Prognostic value of extracardiac incidental findings on attenuation correction cardiac computed tomography

Although both race and socioeconomic status are well known to influence mortality patterns in the United States, few studies have examined the simultaneous influence of these factors on cancer incidence and mortality. We examined relationships among race, education level, and mortality from cancers of the lung, breast, prostate, colon and rectum, and all sites combined in contemporary US vital statistics. Age-adjusted cancer death rates (with 95% confidence intervals [CIs]) were calculated for 137,708 deaths among 119,376,196 individuals aged 25-64 years, using race and education information from death certificates and population denominator data from the US Bureau of the Census, for 47 states and Washington, DC, in 2001. Relative risk (RR) estimates were used to compare cancer death rates in persons with 12 or fewer years of education with those in persons with more than 12 years of education. Educational attainment was strongly and inversely associated with mortality from all cancers combined in black and white men and in white women. The all-cancer death rates were nearly identical for black men and white men with 0-8 years of education (224.2 and 223.6 per 100,000, respectively). The estimated relative risk for all-cancer mortality comparing the three lowest ( 12 years) education categories was 2.38 (95% CI = 2.33 to 2.43) for black men, 2.24 (95% CI = 2.23 to 2.26) for white men, 1.43 (95% CI = 1.41 to 1.46) for black women, and 1.76 (95% CI = 1.75 to 1.78) for white women. For both men and women, the magnitude of the relative risks comparing the three lowest educational levels with the three highest within each race for all cancers combined and for lung and colorectal cancers was higher than the magnitude of the relative risks associated with race within each level of education, whereas for breast and prostate cancer the magnitude of the relative risks associated with race was higher than the magnitude of the relative risks associated with level of education within each racial group. Among the most important and novel findings were that black men who completed 12 or fewer years of education had a prostate cancer death rate that was more than double that of black men with more schooling (10.5 versus 4.8 per 100,000 men; RR = 2.17, 95% CI = 1.82 to 2.58) and that, in contrast with studies of mortality rates in earlier time periods, breast cancer mortality rates were higher among women with less education than among women with more education (37.0 and 31.1 per 100,000, respectively, for black women and 25.2 versus 18.6 per 100,000, respectively, for white women). Cancer death rates vary considerably by level of education. Identifying groups at high risk of death from cancer by level of education as well as by race may be useful in targeting interventions and tracking cancer disparities.

SPECT is a rapidly changing field, and the past several years have produced new developments in both hardware technology and image-processing algorithms. At the component level there have been improvements in scintillators and photon transducers as well as a greater availability of semiconductor technology. These devices permit the fabrication of smaller and more compact systems that can be customized for particular applications. New clinical devices include high-count sensitivity cardiac SPECT systems that do not use conventional collimation and the introduction of diagnostic-quality hybrid SPECT/CT systems. While there has been steady progress with reconstruction algorithms, exciting new processing algorithms have become commercially available that promise to provide substantial reductions in SPECT acquisition time without sacrificing diagnostic quality. Preclinical small-animal SPECT systems have become a major focus in nuclear medicine. These systems have pushed the limits of SPECT into the submillimeter range, making them valuable molecular imaging tools capable of providing information unavailable from other modalities.

Myocardial perfusion scans contribute up to 20% of the estimated annual collective radiation dose to the US population. We estimated potential future cancer risk from these scans by age at exposure and current frequency of use in the United States. Usage patterns were determined from national survey data, and radionuclide dosage was based on current guidelines. Cancer risk projection models were generated on the basis of the National Research Council Biological Effects of Ionizing Radiation VII report, under the assumption that risk has a linear relationship with radiation exposure even at low doses. The mean projected number of radiation-related incident cancers and 95% uncertainty intervals were estimated with the use of Monte Carlo simulations. Estimated risks for a scan performed at age 50 years ranged from 2 cancers per 10,000 scans (95% uncertainty interval, 1 to 5) for a positron emission tomography ammonia-13 test to 25 cancers per 10,000 scans (95% uncertainty interval, 9 to 58) for a dual-isotope (thallium-201 plus technetium-99m) scan. Risks were 50% lower at age 70 years but were similar for men and women. The combination of cancer risk estimates and data on frequency of use suggests that the 9.1 million myocardial perfusion scans performed annually in the United States could result in 7400 (95% uncertainty interval, 3300 to 13,700) additional future cancers. The lifetime cancer risk from a single myocardial perfusion scan is small and should be balanced against likely benefit and appropriateness of the test. The estimates depend on a number of assumptions, including life expectancy. They apply directly to asymptomatic individuals with life expectancies similar to those of the general population. For individuals with a symptomatic clinical profile, on whom such scans are typically performed, the risks will be lower because of shorter life expectancy.