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Thomas J Brady

Publications and source records attributed to Thomas J Brady.

At least 19 recordsLinked to original sources
PubMed2006

Coronary multidetector computed tomography in the assessment of patients with acute chest pain.

BACKGROUND: Noninvasive assessment of coronary atherosclerotic plaque and significant stenosis by coronary multidetector computed tomography (MDCT) may improve early and accurate triage of patients presenting with acute chest pain to the emergency department. METHODS AND RESULTS: We conducted a blinded, prospective study in patients presenting with acute chest pain to the emergency department between May and July 2005 who were admitted to the hospital to rule out acute coronary syndrome (ACS) with no ischemic ECG changes and negative initial biomarkers. Contrast-enhanced 64-slice MDCT coronary angiography was performed immediately before admission, and data sets were evaluated for the presence of coronary atherosclerotic plaque and significant coronary artery stenosis. All providers were blinded to MDCT results. An expert panel, blinded to the MDCT data, determined the presence or absence of ACS on the basis of all data accrued during the index hospitalization and 5-month follow-up. Among 103 consecutive patients (40% female; mean age, 54+/-12 years), 14 patients had ACS. Both the absence of significant coronary artery stenosis (73 of 103 patients) and nonsignificant coronary atherosclerotic plaque (41 of 103 patients) accurately predicted the absence of ACS (negative predictive values, 100%). Multivariate logistic regression analyses demonstrated that adding the extent of plaque significantly improved the initial models containing only traditional risk factors or clinical estimates of the probability of ACS (c statistic, 0.73 to 0.89 and 0.61 to 0.86, respectively). CONCLUSIONS: Noninvasive assessment of coronary artery disease by MDCT has good performance characteristics for ruling out ACS in subjects presenting with possible myocardial ischemia to the emergency department and may be useful for improving early triage.

Acute Disease↗
PubMed2006

Comparison of sixty-four-slice multidetector computed tomographic coronary angiography to coronary angiography with intravascular ultrasound for the detection of transplant vasculopathy.

Coronary allograft vasculopathy (CAV) is the most important limitation to long-term survival in adult heart transplant recipients and is difficult to detect without intravascular ultrasound (IVUS). We systematically evaluated the image quality of 64-slice multidetector computed tomographic (MDCT) coronary angiography in heart transplant recipients and tested the hypothesis that this modality is comparable to invasive coronary angiography with IVUS for the detection of CAV. Heart transplant recipients (n = 20) underwent invasive coronary angiography with IVUS and MDCT coronary angiography with a 64-slice scanner. Images were systematically analyzed for image quality and the presence of CAV. In addition, multidetector computed tomography and quantitative coronary angiography were used to measure lumen diameters at prespecified locations. Image quality analysis showed that, despite high mean heart rates (77 +/- 7 beats/min) and body mass index (29.5 +/- 5.3 kg/m(2)), 83% of coronary segments were graded as of excellent or good image quality. On average, 95 +/- 9% of the overall visualized length of the coronary arteries was imaged without motion artifacts, and the mean contrast-to-noise ratio was 11.3 +/- 4.6. Compared with IVUS, multidetector computed tomography had a sensitivity of 70%, specificity of 92%, positive predictive value of 89%, and negative predictive value of 77% for the detection of CAV. MDCT vessel diameter measurements correlated well with those obtained from quantitative coronary angiography (R(2) = 0.89). In conclusion, 64-slice multidetector computed tomography provides good to excellent image quality in heart transplant recipients and has moderate to excellent test characteristics for the detection of CAV. Further, MDCT measurements of lumen diameters correlated well with quantitative coronary angiography.

Body Mass Index↗
PubMed2006

Arterial wall imaging: evaluation with 16-section multidetector CT in blood vessel phantoms and ex vivo coronary arteries.

