Cervical spine: MR imaging with a partial flip angle, gradient- refocused pulse sequence. Part I. General considerations and disk disease

A magnetic resonance imaging pulse sequence with a short repetition time (TR), short echo time (TE), partial flip angle, and gradient refocused echo was evaluated for the detection of cervical disk disease in a prospective study of 90 patients. These parameters were manipulated to adjust signal-to-noise ratio (S/N) and contrast: flip angle (3 degrees-18 degrees), TR (22-60 msec), and TE (12.5-25 msec). Flip angle had the greatest effect on S/N and contrast; its effect differed between axial and sagittal imaging. Cerebrospinal fluid S/N reached a peak at a smaller flip angle in sagittal imaging than in axial imaging. The useful range of flip angles depended on TR. Increasing TR had minimal direct effect on S/N or contrast, but because a longer TR allowed the use of larger flip angles for both axial and sagittal imaging, higher S/N could be achieved with similar contrast. This effect of increasing TR had to be balanced against increased imaging time and increased probability of motion artifact. Increasing TE decreased S/N, increased contrast, and increased magnetic susceptibility artifacts. For the diagnosis of cervical disk disease, the best sequence appears to be one with a very short TR, short TE, and small flip angles within a narrow range.     

Lymph nodes of the neck. Diagnosis using magnetic resonance with gradient-echo technique

As for the pathologic conditions of neck lymph nodes, the clinician needs to know if the involved node is reactive, phlogistic, or neoplastic in nature. If accurate tumor staging is required, imaging techniques play a fundamental role. Our study was aimed at assessing the actual role of MR imaging in the evaluation of neck lymph node involvement. The study was performed using an MR Max Plus by General Electrics operating with an 0.5 T superconductive magnet. We employed gradient-echo (GE) pulse sequences with TR 500, TE 15 ms and 90 degrees flip angle for T1-weighted images, and with TR 500, TE 30 ms and 25-30 degrees flip angles for T2-weighted images; for Pd-T2-weighted images, TR was 520, TE 30 ms, and flip angles were 40-45 degrees. The results were correlated with histopathologic findings obtained at biopsy. The advantages of GE sequences were: 1) whole neck imaging--thus saving time, and reducing radiation dose and contrast media; 2) optimal anatomical and topographic evaluation of the lesion; 3) imaging of the longitudinal diameter of the node; 4) higher sensitivity for lymph node tissue modifications; 5) imaging of necrosis, hemorrhage, and/or fibrosis. GE sequences were especially useful for accurate tumor staging, in the follow-up, and to verify response to therapy. However, even though MR imaging has proven to have high sensitivity, its specificity was similar to that of contrast-enhanced CT. Further studies with the use of paramagnetic contrast media are needed to solve these problems.     

Partial flip angle MR imaging

Theoretical analysis predicts that performing magnetic resonance (MR) imaging with partial (less than 90 degrees) flip angles can reduce imaging times two- to fourfold when lesions with elevated T1 values are being examined. This time savings occurs because repetition time (TR) is reduced when imaging is performed with partial flips. Partial flip MR imaging can also improve signal-to-noise ratio (S/N) in fast body imaging. For this study, analytical tools were used to predict image contrast and S/N for short TR, partial flip sequences. Experimental implementation of the short TR, partial flip sequences that analytical work had predicted would be optimal supported the analytical predictions and demonstrated their validity. Partial flip MR imaging is applicable to reducing imaging time only when the ratio of signal differences to noise exceeds threshold values in conventional MR images. Partial flip sequences can be used to advantage in MR imaging of both the head and the body, and the observed effects are predictable through theoretical analysis.     

Fast fat suppression RF pulse train with insensitivity to B1 inhomogeneity for body imaging

In higher‐field magnetic resonance imaging scanners, a spectrally selective fat saturation radiofrequency (RF) pulse does not work well because B₁ inhomogeneity increases. An adiabatic 180° pulse is used to improve nonuniform fat suppression, but requires inversion recovery time. Therefore, a new RF pulse that achieves flip angles near 90° and is B₁ insensitive has been developed. The pulse consists of three sinc‐shaped RF pulses with different flip angles and with different time intervals between each RF pulse. Using the Bloch equations, we analyzed the optimal combination of flip angles. Experimental results demonstrated that M_z was maintained at less than 0.05 M₀ for a B₁ inhomogeneity of ±35%. The optimal net flip angles was adjusted to 95° by varying the time interval between RF pulses. The pulse duration was 77 ms, which is less than half of the 170‐ms inversion recovery time required for the adiabatic pulse. We demonstrated excellent fat suppression for body imaging. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.     

