Showing papers in "International Journal of Cardiovascular Imaging in 2009"
TL;DR: For prospectively ECG-gated single heart beat coronary CTA, a phase window width of 10% will reduce patient radiation and yield diagnostic images in >90% of patients and heart rate control is an important component of prospectively gated CT dose reduction.
Abstract: Purpose To evaluate the relationship between the phase window width and image quality in prospectively ECG-gated 320-detector row coronary CTA, and to evaluate the relationship between heart rate and the number of cardiac phases with diagnostic quality images. Methods Thirty-six phases (60–95% R-R, 1% increments) were reconstructed in 41 consecutive prospectively gated single R-R 320 × 0.5 mm detector row coronary CTA patients. For each phase, two cardiovascular imagers retrospectively documented the phases considered diagnostic for the left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA). The smallest phase window width including at least one diagnostic phase for 95% of coronary arteries was determined, and after accounting for sampling variation, the same smallest window width was estimated for the general population. Inter-rater agreement was determined. A linear regression model evaluated the relationship between heart rate and width of diagnostic phase windows. Results Widening the phase window width increases the proportion of coronary arteries with at least one diagnostic phase. Among the 41 patients, 95% of vessels had a diagnostic phase in the 72–77% phase window. Accounting for sampling variation, the 72–81% phase window has a 0.95 probability of including a diagnostic phase for 95% of coronary arteries in the general population. Interobserver agreement was 0.959 with 0.95 confidence interval [0.908, 0.987]. Patients with a lower heart rate had significantly more diagnostic phases. Conclusions For prospectively ECG-gated single heart beat coronary CTA, a phase window width of 10% will reduce patient radiation and yield diagnostic images in >90% of patients. Heart rate control is an important component of 320-detector row prospectively gated CT dose reduction.
179 citations
TL;DR: The fundamental concepts of strain imaging derived from tissue Doppler and two-dimensional speckle tracking are described and how these methods can be incorporated into echocardiographic examinations are investigated and their clinical applications are investigated.
Abstract: Echocardiography is the most common diagnostic method for assessing cardiac functions. However, echocardiographic measures are subjective, semi-quantitative, and relatively insensitive when detecting subtle perturbations in contractility. Furthermore, early detection of abnormalities is crucial and may often influence treatments and establish prognosis. Echocardiographic- and Doppler-derived strain and strain rate imaging are relatively newer and more comprehensive techniques. They characterize the mechanics of myocardial contraction and relaxation (deformation imaging) more precisely and find applications in many cardiac pathologies. They are especially useful for assessing longitudinal myocardial deformation, which is otherwise difficult to assess using standard echocardiographic visual inspection. This review describes the fundamental concepts of strain imaging derived from tissue Doppler and two-dimensional speckle tracking and investigates how these methods can be incorporated into echocardiographic examinations and highlights their clinical applications. The considerable potentiality of imaging modalities for numerous cardiac conditions is thereby shown.
164 citations
TL;DR: Planimetry of the LVOT utilizing three-dimensional imaging modalities such as 3-D echocardiography, MRI, or MDCT may render a more precise aortic valve area (AVA) using 64-slice Multi-detector CT.
Abstract: Background Newer three-dimensional imaging technologies provide insight into cardiac shape and geometry from views previously unobtainable. Standard formulae like the continuity equation (CE) that rely on inherent assumptions about left ventricular outflow tract (LVOT) shape may need to be revisited. In the CE, small changes in LVOT diameter may significantly change calculated aortic valve area (AVA). Using 64-slice Multi-detector CT (MDCT), we performed LVOT planimetry to obviate the need for any geometric assumptions. Methods 64-slice MDCT was performed in 30 consecutive patients. The diameter-derived LVOT area (ALVOTdiam) was calculated from a view analogous to the 2D echo parasternal long axis. Direct planimetry of the LVOT (ALVOTplan) was performed just beneath the aortic valve in a plane perpendicular to the LVOT long axis. Further, assuming an ellipsoid outflow tract shape, LVOT area (ALVOTellip) was calculated using πab from the long and short diameters of the planimetered LVOT view. Eccentricity index (EI) was estimated by subtracting the ratio of shortest and longest LVOT diameters from one. Results ALVOTdiam always measured smaller than ALVOTplan (mean 3.7 ± 1.2 cm2 vs. 4.1 ± 1.3 cm2, respectively). The median EI was 0.18 (95% CI = 0.16–0.2; P = 0.0001). ALVOTellip more closely agreed with ALVOTplan (correlation = 0.96; P < 0.0001) than did ALVOTdiam (correlation = 0.87; P < 0.0001). Conclusion Using MDCT, the LVOT was shown to be elliptical in most patients. Applying the CE which assumes roundness of the LVOT consistently underestimated the LVOT area which may affect estimated AVA. Planimetry of the LVOT utilizing three-dimensional imaging modalities such as 3-D echocardiography, MRI, or MDCT may render a more precise AVA.
132 citations
TL;DR: LGE by CMRI is able to detect fibrosis in selective regions of myocardium in patients with DMD, and unfavorable LV remodeling, with a corresponding decreased ejection fraction, is associated with the presence of LGE.
