Sagittal T2-weighted Images

Chapter 8: The Knee

8.2.4 - Sagittal T2-weighted Images

The sagittal T2-weighted images (Fig. 8.3) are prescribed to match the proton density images in slice thickness and location. These images provide improved visualization of the cartilage surfaces outlined by joint fluid.

Figure 8.3 (click on image to see enlarged view) Sagittal T2-weighted image showing a large joint effusion (arrow).

Timing
Parameters
Series 3
Sagittal
T2 FSE-XL FS
TR/TE
4000/72
ETL
8
Flip Angle
—
RBW
21 kHz
FOV
16 cm
Matrix
256 x 192
Slice Thickness
3mm
Interslice Gap
1mm
NEX
2
Acquisition Time
3:12
Fat Sat
yes
No Phase Wrap
yes
EDR
no
Freq
A/P

Automated shimming combined with imaging at isocenter usually results in excellent fat suppression and visualization of marrow edema. Fluid in the cruciate ligaments and extensor mechanism is easily detected. Because of the use of the Improved Fat SAT available on the LX 8.2.5 platform, with the T2-weighted images in the sagittal and coronal planes, the effective TE can be lowered to about 60 ms. Note that these images are predominantly used for high sensitivity detection of bone edema, therefore are obtained at lower resolution than the sagittal proton density images. With a high SNR coil, 512 matrix images are also feasible.