MRI: Understanding its limitations

In his article, Mr Cherniak argues that compelling reasons exist why MRI should be considered for practically every personal injury claimant. He argues that MRI will, in every instance, benefit the claimant, lawyer, and doctor.

Prior to accepting Mr Cherniak’s position, there are important points to consider.

The use of magnetic resonance imaging (MRI) in musculoskeletal medicine has allowed the noninvasive evaluation of soft tissue structures (muscles, tendons, and ligaments), bony elements, and the neuroaxial canal.

In the medical context, the use of MRI is generally reserved for those instances when the results will influence the decision algorithm in patient management. In personal injury cases, MRI can provide clarity to the medical issues.

In his article, Mr Cherniak indicates the primary purpose of the litigation-driven MRI scan can always be said to assist the lawyer in preparation and presentation of the claimant’s case. It is often difficult, however, to separate the medical implications of ordering an MRI from the legal implications. The physician, in every case, will be responsible to explain the medical relevance of the findings to the patient.

The use of advanced imaging should not be guided by the occurrence of an injury but rather by specific clinical signs and symptoms resulting from an injury. In litigation-driven MRIs this approach is potentially violated and significant pitfalls may arise. These potential pitfalls are recognized by physicians, and their reluctance to overinvestigate patients is frequently justified.

 Pitfalls of an MRI showing abnormalities

MRIs define anatomical structures. In certain instances MRIs may be able to provide clues of a specific pain generator, but are unable to independently distinguish painful abnormalities from painless abnormalities. MRIs are unable to show us whether abnormal appearing tissues are functioning normally.

Abnormal shoulder and lumbar spine MRI findings in asymptomatic people are common, with the prevalence of abnormal MRI findings in asymptomatic people ranging up to 30% to 60%.[1,2] Asymptomatic MRI abnormalities can include complete rotator cuff tears, facet arthropathy, degenerative disc disease, spinal nerve impingement, and disc protrusions.

Following a musculoskeletal injury, most serious medical or surgical pathology can be clinically ruled out through physical examination, history-taking, and basic imaging modalities. In most cases a treatment plan and the phases of recovery may be embarked upon as the next step.

Overinvestigation with advanced imaging without specific clinical signs and symptoms may result in imaging findings that cloud rather than clarify the patient’s problems.

Regardless of medical necessity, patients suffering pain and disability with abnormal MRI findings frequently require referral to specialists to interpret the relevance of the imaging findings. Waiting times for specialist appointments can add to patient anxiety and potentially delay participation in treatment programs, return to work, and recovery.

The fact that false positives are common may be used against some patients. Some insurance companies or lawyers may interpret this fact incorrectly in personal injury cases, and discount abnormal MRI findings when the abnormality may in fact indicate a cause for the pain.

Although MRIs may be considered as objective evidence in court, abnormal MRI findings in one patient may be causally related to permanent neurological impairment and pain. In another patient, the same MRI findings may be asymptomatic.

 Pitfalls of a normal MRI

The presence of a normal MRI does not imply that a structure is not painful. Musculoskeletal and neurologic structures may cause pain and functional impairment in the absence of MRI abnormalities. Although an MRI showing no abnormality is usually a favorable result for the claimant or patient, there is little basis to advise a patient that his or her symptoms will eventually subside because the MRI is normal.

Conclusions

In order to avoid the pitfalls potentially associated with the use of MRI in musculoskeletal-related injuries, it is important to have an understanding of the indications and limitations of advanced imaging techniques in the individual patient or claimant.

Competing interests
None declared.

Mark Adrian, MD, FRCPC

Dr Adrian is a specialist in physical medicine and rehabilitation. He practises at the Vancouver General Hospital Spine Clinic.