Gd-BOPTA for assessment of myocardial viability on MRI: changes of T1 value and their impact on delayed enhancement

Gadobenate (Gd-BOPTA), injected at a dose of 0.1 mmol/kg body weight, was compared with gadopentetate (Gd-DTPA), injected at a dose of 0.2 mmol/kg body weight, for delineation of myocardial infarction interindividually in two groups of 26 patients each. Delayed enhancement images were assessed subjectively for image quality, and measured for regional T1 values before, 3 min after and 25 min after the injection of each contrast agent. In the 26 patients who received Gd-BOPTA, T1 values of remote myocardium were 1,070 ± 125 ms, 358 ± 78 ms and 562 ± 108 ms before, 3 min after and 25 min after injection, respectively. Infarcted myocardium values were 1,097 ± 148 ms, 246 ± 68 ms and 373 ± 84 ms and left ventricular blood pool 1,238 ± 95 ms, 194 ± 47 ms and 373 ± 72 ms. In the 26 patients who received Gd-DTPA, T1 values were 1,087 ± 96 ms, 325 ± 60 ms and 555 ± 108 ms for remote myocardium; 1,134 ± 109, 210 ± 43 ms and 304 ± 57 ms for infarcted myocardium; and 1,258 ± 104 ms, 166 ± 27 ms and 351 ± 73 ms for left ventricular blood pool. Delayed enhancement image quality showing myocardial infarction was rated good (54%) and excellent (46%) after Gd-BOPTA, and good (58%) and excellent (42%) after Gd-DTPA (no significant differences). A single dose of Gd-BOPTA compared with a double dose of Gd-DTPA causes similar changes of T1 values in infarcted and remote myocardium and provides fairly similar contrast between infarcted and remote myocardium (0.64 ± 14 versus 0.71 ± 11) and slightly higher contrast between left ventricular blood and infarcted myocardium (0.22 ± 17 versus 0.14 ± 6; p < 0.05). Administration of 0.1 mmol/kg body weight Gd-BOPTA can provide similar late enhancement images compared with the standard 0.2 mmol/kg body weight dose of Gd-DTPA due to the higher T1 relaxivity associated with the former. Peter Lodemann is an employee of Bracco Deutschland GmbH.     

Prediction of myocardial recovery by dobutamine magnetic resonance imaging and delayed enhancement early after reperfused acute myocardial infarction

The purpose was to study dobutamine magnetic resonance cine imaging (DOB-MRI) and delayed myocardial contrast enhancement (DE) early after reperfused acute myocardial infarction (AMI) for the predicion of segmental myocardial recovery and to find the optimal dose of dobutamine. Fifty patients (56±12 years, 42 males) with reperfused AMI underwent DOB-MRI and DE studies 3.5 (1–19) days after reperfusion. In DOB-MRI systolic wall thickening (SWT) was measured in 18 segments at rest and during dobutamine at 5, 10 and 20 μg*kg⁻¹*min⁻¹. Dysfunctional segments were identified and the extent of DE was measured for each segment. Segmental recovery was examined after 8 (5–15) months. Two hundred-forty-eight segments were dysfunctional with presence of DE in 193. DOB-MRI showed the best prediction of recovery at 10 μg*kg⁻¹*min⁻¹ of dobutamine with sensitivity of 67%, specificity of 63% and accuracy of 66% using a cut-off value for SWT of 2.0 mm. DE revealed a sensitivity of 68%, specificity of 65% and accuracy of 67% using a cut-off value of 46%. Combined analysis of DOB-MRI and DE did not improve diagnostic performance. Early prediction of segmental myocardial recovery after AMI is possible with DOB-MRI and DE. No improvement is achieved by dobutamine >10 μg*kg⁻¹*min⁻¹ or a combination of DOB-MRI and DE.     

