3D Steady-state Free Precession Imaging Research Articles

Insights gained from three-dimensional imaging modalities for closure of ventricular septal defects.

Ventricular septal defects (VSDs) are the commonest group of congenital heart lesions, accounting for ≈30% of congenital heart defects in liveborn infants.1 Defects in the ventricular septum are classified according to their position when the ventricular septum is viewed from the right ventricle and these may vary in their location, size, and number.2,3 VSDs can occur as isolated lesions or as part of more complex disease, for example, transposition of the great arteries or double outlet right ventricle, where the location and size of such defects assume great importance in planning the optimal mode of surgical repair.4 In most cases, surgical closure remains the mainstay treatment for VSDs, but selected lesions may be amenable to catheter closure.5,6 Cross-sectional echocardiography is the most commonly used noninvasive diagnostic method to delineate the position of a VSD before surgery.7 Multiple sonographic cuts and cross-sectional sweeps of the region of interest are used to build a virtual reconstruction of the three-dimensional (3D) anatomy in the mind of the echocardiographer. However, for the surgeon who deals solely with 3D images there can remain an element of uncertainty when called to operate on the patient. The number, size, location of VSDs, and their relationship to adjacent structures are central for selecting whether the defects might be best closed via the tricuspid valve, via the semilunar valves, or via a ventriculotomy or whether these might not be readily approachable and a palliative pulmonary artery banding is desirable.8,9 In this review, we present key 3D echocardiographic projections and examples of different types of VSDs where the images have a direct effect on the approach taken to VSD closure. Comparison of 3D echocardiography (3DE) with other 3D imaging modalities is also described. Images are presented in an …

Three-dimensional flow-independent balanced steady-state free precession vessel wall MRI of the popliteal artery: Preliminary experience and comparison with flow-dependent black-blood techniques

To examine the feasibility of flow-independent T2-prepared inversion recovery (T2IR) black-blood (BB) magnetization preparation for three-dimensional (3D) balanced steady-state free precession (SSFP) vessel wall MRI of the popliteal artery, and to evaluate its performance relative to flow-dependent double inversion recovery (DIR), spatial presaturation (SPSAT), and motion-sensitizing magnetization preparation (MSPREP) BB techniques in healthy volunteers. Eleven subjects underwent 3D MRI at 1.5 Tesla with four techniques performed in a randomized order. Wall and lumen signal-to-noise ratio (SNR), wall-to-lumen contrast-to-noise ratio (CNR), vessel wall area, and lumen area were measured at proximal, middle, and distal locations of the imaged popliteal artery. Image quality scores based on wall visualization and degree of intraluminal artifacts were also obtained. In the proximal region, DIR and SPSAT had higher wall SNR and wall-to-lumen CNR than both MSPREP and T2IR. In the middle and distal regions, DIR and SPSAT failed to provide effective blood suppression, whereas MSPREP and T2IR provided adequate black blood contrast with comparable wall-to-lumen CNR and image quality. The feasibility of 3D SSFP imaging of the popliteal vessel wall using flow-independent T2IR was demonstrated with effective blood suppression and good vessel wall visualization. Although DIR and SPSAT are effective for thin slab imaging, MSPREP and T2IR are better suited for 3D thick slab imaging.

Free-breathing renal MR angiography with steady-state free-precession (SSFP) and slab-selective spin inversion: Initial results

The aim of our study was the investigation of a novel navigator-gated three-dimensional (3D) steady-state free-precession (SSFP) sequence for free-breathing renal magnetic resonance angiography (MRA) without contrast medium, and to examine the advantage of an additional inversion prepulse for improved contrast. Eight healthy volunteers (mean age 29 years) and eight patients (mean age 53 years) were investigated on a 1.5 Tesla MR system (ACS-NT, Philips, Best, The Netherlands). Renal MRA was performed using three navigator-gated free-breathing cardiac-triggered 3D SSFP sequences [repetition time (TR) = 4.4 ms, echo time (TE) = 2.2 ms, flip angle 85 degrees, spatial resolution 1.25 x 1.25 x 4.0 mm(3), scanning time approximately 1 minute 30 seconds]. The same sequence was performed without magnetization preparation, with a non-slab selective and a slab-selective inversion prepulse. Signal-to-noise ratio (SNR), contrast-to-noise (CNR) vessel length, and subjective image quality were compared. Three-dimensional SSFP imaging combined with a slab-selective inversion prepulse enabled selective and high contrast visualization of the renal arteries, including the more distal branches. Standard SSFP imaging without magnetization preparation demonstrated overlay by veins and renal parenchyma. A non-slab-selective prepulse abolished vessel visualization. CNR in SSFP with slab-selective inversion was 43.6 versus 10.6 (SSFP without magnetization preparation) and 0.4 (SSFP with non-slab-selective inversion), P < 0.008. Navigator-gated free-breathing cardiac-triggered 3D SSFP imaging combined with a slab-selective inversion prepulse is a novel, fast renal MRA technique without the need for contrast media.

Effects of view ordering and dummy pulse rate on two-dimensional and three-dimensional steady-state free precession imaging 1

Rationale and Objective. To assess the effects of view ordering and dummy pulse rate on the image quality of steady-state free precession (SSFP) imaging. Material and Methods. Two- and three-dimensional (2D and 3D) SSFP imaging with various view orderings (eg, centric, sequential, reverse centric) and dummy pulse rates were performed in the phantom including several concentrations of gadolinium and patients. Results. Centric view orderings increased the noise in 3D SSFP images in the phantom. In the patients studied, the centric view ordering increased the signals obtained from abdominal organs in 2D and 3D SSFP and the background signal in 3D images, without changing the vascular signals. An increased dummy pulse rate reduced the background signal in 2D SSFP, but not in 3D SSFP. Conclusion. Sequential ordering is recommended for both 2D and 3D SSFP, and centric view ordering combined with an increase in dummy pulse rate can be used for 2D imaging.

Rapid MR imaging of articular cartilage with steady-state free precession and multipoint fat-water separation.

To obtain high-quality high-resolution images of articular cartilage with reduced imaging time, we combined a novel technique of generalized multipoint fat-water separation with three-dimensional (3D) steady-state free precession (SSFP) imaging. The cartilage of 10 knees in five healthy volunteers was imaged with 3D SSFP imaging and a multipoint fat-water separation method capable of separating fat and water with short TE increments. Fat-saturated 3D spoiled gradient-echo (SPGR) images were obtained for comparison. High-quality images of the knee with excellent fat-water separation were obtained with 3D SSFP imaging. Total imaging time required was 58% less than that required for 3D SPGR imaging with a comparable cartilage signal-to-noise ratio and spatial resolution. Unlike 3D SPGR images, 3D SSFP images exhibited bright synovial fluid, providing a potential arthrographic effect. High-quality high-resolution images of articular cartilage with improved fat-water separation, bright synovial fluid, and markedly reduced acquisition times can be obtained with 3D SSFP imaging combined with a fat-water separation technique.