Claus Stefan Simpfendorfer MD, Presenter: Nothing to Disclose

Murali Sundaram MD, Abstract Co-Author: Nothing to Disclose

Hakan Ilaslan MD, Abstract Co-Author: Nothing to Disclose

Thomas W. Bauer MD, PhD, Abstract Co-Author: Nothing to Disclose

The purpose of this study is to determine if the presence of focal normal bone marrow signal within an osseous tumor on magnetic resonance imaging excludes malignancy.

167 tumors of the appendicular skeleton and pelvis were biopsied or resected from January 2002 through February 2007. 72 tumors had available MRI imaging, however surface tumors, previously treated tumors, and pathologic fractures were excluded. 64 tumors (50 malignant and 14 benign) were ultimately reviewed. 2 blinded radiologists reviewed the MRI’s independently and reported the presence or absence of normal marrow within the tumor based upon T1-weighted imaging without fat-suppression and T2 weighted imaging with fat-suppression and/or STIR. Discrepancies were then reviewed in consensus to determine the presence or absence of focal normal marrow. The frequency of focal normal marrow was calculated for the benign and malignant tumors. A two-tailed Fisher's exact test was then used to compare the benign versus malignant tumors. Positive and negative predictive values were also calculated.

The interobserver reliability was 95.3% with a discrepancy in 1 malignant and 2 benign tumors. Reader consensus identified normal marrow within 1 of 50 (2.0%) malignant and 3 of 14 (21.4%) benign tumors. Findings were statistically significant with a p-value of 0.030. The positive predictive value that a tumor is benign, given the presence of normal marrow is 75%. The negative predictive value, given the absence of normal marrow is 82%. The only malignant lesion with normal marrow signal was a focal tibial lymphoma (histological diagnosis) which has remained stable for 4 years despite never receiving treatment or manifesting disease elsewhere. If this lesion were considered benign, 0% of malignant and 26.6% of benign tumors would have focal normal marrow with a calculated p-value of 0.002. The positive and negative predictive values would then be 100% and 82% respectively.

The presence of focal normal marrow signal within an osseous tumor is highly suggestive of a benign tumor.

Follow up imaging would be recommended over biopsy in osseous tumors with focal normal marrow signal.

Simpfendorfer, C, Sundaram, M, Ilaslan, H, Bauer, T, Does the Presence of Focal Normal Marrow Signal within a Tumor on MRI Exclude Malignancy? A Retrospective Analysis of Tumors Involving the Appendicular Skeleton and Pelvis.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5005095.html