Steady-state Free Precession Magnetic Resonance Research Articles

Do Knee-Straining Activities Influence the Subchondral Bone Microarchitecture and Accelerate Knee Osteoarthritis Progression?

Knee overload was detrimental to knee osteoarthritis subjects. We aim to analyze the association between the subchondral bone microarchitecture sclerosis and typical knee-straining activities. The frequency of experiencing squatting, kneeling, lifting, and climbing of 481 knee osteoarthritis subjects was investigated. Subchondral bone microarchitecture (bone volume fraction, trabecular thickness, trabecular separation, and trabecular number) was measured by the fast imaging with steady-state free precession magnetic resonance imaging applying trabecular sequencing, at baseline and 12-mo follow-up. Logistic regression was conducted to investigate the relationship between microarchitecture change and each knee-straining activity, adjusted by age, sex, weight, and Kellgren-Lawrence grade. All data were from the Osteoarthritis Initiative. Long kneeling was associated with increased bone volume fraction (adjusted odds ratio = 1.16, confidence interval = 1.01-1.33) and trabecular number (adjusted odds ratio = 1.16, confidence interval = 1.02-1.33). Long squatting was associated with a lower risk of increased trabecular separation (adjusted odds ratio = 0.84, confidence interval = 0.71-0.98) and a higher risk of increased trabecular thickness (adjusted odds ratio = 1.29, confidence interval = 1.06-1.55). Long squatting also increased the medial compartment joint width narrowing (-0.21 in squatting group vs -0.03 in no squatting group, P < 0.05). Knee osteoarthritis patients should avoid long squatting and kneeling, and subchondral bone microarchitecture possesses excellent potential as a monitoring indicator in subjects who kneel or squat for long.

Decelerated Dark Flow Measured Using Steady-State Free Precession Magnetic Resonance Imaging for Specific Detection of Left Ventricular Myocardial Strain and Dyssynchrony in Dilated Cardiomyopathy

Decelerated Dark Flow Measured Using Steady-State Free Precession Magnetic Resonance Imaging for Specific Detection of Left Ventricular Myocardial Strain and Dyssynchrony in Dilated Cardiomyopathy

Normal values for paediatric atrial volumes assessed by steady-state free-precession cardiovascular magnetic resonance

Abstract Background Measurement of atrial volumes by steady-state free precession (SSFP)cardiovascular magnetic resonance (CMR) is becoming increasingly important in the treatment and follow-up of paediatric congenital heart disease. It has prognostic value in terms of heart failure and cardiovascular death. However, CMR normal values for the clinically often used mono- and biplane area-length method in children are lacking. Aims We sought to create paediatric normal values for atrial volumes using the mono- and biplane area-length method. Methods In a retrospective study design, CMR data sets of 157 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. In a four-chamber (4ch-) view, left and right atrial (LA, RA) endocardial borders were segmented during end-diastole and end-systole to calculate minimal and maximal atrial volumes (LAmin, LAmax, RAmin, RAmax) using the monoplane area-length method. Additionally, end-diastolic and end-systolic LA endocardial borders were segmented in a two-chamber (2ch-) view. Using the measurements from the 2ch- and 4ch-views, minimal and maximal LA volumes were calculated using the biplane area-length method. Atrial volumes were normalized for body surface area (BSA in m2). Sex-specific reference curves were created using the lambda mu sigma method. Results The median age was 13.8±2.81 years (53 girls). In children from 4–10 years average atrial volumes measured: monoplane 4ch: LAmin 10.2±3.5 ml/m2, LAmax 28.8±7.4 ml/m2, RAmin 14.1±6.3 ml/m2, RAmax 27.0±11.4 ml/m2; monoplane 2ch: LAmin 10.9±4.1 ml/m2, LAmax 27.0±6.1 ml/m2; biplane: LAmin 10.2±3.3 ml/m2, LAmax 27.4±5.7 ml/m2. In children from 11–18 years average atrial volumes measured: monoplane 4ch: LAmin 13.6±4.9 ml/m2, LAmax 34.1±9.1 ml/m2, RAmin 19.2±6.8 ml/m2, RAmax 34.2±9.6 ml/m2; monoplane 2ch: LAmin 13.2±4.9 ml/m2, LAmax 31.4±9.7 ml/m2; biplane: LAmin 12.9±4.4 ml/m2, LAmax 31.8±8.8 ml/m2. Separate centile charts and centile tables for boys and girls for all volumetric parameters were created. Conclusion We provide paediatric CMR reference values for atrial volumes. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes. Funding Acknowledgement Type of funding sources: None.

