Computed Tomography Coronary Angiography Studies Research Articles

Radiation dose analysis of computed tomography coronary angiography in Children with Kawasaki disease.

There is evolving role of computed tomography coronary angiography (CTCA) in non-invasive evaluation of coronary artery abnormalities in children with Kawasaki disease (KD). Despite this, there is lack of data on radiation dose in this group of children undergoing CTCA. To audit the radiation dose of CTCA in children with KD. Study (December 2013-February 2018) was performed on dual source CT scanner using adaptive prospective electrocardiography-triggering. The dose length product (DLP in milligray-centimeters-mGy.cm) was recorded. Effective radiation dose (millisieverts-mSv) was calculated by applying appropriate age adjusted conversion factors as per recommendations of International Commission on Radiological Protection. Radiation dose was compared across the groups (0-1, 1-5, 5-10, and > 10 years). Eighty-five children (71 boys, 14 girls) with KD underwent CTCA. The median age was 5 years (range, 2 mo-11 years). Median DLP and effective dose was 21 mGy.cm, interquartile ranges (IQR) = 15 (13, 28) and 0.83 mSv, IQR = 0.33 (0.68, 1.01) respectively. Mean DLP increased significantly across the age groups. Mean effective dose in infants (0.63 mSv) was significantly lower than the other age groups (1-5 years 0.85 mSv, 5-10 years 1.04 mSv, and > 10 years 1.38 mSv) (P < 0.05). There was no significant difference in the effective dose between the other groups of children. All the CTCA studies were of diagnostic quality. No child required a repeat examination. CTCA is feasible with submillisievert radiation dose in most children with KD. Thus, CTCA has the potential to be an important adjunctive imaging modality in children with KD.

Resource implications following expansion of computed tomography coronary angiography: An Australian experience.

To determine the downstream utilisation of Computed Tomography Coronary Angiography (CTCA) in a single Australian tertiary centre. A single-centre retrospective study analysed 1460 patients undergoing CTCA between 1st January 2015 to 31st December 2018 at a tertiary hospital in Victoria, Australia, with a catchment area of 500,000 people. The coronary stenosis grading, plaque characteristics and coronary calcium score were identified. The downstream impact was assessed by measuring the number of stress echocardiograms, myocardial perfusion scans (MPS), invasive coronary angiograms and subsequent revascularisations. The number of CTCA's performed steadily increased from 59 in 2015 to 395, 461 and 545 in 2016, 2017 and 2018 respectively. Seven hundred and fifty-seven (52%) were females, and 703 (48%) males with 724 (50%) normal CTCA studies. The number of downstream stress echocardiogram performed each year was 2, 60, 46 and 16, respectively, accompanied by MPS numbers of 0, 21, 29, and 18. There were 9, 37, 57 and 64 invasive coronary angiograms with 1, 13, 19 and 22 corresponding revascularisations. Despite small increases in absolute numbers of patients presenting with chest pain (from 2678 in 2015 to 3660 in 2018), there was a significant increase in downstream further testing from 11 in 2015 to 98 in 2018. The use of CTCA expansion has resulted in an increase in downstream testing. Therefore, resource planning with regards to CTCA expansion will have to account for increased rates of functional testing, invasive angiography and revascularisation.

A comprehensive, contemporary assessment of the association between the presence of hepatosteatosis and the incidence of coronary artery disease on CT coronary angiography

