MRI T2 Mapping Research Articles

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.

Changes in Cardiovascular Magnetic Resonanse T1 and T2 Mapping in Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation

Introduction Despite the significant improvement in survival afforded by hematopoietic stem cell transplantation (HSCT), the therapy is associated with many complications, cardiovascular being one of them. Cardiovascular magnetic resonance (CMR) can depict changes at the tissue level, which could be a reflection of physiology and pathophysiology. In our study we aimed to evaluate the level and progress of diffuse myocardial fibrosis and edema in the heart using T1 and T2 mapping in patients one year after autologous HSCT. Methods Data of 26 patients undergoing autologous HSCT at the Department of Oncology and Hematology in the Hospital of Lithuanian University of Health Sciences Kaunas Clinics between 2021 October and 2022 July was evaluated. Bioethics approvement for prospective study was obtained (No BE-2-96). Cardiac evaluation including cardiovascular magnetic resonance (CMR) was performed before stem cell mobilization and 12 ± 1 months after HSCT. CMR was performed using 3T MRI Siemens Magnetom Skyra, T1 and T2 mapping MOLLI (modified Look-Locker Inversion Recovery) sequences with motion correction (MOCO) were analysed using Syngo.via. Baseline mapping values were compered to values one year after transplantation. SPSS statistics 20 was used for statistical analysis (paired samples T test). Qualitative data is presented as absolute value (N) and percentage (%), quantitative parameters are given as average (m ± standard deviation). Results The mean age of patients was 56,7 ± 13,7 years (ranging from 18 to 74). Out of 26 patients there were 14 men (53,8%) and 12 women (46,2%). Mean T1 mapping value representing diffuse fibrosis significantly increased 12 months after transplantation. Mean T1 mapping value before HSCT was 1215,02 ± 35,2 ms and after 1243,07 ± 46,2 ms (p=0,014). Mean T2 mapping value representing edema did not change significantly. Mean T2 mapping value before HSCT was 38,28 ± 2,1 ms and 39,05 ± 1,8 ms after HSCT. (p=0,059). Conclusions The extent of diffuse fibrosis in the heart represented by elevation of T1 mapping value tend to increase one year after autologous HSCT. This may lead to further remodelling of the heart.

Clinical utility of circulating TWEAK and CD163 as biomarkers of iron-induced cardiac decompensation in transfusion dependent thalassemia major

Background and aimTumor necrosis factor-like weak inducer of apoptosis (TWEAK) affects most of the cells involved in cardiac fibrosis like inflammatory cells, cardiomyocytes and fibroblasts. CD163, the receptor of TWEAK on the surface of type 2 macrophages, is shed into plasma upon macrophages activation. This work aimed to evaluate serum TWEAK and its decoy receptor CD163 as probable biomarkers to monitor myocardial iron overload (MIO) in transfusion dependent thalassemia major (TDTM) patients and to predict iron-induced cardiac decompensation (IICD). MethodsA total of 140 TDTM patients were enrolled. Patients were categorized into two groups; group I (n = 70) diagnosed with IICD while group II (n = 70) had no evidence of IICD. sTWEAK and sCD163 were quantitated utilizing Enzyme-linked-immunosorbent- assay. ResultssTWEAK was evidently lower in group I than group II (medians, 412 and 1052 pg/mL respectively). sCD163 was higher in group I than group II (medians, 615.5 and 323.5 ng/mL respectively). sTWEAK positively correlated with cardiac MRI-T2 mapping and ventricular ejection fractions and negatively correlated with B-Natriuretic peptide and cardiac troponin. An inverse relationship between TWEAK and CD163 was documented throughout the study. sTWEAK, sCD163 and TWEAK/CD163 ratio proved to be significant predictors of IICD in TDTM patients. TWEAK/CD163 ratio < 1.04 discriminated IICD in TDTM patients with 100 % clinical sensitivity and specificity. ConclusionCirculating TWEAK and CD163 appears to be promising biomarkers for monitoring MIO and predicting IICD in TDTM patients.

A Systematic Review and Meta-Analysis of Myocardial Fibrosis in CKD and ESKD Assessed by Cardiac MRI T1 Mapping

A Systematic Review and Meta-Analysis of Myocardial Fibrosis in CKD and ESKD Assessed by Cardiac MRI T1 Mapping

Evaluation of finger cartilage composition in recreational climbers with 7Tesla T2 mapping magnetic resonance imaging.