Delayed enhancement imaging: standardised segmental assessment of myocardial viability in patients with ST-elevation myocardial infarction

OBJECTIVE: To prospectively compare a selective short axis slice positioning method (selective 3-of-5) used in combination with a single long-axis slice, to the conventional short axis multi-slice technique in the assessment of myocardial viability. MATERIALS AND METHODS: Thirty-one patients with recent or chronic ST segment elevation myocardial infarct (STEMI) were recruited to undergo delayed enhancement (DE) cardiac magnetic resonance imaging (CMR). All patients underwent both methods of DE imaging, with subsequent review of both sets of data by two experienced observers. Sensitivity and specificity, as well as intra and interobserver reproducibility for both techniques were assessed. RESULTS: There was good agreement between the selective 3-of-5 and the conventional multi-slice method for the assessment of viability, with no significant difference in results for sensitivity or reproducibility between the techniques. CONCLUSION: In patients with STEMI, a selective 3-of-5 short axis slice acquisition used in combination with a single vertical long-axis slice can be utilised to produce a standard American Heart Association (AHA) 17-segment model for the assessment of myocardial viability.     

Cardiac delayed enhancement distribution in extralysosomial glycogen storage disease

We describe magnetic resonance (MR) aspect of cardiac glycogenesis in a 49-years old man, presented a progressively declining cardiac function and negative coronary angiography. Delayed enhancement MR confirmed non-ischemic pattern with unusual diffuse distribution of Gadolinium. Cardiac biopsy revealed a Glycogen Storage Disease, extra-lysosomial type. Cardiac MR with analysis of delayed enhancement distribution is an emerging tool that can discriminate between ischemic and non-ischemic diseases; however to identify the precise aetiology of a non-ischemic distribution, myocardial biopsy is still needed.     

Myocardial delayed contrast enhancement in patients with arterial hypertension: Initial results of cardiac MRI

Purpose

In arterial hypertension left ventricular hypertrophy comprises myocyte hypertrophy, interstitial fibrosis and structural alterations of the coronary microcirculation. MRI enables the detection of myocardial fibrosis, infarction and scar tissue by delayed enhancement (DE) after contrast media application.Aim of this study was to investigate patients with arterial hypertension but without known coronary disease or previous myocardial infarction to detect areas of DE.

Methods and material

Twenty patients with arterial hypertension with clinical symptoms of myocardial ischemia, but without history of myocardial infarction and normal coronary arteries during coronary angiography were investigated on a 1.0 T superconducting magnet (Gyroscan T10-NT, Intera Release 8.0, Philips). Fast gradient-echo cine sequences and T2-weighted STIR-sequences were acquired. Fifteen minutes after injection of Gadobenate dimeglumine inversion recovery gradient-echo sequences were performed for detection of myocardial DE. Presence or absence of DE on MRI was correlated with clinical data and the results of echocardiography and electrocardiography, respectively.

Results

Nine of 20 patients showed DE in the interventricular septum and the anteroseptal left ventricular wall. In 6 patients, DE was localized intramurally and in 3 patients subendocardially. There was a significant correlation between myocardial DE and ST-segment depressions during exercise and between DE and left-ventricular enddiastolic pressure. Patients with intermittent atrial fibrillation showed a myocardial DE more often than patients without atrial fibrillation.

Conclusion

In our series, 45% of patients with arterial hypertension showed DE on cardiac MRI. In this clinical setting, delayed enhancement may be due to coronary microangiopathy. The more intramurally localization of DE, however, rather indicates myocardial interstitial fibrosis.     

Simultaneous myocardial and fat suppression in magnetic resonance myocardial delayed enhancement imaging

PURPOSE: To develop a method for fat suppression in myocardial delayed enhancement (MDE) studies that achieves effective signal intensity reduction in fat but does not perturb myocardial signal suppression. MATERIALS AND METHODS: A new approach to fat suppression that uses a spectrally-selective inversion-recovery (SPEC-IR) tip-up radio frequency (RF) pulse following the conventional nonselective IR RF pulse together with a second SPEC-IR RF pulse is proposed. The tip-up pulse restores the fat longitudinal magnetization after the nonselective IR pulse and allows the fat magnetization to recover more fully toward its equilibrium value, providing for better fat suppression by the second SPEC-IR RF pulse. This new approach was validated in phantom studies and in five patients. RESULTS: Effective fat suppression was achieved using the proposed technique with minimal impact on normal myocardial signal suppression. Mean fat suppression achieved using this approach was 67% +/- 8%, as measured in the chest wall immediately opposite the heart. CONCLUSION: The results indicate this modular-type approach optimizes fat suppression in myocardial delayed enhancement studies but does not perturb the basic IR pulse sequence or change basic acquisition parameters.     