Abstract Funding Acknowledgements Type of funding sources: None. Background The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing exponentially. The overall prevalence of NAFLD in the United States is predicted to increase to 33.5% of the adult population by 2030. Hepatosteatosis (HS) has been previously shown to be an independent risk factor for cardiovascular disease events. We sought to investigate the association of clinical covariates and the presence of HS and coronary artery disease (CAD) in patients referred for computed tomography coronary angiography (CTCA). Methods We performed a retrospective, observational analysis at a high-volume cardiac CT centre analysing consecutive CTCA studies. All patients referred for investigation of chest pain over a 28-month period (June 2014 to November 2016) were included. Covariates in those with CAD and patients without CAD were compared using compared using student"s t-test for continuous variables and chi-squared test for categorical variables. Logistic regression models were constructed for the multivariate analysis. Results In total there were 1499 patients referred for CTCA without prior evidence of CAD. Age, male sex, presence of hypertension and diabetes were significantly higher in those with CAD (table 1). HS evaluation was assessed in 1195 (79.7%). In the multivariate analysis significant predictors of CAD were male sex (OR 3.40, p &amp;lt; 0.001), family history (OR 1.90, p = 0.003), current smoking (OR 1.80, p = 0.03) and increasing age (OR 1.12, p &amp;lt; 0.001). The presence of HS was not associated with CAD when adjusted for risk factors (OR 1.05 CI:0.70-1.60, p = 0.80). Conclusion We found a significant association between the increasing age, presence of hypertension, male sex, diabetes and current smoking with presence of CAD as detected by CTCA. In contrast to recent evidence HS may not be an independent risk factor for the development of the development of CAD. Summary statistics of the cohort No CAD (n = 881) CAD (n = 618) P Age (mean (SD)) 48.86 (±12.1) 57.9(±10.6) &amp;lt;0.005* Male Sex (%) 343 (38.6%) 326 (51.1%) &amp;lt;0.005* Hypertension (%) 193(21.9%) 239 (38.7%) &amp;lt;0.005* Diabetes (%) 59 (6.7%) 86 (13.9%) &amp;lt;0.005* Current Smoking (%) 139 (15.8%) 108 (17.5%) 0.423 FHx (%) 239 (27.1%) 167 (27%) 1 HS (%) 291 (33%) 247 (40%) 0.007* A comparison of clinical covariates for the cohort stratified by the presence of coronary artery disease. Statistical significance was assumed when p &amp;lt; 0.05 and is denoted with *.

04 Relationship between erectile dysfunction and silent myocardial ischemia in diabetic patients: a multidetector computed tomography coronary angiography study

As silent myocardial ischemia (SMI) is a strong predictor of early death especially in patients with diabetes mellitus (DM), our study aims to evaluate the relationship between erectile dysfunction (ED) severity and SMI in DM patients using the multidetector computed tomography coronary angiography (MDCT-CA), and to identify predicators of SMI.

Shepherd’s crook right coronary artery: a multidetector computed tomography coronary angiography study

Shepherd's crook deformity of the right coronary artery (RCA) is considered a haemodynamically non-significant course anomaly. It may be challenging for cardiologists during percutaneous transluminal coronary angioplasty. To investigate the radiological anatomy of the high riding course of the proximal segment of the RCA, especially focused on the Shepherd's crook RCA (SCRCA), on multidetector computed tomography (MDCT) coronary angiography. A total of 1,118 MDCT coronary angiography examinations were reviewed retrospectively (349 [31.2%] male; 769 [68.8%] female, age range from 18 to 88 years [54.4 ± 14.7 years, mean ± standard deviation]). We classified the segments that had a higher course than RCA ostium (high riding RCA) into two types: type 1--courses turning inferior with an angle equal to or more than 90 degrees, type 2 (SCRCA)--courses turning inferior with an angle less than 90 degrees. The origin of the sinoatrial node artery (SANA) and conus artery were also noted. High riding RCA was detected in 146 (13%) patients. Of them, 105 (71%) had type 1 and 41 (29%) had type 2. Atherosclerotic plaque formations, to varying degrees, were presented in 10 (24.3%) of the patients with SCRCA. Approximately half of SANA originated from the SCRCA segment of the RCA in SCRCA cases. This is the first study about SCRCA that has been performed with MDCT coronary angiography. This study brings important anatomical knowledge to cardiologists. To have knowledge about the origin of the SANA prior to PTCA procedures is important to prevent possible arrhythmias and infarcts.

Radiation dose and positive predictive value of revascularisation with low dose myocardialperfusion scintigraphy compared with computed tomography coronary angiography

