MRI T2 Mapping Research Articles

Evaluating Synergistic Effects of Hyaluronic Acid, Human Umbilical Cord-Derived Mesenchymal Stem Cells, and Growth Hormones in Knee Osteoarthritis: A Multi-Arm Randomized Trial.

Knee osteoarthritis (OA) significantly affects quality of life and imposes economic burdens due to its prevalence and the disability it causes. The efficacy of current treatments is limited to alleviating the symptoms, and they cannot be used for regenerative purposes. This study aims to evaluate the efficacy and safety of combining hyaluronic acid (HA), human umbilical cord-derived mesenchymal stem cells (hUC-MSCs), and synthetic human growth hormone (somatotropin) in the treatment of knee OA, assessing pain relief, functional improvement, and cartilage regeneration. A four-arm, double-blind randomized trial was conducted with 51 knees from 28 subjects aged ≥50 with primary knee OA. The treatments involved were HA alone, HA with hUC-MSCs, HA with somatotropin, and a combination of all three. Efficacy was measured through the International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and visual analog score (VAS), and MRI T2 mapping of cartilage was conducted on pre-implantation at the 6th and 12th month. All treatment arms showed improvements in the VAS and WOMAC scores over 12 months, suggesting some pain relief and functional improvement. However, MRI T2 mapping showed no significant cartilage regeneration across the groups. While the combined use of HA, hUC-MSCs, and somatotropin improved symptoms of knee OA, it did not enhance cartilage regeneration significantly. This study highlights the potential of these combinations for symptom management but underscores the need for further research to optimize these therapies for regenerative outcomes.

Incremental Prognostic Value of Cardiac MRI Feature Tracking and T1 Mapping in Arrhythmogenic Right Ventricular Cardiomyopathy.

Purpose To explore the role of cardiac MRI feature tracking (FT) and T1 mapping in predicting sustained ventricular arrhythmias (VA) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and to investigate their possible incremental value beyond ARVC risk score. Materials and Methods The retrospective study analyzed 91 patients with ARVC (median age, 36 years [IQR, 27-50 years]; 60 male, 31 female) who underwent cardiac MRI examinations between November 2010 and March 2022. The primary end point was the first occurrence of sustained VA after cardiac MRI to first VA, with censoring of patients who were alive without VA at last follow-up. Cox regression analysis was performed to assess the association between variables and time to sustained VA. Time-dependent receiver operating characteristic (ROC) analysis was performed to determine the incremental value of cardiac MRI FT and T1 mapping. Results During a median follow-up of 55.0 months (IQR, 37.0-76.0 months), 36 of 91 (40%) patients experienced sustained VA. A 1% worsening in left ventricular global longitudinal peak strain (GLS), 1% worsening in right ventricular GLS, and a 1% increase in extracellular volume fraction (ECV) were associated with increased risk of sustained VA, with hazard ratios of 1.14 (95% CI: 1.06, 1.23; P = .001), 1.09 (95% CI: 1.02, 1.16; P = .02), and 1.13 (95% CI: 1.08, 1.18; P < .001), respectively, after adjustment for ARVC risk score. Adding both biventricular GLS and ECV to ARVC risk score showed significant incremental value for predicting sustained VA (area under the ROC curve: 0.73 vs 0.65; P < .001). Conclusion Cardiac MRI-derived biventricular GLS and ECV provided independent and incremental value for predicting sustained VA beyond ARVC risk score alone in patients with ARVC. Keywords: Cardiovascular MRI, Feature Tracking, T1 Mapping, Arrhythmogenic Right Ventricular Cardiomyopathy, Sustained Ventricular Arrhythmias Supplemental material is available for this article Published under a CC BY 4.0 license.

MRI quantitative T1 and T2 mapping of the renal cortex: Assessment of normal values and potential usefulness for renal masses at 3 T