Abstract: Background Progressive cardiomyopathy is a common cause of death in Duchenne muscular dystrophy (DMD), presumably secondary to fibrosis of the myocardium. The posterobasal and left lateral free wall of the left ventricle (LV) are initial sites of myocardial fibrosis pathologically. The purposes of this study were to assess whether cardiac magnetic resonance imaging (CMRI), utilizing late gadolinium enhancement (LGE), could identify fibrosis in selective areas of the myocardium, and to assess the relationship of the presence and extent of fibrosis to LV function. Methods The cardiology databases at Primary Children’s Medical Center and Cincinnati Children’s Hospital Medical Center were reviewed to identify patients with DMD who had undergone a CMRI within the last 2 years. Age, LV ejection fraction, LV mass, presence and location of LGE were documented. Volumes were measured using MASS (Medis, Inc.) to calculate ejection fraction and mass. LGE images were acquired and when positive, customized computer assisted sizing of the areas of late gadolinium enhancement were performed on all slices. Normal function was defined as LV ejection fraction >54%. Results A total of 74 patients with DMD had complete data sets (median age 13.7 years, range 7.7–26.4). Twenty-four patients (32%) had LGE involving the posterobasal region of the LV in a sub-epicardial distribution. Those patients with more involvement had spread to the inferior and left lateral free wall with progressive transmural fibrous replacement. There was relative sparing of the interventricular septum and right ventricle. Patients with LGE were significantly older than those without (mean age 16.4 vs 12.9 years, P < 0.001). LGE was positively associated with BSA-adjusted LV mass, LV end-diastolic volume, LV end-systolic volume, and RV end-systolic volume but inversely correlated with ejection fraction of the LV (P < 0.001) and RV (P = 0.004). Conclusions LGE by CMRI is able to detect fibrosis in selective regions of myocardium in patients with DMD. Unfavorable LV remodeling, with a corresponding decreased ejection fraction, is associated with the presence of LGE. Serial studies are warranted to determine if LGE precedes a decrease in function, and if early medical management is useful in preventing progression once LGE is documented.
127 citations
TL;DR: To compare the effective radiation dose and the image quality with two techniques to reduce radiation doses with CTA studies utilizing 64-MDCT scanners, 149 consecutive patients underwent CT coronary angiography using one of three algorithms.
Abstract: Current 64-multidetector Computed Tomographic scanners (MDCT) utilize retrospective overlapping helical acquisition (RS-OHA) which imparts a higher than desired radiation dose. Although the radiation burden of computed tomographic angio- graphy (CTA) can be efficiently reduced by dose modulation and limiting field of view, a further decrease in radiation without compromising diagnos- tic image quality would be indeed very desirable. An alternative imaging mode is the axial prospective ECG-triggering acquisition (prospective gating). This study was done to compare the effective radiation dose and the image quality with two techniques to reduce radiation doses with CTA studies utilizing 64- MDCT scanners. The study included 149 consecutive patients (48 females and 101 males) 64-MDCT (mean age = 67 ± 11 years, 72.2% male). Patients under- went CT coronary angiography using one of three algorithms: retrospective triggering with dose modulation; prospective triggering with padding (step and shoot acquisition with additional adjacent phases); and prospective triggering without padding (single phase acquisition only). Based on body habitus, two different voltages were utilized: 100 kVp (\85 kg) or 120 kVp ((85 kg). Radiation doses and image quality (signal to noise ratio) was measured for each patient, and compared between different acquisition protocols. The signal to-noise ratio of the ascending aorta (SNR-AA) was calculated from the mean pixel values of the contrast-filled left ventricular chamber divided by the standard deviation of these pixel values. Use of 100 kVp reduced radiation dose 41.5% using prospective triggering and 39.6% using retrospective imaging as compared to 120 kVp (P \ 0.001). Use of prospective imaging reduced radiation exposure by 82.6% as compared to retrospective imaging (P \ 0.001). Using both pro- spective imaging and 100 kVp without padding (single phase data, no other phases obtained), radia- tion dose was reduced by 90% (P \ 0.001). In terms of image quality, the coefficient of variation of ascending aortic contrast enhancement between kVp of 120 and kVp of 100 was 6% (1.05, 95 CI 0.93- 1.17), and 7.8% (0.9, 95% CI 0.7-1.2) at the pulmonary artery. The prospective ECG-Triggered acquisition and 100 kVp images were of diagnostic quality, allowing adequate assessment in all patients. CTA using PA and 100 kVp reduced the radiation dose by up to 90% without compromising the image quality.
96 citations
TL;DR: TAPSE is not a reliable measure of RVEF in TOF by MRI and may be of limited use in conditions that exhibit abnormal regional contraction.
Abstract: The correlation between right ventricular ejection fraction (RVEF) and tricuspid annular plane systolic excursion (TAPSE) by two-dimensional (2-D) echo has been repeatedly validated, but not by magnetic resonance imaging (MRI) nor in patients with congenital heart disease. We tested whether TAPSE measurements by MRI correlate with RVEF in surgically repaired tetralogy of Fallot (TOF) patients. TAPSE was measured from systolic displacement of the RV-freewall/tricuspid annular plane junction in the apical 4-chamber view in 7 normal subjects and 14 TOF patients. The RV was reconstructed in 3-D from manually traced borders on MR images to compute true EF. Because we previously observed discrepancy between TAPSE and RVEF in the presence of regional dysfunction, we also analyzed RV wall motion in terms of regional stroke volume at 20 short axis slices from apex to tricuspid annulus. RVEF was 52 ± 3% in normal subjects and 41 ± 9% in TOF (P < 0.01). TAPSE correlated weakly (r = 0.50, P < 0.05) with RVEF. TOF patients exhibited increased regional stroke volume from apical portions of the RV and decreased regional stroke volume at the base compared to normal (P < 0.05 at 15 of 20 slices). Regional stroke volume in apical slices correlated inversely with RVEF such that patients with higher apical stroke volume had lower RVEF (P < 0.05). TAPSE is not a reliable measure of RVEF in TOF by MRI. TAPSE may be of limited use in conditions that exhibit abnormal regional contraction.
