Purpose: The purpose of this study was to estimate the severity of the participants' lower limb ischemia by calculating the lower limb muscle-to-background ratio (LMBR) using lower limb perfusion single-photon emission computed tomography-computed tomography (SPECT/CT) and to evaluate the prognostic value of LMBR in peripheral artery disease (PAD) patients.
Materials and methods: This retrospective study consists of 38 patients with PAD (70 ± 12 years) and observed over 1 year who were included in the analysis. All participants underwent lower limb perfusion SPECT/CT. LMBR was calculated by dividing counts/volume in lower limb muscle by mean counts/volume of background. All patients were divided into two groups based on their LMBR value and observed for the occurrence of a major adverse event (MAE).
Results: The high and low LMBR groups consisted of 26 and 12 patients, respectively. The median LMBR in the high group was 9.59 (6.11-11.87) while that in the low group was 4.35 (3.85-4.99). A significantly higher number of patients in the low LMBR group experienced MAE than in the high LMBR group (7 of 12 vs. 1 of 26, p < 0.001).
Conclusion: This study demonstrated that the LMBR derived from lower limb perfusion SPECT/CT may have a high prognostic value in patients with PAD.
Keywords: Lower limb muscle-to-blood ratio; Lower limb perfusion SPECT/CT; Peripheral artery disease; Prognosis; Risk factors.