Malignancy grading of soft-tissue sarcoma, and of leiomyosarcoma and liposarcoma in particular, is of prognostic importance. A quantitative non-invasive NMR measurement that directly correlates with mitotic activity would allow for early assessment of change in sarcoma growth rate pre- and post-therapy. As a first step towards meeting this goal, we have measured two-dimensional proton total correlated spectroscopy (TOCSY) spectra at 600 MHz of 3 x 10 mm core specimens originating from eight excised leiomyosarcomas (n=3) and eight excised liposarcomas (n=2). The histological grade (low, medium, high) of each tissue sample was classified by determining the degree of cellularity, pleomorphism, necrosis, and mean mitotic activity. TOCSY spectra showed cross peaks arising from amino acids, peptides, carbohydrates, triglycerides, and phospholipids. The cross peaks from methylene protons coupled to olefinic protons in fatty acyl chains are in particular well resolved and show favorable signal-to-noise ratios. The cross peaks from coupling between olefinic and allylic methylene protons and between olefinic and diallylic methylene protons in fatty acyl chains have been designated C and D, respectively. TOCSY spectra of oleic (18:1), linoleic (18:2), linolenic (18:3) and arachidonic (20:4) acids in chloroform solution yield D/C cross peak volume ratios of 0.0, 1.3, 2.7 and 4.0, respectively. This finding suggests that the D/C cross peak volume ratio can be a measure of the degree of fatty acyl unsaturation. We have found that the D/C cross peak volume ratio correlates with mean mitotic activity (r=0.88) for the leiomyosarcoma specimens examined and with the liposarcoma specimens examined. The D/C ratio for four patients with high grade leiomyosarcomas (2.6q0.4, n=13) was significantly higher compared to the low grade leiomyosarcomas (1.3q0.2, n=6) (p=0.001). In addition, the D/C ratio for low grade leiomyosarcomas was significantly higher than compared to normal smooth muscle (0.5q0.2, n=3) (p=0.001). These results show that the D/C cross peak volume ratio may used in determining histological grade of biopsied leiomyosarcoma. Additional trials are required for statistical evaluation of the liposarcomas. Future studies will include developing selective one-dimensional proton NMR methods to determine the integral of diallylic to allylic methylene protons at 600 MHz and at a magnetic field strength suitable for measurements in vivo. Other NMR correlates for histological grade determination will be examined. The leiomyosarcoma results have been submitted for publication in the Journal of Clinical Investigation.
Showing the most recent 10 out of 12 publications
