Stone foreign body--radiographic and CT appearance

Detection of Intraorbital Foreign Bodies Using Magnetic Resonance Imaging and Computed Tomography

PURPOSE

We analyze the detectability of intraorbital foreign bodies (OrbFBs) of various types and sizes using computed tomography (CT) and magnetic resonance imaging using a three-Tesla machine (MRI 3 T).

METHODS

An ex vivo model of sheep eyes with preserved extraocular muscles and orbital fat tissue placed in the orbital cavity of the human skull was created for this study. Foreign bodies made of four different materials - plastic, bottle glass, stone and wood - each in three different sizes (large, intermediate and small) were inserted into the soft tissue of the orbit in the extraocular space. Each orbit was scanned by CT and MRI. Images were analyzed by a senior radiologist and underwent masked review by three oculoplastic surgeons.

RESULTS

Analysis of MRI and CT scans identified distinguishing characteristics for each of the four materials. This information was further integrated into a clinical algorithm. CT allowed easier identification of most of the embedded materials compared to MRI. Smaller OrbFB size was associated with lower detectability. Review of CT yielded 94.4% agreement between oculoplastic specialists in detecting OrbFbs using CT scans and allowed detection of most OrbFBs. In contrast, the overall agreement with MRI was lower: 66.7% with T1 MPRAGE, 50% with T1TSE, 88.9% with T2 TSE and 72.2% with T2 TSE FS. Plastic was the most difficult material to detect in all size categories.

CONCLUSIONS

CT offers a clear advantage over MRI for detecting and localizing nonmetallic OrbFBs of all sizes, except for plastic. Plastic OrbFBs can be detected with CT depending on size but are more visible in MRI scans.

Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges

Traumatic wounds and lacerations are a common reason for patients to present to emergency departments, with retained foreign bodies (FBs) accounting for 7%-15% of cases, particularly those involving the extremities. These retained materials result in a granulomatous tissue response known as an FB reaction, a pathologic attempt to isolate the FB from the host. The most common FB materials are glass, metal, and wood, but other compositions can also be found, such as plastic and animal-derived materials. Clinical history, physical examination, and wound exploration are essential in investigation of retained material but are not sufficient to exclude an FB, and additional investigation is required. Imaging evaluation is a useful tool to help depict and locate an FB, assess possible complications, and guide removal. Conventional radiography, the first-line method in this scenario, is a widely available low-cost depiction method that has good sensitivity for depicting FBs. If the retained material is not depicted at conventional radiography, US can be performed. US is highly sensitive in depicting both radiolucent and radiopaque FBs in superficial locations. For deeper objects, CT may be necessary. MRI is the best imaging modality to delineate local soft-tissue and osseous complications. Retained FBs can result in early and delayed complications, with infection being the most frequent complication. To avoid preventable morbidities related to FBs, radiologists should be familiar with imaging findings and provide essential information to help the attending physician treat each patient. Online supplemental material is available for this article. ^©RSNA, 2020.

Imaging foreign bodies in head and neck trauma: a pictorial review

Open injuries bear the risk of foreign body contamination. Commonly encountered materials include gravel debris, glass fragments, wooden splinters or metal particles. While foreign body incorporation is obvious in some injury patterns, other injuries may not display hints of being contaminated with foreign body materials. Foreign objects that have not been detected and removed bear the risk of leading to severe wound infections and chronic wound healing disorders. Besides these severe health issues, medicolegal consequences should be considered. While an accurate clinical examination is the first step for the detection of foreign body materials, choosing the appropriate radiological imaging is decisive for the detection or non-detection of the foreign material. Especially in cases of impaired wound healing over time, the existence of an undetected foreign object needs to be considered.

Here, we would like to give a practical radiological guide for the assessment of foreign objects in head and neck injuries by a special selection of patients with different injury patterns and various foreign body materials with regard to the present literature.

Visibility of different foreign bodies in the maxillofacial region using plain radiography, CT, MRI and ultrasonography: an in vitro study

OBJECTIVES

To compare the usefulness of four imaging modalities in visualizing various foreign bodies of different sizes.

METHODS

Foreign bodies of four sizes (0.5, 1, 2 and 3 mm) including metal, tooth, wood, plastic, stone, glass and graphite were embedded in six fresh sheep heads on bone surface between the corpus mandible and muscle, and inside the tongue muscle. A human dry skull served as an air-filled space. Plain radiography, CT, MRI and ultrasonography were used, and four skilled radiologists rated the findings individually.

RESULTS

All embedded foreign bodies except wood were best visualized using CT. Wood could only be detected using ultrasonography, and then only when fragments were >0.5 mm in size. Plain radiography and CT were almost equally accurate in visualizing metal and graphite. MRI was the least useful imaging technique.

CONCLUSIONS

In cases with suspected foreign bodies in the maxillofacial region, CT seems to be the optimal initial imaging study. Wood, however, could only be detected using ultrasonography.