Sport climbing may lead to tissue adaptation including finger cartilage before apparent surface damage is detectable. The main aim was to assess finger cartilage composition with T2 mapping in young, active climbers and to compare the results to a non-climbers' collective. A secondary aim was to compare whether differences in cartilage T2 times are observed between older vs. younger volunteers. 7 Tesla MRI of the fingers Dig.2-4 was performed using a multi-echo spin echo sequence. Manual segmentation of 3 ROIs at the metacarpal heads, 1 ROI at the base phalanx and 1 ROI at the proximal interphalangeal joint was performed. Included were 13 volunteers without history of trauma who are regularly performing climbing activities as a recreational sport (>20 h/month). These were age-matched with 10 control subjects not performing climbing activities. Mean age was 32.4 years for the climbing group and 25.8 years for the controls. Mean T2 values for the 5 different ROIs were 42.2 ± 7.8 msec for climbers and 41.4 ± 6.8 msec for non-climbers. No significant differences were observed for T2 values between both groups. However, higher age had a significant impact on T2 values for all assessed ROIs (higher age 44.2 ± 9.5, younger age 32.9 ± 5.7, p = 0.001). This study evaluated the cartilage composition of young, engaged climbers with a T2 mapping MRI technique with the purpose to depict early onset joint changes. No negative impact on cartilage composition due to the sport activity was found, whereas age-related effects on the cartilage seemed to be more prominent.

Gd-EOB-DTPA-Enhanced Magnetic Resonance Imaging Combined with T1 Mapping Identifies Dysplastic Module and Hepatocellular Carcinoma: A Retrospective Study.

Hepatocellular carcinoma (HCC) is the leading type of liver cancer in adults, often resulting in fatal outcomes for those with cirrhosis. Dysplastic nodule (DN) is a liver nodule that is substantial in size, ranging from 1-2 cm. However, accurately distinguishing between DN and HCC on imaging has posed a challenge. The aim of this study is to assess the usefulness of Gd-EOB-DTPA-enhanced MRI T1 mapping in distinguishing between DN and HCC. This study analyzed 66 patients with confirmed HCC or DN who underwent Gd-EOB-DTPA-enhanced MRI T1 mapping before surgery or puncture at the Army Medical Center in China. The T1 values of each lesion were measured before and after Gd-EOB-DTPA administration, and various calculations were made, including absolute and percentage reduction in T1 value and coefficient of variation. The t-test was used to compare these values between the two groups, and the efficacy of T1 mapping values for differential diagnosis of HCC and DN was evaluated using the receiver operating characteristic curve (ROC). The study found that T1pre, T1hp, ΔT1, ΔT1%, and CV in the HCC group were significantly higher than in the DN group (p < 0.01). The accuracy of T1hp, ΔT1, and CVT1-hp in identifying HCC from DN was high, with AUCs of 0.955, 0.910, and 0.932, respectively. ΔT1% also had some accuracy, with an AUC of 0.818. Our results provide preliminary evidence that Gd-EOB-DTPA-enhanced MRI T1, CVT1-hp mapping, can be a valuable tool in diagnosing and differentiating between HCC and DN.

Abstract 128: Saline Load Induces Acute Changes In Ventricular Extracellular Volume And Mass

Background: Maladaptive left ventricular hypertrophy (LVH) in hypertension is generally regarded as a result of myocardial fibrosis. However, salt loading induces a systemic and isotonic expansion of the extracellular (EC) volume in tissues, which could affect myocardial structure independent of fibrosis. Methods: Cardiac MRI, including cine-images and native T1 and T2 mapping as surrogates for EC volume and myocardial water content, was performed immediately before and after a saline infusion test (SIT; 2L NaCL 0.9% in 4h) in patients with primary aldosteronism (PA), a prototypic sodium-retentive form of hypertension. Results: We enrolled 13 consecutive patients with PA (5F; 50±12 yo; BP=140/88±14/7 mmHg; sK + =3.7±0.4 mmol/L on KCl supplements; renin=2.5[2.0-4.8] mIU/L, aldosterone=568[368-737] pmol/L), lacking aldosterone suppression after SIT (562 [262-776] pmol/L, p=0.127). SIT induced a small but significant increase in wall thickness (septum: 9.0±1.5 vs 9.5±1.0 mm, p=0.027) and, overall, in left ventricular mass (56.3±9.1 vs 58.0±9.2 g/m 2 , p=0.026), paralleled by an increase in myocardial T1 (1012±29 vs 1027±25 ms, p&lt;0.001) and T2 (49.9±2.0 vs 51.2±2.7 ms, p=0.012). After saline the left ventricular ejection fraction was mildly reduced (56[55-62] vs 53[51-59]%, p=0.023), reflecting an increase in end-systolic (ES) volume (38±10 vs 43±10 ml/m 2 , p=0.030) without significant changes in the end-diastolic (ED) volume (88±18 vs 91±16 ml/m 2 , p=0.114). Conclusions: Within a timeframe inconsistent with EC matrix remodeling, saline load induced an increase in ventricular mass and an expansion of the EC volume, i.e. edema, in a human model of salt-related disease.

