3D B1+ corrected simultaneous myocardial T1 and T1ρ mapping with subject-specific respiratory motion correction and water-fat separation.

PURPOSE: To develop a 3D free-breathing cardiac multi-parametric mapping framework that is robust to confounders of respiratory motion, fat, and B1+ inhomogeneities and validate it for joint myocardial T1 and T1ρ mapping at 3T. METHODS: An electrocardiogram-triggered sequence with dual-echo Dixon readout was developed, where nine cardiac cycles were repeatedly acquired with inversion recovery and T1ρ preparation pulses for T1 and T1ρ sensitization. A subject-specific respiratory motion model relating the 1D diaphragmatic navigator to the respiration-induced 3D translational motion of the heart was constructed followed by respiratory motion binning and intra-bin 3D translational and inter-bin non-rigid motion correction. Spin history B1+ inhomogeneities were corrected with optimized dual flip angle strategy. After water-fat separation, the water images were matched to the simulated dictionary for T1 and T1ρ quantification. Phantoms and 10 heathy subjects were imaged to validate the proposed technique. RESULTS: The proposed technique achieved strong correlation (T1: R2 = 0.99; T1ρ: R2 = 0.98) with the reference measurements in phantoms. 3D cardiac T1 and T1ρ maps with spatial resolution of 2 × 2 × 4 mm were obtained with scan time of 5.4 ± 0.5 min, demonstrating comparable T1 (1236 ± 59 ms) and T1ρ (50.2 ± 2.4 ms) measurements to 2D separate breath-hold mapping techniques. The estimated B1+ maps showed spatial variations across the left ventricle with the septal and inferior regions being 10%-25% lower than the anterior and septal regions. CONCLUSION: The proposed technique achieved efficient 3D joint myocardial T1 and T1ρ mapping at 3T with respiratory motion correction, spin history B1+ correction and water-fat separation.

Immediate changes in stroke patients' gait following the application of lower extremity elastic strap binding technique.

Objective: To ascertain the immediate changes in stroke patients' temporal and spatial parameters of gait and the joint angles of stroke patients throughout the entire gait cycle following the application of lower extremity elastic strap binding technique. Methods: Twenty-nine stroke patients were invited as the study participants. The patient seated, flexed the hip and knee, utilized a 5 cm-wide elastic strap, positioning its midpoint beneath the affected foot and crossing it anterior to the ankle joint. Upon standing, the strap encircled the posterior aspect of the lower leg, proceeded around the back of the knee, and ascended the thigh on the affected side. Crossing anteriorly over the thigh, it then encircled the back of the waist before being secured in place. Using Qualisys motion capture system to collect kinematic data of the lower extremities during walking while wearing shoes only or strapping. A paired sample t-test was used to analyze the effects of the technique on gait spatiotemporal parameters and joint angles in stroke patients. Results: The patients' step length decreased (P = 0.024), and step width increased (P = 0.008) during the gait cycle after the strapping. In the gait cycle between 0% and 2%, 7%-77%, and 95%-100%, the hip flexion angle on the affected side was significantly larger after the strapping (P < 0.05). In the gait cycle between 0% to 69% and 94%-100%, the knee flexion angle on the affected side was significantly larger after the strapping (P < 0.05). In the gait cycle between 0% to 57% and 67%-100%, the ankle dorsiflexion angle on the affected side was significantly smaller after the strapping (P < 0.05), and in the gait cycle between 0% to 35% and 68%-100%, the ankle inversion angle on the affected side was significantly smaller after the strapping (P < 0.05). Conclusion: The lower extremity elastic strap binding technique can decrease the hip flexion and knee flexion limitations in stroke patients during walking, and reduce the ankle plantar flexion and ankle inversion angle of stroke patients. The lower extremity elastic strap binding technique enabled stroke patients to adopt a more stable gait pattern.

