kawamura5e_ppt27.pptx

Chapter 27 Foreign Bodies Tim S. Gibbs Objectives  Identify and give examples of different types of soft-tissue foreign bodies (STFBs) based on composition.  Explain sensitivity and specificity.  List the important information the sonographer should obtain from the patient interview and...

Chapter 27 Foreign Bodies Tim S. Gibbs Objectives  Identify and give examples of different types of soft-tissue foreign bodies (STFBs) based on composition.  Explain sensitivity and specificity.  List the important information the sonographer should obtain from the patient interview and patient chart prior to providing a comprehensive sonography evaluation.  Differentiate the different sonographic appearances of STFBs based on composition, location, age, and artifacts.  Describe the role of the sonographer prior to, during, and following sonography-guided foreign body (FB) removal.  Explain the limitations of sonography and the advantages of other imaging modalities used to image STFBs. 2 Copyright © 2023 Wolters Kluwer · All Rights Reserved Key Terms foreign bodies granuloma hypoechoic halo or rim inorganic organic sensitivity shadowing artifacts soft tissue specificity 3 Copyright © 2023 Wolters Kluwer · All Rights Reserved Glossary Term Definition granuloma a tumor-like mass formation that usually contains macrophages and fibroblasts and forms as a result of chronic inflammation and isolation of the infected area hyperemia an increase in the quantity of blood flow to a body part; increased blood flow as in the inflammatory response in vitro when referring to a biologic process, it is made to occur in a laboratory vessel or in a controlled experimental environment but does not occur within a living organism or in a natural setting in vivo when referring to a biologic process, it occurs or is made to occur within a living organism or natural setting occult in reference to foreign bodies (FBs), the term refers to something hidden from view radiolucent a tissue or material that allows transmission of X-rays and appears more dense (dark) on a radiograph; also known as nonradiopaque; for a FB, the material will often blend in and cannot be differentiated from the surrounding soft tissue radiopaque a tissue, contrast, or material that attenuates or blocks radiation; the tissue, contrast, or material will appear bright on the radiograph 4 Copyright © 2023 Wolters Kluwer · All Rights Reserved Introduction  Conventional radiography, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine, and sonography have been used to demonstrate the presence of foreign bodies (FBs).  Purpose of this chapter is to present the sonographic scanning technique to recognize, locate, and assist in the removal of various types of soft-tissue foreign bodies (STFBs) in superficial structures.  Increasing sonographer and clinician awareness and confidence to choose sonography for STFB detection, localization, and removal may result in increased diagnostic accuracy and decreased diagnostic expense. 5 Copyright © 2023 Wolters Kluwer · All Rights Reserved Outline #1 I. Composition of Foreign Bodies A. Sensitivity and Specificity B. Sonography Equipment C. Imaging Technology II. Evaluating the Composition, Location, Age, and Appearance A. Composition B. Location C. Age D. Appearance III. Sonography-Guided Foreign Body Removal IV. Limitation of Sonography V. Comparing Imaging Modalities 6 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #1 FBs can be separated into three distinct categories based on their composition o Organic material refers to biologic plant material and animal products o Inorganic materials are usually man-made products composed of minerals or made from minerals but are not animal or vegetable in origin o Metallic materials are those products with a metal alloy 7 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #2 8 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #3  Sensitivity and Specificity o Despite poor sensitivity, conventional radiography remains most commonly used imaging study for evaluation of FBs in emergency department. o Result: Many FBs missed on initial evaluation  Missed FBs are the second leading cause of malpractice lawsuits against emergency medicine physicians.  Wound care litigation constitutes 5% to 20% of lawsuit claims against emergency medicine physicians and results in 3% to 11% of monetary rewards. 9 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #4 Sensitivity and Specificity o Sonography performs well in demonstrating FBs traditionally considered most difficult to image on radiographic studies. o In retrospective studies where radiography failed to demonstrate an STFB, sonography had a sensitivity of 95% and a specificity of 89%. 10 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #5 Sensitivity and Specificity o In a prospective study using cadaver feet and wooden FBs, sonography revealed wooden FBs as small as 0.5 mm in length with 86.7% sensitivity and 96.7% specificity. o At the time of study, resolution of equipment either makes visualizing FBs smaller than 2.5 mm more difficult or limits adequate visualization. o Equipment today is capable of resolving objects within ±1 mm. 11 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #6  Sonography Equipment o Use a 7- to 12-MHz high-resolution, linear array transducer to obtain images. o Large footprint transducer is generally preferable for initial FB imaging and localization.  