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Myocardial T1, T2 and T2* imaging techniques become increasingly used in clinical practice. While normal values for T1, T2 and T2* times are well established for 1.5 Tesla (T) cardiovascular magnetic resonance (CMR), data for 3T remain scarce. Therefore we sought to determine normal reference values relative to gender and age and day to day reproducibility for native T1, T2, T2* mapping and extracellular volume (ECV) at 3T in healthy subjects. After careful exclusion of cardiovascular abnormality, 75 healthy subjects aged 20 to 90 years old (mean 56 ± 19 years, 47% women) underwent left-ventricular T1 (3-(3)-3-(3)-5 MOLLI)), T2 (8 echo- spin echo-imaging) and T2 * (8 echo gradient echo imaging) mapping at 3T CMR (Philips Ingenia 3T and computation of extracellular volume after administration of 0.2 mmol/kg Gadovist). Inter- and intra-observer reproducibility was estimated by intraclass correlation coefficient (ICC). Day to day reproducibility was assessed in 10 other volunteers. Mean myocardial T1 at 3T was 1122 ± 57 ms, T2 52 ± 6 ms, T2* 24 ± 5 ms and ECV 26.6 ± 3.2%. T1 (1139 ± 37 vs 1109 ± 73 ms, p < 0.05) and ECV (28 ± 3 vs 25 ± 2%, p < 0.001), but not T2 (53 ± 8 vs 51 ± 4, p = NS) were significantly greater in age matched women than in men. T1 (r = 0.40, p < 0.001) and ECV (r = 0.37, p = 0.001) increased, while T2 decreased significantly (r = −0.25, p < 0.05) with increasing age. T2* was not influenced by either gender or age. Intra and inter-observer reproducibility was high (ICC ranging between 0.81-0.99), and day to day coefficient of variation was low (6.2% for T1, 7% for T2, 11% for T2* and 11.5% for ECV). We provide normal myocardial T2, T2*,T1 and ECV reference values for 3T CMR which are significantly different from those reported at 1.5 Tesla CMR. Myocardial T1 and ECV values are gender and age dependent. Measurement had high inter and intra-observer reproducibility and good day-to-day reproducibility.

Background: Noninvasive quantitative magnetic resonance imaging (MRI) measures to assess anterior cruciate ligament (ACL) graft maturity are needed to help inform return to high-demand activities and to evaluate the effectiveness of new treatments to accelerate ACL graft maturation. Quantitative MRI ultrashort echo time T2* (UTE-T2*) and T2* mapping captures short T2 signals arising from collagen-associated water in dense regular connective tissues, such as tendon, ligament, and maturing grafts, which are invisible to conventional MRI. Hypothesis: Quantitative MRI UTE-T2* and T2* mapping is sensitive to ACL graft changes over the first 2 years after ACL reconstruction (ACLR). Study Design: Case series; Level of evidence, 4. Methods: A total of 32 patients (18 men; mean ± SD age, 30 ± 9 years) undergoing unilateral ACLR and 30 uninjured age-matched controls (18 men; age, 30 ± 9 years) underwent 3-T MRI examination. Patients who underwent ACLR were imaged at 6 weeks, 6 months, and 1 and 2 years postoperatively. Two separate ACLR cohorts were scanned with 2 MRI platforms at 2 institutions. Twelve ACLR knees were scanned with a 3-dimensional acquisition-weighted stack of spirals UTE sequence on a Siemens scanner, and 20 ACLR knees were scanned with a 3-dimensional Cones UTE sequence on a GE scanner. UTE-T2* or T2* maps were calculated for the intra-articular portion of the ACL graft. Results: Mean ACL graft UTE-T2* and T2* decreased from 1 to 2 years after ACLR. ACL graft T2* increased 25% to 30% during the first 6 months (P < .013) to a level not different from that of uninjured native ACL (P > .4), stabilized between 6 months and 1 year (P ≥ .999), and then decreased 19% between 1 and 2 years after ACLR (P = .027). At 6-month follow-up, ACL graft UTE-T2* differed from that of tendon (P < .02) but not uninjured native ACL (P > .7) and showed the greatest variability among patients. Conclusion: UTE-T2* mapping suggested substantial changes within the graft during the first 6 months postsurgery. T2* and UTE-T2* mapping showed relatively stable graft composition from 6 months to 1 year, consistent with remodeling, followed by decreases from 1 to 2 years, suggestive of continuing maturation. MRI UTE-T2* and T2* mapping demonstrated potential clinical utility as noninvasive quantitative imaging metrics for evaluation of human ACL grafts.

