T2-weighted Spin-echo Sequences Research Articles

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.

Radiomic-Based MRI for Classification of Solitary Brain Metastases Subtypes From Primary Lymphoma of the Central Nervous System.

Differential diagnosis of brain metastases subtype and primary central nervous system lymphoma (PCNSL) is necessary for treatment decisions. The application of machine learning facilitates the classification of brain tumors, but prior investigations into primary lymphoma and brain metastases subtype classification have been limited. To develop a machine-learning model to classify PCNSL, brain metastases with primary lung and non-lung origin. Retrospective. A total of 211 subjects with pathologically confirmed PCNSL or brain metastases (training cohort 168 and testing cohort 43). A 3.0 T axial contrast-enhanced T1-weighted spin-echo inversion recovery sequence (T1WI-CE), axial T2-weighted fluid-attenuation inversion recovery sequence (T2FLAIR) ASSESSMENT: Several machine-learning models (support vector machine, random forest, and K-nearest neighbors) were built with least absolute shrinkage and selection operator (LASSO) using features from T1WI-CE, T2FLAIR, and clinical. The model with the highest performance in the training cohort was selected to differentiate lesions in the testing cohort. Then, three radiologists conducted a two-round classification (with and without model reference) using images and clinical information from testing cohorts. Five-fold cross-validation was used for model evaluation and calibration. Model performance was assessed based on sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC). Twenty-five image features were selected by LASSO analysis. Random forest classifier was selected for its highest performance on the training set with an AUC of 0.73. After calibration, this model achieved an accuracy of 0.70 on the testing set. Accuracies of all three radiologists improved under model reference (0.49 vs. 0.70, 0.60 vs. 0.77, 0.58 vs. 0.72, respectively). The random forest model based on conventional MRI and clinical data can diagnose PCNSL and brain metastases subtypes (lung and non-lung origin). Model classification can help foster the diagnostic accuracy of specialists and streamline prognostication workflow. 4 TECHNICAL EFFICACY: Stage 2.

Impact of the implementation of a Contouring Atlas on Therapeutic Radiographer Inter-observer Contour Variation in Prostate Radiotherapy

Republished from RTi3 2021 due to author omission. Purpose: The clinical implementation of MR-guided adaptive radiotherapy requires fast, accurate delineation of target volumes and organs at risk (OAR's). It is important with the introduction of new online imaging strategies to mitigate the potential for contouring inaccuracies, as they could potentially result in treatment errors. To support the introduction of radiographer-led real-time MR-guided adaptive radiotherapy on the MR-Linac (MRL), an MR contouring atlas for prostate radiotherapy delineation guidance was developed. This tool was based on the ‘Male Pelvis Normal Tissue RTOG Consensus Contouring’ recommendations and local guidelines, and its impact on inter-observer variation was subsequently determined. Methods: Multi-disciplinary consensus on the contouring of the prostate, seminal vesicles and associated OAR's was obtained by developing a contouring guide (3 MRL radiographers, 2 clinical oncologists and 1 diagnostic radiographer). Contours were defined on T2-weighted three-dimensional turbo spin echo sequences, reconstructed axially (T2w 3D Tra) acquired on the MRL. To assess the guide's utility, 9 radiographers with varying MRL experience contoured 5 MRI scans in the Monaco treatment planning system, from 5 different patients (n= 25). Each radiographer contoured the prostate, seminal vesicles, bladder, and rectum on each data set before and after the introduction of the atlas. The ‘after’ contours were generated >21 days following the ‘before’ contours to minimise the effects of repetition. In addition to DICE coefficients and descriptive statistics, inter-observer contour variations, time to contour and observer contouring confidence was determined prior to and following the introduction of the atlas utilising a 5-point Likert scale (observers score confidence 1 not confident to 5 extremely confident). Results: The contouring atlas has been agreed by the multidisciplinary team incorporating locally defined gold-standard contours and RTOG guidance. Five sets of images from 5 different patients have been acquired on the MRL (T2w 3D Tra) and to date the ‘before’ contours have been completed. Mean contouring time without the atlas for all contours was 54 minutes with the rectum and prostate contouring taking the greatest amount of time, a mean time of 15 minutes each. Contour confidence levels varied between participants greatly. Minimum contour variability between the observers was for the bladder contour, with the maximum range being 22.0cm3. This corresponded with the participants scoring the bladder contour with the higher confidence level rates (majority scoring ≥ 3). Prostate and rectum structures had the greatest contour variability between observers with the maximum range being 32.6cm3 and 36.1 cm3 respectively. Confidence levels also corresponded with this large variation with majority of observers scoring ≤ 2. The same radiographers will repeat the process with the aid of the contouring atlas. Conclusion: It is anticipated that the new atlas for contouring prostate and surrounding OAR anatomy during both online and offline radiotherapy planning scenarios will reduce inter-observer variability, uncertainty and the time needed to contour. This will be of particular benefit in future adapt to shape pathways.

