half-Fourier Single-shot Turbo Spin-echo Research Articles

Structural and functional fetal cardiac imaging using low field (0.55 T) MRI.

This study aims to investigate the feasibility of using a commercially available clinical 0.55 T MRI scanner for comprehensive structural and functional fetal cardiac imaging. Balanced steady-state free precession (bSSFP) and phase contrast (PC) sequences were optimized by in utero studies consisting of 14 subjects for bSSFP optimization and 9 subjects for PC optimization. The signal-to-noise ratio (SNR) of the optimized sequences were investigated. Flow measurements were performed in three vessels, umbilical vein (UV), descending aorta (DAo), and superior vena cava (SVC) using the PC sequences and retrospective gating. The optimized bSSFP, PC and half-Fourier single shot turbo spin-echo (HASTE) sequences were acquired in a cohort of 21 late gestation-age fetuses (>36 weeks) to demonstrate the feasibility of a fetal cardiac exam at 0.55 T. The HASTE stacks were reconstructed to create an isotropic reconstruction of the fetal thorax, followed by automatic great vessel segmentations. The intra-abdominal UV blood flow measurements acquired with MRI were compared to ultrasound UV free-loop flow measurements. Using the parameters from 1.5 T as a starting point, the bSSFP sequences were optimized at 0.55 T, resulting in a 1.6-fold SNR increase and improved image contrast compared to starting parameters, as well as good visibility of most cardiac structures as rated by two experienced fetal cardiologists. The PC sequence resulted in increased SNR and reduced scan time, subsequent retrospective gating enabled successful blood flow measurements. The reconstructions and automatic great vessel segmentations showed good quality, with 18/21 segmentations requiring no or minor refinements. Blood flow measurements were within the expected range. A comparison of the UV measurements performed with ultrasound and MRI showed agreement between the two sets of measurements, with better correlation observed at lower flows. We demonstrated the feasibility of low-field (0.55 T) MRI for fetal cardiac imaging. The reduced SNR at low field strength can be effectively compensated for by strategically optimizing sequence parameters. Major fetal cardiac structures and vessels were consistently visualized, and flow measurements were successfully obtained. The late gestation study demonstrated the robustness and reproducibility at low field strength. MRI performed at 0.55 T is a viable option for fetal cardiac examination.

Visualization of distribution in the vitreous cavity via eye drops using ultra-heavily T2-weighted sequences in MRI: a preliminary study with enucleated pig eyes

We investigated whether magnetic resonance imaging can visualize the distribution in the vitreous cavity via eye drops of ophthalmic solutions, gadolinium-based contrast agent, and 17O-water, and to clarify the usefulness of ultra-heavily T2-weighted sequences in the research of intraocular distribution. Five different solutions (V-ROHTO, TRAVATANZ, gadobutrol, H217O, and saline) were administered to excised pig eye specimens. The samples were scanned using T1 mapping, T2 mapping, 3D T2-weighted (echo times (TE): 500, 3200, and 4500 ms), a half-Fourier single-shot turbo-spin echo sequence (HASTE; TE: 440 and 3000 ms), and 3D-real inversion-recovery before eye drops administration. Subsequently, we used a plastic dropper to drop a 0.5 mL solution each, and images were obtained up to 26 h later. Temporal changes in the T1 and T2 values of the anterior chamber and vitreous cavity were compared. The other sequences were evaluated by determining temporal signal changes as signal intensity ratio (SIR) compared to “No drop.” The T1 and T2 values of samples treated with gadobutrol and H217O decreased over time. The SIR of samples treated with gadobutrol and H217O showed remarkable changes in the 3D T2-weighted images, whereas no remarkable temporal changes were observed in the other solutions. Longer TEs resulted in remarkable changes. We demonstrated that visualization of distribution in the vitreous cavity via eye drops could be achieved with excised pig eyes using gadobutrol and H217O, but not with ophthalmic solutions. Ultra-heavily T2-weighted sequences may be promising for the early and highly sensitive visualization of the intraocular distribution of eye drops.

Brain Metabolite Differences in Fetuses With Cytomegalovirus Infection: A Magnetic Resonance Spectroscopy Study.