Pattern of delayed myocardial enhancement: A key to differentiate ischemic and non-ischemic cardiomyopathies

Objective

Our objective is to find out if the pattern of delayed myocardial enhancement can be used as a key to diagnose and specify different types of cardiomyopathies.

Patients and methods

Fifty-four patients with suspected cardiomyopathy were enrolled in this study. Patients’ age ranged from 3 to 68 years. All patients were subjected to history taking, laboratory investigations, 2D echocardiography and cardiac magnetic resonance. Images were evaluated for presence, distribution, pattern and site of delayed myocardial enhancement.

Results

Seven types of cardiomyopathies were diagnosed in this study. Each type had a characteristic pattern of myocardial enhancement. Ischemic cardiomyopathy showed subendocardial up to transmural enhancement within the territory of the coronary arteries. Dilated cardiomyopathy showed midwall linear enhancement, hypertrophic cardiomyopathy showed patchy midwall enhancement and restrictive cardiomyopathy showed subendocardial circumferential enhancement. Arrythmogenic right ventricular dysplasia showed enhancement of the dilated right ventricle. Non-compaction showed enhancement of the non-compacted area. Sarcoidosis showed midwall patchy enhancement while Behcet’s disease showed right ventricular subendocardial enhancement.

Conclusion

The pattern of myocardial enhancement can be used as a key to diagnose all types of cardiomyopathies. The use of cardiac magnetic resonance in cardiomyopathy is important to quantify myocardial fibrosis as this has prognostic implications.     

Optimizing dose and administration regimen of a high-relaxivity contrast agent for myocardial MRI late gadolinium enhancement

Objectives

To investigate the time-course of late gadolinium enhancement of infarcted myocardium using gadobenate dimeglumine at different dosages and administration regimens.

Materials and methods

After institutional review board approval and informed consent, we studied 13 patients (aged 63 ± 11 years) with chronic myocardial infarction. They underwent two gadobenate dimeglumine-enhanced MR examinations (interval 24–48 h) using short-axis inversion-recovery gradient-echo sequences, with the following two different protocols, in randomized order: 0.05 mmol/kg and imaging at the 2.5th, 5th, 7.5th and 10th minute plus 0.05 mmol/kg and imaging at the 12.5th, 15th, 17.5th and 20th minute; the same as before but using 0.1 mmol/kg for both contrast injections. Contrast-to-noise ratios (CNRs) between infarcted myocardium, non-infarcted myocardium and left ventricle cavity were calculated for each time-point (2.5-min steps). Friedman ANOVA was used for comparing the CNR time-course; Wilcoxon test for comparing CNR at the 10th and the 20th minute.

Results

The CNR between infarcted and non-infarcted myocardium obtained at the 20th minute with 0.05 plus 0.05 mmol/kg resulted significantly higher than that obtained at the 10th minute with 0.05 mmol/kg (P = 0.033) while not significantly different from that obtained at the 10th (0.1 mm/kg) or at the 20th minute with 0.1 plus 0.1 mmol/kg. The CNR between infarcted myocardium and the left ventricle cavity obtained at the 20th minute with 0.05 plus 0.05 mmol/kg resulted significantly higher than all other measured values (P ≤ 0.017).

Conclusion

Using gadobenate dimeglumine, 0.05 plus 0.05 mmol/kg allows for a higher CNR between infarcted myocardium and the left ventricle cavity allowing for reliable assessment of the sub-endocardial infarctions.     

