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Year : 2002  |  Volume : 12  |  Issue : 1  |  Page : 133-135
Radiological detection of unsuspected foreign bodies


Department of Radiodiagnosis, KMC Hospital, Allavar, Mangalore, India

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How to cite this article:
Mahale A R, Shetty R, Venugopal A, Kumar A. Radiological detection of unsuspected foreign bodies. Indian J Radiol Imaging 2002;12:133-5

How to cite this URL:
Mahale A R, Shetty R, Venugopal A, Kumar A. Radiological detection of unsuspected foreign bodies. Indian J Radiol Imaging [serial online] 2002 [cited 2019 Oct 22];12:133-5. Available from: http://www.ijri.org/text.asp?2002/12/1/133/28433
Sir,

A 35 year old man presented to our orthopaedics department with pain and swelling in the right forearm. There was no history of trauma. He was a carpenter by profession. Plain radiographs appeared normal. We advised an ultrasound of the right forearm. Ultrasound was done using a 7.5 MHZ probe (Toshiba SSH-140A machine). There was a linear echogenic focus running along the radial aspect of the right forearm measuring 2-3 mm in thickness and 3.0 cms in length. There was evidence of minimal hypoechoic area around it - suggestive of fluid collection / granulation tissue. Our diagnosis was that of a foreign body in the right forearm. The patient was operated and the foreign body removed and evaluated, it turned out to be a wooden splinter.

Another 40 year old male patient presented with a history of severe pain in the left forearm for the past 2 months with off and on episodes of pain for the past 20 years. The patient was a coconut tree climber by profession

and he was investigated with a plain radiograph. The radiograph of the left forearm revealed a lesion in the mid shaft of the left ulna extending along it interosseous margin with a central lucency surrounded by a radiopaque rim. The cortex appeared intact and there was no definite evidence of a periosteal reaction.

The patient was further investigated with a CT scan of left forearm (Somaton CR-Seimens). Axial sections revealed a rounded density (67HU) extending along the interosseous margin of the ulna shaft with a thick hyperdense area around it. Our diagnosis was that of a foreign body with granulation tissue around it.

The postoperative findings suggested a coconut palm twig which was unsuspectingly causing the symptoms.


   Discussion Top


The visibility of different materials on plain radiographs depends on their ability to absorb X-rays, and that of foreign bodies is dependant on their inherant radiodensity and relation between it and the tissue in which they are embedded. For instance the visibility of fish bones on radiographs varies greatly and is dependent on the species involved. [1]

On CT and plain radiographs radio opaque foreign bodies can be detected, since both systems are based on X-ray absorption. Particles without inherent radio opaqueness eg; wood could be seen as gas density on CT.

The density of wood on CT is, however, very dependent on whether the particle concerned in from fresh or dry wood. Dry wood becomes wet in soft tissues after some time and hence may be visualised better[2]

The best sensitivity and specificity results are achieved by ultrasound, which enables visualisation of the size and form of evenly shaped materials such as wood, amalgam, somposite and glass[2]. The "comet tail" an or "ring down" artifact is caused by reverberation of the ultrasound pulse within the foreign body (glass, crystalline material) because of high acoustic velocity of the material[3].

Evaluation of foreign bodies using ultrasound requires a higher frequency transducer. Foreign bodies appear hyperechoic on sonography. In a subacute and chronic setting a hypoechoic reaction develops around a hyperechoic foreign body and aids in detection.

The evaluation of soft tissue foreign bodies typically begins with routine radiographs. Radiolucent foreign bodies such as those composed of wood, however, may remain undetected. Ultrasound of MR Imaging can be used for wooden foreign body imaging, although MR imaging outperformed sonography when the foreign body was located near bone. Doppler can be used in the evaluation of relation of the foreign body to blood vessels[4].

MRI visualises soft tissue better than other method. The technique is based on the behaviour of protons in a magnetic field; hence, materials with water content are seen better than those without. There is also some difference whether T1 or T2 weighted or proton density images are used as wood is better visualised on T1 weighted images. MRI is superior to CT in the detection of small foreign bodies[5]. However materials with metallic content will cause artifacts and will be poorly delineated on MRI.

In conclusion we found that plain radiographs aided with US and CT were adequate for the evaluation of foreign bodies. MRI was not cost effective and hence not used in our department in foreign body evaluation.

 
   References Top

1.ELL SR, SPRIGGA. The radio-opacity of fishbones - species variation. Clin Radiol 1991; 44: 104-107.  Back to cited text no. 1    
2.Dikarinen KS, Nieminen TM, et al. Visibility of foreign bodies in soft tissue in plain radiographs, Computed tomography, Magnetic resonance imaging and ultrasound. Int J Oral Maxillofac Surg 1993;22:119-124.  Back to cited text no. 2    
3.SCANLAN KA. Sonographic artifacts and their origin. AJR 1991;156:1267-1272  Back to cited text no. 3  [PUBMED]  
4.Jacobson. Musculoskeletal Sonography and MR Imaging. RCNA July 1999;37(4):727-729.  Back to cited text no. 4    
5.Wehrli FW. Principles of magnetic resonance imaging. In; Stark DD, Dradley WG, eds.: Magnetic Resonance Imaging. St. Louis MO: Mosby, 1988:3-23.  Back to cited text no. 5    

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Correspondence Address:
A R Mahale
Department of Radiodiagnosis, KMC Hospital, Allavar, Mangalore
India
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Source of Support: None, Conflict of Interest: None


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