Foreign Body Radiography

Introduction

Radiography for suspected foreign body is a commonplace radiographic examination. This page considers all aspects of radiography for suspected foreign body.

Relevant Wiki Pages

Radiography for Ingested/Aspirated Foreign Bodies
Chest Radiography for Inhaled Foreign Body
Imaging Nail Gun Injuries
Lateral Soft Tissue Neck for Foreign Body

Mechanisms

accidental
intentional
iatrogenic.

Radiography

Radiographers will usually start with conventional orthogonal views- e.g. AP and lateral. The images are reviewed to assess the potential value of supplementary views. The following should be noted;
at least one joint should be included with longbone projections whenever possible
the foreign body may not be near the entry site- don't collimate the beam too tightly
centring the X-ray beam on the likely position of the foreign body will reduce parallax error
an entry site marker provides a useful guide to the position of the foreign body relative to the entry site
ensure that the entry site marker is not confused with the foreign body
it is possible for an entry site marker to obscure a small foreign body
a tangential view of the foreign body can be useful for demonstrating the depth of the foreign body below the skin
it can be useful to image the foreign body separately if the patient has provided an example of the same item
when using film/screen, a soft tissue exposure may be appropriate
where there are multiple possible entry sites, it may be useful to leave the entry site marker in place for the surgeon to see.

Self-adhesive Foreign Body Markers

A commercial foreign body entry site marker makes for a neat and practical solution for marking foreign body entry sites. The marker shown comes on a roll. The marker is peeled off the roll and stuck to the patient's skin at the entry site.
Foreign body entry site marker insitu.

Case 1

This patient presented to the Emergency Department after an incident in which a fragment of ferrous metal casting was suspected to have lodged in his upper arm. The patient (with admirable ingenuity) found a rare earth magnet and placed it against his skin where he thought the foreign body was sited. The magnet adhered to his arm.
When the magnet approached the patient's arm over the site of the suspected foreign body, the patient could feel the pull on the magnet under his skin.
When the magnet was pulled away from his arm, the skin tented with the magnetic attraction to the foreign body under his skin. The patient was referred for radiography of his upper arm to confirm the size and location of the foreign body.

Note the dried blood at the entry sire.
Conventional AP and lateral views of the humerus/elbow were obtained. The entry site was marked by placing an ink pen (biro) on the cassette that lined up with the entry site. This method has the advantage of being quick and easy to execute and the disadvantage of often only being achievable on one view (when the entry site is in contact with the cassette, it is not visible and therefore cannot be marked). An alternative method is to use a commercial adhesive disposable lead (pb) marker. This method has the advantage of providing an entry site identification which is visible on all views. It has the disadvantage of providing an opaque marker that can be confused with the foreign body(s). In addition, it may not always be practicable to adhere anything to the entry site. Entry site marking largely becomes a question of judgement; where the foreign body will be removed under image intensifier control, the entry site marker is somewhat redundant. Where the foreign body is known and will not be confused with the entry site marker (most cases) and the entry site is suitable for an adhesive commercial entry site marker, this is a good choice.

The imaging demonstrates a small metallic foreign body (arrow). An additional tangential view to show the depth of the foreign body was considered unnecessary given that tenting of the patient's skin when a magnet was applied.

There is benefit in centring the X-ray beam to the foreign body to avoid parallax error.
adapted from <a class="external" href="http://northphoenixagent.files.wordpress.com/2007/10/ink-pen.jpg" rel="nofollow" target="_blank">http://northphoenixagent.files.wordpress.com/2007/10/ink-pen.jpg</a>
The tip of an ink pen provides a handy entry point marker.

The practice of using an unfolded pair of paper clips to mark the entry site is arguably effective but aesthetically woeful.

Case 2

This patient presented to the Emergency Department with a broken sewing needle in her index finger. The needle was visible through the puncture hole in her nail. She was referred for radiography of her index finger.

Routine PA and lateral views were performed. These views do not establish whether the needle was partially lodged within the terminal tuft. The patient was re-referred for oblique views to establish whether the needle was within bone
The needle had passed though the patient's finger from dorsal to palmar (nail to pulp). Bearing this in mind, the radiographer was able to establish which way to oblique the finger in order to demonstrate the needle end-on. The resultant image (left) suggests the needle may have deflected along the radial aspect of the terminal tuft.

Comment
The pen was used to identify the finger of interest rather than the entry side. This may have been a point of confusion if the Radiologist thought that it was used to indicate the entry site.

The initial views were inadequate in that they did not establish whether the needle was lodged in bone.

Case 3

This 38 year old male was referred for radiography of his forearm as part of a workup for MR imaging. He had a history of a previous compound fracture of his left forearm associated with an industrial accident.

There is evidence of an old fracture of the distal third of the ulna. It is unclear if the adjacent opacities are foreign bodies of artifacts. The radiography was performed with a CR system. The lateral projection image similarly demonstrates an old healed fracture of the ulna and adjacent small dense opacities.

