Bolus Chase Peripheral MRA
Start iv before entering magnet. First image the foot-ankle in the head coil using the 2D Gd bolus projection MRA with complex subtraction. This sequence will show the distal vessels in the ankles and feet and also can be used to predict the bolus timing for the 3D bolus chase. If there are foot ulcerations and concern about possible osteomyelitis then perform T1 spin echo with fat saturation in region of suspicion post gadolinium in all 3 planes. Then remove the head coil and perform the sagittal T1 of abdomen and pelvis with the table attached to the doghouse. This is an important locator for the post-gadolinium 3D phase contrast MRA of renal arteries. Then disconnect the table from the doghouse, position the patient for the 3D bolus chase, perform bolus chase localizers including axial 2D TOF for all stations. If the contrast travel time to the foot-ankle is 40 seconds or less then go straight to bolus chase using a delay determined by assuming it takes 2/3 of the time to the feet in order to fill the pelvis. If the contrast travel time to the ankle is greater than 40 seconds then perform a test bolus in the thigh to determine optimal timing for each station.
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Locator |
2D MRA
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Locator
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2D MRA |
Locator |
Scout |
Timing run |
renals |
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IMAGING PARAMETERS |
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Plane |
Sagittal |
Coronal |
Coronal |
Sagittal |
Sagittal |
Axial |
Coronal |
Coronal |
Axial |
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Mode |
2D |
2D |
2D |
2D |
2D |
2D |
2D |
3D |
3D |
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Pulse Seq |
Spin
Echo |
SPGR |
Spin
Echo |
SPGR |
Spin Echo |
SPGR |
SPGR |
SPGR |
Vasc PC |
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Imaging Options |
NPW |
Seq,
Fast, MPh, psd/yw/f2m |
NPW |
Seq,
Fast, MPh, psd/yw/f2m |
RC, NPW |
FC, Fast |
Seq, Fast, MPh psd/yw/f2 |
Fast, MPh psd/rw/efgre3D_vo |
FC |
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SCAN TIMING |
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# of Echoes |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
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TE |
Min Full |
Min |
Min Full |
Min |
Min Full |
Min Full |
Min |
Min |
Min |
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TR |
250 |
Min |
250 |
Min |
300 |
23 |
Min |
Min |
24 |
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Flip Angle |
-- |
70 |
-- |
70 |
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60 |
60 |
45 |
30 |
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Bandwidth |
-- |
16 |
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16 |
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16 |
16 |
32 (16-62) |
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ADDITIONAL PARAMETERS (see attached instructions) |
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SAT |
None |
None |
None |
None |
None |
None |
None |
None |
None |
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ACQUISITION TIMING |
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Freq |
256 |
256 |
256 |
256 |
256 |
256 |
256 |
256 |
256 |
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Phase |
160 |
192 |
160 |
192 |
192 |
160 |
256 |
160 |
192 |
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NEX |
1 |
1 |
1 |
1 |
2 |
1 |
1 |
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1 |
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Phase FOV |
1 |
.8 |
1 |
.8 |
1 |
.75 |
1 |
1 (.7-1) |
1 |
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Locs Before Pause |
0 |
0 |
0 |
0 |
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0 |
0 |
1 |
0 |
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Freq DIR |
S/I |
S/I |
S/I |
S/I |
S/I |
R/L |
S/I |
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R/L |
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Auto Center Freq |
Peak |
Water |
Water |
Water |
Peak |
Water |
Water |
Water |
water |
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Auto Shim |
On |
Off |
On |
Off |
On |
Off |
Off |
off |
On |
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Contrast |
No |
10 ml |
No |
10 ml |
No |
No |
5ml |
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SCANNING RANGE |
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FOV |
40 |
36 |
40 |
36 |
44 |
34 |
40 |
40 |
28 |
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Slice Thickness |
10 |
80 (60-120) |
6 |
80
(60-120) |
8 |
4 |
~100 |
3.6 (3-5) |
2.5 |
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Spacing |
Intleave |
15 (5-40) |
Intleave |
15 (5-40) |
Intleave |
16 |
1 |
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28 |
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Start - End |
L90-R99 |
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P65 – A45 |
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L84
– R84 |
S160-I160 |
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# Slices |
20 |
2 |
20 |
2 |
22 |
17 |
1 |
24 (20-40) |
28
(20-40) |
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Scan Time |
1:39 |
~1:30 |
1:39 |
~1:30 |
4:26 |
0:52 |
1:00 |
20-30 |
7:23 |
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ICD9 Codes: |
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Claudication |
440.21 |
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Rest pain |
440.22 |
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Non-healing foot ulcer |
440.23 |
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Post bypass graft |
414.04 |
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Aneurysm |
747.64 |
- First Ask:
1) Diabetes?
2) Aneurysm?
3) Heart disease or CHF?
4) Hypertension?
5) Non-healing ulceration? Location?______________
6) What are the symptoms?__________Which leg?___________
7) Ankle-brachial pressures available? Fax non-invasive labs to 752-8908.
