Quantitative analysis of Gd enhancement histogram tails predicts transformation in low grade gliomas
Tofts P, Tozer D, Benton C, Weil R, Jager H, Waldman A, Altmann D, Rees J
Histograms of percent signal enhancement in low grade gliomas, after injection of double dose Gd, were calculated. Optimising the predictive ability of these histograms, the best feature is the right-hand tail, minus the left-hand tail, all multiplied by the tumour volume. This is the corrected volume of enhancing tissue. In 21 subjects (8 non-transformers, 13 transformers), all but one could be correctly classified using a threshold of 3.0ml. Kaplan-Meier survival curves for the time-to-transformation, based on a 4ml threshold for the uncorrected enhancing volume at the baseline examination, differed substantially (p < 0.04 at 5 years).