Multislice Computed Tomography and Magnetic Resonance Imaging for the Assessment of Reperfused Acute Myocardial Infarction

[Effects of extract of Bulbus Allii Caespitosi on cardiocyte viability of swines with myocardial reperfusion injury evaluated by (18)F-fluorodeoxyglucose positron emission tomography/computed tomography]

OBJECTIVE

To investigate the effects of extract of Bulbus Allii Caespitosi on cardiocyte viability of swines with myocardial reperfusion injury by analyzing the 18F-fluorodeoxyglucose ((18)F-FDG) position emission tomography (PET) imaging.

METHODS

Twenty-four swines were randomly divided into sham-operated group, untreated group, trimethazine group and extract of Bulbus Allii Caespitosi group. Myocardial reperfusion injury was induced by plugging the anterior descending coronary artery of swine with sacculus. Bulbus Allii Caespitosi or trimetazidine was given twice daily for 28 days. Then myocardial perfusion was detected with (18)F-FDG PET/CT and the radioactivity distribution was evaluated.

RESULTS

Compared with the untreated group, Bulbus Allii Caespitosi and trimetazidine could improve the activity of myocardial cells after myocardial infarction (P<0.01), and there were no significant differences between Bulbus Allii Caespitosi and trimetazidine (P>0.05).

CONCLUSION

Bulbus Allii Caespitosi can improve myocardial metabolism after ischemia and reperfusion in swines.

Myocardial ischemia in acute coronary syndrome: assessment using 64-MDCT

OBJECTIVE

We investigated the performance of 64-MDCT myocardial imaging in assessing myocardial ischemia in acute coronary syndrome (ACS).

MATERIALS AND METHODS

Cardiac CT was performed in 35 patients with ACS: 24 patients with acute myocardial infarction (AMI) and 11 patients with unstable angina pectoris (UAP). We reconstructed 2D myocardial images at diastolic and systolic phases using the same raw data as those used for coronary CT angiography. The CT number in the myocardium was used as an estimate of ischemia. The myocardium was shown using a color scale that depicts faint low-density areas more clearly than gray scale. We evaluated the variations in myocardial enhancement during the cardiac cycle in the territory of the culprit lesion. In addition, we classified patients on the basis of the transmurality of myocardial enhancement and examined whether this feature correlates with myocardial damage.

RESULTS

Myocardial imaging at systole showed myocardial hypoenhancement in territories of the culprit lesion in 91% of patients with ACS, 96% of patients with AMI, and 75% of patients with UAP. The hypoenhancement areas at systole tended to be more extensive than those at diastole. The transmural extent of hypoenhancement at systole correlated with myocardial damage, which was shown by myocardial biomarkers.

CONCLUSION

CT myocardial imaging can be used to assess myocardial ischemia in the appropriate region of ACS with high sensitivity.

Relation of plasma brain natriuretic peptide levels on admission for ST-elevation myocardial infarction to left ventricular end-diastolic volume six months later measured by both echocardiography and cardiac magnetic resonance

The main objective of this study was to investigate the relation between brain natriuretic peptide (BNP) levels within the first 96 hours after ST-segment elevation acute myocardial infarction (STEMI) and the development of left ventricular (LV) dilatation at 6-month follow-up. Eighty-two patients with first STEMIs, reperfused within 12 hours of symptom onset, were prospectively included. Plasma BNP was determined on admission and at 1- and 6-month follow-up. Clinically significant LV dilatation, defined as a >20% increase in LV end-diastolic volume at 6-month follow-up, was assessed using echocardiography and cardiac magnetic resonance. Thirty-two percent of patients developed clinically significant LV dilatation. BNP values on admission and at follow-up were significantly higher in patients who developed clinically significant LV dilatation at 6 months (182 +/- 117 vs 106 +/- 91 pmol/ml). After adjusting for age, infarct size, E-wave deceleration time, and the LV ejection fraction, BNP on admission was an independent predictor of LV dilatation, whether assessed by echocardiography (B = 0.075, p = 0.04) or cardiac magnetic resonance (B = 0.085, p = 0.04). In conclusion, high BNP levels on admission and at follow-up predict LV dilatation after STEMI. The early determination of plasma BNP upon admission for STEMI could be helpful in identifying patients at higher risk for LV dilatation, in whom aggressive management is warranted.