A Fetal Brain magnetic resonance Acquisition Numerical phantom (FaBiAN)

Accurate characterization of in utero human brain maturation is critical as it involves complex and interconnected structural and functional processes that may influence health later in life. Magnetic resonance imaging is a powerful tool to investigate equivocal neurological patterns during fetal development. However, the number of acquisitions of satisfactory quality available in this cohort of sensitive subjects remains scarce, thus hindering the validation of advanced image processing techniques. Numerical phantoms can mitigate these limitations by providing a controlled environment with a known ground truth. In this work, we present FaBiAN, an open-source Fetal Brain magnetic resonance Acquisition Numerical phantom that simulates clinical T2-weighted fast spin echo sequences of the fetal brain. This unique tool is based on a general, flexible and realistic setup that includes stochastic fetal movements, thus providing images of the fetal brain throughout maturation comparable to clinical acquisitions. We demonstrate its value to evaluate the robustness and optimize the accuracy of an algorithm for super-resolution fetal brain magnetic resonance imaging from simulated motion-corrupted 2D low-resolution series compared to a synthetic high-resolution reference volume. We also show that the images generated can complement clinical datasets to support data-intensive deep learning methods for fetal brain tissue segmentation.

Fast T2-weighted liver MRI: Image quality and solid focal lesions conspicuity using a deep learning accelerated single breath-hold HASTE fat-suppressed sequence

PurposeAcceleration of MRI acquisitions and especially of T2-weighted sequences is essential to reduce the duration of MRI examinations but also kinetic artifacts in liver imaging. The purpose of this study was to compare the acquisition time and the image quality of a single-shot fat-suppressed turbo spin-echo (TSE) T2-weighted sequence with deep learning reconstruction (HASTEDL) with that of a fat-suppressed T2-weighted BLADE TSE sequence in patients with focal liver lesions. Materials and methodsNinety-five patients (52 men, 43 women; mean age: 61 ± 14 [SD]; age range: 28–87 years) with 42 focal liver lesions (17 hepatocellular carcinomas, 10 sarcoidosis lesions, 9 myeloma lesions, 3 liver metastases and 3 focal nodular hyperplasias) who underwent liver MRI at 1.5 T including HASTEDL and BLADE sequences were retrospectively included. Overall image quality, noise level in the liver, lesion conspicuity and sharpness of liver lesion contours were assessed by two independent readers. Liver signal-to-noise ratio (SNR) and lesion contrast-to-noise ratio (CNR) were measured and compared between the two sequences, as well as the mean duration of the sequences (Student t-test or Wilcoxon test for paired data). ResultsMedian overall quality on HASTEDL images (3; IQR: 3, 3) was significantly greater than that on BLADE images (2; IQR: 1, 3) (P < 0.001). Median noise level in the liver on HASTEDL images (0; IQR: 0, 0.5) was significantly lower than that on BLADE images (1; IQR: 1, 2) (P < 0.001). On HASTEDL images, mean liver SNR (107.3 ± 39.7 [SD]) and mean focal liver lesion CNR (87.0 ± 76.6 [SD]) were significantly greater than those on BLADE images (67.1 ± 23.8 [SD], P < 0.001 and 48.6 ± 43.9 [SD], P = 0.027, respectively). Acquisition time was significantly shorter with the HASTEDL sequence (18 ± [0] s; range: 18–18 s) compared to BLADE sequence (152 ± 47 [SD] s; range: 87–263 s) (P < 0.001). ConclusionBy comparison with the BLADE sequence, HASTEDL sequence significantly reduces acquisition time while improving image quality, liver SNR and focal liver lesions CNR.

Cervical spine ligamentum flavum gaps: MR characterisation and implications for interlaminar epidural injection therapy

BackgroundCervical epidural steroid injections are commonly performed to manage pain from cervical spine disease. Cadaveric studies have demonstrated incomplete ligamentum flavum fusion in the central interlaminar region with resultant midline...

