Steady-state Free Precession Magnetic Resonance Imaging Research Articles

Technical note: A spiral fluid-attenuated inversion recovery magnetic resonance imaging technique for stereotactic radiosurgery treatment planning for trigeminal neuralgia.

Magnetic resonance imaging (MRI) is commonly used in treatment planning for stereotactic radiosurgery (SRS) of trigeminal neuralgia (TN). With current MRI techniques, the delineation of the trigeminal nerve root entry zone (REZ) may be degraded due to poor contrast and artifacts. The purpose of this work is to develop an MRI technique with better delineation of the trigeminal nerve REZ to improve SRS treatment planning for TN. A spiral fluid-attenuated inversion recovery (FLAIR) MRI technique was developed to improve image quality by improving tissue contrast, fluid suppression, artifact reduction, and signal-to-noise ratio (SNR). A concomitant-phase compensation method based on spiral gradient waveforms was implemented to minimize artifacts due to magnetic field change induced by the metal frame used in Gamma Knife treatment planning. The image quality of spiral FLAIR was assessed in four healthy volunteers. The geometric accuracy was quantitatively evaluated by registering spiral FLAIR to computed tomography (CT) images and comparing it with existing MRI techniques. The spiral FLAIR technique demonstrated better delineation of the trigeminal nerve REZ, improved tissue contrast of the brain stem, and minimized flow artifacts, compared to steady-state free precession (SSFP) MRI. Spiral FLAIR also improved fluid suppression, SNR, and artifacts, which contributed to better delineation of the trigeminal nerve REZ compared to conventional Cartesian FLAIR. The measured mean (± standard deviation) distance between spiral FLAIR and CT images is 0.98 ± 0.56mm, comparable to 0.40 ± 0.26mm in 3T T1 spoiled gradient echo (T1-SPGR), 0.59 ± 0.25mm in 3T SSFP, 0.66 ± 0.38mm in 1.5T T1-SPGR, and 0.61 ± 0.25mm in 1.5T Cartesian FLAIR. A spiral FLAIR technique with improved image quality and good geometric accuracy provides a potential alternative for treatment planning in SRS for TN patients.

Fetal dynamic magnetic resonance imaging using Doppler ultrasound gating for the assessment of the aortic isthmus: A feasibility study.

Cardiovascular magnetic resonance imaging (MRI) is established in cardiac evaluation in postnatal life, but its application to the fetus has been hampered by technical limitations. We aimed to investigate the feasibility of dynamic MRI of the fetal aortic isthmus using a magnetic resonance-compatible Doppler ultrasound device for cardiac gating. This prospective study included 19 fetuses at a median gestational age of 32.3weeks (range 26-38weeks). Imaging of the fetal aortic isthmus was assessed by (a) dynamic steady-state free precession MRI using a magnetic resonance-compatible Doppler ultrasound device for cardiac gating and (b) echocardiography. Diameters of the aortic isthmus were compared by two blinded observers. Magnetic resonance image quality was assessed independently by two observers using a four-point scale (1=low quality, 4=high quality). Furthermore, we performed four-dimensional flow MRI of the fetal aorta in three of these fetuses. The Doppler ultrasound device for cardiac gating allowed successful dynamic MRI examinations of the aortic isthmus in 18/19 (95%) fetuses. Evaluation of the fetal aortic isthmus was possible by both MRI (15/18, 83%) and echocardiography (16/18, 89%) (P<.05). Diameters of the aortic isthmus were concordant for MRI (3.8±0.9mm) and echocardiography (4.0±1.1mm), with a variability of 10.8% (bias -2.3%, 95% limits of agreement -23.9% to 19.3%). Overall magnetic resonance image quality was good (score 4 in 67% and score 3 in 23%) with good inter-observer agreement (κ=0.75; 95% CI 0.5-1). Fetal four-dimensional flow MRI allowed visualization of aortic flow dynamics. Doppler ultrasound-gating allows dynamic MRI of the fetal aorta with the potential to serve as a complementary imaging tool in cases where echocardiography is inconclusive.

How to train radiology residents to diagnose pulmonary embolism using a dedicated MRI protocol.