Background: To evaluate the radiation dose and positive predictive value (PPV) of the need for revascularisation of contemporary (low dose) Myocardial Perfusion Scintigraphy (MPS) compared with Computed Tomography Coronary Angiography (CTCA).Methods: We consecutively reviewed 314 MPS and 221 CTCA studies performed at our hospital in 2013. Stress/Rest MPS studies were performed with exercise and/or adenosine using Sestamibi Tc99m and a solid state Cadmium Zinc Telluride gamma camera. CTCA was performed using a 256 slice CT. Radiation exposure was measured in milisievert (mSv). Positive tests leading to invasive coronary angiography were used to determine the PPV of the need for revascularisation.Results: For demographics see table 1. The main indication for tests in both cohorts was chest pain (>75%). Patients undergoing MPS were older, more likely to have diabetes, and had worse renal function compared with CTCA (p< 0.01).Table 1MPSCTCAP valueAge (years)66.09 ± 43.5353.00 ± 13.79<0.01eGFR73.42 ± 19.2484.04 ± 9.55<0.01Diabetes111/314 (35%)49/221(22%)0.001Radiation (mSv)6.80 ± 2.075.64 ± 3.29<0.01PPV21/41 (51%)21/26 (80%)0.02 Open table in a new tab 41/314 (13%) MPS and 26/221 (11%) CTCA patients proceeded to have coronary angiography. There was a small but statistically significant reduction in radiation dose for CTCA compared with MPS (p< 0.01). CTCA was significantly better at predicting the need for revascularisation compared with MPS (PPV 80% vs 51%, p: 0.02).Conclusions: Despite lower than usual dose MPS utilising contemporary techniques, radiation dose remained lower with CTCA. CTCA had a higher PPV of the need for revascularisation compared with MPS in our non-randomised evaluation. Background: To evaluate the radiation dose and positive predictive value (PPV) of the need for revascularisation of contemporary (low dose) Myocardial Perfusion Scintigraphy (MPS) compared with Computed Tomography Coronary Angiography (CTCA). Methods: We consecutively reviewed 314 MPS and 221 CTCA studies performed at our hospital in 2013. Stress/Rest MPS studies were performed with exercise and/or adenosine using Sestamibi Tc99m and a solid state Cadmium Zinc Telluride gamma camera. CTCA was performed using a 256 slice CT. Radiation exposure was measured in milisievert (mSv). Positive tests leading to invasive coronary angiography were used to determine the PPV of the need for revascularisation. Results: For demographics see table 1. The main indication for tests in both cohorts was chest pain (>75%). Patients undergoing MPS were older, more likely to have diabetes, and had worse renal function compared with CTCA (p< 0.01). 41/314 (13%) MPS and 26/221 (11%) CTCA patients proceeded to have coronary angiography. There was a small but statistically significant reduction in radiation dose for CTCA compared with MPS (p< 0.01). CTCA was significantly better at predicting the need for revascularisation compared with MPS (PPV 80% vs 51%, p: 0.02). Conclusions: Despite lower than usual dose MPS utilising contemporary techniques, radiation dose remained lower with CTCA. CTCA had a higher PPV of the need for revascularisation compared with MPS in our non-randomised evaluation. CSANZ NZ AbstractsHeart, Lung and CirculationVol. 23Preview Full-Text PDF

Variation in Coronary Anatomy in Adult Patients Late After Arterial Switch Operation: A Computed Tomography Coronary Angiography Study

The arterial switch operation is the current treatment for transposition of the great arteries. Long-term outcome mainly depends on the patency of the transferred coronary arteries. This study assessed the presence of abnormal coronary findings and neoaortic root dilation late after arterial switch operation. In 30 adult patients after arterial switch operation (22 men, 22 ± 3 years), computed tomography angiography was performed to assess the coronary anatomy and abnormal coronary findings, defined as significant stenosis, interarterial coronary course, and acute angled coronary origins. Neoaortic root dimensions and coronary takeoff height were also assessed. The most common coronary anatomy pattern was found in 24 of 30 patients. Variant anatomy patterns were seen in 6 patients (5 with aberrant circumflex artery, 1 with a single ostium). The prevalence of abnormal coronary findings was higher in patients with variant coronary pattern as compared with patients with common coronary pattern (100% and 29%, respectively; p= 0.003). In particular, an acute angle of the coronary origin was frequently observed. In patients with an acute angle, larger dimensions of the aortic annulus (p= 0.016) and the sinus of Valsalva (p= 0.002) were observed. Moreover, a higher takeoff of the right (p= 0.030) and left (p= 0.002) coronary ostium was noted in patients with acute angles. Abnormal coronary findings were frequently observed in adult patients after arterial switch operation, especially in patients with a variant coronary anatomy pattern. Neoaortic root dilation and a higher coronary takeoff may explain part of the pathophysiology. Long-term follow-up is needed to determine the clinical significance of these findings.

