Magnetic Resonance T1 Mapping Research Articles

Quantification of doxorubicin-induced interstitial myocardial fibrosis in a beagle model using equilibrium contrast-enhanced computed tomography: A comparative study with cardiac magnetic resonance T1-mapping

BackgroundThe noninvasive equilibrium contrast-enhanced cardiac computed tomography (CCT) has potential for myocardial tissue characterization. The objective of this study was to test the feasibility of CCT-based extracellular volume (ECV) fraction in beagle models of doxorubicin-induced interstitial myocardial fibrosis, with cardiac magnetic resonance (CMR) as the reference. MethodsThis study was approved by local ethics committee. Thirteen beagles were included with ECV quantified by CCT and CMR at baseline, 16 and 24 weeks after modeling. Spearman correlation analysis was used to determine the association between CT ECV, CMR ECV, collagen volume fraction (CVF), LVEF and serum fibrosis index (Hyaluronic acid [HA], Laminin [LN] and Type-III procollagen [PCIII]). ResultsMedian ECV values in CT and CMR at 16 and 24 weeks were significantly higher than those at baseline (CT ECV: 34.4% and 37.7% vs. 25.2%; CMR ECV: 32.2% and 37.4% vs. 22.7%; P < 0.001). A strong correlation was found between CCT and CMR for ECV (r = 0.899, P < 0.001). Both correlated well with CVF (r = 0.951 and 0.879 for CT and MR ECV vs. CVF, P < 0.001), serum fibrosis index (r = 0.830–0.907 for CT and MR ECV vs. HA, LN, PCIII, respectively, P < 0.05) and were inversely related to LVEF (r = −0.846 and −0.804 for CCT and CMR, P < 0.001). Bland-Altman analysis showed a small bias (1.5%), with 95% limits of agreement of −2.7% and 5.6%. ConclusionsCCT-derived ECV correlates well with CMR, histology and serum fibrosis index, suggesting that CCT is capable of myocardial tissue characterization.

Diagnostic performance of cardiovascular magnetic resonance native T1 and T2 mapping in pediatric patients with acute myocarditis

BackgroundMultiple studies in adult patients suggest that tissue mapping performed by cardiovascular magnetic resonance (CMR) has excellent diagnostic accuracy in acute myocarditis, however, these techniques have not been studied in depth in children.MethodsCMR data on 23 consecutive pediatric patients from 2014 to 2017 with a clinical diagnosis of acute myocarditis were retrospectively analyzed and compared to 39 healthy controls. The CMR protocol included native T1, T2, and extracellular volume fraction (ECV) in addition to standard Lake Louise Criteria (LLC) parameters on a 1.5 T scanner.ResultsMean global values for novel mapping parameters were significantly elevated in patients with clinically suspected acute myocarditis compared to controls, with native T1 1098 ± 77 vs 990 ± 34 ms, T2 52.8 ± 4.6 ms vs 46.7 ± 2.6 ms, and ECV 29.8 ± 5.1% vs 23.3 ± 2.6% (all p-values < 0.001). Ideal cutoff values were generated using corresponding ROC curves and were for global T1 1015 ms (AUC 0.936, sensitivity 91%, specificity 86%), for global T2 48.5 ms (AUC 0.908, sensitivity 91%, specificity 74%); and for ECV 25.9% (AUC 0.918, sensitivity 86%, specificity 89%). While the diagnostic yield of the LLC was 57% (13/23) in our patient cohort, 70% (7/10) of patients missed by the LLC demonstrated abnormalities across all three global mapping parameters (native T1, T2, and ECV) and another 20% (2/10) of patients demonstrated at least one abnormal mapping value.ConclusionsSimilar to findings in adults, pediatric patients with acute myocarditis demonstrate abnormal CMR tissue mapping values compared to controls. Furthermore, we found CMR parametric mapping techniques measurably increased CMR diagnostic yield when compared with conventional LLC alone, providing additional sensitivity and specificity compared to historical references. Routine integration of these techniques into imaging protocols may aid diagnosis in children.