T2 mapping magnetic resonance imaging of cartilage in hemophilia

BackgroundIn hemophilia, recurrent hemarthrosis may lead to irreversible arthropathy. T2 mapping MRI may reflect cartilage changes at an earlier reversible stage of arthropathy as opposed to structural MRI. ObjectivesTo evaluate interval changes of T2 mapping compared with the International Prophylaxis Study Group (IPSG) structural MRI scores of ankle cartilage in boys with hemophilia receiving prophylaxis. MethodsEight boys with hemophilia A (median age, 13; range, 9-17 years), 7 age- and sex-matched healthy boys (controls, median age, 15; range, 7-16 years). A multiecho spin-echo T2-weighted MRI sequence at 3.0T was used to obtain T2 maps of cartilage of boys with hemophilia and controls. Structural joint status was evaluated using the IPSG MRI score. ResultsT2 relaxation times of ankle cartilage increased significantly over time in both persons with hemophilia and controls (P = .002 and P = .00009, respectively). Changes in T2 relaxation time strongly correlated with changes in IPSG cartilage scores (rs = 0.93 to rs = 0.78 [P = .0007 to P = .023]), but not with changes in age (P = .304 to P = .840). Responsiveness of T2 relaxation times were higher than that of IPSG cartilage scores, with standardized response means >1.4 for T2 mapping in all regions-of-interest compared with 0.84 for IPSG cartilage scores. Baseline T2 relaxation time strongly correlated with timepoint 2 IPSG cartilage score (rs = 0.93 to rs = 0.82 [P = .001 to P = .012]) and T2 relaxation time (rs = 0.98 to rs = 0.88 [P = .00003 to P = .004]) changes in most regions-of-interest. ConclusionT2 mapping shows sensitivity to biochemical changes in cartilage prior to detectable damage using conventional MRI, offering potential for early detection of bleed-related cartilage damage in boys with hemophilia.

Evaluation of liver function using Gd-EOB-DTPA-enhanced MRI with T1 mapping

PurposeTo evaluate the value of MRI T1 mapping with Gd-EOB-DTPA for assessing liver function.MethodsSeventy-two patients who underwent Gd-EOB-DTPA-enhanced MRI for focal liver lesions at Beijing Friendship Hospital from August 2020 to March 2022 were prospectively enrolled, and variable-flip-angle T1 mapping was performed before and 20 min after enhancement. The Child–Pugh (C-P) score and albumin-bilirubin (ALBI) grade of liver function were assessed using the clinical data of the patients. Correlation analysis was used to evaluate the correlation between T1 mapping parameters and liver function grading and laboratory tests. Nonparametric tests were used to compare the differences among different liver function groups. The liver function classification efficiency of each image index was evaluated with receiver operating characteristic (ROC) curves.ResultsT1post was positively correlated with the C-P grade and the ALBI grade (r = 0.717 and r = 0.652). ΔT1 was negatively correlated with the C-P grade and the ALBI grade (r = -0.790 and r = -0.658). T1post and ΔT1 significantly differed among different liver function grades (p < 0.05). For the C-P grade, T1post and ΔT1 were significantly different between each pair of groups (p < 0.05), and ΔT1 had a better diagnostic efficiency than T1post. For the ALBI grade, ΔT1 and T1post were significantly different between the NLF and ALBI1 groups (p < 0.05), and ΔT1 had a better diagnostic efficacy than T1post. T1post significantly differed between the ALBI1 and ALBI2 + 3 groups (p < 0.05), while ΔT1 had a weak ability to differentiate between these two groups.ConclusionT1post and ΔT1 were strongly correlated with the two liver function grades and can be noninvasive imaging indexes for evaluating liver function.