PurposeThe purpose of this monocentric retrospective study consisted in exploring the potential improvement of the assessment of renal masses on MRI by using the T1 (T1m) and T2 (T2m) mapping relaxation times. Materials and MethodsWe recorded the renal cortex values of 125 patients with normal kidneys (reference group) and 75 patients with renal masses on a clinical 3 T MR unit using T1m and T2m sequences.For the quantitative evaluation, measurements were performed by delineating ROIs on T1m and T2m sequences in renal cortex of the reference group and in renal masses.Interobserver agreement for the qualitative analysis of image quality was assessed using quadratic Cohen’s weighted kappa statistics (k).Student’s paired t-test and non-parametric Kruskal-Wallis test were used to compare our datasets in terms of T1m and T2m values. ResultsFor the cohort of reference group, mean renal cortex T1m and T2m values were 1,529 ± 83 ms and 98 ± 7 ms, respectively. No statistically significant differences were found for T1m and T2m in the reference group regardless of age, gender or eGRF categories.For the group with renal masses, mean T1m and T2m values were 1,667 ± 87 ms and 105 ± 8 ms; 1,621 ± 96 ms and 117 ± 6 ms, and 1,530 ± 62 ms and 85 ± 4 ms for renal cell carcinomas, angiomyolipomas, and oncocytomas, respectively. For T1m values, there was no significant difference (p = 0.37) among the three types of renal masses. Among histological subtypes we have found: RCC versus angiomyolipoma (p = 0.25), RCC versus oncocytoma (p = 0.15), and oncocytoma versus angiomyolipoma (p = 0.47).However, we have found a statistically significant difference for the T2m value (p = 0.0005). Among histological subtypes, only T2m values were statistically significant for each combination: RCC versus angiomyolipoma (p = 0.012), RCC versus oncocytoma (p = 0.0002), and oncocytoma versus angiomyolipoma (p = 0.003). ConclusionAs this is the largest normal patient cohort, the T1m and T2m values recorded could be proposed as reference values and can play a role in the differential diagnosis between benign and malignant renal tumoral masses.

Changes in inflammatory edema and fat fraction of thigh muscles following a half-marathon in recreational marathon runners.

It is known that microtrauma exists in the thigh muscles after long-distance running such as the half-marathon. Moreover, training characteristics of long-distance runners may influence the specificity of the distribution of muscle fiber types in the thigh and affect muscle responses to lipid metabolism. However, the specific changes in microtrauma and intramuscular lipid in thigh muscles after a half-marathon are unknown. A cohort of 20 healthy recreational marathon runners was recruited to complete a half-marathon. MRI T2 mapping and 6-echo q-Dixon sequences were employed at baseline (P1), 2-3h after running (P2), and 1day after running (P3). Inflammatory markers (the T2 values) and intramuscular fat fraction (the proton density fat fraction, PDFF) were measured in thigh muscles to detect microtrauma and intramuscular lipid changes, respectively. One-way analysis of variance showed significant time effects for T2 values and PDFF. Post hoc analysis of the 14 datasets collected at three time points revealed significantly higher T2 values in all thigh muscles after running (all p<0.05). Significant differences in T2 values persisted for all thigh muscles at P3 compared to P1 (all p<0.05). The PDFF of the vastus lateralis and vastus medialis was significantly decreased at P2 compared to P1 (p<0.05). No significant differences in PDFF were observed for the thigh muscles at P3 compared to P1. The manifestations of inflammation edema and intramuscular lipid investigated through MRI may offer valuable insights for recreational marathon runners regarding the lower limb movement characteristics during half-marathon running.

Focused Ultrasound Impels the Delivery and Penetration of Model Therapeutics into Cerebral Cavernous Malformations.

Cerebral cavernous malformations (CCMs) are vascular neoplasms in the brain that can cause debilitating symptoms. Current treatments pose significant risks to some patients, motivating the development of new nonsurgical options. We recently discovered that focused ultrasound-mediated blood-brain barrier opening (FUS) arrests CCM formation and growth. Here, we build on this discovery and assess the ability of FUS to deliver model therapeutics into CCMs. Quantitative T1 mapping MRI sequences were used with 1 kDa (MultiHance; MH) and 17 kDa (GadoSpin D; GDS) contrast agents to assess the FUS-mediated delivery and penetration of model small molecule drugs and biologics, respectively, into CCMs of Krit1 mutant mice. FUS elevated the rate of MH delivery to both the lesion core (4.6-fold) and perilesional space (6.7-fold). Total MH delivery more than doubled in the lesion core and tripled in the perilesional space when FUS was applied immediately prior to MH injection. For the model biologic drug (i.e. GDS), FUS was of greater relative benefit, resulting in 21.7-fold and 3.8-fold delivery increases to the intralesional and perilesional spaces, respectively. FUS is capable of impelling the delivery and penetration of therapeutics into the complex and disorganized CCM microenvironment. Benefits to small molecule drug delivery are more evident in the perilesional space, while benefits to biologic delivery are more evident in CCM cores. These findings, when combined with ability of FUS alone to control CCMs, highlight the potential of FUS to serve as a powerful non-invasive therapeutic platform for CCM.

