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OBJECTIVE. The purpose of the present study was to compare the diagnostic performance of an abbreviated MR enterography (MRE) protocol consisting of balanced steady-state free-precession (b-SSFP) imaging only versus standard full-protocol MRE for the evaluation of Crohn disease activity. MATERIALS AND METHODS. This single-center retrospective study included 112 patients with Crohn disease (66 women and 46 men; age range, 18-84 years) who underwent MRE between January 2017 and March 2018. Utilizing binary and 5-point Likert confidence scales, two blinded readers independently interpreted and scored disease activity on b-SSFP sequences only and on full-protocol MRE images. Interreader and intrareader agreement on confidence regarding disease activity were calculated using weighted kappa indexes. Correlation between MRE findings of Crohn disease and the Harvey-Bradshaw index was also performed. RESULTS. Perfect intrareader agreement and strong interreader agreement on disease activity were observed (intrareader agreement: κ = 0.97, 0.96, and 0.96 for reader A, reader B, and both readers combined; interreader agreement: κ = 0.82 for b-SSFP imaging only and κ = 0.81 for MRE). For detecting active Crohn disease, b-SSFP sequences had a sensitivity and specificity of 97% and 100%, respectively, for reader A and 98% and 86%, respectively, for reader B. Strong-to-perfect intrareader agreement was achieved between b-SSFP imaging only and MRE for identification of penetrating disease (κ = 0.80 and 0.97) and stenosing disease (κ = 0.87 and 0.95). Perfect intrareader agreement was also obtained between b-SSFP imaging only and MRE for detecting abnormal bowel segments (κ = 0.91 for reader A; κ = 0.98 for reader B). Weak agreement was noted between both b-SSFP imaging only and MRE versus the Harvey-Bradshaw index (κ = 0.08 of reader A; κ = 0.04 for reader B). CONCLUSION. Robust agreement was observed between b-SSFP imaging only and full-protocol MRE for the assessment of Crohn disease activity and complications. An abbreviated MRE protocol that exclusively uses b-SSFP sequences appears feasible and has significant implications for health care resources.

Purpose: Quantitative magnetization transfer (qMT) imaging can be used to quantify the proportion of protons in a voxel attached to macromolecules. Here, we show that the original qMT balanced steady-state free precession (bSSFP) model is biased due to over-simplistic assumptions made in its derivation. Theory and Methods: We present an improved model for qMT bSSFP, which incorporates finite radiofrequency (RF) pulse effects as well as simultaneous exchange and relaxation. Further, a correction to finite RF pulse effects for sinc-shaped excitations is derived. The new model is compared to the original one in numerical simulations of the Bloch-McConnell equations and in previously acquired in-vivo data. Results: Our numerical simulations show that the original signal equation is significantly biased in typical brain tissue structures (by 7-20 %) whereas the new signal equation outperforms the original one with minimal bias (< 1 %). It is further shown that the bias of the original model strongly affects the acquired qMT parameters in human brain structures, with differences in the clinically relevant parameter of pool-size-ratio of up to 31 %. Particularly high biases of the original signal equation are expected in an MS lesion within diseased brain tissue (due to a low T2/T1-ratio), demanding a more accurate model for clinical applications. Conclusion: The improved model for qMT bSSFP is recommended for accurate qMT parameter mapping in healthy and diseased brain tissue structures.

PURPOSE: To optimize 19 F imaging pulse sequences for perfluoropropane (C3 F8 ) gas human lung ventilation MRI considering intrinsic in vivo relaxation parameters at both 1.5T and 3T. METHODS: Optimization of the imaging parameters for both 3D spoiled gradient (SPGR) and steady-state free precession (SSFP) 19 F imaging sequences with inhaled 79% C3 F8% and 21% oxygen was performed. Phantom measurements were used to validate simulations of SNR. In vivo parameter mapping and sequence optimization and comparison was performed by imaging the lungs of a healthy adult volunteer. T1 and T2* mapping was performed in vivo to optimize sequence parameters for in vivo lung MRI. The performance of SSFP and SPGR was then evaluated in vivo at 1.5T and 3T. RESULTS: The in vivo T2* of C3 F8 was shown to be dependent upon lung inflation level (2.04 ms ± 36% for residual volume and 3.14 ms ± 28% for total lung capacity measured at 3T), with lower T2* observed near the susceptibility interfaces of the diaphragm and around pulmonary blood vessels. Simulation and phantom measurements indicate that a factor of ~2-3 higher SNR can be achieved with SSFP when compared with optimized SPGR. In vivo lung imaging showed a 1.7 factor of improvement in SNR achieved at 1.5T, while the theoretical improvement at 3T was not attained due to experimental SAR constraints, shorter in vivo T1 , and B0 inhomogeneity. CONCLUSION: SSFP imaging provides increased SNR in lung ventilation imaging of C3 F8 demonstrated at 1.5T with optimized SSFP similar to the SNR that can be obtained at 3T with optimized SPGR.