BackgroundIn recent years, magnetic resonance imaging (MRI) has been suggested as an alternative to computed tomography angiography (CTA) to diagnose pulmonary embolism (PE). In previous studies, only senior radiologists have been evaluated as reviewers.PurposeTo investigate if radiology residents can be trained to review MRI regarding PE and to determine the learning curve effects.Material and MethodsFour residents independently went through a training program consisting of 70 participants that had undergone steady-state free precession MRI. The individuals were randomized into ten training sessions. For each exam, the review time and presence or absence of embolus was recorded. After completing each session, the residents received feedback on diagnostic accuracy compared to a consensus reading by two specialists. The residents were also presented with the corresponding CTA.ResultsThe review time was nearly halved (P = 0.0002) during the training program. Comparing the first three sessions with the last three sessions for all residents, the review time decreased from 5:22 min to 2:51 min. The inter-reader agreement improved for all residents during the training program reaching a clinically acceptable level after seven sessions.ConclusionOur study suggests that radiology residents can be trained to independently review MRI investigations regarding PE within a short training program. Similar training programs could be more extensively used as effective teaching method for residents.

Kidney morphological parameters measured using noncontrast-enhanced steady-state free precession MRI with spatially selective inversion recovery pulse correlate with eGFR in patients with advanced CKD

BackgroundIt is well known that atrophic renal changes are associated with chronic kidney disease (CKD) progression, but conventional diagnostic imaging methods such as noncontrast-enhanced computed tomography and magnetic resonance imaging (MRI) have been insufficient for precisely assessing kidney function because they cannot clearly distinguish between the medulla and cortex. Hence, here we used noncontrast-enhanced steady-state free precession (SSFP) MRI with a spatially selective inversion recovery (IR) pulse to improve visibility for renal corticomedullary differentiation and evaluated the association between morphological parameters and kidney function in patients with CKD.MethodsKidney corticomedullary contrast ratio, cortical and medullary areas, and minimal cortical thickness of 107 patients with CKD G1–G5 were measured using SSFP MRI with a spatially selective IR pulse and the association between these morphological parameters and kidney function were evaluated.ResultsCorticomedullary contrast ratio was significantly improved on SSFP MRI compared with conventional in-phase T1-weighted gradient-echo MRI and positively correlated with estimated glomerular filtration ratio (eGFR), raw eGFR, and 24-h creatinine clearance. The medullary and cortical areas and minimal cortical thickness also positively correlated with those of kidney functional markers and the age. In patients with CKD and diabetes mellitus (DM), the correlation coefficients between raw eGFR and morphological parameters were higher than those in patients without DM, while minimal cortical thickness was larger in CKD patients with DM with a raw eGFR ≥ 45 mL/min.ConclusionKidney morphological parameters measured with SSFP MRI were clearly correlated with kidney function in patients with CKD, including those with advanced kidney dysfunction.

Investigation of renal corticomedullary differentiation with age-related change on non-contrast-enhanced MRI

To evaluate the relationship between renal corticomedullary differentiation, renal cortical thickness and age-related changes with non-contrast-enhanced steady-state free precession(SSFP) magnetic resonance imaging (MRI) and spatially selective inversion recovery(IR) pulse technology as well as its applied value . A total of 76 healthy volunteers had been recruited from August 2014 to June 2015 in First Hospital of China Medical University.All volunteers were divided into three groups: 2-40 years old, 41-60 years old, 61-80 years old. All 76 volunteers underwent non-contrast-enhanced steady-state free precession(SSFP) 3.0 T MRI scan using variable inversion times (TIs)(TI=1 000, 1 100, 1 200, 1 300, 1 400, 1 500, 1 600, 1 700 ms). The renal corticomedullary differentiation was observed and the signal intensity of renal cortex and medulla were measured respectively as well in order to calculate renal corticomedullary contrast ratio. Besides, renal cortical thickness and renal size were measured. All 76 volunteers were successfully performed all the sequences of MRI scan, including 152 useful imaging of kidney in total. The renal corticomedullary differentiation was clearly shown in all subjects. There was negative correlation between the optimal inversion time(TI) and age(r=-0.65, P<0.01). Similarly, negative correlation was observed between renal corticomedullary contrast ratio and age(r=-0.35, P<0.01). The mean renal cortical thickness of all subjects was (5.33±0.71)mm and there were statistically significant difference among those different groups, which was negative-related with age(r=-0.79, P<0.01). There was no statistically significant difference between sexuality and renal cortical thickness.Additionally, renal cortical thickness had no statistically significant difference in both sides of kidneys. The renal corticomedullary differentiation is depicted clearly by means of non-contrast-enhanced steady-state free precession MRI with spatially selective inversion recovery pulse technology. The optimal inversion time decreases along with the increase of age. In the meanwhile, the renal cortical thickness could be measured truthfully and accurately.