Visual estimation of the global myocardial extent of hyperenhancement on delayed contrast-enhanced MRI

MRI with paramagnetic contrast agent allows the assessment of the extent of myocardial tissue injury after infarction. Visual segmental scoring has been widely used to define the transmural extent of myocardial infarction, but no attempt has been made to use visual scores in order to assess the percentage of the whole myocardium infarcted. By summing all the segmental scores using a 17-segment model, a global index of the size of the infarcted myocardium is easily obtained. The entire left ventricle of 60 patients with a recent myocardial infarction was scanned using an ECG-gated gradient echo sequence after injection of gadolinium contrast agent. The global score was defined as the sum of the scores on each segment, and expressed as a percentage of the maximum possible score. This index was compared with a planimetric evaluation of hyperenhancement, expressed as a percentage of the left ventricle myocardial volume. There is a good correlation between the two methods (r=0.91; y=1.06x+0.20), and the Bland-Altman plot shows a high concordance between the two approaches (mean of the differences =1.45%). A visual approach based on a 17-segment model can be used to evaluate the global myocardial extent of the hyperenhancement with similar results to planimetry.     

Evaluation of left ventricle diastolic dysfunction in ischemic heart disease by CMR: Correlation with echocardiography and myocardial scarring

Objective

To detect the value of cardiac MR imaging in assessment of left ventricle diastolic function in patients with ischemic heart disease compared to echocardiography and to correlate the degree of dysfunction to the extent of myocardial scarring.

Patients and methods

We examined 40 patients with known coronary artery disease. Mean patient’s age was 48 ± 10. All patients were subjected to 2D echocardiography and CMR including transmitral flow and left atrial planimetry. The degree of diastolic dysfunction was detected and correlated with the echocardiographic results and the extent of myocardial scarring.

Results

On CMR, 35% of the cases had grade I diastolic dysfunction, 35% showed grade II, 15% had grade III while 15% showed normal diastolic function. CMR showed 94.12% sensitivity, 100% specificity and 95% accuracy. Excellent agreement with echocardiography was detected (Kappa coefficient 0.931). There was a significant correlation between the degree of diastolic dysfunction and the extent of myocardial scarring with Spearman’s correlation coefficient of 0.492 and p = 0.028.

Conclusion

CMR has comparative results to echocardiography in assessment of diastolic dysfunction. We found a significant correlation between the degree of diastolic dysfunction and the extent of myocardial scarring.     

Double outlet right ventricle presenting in an adult woman: a case report

Double outlet right ventricle (DORV) is a congenital cardiac malformation that occurs in 1%-3% of individuals with congenital heart defects. Cardiac magnetic resonance imaging (MRI) may play an important role in the anatomy of the ventricular septal defect, functional status of both ventricles, and in identifying any residual stenosis or regurgitation or coexistent anomalies. Here, we present a case of a 28-years-old woman who came to our emergency department with shortness of breath. The patient felt shortness of breath on exertion and improved with rest. Clinical examination showed no abnormalities except low oxygen saturation of 65%. After echocardiography and cardiac MRI were done, it was concluded that she had a double outlet right ventricle with peri membranous ventricular septal defect (VSD), pulmonary hypertension, and pericardial effusion. This study highlights the role of cardiac MRI in assessing DORV.     

Quantification of enhancement of left ventricular myocardium in patients with dilated cardiomyopathy using delayed enhanced MR imaging