Use of compressed sensing to reduce scan time and breath-holding for cardiac cine balanced steady-state free precession magnetic resonance imaging in children and young adults.

Conventional pediatric volumetric MRI acquisitions of a short-axis stack typically require multiple breath-holds under anesthesia. Here, we aimed to validate a vendor-optimized compressed-sensing approach to reduce scan time during short-axis balanced steady-state free precession (bSSFP) cine imaging. Imaging was performed in 28 patients (16±9years) in this study on a commercial 3-tesla (T) scanner using retrospective electrocardiogram-gated cine bSSFP. Cine short-axis images covering both ventricles were acquired with conventional parallel imaging and a vendor-optimized parallel imaging/compressed-sensing approach. Qualitative Likert scoring for blood-myocardial contrast, edge definition, and presence of artifact was performed by two experienced radiologists. Quantitative comparisons were performed including biventricular size and function. A paired t-test was used to detect significant differences (P<0.05). Scan duration was 7±2s/slice for conventional imaging (147±33s total) vs. 4±2s/slice for compressed sensing (83±28s total). No significant differences were found with qualitative image scores for blood-myocardial contrast, edge definition, and presence of artifact. No significant differences were found in volumetric analysis between the two sequences. The number of breath-holds was 10±4 for conventional imaging and 5±3 for compressed sensing. Compressed sensing allowed for a 50% reduction in the number of breath-holds and a 43% reduction in the total scan time without differences in the qualitative or quantitative measurements as compared to the conventional technique.

Assessment of Intrafraction Cervico-Uterine Motion in the Definitive Treatment of Locally Advanced Cervical Cancer Using MR-Guided Radiotherapy

To account for intrafraction motion, patients receiving intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer have an internal target volume (ITV) defined from bladder-full and bladder-empty CT simulation scans. We hypothesized that through daily volumetric magnetic resonance (MR) imaging for setup and treatment, we can assess cervico-uterine motion and create an intrafraction-ITV independent of interfraction bladder changes, and therefore dispense with the full-bladder to empty-bladder ITV paradigm. In this IRB-approved, study patients with locally advanced cervical cancer received IMRT with brachytherapy. IMRT was delivered on a clinical MR-guided radiotherapy (MRgRT) Linac. All patients received a pre-treatment (pre-tx) and post-treatment (post-tx) 0.35T balanced steady-state free precession MR scans in treatment position. The intrafraction cervico-uterine motion was assessed through segmentation of the clinical target volume (CTV) by a gynecological radiation oncologist on each scan. The pre-tx and post-tx MR scans were in the same frame of reference, and any residual patient motion was removed through a rigid registration of the post-tx MR scan to the pre-tx MR scan based on bony anatomy. All post-tx contours were rigidly copied to the pre-tx MR scans. The maximum and mean difference in spatial position between the pre-tx and post-tx MR scans were quantified using maximum Hausdorff distance (HD) and mean distance to agreement (MDA), respectively. Mean, standard deviation, and 95% confidence interval were calculated to determine the intrafraction MR-based internal target volume (ITVMRgRT). In total, 19 same day sessions (N = 38 scans) of intrafraction motion were assessed. Minimal patient voluntary motion was observed across rigid registrations with respect to bony anatomy. The average time between the pre-tx and post-tx MR scans was 14.3 ± 7.1 minutes (mean ± standard deviation), resembling a hypothetical time of on-table adaptation and treatment. The average maximum HD was 0.88 ± 0.46 cm (95% CI 0.668 - 1.08) and average MDA was 0.08 ± 0.07 cm (95% CI 0.05- 0.118). Due to HD’s sensitivity to outliers, a more robust metric (i.e., MDA) was utilized for margin calculation. The ITVMRgRT margin necessary to encompass the MDA for 95% of the intrafraction motion was 0.12 cm; therefore, we propose an ITVMRgRT of 0.15 cm given the non-partial voxelization of segmentation. This work supports margin reduction of the ITV to ITVMRgRT of 0.15 cm when using daily MR-guided online adaptive radiotherapy. Given the maximum setup uncertainty is limited in MRgRT to spatial resolution of the real-time cine imaging sequence, we propose an ITVMRgRT-PTV margin of 0.3 cm. Therefore, our total CTV to PTV margin is 0.45 cm.

