[Show abstract][Hide abstract] ABSTRACT: Cardiac computed tomography (CT) has emerged as a robust modality for imaging coronary stenosis and has recently been used to evaluate myocardial abnormalities such as ischemic perfusion defects and infarction. We developed a new image analysis algorithm for the semiautomatic and quantitative assessment of myocardial perfusion by CT.
The algorithm semiautomatically segments two-dimensional short-axis reformatted DICOM images of the left ventricle into regions of interest (ROIs) in accordance with American Heart Association (AHA) standards and is capable of creating nine further ROI subsegments. This includes separate endocardial, mid-ventricle, and epicardial layers. Image intensity values (Hounsfield unit) and relative myocardial thickness are quantitatively reported for each ROI and segment.
The algorithm allows comparison of the HU values at the same ROI locations between rest and stress. The reproducibility is very good; ICC 0.89 for rest images, 0.83 for stress images. The mean time for generating ROIs for the entire heart was 11 minutes versus 22 minutes for manual tracing.
The algorithm reports parameters relevant for evaluation of stress perfusion CT studies and will allow more accurate and reproducible analysis in cardiac CT research.
[Show abstract][Hide abstract] ABSTRACT: To determine the accuracy of dual-source CT (DSCT) to quantify coronary stenosis compared to intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA).
21 patients (23 vessels) were examined with DSCT, IVUS and invasive coronary angiography. Coronary minimal luminal diameter (MLD) and area (MLA) were measured in cross-sectional multi-planar reformatted images perpendicular to the vessel long-axis. The vessel cross-sectional area stenosis (MLA/CSA ratio) was calculated. DSCT results were compared with IVUS and QCA.
A good correlation between DSCT and IVUS was noted for diameter and area stenosis (r=0.69 and r=0.73), with an overestimation of MLD stenosis by DSCT (+9.1%) and an underestimation of MLA stenosis (-5.8%). For MLD and MLA, high correlation coefficients (r=0.78 and r=0.90, respectively) were found between DSCT and IVUS; and the bias was almost zero (-0.41 mm and +0.1mm(2), respectively). The correlation between DSCT and QCA was moderate (r=0.60) for MLD stenosis with minor overestimation by DSCT (+4.0%) and moderate (r=0.59) for MLD (bias, +0.01 mm). The cross-sectional area stenosis showed a moderate correlation (r=0.59) between DSCT and IVUS (+0.00).
DSCT allows accurate quantification of coronary stenosis as compared to IVUS. An excellent correlation was found for the MLA between DSCT and IVUS.
European journal of radiology 01/2011; 81(1):83-8. DOI:10.1016/j.ejrad.2010.12.008 · 2.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study sought to determine the feasibility of performing a comprehensive cardiac computed tomographic (CT) examination incorporating stress and rest myocardial perfusion imaging together with coronary computed tomography angiography (CTA).
Although cardiac CT can identify coronary stenosis, very little data exist on the ability to detect stress-induced myocardial perfusion defects in humans.
Thirty-four patients who had a nuclear stress test and invasive angiography were included in the study. Dual-source computed tomography (DSCT) was performed as follows: 1) stress CT: contrast-enhanced scan during adenosine infusion; 2) rest CT: contrast-enhanced scan using prospective triggering; and 3) delayed scan: acquired 7 min after rest CT. Images for CTA, computed tomography perfusion (CTP), and single-photon emission computed tomography (SPECT) were each read by 2 independent blinded readers.
The DSCT protocol was successfully completed for 33 of 34 subjects (average age 61.4 +/- 10.7 years; 82% male; body mass index 30.4 +/- 5 kg/m(2)) with an average radiation dose of 12.7 mSv. On a per-vessel basis, CTP alone had a sensitivity of 79% and a specificity of 80% for the detection of stenosis > or =50%, whereas SPECT myocardial perfusion imaging had a sensitivity of 67% and a specificity of 83%. For the detection of vessels with > or =50% stenosis with a corresponding SPECT perfusion abnormality, CTP had a sensitivity of 93% and a specificity of 74%. The CTA during adenosine infusion had a per-vessel sensitivity of 96%, specificity of 73%, and negative predictive value of 98% for the detection of stenosis > or =70%.
Adenosine stress CT can identify stress-induced myocardial perfusion defects with diagnostic accuracy comparable to SPECT, with similar radiation dose and with the advantage of providing information on coronary stenosis.
Journal of the American College of Cardiology 09/2009; 54(12):1072-84. DOI:10.1016/j.jacc.2009.06.014 · 16.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Multidetector computed tomography (MDCT) has recently emerged as a potential noninvasive alternative for high-resolution imaging of coronary arteries.
In this study, we evaluated 64-slice MDCT for detection, quantification, and characterization of atherosclerotic plaque burden in nonculprit lesions.
Data from 11 patients who underwent both MDCT and intravascular ultrasound (IVUS) for suspected coronary artery disease were collected, and a total of 17 coronary segments and 122 cross-sectional slices were analyzed by MDCT and IVUS. Coronary segments on MDCT were coregistered to IVUS, and each obtained slice was scored by 2 blinded observers for presence and type of plaque. Quantitative measurements included cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden. Mean and standard deviation of Hounsfield units (HUs) were recorded for plaque when present.
Overall sensitivity for plaque detection was 95.0%, and specificity, positive predictive value, negative predictive value were 88.7%, 89.1%, and 94.8%, respectively. Spearman's correlation coefficients were 0.85, 0.75, 0.70, 0.89, and 0.54 for cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden, respectively. The interobserver variability for plaque burden and plaque volume measurements between readers on 64-MDCT was high at 32.7% and 30.4%, respectively. Combined noncalcified plaque had a mean MDCT density significantly different from that of calcified plaque. Soft and fibrous plaques were not able to be distinguished based on their HU values.
Sixty-four-slice MDCT had good correlation with IVUS but with high interobserver variability. Plaque characterization remains a challenge with present MDCT technology.
[Show abstract][Hide abstract] ABSTRACT: Lead poisoning from novel environmental sources continues to present a challenge to clinicians who treat infants and children.
A 12 month old infant of Thai parents was found during well child care to have a venous blood lead concentration of 61 mcg/dL. He was hospitalized for parenteral chelation with CaNa2EDTA and subsequently managed as an outpatient with oral succimer, with a reduction in blood lead concentration to 23 mcg/dL. Chronic lead poisoning was attributed to the use of a Thai tongue powder by the parents for the first seven months of the infant's life. This ethnic remedy was applied to the tongue to absorb toxins, reduce white patches present after milk feedings, and preserve the infant's health.
Lead contaminated the powder at 109,000 ppm as measured by x-ray fluorescence spectrometry. Two poison centers in Thailand were contacted and initiated a public health inquiry with the Thai Food & Drug Administration (Thai FDA) to remove contaminated products from the marketplace. Their investigation found six additional contaminated tongue powders (of 10 tested) in a Bangkok shop offering Chinese remedies, some with lead levels > 9000 ppm. These products, unregistered with the Thai FDA, were confiscated and the shop closed. Local media attention and case-finding activities of health officials identified one additional infant suffering from lead poisoning due to tongue powders.
Asian tongue powders can be a source of lead poisoning. Medical toxicologists, poison centers, and public health agencies can work together internationally to accomplish effective post-marketing product surveillance.