來自印度的研究
利用高頻的線形探頭進行掃描
正確率達94%
大多的異物的回音性都會偏高些，
有些會合併有軟組織水腫或膿瘍，尤其是異物留存在軟組織一段時間後，
這時反而會更容易發現異物;
如果有合併空氣或產氣性感染時會不容易看到異物，這點要注意，
如果能夠看到Acoustic shadow，則異物存在的可能性就大增
Role of ultrasound in detection of radiolucent foreign bodies in extremities
Tantray MD1, Rather A2, Manaan Q3, Andleeb I3, Mohammad M3, Gull Y4.
Removal of foreign bodies from soft tissues in emergency is very challenging and becomes more problematic when it is radiolucent. Blind exploration is sometimes hazardous for patients especially when it is in proximity to a vessel or a nerve or an overlying tendon.
The purpose of this study was to determine the accuracy of ultrasonography (USG) in detecting radiolucent soft tissue foreign bodies in the extremities.
From January 2014 to January 2016, 120 patients with either a positive history or clinically suspected soft tissue foreign body and negative radiography were evaluated by USG with a high-frequency (13-6 MHz) linear-array transducer. The sonographic findings were used to guide surgical exploration.
Out of 120 patients who underwent surgical exploration, USG was positive in 114 cases, and foreign body was retrieved in 108 cases, and among the six cases where USG was negative, foreign body was retrieved from one case. In one case with strong clinical suspicion of foreign body USG was falsely negative. Majority of foreign bodies were removed from foot (69 cases) and hands (26 cases), and rest of foreign bodies were removed from ankle (4 cases), wrist (3 cases), thigh (2 cases), leg (1 case), knee (2 cases), forearm (2 cases).
Accuracy, sensitivity, and positive predictive value were determined as 94.16, 99.08, and 94.13%, respectively.
The real-time high-frequency USG is a highly sensitive and accurate tool for detecting and removing radiolucent foreign bodies which cannot be visualized by routine radiography.
Strategies Trauma Limb Reconstr. 2018 Feb 9. doi: 10.1007/s11751-018-0308-z.
[Epub ahead of print]
