Assessment of Myocardial Infarction in Humans with<sup>23</sup>Na MR Imaging: Comparison with Cine MR Imaging and Delayed Contrast Enhancement

Sandstede, J.; Pabst, Thomas; Beer, Meinrad; Lipke, Claudia; Bäurle, K.; Butter, F.; Harre, Kerstin; Kenn, W.; Voelker, Wolfram; Neubauer, Stefan; Hahn, Dietbert

doi:10.1148/radiol.2211001563

Cited by 55 publications

(36 citation statements)

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“…The endo-and epicardial borders, as well as the borders of the areas with elevated 23 Na SI, were traced manually with the use of ARGUS software version VB31B (Siemens AG, Germany). The mass of the area with elevated 23 Na SI was obtained by summing the volume for each slice, and expressed as a percentage of the total LV muscle mass (12). For evaluation of 23 Na SI, the SIs of the infarcted area and the entire noninfarcted myocardium, as well as noise, were measured for each slice separately by region-of-interest (ROI) analysis, and expressed as the mean and standard deviation (SD).…”

Section: Discussionmentioning

confidence: 99%

“…In human studies, we were able to show that 1) cardiac 23 Na MRI can be applied in humans, 2) the myocardium/blood 23 Na signal intensity (SI) ratio represents the ratio of the 23 Na concentrations in myocardium and blood, and 3) 23 Na SI is elevated in MI (10,11). A comparison of 23 Na MRI with 1 H MRI techniques in patients with subacute or chronic MI, respectively, revealed an area of elevated 23 Na SI that significantly correlated with wall motion abnormalities, as detected by cine MRI, in all patients after subacute MI and 80% of patients with chronic MI (12). Myocardial edema in subacute MI also correlated with the areas of elevated 23 Na SI, but it was extensively larger, whereas a significant correlation of late enhancement with 23 Na MRI was found only in the subacute group.…”

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Time course of ²³Na signal intensity after myocardial infarction in humans

Sandstede

Hillenbrand

Beer

et al. 2004

Magnetic Resonance in Med

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Experimental studies demonstrated persistently increased 23 Na content in nonviable myocardium post-myocardial infarction (MI). We hypothesized that nonviable myocardium in humans would show elevated 23 Na content at all stages of infarct development, and therefore could be imaged with 23 Na MRI. Ten patients were examined on days 4, 14, and 90 after infarction, and five of these patients participated in a 12-month follow-up. Physicians frequently require a diagnosis of myocardial viability in patients with large akinetic myocardial regions when they attempt to determine whether such patients should receive revascularization therapy. While nonviable myocardium cannot recover regional function, viable but stunned or hibernating myocardium will eventually resume contractile function following revascularization by percutaneous coronary intervention or bypass grafting (1). Current methods used to diagnose viability, such as positron emission tomography (PET), single photon emission tomography, or stress echocardiography, all have intrinsic limitations related to the use of ionizing radiation, limited access, patient discomfort, or limited acoustic windows. Recently, it was proposed that contrast-enhanced MRI is able to discriminate viable from nonviable myocardium (2).23 Na MRI is another promising approach for the detection of myocardial viability in human cardiac imaging without the need for an intravenous contrast agent (3,4). It has the potential to quantify infarct size, as well as to identify myocardial scars (5-8). In a recent experimental study employing 23 Na MR spectroscopy (MRS) and ion chromatography in the rat post-myocardial infarction (MI) model, we showed that the regional 23 Na concentration is significantly elevated in irreversibly injured myocardium following coronary ligation, both acutely and during the process of chronic scar formation (9). In the same study, we also showed that the Na signal was unchanged in stunned or hibernating myocardium. Thus, 23 Na MRI may allow physicians to diagnose myocardial viability in patients with akinetic areas, using Na content as an intrinsic contrast marker. In human studies, we were able to show that 1) cardiac 23 Na MRI can be applied in humans, 2) the myocardium/blood 23 Na signal intensity (SI) ratio represents the ratio of the 23 Na concentrations in myocardium and blood, and 3) 23 Na SI is elevated in MI (10,11). A comparison of 23 Na MRI with 1 H MRI techniques in patients with subacute or chronic MI, respectively, revealed an area of elevated 23 Na SI that significantly correlated with wall motion abnormalities, as detected by cine MRI, in all patients after subacute MI and 80% of patients with chronic MI (12). Myocardial edema in subacute MI also correlated with the areas of elevated 23 Na SI, but it was extensively larger, whereas a significant correlation of late enhancement with 23 Na MRI was found only in the subacute group. In the present clinical study, we hypothesized that total myocardial Na content would be elevated in patients with nonviabl...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Time course of ²³Na signal intensity after myocardial infarction in humans

