TrueFISP Images Research Articles

3D star shot analysis using MAGAT gel dosimeter for integrated imaging and radiation isocenter verification of MR-Linac system.

PurposeThis study aims to investigate a star shot analysis using a three‐dimensional (3D) gel dosimeter for the imaging and radiation isocenter verification of a magnetic resonance linear accelerator (MR‐Linac).MethodsA mixture of methacrylic acid, gelatin, and tetrakis (hydroxymethyl) phosphonium chloride, called MAGAT gel, was fabricated. One MAGAT gel for each Linac and MR‐Linac was irradiated under six gantry angles. A 6 MV photon beam of Linac and a 6 MV flattening filter free beam of MR‐Linac were delivered to two MAGAT gels and EBT3 films. MR images were acquired by MR‐Linac with a clinical sequence (i.e., TrueFISP). The 3D star shot analysis for seven consecutive slices of the MR images with TrueFISP was performed. The 2D star shot analysis for the central plane of the gel was compared to the results from the EBT3 films. The radius of isocircle (ICr) and the distance between the center of the circle and the center marked on the image (ICd) were evaluated.ResultsFor MR‐Linac with MAGAT gel measurements, ICd at the central plane was 0.46 mm for TrueFISP. Compared to EBT3 film measurements, the differences in ICd and ICr for both Linac and MR‐Linac were within 0.11 and 0.13 mm, respectively. For the 3D analysis, seven consecutive slices of TrueFISP images were analyzed and the maximum radii of isocircles (ICr_max) were 0.18 mm for Linac and 0.73 mm for MR‐Linac. The tilting angles of radiation axis were 0.31° for Linac and 0.10° for MR‐Linac.ConclusionThe accuracy of 3D star shot analysis using MAGAT gel was comparable to that of EBT3 film, having a capability for integrated analysis for imaging isocenter and radiation isocenter. 3D star shot analysis using MAGAT gel can provide 3D information of radiation isocenter, suggesting a quantitative extent of gantry‐tilting.

Exploiting lamina terminalis appearance and motion in prediction of hydrocephalus using convolutional LSTM network

BackgroundEvaluation of the lamina terminalis (LT) is crucial for non-invasive evaluation of the CSF diversion for the treatment of hydrocephalus. Together with deep learning algorithms, morphological and physiological analyses of the LT may play an important role in the management of hydrocephalus. AimWe aim to show that exploiting the motion of LT can contribute to the evaluation of hydrocephalus using deep learning algorithms. MethodsThe dataset contains 61 True-fisp data with routine sequences 37 of which are labeled as ‘hydrocephalus’ and the others as ‘normal condition’. A fifteen-year experienced neuroradiologist divided data into two groups. The first group, ‘hydrocephalus’, consists of patients with typical MRI findings (ventriculomegaly, enlargement of the third ventricular recesses and lateral ventricular horns, decreased mamillo-pontine distance, reduced frontal horn angle, thinning/elevation of the corpus callosum, and non-dilated convexity sulci), and the second group contains samples that did not show any symptoms or neurologic abnormality and labeled as ‘normal condition’. The region of interest was determined by the radiologist supervisor to cover the LT. To achieve our purpose, we used both spatial and spatio-temporal analysis with two different deep learning architectures. We utilized Convolutional Neural Networks (CNN) for spatial and Convolutional Long Short-Term Memory (ConvLSTM) models for spatio-temporal analysis using an ROI around LT on sagittal True-fisp images. ResultsOur results show that 80.7% classification accuracy was achieved with the ConvLSTM model exploiting LT motion, whereas 76.5% and 71.6% accuracies were obtained by the 2D CNN model using all frames, and only the first frame from only spatial information, respectively. ConclusionWe suggest that the motion of the LT can be used as an additional attribute to the spatial information to evaluate the hydrocephalus.

