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Myocardial Perfusion
• Many limitations:
– Motion. Synchronization with ECG. Breath-hold.
– Must be done in stress conditions. High HR. Increase of motion. need to increase
acquisition time. Systolic phase.
– Synchronization with ECG seriously limits sampling time.
– If a big coverage (16 cm) is not available, the shuttle mode must be used:
sampling time further reduced by half.
– BF is really fast in the myocardium (~ 300 mL / min
100 mL). Normally such
values cannot easily be obtained with such low temporal sampling (~3 to 4 s),
thus some models derived from Tofts are normally employed to calculate PS and
backflow, capillaries volume etc. BF is then calculated with MS models.
– Backflow occurs very quickly, so models assuming no backflow (like Patlak) are
not suitable to this application.
– Beam hardening artifacts in myocardium (limitation on how low the kV can be
set).