Diffusion tensor imaging using partial Fourier STEAM MRI with projection onto convex subsets reconstruction.

Diffusion-weighted single-shot STEAM MRI allows for diffusion mapping of the human brain without sensitivity to resonance offset effects. In order to compensate for its inherently lower SNR and speed than echo-planar imaging, this work describes the use of partial Fourier encoding in combination with image reconstruction by the projection onto convex subsets algorithm. The method overcomes phase distortions in diffusion-weighted partial Fourier acquisitions that disturb the conjugate complex symmetry of k-space and preclude the use of respective reconstruction techniques. In comparison with full Fourier encoding and a static flip angle for the STEAM readout pulses, experimental results at 2.9 T demonstrate a gain in relative SNR per unit time by 20% for 5/8 phase encoding with optimized variable flip angles. Simultaneously, the imaging time is reduced from about 670 ms (80 echoes) to 440 ms (50 echoes). Current implementations at 2 x 2 mm2 in-plane resolution comprise a protocol for clinical anisotropy studies (12 diffusion-encoding gradient directions at 1000 s mm(-2)) covering 18 sections of 4-mm thickness within a measurement time of 8.5 min (5 averages) and a version optimized for fiber tracking using 24 gradient directions and 38 sections of 2-mm thickness yielding a measurement time of 29.5 min (4 averages).     

Optimization of magnetic resonance imaging parameters for left ventricular wall motion studies at 0.5 T

Magnetic resonance cine imaging of left ventricular wall motion at rest or during stress may be used to assess myocardial function, infarction and viability, or reversible ischaemia. Whilst interpretation of the cines rests critically on image quality, there is little in the literature which systematically examines the optimal imaging parameters for such wall motion studies at rest or during stress. This study was designed to examine several imaging parameters for cine optimization using a conventional 0.5 T scanner. Gradient echo imaging was performed in two groups of volunteers with varying echo times and flip angles. The period between excitations was 80 ms (simulating a resting heart rate) in one group, and 40 ms (simulating tachycardia during stress) in the other group. Short axis imaging yielded the highest contrast between blood and myocardium for both repetition times (rest p = 0.02; stress p < 0.001) compared with the long axes, because of magnetic saturation of blood moving slowly in-plane. Contrast was higher at end-diastole than end-systole for the long axes (rest p < 0.0001; stress p < 0.0002), but not significantly different in the short axis. Increasing the echo time and flip angle resulted in increased signal but eventually caused motion artefact and magnetic saturation of blood. The optimal parameters were an echo time of 14 ms and a 45 degrees flip angle for resting heart rates, with the flip angle falling to between 35 degrees and 45 degrees for tachycardia. The choice of imaging parameters is therefore a compromise between improved signal and unwanted artefacts, although the latter are less evident in the short axis plane, which yields the best contrast results because of high blood inflow effects.     

Multiecho sequences with variable refocusing flip angles: optimization of signal behavior using smooth transitions between pseudo steady states (TRAPS).

A variation of the rapid acquisition with relaxation enhancement (RARE) sequence (also called turbo spin-echo (TSE) or fast spin-echo (FSE)) is presented. This technique uses variable flip angles along the echo train such that magnetization is initially prepared into the static pseudo steady state (PSS) for a low refocusing flip angle (alpha < 180 degrees ). It is shown that after such a preparation, magnetization will always stay very close to the static PSS even after significant variation of the subsequent refocusing flip angles. This allows the design of TSE sequences in which high refocusing flip angles yielding 100% of the attainable signal are applied only for the important echoes encoding for the center of k-space. It is demonstrated that a reduction of the RF power (RFP) by a factor of 2.5-6 can be achieved without any loss in signal intensity. The contribution of stimulated-echo pathways leads to a reduction of the effective TE by a factor f(t), which for typical implementations is on the order of 0.5-0.8. This allows the use of longer echo readout times, and thus longer echo trains, for acquiring images with a given T(2) contrast.     