The Dynamics of Impaired Blood-Brain Barrier Restoration in a Rat Model of Co-morbid Injury

Defect in brain microperfusion is increasingly recognized as an antecedent event to Alzheimer's disease (AD) and ischemia. Nevertheless, studies on the role of impaired microperfusion as a pathological trigger to neuroinflammation, Aβ deposition as well as blood-brain barrier (BBB) disruption, and the etiological link between AD and ischemia are lacking. In this study, we employ in vivo sequential magnetic resonance imaging (MRI) and computed tomography (CT) imaging in a co-morbid rat model of β-amyloid toxicity (Aβ) and ischemia (ET1) with subsequent histopathology of striatal lesion core and penumbra at 1, 7, and 28days post injury. Within 24h, cerebral injury resulted in increased BBB permeability due to the dissolution of β-dystroglycan (β-DG) and basement membrane laminin by active matrix metalloproteinase9 (MMP9). As a result, net flow of circulating IgG down a hydrostatic gradient into the parenchyma led to vasogenic edema and impaired perfusion, thus increasing the apparent hyperintensity in true fast imaging with steady-state free precession (true FISP) imaging and acute hypoperfusion in CT. This was followed by a slow recruitment of reactive astroglia to the affected brain and depolarization of aquaporin4 (AQP4) expression resulting in cytotoxic edema-in an attempt to resolve vasogenic edema. On d28, functional BBB was restored in ET1 rats as observed by astrocytic MMP9 release, β-DG stabilization, and new vessel formation. This was confirmed by reduced hyperintensity on true FISP imaging and normalized cerebral blood flow in CT. While, Aβ toxicity alone was not detrimental enough, Aβ+ET1 rats showed delayed differential expression of MMP9, late recruitment of astroglial cells, protracted loss of AQP4 depolarization, and thus delayed BBB restoration and cerebral perfusion.

Feasibility of aortic valve planimetry at 7 T ultrahigh field MRI: Comparison to aortic valve MRI at 3 T and 1.5 T

IntroductionThis study examined the feasibility of aortic valve planimetry at 7 T ultrahigh field MRI in intraindividual comparison to 3 T and 1.5 T MRI. Material and methodsAortic valves of eleven healthy volunteers (mean age, 26.4 years) were examined on a 7 T, 3 T, and 1.5 T MR system using FLASH and TrueFISP sequences. Two experienced radiologists evaluated overall image quality, the presence of artefacts, tissue contrast ratios, identifiability, and image details of the aortic valve opening area (AVOA). Furthermore, AVOA was quantified twice by reader 1 and once by reader 2. Correlation analysis between artefact severity and employed magnetic field strength was performed by modified Fisher’s exact-test. Paired t-test was used to analyse for AVOA differences, and Bland-Altman plots were used to analyse AVOA intra-rater and inter-rater variability. ResultsAortic valve imaging at 7 T, 3 T, and 1.5 T with using FLASH was less hampered by artefacts than TrueFISP imaging at 3 T and 1.5 T. Tissue contrast and image details were rated best at 7 T. AVOA was measured slightly smaller at 7 T compared to 3 T (TrueFISP, p-value = 0.057; FLASH, p-value = 0.016) and 1.5 T (TrueFISP, p-value = 0.029; FLASH, p-value = 0.018). Intra-rater and inter-rater variability of AVOA tended to be slightly smaller at 7 T than at 3 T and 1.5 T. ConclusionAortic valve planimetry at 7 T ultrahigh field MRI is technically feasible and in healthy volunteers offers an improved tissue contrast and a slightly better reproducibility than MR planimetry at 1.5 T and 3 T.

BOLD-MRI demonstrates acute placental and fetal organ hypoperfusion with fetal brain sparing during hypercapnia

IntroductionWe evaluated changes in placental and fetal hemodynamics in rodents during acute hypercapnia using BOLD-MRI and Doppler ultrasound. MethodsAnimals were anesthetized with pentobarbital and, in consecutive 4-min periods, breathed: air, 21%O2:5%CO2, and 95%O2:5%CO2. BOLD-MRI: Pregnant ICR mice (n = 6; E17.5) were scanned in a 4.7-T Bruker Biospec spectrometer. Placenta and fetal liver, heart and brain were identified on True-FISP images. Percent change in signal intensity (SI) were analyzed every 30 s from T2*-weighted GE images (TR/TE = 147/10 ms). Doppler: Pregnant Wistar rats (n = 6; E18-20) were anesthetized with pentobarbital and received abdominal Doppler ultrasound. Umbilical artery pulsatility index (PI) and fetal heart rate were assessed at baseline and after two minutes of both hypercapnic challenges. ResultsBOLD-MRI: Normoxic-hypercapnia caused immediate marked reduction in SI in placenta (−44% ± 5.5; p < 0.001), fetal liver (−32% ± 6.4; p < 0.001) and fetal heart (−53% ± 9.9; p < 0.001) but only minor changes in fetal brain (−13% ± 3.4; p < 0.01), suggesting fetal brain sparing. Doppler: Normoxic-hypercapnia caused a marked increase in umbilical artery PI (+27.4% ± 7.2; p < 0.001) and a reduction in fetal heart rate (−48 bpm; 95%CI -9.3 to −87.0; p = 0.02), suggesting acute fetal asphyxia. ConclusionsBrief maternal hypercapnic challenge caused BOLD-MRI changes consistent with acute placental and fetal hypoperfusion with fetal brain sparing. The same challenge caused increased umbilical artery PI and fetal bradycardia on Doppler ultrasound, suggestive for acute fetal asphyxia. BOLD-MRI may be a suitable noninvasive imaging strategy to assess placental and fetal organ hemodynamics.

