Balanced Turbo Field Echo Sequence Research Articles

MRI Diagnosis of Coronary Artery Lesions in Children With Kawasaki Disease and Their Correlation With Inflammatory Factors.

Ultrasonography (US), as a routine examination for evaluating coronary artery lesions (CAL) in children with Kawasaki disease (KD), has strong subjectivity and limitations. Non-contrast enhanced coronary magnetic resonance angiography (NCE-CMRA) is sensitive and reliable in displaying the segments of coronary arteries (CA). To evaluate the CA using NCE-CMRA, to compare NCE-CMRA with US, and to assess the correlation between KD-related inflammatory factors and the occurrence of CAL. Retrospective. 61 children with KD who had undergone NCE-CMRA. Ultimately, 52 cases were included (32 males and 20 females), with an average of 5.9 ± 0.3 years old. 3-T, 3D balanced turbo field echo sequence. NCE-CMRA and US coronary visualization rates were compared in 41 children who were imaged with both techniques. Inflammatory factors were compared between CAL and normal coronary artery (NCA) subgroups. In the CAL group, correlations of these inflammatory factors with CAL parameters were investigated. Comparison between groups was performed by the two independent samples t-test; the comparison of enumeration data between groups was performed by chi-square test. Receiver operating characteristic (ROC) curve analysis was performed to determine the sensitivity of inflammatory factors for detecting CAL. The correlation between CAL and inflammatory indexes was analyzed by multiple linear regression. A P value <0.05 was considered statistically significant. NCE-CMRA visualized significantly more segments than US (76% vs. 46%). There were significant differences in PLT, CRP, ESR, and D-dimer between the CAL and NCA groups. ROC curve analysis showed that the sensitivities of these four indicators in diagnosing CAL were 39%, 44%, 72%, and 61%, respectively, at cut-off points of 562.5 × 109 /L, 48.93 mg/L, 45.5 mm/h, and 0.5 mg/L, respectively. The combination of NCE-CMRA and inflammatory factors is helpful for the early diagnosis and disease severity of CAL in children with KD. 3 TECHNICAL EFFICACY: Stage 2.

Auto-Correction for Inaccurate Auto-Segmentation of Abdominal MRI by Combining Deep Learning and Active Contour Method

Fast and accurate auto-segmentation is crucial during the magnetic resonance-guided adaptive radiation therapy (MRgART). Deep learning auto-segmentation (DLAS) approaches do not always result in clinically acceptable contours, especially for complex abdominal organs. We have previously reported that the inaccurate DLAS for bowels can be refined using deep learning (DL) and/or active contour method (ACM). This study aims to develop an automatic contour correction (ACC) tool by combining DL and ACM techniques to correct for inaccurate DLAS of pancreas and stomach on MRI. The ACC technique consisted of ACM and DL based on UNet system. The ACM utilizes the probability maps generated from DLAS models to establish 2D parameter maps and to initialize contour evolution, thus not requiring initial parameter adjustments. The Organ specific DL-UNet models were trained for pancreas and stomach contours obtained from a research DLAS tool on abdominal MRIs acquired during routine MRgART from a 1.5T MR-Linac using either turbo field-echo or balanced turbo field-echo sequences. The training dataset contained MR slices along with DLAS and ground truth contours from 54 abdominal MRL sets, and 540 additional augmented sets created by shifting and rotating. DLAS contours were classified based on the expected editing effort into the acceptable, minor edit, or major edit category using an in-house developed classification model. Performance of the obtained ACC models were tested on an independent dataset of 11 sets of abdominal MRIs. For pancreas, the DL-UNet model improved 17% (26/153) and 2% (2/95) of the minor and major edits' slices of the testing dataset, respectively, to acceptable and 39% (37/95) of the major edit slices improved to minor edits. The ACM model improved 3% (4/153) of the minor edit slices to acceptable and the 36% (34/95) of the major slices to minor edits. Using the ACC technique with DL and ACM combined, the percentage of acceptable contours increased from 10% (29/277) to 24% (66/277), and minor edits from 55% (153/277) to 61% (170/277), while the percentage of the major edit slices reduced from 35% (95/277) to 15% (41/277). For stomach, the DL model improved 8% (29/366) of the minor edit slices to acceptable and 50% (16/32) of the major edit slices to minor edit slices. The ACM resulted in 2% (6/366) of minor edit slices to acceptable and 41% (13/32) of major edit slices to minor category. Combining both the DL and ACM, the overall percentage of acceptable stomach contours grew from 13% (58/456) to 22% (101/456) and the percentage of major edit slices reduced from 7% (32/456) to 2% (11/456). The ACC method combining both DL and ACM models can substantially improve the quality of inaccurate DLAS contours of pancreas and stomach in a fully automated and fast manner, minimizing the subsequent manual editing time required for MRgART.