[Technological advances in cardiac CT]

The SFR-SFC presents guidelines dedicated to cardiac and coronary imaging using CT in the area of indications, technological requirement including both hardware and software, patient conditioning, CT protocols and related results concerning radiation dose, image quality and diagnostic value. These guidelines are based either on up-dated medical literature proofs and/or on expert consensus.

Integration of Infarct Size, Tissue Perfusion, and Metabolism by Hybrid Cardiac Positron Emission Tomography/Computed Tomography

Background— Hybrid positron emission tomography/computed tomography (PET-CT) allows for combination of PET perfusion/metabolism imaging with infarct detection by CT delayed contrast enhancement. We used this technique to obtain biomorphological insights into the interrelation between tissue damage, inflammation, and microvascular obstruction early after myocardial infarction.

Methods and Results— A porcine model of left anterior descending coronary artery occlusion/reperfusion was studied. Seven animals underwent PET-CT within 3 days of infarction, and a control group of 3 animals was scanned at >4 weeks. Perfusion and glucose uptake were assessed by [ 13 N]-ammonia/[ 18 F]-deoxyglucose (FDG), and 64-slice CT delayed contrast enhancement was measured. In the acute infarct model, CT revealed a no-reflow phenomenon suggesting microvascular obstruction in 80% of all infarct segments. PET showed increased FDG uptake in 68% of the CT-defined infarct segments. Ex vivo staining and histology showed active inflammation in the acute infarct area as an explanation for increased glucose uptake. In chronic infarction, CT showed no microvascular obstruction and agreed well with matched perfusion/metabolism defects on PET.

Conclusions— Perfusion/metabolism PET and delayed enhancement CT can be combined within a single hybrid PET-CT session. Increased regional FDG uptake in the acute infarct area is frequently observed. In contrast to the chronic infarct setting, this indicates tissue inflammation that is commonly associated with microvascular obstruction as identified by no reflow on CT. The consequences of these pathophysiological findings for subsequent ventricular remodeling should be explored in further studies.

History of cardiac computed tomography: single to 320-detector row multislice computed tomography

Since the introduction of computed tomography (CT) over 30 years ago, the challenge of imaging the beating heart has been a driving force in the innovation of cardiac CT. Imaging the anatomy and physiology of the heart demands temporal, spatial and contrast resolution is arguably greater than for any other organ system in the body. Great progress has been achieved in using CT to evaluate coronary artery stenosis and plaque composition. In addition, techniques to evaluate cardiac function, including myocardial perfusion, regional ventricular wall motion, systolic thickening, ejection fraction, valve function, and congenital cardiac abnormalities are also gaining a foothold in clinical practice as adjuncts to or replacements for invasive coronary angiography, cardiac single photon emission CT (SPECT) imaging, ultrasound and magnetic resonance imaging (MRI). This review summarizes the major accomplishments and future directions in this field, with emphasis on developments over the past 10 years.

Magnetic resonance methods and applications in pharmaceutical research

This review presents an overview of some recent magnetic resonance (MR) techniques for pharmaceutical research. MR is noninvasive, and does not expose subjects to ionizing radiation. Some methods that have been used in pharmaceutical research MR include magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) methods, among them, diffusion-weighted MRI, perfusion-weighted MRI, functional MRI, molecular imaging and contrast-enhance MRI. Some applications of MR in pharmaceutical research include MR in metabonomics, in vivo MRS, studies in cerebral ischemia and infarction, degenerative joint diseases, oncology, cardiovascular disorders, respiratory diseases and skin diseases. Some of these techniques, such as cardiac and joint imaging, or brain fMRI are standard, and are providing relevant data routinely. Skin MR and hyperpolarized gas lung MRI are still experimental. In conclusion, considering the importance of finding and characterizing biomarkers for improved drug evaluation, it can be expected that the use of MR techniques in pharmaceutical research is going to increase in the near future.