WE-FG-202-08: Assessment of Treatment Response Via Longitudinal Diffusion MRI On A MRI-Guided System: Initial Experience of Quantitative Analysis

Purpose: To report our initial experience of systematic monitoring treatment response using longitudinal diffusion MR images on a Co-60 MRI-guided radiotherapy system. Methods: Four patients, including 2 head-and-necks, 1 sarcoma and 1 GBM treated on a 0.35 Tesla MRI-guided treatment system, were analyzed. For each patient, 3D TrueFISP MRIs were acquired during CT simulation and before each treatment for treatment planning and patient setup purposes respectively. Additionally, 2D diffusion-weighted MR images (DWI) were acquired weekly throughout the treatment course. The gross target volume (GTV) and brainstem (as a reference structure) were delineated on weekly 3D TrueFISP MRIs to monitor anatomy changes, the contours were then transferred onto the corresponding DWI images after fusing with the weekly TrueFISP images. The patient-specific temporal and spatial variations during the entire treatment course, such as anatomic changes, target apparent diffusion coefficient (ADC) distribution were evaluated in a longitudinal pattern. Results: Routine MRI revealed progressive soft-tissue GTV volume changes (up to 53%) for the H&N cases during the treatment course of 5–7 weeks. Within the GTV, the mean ADC values varied from −44% (ADC decrease) to +26% (ADC increase) in a week. The gradual increase of ADC value was inversely associated with target volume variation for one H&N case. The maximal changes of mean ADC values within the brainstem were 5.3% for the H&N cases. For the large size sarcoma and GBM tumors, spatial heterogeneity and temporal variations were observed through longitudinal ADC analysis. Conclusion: In addition to the superior soft-tissue visualization, the 0.35T MR system on ViewRay showed the potential to quantitatively measure the ADC values for both tumor and normal tissues. For normal tissue that is minimally affected by radiation, its ADC values are reproducible. Tumor ADC values show temporal and spatial fluctuation that can be exploited for personalized adaptive therapy.

SU‐F‐I‐58: Image Quality Comparisons of Different Motion Magnitudes and TR Values in MR‐PET

Purpose:The aim of this work is to evaluate the accuracy and sensitivity of a respiratory‐triggered MR‐PET protocol in detecting four different sized lesions at two different magnitudes of motion, with two different TR values, using a novel PET‐MR‐CT compatible respiratory motion phantom.Methods:The eight‐compartment torso phantom was setup adjacent to the motion stage, which moved four spherical compartments (28, 22, 17, 10 mm diameter) in two separate (1 and 2 cm) linear motion profiles, simulating a 3.5 second respiratory cycle. Scans were acquired on a 3T MR‐PET system (Biograph mMR; Siemens Medical Solutions, Germany). MR measurements were taken with: 1) Respiratory‐triggered T2‐weighted turbo spin echo (BLADE) sequence in coronal orientation, and 2) Real‐time balanced steady‐state gradient echo sequence (TrueFISP) in coronal and sagittal planes. PET was acquired simultaneously with MR. Sphere geometries and motion profiles were measured and compared with ground truths for T2 BLADE‐TSE acquisitions and real time TrueFISP images. PET quantification and geometry measurements were taken using standardized uptake values, voxel intensity plots and were compared with known values, and examined alongside MR‐based attenuation maps. Contrast and signal‐to‐noise ratios were also compared for each of the acquisitions as functions of motion range and TR.Results:Comparison of lesion diameters indicate the respiratory triggered T2 BLADE‐TSE was able to maintain geometry within −2 mm for 1 cm motion for both TR values, and within −3.1 mm for TR = 2000 ms at 2 cm motion. Sphere measurements in respiratory triggered PET images were accurate within +/− 5 mm for both ranges of motion for 28, 22, and 17 mm diameter spheres.Conclusion:Hybrid MR‐PET systems show promise in imaging lung cancer in non‐compliant patients, with their ability to acquire both modalities simultaneously. However, MR‐based attenuation maps are still susceptible to motion derived artifacts and pose the potential to affect PET accuracy.

