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- Open Access
Time-resolved spin-labeled balanced SSFP cineangiography of the heart: a novel approach for visualizing intracardiac shunt
© Mordini et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Present methods for intracardiac shunt evaluation have important technical limitations. For example, phase contrast imaging (PC) is sensitive to velocity encoding setting and angle of imaging plane. PC can also be difficult to interpret due to complex flow patterns and separation of morphologic from velocity images. Cine GRE sequences that involve saturation of inflowing blood have poor SNR. Methods requiring gadolinium have limited use within a single exam and in patients with renal insufficiency. A method that circumvents these technical limitations in shunt visualization is desirable.
We sought to develop a time-resolved spin-labeled technique (TRSL) to image tagged blood within the heart for visualization of intracardiac shunt.
Background signal was suppressed with a non-selective inversion radiofrequency pulse. Slice-selective inversion slabs were applied immediately thereafter to remagnetize the labeled blood pool. Remagnetized blood within the heart was visualized using an ECG gated, segmented, bSSFP readout at sequential inversion times. General parameters were FOV 340, matrix 128 × 100, slice thickness 6-8 mm, TR 46 ms, TE 1.3 ms, 30-40 phases reconstructed, breathhold time 12-14 seconds. The sequence was implemented on a 1.5 T Siemens Avanto scanner.
Six subjects with known atrial septal defects (ASD) were evaluated. Inversion slabs were prescribed in the pulmonary veins to tag left atrial blood and in the inferior/superior vena cava to tag right atrial blood.
TRSL is a non-contrast, non-velocity dependent, non-subtractive method for visualizing RF-tagged blood flowing through cardiac chambers.
The method successfully demonstrated left-to-right and right-to-left intracardiac shunting.
TRSL has potential use in the detection and pre-procedural assessment of intracardiac shunt.
Application in small shunts, valvular disease, and perfusion has yet to be evaluated.
This article is published under license to BioMed Central Ltd.