Practice Patterns of Cardiovascular Magnetic Resonance Use in the Diagnosis of Pediatric Myocarditis: A Survey-Based Study.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is used to diagnose myocarditis in adults and children based on the original Lake Louise Criteria (LLC) and more recently the revised LLC. The major change included in the revised LLC was the incorporation of parametric mapping, which significantly increases the sensitivity and specificity of diagnosis. Subsequently, scientific statements have recommended the use of parametric mapping in the diagnosis of myocarditis in children. However, there are some challenges to parametric mapping that are unique to the pediatric population. Our goal is to characterize clinical CMR and parametric mapping practice patterns for diagnosis of myocarditis in pediatric centers. METHODS: The Cardiovascular Magnetic Resonance Evaluation in Return to Athletes for Myocarditis in COVID-19 and Immunization Consortium created a REDCap survey to evaluate clinical practice patterns for diagnosis of myocarditis in pediatrics. This survey was distributed to the Society for Cardiovascular Magnetic Resonance community. RESULTS: 59 responses from 51 centers were received, with only one response from each center being utilized. Only 35% of centers (37% of North America, 31% of international) reported using CMR routinely in all patients with a suspicion for myocarditis. Diagnostic uncertainty was noted as the most important reason for CMR, while cost was noted as the least important consideration. The majority of centers reported using the revised LLC (37/51, 72%) compared to original LLC (7/51, 14%) or a hybrid criteria (6/51, 12%). When looking at the use of parametric mapping, only 5/47 (11%) for T1 mapping and 11/49 (22%) for T2 mapping reported having scanner-specific pediatric normative data. CONCLUSION: Routine CMR imaging for diagnosis of myocarditis in pediatrics is infrequently performed at surveyed centers despite the focus on a group of non-invasive cardiac imagers. While the majority reported using parametric mapping, few centers reporting having pediatric scanner-specific normative data. This highlights an important gap in the utilization of CMR that may aid in the diagnosis of myocardial disease.

Neural basis of false recognition in Alzheimer's disease and dementia with lewy bodies.

In Alzheimer's disease (AD), reports on the association between false recognition and brain structure have been inconsistent. In dementia with Lewy bodies (DLB), no such association has been reported. This study aimed to identify brain regions associated with false recognition in AD and DLB by analyzing regional gray matter volume (rGMV). We included 184 patients with AD and 60 patients with DLB. The number of false recognitions was assessed using the Alzheimer's Disease Assessment Scale' word recognition task. Brain regions associated with the number of false recognitions were examined by voxel-based morphometry analysis. The number of false recognitions significantly negatively correlated with rGMV in the bilateral hippocampus, left parahippocampal gyrus, bilateral amygdala, and bilateral entorhinal cortex in patients with AD (p < 0.05, family-wise error [FEW] corrected) and in the bilateral hippocampus, left parahippocampal gyrus, right inferior frontal gyrus, right middle frontal gyrus, right basal forebrain, right insula, left medial and lateral orbital gyri, and left fusiform in those with DLB (p < 0.05, FWE corrected). Bilateral hippocampus and left parahippocampal gyrus were associated with false recognition in both diseases. However, we found there were regions where the association between false recognition and rGMV differed from disease to disease.

Differences in cricket fast bowling kinematics between grass and artificial surface pitches.

Cricket fast bowling training and research are often conducted on artificial turf, while matches are played on natural grass. It is unknown if technique differs between the different surfaces; therefore, the aim of this study was to explore if fast bowling technique differed between surfaces. Shoe slip distance and kinematic and temporal parameters previously associated with ball release velocity and lumbar bone stress injury were determined for eight male sub-elite fast bowlers using three-dimensional motion analysis on grass and artificial surfaces. Paired t-test and statistical parametric mapping were used to identify differences in technique between surfaces. Significantly greater slip distance was observed during back and front foot contact on the artificial surface compared to bowling on the grass surface. No kinematic or temporal parameter significantly differed between surfaces, therefore fast bowling technique is likely similar between grass and artificial surfaces, and previous research utilising artificial surfaces in fast bowling research is likely to be valid.

Retrospective motion correction for cardiac multi-parametric mapping with dictionary matching-based image synthesis and a low-rank constraint.