Cardiac MRI Left Atrial Strain Associated With New-Onset Atrial Fibrillation in Patients With ST-Segment Elevation Myocardial Infarction.

Left atrial (LA) strain is associated with structural remodeling of the LA. Whether there is an association between LA strain obtained by cardiac magnetic resonance imaging (MRI) and new-onset atrial fibrillation (AF) after ST-segment elevation myocardial infarction (STEMI) is unclear. To investigate the relationship between LA strain and new-onset AF after STEMI. Retrospective. Three hundred and seventy-nine STEMI patients were enrolled, of which 26 had new-onset AF. 3.0 T, balanced turbo field echo sequence. Patients were divided into w/o AF group and new-onset AF group. Cardiac MRI images were analyzed using cardiovascular imaging software CVI 42 (Circle Cardiovascular Imaging, Canada). An automatic tracing algorithm was applied to obtain strain values. The reservoir strain, conduit strain, and booster strain were included in model 1, model 2, and model 3, respectively. Student's t-test, Mann-Whiney U test, and chi-square test were performed. Variables with a P ≤ 0.05 were incorporated into the logistic regression analysis. Area under curve of receiver operating characteristic was used to assess the ability of LA strain to identify new-onset AF. Bayesian information criterion, Akaike information criterion, and C-index were used to make comparisons between three models. P < 0.05 was considered statistically significant. Three models were used to assess LA strain identification ability for new-onset AF. After including multiple factors, right coronary artery (RCA), LVEF, and reservoir strain were still risk factors for new-onset AF in model 1. In model 2, age, RCA, LVEF, and conduit strain were still risk factors for new-onset AF. In model 3, RCA, LVEF, LVEDVi, and booster strain were still risk factors for new-onset AF. Model 2 has a stronger identification ability than others. LA strain associated with new-onset AF after STEMI. The model including conduit strain was the best-fit one. 4 TECHNICAL EFFICACY: Stage 3.

Contribution of fetal magnetic resonance imaging in fetuses with congenital heart disease.

Increasing evidence supports an association among congenital heart disease (CHD), structural brain lesions on neuroimaging, and increased risk of neurodevelopmental delay and other structural anomalies. Fetal MRI has been found to be effective in demonstrating fetal structural and developmental abnormalities. To determine the contribution of fetal MRI to identifying cardiovascular and non-cardiovascular anomalies in fetuses with CHD compared to prenatal US and fetal echocardiography. We performed a retrospective study of fetuses with CHD identified by fetal echocardiography. Exams were performed on 1.5-tesla (T) or 3-T magnets using a balanced turbo field echo sequence triggered by an external electrocardiogram simulator with a fixed heart rate of 140 beats per minute (bpm). Fetal echocardiography was performed by pediatric cardiologists and detailed obstetrical US by maternal-fetal medicine specialists prior to referral to MRI. We compared the sensitivity of fetal MRI and fetal echocardiography for the diagnosis of cardiovascular anomalies, as well as the sensitivity of fetal MRI and referral US for the diagnosis of non-cardiac anomalies. We performed statistical analysis using the McNemar test. We identified 121 anomalies in 31 fetuses. Of these, 73 (60.3%) were cardiovascular and 48 (39.7%) involved other organ systems. Fetal echocardiography was more sensitive for diagnosing cardiovascular anomalies compared to fetal MRI, but the difference was not statistically significant (85.9%, 95% confidence interval [CI] 77.8-94.0% vs. 77.5%, 95% CI 67.7-87.2%, respectively; McNemar test 2.29; P=0.13). The sensitivity of fetal MRI was higher for diagnosing extracardiac anomalies when compared to referral US (84.1%, 95% CI 73.3-94.9% vs. 31.8%, 95% CI 18.1-45.6%, respectively; McNemar test 12.9; P<0.001). The additional information provided by fetal MRI changed prognosis, counseling or management for 10/31 fetuses (32.2%), all in the group of 19 fetuses with anomalies in other organs and systems besides CHD. Fetal MRI performed in a population of fetuses with CHD provided additional information that altered prognosis, counseling or management in approximately one-third of the fetuses, mainly by identifying previously unknown anomalies in other organs and systems.

