Outcome of early revascularization surgery in patients with ST-elevation myocardial infarction.

OBJECTIVES: To compare morbidity and mortality of patients with ST-elevation myocardial infarction (MI) undergoing coronary artery bypass graft (CABG) surgery within 24 hours with those who had surgery delayed >24 hours. BACKGROUND: Patients with ST-elevation MI are currently managed by emergency percutaneous coronary intervention (PCI). If PCI is unsuccessful, or if there is severe coronary artery disease not amenable to PCI, CABG is considered. If the patient is clinically stable, surgeons wait several days before performing surgery, as very early surgery carries a prohibitive risk. METHODS: One hundred and eighty-four patients with acute ST elevation MI (STEMI) who had undergone CABG were divided into two groups based on their surgery timing (<24 hours vs. >24 hours). Mortality and complication rates were studied between the two groups by Fischer test. Time-to-event analyses were performed for five primary variables: all-cause mortality, cardiac events, congestive heart failure, stroke, and renal failure. RESULTS: At one month post-CABC, all-cause mortality was noted in 10.6% of patients who had CABG within 24 hours of STEMI diagnosis, compared with 8.9% in patients who had CABG after 24 hours (P = 0.3). Cardiac events including re-exploration, atrial fibrillation, graft occlusion, and arrhythmias requiring shock occurred in 17.1% versus 13.9% between the two groups, respectively (P = 0.68). One year post-coronary artery bypass surgery, there was no difference in individual or combined events between the two groups. CONCLUSIONS: In patients with ST-elevation myocardial infarction who required emergency coronary artery bypass surgery, there was no difference in procedure complications or mortality between early (within 24 hours) or later (more than 24 hours). That was noted at one month and one year after the index myocardial infarction.

Absorbed radiation dose in radiosensitive organs using 64- and 320-row multidetector computed tomography: a comparative study.

Aim. To determine absorbed radiation dose (ARD) in radiosensitive organs during prospective and full phase dose modulation using ECG-gated MDCTA scanner under 64- and 320-row detector modes. Methods. Female phantom was used to measure organ radiation dose. Five DP-3 radiation detectors were used to measure ARD to lungs, breast, and thyroid using the Aquilion ONE scanner in 64- and 320-row modes using both prospective and dose modulation in full phase acquisition. Five measurements were made using three tube voltages: 100, 120, and 135 kVp at 400 mA at heart rate (HR) of 60 and 75 bpm for each protocol. Mean acquisition was recorded in milligrays (mGy). Results. Mean ARD was less for 320-row versus 64-row mode for each imaging protocol. Prospective EKG-gated imaging protocol resulted in a statistically lower ARD using 320-row versus 64-row modes for midbreast (6.728 versus 19.687 mGy, P < 0.001), lung (6.102 versus 21.841 mGy, P < 0.001), and thyroid gland (0.208 versus 0.913 mGy; P < 0.001). Retrospective imaging using 320- versus 64-row modes showed lower ARD for midbreast (10.839 versus 43.169 mGy, P < 0.001), lung (8.848 versus 47.877 mGy, P < 0.001), and thyroid gland (0.057 versus 2.091 mGy; P < 0.001). ARD reduction was observed at lower kVp and heart rate. Conclusions. Dose reduction to radiosensitive organs is achieved using 320-row compared to 64-row modes for both prospective and retrospective gating, whereas 64-row mode is equivalent to the same model 64-row MDCT scanner.

Cancerogenesis Risks between 64 and 320 Row Detector CT for Coronary CTA Screening.

OBJECTIVES: This study compares cancerogenesis risks posed by the 64 row detector and the 320 row detector computed tomography scanners used during coronary computed tomography angiography (CCTA) following decennial screening guidelines. MATERIAL AND METHODS: Data of the radiation absorbed after CCTA by lung, thyroid, and female breast in patients between 50 and 70 years of age obtained from prior published literature for the 64 row CT scanner were compared with data from our study using 320 row detector CT scanner. Data from the 64 row and the 320 row detector CT scanners was used to determine lifetime attributable risks (LAR) of cancer based on the biological effects of ionizing radiation (BEIR) VII report. RESULTS: The relative reduction of LAR (%) for 50-, 60-, and 70-year-old patients undergoing scanning with the 320 row detector CT scanner was 30% lower for lung, and more than 50% lower for female breast when compared with results from 64 row detector CT scanner. The use of 320 row detector CT would result in a combined cumulative cancer incidence of less than 1/500 for breast in women and less than 1/1000 for lung in men; By comparison, this is much lower than other more common risk factors: 16-fold for lung cancer in persistent smokers, 2-fold for breast cancer with a first degree family member history of breast cancer, and 10-fold for thyroid cancer with a family member with thyroid cancer. Decennial screening would benefit at least 355,000 patients from sudden cardiac death each year, 94% of whom have significant coronary artery disease, with at least one stenosis >75%. LAR for thyroid cancer was negligible for both scanners. CONCLUSION: Lung and female breast LAR reductions with 320 row detector compared with 64 row detector CT are substantial, and the benefits would outweigh increased cancer risks with decennial screening in the age group of 50-70 years.