PURPOSE: To develop a model-based motion correction (MoCo) method that does not need an analytical signal model to improve the quality of cardiac multi-parametric mapping. METHODS: The proposed method constructs a hybrid loss that includes a dictionary-matching loss and a signal low-rankness loss, where the former registers the multi-contrast original images to a set of motion-free synthetic images and the latter forces the deformed images to be spatiotemporally coherent. We compared the proposed method with non-MoCo, a pairwise registration method (Pairwise-MI), and a groupwise registration method (pTVreg) via a free-breathing Multimapping dataset of 15 healthy subjects, both quantitatively and qualitatively. RESULTS: The proposed method achieved the lowest contour tracking errors (epicardium: 2.00 ± 0.39 mm vs 4.93 ± 2.29 mm, 3.50 ± 1.26 mm, and 2.61 ± 1.00 mm, and endocardium: 1.84 ± 0.34 mm vs 4.93 ± 2.40 mm, 3.43 ± 1.27 mm, and 2.55 ± 1.09 mm for the proposed method, non-MoCo, Pairwise-MI, and pTVreg, respectively; all p < 0.01) and the lowest dictionary matching errors among all methods. The proposed method also achieved the highest scores on the visual quality of mapping (T1: 4.74 ± 0.33 vs 2.91 ± 0.82, 3.58 ± 0.87, and 3.97 ± 1.05, and T2: 4.48 ± 0.56 vs 2.59 ± 0.81, 3.56 ± 0.93, and 4.14 ± 0.80 for the proposed method, non-MoCo, Pairwise-MI, and pTVreg, respectively; all p < 0.01). Finally, the proposed method had similar T1 and T2 mean values and SDs relative to the breath-hold reference in nearly all myocardial segments, whereas all other methods led to significantly different T1 and T2 measures and increases of SDs in multiple segments. CONCLUSION: The proposed method significantly improves the motion correction accuracy and mapping quality compared with non-MoCo and alternative image-based methods.

Male-female spatio-temporal differences of age-related bone changes show faster bone deterioration in older women at femoral regions associated with incident hip fracture.

A better understanding of how age-related bone loss affects the fracture-prone regions of the proximal femur could lead to more informed fracture-prevention strategies. Therefore, the aim of this work was to assess the spatio-temporal distribution of bone deterioration in older men and women with aging. A subset of 305 men (74.87 ± 4.76 years; mean ± SD) and 371 age-matched women (74.84 ± 4.71 years) with no history of fracture was randomly selected from the Age, Gene/Environment Susceptibility-Reykjavik study. Quantitative computed tomography (QCT) scans of the left proximal femur obtained at baseline and at 5.2 ± 0.4 years follow-up were processed to assess local changes in volumetric bone mineral density (vBMD), cortical bone thickness (Ct.Th), and internal bone structure using voxel-based morphometry (VBM), surface-based statistical parametric mapping (surf-SPM), and tensor-based morphometry (TBM). Local parametric changes within each sex and sex differences in these changes were statistically assessed using linear mixed effects models allowing for baseline and time-varying covariates, yielding Student's t-test and p-value statistical maps of the proximal femur. The statistical maps indicated regions with significant parametric changes in each sex and with significant different parametric changes between older men and older women with aging. Older women manifested significantly larger losses in vBMD, (Ct.Th), and structure than older men, and they did so in regions where deficiency in these parameters has been associated with incident hip fracture. Using longitudinal QCT scans of the proximal femur and Computational Anatomy, we provided new insights into the higher fracture rates of the proximal femur in older women compared with men of similar age providing new information on the pathophysiology of osteoporosis.

Fast cardiac T1ρ,adiab mapping using slice-selective adiabatic spin-lock preparation pulses.