Relationship between myocardial fibrosis evaluated by cardiac magnetic resonance T1 mapping and N-terminal pro-B-type natriuretic peptide in elderly patients with ischemic cardiomyopathy

Objective To investigate the correlation between myocardial fibrosis evaluated by cardiac magnetic resonance(CMR)T1 mapping and N-terminal pro-B-type natriuretic peptide(NT-proBNP)in elderly patients with ischemic cardiomyopathy(ICM). Methods The 56 hospitalized patients with ICM(ICM group)and 20 healthy volunteers(control group)were recruited in cardiology department of Henan Provincial People's Hospital from April 2014 to June 2017.Clinical data, serum NT-proBNP detection, CMR T1 mapping and contrast-enhanced scan were determined, retrospectively collected and compared between two groups.The differences in myocardial extracellular volume fraction(ECVF)and NT-proBNP levels were compared among the control group, the ICM group and the ICM subgroups with different degree of cardiac dysfunction.The correlation between ECVF and NT-proBNP level was analyzed. Results The levels of ECVF and NT-proBNP were significantly higher in ICM group than in control group[(35.1±6.2)% vs.(25.3±2.2)% for ECVF, and(3 902.7±1 670.3)ng/L vs.(280.5±140.5)ng/L for NT-proBNP, t=6.917 and 9.645 respectively, both P<0.01]. Along with NYHA Functional Class upgrade of Ⅱ to Ⅲ to Ⅳ of the ICM subgroups, the levels of ECVF and NT-proBNP were significantly increased(F=18.372 for ECVF, 61.82 for NT-proBNP, all P<0.01). There was a positive correlation between ECVF and NT-proBNP level in ICM patients(r=0.666, P<0.05). Conclusions Serum NT-proBNP level is correlated with the degree of myocardial fibrosis, which might be used as an indicator of myocardial fibrosis in ICM patients. Key words: Myocardial ischemia; Natriuretic peptide, Brain; Magnetic resonance imaging

Abstract 16863: Cardiac Magnetic Resonance T1 Mapping as a Window Into the Myocardium in Friedreich Ataxia

Introduction: Left ventricular (LV) remodeling and hypertrophy are common findings in Friedreich Ataxia (FA) and associated with a poorer prognosis. Cardiac magnetic resonance (CMR) T1 mapping, a technique used to assess myocardial fibrosis, may be able to identify cardiomyopathic changes in FA at an early stage of the cardiac disease process. We hypothesized that T1 mapping variables would demonstrate myocardial involvement in FA independently of the recognized LV structural and functional changes. Methods: A standardized CMR protocol including T1 mapping and measurements of LV mass, LV end-diastolic volume, native T1 time, post gadolinium (PostGad) T1 time, and calculation of the LV mass/volume ratio (LVMVR), partition coefficient (PC), and extracellular volume (ECV) was performed at two sites on FA subjects who were homozygous for GAA repeats in the FXN gene. GAA repeat length in the shorter allele (GAA1) of the frataxin gene ( FXN ) was used as a surrogate for the degree of frataxin deficiency. Results: Ninety-five FA subjects (56% males, median age 22 yrs, age of onset 10 yrs, GAA1 700) were scanned. Nine FA subjects had a LV ejection fraction (EF) &amp;lt;55%; their T1 variables were not different than those with preserved LVEF. Fifty-three subjects had an elevated LVMVR (&amp;gt;1.20); their T1 variables were not different from those without an elevated LVMVR. On multivariate analysis, GAA1 correlated with native T1 time (p=0.009), PostGad T1 time (p=0.003), PC (p&amp;lt;0.001), and ECV (p&amp;lt;0.001) after adjusting for sex, age and site. LVMVR was a correlate of native T1 time when adjusted for sex, age and site (p=0.019), but not when also adjusted for GAA1, whereas GAA1 still predicted native T1 when adjusted for sex, age, site, and LVMVR (p=0.018). Conclusion: T1 mapping provides information about the myocardium in FA which is correlated with the degree of frataxin deficiency and is independent of LV remodeling. Study of the relationship between T1 variables and cardiac outcomes is now needed to help determine the utility of this technique as a monitoring and prognostic biomarker for this rare disease.