PURPOSE: To evaluate the diagnostic performance of 16-section multidetector computed tomography (CT) for assessment of plaques in phantoms and ex vivo coronary arteries, with intravascular ultrasonography (US) and optical coherence tomography (OCT) as reference standards. MATERIALS AND METHODS: Research protocol was HIPAA compliant and approved by institutional review board, without informed consent required. Blood vessel and lesion composition phantoms and ex vivo coronary arteries were imaged with 16-section CT. Wall areas of phantoms and ex vivo coronary arteries were measured with multidetector CT and intravascular US. Sensitivity and specificity for lipid detection were determined in lesion composition phantoms. CT numbers of blood vessel wall were determined in ex vivo coronary arteries and compared with lesion classification results from OCT. Agreement in dimensional measurements was compared (paired t tests). CT numbers within blood vessel wall of CT cross sections classified as lipid rich, fibrous, and calcified at OCT were compared (Kruskal-Wallis tests). RESULTS: Mean blood vessel wall areas measured with CT and US in phantoms were 9.2 mm(2) +/- 1.8 (standard deviation) and 10.4 mm(2) +/- 3.4 (bias, -1.3 mm(2) +/- 3.1; P < .05), respectively. Mean blood vessel wall areas measured in ex vivo coronary arteries with CT and US were 10.9 mm(2) +/- 4.1 and 9.1 mm(2) +/- 3.1 (bias, 1.8 mm(2) +/- 3.0; P < .001), respectively. Sensitivity and specificity of 93% and 92%, respectively, for identification of lipid-rich lesions were observed in lesion composition phantoms. Mean CT numbers in blood vessel wall of ex vivo coronary arteries identified at OCT as predominantly lipid rich, fibrous, and calcified were 29 HU +/- 43, 101 HU +/- 21, and 135 HU +/- 199, respectively (P < .001). CONCLUSION: Determination of composition of individual plaques from attenuation values can be more challenging because of overlapping values for different tissue types.

Coronary Angiography↗
PubMed2006

Differentiation of recent and chronic myocardial infarction by cardiac computed tomography.

Clinical use of cardiac computed tomography is rapidly expanding, and its purpose may reach beyond noninvasive coronary angiography. We investigated the ability of 64-slice multidetector computed tomography to differentiate between recent and long-standing myocardial infarction (MI). Contrast-enhanced coronary computed tomographic (CT) scans (Siemens Sensation 64) of patients with a recent MI (< 7 days, n = 16), long-standing MI (> 12 months, n = 13), and no MI (n = 13) were retrospectively evaluated. To anticipate transmural variation of myocardial perfusion and to neutralize image noise, a series of thin, overlapping slices was created in parallel alignment to the myocardial wall. Within each of these slices, a small region of interest was placed at a constant in-plane position to measure the CT attenuation (Hounsfield units [HU]) at consecutive transmural locations of injured and normal remote myocardium. In addition, wall thickness and the myocardial cavity were measured. Significantly lower CT attenuation values were found in patients with long-standing MI (-13 +/- 37 HU) than in those with acute MI (26 +/- 26 HU) and normal controls (73 +/- 14 HU, p < 0.001). The attenuation difference between infarcted and remote myocardia was larger in patients with long-standing MI than in patients with recent MI (89 +/- 41 and 55 +/- 33 HU, respectively, p < 0.001). In addition, long-standing MI was associated with wall thinning (p < 0.01), and ventricular dilation (p < 0.05), whereas recent MI was not (p > 0.05). In conclusion, recent and long-standing MIs may be differentiated by computed tomography based on myocardial CT attenuation values and ventricular dimensions.

Coronary Angiography↗
PubMed2006

Noninvasive assessment of plaque morphology and composition in culprit and stable lesions in acute coronary syndrome and stable lesions in stable angina by multidetector computed tomography.