Non-invasive computed tomography coronary angiography as a gatekeeper for invasive coronary angiography

To determine the rate of subsequent invasive coronary angiography (ICA) and revascularization in relation to computed tomography coronary angiography (CTA) results. In addition, independent determinants of subsequent ICA and revascularization were evaluated. CTA studies were performed using a 64-row (n = 413) or 320-row (n = 224) multidetector scanner. The presence and severity of CAD were determined on CTA. Following CTA, patients were followed up for 1 year for the occurrence of ICA and revascularization. A total of 637 patients (296 male, 56 ± 12 years) were enrolled and 578 CTA investigations were available for analysis. In patients with significant CAD on CTA, subsequent ICA rate was 76 %. Among patients with non-significant CAD on CTA, subsequent ICA rate was 20 % and among patients with normal CTA results, subsequent ICA rate was 5.7 % (p < 0.001). Of patients with significant CAD on CTA, revascularization rate was 47 %, as compared to a revascularization rate of 0.6 % in patients with non-significant CAD on CTA and no revascularizations in patients with a normal CTA results (p < 0.001). Significant CAD on CTA and significant three-vessel or left main disease on CTA were identified as the strongest independent predictors of ICA and revascularization. CTA results are strong and independent determinants of subsequent ICA and revascularization. Consequently, CTA has the potential to serve as a gatekeeper for ICA to identify patients who are most likely to benefit from revascularization and exclude patients who can safely avoid ICA.

Diagnostic Accuracy of Combined Coronary Angiography and Adenosine Stress Myocardial Perfusion Imaging Using 320-Detector Computed Tomography: A Pilot Study

Background: Computed tomography coronary angiography (CTA) is established for the non-invasive diagnosis of coronary artery disease (CAD), however in its current form CTA is limited in detecting myocardial ischaemia. We sought to determine whether adenosine stress CT myocardial perfusion imaging (CTP), when added to CTA, identifies perfusion abnormalities caused by obstructive CAD. Methods: Twenty patients (age 66 ± 9 years, 65% male) with no known CAD but abnormal single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) underwent prospectively-gated adenosine stress 320-detector CTP and CTA, as well as invasive coronary angiography (ICA) within 60 days of SPECT-MPI. A blinded interventional cardiologist evaluated ICA images. A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. CTP and CTA studies were assessed qualitatively by consensus between two blinded cardiologists. Vessels/territories with both >50% stenosis on ICA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard against which combined CTP and CTA were compared. Results: All patients completed the CT protocol with diagnostic image quality (60 vessels/territories available for analysis). Sixteen vessels/territories (27%) were ischaemic by combined ICA and SPECT-MPI criteria. Sensitivity, specificity, positive predictive value and negative predictive value for combined CTP and CTA was 94%, 96%, 88%, and 98%, respectively on a per-vessel/territory basis. Mean combined CTP and CTA radiation dose was 9.2 ± 6.1 mSv compared to 13.2 ± 2.2 mSv for SPECT-MPI (p = 0.06). Conclusions: Combined 320-detector CTP and CTA is accurate in identifying obstructive CAD causing perfusion abnormalities when compared with combined ICA and SPECT-MPI. This is achieved with acceptable radiation dose, comparable to SPECT-MPI.

Diagnostic performance of 320-slice multidetector computed tomography coronary angiography in patients after coronary artery bypass grafting

ObjectivesTo evaluate the diagnostic performance of 320-slice computed tomography coronary angiography (CTA) in the evaluation of patients with prior coronary artery bypass grafting (CABG). Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach.MethodsCTA studies were performed using CT equipment with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 0.35 s. All grafts, recipient and nongrafted vessels were deemed interpretable or uninterpretable. The presence of significant (≥50%) stenosis and occlusion were determined on vessel and patient basis. Results were compared to ICA using quantitative coronary angiography.ResultsA total of 40 patients (28 men, 76 ± 15 years), with 89 grafts, were included in the study. On a graft analysis, the sensitivity, specificity, positive and negative predictive values in the evaluation of significant stenosis were 96%, 92%, 83% and 98% respectively. The diagnostic accuracy for the assessment of recipient and nongrafted vessels was 89% and 80%, respectively. The diagnostic accuracy for the assessment of graft, recipient and nongrafted vessel occlusion was 96%, 92% and 100%, respectively.Conclusions320-slice CTA allows accurate non-invasive assessment of significant graft, recipient vessel and nongrafted vessel stenosis in patients with prior CABG.

