Medical Imaging: Difference between revisions

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<div class="editorbox"> '''Original Editor '''- [[User:Rachael Lowe|Rachael Lowe]] '''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}</div>
== Overview  ==
== Overview  ==
[[File:Cardiac MRI flow.gif|alt=|thumb| Cardiac MRI flow ]]
<p align="justify">
Medical imaging refers to all diagnostic and therapeutic investigations/interventions conducted in a typical radiology department.  It encompasses different imaging modalities and processes to obtain images of the human body for diagnostic,  treatment and follow up purposes.
</p>
<p align="justify">
Imaging investigations have improved significantly over the years and play in important role in diagnostics. It also plays an important role in initiatives to improve public health through screening for certain conditions<ref name=":2">WHO [https://www.who.int/diagnostic_imaging/en/ Diagnostic Imaging] Available from: https://www.who.int/diagnostic_imaging/en/<nowiki/>(accessed 7.4.2021)</ref>. Imaging does however need to be utilised with caution and sound clinical reasoning in order to avoid the potential harms of medical imaging, such as radiation and iatrogenic pain.
</p>


Medical imaging is often perceived to designate the set of techniques that noninvasively produce images of the internal aspect of the body. It is the techniques and processes used to create images of the human body for clinical purposes such as seeking to reveal, diagnose or examine injury, dysfunction or pathology.
== Types of Imaging ==


As a discipline and in its widest sense incorporates radiology, tomography, endoscopy, thermography, medical photography and microscopy (e.g. for human pathological investigations).<br>  
* [[X-Rays|'''X-rays''']] (including plain radiographs, [[DEXA Scan|DEXA]] scans and fluoroscopy): Allows upright and dynamic imaging; assesses bony structures and can help to detect pulmonary pathology, abnormal growths, factures, oedema and deformities.
* [[MRI Scans|'''Magnetic resonance imaging''']] (MRI): Advanced imaging of soft tissue structure
* [[Ultrasound Scans|'''Ultrasound''']] (US)
* [[CT Scans|'''Computed tomography''']] (CT): More accurate assessment of bony structures
* '''[[Nuclear Medicine|Nuclear medicine]]:''' is the practice of utilising microscopic amounts of radioactive substances to diagnose, monitor and treat disease.<ref>Radiopedia Nuclear medicine Available:https://radiopaedia.org/articles/nuclear-medicine (accessed 8.10.20220</ref>
* '''PET''' (positron emission tomography) scan: an imaging test that involves the intravenous injection of a positron-emitting radiopharmaceutical, waiting to allow for systemic distribution, and then scanning for detection and quantification of patterns of radiopharmaceutical accumulation in the body. Used to diagnose a variety of diseases (for example tumours, heart disease, brain disorders). Provides a picture of the body working.<ref>Radiopedia PET Available: https://radiopaedia.org/articles/positron-emission-tomography<nowiki/>(accessed 8.10.2022)</ref>
* '''SPECT''' (Single photon emission computed tomography) similar to PET,  is a nuclear medicine imaging techniques which provide metabolic and functional information unlike CT and MRI.<ref>Radiopedia SPECT vs PET Available:https://radiopaedia.org/articles/spect-vs-pet (accessed 8.10.2022)</ref>


In the clinical context, medical imaging is generally equated to radiology and the medical practitioner responsible for interpreting (and sometimes acquiring) the images is a radiologist. The radiographer or radiologic technologist is usually responsible for acquiring medical images of diagnostic quality, although some radiological interventions are performed by radiologists.<br>
=== Hybrid Imaging ===
[[File:PET-MRI.jpeg|thumb|300x300px|PET-MRI]]
Hybrid Imaging is the fusion of two (or more) imaging modalities to form a new technique<ref>Radiopedia [https://radiopaedia.org/articles/modality?lang=us Modalities] Available from:https://radiopaedia.org/articles/modality?lang=us (accessed 7.4.2021)</ref>. By combining the innate advantages of the fused imaging technologies synergistically, usually a new and more powerful modality comes into being. Existing hybrid imaging modalities include: PET-CT, SPECT-CT, MRI-PET, MRI-SPECT


== Radiographic Imaging    ==
The general benefits of hybrid imaging include: Increased diagnostic accuracy, precise monitoring of interventional procedure and reduced radiation exposure, e.g. dynamic US after obtaining CT map.


