Medical Imaging

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

Overview

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 can play an important role in initiatives to improve public health through screening for certain conditions. It does however need to be utilised with caution and clinical reasoning in order to avoid the potential harms of medical imaging, such as radiation and iatrogenic pain.

Types of Imaging

• 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.
• 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.
• 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.

Hybrid Imaging

PET-MRI

Hybrid Imaging is the fusion of two (or more) imaging modalities to form a new technique. 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)

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. Clinical applications of optoacoustic imaging include: Musculoskeletal Imaging; Gastrointestinal Imaging; Breast imaging; Dermatologic Imaging eg Skin cancer; Vascular Imaging; Carotid Vessel Imaging.

Recent studies showed the potential use of optoacoustic imaging in the assessment, diagnosis and monitoring of treatment in patients with inflammatory arthritis as well as limb and muscle ischemia.

Necessity of Medical Imaging

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 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

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

Caution with Imaging

Also see: 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.

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

Large, repeated doses of exposure to ionising radiation can be harmful to human health. "Image gently" and "Image wisely" are initiatives that promote practices that reduce radiation exposure by eliminating unnecessary procedures.

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.

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 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

• Diagnostic Imaging of the Hip for the Physical Therapist
• Diagnostic Imaging of the Knee for the Physical Therapist
• Diagnostic Imaging of the Ankle and Foot for the Physical Therapist
• Diagnostic Imaging of the Shoulder