HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Aiello, M. R. Articles by Cvitanic, O. Search for Related Content PubMed PubMed Citation Articles by Aiello, M. R. Articles by Cvitanic, O. Social Bookmarking                      What's this?

MR Imaging of Marrow Changes After Laser Diskectomy

Adirondack Medical Center Saranac Lake, NY 12983

The authors of "Subchondral Marrow Changes after Laser Diskectomy in the Lumbar Spine: MR Imaging Findings and Clinical Correlation" [1] state that all seven patients in whom IV gadolinium was administered showed enhancement of the involved subchondral bone, but not the treated disk. Figure 5A is a sagittal T1-weighted MR image showing symmetric elliptic areas of hypointensity in subchondral bone at L3-L4. Figure 5B is a gadolinium-enhanced sagittal T1-weighted MR image that clearly shows disk enhancement, but without apparent connection to the subchondral bone enhancement.

Perhaps contrast enhancement of the disk could reflect normal postoperative change with the enhancing scar related to target tissue vaporization and thermal superimposition. Could the authors comment on this apparent discrepancy?

References

1. Cvitanic OA, Schimandle J, Casper GD, Tirman PFJ. Subchondral marrow changes after laser diskectomy in the lumbar spine: MR imaging findings and clinical correlation. AJR 2000;174:1363 -1369[Abstract/Free Full Text]

Reply

Southwest Oklahoma MRI Oklahoma City, OK 73120

I thank Dr. Aiello for his interest in our article describing subchondral marrow signal changes in the lumbar spine on MR imaging after laser diskectomy [1]. The authors agree that mild gadolinium enhancement identified in the central portion of the disk at L3-L4 does not connect with areas of enhancing subchondral bone marrow above and below L3-L4 in Figure 5B of our article. Our explanation is as follows: partial ablation is the intended effect of the laser. The mechanism is heat absorption with vaporization. This vaporization occurs within 0.2 mm of the laser tip and creates a void. The mechanism of endplate injury, on the other hand, is believed to be heat absorption without vaporization. Heat transmission to the endplate is through the disk rather than as a consequence of direct exposure of the endplate to laser fire. Enhancing granulation tissue subsequently replaces vaporized nucleus pulposus centrally in the disk. Enhancement also appears in heat-injured subchondral bone, but not in the intervening disk.

References

1. Cvitanic OA, Schimandle J, Casper GD, Tirman PFJ. Subchondral marrow changes after laser diskectomy in the lumbar spine: MR imaging findings and clinical correlation. AJR 2000;174:1363 -1369

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Aiello, M. R. Articles by Cvitanic, O. Search for Related Content PubMed PubMed Citation Articles by Aiello, M. R. Articles by Cvitanic, O. Social Bookmarking                      What's this?