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Dive into the research topics where Peter C. Jacobs is active.

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Featured researches published by Peter C. Jacobs.


Journal of Computer Assisted Tomography | 2008

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

Peter C. Jacobs; Willem P. Th. M. Mali; Diederick E. Grobbee; Yolanda van der Graaf

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.


Atherosclerosis | 2010

Comparing coronary artery calcium and thoracic aorta calcium for prediction of all-cause mortality and cardiovascular events on low-dose non-gated computed tomography in a high-risk population of heavy smokers.

Peter C. Jacobs; Mathias Prokop; Yolanda van der Graaf; Martijn J. A. Gondrie; Kristel J.M. Janssen; Harry J. de Koning; Ivana Išgum; Rob J. van Klaveren; Matthijs Oudkerk; Bram van Ginneken; Willem P. Th. M. Mali

BACKGROUND Coronary artery calcium (CAC) and thoracic aorta calcium (TAC) can be detected simultaneously on low-dose, non-gated computed tomography (CT) scans. CAC has been shown to predict cardiovascular (CVD) and coronary (CHD) events. A comparable association between TAC and CVD events has yet to be established, but TAC could be a more reproducible alternative to CAC in low-dose, non-gated CT. This study compared CAC and TAC as independent predictors of all-cause mortality and cardiovascular events in a population of heavy smokers using low-dose, non-gated CT. METHODS Within the NELSON study, a population-based lung cancer screening trial, the CT screen group consisted of 7557 heavy smokers aged 50-75 years. Using a case-cohort study design, CAC and TAC scores were calculated in a total of 958 asymptomatic subjects who were followed up for all-cause death, and CVD, CHD and non-cardiac events (stroke, aortic aneurysm, peripheral arterial occlusive disease). We used Cox proportional-hazard regression to compute hazard ratios (HRs) with adjustment for traditional cardiovascular risk factors. RESULTS A close association between the prevalence of TAC and increasing levels of CAC was established (p<0.001). Increasing CAC and TAC risk categories were associated with all-cause mortality (p for trend=0.01 and 0.001, respectively) and CVD events (p for trend <0.001 and 0.03, respectively). Compared with the lowest quartile (reference category), multivariate-adjusted HRs across categories of CAC were higher (all-cause mortality, HR: 9.13 for highest quartile; CVD events, HR: 4.46 for highest quartile) than of TAC scores (HR: 5.45 and HR: 2.25, respectively). However, TAC is associated with non-coronary events (HR: 4.69 for highest quartile, p for trend=0.01) and CAC was not (HR: 3.06 for highest quartile, p for trend=0.40). CONCLUSIONS CAC was found to be a stronger predictor than TAC of all-cause mortality and CVD events in a high-risk population of heavy smokers scored on low-dose, non-gated CT. TAC, however, is stronger associated with non-cardiac events than CAC and could prove to be a preferred marker for these events.


American Journal of Roentgenology | 2012

Coronary artery calcium can predict all-cause mortality and cardiovascular events on low-dose ct screening for lung cancer

Peter C. Jacobs; Martijn J. A. Gondrie; Yolanda van der Graaf; Harry J. de Koning; Ivana Išgum; Bram van Ginneken; Willem P. Th. M. Mali

OBJECTIVE Performing coronary artery calcium (CAC) screening as part of low-dose CT lung cancer screening has been proposed as an efficient strategy to detect people with high cardiovascular risk and improve outcomes of primary prevention. This study aims to investigate whether CAC measured on low-dose CT in a population of former and current heavy smokers is an independent predictor of all-cause mortality and cardiac events. SUBJECTS AND METHODS We used a case-cohort study and included 958 subjects 50 years old or older within the screen group of a randomized controlled lung cancer screening trial. We used Cox proportional-hazard models to compute hazard ratios (HRs) adjusted for traditional cardiovascular risk factors to predict all-cause mortality and cardiovascular events. RESULTS During a median follow-up of 21.5 months, 56 deaths and 127 cardiovascular events occurred. Compared with a CAC score of 0, multivariate-adjusted HRs for all-cause mortality for CAC scores of 1-100, 101-1000, and more than 1000 were 3.00 (95% CI, 0.61-14.93), 6.13 (95% CI, 1.35-27.77), and 10.93 (95% CI, 2.36-50.60), respectively. Multivariate-adjusted HRs for coronary events were 1.38 (95% CI, 0.39-4.90), 3.04 (95% CI, 0.95-9.73), and 7.77 (95% CI, 2.44-24.75), respectively. CONCLUSION This study shows that CAC scoring as part of low-dose CT lung cancer screening can be used as an independent predictor of all-cause mortality and cardiovascular events.


Radiology | 2010

Cardiovascular disease:prediction with ancillary aortic findings on chest CT scans in routine practice

Martijn J. A. Gondrie; Willem P. Th. M. Mali; Peter C. Jacobs; Ay L. Oen; Yolanda van der Graaf