The purpose is to evaluate delayed enhancement (DE) of the myocardium in patients with dilated cardiomyopathy (DCM), compared with control subjects. We also evaluated the interrelationships of DE and contractile function.DCM patients (n = 42) and 14 control subjects were evaluated by DE MR imaging, acquired using a two-dimensional segmented inversion-recovery prepared gradient-echo sequence (TI = 250 ms), 15 min after intravenous administration of 0.2 mmol/kg gadolinium.For the myocardium of left ventricle (LV), we traced epicardial and endocardial borders, and regions of interest (ROIs) were placed in each slice. For analysis of DE images, the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) of the LV myocardium were calculated. The averaged SNR (aSNR) and averaged CNR (aCNR) per slice of the LV myocardium were calculated. In the DCM group, we also evaluated the interrelationship of DE and the contractile function of the LV.Mean aSNR was not significantly different between the studied groups; however, mean aCNR was significantly higher in the DCM group (3.5 ± 3.1) than in control subjects (−4.1 ± 2.1).In the DCM group, aCNR was moderately related to LV ejection fraction (LVEF) (r = 0.52, P < .0001). Mean aCNR was significantly higher in the DCM group with low LVEF (<25%) (6.0 ± 2.8) than in the DCM group with high LVEF (≥25%) (2.0 ± 2.3).In DE MR imaging, the LV myocardium of DCM usually has high aCNR, which may suggest fibrosis. Quantification of aCNR may contribute to the diagnosis of DCM. The level of aCNR seems to correlate with LVEF. Using this technique, quantification of aCNR is objective and very useful for the diagnosis of DCM and contractile function of LV.     

对比剂剂量优化在心脏MRI延迟强化扫描中的临床应用

目的 在心脏MRI延迟强化中,通过分别注射不同剂量(10 mL、20 mL与30 mL)钆喷酸匍胺,观察它们图像质量,优化对比剂剂量.方法 选取志愿者30例(随机分成3组)行心脏MRI延迟强化检查,通过测量不同剂量图像的信噪比(SNR)、对比信噪比(CNR),包括心肌信噪比(SNRmyo)、血池信噪比(SNRbp)和心肌与血池信噪比(CNRbp/myo)等参数评价图像差别.结果 统计学结果显示对比剂剂量20 mL与30 mL图像质量无差异(P＞0.05),而10 mL与30 mL图像质量有差异(P＜0.000 1),后者图像质量优于前者;SNRmyDo、SNRbp和CNRbp/myo 20 mL与30 mL之间没有统计学差异.结论 在心脏MRI延迟扫描中,使用对比剂剂量20 mL时,既可以保证图像质量、满足临床诊断要求,又可以更安全可靠.     

Enhanced viability imaging: improved contrast in myocardial delayed enhancement using dual inversion time subtraction.

In delayed contrast-enhanced MRI for the assessment of myocardial viability, the TI time in a gated inversion-recovery segmented gradient echo sequence is usually selected to null signal from normal myocardium. Although this TI time generates good contrast between the enhancing infarcted tissue and normal myocardium, there is usually less contrast between the infarct and the blood pool. A subtractive technique utilizing two acquisitions at a long and short TI time is proposed to improve the delineation between infarct-blood and infarct-myocardium. The concept was demonstrated in six mongrel dogs with reperfused myocardial infarction. Infarct-normal myocardium contrast (signal difference) using the proposed enhanced viability imaging (ENVI) technique was 142 +/- 50% (P < 0.001) that of standard magnitude inversion recovery (IR), while at the same TI time for the primary image, infarct-blood contrast, was 247 +/- 136% (P < 0.002) that of magnitude IR. Accounting for increased noise due to the subtraction, signal difference-to-noise ratios (SDNR) did not show a significant change for infarct-myocardium but infarct-blood SDNR for ENVI was 174 +/- 105% that of magnitude-IR (P < 0.03). Thus, marked improvement in the delineation of the infarcted zone was noted over a range of TI times.     