Development and performance evaluation of fully automated deep learning-based models for myocardial segmentation on T1 mapping MRI data

To develop a deep learning-based model capable of segmenting the left ventricular (LV) myocardium on native T1 maps from cardiac MRI in both long-axis and short-axis orientations. Models were trained on native myocardial T1 maps from 50 healthy volunteers and 75 patients using manual segmentation as the reference standard. Based on a U-Net architecture, we systematically optimized the model design using two different training metrics (Sørensen-Dice coefficient = DSC and Intersection-over-Union = IOU), two different activation functions (ReLU and LeakyReLU) and various numbers of training epochs. Training with DSC metric and a ReLU activation function over 35 epochs achieved the highest overall performance (mean error in T1 10.6 ± 17.9 ms, mean DSC 0.88 ± 0.07). Limits of agreement between model results and ground truth were from -35.5 to + 36.1 ms. This was superior to the agreement between two human raters (-34.7 to + 59.1 ms). Segmentation was as accurate for long-axis views (mean error T1: 6.77 ± 8.3 ms, mean DSC: 0.89 ± 0.03) as for short-axis images (mean error ΔT1: 11.6 ± 19.7 ms, mean DSC: 0.88 ± 0.08). Fully automated segmentation and quantitative analysis of native myocardial T1 maps is possible in both long-axis and short-axis orientations with very high accuracy.

The New Frontiers of Fetal Imaging: MRI Insights into Cardiovascular and Thoracic Structures.

Fetal magnetic resonance imaging (fMRI) represents a second-line imaging modality that provides multiparametric and multiplanar views that are crucial for confirming diagnoses, detecting associated pathologies, and resolving inconclusive ultrasound findings. The introduction of high-field magnets and new imaging sequences has expanded MRI's role in pregnancy management. Recent innovations in ECG-gating techniques have revolutionized the prenatal evaluation of congenital heart disease by synchronizing imaging with the fetal heartbeat, thus addressing traditional challenges in cardiac imaging. Fetal cardiac MRI (fCMR) is particularly valuable for assessing congenital heart diseases, especially when ultrasound is limited by poor imaging conditions. fCMR allows for detailed anatomical and functional evaluation of the heart and great vessels and is also useful for diagnosing additional anomalies and analyzing blood flow patterns, which can aid in understanding abnormal fetal brain growth and placental perfusion. This review emphasizes fMRI's potential in evaluating cardiac and thoracic structures, including various gating techniques like metric optimized gating, self-gating, and Doppler ultrasound gating. The review also covers the use of static and cine images for structural and functional assessments and discusses advanced techniques like 4D-flow MRI and T1 or T2 mapping for comprehensive flow quantification and tissue characterization.

High-resolution and highly accelerated MRI T2 mapping as a tool to characterise renal tumour subtypes and grades

BackgroundClinical imaging tools to probe aggressiveness of renal masses are lacking, and T2-weighted imaging as an integral part of magnetic resonance imaging protocol only provides qualitative information. We developed high-resolution and accelerated T2 mapping methods based on echo merging and using k-t undersampling and reduced flip angles (TEMPURA) and tested their potential to quantify differences between renal tumour subtypes and grades.MethodsTwenty-four patients with treatment-naïve renal tumours were imaged: seven renal oncocytomas (RO); one eosinophilic/oncocytic renal cell carcinoma; two chromophobe RCCs (chRCC); three papillary RCCs (pRCC); and twelve clear cell RCCs (ccRCC). Median, kurtosis, and skewness of T2 were quantified in tumours and in the normal-adjacent kidney cortex and were compared across renal tumour subtypes and between ccRCC grades.ResultsHigh-resolution TEMPURA depicted the tumour structure at improved resolution compared to conventional T2-weighted imaging. The lowest median T2 values were present in pRCC (high-resolution, 51 ms; accelerated, 45 ms), which was significantly lower than RO (high-resolution; accelerated, p = 0.012) and ccRCC (high-resolution, p = 0.019; accelerated, p = 0.008). ROs showed the lowest kurtosis (high-resolution, 3.4; accelerated, 4.0), suggestive of low intratumoural heterogeneity. Lower T2 values were observed in higher compared to lower grade ccRCCs (grades 2, 3 and 4 on high-resolution, 209 ms, 151 ms, and 106 ms; on accelerated, 172 ms, 160 ms, and 102 ms, respectively), with accelerated TEMPURA showing statistical significance in comparison (p = 0.037).ConclusionsBoth high-resolution and accelerated TEMPURA showed marked potential to quantify differences across renal tumour subtypes and between ccRCC grades.Trial registrationClinicalTrials.gov, NCT03741426. Registered on 13 November 2018.Relevance statementThe newly developed T2 mapping methods have improved resolution, shorter acquisition times, and promising quantifiable readouts to characterise incidental renal masses.Graphical

The Combination of Gd-EOB-DTPA Enhanced T1 Mapping with Apparent Diffusion Coefficient could Improve the Diagnostic Efficacy of Hepatocellular Carcinoma Grading.

