29) A T2 (*) gradient echo
sequence in the axial or coronal plane is necessary to evaluate for evidence of hemosiderin deposition related to prior trauma or cavernomas.
Incidentally noted was a small focus of brush-like enhancement in the right midbrain (Figures 1 and 2) with only subtle corresponding T2-signal abnormality and signal susceptibility on fast-field gradient echo
sequences (Figure 3).
To evaluate suspected inflammatory bowel disease, we add 3-plane SSTSE sequences and balanced gradient echo
and coronal T1 dynamic, 3D fat-suppressed gradient echo
sequences with and without gadolinium, using a neutral oral contrast.
To achieve this trilogy of goals, the pulse sequence utilizes a saturation recovery prepulse to tip the longitudinal magnetization by 90 degrees (to allow differences in T1 recovery times to manifest), followed by a low flip angle gradient echo
, and a single-shot read out.
3,4) Short echo time (TE) gradient echo
techniques have been successfully utilized as well.
CE MRV is probably the most widely used technique, and is essentially identical to 3-dimensional CE MRA, employing a 3-dimensional spoiled gradient echo
sequence in conjunction with a bolus of gadolinium-based contrast.
When evaluating the mediastinum, the protocol may include T1- and T2-weighted images (T1W and T2W) using fast spin echo (FSE) techniques, chemical shift imaging, pre- and post-contrast 2-dimensional and 3-dimensional gradient echo
techniques, parallel imaging with true fast spin imaging with balance steady state free precession (FISP), and dynamic multiphase 3-dimensional spoiled gradient echo
imaging (LAVA, FAME or VIBE) (22-23,26,27)
Three-dimensional gradient echo
(3D-GE) has been used extensively for MR angiography (MRA) and has evolved into a useful technique for body MRI.
Two different approaches to 3-dimensional imaging of the spine are gradient echo
(GRE)-based and fast spin echo (FSE)-based imaging.
22) Pulmonary nodules often show progressive retention of contrast, increasing their conspicuity on IP images, with fat-suppressed 3-dimensional gradient echo
being the preferred technique (23) (Figure 12).
The FSE sequence provides better resolution than gradient echo
and may be useful for detecting small structures, such as a normal appendix.
Suspected pancreatic cancer: Evaluation by dynamic gadolinium-enhanced 3D gradient echo