A novel male Japanese quail structural connectivity atlas using ultra-high field diffusion MRI at 11.7 T

The structural connectivity of animal brains can be revealed using post-mortem diffusion-weighted magnetic resonance imaging (MRI). Despite the existence of several structural atlases of avian brains, few of them address the bird’s structural connectivity. In this study, a novel atlas of the structural connectivity is proposed for the male Japanese quail (Coturnix japonica), aiming at investigating two lines divergent on their emotionality trait: the short tonic immobility (STI) and the long tonic immobility (LTI) lines. The STI line presents a low emotionality trait, while the LTI line expresses a high emotionality trait. 21 male Japanese quail brains from both lines were scanned post-mortem for this study, using a preclinical Bruker 11.7 T MRI scanner. Diffusion-weighted MRI was performed using a 3D segmented echo planar imaging (EPI) pulsed gradient spin-echo (PGSE) sequence with a 200 upmum isotropic resolution, 75 diffusion-encoding directions and a b-value fixed at 4500 s/mm2. Anatomical MRI was likewise performed using a 2D anatomical T2-weighted spin-echo (SE) sequence with a 150 upmum isotropic resolution. This very first anatomical connectivity atlas of the male Japanese quail reveals 34 labeled fiber tracts and the existence of structural differences between the connectivity patterns characterizing the two lines. Thus, the link between the male Japanese quail’s connectivity and its underlying anatomical structures has reached a better understanding.

Magnetic Resonance Imaging-Based Nomogram to Antenatal Predict Cesarean Delivery for Cephalopelvic Disproportion in Primiparous Women.

Cephalopelvic disproportion (CPD)-related obstructed labor is associated with maternal and neonatal morbidity and mortality. Accurate prediction of whether a primiparous woman is at high risk of an unplanned cesarean delivery would be a major advance in obstetrics. To develop and validate a predictive model assessing the risk of cesarean delivery in primiparous women based on MRI findings. Prospective. A total of 150 primiparous women with clinical findings suggestive of CPD. T1-weighted fast spin-echo sequences, single-shot fast spin-echo (SSFSE) T2-weighted sequences at 1.5T. Pelvimetry and fetal biometry were assessed independently by two radiologists. A nomogram model combined that the clinical and MRI characteristics was constructed. Univariable and multivariable logistic regression analyses were applied to select independent variables. Receiver operating characteristic (ROC) analysis was performed, and the discrimination of the model was assessed by the area under the curve (AUC). Calibration was assessed by calibration plots. Decision curve analysis was applied to evaluate the net clinical benefit. A P value below 0.05 was considered to be statistically significant. In multivariable modeling, the maternal body mass index (BMI) before delivery, bilateral femoral head distance, obstetric conjugate, fetal head circumference, and fetal abdominal circumference was significantly associated with the likelihood of cesarean delivery. The discrimination calculated as the AUC was 0.838 (95% confidence interval [CI]: 0.774-0.902). The sensitivity and specificity of the nomogram model were 0.787 and 0.764, and the positive predictive and negative predictive values were 0.696 and 0.840, respectively. The model demonstrated satisfactory calibration (calibration slope=0.945). Moreover, the decision curve analysis proved the superior net benefit of the model compared with each factor included. Our study might provide a nomogram model that could identify primiparous women at risk of cesarean delivery caused by CPD based on MRI measurements. 2 TECHNICAL EFFICACY: Stage 2.

A Multiparametric Fusion Deep Learning Model Based on DCE-MRI for Preoperative Prediction of Microvascular Invasion in Intrahepatic Cholangiocarcinoma.

Assessment of microvascular invasion (MVI) in intrahepatic cholangiocarcinoma (ICC) by using a noninvasive method is an unresolved issue. Deep learning (DL) methods based on multiparametric fusion of MR images have the potential of preoperative assessment of MVI. To investigate whether a multiparametric fusion DL model based on MR images can be used for preoperative assessment of MVI in ICC. Retrospective. A total of 519 patients (200 females and 319 males) with a single ICC were categorized as a training (n=361), validation (n=90), and an external test cohort (n=68). A 1.5 T and 3.0 T; axial T2-weighted turbo spin-echo sequence, diffusion-weighted imaging with a single-shot spin-echo planar sequence, and dynamic contrast-enhanced (DCE) imaging with T1-weighted three-dimensional quick spoiled gradient echo sequence. DL models of multiparametric fusion convolutional neural network (CNN) and late fusion CNN were both constructed for evaluating MVI in ICC. Gradient-weighted class activation mapping was used for visual interpretation of MVI status in ICC. The DL model performance was assessed through the receiver operating characteristic curve (ROC) analysis, and the area under the ROC curve (AUC) with the accuracy, sensitivity, and specificity were measured. P value &lt; 0.05 was considered as statistical significance. In the external test cohort, the proposed multiparametric fusion DL model achieved an AUC of 0.888 with an accuracy of 86.8%, sensitivity of 85.7%, and specificity of 87.0% for evaluating MVI in ICC, and the positive predictive value and negative predictive value were 63.2% and 95.9%, respectively. The late fusion DL model achieved a lower AUC of 0.866, with an accuracy of 83.8%, sensitivity of 78.6%, specificity of 85.2% for evaluating MVI in ICC. Our DL model based on multiparametric fusion of MRI achieved a good diagnostic performance in the evaluation of MVI in ICC. 3 TECHNICAL EFFICACY: Stage 2.