Automatically Determining Necessity of Online Adaptive Replanning Based on MRI Wavelet Multiscale Texture Features for MRI-Guided Adaptive Radiation Therapy

MRI-guided adaptive radiation therapy (MRgART), particularly daily online adaptive replanning (OLAR) as enabled with MR-LINAC, can substantially improve radiation therapy delivery. However, OLAR is labor-intensive and time-consuming. OLAR is unnecessary for all treatment fractions and being able to objectively and automatically determine when it is needed is desirable. In this study, we investigate whether wavelet multiscale texture features extracted from daily MRI can be used to automatically and objectively identify when OLAR is needed using a machine learning approach.The method was developed and demonstrated using 70 daily motion average MRI sets acquired on a 1.5T MR-LINAC using a balanced turbo field echo sequence during MRgART for 14 pancreatic cancer patients each treated with 5 fractions. For each daily MRI set, OLAR and repositioning (i.e., adapt to position) plans were created and judged per clinical dose-volume constrains by experienced MRL physicists. Multiscale texture features were extracted from the region enclosed by 50 and 100% reference isodose surfaces for different wavelet decomposition levels. Spearman correlations were utilized to rule-out redundant features. Inter-class correlation (ICC), coefficient of variance (COV), and t-test (P < 0.05) were used to determine significant features. Mahalonobis distance classifier with a leave one out cross-validation method was used to develop prediction models based on the identified features and their combinations. The performance of the model to predict whether OLAR is necessary for a given daily MRI set was measured using the AUC of the ROC curve.Spearman correlation identified 123 features from different wavelet decomposition levels that were not redundant (r < 0.9). Of these features, 82 showed high ICC for repositioning, 67 had a COV greater than 9% for OLAR and lower than 5% for repositioning. In addition, 38 of the 67 features passed the t-test with P value < 0.05. Best performing model was a 3-feature combination that can predict OLAR necessity with an AUC of 0.95. It was found that misclassification was attributed to some cases with very close dosimetric gain between repositioning and OLAR and hence a lower discrimination ability for this subgroup.The necessity of OLAR can be automatically determined using a machine learning model based on the wavelet multiscale texture features from the daily MRI immediately after its acquisition, avoiding unnecessary effort during MRgART.

A 3D cine-MRI acquisition technique and image analysis framework to quantify bowel motion demonstrated in gynecological cancer patients.

PurposeMagnetic resonance imaging (MRI) is increasingly used in radiation oncology for target delineation and radiotherapy treatment planning, for example, in patients with gynecological cancers. As a consequence of pelvic radiotherapy, a part of the bowel is irradiated, yielding risk of bowel toxicity. Existing dose‐effect models predicting bowel toxicity are inconclusive and bowel motion might be an important confounding factor. The exact motion of the bowel and dosimetric effects of its motion are yet uncharted territories in radiotherapy. In diagnostic radiology methods on the acquisition of dynamic MRI sequences were developed for bowel motility visualization and quantification. Our study aim was to develop an imaging technique based on three‐dimensional (3D) cine‐MRI to visualize and quantify bowel motion and demonstrate it in a cohort of gynecological cancer patients.MethodsWe developed an MRI acquisition suitable for 3D bowel motion quantification, namely a balanced turbo field echo sequence (TE = 1.39 ms, TR = 2.8 ms), acquiring images in 3.7 s (dynamic) with a 1.25 × 1.25 × 2.5 mm3 resolution, yielding a field of view of 200 × 200 × 125 mm3. These MRI bowel motion sequences were acquired in 22 gynecological patients. During a 10‐min scan, 160 dynamics were acquired. Subsequent dynamics were deformably registered using a B‐spline transformation model, resulting in 159 3D deformation vector fields (DVFs) per MRI set. From the 159 DVFs, the average vector length was calculated per voxel to generate bowel motion maps. Quality assurance was performed on all 159 DVFs per MRI, using the Jacobian Determinant and the Harmonic Energy as deformable image registration error metrics. In order to quantify bowel motion, we introduced the concept of cumulative motion–volume histogram (MVH) of the bowel bag volume. Finally, interpatient variation of bowel motion was analyzed using the MVH parameters M10%, M50%, and M90%. The M10%/M50%/M90% represents the minimum bowel motion per frame of 10%/50%/90% of the bowel bag volume.ResultsThe motion maps resulted in a visualization of areas with small and large movements within the bowel bag. After applying quality assurance, the M10%, M50%, and M90% were 4.4 (range 2.2–7.6) mm, 2.2 (range 0.9–4.1) mm, and 0.5 (range 0.2–1.4) mm per frame, on average over all patients, respectively.ConclusionWe have developed a method to visualize and quantify 3D bowel motion with the use of bowel motion specific MRI sequences in 22 gynecological cancer patients. This 3D cine‐MRI‐based quantification tool and the concept of MVHs can be used in further studies to determine the effect of radiotherapy on bowel motion and to find the relation with dose effects to the small bowel. In addition, the developed technique can be a very interesting application for bowel motility assessment in diagnostic radiology.

Comparison of unenhanced and contrast-enhanced 3T magnetic resonance portovenography in children with extra hepatic portal venous obstruction.

