Single-shot Fast Spin-echo Sequence Research Articles

Application of deep learning techniques for breath-hold, high-precision T2-weighted magnetic resonance imaging of the abdomen.

To evaluate the feasibility of a high-precision single-shot fast spin-echo (SS-FSE) sequence using the deep learning-based Precise IQ Engine (PIQE) algorithm in comparison with standard SS-FSE for T2-weighted MR imaging of the abdomen, and to compare the image quality with a multi-shot (MS)-FSE sequence using the PIQE algorithm. This retrospective study included 105 patients who underwent abdominal MR including T2-weighted sequences using the PIQE reconstruction algorithm. The image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in high-precision SS-FSE sequences using PIQE were compared to those in standard SS-FSE without PIQE and MS-FSE sequences using PIQE. The scores for all qualitative parameters were significantly higher in high-precision SS-FSE sequence using PIQE than in standard SS-FSE sequence without PIQE (all p < 0.001). In the comparison between two high-precision sequences using PIQE, the SS-FSE sequence showed significantly better scores for the blurring, ghosts or motion/flow artifacts, conspicuity of intrahepatic structures, focal nonsolid hepatic and pancreatic cystic lesions, and overall image quality, in comparison to the MS-FSE sequence (all p < 0.001). Additionally, the SS-FSE sequence using PIQE showed significantly higher SNR of the liver and CNR of nonsolid hepatic lesions than the MS-FSE sequence using PIQE (p < 0.001). A high-precision SS-FSE sequence using the PIQE algorithm is a feasible alternative to the standard FSE sequence in T2-weighted MR imaging of the abdomen. It can improve image quality, the SNR of the liver, and the ability to visualize nonsolid focal liver lesions and pancreatic cystic lesions in comparison to a high-precision MS-FSE sequence using PIQE although this study was limited by single-center design and lack of pathological confirmation.

Clinical application of single-shot fast spin-echo sequence for cerebrospinal fluid flow MR imaging.

In normal-pressure hydrocephalus, disturbances in cerebrospinal fluid (CSF) circulation occur; therefore, understanding CSF dynamics is crucial. The two-dimensional phase-contrast (2D-PC) method, a common approach for visualizing CSF flow on MRI, often presents challenges owing to prominent vein signals and excessively high contrast, hindering the interpretation of morphological information. Therefore, we devised a new imaging method that utilizes T2-weighted high-signal intensification of the CSF and saturation pulses, without requiring specialized imaging sequences. This sequence utilized a T2-weighted single-shot fast spin-echo combined with multi-phase imaging synchronized with a pulse wave. Optimal imaging conditions (repetition time, presence/absence of fast recovery, and echo time) were determined using self-made contrast and single-plate phantoms to evaluate signal-to-noise ratio, contrast ratio, and spatial resolution. In certain clinical cases of hydrocephalus, confirming CSF flow using 2D-PC was challenging. However, our method enabled the visualization of CSF flow, proving to be useful in understanding the pathophysiology of hydrocephalus.

Dosimetry with the TruView gel on a 0.35 T MR-Linac: A feasibility study

The purpose of this work is to assess the feasibility of performing dosimetry with the TruView (ModusQA, London, Ontario, Canada) MTB Fricke gel by MRI reading on a low field MR-Linac (0.35 T). Radiochromic TruView gels were manufactured at IRSN. A 4 echoes time (TE) single-shot fast spin echo sequence (HASTE) was used for 2D images acquisitions. Raw MRI images were denoised (MP-PCA) and transversal relaxation rates (R2) maps were extracted using a homemade Matlab routine. Temperature influences on R2 as well as gel homogeneity were investigated. A dosimetric evaluation of the TruView gel was conducted implying four gels made from the same batch, with three of them dedicated to calibration, and the fourth one received a simple dosimetric plan. Results showed the TruView gel to be sensitive to temperature drift. A protocol was thus developed to ensure thermal stability with the use of a dedicated temperature-controlled water bath. An inhomogeneity that manifests as a R2 increase near the air/gel interface was found to cause a 4% amplitude deviation in R2 along unirradiated gels. Air sealing drastically reduced the inhomogeneity. Dose versus R2 calibration was established. TruView gel sensitivity was found to be low (0.0093 Gy−1 s−1). 1D and 2D comparison to planned dose distribution displayed overall agreement with global gamma index (5%/3 mm) evaluation with an 87 % passing rate. Main discrepancies in the low and gradient dose regions were attributable to the calibration range and diffusion effects. This study demonstrated the feasibility of using the TruView gel for dosimetric evaluation on a low field MR-Linac. The protocol developed needs to be extended to a full 3D evaluation to enable patient QA and may require modifications to the gel formulation to increase its overall sensitivity and ensure limited dependence on temperature drift.