OBJECTIVES: The purpose of this study was to assess morphology and composition of culprit and stable coronary lesions by multidetector computed tomography (MDCT). BACKGROUND: Noninvasive identification of culprit lesions has the potential to improve noninvasive risk stratification in patients with acute chest pain. METHODS: Thirty-seven patients with acute coronary syndrome (ACS) or stable angina underwent coronary 16-slice MDCT and invasive selective angiography. In all significant coronary lesions two observers measured the degree of stenosis, plaque area at stenosis, and remodeling index and assessed plaque composition. Differences between culprit lesions in patients with ACS and stable lesions in patients with ACS or stable angina were determined. RESULTS: We analyzed 40 lesions with excellent image quality in 14 patients with ACS and 9 patients with stable angina. Culprit lesions in patients with ACS (n = 14) had significantly greater plaque area and a higher remodeling index than both stable lesions in patients with ACS (n = 13) and in patients with stable angina (n = 13) (17.5 +/- 5.9 mm2 vs. 9.1 +/- 4.8 mm2 vs. 13.5 +/- 10.7 mm2, p = 0.02; and 1.4 +/- 0.3 vs. 1.0 +/- 0.4 vs. 1.2 +/- 0.3, p = 0.04, respectively). The prevalence of non-calcified plaque was 100%, 62%, and 77%, respectively, and the prevalence of calcified plaque was 71%, 92%, and 85%, respectively, in culprit lesions in patients with ACS and in stable lesions in patients with ACS or stable angina. CONCLUSIONS: We introduce the concept of noninvasive detection and characterization of coronary atherosclerotic lesions in patients with ACS by MDCT. We identified differences in lesion morphology and plaque composition between culprit lesions in ACS and stable lesions in ACS or stable angina, consistent with previous intravascular ultrasound studies.

Acute Disease↗
PubMed2006

Characterization of non-calcified coronary atherosclerotic plaque by multi-detector row CT: comparison to IVUS.

UNLABELLED: Multi-detector row Computed Tomography (MDCT) permits non-invasive visualization of the coronary arteries. The ability to visualize and, with limitations, to characterize non-calcified coronary atherosclerotic plaque has been described. We investigated the CT attenuation of non-calcified plaques as determined by 16-slice MDCT in comparison to intravascular ultrasound (IVUS). METHODS AND RESULTS: Thirty-two patients were investigated by contrast-enhanced 16-slice CT. In addition, IVUS of one coronary artery (motorized pullback) was performed (LM+LAD: 22, LM+LCX: 4, RCA: 6). At 252 sites within the coronary system, in which non-calcified atherosclerotic plaque could be identified both in MDCT and IVUS, the CT attenuation within the plaque was measured using a centrally placed region of interest and correlated to the appearance of the plaque in IVUS at the corresponding location. The mean CT attenuation within plaque that corresponded to hyper-echogenic appearance in IVUS was 121+/-34HU (n=76). The mean CT attenuation within plaque that corresponded to hypo-echogenic appearance was 58+/-43HU (n=176, p<0.001). However, there was substantial overlap of the density values measured by MDCT in the two groups. CONCLUSIONS: A significant difference of the mean CT attenuation within atherosclerotic lesions of hypo-echogenic and hyper-echogenic appearance in IVUS could be observed. However, we observed substantial overlap of attenuation values between plaque types so that the differentiation of "vulnerable" and "stable" plaques based on their CT attenuation is doubtful.

Aged↗
PubMed2006

Accuracy of 16-slice multi-detector CT to quantify the degree of coronary artery stenosis: assessment of cross-sectional and longitudinal vessel reconstructions.