The presence, characterization and prognosis of coronary plaques among patients with zero coronary calcium scores

Patients with coronary artery calcium (CAC) scores of zero are generally considered not to have atherosclerosis. Recent studies involving computed tomography coronary angiography (CTCA) challenge this assumption. This goal of the present study is to assess the frequency, morphology, location, and the prognosis of patients with plaque detected on CTCA and zero CAC. 1,119 patients (51±12years, 52% male) with a zero CAC score during CTCA study were retrospectively identified. The CTCA studies were assessed for the presence, morphology, location and severity of all coronary plaques. All-cause mortality was assessed. The prevalence of coronary plaque was 13% (147 patients). Among the 212 plaques identified 154 (73%) were non-calcified, 28 (13%) were calcified, and 30 (14%) were of mixed morphology. Notably, ≥70% stenosis was noted among only 0.4% of all patients. ROC analysis revealed that coronary artery disease risk factors did not add to the prediction of plaque among our patients. Over a mean follow-up of 2.5±0.6years there were 4 deaths (0.4%), all in patients without coronary plaque on CTCA. The presence of coronary plaque is not uncommon among patients with zero CAC scores. These plaques were rarely associated with hemodynamically significant stenoses and were associated with an excellent prognosis. Clinical factors do not appear to be useful in predicting which patients with zero CAC scores have undetected coronary plaque.

190: Real World Use of 320 Detector Computed Tomography Coronary Angiography for Chest Pain Triage In the Emergency Department

Chest pain is a common presenting complaint in emergency department (ED) patients. While diagnosing acute coronary syndrome (ACS) is straightforward, evaluating the extent of coronary artery disease (CAD) is time and resource intensive. Routine use of outpatient stress testing does not guarantee follow-up for all patients. Computed tomography coronary angiography (CTCA) makes it possible to conduct CAD testing prior to ED discharge. The purpose of this study was to evaluate the real-world effectiveness of CTCA in ED patients with chest pain. We conducted a cohort study comparing outcomes in 100 ED patients with chest pain from a single academic center by an intention to treat analysis. One patient cohort (n=50) underwent CTCA during the index ED visit while the other cohort (n=50) was given a prescription for an outpatient stress test. Comparisons were made of the duration of ED visit, the completion of CAD testing, and 3-month adverse events (return ED visit for chest pain, myocardial infarction, or death). Standard statistical methods for comparing continuous and categorical variables were used. Differences in baseline characteristics were negligible. The CT cohort was older (mean age 47.0 years versus 41.3 in control, p = 0.009) and mean BMI in both cohorts was in the obese range (31.5 kg/m2 for the CT cohort, 31.6 kg/m2 for control, p = 0.94) CAD testing was completed in significantly more patients in the CT cohort (48 patients versus 18 patients in the control cohort, p < 0.0001). For 2 CT patients, scanner malfunction resulted in no scan being performed, while in control patients, 32 failed to complete follow-up testing. Three CTCA studies were nondiagnostic due to excessive artifacts. Median CAC was 0 Agatston units (interquartile range [IQR] 0 - 1.5) and 34 patients (71% of 48 with successful CTCA) had a CAC score of zero. Detection of CAD was significantly higher in the CT cohort (14 patients versus 1 patient in the control cohort, p = 0.0004). Obstructive CAD (> 50% stenosis of a coronary artery) was found in 6 CT patients and only 1 control patient (p = 0.11). Median duration of stay was 417.5 minutes (IQR 359 - 581) in the CT cohort and 400 minutes (IQR 338 - 471) in the control cohort (p = 0.53). Patient subgroups were evaluated based on their time of ED arrival, but no subgroup had significantly different duration of stay. During 3 months of follow-up, four patients in each cohort were reevaluated in the ED for chest pain, while no patients suffered MI or death. The routine use of CTCA for evaluating ED patients with chest pain dramatically improves completion of CAD testing without any significant effect on the duration of stay. The prevalence of CAD in the tested population is notable and the majority of patients with CAD will go undetected using a strategy of routine outpatient follow-up stress testing. After ruling out ACS, patients can likely be discharged safely with expected 3-month event rates to be low. Further study is necessary to determine if greater accuracy in CTCA detecting CAD could reduce adverse outcomes, return ED visits, and redundant workups for chest pain.