Sandstede

Hillenbrand

Beer

et al. 2004

Magnetic Resonance in Med

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“…Short-axis views were applied to detect changes in tissue integrity in LV myocardium. 13 To detect late enhancement, images were acquired 10 to 15 minutes after the injection of gadopentetate dimeglumine (Magnevist, Schering, Berlin, Germany; 0.2 mmol/kg body weight) by use of an inversion recovery sequence (field of view, 240ϫ320 mm 2 ; matrix, 165ϫ256). All LV segments were evaluated for the presence of myocardial fibrosis according to the standardized nomenclature for imaging of the heart.…”

Section: Cmri Studiesmentioning

confidence: 99%

Impact of Myocardial Fibrosis in Patients With Symptomatic Severe Aortic Stenosis

et al. 2009

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Background— In this prospective follow-up study, the effect of myocardial fibrosis on myocardial performance in symptomatic severe aortic stenosis was investigated, and the impact of fibrosis on clinical outcome after aortic valve replacement (AVR) was estimated. Methods and Results— Fifty-eight consecutive patients with isolated symptomatic severe aortic stenosis underwent extensive baseline characterization before AVR. Standard and tissue Doppler echocardiography and cardiac magnetic resonance imaging (late-enhancement imaging for replacement fibrosis) were performed at baseline and 9 months after AVR. Endomyocardial biopsies were obtained intraoperatively to determine the degree of myocardial fibrosis. Patients were analyzed according to the severity of interstitial fibrosis in cardiac biopsies (severe, n=21; mild, n=15; none, n=22). The extent of histologically determined cardiac fibrosis at baseline correlated closely with New York Heart Association functional class and markers of longitudinal systolic function (all P <0.001) but not global ejection fraction or aortic valve area. Nine months after AVR, the degree of late enhancement remained unchanged, implying that AVR failed to reduce the degree of replacement fibrosis. Patients with no fibrosis experienced a marked improvement in New York Heart Association class from 2.8±0.4 to 1.4±0.5 ( P <0.001). Only parameters of longitudinal systolic function predicted this functional improvement. Four patients with severe fibrosis died during follow-up, but no patient from the other groups died. Conclusions— Myocardial fibrosis is an important morphological substrate of postoperative clinical outcome in patients with severe aortic stenosis and was not reversible after AVR over the 9 months of follow-up examined in this study. Because markers of longitudinal systolic function appear to indicate sensitively both the severity of myocardial fibrosis and the clinical outcome, they may prove valuable for preoperative risk assessment in patients with aortic stenosis.

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“…Due to lower MR detection sensitivity and lower in vivo concentration (9.3% and 0.05% relative to 1 H), the major limitation of 23 Na MR is the reduced signal-tonoise ratio (SNR) compared with 1 H MR. 23 Na MR, however, allows noninvasive insight into regional cellular ion homeostasis while 1 H MRI does not. In vivo and in vitro animal and human clinical studies demonstrated the feasibility of detecting location and quantifying myocardial infarction (2)(3)(4)(5).…”

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Evaluation of sodium T₁ relaxation times in human heart