In vivo T2 measurements of the fetal brain using single-shot fast spin echo sequences.

We propose a quantitative framework for motion-corrected T2 fetal brain measurements in vivo and validate the single-shot fast spin echo (SS-FSE) sequence to perform these measurements. Stacks of two-dimensional SS-FSE slices are acquired with different echo times (TE) and motion-corrected with slice-to-volume reconstruction (SVR). The quantitative T2 maps are obtained by a fit to a dictionary of simulated signals. The sequence is selected using simulated experiments on a numerical phantom and validated on a physical phantom scanned on a 1.5T system. In vivo quantitative T2 maps are obtained for five fetuses with gestational ages (GA) 21-35 weeks on the same 1.5T system. The simulated experiments suggested that a TE of 400 ms combined with the clinically utilized TEs of 80 and 180 ms were most suitable for T2 measurements in the fetal brain. The validation on the physical phantom confirmed that the SS-FSE T2 measurements match the gold standard multi-echo spin echo measurements. We measured average T2s of around 200 and 280 ms in the fetal brain grey and white matter, respectively. This was slightly higher than fetal T2* and the neonatal T2 obtained from previous studies. The motion-corrected SS-FSE acquisitions with varying TEs offer a promising practical framework for quantitative T2 measurements of the moving fetus.

Effect of Deep Learning Reconstruction on Respiratory-triggered T2-weighted MR Imaging of the Liver: A Comparison between the Single-shot Fast Spin-echo and Fast Spin-echo Sequences.

To compare the effects of deep learning reconstruction (DLR) on respiratory-triggered T2-weighted MRI of the liver between single-shot fast spin-echo (SSFSE) and fast spin-echo (FSE) sequences. Respiratory-triggered fat-suppressed liver T2-weighted MRI was obtained with the FSE and SSFSE sequences at the same spatial resolution in 55 patients. Conventional reconstruction (CR) and DLR were applied to each sequence, and the SNR and liver-to-lesion contrast were measured on FSE-CR, FSE-DLR, SSFSE-CR, and SSFSE-DLR images. Image quality was independently assessed by three radiologists. The results of the qualitative and quantitative analyses were compared among the four types of images using repeated-measures analysis of variance or Friedman's test for normally and non-normally distributed data, respectively, and a visual grading characteristics (VGC) analysis was performed to evaluate the image quality improvement by DLR on the FSE and SSFSE sequences. The liver SNR was lowest on SSFSE-CR and highest on FSE-DLR and SSFSE-DLR (P < 0.01). The liver-to-lesion contrast did not differ significantly among the four types of images. Qualitatively, noise scores were worst on SSFSE-CR but best on SSFSE-DLR because DLR significantly reduced noise (P < 0.01). In contrast, artifact scores were worst both on FSE-CR and FSE-DLR (P < 0.01) because DLR did not reduce the artifacts. Lesion conspicuity was significantly improved by DLR compared with CR in the SSFSE (P < 0.01) but not in FSE sequences for all readers. Overall image quality was significantly improved by DLR compared with CR for all readers in the SSFSE (P < 0.01) but only one reader in the FSE (P < 0.01). The mean area under the VGC curve values for the FSE-DLR and SSFSE-DLR sequences were 0.65 and 0.94, respectively. In liver T2-weighted MRI, DLR produced more marked improvements in image quality in SSFSE than in FSE.

Association Between MRI Radiomics and Intratumoral Tertiary Lymphoid Structures in Intrahepatic Cholangiocarcinoma and Its Prognostic Significance.

