Quantitative assessment of myocardial T2 relaxation times in cardiac amyloidosis

Parametric mapping using cardiovascular magnetic resonance for the differentiation of light chain amyloidosis and transthyretin-related amyloidosis

AIMS

To evaluate different cardiovascular magnetic resonance (CMR) parameters for the differentiation of light chain amyloidosis (AL) and transthyretin-related amyloidosis (ATTR).

METHODS AND RESULTS

In total, 75 patients, 53 with cardiac amyloidosis {20 patients with AL [66 ± 12 years, 14 males (70%)] and 33 patients with ATTR [78 ± 5 years, 28 males (88%)]} were retrospectively analysed regarding CMR parameters such as T1 and T2 mapping, extracellular volume (ECV), late gadolinium enhancement (LGE) distribution patterns, and myocardial strain, and compared to a control cohort with other causes of left ventricular hypertrophy {LVH; 22 patients [53 ± 16 years, 17 males (85%)]}. One-way ANOVA and receiver operating characteristic analysis were used for statistical analysis. ECV was the single best parameter to differentiate between cardiac amyloidosis and controls [area under the curve (AUC): 0.97, 95% confidence intervals (CI): 0.89-0.99, P < 0.0001, cut-off: >30%]. T2 mapping was the best single parameter to differentiate between AL and ATTR amyloidosis (AL: 63 ± 4 ms, ATTR: 58 ± 2 ms, P < 0.001, AUC: 0.86, 95% CI: 0.74-0.94, cut-off: >61 ms). Subendocardial LGE was predominantly observed in AL patients (10/20 [50%] vs. 5/33 [15%]; P = 0.002). Transmural LGE was predominantly observed in ATTR patients (23/33 [70%] vs. 2/20 [10%]; P < 0.001). The diagnostic performance of T2 mapping to differentiate between AL and ATTR amyloidosis was further increased with the inclusion of LGE patterns [AUC: 0.96, 95% CI: (0.86-0.99); P = 0.05].

CONCLUSION

ECV differentiates cardiac amyloidosis from other causes of LVH. T2 mapping combined with LGE differentiates AL from ATTR amyloidosis with high accuracy on a patient level.

The Role of T2 Mapping in Cardiac Amyloidosis

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy divided into two types: light-chain (LA) and transthyretin (ATTR) CA. Cardiac magnetic resonance (CMR) has emerged as an important diagnostic tool in CA. While late gadolinium enhancement (LGE), T1 mapping and extracellular volume (ECV) have a consolidate role in the assessment of CA, T2 mapping has been less often evaluated. We aimed to test the value of T2 mapping in the evaluation of CA. This study recruited 70 patients with CA (51 ATTR, 19 AL). All the subjects underwent 1.5 T CMR with T1 and T2 mapping and cine and LGE imaging. Their QALE scores were evaluated. The myocardial T2 values were significantly (p < 0.001) increased in both types of CA compared to the controls. In the AL-CA group, increased T2 values were associated with a higher QALE score. The myocardial native T1 values and ECV were significantly (p < 0.001) higher in the CA patients than in the healthy subjects. Left ventricular (LV) mass, QALE score and ECV were higher in ATTR amyloidosis compared with AL amyloidosis, while the LV ejection fraction was lower (p < 0.001). These results support the concept of the presence of myocardial edema in CA. Therefore, a CMR evaluation including not only myocardial T1 imaging but also myocardial T2 imaging allows for more comprehensive tissue characterization in CA.