Assessment of liver fat in an obese patient population using noncontrast CT fat percent index.

OBJECTIVE: To develop a simplified method to quantify liver fat using computed tomography (CT) fat % index (CTFPI) compared to liver spleen method (CTL/S, CTL-S). METHODS: Noncontrast CT of the liver was performed in 89 patients (overweight, obese, severely obese) to quantify fat, using the following: CTFPI=[(65-patient HU)/65]×100, normal live r=65 HU. RESULTS: There was a strong linear correlation between CTFPI and the standard method of assessing liver fat using CTL/S (r=-0.901), CTL-S (r=-0.911). Hepatic HU and CTFPI were significantly different in the severely obese group compared to other two groups (P<.05). CONCLUSION: Significant correlation indicates equal diagnostic accuracy of the two methods in appropriately calibrated scanners.

Comparison of coronary plaque subtypes in male and female patients using 320-row MDCTA.

OBJECTIVE: Determine plaque subtype and volume difference in male and female patients with obstructive and non-obstructive CAD using 320-row MDCTA. MATERIALS AND METHODS: 128 patients with suspected CAD underwent MDCTA. All studies were divided into two groups based on disease severity. 0-70% stenosis (non-obstructive CAD) & >70% (obstructive). All were compared for plaque quantity and subtypes by gender. Main arteries, RCA, LM, LAD and LCX were analyzed using Vitrea 5.2 software to quantify fatty, fibrous and calcified plaque. Thresholds for coronary plaque quantification (volume in mm(3)) were preset at 35 ± 12 HU for fatty, 90 ± 24 HU for fibrous and >130 HU for calcified/mixed plaque and analyzed using STATA software. RESULTS: Total plaque burden in 118 patients [65M: 53F] was significantly higher in all arteries in males compared to females with non-obstructive disease. Total plaque volume for males vs. females was: RCA: 10.10 ± 5.02 mm(3) vs. 6.89 ± 2.75 mm(3), respectively, p = 0.001; LAD: 7.21 ± 3.38 mm(3) vs. 5.89 ± 1.93 mm(3), respectively, p = 0.04; LCX: 9.13 ± 3.27 mm(3) vs. 7.16 ± 1.73 mm(3), respectively, p = 0.002; LM 15.13 ± 4.51 mm(3) vs. 11.85 ± 4.03 mm(3), respectively, p = 0.001. In sub-analyses, males had significantly more fibrous and fatty plaque in LM, LAD & LCX than females. However in the RCA, only fibrous plaque was significantly greater in males. Calcified plaque volume was not significantly different in both genders. Only 8% of patients had obstructive CAD (>70% stenosis); there was no significant difference in plaque volume or subtypes. CONCLUSION: In patients with non-obstructive CAD, males were found to have significantly higher total coronary plaque volume with predominance of fibrous and fatty subtypes compared to females of the same age and BMI. There was no significant difference in plaque subtype or volume in patients with obstructive disease.

Effect of Tube Voltage (100 vs. 120 kVp) on Radiation Dose and Image Quality using Prospective Gating 320 Row Multi-detector Computed Tomography Angiography.

OBJECTIVES: The objective of the following study is to evaluate the effect of reducing tube voltage from 120 to 100 kVp using prospective gating 320 row multi-detector computed tomography angiography on image quality and reduction in radiation dose. MATERIALS AND METHODS: A total of 78 sequential patients were scanned with prospective electrocardiogram gating. A total of 45 patients (Group 1) with mean body mass index (BMI) 29 ± 2 and heart rate (HR) 57 ± 7 beats per minute (BPM) were scanned at 120 kVp. 33 patients (Group 2) with mean BMI 23 ± 3 and HR 58 ± 6 bpm were scanned at 100 kVp. Effective dose was calculated using dose length product and factor (k = 0.014). Quantitative assessment of image quality was calculated by measuring signal to noise ratio (SNR) and contrast to noise ratio (CNR) in the left ventricle and left main coronary artery. Two experienced cardiac radiologists using a three-point ordinal scale assessed subjectively image quality. RESULTS: In Group 1, the median radiation dose was 5.31 mSv (95% confidence interval [CI]: 4.86-6.09) and for Group 2 (P = 0.009) the mean radiation dose was 3.71 mSv (95% CI: 2.76-4.87), representing 30% decrease in radiation dose. In multivariate analyses, adjusting for age, gender, HR, BMI, tube current and scan length, an absolute median reduction of 2.21 mSv (1.13-3.29 mSv) was noted in patients scanned with 100 kVp (P < 0.0001). The quantitative image quality (SNR and CNR) was not statistically significant between the groups. Subjective image quality was rated as good or excellent in 99% of coronary segments for both groups (P value was considered as non-significant). CONCLUSION: Our study suggests that radiation dose may be lowered from 120 to 100 kVp with preservation of image quality in patient's whose BMI is ≤27.