Myocardial delayed enhancement imaging using inversion recovery single-shot steady-state free precession: initial experience

PURPOSE: To evaluate the feasibility of using an inversion recovery single-shot steady-state free precession (SS_SSFP) sequence for myocardial delayed enhancement (MDE) imaging, and to compare SS_SSFP with the conventional inversion recovery segmented fast gradient echo (IR_FGRE) technique. MATERIALS AND METHODS: Ten subjects (four volunteers and six patients with suspected or known coronary disease) were included in this study. All subjects were scanned with both IR_FGRE and SS_SSFP sequences 15-25 minutes after gadopentetate dimeglumine injection. Overall image quality, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) between the two techniques were compared. RESULTS: Compared to IR_FGRE, SS_SSFP exhibited adequate image quality (average scores = 3.8 for IR_FGRE and 3.9 for SS_SSFP) with much shorter acquisition time (14.4 seconds for IR_FGRE and 1.3 seconds for SS_SSFP). SS_SSFP images showed higher SNRs (P < 0.05) and less motion artifact from breathing. Enhanced myocardium was detected by both techniques in three patients, but the image sharpness is compromised in SS_SSFP images. CONCLUSION: SS_SSFP provides adequate image quality compared to IR_FGRE, while requiring a much shorter acquisition time. It is feasible to use SS_SSFP as an alternative method for MDE imaging, especially in patients who have difficulty with holding their breath.     

Comparison of visual scoring and quantitative planimetry methods for estimation of global infarct size on delayed enhanced cardiac MRI and validation with myocardial enzymes

Purpose

Although delayed enhanced CMR has become a reference method for infarct size quantification, there is no ideal method to quantify total infarct size in a routine clinical practice. In a prospective study we compared the performance and post-processing time of a global visual scoring method to standard quantitative planimetry and we compared both methods to the peak values of myocardial biomarkers.

Materials and methods

This study had local ethics committee approval; all patients gave written informed consent. One hundred and three patients admitted with reperfused AMI to our intensive care unit had a complete CMR study with gadolinium-contrast injection 4 ± 2 days after admission. A global visual score was defined on a 17-segment model and compared with the quantitative planimetric evaluation of hyperenhancement. The peak values of serum Troponin I (TnI) and creatine kinase (CK) release were measured in each patient.

Results

The mean percentage of total left ventricular myocardium with hyperenhancement determined by the quantitative planimetry method was (20.1 ± 14.6) with a range of 1-68%. There was an excellent correlation between quantitative planimetry and visual global scoring for the hyperenhancement extent's measurement (r = 0.94; y = 1.093x + 0.87; SEE = 1.2; P < 0.001) The Bland-Altman plot showed a good concordance between the two approaches (mean of the differences = 1.9% with a standard deviation of 4.7).Mean post-processing time for quantitative planimetry was significantly longer than visual scoring post-processing time (23.7 ± 5.7 min vs 5.0 ± 1.1 min respectively, P < 0.001).Correlation between peak CK and quantitative planimetry was r = 0.82 (P < 0.001) and r = 0.83 (P < 0.001) with visual global scoring. Correlation between peak Troponin I and quantitative planimetry was r = 0.86 (P < 0.001) and r = 0.85 (P < 0.001) with visual global scoring.

Conclusion

A visual approach based on a 17-segment model allows a rapid and accurate assessment of the myocardial global delayed enhancement. This scoring method could be used on a daily practice and useful for the management strategy of post-MI patients.     

Comparison of different quantification methods of late gadolinium enhancement in patients with hypertrophic cardiomyopathy

Aim

There is no consensus regarding the technique of quantification of late gadolinium enhancement (LGE). The aim of the study was to compare different methods of LGE quantification in patients with hypertrophic cardiomyopathy (HCM).

Methods

Cardiac magnetic resonance was performed in 33 patients with HCM. First, LGE was quantified by visual assessment by the team of experienced readers and compared with different thresholding techniques: from 1SD to 6SD above mean signal intensity (SI) of remote myocardium, above 50% of maximal SI of the enhanced area (full-width at half maximum, FWHM) and above peak SI of remote myocardium.

Results

LGE was present in 25 (78%) of patients. The median mass of LGE varied greatly depending on the quantification method used and was highest with the utilization of 1SD threshold [75.5 g, interquartile range (IQR): 63.3-112.3 g] and lowest for FWHM method (8.4 g, IQR: 4.3-13.3 g). There was no difference in mass of LGE as assessed with 6SD threshold and FWHM when compared to visual assessment (p = 0.19 and p = 0.1, respectively); all other thresholding techniques provided significant differences in the median LGE size when compared to visual analysis. Results for all thresholds, except FWHM were significantly correlated with visual assessment with the strongest correlation for 6SD (rho = 0.956, p < 0.0001).