Accurately predicting the hepatocellular carcinoma (HCC) grade may facilitate the rational selection of treatment strategies. The diagnostic efficacy of the combination of Gadolinium ethoxybenzy diethylenetriamine pentaacetic (Gd-EOB-DTPA) enhancement T1 mapping and apparent diffusion coefficient (ADC) values in predicting HCC grade needs further validation. This study aimed to assess the capacity of Gd-EOB-DTPA-enhanced T1 mapping and ADC values, both individually and in combination, to discriminate between different grades of HCC. From July 2017 to February 2020, 96 patients (male, 83; mean age, 53.67 years; age range, 29-71 years) clinically diagnosed with HCC were included in the present study. All patients underwent Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI, including T1 mapping sequence) before surgery or biopsy. All the patients were categorized into 3 groups according to the pathological results (including 24 cases of well-differentiated HCCs, 59 cases of moderately differentiated HCCs, 13 cases of and poorly differentiated HCCs). The mean Gd-EOB-DTPA enhanced T1 values (&#916;T1=[(T1pre-T1post)/T1pre]×100%) and ADC values between different grading groups of HCC were calculated and compared. The area under the characteristics curve (AUC), the diagnostic threshold, sensitivity, and specificity of &#916;T1 and ADC for differential diagnosis were analyzed. Mean &#916;T1 was 58% for well-differentiated HCCs, 50% for moderately-differentiated HCCs, and 43% for poorly-differentiated HCCs. &#916;T1 showed statistical differences between the groups (P<0.001). The mean ADC values of the 3 groups were 1.11×10-3 mm2/s, 0.91×10-3 mm2/s, and 0.80×10-3mm2/s, respectively. ADC showed statistical differences between the groups (P<0.001). In discriminating well- differentiated group from the moderately differentiated group, the AUC of &#916;T1 was 0.751 (95% CI: 0.642, 0.859), the AUC of ADC was 0.782 (95% CI: 0.671, 0.894), the AUC of combined model was 0.811 (95% CI: 0.709, 0.914). In discriminating the poorly differentiated group from the moderately differentiated group, the AUC of &#916;T1 was 0.768 (95% CI: 0.634, 0.902), the AUC of ADC was 0.754 (95% CI: 0.603, 0.904), and the AUC of the combined model was 0.841 (95% CI: 0.729, 0.953). Gd-EOB-DTPA enhanced T1 mapping, and ADC values have complementary effects on the sensitivity and specificity for identifying different HCC grades. A combined model of Gd-EOB-DTPA-enhanced MRI T1 mapping and ADC values could improve diagnostic performance for predicting HCC grades.</p>.

Muscle texture features on preoperative MRI for diagnosis and assessment of severity of congenital muscular torticollis

ObjectivesTo develop an objective method based on texture analysis on MRI for diagnosis of congenital muscular torticollis (CMT).Material and methodsThe T1- and T2-weighted imaging, Q-dixon, and T1-mapping MRI data of 38 children with CMT were retrospectively analyzed. The region of interest (ROI) was manually drawn at the level of the largest cross-sectional area of the SCM on the affected side. MaZda software was used to obtain the texture features of the T2WI sequences of the ROI in healthy and affected SCM. A radiomics diagnostic model based on muscle texture features was constructed using logistic regression analysis. Fatty infiltration grade was calculated by hematoxylin and eosin staining, and fibrosis ratio by Masson staining. Correlation between the MRI parameters and pathological indicators was analyzed.ResultsThere was positive correlation between fatty infiltration grade and mean value, standard deviation, and maximum value of the Q-dixon sequence of the affected SCM (correlation coefficients, 0.65, 0.59, and 0.58, respectively, P < 0.05).Three muscle texture features—S(2,2)SumAverg, S(3,3)SumVarnc, and T2WI extreme difference—were selected to construct the diagnostic model. The model showed significant diagnostic value for CMT (P < 0.05). The area under the curve of the multivariate conditional logistic regression model was 0.828 (95% confidence interval 0.735–0.922); the sensitivity was 0.684 and the specificity 0.868.ConclusionThe radiomics diagnostic model constructed using T2WI muscle texture features and MRI signal values appears to have good diagnostic efficiency. Q-dixon sequence can reflect the fatty infiltration grade of CMT.