A Blinded, Case-Control Trial Assessing the Value of Steady State Free Precession Magnetic Resonance Imaging in the Diagnosis of Trigeminal Neuralgia

High-resolution magnetic resonance imaging (MRI) may be a useful and readily available adjunct in identifying trigeminal neuralgia secondary to vascular contact (TNVC). This study evaluated the reliability and predictive ability of 1.5-tesla steady state free precession (SSFP) MRI sequences for the diagnosis of symptomatic vascular contact and response to operative intervention in patients with TNVC. We performed a blinded, case-matched control trial evaluating SSFP MRI sequences in consecutive patients with unilateral TNVC with operatively proven vascular contact of the trigeminal nerve compared with healthy control subjects matched on age, sex, and laterality of the pathologic neurovascular complex. Interrater reliability was compared between 2 blinded, expert reviewers. Predictive ability of MRI was assessed in regard to accuracy, discrimination, and clinical utility. Inclusion criteria were met by 44 patients (22consecutive patients with TNVC and 22 matched control subjects). Interrater reliability ranged from fair to excellent for vessel contact (κ= 0.40), location (κ= 0.81), type (κ= 0.72), and multiplicity (κ= 0.31). Vascular contact on MRI sequences did not differ significantly between cases and controls (75% vs. 82%, P= 0.30). MRI demonstrates accurate (Brier 0.15) and good discriminatory ability for clinical response after microvascular decompression (area under the receiver operating characteristic curve 0.81, 95% confidence interval= 0.6-1.0). Decision-curve analysis demonstrated that MRI could result in a net reduction of 5 cases likely to be unsuccessful per 100 patients treated. These results suggest the utility of SSFP MRI lies not in the diagnosis of TNVC, but rather in stratifying the likelihood of response to microvascular decompression in patients with characteristic symptoms.

Clinical Applications of Cine Balanced Steady-State Free Precession MRI for the Evaluation of the Subarachnoid Spaces.

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.

Magnetic resonance estimates of the extent and heterogeneity of scar tissue in ICD patients with ischemic cardiomyopathy predict ventricular arrhythmia.

The majority of patients receiving implantable cardioverter-defibrillator (ICD) implantation under current guidelines never develop sustained ventricular arrhythmia; therefore, better markers of risk for sustained ventricular tachycardia and/or ventricular fibrillation are needed. The purpose of this study was to identify cardiac magnetic resonance arrhythmic risk predictors of ischemic cardiomyopathy before ICD implantation. Forty-three subjects (mean age, 64.5 ± 11.9 years) with previous myocardial infarction who were referred for ICD implantation were evaluated by cardiac magnetic resonance imaging (MRI). The MRI protocol included left ventricular functional parameter assessment using steady-state free precession and late gadolinium enhancement MRI using inversion recovery fast gradient echo. Left ventricular functional parameters were measured using cardiac magnetic resonance software. Subjects were followed up for 6-46 months, and the events of appropriate ICD treatments (shocks and antitachycardia pacing) were recorded. Twenty-eight patients experienced 46 spontaneous episodes during a median follow-up duration of 30 months. The total myocardial infarct (MI) size (18.05 ± 11.44 g vs 38.83 ± 19.87 g; P = .0006), MI core (11.63 ± 7.14 g vs 24.12 ± 12.73 g; P = .0002), and infarct gray zone (6.43 ± 4.64 g vs 14.71 ± 7.65 g; P = .0004) were significantly larger in subjects who received appropriate ICD therapy than in those who did not experience an episode of ventricular tachycardia and/or ventricular fibrillation. Multivariate regression analyses for the infarct gray zone and MI core adjusted for New York Heart Association class, diabetes, and etiology (primary or secondary prevention) revealed that the gray zone and MI core were predictors of appropriate ICD therapies (P = .0018 and P = .007, respectively). The extent of MI scar may predict which patients would benefit most from ICD implantation.