Radiography is the use of ionizing electromagnetic radiation such as X-rays to view objects.&nbsp;This imaging modality utilizes a wide beam of x rays for image acquisition and is the first imaging technique available in modern medicine. Various forms of radiographic images are in use in medical imaging. <br>
=== Photoacoustic Imaging (PA) ===
[[File:PA.png|thumb|Schematic illustration of PA imaging]]
<p align="justify">
Also known as Optoacoustic Imaging, is an upcoming biomedical imaging modality availing the benefits of optical resolution and acoustic depth of penetration. Optoacoustic imaging has demonstrated promising potential in a wide range of preclinical and clinical applications.<ref name=":1">Amalina Binte Ebrahim Attia, Ghayathri Balasundaram, Mohesh Moothanchery, U.S. Dinish, Renzhe Bi, Vasilis Ntziachristos, Malini Olivo, A review of clinical photoacoustic imaging: Current and future trends,
Photoacoustics, Volume 16, 2019, 100144, ISSN 2213-5979, obtained from https://www.sciencedirect.com/science/article/pii/S2213597919300679 doi: 10.1016/j.pacs.2019.100144
</ref> Clinical applications of optoacoustic imaging include: Musculoskeletal Imaging; Gastrointestinal Imaging; Breast imaging; Dermatologic Imaging eg Skin cancer; Vascular Imaging; Carotid Vessel Imaging.<ref name=":1" />
</p><p align="justify">
Studies have showed the potential use of optoacoustic imaging in the assessment, diagnosis and monitoring of treatment in patients with inflammatory arthritis<ref>Jo J, Tian C, Xu G, et al. Photoacoustic tomography for human musculoskeletal imaging and inflammatory arthritis detection. ''Photoacoustics''. 2018;12:82–89. Published 2018 Jul 27 obtained from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306364/ doi:10.1016/j.pacs.2018.07.004
</ref> as well as limb and muscle ischemia.<ref>Chen L, Ma H, Liu H, et al. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446508/ Quantitative photoacoustic imaging for early detection of muscle ischemia injury]. ''Am J Transl Res''. 2017;9(5):2255–2265. Published 2017 May 15 obtained from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446508/</ref>
</p>
== Necessity of Medical Imaging ==
[[File:CT spinal cord.jpg|alt=|thumb|CT spinal cord]]Medical imaging is crucial in a variety of medical setting and at all major levels of health care. In public health and preventive medicine as well as in both curative and palliative care, effective decisions depend on correct diagnoses. Though clinical reasoning may be sufficient prior to treatment of many conditions, the use of diagnostic imaging services is paramount in confirming, correctly assessing and documenting courses of many diseases as well as in assessing responses to treatment.
== Caution with Imaging ==
Imaging is a useful resource for many conditions and is an invaluable tool for clinicians/physiotherapists when used appropriately. It is important to know when imaging is appropriate, as unnecessary imaging will squander financial resources and increase the potential for premature surgery/ iatrogenic effects.


==== Fluoroscopy  ====
Early or unnecessary referral for imaging may be influenced by patient expectations and clinician concerns, or may be used as way to reassure patients. These factors need to be managed with good communication and evidence based guidelines.<ref name=":0" />


Fluoroscopy produces real-time images of internal structures of the body in a similar fashion to radiography, but employs a constant input of x-rays, at a lower dose rate to provide moving projection radiographs of lower quality. Contrast media, such as barium, iodine, and air are used to visualize internal organs as they work. Fluoroscopy is mainly performed to view movement (of tissue or a contrast agent), or to guide a medical intervention, such as angioplasty, pacemaker insertion, or joint repair/replacement.&nbsp; Fluoroscopy is also used in image-guided procedures when constant feedback during a procedure is required such as intraoperative and catheter guidance. <br>
Also see: [[Diagnostic Imaging: Best Practice|Diagnostic Imaging Best Practice]]


'''Angiography''' is the use of fluoroscopy to view the cardiovascular system. An iodine-based contrast is injected into the bloodstream and watched as it travels around. Since liquid blood and the vessels are not very dense, a contrast with high density (like the large iodine atoms) is used to view the vessels under X-ray. Angiography is used to find aneurysms, leaks, blockages (thromboses), new vessel growth, and placement of catheters and stents. Balloon angioplasty is often done with angiography.  
=== Iatrogenic Effects ===
Abnormal radiologic findings of the musculoskeletal system can be very common. Not all abnormalities are relevant to a patient's complaint and over-emphasising radiologic findings can have harmful effects.