Cytomegalovirus (CMV) is the most common intrauterine infection and may be associated with unfavorable outcomes. While some CMV-infected fetuses may show gross or subtle brain abnormalities on MRI, their clinical significance may be unclear. Conversely, normal development cannot be guaranteed in CMV-infected fetuses with normal MRI. To assess brain metabolite differences in CMV-infected fetuses using magnetic resonance spectroscopy (MRS). Retrospective. Out of a cohort of 149 cases, 44 with maternal CMV infection, amniocentesis results, and good-quality MRS were included. CMV-infected fetuses with positive polymerase chain reaction (PCR) (N = 35) were divided based on MRI results as follows: typical brain abnormalities (gross findings, N = 8), exclusive white matter hyperintense signal (WMHS) on T2-weighted images (subtle findings, N = 7), and normal MRI (N = 20). Uninfected fetuses (negative PCR) with normal MRI were included as controls (N = 9). 3 T, T2-weighted half Fourier single-shot turbo spin-echo (HASTE), T2-weighted true fast imaging with steady-state free precession (TrueFISP), T1- and T2*-weighted fast low angle shot (FLASH), and 1H-MRS single-voxel point resolved spectroscopy (PRESS) sequences. MRI findings were assessed by three radiologists, and metabolic ratios within the basal ganglia were calculated using LCModel. Analysis of covariance test with Bonferroni correction for multiple comparisons was used to compare metabolic ratios between groups while accounting for gestational age. A P-value <0.05 was deemed significant. MRS was successfully acquired in 63% of fetuses. Substantial agreement was observed between radiologists (Fleiss' kappa [k] = 0.8). Infected fetuses with gross MRI findings exhibited significantly reduced tNAA/tCr ratios (0.64 ± 0.08) compared with infected fetuses with subtle MRI findings (0.85 ± 0.19), infected fetuses with normal MRI (0.8 ± 0.14) and controls (0.81 ± 0.15). No other significant differences were detected (P ≥ 0.261). Reduced tNAA/tCr within the apparently normal brain tissue was detected in CMV-infected fetuses with gross brain abnormalities, suggesting extensive brain damage. In CMV-infected fetuses with isolated WMHS, no damage was detected by MRS. 3 TECHNICAL EFFICACY: Stage 3.

Feasibility of deep learning-reconstructed thin-slice single-breath-hold HASTE for detecting pancreatic lesions: A comparison with two conventional T2-weighted imaging sequences

ObjectiveThe objective of this study was to evaluate the clinical feasibility of deep learning reconstruction-accelerated thin-slice single-breath-hold half-Fourier single-shot turbo spin echo imaging (HASTEDL) for detecting pancreatic lesions, in comparison with two conventional T2-weighted imaging sequences: compressed-sensing HASTE (HASTECS) and BLADE. MethodsFrom March 2022 to January 2023, a total of 63 patients with suspected pancreatic-related disease underwent the HASTEDL, HASTECS, and BLADE sequences were enrolled in this retrospectively study. The acquisition time, the pancreatic lesion conspicuity (LCP), respiratory motion artifact (RMA), main pancreatic duct conspicuity (MPDC), overall image quality (OIQ), signal-to-noise ratio (SNR), and contrast-noise-ratio (CNR) of the pancreatic lesions were compared among the three sequences by two readers. ResultsThe acquisition time of both HASTEDL and HASTECS was 16 s, which was significantly shorter than that of 102 s for BLADE. In terms of qualitative parameters, Reader 1 and Reader 2 assigned significantly higher scores to the LCP, RMA, MPDC, and OIQ for HASTEDL compared to HASTECS and BLADE sequences; As for the quantitative parameters, the SNR values of the pancreatic head, body, tail, and lesions, the CNR of the pancreatic lesion measured by the two readers were also significantly higher for HASTEDL than for HASTECS and BLADE sequences. ConclusionsCompared to conventional T2WI sequences (HASTECS and BLADE), deep-learning reconstructed HASTE enables thin slice and single-breath-hold acquisition with clinical acceptable image quality for detection of pancreatic lesions.

Simultaneous T1, T2 and T2⁎ mapping of the liver with multi-shot MI-SAGE

PurposeTo apply multi-shot high-resolution multi inversion spin and gradient echo (MI-SAGE) acquisition for simultaneous liver T1, T2 and T2* mapping. MethodsInversion prepared spin- and gradient-echo EPI was developed with ascending slice order across measurements for efficient acquisition with T1, T2, and T2⁎ weighting. Multi-shot EPI was also implemented to minimize distortion and blurring while enabling high in-plane resolution. A dictionary-matching approach was used to fit the images to quantitative parameter maps, which were compared to T1 measured by modified Look-Locker (MOLLI), T1 measured by variable flip angle (VFA), T2 measured by multiple echo time-based Half Fourier Single-shot Turbo spin-Echo (HASTE), T2 measured by radial turbo-spin-echo (rTSE) and T2⁎ measured by multiple gradient echo (MGRE) sequences. ResultsThe multi-shot variant of the sequence achieved higher in-plane resolution of 1.7 × 1.7 mm2 with good image quality in 28 s. Derived quantitative maps showed comparable values to conventional mapping methods. As measured in phantom and in vivo, MOLLI, MESE and MGRE give closest values to MISAGE. VFA, HASTE and rTSE show obvious overestimation. ConclusionsThe proposed multi-shot inversion prepared spin- and gradient-echo EPI sequence allows for high-resolution quantitative T1, T2 and T2 liver tissue characterization in a single breath-hold scan.

Development of a comprehensive cardiac atlas on a 1.5 Tesla Magnetic Resonance Linear Accelerator