Measurement of renal cortical thickness using noncontrast‐enhanced steady‐state free precession MRI with spatially selective inversion recovery pulse: Association with renal function

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). Sixty-five patients with and without chronic kidney diseases (CKD) were investigated. Based on eGFR, patients were divided into three groups (Group 1, eGFR < 60; Group 2, eGFR = 60-90; and Group 3, eGFR > 90). All patients underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulses and minimal renal cortical thickness was measured. 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 < 0.01, r = 0.495). Noncontrast-enhanced SSFP MRI with a spatially selective IR pulse using optimal TI can improve the visibility of renal corticomedullary differentiation even in patients with renal insufficiency. The decrease in renal cortical thickness measured using this technique correlated significantly with eGFR.

Real‐time correction of rigid body motion‐induced phase errors for diffusion‐weighted steady‐state free precession imaging

Diffusion contrast in diffusion-weighted steady-state free precession magnetic resonance imaging (MRI) is generated through the constructive addition of signal from many coherence pathways. Motion-induced phase causes destructive interference which results in loss of signal magnitude and diffusion contrast. In this work, a three-dimensional (3D) navigator-based real-time correction of the rigid body motion-induced phase errors is developed for diffusion-weighted steady-state free precession MRI. The efficacy of the real-time prospective correction method in preserving phase coherence of the steady state is tested in 3D phantom experiments and 3D scans of healthy human subjects. In nearly all experiments, the signal magnitude in images obtained with proposed prospective correction was higher than the signal magnitude in images obtained with no correction. In the human subjects, the mean magnitude signal in the data was up to 30% higher with prospective motion correction than without. Prospective correction never resulted in a decrease in mean signal magnitude in either the data or in the images. The proposed prospective motion correction method is shown to preserve the phase coherence of the steady state in diffusion-weighted steady-state free precession MRI, thus mitigating signal magnitude losses that would confound the desired diffusion contrast.

MR Imaging–guided Electrophysiological Ablation Studies in Humans with Passive Catheter Tracking: Initial Results

To assess if real-time magnetic resonance (MR) imaging-guided radiofrequency (RF) ablation for atrial flutter is feasible in patients. The study complied with the Declaration of Helsinki and was approved by the local ethics committee. All patients were informed about the investigational nature of the procedures and provided written informed consent. Ten patients (six men; mean age ± standard deviation, 68 years ± 10) with symptomatic atrial flutter underwent isthmus ablation. In all patients, two MR imaging conditional steerable diagnostic and ablation catheters were inserted into the coronary sinus via femoral sheaths and into the right atrium with fluoroscopic guidance. The patients were then transferred to a 1.5-T whole-body MR imager for an ablation procedure, in which the catheters were manipulated by an electrophysiologist by using a commercially available interactive real-time steady-state free precession MR imaging sequence. All catheters were placed in standard positions successfully. Furthermore, simple programmed stimulation maneuvers were performed. In one of 10 patients, a complete conduction block was performed with MR imaging guidance. In nine of 10 patients, creating only a small number of additional touch-up lesions was necessary to complete the isthmus block with conventional fluoroscopy (median, three lesions; interquartile range, two to four lesions). Real-time MR imaging-guided placement of multiple catheters is feasible in patients, with subsequent performance of stimulation maneuvers and occasional complete isthmus ablation.

Age‐related change in renal corticomedullary differentiation: Evaluation with noncontrast‐enhanced steady‐state free precession (SSFP) MRI with spatially selective inversion pulse using variable inversion time