Evaluating the mandibular condyles of patients with osteoarthritis for bone marrow abnormalities using magnetic resonance T2 mapping.

This study investigated whether erosion and osteophyte correlates with condyle bone marrow abnormalities (BMA), as detected with quantitative T2 mapping. Fifty-six joints (in 44 patients) that demonstrated evidence of bony erosion (ER) or osteophytes (OS) related to disc displacement without reduction were studied with MR images. A control group of 50 joints (in 50 patients) was included. The subjects were divided into five groups; noAR (control), noBMA-ER, BMA-ER, noBMA-OS, and BMA-OS. T2 mapping was performed and the regions of interest were placed over the bone marrow at the top of the condyle. The mean T2 values of the bone marrow of the mandibular condyle were calculated for all mapping images. After assessing age-related changes in T2 values of noAR group using Pearson's product-moment, differences in median T2 values of five groups were analyzed using Kruskal-Wallis test, and Steel-Dwass test (p < 0.05). There was no significant correlation between age and T2 value in noAR group. The median T2 values of noBMA-ER and BMA-ER groups were significantly higher than those of noAR, noBMA-OS and BMA-OS groups. Those of noBMA-OS and BMA-OS groups were significantly lower than those of noAR, noBMA-ER and BMA-ER groups. There was no significant difference between noBMA and BMA groups. It is suggested that erosion and osteophyte of the condyle may correlate with bone marrow abnormalities. T2 mapping could be show slight marrow changes of the arthritic condyle.

Myocardial Partition Coefficient of Gadolinium: A Pilot Study in Patients With Acute Myocarditis, Chronic Myocardial Infarction, and in Healthy Volunteers

BackgroundThe tissue-blood partition coefficient (PC) of gadolinium, derived from T1 measurements, reflects myocardial connective tissue fraction and tissue injury, increasing in proportion with edema or fibrosis. We determined the myocardial PC of gadolinium in patients with acute myocarditis, chronic myocardial infarction (MI), and healthy volunteers. We hypothesized that the characteristics of the injured myocardium in patients with MI and myocarditis may differ and that the PC will be higher in chronically injured myocardium (MI) compared with acutely injured myocardium (myocarditis). MethodsWe performed late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging and T1 mapping before and after administration of gadolinium (0.1 mmol/kg Gd-BOPTA) at 3 Tesla in 10 healthy volunteers (47.1 ± 12.4 years), 18 patients with chronic MI (62.5 ± 8.1 years), and 16 patients with acute myocarditis (42.5 ± 13.9 years). ResultsIn patients with chronic MI and focal scar by LGE, the whole left ventricular myocardial PC (0.45 ± 0.05) was higher compared with patients with MI without focal scar (0.39 ± 0.03, P = 0.02) but not significantly different from whole myocardial PC in volunteers (0.40 ± 0.05) or patients with myocarditis (0.41 ± 0.05). The PC in myocarditis scars was lower than in chronic MI scars (0.60 ± 0.12 vs 0.77 ± 0.16, P = 0.016). The relationships of PC and scar burden, expressed as % LGE, were similar and significant for the 2 groups (P = 0.042). ConclusionThe tissue-blood partition coefficient of Gd-BOPTA is elevated in areas of acute and chronic myocardial injury and may serve as a marker for disease activity and density of scars, which was found to be higher in chronic MI than in acute myocarditis.

