WASHINGTON — MRI images taken when the patient is upright can make a world of difference when evaluating a patient's spinal pathology before and after surgery, Dr. J. Randy Jinkins said at the annual meeting of the American Society for Neuroradiology.

"Scanning patients flat on their backs really isn't doing the job," said Dr. Jinkins, senior research fellow with Fonar Corp., the Melville, N.Y.-based manufacturer of the Stand-Up MRI. Images taken while the patient is lying down can seriously underestimate the degree of degenerative spinal pathology, he said.

An MRI performed while the patient is in a standing position, however, can help identify position-related, clinically relevant spinal pathology to ensure that an accurate diagnosis is made, he said.

The machine is fully open from both the front and the top, so that the patient can flex and extend his or her spine various degrees while standing or sitting. The scan table translates, rotates, and elevates without interfering with the magnetic field.

Importantly, the Stand-Up MRI permits a variety of images to be taken when the patient is in weight-bearing positions and is therefore more likely to capture what the spine looks like in painful versus nonpainful positions. At least one sequence of images should be taken when the patient is in the most painful position so symptoms can be correlated with imaging observations, advised Dr. Jinkins, who is also professor of radiology at Drexel University, Philadelphia.

However, data on the clinical value of determining the maximal degree of spinal pathology are anecdotal.

Case in point: At 8 months of follow-up after undergoing a partial diskectomy on the right side at L5-S1, a patient developed a recurrent radiculopathy that was symptomatic only in a standing or sitting position. A postoperative supine-recumbent MRI showed no abnormality. A sagittal image in the upright position acquired by Stand-Up MRI revealed a large disk herniation protruding into the epidural space on the right side at the L5-S1 level, the side and the point of the prior microdiskectomy. The MRI images in the upright, weight-bearing position were consistent with the patient's specific position-related pain.

In another patient who had not had prior treatment, a supine-recumbent MRI showed a narrowed, desiccated disk in the midlumbar region and a very minor narrowing of the central spinal canal at the same level (fig. A). When the patient was in a neutral sitting position (partial flexion), however, the Stand-Up MRI images revealed an anterior subluxation of the suprajacent vertebral body on the subjacent body (degenerative anterior spondylolisthesis) and a greater degree of central spinal stenosis (fig. B). Therefore, the patient demonstrated hypermobile intersegmental spinal instability, a condition that may require spinal fusion at the involved level.

Such scenarios suggest that the patient's true diagnosis was missed on standard MRI, he said.

"It has always surprised me that when we speak about failed back surgery, it's always the surgeon that seems to be at fault," Dr. Jinkins added. In some cases, however, perhaps the real source of failed back surgery is in selecting an insensitive modality for preoperative assessment of the spine.

"As the scanner makes its inroads into your community, it's going to raise the standard of care," he said. But availability of the technology is a hurdle at this point.

Currently, a total of 18 Stand-Up MRIs are available for commercial use in New York, Maryland, Florida, and California, Dr. Jinkins said. Nor do CPT codes for the procedure exist yet, Dr. Jinkins said, so ancillary codes have been used.

About 50% of all MRIs in the United States involve the spine.

Fig. A: Recumbent MRI shows disk degeneration and minor central canal stenosis at L3-4.

Fig. B: MRI in a sitting position shows mildly increased central canal stenosis at L3-4. Photos courtesy Dr. J. Randy Jinkins