Detection Of Intramyocardial Hemorrhage Research Articles

Прижиттєва діагностика інтраміокардіальної геморагії в пацієнтів з інфарктом міокарда зі стійким підйомом сегмента ST: поширеність, зв’язок з функцією ендотелію та значення для розвитку післяінфарктної дилатації лівого шлуночка

Мета роботи – визначити поширеність та основні чинники ризику інтраміокардіальної геморагії (ІМГ) у своєчасно реваскуляризованих хворих із гострим інфарктом міокарда (ГІМ) зі стійким підйомом сегмента ST, а також оцінити її значення для розвитку післяінфарктної дилатації лівого шлуночка (ЛШ).Матеріали і методи. Обстежено 24 пацієнтів з першим ГІМ передньої локалізації зі стійким підйомом сегмента ST, яких госпіталізували в перші 6 год (у середньому (2,8±1,4) год) від розвитку захворювання. Наявність ІМГ оцінювали методом магнітно-резонансної томографії (МРТ) з гадолінієвим контрастуванням на 3-тю–4-ту добу ГІМ. Ехокардіографічне дослідження виконували в 1-шу, на 10-ту та 90-ту добу ГІМ, пробу з потокозалежною вазодилатацією – в 1-шу добу ГІМ.Результати та обговорення. Більше третини (37,5 %) пацієнтів з ГІМ передньої локалізації зі стійким підйомом сегмента ST, яким була проведена первинна перкутанна транслюмінальна коронарна ангіопластика (ПТКА), мали ознаки ІМГ. Геморагічна трансформація ГІМ частіше виявлялася у хворих, яким на догоспітальному етапі призначали еноксапарин (відносний ризик (ВР) 3,75; 95 % довірчий інтервал (ДІ) 1,47–9,56) та рідше – в пацієнтів із багатосудинним ураженням коронарних артерій (ВР 0,21; 95 % ДІ 0,03–1,00). Відзначено тенденцію до частішого виявлення ІМГ у хворих із дисфункцією ендотелію. Приріст діаметра плечової артерії ≤ 4,9 % при проведенні проби з потокозалежною вазодилатацією свідчив про схильність до розвитку ІМГ (ВР 3,5; 95 % ДІ 0,9–13,5). Наявність ІМГ асоціювалася з більшою масою некротизованого міокарда та частішим розвитком післяінфарктної дилатації ЛШ (ВР 5,0; 95 % ДІ 1,3–19,7). Додавання до стандартної базисної терапії ГІМ внутрішньовенної форми кверцетину супроводжувалося зниженням імовірності геморагічної трансформації інфаркту міокарда (ВР 0,21; 95 % ДІ 0,03–1,00).Висновки. Предикторами розвитку ІМГ після первинної ПТКА у хворих з ГІМ зі стійким підйомом сегмента ST були догоспітальне введення еноксапарину та ендотеліальна дисфункція, тоді як при багатосудинному (≥ 3) ураженні коронарних артерій ІМГ реєстрували значно рідше. Наявність ІМГ асоціювалася з більшою масою некротизованого міокарда та частішим розвитком післяінфарктної дилатації та дисфункції ЛШ.