Understanding nanomedicine treatment in an aggressive spontaneous brain cancer model at the stage of early blood brain barrier disruption

Personalised nanomedicine is an advancing field which has developed significant improvements for targeting therapeutics to aggressive cancer and with fewer side effects. The treatment of gliomas such as glioblastoma (or other brain tumours), with nanomedicine is complicated by a commonly poor accumulation of drugs in tumour tissue owing to the partially intact blood-brain barrier (BBB). Nonetheless, the BBB becomes compromised following surgical intervention, and gradually with disease progression. Increased vasculature permeability generated by a tumour, combined with decreased BBB integrity, offers a mechanism to enhance therapeutic outcomes. We monitored a spontaneous glioma tumour model in immunocompetent mice with ongoing T2-weighted and contrast-enhanced T1-weighted magnetic resonance imaging gradient echo and spin echo sequences to predict an optimal “leakiness” stage for nanomedicine injections. To ascertain the effectiveness of targeted nanomedicines in treating brain tumours, subsequent systemic administration of targeted hyperbranched polymers was then utislised, to deliver the therapeutic payload when both the tumour and brain vascularity had become sufficiently susceptible to allow drug accumulation. Treatment with either doxorubicin-loaded hyperbranched polymer, or the same nanomedicine targeted to an ephrin receptor (EphA2) using a bispecific antibody, resulted in uptake of chemotherapeutic doxorubicin in the tumour and in reduced tumour growth. Compared to vehicle and doxorubicin only, nanoparticle delivered doxorubicin resulted in increased tumour apoptosis, while averting cardiotoxicity. This suggests that polyethylene based (PEGylated)-nanoparticle delivered doxorubicin could provide a more efficient treatment in tumours with a disrupted BBB, and that treatment should commence immediately following detection of gadolinium permeability, with early detection and ongoing ‘leakiness’ monitoring in susceptible patients being a key factor.

Multiparametric MRI-Based Radiomic Signature for Preoperative Evaluation of Overall Survival in Intrahepatic Cholangiocarcinoma After Partial Hepatectomy.

The clinical outcomes of patients with intrahepatic cholangiocarcinoma (ICC) after partial hepatectomy remain suboptimal. Identifying patients with poor outcomes before surgery is urgently required. To develop a multiparametric magnetic resonance imaging (MRI)-based radiomic signature to evaluate overall survival (OS) preoperatively and to investigate its incremental value for disease stratification. Retrospective. One hundred and sixty-three patients with pathologically defined ICC, divided into training (N=115) and validation sets (N=48). Three-dimensional T1-weighted gradient-echo sequence with and without contrast agent, T2-weighted fast spin-echo sequence, and diffusion-weighted imaging with single-shot echo-planar sequence at 1.5T or 3.0 T. OS was defined as the time from the date of surgery to death or last contact. The radiomic signature was built based on the least absolute shrinkage and selection operator regression model. A clinicopathologic-radiographic (CPR) model and a combined model integrating radiomic signature with CPR factors were developed with multivariable Cox regression models. Harrell's concordance index (C-index) was used to compare the discrimination of different models. Net reclassification index (NRI) and integrated discrimination improvement (IDI) were used to quantify the improvement of prognostic accuracy after adding radiomic signature. The high-risk patients of death defined by the radiomic signature showed significantly lower OS compared with low-risk patients in validation set (3-year OS 17.1% vs. 56.4%, P < 0.001). Integrating radiomic signature into tumor, node, and metastasis (TNM) staging system significantly improved the prognostic accuracy compared with TNM stage alone (validation set C-index 0.745 vs. 0.649, P=0.039, NRI improvement 39.9%-43.8%, IDI improvement 16.1%-19.4%). The radiomic signature showed no significant difference of C-index with postoperative CPR model (validation set, 0.698 vs. 0.674, P=0.752). Incorporating the radiomic signature into CPR model significantly improved prognostic accuracy (NRI improvement 32.5%-34.3%, IDI improvement 8.1%-12.9%). Multiparametric MRI-based radiomic signature is a potential biomarker for preoperative prognostic evaluation of ICC patients. 4 TECHNICAL EFFICACY: Stage 4.

Multiple-echo recombined gradient echo MR imaging of the temporomandibular joint.