Diagnostic and Prognostic Value of Non-late Gadolinium Enhancement Cardiac Magnetic Resonance Parameters in Cardiac Amyloidosis

Early diagnosis is crucial for the improvement of outcomes of patients with cardiac amyloidosis (CA). Emerging non-late gadolinium enhancement (LGE) based cardiac magnetic resonance (CMR) parameters may facilitate early identification of CA. We sought to investigate the diagnostic and prognostic value of T1, T2 mapping and extracellular volume (ECV) in CA. This single-center prospective analysis included 88 patients with CA, 33 patients with aortic stenosis (AS) and left ventricular hypertrophy (LVH), and 15 healthy controls who completed 3T cardiac MRI at the time of their diagnosis and were assessed with T1, T2 (modified Look-Locker inversion recovery), and ECV mapping of the heart and spleen. Echocardiographic, and biochemical parameters and clinical characteristics and outcomes were collected and analyzed. Of the patients with CA, 71 had light-chain (AL) and 17 had transthyretin (ATTR) amyloidosis. Native T1, native T2 and ECV were significantly higher in patients with CA compared to both patients with LVH-AS (P<0.001) and healthy controls (P<0.001). Good diagnostic accuracy was also demonstrated by measuring the area under the curve (AUC) of the receiver operating characteristic (ROC) curves for native T1 in the region of interest (ROI) (AUC=0.90), native T2 ROI (AUC=0.88), and ECV (AUC=0.90). Furthermore, native T1 ROI, native T2 ROI and ECV, correlated with both NT-proBNP levels and Mayo stage of patients (with AL). Spleen ECV was significantly increased in patients with AL versus ATTR amyloidosis (38.5 vs 30.5; P=0.004) and demonstrated good diagnostic accuracy in differentiating between the two types (AUC=0.79). Native T2 ROI was prognostic of mortality in AL CAwith a HR of 1.97 per 5 ms increase (P=0.001) and remained prognostic after adjustment for age, and Mayo stage. Non-LGE based CMR techniques correlated with established markers of disease and demonstrated good diagnostic accuracy, while native T2 ROI was also prognostic of mortality, thus reinforcing their use in the diagnosis and prognosis of CA.

Slip-Ups in the Diagnosis of Cardiac Amyloidosis: A Case Fatality in Point

This case report illustrates a tragic example of a "missed diagnosis" of amyloid light-chain (AL) amyloidosis with cardiac involvement that led to progressive heart failure and the ultimate death of the patient. It had a rather atypical presentation in terms of cardiac imaging, although there were certain highly suspicious clinical features, cardiac and otherwise. It also illustrates the importance of selecting the most appropriate assays to establish (or rule out) the presence of monoclonal immunoglobulin consistent with AL amyloidosis, which has a poor clinical prognosis, as unfortunately demonstrated in this case.

Quantitative MR relaxation using MR fingerprinting with fractional-order signal evolution

The fractional-order Bloch equations have been shown to describe a wider range of experimental situations involving heterogeneous, porous, or composite materials. This paper introduces a novel dictionary of quantitative MR fingerprinting generated by signal evolution model with fractional-order Bloch equations to describe magnetic resonance (MR) relaxation. Here, the fractional-order relaxation models are implemented into Bloch equations through phase transitions using EPG simulation. In the phantom experiments, the fractional-order analysis showed smaller root mean squared error (T1: RMSE = 5.21%, T2: RMSE=3.75%) using the proposed method compared to using conventional method. Among the in vivo experiments of human brains, the estimated T1 and T2 values (mean ± SD) were 843 ± 46.3 ms and 70 ± 4.7 ms in white matter, 1323 ± 28.5 ms and 95 ± 3.8 ms in gray matter. So the proposed method can provide well extensions of current MR fingerprinting and has shown potential to apply into the phantom experiments and the in vivo applications to approach the standard methods for quantitative imaging.

Cardiac Magnetic Resonance Predicting Outcomes Among Patients at Risk for Cardiac AL Amyloidosis

Introduction: Patients with systemic AL amyloidosis (AL) should be evaluated for cardiac amyloidosis (CA), as prognosis is strongly related to cardiac involvement. We assessed the characteristics of patients referred to cardiac magnetic resonance (CMR) with suspected CA from a cancer center and determine predictors of mortality/heart failure hospitalizations (HFH).

Methods: Forty-four consecutive patients referred for CMR with suspected CA were retrospectively included. Variables collected included cardiac biomarkers, in addition to echocardiographic and CMR variables. Survival analyses were performed to determine which variables were more predictive of mortality and HFH.

Results: Of the 44 patients included, 55% were females. 73% of patients were diagnosed with CA by CMR; 56% of them had an established diagnosis of AL. Patients with CA by CMR had higher native T1, higher extracellular volume (ECV) fraction, higher T2, less negative GLS by Echo, and higher troponin I and B-type natriuretic peptide (BNP). Kaplan-Meier survival analysis revealed that the following were predictive of mortality: an ECV ≥ 0.50 (p = 0.0098), CMR LVEF < 50% (p = 0.0010), T2/ECV ≤ 100 (p = 0.0001), and troponin I > 0.03 (p = 0.0025). In a stepwise conditional Cox logistic regression model, the only variable predictive of a composite of mortality and HFH was ECV (HR: 1.17, 95% CI = 1.02–1.34 p = 0.030).

Conclusion: ECV seems to be an important biomarker that could be a predictor of outcomes in cardiac AL amyloidosis. In combination, CMR and serum cardiac biomarkers might help to establish prognosis in patients with CA.

T2 Relaxation Times at Cardiac MRI in Healthy Adults: A Systematic Review and Meta-Analysis

Background T2 mapping is an important cardiac MRI technique with applications in various conditions. However, a comprehensive evaluation of the T2 literature for normal values is lacking. Purpose To characterize the ranges of normal values and variability of myocardial T2 relaxation times using a systematic review and meta-analysis of the T2 literature. Materials and Methods PubMed and Cochrane Central were searched from June 2019 to January 2020 for myocardial T2 measurements in healthy adults. Studies quantifying T2 relaxation times conducted at 1.5 T or 3.0 T using gradient and spin-echo (GRASE) or T2-prepared balanced steady-state free precession sequences were included. Summary means were generated using a random-effects model. Subgroup analysis and meta-regression were performed to assess factors causing heterogeneity. Results Of the 2481 articles retrieved, 42 studies were included with 954 healthy adults (mean age, 42.4 years ± 10.5 [standard deviation]; 538 men). The pooled mean of T2 across studies was 52 msec at 1.5 T (95% confidence interval [CI]: 51 msec, 53 msec) and 46 msec at 3.0 T (95% CI: 44 msec, 48 msec) (P ≤ .001). I² was 98% at 1.5 T and 3.0 T. Meta-regression at 1.5 T and 3.0 T identified vendor (β at 1.5 T = -4 msec [with Philips as reference], P < .001; β at 3.0 T = -5 msec, P = .02) and pulse sequence (β at 1.5 T = -5 msec [with GRASE as reference], P < .001; β at 3.0 T = -6 msec, P = .002) as significant covariates, but it did not identify any association with covariates of age (β at 1.5 T = 0 msec per year, P = .70; β at 3.0 T = 0 msec per year, P = .83) or sex (β at 1.5 T = -1 msec, P = .88; β at 3.0 T = 6 msec, P = .42). Conclusion The pooled mean of T2 relaxation times in healthy adults had marked heterogeneity across studies with field strength, vendor, and pulse sequence identified as covariates associated with T2. T2-prepared measurements were similar between vendors at each field strength. © RSNA, 2020 Online supplemental material is available for this article.

Quantitative cardiac magnetic resonance T2 imaging offers ability to non-invasively predict acute allograft rejection in children

BACKGROUND

Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection.

METHODS

Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Student's t-tests analysis.

RESULTS

Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001).

CONCLUSIONS

Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children.

Myocardial Edema and Prognosis in Amyloidosis

BACKGROUND

Prognosis 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.

OBJECTIVES

The aim of the study was to assess the presence and prognostic significance of myocardial edema in patients with amyloidosis.

METHODS

The 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.

RESULTS

Myocardial 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).

CONCLUSIONS

Myocardial 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.

