1. Interpretation of magnetic resonance imaging in the chronic phase of traumatic brain injury Jussi Laalo 1, Timo Kurki 2, Olli Tenovuo* 3 1 Department of Radiology, University of Turku, Finland, 2 Pulssi Imaging Center, Finland, 3 Department of Neurology, University of Turku, Finland *presenting author

2. Introduction MRI is the imaging method of choice in post- acute TBI or suspected TBI sequels Its findings may be of great importance for differential diagnosis, treatment decisions, outcome prediction, and medicolegal purposes

3. Introduction, continued We found no studies over the accuracy of consultant neuroradiologists’ head MRI reports - in many studies the report of one neuroradiologist has been the reference diagnosis. Regarding CT of acute TBI, we have recently shown that there is a marked variation even between the most experienced readers in the detection of brain injury findings ( Laalo J, Kurki T, Tenovuo O, Sonninen P. Reliability of diagnosis of traumatic brain injury by computed tomography in acute phase. Journal of Neurotrauma 2009;26:2169-78.)

4. Objectives To study eventual differences (in quantity and quality) in detecting the late stage TBI findings in MRI between two neuroradiologists and to compare these interpretations with the original report

5. Material and methods Randomly selected 89 cranial MRI- examinations from patients with clinically evident TBI and 11 non-TBI controls (scattered among TBI images, with blinded evaluation) Reviewed independently by two neuroradiologists: one with 14 years of experience within the subspecialty (R1), and another with recent completion of subspecialty training (R2)

6. Material and methods All examinations were performed on 1,5 T MR- scanners and included T2, gradient echo (T2*) and FLAIR sequences. Eventual other available sequences were also reviewed. The nature, location, and side of the finding was recorded. The classes used were: brain contusion, subdural effusion, and diffuse axonal injury (DAI). DAI included subclasses of spot-like haemorrhages, spot-like hyperintensities and localized atrophy. The readers also stated their view of DAI being evident, possible or absent.

7. Results R1R2Original Number of findings380259173 WM hyperintensities18213470 Contusions433523 Spot-like haemorrhages575752 Local atrophy983328 DAI evident/possible41*40*--- *Only 30 of these concerned same subjects

8. Strong Agreement Good Moderate Poor = R2 vs R1 = original vs R1

9. Results In the original report, the differences in interpretations were all directed towards false negative. These findings and locations were: Atrophy in both frontal lobes and the right temporal lobe Juxtacortical T2 hyperintensities in both frontal lobes T2 hyperintesities of deep WM in both frontal lobes and both parietal lobes and in the corpus callosum Contusion findings in both frontal lobes

10. Results There was consensus between the two neuroradiologists over whether DAI is present or not in 68/89 (76 %). In the control group 4/11 patients had findings, all of which were WM hyperintensities. A patient with 16 WM hyperintensities was reported by R2 as DAI being possible, all others were reported as DAI absent by both neuroradiologists.

11. Conclusions The interpretation of TBI findings in late-stage MRI is difficult, yielding significant variability also between specialists in neuroradiology. This may endanger correct diagnostics and lead to false treatment decisions and medicolegal problems. Detecting atrophy seems to be the most demanding task while interpreting images of chronic TBI.

12. Conclusions Standardized quantitative image analysis programs should be developed to be used in clinical practice. A visual interpretation of MRI images is too pendulous, puts the correct diagnostics in risk, and leaves the vast majority of the available imaging information unused.