Timing of adenosine 2A receptor stimulation relative to reperfusion has differential effects on infarct size and cardiac function as assessed in mice by MRI

The activation of adenosine 2A receptors before reperfusion following coronary artery occlusion reduces infarct size and improves ejection fraction (EF). In this study, we examined the effects of delaying treatment with the adenosine 2A receptor agonist ATL146e (ATL) until 1 h postreperfusion. The infarct size and EF were serially assessed by gadolinium-diethylenetriaminepentaacetic acid-enhanced MRI in C57BL/6 mice at 1 and 24 h postreperfusion. The infarct size was also assessed by 2,3,5-triphenyltetrazolium chloride staining at 24 h. Mice were treated with ATL (10 microg/kg ip) either 2 min before reperfusion (early ATL) or 1 h postreperfusion (late ATL) following the 45-min coronary occlusion. The two methods used to assess infarct size at 24 h postreperfusion (MRI and 2,3,5-triphenyltetrazolium chloride) showed an excellent correlation (R=0.96). The risk region, determined at 24 h postreperfusion, was comparable between the control and ATL-treated groups. The infarct size by MRI at 1 versus 24 h postreperfusion was 25+/-1 vs. 26+/-1% of left ventricular mass (means+/-SE) in control mice, 16+/-2 versus 17+/-2% in early-ATL mice, and 24+/-2 versus 25+/-2% in late-ATL mice (intragroup, P=not significant; and intergroup, early ATL vs. control or late ATL, P<0.05). EF was reduced in control mice but was largely preserved between 1 and 24 h in both early-ATL and late-ATL mice (P<0.05). In conclusion, after coronary occlusion in mice, the extent of myocellular death due to ischemia-reperfusion injury is 95% complete within 1 h of reperfusion. The infarct size was significantly reduced by ATL when given just before reperfusion, but not 1 h postreperfusion. Either treatment window helped preserve the EF between 1 and 24 h postreperfusion.

Acute Myocarditis Mimicking Lateral Myocardial Infarction

We report a case of myocarditis mimicking acute lateral myocardial infarction and treated as such initially, which was complicated by ventricular fibrillation a few hours after admission to the intensive care unit. The correct diagnosis was rapidly made using a low-dose delayed-enhanced cardiac multidetector computed tomography scan performed immediately after a normal coronary angiogram, demonstrating typical myocardial late hyperenhancement and good correlation with delayed enhanced magnetic resonance imaging. This case suggests that myocarditis can be accurately diagnosed by delayed-enhanced cardiac multidetector computed tomography in an emergency setting. The other lesson from this case is that patients presenting with severe clinical symptoms, important ECG signs and high myocardial enzyme levels should be closely monitored for at least 72 hours, even when myocardial infarction has been excluded.

Key Issues in the Developing Synergism between Cardiovascular Imaging and Biomarkers

Background: Sophisticated methods of cardiac imaging have the potential to revolutionize the care of patients with cardiovascular disease. The benefits of these state-of-the art imaging techniques can be enhanced by their use in combination with new cardiac biomarkers. This review addresses potentially useful interactions between imaging and biomarkers.

Content: Areas were defined in which the combined use of novel imaging techniques and biomarkers would be most beneficial. This review addresses multiple cardiovascular conditions for which the useful aspects of imaging and biomarkers are likely to be positively synergistic, including acute and chronic ischemic heart disease, heart failure, myocarditis, hypertension, and atherosclerosis.

