE

To evaluate the efficacy of (99m)Tc-methylene diphosphonate (MDP) bone scintigraphy in diagnosis of diabetic foot.

METHODS

(99m)Tc-MDP three-phase bone imaging was performed in 56 patients with diabetic foot and 36 non-diabetic control subjects, each foot was analyzed independently. The radioactive concentration per pixel hence the foot to tibia ratio (R(m/t)) was calculated and the time-radioactivity curve of each region of interest generated. From the curve the perfusion time (Tp) was read and the velocity of uptake rate (V) of the foot calculated. The indices such as R(m/t), Tp and V were compared between the two groups by t test, and the diagnostic indices such as sensitivity, specificity, accuracy, positive prediction value and negative predictive value were compared using u test.

RESULTS

In the control group, the Tp, V and R(m/t) were 32.9+/-9.8 s, 2.301+/-0.754 counts/s and 0.85+/-0.29, respectively, which were 36.1+/-15.3 s, 1.574+/-0.341 counts/s and 0.72+/-0.31 respectively in the diabetic group. Tp was not significantly different (t=1.693, P>0.05) between the two groups, as was V (t=8.396, P<0.001) and R(m/t)(t=2.759, P<0.01). When V was used as the index, the sensitivity, specificity, and accuracy were 80.2%, 82.8% and 81.5%, respectively, and those for R(m/t) were 65.2%, 68.8% and 67.3%, respectively. By comparison, the sensitivity (u=2.3274, P<0.05) and specificity (u=2.4068, P<0.05) of V were significantly higher than those of R(m/t).

CONCLUSIONS

(99m)Tc-MDP three-phase bone imaging can identify decreased uptake rate and R(m/t) in the diabetic foot, and the former index can be more sensitive and specific to define the hemodynamics in the diabetic foot. This technique may detect hemodynamic abnormity in early stage and greatly assist the diagnoses and treatment.