[IRM et myocardite infectieuse]. / IRM et myocardite infectieuse.

Over the past ten years, cardiac MRI has become an indispensable tool for acute myocarditis diagnosis. Under appropriate conditions, cardiac MRI may allow postponement of initial coronary angiography in many instances. The 2020 ESC guidelines give a class I recommendation to its use in the setting of MINOCA for differential diagnosis between acute myocardial infarction, myocarditis, Tako-Tsubo and other cardiac pathologies, in order to improve therapeutic management and follow-up. This article describes the technical characteristics of MRI in myocarditis (Lake Louise diagnostic criteria and criteria based on myocardial tissue mapping), the main differential diagnoses, the prognostic value and addresses the issue of myocarditis in the setting of COVID-19.

[Cardiac MRI: technical considerations]. / Les conditions techniques d'utilisation de l'IRM cardiaque.

Establishing a clinical cardiovascular magnetic resonance imaging (MRI) program needs a dedicated technical surroundings as well as a specific and expert staff. These guidelines based either on proofs or on expert consensus are stated in order to help the physicians to reach or maintain the competence required for clinical use of cardiovascular MRI. After the general safety statements, the guidelines are focused on hardware and software requirements, the MRI sequences and views, the post-acquisition analysis, and the staff. Specific safety concerns are then approached, more particularly stress testing MRI.

[Evaluation of left ventricular function: echocardiography, MRI or CT?]. / Evaluation de la fonction ventriculaire gauche: échocardiographie, IRM ou scanner?

The objective of this article is to clarify the advantages and limits of echocardiography, MRI, and CT for the determination of left ventricular (LV) function, emphasising the importance of evaluating global ventricular function. MRI is the reference technique, owing to its precision, reproducibility, and innocuous nature. However, echography is performed much more frequently because it is more widely available and easier to carry out. It is our reference technique in everyday practice. More recently, synchronised multi-slice tomodensitometry has provided dynamic reconstructed images of the left ventricle throughout the cardiac cycle, offering a succession of short axis views covering the entire volume of the ventricle. These acquisitions, in addition to non-invasive coronary angiography, allow the LV ejection fraction to be determined. With MRI, study of the LV function does not require any contrast medium to be injected and makes use of effective semi-automatic segmentation programs.

[Assessment of myocardial function and perfusion by MRI two days and four months after acute myocardial infarction revascularised by primary angioplasty]. / Evaluation par IRM de la fonction et de la perfusion myocardique à deux jours et quatre mois de l'infarctus aigu du myocarde revascularisé par angioplastie primaire.

The extent of gadolinium enhancement assessed by cardiac MRI is an accepted marker of myocardial necrosis. The correlation between late enhancement and other parameters of infarct size after myocardial infarction have previously been described. However, the prognostic value of the extent of late enhancement in terms of myocardial recovery remains controversial especially in revascularised infarcts analysed by early MRI. In order to clarify this question the authors compared the results of MRI at two days and four months after myocardial infarction benefiting from early revascularisation. Between July 2002 and November 2004, the authors included patients with myocardial infarction treated by primary angioplasty and examined by MRI (Siemens Symphony 1.5 T) at two days and three to five months after myocardial infarction. The left ventricular ejection fraction, volume, mass and wall thickness were measured. Perfusion at first passage (PP) and late enhancement were analysed after injection of 20 cc of gadolinium. An eight segment short axis model was used for PP and analysis of late enhancement. Each segment was assessed for transmural or subendocardial hypoperfusion for PP assessment and the wall thickness with late enhancement (1-25%, 26-50%, 51-75%, and 76-100%) was measured to calculate the percentage of myocardial mass showing late enhancement. Thirty-nine patients (thirty three men) were included. The average age was 59 +/- 10 years. TIMI III flow was obtained in all but one (TIMI II) patient. Cardiac MRI was performed 2.1 +/- 1.5 days and 4.6 +/- 1.7 months after myocardial infarction. The ejection fraction increased from 48.7 +/- 12.6% to 54.2 +/- 11.1%, p<0.05, and was related to infarct size (p<0.01). Forty-eight per cent of dysfunctional segments at the initial MRI improved their contractility and the extent of transmural late enhancement was inversely correlated with wall thickening at initial (p<0.01) and four month MRI (p<0.01). The PP improved significantly (regression from 9.5 +/- 8.2% to 2.8 +/- 4.1% of segments with abnormal myocardial perfusion, p<0.01). The late enhancement with respect to total myocardial mass decreased from 20.0 +/- 10.7% to 13.0 +/- 8.1%, p<0.01). Despite restoring TIMI III flow, early myocardial reperfusion is incomplete and improves in the medium term. The authors also observed a reduction in late enhancement at four months, indicating that the results immediately after myocardial infarction may overestimate the infarct size and that this sign does not represent necrotic tissue alone but also viable myocardium with a potential for recovery.