The purpose of this study was to compare images generated by a multiple-echo recombined gradient echo (MERGE) with the proton density-weighted fast spin-echo (PD-weighted FSE) sequence, T1-weighted fast spin-echo sequence (T1-weighted FSE), and T2-weighted fast spin-echo sequence (T2-weighted FSE) for the diagnostic imaging of the temporomandibular joint (TMJ). Twenty-three patients with signs and symptoms of TMJ dysfunction were enrolled in this study. The four imaging modalities were used to examine the TMJ. Three images (lateral, middle, and medial parts of the condylar head) were reviewed by two radiologists, who rated the visibility of the disk and cortex of the condylar head. For the medial part of the TMJ, in cases with a normally positioned disk, the results of the MERGE and PD-weighted FSE techniques were significantly better than those of the T1-weighted FSE and T2-weighted FSE. For visibility of the cortex in the normally positioned disk, MERGE was significantly better than PD-weighted FSE [P < 0.0125 (0.05/4)] at the middle and medial parts of the TMJ. MERGE was also significantly better than T1-weighted FSE [P < 0.0125 (0.05/4)] and T2-weighted FSE [P < 0.0125 (0.05/4)]. MERGE is better for visualizing the condylar only at the middle and the medial aspects of the TMJ in a normally positioned disk.

Visual assessment of the placenta in antenatal magnetic resonance imaging across gestation in normal and compromised pregnancies: Observations from a large cohort study.

Visual assessment of the placenta in antenatal magnetic resonance imaging is important to confirm healthy appearances or to identify pathology complicating fetal anomaly or maternal disease. We assessed the placenta in a large cohort of 228 women with low and high risk pregnancies across gestation. All women gave written informed consent and were imaged using either a 3T Philips Achieva or 1.5T Philips Ingenia scanner. Images were acquired with a T2-weighted single shot turbo spin echo sequence of the whole uterus (thereby including placenta) for anatomical information. A structured approach to visual assessment of the placenta on T2-weighted imaging has been provided including determination of key anatomical landmarks to aid orientation, placental shape, signal intensity, lobularity and granularity. Transient factors affecting imaging are shown including the effect of fetal movement, gross fetal motion and contractions. Placental appearances across gestation in low risk pregnancies are shown and compared to pregnancies complicated by preeclampsia and chronic hypertension. The utility of other magnetic resonance techniques (T2* mapping as an indirect marker for quantifying oxygenation) and histological assessment alongside visual assessment of placental T2-weighted imaging are demonstrated. A systematic approach with qualitative descriptors for placental visual assessment using T2-weighted imaging allows confirmation of normal placental development and can detect placental abnormalities in pregnancy complications. T2-weighted imaging can be visually assessed alongside functional imaging (such as T2* maps) in order to further probe the visual characteristics seen.

Quantification of H217O by 1H-MR imaging at 3 T: a feasibility study

BackgroundIndirect 1H-magnetic resonance (MR) imaging of 17O-labelled water allows imaging in vivo dynamic changes in water compartmentalisation. Our aim was to describe the feasibility of indirect 1H-MR methods to evaluate the effect of H217O on the MR relaxation rates by using conventional a 3-T equipment and voxel-wise relaxation rates.MethodsMR images were used to calculate the R1, R2, and R2* relaxation rates in phantoms (19 vials with different H217O concentrations, ranging from 0.039 to 5.5%). Afterwards, an experimental animal pilot study (8 rats) was designed to evaluate the in vivo relative R2 brain dynamic changes related to the intravenous administration of 17O-labelled water in rats.ResultsThere were no significant changes on the R1 and R2* values from phantoms. The R2 obtained with the turbo spin-echo T2-weighted sequence with 20-ms echo time interval had the higher statistical difference (0.67 s−1, interquartile range 0.34, p < 0.001) and Spearman correlation (rho 0.79). The R2 increase was adjusted to a linear fit between 0.25 and 5.5%, represented with equation R2 = 0.405 concentration + 0.3215. The highest significant differences were obtained for the higher concentrations (3.1–5.5%). The rat brain MR experiment showed a mean 10% change in the R2 value after the H217O injection with progressive normalisation.ConclusionsIndirect 1H-MR imaging method is able to measure H217O concentration by using R2 values and conventional 3-T MR equipment. Normalised R2 relative dynamic changes after the intravenous injection of a H217O saline solution provide a unique opportunity to map water pathophysiology in vivo, opening the analysis of aquaporins status and modifications by disease at clinically available 3-T proton MR scanners.

Longitudinal Quantitative MRI Evaluation of Muscle Involvement in Amyotrophic Lateral Sclerosis.