Background and purposeThe 1.5 Tesla (T) Magnetic Resonance Linear Accelerator (MRL) provides an innovative modality for improved cardiac imaging when planning radiation treatment. No MRL based cardiac atlases currently exist, thus, we sought to comprehensively characterize cardiac substructures, including the conduction system, from cardiac images acquired using a 1.5 T MRL and provide contouring guidelines. Materials and methodsFive volunteers were enrolled in a prospective protocol (NCT03500081) and were imaged on the 1.5 T MRL with Half Fourier Single-Shot Turbo Spin-Echo (HASTE) and 3D Balanced Steady-State Free Precession (bSSFP) sequences in axial, short axis, and vertical long axis. Cardiac anatomy was contoured by (AS) and confirmed by a board certified cardiologist (JR) with expertise in cardiac MR imaging. ResultsA total of five volunteers had images acquired with the HASTE sequence, with 21 contours created on each image. One of these volunteers had additional images obtained with 3D bSSFP sequences in the axial plane and additional images obtained with HASTE sequences in the key cardiac planes. Contouring guidelines were created and outlined. 15–16 contours were made for the short axis and vertical long axis. The cardiac conduction system was demonstrated with eleven representative contours. There was reasonable variation of contour volume across volunteers, with structures more clearly delineated on the 3D bSSFP sequence. ConclusionsWe present a comprehensive cardiac atlas using novel images acquired prospectively on a 1.5 T MRL. This cardiac atlas provides a novel resource for radiation oncologists in delineating cardiac structures for treatment with radiotherapy, with special focus on the cardiac conduction system.

Deep learning HASTE sequence compared with T2-weighted BLADE sequence for liver MRI at 3 Tesla: a qualitative and quantitative prospective study.

To qualitatively and quantitatively compare a single breath-hold fast half-Fourier single-shot turbo spin echo sequence with deep learning reconstruction (DL HASTE) with T2-weighted BLADE sequence for liver MRI at 3T. From December 2020 to January 2021, patients with liver MRI were prospectively included. For qualitative analysis, sequence quality, presence of artifacts, conspicuity, and presumed nature of the smallest lesion were assessed using the chi-squared and McNemar tests. For quantitative analysis, number of liver lesions, size of the smallest lesion, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in both sequences were assessed using the paired Wilcoxon signed-rank test. Intraclass correlation coefficients (ICCs) and kappa coefficients were used to assess agreement between the two readers. One hundred and twelve patients were evaluated. Overall image quality (p = .006), artifacts (p < .001), and conspicuity of the smallest lesion (p = .001) were significantly better for the DL HASTE sequence than for the T2-weighted BLADE sequence. Significantly more liver lesions were detected with the DL HASTE sequence (356 lesions) than with the T2-weighted BLADE sequence (320 lesions; p < .001). CNR was significantly higher for the DL HASTE sequence (p < .001). SNR was higher for the T2-weighted BLADE sequence (p < .001). Interreader agreement was moderate to excellent depending on the sequence. Of the 41 supernumerary lesions visible only on the DL HASTE sequence, 38 (93%) were true-positives. The DL HASTE sequence can be used to improve image quality and contrast and reduces artifacts, allowing the detection of more liver lesions than with the T2-weighted BLADE sequence. The DL HASTE sequence is superior to the T2-weighted BLADE sequence for the detection of focal liver lesions and can be used in daily practice as a standard sequence. • The half-Fourier acquisition single-shot turbo spin echo sequence with deep learning reconstruction (DL HASTE sequence) has better overall image quality, reduced artifacts (particularly motion artifacts), and improved contrast, allowing the detection of more liver lesions than with the T2-weighted BLADE sequence. • The acquisition time of the DL HASTE sequence is at least eight times faster (21s) than that of the T2-weighted BLADE sequence (3-5min). • The DL HASTE sequence could replace the conventional T2-weighted BLADE sequence to meet the growing indication for hepatic MRI in clinical practice, given its diagnostic and time-saving performance.

Detection of solid and subsolid pulmonary nodules with lung MRI: performance of UTE, T1 gradient-echo, and single-shot T2 fast spin echo

BackgroundAlthough MRI is a radiation-free imaging modality, it has historically been limited in lung imaging due to inherent technical restrictions. The aim of this study is to explore the performance of lung MRI in detecting solid and subsolid pulmonary nodules using T1 gradient-echo (GRE) (VIBE, Volumetric interpolated breath-hold examination), ultrashort time echo (UTE) and T2 Fast Spin Echo (HASTE, Half fourier Single-shot Turbo spin-Echo).MethodsPatients underwent a lung MRI in a 3 T scanner as part of a prospective research project. A baseline Chest CT was obtained as part of their standard of care. Nodules were identified and measured on the baseline CT and categorized according to their density (solid and subsolid) and size (> 4 mm/ ≤ 4 mm). Nodules seen on the baseline CT were classified as present or absent on the different MRI sequences by two thoracic radiologists independently. Interobserver agreement was determined using the simple Kappa coefficient. Paired differences were compared using nonparametric Mann-Whitney U tests. The McNemar test was used to evaluate paired differences in nodule detection between MRI sequences.ResultsThirty-six patients were prospectively enrolled. One hundred forty-nine nodules (100 solid/49 subsolid) with mean size 10.8 mm (SD = 9.4) were included in the analysis. There was substantial interobserver agreement (k = 0.7, p = 0.05).Detection for all nodules, solid and subsolid nodules was respectively; UTE: 71.8%/71.0%/73.5%; VIBE: 61.6%/65%/55.1%; HASTE 72.4%/72.2%/72.7%. Detection rate was higher for nodules > 4 mm in all groups: UTE 90.2%/93.4%/85.4%, VIBE 78.4%/88.5%/63.4%, HASTE 89.4%/93.8%/83.8%. Detection of lesions ≤4 mm was low for all sequences. UTE and HASTE performed significantly better than VIBE for detection of all nodules and subsolid nodules (diff = 18.4 and 17.6%, p = < 0.01 and p = 0.03, respectively). There was no significant difference between UTE and HASTE. There were no significant differences amongst MRI sequences for solid nodules.ConclusionsLung MRI shows adequate performance for the detection of solid and subsolid pulmonary nodules larger than 4 mm and can serve as a promising radiation-free alternative to CT.

