Volume 39, Issue 12, December 2012
Index of content:
Many methods have been proposed for tumor segmentation from positron emission tomographyimages. Because of the increasingly important role that [11C]choline is playing in oncology and because no study has compared segmentation methods on this tracer, the authors assessed several segmentation algorithms on a [11C]choline test-retest dataset.Methods:
Fixed and adaptive threshold-based methods, fuzzy C-means (FCM), Canny's edge detection method, the watershed transform, and the fuzzy locally adaptive Bayesian algorithm (FLAB) were used. Test-retest [11C]choline scans of nine patients with breast cancer were considered and the percent test-retest variability %VARTEST-RETEST of tumor volume (TV) was employed to assess the results. The same methods were then applied to two denoised datasets generated by applying either a Gaussian filter or the wavelet transform.Results:
The (semi)automated methods FCM, FLAB, and Canny emerged as the best ones in terms of TV reproducibility. For these methods, the %root mean square error %RMSE of %VARTEST-RETEST, defined as , was in the range 10%–21.2%, depending on the dataset and algorithm. Threshold-based methods gave TV estimates which were extremely variable, particularly on the unsmoothed data; their performance improved on the denoised datasets, whereas smoothing did not have a remarkable impact on the (semi)automated methods. TV variability was comparable to that of SUVMAX and SUVMEAN (range 14.7%–21.9% for %RMSE of %VARTEST-RETEST, after the exclusion of one outlier, 40%–43% when the outlier was included).Conclusions:
The TV variability obtained with the best methods was similar to the one reported for TV in previous [18F]FDG and [18F]FLT studies and to the one of SUVMAX/SUVMEAN on the authors’ [11C]choline dataset. The good reproducibility of [11C]choline TV warrants further studies to test whether TV could predict early response to treatment and survival, as for [18F]FDG, to complement/substitute the use of SUVMAX and SUVMEAN.
Physicists who are responsible for high-tech radiotherapy procedures should have to be specially credentialed39(2012); http://dx.doi.org/10.1118/1.4748333View Description Hide Description