To evaluate role of 3-T magnetic resonance portovenography (MRPV) in children with extra hepatic portal venous obstruction (EHPVO) and compare unenhanced and contrast-enhanced sequences. 20 Children with EHPVO underwent MRPV using unenhanced [T2, T1 pre-contrast, Balanced turbo field echo (BTFE)] and contrast-enhanced (CE) modified DIXON (mDIXON) sequences. The images were evaluated for the patency of abdominal veins, hepatic and splenic parenchyma by two radiologists for interobserver agreement. BTFE and post-contrast mDIXON sequences performed best for evaluation of abdominal veins. Concordance between the BTFE and CE sequences was good to very good for both the radiologists for splenic vein (SV) evaluation. The concordance between the two sequences for evaluation of superior mesenteric vein and its confluence with the SV was less remarkable and varied from fair to good, while the interobserver agreement was very good to perfect. The interobserver agreement between the BTFE and CE sequence for the evaluation of left renal vein was very good, while that for IVC was perfect. The agreement between BTFE and CE sequence was perfect for the evaluation of right and middle hepatic veins, while the interobserver agreement was good to perfect. The interobserver agreement was poor for evaluation of hepatic parenchyma on BTFE sequence as compared to CE sequence, and moderate for splenic parenchyma. BTFE sequence is the single best unenhanced MR pulse sequence to detect all the vascular structures in children with EHPVO. CE-MRI is not superior to BTFE sequence and should be used at the discretion of the radiologist.

Impact of chest wall deformity on cardiac function by CMR and feature-tracking strain analysis in paediatric patients with Marfan syndrome

ObjectivesTo evaluate systolic cardiac dysfunction in paediatric MFS patients with chest wall deformity using cardiac magnetic resonance (CMR) imaging and feature-tracking strain analysis.MethodsForty paediatric MFS patients (16 ± 3 years, range 8−22 years) and 20 age-matched healthy controls (16 ± 4 years, range 11−24 years) were evaluated retrospectively. Biventricular function and volumes were determined using cine sequences. Feature-tracking CMR was used to assess global systolic longitudinal (GLS), circumferential (GCS) and radial strain (GRS). A dedicated balanced turbo field echo sequence was used to quantify chest wall deformity by measuring the Haller index (HI).ResultsLV volumes and ejection fraction (EF) were similar in MFS patients and controls. There was a trend for lower right ventricular (RV) volume (75 ± 17 vs. 81 ± 10 ml/m2, p = 0.08), RV stroke volume (41 ± 12 vs. 50 ± 5 ml/m2, p < 0.001) and RVEF (55 ± 10 vs. 62 ± 6%, p < 0.01) in MFS patients. A subgroup of MFS patients had an increased HI compared to controls (4.6 ± 1.7 vs. 2.6 ± 0.3, p < 0.001). They demonstrated a reduced RVEF compared to MFS patients without chest wall deformity (50 ± 11% vs. 58 ± 8%, p = 0.01) and controls (p < 0.001). LV GLS was attenuated when HI ≥ 3.25 (- 16 ± 2 vs. - 18 ± 3%, p = 0.03), but not GCS and GRS. LV GLS (p < 0.01) and GCS (p < 0.0001) were attenuated in MFS patients compared to controls, but not GRS (p = 0.31). RV GLS was attenuated in MFS patients compared to controls (- 21 ± 3 vs. - 23 ± 3%, p < 0.05).ConclusionChest wall deformity in paediatric MFS patients is associated with reduced RV volume, ejection fraction and GLS. Feature-tracking CMR also indicates impairment of systolic LV function in paediatric MFS patients.Key Points• Paediatric Marfan patients demonstrate reduced RV volume and ejection fraction compared to healthy controls.• A concordant attenuation in RV global longitudinal strain was observed in Marfan patients, while the RV global circumferential strain was increased, indicating a possible compensatory mechanism.• Subgroup analyses demonstrated alterations in RV ejection fraction and RV/LV global strain parameters, indicating a possible association of severe chest wall deformity with biventricular dysfunction in paediatric Marfan patients.

MR Measures of Small Bowel Wall T2 Are Associated With Increased Permeability.

Increased small bowel permeability leads to bacterial translocation, associated with significant morbidity and mortality. Biomarkers are needed to evaluate these changes in vivo, stratify an individual's risk, and evaluate the efficacy of interventions. MRI is an established biomarker of small bowel inflammation. To characterize changes in the small bowel with quantitative MRI measures associated with increased permeability induced by indomethacin. Prospective single-center, double-blind, two-way crossover provocation study. A provocation cohort (22 healthy volunteers) and intrasubject reproducibility cohort (8 healthy volunteers). 2D balanced turbo field echo sequences to measure small bowel wall thickness, T2 , and motility acquired at 3T. Participants were randomized to receive indomethacin or placebo prior to assessment. After a minimum 2-week washout, measures were repeated with the alternative allocation. MR measures (wall thickness, T2 , motility) at each study visit were compared to the reference standard 2-hour lactulose/mannitol urinary excretion ratio (LMR) test performed by a lab technician. All analyses were performed blind. Normality was tested (Shapiro-Wilk's test). Paired testing (Student's t-test or Wilcoxon) determined the significance of paired differences with indomethacin provocation. Pearson's correlation coefficient compared significant measures with indomethacin provocation to LMR. Intrasubject (intraclass correlation) and interrater variability (Bland-Altman) were assessed. Indomethacin provocation induced a significant increase in LMR compared to placebo (P < 0.05) and a significant increase in small bowel T2 (0.12 seconds compared to placebo 0.07 seconds, P < 0.05). Small bowel wall thickness (P = 0.17) and motility (P = 0.149) showed no significant change. T2 and LMR were positively correlated (r = 0.68, P < 0.05). T2 measurements were robust to interobserver (intraclass correlation 0.89) and intrasubject variability (Bland-Altman bias of 0.005 seconds, 95% confidence interval [CI] -0.04 to +0.05 seconds, and 0.0006 seconds, 95% CI -0.05 to +0.06 seconds). MR measures of small bowel wall T2 were significantly increased following indomethacin provocation and correlated with 2-hour LMR test results. 1 TECHNICAL EFFICACY STAGE: 2.