Fluoroscopy can be used to examine the digestive system using a substance which is opaque to X-rays, (usually barium sulfate or gastrografin), which is introduced into the digestive system either by swallowing or as an enema. This is normally as part of a double contrast technique, using positive and negative contrast. Barium sulfate coats the walls of the digestive tract (positive contrast), which allows the shape of the digestive tract to be outlined as white or clear on an X-ray. Air may then be introduced (negative contrast), which looks black on the film. <br>  
* '''Routine MRI''' reports produce worse functional outcomes compared to a 'clinical report' (which includes reassurance of incidental findings) in patients with low back pain.<ref>Rajasekaran S, Dilip Chand Raja S, Pushpa BT, Ananda KB, Ajoy Prasad S, Rishi MK. The catastrophization effects of an MRI report on the patient and surgeon and the benefits of ‘clinical reporting’: results from an RCT and blinded trials. European Spine Journal. 2021 Jul;30:2069-81.</ref>
* '''Early-MRI''' in acute low back pain results in longer length of disability, higher medical cost and worse outcomes regardless of radiculopathy (even after controlling for severity and demographics)<ref name=":0">Webster BS, Bauer AZ, Choi Y, Cifuentes M, Pransky GS. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4235393/ Iatrogenic consequences of early magnetic resonance imaging in acute, work-related, disabling low back pain.] Spine. 2013 Oct 15;38(22):1939-46.</ref>


==== Projectional Radiography  ====
It is therefore very important to carefully consider whether imaging is indicated, and to always view the results in the context of an in depth history and physical examination. This will help to discern whether findings correlate with the patient's complaint, or are in fact incidental and negligible.


[[X-Rays|Projectional Radiography]], more commonly known as x-rays, are often used to determine the type and extent of a fracture as well as for detecting pathological changes in the lungs. With the use of radio-opaque contrast media, such as barium, they can also be used to visualize the structure of the stomach and intestines
=== Radiation ===
Even though most imaging techniques use low doses of radiation, large, repeated doses have a cumulative effect and can be harmful to human health (including cancer and tissue damage). '''"Image gently"''' and '''"Image wisely"''' are initiatives that promote practices that reduce radiation exposure by eliminating unnecessary procedures (see resource section).<ref>Ford B, Dore M, Moullet P. [https://www.aafp.org/pubs/afp/issues/2021/0101/p42.pdf Diagnostic imaging: appropriate and safe use.] American Family Physician. 2021 Jan 1;103(1):42-50.</ref>Modern techniques have also resulted in reductions in radiation exposure during imaging.


==== Dual energy X-ray absorptiometry  ====
Factors that should be considered include a patient's age and lifetime exposure to radiation, as well as whether the benefit of the diagnostic test outweighs the risk. CT-scans have higher radiation risk than x-rays, whereas no ionising radiation is produced during MRI or ultrasound scans.<ref name=":3">Mafraji, M.A. Risk of Radiation in Medical Imaging [Internet]. Merck Manuals. 2023 [updated 2023 November; cited 2024 March]. Available from: https://www.msdmanuals.com/home/special-subjects/common-imaging-tests/computed-tomography-ct  </ref>


Dual energy X-ray absorptiometry (or DEXA, or bone densitometry) is used primarily for osteoporosis tests. It is not projection radiography, as the X-rays are emitted in 2 narrow beams that are scanned across the patient, 90 degrees from each other. Usually the hip (head of the femur), lower back (lumbar spine) or heel (calcaneum) are imaged, and the bone density (amount of calcium) is determined and given a number (a T-score). It is not used for bone imaging, as the image quality is not good enough to make an accurate diagnostic image for fractures, inflammation etc. It can also be used to measure total body fat, though this isn't common. The radiation dose received from DEXA scans is very low, much lower than projection radiography examinations.
Radiation risk is of particular concern in the following scenarios:<ref name=":3" />:


==== Computed Tomography (CT)   ====
* During infancy and early childhood
* During pregnancy (especially early)


[[CT Scans|Computed Tomography (CT)]] or CT scan (previously known as CAT scan, the "A" standing for "axial") uses a high amount of ionizing radiation (in the form of X-rays) in conjunction with a computer to create images of both soft and hard tissues.&nbsp; It is a helical tomography which traditionally produces a 2D image of the structures in a thin section of the body.&nbsp; These images look as though the patient was sliced like bread (thus, "tomography"-- "tomo" means "slice").&nbsp; It has a greater ionizing radiation dose burden than projection radiography; repeated scans must be limited to avoid health effects.&nbsp;&nbsp;&nbsp; Contrast agents are often used, depending on the tissues needing to be seen.<br>  
=== Asymptomatic Findings ===
<p align="justify">Although advanced imaging is generally very sensitive, it can be very non-specific. Various studies have found that imaging findings and symptoms often do not correlate. Consider the table below - these findings provide evidence that what we regard as pathology may not be that significant. Also see the pages on imaging of specific body regions for more detail:</p>


== Magnetic resonance imaging (MRI)  ==
* [[Diagnostic Imaging of the Foot and Ankle for Physical Therapists|Foot and Ankle]]
* [[Diagnostic Imaging of the Knee for Physical Therapists|Knee]]
* [[Diagnostic Imaging of the Hip for Physical Therapists|Hip]]
* [[Common Diagnostic Imaging of the Lumbar Spine|Lumbar spine]]
* [[Diagnostic Imaging of the Shoulder|Shoulder]]


[[MRI Scans|Magnetic resonance imaging]] employs a scanner that uses powerful magnets to polarise and excite hydrogen nuclei (single proton) in water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body. MRI uses three electromagnetic fields: a very strong (on the order of units of teslas) static magnetic field to polarize the hydrogen nuclei, called the static field; a weaker time-varying (on the order of 1 kHz) field(s) for spatial encoding, called the gradient field(s); and a weak radio-frequency (RF) field for manipulation of the hydrogen nuclei to produce measurable signals, collected through an RF antenna.  
{| class="wikitable"
|+Pathologies in asymptomatic subjects
!'''Pathology'''
!'''Prevalence among asymptomatic population'''
|-
|Lumbar disc herniation and/or spinal stenosis
|20- 75%
|-
|Cervical disc bulging
|75 - 90%<ref>Nakashima H, Yukawa Y, Suda K, Yamagata M, Ueta T, Kato F. Abnormal findings on magnetic resonance images of the cervical spines in 1211 asymptomatic subjects. Spine. 2015 Mar 15;40(6):392-8.</ref>
|-
|Cervical spinal cord compression
|7 - 35% <ref>Smith SS, Stewart ME, Davies BM, Kotter MR. The prevalence of asymptomatic and symptomatic spinal cord compression on magnetic resonance imaging: a systematic review and meta-analysis. Global spine journal. 2021 May;11(4):597-607.</ref>
|-
|Rotator cuff tendinopathy
|25 - 89% <ref name=":4">Girish G, Lobo LG, Jacobson JA, Morag Y, Miller B, Jamadar DA. Ultrasound of the shoulder: asymptomatic findings in men. American Journal of Roentgenology. 2011 Oct;197(4):W713-9.</ref>
|-
|Mild glenohumeral or acromioclavicular OA 12
|50 - 70%<ref name=":4" />
|-
|Hip labrum tear 13/14
|54% <ref>Heerey, J.J., Kemp, J.L., Mosler, A.B., Jones, D.M., Pizzari, T., Souza, R.B. and Crossley, K.M., 2018. What is the prevalence of imaging-defined intra-articular hip pathologies in people with and without pain? A systematic review and meta-analysis. ''British Journal of Sports Medicine'', ''52''(9), pp.581-593.</ref>
|-
|Knee Meniscal abnormalities and OA 19
|60% <ref>Englund M, Guermazi A, Gale D, Hunter DJ, Aliabadi P, Clancy M, Felson DT. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. New England Journal of Medicine. 2008 Sep 11;359(11):1108-15.</ref>
|}