High resolution ultra-fast sparse sampling with iterative reconstruction imaging for left ventricular evaluation: clinical comparison with standard SSFP imaging

regularization of the SENSE type dataset. Datasets were analysed by two experienced readers (>10 years CMR analysis), with papillary muscles and trabeculae included in the blood pool. Comparison of TrueFISP and CV_sparse was assessed using paired t-test and Pearson’s correlation, and inter-observery reproducibility by Bland-Altman Results 26 clinical patients had both TrueFISP and CV_sparse imaging successfully performed (figure1A,B), mean LVEF 49% (range 16-65%). Strong positive correlation was present for end-diastolic volumes (r=0.98, P< 0.0001), end-systolic volume (r=0.99, P< 0.0001), LVmass (r=0.97, P< 0.0001) and LVEF (r=0.97, P< 0.0001), with no difference between the groups (P=0.95 NS), figure1C. Reproducibility was excellent with bias 0.3%, limits-of-agreement -3.7 to 4.3% (figure1D). Acquisition time for the LVSAX series was significantly shorter for CV_sparse compared to TrueFISP (p<0.001), however CV_sparse images require longer reconstruction times (~5 minutes), during which clinical image acquisition can continue. Conclusions Highly accelerated imaging using TrueFISP with sparse sampling and iterative reconstruction provides excellent image quality with accurate, reproducible results equalling those of standard TrueFISP imaging, but with significantly more rapid acquisition times. This accelerated technique appears valid and ready for application to clinical practice.

Role of magnetic resonance imaging in the prenatal diagnosis of gastrointestinal fetal anomalies.

This study was done to evaluate the role of fetal magnetic resonance imaging (MRI) in the study of gastrointestinal malformations in comparison to prenatal ultrasound (US). A prospective (2010-2012) study of 38 fetal MRI scans was performed on 38 fetuses between 24 and 38 weeks of gestation. All the fetuses had a US diagnosis of gastrointestinal anomalies. T2-weighted HASTE, T1-weighted fast gradient echo, TrueFISP and diffusion-weighted images of the fetal abdomen were obtained on a 1.5-Tesla magnet. All fetal MRI diagnoses were compared with postnatal US findings, autopsy or surgical reports. Fetal MRI was able to confirm the sonographic findings in nine of 38 fetuses (23.7%), to provide additional information in 23 of 38 fetuses (60.6%), to exclude the US diagnosis in five cases (5.2%) and to change it in two cases (5.2%). It was not able to characterize a case of gastric duplication and a case of abdominal cystic lymphangioma (5.2%). Fetal MRI can be used as a complementary imaging modality to US in prenatal evaluation of gastrointestinal anomalies and can be considered a valuable tool not only for confirming or excluding but also for providing additional information to fetal ultrasonographic findings.

Improved inversion time (TI) scout sequence for late gadolinium enhancement MRI of patients with implantable cardiac devices

