骨化性肌炎之超音波影像

Sonographic Manifestation of Myositis Ossificans

我們利用10MHz解像力超音波針對7例骨化性肌炎個案進行影像診斷檢查，然後分析不同時期骨化性肌炎之超音波影像，並討論超音波對骨化性肌炎鑑別診斷上之價值。骨化性肌炎在超音波影像的特殊表現，依其時間先後可分為三期：第一期在腫脹的肌肉中呈現一境界不明顯的低回音區；第二期中心區仍為低回音，但是在病變較外圍部份開始有殼狀或點狀的高回音鈣化區形成，而其回音後陰影較不明顯，而且在高回鈣化區外的最外圍部份還有一層較薄的低回音區；第三期則呈現明顯的殼狀高回音帶並有強例的回音後陰影。超音波檢查可應用於骨化性肌炎與其他骨瘤、血腫、膿瘍以及血管栓塞病變之鑑別診斷，並且具有其他影像檢查所沒有的優點，包括安全、即時、快速、便宜、無游離輻射等，超音波檢查很適合骨化性肌炎的診斷及追蹤。

Myositis ossificans(MO)is a non-neoplastic heterotopic ossification in muscles and soft tissues. We examined seven patients with MO by means of 10-MHz ultrasonography. MO had a unique presentation on ultrasonography,which can be divided into three different stages. In the first stage,an ill-defined hypoechoic lesion can be seen in the swollen muscle. In the second stage, the central area remains hypoechoic, but some shelly or spotted hyperechoic calcification appears in the periphery, with a thin layer of hypoechoic rim. At this stage, the post-acoustic shadow is not so prominent. In the third stage, a prominent shelly hyperechoic rim with a strong post-acoustic shadow can be observed. Ultrasonography can differentiate MO from bone tumor, hematoma, abscess, or thromboembolic disease. Compared with other imaging techniques, it is safe, inexpensive, dynamic, and non-radioactive. Therefore, we believe that ultrasonography is a powerful tool in the diagnosis and follow-up of MO.