Magnetic Resonance Imaging (MRI) Practice Test

When utilizing MRI to assess for brain tumors, which type of weighted images are preferred after gadolinium injection to evaluate lesion extent?

1. T1 weighted

2. T2 weighted

3. FLAIR

4. DWI

The correct answer is: T1 weighted

After the injection of gadolinium in an MRI study to assess brain tumors, T1-weighted images are preferred for evaluating lesion extent. This preference stems from the ability of T1-weighted imaging to provide clear delineation between normal brain tissue and pathological lesions, such as tumors. Gadolinium enhances the contrast in T1-weighted images, making tumors appear brighter compared to surrounding tissues, which allows for a more accurate assessment of the tumor's size, shape, and relationship to adjacent structures. Additionally, T1-weighted images help in visualizing the effect of the tumor on surrounding brain anatomy, which is crucial for surgical planning and treatment. They are particularly effective for evaluating contrast-enhanced lesions, as malignant tumors typically have a higher degree of vascularity and will uptake gadolinium, resulting in well-defined imaging characteristics. Other imaging modalities like T2-weighted images are more sensitive for detecting edema and fluid, and FLAIR is effective in suppressing the fluid signal but may not be as definitive for assessing tumor margins. Diffusion-weighted imaging (DWI) is beneficial for characterizing cellularity but does not provide as clear a view of the lesion boundary as T1-weighted images do in the context of gadolinium-enh