The Evolving Role of Cardiovascular Magnetic Resonance Imaging in the Evaluation of Systemic Amyloidosis

Systemic amyloidosis is a serious multiorgan disease with reduced life expectancy, irrespective of type. The impact of magnetic resonance imaging (MRI) in managing this condition has been immense. The last decade in particular has seen a surge of interest in the assessment and evaluation of the heart in patients with systemic amyloidosis by cardiovascular magnetic resonance imaging (CMR), with approximately 85% of all publications on this subject arising in the last 10 years. This has been largely driven by the creation of new sequences and their subsequent modernisation and technical development, thereby rendering previously prohibitive methods clinically more relevant and applicable. In turn, this has led to an increased awareness and recognition of the disease. This review demonstrates how MRI has become a pivotal diagnostic tool in the assessment of cardiac amyloidosis over the last 2 decades, with the ability to track disease and predict mortality. Several different pathognomonic patterns of late gadolinium enhancement (LGE) are now recognised and are able to prognosticate. T1 mapping and extracellular volume (ECV) techniques have resulted in even earlier disease detection before LGE is even visible and along with T2 mapping, provide new insights into biology. As newer therapies also evolve and become available, the need for accurate tracking of cardiac disease response to treatment carries increasing importance. All these are examined in this review, mainly focussing on light-chain (AL) and transthyretin (ATTR) amyloidosis.

Myocardial native T2 measurement to differentiate light-chain and transthyretin cardiac amyloidosis and assess prognosis

BACKGROUND

To assess the diagnostic and prognosis value of myocardial native T2 measurement in the distinction between Light-chain (AL) and Transthyretin (ATTR) cardiac amyloidosis (CA).

METHODS

Forty-four patients with CA (24 AL; 20 ATTR) and 40 healthy subjects underwent 1.5 T cardiovascular magnetic resonance (CMR). They all underwent T1 and T2 mapping (modified Look-Locker inversion recovery), cine and late gadolinium enhancement (LGE) imaging. The Query Amyloid Late Enhancement (QALE) score, myocardial native T2, T1 and extra cellular volume fraction (ECV) were calculated for all patients.

RESULTS

Of the 44 patients, 36 (82%) exhibited enhancement on LGE images. Mean QALE score of AL (7.9 ± 6) and ATTR (10.5 ± 5) patients were similar (p = 0.6). Myocardial native T2 was significantly (p < 0.0001) higher in AL (63.2 ± 4.7 ms) than in ATTR (56.2 ± 3.1 ms) patients, and both higher (p < 0.001) than healthy subjects (51.1 ± 3.1 ms). Myocardial native T2 was highly correlated with myocardial native T1 (Spearman's rho = 0.79; p < 0.001) and exhibited higher diagnostic performance than T1 to separate AL and ATTR patients: the area under curve (AUC) of T2 was 0.94 (95% CI: 0.86-1, p < 0.001) and the AUC of T1 was 0.77 (95% CI: 0.62-0.91, p = 0.03). Myocardial native T2 did not impact overall survival in patients (HR 1.03 (0.94-1.12); p = 0.53) in contrast to ECV that was the best predictor of outcome (HR 1.66 per 0.1 increase in ECV (1.24-2.22); p = 0.0006).

CONCLUSIONS

Myocardial native T2 significantly is increased in CA, especially in AL patients in comparison to ATTR patients. Myocardial native T2 does not impact survival in CA patients in contrast to ECV that was the best predictor of outcome.

TRIAL REGISTRATION

Trial Registration and unique number: CNIL cardio 1778041. Date of registration: 20 December 2012.

Clinical applications of multi-parametric CMR in myocarditis and systemic inflammatory diseases

Cardiac magnetic resonance (CMR) has changed the management of suspected viral myocarditis by providing a ‘positive’ diagnostic test and has lead to new insights into myocardial involvement in systemic inflammatory conditions. In this review we analyse the use of CMR tissue characterisation techniques across the available studies including T2 weighted imaging, early gadolinium enhancement, late gadolinium enhancement, Lake Louise Criteria, T2 mapping, T1 mapping and extracellular volume assessment. We also discuss the use of multiparametric CMR in acute cardiac transplant rejection and a variety of inflammatory conditions such as sarcoidosis, systemic lupus erythrematous, rheumatoid arthritis and systemic sclerosis.

Myocardial T1 and T2 Mapping: Techniques and Clinical Applications

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.

Usefulness of T2 ratio in the diagnosis and prognosis of cardiac amyloidosis using cardiac MR imaging

PURPOSE

To detect if a difference of T2 ratio, defined as the signal intensity (SI) of the myocardium divided by the SI of the skeletal muscle on T2-weigthed cardiac magnetic resonance (CMR) imaging, exists between patients with systemic amyloidosis, by comparison to control subjects. To determine if a relationship exists between T2 ratio and the overall mortality.

MATERIALS AND METHODS

CMR imaging examinations of 73 consecutive patients (48 men, 25 women; mean age, 63 years±15[SD]) with amyloidosis and suspicion of CA and 27 control subjects were retrospectively analyzed after institutional review board approval. Final diagnosis of CA was retained in case of histological confirmation of CA, typical pattern of CA on imaging and/or positivity of ⁹⁹Technetium-hydroxymethylene diphosphonate scintigraphy. Patients were divided in 2 groups according to the presence or the absence of CA. T2 ratios were calculated in patients with and those without CA and in control subjects with using analysis of variance. Prognostic value of T2 ratio was studied with a Kaplan-Meier curve.

RESULTS

Thirty-five patients (51%) had CA and 33 (49%) were free from CA. T2 ratio was lower in patients with CA (1.18±0.29) than in patients without cardiac involvement (1.37±0.35) (P=0.03) and control subjects (1.45±0.24) (P=0.004). A T2 ratio of 1.36 was the best threshold value for predicting CA with a sensitivity of 63% and a specificity of 73%. Kaplan-Meier analysis showed a significant relationship between a shortened overall survival and a T2 ratio<1.36.

CONCLUSION

Patients with CA exhibit lower T2 ratio on CMR imaging by comparison with patients free of CA and control subjects.

Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques

Cardiac magnetic resonance (MR) imaging has grown over the past several decades into a validated, noninvasive diagnostic imaging tool with a pivotal role in cardiac morphologic and functional assessment and tissue characterization. With traditional cardiac MR imaging sequences, assessment of various pathologic conditions ranging from ischemic and nonischemic cardiomyopathy to cardiac involvement in systemic diseases (eg, amyloidosis and sarcoidosis) is possible; however, these sequences are most useful in focal myocardial disease, and image interpretation relies on subjective qualitative analysis of signal intensity. Newer T1 and T2 myocardial mapping techniques offer a quantitative assessment of the myocardium (by using T1 and T2 relaxation times), which can be helpful in focal disease, and demonstrate special utility in the evaluation of diffuse myocardial disease (eg, edema and fibrosis). Altered T1 and T2 relaxation times in disease states can be compared with published ranges of normal relaxation times in healthy patients. In conjunction with traditional cardiac MR imaging sequences, T1 and T2 mapping can limit the interpatient and interstudy variability that are common with qualitative analysis and may provide clinical markers for long-term follow-up.

Noninvasive detection of cardiac involvement in patients with hereditary transthyretin associated amyloidosis using cardiac magnetic resonance imaging: a prospective study

BACKGROUND

Most of the studies that described cardiac amyloidosis using cardiac magnetic resonance (CMR) imaging refer to patients with primary light chain (AL) amyloidosis. The goal of this study was to evaluate cardiac involvement in patients with hereditary transthyretin associated (ATTR) amyloidosis and asymptomatic carriers and its relationships with clinical symptoms and genotype, using CMR imaging.

METHODS AND RESULTS

Fifty-three patients with hereditary ATTR amyloidosis and 14 asymptomatic carriers were included in this study. Morphological, functional and late gadolinium enhancement (LGE) findings were noted on CMR images. A positive LGE suggesting cardiac amyloidosis was detected in 60% of patients. The pattern of LGE was diffuse, focal and circumferential in 32, 26 and 2% of patients, respectively. The inferior basal segment was the most frequently involved (93%) in case of focal involvement. Diffuse pattern was exclusively encountered in patients with cardiac symptoms. Nineteen percent of patients with isolated neurological symptoms and 20% of subjects without left ventricular wall thickening exhibited cardiac abnormalities on CMR.

CONCLUSION

Cardiac involvement can be detected in patients with hereditary ATTR amyloidosis with isolated neurological symptoms and without left ventricular wall thickening, suggesting that CMR could be useful in detecting preclinical cardiac amyloidosis.

Cardiac magnetic resonance imaging of systemic amyloidosis patients with normal left ventricular ejection fraction: An initial study

Objective: The purpose of this study was to find whether Cardiac Magnetic Resonance (CMR) could assess the myocardial interstitium in patients suffering from systemic amyloidosis with normal left ventricular ejection fraction.

Methods: Twenty Six patients in whom systemic amyloidosis was confirmed by kidney biopsy were investigated. Five patients with normal left ventricular ejection fraction were selected. The heart function of the patients was diagnosed by two-dimensional transthoracic echocardiography. The main MR sequences include an inversion recovery prepared echo planar imaging perfusion sequence, inversion recovery TrueFISP sequence (delayed enhancement) and TrueFISP cine sequence for heart function measurement (including ejection fraction (EF), end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and cardiac output (CO)).

Results: Perfusion defects were seen in three patients. In these patients, myocardial enhancement was visible on late gadolinium enhancement images. The enhancement pattern was diffuse in three patients and focal in two patients. Heart dysfunction was mild, as follows: EF normal (range, 56-75%; mean, 69.4%), ESV normal (range, 15.7-30.0; mean, 23.0), EDV decreased (range, 42.1-96.6; mean, 72.7), SV decreased (range, 23.7-68.6; mean, 49.6) and CO normal (range, 2.6-5.9; mean, 3.9). Hematoxylin and eosin stain and Congo red stain demonstrated typical amyloid deposits. Amyloidosis was classified as amyloid light chain by kappa and lambda stain.

Conclusions: Cardiac Magnetic Resonance could detect abnormal myocardial interstitium in systemic amyloidosis patients with normal left ventricular ejection fraction.

MR, CT, and PET imaging in pericardial disease

Although echocardiography remains the standard diagnostic tool for identifying pericardial diseases, procedures with better delineation of morphology and heart function are often required. The pericardium consists of an inner visceral (epicardium) and outer parietal layer (pericardium), which constitute for the pericardial cavity. Pericardial effusion can occur as transudate, exudate, pyopneumopericardium, or hemopericardium. Potential causes are inflammatory processes, that is, pericarditis due to autoimmune or infective reasons, neoplasms, irradiation, or systemic disorders, chronic renal failure, endocrine, or metabolic diseases. Pericardial fat can mimic pericardial effusion. Using various image-acquisition sequences, MRI allows identifying and separating fluid and solid structures. Fast spin-echo T1-weighted sequences with black-blood preparation are favourably used for morphological evaluation. Fast spin-echo T2-weighted sequences, particularly with fat saturation, and short-tau inversion-recovery sequences are useful to visualize oedema and inflammation. For further tissue characterization, delayed inversion-recovery imaging is used. Therefore, image acquisition is performed at 5-20 min subsequent to contrast agent administration, the so-called technique of late gadolinium enhancement. Ventricular volumes and myocardial mass can be assessed accurately by steady-state free-precession sequences, which is required to measure cardiac function and ventricular wall stress. Constrictive pericarditis usually results from chronic inflammatory processes leading to increased stiffness, which impedes the slippage of both pericardial layers and thereby the normal cardiac filling. CT imaging can favourably assess pericardial calcification. Thus, MR and CT imaging allow a comprehensive delineation of the pericardium. Superior to echocardiography, both methods provide a larger field of view and depiction of the complete chest including abnormalities of the surrounding mediastinum and lungs. PET provides unique information on the in vivo metabolism of 18-fluorodeoxyglucose that can be superimposed on CT findings and is useful for identifying inflammatory processes or masses, for example neoplasms. These imaging techniques provide advanced information of anatomy and cardiac function to optimize the pericardial access, for example by the AttachLifter system, for diagnosis and treatment.

Pathophysiology and treatment of systemic amyloidosis

Amyloid is an abnormal extracellular fibrillar protein deposit in the tissues. In humans, more than 25 different proteins can adopt a fibrillar conformation in vivo that results in the pathognomonic tinctorial property of amyloid (that is, green birefringence when an affected tissue specimen is stained with Congo red dye and viewed by microscopy under cross-polarized light). Amyloid deposition is associated with disturbance of organ function and causes a wide variety of clinical syndromes that are classified according to the respective fibril protein precursor. Systemic amyloidosis, in which amyloid deposits are widespread and typically accumulate gradually, continues to be fatal and is responsible for about one in 1,500 deaths per year in the UK. Advances in our understanding of the pathogenesis of systemic amyloidosis have resulted in the identification of new therapeutic targets, and several drugs with novel mechanisms of action are currently under development. Meanwhile, an increased awareness of amyloidosis coupled with enhancements to existing diagnostic techniques and therapeutic strategies have already resulted in better outcomes for patients with the disease.

T2-weighted imaging of the heart--a pictorial review

Spin-Echo techniques in cardiovascular magnetic resonance (CMR) have been used for decades, primarily to image cardiac anatomy. More recently, T2-weighted (T2W) imaging has seen an increased role in CMR protocols, especially in tissue characterization in acute myocardial processes. This article will review current methodologies of cardiac T2W acquisition and their limitations, as well as approach to both semi-quantitative and quantitative analyses. The appearance and utility of T2W imaging in a myriad of pathologic myocardial processes such as acute myocardial infarction, acute viral myocarditis, reversible stress-related cardiomyopathy, hypertrophic cardiomyopathy, and cardiac sarcoidosis, will also be discussed.

Imaging of early modification in cardiomyopathy: the doxorubicin-induced model

Doxorubicin chemotherapy is effective and widely used to treat acute lymphoblastic leukemia. However, its effectiveness is hampered by a wide spectrum of dose-dependent cardiotoxicity including both morphological and functional changes, affecting primarily the myocardium. Non-invasive imaging techniques are used for the diagnosis and monitoring of these cardiotoxic effects. The purpose of this review is to summarize and compare the most common imaging techniques used in early detection and therapeutic monitoring of doxorubicin-induced cardiotoxicity and the suggested mechanisms of such side effects. Imaging techniques using echocardiography including conventional 2D and 3D echocardiography along with MRI sequences including Tagging, Cine, and quantitative MRI in detecting early myocardial damage are also reviewed. As there is a multitude of reported indices and imaging methods to assess particular functional alterations, we limit this review to the most relevant techniques based on their clinical application and their potential to early detection of doxorubicin-induced cardiotoxic effects.

Monitoring systemic amyloidosis using MRI measurements of the extracellular volume fraction

We report the in vivo evaluation, in a murine model, of MRI measurements of the extracellular volume fraction (ECV) for the detection and monitoring of systemic amyloidosis. A new inducible transgenic model was used, with increased production of mouse serum amyloid A protein controlled by oral administration of doxycycline, that causes both the usual hepatic and splenic amyloidosis and also cardiac deposits. ECV was measured in vivo by equilibrium contrast MRI in the heart and liver of 11 amyloidotic and 10 control mice. There was no difference in the cardiac function between groups, but ECV was significantly increased in the heart, mean (standard deviation) 0.20 (0.05) versus 0.14 (0.04), p < 0.005, and liver, 0.27 (0.04) versus 0.15 (0.04), p < 0.0005, of amyloidotic animals and was strongly correlated with the histological amyloid score, myocardium, ρ = 0.67, p < 0.01; liver, ρ = 0.87, p < 0.01. In a further four mice that received human serum amyloid P component (SAP) followed by anti-human SAP antibody, a treatment to eliminate visceral amyloid deposits, ECV in the liver and spleen returned to baseline after therapy (p < 0.01). MRI measurement of ECV is a sensitive marker of amyloid deposits with potential application for early detection and monitoring therapies promoting their clearance.