Conclusions: The synergistic use of imaging techniques and biomarkers will enhance the investigation of many key issues and questions and will be an important resource in the future.

Combined coronary and late-enhanced multidetector-computed tomography for delineation of the etiology of left ventricular dysfunction: comparison with coronary angiography and contrast-enhanced cardiac magnetic resonance imaging

Aims

To evaluate whether comprehensive evaluation of coronary anatomy and delayed enhancement (DE) by multidetector-computed tomography (MDCT) would allow determination of etiology of left ventricular dysfunction (LVD) as compared with coronary angiography (CA) and DE-magnetic resonance (CMR).

Methods and results

Seventy-one consecutive patients (50 males, 59 ± 16 years) with LVD (ejection fraction: 26 ± 11%) of unknown etiology underwent MDCT, LGE (late Gd-DTPA-enhanced)-CMR and CA. Patients were classified into four groups according to coronary artery disease (CAD) by CA and LGE-CMR patterns. Patients (n = 24) with CAD and transmural or sub-endocardial DE by CMR were considered having definite ischaemic LVD (group 1). Patients (n = 36) without CAD by CA and with no/atypical LGE-CMR were considered non-ischaemic LVD (group 2). Further we identified four patients with transmural DE but no CAD (group 3) and seven patients with CAD but no DE (group 4). On per-patient basis, combined coronary and DE-MDCT had excellent agreement (κ = 0.89; P < 0.001) with CA/LGE-CMR to classify patients into the same four groups. Sensitivity, specificity and accuracy of MDCT were 97, 92 and 94%, respectively for detecting patients with definite (group 1) or likely (groups 3 and 4) ischaemic LVD.

Conclusion

Combined coronary and DE-MDCT can accurately differentiate ischaemic vs. non-ischaemic etiology of LVD.

Comparison of MDCT and MRI in the detection and sizing of acute and chronic myocardial infarcts

PURPOSE

This study compared ability of multidetector computed tomography (MDCT) to detect and size the myocardial infarctions (MI) with MRI.

MATERIALS AND METHODS

Eighty examination sets of MDCT and MRI of 63 consecutive patients in the acute stage (average 6.3 days, n=40) and/or chronic stage (average, 11.8 months; n=40) of reperfused MI were examined in this study. The first-pass and delayed MRI was performed using a 1.5 T scanner with an injection of Gd-DTPA to assess the extent of MI. Within 24h after MRI, MDCT was performed at the arterial phase around 25s with a 10-min delay using one of the following scanners: 4-slice, 16-slice, and 40-slice. The volume of the MI over the total myocardial volume was calculated from the MRI and CT images.

RESULTS

MDCT revealed MI lesions in all cases except for one (1.3%) on the early phase images. The percentage volume of the lesion on the MDCT images correlated with that of the MR images. The correlation coefficient between perfusion MRI and early CT was 0.62 (p<0.0001) and the correlation coefficient between the 5-min delay MRI and late CT was 0.81 (p<0.0001). There was no significant difference in the average lesion volume (%) between perfusion MRI (10.8+/-6.7%) and early CT (12.1+/-8.5%) (p>0.05), but there was significant difference between the 5-min delay MRI (25.9+/-12.1%) and late CT (22.8+/-11.8%) (p<0.001).

CONCLUSION

MDCT produces comparable results to MRI in the detection and sizing of acute and chronic MI.

MDCT of the myocardium: a new contribution to ischemic heart disease

RATIONALE AND OBJECTIVES

Despite the progress made in diagnosis and treatment, cardiovascular diseases remain the main cause of death worldwide.

MATERIALS AND METHODS

Multidetector row computed tomography (MDCT) provides several diagnostic insights, namely assessment of coronary artery anatomy and measurement of left ventricular volume and function. The ability of CT to show myocardial infarcted areas as an enhanced territory was described in the late 1970s in an animal model.

