 DISCUSSION Initial evaluation of the diabetic foot is performed with the standard three-view radiographic series (dorsal-plantar, oblique, and lateral views) that may be supplemented with additional oblique views. Soft tissue swelling and edema may be the only signs of infection. Bone infection may be present, which is characterized by focal areas of osteopenia or overt erosions. If soft tissue gas is present, it is important to determine whether there has been recent debridement or other surgical intervention that could account for its presence. Soft tissue gas secondary to infection is often characterized by numerous small locules of gas that may be clustered together. CT is much more sensitive for soft tissue gas than radiographs, though CT is rarely obtained for the sole purpose of identifying soft tissue gas in the setting of diabetic foot infection. MRI is relatively insensitive to soft tissue gas, though large collections will appear as signal voids on T1- and T2-weighted sequences. With its excellent soft tissue contrast, MRI excels at identifying abnormalities of bone and deep soft tissue structures and may be used not just for diagnosis, but also for preoperative planning. MRI, however, is not very specific; reactive inflammation may appear identical to septic inflammation. Ultrasonography is an excellent modality for the identification of soft tissue gas, which appears as mobile tiny echogenic reflectors either tracking along a fascial plane (necrotizing fasciitis) or within a focal region of necrosis (gas gangrene). These reflectors can block the sound waves from penetrating beyond the gas, making assessment of the anatomy deep to the gas extremely difficult. Radionuclide bone scintigraphy is very sensitive, but quite nonspecific; its use is limited to those in whom MRI is contraindicated or if multifocal disease needs to be documented. Soft tissue gas secondary to infection is an indication for urgent debridement or amputation, depending on the extent of infection. Patients often require multiple debridements in order to establish aseptic healing tissue. This is followed by long-term intravenous antibiotic therapy. Notes： 1. dorsal-plantar 背跖位 2. osteopenia /ˌɒstɪəʊ'piːnɪə/ /ˌɒstɪəʊ'piːnɪə/ 骨质减少 3. overt erosion 明显的侵蚀、破坏 4. locule /'lɒkjuːl/ /ˈlɑkjul/ n. 小腔,小室 5. voids /vɔɪd/ /vɔɪd/ 流空信号影 6. gangrene /'gæŋgriːn/ /'ɡæŋɡrin/ n. 坏疽 7. scintigraphy /sɪn'tɪgrəfɪ/ /sɪn'tɪgrəfi/ n. 闪烁扫描法 8. amputation /ˌæmpjʊˈteɪʃən/ /ˌæmpjə'teʃən/ n. <医>截肢(术)；切断；切除 9. aseptic /eɪ'septɪk/ /ˌe'sɛptɪk/ adj. 无菌的；防腐性的 来源：每天朗读一段医学影像学英语文章 圈主 深圳市人民医院放射科副主任医师杨敏洁 |
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