Fast determination of regional myocardial strain fields from tagged cardiac images using harmonic phase MRI.

BACKGROUND: Tagged MRI of the heart is difficult to implement clinically because of the lack of fast analytical techniques. We investigated the accuracy of harmonic phase (HARP) imaging for rapid quantification of myocardial strains and for detailed analysis of left ventricular (LV) function during dobutamine stimulation. METHODS AND RESULTS: Tagged MRI was performed in 10 volunteers at rest and during 5 to 20 microg(-1). kg(-1). min(-1) dobutamine and in 9 postinfarct patients at rest. We compared 2D myocardial strains (circumferential shortening, Ecc; maximal shortening, E(2); and E(2), direction) as assessed by a conventional technique and by HARP. Full quantitative analysis of the data was 10 times faster with HARP. For pooled data, the regression coefficient was r=0.93 for each strain (P<0.001). In volunteers, Ecc and E(2) were greater in the free wall than in the septum (P<0.01), but recruitable myocardial strain at peak dobutamine was greater in the LV septum (P<0.01). E(2) orientation shifted away from the circumferential direction at peak dobutamine (P<0.01). HARP accurately detected subtle changes in myocardial strain fields under increasing doses of dobutamine. In patients, HARP-determined Ecc and E(2) values were dramatically reduced in the asynergic segments as compared with remote (P<0.001), and E(2) direction shifted away from the circumferential direction (P<0.001). CONCLUSIONS: HARP MRI provides fast, accurate assessment of myocardial strains from tagged MR images in normal subjects and in patients with coronary artery disease with wall motion abnormalities. HARP correctly indexes dobutamine-induced changes in strains and has the potential for on-line quantitative monitoring of LV function during stress testing.

Transesophageal magnetic resonance imaging of the aortic arch and descending thoracic aorta in patients with aortic atherosclerosis.

OBJECTIVES: We sought to determine the feasibility and potential of transesophageal magnetic resonance imaging (TEMRI) for quantifying atherosclerotic plaque burden in the aortic arch and descending thoracic aorta in comparison with transesophageal echocardiography (TEE). BACKGROUND: Improved morphologic assessment of atherosclerotic plaque features in vivo is of interest because of the potential for improved understanding of the pathophysiology of plaque vulnerability to rupture and progression to clinical events. Magnetic resonance imaging (MRI) is well suited for atherosclerotic plaque imaging. Performing MRI using a radio frequency (RF) receiver probe placed near the region of interest improves the signal-to-noise ratio (SNR). METHODS: High-resolution images of the thoracic aortic wall were obtained by TEMRI in 22 subjects (8 normals, 14 with aortic atherosclerosis). In nine subjects, we compared aortic wall thickness and circumferential extent of atherosclerotic plaque measured by TEMRI versus TEE using a Bland-Altman analysis. Additional studies were performed in a human cadaver with pathology as an independent gold standard for assessment of atherosclerosis. RESULTS: In clinical and experimental studies, we found similar measurements for aortic plaque thickness but a relative underestimation of circumferential extent of atherosclerosis by TEE (p = 0.001), due in large part to the lower SNR in the near field. CONCLUSIONS: Using TEMRI allows for quantitative assessment of thoracic aortic atherosclerotic plaque burden. This technique provides good SNR in the near field, which makes it a promising approach for detailed characterization of aortic plaque burden.

Transmural contractile reserve after reperfused myocardial infarction in dogs.

OBJECTIVES: The goal of this study was to characterize detailed transmural left ventricular (LV) function at rest and during dobutamine stimulation in subendocardial and transmural experimental infarcts. BACKGROUND: The relation between segmental LV function and the transmural extent of myocardial necrosis is complex. However, its detailed understanding is crucial for the diagnosis of myocardial viability as assessed by inotropic stimulation. METHODS: Short-axis tagged magnetic resonance images were acquired at five to seven levels encompassing the LV from base to apex in seven dogs 2 days after a 90-min closed-chest left anterior descending coronary occlusion, followed by reflow. Myocardial strains were measured transmurally in the entire LV by harmonic phase imaging at rest and 5 ig x kg(-1) x min(-1) dobutamine. Risk regions were assessed by radioactive microspheres, and the transmural extent of the infarct was assessed by 2,3,5 triphenyltetrazolium chloride staining. RESULTS: Circumferential shortening (Ecc), radial thickening (Err) and maximal shortening at rest were greater in segments with subendocardial versus transmural infarcts, both in subepicardium (-1.1+/-1.0 vs. 2.5+/-0.6% for Ecc, -0.5+/-1.9 vs. -1.8+/-1.0% for Err, p < 0.05) and subendocardium (-2.0+/-1.4 vs. 2.8+/-0.8%, 2.4+/-1.7 vs. 0.0+/-0.9%, respectively, p < 0.05). Under inotropic stimulation, risk regions retained maximal contractile reserve. Recruitable deformation was found in outer layers of subendocardial infarcts (p < 0.01 for Ecc and Err) but also in inner layers (p < 0.01). Conversely, no contractile reserve was observed in segments with transmural infarcts. CONCLUSIONS: Under dobutamine challenge, recruitment of myofiber shortening and thickening was observed in inner layers of segments with subendocardial infarcts. These results may have important clinical implications for the detection of myocardial viability.

Prediction of functional recovery of viable myocardium after delayed revascularization in postinfarction patients: accuracy of dobutamine stress echocardiography and influence of long-term vessel patency.

OBJECTIVES: We sought to evaluate dobutamine stress echocardiography (DSE) for predicting recovery of viable myocardium after revascularization with cineangiography as a gold standard for left ventricular (LV) function. We studied the influence of late vessel reocclusion on regional LV function. BACKGROUND: Dobutamine stress echocardiography is a well established evaluation method for myocardial viability assessment. In previous studies the reference method for assessing LV recovery was echocardiography, long-term vessel patency has not been systematically addressed. METHODS: Sixty-eight patients with a first acute myocardial infarction (AMI) and residual stenosis of the infarct related artery (IRA) underwent DSE (mean +/- standard deviation) 21 +/- 12 days after AMI to evaluate myocardial viability. Revascularization of the IRA was performed in 54 patients by angioplasty (n = 43) or bypass grafting (n = 11). Coronary angiography and LV cineangiography were repeated at four months to assess LV function and IRA patency. RESULTS: Sensitivity and specificity of DSE for predicting myocardial recovery after revascularization were 83% and 82%. In the case of late IRA patency, specificity increased to 95%, whereas sensitivity remained unchanged. In the 16 patients with myocardial viability and late IRA patency, echocardiographic wall motion score index decreased after revascularization from 1.83 +/- 0.15 to 1.36 +/- 0.17 (p = 0.0001), and left ventricular ejection fraction (LVEF) increased from 0.52 +/- 0.06 to 0.57 +/- 0.06 (p = 0.0004), whereas in five patients, reocclusion of the IRA prevented improvement of segmental or global LV function despite initially viable myocardium. CONCLUSIONS: Dobutamine stress echocardiography is reliable to predict recovery of viable myocardium after revascularization in postinfarction patients. Late reocclusion of the IRA may prevent LV recovery and influence the accuracy of DSE.

Segmentation of cardiac cine-MR images and myocardial deformation assessment using level set methods.

In this paper, we present an original method to assess the deformations of the left ventricular myocardium on cardiac cine-MRI. First, a segmentation process, based on a level set method is directly applied on a 2D + t dataset to detect endocardial contours. Second, the successive segmented contours are matched using a procedure of global alignment, followed by a morphing process based on a level set approach. Finally, local measurements of myocardial deformations are derived from the previously determined matched contours. The validation step is realized by comparing our results to the measurements achieved on the same patients by an expert using the semi-automated HARP reference method on tagged MR images.

Effect of delayed percutaneous transluminal coronary angioplasty of occluded coronary arteries after acute myocardial infarction.

Whether angioplasty of occluded vessels after myocardial infarction may have beneficial effects on left ventricular function remains unknown. Patients with a first myocardial infarction and thrombolytic therapy who had an occluded infarct-related vessel at delayed coronary angiography were referred systematically for an elective coronary angioplasty performed between 3 and 4 weeks after the myocardial infarction. All patients underwent stress-redistribution-reinjection thallium-201 single-photon emission computed tomography for myocardial viability assessment. Prior angioplasty, a quantitative evaluation of global and regional left ventricular function, was performed. The study group consisted of 38 patients (aged 57 +/- 10 years); 18 had anterior wall infarctions and 20 inferior wall infarctions, but before angioplasty 3 had a patent artery and were excluded. Angioplasty was successful in 30 patients. At follow-up 13 patients (43%) had an occluded coronary artery. In contrast with patients with an occluded coronary artery at follow-up, those with a patent coronary artery had no left ventricular enlargement and had an improvement in both left ventricular ejection fraction (from 48 +/- 9% to 52 +/- 9.8%, p = 0.002) and regional wall motion index (delta = +0.95 SD, p <0.01). In patients with a patent vessel at follow-up, there was a positive correlation between the number of myocardial viable segments and improvement of the infarct zone wall motion (r = 0.52; p = 0.035), and the number of necrotic segments at baseline was positively correlated to the 4-month changes in end-diastolic volume indexes (r = 0.6; p = 0.04). Thus, elective revascularization of occluded coronary arteries with viable myocardium after myocardial infarction improves left ventricular function and lessens remodeling if the artery remains patent during follow-up.

Stratification of single-vessel coronary stenosis by ischemic threshold at the onset of wall motion abnormality during continuous monitoring of left ventricular function by semisupine exercise echocardiography.

We studied the relation between the ischemic threshold at the onset of wall motion abnormality on exercise echocardiography (EE) and the severity of coronary stenosis in patients with 1-vessel coronary artery disease (CAD). We screened 216 consecutive patients who underwent coronary angiography and EE for suspected CAD. Ninety-five (74 men; age, 56 +/- 12 years) satisfied the study criteria, that is, the presence of 1-vessel disease or no evidence of CAD on angiography and a normal baseline echocardiogram. Eighty-seven patients had 1-vessel CAD on angiography, and exercise-induced wall motion abnormality occurred in 73 (77%). Optimal cutoff values of percent diameter stenosis and minimal lumen diameter for predicting a positive EE were 61% (sensitivity and specificity of 76%) and 1.12 mm (sensitivity and specificity of 74%). Among patients with positive EE, heart rate-blood pressure product at ischemic threshold was correlated with quantitative coronary stenosis (r = -0.72, P <.001). The ischemic threshold from continuous monitoring of left ventricular function during semisupine EE is correlated with the severity of coronary stenosis among patients with 1-vessel disease and a normal resting echocardiogram.