Background: Biomarkers of disease progression and outcome measures are still lacking for patients with amyotrophic lateral sclerosis (ALS). Muscle MRI can be a promising candidate to track longitudinal changes and to predict response to the therapy in clinical trials.Objective: Our aim is to apply quantitative muscle MRI in the evaluation of disease progression, focusing on thigh and leg muscles of patients with ALS, and to explore the correlation between radiological and clinical scores.Methods: We enrolled newly diagnosed patients with ALS, longitudinally scored using the ALS Functional Rating Scale-Revised (ALSFRS-R), who underwent a 3T muscle MRI protocol including a 6-point Dixon gradient-echo sequence and multi-echo turbo spin echo (TSE) T2-weighted sequence for quantification of fat fraction (FF), cross-sectional area (CSA), and water T2 (wT2). A total of 12 muscles of the thigh and six muscles of the leg were assessed by the manual drawing of 18 regions of interest (ROIs), for each side. A group of 11 age-matched healthy controls (HCs) was enrolled for comparison.Results: 15 patients (M/F 8/7; mean age 62.2 years old, range 29–79) diagnosed with possible (n = 2), probable (n = 12), or definite (n = 1) ALS were enrolled. Eleven patients presented spinal onset, whereas four of them had initial bulbar involvement. All patients performed MRI at T0, nine of them at T1, and seven of them at T2. At baseline, wT2 was significantly elevated in ALS subjects compared to HCs for several muscles of the thigh and mainly for leg muscles. By contrast, FF was elevated in few muscles, and mainly at the level of the thigh. The applied mixed effects model showed that FF increased significantly in the leg muscles over time (mainly in the triceps surae) and that wT2 decreased significantly in line with worsening in the leg subscore of ALSFRS-R, mainly at the leg level and in the anterior and medial compartment of the thigh.Conclusions: Quantitative MRI represents a non-invasive tool that is able to outline the trajectory of pathogenic modifications at the muscle level in ALS. In particular, wT2 was found to be increased early in the clinical history of ALS and also tended to decrease over time, also showing a positive correlation with leg subscore of ALSFRS-R.

Q-Dixon and GRAPPATINI T2 Mapping Parameters: A Whole Spinal Assessment of the Relationship Between Osteoporosis and Intervertebral Disc Degeneration.

The relationship between osteoporosis and intervertebral disc (IVD) degeneration remains controversial. Novel quantitative Dixon (Q-Dixon) and GRAPPATINI T2 mapping techniques have shown potential for evaluating the biochemical components of the spine. To investigate the correlation of osteoporosis with IVD degeneration in postmenopausal women. Prospective. A total of 105 postmenopausal females (mean age, 65 years; mean body mass index, 26 kg/m2 ). 3 T; sagittal; 6-echo Q-Dixon, multiecho spin-echo GRAPPATINI T2 mapping, turbo spin echo (TSE) T1-weighted and TSE T2-weighted sequences. The subjects were divided into normal (N=47), osteopenia (N=28), and osteoporosis (N=30) groups according to quantitative computed tomography examination. The Pfirrmann grade of each IVD was obtained. Region of interest analysis was performed separately by two radiologists (X.L., with 10 years of experience, and S.C., with 20 years of experience) on a fat fraction map and T2 map to calculate the bone marrow fat fraction (BMFF) from the L1 to L5 vertebrae and the T2 values of each adjacent IVD separately. One-way analysis of variance, post-hoc comparisons, and Kruskal-Wallis H tests were performed to evaluate the differences in the magnetic resonance imaging parameters between the groups. The relationships between BMFF and the IVD features were analyzed using the Spearman correlation analysis and linear regression models. There were significant differences in BMFF among the three groups. The osteoporosis group had higher BMFF values (64.5 ± 5.9%). No significant correlation was found between BMFF and Pfirrmann grade (r=0.251, P=0.06). BMFF was significantly negatively correlated with the T2 of the adjacent IVD from L1 to L3 (r=-0.731; r=-0.637; r=-0.547), while significant weak correlations were found at the L4 to L5 levels (r=-0.337; r=-0.278). This study demonstrated that osteoporosis is associated with IVD degeneration. 2 TECHNICAL EFFICACY: Stage 4.

Pulmonary Imaging of Immunocompromised Patients during Hematopoietic Stem Cell Transplantation using Non-Contrast-Enhanced Three-Dimensional Ultrashort Echo Time (3D-UTE) MRI.