Tertiary lymphoid structures (TLSs) have prognostic value in intrahepatic cholangiocarcinoma (ICC) patients. Noninvasive tool to preoperatively evaluate TLSs is still lacking. To explore the association between TLSs status of ICC and preoperative MRI radiomics analysis. Retrospective. One hundred and ninety-two patients with ICC, divided into training (T = 105), internal validation groups (V1 = 46), and external validation group (V2 = 41). Coronal and axial single-shot fast spin-echo T2-weighted, diffusion-weighted imaging, T1-weighted, and T1WI fat-suppressed spoiled gradient-recall echo LAVA sequence at 3.0 T. The VOIs were drawn manually within the visible borders of the tumors using ITK-SNAP version 3.8.0 software in the axial T2WI, DWI, and portal vein phase sequences. Radiomics features were subjected to least absolute shrinkage and selection operator regression to select the associated features of TLSs and construct the radiomics model. Univariate and multivariate analyses were used to identify the clinical radiological variables associated with TLSs. The performances were evaluated by the area under the receiver operator characteristic curve (AUC). Logistic regression analysis, ROC and AUC, Hosmer-Lemeshow test, Kaplan-Meier method with the log-rank test, calibration curves, and decision curve analysis. P < 0.05 was considered statistically significant. The AUCs of arterial phase diffuse hyperenhancement were 0.59 (95% confidence interval [CI], 0.50-0.67), 0.52 (95% CI, 0.43-0.61), and 0.66 (95% CI, 0.52-0.80) in the T, V1, and V2 cohorts. The AUCs of Rad-score were 0.85 (95% CI, 0.77-0.92), 0.81 (95% CI, 0.67-0.94), and 0.84 (95% CI, 0.71-0.96) in the T, V1, and V2 cohorts, respectively. In cohort T, low-risk group showed significantly better median recurrence-free survival (RFS)than that of the high-risk group, which was also confirmed in cohort V1 and V2. A preoperative MRI radiomics signature is associated with the intratumoral TLSs status of ICC patients and correlate significantly with RFS. 3 TECHNICAL EFFICACY: Stage 2.

Magnetresonanz-Enterographie/Enteroklysma

Magnetic resonance enterography/enteroclysma (MRE) is an examination technique without ionizing radiation that allows assessment of bowel wall changes and extraluminal pathologies/complications such as in chronic inflammatory bowel diseases, among others. To discuss requirements for optimal MR imaging of the small bowel, technical basis of MRE and principles for the development and optimization of aMRE protocol, and clinical indications for this specific imaging technique. Guidelines, basic and review papers will be analyzed. MRE enables the diagnosis of inflammatory bowel diseases and neoplasms and their evaluation during therapy. In addition to intra- and transmural changes, extramural pathologies and complications can also be detected. Standard sequences include steady-state free precession sequences, T2-weighted single-shot fast spin echo sequences, and three-dimensional (3D) T1-weighted gradient echo (GRE) sequences with fat saturation after contrast administration. Prior to image acquisition, optimal patient preparation and distension of the bowel using intraluminal contrast agents is necessary. Careful patient preparation for MRE, understanding of optimal imaging technique, and appropriate clinical indications are essential to achieve high-quality images of the bowel for accurate assessment and diagnosis as well as therapy monitoring of small bowel disease.

High-Resolution Single-Shot Fast Spin-Echo MR Imaging with Deep Learning Reconstruction Algorithm Can Improve Repeatability and Reproducibility of Follicle Counting.

To investigate the diagnostic performance of high-resolution single-shot fast spin-echo (SSFSE) imaging with deep learning (DL) reconstruction algorithm on follicle counting and compare it with original SSFSE images and conventional fast spin-echo (FSE) images. This study included 20 participants (40 ovaries) with clinically confirmed polycystic ovary syndrome (PCOS) who underwent high-resolution ovary MRI, including three-plane T2-weighted FSE sequences and slice-matched T2-weighted SSFSE sequences. A DL reconstruction algorithm was applied to the SSFSE sequences to generate SSFSE-DL images, and the original SSFSE images were also saved. Subjective evaluations such as the blurring artifacts, subjective noise, and clarity of the follicles on the SSFSE-DL, SSFSE, and conventional FSE images were independently conducted by two observers. Intra-class correlation coefficients and Bland-Altman plots were used to present the repeatability and reproducibility of the follicle number per ovary (FNPO) based on the three types of images. SSFSE-DL images showed less blurring artifact, subjective noise, and better clarity of the follicles than SSFSE and FSE (p < 0.05). For the repeatability of the FNPO, SSFSE-DL showed the highest intra-observer (ICC = 0.930; 95% CI: 0.878-0.962) and inter-observer (ICC = 0.914; 95% CI: 0.843-0.953) agreements. The inter-observer 95% limits of agreement (LOA) for SSFSE-DL, SSFSE, and FSE ranged from -3.7 to 4.5, -4.4 to 7.0, and -7.1 to 7.6, respectively. The intra-observer 95% LOA for SSFSE-DL, SSFSE, and FSE ranged from -3.5 to 4.0, -5.1 to 6.1, and -5.7 to 4.2, respectively. The absolute values of intra-observer and inter-observer differences for SSFSE-DL were significantly lower than those for SSFSE and FSE (p < 0.05). Compared with the original SSFSE images and the conventional FSE images, high-resolution SSFSE images with DL reconstruction algorithm can better display follicles, thus improving FNPO assessment.