Cardiac MRI T2 mapping with heart phase acquisition and improved motion-sensitized driven equilibrium blood suppression

Abstract Background Cardiovascular magnetic resonance (CMR) imaging relies on T2 mapping to assess myocardial tissue properties. However, T2 maps are subject to motion artifacts and signal interference, prompting exploration of techniques such as gradient-spin-echo (GraSE) sequences, heart phase acquisition, and dark blood (DB) imaging to improve image quality and reliability. Purpose This prospective study evaluates the T2 relaxation time (T2) variability and the image quality of T2 maps obtained in end-systole and end-diastole with and without fat saturation (FS), using GraSE sequence in CMR imaging. Furthermore, improved motion-sensitized driven-equilibrium (iMSDE) was compared with double inversion recovery (DIR) as an alternative DB technique. Materials and Methods Five variants of the DB GraSE sequence were developed and performed on a 1.5 Tesla MRI scanner. Forty-four healthy volunteers prospectively underwent the following sequences: GraSE in end-diastole (GraSE-ED), GraSE-ED with FS (GraSE-ED-FS), GraSE in end-systole (GraSE-ES), GraSE-ES with FS (GraSE-ES-FS), and commercial GraSE-ED (GraSE-CO). Four GraSE variants utilized iMSDE technique, while GraSE-CO used DIR for blood suppression. T2, image quality, and visual artifacts were measured. Results Ten volunteers were excluded due to image artifacts or missing datasets. Among the remaining 34 participants, the mean global T2 was measured. No significant differences were seen among all variants (P &amp;gt; .05 for all comparisons). Intra- and inter-reader agreement of global T2 values for all GraSE sequence were very good (r &amp;gt; 0.8 for both). Image quality was rated moderate or good for all variants of GraSE sequences. A lower incidence of artifacts was observed in end-systolic compared to end-diastolic imaging. Conclusion All variants of GraSE sequence are highly reproducible and myocardial T2 values did not significantly differ with heart phase. iMSDE is feasible as an alternative DB technique for T2 mapping enabling acquisition in systole, which shows a lower incidence of artifacts compared to diastole.

Diagnostic performance of unenhanced electrocardiogram-gated cardiac CT for detecting myocardial edema.

To assess the diagnostic performance of unenhanced electrocardiogram (ECG)-gated cardiac computed tomography (CT) for detecting myocardial edema, using MRI T2 mapping as the reference standard. This retrospective study protocol was approved by our institutional review board, which waived the requirement for written informed consent. Between December 2017 to February 2019, consecutive patients who had undergone T2 mapping for myocardial tissue characterization were identified. We excluded patients who did not undergo unenhanced ECG-gated cardiac CT within 3 months from MRI T2 mapping or who had poor CT image quality. All patients underwent unenhanced ECG-gated cardiac CT with an axial scan using a third-generation, 320 × 0.5 mm detector-row CT unit. Two radiologists together drew regions of interest (ROIs) in the interventricular septum on the unenhanced ECG-gated cardiac CT images. Using T2 mapping as the reference standard, the diagnostic performance of unenhanced cardiac CT for detecting myocardial edema was evaluated by using the area under the receiver operating characteristic curve with sensitivity and specificity. Youden index was used to find an optimal sensitivity-specificity cutoff point. A cardiovascular radiologist independently performed the measurements, and interobserver reliability was assessed using intraclass correlation coefficients for CT value measurements. A P value of <.05 was considered statistically significant. We included 257 patients who had undergone MRI T2 mapping. Of the 257 patients, 35 patients underwent unenhanced ECG-gated cardiac CT. One patient was excluded from the study because of poor CT image quality. Finally, 34 patients (23 men; age 64.7 ± 14.6 years) comprised our study group. Using T2 mapping, we identified myocardial edema in 19 patients. Mean CT and T2 values for 34 patients were 46.3 ± 2.7 Hounsfield unit and 49.0 ± 4.9 ms, respectively. Mean CT values moderately correlated with mean T2 values (Rho = -0.41; P < .05). Mean CT values provided a sensitivity of 63.2% and a specificity of 93.3% for detecting myocardial edema, with a cutoff value of ≤45.0 Hounsfield unit (area under the receiver operating characteristic curve = 0.77; P < .01). Inter-observer reproducibility in measuring mean CT values was excellent (intraclass correlation coefficient = 0.93; [95% confidence interval: 0.86, 0.96]). Myocardial edema could be detected by CT value of myocardium in unenhanced ECG-gated cardiac CT.