Background While low-field MRI is disadvantaged by a reduced signal-to-noise ratio (SNR) compared to higher fields, it has a number of useful features such as decreased SAR and shorter T1, and has shown promise for diagnostic imaging. This study demonstrates the feasibility of cardiac balanced steady-state free precession (bSSFP) MRI at 0.35 T and compares cardiac bSSFP MRI images at 0.35 T with those at 1.5 T. Methods Cardiac images were acquired in 7 healthy volunteers using an ECG-gated bSSFP cine sequence on a 0.35 T superconducting MR system as well as a clinical 1.5 T system. Blood and myocardium SNR and contrast-to-noise ratio (CNR) were computed. Subjective image scoring was used to compare the image quality between 0.35 and 1.5 T. Results Cardiac images at 0.35 T were successfully acquired in all volunteers. While the 0.35 T images were noisier than those at 1.5 T, blood, myocardium and papillary muscles could be clearly delineated. At 0.35 T, bSSFP images were acquired at flip angles as high as 150°. Maximum CNR was achieved at 130°. Image quality scoring showed that while at lower flip angles, the 0.35 T images had poorer quality than the 1.5 T, but with flip angles of 110 and 130, the image quality at 0.35 T had scores similar to those at 1.5 T. Conclusions This study demonstrates that cardiac bSSFP imaging is highly feasible at 0.35 T.

The purpose of this article is to review the physiology of normal brain and spinal cord motion in the subarachnoid space, principles of cine balanced steady-state free precession (bSSFP) magnetic resonance imaging (MRI), clinical applications, and the pitfalls encountered with this technique. The brain and spinal cord are dynamic structures that move with each heartbeat due to transmitted arterial pulse waves. Conventional MRI sequences do not allow anatomic evaluation of the pulsatile movement of the neural structures in the subarachnoid space due to limitations in temporal resolution. Cine bSSFP MRI uses cardiac gating to evaluate dynamically the brain and spinal cord with high contrast and temporal resolution.Cine bSSFP can be used in the evaluation of idiopathic syringomyelia to assess an underlying treatable cause, including arachnoid bands, which are usually not well visualized with conventional MR sequences due to motion artifact. This MRI technique is also useful in the evaluation of intraspinal and intracranial arachnoid cysts and the degree of mass effect on the cord. Other applications include preoperative and postoperative evaluation of Chiari I malformation and the evaluation of lateral ventricular asymmetry. The major limitation of cine bSSFP is the presence of banding artifacts, which can be reduced by shimming and modifying other scan parameters.

Background Dual-phase 3-dimensional whole-heart acquisition allows simultaneous imaging during systole and diastole. Respiratory navigator gating and tracking of the diaphragm is used with limited accuracy. Prolonged scan time is common, and navigation often fails in patients with erratic breathing. Image-navigation (iNAV) tracks movement of the heart itself and is feasible in single phase whole heart imaging. To evaluate its diagnostic ability in congenital heart disease, we sought to apply iNAV to dual-phase sequencing. Methods Healthy volunteers and patients with congenital heart disease underwent dual-phase imaging using the conventional diaphragmatic-navigation (dNAV) and iNAV. Acquisition time was recorded and image quality assessed. Sharpness and length of the right coronary (RCA), left anterior descending (LAD), and circumflex (LCx) arteries were measured in both cardiac phases for both approaches. Qualitative and quantitative analyses were performed in a blinded and randomized fashion. Results In volunteers, there was no significant difference in vessel sharpness between approaches (p > 0.05). In patients, analysis showed equal vessel sharpness for LAD and RCA (p > 0.05). LCx sharpness was greater with dNAV (p

