When to Order Imaging for Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery: ACR Appropriateness Decoded

When to Order Imaging for Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery: ACR Appropriateness Decoded

A patient is scheduled for cardiothoracic surgery, and you are tasked with ordering the appropriate preoperative imaging. The patient’s history is complex, perhaps involving a prior sternotomy, which complicates the surgical approach. Do you need a non-contrast chest CT to map out adhesions, or is a CTA required to assess graft patency and the great vessels? Is a simple chest radiograph sufficient? Choosing the right study is critical for surgical planning, minimizing operative time, and preventing complications. This guide breaks down the American College of Radiology (ACR) Appropriateness Criteria for preprocedural imaging in cardiothoracic surgery, providing clear, evidence-based recommendations to guide your decision-making.

What Does ACR Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery Cover?

This ACR guideline focuses on selecting the most appropriate imaging for adult patients in preparation for planned cardiothoracic surgery. The recommendations are stratified based on the type of surgery and the patient’s surgical history. The primary clinical scenarios covered include:

• Preprocedural planning for coronary cardiac surgery (e.g., Coronary Artery Bypass Grafting or CABG).
• Preprocedural planning for noncoronary cardiac surgery (e.g., valve replacement, aortic repair).
• Preprocedural planning for general thoracic surgery (e.g., lung resection, mediastinal mass excision).

Each category is further divided into patients with no history of cardiothoracic surgery and those who have had prior procedures. This distinction is crucial, as a history of surgery significantly alters the anatomy and surgical risks, often elevating the utility of cross-sectional imaging like CT. These criteria do not apply to emergent situations, postoperative evaluations, or initial diagnosis of thoracic conditions.

What Imaging Should I Order for Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery? Recommendations by Clinical Scenario

The optimal imaging strategy depends heavily on the specific surgical context and patient history. The ACR provides detailed guidance for several common variants.

For an adult undergoing preprocedural planning for coronary cardiac surgery with no prior surgical history, several modalities are rated Usually appropriate. These include transesophageal echocardiography (TEE), transthoracic echocardiography (TTE), chest radiography, and coronary arteriography. These studies provide essential information on cardiac function, valve status, lung parenchyma, and coronary anatomy. In this context, advanced imaging like cardiac MRI or chest CTA is considered May be appropriate, reserved for cases where specific anatomical questions remain unanswered by first-line tests.

The recommendations change significantly for an adult with a history of cardiothoracic surgery who is now being planned for coronary cardiac surgery. While echocardiography, chest radiography, and coronary arteriography remain Usually appropriate, CT and CTA of the chest (with or without contrast) are also elevated to Usually appropriate. This is because CT is invaluable for delineating the relationship of the sternum to underlying structures like the heart, aorta, and bypass grafts, which is critical for planning a safe re-entry.

The guidelines for noncoronary cardiac surgery largely mirror those for coronary surgery. In a patient with no prior surgical history, TEE, TTE, chest radiography, and coronary arteriography are Usually appropriate. For a patient with a prior history of cardiothoracic surgery, chest CT (with or without contrast) again becomes Usually appropriate to assess post-surgical anatomy and guide the operative approach.

For an adult undergoing planning for general thoracic surgery with no prior surgical history, the focus shifts away from cardiac-specific imaging. Chest radiography and chest CT (with or without contrast) are Usually appropriate to evaluate the lungs, pleura, and mediastinum. Coronary arteriography, in contrast, is rated Usually not appropriate unless there is a specific cardiac indication. If that same patient has a history of cardiothoracic surgery, the recommendations remain similar, with chest radiography and CT being the primary Usually appropriate modalities for surgical planning.

ACR Imaging Recommendations Table

Adult vs. Pediatric Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery Imaging: Radiation Dose Tradeoffs

While this ACR guideline focuses on adult scenarios, the principles of radiation safety are universal and particularly critical in younger patients. The provided Relative Radiation Levels (RRLs) highlight differences in estimated dose, such as a chest CT delivering 1-10 mSv in adults but a slightly different range of 3-10 mSv in pediatric protocols. This reflects the ongoing effort to optimize pediatric imaging protocols to minimize radiation exposure while maintaining diagnostic quality.