MRI features can help to confirm a diagnosis of progressive myelomalacia, but may not be accurate in dogs lacking characteristic clinical signs at the time of imaging.

Progressive myelomalacia (PMM) is a fatal sequela of acute thoracolumbar intervertebral disc extrusion in dogs, with unpredictable onset in the days after the inciting injury. No single reliable diagnostic test is currently available. Magnetic resonance imaging (MRI) features such as T2-weighted spinal cord hyperintensity and loss of subarachnoid signal in a half-Fourier single-shot turbo spin echo (HASTE) sequence have been associated with PMM, but are sometimes present in other dogs with severe deficits. Magnetic resonance imaging findings in 22 dogs with a clinical or histopathologic diagnosis of PMM and 38 deep pain-negative paraplegic dogs were compared in a retrospective case-control study. Length of T2-weighted hyperintense spinal cord change and HASTE signal loss were significantly associated with clinically evident PMM (P=.0019 and P=.0085), however, there were no significant differences between groups when analysis was restricted to dogs not yet showing clinical signs of PMM. The PMM group also had significantly shorter compressive lesions than the control group (P=0.026), suggesting a possible role of more severe focal pressure at the extrusion site. A segment of total loss of contrast enhancement in the venous sinuses and meninges, a feature not previously described, was more common in the PMM group and the difference approached significance (P=0.054). Findings show that MRI features can support the diagnosis in dogs with clinical evidence of PMM,andabsence of these features supports absence of PMM at time of imaging. However, their absencedoes not reliably differentiate dogs with imminent progressive myelomalacia from other dogs with severe deficits following intervertebral disc extrusion.

Cardiac Phase and Flow Compensation Effects on REnal Flow and Microstructure AnisotroPy MRI in Healthy Human Kidney.

Renal diffusion-weighted imaging (DWI) involves microstructure and microcirculation, quantified with diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM), and hybrid models. A better understanding of their contrast may increase specificity. To measure modulation of DWI with cardiac phase and flow-compensated (FC) diffusion gradient waveforms. Prospective. Six healthy volunteers (ages: 22-48 years, five females), water phantom. 3-T, prototype DWI sequence with 2D echo-planar imaging, and bipolar (BP) or FC gradients. 2D Half-Fourier Single-shot Turbo-spin-Echo (HASTE). Multiple-phase 2D spoiled gradient-echo phase contrast (PC) MRI. BP and FC water signal decays were qualitatively compared. Renal arteries and velocities were visualized on PC-MRI. Systolic (peak velocity), diastolic (end stable velocity), and pre-systolic (before peak velocity) phases were identified. Following mutual information-based retrospective self-registration of DWI within each kidney, and Marchenko-Pastur Principal Component Analysis (MPPCA) denoising, combined IVIM-DTI analysis estimated mean diffusivity (MD), fractional anisotropy (FA), and eigenvalues (λi) from tissue diffusivity (Dt ), perfusion fraction (fp ), and pseudodiffusivity (Dp , Dp,axial , Dp,radial ), for each tissue (cortex/medulla, segmented on b0/FA respectively), phase, and waveform (BP, FC). Monte Carlo water diffusion simulations aided data interpretation. Mixed model regression probed differences between tissue types and pulse sequences. Univariate general linear model analysis probed variations among cardiac phases. Spearman correlations were measured between diffusion metrics and renal artery velocities. Statistical significance level was set at P < 0.05. Water BP and FC signal decays showed no differences. Significant pulse sequence dependence occurred for λ1 , λ3 , FA, Dp , fp , Dp,axial , Dp,radial in cortex and medulla, and medullary λ2 . Significant cortex/medulla differences occurred with BP for all metrics except MD (systole [P= 0.224]; diastole [P= 0.556]). Significant phase dependence occurred for Dp , Dp,axial , Dp,radial for BP and medullary λ1 , λ2 , λ3 , MD for FC. FA correlated significantly with velocity. Monte Carlo simulations indicated medullary measurements were consistent with a 34 μm tubule diameter. Cardiac gating and flow compensation modulate of measurements of renal diffusion. 2 TECHNICAL EFFICACY STAGE: 2.