Voxel-based morphometric magnetic resonance imaging evaluation of small head fetus: A comparative study with normal developmental fetus.

To explore the application value of voxel-based morphometric (VBM) in prenatal diagnosis of microcephaly. A retrospective study of magnetic resonance imaging of fetuses with microcephaly was performed using a single-shot fast spin echo sequence; semiautomatic segmentation of grey matter (GM), white matter (WM), and cerebrospinal fluid (CSF); calculation of their volumes; and VBM analysis of their GM. Two independent samples t-test was used to statistically analyse the fetal GM volume in the microcephaly and normal control groups. Total intracranial volume (TIV), GM volume, WM volume, and CSF volume were linearly regressed against gestational age and compared between the two groups. In the fetus with microcephaly, GM volume of frontal lobe, temporal lobe, cuneus, anterior central gyrus, and posterior central gyrus decreased significantly (P < 0.001, corrected by family-wise error at mass level). The GM volume of microcephaly was significantly lower than that of the control group (except for 28 weeks of gestation) (P < 0.05). TIV, GM volume, WM volume, and CSF volume were all positively correlated with gestational age, and the curves in the microcephaly group were all lower than those in the control group. Compared with the normal control group, the GM volume of microcephaly fetuses decreased, and there were significant differences in many brain regions through VBM analysis.

Automated MR Image Prescription of the Liver Using Deep Learning: Development, Evaluation, and Prospective Implementation.

There is an unmet need for fully automated image prescription of the liver to enable efficient, reproducible MRI. To develop and evaluate artificial intelligence (AI)-based liver image prescription. Prospective. A total of 570 female/469 male patients (age: 56 ± 17 years) with 72%/8%/20% assigned randomly for training/validation/testing; two female/four male healthy volunteers (age: 31 ± 6 years). 1.5 T, 3.0 T; spin echo, gradient echo, bSSFP. A total of 1039 three-plane localizer acquisitions (26,929 slices) from consecutive clinical liver MRI examinations were retrieved retrospectively and annotated by six radiologists. The localizer images and manual annotations were used to train an object-detection convolutional neural network (YOLOv3) to detect multiple object classes (liver, torso, and arms) across localizer image orientations and to output corresponding 2D bounding boxes. Whole-liver image prescription in standard orientations was obtained based on these bounding boxes. 2D detection performance was evaluated on test datasets by calculating intersection over union (IoU) between manual and automated labeling. 3D prescription accuracy was calculated by measuring the boundary mismatch in each dimension and percentage of manual volume covered by AI prescription. The automated prescription was implemented on a 3T MR system and evaluated prospectively on healthy volunteers. Paired t-tests (threshold=0.05) were conducted to evaluate significance of performance difference between trained networks. In 208 testing datasets, the proposed method with full network had excellent agreement with manual annotations, with median IoU > 0.91 (interquartile range < 0.09) across all seven classes. The automated 3D prescription was accurate, with shifts <2.3cm in superior/inferior dimension for 3D axial prescription for 99.5% of test datasets, comparable to radiologists' interreader reproducibility. The full network had significantly superior performance than the tiny network for 3D axial prescription in patients. Automated prescription performed well across single-shot fast spin-echo, gradient-echo, and balanced steady-state free-precession sequences in the prospective study. AI-based automated liver image prescription demonstrated promising performance across the patients, pathologies, and field strengths studied. 4. Stage 1.

Improved Single Breath-Hold SSFSE Sequence for Liver MRI Based on Compressed Sensing: Evaluation of Image Quality Compared with Conventional T2-Weighted Sequences.

The purpose of this study was to evaluate the image quality of compressed-sensing accelerated single-shot fast spin-echo (SSFSECS) sequences acquired within a single breath-hold in comparison with conventional SSFSE (SSFSECONV) and multishot TSE (mTSE). A total of 101 patients who underwent liver MRI at 3 T, including SSFSECONV (acquisition time (TA) = 58–62 s), mTSE (TA = 108 s), and SSFSECS (TA = 18 s), were included in this retrospective study. Two radiologists assessed the three sequences with respect to artifacts, organ sharpness, small structure visibility, overall image quality, and conspicuity of main lesions of liver and pancreas using a five-point evaluation scale system. Descriptive statistics and the Wilcoxon signed-rank test were used for statistical analysis. SSFSECS was significantly better than SSFSECONV and mTSE for artifacts, small structure visibility, overall image quality, and conspicuity of main lesions (p < 0.005). Regarding organ sharpness, mTSE and SSFSECS did not significantly differ (p = 0.554). Conspicuity of liver lesion did not significantly differ between SSFSECONV and mTSE (p = 0.404). SSFSECS showed superior image quality compared with SSFSECONV and mTSE despite a more than three-fold reduction in TA, suggesting a remarkable potential for saving time in liver imaging.