Small footprint transducer may be used when indicated. o Visualization of superficial FBs may be facilitated by use of a water bath. o To increase near-field length for better visualization of skin surface and to place a superficial FB in focal zone, use a standoff gel pad or thicker layer of scanning gel. 12 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #7 Figure 27-1 Water bath. A: The photograph demonstrates using a water bath to scan the finger. B: The sonogram demonstrates a hyperechoic foreign body that was a broken toothpick located in the finger. C: This represents the broken tip of a toothpick within a finger along with the original path while immersed in the water bath (Photo and image A and B: Courtesy and C permission of Robert Tillotson DO, RDMS, FACEP, FAAEM, Stevens Point, WI.) 13 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #8 Figure 27-2 Increasing the near field length can be achieved by using a standoff gel pad or thicker layer of scanning gel, which can help to demonstrate superficial foreign bodies. A: On a sonogram of the foot, the punctate, hyperechoic material was diagnosed as gravel. B: The transverse sonogram of the left plantar image demonstrates glass as hyperechoic echoes in this foot of a 1- year-old infant. C: The transducer-to-skin surface distance of a standoff gel pad is seen on this transverse image, which demonstrates the hyperechoic glass located in the right forehead. 14 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #9  Imaging Technology o New technology may not improve imaging FBs and may make detection more difficult. o Transmit beam-steering creates multiple imaging angles and combines microimages from different viewing angles into single compounded image.  Use of multiple imaging angles reduces shadowing.  Tissue harmonic imaging diminishes or eliminates shadowing completely. o Shadow and reverberation artifacts are important secondary signs in detecting FBs. o Only speckle reduction imaging (SRI) helps improve image quality over normal parameters. 15 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #10 Imaging Technology o Color and power Doppler may further increase sensitivity because normal inflammatory reaction materializes in a hypoechoic ring around FB as a result of hyperemic flow. o Color Doppler parameters should be set to visualize slow flow (low velocity) to help determine whether reactive hyperemia is present. o Varying transducer angle in relation to FB will assure best color-flow image will be obtained with highest Doppler shift. 16 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #11  Figure 27-3  A: Compare the edge shadowing (arrow) and resolution of the glass foreign body of the image on the left made with normal instrumentation and the sonogram on the right made with crossbeam instrumentation.  B: After removing the glass fragment, the foreign body is seen on the centimeter ruler. 17 Copyright © 2023 Wolters Kluwer · All Rights Reserved Composition of Foreign Bodies #12  Figure 27-4  A toothpick in the plantar surface of the foot is seen on these two images.  Compare the foreign body image without speckle reduction (WO SRI) to the image with speckle reduction (W SRI). 18 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #1 What category refers to foreign bodies composed of man-made products? A. Organic B. Inorganic C. Metallic D. Nonliving 19 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #2 What artifacts are helpful in identifying and locating foreign bodies? A. Range ambiguity and refraction B. Range ambiguity and motion C. Shadowing and reverberation D. Color Doppler saturation and aliasing 20 Copyright © 2023 Wolters Kluwer · All Rights Reserved Outline #2 I. Composition of Foreign Bodies A. Sensitivity and Specificity B. Sonography Equipment C. Imaging Technology II. Evaluating the Composition, Location, Age, and Appearance A. Composition B. Location C. Age D. Appearance III. Sonography-Guided Foreign Body Removal IV. Limitation of Sonography V. Comparing Imaging Modalities 21 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #1 Before beginning imaging examination, interview patient and review patient’s chart. Review radiographs if a radiographic procedure has already been performed. Information helpful before scanning includes o Ascertaining type of material o Mechanism of injury to include point of entry o Duration of symptoms 22 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #2  Composition o Organic FB  Radiography—Most difficult to locate and is rarely demonstrated  Sonography—Easier to locate and demonstrate  Echogenic pattern of organic FB varies with its indwelling age. o Inorganic FB  Radiography—Can be difficult to image using radiography  Sonography—Present little challenge for sonography 23 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #3 Composition o Metallic FB  Can be visualized on both radiography and sonography  Metal is radiopaque and relatively easily seen with radiography.  Most glass is radiopaque and relatively easily seen with radiography. 24 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #4 E  Figure 27-5  Metal and most types of glass are radiopaque foreign bodies that can be demonstrated and located on radiographs while others are invisible.  A metal sewing needle (arrows) can be seen in the lower leg on this (A) anterior to posterior projection and (B) the lateral projection of the tibia and fibula.  C: A glass foreign body is seen on a lateral projection of the plantar surface of the foot.  