94 citations
TL;DR: RV L PSS is reduced in TOF patients as compared to controls; during follow-up RV EF remained unchanged whereas LPSS decreased suggesting that RV LPSs may be a sensitive marker to detect early deterioration in RV performance.
Abstract: The aim of this study was to evaluate the feasibility of right ventricular (RV) longitudinal peak systolic strain (LPSS) assessment for the follow-up of adult patients with corrected tetralogy of Fallot (TOF). Adult patients (n = 18) with corrected TOF underwent echocardiography and CMR twice with a time interval of 4.2 ± 1.7 years. RV performance was derived from CMR, and included RV volumes and ejection fraction (EF). LPSS was calculated globally (GLPSS) and in the RV free wall (LPSS FW), with echocardiographic speckle-tracking strain-analysis. Baseline (G)LPSS values were compared between patients and healthy controls; the relation between (G)LPSS and CMR parameters was evaluated and the changes in (G)LPSS and CMR parameters during follow-up were compared. GLPSS and LPSS FW were significantly reduced in patients as compared to controls (−14.9 ± 0.7% vs. −21.6 ± 0.9% and −15.5 ± 0.9% vs. −22.7 ± 1.5%, P < 0.01). Moderate agreement between LPSS and CMR parameters was observed. RV EF remained unchanged during follow-up, whereas GLPSS and LPSS FW demonstrated a significant reduction. RVEF showed a 1% increase, whereas GLPSS decreased by 14%, and LPSS FW by 27%. RV LPSS is reduced in TOF patients as compared to controls; during follow-up RV EF remained unchanged whereas LPSS decreased suggesting that RV LPSS may be a sensitive marker to detect early deterioration in RV performance.
93 citations
TL;DR: This review summarizes the major accomplishments and future directions in this field, with emphasis on developments over the past 10 years.
Abstract: 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.
90 citations
TL;DR: The steps required to derive an ESS map from 320-detector row CT data using the Lattice Boltzmann method to include the complex geometry of the coronary arterial tree are described.
Abstract: Advances in MDCT will extend coronary CTA beyond the morphology data provided by systems that use 64 or fewer detector rows. Newer coronary CTA technology such as prospective ECG-gating will also enable lower dose examinations. Since the current standard of care for coronary diagnoses is catheterization, CT will continue to be benchmarked against catheterization reference points, in particular temporal resolution, spatial resolution, radiation dose, and volume coverage. This article focuses on single heart beat cardiac acquisitions enabled by 320-detector row CT. Imaging with this system can now be performed with patient radiation doses comparable to catheterization. The high image quality, excellent contrast opacification, and absence of stair-step artifact provide the potential to evaluate endothelial shear stress (ESS) noninvasively with CT. Low ESS is known to lead to the development and progression of atherosclerotic plaque culminating in high-risk vulnerable plaque likely to rupture and cause an acute coronary event. The magnitude of local low ESS, in combination with the local remodeling response and the severity of systemic risk factors, determines the natural history of each plaque. This paper describes the steps required to derive an ESS map from 320-detector row CT data using the Lattice Boltzmann method to include the complex geometry of the coronary arterial tree. This approach diminishes the limitations of other computational fluid dynamics methods to properly evaluate multiple coronary arteries, including the complex geometry of coronary bifurcations where lesions tend to develop.
71 citations
TL;DR: The benefit from a separate ECG-gated CT scan for the evaluation of RV ventricular diameter, area, and volume measurements is minimal and does not justify its routine clinical use.
Abstract: Objective To prospectively compare cardiac ventricular measurements from non-gated CT and end-diastolic ECG-gated CT in patients with acute pulmonary embolism (PE). Materials and methods With institutional review board approval, 30 adult patients (16 female, mean age = 56 years, range = 26–77 years) underwent ECG-gated cardiac CT within 36 h of their CT diagnosis of acute PE to assess the right ventricle (RV). The axial and reformatted four-chamber ventricular diameters, areas and volumes were measured for both the non-gated CT and the ECG-gated CT in end-diastole and end-systole. Spearman’s rank correlation coefficient (RCC) was calculated to compare measurements from the non-gated CT to the gated end-diastolic measurements. The median absolute differences between the gated and non-gated measurements relative to the gated measurements were provided to summarize the degree to which the two measurements differ. A statistical model was constructed to test for potential improvement in specificity for the prediction of 30-day mortality after acute PE using right ventricular measurements from ECG-gated CT versus non-gated CT. Results The RCC (0.90 confidence interval) for non-gated and ECG-gated end-diastolic four-chamber and axial RV/LV diameter ratios were 0.83 (0.68–0.90) and 0.88 (0.74–0.95). The median absolute percent differences suggested a high degree of concordance between gated and non-gated measurements. The statistical model predicted that measuring the RV/LV diameter ratio from end-diastole using ECG-gated CT rather than non-gated CT would yield a potential improvement in specificity for death after PE of 0.035 (0.020–0.060) for axial diameter ratios and 0.035 (0.020–0.055) for four-chamber diameter ratios. Conclusion The benefit from a separate ECG-gated CT scan for the evaluation of RV ventricular diameter, area, and volume measurements is minimal and does not justify its routine clinical use.
65 citations
TL;DR: This paper will review the technical aspects of 320-row detector computed tomography and their implications for coronary angiography and perfusion imaging, and the prospects for combined CT angiographic and myocardial perfusion Imaging are very promising.