Accuracy of non-contrast enhancement multiparametric MRI to diagnose liver tumor compared to conventional MRI sequences

Magnetic resonance imaging is widely used to create detailed images of the organs and tissues. In daily clinical practice of diagnosing liver cirrhosis, it is still a challenge to find the best clinical diagnosis for detection hepatic lesions like hemangioma or hepatoma. In this study, we tried to compare the accuracy of method non-contrast enhancement multiparametric MRI (mpMRI) with conventional liver MRI. A total of 120 patients with liver cirrhosis were enrolled and were divided into two groups, 60 patients with hepatic hemangioma (HH, group A) and 60 patients with hepatocellular carcinoma (HCC, group B). MRI was first used for different diagnosis hepatic lesions without any invasive procedure or surgical treatment. All acquired MRI images were divided into 2 parts: the first part was the non-contrast enhancement multiparametric MRI (mpMRI), and the second part named the conventional liver MRI, was covered all images including non-contrast enhancement and dynamic contrast material-enhanced. The MRI images were interpreted by two experience gastrointestinal radiologists (I and II). Before analysis, the clinical manifestations, laboratory data, tissue biopsy results were not known. Paired samples t-test was used to analyze the significant difference of two-tailed probability (P &lt; 0.05), and its Hemangioma and Hepatoma of receiver operating characteristic curve and area under the ROC curves values were evaluated. In the results, two-tailed probability of non-contrast enhancement mpMRI sequences and the conventional liver MRI in group A was found to be P = 0.109, while that in group B was found to be P = 0.115. After Wilcoxon sign-ranked test, the two-tailed probability reached 0.557 in group A, while that of group B reached 0.624; both showed not difference between the two groups. In conclusion, the non-contrast enhancement mpMRI that included the half-Fourier single-shot turbo spin-echo (HASTE) with fat suppression T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and susceptibility-weighted imagining (SWI) sequence can provide reliable information for effectively differentiate HH and HCC without using contrast materials. This study is expected to provide a reference for the application of MRI in clinical diagnose for a better enhanced method.

Fully automated segmentation of prostatic urethra for MR-guided radiation therapy.

Accurate delineation of the urethra is a prerequisite for urethral dose reduction in prostate radiotherapy. However, even in magnetic resonance-guided radiation therapy (MRgRT), consistent delineation of the urethra is challenging, particularly in online adaptive radiotherapy. This paper presented a fully automatic MRgRT-based prostatic urethra segmentation framework. Twenty-eight prostate cancer patients were included in this study. In-house 3D half fourier single-shot turbo spin-echo (HASTE) and turbo spin echo (TSE) sequences were used to image the Foley-free urethra on a 0.35T MRgRT system. The segmentation pipeline uses 3D nnU-Net as the base and innovatively combines ground truth and its corresponding radial distance (RD) map during training supervision. Additionally, we evaluate the benefit of incorporating a convolutional long short term memory (LSTM-Conv) layer and spatial recurrent convolution layer (RCL) into nnU-Net. A novel slice-by-slice simple exponential smoothing (SEPS) method specifically for tubular structures was used to post-process the segmentation results. The experimental results show that nnU-Net trained using a combination of Dice, cross-entropy and RD achieved a Dice score of 77.1±2.3% in the testing dataset. With SEPS, Hausdorff distance (HD) and 95% HD were reduced to 2.95±0.17mm and 1.84±0.11mm, respectively. LSTM-Conv and RCL layers only minimally improved the segmentation precision. We present the first Foley-free MRgRT-based automated urethra segmentation study. Our method is built on a data-driven neural network with novel cost functions and a post-processing step designed for tubular structures. The performance is consistent with the need for online and offline urethra dose reduction in prostate radiotherapy.

Evaluation of Spatial Attentive Deep Learning for Automatic Placental Segmentation on Longitudinal MRI.

Automated segmentation of the placenta by MRI in early pregnancy may help predict normal and aberrant placenta function, which could improve the efficiency of placental assessment and the prediction of pregnancy outcomes. An automated segmentation method that works at one gestational age may not transfer effectively to other gestational ages. To evaluate a spatial attentive deep learning method (SADL) for automated placental segmentation on longitudinal placental MRI scans. Prospective, single-center. A total of 154 pregnant women who underwent MRI scans at both 14-18 weeks of gestation and at 19-24 weeks of gestation, divided into training (N=108), validation (N=15), and independent testing datasets (N=31). A 3 T, T2-weighted half Fourier single-shot turbo spin-echo (T2-HASTE) sequence. The reference standard of placental segmentation was manual delineation on T2-HASTE by a third-year neonatology clinical fellow (B.L.) under the supervision of an experienced maternal-fetal medicine specialist (C.J. with 20 years of experience) and an MRI scientist (K.S. with 19 years of experience). The three-dimensional Dice similarity coefficient (DSC) was used to measure the automated segmentation performance compared to the manual placental segmentation. A paired t-test was used to compare the DSCs between SADL and U-Net methods. A Bland-Altman plot was used to analyze the agreement between manual and automated placental volume measurements. A P value < 0.05 was considered statistically significant. In the testing dataset, SADL achieved average DSCs of 0.83 ± 0.06 and 0.84 ± 0.05 in the first and second MRI, which were significantly higher than those achieved by U-Net (0.77 ± 0.08 and 0.76 ± 0.10, respectively). A total of 6 out of 62 MRI scans (9.6%) had volume measurement differences between the SADL-based automated and manual volume measurements that were out of 95% limits of agreement. SADL can automatically detect and segment the placenta with high performance in MRI at two different gestational ages. 4 TECHNICAL EFFICACY STAGE: 2.

Three-dimensional ultrashort echo time magnetic resonance imaging in assessment of idiopathic pulmonary fibrosis, in comparison with high-resolution computed tomography.

