Magnetic resonance imaging of the cranial nerves in the posterior fossa: a comparative study of t2-weighted spin-echo sequences at 1.5 and 3.0 tesla.
BACKGROUND
High-field magnetic resonance imaging (MRI) at 3.0 Tesla (T) is rapidly gaining clinical acceptance. Whether doubling of the field strength of 1.5T and the subsequent increase in signal-to-noise ratio (SNR) leads to a significant improvement of image quality is not automatically given.


OBJECTIVE
To evaluate the depiction of fine anatomic detail in the posterior fossa, focusing on brain nerves, on T2-weighted imaging, and to define the potential advantage of imaging at 3.0T versus 1.5T.


METHODS
In total, 10 brainstem nerve pairs of 12 volunteers were identified on T2-weighted MR images of 2- and 5-mm section thickness acquired at 1.5T and 3.0T. The MR images were compared for each subject at both field strengths by three independent readers who rated image quality according to depiction of anatomic detail and contrast by using a rating scale.


RESULTS
In general, MR images at 3.0T were considered more conspicuous and less noisy than images at 1.5T. The SNR value measured was almost doubled. With respect to structural identification and contrast according to the rating scale, observer scores were significantly improved both for standard imaging with 5-mm sections and high-resolution imaging with 2-mm sections at 3.0T. Direct comparison revealed a significant increase for evaluated image quality criteria and the number of nerves detected.


CONCLUSIONS
The comparison revealed a clear advantage in favor of T2-weighted MRI at 3.0T vs. 1.5T in depicting the roots and course of brain nerves in the posterior fossa.
Fischbach
F
F
Department of Radiology, Otto von Guericke University, Medical School, Magdeburg, Germany.
Müller
M
M
Bruhn
H
H
D000328:Adult; D001933:Brain Stem / Q000033:anatomy & histology; D003287:Contrast Media / Q000008:administration & dosage; D003391:Cranial Nerves / Q000033:anatomy & histology*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008280:Magnetics; D008297:Male; D015588:Observer Variation; D019047:Phantoms, Imaging; D012016:Reference Values
D003287:Contrast Media; D019786:Gadolinium DTPA