Incidental imaging findings from routine chest CT used to identify subjects at high risk of future cardiovascular events.

PURPOSE: To investigate the contribution of incidental findings at chest computed tomography (CT) in the detection of subjects at high risk for cardiovascular disease (CVD) by deriving and validating a CT-based prediction rule. MATERIALS AND METHODS: This retrospective study was approved by the ethical review board of the primary participating facility, and informed consent was waived. The derivation cohort comprised 10 410 patients who underwent diagnostic chest CT for noncardiovascular indications. During a mean follow-up of 3.7 years (maximum, 7.0 years), 1148 CVD events (cases) were identified. By using a case-cohort approach, CT scans from the cases and from an approximately 10% random sample of the baseline cohort (n = 1366) were graded visually for several cardiovascular findings. Multivariable Cox proportional hazards analysis with backward elimination technique was used to derive the best-fitting parsimonious prediction model. External validation (discrimination, calibration, and risk stratification) was performed in a separate validation cohort (n = 1653). RESULTS: The final model included patient age and sex, CT indication, left anterior descending coronary artery calcifications, mitral valve calcifications, descending aorta calcifications, and cardiac diameter. The model demonstrated good discriminative value, with a C statistic of 0.71 (95% confidence interval: 0.68, 0.74) and a good overall calibration, as assessed in the validation cohort. This imaging-based model allows accurate stratification of individuals into clinically relevant risk categories. CONCLUSION: Structured reporting of incidental CT findings can mediate accurate stratification of individuals into clinically relevant risk categories and subsequently allow those at higher risk of future CVD events to be distinguished.

Coronary artery calcification scoring in low-dose ungated CT screening for lung cancer: interscan agreement.

OBJECTIVE: In previous studies detection of coronary artery calcification (CAC) with low-dose ungated MDCT performed for lung cancer screening has been compared with detection with cardiac CT. We evaluated the interscan agreement of CAC scores from two consecutive low-dose ungated MDCT examinations. SUBJECTS AND METHODS: The subjects were 584 participants in the screening segment of a lung cancer screening trial who underwent two low-dose ungated MDCT examinations within 4 months (mean, 3.1 +/- 0.6 months) of a baseline CT examination. Agatston score, volume score, and calcium mass score were measured by two observers. Interscan agreement of stratification of participants into four Agatston score risk categories (0, 1-100, 101-400, > 400) was assessed with kappa values. Interscan variability and 95% repeatability limits were calculated for all three calcium measures and compared by repeated measures analysis of variance. RESULTS: An Agatston score > 0 was detected in 443 baseline CT examinations (75.8%). Interscan agreement of the four risk categories was good (kappa = 0.67). The Agatston scores were in the same risk category in both examinations in 440 cases (75.3%); 578 participants (99.0%) had scores differing a maximum of one category. Furthermore, mean interscan variability ranged from 61% for calcium volume score to 71% for Agatston score (p < 0.01). A limitation of this study was that no comparison of CAC scores between low-dose ungated CT and the reference standard ECG-gated CT was performed. CONCLUSION: Cardiovascular disease risk stratification with low-dose ungated MDCT is feasible and has good interscan agreement of stratification of participants into Agatston score risk categories. High mean interscan variability precludes the use of this technique for monitoring CAC scores for individual patients.

Semiquantitative assessment of cardiovascular disease markers in multislice computed tomography of the chest: interobserver and intraobserver agreements.

OBJECTIVE: To investigate the interobserver and intraobserver agreements for the semiquantitative assessment of markers of subclinical cardiovascular disease as identified by routine care, diagnostic computed tomography (CT) of the chest, to improve the quality of reporting of these incidental findings. METHODS: Two observers independently evaluated 109 consecutive chest CT scans in routine care, clinical patients from one tertiary referral center. All nongated, contrast-enhanced scans were acquired on a 16-slice CT scanner. Images were scored for the presence of aortic wall abnormalities and calcifications of the coronary artery, the heart valves, the thoracic aorta, and the proximal supraaortic arteries. Furthermore, the presence of left ventricular scarring and elongation of the aorta were recorded. All markers were scored on a semiquantitative scale. Interobserver and intraobserver agreements are presented as weighted kappa and intraclass correlation coefficients. RESULTS: Interobserver and intraobserver agreements for individual markers were good to excellent, with weighted kappa coefficients of 0.54 to 0.89 for interobserver agreement and 0.55 to 0.96 for intraobserver agreement. CONCLUSIONS: Semiquantitative assessment of subclinical cardiovascular disease markers in routine care, diagnostic chest CT scans is possible with good to excellent interobserver and intraobserver agreements. Use of these definitions in clinical practice will enable a more standardized assessment and reporting of incidental findings in diagnostic chest CT.

Age and sex based reference values for incidental coronary artery and thoracic aorta calcifications on routine clinical chest CT: a powerful tool to appreciate available imaging findings.

OBJECTIVE: To establish age and gender specific reference values for incidental coronary artery and thoracic aorta calcification scores on routine diagnostic CT scans. These reference values can aid in structured reporting and interpretation of readily available imaging data by chest CT readers in routine practice. METHODS: A random sample of 1572 (57% male, median age 61 years) was taken from a study population of 12,063 subjects who underwent diagnostic chest CT for non-cardiovascular indications between January 2002 and December 2005. Coronary artery and thoracic aorta calcifications were graded using a validated ordinal score. The 25th, 50th and 75th percentile cut points were calculated for the coronary artery and thoracic aorta calcification scores within each age/gender stratum. RESULTS: The 75th percentile cut points for coronary artery calcification scores were higher for men than for women across all age groups, with the exception of the lowest age group. The 75th percentile cut points for thoracic aorta calcifications scores were comparable for both genders across all age groups. Based on the obtained age and gender reference values a calculation tool is provided, that allows one to enter an individual's age, gender and calcification scores to obtain the corresponding estimated percentiles. CONCLUSIONS: The calculation tool as provided in this study can be used in daily practice by CT readers to examine whether a subject has high calcifications scores relative to others with the same age and gender.

Prevalence of incidental findings in computed tomographic screening of the chest: a systematic review.

OBJECTIVE: To perform a systematic review on the prevalence of incidental findings in computed tomographic (CT) screening studies of the chest. METHODS: We selected CT screening studies of the chest (screening for coronary artery disease [CAD] [coronary calcium and CT coronary angiography] and lung cancer screening). Screening protocols, descriptions of baseline characteristics, range of incidental findings, and recommendations for follow-up were abstracted. RESULTS: Eleven chest CT screening studies were identified. The proportion of people with at least 1 imaging abnormality requiring follow-up varied widely between studies (3%-41.5%). This was largely due to considerable variation in follow-up recommendations for incidental findings across studies. Analyzed by subgroup, 7.7% (confidence interval, 7.0%-8.3%) of 6421 participants in CAD screening had further investigations compared with 14.2% (confidence interval, 13.2%-15.2%) of 4531 participants in lung cancer screening. CONCLUSIONS: In this review, 7.7% and 14.2% of patients undergoing either CAD or lung cancer screening with CT were found to have clinically significant incidental findings requiring additional investigations.