This document discusses using inverted CT images to better visualize organic foreign bodies. It presents two case studies where inverted CT images clearly showed wooden foreign bodies that were difficult to see on conventional CT scans - a foreign body in the right orbit of a 5-year-old male and a foreign body in the floor of the mouth of a 2-year-old female. The document argues that spectral CT with inverted images can increase radiologist confidence by convincingly depicting these low-density organic structures, reducing the need for repeat imaging.

1. Inverted CT images in organic foreign bodies - is it more visually
convincing ?
Affiliation and Institution: North eastern Indira Gandhi Regional Institute of Health and Medical
Sciences, Shillong
Presenting Author: Donboklang Lynser
Co-authors: A. Handique, B Nongrum. Department of Radiology & Imaging, North-Eastern Indira Gandhi
Regional Institute of Health & Medical Sciences, Shillong, Meghalaya, India

2. • Organic foreign bodies are seen as low attenuation linear structures on CT images
• Imaging of wooden foreign bodies particularly orbital can be complex sometimes requiring MRI
when invisible on CT scan [1]
• We exploit the not often used “Spectral with inverted CT images” to visualize the organic foreign
bodies which to our knowledge has not yet been reported
• The first case is a foreign body in the right orbit and the other is an organic foreign body in the floor
of the mouth
• Our cases illustrated the use of Spectral with inverted CT images in convincingly showing these
structures which are normally difficult to visualize on CT

3. Case 1: 5 year male with wooden foreign body in the right orbit
Figure 1: Wooden foreign body (arrow) in the right orbit. A. Conventional CT images
showing a linear hypointense lesion of air attenuation. B. Inverted images showing the
foreign body. C. Iterative reconstructed, “Spectrum 10 steps with image inversion” in
128 slice Somatom Siemens AS + definitions, Germany make, machine showing the
foreign body
A B C

4. Case 2: 2 Y/F child with wooden foreign body in the right floor of the mouth
Figure 2: Wooden foreign body (arrow) in the right floor of the mouth. A. Conventional
CT images showing a linear hypointense lesion of air attenuation. B. Inverted images
showing the foreign body. C. Iterative reconstructed, “Spectrum 10 steps with image
inversion” in 128 slice Siemens machine showing the foreign body
A B C

5. • Our machine is Siemens 128 slice, Somatom AS+ Definitions,
Germany, with SAFIRE iterative reconstruction
• Spectral CT can increase the confidence of radiologist [2]
• Our spectral images with CT inversion techniques clearly and
convincingly depicts the organic foreign body
Discussion

6. 1. Li, J, Zhou, LP, Jin, J, et al. Clinical diagnosis and treatment of intraorbital wooden foreign bodies. Chin J
Traumatol 2016; 19(6): 322–325.
2. Andersen MB, Ebbesen D, Thygesen J, Kruis M, Rasmussen F. Impact of spectral body imaging in patients suspected for
occult cancer: a prospective study of 503 patients. Eur Radiol. 2020 Oct;30(10):5539-5550. doi: 10.1007/s00330-020-
06878-7. Epub 2020 May 4. PMID: 32367416; PMCID: PMC7476920.
• Visualising organic foreign bodies is utterly challenging in CT due to their
natively low density.
• Confident visualization of organic foreign body can be achieved in CT scan using
spectral with inverted CT images
• This can reduce the usual repeat imaging when such lesions are encountered.