To evaluate age-related change in renal corticomedullary differentiation and renal cortical thickness by means of noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with spatially selective inversion recovery (IR) pulse. The Institutional Review Board of our hospital approved this retrospective study and patient informed consent was waived. This study included 48 patients without renal diseases who underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulse using variable inversion times (TIs) (700-1500 msec). The signal intensity of renal cortex and medulla were measured to calculate renal corticomedullary contrast ratio. Additionally, renal cortical thickness was measured. The renal corticomedullary junction was clearly depicted in all patients. The mean cortical thickness was 3.9 ± 0.83 mm. The mean corticomedullary contrast ratio was 4.7 ± 1.4. There was a negative correlation between optimal TI for the best visualization of renal corticomedullary differentiation and age (r = -0.378; P = 0.001). However, there was no significant correlation between renal corticomedullary contrast ratio and age (r = 0.187; P = 0.20). Similarly, no significant correlation was observed between renal cortical thickness and age (r = 0.054; P = 0.712). In the normal kidney, noncontrast-enhanced SSFP MRI with spatially selective IR pulse can be used to assess renal corticomedullary differentiation and cortical thickness without the influence of aging, although optimal TI values for the best visualization of renal corticomedullary junction were shortened with aging.

Magnetic Catheter Manipulation in the Interventional MR Imaging Environment

PurposeTo evaluate deflection capability of a prototype endovascular catheter, which is remotely magnetically steerable, for use in the interventional magnetic resonance (MR) imaging environment. Materials and MethodsCopper coils were mounted on the tips of commercially available 2.3–3.0-F microcatheters. The coils were fabricated in a novel manner by plasma vapor deposition of a copper layer followed by laser lithography of the layer into coils. Orthogonal helical (ie, solenoid) and saddle-shaped (ie, Helmholtz) coils were mounted on a single catheter tip. Microcatheters were tested in water bath phantoms in a 1.5-T clinical MR scanner, with variable simultaneous currents applied to the coils. Catheter tip deflection was imaged in the axial plane by using a “real-time” steady-state free precession MR imaging sequence. Degree of deflection and catheter tip orientation were measured for each current application. ResultsThe catheter tip was clearly visible in the longitudinal and axial planes. Magnetic field artifacts were visible when the orthogonal coils at the catheter tip were energized. Variable amounts of current applied to a single coil demonstrated consistent catheter deflection in all water bath experiments. Changing current polarity reversed the observed direction of deflection, whereas current applied to two different coils resulted in deflection represented by the composite vector of individual coil activations. Microcatheter navigation through the vascular phantom was successful through control of applied current to one or more coils. ConclusionsControlled catheter deflection is possible with laser lithographed multiaxis coil-tipped catheters in the MR imaging environment.

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

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. 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. 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). SSFP MRI with Time-SLIP can improve the visibility of renal corticomedullary differentiation without using contrast agents.

Limited, Fast Magnetic Resonance Imaging as an Alternative for Preoperative Evaluation of Pectus Excavatum

The purpose of this study was to determine the reliability, feasibility, and image quality of a limited, fast magnetic resonance imaging (MRI) protocol for preoperative evaluation of pectus excavatum in a pediatric population referred for presurgical imaging. A total of 47 patients, median age 14 years, referred for preoperative imaging of pectus excavatum, underwent axial balanced steady-state free precession MRI of the chest, with a limited patient charge. Two pediatric radiologists independently conducted a blinded retrospective study. The Haller and asymmetry indices were calculated at the level of greatest anterior-posterior chest narrowing. In addition, right heart compression and image quality were subjectively assessed, and scan duration was determined. Intraclass correlation coefficient reliability was between 0.85 and 0.98, indicating almost perfect agreement for quantitative measurements. Subjective evaluation of right heart compression and image quality showed moderate interreader agreement. Image quality was graded as good or excellent by both readers for all studies. No difference in the Haller index was observed between modalities in 3 patients on both computed tomographic scan and MRI (P = 0.2697). The median scan duration was 8 minutes. Limited MRI is a reliable and cost-effective alternative for preoperative assessment of pectus excavatum. It is fast, free of ionizing radiation, and there is excellent interreader reliability for measurements of chest wall deformity.

