Imaging For Back Pain


May 7 2009 - 11:15am

When back or leg pain makes a visit to the doctor necessary, the physician will review the patient’s history, perform a physical exam, and make a diagnosis based on those findings.

The precise etiology (or cause) of most back pain is difficult to determine, but typically will resolve with standard treatment. In most cases, diagnostic imaging studies are not required for effective treatment.

When imaging studies for back or leg pain are indicated, they are administered in the following situations:

* The initial diagnosis is either in question or requires confirmation.

* The patient presents with symptoms possibly due to infection or a tumor.

* The patient experiences certain types of trauma.

* The patient’s condition or level of pain has not improved after the initial course of treatment.

The more specialized the doctor, the less imaging studies are generally needed, says Richard J. Herzog, MD, Chief of the Division of Teleradiology at Hospital for Special Surgery (HSS). “A general practitioner may order imaging studies sooner than a physiatrist or a spine surgeon,” he explains.

The information provided by imaging studies is utilized for both the diagnosis and treatment of back and leg pain. The quality of the imaging study and the accuracy of its interpretation will directly impact the care that a patient receives.

Methods of Imaging

While patients present with a wide range of causes of back or leg pain, the fundamental question that needs to be resolved for all patients is, “where is the pain coming from?”

There are several potential causes of pain, Dr. Herzog notes, including abnormalities of the disc, nerve roots, or vertebrae.

Imaging studies such as x-ray, CT (computed tomography), and MRI (magnetic resonance imaging) are all employed to evaluate patients who present with back or leg pain. The choice of which examination depends upon the specific clinical question that needs to be answered.

X-ray

Conventional radiographs, also known as plain films or x-rays, are particularly useful as the first imaging study in diagnosing the initial onset of back pain and before prescribing therapy. These x-rays should be obtained with the patient standing erect. Weight-bearing, standing x-rays are particularly important to determine the nature and extent of spinal deformities and treating problems of spinal alignment, such as scoliosis.

Gregory R. Saboeiro, MD, Chief of Interventional Radiology and CT at HSS, says that the ordering physician will prescribe a variety of different positions with the patient standing or bending, depending on their symptoms. “X-rays don’t provide the fine detail of CT or MRI,” he notes, “but they can be very important in evaluating the alignment and potential abnormal motion of the spine in the various positions obtained.”

“Certain spinal deformities that are demonstrated in x-rays taken when the patient is standing,” adds Dr. Herzog, “may not be detected when that same patient is lying down.”

Additional benefits of x-ray imaging include monitoring patients with spinal deformities or spinal imbalance and for follow-up during and after treatment or surgery.

Both doctors are quick to point out the drawbacks and limitations of x-ray imaging. X-rays provide little or no information when trying to diagnose a disc herniation or nerve root compression. And even though x-rays demonstrate vertebral bodies, they are less sensitive than other imaging studies in detecting bone destruction due to tumor or infection.

In most cases where additional information is needed to resolve a clinical question concerning back or leg pain, advanced imaging modalities such as MRI or CT will be employed.

CT

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