8) Any bypass grafts?__________________________
9) How long can you hold your breath?____________
· Scheduling preferences: 60 minute slot - check Dr. Prince’s schedule to be sure he is in town
Monday: 7am to 10am or after 6pm
Tuesday - Thursday: schedule in late afternoon: up to 4 cases all after 4pm
Friday: 9am to 10am or after 6pm
· Ask patient to bring reports and films from any prior arteriograms:
· Light meal prior to MRA is acceptable
· If patient is claustrophobic request that referring physician prescribe valium (5-10 mg po) or Xanax (1-2 mg po) to be taken after arrival at imaging center about 20-30 minutes before beginning scan
· If patient cannot lie flat due to dependent rest pain then request medication for pain management during scanning
· Instruct patients scheduled into early morning slots on operation of door intercom system
- Change all clothes
- Start iv with heplock before entering scanner room, 20 gauge is preferable but 22 gauge is acceptable when using SmartSet. Be sure that all iv connections are tight so they do not pop apart or leak. When using the smartest, load 30 cc of saline flush in 30 cc syringe and use 10 cc to prime Smart Set and test iv. Save remaining 20 cc saline to use later for flushing Gadolinium through tubing. When using automatic injector, load 60 cc of saline into flush syringe.
- Mark any surgical scars, masses or areas of ulceration with Vitamin E capsule or MR compatible marker
Pre bolus
chase 2D projection MRA
Head coil: Place both lags in head coil to cover from just above the knees down to mid-calf. This will provide on optimal image of the trifurcation.
Landmark: on the middle of the coil
Head coil: position with a small cushion under knees; toes should be just at end of coil without sticking out the end. Gently bind feet together with curlex and pack foam in between and around feet to help prevent motion. Foam in between feet also prevents burns at sites of skin contact. Be extra careful to avoid irritating any foot ulcerations. Mark the location of any areas of ulceration or surgical scars with vitamin E capsules.
Landmark: on the middle of the coil
Series 1: Sagittal Locator
Series
2: Coronal
2D Projection MRA:
Series
3: Coronal
T1 of ankle-foot:
This series is ready to run. No adjustment necessary. Since it is an interleaved acquisition, images will be available half-way through the scan for setting up series 4. This scan is also useful in patients with non-healing ulcers for a rough screening of bone marrow to look for osteomyelitis. It can also help with positioning.
Series
4: Sagittal
2D projection MRA
- Set slab thickness to width of foot-ankle, typically 80-100mm (okay to be slightly narrower than the foot).
- Use “shift” to place one sagittal slab on each foot-ankle
- Prescribe on a slice near isocenter or posterior 10-20 mm
- It seems like it is always necessary to position more inferiorly than you think.
- Use sufficient phases so that total scan time is > 1 minute. If patient is older or expected to have really slow flow, make sure there are sufficient slices to image for at least 90 seconds.
- Inject 7-10 ml of Gadolinium:
1. by hand, inject as fast as possible with 20ml flush using smartest
2. by injector: 3.5 ml/sec followed with 25ml flush as 3.5ml/sec
3. always inject by hand if iv is in hand or if it is tenuous
- Reconstruction from remote terminal:
1. telnet
2. login: signa
3. password: adw2.0
4. cd /usr/g/mrraw
5. plist
6. lx2dsam
7. if uncertain about mask use image 5
8. usually there are 2 locations
- if telnet does not work use utilities: command window: cd /usr/g/mrraw
Optional
Abdominal T1 and localizer for renal 3D Phase Contrast MRA
Series 5: Sagittal T1 abdomen-pelvis:
- The purpose of this scan is to identify the renal artery origins and kidneys for localizing a 3D phase contrast MRA which is performed at the end of the bolus chase. It is also useful for screening the abdomen for any large masses or anomalies.
- Position patient supine, feet first in body coil
- Attach respiratory bellows for the respiratory compensation
- Landmark 2-3 fingers above umbilicus
- run the Sagittal T1
- make sure the table is attached to the doghouse for this scan
Bolus
Chase of abdomen to mid-calf
Body coil: position with cushions under knees and ankles so that legs are perfectly horizontal. This will enable a relatively small 3D volume with a limited number of slices to cover the arterial anatomy in pelvis thigh and calf without having to download new sequences for every station. Make sure feet are bound together with curlex and use a Velcro strap over knee and thighs to hold legs down to help minimize motion. Be extra careful to avoid irritating any foot ulcerations.
Landmark: do not change the landmark. Keep the same landmark as for series 3. If the patient is re-landmarked than it will be necessary to repeat series 3 with the new landmark.
Cushions under ankles and knees to keep legs perfectly horizontal
Series 6: Axial time-of-flight
localizer
- Add cushions under knees and ankles to make level with abdominal aorta
- Strap feet together with curlex using foam in between feet to prevent them from touching. Be careful with patients who have foot ulcers.
- Place wide strap over knees to help patient hold legs still during bolus chase
Disconnect
table from doghouse and place 5 cm wide board over doghouse latch- Advance to scan. Manually advance table all the way until it abuts the 5cm board on doghouse latch
- Place positioning boards on table
- First board = 30-32 cm. Make the first board small to overlap common femoral bifurcations on both first and second stations.
- Second board =36 cm (32-40 cm)
- Third board = 15-30 cm depending upon patient height: usually 15 cm. Note if second board is long then a third board may be unnecessary