MRF-ZOOM for the unbalanced steady-state free precession (ubSSFP) magnetic resonance fingerprinting

In magnetic resonance fingerprinting (MRF), tissue parameters are determined by finding the best-match to the acquired MR signal from a predefined signal dictionary. This dictionary searching (DS) process is generally performed in an exhaustive manner, which requires a large predefined dictionary and long searching time. A fast MRF DS algorithm, MRF-ZOOM, was recently proposed based on DS objective function optimization. As a proof-of-concept study, MRF-ZOOM was only tested with one of the earliest MRF sequences but not with the recently more popular unbalanced steady state free precession MRF sequence (MRF-ubSSFP, or MRF-FISP). Meanwhile noise effects on MRF and MRF-ZOOM have not been examined. The purpose of this study was to address these open questions and to verify whether MRF-ZOOM can be combined with a dictionary-compression based method to gain further speed. Numerical simulations were performed to evaluate the DS objective function properties, noise effects on MRF, and to compare MRF-ZOOM with other methods in terms of speed and accuracy. In-vivo experiments were performed as well. Evaluation results showed that premises of MRF-ZOOM held for MRF-FISP; noise did not affect MRF-ZOOM more than the conventional MRF method; when SNR ≥ 1, MRF quantification yielded accurate results. Dictionary compression introduced quantification errors more to T2 quantification. MRF-ZOOM was thousands of times faster than the conventional MRF method. Combining MRF-ZOOM with dictionary compression showed no benefit in terms of fitting speed. In conclusion, MRF-ZOOM is valid for MRF- FISP, and can remarkably save MRF dictionary generation and searching time without sacrificing matching accuracy.

276Non contrast 3D steady-state free-precession magnetic resonance angiography: the more relevant magnetic resonance technique for the assessment prior to Ross procedure?

276Non contrast 3D steady-state free-precession magnetic resonance angiography: the more relevant magnetic resonance technique for the assessment prior to Ross procedure?

Validation of contrast enhanced cine steady-state free precession and T2-weighted CMR for assessment of ischemic myocardial area-at-risk in the presence of reperfusion injury.