Histopathologic Validation of Stress T1 Mapping in Myocardial Ischemia: Another Step toward Clinical Translation?

Histopathologic Validation of Stress T1 Mapping in Myocardial Ischemia: Another Step toward Clinical Translation?

Improved accuracy and precision of fat-suppressed isotropic 3D T2 mapping MRI of the knee with dictionary fitting and patch-based denoising

PurposeTo develop an isotropic three-dimensional (3D) T2 mapping technique for the quantitative assessment of the composition of knee cartilage with high accuracy and precision.MethodsA T2-prepared water-selective isotropic 3D gradient-echo pulse sequence was used to generate four images at 3 T. These were used for three T2 map reconstructions: standard images with an analytical T2 fit (AnT2Fit); standard images with a dictionary-based T2 fit (DictT2Fit); and patch-based-denoised images with a dictionary-based T2 fit (DenDictT2Fit). The accuracy of the three techniques was first optimized in a phantom study against spin-echo imaging, after which knee cartilage T2 values and coefficients of variation (CoV) were assessed in ten subjects in order to establish accuracy and precision in vivo. Data given as mean ± standard deviation.ResultsAfter optimization in the phantom, whole-knee cartilage T2 values of the healthy volunteers were 26.6 ± 1.6 ms (AnT2Fit), 42.8 ± 1.8 ms (DictT2Fit, p < 0.001 versus AnT2Fit), and 40.4 ± 1.7 ms (DenDictT2Fit, p = 0.009 versus DictT2Fit). The whole-knee T2 CoV reduced from 51.5% ± 5.6% to 30.5 ± 2.4 and finally to 13.1 ± 1.3%, respectively (p < 0.001 between all). The DictT2Fit improved the data reconstruction time: 48.7 ± 11.3 min (AnT2Fit) versus 7.3 ± 0.7 min (DictT2Fit, p < 0.001). Very small focal lesions were observed in maps generated with DenDictT2Fit.ConclusionsImproved accuracy and precision for isotropic 3D T2 mapping of knee cartilage were demonstrated by using patch-based image denoising and dictionary-based reconstruction.Key points• Dictionary T2 fitting improves the accuracy of three-dimensional (3D) knee T2 mapping.• Patch-based denoising results in high precision in 3D knee T2 mapping.• Isotropic 3D knee T2 mapping enables the visualization of small anatomical details.

PO-455617-1 EXPLORING THE INTERPLAY OF FUNCTIONAL AND STRUCTURAL REMODELING PROGRESSION IN ATRIAL FIBRILLATION IN A RAPID ATRIAL PACING CANINE MODEL

In sustained atrial fibrillation (AF) it is still unclear to what extent, at which time points functional and structural remodeling processes develop over time, and which parameters can measure the progression state. We hypothesized that persistent AF progression state induced by rapid atrial pacing (RAP) can be uncovered by measuring electrogram characteristics, OS levels, nerve activity, and the degree of fibrosis with MRI imaging. AF was induced in 15 dogs (25-35 kg, ≥1 year) by RAP (3-17 weeks RAP, 600 beats/min), and 8 controls were used. We performed high-resolution epicardial mapping (6 regions, 130 electrodes, distance 2.5mm) (Figure 1) and analyzed bipolar peak-to-peak voltage, cycle length (CL), and organization index (OI). We quantified OS levels as damaged nuclei against total number in 8-OHdG staining (N=36 samples, 6 animals) and degree of fibrosis (Masson’s trichrome) (N=24, 4 dogs). We also quantified in implantable telemetry recordings (DSI) parasympathetic nerve activity (PNA) (2 hours) assessed as the time between PNA spikes (3 AF dogs, 3 controls). MRI native T1, post-contrast T1, and T2 mapping, and late gadolinium enhancement (LGE) were assessed (1.5T clinical scanner, Siemens Aera) in the posterior left atrium (PLA) (7 AF, 8 at baselines). Voltage, CL, and OI decreased (R=0.9, P<0.05), (R=0.6, P<0.05), (R=0.5, P<0.05) over time of RAP (Figure 1). After 80 RAP days voltage changed, but no more changes in other EGM measures were observed. OS levels in AF were highest in the left atrial free wall and lowest in the appendages (Figure 2). The electrogram measures OI and CL decreased with increased oxidative stress levels (Figure 2). Fibrosis (R=0.6, P<0.05) increased with OS (R=0.6, P<0.05) in all atrial regions (Figure 2). Parasympathetic nerve activity increased by factor 5 after 120 RAP days, (Figure 3). Native T1, T2 times increased with RAP days (R=0.6, P<0.05), (R=0.4, P<0.05) in PLA (<120 pacing days) (Fig. 4). Functional and structural remodeling in persistent AF is the result of an interplay among the development of increased OS, fibrosis, and nerve activity in a RAP canine model and can moderately be uncovered using the electrogram measures CL and OI until the saturation point after 80 RAP days. Voltage also uncovers the AF progression state post 80- RAP days with a strong correlation coefficient. Additional parasympathetic nerve recordings and MRI imaging including T1 mapping may be complementary to detect AF remodeling states.