D: On a posterior to anterior projection of the hand, a glass foreign body is seen near the proximal end of the fifth metacarpal.  E: Ultrasound of a silicone fragment from broken fish tank injury. 25 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #5  Location o When locating an FB, radiographs provide further information regarding location, depth, and composition of FB. o Radiographs should be obtained in two perpendicular projections (imaging planes) in order to triangulate FB location. o FB will only be radiographically visualized if its density is greater than surrounding soft tissue. o Radiographs may assist in targeting location for initial insonation. o Especially helpful when external signs such as swelling or redness are not present. 26 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #6 Location o Working knowledge of normal soft-tissue structures can assist in separating normal structures from that of FB. o Documenting anatomic structures (arteries, veins, tendons, etc.) and relationship to FB helps physician to plan best approach for FB removal and to diminish postoperative complications. 27 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #7  Location o Smaller FB makes it more difficult to visualize. o Depth of FB will determine optimal transducer frequency. o Utilize highest frequency possible that allows adequate depth of penetration. o Make every attempt to visualize FB perpendicular to transducer to minimize potential errors in location and position within soft tissue. o When FB is visualized, mark location on overlying skin for physician to use during sonography-guided FB removal. 28 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Evaluating the Composition, Location, Age, and Appearance #8  Figure 27-6 A and B  Knowing soft-tissue structures and anatomic relationships is important to enable differentiating anatomy from a foreign body and to identify the foreign body location.  A: A transverse sonogram demonstrates three linear echogenic structures (arrows). The structures are three right carpal bones but were mistaken for foreign bodies.  B: A sonogram of the right hand shows the relationship of the foreign body (arrows) to an artery (A). 29 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #9 Figure 27-6 C and D C: Broken needle with the tip still within the vein. D: Glass fragment still present under the upper eye lid after copious irrigation. 30 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #10 Figure 27-7  This patient with 26-G hypodermic needles imbedded in her upper forearm presented a difficult challenge. A: Imaging perpendicular to the proximal forearm best demonstrated the needles (arrows). B: The superficial four needles were easily demonstrated and removed. C: The lateral view of the right elbows made with fluoroscopy during removal demonstrates six radiopaque needles that were not seen sonographically. 31 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #11 Age o Based on the duration of symptoms before imaging, FB may be described in one of three age categories  Acute  Intermediate  Chronic o Sonographic appearance of an STFB will correlate with the type and age of the retained material. 32 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #12 33 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #13 Age o In acute phase, FB will present as a bright echogenic structure with shadowing because of o Strong reflection of air in an organic FB o Material composition of an inorganic FB o Alloy in a metallic FB o Dirty shadowing, due to reflection caused by refracting properties of small gas bubbles and high impedance of a gas o Clean shadowing, which is caused by attenuating properties 34 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #14 Age o Potential pitfall usually occurs with a projectile FB when there is air within wound that can obscure visualization of FB. o Diminish or avoid by using multiple imaging angles after evaluating FB with perpendicular beam. o After 24 hours from beginning of acute phase, a hypoechoic ring develops around FB, representing an inflammatory reaction to FB. o Hypoechoic halo helps locate FB because it highlights its location. 35 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #15 Age o In intermediate phase with organic FB, air is slowly replaced with fluid. o Sound penetrates FB without shadowing artifact from air that was present in acute phase. o At this age point, inflammatory response to FB will appear with a more pronounced hypoechoic halo seen surrounding each type of FB. o Use hypoechoic ring to improve both sensitivity and specificity of sonography examination. 36 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #16  Age o Toward the end of intermediate phase, inflammatory response increases and hypoechoic halo surrounding FB becomes more pronounced. o Inflammatory response may demonstrate an increased vascular perfusion on color or power Doppler. o In chronic phase, appearance of organic FB is similar to acute phase in that air is replaced by fluid. o As chronic stage progresses, a dense granular material develops encapsulating all three types of FBs. 37 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #17 Age o Granular material development is body’s response to wall off foreign material. o Inflammatory response can result in a clean shadow similar to that of bone. o If granular material attenuates sound, FB in chronic stage may be easier to locate and demonstrate with sonography. o When located superficially, FB and associated granuloma may easily be palpated aiding in documenting its location. 