RESULTS

This method found a second wind with the arrival of MDCT technology that led to its clinical application. Several authors describe the ability of MDCT to assess myocardial injury both in animals and humans. The MDCT assessment of myocardial late enhancement is based on the same principle as delayed enhancement MRI.

CONCLUSIONS

The aim of this review is to cover the technical aspects of cardiac MDCT in assessing the myocardium and its potential in diagnosing ischemic heart disease.

Association of TIMI myocardial perfusion grade and ST-segment resolution with cardiovascular magnetic resonance measures of microvascular obstruction and infarct size following ST-segment elevation myocardial infarction

BACKGROUND

Impairment of coronary microvascular perfusion is common among patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). Cardiovascular magnetic resonance imaging (CMR) can identify microvascular obstruction (MO) following reperfusion of STEMI. We hypothesized that myocardial perfusion, as assessed by the Thrombolysis in Myocardial Infarction (TIMI) Myocardial Perfusion Grade (TMPG), would be associated with a CMR metric of MO in this population.

METHODS

Twenty-one STEMI patients who underwent successful primary PCI were evaluated. Contrast-enhanced CMR was performed within 7 days of presentation and repeated at three months. TIMI Flow Grade (TFG), corrected TIMI Frame Count (cTFC), TMPG, MO, infarct size, and left ventricular ejection fraction (EF) were assessed.

RESULTS

The median peak creatine phosphokinase (CPK) was 1,775 IU/l (interquartile range 838-3,321). TFG 3 was present following PCI in 19 (90%) patients. CMR evidence of MO was present in 52% following PCI. Abnormal post-PCI TMPG (0/1/2) was present in 48% of subjects and was associated with MO on CMR (90% MO with TMPG 0/1/2 vs. 18% MO with TMPG 3, P < 0.01). Abnormal post-PCI TMPG was also associated with a greater peak CK (median 3,623 IU/l vs. 838 IU/l, P < 0.001) and greater relative infarct size (17.3% vs. 5.2%, P < 0.01).

CONCLUSION

Among STEMI patients undergoing primary PCI, post-PCI TMPG correlates with CMR measures of MO and infarct size. The combined use of both metrics in a comprehensive assessment of microvascular integrity and infarct size following STEMI may aid in the evaluation of future therapeutic strategies.

MRI for the assessment of myocardial viability

Accurate distinction between viable and infarcted myocardium is important for assessment of patients who have cardiac dysfunction. Through the technique of delayed-enhancement MRI (DE-MRI), viable and infarcted myocardium can be simultaneously identified in a manner that closely correlates with histopathology findings. This article provides an overview of experimental data establishing the physiologic basis of DE-MRI-evidenced hyperenhancement as a tissue-specific marker of myocardial infarction. Clinical data concerning the utility of transmural extent of hyperenhancement for predicting response to medical and revascularization therapy are reviewed. Studies directly comparing DE-MRI to other viability imaging techniques are presented, and emerging applications for DE-MRI are discussed.

Imaging techniques in cardiac resynchronization therapy

Cardiac resynchronization therapy is a high cost therapeutic option with proven efficacy on improving symptoms of ventricular failure and for reducing both hospitalization and mortality. However, a significant number of patients do not respond to cardiac resynchronization therapy that is due to various reasons. Identification of the optimal pacing site is crucial to obtain the best therapeutic result that necessitates careful patient selection. Currently, using echocardiography for mechanical dyssynchrony assessment performs patient selection. Multi-Detector-Row Computed Tomography (MDCT) and Magnetic Resonance Imaging (MRI) are new imaging techniques that may assist the cardiologist in patient selection. These new imaging techniques have the potential to improve the success rate of cardiac resynchronization therapy, due to pre-interventional evaluation of the venous coronary anatomy, to evaluation of the presence of scar tissue, and to improved evaluation of mechanical dyssynchrony. In conclusion, clinical issues associated with heart failure in potential candidates for cardiac resynchronization therapy, and the information regarding this therapy that can be provided by the imaging techniques echocardiography, MDCT, and MRI, are reviewed.