Abstract: Cardiac multidetector computed tomography has evolved from early four detector systems that first demonstrated the feasibility of non-invasive angiography to today’s wide-area detector computed tomography systems, such as 320-row detector computed tomography. As detector arrays have widened, there have been great improvements in image quality that have improved test accuracy. In addition, wider detector arrays have allowed for the application of prospective ECG-gating for CT angiography, although the current 64-row detector systems have some limitations. 320-row detector computed tomography with full cardiac coverage allows for cardiac imaging in a single heart beat. This technology has realized some of the great advantages provided by full cardiac coverage in regards to image quality (elimination of step artifacts and variation in contrast enhancement), patient safety (reductions in overall radiation and contrast dose), and the prospects for combined CT angiography and myocardial perfusion imaging are very promising. We will review the technical aspects of 320-row detector computed tomography and their implications for coronary angiography and perfusion imaging.
TL;DR: Early clinical results indicate that high-quality, low-dose prospective coronary CTA may be applied to patients with higher heart rates, higher BMI, and with less sensitivity to heart rate variability using 256-slice MDCT.
Abstract: Since the introduction of 64-slice scanners, multidetector computed tomography (MDCT) has experienced a marked increase in adoption for the noninvasive assessment of coronary artery disease, although radiation dose concerns remain. The recent introduction of prospective coronary CT angiography (CCTA) has begun to address these concerns; however, its applicability with existing scanners remains limited to cohorts defined by heart rate, heart rate variability, and body mass index. This paper reviews prospective CCTA, the effect of heart rate and heart rate variability on image quality, and the physiologic basis for selection of optimal prospective imaging windows. We then discuss 256-slice technology and our first 4 months of clinical experience with 256-slice prospective CCTA. Our early clinical results indicate that high-quality, low-dose prospective coronary CTA may be applied to patients with higher heart rates, higher BMI, and with less sensitivity to heart rate variability using 256-slice MDCT.
TL;DR: The current status of wide-detector MDCT scanners and their advantages for clinical coronary and ventricular imaging are discussed and emerging complementary non-coronary applications that have been enabled byWide-detectors and multi-energy acquisitions are discussed.
Abstract: Multidetector computed tomography (MDCT) using 64 detectors is widely used for cardiac imaging in the clinical setting. Despite promising results, 64-slice MDCT has important limitations for cardiac applications related to detector coverage, which leads to longer scan times, image artifacts, increased radiation and the need for higher contrast doses. The advent of wide or full cardiac coverage with 256- or 320-slice MDCT provides important advantages that can potentially improve the status of these limitations and expand the utility of cardiac MDCT imaging beyond coronary imaging. Additionally, the combination of wide-detectors and multi-energy acquisitions offer interesting possibilities of improved coverage and temporal resolution that may improve plaque characterization as well as viability and perfusion imaging. In this review we will discuss the current status of wide-detector MDCT scanners and their advantages for clinical coronary and ventricular imaging. We will also review examples of wide detector coronary angiography imaging and discuss emerging complementary non-coronary applications that have been enabled by wide-detector MDCT imaging.
TL;DR: The different applications to reduce cardiac CT radiation doses to nominal levels are reviewed, potentially expanding the applications of cardiac CT by removing one of the biggest barriers.
Abstract: Multidetector computed tomography has come a long way in a short time, quickly becoming a standard tool in the cardiac imaging armamentarium. The promise of plaque imaging, combined with both anatomical visualization and stenosis detection, has made this a preferred first line test of many cardiologists and radiologists. This test is well suited to rule out coronary artery disease (obstruction) and still diagnosing subclinical plaque, with may be a good target for anti-atherosclerotic therapies. There has been recent criticism against CT imaging, and cardiac CT specifically, due to the high radiation doses that being employed. New advances have allowed for dramatic dose reductions. These include more routinely performed methods such as dose modulation, and newer methods such as prospective gating or minimizing the field of view. This paper will review the different applications to reduce cardiac CT radiation doses to nominal levels, potentially expanding the applications of cardiac CT by removing one of the biggest barriers.
TL;DR: In ED patients who have a low clinical suspicion of pulmonary embolism and acute aortic syndrome, especially younger patients, dedicated coronary CT angiography accompanied by modifications to reduce radiation dose is recommended.
Abstract: Immediate coronary catheterization is mandatory for high risk patients with typical chest pain in the emergency department (ED). In contrast, in ED patients with acute chest pain but low to intermediate risk, traditional management protocol includes serial ECG, cardiac troponins and radionuclide perfusion imaging. However, this protocol is time-consuming and expensive, and definite treatment of unstable angina is often delayed. Due to advances of multi-detector CT (MDCT) technology, dedicated coronary CT angiography provides the potential to rapidly and reliably diagnose or exclude acute coronary syndrome in ED patients with acute chest pain. Moreover, major life-threatening causes of ED chest pain (i.e., acute aortic syndrome and pulmonary embolism as well as acute coronary syndrome) can simultaneously be assessed by the so-called “triple rule-out” protocol with a single scan. In ED patients with atypical chest pain and low to intermediate risk, the triple rule-out protocol may be preferred, especially in older patients who have relatively lower risk of lifelong radiation-induced cancer. However, the increased radiation dose resulting from the extended volume coverage with this protocol should be fully considered prior to performing this protocol. Therefore, in ED patients who have a low clinical suspicion of pulmonary embolism and acute aortic syndrome, especially younger patients, dedicated coronary CT angiography accompanied by modifications to reduce radiation dose is recommended.
TL;DR: Low heart rate patients had higher coronary sharpness at most cardiac phases; however, patients with high heart rates had higher cardiac sharpness in the 45% phase for all four vessels (P < 0.0001).