Growth trajectories and cluster features of the human fetal brain estimated by signal intensity from sBTFE sequence in utero MRI

To evaluate the growth trajectories and cluster features of the human fetal brain tissues using signal intensity in utero magnetic resonance imaging. In 136 fetal brain in utero, the signal intensity was measured in 20 region of interests (ROIs) including the bilateral thalamus, pons, genu, body and splenium of corpus callosum, the bilateral frontal, occipital, temporal pole, precentral and postcentral region, cerebellum and the bilateral posterior part of lateral ventricles as a reference. Calculating the signal intensity ratio (SIR) of these ROIs, and then, clustering analysis is used to explore the cluster features of SIR. Furthermore, five representative linear and nonlinear fitting models are used to estimate the relationship between SIR in each region and each cluster and gestational weeks. Over 22–38 gestational weeks, the SIR showed linear decrease in the most of (13 of 18) investigated brain regions, including the pons, bilateral occipital, precentral, postcentral, temporal, cerebellum, and thalamus. By using clustering analysis, the above brain regions could be classified into 6 clusters, and in 4 of 6 clusters, there was similar significant linear growth strategy with that in each of 13 of 18 regions. The applications of a clinical available superfast sequence with sensitivity encoding with balanced turbo field echo sequence and signal intensity-based analysis may to some extent reflect the myelination process and growth strategies of fetal brain following heterogeneous and heterochronicity trajectories. It may be helpful for us to understand the normal fetal brain development pattern through in vivo imaging method prior to birth.

Identification of suspicious invasive placentation based on clinical MRI data using textural features and automated machine learning.

The aim of this study was to investigate whether intraplacental texture features from routine placental MRI can objectively and accurately predict invasive placentation. This retrospective study includes 99 pregnant women with pathologically confirmed placental invasion and 56 pregnant women with simple placenta previa. All participants underwent magnetic resonance imaging after 24 gestational weeks. The placenta was segmented in sagittal images from both turbo spin echo (TSE) and balanced turbo field echo (bTFE) sequences. Textural features were extracted from the both original and Laplacian of Gaussian (LoG)-filtered MRI images. An automated machine learning algorithm was applied to the extracted feature sets to obtain the optimal preprocessing steps, classification algorithm, and corresponding hyper-parameters. A gradient boosting classifier using all textual features from original and LoG-filtered TSE images and bTFE images identified by the automated machine learning algorithm achieved the optimal performance with sensitivity, specificity, accuracy, and area under ROC curve (AUC) of 100%, 88.5%, 95.2%, and 0.98 in the prediction of placental invasion. In addition, textural features that contributed to the prediction of placental invasion differ from the features significantly affected by normal placenta maturation. Quantifying intraplacental heterogeneity using LoG filtration and texture analysis highlights the different heterogeneous appearance caused by abnormal placentation relative to normal maturation. The predictive model derived from automated machine learning yielded good performance, indicating the proposed radiomic analysis pipeline can accurately predict placental invasion and facilitate clinical decision-making for pregnant women with suspicious placental invasion. • The intraplacental texture features have high efficiency in prediction of invasive placentation after 24 gestational weeks. • The features with dominated predictive power did not overlap with the features significantly affected by gestational age.

