OBJECTIVE: To quantify the test-retest repeatability of mean diffusivity (MD) and fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) tractography in a cohort of paediatric patients with localization-related epilepsy. METHODS: 30 patients underwent 2 DTI acquisitions [repetition time/echo time (ms), 7000/90; flip, 90°; b-value, 1000 s mm(-2); voxel (mm), 2 × 2 × 2]. Two observers used Diffusion Toolkit and TrackVis ( www.trackvis.org ) to segment and analyse the following tracts: corpus callosum, corticospinal tracts, arcuate fasciculi, inferior longitudinal fasciculi and inferior fronto-occipital fasciculi. Mean MD and mean FA were calculated for each tract. Each observer independently analysed one of the DTI data sets for every patient. RESULTS: Segmentation identified all tracts in all subjects, except the arcuate fasciculus. There was a highly consistent relationship between repeated observations of MD (r = 0.993; p < 0.0001) and FA (r = 0.990; p < 0.0001). For each tract, coefficients of variation ranged from 0.9% to 2.1% for MD and from 1.5% to 2.8% for FA. The 95% confidence limits (CLs) for change ranged from 2.8% to 6% for MD and from 4.3% to 8.6% for FA. For the arcuate fasciculus, Cohen's κ for agreement between the observers (identifiable vs not identifiable) was 1.0. CONCLUSION: We quantified the repeatability of two commonly utilized scalar metrics derived from DTI tractography. For an individual patient, changes greater than the repeatability coefficient or 95% CLs for change are unlikely to be related to variability in their measurement. ADVANCES IN KNOWLEDGE: Reproducibility of these metrics will aid in the design of future studies and might one day be used to guide management in patients with epilepsy.
OBJECTIVE: To quantify the test-retest repeatability of mean diffusivity (MD) and fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) tractography in a cohort of paediatric patients with localization-related epilepsy. METHODS: 30 patients underwent 2 DTI acquisitions [repetition time/echo time (ms), 7000/90; flip, 90°; b-value, 1000 s mm(-2); voxel (mm), 2 × 2 × 2]. Two observers used Diffusion Toolkit and TrackVis ( www.trackvis.org ) to segment and analyse the following tracts: corpus callosum, corticospinal tracts, arcuate fasciculi, inferior longitudinal fasciculi and inferior fronto-occipital fasciculi. Mean MD and mean FA were calculated for each tract. Each observer independently analysed one of the DTI data sets for every patient. RESULTS: Segmentation identified all tracts in all subjects, except the arcuate fasciculus. There was a highly consistent relationship between repeated observations of MD (r = 0.993; p < 0.0001) and FA (r = 0.990; p < 0.0001). For each tract, coefficients of variation ranged from 0.9% to 2.1% for MD and from 1.5% to 2.8% for FA. The 95% confidence limits (CLs) for change ranged from 2.8% to 6% for MD and from 4.3% to 8.6% for FA. For the arcuate fasciculus, Cohen's κ for agreement between the observers (identifiable vs not identifiable) was 1.0. CONCLUSION: We quantified the repeatability of two commonly utilized scalar metrics derived from DTI tractography. For an individual patient, changes greater than the repeatability coefficient or 95% CLs for change are unlikely to be related to variability in their measurement. ADVANCES IN KNOWLEDGE: Reproducibility of these metrics will aid in the design of future studies and might one day be used to guide management in patients with epilepsy.
Authors: Elias R Melhem; Susumu Mori; Govind Mukundan; Michael A Kraut; Martin G Pomper; Peter C M van Zijl Journal: AJR Am J Roentgenol Date: 2002-01 Impact factor: 3.959
Authors: T L Chenevert; L D Stegman; J M Taylor; P L Robertson; H S Greenberg; A Rehemtulla; B D Ross Journal: J Natl Cancer Inst Date: 2000-12-20 Impact factor: 13.506
Authors: Thomas Ptak; Robert L Sheridan; James T Rhea; Alice A Gervasini; Jong H Yun; Marjorie A Curran; Pierre Borszuk; Laurie Petrovick; Robert A Novelline Journal: AJR Am J Roentgenol Date: 2003-11 Impact factor: 3.959
Authors: Regula S Briellmann; L Anne Mitchell; Anthony B Waites; David F Abbott; Gaby S Pell; Michael M Saling; Graeme D Jackson Journal: Epilepsia Date: 2003-12 Impact factor: 5.864
Authors: O Ciccarelli; G J M Parker; A T Toosy; C A M Wheeler-Kingshott; G J Barker; P A Boulby; D H Miller; A J Thompson Journal: Neuroimage Date: 2003-02 Impact factor: 6.556