Diagnostic Accuracy of 320-Row Multidetector Computed Tomography Coronary Angiography to Noninvasively Assess In-Stent Restenosis

Percutaneous coronary intervention with stent implantation is routinely performed to treat patients with obstructive coronary artery disease. However, thus far, noninvasive assessment of in-stent restenosis has been challenging. Recently, 320-row multidetector computed tomography coronary angiography (CTA) was introduced, allowing volumetric image acquisition of the heart in a single heart beat or gantry rotation. The aim of this study was to evaluate the diagnostic performance of 320-row CTA in the evaluation of significant in-stent restenosis. Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach. The population consisted of patients with previous coronary stent implantation who were clinically referred for cardiac evaluation because of recurrent chest pain and who underwent both CTA and ICA. CTA studies were performed using a 320-row CTA scanner with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 350 milliseconds. Tube voltage and current were adapted to body mass index and thoracic anatomy. The entire heart was imaged in a single heart beat, with a maximum of 16-cm craniocaudal coverage. During the scan, the ECG was registered simultaneously for prospective triggering of the data. First, CTA stent image quality was assessed using a 3-point grading scale: (1) good image quality, (2) moderate image quality, and (3) poor image quality. Subsequently, the presence of in-stent restenosis was determined on a stent and patient basis by a blinded observer. Significant in-stent restenosis was defined as >or=50% luminal narrowing in the stent lumen or the presence of significant stent edge stenosis. Overlapping stents were considered to represent a single stent. Results were compared with ICA using quantitative coronary angiography. In addition, CTA stent image quality and diagnostic accuracy were related to stent characteristics and heart rate during CTA image acquisition. The population consisted of 53 patients (37 men, mean age: 65 +/- 13 years) with a total of 89 stents available for evaluation. ICA identified 12 stents (13%) with significant in-stent restenosis. A total of 7 stents (8%) were of nondiagnostic CTA stent image quality, and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 92%, 83%, 46%, and 98%, respectively on a stent basis. Five CTA studies (9%) were of nondiagnostic quality for the evaluation of in-stent restenosis and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 100%, 81%, 58%, and 100%, respectively on a patient level. Stent diameter <3 mm as well as stent strut thickness >or=140 mum were associated with decreased CTA stent image quality and diagnostic accuracy. Heart rate during CTA acquisition and stent overlap were not associated with image degradation. The present results show that 320-row CTA allows accurate noninvasive assessment of significant in-stent restenosis. However, stents with a large diameter and thin struts allowed better in-stent visualization than stents with a small diameter or thick struts. Consequently, noninvasive assessment of in-stent restenosis using CTA may be an attractive and feasible alternative particularly in carefully selected patients.

Evaluation of a Computed Tomography Coronary Angiography Scan – Advantages and Disadvantages of Different Post-processing Techniques

Computed tomography coronary angiography (CTCA) is increasingly performed worldwide. For the interpretation of the acquired data set, different post-processing techniques are available, such as multiplanar reformation, maximum-intensity projections, direct volume rendering, virtual coronary angioscopy or the angiographic view. Each of these techniques shows certain advantages and disadvantages during application and image interpretation. Thus, a combination of post-processing techniques for the interpretation of CTCA studies should be used. When starting to perform and interpret CTCA, a systematic approach is mandatory for accurate diagnosis. We developed a practical algorithm in our institution for the interpretation of CTCA studies with special emphasis on interpretation steps to avoid a false-negative or false-positive diagnosis. In this article we discuss the strengths and weaknesses of the different post-processing techniques available for evaluation of CTCA and provide a systematic approach for interpreting a CTCA study, with an emphasis on how to avoid false-positive and false-negative classifications.

Estimating Risk of Cancer Associated With Radiation Exposure From 64-Slice Computed Tomography Coronary Angiography

