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Last Updated: 4/9/2002
These cases are typically performed on pediatric patients
and are often run and read by the pediatric radiologist.
Patients will usually have an IV placed for sedation.
Typically double dose IV Gadolinium contrast (*)
is used to obtain the MRA
(2cc/10 lb instead of 1cc/10 lb) (0.1 – 0.2 mmol/kg Gd)
EKG leads
The protocol is variable, depending on the patient’s
history and the clinical question, and sequences are under body
coil or head coil (for small babies). The typical protocol is:
| Sequence |
Plane |
Comment |
Film # |
| DB Haste |
Ax, Cor |
Gated. |
2 |
| DB Haste |
Obl Sag |
Gated. |
2 |
| Cine GRE |
Obl Sag |
Gated. 10-20 slices; 4-6mm; Run
through the aorta. Repeat several times at slightly different angles
to maximize image quality.
Under WIP-cardiac function. TR 60; 23 beat (don’t use grid tagging)
# of phases usu 7-15 based on heart rate (TR * phases < RR interval)
Acq time 24-35 sec using 2 acquisitions. |
2
(film 1st image of each cine) |
| 3D FLASH |
Obl
Sag |
1 measure. Use 3D FLASH 2b488 {fl3d_itn_2b488ykc:
NOT qfs} (System #2) or ITN 2b488 (System #1)
Otherwise, 15-24 sec for aortic studies (allows better resolution).
Minimum FOV; actual effective thickness 1-2mm. |
0 |
| Timing Run |
Ax |
Thru region of interest.
Use 10% of the contrast dose up to 1cc and inject by power injector
at 2cc/sec(if IV and patient are large enough) followed by 10-20
cc saline at 2cc/sec or hand injection if patient and IV are too
small |
0 |
| 3D FLASH |
Obl
Sag |
2 measures with no gap. Contrast
at 2cc/sec with 20 cc saline flush or by hand if IV too small.
Use the standard timing formula. |
0 |
| Flow Quant |
Perpend-icular
to the aorta |
Typically 2-4 min – be sure patient
is well sedated or told not to move.
Choose VENC 500 sequence. Done as a through plane. Use a
level at the area of maximal signal loss on the oblique sagital
cine (for P=4v2).
DON’T PLACE IT: at the narrowest point
Alternatively, place above and at the diaphragm, to determine collateral
flow volumes rather than percent stenosis. |
0 |
| MIP |
|
Subtract if necessary. |
2 |
Gradient calculation:
- Found in the menu system under EVALUATE > FLOW
QUANT.
- Place a SMALL ROI circle at the area of greatest
signal loss (dephasing) and press GO.
- The gradient across the coarct is (mmHg) = 4 * [Peak
gradient (m/s)]2
(*) The use of gadolinium contrast material for these
applications represents off-label usage in the U.S. Outside the U.S.,
please consult your country's regulations for local guidelines.
NOTE: These protocols apply to Siemens
Symphony (with Quantum gradients) and Sonata systems. While they reflect
the protocols used at NYU Medical Center, NYU is not responsible for their
application elsewhere.
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