PURPOSE: Myocardial T1ρ mapping techniques commonly acquire multiple images in one breathhold to calculate a single-slice T1ρ map. Recently, non-selective adiabatic pulses have been used for robust spin-lock preparation (T1ρ,adiab). The objective of this study was to develop a fast multi-slice myocardial T1ρ,adiab mapping approach. METHODS: The proposed-sequence reduces the number of breathholds required for whole-heart 2D T1ρ,adiab mapping by acquiring multiple interleaved slices in each breathhold using slice-selective T1ρ,adiab preparation pulses. The proposed-sequence was implemented with two interleaved slices per breathhold scan and was quantitatively evaluated in phantom experiments and 10 healthy-volunteers against a single-slice T1ρ,adiab mapping sequence. The sequence was demonstrated in two patients with myocardial scar. RESULTS: The phantom experiments showed the proposed-sequence had slice-to-slice variation of 1.62% ± 1.05% and precision of 4.51 ± 0.68 ms. The healthy volunteer cohort subject-wise mean relaxation time was lower for the proposed-sequence than the single-slice sequence (137.7 ± 5.3 ms vs. 148.4 ± 8.3 ms, p < 0.001), and spatial-standard-deviation was better (18.7 ± 1.8 ms vs. 21.8 ± 3.4 ms, p < 0.018). The mean within-subject, coefficient of variation was 5.93% ± 1.57% for the proposed-sequence and 6.31% ± 1.92% for the single-slice sequence (p = 0.35) and the effect of slice variation (0.81 ± 4.87 ms) was not significantly different to zero (p = 0.61). In both patient examples increased T1ρ,adiab (maximum American Heart Association-segment mean = 174 and 197 ms) was measured within the myocardial scar. CONCLUSION: The proposed sequence provides a twofold acceleration for myocardial T1ρ,adiab mapping using a multi-slice approach. It has no significant difference in within-subject variability, and significantly better precision, compared to a 2D T1ρ,adiab mapping sequence based on non-selective adiabatic spin-lock preparations.

Unraveling stroke gait deviations with movement analytics, more than meets the eye: a case control study.

Background: This study aimed to identify and quantify the kinematic and kinetic gait deviations in post-stroke hemiplegic patients with matched healthy controls using Statistical Parametric Mapping (SPM). Methods: Fifteen chronic stroke patients [4 females, 11 males; age 53.7 (standard deviation 12.2) years; body mass 65.4 (10.4) kg; standing height 168.5 (9.6) cm] and 15 matched healthy controls [4 females, 11 males; age 52.9 (11.7) years; body weight 66.5 (10.7) years; standing height 168.3 (8.8) cm] were recruited. In a 10-m walking task, joint angles, ground reaction forces (GRF), and joint moments were collected, analyzed, and compared using SPM for an entire gait cycle. Results: Generally, when comparing the stroke patients' affected (hemiplegic) and less-affected (contralateral) limbs with the control group, SPM identified significant differences in the late stance phase and early swing phase in the joint angles and moments in bilateral limbs (all p < 0.005). In addition, the vertical and anteroposterior components of GRF were significantly different in various periods of the stance phase (all p < 0.005), while the mediolateral component showed no differences between the two groups. Conclusion: SPM was able to detect abnormal gait patterns in both the affected and less-affected limbs of stroke patients with significant differences when compared with matched controls. The findings draw attention to significant quantifiable gait deviations in the less-affected post-stroke limb with the potential impact to inform gait retraining strategies for clinicians and physiotherapists.

Insights on the Selection of the Coefficient of Variation to Assess Speed Fluctuation in Swimming.

The aim of this study was to compare swimming speed and speed fluctuations in front crawl between swimmers of different performance levels using discrete variables against statistical parametric mapping (SPM). The sample was composed of 34 male swimmers divided into three groups: (i) group #1-recreational swimmers; (ii) group #2-competitive swimmers aged 12 to 14 years; (iii) group #3-competitive swimmers aged 15 to 17 years. Swimming speed and speed fluctuations (calculated based on four different conditions) were used as discrete variables. Using these discrete variables, ANOVA one-way was used to verify differences between groups, and Bonferroni post-hoc correction for pairwise comparison whenever suitable. SPM (with similar statistical tests) was used to analyze the swimming speed and fluctuation as a continuous variable. Overall, both statistical approaches revealed significant differences (p < 0.001) in swimming speed and speed fluctuations. However, as discrete variables (in four different conditions), the speed fluctuation was not able to detect significant differences between groups #2 and #3. Conversely, SPM was more sensitive and did yield significant differences between these two groups. Therefore, researchers and coaches should be aware that the speed fluctuation as a discrete variable may not identify differences in swimming speed fluctuations when the average value between groups is marginal. On the other hand, SPM was more sensitive in analyzing all groups.