Like CT, MRI traditionally creates a two dimensional image of a thin "slice" of the body and is therefore considered a tomographic imaging technique. Modern MRI instruments are capable of producing images in the form of 3D blocks, which may be considered a generalisation of the single-slice, tomographic, concept. Unlike CT, MRI does not involve the use of ionizing radiation and is therefore not associated with the same health hazards. For example, because MRI has only been in use since the early 1980s, there are no known long-term effects of exposure to strong static fields and therefore there is no limit to the number of scans to which an individual can be subjected, in contrast with X-ray and CT. However, there are well-identified health risks associated with tissue heating from exposure to the RF field and the presence of implanted devices in the body, such as pace makers. These risks are strictly controlled as part of the design of the instrument and the scanning protocols used.  
== Health Care Team ==
Imaging for medical purposes involves a team which includes the service of radiologists, radiographers (x-ray technologists), sonographers (ultrasound technologists), medical physicists, nurses, biomedical engineers, and other support staff working together. Appropriate use of medical imaging requires a multidisciplinary approach.<ref name=":2" />


Because CT and MRI are sensitive to different tissue properties, the appearance of the images obtained with the two techniques differ markedly. In CT, X-rays must be blocked by some form of dense tissue to create an image, so the image quality when looking at soft tissues will be poor. In MRI, while any nucleus with a net nuclear spin can be used, the proton of the hydrogen atom remains the most widely used, especially in the clinical setting, because it is so ubiquitous and returns a large signal. This nucleus, present in water molecules, allows the excellent soft-tissue contrast achievable with MRI.
== Conclusion ==
 
Medical imaging is a crucial component of healthcare and provide a valuable tool for diagnosis, screening and treatment. It is however important to follow [[Diagnostic Imaging: Best Practice|best practice guidelines]] with a particular focus on avoiding unnecessary imaging and ensuring appropriate, evidence-based interpretation of results. '''We treat whole, complex persons - not images and scans.'''
== Ultrasound Imaging  ==
 
[[Ultrasound Scans|Ultrasound]] uses high frequency broadband sound waves in the megahertz range that are reflected by tissue to varying degrees to produce (up to 3D) images. This is commonly associated with imaging the fetus in pregnant women. Uses of ultrasound are much broader, however. Other important uses include imaging the abdominal organs, heart, breast, muscles, tendons, arteries and veins.
 
While it may provide less anatomical detail than techniques such as CT or MRI, it has several advantages which make it ideal in numerous situations, in particular that it studies the function of moving structures in real-time, emits no ionizing radiation, and contains speckle that can be used in elastography. It is very safe to use and does not appear to cause any adverse effects, although information on this is not well documented. It is also relatively inexpensive and quick to perform. Ultrasound scanners can be taken to critically ill patients in intensive care units, avoiding the danger caused while moving the patient to the radiology department. The real time moving image obtained can be used to guide drainage and biopsy procedures. Doppler capabilities on modern scanners allow the blood flow in arteries and veins to be assessed.
 
== Electron microscopy  ==
 
The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons as the source of illumination, magnifying at levels up to 2,000,000 times.
 
Electron microscopy is employed in anatomic pathology to identify organelles within the cells. Its usefulness has been greatly reduced by immunhistochemistry but it is still irreplaceable for the diagnosis of kidney disease, identification of immotile cilia syndrome and many other tasks.  
 
== Nuclear Bombs  ==
 
Nuclear medicine on a whole encompasses both the diagnosis and treatment of disease using nuclear properties. In imaging, the energetic photons emitted from radioactive nuclei are used for enhancing and viewing various pathologies.
 
Gamma cameras are used in nuclear medicine to detect regions of biological activity that are often associated with diseases. A short lived isotope, such as 123I is administered to the patient. These isotopes are more readily absorbed by biologically active regions of the body, such as tumors or fracture points in bones.
 