Cardiac MRI for clinical dilated cardiomyopathy: Improved diagnostic power via combined T1, T2, and ECV

IntroductionEarly diagnosis of patients with dilated cardiomyopathy (DCM) remains challenging. Cardiac MR can correlate myocardial changes with their pathological basis. There have been some previous studies on the effect of T1 mapping in DCM, but there is limited data on the incremental value of T2 mapping for DCM in routine clinical practice. This study will examine whether the combination of MRI T1 and T2 mapping offers greater advantages in the diagnosis of DCM. MethodsThe study included 28 patients with DCM and 21 healthy controls. CMR evaluation included late gadolinium enhancement (LGE), T1 mapping, extracellular volume (ECV) fraction and T2 mapping. The DCM group was divided into LGE (+) and LGE (−) subgroups. The main modes of LGE are subendocardial, midwall, subepicardial, or transmural. T1 values, T2 values, and ECV in the 16 segments myocardial levels were measured by post-processing software. Student's t-tests or Mann–Whitney U test was used to compare between two groups, and one-way ANOVA or Kruskal–Wallis H test was used to compare between multiple groups, with p values corrected by Bonferroni. The difference was considered statistically significant at P < 0.05. ROC curve analysis was used to compare the area under the curve (AUC) of each index and its combined value, and the cut-off value, sensitivity and specificity were determined by Jordan's index. ResultsMean native myocardial T1, ECV and T2 were significantly higher in the DCM group compared to controls (p ≤ 0.001, respectively). The best cut-off values for T1, T2 and ECV to discriminate DCM from controls were 1184 ms, 40.9 ms and 29.2%, respectively. The AUC of T1, ECV and T2 were 0.87, 0.89, and 0.83, respectively. The combined AUC of the three values was 0.96. ConclusionNative T1 value and ECV overcome some of the limitations of LGE, and the T2 helps to understand the extent of myocardial damage. The combination of T1 and T2 mapping techniques can reveal fibrotic and oedematous changes in the early stages of DCM, providing a more comprehensive assessment of DCM and better guidance for individualised clinical management of patients. Implications for practiceWe suggest that the addition of T2 mapping to the routine CMR examination of patients with suspected DCM, and the combined assessment of T1mapping and T2 mapping can provide complementary information about the disease and improve the early diagnosis of DCM.

Fast T1 mapping MRI in preclinical and clinical settings using subspace-constrained joint-domain reconstructions

This work aims to develop fast T1 mapping methods for preclinical and clinical scanners based on subspace-constrained reconstructions. Two sequences are explored for rapid T1 characterizations: 1) Interleaved spatiotemporal encoding incorporating variable repetition times. 2) Inversion recovery gradient echo with random sampling of the phase-encoding (PE) dimension. For both sequences, the subspace reconstruction of the signal recovery was applied, to jointly reconstruct the down-sampled images while characterizing the T1 relaxation. In vivo scans on human brains and abdomens confirmed the efficiency of the proposed methods, including compatibility with breath-holding. In addition, Scans on animals with abdominal tumors and dynamic contrast-enhanced T1 mapping on kidneys support the applicability of the proposed methods also in preclinical settings.

MRI T2 mapping and shear wave elastography for identifying main pain generator in delayed-onset muscle soreness: muscle or fascia?

IntroductionThe main generator of delayed onset muscle soreness (DOMS) is still unknown. This study aimed to clarify the main generator of DOMS.MethodsTwelve participants performed eccentric exercise (EE) on lower legs. MRI and ultrasound were used to assess changes of calf muscle and deep fascia before and after EE. These results were then compared to the muscle pain level.ResultsCompared to baseline, muscle pain peaked at 24–48 h after EE (downstairs 22.25 ± 6.196, 57.917 ± 9.298, F = 291.168, p < 0.01; resting 5.833 ± 1.899, 5.083 ± 2.429, F = 51.678, p < 0.01). Shear wave speed (SWE) of the deep fascia and T2 values of the gastrocnemius muscle and deep fascia all increased and peaked at 48 h after EE (1.960 ± 0.130, F = 22.293; 50.237 ± 2.963, F = 73.172; 66.328 ± 2.968, F = 231.719, respectively, p < 0.01). These measurements were positively correlated with DOMS (downstairs: r = 0.46, 0.76, 0.87, respectively, p < 0.001; resting: r = 0.42, 0.70, 0.77, respectively, p < 0.001). There was a significant positive correlation between SWE and T2 values of deep fascia (r = 0.54, p < 0.01).ConclusionDOMS is a common result of muscle and fascia injuries. Deep fascia edema and stiffness play a crucial role in DOMS, which can be effectively evaluated MR-T2 and SWE.Critical relevance statementDelayed-onset muscle soreness is a common result of muscle and deep fascia injuries, in which the edema and stiffness of the deep fascia play a crucial role. Both MRI and shear wave elastography can be effectively used to evaluate soft tissue injuries.Key points• The deep fascia is the major pain generator of delayed-onset muscle soreness.• There is a significant correlation between fascia injury and delayed-onset muscle soreness.• MRI and shear wave elastography are preferred methods for assessing fascia injuries.Graphical