Visualization of the Anal Dimple by Fetal MRI: Is It Feasible?

Introduction: The aim of this study was to determine the feasibility of fetal MRI in identifying the normal anal dimple (AD) and compare it with prenatal ultrasound (US). Methods: Retrospective review of 130 patients with both fetal MRI and US. The gestational age (GA) was stratified into four groups: (1) 16 to 21 weeks-6 days; (2) 22 to 27 weeks-6 days; (3) 28 to 33 weeks-6 days; and (4) 34 weeks and beyond. Steady-state free precession (SSFP) and single shot fast spin echo (SSFSE) axial T2 MRI and transverse US images of the fetal perineum were analyzed, and visualization of the AD was determined. Clinical indication, gender, single versus multiple gestation, best MRI sequence where it was seen, and postnatal AD information were recorded. Results: The AD was visualized in 125/130 fetal MRIs, and visualization was independent of GA (p 0.230). US visualized the AD in 67/130 cases, and the best GA for visualization was in group 3 (p < 0.001). There was no difference in AD visualization between SSFSE and SSFP sequences (p 0.167). Conclusion: Prenatal visualization of the AD by MRI is feasible and superior to US, independent of GA. Adding AD visualization to routine screening prenatal US and MRI may increase recognition of anorectal malformation.

Magnetic Resonance Imaging and Magnetic Resonance Imaging Cholangiopancreatography of the Pancreas in Small Animals.

Simple SummaryIn human medicine Magnetic resonance imaging (MRI) and MR cholangiopancreatography (MRCP) play a consistent role in the investigation of pancreatic and pancreatic duct disorders. In veterinary medicine the number of studies focused on MR and MRCP for pancreatic disease is scant, and the protocols are not yet standardized. This review will focus on the MRI and MRCP technical aspects of the protocols used for the investigation of pancreatic disease in veterinary medicine. The aim of this review is to elucidate the value and the potential of each MR and MRCP sequence listed in the different protocols, either in canine or feline patients, with the intention to build a valid and solid tool for further innovative studies.Magnetic resonance imaging (MRI) and MR cholangiopancreatography (MRCP) have emerged as non-invasive diagnostic techniques for the diagnosis of pancreatic and pancreatic duct disorders in humans. The number of studies focused on MR and MRCP for pancreatic disease in small animals is very limited. MR has been described for the evaluation of insulinoma in dogs and to investigate pancreatitis in cats. The studies were based on a standard protocol with T2 weighted (w) fast recovery fast spin-echo (FRFSE) with and without fat suppression, T1w FSE pre-contrast and T1w FSE post-contrast with and without fat suppression. MRCP after secretin stimulation has been described in cats to assess the pancreatic ductal system, taking advantage of pulse sequences heavily T2w as rapid acquisition with rapid enhancement (RARE), fast-recovery fast spin-echo (FRFSE) sequences and single-shot fast spin-echo (SSFSE) sequences. In addition to the standard protocol, fast spoiled gradient recalled echo pulse sequences (fSPGR) and volume interpolated 3D gradient-echo T1w pulse sequences pre and post-contrast have also been used in cats, reaching the goal of assessing the biliary tree and the pancreatic duct with the same sequence and in multiple planes. Despite the small amount of data, the results show potential, and the most recent technical innovations, in particular, focused on diffusion MRI and fast acquisition, further support the need for continued evaluation of MRI as an effective instrument for the investigation of pancreatic disease.

Prospective comparative analysis for application and selection of FIESTA sequence and SSFSE sequence in MRI for prenatal diagnosis of placenta previa accreta

