Comparative Magnetic Resonance Imaging at 1.5 and 3 Tesla for the Evaluation of Traumatic Microbleeds

Abstract

Traumatic microbleeds (TMBs) can be regarded as a radiological marker of diffuse axonal injury (DAI). We sought to investigate the impact of the field strengths on the depiction of TMBs by T2*-weighted gradient echo magnetic resonance imaging (MRI). By the use of comparative MRI of 14 patients (age range, 22-62 years) on 1.5- and a 3 T (Tesla) systems at a median time interval of 61 months after traumatic brain injury (TBI), we found 239 (range 0.5-48.5, median 7.5) TMBs at 1.5 T, and 470 (range 2-118, median 18.5) TMBs at 3 T, respectively (p=0.001). However, in all but one patients MRI at 1.5 T also clearly showed TMBs. A significant negative correlation between the number of TMBs and the time interval TBI-MRI was observed, which was weaker for the imaging at 3 T (r(s)=-0.798; p=0.001; and r(s)=-0.649; p=0.012, respectively). In conclusion, T2*-weighted gradient-echo MRI at 3 T is superior as compared to MRI at 1.5 T for the detection of TMBs. Nevertheless, in clinical practice, MRI at 1.5 T seems to be sufficient for this purpose. MRI at 3 T may be appropriate if there is a strong clinical suspicion of DAI, despite unremarkable routine MRI, and possibly also if evidence of DAI is sought after a long interval from trauma.

Silent cerebral microbleeds associated with arterial stiffness in an apparently healthy subject

“…[2][3][4] Using a custom three dimensional T2* sequence on a 1.5T MRI, which detects MBs with nearly two times the sensitivity of conventional two-dimensional T2* imaging; however, the Rotterdam study recently reported a much higher prevalence in the general population of 23.5%. 10 In the present study, using 3T MRI, which in turn has greater sensitivity than 1.5T MRI, 22 we observed a prevalence of 5% in our studied population free from a history of stroke. These differences in prevalence might be explained by differences in the clinical background of the study populations, particularly with regard to the ratio of hypertensive patients, which was 71.9% in the Rotterdam study compared with 56.2% in the present study.…”

New Appearance of Extraischemic Microbleeds on T2*-Weighted Magnetic Resonance Imaging 24 Hours After Tissue-type Plasminogen Activator Administration

“…If 3-T MRI, which is superior to the 1.5-T MRI that was used, had been performed, the frequency of new-EMBs might have increased. 41 Fourth, CT scans were not performed. It is questionable whether CT can detect new-EMBs after tPA infusion.…”

Common data elements in radiologic imaging of traumatic brain injury

“…Standard T2-weighted, T2 FLAIR, and T2*-weighted gradient-recalled echo (GRE) imaging methods often detect small lesions missed on CT. The sensitivity of these methods increases with increasing magnetic field strengths; for example, 3T T2* GRE detects twice as many tiny (several millimeter) parenchymal hemorrhages (sometimes referred to as ''microbleeds'' (9)) as at 1.5T (10). As good as these methods are, there are more advanced MRI methods, yet to be commonly practiced, that offer more sensitive measures of blood products (using susceptibility weighted imaging [SWI]), blood flow and perfusion (using perfusion weighted imaging [PWI]), microstructural white matter (WM) tract integrity (using diffusion tensor imaging), metabolic activity (using MR spectroscopy), and hemodynamic brain function (using fMRI).…”

“…SWI uses not only the magnitude component of the T2* data but also the phase information to enhance contrast and better reveal small hemorrhages. Generally imaging at higher fields such as 3T affords twice the sensitivity to blood products in comparison to 1.5T when using gradient echo imaging (10).…”