The Efficacy of Microfracture Combined with Extracorporeal Shock Wave Therapy for Treating Osteochondral Lesion of the Talus and the Quality of Regenerated Cartilage: A Retrospective Cohort Study and MRI Assessment.

osteochondral lesion of the talus (OLT) is a common disease in the physically active population, and extracorporeal shock wave therapy (ESWT) is a noninvasive treatment. We hypothesized that microfracture (MF) combined with ESWT may have great potential to become a novel combination treatment of OLT. the OLT patients who received MF + ESWT or MF + platelet-rich plasma (PRP) injection were retrospectively included, with a minimal follow up of 2y. The daily activating VAS, exercising VAS, and American Orthopedic Foot and Ankle Society Ankle-Hindfoot Score (AOFAS) were used to assess the efficacy and functional outcome, and ankle MRI T2 mapping was used to evaluate the quality of regenerated cartilage in the OLT patients. only transient synovium-stimulated complications were found during the treatment sessions; the complication rate and daily activating VAS did not have differences between groups. MF + ESWT had a higher AOFAS and a lower T2 mapping value than MF + PRP at the 2y follow up. the MF + ESWT had superior efficacy for treating OLT, which resulted in better ankle function and more hyaline-like regenerated cartilage, superior to the traditional MF + PRP.

MICRORNA BIOMARKERS IN EQUINE DISTAL INTERPHALANGEAL OSTEOARTHRITIS

Osteoarthritis (OA) of the equine distal interphalangeal joint (DIPJ) is a common cause of lameness. MicroRNAs (miRNAs) from biofluids such as plasma and synovial fluid make promising biomarker and therapeutic candidates.The objectives of this study are (1) Identify differentially expressed (DE) miRNAs in mild and severe equine DIPJ OA synovial fluid samples and (2) Determine the effects of DE miRNAs on equine chondrocytes in monolayer culture.Synovial fluid samples from five horses with mild and twelve horses with severe DIPJ OA were submitted for RNA-sequencing; OA diagnosis was made from MRI T2 mapping, macroscopic and histological evaluation. Transfection of equine chondrocytes (n=3) was performed using the Lipofectamine® RNAiMAX system with a negative control and a miR-92a mimic and inhibitor. qPCR was used to quantify target mRNA genes.RNA-seq showed two miRNAs (miR-16 and miR-92a) were significantly DE (p&lt;0.05). Ingenuity Pathway Analysis (IPA) identified important downstream targets of miR-92a involved in the pathogenesis of osteoarthritis and so this miRNA was used to transfect equine chondrocytes from three donor horses diagnosed with OA. Transfection was successfully demonstrated by a 1000-20000 fold increase in miR-92a expression in the equine chondrocytes. There was a significant (p&lt;0.05) increase in COMP, COL3A1 and Sox9 in the miR-92a mimic treatment and there was no difference in ADAMTS-5 expression between the miR-92 mimic and inhibitor treatment.RNA-seq demonstrated miR-92a was downregulated in severe OA synovial fluid samples which has not previously been reported in horses, however miR-92a is known to play a role in the pathogenesis of OA in other species. Over expression of miR-92a in equine chondrocytes led to significantly increased COMP and Sox9 expression, consistent with a chondrogenic phenotype which has been identified in human and murine chondrocytes.

Perfusion and T2 Relaxation Time as Predictors of Severity and Outcome in Sepsis-Associated Acute Kidney Injury: A Preclinical MRI Study.