Correlation between ECG abnormalities and cardiac parameters in highly trained asymptomatic male endurance athletes: evaluation using cardiac magnetic resonance imaging

Intensive endurance training can induce abnormal ECG patterns at rest. These alterations are differentiated into minor, mildly or distinctly abnormal ECG patterns. Echocardiographic data imply a correlation between the extent of these alterations and cardiac parameters like cardiac volume or wall thickness. In comparison to echocardiography, cardiac magnetic resonance imaging (MRI) is characterized by high reproducibility and accuracy. The aim of this study was to investigate the correlation between ECG alterations and cardiac parameters in highly trained asymptomatic male endurance athletes as assessed using cardiac MRI. Forty-five asymptomatic male endurance athletes (mean age 40 ± 8.9 years., range 19-59 years., 13 ± 5 h of training per week) underwent a cardiac MRI examination in addition to a resting ECG. Based on the ECG patterns at rest, the athletes were divided into groups with normal or minor (group 1) and mild or distinct (group 2) alterations. Steady-state free-precession cine MRI was used to calculate left and right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass (MM). Late enhancement imaging was used to exclude structural alterations or myocardial scarring. Athletes in group 1 and 2 did not differ significantly in terms of age, height, body weight, body mass index or hours of training per week. Athletes with mildly or distinctly abnormal ECG patterns showed a significantly higher MM than athletes with minor ECG alterations at rest or normal resting ECG values (156.4 ± 18.4 g vs. 140.5 ± 20.0 g; p = 0.0103). The differences persisted when the values were corrected for body surface area (80.0 ± 7.4 g/m² vs. 73.4 ± 8.3 g; p = 0.0093). All other assessed cardiac parameters did not differ between the two groups. Pathological myocardial enhancement was detected only in one patient with a minor abnormal ECG. Male asymptomatic endurance athletes with mildly or distinctly abnormal ECG patterns at rest are characterized by a higher myocardial mass than comparable athletes with minor alterations or normal ECG at rest. Thus, the extent of ECG-abnormalities seems to be mainly the result of an increase in myocardial mass. Additionally, the absence of mild or distinct ECG alterations does not exclude the presence of pathological late gadolinium enhancement.

Accuracy of Right and Left Ventricular Functional Assessment by Short-Axis vs Axial Cine Steady-State Free-Precession Magnetic Resonance Imaging: Intrapatient Correlation With Main Pulmonary Artery and Ascending Aorta Phase-Contrast Flow Measurements

ObjectiveThe left ventricle (LV) is routinely assessed with cardiac magnetic resonance imaging (MRI) by using short-axis orientation; it remains unclear whether the right ventricle (RV) can also be adequately assessed in this orientation or whether dedicated axial orientation is required. We used phase-contrast (PC) flow measurements in the main pulmonary artery (MPA) and the ascending aorta (Aorta) as nonvolumetric standard of reference and compared RV and LV volumes in short-axis and axial orientations. MethodsA retrospective analysis identified 30 patients with cardiac MRI data sets. Patients underwent MRI (1.5 T or 3 T), with retrospectively gated cine steady-state free-precession in axial and short-axis orientations. PC flow analyses of MPA and Aorta were used as the reference measure of RV and LV output. ResultsThere was a high linear correlation between MPA-PC flow and RV–stroke volume (SV) short axis (r = 0.9) and RV-SV axial (r = 0.9). Bland-Altman analysis revealed a mean offset of 1.4 mL for RV axial and –2.3 mL for RV–short-axis vs MPA-PC flow. There was a high linear correlation between Aorta-PC flow and LV-SV short-axis (r = 0.9) and LV-SV axial (r = 0.9). Bland-Altman analysis revealed a mean offset of 4.8 m for LV short axis and 7.0 mL for LV axial vs Aorta-PC flow. There was no significant difference (P = .6) between short-axis–LV SV and short-axis–RV SV. ConclusionNo significant impact of the slice acquisition orientation for determination of RV and LV stroke volumes was found. Therefore, cardiac magnetic resonance workflow does not need to be extended by an axial data set for patients without complex cardiac disease for assessment of biventricular function and volumes.

