Vascular Imaging Clinical Protocols: Symphony System Moving Table Runoff

The peripheral coil and the spine elements (SP1-Sp6) are fixed in position on the table. The phased array coil is positioned adjacent to the peripheral coil, over the abdomen.

If a full runoff to the toes is desired, TOF images through the feet can be performed in the dedicated peripheral coil. However, in most patients, the small vessels of the feet can be imaged with gadolinium and TOF imaging isn’t necessary.
If TOF imaging is necessary center on the feet and run a single package of TOF sequence (128 slices 2-3mm with 30% overlap; gated, ideally). This typically takes about 10 minutes and will image into the ankle.

Subsequently, a single injection, 3-station table move acquisition is performed to image the arterial system from the renal arteries to the ankle/toes.

Depending on the patient’s stature, the kidneys may or may not be covered by the spine element, SP6, posteriorly and the phased array coil anteriorly. If they are, these coils may be used during station 1 image acquisition. Otherwise, the body coil must be used for station 1.

Currently, 2 protocols are setup on the system for a single injection runoff:
Peripheral angio > Claudication > 3 station table move - Short
Peripheral angio > Claudication > 3 station table move - Tall

These protocols cover approximately 900 and 1200mm respectively. The “short” protocol moves the table 300mm between each station and incorporates 100mm of overlap between stations. The “tall” protocol moves the table 400mm between each station and incorporates 50mm of overlap between stations. In general, even patients of average height are better imaged with the “tall” protocol. A small error margin is incorporated in the proximal overlap section at the top of the FOV.

However, by measuring up from the distal point of the FOV (typically midfoot – ankle which allows more distal coverage in the distal overlap section) a distance of 900 or 1200mm the coverage can be estimated. In order to center the patient, simply measure up 750mm from the distal point of the FOV for the “short” protocol or 1000mm from the distal point of the FOV for the “tall” protocol. This will ensure that the last station includes the feet (or whatever you choose to be the distal point).

When planning the 3D slab in each station, the minimum slab thickness should be used (angle the slab to help you). Ideally you want the acquisition time of the first station to be approximately 10 seconds and the acquisition time of the second station to be approximately 14 seconds. This should allow 1.5mm effective thickness. The short acquisition times allows you to chase the bolus down the legs with minimized venous contamination.

For the third station, again the slab should be minimized, but the desired effective thickness is about 1-1.2mm. In this station elliptical, centric k-space filling is used. This allows for a longer acquisition (needed for the higher resolution) without significant venous contamination in patients with relatively normal perfusion. Two acquisitions are performed in order to capture the arterial phase in patients with significantly delayed distal transit time.

As seen in the protocol below, after a general scout is performed, the timing run is performed at the level of the femoral heads (2cc of contrast are used). Then, a 3-plane scout is obtained at each of the 3 table positions/stations. At each of the 3 locations, in turn, a pre-contrast acquisition is planned (slab sized and positioned, coils selected, etc.) and run. Then, during contrast injection, the 3 pre-contrast scans are re-run sequentially. A 2-phase injection seems to work well; 25cc of the contrast mixture at 2cc/sec, followed by 35cc of the mixture at 1cc/sec then 20cc flush at 2cc/sec.

The timing run is typically performed at the level of the femoral heads in order to assess the proximal transit time. Since this value represents the time to the distal point of the first station, you can use the time to peak as the scan delay, even with a short first station acquisition time.

(*) 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.