Individual factors determine landing impacts in rested and fatigued cheerleaders.

High vertical ground reaction forces (VGRF) during landings following acrobatic elements in artistic gymnastics is associated with trunk and lower extremity injury risk. As similar data regarding injury risk factors in cheerleading are scarce, the purpose of this study was to assess VGRF in pop-off dismounts of rested and fatigued flyers in cheerleaders. Fifteen German cheerleaders were recruited for this study, including seven female flyers and eight male bases. It was expected that performance would change in fatiguing athletes, potentially increasing the risk for injuries. However, neither the mean VGRF (rested: 6.0 ± 1.9 BW, fatigued: 6.2 ± 1.3 BW, overall range: 2.1-14.9 BW) nor the individual VGRF-time courses of the flyers changed significantly after the workout. Instead, we show that the flyers' ability to land - but not the bases' ability to catch - significantly influences the maximum and time-resolved impacts.

Clinical Applications of Cardiac Magnetic Resonance Parametric Mapping.

Cardiovascular magnetic resonance (CMR) imaging is widely regarded as the gold-standard technique for myocardial tissue characterization, allowing for the detection of structural abnormalities such as myocardial fatty replacement, myocardial edema, myocardial necrosis, and/or fibrosis. Historically, the identification of abnormal myocardial regions relied on variations in tissue signal intensity, often necessitating the use of exogenous contrast agents. However, over the past two decades, innovative parametric mapping techniques have emerged, enabling the direct quantitative assessment of tissue magnetic resonance (MR) properties on a voxel-by-voxel basis. These mapping techniques offer significant advantages by providing comprehensive and precise information that can be translated into color-coded maps, facilitating the identification of subtle or diffuse myocardial abnormalities. As unlikely conventional methods, these techniques do not require a substantial amount of structurally altered tissue to be visually identifiable as an area of abnormal signal intensity, eliminating the reliance on contrast agents. Moreover, these parametric mapping techniques, such as T1, T2, and T2* mapping, have transitioned from being primarily research tools to becoming valuable assets in the clinical diagnosis and risk stratification of various cardiac disorders. In this review, we aim to elucidate the underlying physical principles of CMR parametric mapping, explore its current clinical applications, address potential pitfalls, and outline future directions for research and development in this field.

Neuromuscular fatigue and cognitive constraints independently modify lower extremity landing biomechanics in healthy and chronic ankle instability individuals.

The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.

Inter-joint coordination with and without dopaminergic medication in Parkinson's disease: a case-control study.

BACKGROUND: How the joints exactly move and interact and how this reflects PD-related gait abnormalities and the response to dopaminergic treatment is poorly understood. A detailed understanding of these kinematics can inform clinical management and treatment decisions. The aim of the study was to investigate the influence of different gait speeds and medication on/off conditions on inter-joint coordination, as well as kinematic differences throughout the whole gait cycle in well characterized pwPD. METHODS: 29 controls and 29 PD patients during medication on, 8 of them also during medication off walked a straight walking path in slow, preferred and fast walking speeds. Gait data was collected using optical motion capture system. Kinematics of the hip and knee and coordinated hip-knee kinematics were evaluated using Statistical Parametric Mapping (SPM) and cyclograms (angle-angle plots). Values derived from cyclograms were compared using repeated-measures ANOVA for within group, and ttest for between group comparisons. RESULTS: PD gait differed from controls mainly by lower knee range of motion (ROM). Adaptation to gait speed in PD was mainly achieved by increasing hip ROM. Regularity of gait was worse in PD but only during preferred speed. The ratios of different speed cyclograms were smaller in the PD groups. SPM analyses revealed that PD participants had smaller hip and knee angles during the swing phase, and PD participants reached peak hip flexion later than controls. Withdrawal of medication showed an exacerbation of only a few parameters. CONCLUSIONS: Our findings demonstrate the potential of granular kinematic analyses, including > 1 joint, for disease and treatment monitoring in PD. Our approach can be extended to further mobility-limiting conditions and other joint combinations. TRIAL REGISTRATION: The study is registered in the German Clinical Trials Register (DRKS00022998, registered on 04 Sep 2020).