T2 mapping MRI technique quantifies carotid plaque lipid, and its depletion after statin initiation, following acute myocardial infarction

Background & aimsA recently-validated, highly-sensitive T2 mapping magnetic resonance (MRI) technique accurately quantifies carotid plaque lipid. The aims of this study were to determine: (i) the extent of carotid plaque lipid in patients with acute coronary syndromes (ACS); (ii) the effects of initiation of high-intensity statin on plaque lipid content and (iii) whether plaque lipid content is related to standard or ‘functional’ blood lipid measurements. MethodsStatin naïve subjects presenting with ACS underwent carotid artery MRI at 3 T scanner to quantify plaque lipid. Patients were subsequently commenced on high dose statin as part of clinical care and underwent a second MRI after three months. Plaque composition was measured using objective semi-automated techniques. Results23 out of 24 patients had measurable lipid. Three months after statin initiation there was a significant reduction in carotid lipid percentage [from 10.3% (7.2–14.2) to 7.4% (5.4–10.0), p = 0.002] and a significant increase in fibrous percentage [from 83.3% ± 6.6–85.5% ± 4.8, p = 0.039]. None of the studied functional blood biomarkers were related to either baseline carotid plaque lipid content or its propensity to change with statin treatment. ConclusionsT2-mapping demonstrated depleted carotid plaque lipid following the initiation of high-intensity statin treatment. Standard or ‘functional’ blood biomarkers were dissociated from plaque lipid content or changes with treatment. These findings further reinforce the importance of disease characterisation over risk factor assessment. Subject to clinical trial findings, quantification of plaque lipid may provide the basis for an approach to identify patients suitable for intensive lipid reduction regimes.

Amyloidosis cardiomyopathy

The present article provides an update about the recent advances in the diagnosis and management of the most common types of cardiac amyloidosis, including light chain, wild-type transthyretin (ATTRwt), and mutant transthyretin (ATTRm). The document reviews the utility of diagnostic tools including innovative echocardiographic indices, magnetic resonance T1 mapping and measurement of extracellular volume, and the role and validation of bone scintigraphy for the noninvasive assessment of ATTR amyloidosis. It summarizes the data about therapies for light chain amyloidosis including bortezomib regimens and also novel disease modifying therapies for ATTR amyloidosis such as gene silencers, transthyretin stabilizers, and degraders of amyloid fibrils. The present review provides the readers with the necessary tools in order to recognize and diagnose cardiac amyloidosis early and introduces the recent advances in management that are improving the outcomes of a condition that was considered to be untreatable.

Texture analysis of magnetic resonance T1 mapping with dilated cardiomyopathy: A machine learning approach.

The diagnosis of dilated cardiomyopathy (DCM) remains a challenge in clinical radiology. This study aimed to investigate whether texture analysis (TA) parameters on magnetic resonance T1 mapping can be helpful for the diagnosis of DCM.A total of 50 DCM cases were retrospectively screened and 24 healthy controls were prospectively recruited between March 2015 and July 2017. T1 maps were acquired using the Modified Look-Locker Inversion Recovery (MOLLI) sequence at a 3.0 T MR scanner. The endocardium and epicardium were drawn on the short-axis slices of the T1 maps by an experienced radiologist. Twelve histogram parameters and 5 gray-level co-occurrence matrix (GLCM) features were extracted during the TA. Differences in texture features between DCM patients and healthy controls were evaluated by t test. Support vector machine (SVM) was used to calculate the diagnostic accuracy of those texture parameters.Most histogram features were higher in the DCM group when compared to healthy controls, and 9 of these had significant differences between the DCM group and healthy controls. In terms of GLCM features, energy, correlation, and homogeneity were higher in the DCM group, when compared with healthy controls. In addition, entropy and contrast were lower in the DCM group. Moreover, entropy, contrast, and homogeneity had significant differences between these 2 groups. The diagnostic accuracy when using the SVM classifier with all these histogram and GLCM features was 0.85 ± 0.07.A computer-based TA and machine learning approach of T1 mapping can provide an objective tool for the diagnosis of DCM.

Advanced imaging in pulmonary hypertension: emerging techniques and applications.

