Routine MRI findings of the asymptomatic foot in diabetic patients with unilateral Charcot foot

Abstract

BackgroundImaging studies of bones in patients with sensory deficits are scarce.AimTo investigate bone MR images of the lower limb in diabetic patients with severe sensory polyneuropathy, and in control subjects without sensory deficits.MethodsRoutine T1 weighted and T2-fat-suppressed-STIR-sequences without contrast media were performed of the asymptomatic foot in 10 diabetic patients with polyneuropathy and unilateral inactive Charcot foot, and in 10 matched and 10 younger, non-obese unmatched control subjects. Simultaneously, a Gadolinium containing phantom was also assessed for reference. T1 weighted signal intensity (SI) was recorded at representative regions of interest at the peritendineal soft tissue, the tibia, the calcaneus, and at the phantom. Any abnormal skeletal morphology was also recorded.ResultsMean SI at the soft tissue, the calcaneus, and the tibia, respectively, was 105%, 105% and 84% of that at the phantom in the matched and unmatched control subjects, compared to 102% (soft tissue), 112% (calcaneus) and 64% (tibia) in the patients; differences of tibia vs. calcaneus or soft tissue were highly significant (p < 0.005). SI at the tibia was lower in the patients than in control subjects (p < 0.05). Occult traumatic skeletal lesions were found in 8 of the 10 asymptomatic diabetic feet (none in the control feet).ConclusionMR imaging did not reveal grossly abnormal bone marrow signalling in the limbs with severe sensory polyneuropathy, but occult sequelae of previous traumatic injuries.

Charcot foot syndrome

“…While it is often suggested that premorbid reduction in bone strength may contribute to the onset of the active Charcot foot, the evidence for its involvement is mixed. The possibility is suggested by a reduction in bone mineral density in the contralateral limb [37], but this finding has not been confirmed by all [38].…”

Advanced MR Imaging Techniques for Differentiation of Neuropathic Arthropathy and Osteomyelitis in the Diabetic Foot

“…The introduction of MR imaging for assessment of the diabetic foot has meant a qualitative leap and leaves behind several limitations of conventional imaging techniques. MR imaging is the imaging modality of choice for diabetic foot evaluation, with high sensitivity and high specificity (90% and 79%, respectively) in the diagnosis of osteomyelitis (4,14,16) (Table 1). In addition, MR imaging is able to depict bone marrow edema, which cannot be assessed with plain film radiography, CT, or US.…”

Bone–Fat Interaction

“…For example, T1DM patients with severe sensory polyneuropathy revealed a slight shift in T1 waves of routine MRI, indicative of marrow fat, in the tibia compared to matched controls. 41 However, the author’s noted that while this signaling shift was significant it was not overtly abnormal. 41 Somewhat consistent with this finding, Slade et al, 42 reported no differences in marrow adiposity from any site tested (e.g., vertebrae, femur epiphysis, femur metaphysis, and tibia metaphysis) between control and T1DM patients.…”

“…41 However, the author’s noted that while this signaling shift was significant it was not overtly abnormal. 41 Somewhat consistent with this finding, Slade et al, 42 reported no differences in marrow adiposity from any site tested (e.g., vertebrae, femur epiphysis, femur metaphysis, and tibia metaphysis) between control and T1DM patients. An unexpected and key finding to this study was that serum lipids (e.g., cholesterol, cholesterol/HDL ratio, LDL, and triglycerides) demonstrated a strong relationship with marrow adiposity, not duration of T1DM or HbA 1C .…”