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

OBJECTIVE: 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. SUBJECTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

Non-contrast-enhanced MR angiography of the thoracic aorta using cardiac and navigator-gated magnetization-prepared three-dimensional steady-state free precession

PURPOSE: To assess the usefulness of non-contrast-enhanced MR angiography using cardiac and navigator-gated magnetization-prepared three-dimensional (3D) steady-state free precession (SSFP) imaging for the diagnosis of diseases of the thoracic aorta. MATERIALS AND METHODS: Twenty-two patients with diseases of the thoracic aorta were examined using a 1.5 Tesla unit. Non-contrast-enhanced MR angiography was done using parasagittal 3D SSFP combined with cardiac-gating and k-space weighted navigator-gating techniques, using T2-prepared and fat-suppression pulses. Imaging quality and the diagnostic capability of this technique were compared with the imaging quality of 2D SSFP or contrast-enhanced 3D MR angiography and with final diagnoses. RESULTS: Non-contrast-enhanced 3D MR angiography provided signal-to-noise and contrast-to-noise ratios of the thoracic aorta comparable to non-contrast-enhanced 2D or contrast-enhanced 3D MR angiography (P > 0.17). This imaging technique gave accurate diagnoses in 19 of the 22 patients. CONCLUSION: Non-contrast-enhanced MR angiography using cardiac and navigator-gated magnetization-prepared 3D SSFP technique was useful for the diagnosis of diseases of the thoracic aorta.     

Application of refocused steady-state free-precession methods at 1.5 and 3 T to in vivo high-resolution MRI of trabecular bone: simulations and experiments

PURPOSE: To evaluate the potential of fully-balanced steady-state free-precession (SSFP) sequences in in vivo high-resolution (HR) MRI of trabecular bone at field strengths of 1.5 and 3 T by simulation and experimental methods. MATERIALS AND METHODS: Using simulation studies, refocused SSFP acquisition was optimized for our imaging purposes with a focus on signal-to-noise ratio (SNR) and SNR efficiency. The signal behavior in trabecular bone was estimated using a magnetostatic model of the trabecular bone and marrow. Eight normal volunteers were imaged at the proximal femur, calcaneus, and the distal tibia on a GE Signa scanner at 1.5 and at 3 T with an optimized single-acquisition SSFP sequence (three-dimensional FIESTA) and an optimized multiple-acquisition SSFP sequence (three-dimensional FIESTA-c). Images were also acquired with a fast gradient echo (FGRE) sequence for evaluation of the SNR performance of SSFP methods. RESULTS: Refocused SSFP images outperformed FGRE acquisitions in both SNR and SNR efficiency at both field strengths. At 3 T, susceptibility effects were visible in FIESTA and FGRE images and much reduced in FIESTA-c images. The magnitude of SNR boost at 3 T was closely predicted by simulations. CONCLUSION: Single-acquisition SSFP (at 1.5 T) and multiple-acquisition SSFP (at 3 T) hold great potential for HR-MRI of trabecular bone.     

4D radial coronary artery imaging within a single breath-hold: cine angiography with phase-sensitive fat suppression (CAPS).

Coronary artery data acquisition with steady-state free precession (SSFP) is typically performed in a single frame in mid-diastole with a spectrally selective pulse to suppress epicardial fat signal. Data are acquired while the signal approaches steady state, which may lead to artifacts from the SSFP transient response. To avoid sensitivity to cardiac motion, an accurate trigger delay and data acquisition window must be determined. Cine data acquisition is an alternative approach for resolving these limitations. However, it is challenging to use conventional fat saturation with cine imaging because it interrupts the steady-state condition. The purpose of this study was to develop a 4D coronary artery imaging technique, termed "cine angiography with phase-sensitive fat suppression" (CAPS), that would result in high temporal and spatial resolution simultaneously. A 3D radial stacked k-space was acquired over the entire cardiac cycle and then interleaved with a sliding window. Sensitivity-encoded (SENSE) reconstruction with rescaling was developed to reduce streak artifact and noise. Phase-sensitive SSFP was employed for fat suppression using phase detection. Experimental studies were performed on volunteers. The proposed technique provides high-resolution coronary artery imaging for all cardiac phases, and allows multiple images at mid-diastole to be averaged, thus enhancing the signal-to-noise ratio (SNR) and vessel delineation.     

In vivo single scan detection of both iron-labeled cells and breast cancer metastases in the mouse brain using balanced steady-state free precession imaging at 1.5 T

Purpose:

To simultaneously detect iron‐labeled cancer cells and brain tumors in vivo in one scan, the balanced steady‐state free precession (b‐SSFP) imaging sequence was optimized at 1.5 T on mice developing brain metastases subsequent to the injection of micron‐sized iron oxide particle‐labeled human breast cancer cells.

Materials and Methods:

b‐SSFP sequence parameters (repetition time, flip angle, and receiver bandwidth) were varied and the signal‐to‐noise ratio, contrast between the brain and tumors, and the number of detected iron‐labeled cells were evaluated.

Results:

Optimal b‐SSFP images were acquired with a 26 msec repetition time, 35° flip angle, and bandwidth of ±21 kHz. b‐SSFP images were compared with T₂‐weighted 2D fast spin echo (FSE) and 3D spoiled gradient recalled echo (SPGR) images. The mean tumor‐brain contrast‐to‐noise ratio and the ability to detect iron‐labeled cells were the highest in the b‐SSFP images.

Conclusion:

A single b‐SSFP scan can be used to visualize both iron‐labeled cells and brain metastases. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Performance of steady-state free precession for imaging carotid artery disease

PURPOSE: To evaluate steady-state free precession (SSFP) for diagnosing carotid artery disease. MATERIALS AND METHODS: Following bilateral x-ray angiography, seven patients with suspected carotid artery disease were imaged with SSFP, black blood fast spin echo (BB FSE), and time-of-flight MR angiography (TOF MRA). The techniques were compared for characterizing the vessel lumen. Flow phantom experiments were also performed, using speeds of 0 to 40 cm/second, to further evaluate the merits of each MR technique. RESULTS: In the patient studies, of the 14 arteries available, a correct grading of stenosis was possible with SSFP in 9 of 14, FSE in 12 of 14, and TOF in 13 of 14, assuming x-ray angiography as the gold standard. The SSFP technique was the least reliable and had severe artifacts in 5 of 14 arteries, making these images nondiagnostic. The flow phantom demonstrated that although the SSFP technique performs well under slow or no flow, it breaks down at higher flow levels. CONCLUSION: The continuous SSFP sequence used here was not reliable for imaging carotid artery disease owing to artifact in many cases. Nevertheless, the high speed of this SSFP technique does allow it to serve as a rapid scouting method prior to a more detailed evaluation with other MRI methods.     

3D flow‐independent peripheral vessel wall imaging using T2‐prepared phase‐sensitive inversion‐recovery steady‐state free precession

Purpose:

To develop a 3D flow‐independent peripheral vessel wall imaging method using T₂‐prepared phase‐sensitive inversion‐recovery (T₂PSIR) steady‐state free precession (SSFP).

Materials and Methods:

A 3D T₂‐prepared and nonselective inversion‐recovery SSFP sequence was designed to achieve flow‐independent blood suppression for vessel wall imaging based on T₁ and T₂ properties of the vessel wall and blood. To maximize image contrast and reduce its dependence on the inversion time (TI), phase‐sensitive reconstruction was used to restore the true signal difference between vessel wall and blood. The feasibility of this technique for peripheral artery wall imaging was tested in 13 healthy subjects. Image signal‐to‐noise ratio (SNR), wall/lumen contrast‐to‐noise ratio (CNR), and scan efficiency were compared between this technique and conventional 2D double inversion recovery – turbo spin echo (DIR‐TSE) in eight subjects.

Results:

3D T₂PSIR SSFP provided more efficient data acquisition (32 slices and 64 mm in 4 minutes, 7.5 seconds per slice) than 2D DIR‐TSE (2–3 minutes per slice). SNR of the vessel wall and CNR between vessel wall and lumen were significantly increased as compared to those of DIR‐TSE (P < 0.001). Vessel wall and lumen areas of the two techniques are strongly correlated (intraclass correlation coefficients: 0.975 and 0.937, respectively; P < 0.001 for both). The lumen area of T₂PSIR SSFP is slightly larger than that of DIR‐TSE (P = 0.008). The difference in vessel wall area between the two techniques is not statistically significant.

Conclusion:

T₂PSIR SSFP is a promising technique for peripheral vessel wall imaging. It provides excellent blood signal suppression and vessel wall/lumen contrast. It can cover a 3D volume efficiently and is flow‐ and TI‐independent. J. Magn. Reson. Imaging 2010;32:399–408. © 2010 Wiley‐Liss, Inc.     

SSFP and GRE phase contrast imaging using a three-echo readout.

A technique for rapid in-plane phase-contrast imaging with high signal-to-noise ratio (SNR) is described. Velocity-encoding is achieved by oscillating the readout gradient, such that each 2DFT phase-encode is acquired three times following a single RF slice-selective excitation. Three images are reconstructed, from which both flow velocity and local resonance offset are calculated. This technique is compatible with both gradient-recalled echo (GRE) and balanced steady-state free precession (SSFP) imaging using a single steady-state. The proposed technique enables 1D velocity mapping with 40% higher temporal resolution and 80% higher SNR, compared to conventional PC-MRI using bipolar velocity-encoding gradient pulses.     

Pilot study of improved lesion characterization in breast MRI using a 3D radial balanced SSFP technique with isotropic resolution and efficient fat‐water separation

Purpose

To assess a 3D radial balanced steady‐state free precession (SSFP) technique that provides submillimeter isotropic resolution and inherently registered fat and water image volumes in comparison to conventional T2‐weighted RARE imaging for lesion characterization in breast magnetic resonance imaging (MRI).

Materials and Methods

3D projection SSFP (3DPR‐SSFP) combines a dual half‐echo radial k‐space trajectory with a linear combination fat/water separation technique (linear combination SSFP). A pilot study was performed in 20 patients to assess fat suppression and depiction of lesion morphology using 3DPR‐SSFP. For all patients fat suppression was measured for the 3DPR‐SSFP image volumes and depiction of lesion morphology was compared against corresponding T2‐weighted fast spin echo (FSE) datasets for 15 lesions in 11 patients.

Results

The isotropic 0.63 mm resolution of the 3DPR‐SSFP sequence demonstrated improved depiction of lesion morphology in comparison to FSE. The 3DPR‐SSFP fat and water datasets were available in a 5‐minute scan time while average fat suppression with 3DPR‐SSFP was 71% across all 20 patients.

Conclusion

3DPR‐SSFP has the potential to improve the lesion characterization information available in breast MRI, particularly in comparison to conventional FSE. A larger study is warranted to quantify the effect of 3DPR‐SSFP on specificity. J. Magn. Reson. Imaging 2009;30:135–144. © 2009 Wiley‐Liss, Inc.     

Free-breathing 3D steady-state free precession coronary magnetic resonance angiography: comparison of diaphragm and cardiac fat navigators

PURPOSE: To compare the performance of the conventional diaphragm navigator (DNAV) and the recently developed cardiac fat navigator (FatNAV) in suppressing respiration-induced cardiac motion in free-breathing 3D balanced steady-state free precession coronary MRA (SSFP CMRA). MATERIALS AND METHODS: In 16 healthy volunteers the right coronary artery (RCA) was imaged at 1.5T using a navigator-gated 3D SSFP CMRA sequence. DNAV and FatNAV gating were performed in random order. Image quality difference was scored by three experienced readers blinded to the gating technique. Blood signal-to-noise ratio (SNR), blood-to-myocardium contrast-to-noise ratio (CNR), and navigator efficiency were calculated. RESULTS: Diagnostically interpretable CMRA was obtained successfully in all 16 subjects with FatNAV gating (0% failure rate) and only 14 subjects with DNAV gating (12% failure rate). Compared to DNAV gating, FatNAV gating provided similar SNR and CNR, better image quality (P < 0.01), and 28% improvement in navigator efficiency (P = 0.002). CONCLUSION: FatNAV gating provides more effective motion suppression and better image quality than DNAV gating for free-breathing 3D SSFP CMRA of the RCA in healthy subjects.     

Fast phase-contrast velocity measurement in the steady state.

A new method of encoding flow velocity as image phase in a refocused steady-state free precession (SSFP) sequence, called steady-state phase contrast (SSPC), can be used to generate velocity images rapidly while retaining high signal. Magnitude images with refocused-SSFP contrast are simultaneously acquired. This technique is compared with the standard method of RF-spoiled phase contrast (PC), and is found to have more than double the phase-signal to phase-noise ratio (PNR) when compared with standard PC at reasonable repetition intervals (TRs). As TR decreases, this advantage increases exponentially, facilitating rapid scans with high PNR efficiency. Rapid switching between the two necessary steady states can be accomplished by the insertion of a single TR interval with no flow-encoding gradient. The technique is implemented in a 2DFT sequence and validated in a phantom study. Preliminary results indicate that further TR reduction may be necessary for high-quality cardiac images; however, images in more stationary structures, such as the descending aorta and carotid bifurcation, exhibit good signal-to-noise ratio (SNR) and PNR. Comparisons with standard-PC images verify the PNR advantage predicted by theory.     

Corticomedullary differentiation of the kidney: Evaluation with noncontrast‐enhanced steady‐state free precession (SSFP) MRI with time‐spatial labeling inversion pulse (time‐SLIP)

Purpose:

To assess whether noncontrast‐enhanced steady‐state free precession (SSFP) magnetic resonance imaging (MRI) with time‐spatial labeling inversion pulse (Time‐SLIP) can improve the visibility of corticomedullary differentiation of the normal kidney.

Materials and Methods:

A series of noncontrast‐enhanced SSFP MRI with Time‐SLIP were performed in 20 patients by using various inversion times (TIs); 500–1800 msec in increments of 100 msec. In‐phase (IP) and opposed‐phase (OP) MR images were also obtained. The signal intensity (SI) of the renal cortex and medulla was measured to calculate corticomedullary contrast ratio (SI of cortex/medulla). Additionally, the visibility of corticomedullary differentiation was visually categorized using a four‐point scale.

Results:

In SSFP with Time‐SLIP, corticomedullary contrast ratio was highest with TI of 1200 msec in eight subjects (40%), followed by 1100 msec in seven (35%) and 1000 msec in three (15%). The corticomedullary contrast ratio in SSFP with optimal Time‐SLIP (4.93 ± 1.25) was significantly higher (P < 0.001) than those of IP (1.46 ± 0.12) and OP (1.43 ± 0.14). The visibility of corticomedullary differentiation was significantly better (P < 0.001) in SSFP images with Time‐SLIP (averaged grade = 4.0) than in IP images (averaged grade = 2.63) and OP images (averaged grade = 2.05).

Conclusion:

SSFP MRI with Time‐SLIP can improve the visibility of renal corticomedullary differentiation without using contrast agents. J. Magn. Reson. Imaging 2012;37:1178–1181. © 2012 Wiley Periodicals, Inc.     

Oscillating dual-equilibrium steady-state angiography.

A novel technique of generating noncontrast angiograms is presented. This method, called oscillating dual-equilibrium steady-state angiography (ODESSA), utilizes a modified steady-state free precession (SSFP) pulse sequence. The SSFP sequence is modified such that flowing material reaches a steady state which oscillates between two equilibrium values, while stationary material attains a single, nonoscillatory steady state. Subtraction of adjacent echoes results in large, uniform signal from all flowing spins and zero signal from stationary spins. Venous signal can be suppressed based on its reduced T2. ODESSA arterial signal is more than three times larger than that of traditional phase-contrast angiography (PCA) in the same scan time, and also compares favorably with other techniques of MR angiography (MRA). Pulse sequences are implemented in 2D, 3D, and volumetric-projection modes. Angiograms of the lower leg, generated in as few as 5 s, show high arterial signal-to-noise ratio (SNR) and full suppression of other tissues.     

Single breath‐hold assessment of ventricular volumes using 32‐channel coil technology and an extracellular contrast agent

Purpose:

To evaluate the feasibility of a single breath‐hold 3D cine balanced steady‐state free precession (b‐SSFP) sequence after gadolinium diethylenetriamine penta‐acetic acid (Gd‐DTPA) injection for volumetric cardiac assessment.

Materials and Methods:

Fifteen adult patients routinely referred for cardiac magnetic resonance imaging (MRI) underwent quantitative ventricular volumetry on a clinical 1.5T MR‐scanner using a 32‐channel cardiac coil. A stack of 2D cine b‐SSFP slices covering the ventricles was used as reference, followed by a single breath‐hold 3D cine balanced SSFP protocol acquired before and after administration of Gd‐DTPA. The acquisition was accelerated using SENSE in both phase encoding directions. Volumetric and contrast‐to‐noise data for each technique were assessed and compared.

Results:

The 3D cine protocol was accomplished within one breath‐hold (mean acquisition time 20 sec; spatial resolution 2.1 × 2.1 × 10 mm; temporal resolution 51 msec). The contrast‐to‐noise ratio between blood and myocardium was 234 determined for the multiple 2D cine data, and could be increased for the 3D acquisition from 136 (3D precontrast) to 203 (3D postcontrast) after injecting Gd‐DTPA. In addition the endocardial definition was significantly improved in postcontrast 3D cine b‐SSFP. There was no significant difference for left and right ventricular volumes between standard 2D and 3D postcontrast cine b‐SSFP. However, Bland–Altman plots showed greater bias and scatter when comparing 2D with 3D cine b‐SSFP without contrast.

Conclusion:

3D cine b‐SSFP imaging of the heart using 32 channel coil technology and spatial undersampling allows reliable volumetric assessment within a single breath‐hold after application of Gd‐DTPA. J. Magn. Reson. Imaging 2010;31:838–844. ©2010 Wiley‐Liss, Inc.     

Fat and water separation in balanced steady-state free precession using the Dixon method.

In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished.     

Fast 3D 1H spectroscopic imaging at 3 Tesla using spectroscopic missing-pulse SSFP with 3D spatial preselection.

Three-dimensional (3D) (1)H MR spectroscopic imaging (SI) allows metabolic changes in human tissue to be identified. In clinical practice, fast acquisition techniques are required to achieve an adequate spatial resolution within acceptable total measurement times. In this study a novel fast pulse sequence for 3D (1)H SI based on the condition of steady-state free precession (SSFP), termed "spectroscopic missing-pulse SSFP" (spMP-SSFP), is proposed. It combines 3D spatial preselection with the acquisition of full spin echoes (SEs), and thus makes subsequent phase correction of spectra redundant. The sequence was applied to a phantom and healthy human brains in vivo at 3 Tesla. Metabolic images are acquired with a spatial resolution of 1.8 cm(3) within a total measurement time of about 6 min. With a lower signal-to-noise ratio (SNR) per unit measurement time compared to previous spectroscopic SSFP implementations, 3D spatial preselection can now be realized with spMP-SSFP. Since the method does not require separate techniques for water and lipid suppression, and employs a simple data-processing approach, spMP-SSFP is a robust, fast SI method that requires only minimal user interaction.     

3D breath-held cardiac function with projection reconstruction in steady state free precession validated using 2D cine MRI

PURPOSE: To develop and validate a three-dimensional (3D) single breath-hold, projection reconstruction (PR), balanced steady state free precession (SSFP) method for cardiac function evaluation against a two-dimensional (2D) multislice Fourier (Cartesian) transform (FT) SSFP method. MATERIALS AND METHODS: The 3D PR SSFP sequence used projections in the x-y plane and partitions in z, providing 70-80 msec temporal resolution and 1.7 x 1.7 x 8-10 mm in a 24-heartbeat breath hold. A total of 10 volunteers were imaged with both methods, and the measurements of global cardiac function were compared. RESULTS: Mean signal-to-noise ratios (SNRs) for the blood and myocardium were 114 and 42 (2D) and 59 and 21 (3D). Bland-Altman analysis comparing the 2D and 3D ejection fraction (EF), left ventricular end diastolic volume (LVEDV) and end systolic volume (LVESV), and end diastolic myocardial mass (LVEDM) provided values of bias +/-2 SD of 0.6% +/- 7.7 % for LVEF, 5.9 mL +/- 20 mL for LVEDV, -2.8 mL +/- 12 mL for LVESV, and -0.61 g +/- 13 g for LVEDM. 3D interobserver variability was greater than 2D for LVEDM and LVESV. CONCLUSION: In a single breath hold, the 3D PR method provides comparable information to the standard 2D FT method, which employs 10-12 breath holds.     

Analysis of multiple-acquisition SSFP.

Refocused steady-state free precession (SSFP) is limited by its high sensitivity to local field variation, particularly at high field strengths or the long repetition times (TRs) necessary for high resolution. Several methods have been proposed to reduce SSFP banding artifact by combining multiple phase-cycled SSFP acquisitions, each differing in how individual signal magnitudes and phases are combined. These include maximum-intensity SSFP (MI-SSFP) and complex-sum SSFP (CS-SSFP). The reduction in SSFP banding is accompanied by a loss in signal-to-noise ratio (SNR) efficiency. In this work a general framework for analyzing banding artifact reduction, contrast, and SNR of any multiple-acquisition SSFP combination method is presented. A new sum-of-squares method is proposed, and a comparison is performed between each of the combination schemes. The sum-of-squares SSFP technique (SOS-SSFP) delivers both robust banding artifact reduction and higher SNR efficiency than other multiple-acquisition techniques, while preserving SSFP contrast.     

Double average parallel steady-state free precession imaging: optimized eddy current and transient oscillation compensation.

Balanced steady-state free precession (SSFP) imaging is sensitive to off-resonance effects, which can lead to considerable artifacts during a transient phase following magnetization preparation or steady-state interruption. In addition, nonlinear k-space encoding is required if contrast-relevant k-space regions need to be acquired at specific delays following magnetization preparation or for transient artifact reduction in cardiac-gated k-space segmented CINE imaging. Such trajectories are problematic for balanced SSFP imaging due to nonconstant eddy current effects and resulting disruption of the steady state.In this work, a novel acquisition strategy for balanced SSFP imaging is presented that utilizes scan time reduction by parallel imaging for optimized "double average" eddy current compensation and artifact reduction during the transient phase following steady-state storage and magnetization preparation. Double average parallel SSFP imaging was applied to k-space segmented CINE SSFP tagging as well as nongated centrically encoded SSFP imaging. Phantom and human studies exhibit substantial reduction in steady-state storage and eddy current artifacts while maintaining spatial resolution, signal-to-noise ratio, and similar total scan time of a standard SSFP acquisition. The proposed technique can easily be extended to other acquisition schemes that would benefit from nonlinear reordering schemes and/or rely on interruption of the balanced SSFP steady state.     

Implications of pulse sequence in structural imaging of trabecular bone

PURPOSE: To investigate the SNR and image properties of 3D steady-state free precession (SSFP), fast large-angle spin echo (FLASE), gradient-recalled acquisition in steady state (GRASS), and spoiled GRASS (SPGR) for structural imaging of trabecular bone (TB). MATERIALS AND METHODS: SNR was examined theoretically and experimentally on phantoms, bone specimens, and in vivo. The bone volume fraction, TB thickness, and echo time (TE) dependence of the thickness were compared. The trabecula was modeled as a cylinder in simulations to examine the intra-voxel spin-dephasing in SSFP and GRASS. Images were acquired on a 1.5 T Siemens Sonata system (40 mT/m maximum gradient, 200 T/m/s peak slew rate). RESULTS: Within the hardware and safety limit constraints, SNR of FLASE was superior, followed by SSFP, GRASS, and SPGR. The trabecular thickness derived from gradient-echo images was 10-45% greater than that obtained with FLASE. Conversely, SSFP images delineated partial volume trabeculae better than FLASE. Simulations indicated that the artifactual thickening was more severe in SSFP than in GRASS, which was attributed to off-resonance effects from the induced gradients at the bone/marrow interface. CONCLUSION: FLASE had the highest SNR and was insensitive to susceptibility dephasing. Although SSFP has superior SNR compared to GRASS, off-resonance effects and duty cycle limitations may compromise its practicality in this application. Inc.