38 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #18  Figure 27-8  Shadowing.  A: The linear echogenic foreign body is seen with distal acoustic shadowing.  B: The sonogram of an acute injury to the plantar surface demonstrates a linear echogenic toothpick (arrows) with distal shadowing.  C: The sonogram of a slanted echogenic foreign body (arrows) shows distal clean shadowing (AS). 39 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #19  Figure 27-9  Hypoechoic rim.  A: The transverse sonogram shows a large broken tooth fragment imbedded in the lower lip with surrounding exudation. There is acoustic shadowing distal to the linear echogenic tooth fragment (arrow).  B: On the same patient, a transverse sonogram shows multiple small tooth fragments, which appear echogenic and are located in the lower lip with a surrounding inflammatory process.  C: On this patient, a transverse sonogram shows the glass foreign body in the forehead with the early formation of a hypoechoic rim. 40 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #20 A B  Figure 27-10  A: This sonogram demonstrates a linear echogenic wood splinter in the finger with some distal acoustic shadowing. A hypoechoic halo (arrows) representing an inflammatory reaction to the foreign body is forming around the wooden foreign body.  B: Tip of a Spanish bayonet plant with hypoechoic halo. 41 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #21  Figure 27-11  A: Longitudinal sonogram of the finger shows a linear echogenic wood foreign body (arrows). The air normally seen in wood is replaced by fluid, which results in the loss of an acoustical shadow.  B: On this patient, the sonogram was made on a wooden splinter (arrows) in the late intermediate early chronic stage. The splinter loses the acoustic shadow as air due to fluid replacement.  C: The 2-cm splinter is seen after removal. 42 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #22  Figure 27-12  A: The transverse sonogram on the plantar surface shows the formation of a granuloma from a 3-month-old glass foreign body.  B: This transverse sonogram shows a 5.6-mm granuloma from a retained bee stinger. In this patient, the attenuation by the granular material creates a clean shadow distal to the granuloma and foreign body. 43 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #23 Appearance o Changing sonographic appearance of retained FBs can assist in their detection and can be used to draw attention to the actual FB itself. 44 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #24  Appearance o Most FBs are echogenic. o Artifacts created by FB may help identify location. o Comet tail artifacts can be seen with both metallic and glass FBs. o Clean or dirty posterior shadowing may also be seen with FB or fragments of varying thicknesses and shapes from FB. o Potential pitfall of relying on shadowing is air within soft tissue can mimic appearance of an FB. 45 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #25  Figure 27-13  This patient presented with a history of being injured with a wire.  A: The sonogram shows the wire (arrow) located 2-cm deep, posterior, and lateral to the calcaneus. Distal to the wire, the short arrows mark the comet tail artifact that is caused by closely spaced reverberation echoes.  B: The radiopaque wire can be seen on a lateral radiograph of the calcaneus.  C: The 1.5-cm wire is measured after its removal. 46 Copyright © 2023 Wolters Kluwer · All Rights Reserved Evaluating the Composition, Location, Age, and Appearance #26  Figure 27-14  A: The longitudinal sonogram of the right elbow demonstrates glass (arrow) embedded in soft tissue near air (arrowhead), which can mimic a foreign body.  B: The air (arrows) seen on this sonogram through soft tissue can mimic foreign bodies.  C: On this sonogram, one can see shadowing from the foreign body (small arrow) and from the air (large arrow), which was introduced with a lidocaine injection. 47 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #3 In which injury phase does an organic, inorganic of metallic foreign present as a bright echogenic structure with shadowing? A. Acute B. Intermediate C. Chronic D. Undetermined 48 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #4 In the intermediate phase, what is the value of evaluating the inflammatory response that presents as a more pronounced hypoechoic halo surrounding each type of foreign body? A. Documents decreased vascular perfusion B. Level of erosion of organic foreign bodies C. Improves the sensitivity and specificity of foreign body sonography examinations D. Level of encapsulating the foreign body with a granular substance 49 Copyright © 2023 Wolters Kluwer · All Rights Reserved Outline #3 I. Composition of Foreign Bodies A. Sensitivity and Specificity B. Sonography Equipment C. Imaging Technology II. Evaluating the Composition, Location, Age, and Appearance A. Composition B. Location C. Age D. Appearance III. Sonography-Guided Foreign Body Removal IV. Limitation of Sonography V. Comparing Imaging Modalities 50 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #1 Once located, depth, size, shape, and orientation or position of FB should be determined and sonographically documented. 