The purpose of the study was to validate by histopathology, contrast enhanced cine steady-state free precession and T2-weighted CMR for the assessment of ischemic myocardial area-at-risk (AAR) in the presence of microvascular obstruction (MVO). Eleven anesthetized pigs underwent CMR 7 to 10 days post infarction. The area-at-risk was measured from T2-weighted fast spin echo (T2-STIR) and contrast-enhanced steady-state free precession magnetic resonance imaging (CE-SSFP) images using semi-automated algorithms based on a priori knowledge of perfusion territory. Also, late gadolinium enhancement (LGE) was performed to measure final infarct size (FIS). Histopathological comparison with Evans blue dye to define AAR and triphenyltetrazolium chloride to define FIS served as the reference. All infarcts demonstrated MVO on LGE images. Bland-Altman analysis showed no significant bias in AAR or myocardial salvage between T2-STIR and CE-SSFP or between CMR and histopathology. The mean differences ± 2SD from Bland-Altman analysis were: AAR: Evans Blue vs. T2-STIR [0.7%; +13.5%; -12.1%]; AAR: Evans Blue vs. CE-SSFP [0.1%; +13.8%; -13.7%]; AAR: T2-STIR vs. CE-SSFP [0.7%; +6.2%; -4.9%]; Salvage: Evans Blue-TTC vs. T2-STIR-LGE [0.8%; +11.1%; -9.6%]; Salvage: Evans Blue-TTC vs. CE-SSFP-LGE [0.1%; +9.9%; -9.6%]; Salvage: CE-SSFP-LGE vs. T2-STIR-LGE [0.7%; +6.2%; -4.9%]. Both T2-STIR and CE-SSFP sequences allow for unbiased quantification of AAR in the presence of ischemia/reperfusion injury when analysed by semi-automated algorithms. These experimental data, which was validated by histopathology, supports the use of CMR for the assessment of myocardial salvage during the subacute phase.

Can visual analogue scale be used in radiologic subjective image quality assessment?

BackgroundAssessment of qualitative or subjective image quality in radiology is traditionally performed using a fixed-point scale even though reproducibility has proved challenging.ObjectiveImage quality of 3-T coronary magnetic resonance (MR) angiography was evaluated using three scoring methods, hypothesizing that a continuous scoring scale like visual analogue scale would improve the assessment.Materials and methodsAdolescents corrected for transposition of the great arteries with arterial switch operation, ages 9–15 years (n=12), and healthy, age-matched controls (n=12), were examined with 3-D steady-state free precession magnetic resonance imaging. Image quality of the coronary artery origin was evaluated by using a fixed-point scale (1–4), visual analogue scale of 10 cm and a visual analogue scale with reference points (figurative visual analogue scale). Satisfactory image quality was set to a fixed-point scale 3=visual analogue scale/figurative visual analogue scale 6.6 cm. Statistical analysis was performed using Cohen kappa coefficient and agreement index.ResultsThe mean interobserver scores for the fixed-point scale, visual analogue scale and figurative visual analogue scale were, respectively, in the left main stem 2.8, 5.7, 7.0; left anterior descending artery 2.8, 4.7, 6.6; circumflex artery 2.5, 4.5, 6.2, and right coronary artery 3.2, 6.3, 7.7. Scoring with a fixed-point scale gave an intraobserver κ of 0.52–0.77 while interobserver κ was lacking. For visual analogue scale and figurative visual analogue scale, intraobserver agreement indices were, respectively, 0.08–0.58 and 0.43–0.71 and interobserver agreement indices were up to 0.5 and 0.65, respectively.ConclusionQualitative image quality evaluation with coronary 3-D steady-state free precession MR angiography, using a visual analogue scale with reference points, had better reproducibility compared to a fixed-point scale and visual analogue scale. Image quality, being a continuum, may be better determined by this method.

Assessing venous thrombus in renal cell carcinoma: preliminary results for unenhanced 3D-SSFP MRI

