title: True real-time cardiac MRI in free breathing without ECG synchronization using a novel sequence with radial k-space sampling and balanced SSFP contrast mode.
abstract: We investigated a novel sequence with radial k-space sampling, gridding and sliding window reconstruction with bSSFP contrast that allows for true real-time functional cardiac evaluation independent from respiration and ECG triggering. 12 healthy volunteers underwent 1.5 T cardiac MRI. Single-shot short axis views were acquired with a) standard retrospectively ECG-gated segmented breath-hold (bh) bSSFP and with the real-time radial bSSFP sequence with a nominal temporal resolution of b) 16 fps (frames per second) and c) 40 fps. Radial bSSFP were acquired during free breathing without ECG synchronization. Left ventricular functional parameters (EDV, ESV, SV and EF) were compared and quality of wall motion depiction was assessed. Contrast-to-noise-ratio (CNR) of myocardium/blood pool in the left ventricle was calculated. EF showed excellent correlation (Bland-Altman r = 0.99; Lin rho = 0.91) between bh-bSSFP (65%) and 40 fps radial (64%) and moderate correlation (r = 0.84, rho = 0.20) with 16 fps radial bSSFP (56%). While EDV was in good agreement for all three sequences, ESV was significantly overestimated with 16 fps radial bSSFP. Despite lower CNR, image quality for wall motion assessment was rated significantly better for 40 fps compared to 16 fps radial bSSFP due to the faster temporal resolution. Left ventricular functional analysis with fast true real-time radial bSSFP is in good agreement with standard ECG-gated bh-bSSFP. The independency from ECG synchronization and breathing promises a robust method for patients with impaired cardiopulmonary status in whom breath-hold and good quality ECG cannot be achieved.
authors: Department of Diagnostic and Interventional Radiology, Clinic of the Goethe University, Haus 23 C UG, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. ralfwbauer@aol.com
authors: Ralf W
authors: RW
authors: Bauer
authors: Isabel
authors: I
authors: Radtke
authors: Kai T
authors: KT
authors: Block
authors: Maya C
authors: MC
authors: Larson
authors: J Matthias
authors: JM
authors: Kerl
authors: Renate
authors: R
authors: Hammerstingl
authors: Thomas G
authors: TG
authors: Graf
authors: Thomas J
authors: TJ
authors: Vogl
authors: Shuo
authors: S
authors: Zhang
mesh_terms: D000328:Adult; D055424:Cardiac-Gated Imaging Techniques; D004562:Electrocardiography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012016:Reference Values; D012119:Respiration; D013318:Stroke Volume; D016277:Ventricular Function, Left; D055815:Young Adult