Evaluation of fast MR imaging with suspended respiration in hepatic tumors

The purpose of this study is to evaluate the possibility of qualitative diagnosis in hepatic tumors by fast magnetic resonance (MR) imaging with suspended respiration using partial flip angle and gradient echo technique at 0.5 T. Fast MR imaging does not replace conventional spin-echo procedures, but is complementary to it. For the analysis of contrast as a function of flip angle, 32 hepatocellular carcinomas (HCCs) of nodular type and 11 hemangiomas were examined with flip angles of 20, 40 and 60 degrees on sagittal images. In general, the lesions showed relatively high and low intensities on the images with flip angles of 20 and 60 degrees, respectively. On the images with flip angle of 40 degrees, signal-to-noise (S/N) ratio was higher, but contrast between tumor and liver was lesser than with that of other angles. The change of contrast-to-noise (C/N) ratio between the flip angles of 20 and 60 degrees in hemangiomas was larger than that in HCCs, significantly. It was useful for evaluation of lesions to observe the change of C/N ratio, and it was necessary for detection of lesions to obtain the images with at least three flip angles. For dynamic MR imaging, 18 HCCs including 5 cases after transcatheter chemoembolization (TCE) and 5 hemangiomas were examined with flip angle of 40 degrees. With employment of Gd-DTPA, S/N ratio and contrast were improved in many cases, and hemodynamics of tumors was able to be observed. It was suggested that dynamic MR imaging was useful especially in evaluation of efficacy of TCE using lipiodol.     

Multipurpose NMR imaging using stimulated echoes

STEAM (stimulated-echo acquisition mode) imaging techniques recently introduced by the authors are demonstrated to provide a versatile tool for improving the parametric specificity in NMR imaging. Stimulated echoes can be excited by a sequence of at least three rf pulses with flip angles of 90 degrees or less. The main characteristics of the STEAM method are based on the great functional flexibility of an imaging sequence comprising three rf pulses unequal to 180 degrees and three intervals prior to acquisition of the data. Major advantages are the easy access to contiguous multiplanar images, to CHESS (chemical-shift-selective) images, and to T1 information. Moreover, the rf power deposition is considerably reduced as compared to spin-echo NMR imaging sequences. Here first in vivo results on human extremities are presented including contiguous multislice images, multiple CHESS images, and spin-lattice relaxation time images calculated from a series of simultaneously recorded T1-weighted STEAM images.     

Time-reduced T2-weighted celebral MRI with optimized flip angles

This study was set up to see whether lowering the flip angle in proton density- and T2-weighted double-spin echo sequences allows for shortening of repetition time (TR) and imaging time without significant change of image quality. Ten patients with celebral white matter lesions were investigated with an 1.5 T MR scanner using a conventional long- TR double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and reduced-TR double-spin echo sequences (TR = 1900 ms, TE = 15 and 70 ms) at flip angles of 90°, 80°, 70°, 60°, and 50°. Lowering the flip angle resulted in less T1-contrast and a relative increase of T2-contrast. At a flip angle of 70°, contrast-to noise ratios (NNRs) between lesions and brain, as well as image artifacts of the reduced-TR sequence (CNR: 22.4) were similar to the conventional long-TR sequence (CNR:21.1), while imaging time was shortened by about 25%. Offprint requests to: Peter Schubeus     

Magnetic resonance angiography of the pulmonary artery. Preliminary considerations

The possibility was evaluated of imaging the pulmonary artery with MR angiography. Twenty healthy volunteers were studied using 3D FT gradient-echo sequences on the coronal plane, with post-processing by the maximum intensity projection method. TE and TR remaining short, flip angles were selected to increase pulmonary artery signal in contrast with hypointense adjacent tissues and vessels. Flip angle selection allowed the optimal differentiation between pulmonary artery and aorta with 15 degree-25 degree angles (range: 110.7 to 122 for the 15 degree flip angle and 158.7 to 182.1 for the 20 degree flip angle). The sequence was obtained on the coronal plane and the following parameters were employed: TR 0.03 s, TE 10 ms, flip angle 15 degree-20 degree, slice of the total volume 100 mm with 64 partitions, 256 x 256 matrix, 1 zoom factor, 1 acquisition. The patient was positioned with the right hemithorax raised by 30 degrees to visualize the common pulmonary artery and lying on his back, face upward, to visualize the right and left pulmonary arteries. Post-processing employed axial plane rotations from -45 degrees to +45 degrees, with 5 degrees step, and from 0 degrees to 180 degrees, with 15 degrees step. Angio-MR images of the pulmonary artery allowed the visualization of its main components, up to its right and left lobar branches. The main limitation of this technique consisted in its poor spatial resolution.     

Cervical spine: MR imaging with a partial flip angle, gradient- refocused pulse sequence. Part II. Spinal cord disease

A magnetic resonance imaging pulse sequence (GRASS) with a short repetition time (TR), short echo time (TE), partial flip angle, and gradient refocused echo was prospectively evaluated for the detection of cervical cord disease that caused minimal or no cord enlargement in eight patients. Sagittal T2-weighted, cerebrospinal fluid (CSF)-gated images and sagittal and axial GRASS images were obtained in all patients. The following GRASS parameters were manipulated to determine their effect on signal-to-noise ratio (S/N) and contrast: flip angle (4 degrees-18 degrees), TR (22-50 msec), and TE (12.5-25 msec). Flip angle had the greatest effect on S/N and contrast. There were no differences between axial and sagittal imaging for the spinal cord or lesion. However, because the signal intensity of CSF did differ on sagittal and axial images and because this influenced the conspicuity of lesions, there was a difference in the useful flip angle range for axial and sagittal imaging. No one set of imaging parameters was clearly superior, and in all patients, the gated image was superior to the sagittal GRASS image in lesion detection. GRASS images should be used in the axial plane primarily to confirm spinal cord disease detected on sagittal CSF-gated images. For this, a balanced approach is suggested (TR = 40 msec, TE = 20 msec, with flip angles of 4 degrees-6 degrees for sagittal and 6 degrees-8 degrees for axial imaging).     

Correction of inhomogeneous RF field using multiple SPGR signals for high-field spin-echo MRI.

PURPOSE: To propose a simple and useful method for correcting nonuniformity of high-field (3 Tesla) T(1)-weighted spin-echo (SE) images based on a B1 field map estimated from gradient recalled echo (GRE) signals. METHODS: To estimate B1 inhomogeneity, spoiled gradient recalled echo (SPGR) images were collected using a fixed repetition time of 70 ms, flip angles of 45 and 90 degrees, and echo times of 4.8 and 10.4 ms. Selection of flip angles was based on the observation that the relative intensity changes in SPGR signals were very similar among different tissues at larger flip angles than the Ernst angle. Accordingly, spatial irregularity that was observed on a signal ratio map of the SPGR images acquired with these 2 flip angles was ascribed to inhomogeneity of the B1 field. Dual echo time was used to eliminate T(2)(*) effects. The ratio map that was acquired was scaled to provide an intensity correction map for SE images. Both phantom and volunteer studies were performed using a 3T magnetic resonance scanner to validate the method. RESULTS: In the phantom study, the uniformity of the T(1)-weighted SE image improved by 23%. Images of human heads also showed practically sufficient improvement in the image uniformity. CONCLUSION: The present method improves the image uniformity of high-field T(1)-weighted SE images.     

A method for correctly setting the rf flip angle

Currently the accepted method for setting the correct rf power levels to achieve 90 degrees and 180 degrees rf pulses for MR imaging is to peak the echo amplitude of a rf spin-echo sequence. The echo amplitude of this alpha-2 alpha pulse sequence is proportional to sin3 (alpha) and has a relatively broad maximum. Recently another method for setting the rf flip angle by maximizing the ratio of the stimulated echo to the primary echo amplitudes (in a 3 alpha sequence) demonstrated accuracy similar to that of the spin-echo method using a shorter repetition time. We present a new, more sensitive, and more accurate method for setting the correct rf power levels for 90 degrees and 180 degrees rf pulses. In this method, based upon the stimulated echo pulse sequence, we are able to accurately set the rf power to within +/- 0.1 dB by minimizing the signal amplitude of the third spin echo. This null method works for both selective and nonselective rf pulses of flip angle 90 degrees or 180 degrees, allowing the user to accurately adjust the relative amplitudes of the four rf pulse types within a single pulse sequence.     

Preliminary clinical results with low flip angle spin-echo MR imaging of the head and neck

A new approach for producing primarily T2- and proton-density-weighted MR images in less time than the conventional long TR, long TE imaging is to reduce the TR of a double spin-echo pulse sequence and to also reduce the RF excitation flip angle to minimize the resulting T1 sensitivity. In preliminary studies with a human volunteer and five patients with various diseases of the head and neck, conventional long TR, long TE and short TR, short TE images were compared with short TR, long TE images with reduced flip angles (45 degrees, 30 degrees), which required only 40% of the imaging time of the long TR images. The latter images showed a similar contrast pattern to the conventional T2-weighted image, and contrast-to-noise measurements indicated an increase in contrast between the lesion and nearby tissue when the flip angle was reduced. Furthermore, the maximum contrast/noise per unit imaging time on the short TR, long TE image was comparable to that on the long TR, long TE image. Optimization of the flip angle with short TR allows a substantial reduction in imaging time but with a reduction in multislice capability. This technique will be most useful in areas of complex anatomy where two or more orthogonal imaging planes are required, such as the head and neck.     

Quantitative evaluation of hyaline cartilage disorders using flash sequence. I. Method and animal experiments

A method for quantitative evaluation of hyaline cartilage signal intensities has been developed in an experimental study of 6 swine knees with different types of arthritis. A FLASH sequence with TR 50 ms, TE 10 ms and flip angles of 5, 10, 20, 25, 30, 35, 50 and 90 degrees was employed. Two parameters of the signal intensity flip angle curves proved to be useful for tissue characterisation: The initial increase (A) and the maximum (M).     

Variable-flip-angle spin-echo MR imaging of the pelvis: more versatile T2-weighted images

Dependence on T1 contrast can be reduced by changing the excitation flip angle. The authors compared T2-weighted spin-echo images (with 30 degrees and 90 degrees flip angles) of the male and female pelvis in 22 individuals. In six women imaged with a 1,000/80 sequence (repetition time msec/echo time msec), signal difference-to-noise ratios (SD/Ns) were higher with a 30 degree flip angle than with a 90 degree angle for urine/fat (mean, 15.2 vs -6.2; P less than .05) and endometrium/myometrium (13.8 vs 9.0, P less than .05). In eight additional examinations, a 1,000/80 sequence with a 30 degree flip angle and two signal averages had less motion artifact (1.2 vs 2.7, P less than .01) than a 2,000/80 sequence with a 90 degree angle and one signal average (4.5 minutes each); SD/Ns were similar. In a third series of experiments, contiguous sections without cross talk, obtained by interleaving two 1,000/100, 30 degrees-flip-angle acquisitions, had better contrast than contiguous sections obtained at 2,400/100 with a 90 degree flip angle (10 minutes each), with SD/Ns of urine/fat of 28.5 versus 16.1 (P less than .01) and SD/Ns of endometrium/myometrium of 15.5 versus 7.8 (P less than .05). Reducing the flip angle can improve examination time, contrast, or motion artifact suppression or eliminate cross talk in T2-weighted spin-echo MR imaging of the pelvis.     

Cardiac MRI: comparison between single-shot fast spin echo and conventional spin echo sequences in the morphological evaluation of the ventricles

PURPOSE: Black blood single shot FSE sequences (Nffse) employ 180 degrees RF refocalisation pulses preceded by an inversion RF double pulse associated to presaturation pulses. The latter produce signal void of the external volume, and possible reduction of the field of view without wrap-around artifacts along the phase coding direction. The aim of our study was to compare the diagnostic possibilities of the Nffse sequences with those of conventional SE study of cardiac morphology. MATERIAL AND METHODS: Twenty-five patients (19 males and 9 females with age ranging from 20 to 54 years) presented findings suggesting right ventricular arrhythmogenic dysplasia. MR examinations were performed with a 1,5 T unit (GE Signa Horizon Echospeed 8.3, Milwaukee, USA) and Torso Phased Array coil positioned at thoracic level. The morphologic study was performed with SE multiphase-multislice ECG-gated sequences (TR: R-R, TE: 30 ms, FOV 320X250, matrix 160X256, slice thickness 10 mm, acquisition time about 5 minutes) and Single-Shot FSE Half Fourier sequences (TR: R-R, TE: 30 ms, flip angle 120 degrees, ETL 30-40, FOV 360X180, Phase FOV 0,5, VBW 64 MHz, slice tickness 10 mm, acquisition time about 10-12 seconds), by imaging along the long and short axis. The study was completed with Fast Gradient Echo sequences (TR: 9ms, TE: 8,2ms, flip angle 25 degrees, VBW 15,63 MHz, FOV 320X250, 10 mm slice thickness, matrix 128X256), subsequently assessed by cine-MR. In order to compare both sequences, two experienced radiologists performed an analysis of quantitative parameters (signal intensity ratio between fat and muscular interventricular septum) and qualitative parameters (double blind evaluation for the presence of cardiac and respiratory artifacts). RESULTS: The signal intensity ratio for the Nffse sequence images was 4.63 +/- 1.56 on the long axis and 7.69 +/- 2.46 on the short axis, whereas it was 3.17 +/- 0.64 on the long axis and 3,50 +/- 0,75 on the axis one for SE images, with a statistically significant difference (p<0,001 and p<0.002 for the long and short axis, respectively). The two radiologists evaluation of the magnitude of artifacts on the SE and Nffse images was similar only as regards the images with significant artefacts alone. Nffse images consistently afforded a detailed evaluation of the right ventricular wall, although blurring artifacts were more common than with good quality SE images. Presence of fatty infiltration of the right ventricle wall was observed in 5 out of 25 patients. In the remaining 20 patients no fatty substitution of the muscular wall of the right ventricle was observed. DISCUSSION AND CONCLUSIONS: The Nffse sequences provide a number of gated multiphase-multislice images, similar to that obtained by conventional SE sequences, in one breath-hold time interval. Due to high intrinsic contrast and reduction of motion artifacts, the Nffse sequences allow a good evaluation of the ventricular morphology and subepicardial and paracardiac adipose tissue. Image quality can be suboptimal due to blurring artifacts. Therefore Nffse sequences can be advantageously employed to image patients with suspected right ventricular arrhythmogenic dysplasia, whenever conventional SE images exhibit substandard quality.     