Purpose To assess whether noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with a spatially selective inversion recovery (IR) pulse can improve the visibility of renal corticomedullary differentiation in patients showing renal dysfunction, and to investigate the correlation between renal cortical thickness and estimated glomerular filtration rate (eGFR). Materials and Methods Sixty-five patients with and without chronic kidney diseases (CKD) were investigated. Based on eGFR, patients were divided into three groups (Group 1, eGFR 90). All patients underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulses and minimal renal cortical thickness was measured. Results The mean corticomedullary contrast ratio was significantly higher in SSFP images with optimal TI than in in-phase images in all three groups (P = 0.001). Positive correlation was seen between the corticomedullary contrast ratio in SSFP images with optimal TI and eGFR (P = 0.011, r = 0.314). A significantly positive correlation was observed between minimal renal cortical thickness and eGFR (P

Balanced steady state free precession (balanced SSFP) has become increasingly popular for research and clinical applications, offering a very high signal-to-noise ratio and a T2 /T1 -weighted image contrast. This review article gives an overview on the basic principles of this fast imaging technique as well as possibilities for contrast modification. The first part focuses on the fundamental principles of balanced SSFP signal formation in the transient phase and in the steady state. In the second part, balanced SSFP imaging, contrast, and basic mechanisms for contrast modification are revisited and contemporary clinical applications are discussed.

The balanced steady-state free precession (bSSFP) MR sequence is frequently used in clinics, but is sensitive to off-resonance effects, which can cause banding artifacts. Often multiple bSSFP datasets are acquired at different phase cycling (PC) angles and then combined in a special way for banding artifact suppression. Many strategies of combining the datasets have been suggested for banding artifact suppression, but there are still limitations in their performance, especially when the number of phase-cycled bSSFP datasets is small. The purpose of this study is to develop a learning-based model to combine the multiple phase-cycled bSSFP datasets for better banding artifact suppression. Multilayer perceptron (MLP) is a feedforward artificial neural network consisting of three layers of input, hidden, and output layers. MLP models were trained by input bSSFP datasets acquired from human brain and knee at 3T, which were separately performed for two and four PC angles. Banding-free bSSFP images were generated by maximum-intensity projection (MIP) of 8 or 12 phase-cycled datasets and were used as targets for training the output layer. The trained MLP models were applied to another brain and knee datasets acquired with different scan parameters and also to multiple phase-cycled bSSFP functional MRI datasets acquired on rat brain at 9.4T, in comparison with the conventional MIP method. Simulations were also performed to validate the MLP approach. Both the simulations and human experiments demonstrated that MLP suppressed banding artifacts significantly, superior to MIP in both banding artifact suppression and SNR efficiency. MLP demonstrated superior performance over MIP for the 9.4T fMRI data as well, which was not used for training the models, while visually preserving the fMRI maps very well. Artificial neural network is a promising technique for combining multiple phase-cycled bSSFP datasets for banding artifact suppression.

MRI has become the primary tool for assessment of myocardial inflammation in patients with suspected acute myocarditis. Optimal diagnostic performance is achieved with late gadolinium-enhanced sequences, but cine balanced steady-state free precession (SSFP) MRI sequences are routinely used to evaluate cardiac function. Our aim was to prospectively assess the diagnostic value of unenhanced and contrast-enhanced cine SSFP MRI sequences in comparison with late gadolinium-enhanced sequences for imaging of patients with strong evidence of acute myocarditis.Eighteen patients with strong evidence of acute myocarditis underwent 1.5-T cardiac MRI. Unenhanced and contrast-enhanced cine SSFP images and late gadolinium-enhanced images were obtained. The images were analyzed both qualitatively and quantitatively. Data were analyzed with analysis of variance and the Bonferroni test or paired Student t test.Areas of high signal intensity were detected in 28% (5/18), 94% (17/18), and 89% (16/18) of patients on unenhanced cine, contrast-enhanced cine, and late gadolinium-enhanced images. In one patient, contrast-enhanced cine images revealed subepicardial areas of high signal intensity that were not visible on late gadolinium-enhanced images. The location and transmural nature of involved segments matched on contrast-enhanced cine and late gadolinium-enhanced images (both, r = 0.91, p0.0001). The contrast-to-noise ratio was significantly higher on contrast-enhanced cine images than on late gadolinium-enhanced images (p0.05).Contrast-enhanced cine MRI is a valuable tool for detection of lesions of acute myocarditis and should be recommended for routine clinical MRI.