3D localization should be made by scanning area of interest in both longitudinal and transverse orientations. o Pay attention to detecting an FB and imaging any associated posterior acoustic shadowing or reverberation echoes o Important to mark surface of skin with an indelible marker directly over FB 51 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #2 To facilitate correct surface location, insert a paperclip between patient and transducer to create a shadow on the FB. Transducer is then removed, and a mark is placed at skin surface. If FB is a small square or round BB-sized object, dot label is sufficient to mark its location. If FB is linear object like a needle or toothpick, mark both ends of FB and connect by dotted line. Surface marker provides physician with information regarding which direction to remove (pull out) FB. 52 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #3  Location and distance of FB from an acute entry wound can help physician determine feasibility of removing FB through original track or if a more direct approach is required.  Trauma to surrounding soft tissue is reduced whenever FB can be removed through original injury track. o Tract may need to be enlarged slightly to provide access for forceps.  Using sonographic guidance for FB removal can result in reducing size of incision with a less traumatic dissection to find and remove FB.  Sonographer may need small footprint sector transducer for direct imaging to guide forceps. 53 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #4  Figure 27-15 A and B  Documenting foreign body location.  A: The sonographer should annotate the image so the physician can see related anatomy and the angle of the foreign body in relationship to the skin surface.  B: The annotation should include the length of the foreign body. 54 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #5  Figure 27-15 C  C: The depth of the foreign body in the soft tissue and the skin surface marked. 55 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #6  Figure 27-16  During sonography- assisted removal, this sonogram shows the forceps (arrows) holding a glass fragment prior to removal. 56 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #7 When an open wound is present, physician needs to determine if FB may be removed through tract it entered. To determine best approach and minimize postoperative complications, tract’s angle and characteristics as well as surrounding structures and relationship to FB should be ascertained. To further assist in removal of small FBs, a needle or guide wire may be inserted with tip placed at FB. Provides a path of dissection through which FB may be removed 57 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #8  Figure 27-17  The sonogram shows the placement of the needle tip (arrow) adjacent to a glass fragment. 58 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #9 After anesthetizing region adjacent to extraction site, small forceps are used to dissect to FB’s location. Some physicians use hydraulic dissection before extracting FB to minimize tissue damage. 59 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #10 60 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #11  If site is old and original track has closed, determining FB position can result in smaller incision and decreased dissection for its removal. o Results in decreased risk of complications as well as a faster recovery period  Untreated or retained FBs can result in inflammation, infection, tendon or nerve injury, and allergic reaction.  Infection is the most common complication with nerve injury a distant second.  Patient who present with a history of recurrent localized infections should be asked about recent or remote trauma that may lead to search for retained FB. 61 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #12  Figure 27-18  The longitudinal sonograms show hypoechoic inflammation (arrows), surrounding the tendon. 62 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #13 Sonographic guidance results in o Reduced time for FB localization and removal o Smaller incisions o Less traumatic dissections Site should be reimaged after FB removal to evaluate if removal was a complete success. Postremoval sonography evaluation precaution will help prevent retained FBs, which can result in inflammation, infection, tissue injury, and allergic reaction. 63 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonography-Guided Foreign Body Removal #14 Figure 27-19 Removing glass from the forearm. A: After sonography-guided removal of three small glass shards, the rescanning of the area showed that foreign bodies (arrows) were still present. B: Seven more glass shards were eventually removed. 64 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #5 What is the most common complication patients acquire for untreated or retained foreign bodies? A. Nerve injury B. Nerve injury C. Infection D. Allergic reaction 65 Copyright © 2023 Wolters Kluwer · All Rights Reserved Outline #4 I. Composition of Foreign Bodies A. Sensitivity and Specificity B. Sonography Equipment C. Imaging Technology II. Evaluating the Composition, Location, Age, and Appearance A. Composition B. Location C. Age D. Appearance III. Sonography-Guided Foreign Body Removal IV. Limitation of Sonography V. Comparing Imaging Modalities 66 Copyright © 2023 Wolters Kluwer · All Rights Reserved Limitation of Sonography #1  Few limitations to sonography effectively localizing FBs do exist.  