Improved functional cardiac MR imaging using the intravascular contrast agent CLARISCAN.
OBJECTIVE
Using segmented k-space turbo gradient echo MR techniques (TGE) contrast between blood and myocardium is often reduced in long axis views due to reduced in plane spin-refreshment, particularly in patients with low ejection fraction. The application of an intravascular contrast agent (CA) may improve endocardial border delineation.


METHODS
In 15 patients cardiac cine loops in two long axis and two short axis views were acquired during breath hold using a TGE sequence without and with increasing doses of CA (0.75, 2.0, 5.0 mg Fe/kg). Two independent observers evaluated left ventricular function (LVEF, modified Simpson's rule) and assigned a visual score (range: 0 = 'not visualized' to 6 = 'excellent visualization') for endocardial border delineation. Signal- and contrast-to-noise ratios (SNR; CNR) were determined.


RESULTS
Endocardial border delineation score for TGE was 1.7 +/- 0.6 and 3.9 +/- 0.6**, 4.4 +/- 0.5**, 4.6 +/- 0.4** for 0.75, 2.0, 5.0 mg Fe/kg of CA, respectively (**p < 0.01 vs. TGE). SNR of blood increased significantly with any dose of CA with a mild drop of myocardial SNR resulting in a significant increase of CNR blood/myocardium. The maximum effect with 2.0 mg Fe/kg was a >2-fold CNR increase. Inter- and intraobserver variability assessed according to the method of Bland-Altmann was reduced at 2.0 mg Fe/kg for determination of LVEF and reached statistical significance for LVEF <50%.


CONCLUSIONS
Intravascular CA increased CNR between blood and myocardium by a factor >2 and significantly improved the determination of cardiac volumes. The benefit in accuracy was most for patients with left ventricular ejection fraction <50%.
Clinic of Internal Medicine/Cardiology, German Heart Institute, Humboldt University, Berlin, Germany.
I
I
Paetsch
H
H
Thiele
B
B
Schnackenburg
A
A
Bornstedt
A
A
Müller-York
J
J
Schwab
E
E
Fleck
E
E
Nagel
D000368:Aged; D003287:Contrast Media; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007501:Iron; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010087:Oxides; D016277:Ventricular Function, Left
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide