Importance of cardiac magnetic resonance imaging in cardiomyopathies in present scenario

Ashok Kumar Sharma

doi:10.4103/sujhs.sujhs_33_22

REVIEW ARTICLE

Year : 2022 | Volume : 8 | Issue : 2 | Page : 99-107

Importance of cardiac magnetic resonance imaging in cardiomyopathies in present scenario

Ashok Kumar Sharma
Department of Radio-Diagnosis and Imaging Santosh Medical College and Hospital (Santosh Deemed To Be University), Noida, Uttar Pradesh, India

Date of Submission	14-Nov-2022
Date of Decision	24-Nov-2022
Date of Acceptance	24-Nov-2022
Date of Web Publication	11-Jan-2023

Correspondence Address:
Ashok Kumar Sharma
C10, Kendriya Vihar, Sector 51, Noida, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sujhs.sujhs_33_22

Abstract

Cardiomyopathy includes a heterogeneous group of diseases and conditions that are caused by mechanical and/or electrical dysfunction and shows inappropriate hypertrophy or dilatation which may be due to various causes, mostly genetic, can be confined only to heart or may be a part of systemic disorders. It includes hypertrophic, dilated, arrhythmogenic right ventricular cardiomyopathy, restrictive, and unclassified type. Cardiac magnetic resonance imaging (C-MRI) is currently the gold standard examination due to its high temporal and spatial resolution. In late gadolinium enhancement (LGE) studies, the gadolinium contrast which is administered, it has a slower washout rate in abnormal areas of increased extracellular space and fibrosis. The normal myocardium gets nulled and the abnormal areas are seen as bright areas on LGE. According to the Global Burden of Diseases, injuries, and risk factors study 2016, cardiomyopathy contributed to 0.12% of total deaths, 0.11% of total disability-adjusted life years in India. The main objective of the article is to review the role of MRI in cardiomyopathies (CMPs), especially after post-COVID-19 pandemic with the purpose whether this can be one shop modality with reference to echocardiography. With the advancement in MRI technology and availability of state of art cardiac coils and cardiac software C-MRI has emerged as modality of choice in diagnosis as well as in follow-up cases of CMPs diseases as it is nonoperator dependent as well as radiation-free modality.

Keywords: Cardiac, cardiomyopathies, magnetic resonance imaging

How to cite this article:
Sharma AK. Importance of cardiac magnetic resonance imaging in cardiomyopathies in present scenario. Santosh Univ J Health Sci 2022;8:99-107

How to cite this URL:
Sharma AK. Importance of cardiac magnetic resonance imaging in cardiomyopathies in present scenario. Santosh Univ J Health Sci [serial online] 2022 [cited 2023 May 30];8:99-107. Available from: http://www.sujhs.org/text.asp?2022/8/2/99/367568

Introduction

Cardiomyopathies (CMPs) are myocardial diseases associated with cardiac dysfunction. They are classified as dilated CMP, hypertrophic CMP, restrictive CMP, arrhythmogenic right ventricular (RV) CMP, specific CMP, post-COVID-19 CMP, and nonclassified CMP.^[1]

Cardiac magnetic resonance imaging (C-MRI) has become an important imaging technique for the diagnosis and follow-up of CMP. In fact, echocardiography, usually the first step in CMP evaluation, has some pitfalls, mainly its limited acoustic window and is operator dependent. On the contrary, C-MRI allows a reproducible and accurate evaluation of myocardial morphology, function, perfusion, and tissue damage in a noninvasive and “one-stop shop” way. Hence, C-MRI has become an important diagnostic tool for CMP and is the new reference standard for the assessment of cardiac function. C-MRI has become main diagnostic tool in the pre- and posttherapy evaluation of hypertrophic and dilated CMPs, the differential diagnosis between restrictive CMP and constrictive pericarditis, the assessment of myocardial damage in acute and chronic CMP, and the evaluation of myocardial involvement in systemic diseases such as amyloidosis and sarcoidosis. Black blood imaging is the first step in a C-MRI evaluation because it allows reliable assessment of morphology as a result of its high spatial resolution and soft-tissue contrast. Cine imaging is important in the evaluation of cardiac volumes and kinesis and is now considered the reference standard for the assessment of cardiac function. Transvalvular flow can be studied by means of phase-contrast sequences. Late-enhancement imaging is performed after the intravenous administration of gadolinium and is fundamental in the characterization of myocardial tissue abnormalities in CMP.^[1]

Cardiac Magnetic Resonance Imaging Protocol

Patients of all age groups suspected of cardiomyopathy on echocardiography or clinical grounds can be evaluated with C-MRI. Patients with contraindications to magnetic resonance (MR) contrast, on compatible metallic valvular replacement, devices internal cardiac pacemaker, implantable cardiac defibrillator cochlear and ocular implants, electrically programmed drug infusion pumps, metallic foreign body patient not able to hold breath (debilitated patients), and deranged renal function are avoided.^[2]

The procedure is to be explained to the patient and informed written consent in vernacular language is to be obtained in every case.

Description of complete procedure, patients were asked to remove all jewelry, hairpins, watch, belts. Patients were not allowed to carry any coins, knives, keys, nail cutter, pen/pencil, spoon, scissor, and ATM card, mobile in the MR scanner. Patients with cardiac pacemaker, prosthetic, hearing device, or any metallic implant were strictly not allowed in the MR room. The studies conducted using Philips 1.5 T and 3T Ingenia MRI system.

Sedation/anesthesia is needed for young children below 7–10 years.

Patient positioning and coil placement: Patient needs to lie supine in the gantry. Multielement.

Phased array coils with parallel imaging capabilities are preferred coils. Coil selection.

Depends on the patient size, clinical indication and the desired field of view. Electrocardiogram (ECG) electrodes placement as per standard protocol.

BB_SSh_BH (black blood single shot haste breath hold): Axial stack
Steady-state-free precession (SSFP) cine: Axial, coronal, and sagittal stack
SSFP cine: Vertical long axis
SSFP cine: Horizontal long axis
SSFP cine: Short axis (SA)-localizer
SSFP cine: 4 chamber (4C)
SSFP cine: 2 chamber (2C)
SSFP cine: SA-View
SSFP cine: LVOT-left ventricular (LV) outflow tract
Look Locker: SA
T1 MAPPING: MOLLI: SA
T2 MAPPING- GRASE: SA
T2/STIR: SA
PSIR-late gadolinium enhancement (LGE) sequence: SA, chamber view (2CV) and 4CV: Breath-hold: BB-Axial: SSFP-Axial
TR (ms): 2000: 2.8
TE (ms): 39: 1.4
Flip angle (degree): 90: 45
Field of view (mm²): 300 × 300 × 131: 350 × 350 × 120
Acquisition matrix: 152 × 120: 164 × 190
Slice thickness (mm): 8: 8
In-phase resolution (mm²): 2 × 2.5: 2.15 × 1.72
Parallel imaging factor: 2: 2
Number of signal averages: 1: 1
Acquisition time (min): 0.45: 1.07 Table 3: Contrast parameters
Contrast: Gadopentetate DTPA Dimeglumine
Brand name: Magnascan
Dose: 0.2 mmol/kg body weight
Flow rate: 3 ml/s
Volume of saline chaser: 15–20 ml

Late gadolinium enhancement technical parameters

TR (ms): 6.1
TE (ms): 3
FLIP ANGLE (degree): 25
FOV (mm²): 300 mm × 300 mm × 120 mm
Acquisition matrix: 188 × 396
Slice thickness (mm): 10
NSA: 1

Image interpretation

Philips MR software and MR cardiac analysis clinical application were used to view and analyze the MRIs.

Morphological assessment by white blood gradient (turbo fast echo) sequence with cine acquisition (in SA, 2 chambers and 4 chamber planes) was done for the assessment of anatomical features of the heart (pericardium, myocardium cardiac chamber dimensions, papillary muscle, valves, and large vessels)
Cine images were obtained for each sequence to assess cardiac function and motion during the cardiac cycle
Delineation of the endocardial and epicardial contours of the left ventricle was done. Functional assessment of the left ventricle (ejection fraction (EF), end-systolic volume, and end-diastolic volume) was obtained. The RV EF was also assessed
For segmental wall motion analysis, the regional function was assessed, either qualitatively (described as: normal; hypokinetic, akinetic, and dyskinetic) or quantitatively (relative or absolute wall thickening)
LGE was used for scar assessment (nonviable tissue) as enhanced areas in the myocardium.

Viability assessment in cases of ischemic cardiomyopathy

For viability analysis, a visual assessment of the presence of scar tissue (seen as enhanced areas in LGE-C-MRIs) and its extent across the myocardial wall was performed. Myocardial segments showing abnormal enhancement are named and localized according to the 17 segments model of the American Heart Association 30 [Figure 1].

Figure 1: Restrictive cardiomyopathy. CMR images of a 29-year-old male. From left, 4CH view (a) shows biatrial enlargement; (b) Concentric hypertrophy at apex; (c) 2CH image shows a black linear jet s/o mitral regurgitation (blue arrow); (c) LGE shows no enhancement; (d) increased T2 values at the anterior wall of LV; (e) LV volumetry showing reduced EDV and ejection fraction-s/o restrictive cardiomyopathy. CMR: Cardiac magnetic resonance, LV: Left ventricular, LGE: Late gadolinium enhancement

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Scoring system for myocardial viability

SCORE: CMR

No enhancement
Enhancement <50% of wall thickness
Enhancement ≥50% of wall thickness
Transmural enhancement.^[3]

Calculation of fibrosis percentage

Calculation of fibrosis percentage can be done by the estimation of the LGE enhancement areas in all the segments. A semi-quantitative method was used in which manual tracing of contours of the enhanced area was done.

These are the following steps that can depict the same:

Select SSFP cine-LGE sequence and start cardiac analysis
All the LV and RV contours have to be imported onto the LGE images
Select a threshold method based on standard deviation or full width half maximum
Manually trace the areas of LGE
View results. (A table is displayed which shows enhanced area percentage and enhanced LV mass).

T1 and T2 mapping.

Native T1 mapping (normal control values up to 1300 ms); T2 mapping (normal control values - up to 50 ms)
Put an ROI in the native T1 and T2 map in the myocardium.

Dilated Cardiomyopathy

Dilated CMP is associated with dilatation and dysfunction of the LV or both ventricles. Ventricles can have normal or thin walls but always have increased cavitary volumes and low EFs. Atrial dilatation and valvular dysfunction may be associated.

The clinical presentation of dilated CMP is usually characterized by progressive cardiac failure, and the long-term prognosis is poor.^[3] The cause is not well understood and, although a number of cases are considered to be idiopathic, it is now recognized that other cases of the disease may have ischemic, genetic or familial, viral, immune, or a toxic origin, or can be secondary to cardiovascular diseases with myocardial dysfunction that is not explained by ischemic damage or increased volumetric loads.^[4],[5]

In black blood images, enlarged cardiac chambers and thin myocardial walls are evident. Cine images usually show LV hypokinesia and increased volumes. Roughly, the end-diastolic volumes that constitute a dilated CMP are more than 140 mL for the LV and more than 150 mL for the RV; these data may be more accurate if indexed to the body surface area. Phase-contrast sequences may show impaired diastolic function of one or both ventricles. In particular, the transvalvular flow may be characterized by a restrictive pattern, with a narrow blood inflow jet in early diastole and an early peak–atrial peak ratio >2, or by an early peak–atrial peak ratio <1, due to the early diastolic filling decrease and compensatory atrial contraction.^[6]

A C-MRI study in dilated CMP should always include late-enhancement images, which are an important element in tissue characterization and can help differentiate between dilated CMP secondary to coronary artery disease and other causes of dilated CMP. Forty-one percent of patients with dilated CMP showed late-enhancement areas in the myocardial walls. This 41% consisted of 13% with a pattern (subendocardial and transmural) that cannot be distinguished from the typical ischemic pattern, and 28% with a mesocardial distribution of late-enhancement areas; therefore, the differentiation between these subgroups may be fundamental in the therapeutic and prognostic approach to the patients. the role of late-enhancement imaging in the assessment of heart failure secondary to biopsy-proven chronic myocarditis; the possible persistence of autoimmune inflammatory processes may give rise to typical late-enhancement patterns, which again are useful in the diagnostic, therapeutic, and prognostic management of patients with chronic myocarditis that may evolve toward dilated CMP.^[7]

C-MRI with late-enhancement sequences seems to have a role also in the evaluation of the degree of fibrosis and of the prognostic significance of the fibrosis itself in patients with dilated CMP. Testing the hypothesis that fibrosis in dilated CMP might predict outcome used C-MRI—in particular, late-enhancement imaging—to study a group of patients with dilated CMP and found that 35% of these patients had midwall myocardial fibrosis, which is a predictor of the combined end point of all-cause mortality and cardiovascular hospitalization, and also of sudden cardiac death and ventricular tachycardia. These results perhaps suggest that C-MRI has a potential role in the risk stratification of patients with dilated CMP [Figure 2]a, [Figure 2]b, [Figure 2]c.

Figure 2: Dilated cardiomyopathy-likely nonischemic. CMR images of a 21-year-old male patient. From left (a) 4 chamber view shows dilated cardiac champers; (b) T2/STIR image showing hyper intensity in LV myocardium (white arrow); (c) LGE image- Short axis and 4CH shows subepicardial enhancement in the septum (blue arrows); (e) LV volumetry reveals severely reduced ejection fraction values. Dilated cardiomyopathy likely nonischemic. CMR: Cardiac magnetic resonance, LV: Left ventricular, LGE: Late gadolinium enhancement

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Hypertrophic Cardiomyopathy

The main feature of hypertrophic CMP is LV wall thickening, more often asymmetric and involving the interventricular septum.^[4] A marker of hypertrophic CMP may be LV outflow tract obliteration, with the occurrence of systolic gradients (obstructive form) [Figure 3]a, [Figure 3]b, [Figure 3]c, [Figure 3]d, [Figure 3]e. LV EF can be normal or increased, whereas cavitary volumes can be normal or reduced. Diastolic function may also be impaired because of the altered ventricular compliance. Valve insufficiency may coexist. In most cases, the cause of hypertrophic CMP is genetic or familial, with a 50% autosomal-dominant hereditary pattern, even if with variable expression.^[8] Patients are usually asymptomatic or mildly symptomatic, even if sudden death is a possibility.^[6]

Figure 3: Diagnosis: Asymmetric septal hypertrophic cardiomyopathy. CMR images of a 44-year-old male patient presenting with palpitations and syncope. From left (a) short axis shows asymmerrical thickening of sptal wall in base and mid region (b) Rest perfusion image showing hypo intensity s/o perfusion image defect n subendocardial location in inferoseptal wall (white arrow); (c) and (d) LGE images short axis and 4CH shows min myocardial enhancement (green arrows); (e) T1 mapping reveals elevated values in the LV myocardium. Diagnosis: Asymmetric septal hypertrophic cardiomyopathy. CMR: Cardiac magnetic resonance, LV: Left ventricular, LGE: Late gadolinium enhancement

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In black blood images, increased LV wall thickness is usually evident. Cine imaging allows the assessment of LV systolic function, which can be increased with reduced volumes, and the evaluation of outflow tract obstruction. Impaired diastolic function is well investigated using phase-contrast sequences. In particular, the evaluation of transvalvular flow may depict decreased LV compliance, with a narrow blood inflow jet in early diastole and an early peak–atrial peak ratio >2.^[6]

The myocardium in patients with hypertrophic CMP is histologically characterized by fibrotic scars and signs of myocardial micro ischemia. These phenomena have a correlation with C-MRI because they are seen in the late-enhancement areas, the extent of which is associated with the progression and seriousness of the disease; and an increased risk of sudden death exists because myocardial scarring can be the substrate for fatal arrhythmia.^[2],[3] Therefore, late-enhancement imaging may have a fundamental role in risk stratification in patients with hypertrophic CMP, which has important prognostic and therapeutic implications^[6] [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d, [Figure 1]e, [Figure 1]f.

Restrictive cardiomyopathy

Restrictive CMP is characterized by reduced ventricular filling and diastolic volume, leading to atrial dilatation and venous stasis, usually with preserved systolic function.^[4] Restrictive CMP may be idiopathic, secondary to infiltrative and storage diseases (such as amyloidosis and sarcoidosis), or associated with myocardial disorders such as hypereosinophilic syndrome.^[6] Morphologic images in restrictive CMP may show atrial enlargement. The RV may also enlarge if pulmonary hypertension coexists. Cine images allow assessment of the altered diastolic ventricular filling. Restrictive CMP is characterized by a restrictive diastolic filling pattern, with a narrow blood inflow jet in early diastole and an early peak–atrial peak ratio >2.^[6] Systolic function of the LV is either preserved or reduced. C-MRI is a fundamental diagnostic tool because it helps in the differentiation between restrictive CMP and constrictive pericarditis, which have different therapeutic approaches. Although reduced ventricular filling and diastolic volumes may be features of both diseases, pericardial thickening (>4 mm) is typical of constrictive pericarditis. Pericardial thickening can be assessed with morphologic T2-weighted black blood images; unfortunately, the pericardium may be only minimally thickened or even normal in patients with constrictive pericarditis. New C-MRI techniques have been implemented for the evaluation of dubious cases, such as cine MRI assessment of diastolic ventricular septal movements and real-time cine MRI evaluation of septal motion during respiration. These techniques show that in restrictive CMP, septal convexity is maintained in all respiratory phases, whereas in constrictive pericarditis, septal flattening can be observed in early inspiration. To the best our knowledge, the issue of the late-enhancement patterns in idiopathic restrictive CMP has not been specifically addressed in the literature, although the late-enhancement patterns in secondary restrictive CMP have been and will be described further in this article in the section “Specific Cardiomyopathy” [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d.

Figure 4: Arrhythmogenic right ventricular dysplasia. CMR images of a 40-year-old male patient having arrhythmia. From left short axis axial (a) shows grossly dilated right ventricle with thinned out wall multiple trabeculations (b) T1/STIR image shows patchy areas of hyper intensity s/edema in both ventricular myocardial (yellow arrow); (c) LGE image in 4CH shows right ventricular myocardial enhancement (green arrow); (d) hypo enhancing thrombus in right ventricular cavity (black arrow); (e) raised T2 values (f) RV volumetry reveals severely reduced ejection fraction of right ventricle; (g) normal LV funcyion. Diagnosis: Arrhythomogenic right ventricular dysplasia. CMR: Cardiac magnetic resonance, LV: Left ventricular, LGE: Late gadolinium enhancement, RV: Right ventricular

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Arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic RV CMP is characterized by progressive fibrous or fibrofatty replacement of the myocytes of the RV walls, which can extend to the entire RV and also to the LV. The pathogenesis and cause of the disease are still unclear, but many studies have been implemented and four main hypotheses are now considered: myocyte apoptosis followed by fibro-fatty replacement, dysontogenesis and subsequent abnormal RV development, degenerative RV disorders with metabolic causes, and RV myocyte inflammation with fibrofatty replacement seen as a healing process after myocarditis. The familial form of the disease is fairly common, with either autosomal dominant or recessive inheritance. The clinical manifestations of arrhythmogenic RV CMP may vary but usually include ventricular tachycardia with left bundle-branch block, which can lead to sudden death.^[6] Therefore, the diagnosis of arrhythmogenic RV CMP is fundamental, and C-MRI is now considered an important tool for this purpose.^[6] Black blood images with and without fat suppression may show fibrofatty replacement of the RV-free walls, even if this finding is rarely the only abnormality in arrhythmogenic RV CMP. Black blood images have recently been considered less sensitive for the diagnosis of this disease than the detection of the RV systolic and diastolic dysfunction. Moreover, the estimation of RV dysfunction should be both qualitative and quantitative.^[6] Cine images usually show augmented RV volumes (end-diastolic volume >150 mL and end-systolic volume >70 mL). These data may be more accurate if indexed to the body surface area.^[6] Systolic bulging or even gross dyskinesia and aneurysms of the RV free wall and outflow tract may be present, leading to an EF <45% [Figure 5]a, [Figure 5]b, [Figure 5]c. In our experience, late-enhancement imaging is not always significant because RV walls in patients with arrhythmogenic RV CMP can be very thin; however, there is not agreement on this topic in the literature.

Figure 5: (a) Cardiac amyloidosis. Four-chamber steady-state free precession image of 64-old-man with cardiac amyloidosis shows diffuse thickening of myocardium and mild atrial enlargement; (b) 61-year-old man with cardiac amyloidosis. Short-axis views from postgadolinium delayed enhancement images show widespread enhancement

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Specific Cardiomyopathy

Specific CMP is a large group of diseases associated with cardiac or systemic disorders.^[4]

Our attention focuses on amyloidosis, sarcoidosis, Anderson–Fabry disease (FD), and COVID-19 pandemic.

Amyloidosis

Amyloidosis represents the extra-cellular deposition of insoluble fibrillar proteinaceous material in various organs and tissues in a variety of clinical settings. Cardiac involvement is seen with most forms of amyloidosis, although it is most common and most often clinically significant with type AL amyloidosis (primary amyloidosis), often associated with multiple myeloma or other monoclonal gammopathies.^[1],[4] Amyloidosis is the most common cause of restrictive cardiomyopathy (RCM) outside the tropics. Cardiac injury occurs due to the widespread interstitial deposition of proteinaceous material throughout the myocardium that causes pressure atrophy of adjacent myocardial fibers. Intramural deposition within coronary arteries leads to vessel wall thickening, luminal narrowing, and potentially arterial occlusion. Over time, these changes result in ventricular (and atrial) wall thickening and reduced ventricular wall compliance, impairment of diastolic filling, and eventual diastolic heart failure.^[4]

Differentiation of amyloidosis from other forms of RCM, such as hypertrophic cardiomyopathy, sarcoidosis, or infiltrative lymphoma, is important for selection of appropriate treatment options. MR appearances of restrictive CMPs as a group have been well documented. Findings are similar to those of echocardiography including concentric thickening of the LV wall, reduced systolic function with diminished EF, restriction of diastolic filling, and enlargement of atria without associated ventricular enlargement. The reduced EF is often useful to differentiate restrictive CMPs from hypertrophic CMPs, which often are associated with a normal or even increased EF. Descriptions in the literature of more specific MRI features related to cardiac amyloid infiltration are limited. The most common observation has been a diffuse decrease in signal intensity on T1- and T2-weighted images, although this often needs to be formally measured in a region of interest and may not be apparent on simple viewing of images. Patchy areas of enhancement in the myocardium after IV gadolinium administration have also been described. The late-enhancement pattern seems to be specific for this disorder and is characterized by a diffuse, heterogeneous subendocardial distribution that may resemble an incorrect myocardial signal suppression due to an inappropriate TI choice^[5],[9] [Figure 6]a, [Figure 6]b, [Figure 6]c.

Figure 6: Features were consistent with sarcoidosis (also in view of raised ACE levels). CMR images of a 49-year-old female. From left 4CH views (a) shows biatrial enlargement; (b) septal hypertrophy; (c) T2/STIR image depicating the hyper intensity in lateral wall (yellow arrow); (d) patchy subepicardial enhancement in the anteroseptal wall; (e) T1W post contrast MR brain of the same patient shows optic neuritis (red arrow) and dura arachnoid thickening (blue arrow) - Features were consistent with sarcoidosis (also in view of raised ACE levels). MR: Magnetic resonance. ACE: Angiotensin converting enzyme

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Sarcoidosis is a systemic granulomatous disease that can involve the heart with noncaseating granulomatous infiltration. Cardiac involvement is one of the main factors determining the prognosis, even if cardiac symptoms are experienced by only approximately 5% of subjects with the disorder.^[2]

At black blood imaging, myocardial thickening may be present and may resemble hypertrophic CMP. Diffuse and focal sarcoid infiltrates may lead to hyperintensity on T2-weighted fat-saturated or STIR images because of myocardial edema. On cine images, LV-altered filling patterns may be seen and may be consistent with secondary restrictive CMP. Moreover, contraction abnormalities are a frequent finding, with a segmental distribution that often overlaps the late-enhancement areas. These findings suggest that in cardiac sarcoidosis, late-enhancement areas may also represent fibrotic replacement of the myocardium. The late-enhancement areas seem to have specific locations (basal interventricular septum, lateral LV wall) and distribution patterns (patchy or with striae that do not involve the subendocardium; diffuse and transmural if the disease is advanced), which can help in the differentiation between cardiac sarcoidosis and postischemic myocardial injury.^[2] [Figure 7]a, [Figure 7]b, [Figure 7]c Cardiac involvement in sarcoidosis results in substantial mortality, accounting for up to 50% of all deaths from this condition, predominantly from ventricular tachyarrhythmia. The presence of LGE with C-MRI is a very powerful risk factor for sudden cardiac death. Given the focal nature of the disease, the utility of endomyocardial biopsy is limited. The LGE pattern in this case was classic for cardiac sarcoidosis and the patient was successfully treated with implantable cardioverter defibrillator placement and was doing well at 6-month follow-up.

