Diagnostic Imaging: Best Practice

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Original Editor - Melissa Coetsee

Top Contributors - Melissa Coetsee, Kristen Holeman, Vidya Acharya and Alexandra Stead  

Introduction

Inappropriate diagnostic imaging is a major contributor to unnecessary health care expenditure and overtreatment. Improved awareness of the risks, benefits and evidence-based recommendations can improve decision-making and avoid unnecessary imaging.

The use of diagnostic imaging has doubled in the United States over a 16-year period.

Potential factors that influence unnecessary imaging:

• Patient expectations/requests, and the need to find proof that their pain is real
• Clinician's fear of missing severe pathology
• Lack of awareness of current guidelines
• Lack of awareness of the harm of unnecessary imaging
• Belief that imaging will reassure patients
• A lack of access to conservative management options

These factors need to be managed with good communication and evidence-based guidelines.

Types of Diagnostic Imaging

A variety of diagnostic imaging modalities are available to assist in the evaluation of musculoskeletal conditions. Each modality utilises different technologies to visualise bones, joints, soft tissues or physiological processes that each possesses distinct advantages, limitations, and clinical indications. Selection of the appropriate imaging should be guided by the patient’s history, physical examination, suspected pathology, and the likelihood that the imaging findings will influence clinical management.

Table 1: Types of Diagnostic Imaging

Modality	Best For	Advantages	Limitations
Radiographs (X-ray)	Fractures, alignment, osteoarthritis	Fast, inexpensive, widely available	Limited soft tissue visualisation, ionizing radiation
MRI	Soft tissue, bone marrow, neural structures	Excellent soft tissue contrast; no ionizing radiation	Higher cost, longer examination time, contraindications for some implants
CT	Complex fractures, cortical bone, tumour detection	Excellent bony detail, rapid acquisition	Higher radiation dose than radiographs
Ultrasound	Tendons, muscles, bursae, dynamic assessment	Dynamic imaging, inexpensive, no radiation	Operator dependent; limited penetration through bone
Fluoroscopy	Barium enema procedures, cardiac catheterization, joint injections	Real-time imaging, guidance during procedures	Ionizing radiation exposure, potential for contrast dye reactions

Clinical Indications for Diagnostic Imaging

Historically, diagnostic imaging was commonly incorporated into the routine evaluation of patients with musculoskeletal conditions. However, growing evidence has demonstrated that routine imaging for non-specific musculoskeletal pain does not improve clinical outcomes and is associated with increased healthcare utilisation, longer work absence, and unnecessary interventions.

To promote evidence-based practice and reduce low-value care, several organisations have developed clinical practice guidelines outlining the appropriate use of diagnostic imaging. The American College of Physicians (ACP), American College of Radiology (ACR), and the National Institute for Health and Care Excellence (NICE) consistently recommend against routine imaging for patients with non-specific musculoskeletal conditions in the absence of red flag signs or symptoms. These organisations generally agree that diagnostic imaging should be considered when one or more of the following clinical indications are present:

• Red flag signs or symptoms suggestive of serious pathology
• Suspected fracture or significant trauma
• Suspected infection
• Suspected malignancy
• Progressive or severe neurological deficits
• Surgical or interventional planning
• Failure of an appropriate course of conservative management when imaging findings are expected to influence clinical decision-making

In addition to these clinical practice guidelines, international initiatives such as Image Wisely® and Image Gently® have been established to promote the responsible use of diagnostic imaging. These campaigns encourage healthcare professionals to minimise unnecessary radiation exposure and optimise imaging practices through evidence-based decision-making while maintaining high-quality patient care.

Risks of Unnecessary Imaging

Although diagnostic imaging is an essential tool when clinically indicated, unnecessary imaging may expose patients to a variety of physical, psychological, and economic harms without improving clinical outcomes. In patients with uncomplicated musculoskeletal conditions, particularly non-specific low back pain, routine imaging rarely changes management and may contribute to overdiagnosis, incidental findings, unnecessary radiation exposure (with radiographs and CT), patient anxiety, nocebo effects, increased healthcare utilisation, and unnecessary interventions. These risks highlight the importance of adhering to evidence-based imaging guidelines and correlating imaging findings with the patient's clinical presentation.

