(PD-weighted, T1-weighted)¶
INCORRECT ANSWER¶
The correct answer was: (T1-weighted, T2-weighted)
| Proton density weighted | T1 weighted | T2 weighted | |
|---|---|---|---|
| Echo Time (TE) | Medium | Short | Long |
| Repetition time (TR) | Medium | Short | Long |
T1-weighted images are optimized for greater T1 contrast between tissues-of-interest, while T2-weighted images are optimized for greater T2 contrast between tissues-of-interest.
Revisiting Figure 2.8 and Figure 3.3, can you explain out why the T1w parameters were chosen to be [TR = 1 s, TE = 15 ms] and not [TR = 5s, TE = 150 ms]? Why was T2w protocol parameters [TR = 5s, TE = 150 ms] instead of [TR = 1 s, TE = 15 ms]?
A common trick is to remember that white-matter is white in T1-weighted images, and water is bright in T2-weighted images. Here are those images again:
Return to Case Study¶
The radiologist expresses concern that the standard T2-weighted image does not provide sufficient contrast to clearly identify periventricular lesions, which are a hallmark of MS. Given that these lesions are expected to consist of inflamed axon fibers with higher water content, the radiologist asks for your help in designing an imaging protocol that can better differentiate between the hyperintense CSF in the ventricles and the hyperintense periventricular lesions.
Look at Figure 7.2, can you easily identify these lesions?
From the information provided above, how do you think the T1 and T2 values will differ in a lesions vs normal white matter?
A - (T1 increased, T2 decreases)
B - (T1 decreases, T2 increases)