138 Head on Comparison of Two Novel Techniques for the Detection of Intramyocardial Haemorrhage

Background A variety of CMR methods for detecting intramyocardial haemorrhage (IMH) has been proposed, including T2-weighted imaging (T2w), T2-mapping and T2* mapping. IMH detected by T2w imaging is associated with adverse LV remodelling and adverse outcome post acute myocardial infarction (MI). We compare the sensitivity, specificity, CNR and SNR of the three IMH imaging techniques. Methods Twenty patients underwent CMR at 3T (Achieva TX system, Philips Healthcare, Best, The Netherlands) within 3 days following reperfused ST-elevation MI. Black blood, cine, T2w, T2-mapping, T2*-mapping and LGE imaging (0.1 mmol/kg gadolinium DTPA) were performed in identical short axis locations using the ‘3 of 5’ approach. Data were evaluated offline using commercial software (cvi42 v4.1.5, Circle Cardiovascular Imaging Inc., Calgary, Canada). On the LGE images showing the largest infarct volume, infarct size was determined by using a semi-automated histogram-based thresholding method. This slice was evaluated for visual presence of IMH by the three methods. Signal intensity (SI) and respective standard deviation of SI (SD) were measured for the infarcted myocardium, remote myocardium and any IMH (if present). SNR was computed for each using the formula = 0.655((SI)/(SD)). CNR was determined comparing contrast-to-noise of infarcted myocardium to IMH (SNRi-SNRIMH). Results Of the twenty patients, 55% (n = 11) had IMH on T2w-imaging. The mean (±standard deviation) SNR and CNR values are listed in Table 1. The visual assessment of T2w imaging correlated strongly to T2-maps (r = 0.69; p = 0.001) and to the T2*-maps (r = 0.60; p = 0.005). The SNR for IMH and infarct zone were significantly different for only T2w imaging (Figure 1). Quantitative CNR for T2w imaging correlated strongly to visual assessment of all three imaging modalities (T2w- r = 0.650; p = 0.002, T2-map- r = 0.454; p = 0.04, T2*-map- r = 0.603; p = 0.005). The CNR for T2-maps and T2*-maps did not show similar correlation to the visual assessment. Conclusion Quantitative and qualitative T2w-imaging assessment for IMH is superior to T2-mapping and T2*mapping.

Imaging of reperfused intramyocardial hemorrhage with cardiovascular magnetic resonance susceptibility weighted imaging (SWI).

PurposeTo report initial experience with TE-averaged susceptibility weighted imaging (SWI) in normal subjects and acute myocardial infarction (AMI) patients for the detection of intramyocardial hemorrhage (IMH).Materials and Methods15 healthy control and 11 AMI subjects were studied at 1.5T before contrast agent administration with a dark blood double inversion recovery multiple spoiled gradient-echo sequence. Magnitude, susceptibility weighted and TE-averaged images were reconstructed from raw data. Contrast and signal-difference-to-noise were measured and compared between methods for IMH detection.ResultsThere were six patients with microvascular obstruction (MVO) and four patients with IMH detected by TE-averaged SWI imaging. All patients with IMH on SWI scans had MVO on late gadolinium-enhanced (LGE) imaging. There was a three-fold increase in IMH contrast with SWI compared to magnitude images. IMH contrast decreased and signal-to-noise increased with increased TE averages.ConclusionsTE-averaged SWI imaging is a promising method for myocardial tissue characterization in the setting of AMI for the detection of IMH. Along with gray-scale colormap inversion, it combines not only magnitude and phase information, but also images across TEs to provide a single image sensitive to IMH with characteristics similar to LGE imaging.

Clinical validation of susceptibility-weighted cardiovascular magnetic resonance in comparison to T2 and T2* imaging for detection of intramyocardial hemorrhage following acute myocardial infarction

Background Intramyocardial hemorrhage (IMH) identified by CMR is an established prognostic marker following acute myocardial infarction (AMI), but remains relatively underused in the clinical setting. Detection of IMH by T2-weighted or T2* CMR can be limited by long breath hold times and sensitivity to artefacts, especially at 3 Tesla. Alternative methods that can detect IMH with shorter breath hold times are therefore desirable. CMR is capable of detecting differences in the magnetic susceptibility of tissues. The paramagnetic properties of hemoglobin products within IMH cause local phase shifts relative to surrounding tissue. Phase data can be filtered and combined with magnitude data to generate susceptibility weighted MR images (SW MRI). SW imaging has been shown to be highly sensitive for the detection of cerebral hemorrhage, but typically uses long echo times, resulting in prolonged image acquisition. With the larger size of IMH, we hypothesized that SW MRI may be used with shorter echo times, leading to rapid imaging with breath hold times of approximately 4 seconds. We compared the image quality and diagnostic ability of this SW MRI pulse sequence with T2-weighted and T2* CMR to detect IMH at 3T. Methods

T2-mapping and T2*-mapping for detection of intramyocardial haemorrhage: a head-to-head comparison with T2-weighted imaging