Asymptomatic Imaging Findings

Advances in diagnostic imaging have improved the ability to detect structural abnormalities within the musculoskeletal system. However, numerous studies have demonstrated that many imaging findings commonly associated with musculoskeletal disorders are also highly prevalent in asymptomatic individuals and often represent normal age-related changes rather than the source of a patient's symptoms.

Common asymptomatic imaging findings include:

• Disc degeneration
• Disc bulges
• Rotator cuff tears
• Meniscal tears
• Labral tears
• Osteoarthritic changes

Because many of these findings are incidental and demonstrate a poor correlation with pain or functional impairment, imaging results should always be interpreted within the context of the patient's history and physical examination. When age-related or incidental findings are incorrectly attributed as the cause of symptoms, patients may develop unnecessary anxiety and misconceptions regarding their condition. This may lead to additional diagnostic testing, specialist referrals, more invasive treatments, and increased healthcare utilisation without improving clinical outcomes.

The most commonly studied musculoskeletal condition in relation to diagnostic imaging is LBP. Age-related degenerative changes are frequently identified in individuals without LBP. The prevalence of these findings steadily increases along the lifespan, suggesting that many imaging abnormalities represent normal aging rather than clinically significant pathology. Table 2 illustrates the prevalence of common lumbar MRI findings in asymptomatic individuals:

Table 2: Prevalence of Common Lumbar MRI Findings in Asymptomatic Individuals

Imaging Finding	Prevalence in Asymptomatic Individuals
Disc Degeneration	37% at age 20 → 96% at age 80
Disc Bulge	30% at age 20 → 84% at age 80
Disc Protrusion	29% at age 20 → 43% at age 80
Facet Degeneration	4% at age 20 → 83% at age 80

Overdiagnosis

Overdiagnosis is defined as "the identification of abnormalities that are unlikely to cause symptoms, disease progression, or harm during a patient's lifetime". In musculoskeletal medicine, overdiagnosis may occur when highly sensitive imaging modalities detect incidental findings or normal age-related anatomical changes that are subsequently labelled as pathological and assumed to be the source of a patient's symptoms. Although these findings are accurately identified, they frequently represent asymptomatic or age-related changes that do not require intervention.

When imaging findings are interpreted without appropriate clinical correlation, patients may undergo additional diagnostic testing, specialist referrals, or treatments that provide little or no clinical benefit. Overdiagnosis has been associated with increased healthcare utilization, higher healthcare costs, prolonged work absence, unnecessary interventions, and patient labelling without corresponding improvements in pain, function, or quality of life.

"Incidentalomas"

The increased use of advanced diagnostic imaging has led to a rise in the detection of incidental findings, commonly referred to as incidentalomas which occur in 20-50% of imaging studies. An incidentaloma is an unexpected imaging finding that is unrelated to the patient's presenting symptoms and is discovered unintentionally during diagnostic evaluation. Discernment is required to determine when such findings require further investigation or pose no threat in the absence of symptoms. As imaging technology has become more sensitive, these incidental findings are identified with increasing frequency, many of which represent normal age-related or clinically insignificant anatomical variations. While often benign, incidentalomas may trigger a cascade of additional diagnostic tests, specialist referrals, repeat imaging, invasive procedures, increased healthcare costs, and patient anxiety without improving clinical outcomes. This phenomenon contributes to overdiagnosis and exposes patients to unnecessary iatrogenic harm.

The "cascade effect"

A concept that's becoming increasingly discussed in the literature is the diagnostic cascade or cascade effect, which often follows the discovery of an incidentaloma:

Unnecessary imaging → Incidentaloma → Additional imaging/testing → Specialist referral → Biopsy or intervention → Increased patient anxiety, costs, and potential complications.