Background Lumbar cartilage endplate (CEP) structures show low signal intensity on conventional magnetic resonance imaging (MRI), making them hard to observe and quantify. This often results in poor correlation between conventional MRI findings and low back pain (LBP) symptoms and provides inadequate guidance for clinical decisions. Methods The study included Twenty-five healthy volunteers and forty-one patients with LBP. Quantitative MRI techniques—Ultrashort Echo Time (UTE) T2* mapping and T2 mapping are employed to evaluate lumbar intervertebral disc degeneration (IVDD) and LBP symptoms. Pfirrmann and Rajasekaran grading systems and the Oswestry Disability Index (ODI) served as reference standards. Regions of interest (ROIs) for the nucleus pulposus (NP), upper CEP, and lower CEP were outlined in UTE Two echo subtracting images and transferred to UTE images fused with 3D water sequence images and T2 mapping images. UTE-T2* and T2 mapping values were automatically calculated. Cohen’s kappa, Spearman’s rank correlation, and Kruskal–Wallis tests were used, with significance set at p  < 0.05. Results Spearman’s rank correlation revealed that UTE‑T2* and T2 values for upper CEP, lower CEP, and NP negatively correlated with Pfirrmann and Rajasekaran grades ( P  < 0.001). The Kruskal–Wallis test showed significant differences in values between Pfirrmann grades II, III, IV, and V ( P  < 0.001). ODI was negatively correlated with T2* and T2 values of the lower CEP ( P  < 0.001) and positively with Pfirrmann grade ( r  = 0.2, P  = 0.003). Conclusion Quantitative MRI methods for T2* values and T2 mapping are associated with grade of degeneration and ODI index and are more effective for assessing CEP damage and LBP symptoms than conventional MRI sequence.

Purpose This study evaluated the regenerated cartilage after opening-wedge high tibial osteotomy (OWHTO) with concomitant microfracture by second-look arthroscopy, Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and magnetic resonance imaging (MRI) T2 mapping. It was hypothesised that cartilage regeneration can be achieved by HTO, but the quality of regenerated cartilage is not normal cartilage. Methods OWHTO was performed in eight knees of seven patients (mean age, 57.6 ± 5.2 years). Microfracture for the cartilage defect was performed followed by OWHTO, and second-look arthroscopy was performed at the time of plate removal (14.1 ± 4.5 months after OWHTO). MRI was assessed at three months and one year after surgery. The status of articular cartilage regeneration was assessed by the ICRS grade, MOCART score and T2 value. Results The number of subjects in ICRS grade 1/2/3/4 changed significantly from 0/0/4/4 preoperatively to 0/2/6/0 postoperatively in the medial femoral condyle (MFC) ( P  < 0.05) and 0/0/0/8 preoperatively to 0/0/7/1 postoperatively in the medial tibial plateau (MTP) ( P  < 0.05). Mean MOCART scores for MFC and MTP at one year after surgery exhibited significant increases compared with the results at three months after surgery. Mean T2 values for MFC and MTP did not differ at three months and one year after surgery. Conclusion The appearance and morphological evaluation by ICRS grade and MOCART score of regenerated cartilage were improved after OWHTO with concomitant microfracture. However, there were no significant qualitative differences in T2 values. This suggests that the regenerated cartilage tissue was likely to be insufficient cartilage. Level of evidence Level IV, therapeutic case series.

