Focused Field of View Calcium Scoring Prior to Coronary CT Angiography
Focused Field of View Calcium Scoring Prior to Coronary CT Angiography
Coronary computed tomography angiography (CCTA) is a frequently performed test for the
 diagnosis and/or exclusion of coronary artery disease (CAD) in appropriately selected
 patients. The performance of non-contrast computed tomography for the detection and
 quantification of coronary calcification is typically performed prior to CCTA in an effort to
 identify significant calcification which may influence subsequent data acquisition during the
 CCTA. However, performance of calcium scoring adds significant radiation and most coronary
 calcification is proximal in its location, potentially visualized using a focused
 non-contrast scan.

 The purpose of this study is to prospectively compare the usefulness of a modified
 non-contrast CT, using a significantly shorter scan length and lower radiation parameters, as
 compared to standard coronary artery calcium scanning for the detection of coronary
 calcification that may influence subsequent CCTA performance.
Prior to undergoing CCTA, non-contrast CT scanning of the entire heart is usually performed
 in adults over 50-years of age in order to assess for the presence and severity of coronary
 artery calcium. By providing a modified CT scan with a reduced length the same data can be
 obtained by the imager to ensure a high quality scan while decreasing the patient's overall
 radiation exposure. Our objectives and specific aims to validate our hypothesis include:

 -  To assess the impact on CCTA image quality using modified calcium score approach

 -  To determine the rate of changes in the coronary CT angiography acquisition parameters
 after evaluation of the modified versus standard calcium scoring scout series.
 Significant changes in CCTA acquisition include any of the following as compared to
 recommended CCTA parameters prior to scout CT performance: a change (increase or
 decrease) in tube current (mA) by 50, any change in tube potential (kV), change to/from
 retrospectively-gated CCTA, any change in padding (acquisition window), or changing
 to/from a high definition CT scan acquisition.

 -  To assess the difference in patient estimated effective radiation exposure (mSv) between
 the modified versus standard calcium scoring techniques.

 -  To assess the difference in patient estimated effective radiation exposure (mSv) of the
 entire CCTA study (plus calcium scoring) between groups.

 Study Design Prospective, randomized single-center cohort study.

 Anticipated Requirements

 1. Facilities: Walter Reed National Military Medical Center

 1. Cardiology Clinic

 2. Cardiovascular Health and Interventional Radiology, Angiography and Recovery
 [CVHIR]

 3. Radiology Department (CT Section)

 2. Duration of enrollment: 12 months

 3. Budget: no additional budget is needed.

 Subject Population

 1. One hundred seventy-five (175) male and female adult subjects (military health
 beneficiaries age greater than 50 years) who are clinically referred for CCTA will be
 eligible for participation.

 2. The Walter Reed National Military Medical Center Cardiology Department and Radiology
 Departments perform multiple clinically appropriate and indicated coronary CTA studies
 weekly (approximately 8-12), which will allow for ease of subject recruitment. Although
 there are other open studies using CCTA in our department there is not a lot of overlap
 in their requirements and should not prohibit enrollment in our study. This study will
 enroll both men and women of all ethnic origins aged ≥ 50 years. All subjects will
 consent for themselves. All patients' participation in this research and subsequent
 contribution to our medical knowledge notwithstanding, no intent to benefit patients
 from enrollment is implied or offered. Pregnant women will be excluded from enrollment
 based on:

 1. Verbal admission of pregnant status; OR

 2. Positive urine pregnancy test performed within 7 days of CCTA in subjects not
 previously known to be pregnant.
Inclusion Criteria:

 1. Consenting adult patients ≥ 50 years of age;

 2. Suspected but without known prior history of CAD. Prior CAD is defined as a history of
 myocardial infarction, coronary revascularization or ≥ 50% coronary lumen stenosis on
 prior coronary angiography

 3. Scheduled for non-emergent clinically indicated coronary CT angiography

 Exclusion Criteria:

 1. Prior coronary bypass graft (CABG) surgery

 2. Suspicion of acute coronary syndrome (MI or unstable angina)

 3. Known complex congenital heart disease

 4. Evidence of ongoing or active clinical instability, including chest pain (sudden
 onset); cardiogenic shock; unstable blood pressure with systolic blood pressure < 90
 mmHg; and severe congestive heart failure (NYHA class III or IV); or acute pulmonary
 embolism

 5. Atrial fibrillation

 6. Abnormal renal function (GFR < 60 ml/min; Creatinine > 1.5 mg/dL)

 7. Concomitant participation in another clinical trial in which patient is subject to
 investigation drug or device

 8. Pregnancy or unknown pregnancy status

 9. Allergy to iodinated contrast agent

 10. Contraindications to nitroglycerin

 11. Unwilling or unable to give consent

 12. Inability to comply with study procedures

 13. Prior coronary artery calcium score and/or coronary CT angiogram