Abstract: The purpose of this study was to determine the cardiac phase having the highest coronary sharpness for low and high heart rate patients scanned with dual source CT (DSCT) and to compare coronary image sharpness over different cardiac phases. DSCT coronary CT scans for 30 low heart rate (≤70 beats per minute- bpm) and 30 high heart rate (>70 bpm) patients were reconstructed into different cardiac phases, starting at 30% and increasing at 5% increments until 70%. A blinded observer graded image sharpness per coronary segment, from which sharpness scores were produced for the right (RCA), left main (LM), left anterior descending (LAD), and circumflex (Cx) coronary arteries. For each coronary artery, the phase with maximal image sharpness was identified with repeated measures analysis of variance. Comparison of coronary sharpness between low and high heart rate patients was made using generalized estimating equations. For low heart rates the highest sharpness scores for all four vessels (RCA, LM, LAD, and Cx) were at the 65 or 70% phase, which are end-diastolic cardiac phases. For high heart rates the highest sharpness scores were between the 35 and 45% phases, which are end-systolic phases. Low heart rate patients had higher coronary sharpness at most cardiac phases; however, patients with high heart rates had higher coronary sharpness in the 45% phase for all four vessels (P < 0.0001). Using DSCT scanning, optimal image sharpness is obtained in end-diastole at low heart rates and in end-systole in high heart rates.
TL;DR: The use of intravenous adenosine in CMR perfusion imaging is safe and well-tolerated, even in patients with severe CAD, where serious adverse events in the CMR scanner are relatively rare and symptoms resolve following termination of the infusion, without the need for aminophylline.
Abstract: We sought to assess the tolerance and safety of adenosine-stress cardiovascular magnetic resonance (CMR) perfusion imaging in patients with coronary artery disease (CAD). We retrospectively examined all adenosine CMR perfusion scans performed in our centre in patients with known or suspected (CAD) and normal volunteers at either 1.5 or 3 T. All subjects were initially screened for contraindications to adenosine. The dose of adenosine infused was 140 microg/kg/min. Significant CAD was defined angiographically as the presence of at least one stenosis of >50% diameter. Data were collected from 351 consecutive subjects (mean age 62 +/- 11 years, range 25-85 years-245 men). Of the 351 subjects, 305 had a coronary angiogram, the remaining 46 subjects were normal volunteers studied for research protocols. In total, 233 subjects (76%) were found to have significant CAD of whom 128 had multi-vessel disease. There were no deaths, myocardial infarctions, or episodes of bronchospasm during the CMR study. Transient 2nd (Mobitz II) or 3rd-degree atrioventricular (AV) block occurred in 27 patients (8%). There were no sustained episodes of advanced AV block. Transient chest pain was the most common side effect (199 subjects-57%). The use of intravenous adenosine in CMR perfusion imaging is safe and well-tolerated, even in patients with severe CAD. Where a careful screening policy for contraindications to adenosine is followed, serious adverse events in the CMR scanner are relatively rare and symptoms resolve following termination of the infusion, without the need for aminophylline.
TL;DR: In symptomatic angina patients, a negative CTCA reliably excludes significant CAD but the additional value of CTC a decreases sharply with CS >10 and especially with CS>400, while in patients with CS <10, CTCa provides excellent diagnostic performance.
Abstract: Present guidelines discourage the use of CT coronary angiography (CTCA) in symptomatic angina patients. We examined the relation between coronary calcium score (CS) and the performance of CTCA in patients with stable and unstable angina in order to understand under which conditions CTCA might be a gate-keeper to conventional coronary angiography (CCA) in such patients. We included 360 patients between 50 and 70 years old with stable and unstable angina who were clinically referred for CCA irrespective of CS. Patients received CS and CCTA on 64-slice scanners in a multicenter cross-sectional trial. The institutional review board approved the study. Diagnostic performance of CTCA to detect or rule out significant coronary artery disease was calculated on a per patient level in pre-defined CS categories. The prevalence of significant coronary artery disease strongly increased with CS. Negative CTCA were associated with a negative likelihood ratio of 400 it decreased to 1.3. In the 62 (17%) patients with CS 10 and especially with CS >400. In patients with CS <10, CTCA provides excellent diagnostic performance.
TL;DR: A meta-analysis of the published literature evaluating the accuracy of CT planimetry to measure the aortic valve area suggests that multi-detector CT is an accurate method for obtaining AVA measurements in patients with AS.
Abstract: Degenerative aortic valve stenosis (AS) has an incidence of 2–7% in the Western European and North American populations over 65 years of age. The aim of this study was to perform a meta-analysis of the published literature evaluating the accuracy of CT planimetry to measure the aortic valve area. The PUBMED and OVID databases were searched up to May 2008. Major criteria for article inclusion was the use of (a) multi-detector computed tomography as a diagnostic test for the assessment of AVA in patients with AS, and (b) TTE as the reference standard. Nine studies were included in the analysis with 175 women and 262 men. The mean AVA as measured by CT was 1.0 ± 0.1. The mean AVA measured by TTE was 0.9 ± 0.1. The correlation between CT and TTE AVA measurements was r = 1.45. The mean difference was 0.03 ± 0.05. The results of our meta-analysis suggest that multi-detector CT is an accurate method for obtaining AVA measurements in patients with AS.
TL;DR: There is an impairment in longitudinal left ventricular systolic function in patients with SCF, and global and regional strain rate were decreased in SCF.