The Emerging Role of Multi-Detector Computed Tomography in Heart Failure

BACKGROUND

Recent advances in cardiac multi-detector computed tomography (MDCT) technology now permits entire coronary tree evaluation in a single breath hold with submillimeter slice collimation and improved temporal resolution.

METHODS AND RESULTS

Besides excellent correlation with invasive angiogram for the detection of significant coronary occlusion, MDCT also provides reliable and reproducible data regarding various other cardiac anatomic and functional parameters that are pertinent to heart failure patients. These include left ventricular measurement (eg, ejection fraction, regional wall motion, dimensions, volumes), pulmonary vein anatomy and drainage, right ventricular function, and cardiac venous system, among many others. However, there are radiogenic and nonradiogenic risks associated with MDCT that should be considered before scanning the patients.

CONCLUSIONS

This review summarizes the existing literature of the various cardiac MDCT applications pertinent to heart failure patients.

Low Tube Voltage Improves Computed Tomography Imaging of Delayed Myocardial Contrast Enhancement in an Experimental Acute Myocardial Infarction Model

OBJECTIVE

We sought to evaluate the influence of tube voltage on the visualization of acute myocardial infarction (MI) in cardiac multislice spiral computed tomography (MSCT).

MATERIALS AND METHODS

Acute MI was induced in 12 domestic pigs by a 45-minute balloon occlusion of the left anterior descending artery. Delayed enhancement magnetic resonance imaging was performed 15 minutes after the injection of 0.2 mmol/kg Gd-DTPA. On the same day, retrospectively ECG-gated MSCT was performed at 120, 100, and 80 kV (16x0.75mm, 550mAseff.) 15 minutes after the injection of 140 mL of iopromide (1 g/iodine/kg). The pigs were killed and the hearts were excised and stained with 2,3,5-triphenyltetrazolium chloride. The area of acute MI, contrast-to-noise ratio (CNR), and percent signal difference were compared among the different imaging techniques by applying Bland-Altman plots and 2-way analysis of variance.

RESULTS

On MSCT at 120, 100, and 80 kV, the respective mean acute MI sizes were 18.4+/-11.4%, 19.3+/-11.5%, and 20.5+/-11.6%. The mean MI sizes were 20.8+/-12.2% and 20.1+/-12.4% on magnetic resonance imaging and 2,3,5-triphenyltetrazolium chloride staining. Analysis of variance did not show any statistically significant differences between the different techniques with respect to the size of acute MI (P=0.9880). Comparing the different kV settings on MSCT, the highest percent signal difference (74.7+/-12.1%) and the highest CNR (6.7+/-1.8) between infarcted and healthy remote myocardium were achieved at 80 kV.

CONCLUSIONS

When compared with routine scan protocols, low tube voltage MSCT allows for the assessment of the MI size with an improved CNR and contrast resolution. This technique appears to be advantageous for assessing myocardial viability from contrast enhanced late-phase MSCT.

Late-phase MSCT in the different stages of myocardial infarction: animal experiments

The purpose of this study was to intraindividually evaluate myocardial late enhancement on multislice spiral computed tomography (MSCT) for the assessment of the different stages of myocardial infarction (MI) in comparison with magnetic resonance (MR) imaging. Reperfused MI was successfully induced in seven pigs. Delayed enhancement MR imaging and late-phase MSCT were performed on day 0 as well as 7, 28 and 90 days after the procedure. The pigs were sacrificed, and 2,3,5-triphenyltetrazolin-chloride (TTC) staining was acquired. MI size was compared between the different imaging techniques and over time applying Bland-Altman plots and multivariate analysis with repeated measures. On day 0 the mean MI size was 23.7 +/- 11.8% of the left ventricular area on MSCT and 24.5 +/- 10.6% on MR imaging. On day 90 infarct sizes decreased significantly to 16.9 +/- 8.4% and 18.9 +/- 8.0%, respectively (P = 0.0019). On TTC staining the size of MI was 16.8 +/- 8.2%. Bland-Altman plots showed a good agreement between MSCT and MR imaging with mean deviations ranging from -3.4% to -1.9%. No significant difference between MSCT and MR imaging was found. Myocardial late enhancement on MSCT correlates well with delayed enhancement MR imaging during the different stages of MI and allows for reliable assessment of reperfused MI during acute, subacute and chronic stages.