To test the potential of unenhanced cardiac- and respiratory-motion-corrected three-dimensional steady-state free precession (3D-SSFP) magnetic resonance imaging (MRI) for the assessment of inferior vena cava (IVC) thrombus in patients with clear-cell renal cell carcinoma (cRCC), compared to standard contrast-enhanced (CE)-MRI and CE-computed tomography (CT). Eighteen patients with cRCC and IVC thrombus, who received CE-MRI and 3D-SSFP at 1.5 T between June 2015 and December 2017, were included. The diagnostic performance of 3D-SSFP in determining the level of thrombus extension, contrast-to-noise ratio (CNR), and image quality were compared with standard MRI/CT and validated against intraoperative and histopathology results. There was 100% agreement between 3D-SSFP, 83.3% agreement between CE-MRI, and 71.4% agreement between CE-CT and surgical findings regarding the level of IVC thrombus. In addition, 3D-SSFP showed a slightly superior estimate of pathological IVC volume. 3D-SSFP reached a significantly higher CNR in the supra- and infrarenal IVC compared to the morphological sequence T2-weighted half-Fourier axial single-shot fast spin-echo (T2-HASTE) and all phases of CE-MRI. More specifically, 3D-SSFP showed a significantly higher CNR in the infrarenal IVC (mean CNR of 10.09±5.74 versus 4.21±2.33 in the delayed phase, p≤0.001) and in the suprarenal IVC (mean CNR of 9.22±4.11 versus 4.84±5.74 in the late arterial phase, p=0.015). CE-CT also was significantly inferior to 3D-SSFP (p≤0.01) and slightly inferior to CE-MRI (p>0.05). The thrombus delineation score for 3D-SSFP (4.38±0.67) was higher compared to CE-MRI (3.76±0.56, p=0.005). This preliminary study indicates that 3D-SSFP can achieve an accurate assessment of IVC thrombus in cRCC patients without the need for contrast medium administration, being superior to standard MRI and CT.

Feasibility of performing non-contrast magnetic resonance angiography in pregnant subjects with familial aortopathies

BackgroundPregnancy is associated with an increased risk of aortic pathology. We sought to assess the feasibility of performing non-contrast 3D steady-state free-precession (SSFP) magnetic resonance angiography (MRA) in pregnant subjects with inherited aortopathy. MethodsFifteen pregnant subjects (age 27±4yr) with positive genotyping for aortopathy (Marfan, Loeys-Dietz, Ehlers-Danlos) and/or a family history of aortic dissection underwent non-contrast 3D-SSFP MRA at 1.5T (Avanto, Siemens Healthcare, Erlangen, Germany) using a modified ECG-triggered orientated in a sagittal-oblique plane with a respiratory navigator at the diaphragmatic level (mean acquisition time 4.1±1.9min). Imaging was performed during the mid-trimester (21±5weeks). Image analysis was performed off-line using Cvi42 software (Circle Cardiovascular Imaging, Calgary, Canada). An assessment of image quality (score 0–3) was made before performing inner edge to inner edge measurements of the thoracic aorta at 7 levels from the multiplanar reconstructions by two independent blinded observers. ResultsNon-contrast 3D-MRA was successfully acquired in all 15 subjects. Image quality was deemed excellent in 87% (13/15) of cases after a mean acquisition time of 4.1±1.9min. There was a high level of agreement for aortic measurements, with low intra- and inter-observer variability (ICC ranges; 0.95–0.99 and 0.92–0.98, respectively). All pregnancies reached term (≥37/40) with a mean gestation at delivery of 38.0±0.5weeks. The mode of delivery was vaginal in 9 out of 15 subjects (60%). ConclusionsNon-contrast SSFP MRA imaging provides a quick and reproducible method of assessing the thoracic aorta in pregnancy.

Diagnostic Efficacy of Coronary Artery Three-Dimensional Steady-State Free Precession Magnetic Resonance Angiography in Comparison with Invasive Coronary Angiography for Detecting Coronary Artery Disease.

To assess the diagnostic value of three-dimensional steady-state free precession magnetic resonance angiography (3D-SSFP MRA) for detecting coronary artery disease (CAD). Patients suspected of CAD based on clinical evaluation, underwent invasive coronary angiography (CAG) and Cardiac MRA (CMRA). Collected data in favor of any CAD findings in CMRA were compared to CAG results as the standard diagnostic method in CAD detection. Analysis was performed on per-patient, per-vessel and per-segment bases. A total of 30 patients (mean age: 43 ± 10 years, 19 men) were enrolled for analysis. On per-patient analysis, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and area under receiver operator characteristic (ROC) curve of CMRA for detection of coronary artery stenosis were 100% (CI95%: 75% - 100%), 50% (CI95%: 18% - 81%), 73.33% (CI95%: 46% - 90%), 100% (CI95%: 47% - 100%) and 0.827, respectively. On per-vessel analysis, CMRA had a sensitivity of 89.29% (CI95%: 71%-97%), specificity of 80.56% (CI95%: 63% - 91%), PPV of 78.13% (CI95%: 60% - 90%), NPV of 90.63% (CI95%: 74% - 98%) and area under ROC curve of 0.845. On per-segment analysis, sensitivity, specificity, PPV and NPV of CMRA for segmental stenosis detection were 77.78% (CI95%: 60% - 89%), 87% (CI95%: 81% - 92%), 62% (CI95%: 46% - 76%), and 93.89% (CI95%: 88% - 97%), respectively. Area under ROC curve was 0.835 on per-segment analysis. 3D SSFP CMRA provides a promising non-invasive diagnostic tool for assessing coronary artery disease.