Preventing sepsis-associated acute kidney injury (S-AKI) can be challenging because it develops rapidly and is often asymptomatic. Probability assessment of disease progression for therapeutic follow-up and outcome are important to intervene and prevent further damage. To establish a noninvasive multiparametric MRI (mpMRI) tool, including T1 , T2 , and perfusion mapping, for probability assessment of the outcome of S-AKI. Preclinical randomized prospective study. One hundred and forty adult female SD rats (65 control and 75 sepsis). 9.4T; T1 and perfusion map (FAIR-EPI) and T2 map (multiecho RARE). Experiment 1: To identify renal injury in relation to sepsis severity, serum creatinine levels were determined (31 control and 35 sepsis). Experiment 2: Animals underwent mpMRI (T1 , T2 , perfusion) 18 hours postsepsis. A subgroup of animals was immediately sacrificed for histology examination (nine control and seven sepsis). Result of mpMRI in follow-up subgroup (25 control and 33 sepsis) was used to predict survival outcomes at 96 hours. Mann-Whitney U test, Spearman/Pearson correlation (r), P < 0.05 was considered statistically significant. Severely ill septic animals exhibited significantly increased serum creatinine levels compared to controls (70 ± 30 vs. 34 ± 9 μmol/L, P < 0.0001). Cortical perfusion (480 ± 80 vs. 330 ± 140 mL/100 g tissue/min, P < 0.005), and cortical and medullary T2 relaxation time constants were significantly reduced compared to controls (41 ± 4 vs. 37 ± 5 msec in cortex, P < 0.05, 52 ± 7 vs. 45 ± 6 msec in medulla, P < 0.05). The combination of cortical T2 relaxation time constants and perfusion results at 18 hours could predict survival outcomes at 96 hours with high sensitivity (80%) and specificity (73%) (area under curve of ROC = 0.8, Jmax = 0.52). This preclinical study suggests combined T2 relaxation time and perfusion mapping as first line diagnostic tool for treatment planning. 2 TECHNICAL EFFICACY STAGE: 2.

T1 mapping of the prostate using Single-Shot T1FLASH and MOLLI MRI Techniques: Comparison of artifact burden and image quality

PurposeTo assess artifact burden and image quality of different MRI T1 mapping techniques of the prostate. MethodsParticipants with suspected prostate cancer (PCa) were prospectively enrolled from June-October 2022 and examined with multiparametric prostate MRI (mpMRI; 3 T scanner; T1wi, T2wi, DWI und DCE). T1 mapping was performed before and after administration of gadolinium-based contrast-agent (GBCA) using (i) a modified Look-Locker inversion (MOLLI) technique and (ii) a novel single-shot T1FLASH inversion recovery technique. T2wi, DWI, T1FLASH and MOLLI sequences were systematically examined regarding prevalence of artifacts and image quality using a 5-point Likert-Scale. ResultsA total of n = 100 patients were included (median age: 68 years). T1FLASH maps (pre-and post-GBCA) showed metal artifacts in 7% of cases and susceptibility artifacts in 1%. For MOLLI maps, pre-GBCA metal and susceptibility artifacts were documented in 6.5% of cases each. MOLLI maps post-GBCA showed artifacts in 59% of cases resulting primarily from urinary GBCA excretion and GBCA accumulation at the bladder base (p < 0.01 versus T1FLASH post-GBCA). Image quality for T1FLASH pre-GBCA was rated at a mean 4.9+/-0.4 and for MOLLI at 4.8+/-0.6 (p = 0.14). Post-GBCA image quality was rated at a mean 4.9+/-0.4 for T1FLASH and at 3.7+/-1.1 for MOLLI (p < 0.001). ConclusionsT1FLASH maps provide a fast and robust method for quantification of T1 relaxation times of the prostate. T1FLASH is suitable for T1 mapping of the prostate following administration of contrast agents, while MOLLI T1 mapping is impaired through GBCA accumulation at the bladder base leading to severe image artifacts and reduced image quality.

Validation of automatically measured T1 map cortico-medullary difference (ΔT1) for eGFR and fibrosis assessment in allograft kidneys.