Pediatric patients have a longer life expectancy, affording more time for the potential stochastic effects of radiation to manifest, and their developing tissues are more radiosensitive. Therefore, adherence to the ALARA (As Low As Reasonably Achievable) principle is paramount. This involves choosing non-ionizing modalities like ultrasound (echocardiography) or MRI when clinically appropriate and carefully tailoring CT parameters (e.g., kVp, mAs) for pediatric patients when CT is necessary. The different RRLs underscore the importance of using dedicated pediatric protocols rather than simply applying adult settings to smaller patients.

Imaging Protocol Details for Preprocedural Chest or Cardiac Imaging for Cardiothoracic Surgery

Once you’ve decided on the right study, the specific imaging protocol is essential for acquiring high-quality, actionable images. Details such as contrast timing, slice thickness, and ECG gating can make the difference between a diagnostic and a non-diagnostic scan. Our protocol guides cover technique, contrast considerations, and interpretation principles for the studies recommended above.

• CT Chest/Abdomen/Pelvis with IV Contrast

Tools to Help You Order the Right Study

Navigating imaging guidelines can be complex. GigHz offers a suite of tools designed to support evidence-based clinical decision-making at the point of care.

For clinical scenarios beyond preprocedural cardiothoracic imaging, the ACR Appropriateness Criteria Lookup provides a searchable interface to the full library of ACR guidelines, helping you find the right test for hundreds of clinical presentations.

To ensure studies are performed correctly, the Imaging Protocol Library offers detailed, step-by-step protocols for a wide range of CT, MRI, and ultrasound examinations, standardizing best practices across institutions.

When discussing the risks and benefits of imaging with patients, especially concerning radiation, the Radiation Dose Calculator is a valuable resource. It helps estimate cumulative radiation exposure from various imaging studies, facilitating informed patient consent and communication.

Why is a chest CT “Usually appropriate” for patients with a history of cardiothoracic surgery but only “May be appropriate” for those without?

In a patient with a prior cardiothoracic surgery (e.g., a sternotomy), the normal anatomy is altered. Adhesions can form, tethering the heart, aorta, or prior bypass grafts to the posterior surface of the sternum. A preoperative CT provides a crucial surgical roadmap, showing the surgeon exactly where these vital structures are in relation to the sternum. This knowledge helps prevent catastrophic injury during sternal re-entry. In a patient without prior surgery, this specific risk is absent, so a CT is not routinely necessary and is reserved for answering specific clinical questions.

What is the primary role of echocardiography in preprocedural planning for cardiac surgery?

Echocardiography (both transthoracic and transesophageal) is fundamental for assessing cardiac structure and function. It provides critical information on left and right ventricular systolic function, evaluates valvular morphology and function (stenosis or regurgitation), measures chamber sizes, and estimates pulmonary artery pressures. This information is essential for risk stratification and planning the specifics of the cardiac procedure, such as whether a valve repair or replacement is needed in addition to bypass grafting.

When is coronary arteriography indicated before noncoronary cardiac surgery?

Coronary arteriography is rated as Usually appropriate before noncoronary cardiac surgery (e.g., valve surgery) to assess for concurrent coronary artery disease (CAD). Identifying and treating significant CAD with bypass grafting at the time of the primary surgery can improve long-term outcomes. The decision to perform arteriography is typically based on the patient’s age, risk factors for CAD, and any symptoms of angina. Guidelines from cardiology societies often recommend coronary angiography for most adult patients undergoing cardiac valve surgery.

Is there a role for MRI or MRA in preprocedural planning for cardiothoracic surgery?

Yes, though it is often a second-line or problem-solving tool. According to the ACR criteria, cardiac MRI and MRA are rated as May be appropriate in many scenarios. Cardiac MRI is excellent for assessing myocardial viability, quantifying ventricular function and volumes with high accuracy, and characterizing cardiac masses. MRA can provide detailed, non-invasive imaging of the aorta and other great vessels without ionizing radiation. These modalities are typically used when echocardiography or CT results are equivocal or when specific information about tissue characterization or complex vascular anatomy is required.

Why is a simple chest radiograph still considered “Usually appropriate” for most pre-cardiothoracic surgery patients?

A chest radiograph is a low-cost, low-radiation, and widely available imaging test that provides valuable baseline information. It can reveal signs of heart failure (e.g., cardiomegaly, pulmonary edema), identify significant lung pathology (e.g., nodules, effusions, pneumonia) that might affect surgical planning or postoperative recovery, and show the position of the aorta and mediastinal contours. It also serves as a crucial baseline for comparison with postoperative films to assess for complications like pneumothorax or atelectasis.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 12, 2026