A Novel Workflow for Electrophysiology Studies in Patients with Brugada Syndrome.

Brugada Syndrome (BrS) is a primary electrical epicardial disease characterized by ST-segment elevation followed by a negative T-wave in the right precordial leads on the surface electrocardiogram (ECG), also known as the 'type 1' ECG pattern. The risk stratification of asymptomatic individuals with spontaneous type 1 ECG pattern remains challenging. Clinical and electrocardiographic prognostic markers are known. As none of these predictors alone is highly reliable in terms of arrhythmic prognosis, several multi-factor risk scores have been proposed for this purpose. This article presents a new workflow for processing endocardial signals acquired with high-density RV electro-anatomical mapping (HDEAM) from BrS patients. The workflow, which relies solely on Matlab software, calculates various electrical parameters and creates multi-parametric maps of the right ventricle. The workflow, but it has already been employed in several research studies involving patients carried out by our group, showing its potential positive impact in clinical studies. Here, we will provide a technical description of its functionalities, along with the results obtained on a BrS patient who underwent an endocardial HDEAM.

T1 mapping: a non-invasive tool to assess the systemic right ventricle.

Ventricular remodeling leads to fibrotic changes in systemic right ventricles (RV). Native T1 mapping provides a quantitative measure in myocardial tissue characterization. The aim of our study was to correlate native T1 values of the systemic RV to function and volumetric data. Native T1 maps were generated with a single breath hold Modified Look-Locker Inversion-recovery pulse (MOLLI) sequence was acquired in the mid-ventricular short axis. Regions of interest (ROI) were drawn in both ventricular free walls, the interventricular septum (IVS), superior insertion point (SIP) and inferior insertion point (IIP) to obtain native T1 values. T1 values were compared to CMR ventricular volumes and function using Spearman correlation. The median age was 36 years (IQR 27-48 years). There were elevated mean native left ventricular (LV) T1 and IIP T1 values at 1122 ± 171 ms and 1117 ± 96 ms, respectively. RV dysfunction was associated with elevated IIP T1 (p = 0.007). Significant moderate negative correlations were seen between RV T1 and LV ejection fraction (LVEF) (r= -0.63, p = 0.01), between RV: IVS T1 ratio and LVEF (r= -0.68, p = 0.006), between LVEF and SIP: IVS T1 ratios (r= -0.54, p = 0.04), and RVEF and IIP T1 (r= -0.59, p = 0.02). Fibrosis measured by native T1 mapping in the systemic RV is most prominent in the LV wall and septal insertion point and correlates with decreased function. T1 values can be used in non-invasive imaging assessment of the RV, but further studies with larger cohorts are needed to assess ability to risk stratify and guide therapy.

Physics-guided self-supervised learning for retrospective T1 and T2 mapping from conventional weighted brain MRI: Technical developments and initial validation in glioblastoma.

PURPOSE: To develop a self-supervised learning method to retrospectively estimate T1 and T2 values from clinical weighted MRI. METHODS: A self-supervised learning approach was constructed to estimate T1, T2, and proton density maps from conventional T1- and T2-weighted images. MR physics models were employed to regenerate the weighted images from the network outputs, and the network was optimized based on loss calculated between the synthesized and input weighted images, alongside additional constraints based on prior information. The method was evaluated on healthy volunteer data, with conventional mapping as references. The reproducibility was examined on two 3.0T scanners. Performance in tumor characterization was inspected by applying the method to a public glioblastoma dataset. RESULTS: For T1 and T2 estimation from three weighted images (T1 MPRAGE, T1 gradient echo sequences, and T2 turbo spin echo), the deep learning method achieved global voxel-wise error ≤9% in brain parenchyma and regional error ≤12.2% in six types of brain tissues. The regional measurements obtained from two scanners showed mean differences ≤2.4% and correlation coefficients >0.98, demonstrating excellent reproducibility. In the 50 glioblastoma patients, the retrospective quantification results were in line with literature reports from prospective methods, and the T2 values were found to be higher in tumor regions, with sensitivity of 0.90 and specificity of 0.92 in a voxel-wise classification task between normal and abnormal regions. CONCLUSION: The self-supervised learning method is promising for retrospective T1 and T2 quantification from clinical MR images, with the potential to improve the availability of quantitative MRI and facilitate brain tumor characterization.