Positron emission tomography (PET) is primarily used to detect diseases of the brain and heart. Similarly to nuclear medicine, a short-lived isotope, such as 18F, is incorporated into a substance used by the body such as glucose which is absorbed by the tumor of interest. PET scans are often viewed alongside computed tomography scans, which can be performed on the same equipment without moving the patient. This allows the tumors detected by the PET scan to be viewed next to the rest of the patient's anatomy detected by the CT scan. Another 3D tomographic technique is SPECT but uses gamma camera like method for reconstruction.


==Diagnostic Imaging for Body Regions==
*[http://www.physio-pedia.com/Diagnostic_Imaging_for_Hip Diagnostic Imaging of the Hip for the Physical Therapist]
*[http://www.physio-pedia.com/Imaging_for_knee_conditions Diagnostic Imaging of the Knee for the Physical Therapist]
*[http://www.physio-pedia.com/Diagnostic_Imaging_of_the_Foot_and_Ankle_for_Physical_Therapists Diagnostic Imaging of the Ankle and Foot for the Physical Therapist]
*[[Diagnostic Imaging of the Shoulder]]
== References  ==
== References  ==


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[[Category:Procedures]]
[[Category:Procedures]]
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[[Category:Acute Care]]
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[[Category:Imaging]]

Latest revision as of 16:41, 21 March 2024

Original Editor - Rachael Lowe Top Contributors - Rachael Lowe, Lucinda hampton, Donald John Auson, Admin, Melissa Coetsee, Kim Jackson, Naomi O'Reilly, Adam Vallely Farrell and Karen Wilson

Overview[edit | edit source]

Cardiac MRI flow

Medical imaging refers to all diagnostic and therapeutic investigations/interventions conducted in a typical radiology department. It encompasses different imaging modalities and processes to obtain images of the human body for diagnostic, treatment and follow up purposes.

Imaging investigations have improved significantly over the years and play in important role in diagnostics. It also plays an important role in initiatives to improve public health through screening for certain conditions[1]. Imaging does however need to be utilised with caution and sound clinical reasoning in order to avoid the potential harms of medical imaging, such as radiation and iatrogenic pain.

Types of Imaging[edit | edit source]

  • X-rays (including plain radiographs, DEXA scans and fluoroscopy): Allows upright and dynamic imaging; assesses bony structures and can help to detect pulmonary pathology, abnormal growths, factures, oedema and deformities.
  • Magnetic resonance imaging (MRI): Advanced imaging of soft tissue structure
  • Ultrasound (US)
  • Computed tomography (CT): More accurate assessment of bony structures
  • Nuclear medicine: is the practice of utilising microscopic amounts of radioactive substances to diagnose, monitor and treat disease.[2]
  • PET (positron emission tomography) scan: an imaging test that involves the intravenous injection of a positron-emitting radiopharmaceutical, waiting to allow for systemic distribution, and then scanning for detection and quantification of patterns of radiopharmaceutical accumulation in the body. Used to diagnose a variety of diseases (for example tumours, heart disease, brain disorders). Provides a picture of the body working.[3]
  • SPECT (Single photon emission computed tomography) similar to PET, is a nuclear medicine imaging techniques which provide metabolic and functional information unlike CT and MRI.[4]

Hybrid Imaging[edit | edit source]

PET-MRI

Hybrid Imaging is the fusion of two (or more) imaging modalities to form a new technique[5]. By combining the innate advantages of the fused imaging technologies synergistically, usually a new and more powerful modality comes into being. Existing hybrid imaging modalities include: PET-CT, SPECT-CT, MRI-PET, MRI-SPECT

The general benefits of hybrid imaging include: Increased diagnostic accuracy, precise monitoring of interventional procedure and reduced radiation exposure, e.g. dynamic US after obtaining CT map.

Photoacoustic Imaging (PA)[edit | edit source]

Schematic illustration of PA imaging

Also known as Optoacoustic Imaging, is an upcoming biomedical imaging modality availing the benefits of optical resolution and acoustic depth of penetration. Optoacoustic imaging has demonstrated promising potential in a wide range of preclinical and clinical applications.[6] Clinical applications of optoacoustic imaging include: Musculoskeletal Imaging; Gastrointestinal Imaging; Breast imaging; Dermatologic Imaging eg Skin cancer; Vascular Imaging; Carotid Vessel Imaging.[6]

Studies have showed the potential use of optoacoustic imaging in the assessment, diagnosis and monitoring of treatment in patients with inflammatory arthritis[7] as well as limb and muscle ischemia.[8]

Necessity of Medical Imaging[edit | edit source]

CT spinal cord

Medical imaging is crucial in a variety of medical setting and at all major levels of health care. In public health and preventive medicine as well as in both curative and palliative care, effective decisions depend on correct diagnoses. Though clinical reasoning may be sufficient prior to treatment of many conditions, the use of diagnostic imaging services is paramount in confirming, correctly assessing and documenting courses of many diseases as well as in assessing responses to treatment.

