Effect of contrast dose and field strength in the magnetic resonance detection of brain metastases.
OBJECTIVE
To compare the diagnostic efficacy of a standard and cumulative triple dose of magnetic resonance (MR) imaging contrast agent in the evaluation of brain metastases using a high-field 3.0 T MR unit versus a standard field 1.5 T MR unit.


METHODS
Twenty-two patients with suspected brain metastases were examined at both field strengths using identical postcontrast coronal 3D gradient echo with magnetization preparation, which was adjusted separately for each field strength. In both groups initially, iv injection of 0.1 mmol/kg body weight gadolinium chelate (gadodiamide) and thereafter, 0.2 mmol/kg body weight gadodiamide were administered. Subjective assessment of the images was performed independently by 3 neuroradiologists. Objective measurement of signal-to-noise and contrast-to-noise ratios was obtained.


RESULTS
The subjective assessment of cumulative triple-dose 3.0 T images obtained the best results compared with other sequences, detecting 84 metastases, followed by 1.5 T cumulative triple-dose enhanced images with 81 brain metastases. The objective assessment confirmed those results, showing significantly higher signal-to-noise and contrast-to-noise ratios with 3.0 T than with 1.5 T.


CONCLUSIONS
Cumulative triple-dose images of both field strengths were superior to standard field strengths. However, administration of gadodiamide contrast agent produces higher contrast between tumor and normal brain on 3.0 T than on 1.5 T, resulting in better detection of brain metastases and leptomeningeal involvement.
Ba-Ssalamah
Ahmed
A
Department of Radiology, University of Vienna, A-1090 Vienna, Austria. ahmed.ba-ssalamah@univie.ac.at
Nöbauer-Huhmann
Iris M
IM
Pinker
Katja
K
Schibany
Nadja
N
Prokesch
Rupert
R
Mehrain
Sheida
S
Mlynárik
Vladimir
V
Fog
Amura
A
Heimberger
Karl
K
Trattnig
Siegfried
S
D000368:Aged; D001932:Brain Neoplasms / Q000556:secondary*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA