T2 weighted three dimensional imaging of the whole heart
© Chung et al; licensee BioMed Central Ltd. 2009
Published: 28 January 2009
T2 weighted (T2w) dark blood turbo spin echo (DB-TSE)  is useful in myocardial tissue characterization such as acute myocarditis and acute myocardial infarction [2, 3]. 3D acquisitions can provide high resolution images of the whole heart, allowing arbitrary views of the organ, and reducing partial volume effect. Conventional 3D TSE improves SNR but not sampling efficiency or spatial resolution. We propose a novel TSE technique for T2w 3D imaging of the whole heart that provides higher spatial resolution and reduces scan time per slice compared to 2D DB-TSE.
To study the feasibility of a T2w 3D TSE technique for whole heart imaging with improved spatial resolution and imaging efficiency compared to 2D DB-TSE.
The sequence (aka T2w-SPACE) uses non-selective refocusing pulses  to reduce echo spacing and cardiac motion sensitivity. It supports constant (CFL) and variable flip angle (VFL) refocusing pulses. VFL uses longer echo train (ETL) than CFL while maintaining good T2 weighting . Optional motion sensitizing gradient (MSG) was implemented to suppress blood . Navigator gating was supported. The technique was evaluated on a 1.5 T scanner (MAGNETOM Avanto, Siemens, Germany).
T2w-SPACE was first optimized in 5 healthy volunteers (STIR contrast on two of them) using these parameters: inplane voxel = 1.6–1.8 mm isotropic, partition = 2.5–4 mm, 28–40 partitions, 2 averages, TR = 2 heartbeats, bandwidth/pixel = 840 Hz, 100% partition resolution. T2w-SPACE with MSG of 25 mT/m*ms (3 directions) was then compared with 2D DB-TSE in 4 other healthy volunteers using the optimal parameters. SAX views were used. In the comparison, common parameters for 2D and 3D acquisitions were: inplane resolution = 1.8 mm isotropic, fatsat, 100% phase resolution, parallel imaging rate 2 (24 reference lines), and navigator gating. 12 slices and 36 partitions (each 3.2 mm) were acquired by 2D DB-TSE and T2w-SPACE respectively. 2D specific parameters were: slice = 8 mm, ETL = 23, bandwidth/pixel = 300 Hz, echo spacing = 7 ms, TE = 56/76 ms.
Optimal imaging parameters for cardiac imaging with T2w-SPACE
Flip angle series
Echo train (ETL)
Slice turbo factor
Echo train duration
T2w-SPACE for whole heart imaging is feasible. It requires 2 and 3 excitations/partition for the VFL and CFL mode respectively and is two times more efficient than 2D DB-TSE, sparing time for improved slice/partition resolution. In reality, heart rate and navigator efficiency determine scan times in both cases. The technique would also be relevant to myocardial tissue characterization at 3 T and beyond.
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