Nerves of Steel: a Low-Cost Method for 3D Printing the Cranial Nerves.

Steady-state free precession (SSFP) magnetic resonance imaging (MRI) can demonstrate details down to the cranial nerve (CN) level. High-resolution three-dimensional (3D) visualization can now quickly be performed at the workstation. However, we are still limited by visualization on flat screens. The emerging technologies in rapid prototyping or 3D printing overcome this limitation. It comprises a variety of automated manufacturing techniques, which use virtual 3D data sets to fabricate solid forms in a layer-by-layer technique. The complex neuroanatomy of the CNs may be better understood and depicted by the use of highly customizable advanced 3D printed models. In this technical note, after manually perfecting the segmentation of each CN and brain stem on each SSFP-MRI image, initial 3D reconstruction was performed. The bony skull base was also reconstructed from computed tomography (CT) data. Autodesk 3D Studio Max, available through freeware student/educator license, was used to three-dimensionally trace the 3D reconstructed CNs in order to create smooth graphically designed CNs and to assure proper fitting of the CNs into their respective neural foramina and fissures. This model was then 3D printed with polyamide through a commercial online service. Two different methods are discussed for the key segmentation and 3D reconstruction steps, by either using professional commercial software, i.e., Materialise Mimics, or utilizing a combination of the widely available software Adobe Photoshop, as well as a freeware software, OsiriX Lite.

Left Atrial Structure in Relationship to Age, Sex, Ethnicity, and Cardiovascular Risk Factors: MESA (Multi-Ethnic Study of Atherosclerosis).

Left atrial (LA) size is a marker of diastolic function and is associated with atrial fibrillation and cardiovascular outcomes. However, there are no large population studies measuring LA structure. The relationship of demographics and cardiovascular risk factors to LA size is largely unknown. This study aimed to determine associations of LA size with demographic factors, cardiac structure and function, and cardiovascular risk factors. LA volume indexed to body surface area was measured by cardiovascular magnetic resonance steady-state free precession and fast gradient echo cine long- and short-axis images in 2576 asymptomatic participants of MESA ([Multi-Ethnic Study of Atherosclerosis] 68.7 years, 53.0% women, white 42.2%, Chinese American 12.0%, black 24.5%, and Hispanic 21.2%) using biplane and short-axis images. The mean LA volume index was 36.5±11.4 mL/m2 in the entire cohort and 35.5±10.1 mL/m2 in subjects free of cardiovascular risk factors (n=283). Multivariable analysis included adjustment for demographics, ethnicity, cardiovascular risk factors, serological studies, socioeconomic status, left ventricular structure, and medications. In the adjusted analysis, age (β=0.2 mL/m2 per year, P<0.0001), male sex (β=-4.2 mL/m2, P<0.0001), obesity (β=1.3 mL/m2, P<0.01), end-diastolic volume index (β=0.4 mL/m2, P<0.0001), Chinese American (β=-2.6 mL/m2, P<0.0001), and Hispanic (β=1.1 mL/m2, P<0.05) ethnicities were associated with LA volume index. Diabetes mellitus and smoking were not associated with LA volume index. LA volumes measured by steady-state free precession were 3% larger than by fast gradient echo cine cardiovascular magnetic resonance (P<0.001). Age, sex, ethnicity and left ventricular structural parameters were associated with LA size. Importantly, the study provides reference values of normal LA volume index.