Whilst the dense opacities were likely to represent metallic foreign bodies, to be certain the radiographer repeated the lateral projection ensuring that a different CR cassette was used. A virtually identical demonstration of the small dense artifacts was achieved confirming the presence of foreign bodies which were likely to be metal fragments. The metallic foreign bodies were considered to represent contra-indications for 3 Tesla MR imaging.

Case 4

This 34 year old male presented to the Emergency Department with a laceration over the dorsum of his right foot. The laceration was caused by broken glass. He was referred for foot radiography to ensure that there was no foreign body in the wound prior to stitching.

The level of the entry site was marked with an radiopaque pen. Several small glass fragments were identified between the second and third metatarsals.
The small glass fragments were demonstrated to be relatively superficial on the lateral projection image.

? old foreign body beneath metatarso-phalangeal joint.
The referring doctor attempted to remove the foreign bodies based on the position on the foot X-ray images. This procedure was unsuccessful. The patient was re-referred for foot radiography with a request for more detailed localisation.

The radiographer performed collimated foot radiography with the laceration outlined by lead shot markers.
A tangential projection demonstrated the foreign bodies in relation to the laceration.

On second attempt, the foreign bodies were successfully removed.

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	This 34 year old male presented to the Emergency Department with a laceration over the dorsum of his right foot. The laceration was caused by broken glass. He was referred for foot radiography to ensure that there was no foreign body in the wound prior to stitching. The level of the entry site was marked with an radiopaque pen. Several small glass fragments were identified between the second and third metatarsals.
	The small glass fragments were demonstrated to be relatively superficial on the lateral projection image. ? old foreign body beneath metatarso-phalangeal joint.
	The referring doctor attempted to remove the foreign bodies based on the position on the foot X-ray images. This procedure was unsuccessful. The patient was re-referred for foot radiography with a request for more detailed localisation. The radiographer performed collimated foot radiography with the laceration outlined by lead shot markers.
	A tangential projection demonstrated the foreign bodies in relation to the laceration. On second attempt, the foreign bodies were successfully removed.

Foreign Body Radiography

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	A commercial foreign body entry site marker makes for a neat and practical solution for marking foreign body entry sites. The marker shown comes on a roll. The marker is peeled off the roll and stuck to the patient's skin at the entry site.
	Foreign body entry site marker insitu.

	This patient presented to the Emergency Department after an incident in which a fragment of ferrous metal casting was suspected to have lodged in his upper arm. The patient (with admirable ingenuity) found a rare earth magnet and placed it against his skin where he thought the foreign body was sited. The magnet adhered to his arm.
	When the magnet approached the patient's arm over the site of the suspected foreign body, the patient could feel the pull on the magnet under his skin.
	When the magnet was pulled away from his arm, the skin tented with the magnetic attraction to the foreign body under his skin. The patient was referred for radiography of his upper arm to confirm the size and location of the foreign body. Note the dried blood at the entry sire.
	Conventional AP and lateral views of the humerus/elbow were obtained. The entry site was marked by placing an ink pen (biro) on the cassette that lined up with the entry site. This method has the advantage of being quick and easy to execute and the disadvantage of often only being achievable on one view (when the entry site is in contact with the cassette, it is not visible and therefore cannot be marked). An alternative method is to use a commercial adhesive disposable lead (pb) marker. This method has the advantage of providing an entry site identification which is visible on all views. It has the disadvantage of providing an opaque marker that can be confused with the foreign body(s). In addition, it may not always be practicable to adhere anything to the entry site. Entry site marking largely becomes a question of judgement; where the foreign body will be removed under image intensifier control, the entry site marker is somewhat redundant. Where the foreign body is known and will not be confused with the entry site marker (most cases) and the entry site is suitable for an adhesive commercial entry site marker, this is a good choice. The imaging demonstrates a small metallic foreign body (arrow). An additional tangential view to show the depth of the foreign body was considered unnecessary given that tenting of the patient's skin when a magnet was applied. There is benefit in centring the X-ray beam to the foreign body to avoid parallax error.
adapted from <a class="external" href="http://northphoenixagent.files.wordpress.com/2007/10/ink-pen.jpg" rel="nofollow" target="_blank">http://northphoenixagent.files.wordpress.com/2007/10/ink-pen.jpg</a>	The tip of an ink pen provides a handy entry point marker. The practice of using an unfolded pair of paper clips to mark the entry site is arguably effective but aesthetically woeful.


This 38 year old male was referred for radiography of his forearm as part of a workup for MR imaging. He had a history of a previous compound fracture of his left forearm associated with an industrial accident. There is evidence of an old fracture of the distal third of the ulna. It is unclear if the adjacent opacities are foreign bodies of artifacts. The radiography was performed with a CR system.	The lateral projection image similarly demonstrates an old healed fracture of the ulna and adjacent small dense opacities. Whilst the dense opacities were likely to represent metallic foreign bodies, to be certain the radiographer repeated the lateral projection ensuring that a different CR cassette was used.	A virtually identical demonstration of the small dense artifacts was achieved confirming the presence of foreign bodies which were likely to be metal fragments. The metallic foreign bodies were considered to represent contra-indications for 3 Tesla MR imaging.