BACKGROUND: Sixteen-slice multi-detector computed tomography (MDCT) permits reliable noninvasive detection of significant coronary stenosis based on qualitative visual assessment. The purpose of this study was to determine the accuracy of MDCT to quantify the degree of coronary stenosis as compared to quantitative coronary angiography (QCA) using two different reconstruction methods. METHODS: We studied 69 coronary artery lesions from 38 consecutive patients that underwent 16-slice MDCT as a part of research study, which enrolled consecutive subjects scheduled for clinically indicated invasive coronary angiography. Nine coronary artery lesions with motion artifacts, heavily calcified plaques or stents were excluded from the analysis. The degree of stenosis was calculated by two independent readers non-blinded to the location of the stenosis, but blinded to the results of the QCA. MDCT luminal diameters were measured in cross-sectional multi-planar reformatted (CS-MPR) images created perpendicular to the centerline of the vessel and in 5 mm thin-slab maximum intensity projections (MIP) parallel to the long axis of the vessel. Both MDCT methods were compared against QCA. RESULTS: The mean degree of stenosis as measured by MDCT was closely correlated to QCA for both methods (CS-MPR versus QCA: 61 +/- 23% versus 64 +/- 29%; r2 = 0.83, p < 0.001 and MIP versus QCA: 64 +/- 22% versus 64 +/- 29%; r2 = 0.84, p < 0.001 for MIP. Bland-Altman analysis demonstrated a negative bias of the degree of stenosis of -2.8 +/- 12% using CS-MPR and a minimally positive bias of 0.6 +/- 12% for MIP. In stratified analysis for lesion severity (mild, 0-40%; moderate, 41-70% or severe, > 70%) the agreement between both CS-MPR and MIP was high when compared to QCA (kappa = 0.74 and 0.71, respectively). CONCLUSION: Multi-detector spiral CT permits accurate quantitative assessment of the degree of coronary stenosis in selected data sets of sufficient quality using both cross-sectional and longitudinal vessel reconstructions.

Aged↗
PubMed2006

Improved vessel morphology measurements in contrast-enhanced multi-detector computed tomography coronary angiography with non-linear post-processing.

Multi-detector computed tomography (MDCT) permits detection of coronary plaque. However, noise and blurring impair accuracy and precision of plaque measurements. The aim of the study was to evaluate MDCT post-processing based on non-linear image deblurring and edge-preserving noise suppression for measurements of plaque size. Contrast-enhanced MDCT coronary angiography was performed in four subjects (mean age 55 +/- 5 years, mean heart rate 54 +/- 5 bpm) using a 16-slice scanner (Siemens Sensation 16, collimation 16 x 0.75 mm, gantry rotation 420 ms, tube voltage 120 kV, tube current 550 mAs, 80 mL of contrast). Intravascular ultrasound (IVUS; 40 MHz probe) was performed in one vessel in each patient and served as a reference standard. MDCT vessel cross-sectional images (1 mm thickness) were created perpendicular to centerline and aligned with corresponding IVUS images. MDCT images were processed using a deblurring and edge-preserving noise suppression algorithm. Then, three independent blinded observers segmented lumen and outer vessel boundaries in each modality to obtain vessel cross-sectional area and wall area in the unprocessed MDCT cross-sections, post-processed MDCT cross-sections and corresponding IVUS. The wall area measurement difference for unprocessed and post-processed MDCT images relative to IVUS was 0.4 +/- 3.8 mm2 and -0.2 +/- 2.2 mm2 (p < 0.05), respectively. Similarly, Bland-Altman analysis of vessel cross-sectional area from unprocessed and post-processed MDCT images relative to IVUS showed a measurement difference of 1.0 +/- 4.4 and 0.6 +/- 4.8 mm2, respectively. In conclusion, MDCT permitted accurate in vivo measurement of wall area and vessel cross-sectional area as compared to IVUS. Post-processing to reduce blurring and noise reduced variability of wall area measurements and reduced measurement bias for both wall area and vessel cross-sectional area.

Algorithms↗
PubMed2006

Quantitative parameters of image quality in 64-slice computed tomography angiography of the coronary arteries.

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rate < or = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate > 65 bpm (p < 0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.

Adult↗
PubMed2006

Evidence for lower variability of coronary artery calcium mineral mass measurements by multi-detector computed tomography in a community-based cohort--consequences for progression studies.