Pulmonary hypertension (PH) is a pathophysiological disorder defined by an increase in pulmonary arterial pressure which can occur in multiple clinical conditions. Irrespective of etiology, PH entails a negative impact on exercise capacity and quality of life, and is associated with high mortality particularly in pulmonary arterial hypertension. Noninvasive imaging techniques play an important role in suggesting the presence of PH, providing noninvasive pulmonary pressure measurements, classifying the group of PH, identifying a possibly underlying disease, providing prognostic information and assessing response to treatment. While echocardiography, computed tomography (CT) and ventilation/perfusion scans are an integral part of routine work-up of patients with suspected PH according to current guidelines and across centers, innovative new techniques and applications in the field of PH such as 3D echocardiography, dual-energy CT, 4D flow magnetic resonance imaging (MRI), T1 and extracellular volume fraction mapping, non-contrast-enhanced MRI sequences for perfusion and ventilation assessment, and molecular-targeted positron emission tomography are emerging. This review discusses advanced and emerging imaging techniques in diagnosis, prognostic evaluation and follow-up of patients with PH.

T2 mapping in dermatomyositis/polymyositis and correlation with clinical parameters

To explore the T2-mapping signal characteristics of the thigh muscles in patients with dermatomyositis/polymyositis (DM/PM) and to investigate the correlation between thigh muscle T2 values, clinical parameters, and serum creatinine kinase (CK). Forty-two patients with DM/PM proven by diagnostic criteria were enrolled in the study along with 13 healthy control subjects. Both T2-mapping and conventional magnetic resonance imaging (MRI) images were obtained in the thigh musculature of all subjects. The T2 values of thigh muscles were compared between the DM/PM patients and control groups. Thirty-one DM/PM patients were evaluated with manual muscle testing (MMT) and serum CK levels. A Spearman correlation coefficient model was used to correlate the mean T2 values and clinical assessments. The Kruskal-Wallis test and receiver operating characteristic (ROC) curves were also utilised. p-Values <0.05 reflected statistical significance. The T2 value of all oedematous muscles was greater on average than that of the unaffected muscles of the DM/PM patients (p<0.05) and the muscles of healthy volunteers (p<0.05). The T2 value of unaffected muscles in DM/PM patients was also greater than that of the normal muscles in healthy volunteers (p<0.05). The area under the curves (AUCs) for T2 relaxation time values was 0.72 with respective sensitivity and specificity of 72.6% and 65.4%. The mean T2 relaxation time of the 31 patients group and the MMTs (p<0.05) was correlated without serum CK levels (p>0.05). T2 mapping is not only quantitatively used for subclinical muscle involvement in DM/PM, but also be used to demonstrate severity of damaged muscles in DM/PM.

Magnetic resonance T1-mapping evaluates the degree of thyroid destruction in patients with autoimmune thyroiditis

ObjectiveAutoimmune thyroiditis (AIT) is the most common autoimmune thyroid disease. Longitudinal relaxation time mapping (T1-mapping) measured by MRI is a new technique for assessing interstitial fibrosis of some organs, such as heart and liver. This study aimed to evaluate the relationship between T1-mapping value and thyroid function and determine the usefulness of T1-mapping in identifying thyroid destruction in AIT patients.MethodsThis case–control study recruited 57 drug-naïve AIT patients and 17 healthy controls. All participants were given thyroid MRI, and T1-mapping values were measured using a modified look-locker inversion-recovery sequence.ResultsAIT patients had significantly higher thyroid T1-mapping values than the healthy controls (1.077 ± 177 vs 778 ± 82.9 ms; P < 0.01). A significant increase in thyroid T1-mapping values was presented along with the increased severity of thyroid dysfunction (P < 0.01). Correlation analyses showed that increased thyroid T1-mapping values were associated with higher TSH and lower FT3 and FT4 levels (TSH: r = 0.75; FT3: r = −0.47; FT4: r = −0.72; all P < 0.01). Receiver-operating characteristic curve analysis revealed a high diagnostic value of T1-mapping values for the degree of thyroid destruction (area under the curve was 0.95, 95% CI: 0.90–0.99, P < 0.01).ConclusionsAIT patients have higher thyroid T1-mapping values than the healthy controls, and the T1-mapping values increased with the progression of thyroid dysfunction. Thyroid T1-mapping value might be a new index to quantitatively evaluate the degree of thyroid destruction in AIT patients.

Association between patellofemoral congruence and patellofemoral chondropathy in patients with anterior knee pain: A T2 mapping knee MRI study.

In this study, the T2 mapping magnetic resonance imaging technique was used to evaluate early cartilage changes associated with patellofemoral alignment and morphology. Fifty four patients (Study group: 38 females, 16 males) with anterior knee pain and a randomly selected and age-matched 50 controls (Control group; 37 females, 13 males) were compared by two blinded authors in terms of T2 values of the patella medial, lateral facet, and trochlea, Insall-Salvatti index, lateral trochlear inclination angle, patellar tilt angle, sulcus angle, and patella medial and lateral facet lengths. The inter- and intra-observer reliability tests were assessed. The T2 medial patellar facet value, T2 lateral patellar facet value, T2 trochlea value, Visual Analog Scale, tibial tubercle - greater trochanter distance, and patellar tilt angle measure were statistically significantly higher in the study group. Based on our study findings, the T2 mapping magnetic resonance imaging (MRI) technique was found to be reliable test that can be used to diagnose early cartilage damage in patients with anterior knee pain. In patients with anterior knee pain, especially with decreased Insall Salvatti index, low lateral trochlear inclination angle, and higher patellar tilt angle, adding a T2 mapping sequence to the standard knee MRI protocol is recommended to help detect early cartilage damage.

P5639Myocardial extracellular volume assessed by cardiac magnetic resonance T1 mapping as a marker of diastolic function: comparative study of CMR and strain echocardiography

P5639Myocardial extracellular volume assessed by cardiac magnetic resonance T1 mapping as a marker of diastolic function: comparative study of CMR and strain echocardiography

Myocardial Edema and Prognosis in Amyloidosis

BackgroundPrognosis in light-chain (AL) and transthyretin (ATTR) amyloidosis is influenced by cardiac involvement. ATTR amyloidosis has better prognosis than AL amyloidosis despite more amyloid infiltration, suggesting additional mechanisms of damage in AL amyloidosis. ObjectivesThe aim of the study was to assess the presence and prognostic significance of myocardial edema in patients with amyloidosis. MethodsThe study recruited 286 patients: 100 with systemic AL amyloidosis, 163 with cardiac ATTR amyloidosis, 12 with suspected cardiac ATTR amyloidosis (grade 1 on 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid), 11 asymptomatic individuals with amyloidogenic TTR gene mutations, and 30 healthy volunteers. All subjects underwent cardiovascular magnetic resonance with T1 and T2 mapping and 16 underwent endomyocardial biopsy. ResultsMyocardial T2 was increased in amyloidosis with the degree of elevation being highest in untreated AL patients (untreated AL amyloidosis 56.6 ± 5.1 ms; treated AL amyloidosis 53.6 ± 3.9 ms; ATTR amyloidosis 54.2 ± 4.1 ms; each p < 0.01 compared with control subjects: 48.9 ± 2.0 ms). Left ventricular (LV) mass and extracellular volume fraction were higher in ATTR amyloidosis compared with AL amyloidosis while LV ejection fraction was lower (p < 0.001). Histological evidence of edema was present in 87.5% of biopsy samples ranging from 5% to 40% myocardial involvement. Using Cox regression models, myocardial T2 predicted death in AL amyloidosis (hazard ratio: 1.48; 95% confidence interval: 1.20 to 1.82) and remained significant after adjusting for extracellular volume fraction and N-terminal pro–B-type natriuretic peptide (hazard ratio: 1.32; 95% confidence interval: 1.05 to 1.67). ConclusionsMyocardial edema is present in cardiac amyloidosis by histology and cardiovascular magnetic resonance T2 mapping. T2 is higher in untreated AL amyloidosis compared with treated AL and ATTR amyloidosis, and is a predictor of prognosis in AL amyloidosis. This suggests mechanisms additional to amyloid infiltration contributing to mortality in amyloidosis.