Prognostic impact of T2-weighted CMR imaging for cardiac amyloidosis

OBJECTIVES

Using cardiac magnetic resonance imaging (MRI) we tested the diagnostic value of various markers for amyloid infiltration.

METHODS

We performed MRI at 1.5 T in 36 consecutive patients with cardiac amyloidosis and 48 healthy volunteers. The protocol included cine imaging, T2-weighted spin echo, T1-weighted spin echo before and early after contrast and late gadolinium enhancement. We compared the frequency of abnormalities and their relation to mortality.

RESULTS

Median follow-up was 31 months. Twenty-three patients died. Mean left ventricular (LV) mass was 205 ± 70 g. LV ejection fraction (EF) was 55 ± 12%. T2 ratio was 1.5 ± 0.4. 33/36 patients had pericardial and 22/36 had pleural effusions. All but two had heterogeneous late enhancement. Surviving patients did not differ from those who had died with regard to gender, LV mass or volume. Surviving patients had a significantly higher LVEF (60.4 ± 9.9% vs. 51.6 ± 11.5%; p = 0.03). The deceased patients had a lower T2 ratio than those who survived (1.38 ± 0.42 vs. 1.76 ± 0.17; p = 0.005). Low T2 was associated with shorter survival (Chi-squared 11.3; p < 0.001). Cox regression analysis confirmed T2 ratio < 1.5 as the only independent predictors for survival.

CONCLUSION

Cardiac amyloidosis is associated with hypointense signal on T2-weighted images. A lower T2 ratio was independently associated with shortened survival.

T2 quantification for improved detection of myocardial edema

BACKGROUND

T2-Weighted (T2W) magnetic resonance imaging (MRI) pulse sequences have been used to detect edema in patients with acute myocardial infarction and differentiate acute from chronic infarction. T2W sequences have suffered from several problems including (i) signal intensity variability caused by phased array coils, (ii) high signal from slow moving ventricular chamber blood that can mimic and mask elevated T2 in sub-endocardial myocardium, (iii) motion artifacts, and (iv) the subjective nature of T2W image interpretation. In this work we demonstrate the advantages of a quantitative T2 mapping technique to accurately and reliably detect regions of edematous myocardial tissue without the limitations of qualitative T2W imaging.

METHODS

Methods of T2 mapping were evaluated on phantoms; the best of these protocols was then optimized for in vivo imaging. The optimized protocol was used to study the spatial, view-dependent, and inter-subject variability and motion sensitivity in healthy subjects. Using the insights gained from this, the utility of T2 mapping was demonstrated in a porcine model of acute myocardial infarction (AMI) and in three patients with AMI.

RESULTS

T2-prepared SSFP demonstrated greater accuracy in estimating the T2 of phantoms than multi-echo turbo spin echo. The T2 of human myocardium was found to be 52.18 +/- 3.4 ms (range: 48.96 ms to 55.67 ms), with variability between subjects unrelated to heart rate. Unlike T2W images, T2 maps did not show any signal variation due to the variable sensitivity of phased array coils and were insensitive to cardiac motion. In the three pigs and three patients with AMI, the T2 of the infarcted region was significantly higher than that of remote myocardium.

CONCLUSION

Quantitative T2 mapping addresses the well-known problems associated with T2W imaging of the heart and offers the potential for increased accuracy in the detection of myocardial edema.