Comparison of regional myocardial velocities assessed by quantitative 2-dimensional and M-mode color Doppler tissue imaging: influence of the signal-to-noise ratio of color Doppler myocardial images on velocity estimators of the Doppler tissue imaging system.

M-mode color Doppler imaging of the myocardium affords a greater sampling rate and signal-to-noise (S/N) ratio than 2-dimensional (2D) imaging. In this study, we compared myocardial velocities assessed by 2D and M-mode Doppler tissue imaging (DTI) at the same site and evaluated the influence of the S/N ratio on velocity estimates of the currently used DTI systems. In patients with and without impaired regional left ventricular function, myocardial velocities assessed by 2D DTI were lower than those obtained with M-mode DTI. The difference between regional velocities derived from both imaging techniques was positively correlated with the extent of the "black zone," which could be considered as indirectly reflecting the S/N ratio for each frame. Thus in the clinical setting and on currently used echocardiographs, 2D DTI may provide underestimated regional myocardial velocities when compared with M-mode, mainly because of the influence of the lower sampling rate and S/N ratio on velocity estimators of the imaging system.

Magnetic resonance imaging of myocardial infarct.

Magnetic resonance imaging offers the unique opportunity to directly visualize the size and location of myocardial infarcts (MIs) with excellent spatial resolution. Because infarct size is the most important determinant of postinfarct outcome, precise determination of infarct size may be valuable to risk stratify patients after acute MI. In addition, infarct imaging may provide direct information on the amount of irreversibly injured myocardium and thus can be used to identify myocardial viability in dysfunctional regions. Acute infarcts can be recognized as hyperintense signal on T2-weighted spin-echo images. This technique, however, does not identify chronic infarcts and may overestimate infarct size by including area at risk. Also, T2-weighted images often have a low signal-to-noise ratio. Contrast-enhanced perfusion imaging provides better-quality images. Extravascular contrast agents such as (Gd-DTPA) gadolinium diethyletriamine-pentaacetic acid identify infarcts as hyperenhanced regions on images acquired late after contrast injection. In addition, these tracers can examine the integrity and permeability of infarct microvasculature on first-pass perfusion images. Necrosis avid tracers and 23Na imaging are other new exciting approaches to identify infarcted myocardium acutely after MI. These techniques, are still investigational, and their value for clinical imaging remains to be established.

Magnetic resonance imaging of acute myocardial ischaemia and infarction.

Recent developments in cardiac magnetic resonance imaging (MRI) have led to tremendous breakthroughs in the imaging of acute myocardial ischaemia and infarction. Hardware and acquisition sequences have improved image quality while simplifying cardiac examinations. Cine-MRI allows for accurate time-resolved imaging of global and segmental left ventricular (LV) function with high spatial resolution. Dynamic multislice MRI of myocardial perfusion is now widely available allowing for the detection of microvascular obstruction after myocardial infarction (MI) or adding significant diagnostic value over usual clinical and biological markers after non ST elevation coronary syndromes. Direct high-resolution MRI of MI is well standardized with important clinical implications for the diagnosis of myocardial viability. In addition, stress cardiac MRI enables time-resolved analysis of myocardial perfusion under pharmacological stress, or accurate assessment of regional LV function during dobutamine cine-MRI for detection of myocardial ischaemia and/or viability. Non-invasive MR coronary angiography is beyond the scope of this article.

[Treatment by angiotensin converting enzyme inhibitors after myocardial infarction. What did the clinical trials teach us?]. / Traitement par inhibiteurs de l'enzyme de conversion après infarctus du myocarde. Qu'avons-nous appris des grands essais?