MRI for the Assessment of Myocardial Viability

Accurate distinction between viable and infarcted myocardium is important for assessment of patients who have cardiac dysfunction. Through the technique of delayed-enhancement MRI (DE-MRI), viable and infarcted myocardium can be simultaneously identified in a manner that closely correlates with histopathology findings. This article provides an overview of experimental data establishing the physiologic basis of DE-MRI-evidenced hyperenhancement as a tissue-specific marker of myocardial infarction. Clinical data concerning the utility of transmural extent of hyperenhancement for predicting response to medical and revascularization therapy are reviewed. Studies directly comparing DE-MRI to other viability imaging techniques are presented, and emerging applications for DE-MRI are discussed.

Assessment of Myocardial Microvascular Function: New Opportunities in Fast Computed Tomography

It has been increasingly recognized that the initial site of cardiac damage in several forms of cardiovascular disease resides in the microcirculation. Noninvasive or minimally invasive evaluation of myocardial microvascular functional attributes, such as myocardial perfusion or microvascular permeability, could be an invaluable tool in the clinical practice. Advances in the field of computed tomography over the past three decades culminated in the advent of fast scanners, which show promise to provide both fine cardiac anatomic detail and quantification of the function of the myocardial microcirculation. This review describes the approach and utility of measurements of myocardial microvascular function obtained with state-of-the-art cardiac computed tomography.

Sixty-four-MSCT in the characterization of porcine acute and subacute myocardial infarction: determination of transmurality in comparison to magnetic resonance imaging and histopathology

OBJECTIVE

The aim of this study was to assess the accuracy of MSCT in characterizing myocardial infarction (MI) and, thereby, determine the extent of early perfusion defect (ED), microvascular obstruction (MO) and transmural depth of late enhancement (LE) in comparison to MRI and histology.

MATERIALS AND METHODS

Seven pigs were studied with MSCT (Somatom Sensation 64) and MRI (Magnetom Sonata) a median 1 and 21 days following temporary occlusion of a diagonal branch and creation of small reperfused infarction. For depiction of ED, CT images were acquired in the early arterial phase and following 35 s; LE and MO were evaluated on images obtained at 3, 5, 10 and 15 min. Thereby, a bolus/low-flow contrast injection protocol was used. Triphenyltetrazolium-chloride (TTC) stain and histology were obtained. Volumes of enhancement patterns were assessed as percentage of the ventricle and compared by Bland-Altman analysis. Segmental co-localization and graded transmurality was evaluated with weighted-kappa-test.

RESULTS

Close spatial agreement was observed for MRI-MO and MSCT-MO (bias=0.55; CI=-1.49 to 2.60 at 5 min MSCT), TTC and MSCT-LE (bias=-1.28; CI=-3.76 to 1.19) or MRI-LE and MSCT-LE (bias=-0.79; CI=-4.19 to 2.60). There was good segmental co-localization for MO (weighted kappa=0.93) and high agreement for transmural extent of TTC, MRI-LE and MSCT-LE (weighted kappa=0.84 TTC versus MSCT; 0.86 MRI versus MSCT). Arterial and 35s ED significantly underestimated infarct size and showed poor segmental or transmural agreement (weighted kappa=0.33; 0.44).

CONCLUSIONS

MSCT late-scans not only reliably depict size of MO and LE in acute or subacute infarct phases but, moreover, allow for accurate determination of LE transmurality.