BackgroundWe aimed to evaluate the image quality, feasibility, and diagnostic performance of three-dimensional ultrashort echo time magnetic resonance imaging (3D UTE-MRI) to assess idiopathic pulmonary fibrosis (IPF) compared with high-resolution computed tomography (HRCT) and half-Fourier single-shot turbo spin-echo (HASTE) MRI.MethodsA total of 36 patients with IPF (34 men; mean age: 62±8 years, age range: 43 to 78 years) were prospectively included and underwent HRCT and chest MRI on the same day. Chest MRI was performed with a free-breathing 3D spiral UTE pulse sequence and HASTE sequence on a 1.5 T MRI. Two radiologists independently evaluated the image quality of the HRCT, HASTE, and 3D UTE-MRI. They assessed the representative imaging features of IPF, including honeycombing, reticulation, traction bronchiectasis, and ground-glass opacities. Image quality of the 3D UTE-MRI, HASTE, and HRCT were assessed using a 5-point visual scoring method. Kappa and weighted kappa analysis were used to measure intra- and inter-observer and inter-method agreements. Sensitivity (SE), specificity (SP), and accuracy (AC) were used to assess the performance of 3D UTE-MRI for detecting image features of IPF and monitoring the extent of pulmonary fibrosis. Linear regressions and Bland-Altman plots were generated to assess the correlation and agreement between the assessment of the extent of pulmonary fibrosis made by the 2 observers.ResultsThe image quality of HRCT was higher than that of HASTE and UTE-MRI (HRCT vs. UTE-MRI vs. HASTE: 4.9±0.3 vs. 4.1±0.7 vs. 3.0±0.3; P<0.001). Interobserver agreement of HRCT, HASTE, and 3D UTE-MRI when assessing pulmonary fibrosis was substantial and excellent (HRCT: 0.727≤ κ ≤1, P<0.001; HASTE: 0.654≤ κ ≤1, P<0.001; 3D UTE-MRI: 0.719≤ κ ≤0.824, P<0.001). In addition, reticulation (SE: 97.1%; SP: 100%; AC: 97.2%; κ =0.654), honeycombing (SE: 83.3%; SP: 100%; AC: 86.1%; κ =0.625) patterns, and traction bronchiectasis (SE: 94.1%; SP: 100%; AC: 94.4%, κ =0.640) were also well-visualized on 3D UTE-MRI, which was significantly superior to HASTE. Compared with HRCT, the sensitivity of 3D UTE-MRI to detect signs of pulmonary fibrosis (n=35) was 97.2%. The interobserver agreement in elevation of the extent of pulmonary fibrosis with HRCT and 3D UTE-MRI was R2=0.84 (P<0.001) and R2=0.84 (P<0.001), respectively. The extent of pulmonary fibrosis assessed with 3D UTE-MRI [median =9, interquartile range (IQR): 6.25 to 10.00] was lower than that from HRCT (median =12, IQR: 9.25 to 13.00; U=320.00, P<0.001); however, they had a positive correlation (R=0.72, P<0.001).ConclusionsAs a radiation-free non-contrast enhanced imaging method, although the image quality of 3D UTE-MRI is inferior to that of HRCT, it has high reproducibility to identify the imaging features of IPF and evaluate the extent of pulmonary fibrosis.

Concentration of Gallbladder Phosphatidylcholine in Cholangiopathies: A Phosphorus-31 Magnetic Resonance Spectroscopy Pilot Study.

Biliary phosphatidylcholine (PtdC) concentration plays a role in the pathogenesis of bile duct diseases. In vivo phosphorus-31 magnetic resonance spectroscopy (31 P-MRS) at 7 T offers the possibility to assess this concentration noninvasively with high spectral resolution and signal intensity. Comparison of PtdC levels of cholangiopathic patient groups to a control group using a measured T1 relaxation time of PtdC in healthy subjects. Case control. Two patient groups with primary sclerosing cholangitis (PSC, 2f/3 m; age: 43 ± 7 years) and primary biliary cholangitis (PBC, 4f/2 m; age: 57 ± 6 years), and a healthy control group (CON, 2f/3 m; age: 38 ± 7 years). Ten healthy subjects for the assessment of the T1 relaxation time of PtdC. A 3D phase-encoded pulse-acquire 31 P-MRSI sequence for PtdC quantification and a 1D image-selected in vivo 31 P spectroscopy for T1 estimation at 7 T, and a T2-weighted half-Fourier single-shot turbo spin echo MRI sequence for volumetry at 3 T. Calculation of gallbladder volumes and PtdC concentration in groups using hepatic gamma-adenosine triphosphate signal as an internal reference and correction for insufficient relaxation of PtdC with a T1 value assessed in healthy subjects. Group comparison of PtdC content and gallbladder volumes of the PSC/PBC and CON group using Student's t-tests with a significance level of 5%. PtdC T1 value of 357 ± 85 msec in the gallbladder. Significant lower PtdC content for the PSC group, and for the female subgroup of the PBC group compared to the CON group (PSC/CON: 5.74 ± 0.73 mM vs. 9.64 ± 0.97 mM, PBC(f)/CON: 5.77 ± 1.44 mM vs. 9.64 ± 0.97 mM). Significant higher gallbladder volumes of the patient groups compared to the CON group (PSC/CON: 66.3 ± 15.8 mL vs. 20.9 ± 2.2 mL, PBC/CON: 49.8 ± 18.2 mL vs. 20.9 ± 2.2 mL). This study demonstrated the application of a 31 P-MRSI protocol for the quantification of PtdC in the human gallbladder at 7 T. Observed differences in PtdC concentration suggest that this metabolite could serve as a biomarker for specific hepatobiliary disorders. 2 TECHNICAL EFFICACY STAGE: 3.