Mortality rates in smokers and nonsmokers in the presence or absence of coronary artery calcification.

OBJECTIVES: The aim of this study was to further explore the interplay between smoking status, coronary artery calcium (CAC), and all-cause mortality. BACKGROUND: Prior studies have not directly compared the relative prognostic impact of CAC in smokers versus nonsmokers. In particular, although a calcium score of zero (CAC = 0) is a known favorable prognostic marker, whether smokers with CAC = 0 have as good a prognosis as nonsmokers with CAC = 0 is unknown. Given that computed tomography (CT) screening for lung cancer appears effective in smokers, the relative prognostic implications of visualizing any CAC versus no CAC on such screening also deserve study. METHODS: Our study cohort consisted of 44,042 asymptomatic individuals referred for noncontrast cardiac CT (age 54 ± 11 years, 54% men). Subjects were followed for a mean of 5.6 years. The primary endpoint was all-cause mortality. RESULTS: Approximately 14% (n = 6,020) of subjects were active smokers at enrollment. There were 901 deaths (2.05%) overall, with increased mortality in smokers versus nonsmokers (4.3% vs. 1.7%, p < 0.0001). Smoking remained a risk factor for mortality across increasing strata of CAC scores (1 to 100, 101 to 400, and >400). At each stratum of elevated CAC score, mortality in smokers was consistently higher than mortality in nonsmokers from the CAC stratum above. In multivariable analysis within these strata, we found mortality hazard ratios of 3.8 (95% confidence interval [CI]: 2.8 to 5.2), 3.5 (95% CI: 2.6 to 4.9), and 2.7 (95% CI: 2.1 to 3.5), respectively, in smokers compared with nonsmokers. However, among the 19,898 individuals with CAC = 0, the mortality hazard ratio for smokers without CAC was 3.6 (95% CI: 2.3 to 5.7), compared with nonsmokers without CAC. CONCLUSIONS: Smoking is a risk factor for death across the entire spectrum of subclinical coronary atherosclerosis. Smokers with any CAC had significantly higher mortality than smokers without CAC, a finding with implications for smokers undergoing lung cancer CT-based screening. However, the absence of CAC might not be as useful a "negative risk factor" in active smokers, because this group has mortality rates similar to nonsmokers with mild-to-moderate atherosclerosis.

Interplay of coronary artery calcification and traditional risk factors for the prediction of all-cause mortality in asymptomatic individuals.

BACKGROUND: Current guidelines recommend the use of coronary artery calcium (CAC) scoring for intermediate-risk patients; however, the potential role of CAC among individuals who have no risk factors (RFs) is less established. We sought to examine the relationship between the presence and burden of traditional RFs and CAC for the prediction of all-cause mortality. METHODS AND RESULTS: The study cohort consisted of 44,052 consecutive asymptomatic individuals free of known coronary heart disease referred for computed tomography for the assessment of CAC. The following RFs were considered: (1) current cigarette smoking, (2) dyslipidemia, (3) diabetes mellitus, (4) hypertension, and (5) family history of coronary heart disease. Patients were followed for a mean of 5.6 ± 2.6 years for the primary end point of all-cause mortality. Among individuals who had no RF, Cox proportional model adjusted for age and sex identified that increasing CAC scores were associated with 3.00- to 13.38-fold higher mortality risk. The lowest survival rate was observed in those with no CAC and no RF, whereas those with CAC ≥ 400 and ≥3 RFs had the highest all-cause fatality rate. Notably, individuals with no RF and CAC ≥ 400 had a substantially higher mortality rate compared with individuals with ≥3 RFs in the absence of CAC (16.89 versus 2.72 per 1000 person-years). CONCLUSIONS: By highlighting that individuals without RFs but elevated CAC have a substantially higher event rates than those who have multiple RFs but no CAC, these findings challenge the exclusive use of traditional risk assessment algorithms for guiding the intensity of primary prevention therapies.