Extracellular volume quantitation using dual-energy CT in patients with heart failure: Comparison with 3T cardiac MR

BackgroundsCardiac magnetic resonance (CMR) T1 mapping and the extracellular volume (ECV) have been developed to quantitative analysis of diffusely abnormal myocardial fibrosis (MF). However, dual-energy CT (DECT) has a potential for calculation of ECV. The aim of this study is to evaluate the feasibility and accuracy of DECT technique in determining the ECV in patients with heart failure, with 3T CMR as the reference. MethodsThirty-five patients with various reasons of heart failure were enrolled in this study. Both DECT and CMR exams were completed within 24 h. ECVs were calculated, and the relationship between DECT-ECV, CMR-ECV, and other heart function parameters, including left ventricular end systolic and diastolic volume, cardiac output and ejection fraction (LVESV, LVEDV, CO, LVEF), Brain natriuretic peptide (BNP) was determined. All participants gave informed consent, and the study was approved by the institutional review board. ResultsThe median ECVs on DECT and CMR were 33% (95%CI: 32%–36%) and 30% (95%CI: 30% - 32%), respectively. A good correlation between myocardial ECV at DECT and that at CMR (r = 0.945, P < 0.001) was observed. Bland-Altman analysis between DECT and CMR showed a small bias (2.6%), with 95% limits of agreement of −0.4% and 5.6%. Interobserver agreement for ECV at DECT was excellent (ICC = 0.907). Both ECVs, for DECT and CMR, were inversely associated with LVEF and CO. ConclusionDECT-based ECV could be an alternative non-invasive imaging tool for myocardial tissue characterization. However, overestimation of the extent of diffuse MF is observed with use of DECT.

T1 Mapping by Cardiac Magnetic Resonance and Multidimensional Speckle-Tracking Strain by Echocardiography for the Detection of Acute Cellular Rejection in Cardiac Allograft Recipients

ObjectivesThe aim of this study was to test the hypothesis that echocardiographic strain imaging, by tracking subtle alterations in myocardial function, and cardiac magnetic resonance T1 mapping, by quantifying tissue properties, are useful and complement each other to detect acute cellular rejection in heart transplant recipients. BackgroundNoninvasive alternatives to endomyocardial biopsy are highly desirable to monitor acute cellular rejection. MethodsSurveillance endomyocardial biopsies, catheterizations, and echocardiograms performed serially according to institutional protocol since transplantation were retrospectively reviewed. Sixteen-segment global longitudinal strain (GLS) and circumferential strain were measured before, during, and after the first rejection and at 2 time points for patients without rejection using Velocity Vector Imaging for the first part of the study. The second part, with cardiac magnetic resonance added to the protocol, served to validate previously derived strain cutoffs, examine the progression of strain over time, and to determine the accuracy of strain and T1 measurements to define acute cellular rejection. All tests were performed within 48 h. ResultsMedian time to first rejection (16 grade 1 rejection, 15 grade ≥2 rejection) was 3 months (interquartile range: 3 to 36 months) in 49 patients. GLS and global circumferential strain worsened significantly during grade 1 rejection and ≥2 rejection and were independent predictors of any rejection. In the second part of the study, T1 time ≥1,090 ms, extracellular volume ≥32%, GLS >−14%, and global circumferential strain ≥−24% had 100% sensitivity and 100% negative predictive value to define grade ≥2 rejection with 70%, 63%, 55%, and 35% positive predictive values, respectively. The combination of GLS >−16% and T1 time ≥1,060 ms defined grade 1 rejection with 91% sensitivity and 92% negative predictive value. After successful treatment, T1 times decreased significantly. ConclusionsT1 mapping and echocardiographic GLS can serve to guide endomyocardial biopsy selectively.