PURPOSE To predict cardiovascular disease (CVD) in a clinical care population by using prevalent subclinical ancillary aortic findings detected on chest computed tomographic (CT) images. MATERIALS AND METHODS The study was approved by the medical ethics committee of the primary participating facility and the institutional review boards of all other participating centers. From a total of 6975 patients who underwent diagnostic contrast material-enhanced chest CT for noncardiovascular indications, a representative sample population of 817 patients plus 347 patients who experienced a cardiovascular event during a mean follow-up period of 17 months were assigned visual scores for ancillary aortic abnormalities--on a scale of 0-8 for calcifications, a scale of 0-4 for plaques, a scale of 0-4 for irregularities, and a scale of 0-1 for elongation. Four Cox proportional hazard models incorporating different sum scores for the aortic abnormalities plus age, sex, and chest CT indication were compared for discrimination and calibration. The prediction model that performed best was chosen and externally validated. RESULTS Each aortic abnormality was highly predictive, and all models performed well (c index range, 0.70-0.72; goodness-of-fit P value range, .45-.76). The prediction model incorporating the sum score for aortic calcifications was chosen owing to its good performance (c index, 0.72; goodness-of-fit P = .47) and its applicability to nonenhanced CT scanning. Validation of this model in an external data set also revealed good performance (c index, 0.71; goodness-of-fit P = .25; sensitivity, 46%; specificity, 76%). CONCLUSION A derived prediction model incorporating ancillary aortic findings detected on routine diagnostic CT images complements established risk scores and may help to identify patients at high risk for CVD. Timely application of preventative measures may ultimately reduce the number or severity of CVD events.


American Journal of Roentgenology | 2010

Coronary Artery Calcification Scoring in Low-Dose Ungated CT Screening for Lung Cancer: Interscan Agreement

Peter C. Jacobs; Ivana Išgum; Martijn J. A. Gondrie; Willem P. Th. M. Mali; Bram van Ginneken; Mathias Prokop; Yolanda van der Graaf

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.


Radiology | 2014

Incidental Imaging Findings from Routine Chest CT Used to Identify Subjects at High Risk of Future Cardiovascular Events

Pushpa M. Jairam; Martijn J. A. Gondrie; Diederick E. Grobbee; Willem P. Th. M. Mali; Peter C. Jacobs; Yolanda van der Graaf

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.


Journal of Computer Assisted Tomography | 2010

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

Peter C. Jacobs; Mathias Prokop; Ayke L. Oen; Yolanda van der Graaf; Diederick E. Grobbee; Willem P. Th. M. Mali

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 &kgr; and intraclass correlation coefficients. Results: Interobserver and intraobserver agreements for individual markers were good to excellent, with weighted &kgr; 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.


European Journal of Epidemiology | 2010

The PROgnostic Value of unrequested Information in Diagnostic Imaging (PROVIDI) Study: rationale and design

Martijn J. A. Gondrie; W.P.Th.M. Mali; Constantinus F. Buckens; Peter C. Jacobs; Diederick E. Grobbee; Y. van der Graaf

We describe the rationale for a new study examining the prognostic value of unrequested findings in diagnostic imaging. The deployment of more advanced imaging modalities in routine care means that such findings are being detected with increasing frequency. However, as the prognostic significance of many types of unrequested findings is unknown, the optimal response to such findings remains uncertain and in many cases an overly defensive approach is adopted, to the detriment of patient-care. Additionally, novel and promising image findings that are newly available on many routine scans cannot be used to improve patient care until their prognostic value is properly determined. The PROVIDI study seeks to address these issues using an innovative multi-center case-cohort study design. PROVIDI is to consist of a series of studies investigating specific, selected disease entities and clusters. Computed Tomography images from the participating hospitals are reviewed for unrequested findings. Subsequently, this data is pooled with outcome data from a central population registry. Study populations consist of patients with endpoints relevant to the (group of) disease(s) under study along with a random control sample from the cohort. This innovative design allows PROVIDI to evaluate selected unrequested image findings for their true prognostic value in a series of manageable studies. By incorporating unrequested image findings and outcomes data relevant to patients, truly meaningful conclusions about the prognostic value of unrequested and emerging image findings can be reached and used to improve patient-care.


Atherosclerosis | 2014

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

Pushpa M. Jairam; Pim A. de Jong; Willem P. Th. M. Mali; Martijn J. A. Gondrie; Peter C. Jacobs; Yolanda van der Graaf

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 individuals 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.


PLOS ONE | 2011

Prediction of Cardiovascular Events by Using Non-Vascular Findings on Routine Chest CT

Pim A. de Jong; Martijn J. A. Gondrie; Constantinus F. Buckens; Peter C. Jacobs; Willem P. Th. M. Mali; Yolanda van der Graaf

Background Routine computed tomography (CT) examinations contain an abundance of findings unrelated to the diagnostic question. Those with prognostic significance may contribute to early detection and treatment of disease, irrelevant findings can be ignored. We aimed to assess the association between unrequested chest CT findings in lungs, mediastinum and pleura and future cardiovascular events. Methods Multi-center case-cohort study in 5 tertiary and 3 secondary care hospitals involving 10410 subjects who underwent routine chest CT for non-cardiovascular reasons. 493 cardiovascular hospitalizations or deaths were recorded during an average follow-up time of 17.8 months. 1191 patients were randomly sampled to serve as a control subcohort. Hazard ratios and annualized event rates were calculated. Results Abnormalities in the lung (26–44%), pleura (14–15%) and mediastinum (20%) were common. Hazard ratios after adjustment for age and sex were for airway wall thickening 2.26 (1.59–3.22), ground glass opacities 2.50 (1.72–3.62), consolidations 1.97 (1.12–3.47), pleural effusions 2.77 (1.81–4.25) and lymph-nodes 2.04 (1.40–2.96). Corresponding annual event rates were 5.5%, 6.0%, 3.8%, 10.2% and 4.4%. Conclusions We have identified several common chest CT findings that are predictive for future risk of cardiovascular events and found that other findings have little utility for this. The added value of the non-vascular predictors to established vascular calcifications on CT remains to be determined.

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Mathias Prokop

Radboud University Nijmegen

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Bram van Ginneken

Radboud University Nijmegen

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Harry J. de Koning

Erasmus University Rotterdam

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