The Visibility of the Terminal Thoracic Duct Into the Venous System Using MR Thoracic Ductography with Balanced Turbo Field Echo Sequence

Magnetic resonance thoracic ductography (MRTD) with balanced turbo field echo (bTFE) can visualize both the thoracic duct and its surrounding vessels. This study aimed to investigate the visibility of the terminal thoracic duct into the venous system in the subclavian region using MRTD with bTFE. MRTD was performed with bTFE as a preoperative workup comprising respiratory gating on a 1.5-T magnetic resonance system for patients with esophageal cancer. The portion and the number of terminal thoracic ducts into the venous system and preterminal branching in the left subclavian region were assessed using MRTD in 132 patients. The confidence level of the visibility using MRTD was also evaluated. The most frequent terminal portion of the thoracic duct was the jugulovenous angle (92 patients, 69.7%), followed by the subclavian vein (27 patients, 20.5%) and the internal jugular vein (8 patients, 6.1%). Four patients also exhibited double entry of the thoracic duct into the venous system. The preterminal branching was single in 96 patients (72.7%) and multiple in 36 patients (27.3%). The confidence level of the visibility of the thoracic duct using MRTD was absolutely certain in 112 patients (84.8%) and was somewhat certain in 20 patients (15.2%). MRTD with bTFE is a robust imaging modality to visualize the terminal portion of the thoracic duct into the venous system in the subclavian region.

Simultaneous detection of hepatocellular carcinoma and vessel thrombus by using SPIO-enhanced B-TFE with the T2 preparation pulse technique.

The purpose of this study was to compare between superparamagnetic iron oxide (SPIO)-enhanced three-dimensional balanced turbo field-echo (B-TFE) sequence with T2 preparation pulse (T2 prep) and T2*-weighted imaging (T2*WI) for the simultaneous detection of hepatocellular carcinoma (HCC) and vessel thrombus. For 1.5-T magnetic resonance imaging, SPIO was administered to 23 patients with a portal or venous tumor thrombus, and B-TFE with T2 prep and T2*WI were acquired. Regions of interest in the B-TFE and T2*WI were selected for the tumor, liver, tumor thrombus, and vessels. The contrasts of the HCC in the liver and the tumor thrombus in the vessels were determined from clinical image. Contrast was calculated using the mean value of the signal intensity on the HCC to the liver and tumor thrombus to vessels. The mean contrasts between HCC and the liver with the use of B-TFE and T2*WI were 0.61±0.05 and 0.70±0.04, respectively. The contrast of HCC to the liver was significantly higher in T2*WI than in B-TFE (p<0.05). The mean contrasts between the tumor thrombus and vessels with the use of B-TFE and T2*WI were 0.28±0.02 and 0.10±0.02, respectively. The contrast of tumor thrombus in the vessels was higher in B-TFE than in T2*WI (p<0.01). Kupffer imaging can be used to assess liver function and acquire morphological images using three-dimensional B-TFE with T2 prep. This technique would be helpful for simultaneous detection of HCC and tumor thrombus.

Improved diagnosis of common bile duct stone with single-shot balanced turbo field-echo sequence in MRCP.

To evaluate the value of adding single-shot balanced turbo field-echo (b-TFE) sequence to conventional magnetic resonance cholangiopancreatography (MRCP) for the detection of common bile duct (CBD) stone. One hundred thirty-seven consecutive patients with suspected CBD stone underwent MRCP including single-shot b-TFE sequence. Twenty-five patients were confirmed with CBD stone by endoscopic retrograde cholangiopancreatography or ultrasonography. Two radiologists reviewed two image protocols: protocol A (conventional MRCP protocol: unenhanced T1-, T2-, and respiratory-triggered three-dimensional fat-suppressed single-shot turbo spin-echoMRCP sequence) and protocol B (protocol A plus single-shot b-TFE sequence). The sensitivity, specificity, positive (PPV) and negative predictive value (NPV), and area under the receiver-operating-characteristic (ROC) curve (AUC) for the detection of CBD stone were compared. The sensitivity (72%) and NPV (94%) were the same between the two protocols. However, protocol B was greater in the specificity (99%) and PPV (94%) than protocol A (92% and 67%, respectively) (P=0.0078 and 0.031, respectively). The AUC was significantly greater for protocol B (0.93) than for protocol A (0.86) (P=0.026). Inclusion of single-shot b-TFE sequence to conventional MRCP significantly improved the specificity and PPV for the detection of CBD stone.

The diagnostic value of magnetic resonance urography using a balanced turbo field echo sequence.

The aim of the study was to compare the inter-observer variability and the accuracy of magnetic resonance urography (MRU) using a thin sectional balanced-turbo field echo (B-TFE) sequence for detecting ureteral calculi and to determine the effect of additional factors (size, density and location of the calculus) on the sensitivity and specificity of the MRU. MRU and CT images were evaluated independently by two radiologists according to presence, density and localization of calculi. The degrees of inter-rater agreement for categorical items were evaluated by the Kappa coefficient. According to the 1st and 2nd observers, the sensitivity of MRU was 65.9%, 71.8% and the specificity of MRU was 95.9%, 100%, respectively. Inter-observer agreement was 84.6% for stone detection. The larger size had a better effect on detectability (p < 0.05). Also, the higher density had a better impact on detectability (p < 0.05). Our study has shown that B-TFE MRU was useful to detect ureteral calculi. However, B-TFE MRU has low sensitivity and high specificity in comparison with CT images. MRU is a reasonable alternative imaging technique for follow-up periods of selective groups like patients with large urinary stones, children or pregnant patients when ionizing radiation is undesirable. • According to 1st and 2nd observers, sensitivity of MRU was 65.9%, 71.8%, respectively. • According to 1st and 2nd observers, MRU specificity was 95.9%, 100%, respectively. • Interobserver agreement was found to be over 84% for stone detection. • B-TFE sequence provides calculus follow-up without radiation. • Larger calculi and more dense calculi individually have the better effect on detectability.