PURPOSE: To compare the measurement variability for coronary artery calcium (CAC) measurements using mineral mass compared with a modified Agatston score (AS) or volume score (VS) with multi-detector CT (MDCT) scanning, and to estimate the potential impact of these methods on the design of CAC progression studies. MATERIALS AND METHODS: We studied 162 consecutive subjects (83 women, 79 men, mean age 51 +/- 11 years) from a general Caucasian community-based cohort (Framingham Heart Study) with duplicate runs of prospective electrocardiographically-triggered MDCT scanning. Each scan was independently evaluated for the presence of CAC by four experienced observers who determined a "modified" AS, VS and mineral mass. RESULTS: Of the 162 subjects, CAC was detected in both scans in 69 (42%) and no CAC was detected in either scan in 72 (45%). Calcium scores were low in the 21/162 subjects (12%) for whom CAC was present in one but not the other scan (modified AS < 20 in 20/21 subjects, mean AS 4.6 +/- 1.9). For all three quantification algorithms, the inter- and intraobserver correlation were excellent (r > 0.96). However, the mean interscan variability was significantly different between mineral mass, modified AS, and VS (coefficient of variation 26 +/- 19%, 41 +/- 28% and 34 +/- 25%, respectively; p < 0.04), with significantly smaller mean differences in pair-wise comparisons for mineral mass compared with modified AS (p < 0.002) or with VS (p < 0.03). The amount of CAC but not heart rate was an independent predictor of interscan variability (r = -0.638, -0.614 and -0.577 for AS, VS, and mineral mass, respectively; all p < 0.0001). The decreased interscan variability of mineral mass would allow a sample size reduction of 5.5% compared with modified AS for observational studies of CAC progression and for randomized clinical trials. CONCLUSION: There is significantly reduced interscan variability of CAC measurements with mineral mass compared with the modified AS or VS. However, the measurement variability of all quantification methods is predicted by the amount of CAC and is inversely correlated to the extent of partial volume artifacts. Moreover, the improvement of measurement reproducibility leads to a modest reduction in sample size for observational epidemiological studies or randomized clinical trials to assess the progression of CAC.

Adult↗
PubMed2006

Threshold-dependent variability of coronary artery calcification measurements -- implications for contrast-enhanced multi-detector row-computed tomography.

INTRODUCTION: The present study investigated the threshold-dependent variability of coronary artery calcification (CAC) measurements and the potential to quantify CAC in contrast-enhanced multi-detector row-computed tomography (MDCT). METHODS: We compared the mean CT attenuation of CAC to luminal contrast enhancement of the coronary arteries in 30 patients (n = 30) undergoing standard coronary contrast-enhanced spiral MDCT. The modified Agatston score [AS], calcified plaque volume [CV], and mineral mass [MM]) at four different thresholds (130, 200, 300, and 400 HU) were measured in 50 patients who underwent non-contrast-enhanced MDCT. RESULTS: Mean CT attenuation of CAC was similar to the attenuation of the contrast-enhanced coronary lumen (CAC 297.1 +/- 68.7 HU versus 295 +/- 65 HU (p < 0.0001), respectively). Above a threshold of 300 HU CAC measurements significantly varied to standard measurements obtained at a threshold of 130 HU (p < 0.0001). The threshold-dependent variation of MM measurements was significantly smaller than for AS and CV (130 HU versus 400 HU: 63, 75, and 81, respectively; p < 0.001). These differences resulted in a change of age and gender based percentile category for AS in 78% of subjects. DISCUSSION: We demonstrated that CAC measurements are threshold dependent with MM measurements having significantly less variation than AS or CV. Due to the similarity of mean CT attenuation of CAC and the contrast-enhanced coronary lumen accurate quantification of CAC may be difficult in standard coronary contrast-enhanced spiral MDCT.

Calcinosis↗
PubMed2006

Delayed enhancement cardiac MR imaging in noncompaction of left ventricular myocardium.

A 49-year-old female with a history of paroxysmal atrial fibrillation, presented with worsening dyspnea on minimal exertion. During the follow-up period, transthoracic echocardiography and cardiac magnetic resonance imaging (CMR) were consistent with the diagnosis of noncompaction of the left ventricle. Delayed-enhancement CMR demonstrated hyperenhancement of the prominent trabeculations located at the mid and apical portions of the left ventricle, suggesting areas of fibrosis. Although previous cases of left ventricular noncompaction diagnosed with CMR have been described in the literature, this is the first case to describe the utility of delayed-enhancement imaging in the pathohistological confirmation of myocardial fibrosis and scarring in the hypertrabeculated myocardium.