Background: The research of primary progressive multiple sclerosis (PPMS) has not been able to capitalize on recent progresses in advanced magnetic resonance imaging (MRI) protocols. Objective: The presented cross-sectional study evaluated the utility of four different MRI relaxation metrics and diffusion-weighted imaging in PPMS. Methods: Conventional free precession T1 and T2, and rotating frame adiabatic T1ρ and T2ρ in combination with diffusion-weighted parameters were acquired in 13 PPMS patients and 13 age- and sex-matched controls. Results: T1ρ, a marker of crucial relevance for PPMS due to its sensitivity to neuronal loss, revealed large-scale changes in mesiotemporal structures, the sensorimotor cortex, and the cingulate, in combination with diffuse alterations in the white matter and cerebellum. T2ρ, particularly sensitive to local tissue background gradients and thus an indicator of iron accumulation, concurred with similar topography of damage, but of lower extent. Moreover, these adiabatic protocols outperformed both conventional T1 and T2 maps and diffusion tensor/kurtosis approaches, methods previously used in the MRI research of PPMS. Conclusion: This study introduces adiabatic T1ρ and T2ρ as elegant markers confirming large-scale cortical gray matter, cerebellar, and white matter alterations in PPMS invisible to other in vivo biomarkers.

Purpose To evaluate the effect of imaging plane and experience of observers on the reliability of T2 mapping of native and repair cartilage tissue of the knee. Methods Fifteen consecutive patients from two randomised controlled trials (RCTs) were included in this cross-sectional study. Patients with an isolated knee cartilage lesion were randomised to receive either debridement or microfracture (RCT 1) or debridement or autologous chondrocyte implantation (RCT 2). T2 mapping was performed in coronal and sagittal planes two years postoperatively. A musculoskeletal radiologist, a resident of radiology and two orthopaedic surgeons measured the T2 values independently. Intraclass Correlation Coefficient (ICC) with 95% Confidence Intervals was used to calculate the inter- and intraobserver agreement. Results Mean age for the patients was 36.8 ± 11 years, 8 (53%) were men. The overall interobserver agreement varied from poor to good with ICCs in the range of 0.27– 0.76 for native cartilage and 0.00 – 0.90 for repair tissue. The lowest agreement was achieved for evaluations of repair cartilage tissue. The estimated ICCs suggested higher inter- and intraobserver agreement for radiologists. On medial femoral condyles, T2 values were higher for native cartilage on coronal images ( p  < 0.001) and for repair tissue on sagittal images ( p  < 0.001). Conclusions The reliability of T2 mapping of articular cartilage is influenced by the imaging plane and the experience of the observers. This influence may be more profound for repair cartilage tissue. This is important to consider when using T2 mapping to measure outcomes after cartilage repair surgery. Trial registration ClinicalTrials.gov, NCT02637505 and NCT02636881 , registered December 2015. Level of evidence II, based on prospective data from two RCTs.

Cardiovascular magnetic resonance (CMR) is considered the gold standard imaging modality for myocardial tissue characterization. Elevated transverse relaxation time (T2) is specific for increased myocardial water content, increased free water, and is used as an index of myocardial edema. The strengths of quantitative T2 mapping lie in the accurate characterization of myocardial edema, and the early detection of reversible myocardial disease without the use of contrast agents or ionizing radiation. Quantitative T2 mapping overcomes the limitations of T2-weighted imaging for reliable assessment of diffuse myocardial edema and can be used to diagnose, stage, and monitor myocardial injury. Strong evidence supports the clinical use of T2 mapping in acute myocardial infarction, myocarditis, heart transplant rejection, and dilated cardiomyopathy. Accumulating data support the utility of T2 mapping for the assessment of other cardiomyopathies, rheumatologic conditions with cardiac involvement, and monitoring for cancer therapy-related cardiac injury. Importantly, elevated T2 relaxation time may be the first sign of myocardial injury in many diseases and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. This comprehensive review discusses the technical considerations and clinical roles of myocardial T2 mapping with an emphasis on expanding the impact of this unique, noninvasive tissue parameter.