TH‐A‐BRF‐03: Evaluation of Synthetic CTs Generated Using MR‐SIM Data

Purpose:To describe and evaluate a novel algorithm for generating synthetic CT images from MR‐SIM data for dose calculations in MR‐only treatment planning.Methods:A voxel‐based weighted summation method was implemented to generate synthetic CT (synCT) images. MR data were acquired using Philips 1.0T Panorama high‐field open MR‐SIM. Retrospective patient data from seven prostate patients and one brain patient (three lesions) enrolled in an IRB‐approved study were used. 3D T1‐weighted fast field echo and 3D T2‐weighted turbo spin echo sequences were utilized for all patients. A 3D balanced turbo field echo sequence using spectral presaturation with inversion recovery was acquired for prostate patients, but 3D ultra‐short echo time (UTE)‐DIXON was instead acquired for the brain patient to amplify bone signal for semi‐automatic bone segmentation. Weight optimization was performed using a training subset of patients. HU value differences between planning CT and synCTs were analyzed using mean absolute error (MAE). Original patient CT‐based treatment plans were mapped onto synCTs, dose was recalculated using original leaf motion and MU values, and DRRs were generated. Dosevolume metrics and gamma analysis were used for dosimetric evaluation.Results:Average whole‐body MAE of synCTs across all patients was 75+12 HU. In prostate cancer patients, average HU difference between planning and synCTs was 0.9±1.0% for soft tissue structures and 4.3±2.5% for bony structures. DRRs were generated from synCTs and qualitatively showed good geometric agreement with planning CT‐generated DRRs. D99, mean dose, and maximum dose to CTV calculated using the synCT remained within 1.2% of planning CT‐based dose calculations. All gamma analysis evaluated at 2%/2mm dose difference/distance to agreement) pass rates were greater than 95% with an average of 99.9±0.1% for prostate patients and 98.4±2.2% for three brain lesions.Conclusion:SynCTs were generated with clinically acceptable accuracy comparable to planning CTs, enabling dose computations for MR‐only simulation.Research supported in part by a grant from Philips HealthCare (Best, Netherlands).

Associations of arterial distensibility between carotid arteries and abdominal aorta by MR

To investigate the correlations of arterial distensibility between carotid arteries and abdominal aorta by MR. Twenty eight asymptomatic old subjects (71.4 ± 6.7 years; 14 males) and 20 healthy young subjects (23.5 ± 1.0 years; 10 males) were imaged with electrocardiograph-triggered balanced turbo field echo sequence sequence. Arterial distensibility was calculated as the relative lumen area change against unit blood pressure change and its relationship between carotid arteries and abdominal aorta was determined. The arterial distensibility in old subjects was significantly smaller than that in young subjects for left carotid artery (19.0 ± 6.6 × 10(-3) /kpa versus 30.9 ± 6.5 × 10(-3) /kpa), right carotid artery (16.7 ± 6.1 × 10(-3) /kpa versus 28.6 ± 9.3 × 10(-3) /kpa), and abdominal aorta (14.3 ± 5.5 × 10(-3) /kpa versus 37.5 ± 8.8 × 10(-3) /kpa), respectively (all P < 0.001). In both age groups, distensibility of the abdominal aorta was strongly correlated with that of the left carotid artery (old age group: r = 0.553; P = 0.004; young age group: r = 0.487; P = 0.029) but not with that of the right carotid artery (old age group: r = 0.371; P = 0.062; young age group: r = 0.189; P = 0.424). The distensibility of abdominal aorta is much more strongly associated with that of the left carotid artery compared with that of the right carotid artery.