Primary and metastatic vascular neoplasms: imaging findings.

OBJECTIVE: The purpose of this article is to review the imaging findings of vascular tumors. CONCLUSION: Tumors of the vasculature are a pervasive disease entity consisting of both primary and metastatic lesions. Cross-sectional imaging plays a pivotal role in the diagnosis and delineation of the extent of this entity. Recognition of the characteristic imaging presentation of each tumor at CT and MRI can facilitate prompt diagnosis and accurate staging.

Relation of aortic valve calcium detected by cardiac computed tomography to all-cause mortality.

Aortic valve calcium (AVC) can be quantified on the same computed tomographic scan as coronary artery calcium (CAC). Although CAC is an established predictor of cardiovascular events, limited evidence is available for an independent predictive value for AVC. We studied a cohort of 8,401 asymptomatic subjects (mean age 53 ± 10 years, 69% men), who were free of known coronary heart disease and were undergoing electron beam computed tomography for assessment of subclinical atherosclerosis. The patients were followed for a median of 5 years (range 1 to 7) for the occurrence of mortality from any cause. Multivariate Cox regression models were developed to predict all-cause mortality according to the presence of AVC. A total of 517 patients (6%) had AVC on electron beam computed tomography. During follow-up, 124 patients died (1.5%), for an overall survival rate of 96.1% and 98.7% for those with and without AVC, respectively (hazard ratio 3.39, 95% confidence interval 2.09 to 5.49). After adjustment for age, gender, hypertension, dyslipidemia, diabetes mellitus, smoking, and a family history of premature coronary heart disease, AVC remained a significant predictor of mortality (hazard ratio 1.82, 95% confidence interval 1.11 to 2.98). Likelihood ratio chi-square statistics demonstrated that the addition of AVC contributed significantly to the prediction of mortality in a model adjusted for traditional risk factors (chi-square = 5.03, p = 0.03) as well as traditional risk factors plus the presence of CAC (chi-square = 3.58, p = 0.05). In conclusion, AVC was associated with increased all-cause mortality, independent of the traditional risk factors and the presence of CAC.

Absorbed radiation dose in radiosensitive organs during coronary CT angiography using 320-MDCT: effect of maximum tube voltage and heart rate variations.

OBJECTIVE: The purpose of this article is to estimate the absorbed radiation dose in radiosensitive organs during coronary MDCT angiography using 320-MDCT and to determine the effects of tube voltage variation and heart rate (HR) control on absorbed radiation dose. MATERIALS AND METHODS: Semiconductor field effect transistor detectors were used to measure absorbed radiation doses for the thyroid, midbreast, breast, and midlung in an anthropomorphic phantom at 100, 120, and 135 kVp at two different HRs of 60 and 75 beats per minute (bpm) with a scan field of view of 320 mm, 400 mA, 320 × 0.5 mm detectors, and 160 mm collimator width (160 mm range). The paired Student's t test was used for data evaluation. RESULTS: At 60 bpm, absorbed radiation doses for 100, 120, and 135 kVp were 13.41 ± 3.59, 21.7 ± 4.12, and 29.28 ± 5.17 mGy, respectively, for midbreast; 11.76 ± 0.58, 18.86 ± 1.06, and 24.82 ± 1.45 mGy, respectively, for breast; 12.19 ± 2.59, 19.09 ± 3.12, and 26.48 ± 5.0 mGy, respectively, for lung; and 0.37 ± 0.14, 0.69 ± 0.14, and 0.92 ± 0.2 mGy, respectively, for thyroid. Corresponding absorbed radiation doses for 75 bpm were 38.34 ± 2.02, 59.72 ± 3.13, and 77.8 ± 3.67 mGy for midbreast; 26.2 ± 1.74, 44 ± 1.11, and 52.84 ± 4.07 mGy for breast; 38.02 ± 1.58, 58.89 ± 1.68, and 78 ± 2.93 mGy for lung; and 0.79 ± 0.233, 1.04 ± 0.18, and 2.24 ± 0.52 mGy for thyroid. Absorbed radiation dose changes were significant for all organs for both tube voltage reductions as well as for HR control from 75 to 60 bpm at all tube voltage settings (p < 0.05). The absorbed radiation doses for the calcium score protocol were 11.2 ± 1.4 mGy for midbreast, 9.12 ± 0.48 mGy for breast, 10.36 ± 1.3 mGy for lung, and 0.4 ± 0.05 mGy for thyroid. CONCLUSION: CT angiography with 320-MDCT scanners results in absorbed radiation doses in radiosensitive organs that compare favorably to those previously reported. Significant dose reductions can be achieved by tube voltage reductions and HR control.