MR imaging of the diabetic foot Mark E. Schweitzer, MD a, * , William B. Morrison, MD b a Department of Radiology, New York University Hospital for Joint Disease, 301 East 17th Street, New York, NY 10003, USA b Department of Radiology, Thomas Jefferson University Hospital, 111 South 11th Street, Suite G-3390, Philadelphia, PA 19107, USA Diabetes affects approximately 15 million persons in the United States alone [1]. In the foot and ankle, diabetes leads to vascular disease [2,3], arthritic dis- ease (typically neuropathic) [4,5], and an increased frequency of tendon disorders [6] and, perhaps most importantly, soft tissue and osseous infection [7,8]. Approximately one-fifth of diabetic patients warrant hospitalization for pedal infections [9]. Historically, amputation has been performed for severe diabetic pedal infection and ischemia. Diabetes is the most common reason for nontraumatic amputa- tions. Amputations in diabetic individuals are approx- imately 40 times higher than in nondiabetic persons [10]. Recent medical and surgical plans stressing the use of revascularization procedures (when appropri- ate) and local control of infection (including local wound care), appropriate antibiotics, and orthotics to alter weight bearing [11,12] often obviate the need for amputation. Currently, if an amputation is necessary, it is usually more limited, because imaging data allow precise mapping of the extent of infection [13,14]. The principles behind limited resection are to improve the patient’s quality of life [15] and to decrease the risk for contralateral amputation. With more residual bone, less energy is needed for ambu- lation [16], and, consequently, there is a less frequent occurrence of acute ulceration and infection of the opposite foot. Early intervention and accurate diag- nosis of the extent of infection have a significant effect on the quality of life [17]. Vascular disease in diabetic patients The negative effects of diabetes alter proximal [18] and distal lower extremity vessels [3,4]. Radiograph- ically, proximal arterial disease is usually seen as calcification of large vessels; angiographically, it appears as vessel narrowing [19]. Calcification of vessels distal to the Lisfranc joint in patients younger than 60 years is specific for diabetes. A conventional angiogram or MR angiogram can be performed to assess for stenoses treatable by focal angioplasty, stenting, or bypass grafts [20]. Although these procedures may improve flow to the distal vessels [21], there is a baseline decrease in distal vascular flow because of the effect of diabetes on distal arterioles and capillaries. This deficiency leads to ischemia and decreased vascular reserve in which the sequelae of minor trauma heal slowly and incom- pletely [22]. Neuropathy Diabetes mellitus has an effect on several compo- nents of the peripheral nervous system, leading to changes that accelerate ulcer formation and superin- fection [23]. Neuropathic arthropathy is the result of the interplay of sensory, motor, and autonomic neu- ropathy [24]. Motor neuropathy leads to atrophy of the intrinsic foot musculature and, to a lesser degree, the calf musculature, with resultant shifts in weight bearing. The sensory neuropathy leads to repetitive trauma without the patient being aware that injury is present, and consequent inadequate healing. This healing is further delayed by the underlying poor blood flow. 0033-8389/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved. doi:10.1016/S0033-8389(03)00163-5 * Corresponding author. E-mail address: mark.schweitzer@mail.tju.edu (M.E. Schweitzer). Radiol Clin N Am 42 (2004) 61 – 71