Diagnostic Confidence and Feasibility of a Deep Learning Accelerated HASTE Sequence of the Abdomen in a Single Breath-Hold.

The aim of this study was to evaluate the feasibility of a single breath-hold fast half-Fourier single-shot turbo spin echo (HASTE) sequence using a deep learning reconstruction (HASTEDL) for T2-weighted magnetic resonance imaging of the abdomen as compared with 2 standard T2-weighted imaging sequences (HASTE and BLADE). Sixty-six patients who underwent 1.5-T liver magnetic resonance imaging were included in this monocentric, retrospective study. The following T2-weighted sequences in axial orientation and using spectral fat suppression were compared: a conventional respiratory-triggered BLADE sequence (time of acquisition [TA] = 4:00 minutes), a conventional multiple breath-hold HASTE sequence (HASTES) (TA = 1:30 minutes), as well as a single breath-hold HASTE with deep learning reconstruction (HASTEDL) (TA = 0:16 minutes). Two radiologists assessed the 3 sequences regarding overall image quality, noise, sharpness, diagnostic confidence, and lesion detectability as well as lesion characterization using a Likert scale ranging from 1 to 4 with 4 being the best. Comparative analyses were conducted to assess the differences between the 3 sequences. HASTEDL was successfully acquired in all patients. Overall image quality for HASTEDL was rated as good (median, 3; interquartile range, 3-4) and was significantly superior to HASTEs (P < 0.001) and inferior to BLADE (P = 0.001). Noise, sharpness, and artifacts for HASTEDL reached similar levels to BLADE (P ≤ 0.176) and were significantly superior to HASTEs (P < 0.001). Diagnostic confidence for HASTEDL was rated excellent by both readers and significantly superior to HASTEs (P < 0.001) and inferior to BLADE (P = 0.044). Lesion detectability and lesion characterization for HASTEDL reached similar levels to those of BLADE (P ≤ 0.523) and were significantly superior to HASTEs (P < 0.001). Concerning the number of detected lesions and the measured diameter of the largest lesion, no significant differences were found comparing BLADE, HASTES, and HASTEDL (P ≤ 0.912). The single breath-hold HASTEDL is feasible and yields comparable image quality and diagnostic confidence to standard T2-weighted TSE BLADE and may therefore allow for a remarkable time saving in abdominal imaging.

Heart Failure With Preserved Ejection Fraction in Hypertension Patients: A Myocardial MR Strain Study.

Despite current recommendations for heart failure with preserved ejection fraction (HFpEF), few studies have demonstrated the ability of MRI to identify subtle functional differences between HFpEF with essential hypertension (HFpEF-HTN) patients and hypertension patients (HTN). This study aimed to detect and evaluate HFpEF in patients with HTN using feature-tracking (FT) and to ascertain optimal strain cutoffs for the diagnosis of HFpEF-HTN. Retrospective study. Three groups (84 with HFpEF-HTN; 72 with HTN; and 70 healthy controls). 1.5T, steady-state free precession (SSFP), and half-Fourier single-shot turbo spin-echo (HASTE) sequences. All patients underwent laboratory testing and imaging protocols (echocardiography and MRI). FT-derived left ventricular (LV) strain and strain rate (SR) were measured and compared among the three groups with adjustment for confounding factors. Kolmogorov-Smirnov's test, independent-sample t-tests, one-way analysis of variance (ANOVA), Pearson's correlation coefficient, area under the receiver-operator characteristic (ROC) curve (AUC), and logistic regression. Compared to 72 HTN patients and 70 healthy controls, HFpEF-HTN patients (84 patients) demonstrated significantly impaired LV strains (except for global peak systolic radial strain, GRS, P < 0.05 for all). Only LV global peak systolic longitudinal strain (GLS) was significantly impaired in HTN patients vs. controls (P < 0.05). The global peak systolic circumferential SR (sGCSR) showed the highest diagnostic value for the differentiation of HFpEF-HTN patients from HTN patients (AUC, 0.731; cutoff value, -1.11/s; sensitivity, 56.0%; specificity, 84.7%). Only global peak early diastolic longitudinal SR (eGLSR) remained independently associated with a diagnosis of HFpEF-HTN in multilogistic analysis. The major strain parameters significantly correlated with LV ejection fraction, end-systolic volume index, and N-terminal pro-brain natriuretic peptide (P < 0.05 for all) and also demonstrated differences between NYHA functional class. HFpEF-HTN patients suffer from both systolic and diastolic cardiac dysfunction. FT-derived strain parameters have potential value for the diagnosis and risk stratification of HFpEF-HTN patients. Level of Evidence 3. Technical Efficacy Stage 2.

Human Placenta Blood Flow During Early Gestation With Pseudocontinuous Arterial Spin Labeling MRI.