Caution with Imaging[edit | edit source]

Imaging is a useful resource for many conditions and is an invaluable tool for clinicians/physiotherapists when used appropriately. It is important to know when imaging is appropriate, as unnecessary imaging will squander financial resources and increase the potential for premature surgery/ iatrogenic effects.

Early or unnecessary referral for imaging may be influenced by patient expectations and clinician concerns, or may be used as way to reassure patients. These factors need to be managed with good communication and evidence based guidelines.[9]

Also see: Diagnostic Imaging Best Practice

Iatrogenic Effects[edit | edit source]

Abnormal radiologic findings of the musculoskeletal system can be very common. Not all abnormalities are relevant to a patient's complaint and over-emphasising radiologic findings can have harmful effects.

  • Routine MRI reports produce worse functional outcomes compared to a 'clinical report' (which includes reassurance of incidental findings) in patients with low back pain.[10]
  • Early-MRI in acute low back pain results in longer length of disability, higher medical cost and worse outcomes regardless of radiculopathy (even after controlling for severity and demographics)[9]

It is therefore very important to carefully consider whether imaging is indicated, and to always view the results in the context of an in depth history and physical examination. This will help to discern whether findings correlate with the patient's complaint, or are in fact incidental and negligible.

Radiation[edit | edit source]

Even though most imaging techniques use low doses of radiation, large, repeated doses have a cumulative effect and can be harmful to human health (including cancer and tissue damage). "Image gently" and "Image wisely" are initiatives that promote practices that reduce radiation exposure by eliminating unnecessary procedures (see resource section).[11]Modern techniques have also resulted in reductions in radiation exposure during imaging.

Factors that should be considered include a patient's age and lifetime exposure to radiation, as well as whether the benefit of the diagnostic test outweighs the risk. CT-scans have higher radiation risk than x-rays, whereas no ionising radiation is produced during MRI or ultrasound scans.[12]

Radiation risk is of particular concern in the following scenarios:[12]:

  • During infancy and early childhood
  • During pregnancy (especially early)

Asymptomatic Findings[edit | edit source]

Although advanced imaging is generally very sensitive, it can be very non-specific. Various studies have found that imaging findings and symptoms often do not correlate. Consider the table below - these findings provide evidence that what we regard as pathology may not be that significant. Also see the pages on imaging of specific body regions for more detail:

Pathologies in asymptomatic subjects
Pathology Prevalence among asymptomatic population
Lumbar disc herniation and/or spinal stenosis 20- 75%
Cervical disc bulging 75 - 90%[13]
Cervical spinal cord compression 7 - 35% [14]
Rotator cuff tendinopathy 25 - 89% [15]
Mild glenohumeral or acromioclavicular OA 12 50 - 70%[15]
Hip labrum tear 13/14 54% [16]
Knee Meniscal abnormalities and OA 19 60% [17]

Health Care Team[edit | edit source]

Imaging for medical purposes involves a team which includes the service of radiologists, radiographers (x-ray technologists), sonographers (ultrasound technologists), medical physicists, nurses, biomedical engineers, and other support staff working together. Appropriate use of medical imaging requires a multidisciplinary approach.[1]

Conclusion[edit | edit source]

Medical imaging is a crucial component of healthcare and provide a valuable tool for diagnosis, screening and treatment. It is however important to follow best practice guidelines with a particular focus on avoiding unnecessary imaging and ensuring appropriate, evidence-based interpretation of results. We treat whole, complex persons - not images and scans.