Quantitative assessment of iron-oxide-enhanced magnetic resonance imaging of the liver: Vessel isointensity is a potential characteristic of liver hemangiomas on late T1-weighted images

PURPOSE: To test whether a new quantitative measure, the tumor-to-vessel ratio, obtained from late post-iron-oxide-enhanced T1-weighted images allows for differentiating hemangiomas from liver metastases or all malignant liver lesions. MATERIAL AND METHODS: Twenty-six patients (mean 57, range 33-79 years) were prospectively studied at 1.5T magnetic resonance imaging (MRI) with a T1-weighted 2D fast low-angle shot (FLASH) sequence (repetition time/echo time/flip angle; 200 ms/4.8 ms/90 degrees ) and a T2-weighted turbo spin-echo sequence (4072 ms/99 ms/180 degrees ). Imaging was carried out before and at intervals up to 18 min after IV injection of Ferucarbotran (Resovist, Schering, Germany). In 19 patients, one representative malignant lesion was analysed. Eleven hemangiomas were evaluated in 7 patients. Two readers performed a consensus reading with a signal intensity measurement in a lesion, normal liver and hepatic veins, from which ratios were computed. RESULTS: On T1-weighted iron-oxide-enhanced MRI of 30 lesions, tumor-to-vessel signal intensity ratios were distinct in hemangiomas (median 1.04, range 0.99-1.10) as opposed to either metastases (0.64, 0.33-0.77; P < 0.05) or all malignant lesions taken together (0.64, 0.33-0.98; P < 0.05), while the tumor-to-liver ratio was not. CONCLUSION: The tumor-to-vessel ratio may help to differentiate between hemangiomas and metastases. A ratio greater than 0.98 allowed differentiating hemangiomas from metastases with a wide safety margin.     

Alternating repetition time balanced steady state free precession.

A novel balanced SSFP technique for the separation or suppression of different resonance frequencies (e.g., fat suppression) is presented. The method is based on applying two alternating and different repetition times, TR(1) and TR(2). This RF scheme manipulates the sensitivity of balanced SSFP to off-resonance effects by a modification of the frequency response profile. Starting from a general approach, an optimally broadened stopband within the frequency response function is designed. This is achieved with a TR(2) being one third of TR(1) and an RF-pulse phase increment of 90 degrees . With this approach TR(2) is too short ( approximately 1 ms) to switch imaging gradients and is only used to change the frequency sensitivity. Without a significant change of the spectral position of the stopband, TR(1) can be varied over a range of values ( approximately 2.5-4.5 ms) while TR(2) and phase cycling is kept constant. On-resonance spins show a magnetization behavior similar to balanced SSFP, but with maximal magnetization at flip angles about 10 degrees lower than in balanced SSFP. The total scan time is increased by about 30% compared to conventional balanced SSFP. The new technique was applied on phantoms and volunteers to produce rapid, fat suppressed images.