Comparison of 1.5 Tesla and 3.0 Tesla for Skull Base Lesion Enhancement

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FJ Londy, S Rohrer, S Kumar, H Parmar, SK Mukherji

Hong Kong J Radiol 2008;11:19-23

Aim: To determine whether there are significant differences between 3.0 Tesla and 1.5 Tesla in the degree of contrast enhancement of skull base lesions.

Patients and Methods: Fifteen consecutive patients with lesions involving the skull base who had undergone clinical magnetic resonance imaging on both 1.5 Tesla and 3.0 Tesla scanners were identified. Signal intensity and contrast-enhancement ratios were normalised to brain and measured for each abnormality at 1.5 Tesla and 3.0 Tesla. Statistical analysis consisted of paired Student t test. Additionally, a mathematical simulation of the influence of field strength on gadolinium enhancement was created.

Results: The average percent increase in lesion signal-enhancement ratio identified on the postcontrast enhanced T1-weighted image compared with the non-contrast T1-weighted image was 103% at 1.5 Tesla and 172% at 3.0 Tesla. The increased enhancement identified at 3.0 Tesla compared with 1.5 Tesla was statistically significant (p = 0.001). This result was predicted by the mathematical model.

Conclusions: Enhancement of skull base lesions is significantly greater at 3.0 Tesla than at 1.5 Tesla. The enhancement gain is consistent with the known increases in tissue T1 with increasing field strength. Using the selected T1-weighted acquisition settings at 1.5 Tesla and 3.0 Tesla, the impact of a given tissue gadolinium concentration has a predictable greater impact on signal-enhancement ratio at 3.0 Tesla relative to 1.5 Tesla.