Most clinical trials of angiotensin converting enzyme inhibitors after myocardial infarction have shown an improved outcome with reduction of morbidity and mortality. In comparable groups of patients, the results are concordant with a decrease in mortality which is all the more significant and early in severe infarction with serious haemodynamic consequences. The clinician has a new arm in his therapeutic arsenal either for use in the acute phase of all cases of myocardial infarction but for only a short period of 4 to 6 weeks after which the treatment is withdrawn when the anatomical sequellae are more moderate, or for use in selected cases for longer periods (patients with severe infarction with cardiac failure and/or severe left ventricular dysfunction). The second attitude has the advantage of treating a selected population which will derive greater benefits. In all cases, treatment should be started orally at low doses, and the dose must be increased rapidly do attain the target dosage under close clinical and biological surveillance. When the classical contraindications are respected, ACE inhibitors seem to be well tolerated even at the relatively high dosages recommended after myocardial infarction. Hypotension and, more rarely, renal failure, are the two most common complications leading to withdrawal of treatment, but neither of these side effects was associated with increased mortality in any of the clinical trials. The mechanisms by which ACE inhibitors exert these beneficial effects after myocardial infarction are not only their haemodynamic effects and their role in ventricular remodelling, but also probably by a vascular protective action which, if confirmed, would further increase the indications of this therapeutic class in cardiovascular diseases.

[Alterations of left ventricular mechanics after anterior myocardial infarction. Quantitative analysis by tissue doppler echocardiography]. / Altérations de la mécanique ventriculaire gauche après infarctus du myocarde antérieur. Etude quantitative par échocardiographie doppler tissulaire.

Myocardial ischemia is usually responsible for alterations of regional left ventricular function which are not quantified by routine echocardiography. We used tissue Doppler echocardiography to quantitate the three main components (radial, longitudinal and angular) of left ventricular function, and their alterations after acute anterior myocardial infarction. Radial function was assessed by the myocardial velocity gradient derived from M-mode color tissue Doppler echocardiography, and longitudinal function by the pulsed wave tissue Doppler echocardiography, in 26 patients who experienced a first acute anterior myocardial infarction and in 11 matched healthy subjects. We describe a new tissue Doppler method for the measurement of septal angular deformation during cardiac contraction. In healthy subjects, our results showed heterogeneous regional myocardial contraction. Septal angular deformation occurred in the same direction and was of the same order as predicted by previous MRI studies. After anterior infarction, systolic and diastolic myocardial velocity gradients were dramatically decreased in the anterior wall when compared with controls (p < 0.01), whereas the systolic velocity gradient was significantly higher in the opposite wall (p < 0.05). Pulsed wave tissue Doppler echocardiography revealed significant alterations of longitudinal left ventricular function. Septal angular deformation was decreased after anterior infarct, and a good correlation was found between the angle of rotation and the left ventricular ejection fraction by cineangiography. These results indicate that tissue Doppler echocardiography has the potential for measuring the three main components of regional left ventricular function, and for quantitatively assessing their functional alterations induced by acute myocardial ischemia.

[Chronic ischemic left ventricular dysfunction: myocardial hibernation?]. / Dysfonction ventriculaire gauche chronique d'origine ischémique: hibernation myocardique?

Hibernating myocardium is a term which covers chronic ischaemic left ventricular dysfunction which is potentially reversible after revascularisation. Hibernating myocardium is classically associated with chronic hypoperfusion responsible for hypocontraction and cellular degeneration. This "classical" conception has been questioned as some workers emphasise that the reduction in coronary reserve responsible for repeated episodes of ischaemia and stunning could be the main causes of myocardial dysfunction. Position emission tomography (PET), and, most of all, myocardial scintigraphy and dobutamine echocardiography are the most commonly used techniques for detecting hibernating myocardium. Their sensitivity is good but the specificity and positive predictive value of dobutamine echocardiography seems to be better than the isotopic techniques. Structural abnormalities of hibernating myocardium and the delay, which is often long, between revascularisation and improvement, may explain some of the discordances between these techniques. Irrespective of the term used, hibernation or chronic ischaemic left ventricular dysfunction with myocardial viability, the reported data is in favour of coronary revascularisation with improved long-term quality of life and reduced mortality in patients with positive viability tests.