Additional value of CMR parametric mapping in tissue characterization of common benign pediatric cardiac tumors.

BACKGROUND: Cardiac Magnetic Resonance (CMR) parametric mapping is underexplored in cardiac tumors. OBJECTIVES: To evaluate the contribution of mapping sequences on the characterization of pediatric tumors. METHODS: All pediatric patients referred for cardiac tumors at Bambino Gesù Children's Hospital from June 2017 to November 2023, who underwent CMR with mapping sequences, were included. The diagnosis of tumor type was performed according to signal characteristics on different sequences. Mass parametric mapping for each subtype and interobserver variability was assessed. RESULTS: Sixteen patients were enrolled. The mean age at CMR was 7 ± 5 years. "Traditional" mass-type assessment diagnosed hemangioma (Group A) in 3 patients (19%), fibroma (Group B) in 4 patients (25%), rhabdomyoma (Group C) in 6 patients (37%), and lipoma (Group D) in 3 patients (19%). The ANOVA analysis revealed significant differences in mass native T1 and mass extracellular volume (ECV) values among the four subgroups (p<0.001 for both comparisons). The mean native T1 and ECV values were respectively 1465 ± 158 msec and 54 ± 4% for Group A, 860 ± 118 msec and 93 ± 4% for Group B, 1007 ± 57 msec and 23 ± 5% for Group C, and 215 ± 13 msec and 0 ± 0% for Group D. CONCLUSIONS: Mass mapping analysis is feasible and reproducible in children. ECV values provide the most accurate differentiation. Mass ECV consistently resembles normal myocardium in rhabdomyoma, is extremely high (approaching 100%) in fibroma, equals to zero in lipoma, and matches blood pool ECV (1-Hct) in hemangioma.

Free-breathing three-dimensional simultaneous myocardial T1 and T2 mapping based on multi-parametric SAturation-recovery and Variable-flip-Angle.

BACKGROUND: Quantitative myocardial tissue characterization with T1 and T2 parametric mapping can provide an accurate and complete assessment of tissue abnormalities across a broad range of cardiomyopathies. However, current clinical T1 and T2 mapping tools rely predominantly on two-dimensional (2D) breath-hold sequences. Clinical adoption of three-dimensional (3D) techniques is limited by long scan duration. The aim of this study is to develop and validate a time-efficient 3D free-breathing simultaneous T1 and T2 mapping sequence using multi-parametric SAturation-recovery and Variable-flip-Angle (mSAVA). METHODS: mSAVA acquires four volumes for simultaneous whole-heart T1 and T2 mapping. We validated mSAVA using simulations, phantoms, and in-vivo experiments at 3T in 11 healthy subjects and 11 patients with diverse cardiomyopathies. T1 and T2 values by mSAVA were compared with modified Look-Locker inversion recovery (MOLLI) and gradient and spin echo (GraSE), respectively. The clinical performance of mSAVA was evaluated against late gadolinium enhancement (LGE) imaging in patients. RESULTS: Phantom T1 and T2 by mSAVA showed a strong correlation to reference sequences (R2 = 0.98 and 0.99). In-vivo imaging with an imaging resolution of 1.5 × 1.5 × 8 mm3 could be achieved. Myocardial T1 and T2 of healthy subjects by mSAVA were 1310 ± 46 and 44.6 ± 2.0 ms, respectively, with T1 standard deviation higher than MOLLI (105 ± 12 vs 60 ± 16 ms) and T2 standard deviation lower than GraSE (4.5 ± 0.8 vs 5.5 ± 1.0 ms). mSAVA T1 and T2 maps presented consistent findings in patients undergoing LGE. Myocardial T1 and T2 of all patients by mSAVA were 1421 ± 79 and 47.2 ± 3.3 ms, respectively. CONCLUSION: mSAVA is a fast 3D technique promising for clinical whole-heart T1 and T2 mapping.