Imaging Studies: When and When Not to Order Them

LAS VEGAS—Management of pain begins with the oftentimes challenging task of correctly diagnosing its cause, said David M. Glick, DC, Director of Neural Pain Assessment in Richmond, Virginia, adding that inadequate diagnostic workups are likely one of the most common causes of chronic pain.

Knowing when to order imaging studies and which imaging studies are most appropriate for a particular case is a key component of diagnosing a patient in pain, Dr. Glick said. Many imaging studies are unnecessary and can lead to mistaken or erroneous diagnoses resulting in unnecessary treatment of failed clinical outcomes he said.

Patient expectations are among the reasons clinicians order tests that may be unwarranted, Dr. Glick noted. Many patients mistakenly believe that imaging studies—and not the clinical experience of their healthcare provider—provide the definitive clues to the source of their pain, he said.

Another issue faced is that clinicians can misunderstand or misapply the results of imaging studies, possibly because they are unaware of their limitations. “I would argue, and could do it justifiably, that there is, and has been, a lot of red-herring diagnoses made from inappropriately assuming that pathologies seen on imaging studies were clinically significant when they were not,” said Dr. Glick.

CLINICAL EVALUATION TAKES PRECEDENCE

Objective clinical examination findings should not be dismissed solely on negative imaging study results, Dr. Glick said. He also pointed out to attendees that radiologists typically are not clinically familiar with a patient, and this should be kept in mind when reading radiologists' interpretation of imaging studies.

In formulating a clinical impression, he said, clinicians should consider whether a particular clinical situation seems familiar on the basis of patient history and whether the identified pathology could explain the patient's complaints or symptoms. There are times when clinicians should consider alternative explanations for a patient's complaints or symptoms, and not rely solely upon test results.

INCREASED COSTS WITHOUT IMPROVED OUTCOMES

Dr. Glick reviewed some recommendations developed as part of the Choosing Wisely initiative of the American Board of Internal Medicine. As part of this initiative, each of nine medical societies prepared documents titled Five Things Physicians and Patients Should Question. The American Academy of Family Physicians (AAFP) advises against ordering imaging studies for low back pain within the first six weeks, unless “red flags” are present. These include severe or progressive neurologic deficits or suspicion of serious underlying conditions such as osteomyelitis. Imaging of the lower spine before six weeks does not improve outcomes, but does increase costs, according to AAFP.

The American College of Radiology (ACR) advises against imaging for uncomplicated headache. “Imaging headache patients absent specific risk factors (such as loss of vision, seizures, etc.) for structural disease is not likely to change management or improve outcome,” ACR wrote.  Clinicians should pay attention to conditions that can result in increased morbidity or mortality if not identified promptly, that is, “red flags,” and not delay ordering a study in such circumstances, he said.

IMAGING LIMITATIONS

Imaging studies are also accompanied with limitations. With nerve root compression, for instance, magnetic resonance imaging (MRI) can demonstrate disc compression of a nerve but not inflammation of a nerve (radiculitis).

Furthermore, MRI studies may not provide the appropriate imaging detail. For example, all intrinsic muscles of the hand are innervated by C8-T1 nerves, as are most muscles for grip. If upper extremity symptoms extend to hands or include decreased grip strength, it is highly likely that C8 or T1 may be involved. However, most cervical MRIs do not image the T1 root and many do not include C8. When ordering cervical MRIs for neck and upper extremity pain, always request that axial images include C8 and T1 nerve roots, he said.

Additionally, Dr. Glick noted a preponderance of research has demonstrated that MRIs of the lumbar spine often show that many patients without back pain have disc bulges or protrusions. Given the high prevalence of these findings and of back pain, the discovery by MRI of bulges or protrusions in patients with low back pain may frequently be coincidental, Dr. Glick stressed to attendees. Complicating matters further patients often become overly consumed with pathologies that may be clinically insignificant, such as an asymptomatic disc bulge, with the perception having an adverse effect upon their response to treatment. Abnormalities on MRI scans must be strictly correlated with age and any clinical examination findings and symptoms before operative or other treatments are considered.

Imaging studies can have a key role in the diagnosis and clinical management of a variety of painful pathologies, Dr. Glick said. They can also lead to potentially unnecessary and inappropriate treatments that result in increased morbidity and healthcare resources.

“With better understating of both the clinical abilities and limitations of each study, clinicians can significantly improve clinical outcomes when treating their patients essentially enhancing the quality of care while decreasing the cost,” he concluded.