[The best of echocardiography in 1999]. / L'essentiel de 1999 en échocardiographie.

As many techniques of medical investigation, echocardiography regularly benefits from technical innovations which, with application, prove to be extremely useful and, for some of them, even widen the field of investigation. The end of this decade has seen the introduction of major improvements. In daily practice, second harmonic imaging has been the most important technical advance with such improved quality of imaging that this mode has rapidly become the routine for transthoracic investigations in adults. All modern echocardiographs are, or can be, equipped at modest cost. Stress echocardiography, the diagnostic reliability of which is closely related to the quality of the imaging, has greatly benefited from this technique, to the point of obtaining equivalent results as nuclear medicine in the detection of myocardial ischaemia and cellular viability. The results are now sufficiently convincing for the technique to have a real prognostic value in myocardial ischaemia. Doppler tissue imaging is also a major advance but the clinical value is still under evaluation: the pulsed Doppler mode is quantifiable during the investigation, contrary to the calculation of transparietal velocity gradients which requires computerisation techniques not provided by all manufacturers. The regain in interest in contrast echocardiography is due to the development of agents which, injected intravenously, cross the pulmonary capillary barrier and opacify the left heart chambers. The reinforcement of the Doppler signal and improved detection of the endocardial echoes have justified the authorization of their commercialisation, but the essential point is their use in the investigation of myocardial perfusion which is under evaluation. Three-dimensional reconstruction has made great strides but its diffusion is still limited by the limited availability of the required powerful computers.

[Changes in left ventricular torsion during ischemia-reperfusion]. / Altérations de la rotation systolique du ventricule gauche au cours de l'ischémie-reperfusion.

We aimed to characterise the alterations of left ventricular twist during ischaemia-reperfusion and to study their relationship to global left ventricular function. Systolic left ventricular twist was measured at the mid-papillary muscle level by colour tissue Doppler echocardiography in 7 anaesthetised open-chest dogs at baseline, 90 min-occlusion of the left anterior descending, and 180 min after reflow. Tissue Doppler was also performed in 34 patients after anterior infarct and in 20 controls. In controls, rotation occurred counterclockwise when viewed from the base. In a random subset of subjects, the assessment of ventricular twist by tissue Doppler was validated against magnetic resonance myocardial tagging. Myocardial ischaemia led to a decrease in ventricular twist in dogs and infarct patients (p < 0.01). This decrease was correlated with the extent of the asynergic area and global left ventricular function (p < 0.001). In dogs, cardiac twist was higher after reflow relative to ischaemia (p < 0.01). Thus, acute myocardial ischaemia is responsible for a decrease in left ventricular twist that is related to global ventricular function. Colour tissue Doppler echocardiography provides straightforward assessment of left ventricular twist in humans.

[Left ventricular functional imagery by magnetic resonance. Applications and developments]. / Imagerie fonctionnelle du ventricule gauche par résonance magnétique. Applications et développements.

Technical developments have considerably reduced the acquisition time and have improved the quality of magnetic resonance imaging. The recent recommendations of the European Society of Cardiology place MRI in the front line of investigations for the diagnosis and evaluation of congenital heart disease, cardiac tumours and pathology of the pericardium and great vessels. With the possibility of obtaining oblique planes in all 3 dimensions, MRI is the reference for the measurement of left ventricular mass, volumes, and ejection fraction, with the major advantage of not depending on hypotheses of left ventricular geometry. In addition to these known applications, the development of functional cardiac MRI has led to significant advances in the study of regional myocardial function and perfusion. The aim of this article is to discuss present indications and the potential developments of functional cardiac MRI, focusing on the quantitative evaluation of myocardial function and perfusion.