Background Late gadolinium enhancement (LGE) cardiac MRI is the clinical gold standard for non-invasive characterization of myocardial scar [1]. The LGE technique is a contrast enhanced inversion recovery (IR) FLASH sequence, and requires a priori knowledge of the initial inversion time (TI) to produce optimal contrast between healthy myocardium and scar substrate. The TI is typically assessed using a Look-Locker based TI scout sequence. Recent advances [2,3] have enabled successful application of LGE MRI to patients with cardiac implantable devices at our institution. Presence of cardiac devices, such as implantable cardioverter defibrillators (ICD), gives rise to severe offresonance in the myocardium. This produces banding artifacts in standard TI scout images which cannot be used to estimate the initial TI for LGE imaging. This can result in LGE images with poor contrast and delays in patient scanning. In this abstract, we present a modification to the standard TI scout sequence that prominently reduces artifacts in TI scout images. Methods The TI scout sequence is an inversion prepared cine sequence with TrueFISP readout. Severe off-resonance from an ICD produces severe banding artifacts in TrueFISP images. In addition, in IR sequences, severe off-resonance can prevent inversion of spins in the myocardium, giving rise to hyper-intensity artifacts [2,3]. Recently, we demonstrated that a wideband (3.8 kHz) inversion pulse can overcome this off-resonance effect and invert off-resonant spins sufficiently, thereby eliminating hyper-intensity artifacts [2,3]. We modified the TI scout sequence by replacing the conventional inversion pulse (bandwidth: 1.1 kHz) with a wideband inversion pulse (spectral bandwidth: 3.8 kHz). We also replaced the TrueFISP readout with a FLASH readout. The modified sequence was tested on a group of T1 phantoms and one ICD patient. Results Figure 1 shows phantom images of the modified TI scout sequence. The phantom results show that when a flip angle of 5° is used, the modified TI scout sequence can be used to determine the optimal TI quite accurately. At higher flip angles, larger TIs may be underestimated due to signal burn-off. Figure 2 demonstrates the banding artifacts produced when the standard TI scout sequence is used in an ICD patient. The modified TI scout sequence is able to remove these artifacts completely and allow effective determination of the optimal TI. Conclusions We have modified the TI scout sequence by implementing a wideband inversion pulse and FLASH readout. Phantom results and patient studies demonstrate that the modified sequence has none of the image artifacts that occur with the standard sequence, and produces a reliable estimation of inversion time. We expect that the new TI scout sequence will lead to improved application of LGE MRI in patients with implantable cardiac devices. Funding

Accelerated delayed enhancement imaging of myocardial infarction with through-time radial GRAPPA

Background Delayed contrast enhancement (DCE) imaging is a well-established MRI technique for the evaluation of myocardial infarction (MI) and tissue viability [1]. Inversion-recovery (IR) is used to visualize the hyperenhanced regions of scar after injection of Gd-DTPA. Mid-diastolic segmented k-space coverage is typical, requiring several heartbeats to reconstruct an image [2]. More recently, Cartesian single-shot trueFISP imaging,[3] has achieved free-breathing acquisitions though spatial resolution is traded for imaging speed and multiple heartbeats may be needed to increase SNR through averaging [4]. Alternatively, radial imaging can achieve higher degrees of acceleration[5], and should produce sharper images in patients with high heart-rates and with shorter or non-existent quiescent periods. We demonstrate the feasibility of IR-DCE imaging with a rapid radial sequence accelerated using through-time radial GRAPPA with and without multiheartbeat averaging.

913Dual Bolus Dynamic Contrast Enhanced Cardiac Perfusion Imaging: Comparison of Turbo FLASH and True FISP

Objective: To compare Turbo FLASH and True FISP data from 3 Tesla MRI for the analysis of cardiac perfusion flow. Methods: An anaesthetized healthy minipig was repeatedly (x 10) scanned with a 14 day interval with Turbo FLASH (x 5) and True FISP (x 5). Voxel size was 2.00 x 2.47 x 8 mm3 and prepulse delay time was TI=110 ms. Total scan time for 120 scans was 2:00 min. Prebolus and bolus CA were 1.2 ml and 6 ml 0.5 mmol/ml GdDTPA (Magnevist) with an injection speed of 4 ml/sec. Perfusion was assessed in 6 segments of the mid ventricle short axis view from the heart with eight reported methods: (1) Fermi, (2) Model-free Deconvolution, (3) modified Tofts, (4) Exchange, (5) Uptake, (6) Tofts, (7) Patlak, and (8) Upslope. We compared the outcome of the methods by regression analysis and by comparing medians and distribution of the data. Data yielding perfusion flow values of more than 200 ml/ 100 ml/ min that resulted for one of the 8 methods was completely discarded for all methods. Results: In Turbo FLASH imaging, 5 out of 30 measurements had to be discarded, whereas in True FISP imaging, only 1 out of 30 measurements had to be discarded. The highest correlations (R2>0.9) were observed for methods 1-3, 5, 6 (Turbo FLASH), and for 1, 3, 5, 6 (True FISP). From the Turbo FLASH data, the 5 methods 1-3, 5, 6 were considered as a reference. The Figure shows the box-plots of perfusion flow from the Turbo FLASH and True FISP data. Method 7 underestimates the flow in both cases. The median values of the methods 1-3, 5, (Turbo FLASH), and for all methods (True FISP) match within an interval of ±2 SD (computed from the 5 methods) around the median of the reference (which came out to be 56.0 ml/100 ml/ min for Turbo FLASH, respectively 50.0 ml/100ml/min for True FISP). Perfusion flow assessed by the methods 1-3, 8, (Turbo FLASH), and by the methods 2-4, 6, 8, (True FISP), was observed not to be significantly different from the chosen reference (p<0.01, related samples Wilcoxon rank test). Box plots for Turbo FLASH and True FISP Box plots for Turbo FLASH and True FISP