Non-contrast MR angiography at 1.5 Tesla for aortic monitoring in Marfan patients after aortic root surgery

BackgroundContrast-enhanced cardiovascular magnetic resonance angiography (CE-CMRA) is the established imaging modality for patients with Marfan syndrome requiring life-long annual aortic imaging before and after aortic root replacement. Contrast-free CMRA techniques avoiding side-effects of contrast media are highly desirable for serial imaging but have not been evaluated in the postoperative setup of Marfan patients. The purpose of this study was to assess the feasibility of non-contrast balanced steady-state free precession (bSSFP) magnetic resonance imaging for aortic monitoring of postoperative patients with Marfan syndrome.MethodsSixty-four adult Marfan patients after aortic root replacement were prospectively included. Fourteen patients (22%) had a residual aortic dissection after surgical treatment of type A dissection. bSSFP imaging and CE-CMRA were performed at 1.5 Tesla. Two radiologists evaluated the images regarding image quality (1 = poor, 4 = excellent), artifacts (1 = severe, 4 = none) and aortic pathologies. Readers measured the aortic diameters at defined levels in both techniques. Statistics included observer agreement for image scoring and diameter measurements and ROC analyses for comparison of the diagnostic performance of bSSFP and CE-CMRA.ResultsBoth readers observed no significant differences in image quality between bSSFP and CE-CMRA and found a median image quality score of 4 for both techniques (all p > .05). No significant differences were found regarding the frequency of image artifacts in both sequences (all p > .05). Sensitivity and specificity for detection of aortic dissections was 100% for both readers and techniques. Compared to bSSFP imaging, CE-CMRA resulted in higher diameters (mean bias, 0.9 mm; p < .05). The inter-observer biases of diameter measurements were not significantly different (all p > .05), except for the distal graft anastomosis (p = .001). Using both techniques, the readers correctly identified a graft suture dehiscence with aneurysm formation requiring surgery.ConclusionUnenhanced bSSFP CMR imaging allows for riskless aortic monitoring with high diagnostic accuracy in Marfan patients after aortic root surgery.

Image Quality and Stenosis Assessment of Non-Contrast-Enhanced 3-T Magnetic Resonance Angiography in Patients with Peripheral Artery Disease Compared with Contrast-Enhanced Magnetic Resonance Angiography and Digital Subtraction Angiography.

PurposeTo evaluate the diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) magnetic resonance angiography (MRA) at 3 T for imaging infragenual arteries relative to contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA).Materials and MethodsA series of 16 consecutive patients with peripheral arterial disease (PAD) underwent a combined peripheral MRA protocol consisting of FSD-MRA for the calves and large field-of-view CE-MRA. DSA was performed on all patients within 1 week of the MR angiographies. Image quality and degree of stenosis was assessed by two readers with rich experience. Inter-observer agreement was determined using kappa statistics. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of FSD-MRA, CE-MRA, and CE-MRA combined with FSD-MRA (CE+FSD MRA) in predicting vascular stenosis.ResultsAt the calf station, no significantly difference of subjective image quality scores was found between FSD-MRA and CE-MRA. Inter-reader agreement was excellent for both FSD-MRA and CE-MRA. Both of FSD-MRA and CE-MRA carry a stenosis overestimation risk relative to DSA standard. With DSA as the reference standard, ROC curve analysis showed that the area under the curve was largest for CE+FSD MRA. The greatest sensitivity and specificity were obtained when a cut-off stenosis score of 2 was used.ConclusionIn patients with severe PAD,3 T FSD-MRA provides good-quality diagnostic images without a contrast agent and is a good supplement for CE-MRA. CE+FSD MRA can improve the accuracy of vascular stenosis diagnosis.

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.