Major limitation is that examination relies on skill, knowledge, experience, and accuracy of sonographer.  While sonography has demonstrated superficial FBs less than 2 mm in size, sonography can be challenging for imaging objects that are smaller and/or not superficially located.  FBs may also be obscured by bony structures and air within the wound. o Varying imaging angles can decrease obscuration from bone. 67 Copyright © 2023 Wolters Kluwer · All Rights Reserved Limitation of Sonography #2 Imaging before wound exploration or irrigation may decrease introduction of air bubbles into field of view. Air within open cavity or removal site creates difficulty for sonographic imaging because it can mimic the appearance of FB or obscure FB. Air is introduced with injection of numbing anesthetic and can result in almost total obliteration of FB on sonography image. 68 Copyright © 2023 Wolters Kluwer · All Rights Reserved Limitation of Sonography #3  False-positive findings can occur as a result from calcifications, scar tissue, fresh hematoma, or air trapped in soft tissues.  Air within tract created by FB is seldom a problem for sonography if imaging is performed before any surgical intervention.  Small glass fragments can mimic the appearance of air when wound is still open. o Potential risk with open wound can be minimized with good understanding of normal anatomic structures. o Prior unsuccessful attempts at removing an FB can result in scar tissue that can distort the normal anatomic structures, making a definitive identification problematic. 69 Copyright © 2023 Wolters Kluwer · All Rights Reserved Limitation of Sonography #4  Figure 27-20  The sonogram on the left (A) shows a glass foreign body as a linear echogenic structure in the tissue with some distal attenuation. Following injection with lidocaine, the sonogram on the right (B) shows air bubbles interfering with visualizing the glass foreign body. Note the distal acoustic shadowing. 70 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #6 Which is one of the limitations of sonography examinations of foreign bodies? A. Foreign bodies between 3 and 4 mm cannot be visualized. B. Pitfalls associated with sonography far outweigh benefits. C. False-positive findings can result from air trapped in soft tissues. D. Varying imaging angles cannot decrease obscuration from bone. 71 Copyright © 2023 Wolters Kluwer · All Rights Reserved Outline I. Composition of Foreign Bodies A. Sensitivity and Specificity B. Sonography Equipment C. Imaging Technology II. Evaluating the Composition, Location, Age, and Appearance A. Composition B. Location C. Age D. Appearance III. Sonography-Guided Foreign Body Removal IV. Limitation of Sonography V. Comparing Imaging Modalities 72 Copyright © 2023 Wolters Kluwer · All Rights Reserved Comparing Imaging Modalities #1 Radiography o Capable of visualizing metal, glass, and stone in bone, muscle, and air o Limited to demonstrate graphite only in muscle o Most organic and inorganic FBs are radiolucent and cannot be visualized in bone, muscle, or air. 73 Copyright © 2023 Wolters Kluwer · All Rights Reserved Comparing Imaging Modalities #2 CT Image o Wood is poorly seen, difficult to image in muscle, but may be seen in the presence of air. o Detects metal, glass, stone, and graphite in bone and muscle o Greatest advantage over radiography or sonography is capable of demonstrating FBs in air. o More expensive imaging procedure, uses ionizing radiation, and may require sedation when used with pediatric patients 74 Copyright © 2023 Wolters Kluwer · All Rights Reserved Comparing Imaging Modalities #3 A B  Figure 27-21  Comparison of computed tomography (CT) and sonography demonstrating the same wood tree splinter in the neck of a professional tree trimmer.  A: CT scan of the splinter (arrow) located in the patients neck inferior to the right mandibular ramus.  B: Sonogram of the same splinter. 75 Copyright © 2023 Wolters Kluwer · All Rights Reserved Comparing Imaging Modalities #4 Sonography o Proven more effective and less expensive than CT imaging, eliminating problem of radiation exposure o Widespread availability and low cost of sonography make it best choice for determining presence of FB. o Major reason sonographic utilization does not increase may be related to lack of knowledge, experience, and confidence with sonographic findings prompting physicians to order other imaging procedures. 76 Copyright © 2023 Wolters Kluwer · All Rights Reserved Comparing Imaging Modalities #5 The American College of Emergency Physicians published guidelines recognizing FB detection and removal as a unique and evolving application of emergency sonography. Sonography should become main imaging tool used for detection and localization of STFBs because of o Sensitivity compared to lack of sensitivity of other imaging modalities o Noninvasive compared to ionizing radiation or magnet safety seen in other modalities o Provides a high-resolution, real-time evaluation 77 Copyright © 2023 Wolters Kluwer · All Rights Reserved Quiz #7 Which statement is accurate comparing different imaging modalities in the evaluation of foreign bodies? A. CT is excellent in imaging wood in muscle. B. MRI is safe and effective in early detection of all foreign bodies. C. Radiography is capable of visualizing graphite in bone and muscle. D. Sonography is best choice because of widespread availability, low cost, and determining the presence of foreign bodies. 78 Copyright © 2023 Wolters Kluwer · All Rights Reserved