The Diabetic Foot—Imaging Options and Considerations

Dakshin Gangadharamurthy, Perry Horwich, Robert L Greenman
US Endocrinology, 2007;(2):75-8
pdf icon download pdf Printer icon matthew [dot] goodwin [at] toucmedicalinformation [dot] com (subject: Reprint%20Request, amp, body: %20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20Dear%20Matthew%2C%0A%0AI%20would%20like%20to%20request%20a%20quote%20for%20.........%20reprints%20of%20the%20following%20article%3A%0A%0Ahttp%3A%2F%2Fwww.touchendocrinology.com%2F%2Farticles%2Fdiabetic-foot-imaging-options-and-considerations%0A%0APlease%20contact%20me%20on%20the%20following%20details.%0A%0A.........%0A%0AKind%20regards%2C%0A%0A.........%0A) (Order reprints)

Patients with diabetes may present with an array of foot disorders that include, but are not limited to, neuropathy, ulceration, and osteomyelitis. Ischemia and infection are common clinical concerns as either, or both, may be involved in the pathogenesis of these disorders. Management choices can be difficult to make and diagnostic imaging is often sought to help clarify the clinical picture. The imaging options available all have strengths and weaknesses in terms of their clinical relevance. A common problem encountered with imaging is distinguishing inflammation that is due to trauma—e.g. surgical, mechanical or Charcot arthropathy—from soft-tissue or osseous infection. This article reviews the most common imaging options available to clinicians and summarizes the benefits and drawbacks of each. No single imaging modality can answer all the clinical questions that arise in the setting of the diabetic foot, but knowing the features of the imaging choices available to you may help answer the most pressing questions.

Pathogenesis of Ischemia and Infection

While foot ulcers are the most common complication in the diabetic foot, infections rank a close second.1 Sensory neuropathy in the distal regions of the extremities predisposes many diabetics to traumatic insults that can lead to skin breakdown, ulceration, and infection. Impaired perfusion due to peripheral vascular disease and microvascular abnormalities reduces the patient’s capacity to heal wounds and recover from infection.2 In the diabetic foot, infected skin ulcers, the development of cellulitis, osteomyelitis, and abscess are major sources of morbidity.

The management of patients with diabetic foot disorders can vary substantially depending on the presence and extent of infection, necrosis, and osteomyelitis.3 Imaging of the diabetic foot may provide information that can aid the clinician in making patient management decisions. Diagnostic imaging procedures may also provide information that helps guide surgical planning.

Radiographs

This basic modality may be indicated when bone involvement is suspected. Radiographs can detect cortical fragmentation, osteomyelitis, fractures, arterial calcifications, and soft-tissue gas and articular deformities, including Charcot osteoarthropathy (see Figure 1).1,4 While radiography is often used initially, an early diagnosis of osteomyelitis may be difficult to make as changes on radiographs are often subtle, or absent, in the early stages of the disease process.5 Thus, this imaging modality is useful for detecting changes associated with the later stages of osseous infection (typically two or more weeks from onset) (see Figure 2).6 This limitation is partly responsible for the modality having low sensitivity in the detection of osteomyelitis. While studies show radiographs typically have a higher specificity than sensitivity, periosteal reaction and post-traumatic changes can be non-specific. For example, the appearance of Charcot osteoarthropathy can be mistakenly identified as osteomyelitis on radiographs.6

