Vnitr Lek 2017, 63(4):236-241 | DOI: 10.36290/vnl.2017.050

Diabetic foot syndrome: importance of calf muscles MR spectroscopy in the assessment of limb ischemia and effect of revascularization

Andrea Němcová^1,*, Michal Dubský¹, Alexandra Jirkovská¹, Petr Šedivý², Miloslav Drobný², Milan Hájek², Monika Dezortová², Robert Bém¹, Vladimíra Fejfarová¹, Anna Pyšná¹

¹ Centrum diabetologie IKEM, Praha

² Oddělení výpočetní tomografie, magnetické rezonance a klinické a experimentální spektroskopie Pracoviště radiodiagnostiky a intervenční radiologie IKEM, Praha

Aim:
The standard method for assessment of effect of revascularization in patients with diabetic foot (DF) and critical limb ischemia (CLI) is transcutaneous oxygen pressure (TcPO₂). Phosphorus magnetic resonance spectroscopy (³¹P MRS) enables to evaluate oxidative muscle metabolism that could be impaired in patients with diabetes and its complications. The aim of our study was to compare MRS of calf muscle between patients with DF and CLI and healthy controls and to evaluate the contribution of MRS in the assessment of the effect of revascularization.

Methods:
Thirty-four diabetic patients with DF and CLI treated either by autologous cell therapy (ACT; 15 patients) or percutaneous transluminal angioplasty (PTA; 12 patients) in our foot clinic during 2013-2016 and 19 healthy controls were included into the study. TcPO₂ measurement was used as a standard method of non-invasive evaluation of limb ischemia. MRS examinations were performed using the whole-body 3T MR system 1 day before and 3 months after the procedure. Subjects were examined in a supine position with the coil fixed under the m. gastrocnemius. MRS parameters were obtained at rest and during the exercise period. Rest MRS parameters of oxidative muscle metabolism such as phosphocreatine (PCr), inorganic phosphate (Pi), phosphodiesters (PDE), adenosine triphosphate (ATP), dynamic MRS parameters such as recovery constant PCr (τPCr) and mitochondrial capacity (Q_max), and pH were compared between patients and healthy controls, and also before and 3 months after revascularization.

Results:
Patients with CLI had significantly lower PCr/Pi (p < 0.001), significantly higher Pi and pH (both p < 0.01), significantly lower Q_max and prolonged τPCr (both p < 0.001) in comparison with healthy controls. We observed a significant improvement in TcPO₂ at 3 months after revascularization (from 26.4 ± 11.7 to 39.7 ± 17.7 mm Hg, p < 0.005). However, the rest MRS parameters did not change significantly after revascularization. In individual cases we observed improvement of dynamic MRS parameters. There was no correlation between MRS parameters and TcPO₂ values.

Conclusion:
Results of our study show impaired oxidative metabolism of calf muscles in patients with CLI in comparison with healthy controls. We observed an improvement in dynamic MRS parameters in individual cases; this finding should be verified in a large number of patients during longer follow-up.

Keywords: autologous cell therapy; critical limb ischemia; diabetic foot; MR spectroscopy

Received: March 6, 2017; Accepted: March 29, 2017; Published: April 1, 2017  Show citation