Abstract: Slow coronary flow (SCF) is a well recognized clinical entity, characterized by delayed opacification of coronary arteries in the presence of normal coronary angiogram. There is currently no data evaluating myocardial systolic function in SCF phenomenon. This study was performed to evaluate regional and global systolic function using tissue Doppler imaging (TDI), strain (S) and strain rate imaging (SRI) in patients with slow coronary flow. A total of 35 patients with slow coronary flow and otherwise normal coronary arteries (mean age 48 ± 7 years) (SCF group) and 21 patients with normal coronary angiograms (mean age 50 ± 12 years) (control group) were included in the study. These patients were prospectively assessed for evaluation of regional and global left ventricular function by conventional echocardiography, systolic TDI, peak S, and peak systolic strain rates (SRs) There was a significant difference in peak SRs (−1.1 ± 0.2 vs. −1.8 ± 0.2 1/s, P ≤ 0.0001) but similar in systolic TDI (42 ± 20 vs. 44 ± 21 mm/s, P = 0.77) and S (20.7 ± 7.7 vs. 23.7 ± 8.8, P = 0.14) between groups. SRs showed a good correlation with mean TIMI frame count (r = −0.80, P ≤ 0.0001). As the number of coronary artery with SCF increased global strain rate decreased further. In case of one or two or three coronary artery with SCF global strain rates were 1.4 ± 0.2; 1.1 ± 0.3; 0.9 ± 0.2 1/s, respectively, P ≤ 0.0001. Although ejection fraction was preserved, global and regional strain rate were decreased in SCF. In brief, there is an impairment in longitudinal left ventricular systolic function in patients with SCF.
TL;DR: In patients suspected of CAD, low fingertip temperature rebound measured by DTM significantly predicted CTA-diagnosed obstructive disease, and all DTM indices of vascular and neurovascular reactivity significantly decreased from normal to non-obstructive to obstructive CAD.
Abstract: Previous studies showed strong correlations between low fingertip temperature rebound measured by digital thermal monitoring (DTM) during a 5 min arm-cuff induced reactive hyperemia and both the Framingham Risk Score (FRS), and coronary artery calcification (CAC) in asymptomatic populations. This study evaluates the correlation between DTM and coronary artery disease (CAD) measured by CT angiography (CTA) in symptomatic patients. It also investigates the correlation between CTA and a new index of neurovascular reactivity measured by DTM. 129 patients, age 63 ± 9 years, 68% male, underwent DTM, CAC and CTA. Adjusted DTM indices in the occluded arm were calculated: temperature rebound: aTR and area under the temperature curve aTMP-AUC. DTM neurovascular reactivity (NVR) index was measured based on increased fingertip temperature in the non-occluded arm. Obstructive CAD was defined as ≥50% luminal stenosis, and normal as no stenosis and CAC = 0. Baseline fingertip temperature was not different across the groups. However, all DTM indices of vascular and neurovascular reactivity significantly decreased from normal to non-obstructive to obstructive CAD [(aTR 1.77 ± 1.18 to 1.24 ± 1.14 to 0.94 ± 0.92) (P = 0.009), (aTMP-AUC: 355.6 ± 242.4 to 277.4 ± 182.4 to 184.4 ± 171.2) (P = 0.001), (NVR: 161.5 ± 147.4 to 77.6 ± 88.2 to 48.8 ± 63.8) (P = 0.015)]. After adjusting for risk factors, the odds ratio for obstructive CAD compared to normal in the lowest versus two upper tertiles of FRS, aTR, aTMP-AUC, and NVR were 2.41 (1.02–5.93), P = 0.05, 8.67 (2.6–9.4), P = 0.001, 11.62 (5.1–28.7), P = 0.001, and 3.58 (1.09–11.69), P = 0.01, respectively. DTM indices and FRS combined resulted in a ROC curve area of 0.88 for the prediction of obstructive CAD. In patients suspected of CAD, low fingertip temperature rebound measured by DTM significantly predicted CTA-diagnosed obstructive disease.
TL;DR: Dynamic z-collimation for retrospectively ECG-gated spiral scanning and adaptive z-Collimation for prospectivelyECG-triggered axial scanning are both associated with a significant dose reduction on a wide coverage, 256-slice CT scanner.
Abstract: Purpose This paper aims to evaluate the dose reductions conferred by spiral dynamic z-collimation and axial adaptive z-collimation for retrospectively and prospectively ECG-referenced cardiac CTA, respectively, on a wide coverage, 256-slice CT scanner. Methods Using typical data presented in the literature, a distribution of cardiac CT scan lengths was synthesized. To isolate the effect of z-overscan on effective radiation dose, 1,000 simulated patient scan lengths were then randomly sampled from this distribution and used for subsequent analysis. Results Retrospectively ECG-gated spiral scans with dynamic z-collimation resulted in a mean relative effective dose reduction of 11.7 and 24.3% for MDCT with 40 and 80 mm z-axis detector coverage, respectively. Mean relative dose reduction of prospectively ECG-triggered axial scans with adaptive z-collimation on an 80 mm coverage scanner was 10.0%. Conclusion Dynamic z-collimation for retrospectively ECG-gated spiral scanning and adaptive z-collimation for prospectively ECG-triggered axial scanning are both associated with a significant dose reduction on a wide coverage, 256-slice CT scanner.
TL;DR: FDG PET can quantify in vivo macrophage content and serially monitor changes in FDG activity in this rabbit model of atherosclerosis.