Iatrogenic Effects

Clinical practice guidelines consistently discourage routine early diagnostic imaging for patients without specific signs of serious pathology, as imaging may expose patients to unintended iatrogenic consequences. When specifically studied in the acute low back pain population, early diagnostic imaging (MRI) without indication lead to:

• Increased total medical costs (approximately $13,000 per case)
• Increased disability
• Greater likelihood of unnecessary imaging, injections, surgery or opioid use
• Greater pain intensity
• Delayed return to work and daily activities

Nocebo Effect

One important mechanism underlying these iatrogenic harms is the nocebo effect, the effect of a patient's negative expectations about their health status which result in patient harm. With performance of diagnostic imaging patients are subject to labelling when told they have an abnormality on imaging. When findings of “abnormality" are communicated to a patient, this typically has a negative effect, increasing behaviours such as fear avoidance and decreasing patients' beliefs of improvement or resolution to symptoms.

Counteracting the negative interpretation of a pathology obtained by a diagnostic image has proven to be challenging. Phrases such as “bone-on-bone”, “degenerative disc disease”, and “disc herniation” have very negative interpretations by a patient and can lead to increased fear and poorer outcomes.

Patient education is the best way a clinician can communicate image findings to reduce negative perception, however, once labelling of a pathology occurs it can be difficult to counteract the consequences. Providing patients with education regarding pain science, and explaining that imaging findings do not correlate to impairment/disability, is an important component of reducing fear avoidance and supporting recovery. Frequent reassurance is also required to reduce fear avoidance patterns and improve patient’s confidence. Avoiding fear-provoking language is essential, and possible education regarding asymptomatic findings related to normal aging processes. 

Radiation Exposure

Unnecessary imaging may expose patients to radiation without evidence of improving pain, function, or quality of life. Diagnostic imaging, such as radiographs and computed tomography (CT) scans contribute to cumulative radiation exposure. CT examinations deliver substantially higher radiation doses than conventional radiographs and are associated with a small but measurable increase in lifetime cancer risk. It has been estimated that a 10 mSv CT scan carries an estimated lifetime attributable cancer risk of approximately 1 in 2,000 for an average adult with risk varying by age and sex (higher in younger patients).

While the radiation dose from a single examination is generally low, avoiding imaging that is unlikely to influence clinical management remains an important principle of patient safety and high-value care.  One of the easiest ways to communicate radiation risk is by comparing it with natural background radiation. Average background radiation exposure in the United States is approximately 3 mSv per year. Table 3 indicates the approximate effective dose of radiation exposure for the different diagnostic modalities:

Table 3: Approximate Dosage of Ionizing Radiation

Imaging Study	Approximate Effective Dose
MRI	0 mSv
Ultrasound	0 mSv
Lumbar Spine X-ray	1.4-1.5 mSv
Cervical Spine X-ray	0.2 mSv
CT Lumbar Spine	6-8 mSv
CT Cervical Spine	6-7 mSv

Conclusion

Diagnostic imaging has revolutionized the diagnosis and management of musculoskeletal conditions and remains an essential component of patient care when used appropriately. However, the increasing overuse of diagnostic imaging has become an important concern, as unnecessary imaging may contribute to overdiagnosis, incidental findings, nocebo effects, increased healthcare utilisation, higher healthcare costs, and unnecessary interventions, including opioid prescribing and surgical procedures. Evidence-based clinical practice guidelines developed by organisations such as the American College of Physicians (ACP), American College of Radiology (ACR), and the National Institute for Health and Care Excellence (NICE) provide clinicians with recommendations to support appropriate imaging decisions.

In practice, best practice imaging means: correlating any imaging findings with the patient's clinical presentation rather than treating the image in isolation; reserving imaging for cases meeting guideline-concordant indications, such as red flags or failure of conservative management; and communicating results using clear, non-threatening language that avoids unnecessary patient labelling. By integrating these principles with a thorough patient history and physical examination, clinicians can reduce low-value care, minimise potential iatrogenic harms, and ensure that diagnostic imaging is used judiciously to improve patient outcomes.

Resources

• ACR Appropriateness Criteria: Evidence-based guidelines to guide imaging decision-making
• American Society of Radiologic Technologists: Radiation risk calculator
• Image Gently: Free resources to reduce unnecessary imaging in children
• Image Wisely: Free resources to reduce unnecessary imaging in adults