Diagnostic Imaging for Body Regions[edit | edit source]

References[edit | edit source]

  1. ↑ 1.0 1.1 WHO Diagnostic Imaging Available from: https://www.who.int/diagnostic_imaging/en/(accessed 7.4.2021)
  2. ↑ Radiopedia Nuclear medicine Available:https://radiopaedia.org/articles/nuclear-medicine (accessed 8.10.20220
  3. ↑ Radiopedia PET Available: https://radiopaedia.org/articles/positron-emission-tomography(accessed 8.10.2022)
  4. ↑ Radiopedia SPECT vs PET Available:https://radiopaedia.org/articles/spect-vs-pet (accessed 8.10.2022)
  5. ↑ Radiopedia Modalities Available from:https://radiopaedia.org/articles/modality?lang=us (accessed 7.4.2021)
  6. ↑ 6.0 6.1 Amalina Binte Ebrahim Attia, Ghayathri Balasundaram, Mohesh Moothanchery, U.S. Dinish, Renzhe Bi, Vasilis Ntziachristos, Malini Olivo, A review of clinical photoacoustic imaging: Current and future trends, Photoacoustics, Volume 16, 2019, 100144, ISSN 2213-5979, obtained from https://www.sciencedirect.com/science/article/pii/S2213597919300679 doi: 10.1016/j.pacs.2019.100144
  7. ↑ Jo J, Tian C, Xu G, et al. Photoacoustic tomography for human musculoskeletal imaging and inflammatory arthritis detection. Photoacoustics. 2018;12:82–89. Published 2018 Jul 27 obtained from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306364/ doi:10.1016/j.pacs.2018.07.004
  8. ↑ Chen L, Ma H, Liu H, et al. Quantitative photoacoustic imaging for early detection of muscle ischemia injury. Am J Transl Res. 2017;9(5):2255–2265. Published 2017 May 15 obtained from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446508/
  9. ↑ 9.0 9.1 Webster BS, Bauer AZ, Choi Y, Cifuentes M, Pransky GS. Iatrogenic consequences of early magnetic resonance imaging in acute, work-related, disabling low back pain. Spine. 2013 Oct 15;38(22):1939-46.
  10. ↑ Rajasekaran S, Dilip Chand Raja S, Pushpa BT, Ananda KB, Ajoy Prasad S, Rishi MK. The catastrophization effects of an MRI report on the patient and surgeon and the benefits of ‘clinical reporting’: results from an RCT and blinded trials. European Spine Journal. 2021 Jul;30:2069-81.
  11. ↑ Ford B, Dore M, Moullet P. Diagnostic imaging: appropriate and safe use. American Family Physician. 2021 Jan 1;103(1):42-50.
  12. ↑ 12.0 12.1 Mafraji, M.A. Risk of Radiation in Medical Imaging [Internet]. Merck Manuals. 2023 [updated 2023 November; cited 2024 March]. Available from: https://www.msdmanuals.com/home/special-subjects/common-imaging-tests/computed-tomography-ct
  13. ↑ Nakashima H, Yukawa Y, Suda K, Yamagata M, Ueta T, Kato F. Abnormal findings on magnetic resonance images of the cervical spines in 1211 asymptomatic subjects. Spine. 2015 Mar 15;40(6):392-8.
  14. ↑ Smith SS, Stewart ME, Davies BM, Kotter MR. The prevalence of asymptomatic and symptomatic spinal cord compression on magnetic resonance imaging: a systematic review and meta-analysis. Global spine journal. 2021 May;11(4):597-607.
  15. ↑ 15.0 15.1 Girish G, Lobo LG, Jacobson JA, Morag Y, Miller B, Jamadar DA. Ultrasound of the shoulder: asymptomatic findings in men. American Journal of Roentgenology. 2011 Oct;197(4):W713-9.
  16. ↑ Heerey, J.J., Kemp, J.L., Mosler, A.B., Jones, D.M., Pizzari, T., Souza, R.B. and Crossley, K.M., 2018. What is the prevalence of imaging-defined intra-articular hip pathologies in people with and without pain? A systematic review and meta-analysis. British Journal of Sports Medicine, 52(9), pp.581-593.
  17. ↑ Englund M, Guermazi A, Gale D, Hunter DJ, Aliabadi P, Clancy M, Felson DT. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. New England Journal of Medicine. 2008 Sep 11;359(11):1108-15.
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