Diffuse Axonal Injury at Ultra-High Field MRI

Abstract

ObjectiveDiffuse axonal injury (DAI) is a specific type of traumatic brain injury caused by shearing forces leading to widespread tearing of axons and small vessels. Traumatic microbleeds (TMBs) are regarded as a radiological marker for DAI. This study aims to compare DAI-associated TMBs at 3 Tesla (T) and 7 T susceptibility weighted imaging (SWI) to evaluate possible diagnostic benefits of ultra-high field (UHF) MRI.Material and Methods10 study participants (4 male, 6 female, age range 20-74 years) with known DAI were included. All MR exams were performed with a 3 T MR system (Magnetom Skyra) and a 7 T MR research system (Magnetom 7 T, Siemens AG, Healthcare Sector, Erlangen, Germany) each in combination with a 32-channel-receive coil. The average time interval between trauma and imaging was 22 months. Location and count of TMBs were independently evaluated by two neuroradiologists on 3 T and 7 T SWI images with similar and additionally increased spatial resolution at 7 T. Inter- and intraobserver reliability was assessed using the interclass correlation coefficient (ICC). Count and diameter of TMB were evaluated with Wilcoxon signed rank test.ResultsSusceptibility weighted imaging revealed a total of 485 TMBs (range 1-190, median 25) at 3 T, 584 TMBs (plus 20%, range 1-262, median 30.5) at 7 T with similar spatial resolution, and 684 TMBs (plus 41%, range 1-288, median 39.5) at 7 T with 10-times higher spatial resolution. Hemorrhagic DAI appeared significantly larger at 7 T compared to 3 T (p = 0.005). Inter- and intraobserver correlation regarding the counted TMB was high and almost equal 3 T and 7 T.Conclusion7 T SWI improves the depiction of small hemorrhagic DAI compared to 3 T and may be supplementary to lower field strengths for diagnostic in inconclusive or medicolegal cases.

Susceptibility‐weighted imaging: current status and future directions

“…This differentiates CMBs from calcification, which is diamagnetic . It should also be noted that the detection of CMBs may also depend on the imaging parameters, such as field strength, TE and imaging resolution . Although the first two parameters determine the phase information and blooming effects, imaging resolution may affect the accuracy of CMB detection through partial volume effects .…”

Perspectives of Ultra-High-Field MRI in Neuroradiology

“…One study looked for cortical cerebral microinfarcts as a novel marker of coexistent vascular damage in intracranial hemorrhage (ICH). They found microinfarcts in 9 of 12 patients with spontaneous ICH, and in 5 of 15 controls indicating that microinfarcts are a very common vascular comorbidity in spontaneous ICH [21][22][23]. …”

Leitlinie „Begutachtung nach gedecktem Schädel-Hirntrauma im Erwachsenenalter“

“…Sie lassen sich von vorbestehenden Läsionen dadurch unterscheiden, dass siein einer MRT-Kontrolleeiner zeitlichen Dynamik unterliegen. Im chronischen Stadium lassen sie sich oft nur mit speziellen MR-Techniken als kleine Hämosiderinablagerungen (T2*, Scheid et al 2003) nachweisen, wobei die Sensitivität mit der MRT-Feldstärke steigt (Moenninghoff et al 2015). Bei potentiell entschädigungspflichtigen Verletzungen sollte daher in der Frühphase der Behandlung (in den ersten Tagen) eine MR-Bildgebung erhoben werden.…”