Abstract: We investigated the ability of fluorodeoxyglucose positron emission tomography (FDG PET) imaging to serially monitor macrophage content in a rabbit model of atherosclerosis. Atherosclerosis was induced in rabbits (n = 8) by a combination of atherogenic diet and balloon denudation of the aorta. At the end of nine months, the rabbits were randomized to a further six months of the same atherogenic diet (progression group) or normal diet (regression group). In vivo uptake of FDG by the thoracic aorta was measured using aortic uptake-to-blood radioactivity ratios at the start and end of the randomized period. A significant increase in FDG uptake of the progression group after continued cholesterol feeding (aortic uptake-to-blood radioactivity: 0.57 ± 0.02 to 0.68 ± 0.02, P = 0.001), and a corresponding fall in FDG uptake of the regression group after returning to a normal chow diet (aortic uptake-to-blood radioactivity ratios: 0.67 ± 0.02 to 0.53 ± 0.02, P < 0.0001). FDG PET can quantify in vivo macrophage content and serially monitor changes in FDG activity in this rabbit model.
TL;DR: The experience using prospective gating in specific areas is reviewed to include patient selection, patient preparation, use of β- and calcium-channel-blockers for heart rate control, selection of gating technique and scan parameters, radiation dose, and post-processing techniques.
Abstract: Cardiac CT exams have recently come under increased scrutiny because of their relatively high radiation dose. The most effective way to lower the dose of coronary computed tomography angiography (CCTA) exams is with the use of prospective gating. This allows for a significant reduction in effective radiation dose when compared to retrospective ECG gating while image quality is maintained or improved. We reviewed data from 2,124 consecutive cardiac CT exams, including 1,978 CCTA’s and 146 CCTA’s post CABG. With effective heart rate control, prospective gating was used for 92.1% of the CCTAs and 83.2% of CCTAs following CABG. The prospectively gated CCTAs had a mean effective dose of 3.1 ± 1.5 mSv, CCTAs following CABG had a mean dose of 6.4 ± 2.3 mSv. We review our experience using prospective gating in specific areas to include patient selection, patient preparation, use of β- and calcium-channel-blockers for heart rate control, selection of gating technique and scan parameters, radiation dose, and post-processing techniques.
TL;DR: Clinical significance of incidental extracardiac findings at cardiac CT angiography with precontrast low-dose whole thoracic scan (LDCT) and ECG-gated CCTA is compared and a considerable number of extracARDiac findings are detected only on LDCT.
Abstract: Purpose To compare the prevalence and clinical significance of incidental extracardiac findings at cardiac CT angiography (CCTA) with precontrast low-dose whole thoracic scan (LDCT) and ECG-gated CCTA. Materials and Methods We reviewed 254 patients who underwent CCTA. All participants first underwent LDCT to determine a range for CCTA and to screen unrecognized extracardiac lesions. CCTA was reconstructed with a small field of view of the heart. Clinically significant extracardiac findings were defined as abnormalities requiring further diagnostic work up, therapeutic intervention, or follow-up. Results On LDCT, 285 extracardiac findings were detected in 62.6% patients; on CCTA, 18 findings in 7% patients. Among these, 66 findings in 20.4% patients were considered clinically significant on LDCT, and 4 findings in 1.6% patients on CCTA. Conclusion Clinically significant extracardiac findings are common in patients undergoing CCTA with a considerable number of extracardiac findings being detected only on LDCT. We advise performing whole thorax LDCT prior to CCTA.
TL;DR: Patients with type 2 DM tend to have atherosclerotic plaques which are more likely to be mixed in nature, whereas no such differences were observed for non-calcified or calcified plaques.
Abstract: Type 2 diabetes mellitus (DM) is associated with a higher risk of cardiovascular disease and atherosclerotic burden. However little data exists in regards to plaque distribution and plaque composition in these patients. To assess for differences in the coronary plaques burden and composition among symptomatic patients with and without type 2 DM using multidetector computed tomography angiography (MDCTA). The 416 symptomatic patients (64% males, mean age: 61 +/- 13 years) with 61 (15%) reporting type 2 DM, who underwent contrast-enhanced MDCTA were studied. Enrolled patients had an intermediate to high pre-test probability of obstructive coronary artery disease. Multivariate analysis was used to correct for differences in age and gender. Patients with type 2 DM were more likely to have significant stenosis >or=70% in at least one coronary segments (33% in type 2 DM vs. 18% in non diabetic, P = 0.013), whereas 11% of both type 2 DM and non diabetics had stenosis of 50-70% (P = NS). Also type 2 DM patients had a higher number of coronary segments with mixed plaques compared to nondiabetic patients (1.67 +/- 2.01 vs. 1.23 +/- 1.61, P = 0.05), whereas no such differences were observed for non-calcified or calcified plaques. Nearly half (43%) of type 2 DM had coronary artery calcium scores (CACS) >or=400 vs. 29% in non diabetic patients (P = 0.03). Patients with type 2 DM tend to have atherosclerotic plaques which are more likely to be mixed in nature. Future studies need to elucidate the prognostic value of differences in plaque characteristics observed according to type 2 diabetic status.
TL;DR: CTCA can help identify features that most influence current success rates of PCI such as marked calcifications at the stump, severe tortuosity of the proximal vessel, long length of the Occluded segment as well location of the vessel distal to the occlusion, which often may not be well seen on conventional angiography.
Abstract: Chronic total occlusions (CTO) of the coronary arteries are a common finding. A CTO can be underdiagnosed on CT coronary angiography (CTCA) as a high grade stenosis, because of the presence of retrograde collaterals which allow opacification of the vessel distal to the stenosis, or can be missed completely, especially if another adjacent opacified artery is mistaken for occluded artery. CTOs are considered as Type C or high risk lesions with a higher restenosis rate and increased technical failure rate by percutaneous coronary intervention (PCI). CTCA can help identify features that most influence current success rates of PCI such as marked calcifications at the stump, severe tortuosity of the proximal vessel, long length of the occluded segment as well location of the vessel distal to the occlusion, which often may not be well seen on conventional angiography. Identification of these features and displaying the 3D information as the best angiographic projection that demonstrates the length and orientation of the CTO, either as hard copy images or transmitted direct to the angiographic catheter lab for data fusion, allows strategic preprocedural planning and scheduling of the PCI. Myocardial viability of the affected area of the occluded segment is a major factor that influences whether PCI for CTO is attempted but is not currently readily available by cardiac CT. Contrast enhanced cardiac MR imaging is still the gold standard for this and may need to be performed prior to PCI.
