Correlation between dose rate and T1 in blood at Gd-enhanced MR angiography.
OBJECTIVE
To determine the correlation between dose rate and T1 in blood at Gd-enhanced MR angiography (MRA).


METHODS
A test dose of contrast agent was used to calculate the time delay between injection and arrival in the abdominal aorta. The dose rate was expressed as ml.kg b.w.-1.s-1. The correlation between dose rate and T1 was determined by varying the dose rate while keeping the scanning and infusion times constant. The signal intensity in the abdominal aorta was measured during the first pass of Gd and compared with markers of known T1 values.


RESULTS
A correlation between dose rate and T1 in blood was obtained.


CONCLUSIONS
A Gd dose rate of 0.01 ml.kg b.w.-1.s-1 gives a T1 in blood of 100 ms. This can be used to calculate the optimal pulse sequence for contrast-enhanced MRA.
Department of Diagnostic Radiology, Uppsala University Hospital, Sweden.
L O
LO
Johansson
H K
HK
Ahlström
D001012:Aorta, Abdominal / Q000033:anatomy & histology* / Q000502:physiology; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000008:administration & dosage*; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement; D007275:Injections, Intravenous; D018810:Magnetic Resonance Angiography; D019047:Phantoms, Imaging; D011673:Pulsatile Flow / Q000502:physiology; D012016:Reference Values
D003287:Contrast Media; C064925:gadodiamide; D005682:Gadolinium; D019786:Gadolinium DTPA