Purpose: To validate a novel, real-time, steady-state free precession (SSFP), single-breathhold technique for the assessment of left ventricular (LV) and right ventricular (RV) function in heart failure patients. Materials and Methods: A total of 20 heart failure patients (mean age 59 17 years) underwent scanning with our new, real-time, spiral SSFP sequence in which each cardiac phase was acquired in 118 msec at a resolution of 1.8 1.8 mm. Each cardiac slice (1-cm thick) was automatically advanced based on a cardiac trigger, allowing complete coverage of the heart in a single breathhold. The patients also underwent LV and RV assessment with the gold standard: multiple breathhold, cardiac-gated, segmented k-space strategy. LV and RV end-systolic volume (ESV) and enddiastolic volume (EDV) and LV mass were compared between the two imaging techniques. Results: The new real-time strategy was highly concordant with the gold standard technique in the assessment of LVEDV (r 0.98), LVESV (r 0.98), RVESV (r 0.86), RVEDV (r 0.91), LVMASS (r 0.95), RVEF (r 0.70), and LVEF (r 0.94). The mean bias (95% confidence interval [CI]) for each parameter is LVEDV: 10.6 cc (cm 3 ) (3.8 –17.4 cc), LVESV: – 0.8 cc (–5.3 to 3.7 cc), RVEDV: 3.7 cc (–5.6 to 13.2 cc), RVESV: –3.1 cc (–11.1 to 4.9 cc), LVMASS: 26 g (12.4 –39.8 g), RVEF: –2.9% (1.3 to –7.2 %), LVEF: 1.9% (5 to –1.1%). In addition, data acquisition was only nine two seconds with the real-time strategy vs. 312 41 seconds for the standard technique. Conclusion: In patients with heart failure, real-time, spiral SSFP allows rapid and accurate assessment of RV and LV function in a single-breath hold. Using the same strategy, increased temporal resolution will allow real-time assessment of cardiac wall motion during stress studies.

Objectives:(1) Compare noncontrast steady-state free precession (SSFP, also called FIESTA, CISS, and bFFE) magnetic-resonance imaging (MRI) to contrast-enhanced full sequence MRI for initial evaluation of retrocochlear pathology. (2) Assess the sensitivity and specificity of SSFP alone versus complete contrast-enhanced MRI as the gold standard.Methods:Retrospective review of a tertiary care center radiology imaging database from 2006 to present was performed. Based on statistical power analysis, 50 studies with identified vestibular schwannomas and 53 studies with normal internal auditory canal (IAC) findings were included. Four expert reviewers performed blinded, randomized evaluation of non-contrast SSFP sequence and contrast-enhanced MRI studies to evaluate for retrocochlear pathology. MRI reports from the original studies were used as the gold standard. Using XLSTAT™ statistical software, data were analyzed using a 2-sided z-test of one proportion for each reviewer’s sensitivity and specificity agains...

Background: The radial long-axis orientation for the measurement of left ventricular (LV) volume and mass has been shown to have advantages over the short-axis orientation. Previous work has highlighted the need for technique specific normal ranges. The purpose of this study was therefore to establish normal ranges of LV volume and mass for the radial long-axis orientation. Materials and methods: Forty normal subjects (20 males, average age 32.3, age range 19–58; 20 females, average age 37.4, age range 21–54) were examined utilising a steady state free precession (SSFP) pulse sequence. Two observers analysed the images independently using in-house validated software. Results: The normal ranges for LV end-diastolic volume measurements after adjustment to body surface area (BSA) were 62–120 ml for males and 58–103 ml for females. LV mass indexed to BSA ranged from 50–86 g for males and 36–72 g for females. The normal range for ejection fraction was 49–73 % for males and 54–73 % for females. Conclusion: A gender specific normal range using SSFP in the radial long-axis orientation was established.

Our objective was to evaluate variable-bandwidth steady-state free-precession (VBSSFP) MRI in characterization of epidermoid tumors and arachnoid cysts. Axial conventional spin-echo and VBSSFP MR images were obtained in 12 patients with epidermoid tumors and 23 with arachnoid cysts and examined for ability to characterize these two lesions and to delineate lesion margin. On conventional spin-echo MRI, characterization of epidermoid tumor and arachnoid cyst was occasionally difficult, because of atypical cases. On VBSSFP MRI, lesion characterization was improved by recognition of two distinct patterns of internal texture and margins of the lesions could be separated from surrounding cerebrospinal fluid. The 25 operated cases confirmed the imaging impression. VBSSFP MRI complements conventional spin-echo imaging to help characterize epidermoid tumors and arachnoid cysts. The improved characterization of these cystic masses with VBSSFP MRI can help radiologists and surgeons establish more accurate preoperative diagnoses and more appropriate treatment plans.