Diffuse cardiac fibrosis quantification in early systemic sclerosis by magnetic resonance imaging and correlation with skin fibrosis.

To evaluate the utility of cardiac magnetic resonance (CMR) T1 mapping in early systemic sclerosis (SSc) and its association with skin score. Twenty-four consecutive patients with early SSc referred for cardiovascular evaluation and 12 controls without SSc were evaluated. All patients underwent cine, T1 mapping, and late gadolinium enhanced (LGE) CMR imaging. T1 mapping indices were compared between SSc patients and controls (extracellular volume fraction [ECV], gadolinium partition coefficient [λ], pre-contrast T1, and post-contrast T1). The association between T1 mapping parameters and the modified Rodnan skin score (mRSS) was determined. There were no significant differences in cardiac structure/function between SSc patients and controls on cine imaging, and 8/24 (33%) SSc patients had evidence of LGE (i.e., focal myocardial fibrosis). Of the T1 mapping parameters (indices indicative of diffuse myocardial fibrosis), ECV differentiated SSc patients from controls the best, followed by λ, even when the eight SSc patients with LGE were excluded. ECV had a sensitivity and specificity of 75% and 75% for diffuse myocardial fibrosis (optimal abnormal cut-off value of >27% [area under ROC curve=0.85]). In the 16 patients without evidence of LGE, each of the 4 CMR T1 mapping parameters (ECV, λ, Pre-T1 and Post-T1) correlated with mRSS (R=0.51-0.65, P=0.007-0.043), indicating a correlation between SSc cardiac and skin fibrosis. The four T1 mapping indices are significantly correlated with mRSS in patients with early SSc. Quantification of diffuse myocardial fibrosis using ECV should be considered as a marker for cardiac involvement in SSc clinical studies.

Impact of Systemic Volume Status on Cardiac Magnetic Resonance T1 Mapping

Diffuse myocardial fibrosis is a key pathophysiologic feature in heart failure and can be quantified by cardiac magnetic resonance (CMR) T1 mapping. However, increases in myocardial free water also prolong native T1 times and may impact fibrosis quantification. Thus far, the impact of systemic patient volume status remains unclear. In this study, native T1 time by CMR was investigated in hemodialysis (HD) patients (n = 37) and compared with healthy controls (n = 35). Volume status was quantified by bioimpedance spectroscopy and correlated with CMR T1 time. While no differences between HD patients and controls were present with regard to age (p = 0.180), height (p = 0.535), weight (p = 0.559) and left ventricular (LV) ejection fraction (p = 0.273), cardiac size was significantly larger in HD patients (LV end-diastolic volume 164 ± 53 vs. 132 ± 26 ml, p = 0.002). Fluid overloaded HD patients had significantly longer native T1 times than normovolemic HD patients and healthy controls (1,042 ± 46 vs. 1,005 ± 49 vs. 998 ± 47 ms, p = 0.030). By regression analysis, T1 time was significantly associated with fluid status (r = 0.530, p = 0.009, post-HD fluid status). Our data strongly indicate that native CMR T1 time is significantly influenced by systemic volume status. As fluid overload is common in patients with cardiovascular diseases, this finding is important and requires further study.

IMPACT OF MYOCARDIAL EXTRACELLULAR VOLUME ASSESSED BY CARDIAC MAGNETIC RESONANCE T1 MAPPING ON SYSTOLIC AND DIASTOLIC FUNCTION OF THE HEART

Extracellular volume (ECV) derived cardiac magnetic resonance (CMR) T1-mapping has emerged as a non-invasive method to quantify extracellular matrix of human heart. The aim of this study was to assess the impact of ECV assessed by CMR T1 mapping on systolic and diastolic function of the heart