MRI T1-mapping is an important non-invasive tool for renal diagnosis. Previous work shows that ΔT1 (cortex-medullary difference in T1) has significant correlation with interstitial fibrosis in chronic kidney disease (CKD) allograft patients. However, measuring cortico-medullary values by manually drawing ROIs over cortex and medulla (a gold standard method) is challenging, time-consuming, subjective and requires human training. Moreover, such subjective ROI placement may also affect the work reproducibility. This work proposes a deep learning-based 2D U-Net (RCM U-Net) to auto-segment the renal cortex and medulla of CKD allograft kidney T1 maps. Furthermore, this study presents a correlation of automatically measured ΔT1 values with eGFR and percentage fibrosis in allograft kidneys. Also, the RCM U-Net correlation results are compared with the manual ROI correlation analysis. The RCM U-Net has been trained and validated on T1 maps from 40 patients (n = 2400 augmented images) and tested on 10 patients (n = 600 augmented images). The RCM U-Net segmentation results are compared with the standard VGG16, VGG19, ResNet34 and ResNet50 networks with U-Net as backbone. For clinical validation of the RCM U-Net segmentation, another set of 114 allograft kidneys patient's cortex and medulla were automatically segmented to measure the ΔT1 values and correlated with eGFR and fibrosis. Overall, the RCM U-Net showed 50% less Mean Absolute Error (MAE), 16% better Dice Coefficient (DC) score and 12% improved results in terms of Sensitivity (SE) over conventional CNNs (i.e. VGG16, VGG19, ResNet34 and ResNet50) while the Specificity (SP) and Accuracy (ACC) did not show significant improvement (i.e. 0.5% improvement) for both cortex and medulla segmentation. For eGFR and fibrosis assessment, the proposed RCM U-Net correlation coefficient (r) and R-square (R2) was better correlated (r = -0.2, R2 = 0.041 with p = 0.039) to eGFR than manual ROI values (r = -0.19, R2 = 0.037 with p = 0.051). Similarly, the proposed RCM U-Net had noticeably better r and R2 values (r = 0.25, R2 = 0.065 with p = 0.007) for the correlation with the renal percentage fibrosis than the Manual ROI results (r = 0.3, R2 = 0.091 and p = 0.0013). Using a linear mixed model, T1 was significantly higher in the medulla than in the cortex (p<0.0001) and significantly lower in patients with cellular rejection when compared to both patients without rejection and those with humoral rejection (p<0.001). There was no significant difference in T1 between patients with and without humoral rejection (p = 0.43), nor between the types of T1 measurements (Gold standard manual versus automated RCM U-Net) (p = 0.7). The cortico-medullary area ratio measured by the RCM U-Net was significantly increased in case of cellular rejection by comparison to humoral rejection (1.6 +/- 0.39 versus 0.99 +/- 0.32, p = 0.019). In conclusion, the proposed RCM U-Net provides more robust auto-segmented cortex and medulla than the other standard CNNs allowing a good correlation of ΔT1 with eGFR and fibrosis as reported in literature as well as the differentiation of cellular and humoral transplant rejection. Therefore, the proposed approach is a promising alternative to the gold standard manual ROI method to measure T1 values without user interaction, which helps to reduce analysis time and improves reproducibility.

Clinical evaluation of platelet-rich plasma in the treatment of early and middle stage knee osteoarthritis under 3.0T MRI T2 mapping sequence

