Principles of Interpreting Imaging Studies (X-ray/CT/MRI)

2.7 - Principles of Interpreting Imaging Studies (X-ray/CT/MRI)

from Section 2 - Diagnosis, Assessment, Investigation, Monitoring and Data Interpretation

Published online by Cambridge University Press: 27 July 2023

Chun Wah So and

Edited by

Debashish Dutta and

Ned Gilbert-Kawai: Affiliation:
The Royal Liverpool Hospital
Debashish Dutta: Affiliation:
Princess Alexandra Hospital NHS Trust, Harlow
Carl Waldmann: Affiliation:
Royal Berkshire Hospital, Reading

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Summary

Key Learning Points

1. For X-rays, denser tissue (i.e. bone) absorbs more X-rays and therefore is whiter on the final image.
2. In CT imaging, different contrast media are used, depending on the clinical question. Normally oral/nasogastric contrast is given to detect intraluminal bowel pathology, and intravenous contrast is given to delineate the vasculature and lesions.
3. When looking at CT images, the process of windowing is used to optimally display the desired set of tissues. Sequential windows should be reviewed to assess the desired structures.
4. Magnetic resonance imaging works by utilising the magnetic properties of hydrogen ions (protons), which are found in high concentration in water and fat.
5. Different tissues can be characterised by different relaxation times – T1 and T2.

Keywords

radiograph X-ray computed tomography magnetic resonance imaging

Type: Chapter
Information: Intensive Care Medicine
The Essential Guide
, pp. 43 - 46

DOI: https://doi.org/10.1017/9781108989060 [Opens in a new window]

Publisher: Cambridge University Press

Print publication year: 2021

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References

References and Further Reading

Allisy-Roberts, P, Williams, J. Farr’s Physics for Medical Imaging, 2nd edn. Edinburgh: Elsevier; 2008.Google Scholar

Darby, MJ, Barron, D, Hyland, RE. Oxford Handbook for Medical Imaging. Oxford: Oxford University Press; 2011.Google Scholar

Public Health England. 2008. Patient dose information: guidance. www.gov.uk/government/publications/medical-radiation-patient-doses/patient-dose-information-guidance Google Scholar

Raby, N, Berman, L, de Lacey, G. Accident & Emergency Radiology: A Survival Guide, 2nd edn. Edinburgh: Elsevier; 2005.Google Scholar

Radiology Masterclass. 2008. Basics of X-ray physics. www.radiologymasterclass.co.uk/tutorials/physics/x-ray_physics_introduction Google Scholar