Exploring ΔR2* and ΔR1 as imaging biomarkers of tumor oxygenation

To investigate the combined use of hyperoxia-inducedΔR(2) * and ΔR(1) as a noninvasive imaging biomarker of tumor hypoxia. MRI was performed on rat GH3 prolactinomas (n = 6) and human PC3 prostate xenografts (n = 6) propagated in nude mice. multiple gradient echo and inversion recovery truefisp images were acquired from identical transverse slices to quantify tumor R(2) * and R(1)before and during carbogen (95% O2 /5% CO2 ) challenge, and correlates of ΔR(2) * and ΔR(1) assessed. Mean baseline R(2) * and R(1) were 119 ± 7 s(-1) and 0.6 ± 0.03 s(-1) for GH3 prolactinomas and 77 ± 12 s(-1) and 0.7 ± 0.02 s(-1) for PC3 xenografts, respectively. During carbogen breathing, mean ΔR(2) * and ΔR(1) were -20 ± 8 s(-1) and 0.08 ± 0.03 s(-1) for GH3 and -0.5 ± 1 s(-1) and 0.2 ± 0.08 s(-1) for the PC3 tumors, respectively. A pronounced relationship betweenΔR(2) * and ΔR(1) was revealed. Considering the blood oxygen-hemoglobin dissociation curve, fast R2 * suggested that GH3 prolactinomas were more hypoxic at baseline, and their carbogen response dominated by increased hemoglobin oxygenation, evidenced by highly negative ΔR(2) *. PC3 tumors were less hypoxic at baseline, and their response to carbogen dominated by increased dissolved oxygen, evidenced by highly positive ΔR(1) . Because the two biomarkers are sensitive to different oxygenation ranges, the combination of ΔR(2) * and ΔR(1) may better characterize tumor hypoxia than each alone.

MR diagnosis of vertebral artery dissection: value of 3D time-of-flight and true fast imaging with steady-state precession fusion imaging

ObjectivesWe hypothesized that 3D time-of-flight (TOF) and true fast imaging with steady-state precession (true-FISP) fusion imaging could provide more information regarding the arterial vessel wall. The purpose of this study was to compare the accuracy of lesion detection and the diagnostic confidence of VAD between TOF images alone and fused TOF and true-FISP images.MethodsFifty patients were studied: 17 had VAD and 33 had vertebral artery hypoplasia. Fusion images of the vertebral artery were reconstructed using a workstation. A receiver-operating characteristic (ROC) analysis was conducted with a continuous rating scale from 1 to 100 to compare observer performance in VAD detection. Five radiologists participated in the observer performance test, and their performances with TOF images were compared with those using fused images.ResultThe observers found that the mean areas under the best-fit ROC curve for TOF images alone and fused TOF images were 0.66 ± 0.05 and 0.93 ± 0.04, which were significantly different (P < 0.01).ConclusionThe fusion images provided more information regarding the arterial vessel wall. Fused images aided distinction between vertebral artery dissection versus vertebral artery hypoplasia.Key Points• New MR techniques can help to differentiate flowing blood from static blood products.• Fused TOF and true-FISP images differentiate the lumen and the arterial wall, improving diagnostic performance.• Fused images may be superior to time-of-flight MR angiography alone.