Figure 7: Mixed apical hypetropic cardiomyopathy. CMR images of a 60-year-old female. From left short axis axial (a) shows asymmetrical septal hypetrophy at basal level (yellow arrow; (b) concentric hypetrophy at apex; (c) LGE image short axis shows patchy subepiccardial enhancement in anteroseptal region (blue arrow); (d) With complete obliteration in systole (white arrow); (e) raised T1 values; (f) LV volumetry showing normal ejection fraction; (g) table showing enhancement percentage - s/o mixed apical hypertrophic cardiomyopathy. CMR: Cardiac magnetic resonance, LV: Left ventricular, LGE: Late gadolinium enhancement

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Anderson-Fabry Disease

The prevalence of clinical signs is LV-hypertrophy (LVH), proteinuria, abnormal audiogram, neuropathic pain, angiokeratoma, gastrointestinal symptom, fatigue, hypohydrosis, chest pain/palpitation, dysmorphic face, abnormal renal function, ankle swelling, self-reported hearing loss, tinnitus, end-stage renal failure, heart valve abnormalities, IA or CVA, lymphedema.

Anderson-FD disease is a rare X-linked disorder caused by different mutations in the Galactosidase α (GLA) gene, which leads to α-galactosidase A enzyme deficiency and the storage of glycosphingolipids in different kinds of organs, included the heart. This results in myocardial inflammation and LVH and fibrosis. Echocardiography and C-MRI, in particular with new techniques, such as mapping analysis, LGE assessment, and strain imaging, are important tools that allow a correct diagnosis, discriminating FD from other hypertrophic heart conditions. C-MRI is able to detect tissue alterations in the early stages of the disease, when an appropriate treatment could be more effective, and it has a fundamental role in monitoring therapy.^[10] CMR is the gold standard for assessing myocardial involvement in FD and providing important information in a noninvasive and reproducible way. Moreover, it is able to differentiate this condition from other heart diseases, thus avoiding misdiagnosis. Since their strong correlation with echocardiographic features, T1 values measurement and perfusion mapping allow the detection of early myocardial involvement before the occurrence of LVH and myocardial fibrosis, when ERT may show the greatest effectiveness [Figure 8].

Figure 8: In a post -COVID infection patient with ECG changes, present cardiac MRI reveals. (a) Raised T2 signal intensity ratio of cardiac muscle (white arrow) compared with skeletal muscle (blue arrow); (b) No LGE enhancement; (c) and (d) Diffusely elevated T1 and T2 mapping values at mid cavity levels–this represents myocardial edema without fibrosis. Possibility of COVID myocarditis was considered. (In view of COVID positive history). ECG: Electrocardiogram, LGE: Late gadolinium enhancement, MRI: Magnetic resonance imaging

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Coronavirus Disease 2019 (COVID-19)

It has been a global outbreak since March 2020. In our study, a case of COVID-related myocarditis was diagnosed. The lung is the major organ involved in COVID-19. Cardiac involvement in myocarditis, including myocardial fibrosis, edema, pericarditis, is associated with adverse events and poor prognosis; it is important to identify such involvement at an early stage for appropriate treatment. Recent MR techniques including T1, T2 mapping, and extracellular volume are unique tools to quantitatively assess myocardial diffuse fibrosis and edema (D2). On cardiac MRI, our case had high T1 and T2 mapping values in the myocardium and also the T2 myocardial signal intensity ratio to skeletal muscle was more than 2. There was no LGE enhancement. Similar finding was seen in a study done by Leutkens JA in the year 2021 that also showed presence of myocardial edema (elevated T1 and T2 values) in most COVID related myocarditis cases. Furthermore, the presence of LGE-positive segments was less in COVID myocarditis compared to other non-COVID-related myocarditis.^{[8],[11],[12]}

Comparison of Echocardiography and Cardiac Magnetic Resonance Imaging

C-MRI could additionally detect 20% more cases than echocardiography. As observed in our study, C-MRI has certain advantages over echocardiography including wider field of view, accurate assessment of functional parameters and tissue characterization.

Conclusion

MRI provides comprehensive reporting of both morphological and functional details in patients with cardiomyopathy. They are better than echocardiography in providing more detailed reporting which is both objective and reproducible.

The unique ability of cardiac MRI lies in detection and quantification of scar and fibrosis using the delayed enhancement technique, which can act as an independent predicting factor for prognosis and risk stratification.

MRI is able to establish the definite diagnosis of specific RCM subtypes which is not feasible in echocardiography due to its inherent poor tissue characterization and limited assessment of the ventricular apex and the right ventricle.

MRI has an edge over echocardiography in cases when echocardiography is suboptimal or unsatisfactory, such as in the evaluation of abnormal papillary muscle, apical variant, and RV involvement MRI can act as problem-solving tool in cases where echocardiography holds various limitations such as in obese individuals or those with chronic obstructive pulmonary disease having a poor acoustic window.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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