Conclusions

LGE quantification with the use of a threshold of 6SD above the mean SI of the remote myocardium provided the best agreement with visual assessment in patients with HCM.     

Free-breathing, nongated real-time delayed enhancement MRI of myocardial infarcts: a comparison with conventional delayed enhancement

PURPOSE: To compare a free-breathing, nongated, and black-blood real-time delayed enhancement (RT-DE) sequence to the conventional inversion recovery gradient echo (IR-GRE) sequence for delayed enhancement MRI. MATERIALS AND METHODS: Twenty-three patients with suspected myocardial infarct (MI) were examined using both the IR-GRE and RT-DE imaging sequences. The sensitivity and specificity of RT-DE for detecting MI, using IR-GRE as the gold standard, was determined. The contrast-to-noise ratios (CNR) between the two techniques were also compared. RESULTS: RT-DE had a high sensitivity and specificity (94% and 98%, respectively) for identifying MI. The total acquisition time to image the entire left ventricle was significantly shorter using RT-DE than IR-GRE (5.6+/-0.9 versus 11.5+/-1.9 min). RT-DE had a slightly lower infarct-myocardium CNR but a higher infarct-blood CNR than IR-GRE imaging. Compared with IR-GRE, RT-DE accurately measured total infarct sizes. CONCLUSION: RT-DE can be used for delayed enhancement imaging during free-breathing and without cardiac gating.     

Delayed enhancement in hypertrophic cardiomyopathy: comparison with myocardial tagging MRI

PURPOSE: To evaluate the relationship between delayed enhancement (DE) and regional left ventricular function in hypertrophic cardiomyopathy (HCM) using gadolinium enhancement MRI and myocardial tagging MRI. MATERIALS AND METHODS: Cine imaging, delayed enhancement imaging, and tagging MRI were performed in 25 patients with HCM. The location, pattern, and extent of DE were evaluated. Circumferential shortening (Ecc) was obtained by analyzing MR tagging images with HARP software. RESULTS: DE occurred in 21 (84%) patients with a high frequency of localization in the septum and the right ventricular attachment sites. Circumferential shortening was significantly decreased in the enhanced segments compared with nonenhanced segments (P < 0.0001). The myocardial wall was thicker in the enhanced segments than in the nonenhanced segments (P < 0.0001). However, circumferential shortening was significantly decreased in the enhanced segments of the same thickness (P < 0.0001). Circumferential shortening was more substantially impaired in the segments with focal nodular enhancement than those in the segments with ill-defined patchy enhancement (P = 0.0002). CONCLUSION: In HCM, DE is commonly found and circumferential shortening is significantly impaired in the regions with DE, regardless of the degree of myocardial hypertrophy. Focal nodular enhancement is particularly related with regional dysfunction in patients with HCM.     

Does binding of Gd‐DTPA to myocardial tissue contribute to late enhancement in a model of acute myocardial infarction?

The long-lasting signal enhancement by Gd-DTPA in areas of myocardial infarction has been conventionally explained by low perfusion and an enhanced Gd distribution volume. To test whether binding of Gd to myocardial constituents is an additional factor contributing to this effect, Gd-DTPA was allowed to equilibrate between homogenized porcine myocardial tissue and physiological saline. The relaxation rate (1/T(1)) of homogenate samples (n = 61) increased in proportion (r(2) = 0.98) to the Gd concentration (0.025-0.5 mM) of the surrounding medium, with no evidence for augmented uptake. The diffusion-limited uptake was only slightly more rapid than the subsequent Gd-release. The amount of Gd released was in line with all of the Gd-DTPA in the homogenate participating in water proton relaxation. The data from this acute myocardial infarction model do not support the notion that Gd-DTPA binding in the early stages of myocardial damage contributes to delayed enhancement.