To evaluate the feasibility of non-contrast-enhanced three-dimensional ultrashort echo time (3D-UTE) MRI for pulmonary imaging in immunocompromised patients during hematopoietic stem cell transplantation (HSCT). MRI was performed using a stack-of-spirals 3D-UTE sequence (slice thickness: 2.34mm; matrix: 256 × 256; acquisition time: 12.7-17.6 seconds) enabling imaging of the entire thorax within single breath-holds. Patients underwent MRI before HSCT initiation, in the case of periprocedural pneumonia, before discharge, and in the case of re-hospitalization. Two readers separately assessed the images regarding presence of pleural effusions, ground glass opacities (GGO), and consolidations on a per lung basis. A T2-weighted (T2w) multi-shot Turbo Spin Echo sequence (BLADE) was acquired in coronal orientation during breath-hold (slice thickness: 6.00mm; matrix: 320 × 320; acquisition time: 3.1-5.5 min) and read on a per lesion basis. Low-dose CT scans in inspiration were used as reference and were read on a per lung basis. Only scans performed within a maximum of three days were included in the inter-method analyses. Interrater agreement, sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of 3D-UTE MRI were calculated. 67 MRI scans of 28 patients were acquired. A reference CT examination was available for 33 scans of 23 patients. 3D-UTE MRI showed high sensitivity and specificity regarding pleural effusions (n = 6; sensitivity, 92 %; specificity, 100 %) and consolidations (n = 22; sensitivity 98 %, specificity, 86 %). Diagnostic performance was lower for GGO (n = 9; sensitivity, 63 %; specificity, 84 %). Accuracy rates were high (pleural effusions, 98 %; GGO, 79 %; consolidations 94 %). Interrater agreement was substantial for consolidations and pleural effusions (κ = 0.69-0.82) and moderate for GGO (κ = 0.54). Compared to T2w imaging, 3D-UTE MRI depicted the assessed pathologies with at least equivalent quality and was rated superior regarding consolidations and GGO in ~50 %. Non-contrast 3D-UTE MRI enables radiation-free assessment of typical pulmonary complications during HSCT procedure within a single breath-hold. Yet, CT was found to be superior regarding the identification of pure GGO changes. · 3D-UTE MRI of the thorax can be acquired within a single breath-hold.. · 3D-UTE MRI provides diagnostic imaging of pulmonary consolidations and pleural effusions.. · 3D-UTE sequences improve detection rates of ground glass opacities on pulmonary MRI.. · 3D-UTE MRI depicts pulmonary pathologies at least equivalent to T2-weighted Blade sequence.. · Metz C, Böckle D, Heidenreich JF et al. Pulmonary Imaging of Immunocompromised Patients during Hematopoietic Stem Cell Transplantation using Non-Contrast-Enhanced Three-Dimensional Ultrashort Echo Time (3D-UTE) MRI. Fortschr Röntgenstr 2022; 194: 39 - 48.

Orthotopic Versus Allotopic Implantation: Comparison of Radiological and Pathological Characteristics.

BackgroundIn experimental animal models, implantation location might influence the heterogeneity and overall development of the tumor, leading to an interpretation bias.PurposeTo investigate the effects of implantation location in experimental tumor model using magnetic resonance imaging (MRI) and pathological findings.Study TypeProspective.SubjectsForty‐five breast cancer‐bearing mice underwent orthotopic (N = 15) and heterotopic (intrahepatic [N = 15] and subcutaneous [N = 15]) implantation.Field Strength/SequenceSequences including: T1‐weighted turbo spin echo sequence, T2‐weighted blade sequence, diffusion‐weighted imaging, pre‐ and post‐contrast T1 mapping, multi‐echo T2 mapping at 3.0 T.AssessmentMRI was performed at 7, 14, and 21 days after implantation. Native T1, post‐contrast T1, T2, and apparent diffusion coefficient (ADC) of tumors, the tumor volume and necrosis volume within tumor were obtained. Lymphocyte cells from H&E staining, Ki67‐positive, and CD31‐positive cells from immunohistochemistry were determined.Statistical TestsOne‐way analysis of variance and Spearman's rank correlation were performed. P value <0.05 was considered statistically significant.ResultsThe tumor volume (intrahepatic vs. orthotopic vs. subcutaneous: 587.50 ± 77.62 mm3 vs. 814.00 ± 43.85 mm3 vs. 956.13 ± 119.22 mm3), necrosis volume within tumor (89.10 ± 26.60 mm3 vs. 292.41 ± 57.92 mm3 vs. 179.91 ± 31.73 mm3, respectively), ADC at day 21 (543.41 ± 42.28 vs. 542.92 ± 99.67 vs. 369.83 ± 42.90, respectively), and post‐contrast T1 at all timepoints (day 7: 442.00 ± 11.52 vs. 435.00 ± 22.90 vs. 394.33 ± 29.95; day 14: 459.00 ± 26.11 vs. 436.83 ± 26.01 vs. 377.00 ± 27.83; day 21: 463.50 ± 23.49 vs. 458.00 ± 34.28 vs. 375.00 ± 30.55) were significantly different between three groups. Necrosis volumes of subcutaneous and intrahepatic tumors were significantly lower than those of orthotopic tumors. The CD31‐positive rate in the intrahepatic implantation was significantly higher than in orthotopic and subcutaneous groups. Necrosis volume (r = −0.71), ADC (r = −0.85), and post‐contrast T1 (r = −0.75) were strongly correlated with vascular invasion index.Data ConclusionOrthotopic and heterotopic tumors have their unique growth kinetics, necrosis volume, and vascular invasion. Non‐invasive MR quantitative parameters, including ADC and post‐contrast T1, may reflect vascular invasion in mice.Level of Evidence1Technical EfficacyStage 3