Quantified terminal ileal motility during MR enterography as a potential biomarker of Crohn’s disease activity: a preliminary study

To compare quantified terminal ileal (TI) motility during MR enterography (MRE) with histopathological severity of acute inflammation in Crohn's disease. A total of 28 Crohn's patients underwent MRE and endoscopic TI biopsy. Axial and coronal TrueFISP, HASTE and post-gadolinium VIBE images were supplemented by multiple coronal TrueFISP cine motility sequences through the small bowel volume. TI motility index (MI) was quantified using validated software; an acute inflammation score (eAIS; 0-6) was assigned to the biopsy. Two observers qualitatively scored mural thickness, T2 signal, contrast enhancement and perimural oedema (0-3) to produce an activity score (aMRIs) based on anatomical MRI. The association among the MI, eAIS and aMRIs was tested using Spearman's rank correlation. Wilcoxon rank sum test compared motility in subjects with and without histopathological inflammation. Mean MI and mean eAIS were 0.27 (range 0.06-0.55) and 1.5 (range 0-5), respectively. There was a significant difference in MI between non-inflamed (mean 0.37, range 0.13-0.55) and inflamed (mean 0.19, range 0.06-0.44) TI, P = 0.002, and a significant negative correlation between MI and both eAIS (Rho = -0.52, P = 0.005) and aMRIs (R = -0.7, P < 0.001). Quantified TI motility negatively correlates with histopathological measures of disease activity and existing anatomical MRI activity biomarkers. • Magnetic resonance imaging is increasingly used to assess Crohn's disease. • MRI measurements can provide a quantitative assessment of small bowel motility. • MR enterography can grade Crohn's disease. • Small bowel motility can be used as a marker of inflammatory activity.

SU-E-I-69: Magnetic Resonance Metal Artifact Evaluation with Routine Clinical Cardiac Sequences.

To examine schemes to grade the severity of metal susceptibility artifacts on image quality using cardiac MRI pulse sequences. A post-thoracotomy patient was simulated with a stainless steel sternal wire (Syneture,MA; size=6, diameter=48mm), placed securely on an ACR MRI phantom. Phantom was scanned on a 1.5-T Siemens using cardiac MRI sequences:1)TrueFISP, 2)Gradient-Recalled-Echo (GRE), 3)Turbo-Spin- Echo (TSE), 4)Turbo-Inversion-Recovery-Magnitude (TIRM), 5)Dark- blood-IR-FS (DBFS) with and without the wire (FOV=30×30cm, slice- thickness/slice-gap=7.0/1.5mm, matrix size=192×192, slices=17). Image quality degradation was assessed in terms of signal loss and spatial deformation; signal loss by a) measuring the largest diameter of signal drop and b) number of slices with a signal drop and spatial deformation in VelocityAI (Atlanta,GA) by computing the rigid transformation indices between the phantom's internal grid with and without the metal. Image quality was evaluated in terms of signal loss, spatial deformation and ring artifacts. Signal loss: TruFISP and GRE showed the largest signal drop diameter (13 and 16cm respectively). GRE sequence showed a signal drop in -12 slices where as signal drop occurred in only ∼4-5 slices with other sequences. Spatial deformation: GRE sequence showed the maximum with a ∼9mm grid deflection followed by TSE and DBFS (∼8mm). An average deflection of 5.4mm was observed on most of the sequences except T rueFISP and TIRM (Omm). Rigid body transformation showed a maximum x,y,z-translation of -4.7, 0.3 and 1.69 mm and x,y,z-angular rotation of 0.2, - 1.5 and 0.5° for GRE sequence followed by TSE and DBFS confirming the spatial distortion results. Concentric ring artifacts with signal loss were also observed on TrueFISP and DBFS images. Quantification of cardiac MR sequences to metal tolerance and the impact on image quality has shown that GRE and TrueFISP are the most metal-susceptible and TIRM is the most metal-tolerant sequence in terms of both signal loss and spatial deformation. This study helped in creating a separate cardiac metal protocol comprising of mainly metal-tolerant sequences thus reducing scan time and patient discomfort.