Automated assessment of cardiac pathologies on cardiac MRI using T1-mapping and late gadolinium phase sensitive inversion recovery sequences with deep learning

BackgroundA deep learning (DL) model that automatically detects cardiac pathologies on cardiac MRI may help streamline the diagnostic workflow. To develop a DL model to detect cardiac pathologies on cardiac MRI T1-mapping and late gadolinium phase sensitive inversion recovery (PSIR) sequences were used.MethodsSubjects in this study were either diagnosed with cardiac pathology (n = 137) including acute and chronic myocardial infarction, myocarditis, dilated cardiomyopathy, and hypertrophic cardiomyopathy or classified as normal (n = 63). Cardiac MR imaging included T1-mapping and PSIR sequences. Subjects were split 65/15/20% for training, validation, and hold-out testing. The DL models were based on an ImageNet pretrained DenseNet-161 and implemented using PyTorch and fastai. Data augmentation with random rotation and mixup was applied. Categorical cross entropy was used as the loss function with a cyclic learning rate (1e-3). DL models for both sequences were developed separately using similar training parameters. The final model was chosen based on its performance on the validation set. Gradient-weighted class activation maps (Grad-CAMs) visualized the decision-making process of the DL model.ResultsThe DL model achieved a sensitivity, specificity, and accuracy of 100%, 38%, and 88% on PSIR images and 78%, 54%, and 70% on T1-mapping images. Grad-CAMs demonstrated that the DL model focused its attention on myocardium and cardiac pathology when evaluating MR images.ConclusionsThe developed DL models were able to reliably detect cardiac pathologies on cardiac MR images. The diagnostic performance of T1 mapping alone is particularly of note since it does not require a contrast agent and can be acquired quickly.

Retrospectively gated ultrashort-echo-time MRI T1 mapping reveals compromised pulmonary microvascular NO-dependent function in a murine model of acute lung injury.

This study sought to develop noninvasive, in vivo imaging schemes that allow for quantitative assessment of pulmonary microvascular functional status based on the combination of pulmonary T1 mapping and dynamic contrast-enhanced (DynCE) imaging. Ultrashort-echo-time (UTE) imaging at 9.4 T of lung parenchyma was performed. Retrospective gating was based on modulation of the first point in each recorded spoke. T1 maps were obtained using a series of five consecutive images with varying RF angles and analyzed with the variable flip angle approach. The obtained mean T1 lung value of 1078 ± 38 ms correlated well with previous reports. Improved intersession variability was observed, as evident from a decreased standard deviation of motion-resolved T1 mapping (F-test = 0.051). Animals received lipopolysaccharide (LPS) and were imaged at t= 2, 6, and 12 h after administration. The nitric oxide (NO)-dependent function was assessed according to changes in lung T1 after L-NAME injection, while microvascular perfusion and oxidant stress were assessed with contrast-enhanced imaging after injection of gadolinium or 3-carbamoyl-proxyl nitroxide radical, respectively. Retrospectivel gated UTE allowed robust, motion-compensated imaging that could be used for T1 mapping of lung parenchyma. Changes in lung T1 after L-NAME injection indicated that LPS induced overproduction of NO at t= 2 and 6 h after LPS, but NO-dependent microvascular function was impaired at t= 12 h after LPS. DynCE imaging at t= 6 h after LPS injection revealed decreased microvascular perfusion, with increased vascular permeability and oxidant stress. MRI allows to visualize and quantify lung microvascular NO-dependent function and its concomitant impairment during acute respiratory distress syndrome development with high sensitivity. UTE T1 mapping appears to be sensitive and useful in probing pulmonary microvascular functional status.

T1 mapping combined with arterial spin labeling MRI to identify renal injury in patients with liver cirrhosis.