Diagnostic value of gadolinium contrast administration for spinal cord magnetic resonance imaging in multiple sclerosis patients and correlative markers of lesion enhancement

BackgroundMagnetic resonance imaging is essential for monitoring people with multiple sclerosis, but the diagnostic value of gadolinium contrast administration in spine magnetic resonance imaging is unclear.ObjectiveTo assess the diagnostic value of gadolinium contrast administration in spine magnetic resonance imaging follow-up examinations and identify imaging markers correlating with lesion enhancement.MethodsA total of 65 multiple sclerosis patients with at least 2 spinal magnetic resonance imaging follow-up examinations were included. Spine magnetic resonance imaging was performed at 3 Tesla with a standardized protocol (sagittal and axial T2-weighted turbo spin echo and T1-weighted post-contrast sequences). T2 lesion load and enhancing lesions were assessed by two independent neuroradiologists for lesion size, localization, and T2 signal ratio (T2 signallesion/T2 signalnormal appearing spinal cord).ResultsA total of 68 new spinal T2 lesions and 20 new contrast-enhancing lesions developed during follow-up. All enhancing lesions had a discernable correlate as a new T2 lesion. Lesion enhancement correlated with a higher T2 signal ratio compared to non-enhancing lesions (T2 signal ratio: 2.0 ± 0.4 vs. 1.4 ± 0.2, ****p < 0.001). Receiver operating characteristics analysis showed an optimal cutoff value of signal ratio 1.78 to predict lesion enhancement (82% sensitivity and 97% specificity).ConclusionGadolinium contrast administration is dispensable in follow-up spine magnetic resonance imaging if no new T2 lesions are present. Probability of enhancement correlates with the T2 signal ratio.

Intraindividual Comparison between the Contrast-Enhanced Golden-Angle Radial Sparse Parallel Sequence and the Conventional Fat-Suppressed Contrast-Enhanced T1-Weighted Spin-Echo Sequence for Head and Neck MRI.

The golden-angle radial sparse parallel-volumetric interpolated breath-hold (GRASP-VIBE) sequence is a recently introduced imaging technique with high resolution. This study compared the image quality between conventional fat-suppressed T1-weighted TSE and GRASP-VIBE after gadolinium enhancement in the head and neck region. Data from 65 patients with clinical indications for head and neck MR imaging between September 2020 and January 2021 were retrospectively reviewed. Two radiologists assessed the overall image quality, overall artifacts, and image conspicuities in the oropharynx, hypopharynx, and cervical lymph nodes according to 5-point scores (best score: 5). Interobserver agreement was assessed using weighted κ statistics. The SNR and contrast-to-noise ratio were calculated and compared between the 2 sequences using a paired Wilcoxon signed rank test. The analysis included 52 patients (mean age, 60 [SD, 14 ] years; male, 71.2% [37/52]) who were mostly diagnosed with head and neck malignancies (94.3% [50/52]). κ statistics ranged from slight agreement in cervical lymph node conspicuity (κ = 0.18) to substantial agreement in oropharyngeal mucosal conspicuity (κ = 0.80) (κ range, 0.18-0.80). Moreover, GRASP-VIBE demonstrated significantly higher mean scores in overall image quality (4.68 [SD, 0.41] versus 3.66 [SD, 0.73]), artifacts (4.47 [SD, 0.48] versus 3.58 [SD, 0.71]), oropharyngeal mucosal conspicuity (4.85 [SD, 0.41] versus 4.11 [SD, 0.79]), hypopharyngeal mucosal conspicuity (4.84 [SD, 0.34] versus 3.58 [SD, 0.81]), and cervical lymph node conspicuity (4.79 [SD, 0.32] versus 4.08 [SD, 0.64]) than fat-suppressed T1-weighted TSE (all, P < .001). Furthermore, GRASP-VIBE demonstrated a higher SNR (22.8 [SD, 11.5] versus 11.3 [SD, 5.6], P < .001) and contrast-to-noise ratio (4.7 [SD, 5.4] versus 2.3 [SD, 2.7], P = .059) than fat-suppressed T1-weighted TSE. GRASP-VIBE provided better image quality with fewer artifacts than conventional fat-suppressed T1-weighted TSE for the head and neck regions.