Objective: To quantitatively evaluate the clinical effect of platelet-rich plasma(PRP) intra-articular injection for early and middle stage knee osteoarthritis(KOA) treatment by 3.0T MRI T2 mapping sequence. Methods: Clinical data of 26 patients with early or middle stage KOA who received treatment from April to December 2021 at Department of Orthopaedic Surgery,the Second Affiliated Hospital,Zhengzhou University were retrospectively analyzed. In total, 8 patients were male and 18 were female,with age of (66.4±12.0)years(range:51 to 94 years). Four patients were bilateral KOA and 22 patients were unilateral KOA.All patients received PRP intra-articular injection. Patients underwent 3.0T MRI T2 mapping sequence scanning pre-treatment,3-month-after and 6-month-after treatment respectively. Those were used to measure and compare T2 values of medial and lateral femoral articular surface and patellofemoral articular surface. Visual analogue scale(VAS) and Western Ontario and McMaster Osteoarthritis Index (WOMAC) score were recorded and evaluated. The results were analyzed using repeated measure ANOVA followed by Bonferroni multiple comparison test.The correlation between WOMAC scores and T2 values at pre-treatment and 6 months post-treatment was analyzed using Pearson correlation test. Results: After treatment, the patients' International Cartilage Regeneration＆Joint Preservation Society(ICRS) classification were partly improved(one case improved from grade Ⅲ to grade Ⅱ, one case improved from grade Ⅱ to grade Ⅰ),and all patients generally improved after treatment in clinical symptoms. Compared with pre-treatment,VAS and WOMAC scores of grade Ⅰ,Ⅱ,and Ⅲ of 6-month after treatment were declined significantly(all P<0.05).The T2 values of articular cartilage declined to varying degrees(the decrease in T2 values was about 2.06 ms in grade Ⅰ, 2.66 ms in grade Ⅱ, and 3.72 ms in grade Ⅲ).Three-month (VAS:4.8±1.3,WOMAC:21.5±4.0) and 6-month (VAS:4.2±1.4,WOMAC:17.2±2.9) after treatment, the VAS and WOMAC score were significantly higher than those before treatment (VAS:6.0±1.2, WOMAC:29.0±2.3) (F=48.846, F=346.746;both P<0.01). Multiple comparisons showed a statistically significant difference between pre-treatment and post-treatment VAS (P<0.01) and it also was significantly different between 3-month and 6-month post-treatment (P<0.01).At 3- and 6-month after treatment,WOMAC scores were significantly different from before treatment.And it also was significantly different between 3-month and 6-month post-treatment (P<0.01).There was a statistically significant improvement in T2 values of patellofemoral articular surface, medial and lateral femoral articular surface at pre-treatment((44.64±4.02)ms,(44.17±3.64)ms and(43.53±3.91)ms) and 3-month ((43.19±3.91)ms,(43.24±3.34)ms and (42.47±3.80)ms), 6-month ((41.49±3.64)ms,(41.83±3.15)ms and (41.10±3.42)ms) after treatment(F=148.845,F=73.657,F=86.268;all P<0.01).The results of the multiple comparisons showed a statistically significant difference in the T2 values of medial and lateral femoral articular surface and patellofemoral articular surface at each time point(all P<0.01).The Pearson correlation analysis suggested that the WOMAC score at pre-treatment was positively correlated with the medial condyle (r=0.856,P<0.01) and the patellofemoral joint surface T2 values (r=0.840,P<0.01);The WOMAC score at 6-month post-treatment was positively correlated with the medial condyle (r=0.731,P<0.01) and the patellofemoral joint surface T2 values (r=0.691,P<0.01). Conclusions: In the treatment of early and mid-stage KOA,MRI T2 mapping sequences are able to indicate the integrity of cartilage morphology and quantitatively evaluate cartilage repair. PRP has a good therapeutic effect on cartilage repair and reconstruction.

Myocardial Characterization with Extracellular Volume Mapping with a First-Generation Photon-counting Detector CT with MRI Reference.

Background Photon-counting detector (PCD) CT provides comprehensive spectral data with every acquisition, but studies evaluating myocardial extracellular volume (ECV) quantification with use of PCD CT compared with an MRI reference remain lacking. Purpose To compare ECV quantification for myocardial tissue characterization between a first-generation PCD CT system and cardiac MRI. Materials and Methods In this single-center prospective study, adults without contraindication to iodine-based contrast media underwent same-day cardiac PCD CT and MRI with native and postcontrast T1 mapping and late gadolinium enhancement for various clinical indications for cardiac MRI (the reference standard) between July 2021 and January 2022. Global and midventricular ECV were assessed with use of three methods: single-energy PCD CT, dual-energy PCD CT, and MRI T1 mapping. Quantitative comparisons among all techniques were performed. Correlation and reliability between different methods of ECV quantification were assessed with use of the Pearson correlation coefficient (r) and the intraclass correlation coefficient. Results The final sample included 29 study participants (mean age ± SD, 54 years ± 17; 15 men). There was a strong correlation of ECV between dual- and single-energy PCD CT (r = 0.91, P < .001). Radiation dose was 40% lower with dual-energy versus single-energy PCD CT (volume CT dose index, 10.1 mGy vs 16.8 mGy, respectively; P < .001). In comparison with MRI, dual-energy PCD CT showed strong correlation (r = 0.82 and 0.91, both P < .001) and good to excellent reliability (intraclass correlation coefficients, 0.81 and 0.90) for midventricular and global ECV quantification, but it overestimated ECV by approximately 2%. Single-energy PCD CT showed similar relationship with MRI but underestimated ECV by 3%. Conclusion Myocardial tissue characterization with photon-counting detector CT-based quantitative extracellular volume analysis showed a strong correlation to MRI. © RSNA, 2023 Supplemental material is available for this article.