Contrast Media↗
PubMed2006

Vulnerable plaque detection by 3.0 tesla magnetic resonance imaging.

RATIONALE AND OBJECTIVES: A clinical case report is presented on a 76-year-old man who volunteered for a 3.0 T magnetic resonance (MR) carotid protocol. The subject was referred for carotid endarterectomy and histology was performed on the ex vivo specimen and compared with the in vivo images. METHODS: The 3.0 and 1.5 T (obtained for comparison) MR protocol consisted of 2-dimensional (2D) and 3-dimensional (3D) multicontrast bright and black blood imaging for detecting the lumen and vessel wall. RESULTS: The combination of multicontrast black blood transverse images and the 3D time of flight transverse images provided visualization of a narrowed internal carotid artery lumen 4 mm above of the bifurcation and the presence of a complex atherosclerotic plaque containing a large lipid pool, calcification, and intact fibrous cap. Quantitative comparisons including vessel lumen and plaque area, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were obtained for 1.5 and 3.0 T image data. Plaque composition was verified with histology. Macrophages were also detected in the shoulders of the plaque as demonstrated by CD68 staining and corresponded with a small hyperintense area in the T2W images at 3.0 T, but not observed in comparable 1.5 T images. CONCLUSIONS: High field 3.0 T multicontrast MRI of atherosclerotic plaque has been validated with histology comparison and provides improved detection of complex atherosclerotic plaque with increased SNR and CNR compared with 1.5 T. Further studies validating contrast mechanisms of plaque at 3.0 T are required, but atherosclerotic plaque imaging has clear benefit from application at the higher magnetic field strength.

Aged↗
PubMed2006

Diagnostic performance of stress perfusion and delayed-enhancement MR imaging in patients with coronary artery disease.

PURPOSE: To prospectively determine the accuracy of a combined magnetic resonance (MR) imaging approach (stress first-pass perfusion imaging followed by delayed-enhancement imaging) for depicting clinically significant coronary artery stenosis (> or = 70% stenosis) in patients suspected of having or known to have coronary artery disease (CAD), with coronary angiography serving as the reference standard. MATERIALS AND METHODS: The committee on human research approved the study protocol, and all participants gave written informed consent. This study was HIPAA compliant. Forty-seven patients (38 men and nine women; mean age, 63 years +/- 5.3 [standard deviation]) scheduled for coronary angiography were prospectively enrolled: 33 were suspected of having CAD (group A) and 14 had experienced a previous myocardial infarction and were suspected of having new lesions (group B). The MR imaging protocol included cine function, gadolinium-enhanced stress and rest first-pass perfusion MR imaging, and delayed-enhancement MR imaging. Myocardial ischemia was defined as a segment with perfusion deficit at stress first-pass perfusion MR imaging and no hyperenhancement at delayed-enhancement imaging. Myocardial infarction was defined as an area with hyperenhancement at delayed-enhancement imaging. RESULTS: One patient was excluded from analysis because of poor-quality MR images. Coronary angiography depicted significant stenosis in 30 of 46 patients (65%). In a per-vessel analysis (n = 138), stress first-pass perfusion MR imaging and delayed-enhancement imaging yielded sensitivity of 0.87, specificity of 0.89, and accuracy of 0.88, when compared with coronary angiography. The diagnostic accuracy of stress first-pass perfusion MR imaging and delayed-enhancement imaging was slightly better than that of stress and rest first-pass perfusion MR imaging in the entire population (0.88 vs 0.85), in group A (0.86 vs 0.82), and in group B (0.93 vs 0.90). CONCLUSION: Stress first-pass perfusion MR imaging followed by delayed-enhancement imaging is an accurate method to depict significant coronary stenosis in patients suspected of having or known to have CAD.

Aminophylline↗
PubMed2005

A novel model to test accuracy and reproducibility of MDCT scan protocols for coronary calcium in vivo.