Global Small Bowel Motility: Assessment with Dynamic MR Imaging

To assess the repeatability in human volunteers of software-quantified small bowel motility captured with magnetic resonance (MR) imaging and to test the ability to detect changes in motility induced by pharmacologic agents. The study was approved by the Royal Free Research Ethics Committee, and all subjects gave full written informed consent. Twenty-one healthy volunteers (14 men, seven women; mean age, 28 years) underwent cine MR imaging with a three-dimensional balanced turbo field-echo sequence to capture small bowel motility. Volume blocks (15 cm thick) were acquired every second during a 20-second breath hold. A randomized, blinded, placebo-controlled crossover study of either 0.5 mg neostigmine or saline (n = 11) or 20 mg intravenous butylscopolamine or saline (n = 10) was performed with motility MR imaging at baseline and repeated at a mean of 4 weeks (range, 2-7 weeks). Two readers independently drew regions of interest around the small bowel, and motility was quantified by using a registration algorithm that provided a global motility metric in arbitrary units. Repeatability of the motility measurements at baseline was assessed by using Bland-Altman and within-subject coefficient of variation measures. Changes in mean motility measurements after drug administration were compared with those after placebo administration by using paired t testing. The repeatability between baseline measurements of motility was high; the Bland-Altman mean difference was -0.0025 (range, 0.28-0.4), the 95% limit of agreement was ±0.044 arbitrary units (au), and the within-subject coefficient of variation was 4.9%. Measured motility with neostigmine (mean, 0.39 au) was significantly higher than that with placebo (mean, 0.34 au; P < .001), whereas that with butylscopolamine (mean, 0.13 au) was significantly lower than that with placebo (mean, 0.30 au; P < .001). Quantification of small bowel motility with use of MR imaging in healthy volunteers is repeatable and sensitive to changes induced by means of pharmacologic manipulation. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130151/-/DC1.

Global Small Bowel Motility: Assessment with Dynamic MR Imaging

To assess the repeatability in human volunteers of software-quantified small bowel motility captured with magnetic resonance (MR) imaging and to test the ability to detect changes in motility induced by pharmacologic agents. The study was approved by the Royal Free Research Ethics Committee, and all subjects gave full written informed consent. Twenty-one healthy volunteers (14 men, seven women; mean age, 28 years) underwent cine MR imaging with a three-dimensional balanced turbo field-echo sequence to capture small bowel motility. Volume blocks (15 cm thick) were acquired every second during a 20-second breath hold. A randomized, blinded, placebo-controlled crossover study of either 0.5 mg neostigmine or saline (n = 11) or 20 mg intravenous butylscopolamine or saline (n = 10) was performed with motility MR imaging at baseline and repeated at a mean of 4 weeks (range, 2-7 weeks). Two readers independently drew regions of interest around the small bowel, and motility was quantified by using a registration algorithm that provided a global motility metric in arbitrary units. Repeatability of the motility measurements at baseline was assessed by using Bland-Altman and within-subject coefficient of variation measures. Changes in mean motility measurements after drug administration were compared with those after placebo administration by using paired t testing. The repeatability between baseline measurements of motility was high; the Bland-Altman mean difference was -0.0025 (range, 0.28-0.4), the 95% limit of agreement was ±0.044 arbitrary units (au), and the within-subject coefficient of variation was 4.9%. Measured motility with neostigmine (mean, 0.39 au) was significantly higher than that with placebo (mean, 0.34 au; P < .001), whereas that with butylscopolamine (mean, 0.13 au) was significantly lower than that with placebo (mean, 0.30 au; P < .001). Quantification of small bowel motility with use of MR imaging in healthy volunteers is repeatable and sensitive to changes induced by means of pharmacologic manipulation. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130151/-/DC1.

TH‐C‐141‐11: Evaluation of MR Images as the Planning and Reference Dataset for Daily CBCT‐Based IGRT of the Prostate

Purpose: An important question rarely discussed in the CT vs. MRI simulation debate is whether MRI reference images provide an adequate image‐set to use with daily localization such as cone‐beam CT (CBCT). This study compares clinical couch shifts based on daily CBCT images to shifts measured from MR images as the reference dataset for prostate IMRT treatment. Methods: Eight patients undergoing a pilot study had MR imaging along with CT simulation with the intent of evaluating a MR‐simulation process. Patients had T1, T2 and bTFE (balanced Turbo Field Echo) sequences. The remainder of the treatment planning process continued using traditional procedures using CT. Therapists used only the CT scan as a reference for localization. Retrospectively, an observer measured shifts between daily CBCT images and MR reference images. Results: The differences in shift positions for the cohort between therapists and the observer are −0.16cm ± 0.25cm (AP), 0.04cm ± 0.19cm (SI), and — 0.01cm ± 0.14cm (LR). The mean group error for the therapists and the observer were less than 2 mm in all directions. Based on these shifts, the calculated margins for the therapists would be 0.87cm (AP), 0.65cm (SI), and 0.71cm (LR) and for the observer would be 1.1cm (AP), 0.66cm (SI), and 0.70cm (LR). For SI and LR directions both sets of margins are very close to one another. An outlier impacted the AP margin difference by 2.3mm and should be investigated further. This initial analysis suggests that each modality can be considered clinically sufficient for daily localization. Conclusion: The results of this study suggest that MR reference image‐sets can be used for daily image‐guided localization of prostate cancers with at least the same accuracy as current methods. MR simulation provides substantial soft‐tissue contrast and can improve tissue targeting in radiation oncology, as a Result further investigation is warranted.