TrueFISP of the Pediatric Pineal Gland

Although high-resolution 3D-imaging has markedly improved the imaging of the pediatric pineal gland, the prevalences of typical and atypical cysts as well as in vivo volumes are unknown. The purpose of this study was to compare the frequency of typical and atypical cysts using high-resolution 3D-sequence true fast imaging with steady state precession (trueFISP) and standard sequences and to directly measure the pineal volume in a large pediatric population. In 54 consecutively examined children (age 0-17 years, mean age 5.4 ± 5.6 years, 44% female, 56% male) the prevalence of typical and atypical cysts (thickened rim, trabeculations, asymmetry) was determined using trueFISP (isotropic, 0.8mm) and standard sequences, 1.5-T, T1-weighted spin echo (T1-SE), T2-weighted turbo spin echo (T2-TSE) and fluid attenuated inversion recovery (FLAIR). Indistinct findings were noted separately. Volumetry was based on the trueFISP datasets. Solid and cystic compartments were approached separately. The pineal volume was correlated to gender and age. The detected frequency of pineal cysts was higher in trueFISP (57.4%) than in standard sequences (T1-SE 7.4%, T2-TSE 14.8%, and FLAIR 13.0%). In trueFISP 66.3% of the detected cysts were classified as atypical (standard sequences 0%). Indistinct findings were lowest in trueFISP. The mean pineal volume was 94.3 ± 159.1mm³ and no gender related differences were found. Age and volume showed a moderate correlation (r = 0.382) which was remarkably higher in completely solid glands (r = 0.659). TrueFISP imaging improves the detection of pineal cysts in children. A typical cysts are frequently detected as an incidental finding. Volumetric analysis of the pediatric pineal gland is feasible and reveals enormous variation. Whereas gender effects are negligible, the pineal volume in children is dependant on age.

Roboterunterstützte Punktion in einem Hochfeld-Kernspintomografen – erste klinische Ergebnisse

The purpose of this study was to examine the clinical use of MR-guided biopsies in patients with suspicious lesions using a new MR-compatible assistance system in a high-field MR system. Six patients with suspicious focal lesions in various anatomic regions underwent percutanous biopsy in a high-field MR system (1.5 T, Magnetom Espree, Siemens) using a new MR-compatible assistance system (Innomotion). The procedures were planned and guided using T 1-weighted FLASH and TrueFISP sequences. A servopneumatic drive then moved the guiding arm automatically to the insertion point. An MRI compatible 15G biopsy system (Somatex) was introduced by a physician guided by the needle holder and multiple biopsies were performed using the coaxial technique. The feasibility, duration of the intervention and biopsy findings were analyzed. The proposed new system allows accurate punctures in a high-field MR system. The assistance device did not interfere with the image quality, and guided the needle virtually exactly as planned. Histological examination could be conducted on every patient. The lesion was malignant in four cases, and an infectious etiology was diagnosed for the two remaining lesions. Regarding the differentiation of anatomical and pathological structures and position monitoring of the insertion needle, TrueFISP images are to be given preference. The average intervention time was 41 minutes. Lesions up to 15.4 cm beneath the skin surface were punctured. The proposed MR-guided assistance system can be successfully utilized in a high-field MR system for accurate punctures of even deep lesions in various anatomic regions.

Quantitative T2 mapping of the patella at 3.0T is sensitive to early cartilage degeneration, but also to loading of the knee

ObjectiveThe aim of the study was to explore the sensitivity and robustness of T2 mapping in the detection and quantification of early degenerative cartilage changes at the patella.Materials and methodsForty-two patients (22 women, 20 men) with a mean age of 30.3 years and a symptomatic cartilage defect of ICRS grade ≤2 were examined using a 3 T MRI with an 8-channel knee coil. The cartilage lesion was graded based on high-resolution PD TSE and 3D isotropic TrueFISP images. T2 maps were calculated from a standard MESE-sequence, performed at the beginning and at the end of the scan (40 min in-between). Depending on the defect size, a region-of-interest (ROI) analysis was performed on 1–3 consecutive slices. Mean T2 values for the deep, superficial, and global layer as well as the zonal variation were compared among defect grades (ANOVA, post hoc Duncan-test) and over time (Student's t-test).ResultsT2-measurements directly correlated with the extent of cartilage defect (ICRS grade) at all layers and at both time-points. However, correlations were closer for the second measurement at the end of the scan. In this unloaded state, differences in T2-values became more pronounced and were significant even between cartilage of normal appearance adjacent to the defect and healthy cartilage of control patients (both ICRS grade 0). In contrast, there were no such differences among grades in the zonal variation at any time.ConclusionT2 mapping might be a sensitive method for the detection of early cartilage degeneration at the patella in the unloaded joint.

Ultrafast Cine cardiac MRI in the assessment of left ventricular diastology

Cardiac MRI is the accepted gold standard for the assessment of left ventricular systolic function. However, no standards exist for the MRI assessment of left ventricular diastolic function. We hypothesize that the superior morphologic assessment enabled by ultrafast ECG gated cine TrueFISP imaging will enable assessment of left ventricular diastolic function.