OBJECTIVES: We compared the accuracy and reliability of prospectively triggered, retrospectively ECG gated, and non-gated CT image reconstruction for measurements of coronary artery calcification (CAC) in vivo using a novel animal model. MATERIALS AND METHODS: In six Yorkshire farm pigs, prefabricated chains of cortical bone fragments were sutured over the epicardial bed of the major coronary arteries. Using a 4-slice MDCT scanner, each animal was imaged with two different protocols: sequential acquisition with prospective ECG triggering, and spiral acquisition with retrospectively ECG gated image reconstruction- non-gated reconstructions were also generated from these latter scans. Two independent observers measured the 'Agatston score' (AS), the calcified volume (CV), and mineral mass (MM). To calculate accuracy of MM measurements the ash weight of the burned bone fragments was compared to MDCT derived MM. RESULTS: Six pigs successfully underwent surgery and CT imaging (mean heart rate: 86+/-12 bpm). MM measurements from prospectively ECG triggered CT sequential scans were more accurate (p<0.02) and reproducible (p=0.05) than sequential CT scans without ECG triggering or spiral acquisition using retrospective ECG gating. CONCLUSIONS: At high heart rates prospective ECG triggered image reconstruction is more accurate and reproducible for CAC scoring than retrospective ECG gated reconstruction and non-gated reconstruction.

Analysis of Variance↗
PubMed2005

Comparison of the degree of coronary stenoses by multidetector computed tomography versus by quantitative coronary angiography.

Sixteen-slice multidetector computed tomography (MDCT) and quantitative coronary angiography (QCA) were performed in 29 patients. Quantification of the degree of luminal narrowing and lesion length measurements were performed independently on MDCT and QCA at 42 sites with sufficient computed tomographic image quality. The correlation between MDCT and QCA for quantifying the degree of stenosis was excellent (r2 = 0.93), although a systematic overestimation was observed by MDCT (bias 4% +/- 8%). The correlation between MDCT and QCA was moderate with respect to lesion length (r2 = 0.54). In the absence of severe calcifications or motion artifacts, MDCT permits noninvasive quantification of coronary stenosis.

Aged↗
PubMed2005

Calcium concentration of individual coronary calcified plaques as measured by multidetector row computed tomography.

BACKGROUND: Characteristics of individual calcified plaques, especially calcium concentration (CC), may provide incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and evaluation of therapeutic intervention. In this study, therefore, we assessed the characteristics of individual calcified plaques and their relationship to other parameters derived from CT analysis of coronary calcium in a community-based cross-sectional cohort. METHODS AND RESULTS: Coronary artery calcium (CAC) was analyzed in 612 participants of the Framingham Heart Study (third-generation and offspring cohorts) using prospectively ECG-triggered multidetector CT. We determined the CC, Agatston score, calcified volume, and mineral mass of individual calcified plaques in each subject. Heterogeneity of CC was defined as the standard deviation of CC of all individual calcified plaques in a subject. CAC was detected in 274 of 605 subjects. After excluding 57 subjects (21%) because of motion artifacts, we identified a total of 956 calcified coronary plaques in 217 subjects (74 women, 143 men; mean age, 57.1+/-10.8 years) with detectable CAC and no image artifacts. CC of individual calcified plaques was independent of subject age (P=0.76) and sex (197.8+/-74.8 versus 183.6+/-52.8 mg/cm3 for men versus women; P=0.21). Among a subgroup of 125 subjects with multiple (> or =3) individual calcified plaques, CC was heterogeneous within individual subjects (mean SD of CC, 43.6+/-23.1 mg/cm3). The degree of heterogeneity of CC in these subjects was independent of age (P=0.60), sex (P=0.99), and number of plaques (P=0.06). CONCLUSIONS: The CC of individual calcified plaques is independent of age and sex but heterogeneous within a subject, which may reflect that the pathological process of calcified plaque formation and progression is the same in men and women regardless of age. CC may have incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and the evaluation of therapeutic intervention. Further studies are warranted to confirm that individual plaque analysis is preferable to global CAC scores to evaluate progression of atherosclerosis and to assess whether individual plaque analysis may be complementary to global CAC measures to assess coronary event risk.

Age Factors↗