Methods Twenty patients underwent CMR at 3T (Achieva TX system, Philips Healthcare, Best, The Netherlands) within 3 days following reperfused ST-elevation MI. Black blood, cine, T2w, T2-mapping, T2*-mapping and LGE imaging (0.1mmol/kg gadolinium DTPA) were performed in identical short axis locations using the ‘3 of 5’ approach. Data were evaluated offline using commercial software (cvi42 v4.1.5, Circle Cardiovascular Imaging Inc., Calgary, Canada). On the LGE images showing the largest infarct volume, infarct size was determined by using a semi-automated histogram-based thresholding method. This slice was evaluated for visual presence of IMH by the three methods. Signal intensity (SI) and respective standard deviation of SI (SD) were measured for the infarcted myocardium, remote myocardium and any IMH (if present). SNR was computed for each using the formula=0.655((SI)/(SD)). CNR was determined comparing contrast-to-noise of infarcted myocardium to IMH (SNRi-SNRIMH). Results Of the twenty patients, 55% (n=11) had IMH on T2wimaging. The mean (±standard deviation) SNR and CNR values are listed in Table 1. The visual assessment of T2w imaging correlated strongly to T2-maps (r=0.69; p=0.001) and to the T2*-maps (r=0.60; p=0.005). The SNR for IMH and infarct zone were significantly different for only T2w imaging (Figure 1). Quantitative CNR for T2w imaging correlated strongly to visual assessment of all three imaging modalities (T2wr=0.650; p=0.002, T2-mapr=0.454; p=0.04, T2*-mapr=0.603;p=0.005). The CNR for T2-maps and T2*-maps did not show similar correlation to the visual assessment.

Detection of Acute Reperfusion Myocardial Hemorrhage with Cardiac MR Imaging: T2 versus T2*

To evaluate T2 and T2* changes in acute reperfused hemorrhagic and nonhemorrhagic myocardial infarctions and to determine which technique is more suitable in the detection of intramyocardial hemorrhage at 1.5 T. Patient studies were approved by the institutional review board and were HIPAA compliant. Patients (n = 14, three women) with first ST-elevation myocardial infarction underwent cardiac magnetic resonance (MR) imaging 3 days after angioplasty. T2* maps, T2 short inversion time inversion-recovery (STIR) images, and late gadolinium enhancement (LGE) images were acquired. Animal studies were approved by the institutional animal care and use committee. Canines (n = 20) were subjected to ischemia-reperfusion injury, and cardiac MR imaging was performed 5 days after reperfusion. T2* and T2 maps and T2 STIR and LGE images were acquired. Repeated-measures analysis of variance or the Friedman test was used to compare T2 and T2* changes in patients with hemorrhagic infarctions and those with nonhemorrhagic infarctions. Relative to remote myocardium, mean T2* of hemorrhagic infarctions was 54% ± 13 (standard deviation) lower in patients (15.9 msec ± 4.5 vs 35.2 msec ± 2.1, P < .001) and 40% ± 10 lower in canines (23.0 msec ± 4.0 vs 39.3 msec ± 2.5, P < .001). Mean T2* of nonhemorrhagic infarctions was marginally elevated by 6% ± 2.5 (37.8 msec ± 2.5, P = .021) in patients and by 8% ± 5 (44.6 msec ± 4.8, P = .012) in canines. In contrast, mean T2 STIR signal intensity (SI) of both hemorrhagic infarctions and nonhemorrhagic infarctions was higher than that in remote myocardium both in patients (hemorrhagic: 37% ± 19, P < .001; nonhemorrhagic: 78% ± 27, P < .001) and in canines (hemorrhagic: 42% ± 22, P < .001; nonhemorrhagic: 65% ± 22, P < .001). Consistent with STIR SI findings, mean T2 of both hemorrhagic (62.0 msec ± 4.9) and nonhemorrhagic (71.7 msec ± 7.3) infarctions in canines was elevated relative to mean T2 of remote myocardium (52.1 msec ± 4.8) by 18% ± 9 and 38% ± 13, respectively (P < .001 for both). T2* cardiac MR imaging is more suitable than T2 cardiac MR imaging in the detection and characterization of acute reperfusion myocardial hemorrhage. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122397/-/DC1.

