1. NINA BRANDSTACK 26.06.2013 QUANTITATIVE DIFFUSION TENSOR TRACTOGRAPHY OF LONG ASSOCIATION TRACTS IN PATIENTS WITH TRAUMATIC BRAIN INJURY WITHOUT FINDINGS IN ROUTINE MRI BRANDSTACK NINA, KURKI TIMO, AND TENOVUO OLLI. RADIOLOGY APRIL 2013 267:1 231-239 Quantitative Diffusion-Tensor Tractography Can Detect Posttraumatic Abnormalities That Are Not Depicted at Conventional MR

2. Conventional MRI Superior to CT in the detection of intraparenchymal traumatic lesions Often normal even in TBI cases with persistent symptoms True injury/ other disorder? -> Treatment Medicolegal consequences

3. Our study: Materials and methods 106 consecutive (from July 2008 to December 2011) clinical subjects with TBI without abnormalities on routine MRI (age 16-56 years) 62 demographically- matched control subjects DTI at 3T (Achieva; Philips Medical Systems, Best, the Netherlands) was performed (number of excitations 2, 15 gradient encoding directions) Deterministic DTT (FiberTrak package, Philips Medical Systems) was performed by using an FA threshold of 0.15 and a turning angle threshold of 27° to terminate the tracking process The tracts were defined with 2-3 free hand inclusion ROIs and 1-4 exclusion ROIs

4. Materials and methods Volume, ADC and FA of the SLF, IFOF, UF, SC, TC, AF, and ILF were measured Statistical analyses were based on repeated-measures ANCOVA Sex, age, time between injury and imaging, trauma mechanism and severity of TBI were considered as covariates for the tests

5. Results In controls, tract volumes showed large variability while FA and ADC values showed small variability In several tracts, mean FA values correlated negatively with the respective volumes In subjects with TBI, FA values were reduced in both UFs, both IFOFs, and in the right ILF compared with controls (p<0.05) Diffusivity was increased in half of the tracts The tract volumes were not significantly reduced

6. Reproducibility ICC, Bland-Altman reliability analysis FA/ turning angle threshold: 0.15/60° (light blue),0.15/27° (blue), 0.30/27° (green) Volume-based FA and ADC analysis in the central part of the tract with two pretermined sizes: 3cm³ (purple), 1cm³ (red)

7. Reproducibility -results For the tract-based methods, intra-rater and inter-rater reliabilities of FA and ADC measurements were excellent. Between-scan reproducibility was good or excellent in 127/130 of the measurements. In our study with relatively few subjects (n=10), neither the turning angle threshold (27°/60°) nor FA threshold (0.15/0.30) had a systematic influence on reproducibility

8. Conclusions QDTT is able to show posttraumatic FA and ADC abnormalities in subjects with normal routine MRI in several association tracts, most commonly in the UF The tract-based FA and ADC measurements are highly reproducible The large variability of normal tract volumes and the dependence of mean FA values on volume can decrease the accuracy of the method

9. Thank You