We investigated the capability and imaging criteria of T1 mapping and arterial spin labeling (ASL) MRI to identify renal injury in patients with liver cirrhosis. We recruited 27 patients with cirrhosis and normal renal function (cirrhosis-NR), 10 with cirrhosis and renal dysfunction (cirrhosis-RD) and 23 normal controls (NCs). All participants were examined via renal T1 mapping and ASL imaging. Renal blood flow (RBF) derived from ASL was measured from the renal cortex, and T1 values were measured from the renal parenchyma (cortex and medulla). MRI parameters were compared between groups. Diagnostic performances for detecting renal impairment were statistically analyzed. Cortical T1 (cT1) and medullary T1 (mT1) were significantly lower in the NCs than in the cirrhosis-NR group. The cortical RBF showed no significant changes between the NCs and cirrhosis-NR group but was markedly decreased in the cirrhosis-RD group. The areas under the curve (AUCs) for discriminating cirrhosis-NR from NCs were 0.883 and 0.826 by cT1 and mT1, respectively. Cortical RBF identified cirrhosis-RD with AUC of 0.978, and correlated with serum creatinine (r = -0.334) and the estimated glomerular filtration rate (r = 0.483). A classification and regression tree based on cortical RBF and cT1 achieved 85% accuracy in detecting renal impairment in the cirrhosis. Renal T1 values might be sensitive predictors of early renal impairment in patients with cirrhosis-NR. RBF enabled quantifying renal perfusion impairment in patients with cirrhosis-RD. The diagnostic algorithm based on cortical RBF and T1 values allowed detecting renal injury during cirrhosis.

MRI T2 mapping assessment of T2 relaxation time in desmoid tumors as a quantitative imaging biomarker of tumor response: preliminary results.

Because size-based imaging criteria poorly capture biologic response in desmoid-type fibromatosis (DF), changes in MRI T2 signal intensity are frequently used as a response surrogate, but remain qualitative. We hypothesized that absolute quantification of DF T2 relaxation time derived from parametric T2 maps would be a feasible and effective imaging biomarker of disease activity. This IRB-approved retrospective study included 11 patients with DF, managed by observation or systemic therapy, assessed by 3T MRI. Tumor maximum diameter, volume, and T2-weighted signal intensity were derived from manual tumor segmentations. Tumor:muscle T2 signal ratios were recorded. Two readers measured tumor T2 relaxation times using a commercial T2 scanning sequence, manual ROI delineation and commercial calculation software enabling estimation of reader reliability. Objective response rates based on RECIST1.1 and best responses were compared between size-based and signal-based parameters. Median patient age was 52.6 years; 8 subjects were female (73%). Nine patients with longitudinal assessments were followed for an average of 314 days. Median baseline tumor diameter was 7.2 cm (range 4.4 - 18.2 cm). Median baseline T2 was 65.1 ms (range 40.4 - 94.8 ms, n=11); median at last follow-up was 44.3 ms (-32% from baseline; range 29.3 - 94.7 ms, n=9). T2 relaxation times correlated with tumor:muscle T2 signal ratios, Spearman p=0.78 (p<0.001). T2 mapping showed high inter-reader reliability, ICC=0.84. The best response as a percentage change in T2 values was statistically significant (mean -17.9%, p=0.05, paired t-test) while change in diameter was not (mean -8.9%, p=0.12). Analysis of T2 relaxation time maps of DF may offer a feasible quantitative biomarker for assessing the extent of response to treatment. This approach may have high inter-reader reliability.

MRI T2 mapping and quantitative ultrasound shear wave elastography in cartilage integrity assessment for juvenile idiopathic arthritis patients

BackgroundJuvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood that can lead to irreversible cartilage damage, with associated disability and decreased life quality. Shear wave elastography and quantitative MRI mapping can be used to identify early cartilage affection. PurposeTo evaluate diagnostic utility of distal femoral cartilage shear wave elastography and MRI T2 mapping in patients with symptomatic knee and investigate their potential clinical significance.Material and methodsTwenty patients with knee affection (study group) and 20 volunteers with the same demographic characteristics but without symptomatic knee pain (control group) were included in the study. A total of 80 knee joints of 40 individuals were evaluated. At the medial, intercondylar, and lateral condylar levels, distal femoral cartilage thickness was measured by B-mode ultrasonography and MRI, stiffness was assessed by shear wave elastography, and T2 relaxation time was measured by MRI.ResultsThe medial, intercondylar, and lateral cartilage thickness measurements were similar between the two groups and no statistically significant difference was observed while measured by US (P value 0.653,0.702,0.607) and MRI (P value 0.414, 0.4187, 0.3903). The shear wave velocity values in the study group were significantly higher than in the control group (P value 0.0202). There was a statistically significant difference between the average T2 relaxation time values for the distal femoral cartilage in the study and the control groups (P value 0.0027). SWE results were statistically significant in moderate and high disease activity while T2* revealed statistically significant p values in low as well as moderate and high disease activity; we found the best cutoff values for detection of cases using shear wave elastography velocity ratio (m/sec) about 4.445 with significant p value = 0.02, sensitivity 59.3% and specificity = 70.45%.ConclusionShear wave elastography and MRI T2 mapping are reliable, non-invasive, and acceptable methods for the assessment of pathologic cartilage. Better diagnostic information of hyaline cartilage can be obtained by adding up an extra sequence called T2 mapping to the routine MRI protocol of knee.