Noninvasive measurement of placental blood flow is the major technical challenge for predicting ischemic placenta (IPD). Pseudocontinuous arterial spin labeling (pCASL) MRI was recently shown to be promising, but the potential value in predicting the subsequence development of IPD is not known. To derive global and regional placental blood flow parameters from longitudinal measurements of pCASL MRI and to assess the associations between perfusion-related parameters and IPD. Prospective. Eighty-four women completed two pCASL MRI scans (first; 14-18 weeks and second; 19-24 weeks) from prospectively recruited 118 subjects. A total of 69 subjects were included for the analysis, of which 15 subjects developed IPD. 3T/T2 -weighted half-Fourier single-shot turbo spin-echo (HASTE) and pCASL. Four perfusion-related parameters in the placenta were derived: placenta volume, placental blood flow (PBF), high PBF (hPBF), and relative hPBF. The longitudinal changes of the parameters and their association with IPD were tested after being normalizing to the 16th and 20th weeks of gestation. Comparisons between two gestational ages within subjects were performed using the paired Wilcoxon tests, and comparisons between normal and IPD groups were performed using the unpaired Wilcoxon tests. The difference between the first and second MRI scans was statistically significant for volume (156.6 cm3 vs. 269.7 cm3 , P < 0.001) and PBF (104.9 ml/100g/min vs. 111.3 ml/100g/min, P = 0.02) for normal subjects, indicating an increase in pregnancy with advancing gestation. Of the parameters tested, the difference between the normal and IPD subjects was most pronounced in hPBF (278.1 ml/100g/min vs. 180.7 ml/100g/min, P < 0.001) and relative hPBF (259.1% vs. 183.2%, P < 0.001) at 16 weeks. The high perfusion-related image parameters for IPD were significantly decreased from normal pregnancy at 14-18 weeks of gestation. 2 TECHNICAL EFFICACY STAGE: 1 J. Magn. Reson. Imaging 2020;51:1247-1257.

Does non-echo-planar diffusion-weighted magnetic resonance imaging have a role in assisting the clinical diagnosis of cholesteatoma in selected cases?

To determine the diagnostic performance of diffusion-weighted magnetic resonance imaging in the assessment of patients with suspected, but not clinically evident, cholesteatoma. A retrospective analysis of a prospectively collected database of non-echo-planar diffusion-weighted magnetic resonance imaging studies (using a half-Fourier single-shot turbo-spin echo sequence) was conducted. Clinical records were retrospectively reviewed to determine indications for imaging and operative findings. Seventy-eight investigations in 74 patients with suspected cholesteatoma aged 5.7-79.2 years (mean, 41.7 years) were identified. Operative confirmation was available in 44 ears. Diagnostic accuracy of the imaging technique was calculated using operative findings as a 'gold standard'. Sensitivity of the investigation was examined via comparison with clinically evident cholesteatoma. The accuracy of diffusion-weighted magnetic resonance imaging in assessment of suspected cholesteatoma was 63.6 per cent. The imaging technique was significantly less accurate in assessment of suspected cholesteatoma than clinically evident disease (p < 0.001). Computed tomography and diffusion-weighted magnetic resonance imaging may be complementary in assessment of suspected cholesteatoma, but should be used with caution, and clinical judgement is paramount.

Ferumoxytol enhanced black-blood cardiovascular magnetic resonance imaging

BackgroundBright-blood and black-blood cardiovascular magnetic resonance (CMR) techniques are frequently employed together during a clinical exam because of their complementary features. While valuable, existing black-blood CMR approaches are flow dependent and prone to failure. We aim to assess the effectiveness and reliability of ferumoxytol enhanced (FE) Half-Fourier Single-shot Turbo Spin-echo (HASTE) imaging without magnetization preparation pulses to yield uniform intra-luminal blood signal suppression by comparing FE-HASTE with pre-ferumoxytol HASTE imaging.MethodsThis study was IRB-approved and HIPAA compliant. Consecutive patients who were referred for FE-CMR between June 2013 and February 2017 were enrolled. Qualitative image scores reflecting the degree and reliability of blood signal suppression were based on a 3-point Likert scale, with 3 reflecting perfect suppression. For quantitative evaluation, homogeneity indices (defined as standard deviation of the left atrial signal intensity) and signal-to-noise ratios (SNR) for vascular lumens and cardiac chambers were measured.ResultsOf the 340 unique patients who underwent FE-CMR, HASTE was performed in 257. Ninety-three patients had both pre-ferumoxytol HASTE and FE-HASTE, and were included in this analysis. Qualitative image scores reflecting the degree and reliability of blood signal suppression were significantly higher for FE-HASTE images (2.9 [IQR 2.8–3.0] vs 1.8 [IQR 1.6–2.1], p < 0.001). Inter-reader agreement was moderate (k = 0.50, 95% CI 0.45–0.55). Blood signal suppression was more complete on FE-HASTE images than on pre-ferumoxytol HASTE, as indicated by lower mean homogeneity indices (24.5 [IQR 18.0–32.8] vs 108.0 [IQR 65.0–170.4], p < 0.001) and lower blood pool SNR for all regions (5.6 [IQR 3.2–10.0] vs 21.5 [IQR 12.5–39.4], p < 0.001).ConclusionFE-HASTE black-blood imaging offers an effective, reliable, and simple approach for flow independent blood signal suppression. The technique holds promise as a fast and routine complement to bright-blood cardiovascular imaging with ferumoxytol.