Placenta previa accreta patients were examined using fast-imaging employing steady-state acquisition (FIESTA) and single-shot fast spin echo (SSFSE) sequence. The diagnostic value of the two sequences was compared. FIESTA was better than the SSFSE sequence in displaying outline-boundary (excellent: 82 vs. 26), signal-to-noise ratio (excellent: 75 vs. 54) for placenta and uterus. The direct signs detection rate in FIESTA was higher than SSFSE (implantable: P = .028, adhesive: P = .131, penetrating type: P = .326). The indirect signs detection rate in FIESTA was lower than SSFSE (low-signal density: P = .029, uneven-signal density: P = .328, thicker and more vascular shadow: P = 398). FIESTA combining SSFSE demonstrated higher detecting rates (100% for sensitivity, specificity, and accuracy) for all types than single sequence scanning (FIESTA/SSFSE). In conclusion, FIESTA clearly showed the situation of the placenta and uterus in placenta previa accreta patients, with excellent image quality. A combination of FIESTA and SSFSE can improve the diagnostic value of placenta previa accreta. Important statement What is already known on this subject? Placenta previa is the most common cause of vaginal bleeding in the third trimester of pregnancy. What do the results of this study add? FIESTA was better than the SSFSE sequence in displaying images and demonstrated higher detection rates for direct signs and lower detection rate comparing the SSFSE sequence. FIESTA combining SSFSE sequence demonstrated higher detecting rates for implantable, adhesive and penetrating types than single sequence scanning. What are the implications of these findings for clinical practice and/or further research? FIESTA sequence clearly showed the situation of placenta and uterus in placenta previa accreta patients, with excellent image quality. Combination of FIESTA and SSFSE sequences can effectively improve the diagnostic value of placenta previa accreta.

Fetal periventricular pseudocysts: is MRI evaluation needed? What is the long-term neurodevelopmental outcome? Systematic review and meta-analysis.

To explore the value of magnetic resonance imaging (MRI) in fetuses with periventricular pseudocysts (PVPC) and the neurodevelopmental outcomes of these fetuses via meta-analysis. MEDLINE and EMBASE database were searched for studies reporting on the MRI assessment of fetuses diagnosed with PVPC on neurosonography. The neurosonography was conducted according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guidelines or standard axial, coronal and sagittal planes for advanced central nervous system (CNS) assessment. Single-shot fast spin-echo T2-weighted sequences of MRI technique in three orthogonal planes were necessarily performed. The pooled proportion of CNS anomalies missed on neurosonography and detected only at prenatal MRI was calculated. Subanalysis was performed according to the types of intracranial anomalies. The pregnancy outcomes (including normal, abnormal, termination of pregnancy, and perinatal death) of PVPC fetuses were also analyzed. Five studies comprising 136 fetuses were included in this meta-analysis. Mean gestational age was 29.8weeks (16-38weeks) at ultrasonography and 31.5weeks (25-37weeks) at MRI. Overall, MRI detected exclusively CNS anomalies in 25.2% (95% CI 15.9-35.8%) of cases. Among them, the highest incidence was white matter abnormalities with the pooled proportion of 16.3% (95% CI 9.7-24.2%). When getting rid of whitematter abnormalities, the risk of associated CNS anomalies only detected on MRI was reduced to 9.1% (95% CI 1.8-21.4%). Meanwhile, 130 cases were studied to assess the pregnancy outcomes with the scope of 1month to 10years. The pooled proportion of normal outcomes in isolated PVPC fetuses was as high as 95.0% (95% CI 83.9-99.8%). When analyzing the neurodevelopmental outcomes in non-isolated PVPC fetuses, the incidence of normal neurodevelopmental outcomes was about 22.1% (95% CI 5.6-45.5%) with mild and single additional abnormalities, the rate of abnormal neurodevelopmental outcomes was 19.5% (95% CI 11.0-29.7%) with apparent and/or multiple abnormalities. Besides, 53.6% (95% CI 35.4-71.3%) of non-isolated PVPC cases were terminated mainly due to infections, genetic anomalies, metabolic disorders and hemorrhage. MRI assessment of PVPC fetuses is recommended to detect associated intracranial anomalies that may be missed on dedicated neurosonography. White matter abnormalities on MRI account for the majority of additional anomalies, which might to be the clue of CMV infection, aminoacidopathy or white matter disease. Moreover, the neurodevelopmental outcome of isolated PVPC fetuses remains favorable, while the neurodevelopmental outcomes of non-isolated PVPC fetuses depend on the accompanying anomaly.