Pabst

Sandstede

Beer

et al. 2003

Magnetic Resonance Imaging

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Purpose: To evaluate the sodium longitudinal relaxation (T 1 ) characteristics for myocardium and blood in humans. Materials and Methods:Eleven healthy volunteers were examined by using a 23 Na heart surface coil at a 1.5 T clinical scanner equipped with a broadband spectroscopy option. 23 Na MR measurements were performed by using a three-dimensional spoiled gradient echo sequence (inplane resolution, 3.5 mm ϫ 7 mm; slice thickness, 24 mm; TE, 3.1 msec; bandwidth, 65 Hz/pixel; TR, 21 to 150 msec). Results:Longitudinal T 1 relaxation time components were 31.6Ϯ7.0 msec and 31.1Ϯ7.5 msec for myocardium and blood, respectively. SODIUM CONTENT AND FUNCTION OF THE SODIUM-POTASSIUM PUMP are important factors in human cellular physiology. Dysfunction in cell membrane function, e.g., in acute myocardial ischemia, results in alterations of the sodium-potassium pump function and of the intracellular sodium content. Scar tissue, such as after chronic myocardial infarction, also shows increased Na content due to expansion of extracellular space (1). Therefore, evidence of increased sodium content allows detection of both acute and chronic myocardial infarction. Because of a nuclear spin value of 3/2 of the isotope 23 Na, sodium state changes can be measured noninvasively with MR imaging and spectroscopy. Due to lower MR detection sensitivity and lower in vivo concentration (9.3% and 0.05% relative to 1 H), the major limitation of 23 Na MR is the reduced signal-tonoise ratio (SNR) compared with 1 H MR. 23 Na MR, however, allows noninvasive insight into regional cellular ion homeostasis while 1 H MRI does not. In vivo and in vitro animal and human clinical studies demonstrated the feasibility of detecting location and quantifying myocardial infarction (2-5). ConclusionAnimal studies have demonstrated (4) that not only the concentration of the isotope 23 Na, but also the MR parameter T 1 and T 2 relaxation time, undergo significant changes under pathophysiological conditions. Determination and knowledge of the T 1 and T 2 relaxation time is important due to three reasons: additional pathophysiological information may be obtained; interpretation of sodium MR image contrast will be aided because T 1 , T 2, as well as the concentration, are the dominant factors affecting the image contrast; and the knowledge of the fundamental MR properties of biological tissue is essential for the development of MR imaging sequences and optimization of examination parameters for dedicated anatomical areas.The nuclear spin of the isotope 23 Na is 3/2. Thus, in contrast to the nucleus 1 H with spin 1 ⁄2, quadrupolar interactions with neighboring molecules become possible. This is the reason for a more complex relaxation behavior of 23 Na in comparison to 1 H. In biological tissue, a biexponential transverse relaxation with a slow and a fast component, as well as monoexponential transverse relaxation, were found in animal and in in vivo human studies (6 -14). T 1 relaxation measurements were performed in in vitro animal studies (4,15) and in in vi...

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Assessment of Myocardial Infarction in Humans with²³Na MR Imaging: Comparison with Cine MR Imaging and Delayed Contrast Enhancement

Abstract: (23)Na MR imaging demonstrates dysfunctional myocardium caused by subacute and chronic myocardial infarction.

Cited by 55 publications

References 27 publications

Time course of ²³Na signal intensity after myocardial infarction in humans

Time course of ²³Na signal intensity after myocardial infarction in humans

Impact of Myocardial Fibrosis in Patients With Symptomatic Severe Aortic Stenosis

Evaluation of sodium T₁ relaxation times in human heart

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Assessment of Myocardial Infarction in Humans with23Na MR Imaging: Comparison with Cine MR Imaging and Delayed Contrast Enhancement

Abstract: (23)Na MR imaging demonstrates dysfunctional myocardium caused by subacute and chronic myocardial infarction.

Cited by 55 publications

References 27 publications

Time course of 23Na signal intensity after myocardial infarction in humans

Time course of 23Na signal intensity after myocardial infarction in humans

Impact of Myocardial Fibrosis in Patients With Symptomatic Severe Aortic Stenosis

Evaluation of sodium T1 relaxation times in human heart

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Assessment of Myocardial Infarction in Humans with²³Na MR Imaging: Comparison with Cine MR Imaging and Delayed Contrast Enhancement

Time course of ²³Na signal intensity after myocardial infarction in humans

Time course of ²³Na signal intensity after myocardial infarction in humans

Evaluation of sodium T₁ relaxation times in human heart