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

Abstract

Diagnosis and treatment of foot disease in patients with diabetes is a common clinical-radiologic challenge, particularly the differentiation of neuropathic arthropathy from osteomyelitis. Conventional clinical tests and imaging techniques have limited accuracy for evaluation of the diabetic foot. The introduction of morphologic magnetic resonance (MR) imaging in these patients has provided a qualitative leap in diagnosis. The characteristics of soft-tissue and bone marrow edema and their patterns of distribution throughout the foot allow discrimination between both entities. However, in certain scenarios, the application of MR imaging to this problem is limited because of overlapping features between the two and the coexistence of infection and neuropathic changes. Recent technical advances in MR imaging sequences have increased the capability to add functional quantitative information to structural information. Diffusion-weighted imaging is useful to determine the presence and extension of osteomyelitis. Dynamic contrast-enhanced MR imaging may help to detect differences between the vascularization patterns of neuropathic arthropathy and osteomyelitis. MR angiography (with or without contrast material) is used in clinical practice to identify candidate distal vessels for revascularization. MR neurography, and especially diffusion-tensor imaging, provides quantitative information about neural damage. These new sequences may help in assessment of the different pathophysiologic conditions that occur in the diabetic foot. The physical basis of these techniques, their limitations, and their potential applications for diabetic foot assessment are detailed in this article. The introduction of advanced MR imaging multiparametric protocols, with the aim of enhancing the overall diagnostic accuracy of MR imaging, may help in treatment decision making and lead to improved patient outcomes. RSNA, 2017.

Guidelines on the diagnosis and treatment of foot infection in persons with diabetes (IWGDF 2019 update)

“…The presence of reactive bone marrow edema from non‐infectious pathologies, such as trauma, previous foot surgery or Charcot neuroarthropathy, lowers the specificity and positive predictive value . In selected patients with possible neuro‐osteoarthropathy, newer techniques such as MR angiography, dynamic contrast‐enhanced MRI or neurography may better distinguish Charcot from osteomyelitis . Newer advanced imaging tests, especially 18 F‐fluorodeoxyglucose (FDG)‐PET/CT and 99m Tc‐exametazime (HMPAO)‐labelled leukocyte scintigraphy, can be used in patients with a contraindication to MRI and appear to have a higher specificity than MRI (especially when noninfectious bony changes are more likely) but are limited in availability, require special expertise, and are more expensive .…”

Diabetic Foot Infections: The Diagnostic Challenges

“…In the last years, technical improvements have allowed the capability to add functional quantitative information to structural information. The application of Dixon sequences improves image quality and increases the detection of sinus tracts and intraosseus sequestrums [45]. Diffusion-weighted imaging and the apparent diffusion coefficient value can help in the differentiation of diabetic neuropathic osteoarthropathy from OM with excellent inter-observer agreement [45].…”

New trends in the orthopaedic management of diabetic foot

“…Today, when conventional clinical tests and imaging modalities such as radiography, ultrasonography and computed tomography (CT) fail to diagnose DFIs, advanced imaging techniques can be employed. 12 MRI is the most useful diagnostic imaging method for investigating DFIs. 12 , 13 However, in certain clinical conditions, particularly osteomyelitis and Charcot neuroarthropathy (CN), the use of MRI is limited because of the overlapping features of both conditions.…”

“… 12 MRI is the most useful diagnostic imaging method for investigating DFIs. 12 , 13 However, in certain clinical conditions, particularly osteomyelitis and Charcot neuroarthropathy (CN), the use of MRI is limited because of the overlapping features of both conditions. Therefore, new functional MRI modalities, including dixon imaging, diffusion-weighted imaging and dynamic contrast-enhanced MRI, have been of interest in distinguishing the two entities.…”

“…Nonetheless, these helpful techniques are not routinely used for diabetic foot assessment, and further studies are needed to verify their feasibility in discriminating between neuroarthropathy and osteomyelitis. 12 , 14 …”