Clinical feasibility of an abdominal thin-slice breath-hold single-shot fast spin echo sequence processed using a deep learning-based noise-reduction approach

BackgroundT2-weighted imaging (T2WI) is a key sequence of MRI studies of the pancreas. The single-shot fast spin echo (single-shot FSE) sequence is an accelerated form of T2WI. We hypothesized that denoising approach with deep learning-based reconstruction (dDLR) could facilitate accelerated breath-hold thin-slice single-shot FSE MRI, and reveal the pancreatic anatomy in detail. PurposeTo assess the image quality of thin-slice (3 mm) respiratory-triggered FSE T2WI (Resp-FSE) and breath-hold fast advanced spin echo with and without dDLR (BH-dDLR-FASE and BH-FASE, respectively) at 1.5 T. Materials and methodsMR images of 42 prospectively enrolled patients with suspected pancreaticobiliary disease were obtained at 1.5 T. We qualitatively and quantitatively evaluated image quality of BH-dDLR-FASE related to BH-FASE and Resp-FSE. ResultsThe scan time of BH-FASE was significantly shorter than that of Resp-FSE (30 ± 4 s and 122 ± 25 s, p < 0.001). Qualitatively, dDLR significantly improved BH-FASE image quality, and the image quality of BH-dDLR-FASE was significantly better than that of Resp-FSE; as quantitative parameters, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of BH-dDLR-FASE were also significantly better than those of Resp-FSE. The BH-dDLR-FASE sequence covered the entire pancreas and liver and provided overall image quality rated close to excellent. ConclusionsThe dDLR technique enables accelerated thin-slice single-shot FSE, and BH-dDLR-FASE seems to be clinically feasible.

Free-breathing magnetic resonance imaging with radial k-space sampling for neonates and infants to reduce anesthesia.

Conventional chest and abdominal MRI require breath-holds to reduce motion artifacts. Neonates and infants require general anesthesia with intubation to enable breath-held acquisitions. We aimed to validate a free-breathing approach to reduce general anesthesia using a motion-insensitive radial acquisition with respiratory gating. We retrospectively enrolled children <3years old who were referred for MRI of the chest or abdomen. They were divided into two groups according to MRI protocol: (1) breath-held scans under general anesthesia with T2-weighted single-shot fast spin-echo (SSFSE) and contrast-enhanced T1-weighted modified Dixon, and (2) free-breathing scans using radial sequences (T2-W MultiVane XD and contrast-enhanced T1-W three-dimensional [3-D] Vane XD). Two readers graded image quality and motion artifacts. We included 23 studies in the free-breathing cohort and 22 in the breath-hold cohort. The overall imaging scores for the free-breathing radial T2-W sequence were similar to the scores for the breath-held T2-W SSFSE sequence (chest, 3.6 vs. 3.2, P=0.07; abdomen, 3.9 vs. 3.7, P=0.66). The free-breathing 3-D radial T1-W sequence also had image quality scores that were similar to the breath-held T1-W sequence (chest, 4.0 vs. 3.0, P=0.06; abdomen, 3.7 vs. 3.9, P=0.15). Increased motion was seen in the abdomen on the radial T2-W sequence (P<0.001), but increased motion was not different in the chest (P=0.73) or in contrast-enhanced T1-W sequences (chest, P=0.39; abdomen, P=0.15). The mean total sequence time was longer in free-breathing compared to breath-held exams (P<0.01); however, this did not translate to longer overall exam times (P=0.94). Motion-insensitive radial sequences used for infants and neonates were of similar image quality to breath-held sequences and had decreased sedation and intubation.

Impact of Deep Learning Reconstruction Combined With a Sharpening Filter on Single-Shot Fast Spin-Echo T2-Weighted Magnetic Resonance Imaging of the Uterus.

This study aimed to evaluate the effects of deep learning (DL) reconstruction and a postprocessing sharpening filter on the image quality of single-shot fast spin-echo (SSFSE) T2-weighted imaging (T2WI) of the uterus. Fifty consecutive patients who underwent pelvic magnetic resonance imaging were included. Parasagittal T2WI with a slice thickness of 4 mm was obtained with the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) and SSFSE sequences (mean scan time, 204 and 22 seconds, respectively). The following 3 types of SSFSE images were reconstructed, and the signal-to-noise ratio (SNR) and tissue contrast were assessed: conventional reconstruction (SSFSE-C), DL reconstruction (SSFSE-DL), and DL with a sharpening filter (SSFSE-DLF). Three radiologists independently assessed image quality, and area under the visual grading characteristics curve (AUCVGC) analysis was performed to compare the SSFSE and PROPELLER images. Compared with that of the PROPELLER images, the SNR of the SSFSE-C, SSFSE-DL, and SSFSE-DLF images was significantly lower (P < 0.05), significantly higher (P < 0.05), and equivalent, respectively. The SSFSE-DL images exhibited significantly lower contrast between the junctional zone and myometrium than those obtained with the other sequences (P < 0.05). In qualitative comparisons with the PROPELLER images, all 3 SSFSE sequences, SSFSE-DL, and SSFSE-DLF demonstrated significantly higher scores for artifacts, noise, and sharpness, respectively (P < 0.01). The overall image quality of SSFSE-C (mean AUCVGC, 0.03; P < 0.01) and SSFSE-DL (mean AUCVGC, 0.23; P < 0.01) was rated as significantly inferior, whereas that of SSFSE-DLF (mean AUCVGC, 0.69) was equivalent or significantly higher (P < 0.01). Using a combination of DL and a sharpening filter markedly increases the image quality of SSFSE of the uterus to the level of the PROPELLER sequence.

