SPHP

Respiratory motion severely degrades images, especially 3D sequences like VIBE

Even single shot sequences like HASTE are degraded due to "bouncing" (if MBH)

BEFORE the patient is in the scanner:

• Practice with the patient to see how long they can adequately hold their breath, and note this time
  
• Stress the importance of consistent breath holds - patient's don't know this until you stress it

 patient is in the scanner:

AFTER the patient is in the scanner:

• Give consistent instructions
  
• Watch the patient's chest! Start scan when the chest is still.
• Decrease abdominal wall motion artifact by swtiching the phase encoding direction to L-R (especially important for non breath hold high res T2 images i.e. pelvic MR)

Pre- and postcontrast VIBEs are the most important images

Remember: 

Scan time is proprtional to  (PE steps x NEX x TR) / (PIF x ETL)

NEX = number of excitations

TR = repetition time

PIF = parallel imaging factor

ETL = echo train length

To shorten the length of a VIBE sequence, decreased the number of PHASE ENCODING steps:

1. Increase slice thickness (intervals of 0.5 mm) and decrease the # of slices. 

• Fewer, thicker slices 
• Significantly decreased through plane resolution
• Best to use if a large decrease in breath hold time is needed. 
  

2. Increase FOV and decrease the phase FOV to fit the patient's anatomy. 

• Easiest method to decrease scan time. 
• Decreased in-plane resolution. 
• Best to use if only a small decrease in breath hold time is needed. 
  

3. Decrease the phase resolution. (resolution tab). 

• Decreases matrix size in the phase direction and decreases breath hold time. 
• Slightly decreased in plane resolution. 
• Best to use if only a small decrease in breath hold time is needed.
  

• Lowers matrix size in both phase and frequency directions and decrease breath hold time. 
• Significantly decreased in-plane resolution. 
• Best to use if a substantial decrease in breath hold time is needed.