Lung Morphology Assessment with Balanced Steady-State Free Precession MR Imaging Compared with CT

To evaluate the utility of 1.5-T noncontrast magnetic resonance (MR) imaging of the lung parenchyma and to compare it with computed tomography (CT) in the assessment of interstitial lung disease and other morphologic lung abnormalities. Institutional review board approval was obtained for retrospective image analysis. A total of 236 patients who underwent MR imaging and CT as part of their assessment for suspected pulmonary hypertension were included in this study. Lung MR imaging was performed with a 1.5-T system as a stack of axial two-dimensional balanced steady-state free precession (bSSFP) acquisitions. Two radiologists independently evaluated CT and MR images for various morphologic abnormalities, such as pulmonary fibrosis, pleural and mediastinal disease, solid lesions, bronchial disease, and emphysema. Κ statistics were used to measure interobserver agreement. Sensitivity and specificity of MR imaging in the identification of pulmonary fibrosis (n = 46) were 89% (95% confidence interval: 77%, 96%) and 91% (95% confidence interval: 76%, 98%), respectively, when compared with CT. In comparison to CT, MR imaging depicted 75% of ground-glass opacities. Nine of the 12 noncalcified nodules were identified on MR images. Lung nodules (75%, κ = 0.71) and effusions (100%, κ = 0.89) were also well visualized on MR images. MR imaging was however less effective in depicting emphysema (16%, κ = 0.60) and minor fibrosis (67%, κ = 0.79). This study shows bSSFP MR imaging is inferior to CT in imaging parenchymal lung disease; however, this study does demonstrate for the first time a potential role for the bSSFP sequence as an alternative radiation-free noncontrast imaging modality for use in patients with pulmonary fibrosis.

Determination of right ventricular volume and function using multiple axially rotated MRI slices

The conventional magnetic resonance imaging (MRI) method for right ventricular (RV) volume and motion, using short-axis (SA) orientation, is limited by RV anatomy and shape. We suggest an orientation based on six slices rotated around the long axis of the RV, rotated long axis (RLA). Three phantoms were investigated in SA and RLA using cine balanced steady-state free precession MRI. Volumes were calculated based on segmentation and checked against true volumes. In 23 healthy male volunteers, we used six long-axis planes from the middle of the tricuspid valve to the RV apex, rotated in 30° increments. For comparison, short-axis slices were acquired. Imaging parameters were identical in both acquisitions. Right ventricular end-diastolic (EDV), end-systolic (ESV) and stroke volumes (SV) determined in the RLA 179.1 ± 29.3; 80.1 ± 17.1; 99.3 ± 16.9 ml and in the SA were 174.0 ± 21.1; 78.8 ± 13.6; 95.3 ± 14.5 ml with P-values for the difference from 0.17 to 0.64 (ns). Interobserver variability ranged between 3.2% and 6.6% and intraobserver variability between 2.8% and 6.8%. In SA views, consensus for the definition of the basal slice was necessary in 39% of the volunteers for whom the average volume change was 20% in ESV and 10% in EDV. The RLA method results in better visualization and definition of the RV inflow, outflow and apex. Accurate measurement of RV volumes for diagnosis and follow-up of cardiac diseases are enhanced by the RLA orientation, even though additional acquisition time is required.

Dynamic visualization of arachnoid adhesions in a patient with idiopathic syringomyelia using high‐resolution cine magnetic resonance imaging at 3T

A 39-year-old female patient with thoracic syringomyelia underwent routine magnetic resonance imaging (MRI) and 3 T MRI to investigate the value of retrospectively cardiac-gated cine steady-state free precession (SSFP) MRI in the preoperative and postoperative diagnosis of arachnoid membranes in the spinal subarachnoid space. Therefore, 3T MRI included sagittal and transverse retrospectively cardiac-gated cine balanced fast-field echo (balanced-FFE) sequences both preoperatively and after microsurgical lysis of arachnoid adhesions and expansive duraplasty. Arachnoid membranes were detected and this result was correlated with intraoperative findings and the results of routine cardiac-gated phase-contrast cerebrospinal fluid (CSF) flow MRI. Retrospectively cardiac-gated cine SSFP MRI enabled imaging of arachnoid membranes with high spatial resolution and sufficient contrast to delineate them from hyperintense CSF preoperatively and postoperatively. The images were largely unaffected by artifacts. Surgery confirmed the presence of arachnoid adhesions in the upper thoracic spine. Not all arachnoid membranes that were seen on cine balanced-FFE sequences caused significant spinal CSF flow blockages in cardiac-gated phase-contrast CSF flow studies. In conclusion, retrospectively cardiac-gated cine SSFP MRI may become a valuable tool for the preoperative detection of arachnoid adhesions and the postoperative evaluation of microsurgical adhesiolysis in patients with idiopathic syringomyelia.