References:
  1. Frykberg RG, Zgonis T, Armstrong DG, et al., Diabetic foot disorders. A clinical practice guideline (2006 revision), J Foot Ankle Surg, 2006;45:S1–66.
  2. Zlatkin Z, Pathra M, Sartoris D, Resnick D, The Diabetic Foot, Radiol Clin North Am, 1987;25:1095–1105.
  3. Ledermann HP, Morrison WB, Schweitzer ME, Pedal abscesses in patients suspected of having pedal osteomyelitis: analysis with MR imaging, Radiology, 2002;224:649–55.
  4. Lipsky BA, Berendt AR, Embil J, De Lalla F, Diagnosing and treating diabetic foot infections, Diabetes Metab Res Rev, 2004;20(Suppl. 1):S56–64.
  5. Marcus CD, Ladam-Marcus VJ, Leone J, et al., MR imaging of osteomyelitis and neuropathic osteoarthropathy in the feet of diabetics, Radiographics, 1996;16:1337–48.
  6. Kapoor A, Page S, Lavalley M, et al., Magnetic resonance imaging for diagnosing foot osteomyelitis: a meta-analysis, Arch Intern Med, 2007;167:125–32.
  7. Palestro CJ, Torres MA, Radionuclide imaging in orthopaedic infections, Semin Nucl Med, 1997;27:334.
  8. Seabold JE, Flickinger FW, Kao SC, et al., Indium-111- leukocyte/technetium-99m-MDP bone and magnetic resonance imaging: difficulty of diagnosing osteomyelitis in patients with neuropathic osteoarthropathy, J Nucl Med, 1990;31:549–56.
  9. Elgazzar HA, Dayem AJC, Multimodality of osteomyelitis, Eur J Nucl Med, 1995;22:1043–63.
  10. Schauwecker DS, Park HM, Burt RW, Combined bone scintigraphy and In-111leucocytes scans in neuropathic foot disease, J Nucl Med, 1988;29:1651.
  11. Roca M, Martin-Comin J, Becker W, et al., A consensus protocol for white blood cells labelling with technetium-99m hexamethylpropylene amine oxime. International Society of Radiolabeled Blood Elements (ISORBE), Eur J Nucl Med, 1998;25: 797–9.
  12. Splittgerber GF, Spiegelhoff DR, Buggy BR, Combined leukocyte and bone imaging used to evaluate diabetic osteoarthropathy and osteomyelitis, Clin Nucl Med, 1989;14:156–60.
  13. Schauwecker DS, Diagnosis with In-lll-labeled leukocytes, Radiology, 1989;71:141–6.
  14. Datz FL, Anderson CA, Ahluwalia R, The efficacy of Indium 111polyclonal IgG for the detection of infection and inflammation, Semin Nucl Med, 1994;35:74.
  15. Rubin RH, Fischman AJ, The use of radiolabelled non-specific immunoglobulin in the detection of focal inflammation, Semin Nucl Med, 1994;24.
  16. Sella EJ, Grosser DM, Imaging modalities of the diabetic foot, Clin Podiatr Med Surg, 2003;20:729–40.
  17. Unal SN, Birinci H, Baktiroglu S, Cantez S, Comparison of Tc- 99m methylene diphosphonate, Tc-99m human immune globulin, and Tc-99m-labeled white blood cell scintigraphy in the diabetic foot, Clin Nucl Med, 2001;26:1016–21.
  18. Demirkol MO, Adalet I, Unal SN, et al., 99Tc(m)-polyclonal IgG scintigraphy in the detection of infected hip and knee prostheses, Nucl Med Commun, 1997;18:543–8.
  19. Palermo F, Boccaletto F, Paolin A, et al., Comparison of technetium-99m-MDP, technetium-99m-WBC and technetium- 99m-HIG in musculoskeletal inflammation, J Nucl Med, 1998;39:516–21.
  20. Oyen WJ, Netten PM, Lemmens JA, et al., Evaluation of infectious diabetic foot complications with indium-111-labeled human nonspecific immunoglobulin G, J Nucl Med, 1992;33: 1330–36.
  21. Bleeker-Rovers CP, de Kleijn EM, Corstens FH, et al., Clinical value of FDG PET in patients with fever of unknown origin and patients suspected of focal infection or inflammation, Eur J Nucl Med Mol Imaging, 2004;31:29–37.
  22. Keidar Z, Militianu D, Melamed E, et al., The diabetic foot: initial experience with 18F-FDG PET/CT, J Nucl Med, 2005;46:444–9.
  23. Zhuang H, Duarte PS, Pourdehnad M, et al., The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants, J Nucl Med, 2001;42:44–8.
  24. De Winter F, Vogelaers D, Gemmel F, Dierckx RA, Promising role of 18-F-fluoro-D-deoxyglucose positron emission tomography in clinical infectious diseases, Eur J Clin Microbiol Infect Dis, 2002;21:247–57.
  25. Larcos G, Brown ML, Sutton RT, Diagnosis of osteomyelitis of the foot in diabetic patients: value of 111In-leukocyte scintigraphy, Am J Roentgenol, 1991;157:527–31.
  26. Shults DW, Hunter GC, McIntyre KE, Parent FN, Value of radiographs and bone scans in determining the need for therapy in diabetic patients with foot ulcers, Am J Surg, 1989;158:525–30.
  27. Tomas MB, Patel M, Marwin SE, Palestro CJ, The diabetic foot, Br J Radiol, 2000;73:443–50.
  28. Morrison WB, Ledermann HP, Work-up of the diabetic foot, Radiol Clin North Am, 2002;40:1171–92.
  29. Thomsen HS, Nephrogenic systemic fibrosis: A serious late adverse reaction to gadodiamide, Eur Radiol, 2006;16:2619–21.
  30. Dyet JF, Nicholson AA, Ettles DF, Vascular imaging and intervention in peripheral arteries in the diabetic patient, Diabetes Metab Res Rev, 2000;16(Suppl. 1):S16–22.
  31. Kramer C, Budoff M, Fayad Z, et al., ACCF/AHA 2007 clinical competence statement on vascular imaging with computed tomography and magnetic resonance, Circulation, 2007;116: 1318–35.
  32. Gates J, Hartnell GG, Optimized diagnostic angiography in high-risk patients with severe peripheral vascular disease, Radiographics, 2000;20:121–33.
  33. Lapeyre M, Kobeiter H, Desgranges P, et al., Assessment of critical limb ischemia in patients with diabetes: comparison of MR angiography and digital subtraction angiography, Am J Roentgenol, 2005;185:1641–50.
  34. Kreitner KF, Kalden P, Neufang A, et al., Diabetes and peripheral arterial occlusive disease: prospective comparison of contrast-enhanced three-dimensional MR angiography with conventional digital subtraction angiography, Am J Roentgenol, 2000;174:171–9.
  35. Enderle MD, Coerper S, Schweizer HP, et al., Correlation of imaging techniques to histopathology in patients with diabetic foot syndrome and clinical suspicion of chronic osteomyelitis. The role of high-resolution ultrasound, Diabetes Care, 1999;22: 294–9.