Reply

¹ From the Department of Radiology, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792-3252
² From the Department of Preventive Medicine, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792-3252
³ From the Department of Medicine, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792-3252
⁴ From the Department of Neurological Surgery, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792-3252
⁵ From the Department of Neurology, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792-3252
⁶ Department of Neurological Surgery, University of Rochester, NY

In conclusion, the authors' recommendation of MR imaging for all patients seems unreasonable to us. Seidenwurm et al present an understandable criticism that a large proportion of our patients (78 of 95 patients) did come from surgical clinics and that more patients received surgical treatment (56 of 95 patients) than conservative treatment (39 of 95 patients). This might be construed to bias our study. As we noted earlier, we believe that this directs the study results specifically to the patient population for which it is most relevant (ie, those in whom imaging is indicated after an initial adequate trial of conservative treatment).

In this decision environment, we submit that our data analysis and recommendations are valid (not flawed), based on the results of our study and examination costs like those at our institution. The authors should find encouragement in our statement on page 738 (2) that MR imaging will be an acceptable replacement for plain CT in patients with low probability of HNPNC when the cost of MR imaging decreases and approaches that of plain CT. This has happened recently in California. In that case, as we stated in our report, we would agree with Seidenwurm et al that plain CT can be replaced by MR imaging.

We hope that future commentary on our report will be more to the point scientifically and not rely on rhetoric and anecdotal evidence in place of comparative data like ours. The protocol of our study was the least biased, most rigorous methodology-based one that we could devise. As such, the study appears to be a rarity in the previous literature on the diagnostic accuracy of MR imaging and CT examination of the spine (2). One of our underlying aims has been to put radiologists who perform radiologic imaging technology assessment in a stronger position to compete with non-radiologists for grant support at the national level. We have secured peer-reviewed grant support for our multidisciplinary team and hope that other radiologists will become successful in use of such rigorous research methods.

It is appropriate to recall the prophetic comment by Fineberg (19), which remains as appropriate today as in 1978, when he stated the following:

Evaluation of CT, or of any dynamic medical technology, will never provide final answers. Findings will be open to interpretation. Individual values and judgments will always play a role. Decisions about the development, reimbursement, and use of new technologies will continue to be made, however imperfectly. The great challenge, embodied in CT but embracing all of medicine, is to bring policy and practice into line with knowledge.

Useful knowledge, we submit, is knowledge based on the least biased evidence with the highest scientific quality available.