TL;DR: In mild-to-moderate atherosclerotic coronary artery disease the reproducibility of volumetric compositional RF-IVUS measurements from the same pullback is relatively high, but lower than the reproduCibility of geometrical IVUS measurements.
Abstract: Intravascular ultrasound radiofrequency (RF-IVUS) data permit the analysis of coronary plaque composition in vivo and is used as an endpoint of ongoing pharmacological intervention trials. We assessed the reproducibility of volumetric RF-IVUS analyses in mild-to-moderately diseased atherosclerotic human coronary arteries in vivo. A total of 9,212 IVUS analyses on cross-sectional IVUS frames was performed to evaluate the reproducibility of volumetric RF-IVUS measurements in 33 coronary segments with a length of 27 ± 7 mm. For vessel, lumen, and plaque + media volume the relative measurement differences (P = NS for all) were (A = intraobserver comparison, same pullback) −0.40 ± 1.0%; −0.48 ± 1.4%; −0.35 ± 1.6%, (B = intraobserver comparison, repeated pullback) −0.42 ± 1.2%; −0.52 ± 1.8%; −0.43 ± 4.5% (C = interobserver comparison, same pullback) 0.71 ± 1.8%; 0.71 ± 2.2%, and 0.89 ± 5.0%, respectively. For fibrous, fibro-lipidic, calcium, and necrotic-core volumes the relative measurement differences (P = NS for all) were (A) 0.45 ± 2.1%; −1.12 ± 4.9%; −0.84 ± 2.1%; −0.22 ± 1.8%, (B) 1.40 ± 4.1%; 1.26 ± 6.7%; 2.66 ± 7.4%; 0.85 ± 4.4%, and (C) −1.60 ± 4.9%; 3.85 ± 8.2%; 1.66 ± 7.5%, and −1.58 ± 4.7%, respectively. Of note, necrotic-core volume showed on average the lowest measurement variability. Thus, in mild-to-moderate atherosclerotic coronary artery disease the reproducibility of volumetric compositional RF-IVUS measurements from the same pullback is relatively high, but lower than the reproducibility of geometrical IVUS measurements. Measurements from repeated pullbacks and by different observers show acceptable reproducibilities; the volumetric measurement of the necrotic-core shows on average the highest reproducibility of the compositional RF-IVUS measurements
TL;DR: After successfully overcoming the impact of BMI on image noise by adapting tube parameters, CNR mainly depends on coronary vessel contrast, which reflects the dilution of the contrast material by blood volume and CO, which are both correlated to BSA.
Abstract: We evaluated the determinants of vessel contrast in prospectively ECG-triggered CT coronary angiography (CTCA). Seventy patients underwent low-dose CTCA using Body Mass Index (BMI)-adapted tube parameters and a fixed contrast material bolus. Contrast to noise ratio (CNR) was calculated from contrast (between coronaries and perivascular tissue) and image noise (standard deviation of aortic attenuation). Cardiac output (CO) was calculated from gated 99mTc-tetrofosmin-SPECT. Mean radiation dose was 2.13 ± 0.69 mSv. Image noise was not affected by BMI (r = 0.1, P = 0.36), while CNR was inversely related to body surface area (BSA) (r = −0.5, P < 0.001) and CO (r = −0.45, P < 0.001). After successfully overcoming the impact of BMI on image noise by adapting tube parameters, CNR mainly depends on coronary vessel contrast. The latter reflects the dilution of the contrast material by blood volume and CO, which are both correlated to BSA. Therefore, BSA adapted contrast administration may help to compensate for this effect.
TL;DR: This scientifically-based OVM evaluation of coronary vessel segments provides the means to facilitate acquisitions during coronary angiography and interventions that minimize imaging inaccuracies related to foreshortening and overlap, improving the accuracy, efficiency, and safety of diagnostic and interventional coronary procedures.
Abstract: Current expert-recommended views for coronary angiography are based on heuristic experience and have not been scientifically studied. We sought to identify optimal viewing regions for first and second order vessel segments of the coronary arteries that provide optimal diagnostic value in terms of minimizing vessel foreshortening and overlap. Using orthogonal 2D images of the coronary tree, 3D models were created from which patient-specific optimal view maps (OVM) allowing quantitative assessment of vessel foreshortening and overlap were generated. Using a novel methodology that averages 3D-based optimal projection geometries, a universal OVM was created for each individual coronary vessel segment that minimized both vessel foreshortening and overlap. A universal OVM model for each coronary segment was generated based on data from 137 patients undergoing coronary angiography. We identified viewing regions for each vessel segment achieving a mean vessel foreshortening value of 5.8 ± 3.9% for the left coronary artery (LCA) and 5.6 ± 3.6% for the right coronary artery (RCA). The overall mean overlap values achieved were 8.7 ± 7.9% for the LCA and 4.6 ± 3.2% for the RCA. This scientifically-based OVM evaluation of coronary vessel segments provides the means to facilitate acquisitions during coronary angiography and interventions that minimize imaging inaccuracies related to foreshortening and overlap, improving the accuracy, efficiency, and safety of diagnostic and interventional coronary procedures.