Abstract 13266: Non-contrast 3D Magnetic Resonance Imaging Offers and Alternative to Contrast Enhanced Multisclice Computed Tomography for Correct Aortic Valve Sizing in Patients Undergoing Transcatheter Aortic Valve Implantation

Introduction: For successful transcatheter aortic valve implantation (TAVI) correct sizing of the aortic annulus and left ventricular outflow tract in aortic valve stenosis is crucial. With multislice computed tomography (MSCT) 3D volume data sets of the aorta could be acquired in high spatial resolution, but the comorbid patients are exposed to nephrotoxic contrast agents leading to kidney injury in many cases. Hypothesis: The purpose of this study was to establish a useful method for sizing for TAVI without the use of contrast media. With MSCT serving as a the reference standard, we compared measurements of a non-contrast 3D steady-state free-precession (SSFP) magnetic resonance (MRI) for correct annulus sizing and decision for valve size. Methods: We examined 52 patients previous to TAVI with MSCT using a 256-MSCT and a 1.5 Tesla whole-body MRI scanner, respectively. MRI examination included a 3D SSFP sequence covering the entire ascending aorta. The 3D images of both imaging modalities were reconstructed for correct orthogonal view of the aortic annulus using a dedicated software (3mensio, Pie Medical Imaging, The Netherlands). Minimal and maximal annulus diameters, annulus perimeters, and areas of both imaging modalities were analyzed by two blinded and experienced readers in consensus. Virtual decision for valve size (Edwards Sapien 3) was based on the median of these diameters. Results: Mean age of the study cohort was 82.2±4.9 years, 32 (61.5%) were female. Log EuroScore was 25.2±4.8%. Mean annulus perimeter measured by MSCT was 76.7±6.9 mm, by MRI 76.5±6.7 mm (r=0.93, p&lt;0.0001). MSCT yielded a mean annulus area of 545.2±49.0 mm2 with good correlation to MRI, which resulted in a mean area of 543.5±47.0 mm2 (r=0.92, p&lt;0.0001). Decision for Sapien 3 valve size showed good correlation between MSCT and MRI (r=0.94, p&lt;0.0001). Conclusions: In conclusion, non-contrast 3D SSFP MRI shows good correlation to MSCT in the assessment of the aortic annulus and valve sizing for TAVI. The non-contrast MRI approach might be a reasonable alternative for aortic root sizing before TAVI without the use of nephrotoxic contrast agents, especially in patients with reduced kidney function.

Coronary Artery Total Occlusion: MR Angiographic Imaging Findings and Success Rates of Percutaneous Coronary Intervention according to Intraluminal Signal Intensity Patterns.

To compare the success rates of percutaneous coronary interventions (PCIs) for chronic total occlusion (CTO) lesions according to the different signal intensity (SI) patterns seen at coronary magnetic resonance (MR) angiography. Institutional review board approval was obtained, and all patients gave written informed consent. This study included 95 CTO lesions in 93 consecutive patients who underwent steady-state free-precession coronary MR angiography with a 1.5-T imager before PCI. The SI and length of CTO lesions were evaluated at coronary MR angiography, and the lesions were classified into two groups according to the continuity of the areas of high SI in the CTO lesions. Invasive angiographic findings including lesion length and collateral grades were analyzed. A multivariable logistic regression analysis was performed to identify variables associated with successful PCI. Seventy-eight (82%) of 95 CTO lesions were treated successfully with PCI. On coronary MR angiograms, areas of continuous high SI were found in 42 lesions (44%), and 40 (95%) of them were treated successfully with PCI. Thirty-eight (72%) of 53 lesions with low SI or interrupted high SI throughout the CTO segments were successfully treated with PCI. The presence of areas of continuous high SI in the CTO segments was the only independent predictor of PCI success (odds ratio, 8.20; 95% confidence interval: 1.08, 62.15; P = .042). Continuous areas of high SI in CTO lesions on coronary MR angiograms are predictive of better success rates with PCI than are discontinuous or absent areas of high SI.

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.