Detection of Acute Reperfusion Myocardial Hemorrhage with Cardiac MR Imaging: T2 versus T2*

To evaluate T2 and T2* changes in acute reperfused hemorrhagic and nonhemorrhagic myocardial infarctions and to determine which technique is more suitable in the detection of intramyocardial hemorrhage at 1.5 T. Patient studies were approved by the institutional review board and were HIPAA compliant. Patients (n = 14, three women) with first ST-elevation myocardial infarction underwent cardiac magnetic resonance (MR) imaging 3 days after angioplasty. T2* maps, T2 short inversion time inversion-recovery (STIR) images, and late gadolinium enhancement (LGE) images were acquired. Animal studies were approved by the institutional animal care and use committee. Canines (n = 20) were subjected to ischemia-reperfusion injury, and cardiac MR imaging was performed 5 days after reperfusion. T2* and T2 maps and T2 STIR and LGE images were acquired. Repeated-measures analysis of variance or the Friedman test was used to compare T2 and T2* changes in patients with hemorrhagic infarctions and those with nonhemorrhagic infarctions. Relative to remote myocardium, mean T2* of hemorrhagic infarctions was 54% ± 13 (standard deviation) lower in patients (15.9 msec ± 4.5 vs 35.2 msec ± 2.1, P < .001) and 40% ± 10 lower in canines (23.0 msec ± 4.0 vs 39.3 msec ± 2.5, P < .001). Mean T2* of nonhemorrhagic infarctions was marginally elevated by 6% ± 2.5 (37.8 msec ± 2.5, P = .021) in patients and by 8% ± 5 (44.6 msec ± 4.8, P = .012) in canines. In contrast, mean T2 STIR signal intensity (SI) of both hemorrhagic infarctions and nonhemorrhagic infarctions was higher than that in remote myocardium both in patients (hemorrhagic: 37% ± 19, P < .001; nonhemorrhagic: 78% ± 27, P < .001) and in canines (hemorrhagic: 42% ± 22, P < .001; nonhemorrhagic: 65% ± 22, P < .001). Consistent with STIR SI findings, mean T2 of both hemorrhagic (62.0 msec ± 4.9) and nonhemorrhagic (71.7 msec ± 7.3) infarctions in canines was elevated relative to mean T2 of remote myocardium (52.1 msec ± 4.8) by 18% ± 9 and 38% ± 13, respectively (P < .001 for both). T2* cardiac MR imaging is more suitable than T2 cardiac MR imaging in the detection and characterization of acute reperfusion myocardial hemorrhage. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122397/-/DC1.

Detection of intramyocardial hemorrhage using high‐field proton (1h) nuclear magnetic resonance imaging

Proton (1H) nuclear magnetic resonance (NMR) imaging has been used to define zones of myocardial infarction (MI), which appear as areas of relatively increased signal intensity (SI). However, zones of decreased SI have been observed within the areas of infarction and have been postulated to result from intramyocardial hemorrhage. To explore this phenomenon further, ex vivo spin-echo 1H NMR imaging at 1.5 Tesla was performed in 17 dogs after 24 hr (n = 9) and after 72 hr (n = 8) of coronary artery occlusion. In all dogs, a zone of increased SI (118 +/- 9% compared with normal myocardium) was observed in the distribution of the occluded coronary artery. In 12 of the 17 dogs, zones of decreased SI (92 +/- 8% compared with normal) were seen within or around the central zone of increased SI. Gross inspection and histological assessment of sliced myocardium usually disclosed hemorrhage in the regions of decreased SI. In three of the five dogs with no apparent zones of decreased SI on NMR, the infarct was small, and only minor hemorrhage was observed by gross inspection, whereas in the remaining two dogs no hemorrhage was seen. Myocardial flow in the hemorrhagic regions was significantly higher than in the necrotic core (59 +/- 29% vs. 31 +/- 24% compared with control, P less than 0.05). Image-derived calculation of T2 relaxation times in the different infarcted regions revealed a significant shortening of T2 in the infarcted hemorrhagic zones with decreased SI compared with the infarct zones with increased SI (49 +/- 8 msec vs. 66 +/- 8 msec, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)