Computed tomography coronary angiography (CTCA) has become a common diagnostic test, yet there are little data on its associated cancer risk. The recent Biological Effects of Ionizing Radiation (BEIR) VII Phase 2 report provides a framework for estimating lifetime attributable risk (LAR) of cancer incidence associated with radiation exposure from a CTCA study, using the most current data available on health effects of radiation. To determine the LAR of cancer incidence associated with radiation exposure from a 64-slice CTCA study and to evaluate the influence of age, sex, and scan protocol on cancer risk. Organ doses from 64-slice CTCA to standardized phantom (computational model) male and female patients were estimated using Monte Carlo simulation methods, using standard spiral CT protocols. Age- and sex-specific LARs of individual cancers were estimated using the approach of BEIR VII and summed to obtain whole-body LARs. Whole-body and organ LARs of cancer incidence. Organ doses ranged from 42 to 91 mSv for the lungs and 50 to 80 mSv for the female breast. Lifetime cancer risk estimates for standard cardiac scans varied from 1 in 143 for a 20-year-old woman to 1 in 3261 for an 80-year-old man. Use of simulated electrocardiographically controlled tube current modulation (ECTCM) decreased these risk estimates to 1 in 219 and 1 in 5017, respectively. Estimated cancer risks using ECTCM for a 60-year-old woman and a 60-year-old man were 1 in 715 and 1 in 1911, respectively. A combined scan of the heart and aorta had higher LARs, up to 1 in 114 for a 20-year-old woman. The highest organ LARs were for lung cancer and, in younger women, breast cancer. These estimates derived from our simulation models suggest that use of 64-slice CTCA is associated with a nonnegligible LAR of cancer. This risk varies markedly and is considerably greater for women, younger patients, and for combined cardiac and aortic scans.

New Technology for Noninvasive Evaluation of Coronary Artery Disease

Cardiac computed tomography (CT) and positron emission tomography (PET) are emerging as powerful noninvasive imaging tools for the evaluation of atherosclerosis in patients with known or suspected coronary artery disease (CAD). Unlike invasive coronary angiography, CT coronary angiography (CTA) not only assesses disease within the coronary lumen but can also provide direct qualitative and quantitative information about nonobstructive atherosclerotic plaque burden within the vessel wall. Thus, it is possible that CTA-based patient evaluation may provide more clinically relevant information on which to base risk assessments compared with conventional “lumenography.” On the other hand, PET is rapidly growing as a powerful and efficient alternative to conventional single-photon emission CT (SPECT) imaging to evaluate regional myocardial perfusion and metabolism in patients with CAD. In addition, PET scanners are now being converted to hybrid PET/CT devices, which, in the setting of CAD, offer the potential for a comprehensive noninvasive cardiac evaluation of anatomy and function. This review will discuss current and potential future applications of cardiovascular CT, PET, and hybrid PET/CT, with a particular focus on ischemic heart disease. The information provided by noninvasive imaging generally falls into 1 of 3 categories: myocardial perfusion, left ventricular (LV) function, or coronary artery anatomy. The clinical utility, value, and role of a noninvasive modality are based on 2 test characteristics: What type of information is provided (eg, stress perfusion, stress and/or rest LV function, coronary anatomy), and what is the accuracy of the information provided. For example, SPECT and PET both provide stress and rest perfusion information, but the latter will be a superior clinical tool if the imaging data better represent the actual defect size and are subject to less artifact. The advantage of PET over SPECT will be further enhanced, as will be discussed later, if it provides additional clinically relevant information not …

Effect of the Reconstruction Window Obtained at the Isovolumic Relaxation Period on the Image Quality in Electrocardiographic-Gated 16-Multidetector-Row Computed Tomography Coronary Angiography Studies

To evaluate whether images obtained during the reconstruction window responding to the isovolumic relaxation period could be used for rapid and easy postprocessing. One hundred ten consecutive patients with suspected coronary artery disease who had previously had a multidetector computed tomography (MDCT) scan for imaging coronary arteries were enrolled in this study. The age of the patients was 59 +/- 13 years (range: 33-78 years), and 77 (70%) were male. Multidetector computed tomography was performed on a 16-detector-row computed tomography scanner during 1 breath hold (16-24 seconds). Seven different sets of images reconstructed at every 10% of the R-R interval from 30% to 90% for contrast-enhanced scans at levels containing the first several centimeters of the left and right coronary arteries were analyzed. The best of these reconstruction windows were then compared with the images reconstructed at the isovolumic relaxation period, which is the last portion of the T wave at the end of the systole, where there is not any change in ventricular volume, which causes stepladder artifacts. The step artifact was classified as excellent, good, or poor. Image quality was assessed by 2 radiologists who were not aware of each other's interpretation. According to the routinely used reconstructions, there were 76 patients with excellent image quality, 28 with good image quality, and 6 with poor image quality. For the period of isovolumic relaxation, there were 74 patients with excellent image quality, 25 with good image quality, and 11 with poor image quality. If one begins image analysis with the isovolumic relaxation period reconstruction window, spending less time for postprocessing analyses, good image quality can be obtained such as with other good reconstruction windows.