Enhancing the differentiation of pulmonary lymphoma and fungal pneumonia in hematological patients using texture analysis in 3-T MRI

ObjectivesTo evaluate texture analysis in nonenhanced 3-T MRI for differentiating pulmonary fungal infiltrates and lymphoma manifestations in hematological patients and to compare the diagnostic performance with that of signal intensity quotients (“nonenhanced imaging characterization quotients,” NICQs).MethodsMR scans were performed using a speed-optimized imaging protocol without an intravenous contrast medium including axial T2-weighted (T2w) single-shot fast spin-echo and T1-weighted (T1w) gradient-echo sequences. ROIs were drawn within the lesions to extract first-order statistics from original images using HeterogeneityCAD and PyRadiomics. NICQs were calculated using signal intensities of the lesions, muscle, and fat. The standard of reference was histology or clinical diagnosis in follow-up. Statistical testing included ROC analysis, clustered ROC analysis, and DeLong test. Intra- and interrater reliability was tested using intraclass correlation coefficients (ICC).ResultsThirty-three fungal infiltrates in 16 patients and 38 pulmonary lymphoma manifestations in 19 patients were included. Considering the leading lesion in each patient, diagnostic performance was excellent for T1w entropy (AUC 80.2%; p < 0.005) and slightly inferior for T2w energy (79.9%; p < 0.005), T1w uniformity (79.6%; p < 0.005), and T1w energy (77.0%; p < 0.01); the best AUC for NICQs was 72.0% for T2NICQmean (p < 0.05). Intra- and interrater reliability was good to excellent (ICC > 0.81) for these parameters except for moderate intrarater reliability of T1w energy (ICC = 0.64).ConclusionsT1w entropy, uniformity, and energy and T2w energy showed the best performances for differentiating pulmonary lymphoma and fungal pneumonia and outperformed NICQs. Results of the texture analysis should be checked for their intrinsic consistency to identify possible incongruities of single parameters.Key Points• Texture analysis in nonenhanced pulmonary MRI improves the differentiation of pulmonary lymphoma and fungal pneumonia compared with signal intensity quotients.• T1w entropy, uniformity, and energy along with T2w energy show the best performances for differentiating pulmonary lymphoma from fungal pneumonia.• The results of the texture analysis should be checked for their intrinsic consistency to identify possible incongruities of single parameters.

Measuring Knee Bone Marrow Perfusion Using Arterial Spin Labeling at 3\u2009T

Bone perfusion is an essential physiological measure reflecting vasculature status and tissue viability of the skeletal system. Arterial spin labeling (ASL), as a non-invasive and non-contrast enhanced perfusion imaging method, is an attractive approach for human research studies. To evaluate the feasibility of ASL perfusion imaging of knee bone marrow in the distal femoral condyle at a 3 T MRI scanner, a study was performed with eight healthy volunteers (three males and five females, 26 ± 2 years old) and two patients (male, 15 and 11 years old) with diagnosed stage II juvenile osteochondritis dissecans (JOCD). ASL imaging utilized a flow-sensitive alternating inversion recovery method for labeling and a single-shot fast spin echo sequence for image readout. In addition to quantitative knee bone marrow ASL imaging, studies were also performed to evaluate the effects of prolonged post-bolus delay and varied labeling size. ASL imaging was successfully performed with all volunteers. Despite the benefits of hyper-intensive signal suppression within bone marrow, the use of a prolonged post-bolus delay caused excessive perfusion signal decay, resulting in low perfusion signal-to-noise ratio (SNR) and poor image quality. Bone marrow perfusion signal changed with the labeling size, suggesting that the measured bone marrow perfusion signal is flow-associated. The means and standard deviations of bone marrow blood flow, spatial SNR, and temporal SNR from the quantitative perfusion study were 38.3 ± 5.2 mL/100 g/min, 3.31 ± 0.48, and 1.33 ± 0.31, respectively. The imaging results from JOCD patients demonstrated the potential of ASL imaging to detect disease-associated bone marrow perfusion changes. This study demonstrates that it is feasible to perform ASL imaging of knee bone marrow in the distal femoral condyle at 3 T.