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>
<div class="editorbox"> '''Original Editor '''- [[User:Rachael Lowe|Rachael Lowe]] '''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}</div>
== Overview  ==
== Overview  ==
[[File:Structural MRI animation.ogv.jpg|right|frameless]]
[[File:Cardiac MRI flow.gif|alt=|thumb| Cardiac MRI flow ]]
<p align="justify">
<p align="justify">
Medical imaging is home to all diagnostic and therapeutic investigations/interventions conducted in a typical radiology department.  It encompasses different imaging modalities and processes to image the human body for diagnostic,  treatment and follow up purposes and plays an important role in initiatives to improve public health for all population groups<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>. It includes:
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"> [[X-Rays|X-rays]] (including eg plain xrays, DEXA scans, fluoroscopy)  </p>
* <p align="justify"> Magnetic resonance imaging ([[MRI Scans|MRI]])  </p>
* [[nuclear medicine]]: often cross-sectional radiotracer scanning e.g. PET is considered a separate modality from 'traditional' scintigraphy e.g. bone scans
* [[Ultrasound Scans|Ultrasound]] (US)
* [[CT Scans|Computed tomography]] (CT)
* Hybrid modalities<ref>Radiopedia [https://radiopaedia.org/articles/modality?lang=us Modalities] Available from:https://radiopaedia.org/articles/modality?lang=us (accessed 7.4.2021)</ref>
Medical imaging, especially X-ray based examinations and ultrasonography, 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 medical/clinical judgment 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
* <p align="justify"> Imaging is a useful resource for many conditions and is an invaluable tool for physical therapists when used appropriately.  </p>
* <p align="justify"> It is important to know when imaging is appropriate, as unnecessary imaging will squander financial resources and increase potential for premature surgery.  </p>
{{#ev:youtube|https://www.youtube.com/watch?v=Dm9iaq8uMkI|width}}<ref>The Audiopedia What is Medical Imaging? What does Medical Imaging mean? Medical Imaging meaning & explanation Available from: https://www.youtube.com/watch?v=Dm9iaq8uMkI (last accessed 1.10.19)</ref>
== 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 to optimize the wellbeing of patients, one at a time. Appropriate use of medical imaging requires a multidisciplinary approach.<ref name=":2" />
 
==Electron Microscopy==
<p align="justify">
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.  
</p>
</p>
<p align="justify">
<p align="justify">
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.  
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>
</p>


== Nuclear Medicine  ==
== Types of Imaging ==
<p align="justify">
Nuclear medicine on a whole encompasses both the diagnosis and treatment of disease using nuclear properties. In imaging, a radiopharmaceutical is injected to the patient, radiopharmaceuticals are drugs that contain radioactive isotopes, these then decay and emit energy that helps produce the images.. 
</p>
<p align="justify">
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.
</p>
<p align="justify">
Bone scan is an imaging technique that uses a radioactive compound to identify areas of healing within the bone. Bone scans work by drawing blood from the patient and tagging it with a bone seeking radiopharmaceutical. This radioactive compound emits gamma radiation. The blood is then returned to the patient intravenously. As the body begins its metabolic activity at the site of the injury, the blood tagged by the radioactive compound is absorbed at the bone and the gamma radiation at the site of the injury can be detected with an external gamma camera. A bone scan can be beneficial in determining injury to the bone within the first 24-48 hours of injury or when the displacement is too small to be detected by an x-ray or CT scan.<ref name="Swain">Swain J, Bush K.  Diagnostic Imaging for Physical Therapists. St. Louis:  Saunders Elsevier; 2009</ref>
</p>Indications for Bone Scans:
[[File:Bone Scan Stress Fracture.jpg|thumb|Stress Fracture under Bone Scan]]
#Primary and metastatic bone neoplasms.
#Disease progression or response to therapy.
#Paget’s disease of bone.
#Stress and/or occult fractures.
#Trauma – accidental and non-accidental.
#Osteomyelitis.
#Musculoskeletal inflammation or infection.
#Bone viability (grafts, infarcts, osteonecrosis).
#Metabolic bone disease.
#Arthritides.
#Prosthetic joint loosening and infection.
#Pain of suspected musculoskeletal etology.
#Myositis ossificans.
#Complex regional pain syndrome (CRPS 1). Reflex sympathetic dystrophy.
#Abnormal radiographic or laboratory findings.
#Distribution of osteoblastic activity prior to administration of therapeutic radio-pharmaceuticals for treating bone pain.<ref>College A. ACR Practice Guideline For The Performance Of Adult and Pediatric Skeletal Scintigraphy ( Bone Scan ). North. 2007:1-5.</ref>