The aim of this study was to quantitatively assess supraspinatus tendon pathologies with T2/T2* mapping techniques, which are sensitive to biochemical changes. Conventional magnetic resonance imaging (MRI) and T2/T2* mapping techniques were applied to 41 patients with shoulder pathology, and there were also 20 asymptomatic cases included. The patients were divided into two groups: tendinosis and rupture. The supraspinatus tendon was divided into medial, middle, and lateral sub-regions, and the T2/T2* values were measured in both the coronal and sagittal planes for intergroup comparison. Intra-class and inter-class correlation coefficients (ICCs) were calculated to assess test reproducibility. Receiver operating characteristic (ROC) analysis was used to determine the cut-off value in each group. A total of 61 patients (27 males and 34 females)—including 20 asymptomatic individuals, 20 with tendinosis, and 21 with rupture—were evaluated using T2/T2* mapping techniques. In the rupture group, there were significant differences in the values of the lateral region (p < 0.001), as well as in the middle and medial regions (p < 0.05) of the supraspinatus tendon compared to the tendinosis and asymptomatic groups. These were determined using both T2* and T2 mapping in both the coronal and sagittal plane measurements. In the tendinosis group, there were significant differences in the values of the lateral region with T2* mapping (p < 0.001) in both the coronal and sagittal planes, and also with the T2 mapping in the coronal plane (p < 0.05) compared to the asymptomatic groups. The cut-off values for identifying supraspinatus pathology ranged from 85% to 90% for T2 measurements and above 90% for T2* measurements in both planes of the lateral section. The ICC values showed excellent reliability (ICC > 0.75) for all groups. In conclusion, T2 and T2* mapping techniques with 1.5 T MRI can be used to assess tendon rupture and tendinosis pathologies in the supraspinatus tendon. For an accurate evaluation, measurements from the lateral region in both the coronal and sagittal planes are more decisive.

•Development of a novel T2-prepared stack-of-stars imaging sequence that can achieve whole-brain scan in 70 s for T2 mapping.•Introduction of a signal evolution model to account for incomplete magnetization recovery, enabling efficient data acquisition without compromising mapping accuracy.•Integration of implicit neural representation for direct, unsupervised reconstruction of T2 maps from undersampled k-space data, without requiring fully sampled training datasets.•Reformulation of the T2 mapping problem into a function optimization framework, guided by a physical model and leveraging the flexibility of neural networks for precise parametric quantification. To propose a technique for highly accelerated T2 mapping of the whole brain. A pulse sequence with T2 preparation and a highly undersampled golden-angle stack-of-stars trajectory is used for data acquisition. A multiresolution hash encoding implicit neural representation, embedded with a physical model of signal evolution, is employed for unsupervised reconstruction. By rotating the trajectory at different kz encodings and effective echo times (TEeff) during acquisition, undersampling is applied to three dimensions, i.e., (kx, ky, TEeff) domain. In the phantom experiment, T2 quantification using this T2-prepared stack-of-stars acquisition was compared with that using a Cartesian multi-echo spin-echo acquisition. In the human experiments, T2 quantification using the undersampled acquisition was validated in comparison with those using the fully sampled acquisition and multi-echo spin-echo. In phantom test, T2 quantification using the proposed reconstruction agreed well (slope = 0.999, R2 > 0.99) with that obtained by fitting the NUFFT-reconstructed results for the fully sampled T2-prepared stack-of-stars acquisition. In human experiments, T2 quantification using a 20-fold acceleration agreed well with that using fully sampled data (NRMSE = 0.0066) in retrospectively undersampled reconstruction. No significant difference in T2 values was found between our technique and the reference method in prospective experiments, and our technique showed good inter-scan reproducibility and intra-scan repeatability. Using the proposed technique, whole-brain T2 mapping can be acquired in 70 s with a 20-fold acceleration.

Cardiac magnetic resonance (CMR) imaging is widely used in various medical fields related to cardiovascular diseases. Rapid technological innovations in magnetic resonance imaging in recent times have resulted in the development of new techniques for CMR imaging. T1 and T2 image mapping sequences enable the direct quantification of T1, T2, and extracellular volume fraction (ECV) values of the myocardium, leading to the progressive integration of these sequences into routine CMR settings. Currently, T1, T2, and ECV values are being recognized as not only robust biomarkers for diagnosis of cardiomyopathies, but also predictive factors for treatment monitoring and prognosis. In this study, we have reviewed various T1 and T2 mapping sequence techniques and their clinical applications.