== Electron Microscopy  ==
* [[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.
[[File:PET scan brain.png|thumb|200x200px|PET Scan of brain]]
* [[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>


=== Positron Emission Tomography ===
=== Hybrid Imaging ===
<p align="justify">
[[File:PET-MRI.jpeg|thumb|300x300px|PET-MRI]]
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.
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
</p><p align="justify"> </p>


=== Single Photon Emission Computed Tomography ===
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.
<p align="justify">
Single Photon Emission Computed Tomography (SPECT) is a widely used imaging technique in nuclear medicine for the visualization of organs, such as the bones, heart and brain, as well as for the detection of tumors.<ref>Warwick, J.M. Imaging of Brain Function Using SPECT. ''Metab Brain Dis'' 19, 113–123 (2004) obtained from https://link.springer.com/article/10.1023/B:MEBR.0000027422.48744.a3 doi:10.1023/B:MEBR.0000027422.48744.a3</ref>  Because of its capability to visualize and quantify changes in the cerebral blood flow and neurotransmitter system, it has important use in the differential diagnosis of neurological and psychiatric diseases. <ref>Andrew B. Newberg, Abass Alavi, Single Photon Emission Computed Tomography☆, Reference Module in Neuroscience and Biobehavioral Psychology, Elsevier, 2017, ISBN 9780128093245, obtained from https://www.sciencedirect.com/science/article/pii/B9780128093245024871 doi: 10.1016/B978-0-12-809324-5.02487-1</ref>
</p><p align="justify"> </p>


== Optoacoustic Imaging ==
=== Photoacoustic Imaging (PA) ===
[[File:PA.png|thumb|Schematic illustration of PA imaging]]
<p align="justify">
<p align="justify">
Also known as Photoacoustic Imaging, is an upcoming biomedical imaging modality availing the benefits of optical resolution and acoustic depth of penetration. With its capacity to offer structural, functional, molecular and kinetic information making use of either endogenous contrast agents like hemoglobin, lipid, melanin and water or a variety of exogenous contrast agents or both, 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,
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
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>
</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>
</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.
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" />
Also see: [[Diagnostic Imaging: Best Practice|Diagnostic Imaging Best Practice]]
=== 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.
* '''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>
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 ===
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.
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>
Radiation risk is of particular concern in the following scenarios:<ref name=":3" />:
* During infancy and early childhood
* During pregnancy (especially early)
=== 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>
* [[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]]
{| 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>
|}


Clinical applications of optoacoustic imaging include:<ref name=":1" />
== Health Care Team ==
* Breast imaging
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" />
* Dermatologic Imaging
** Pilosebaceous units
** Skin cancer
** Inflammatory skin diseases
* Vascular Imaging
** Cutaneous miscrovasculature
** Vascular Dysfunction
** Wound Imaging
* Carotid Vessel Imaging
* Musculoskeletal Imaging
* Gastrointestinal Imaging
* Adipose Tissue Imaging


<p align="justify">
== Conclusion ==
Recent studies 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
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.'''
</ref> as well 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>


==Diagnostic Imaging for Body Regions==
==Diagnostic Imaging for Body Regions==

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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