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 the surgical team needs a clear roadmap of the anatomy before they proceed. Whether it’s a primary coronary artery bypass graft (CABG), a complex valve replacement in a patient with a prior sternotomy, or a thoracic tumor resection, the choice of preoperative imaging is critical. Ordering the right study provides essential information on cardiac function, great vessel anatomy, and the relationship of key structures, while ordering an unnecessary one can lead to delays, increased costs, and needless radiation exposure. This guide clarifies the American College of Radiology (ACR) Appropriateness Criteria to help you select the most effective imaging for your patient’s specific surgical context.

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

This ACR topic provides evidence-based recommendations for imaging performed for the purpose of preprocedural planning in adults undergoing cardiothoracic surgery. The guidelines are stratified based on the type of surgery and the patient’s surgical history, which are key determinants of imaging appropriateness. The scenarios covered include:

• Coronary Cardiac Surgery: Imaging before procedures like CABG.
• Noncoronary Cardiac Surgery: Imaging for valve repair/replacement, aortic surgery, or congenital defect repair.
• Thoracic Surgery: Imaging for non-cardiac procedures such as lung resection or mediastinal mass removal.

Each category is further divided into patients with no prior cardiothoracic surgery and those with a history of cardiothoracic surgery (e.g., redo-sternotomy), as the latter often requires more detailed anatomical assessment. These criteria are intended for non-emergent, planned procedures and do not address imaging for acute chest pain, trauma, or evaluation of postoperative complications.

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 planned procedure and whether the patient has had previous surgery in the chest.

For an adult undergoing coronary cardiac surgery with no history of cardiothoracic surgery, several studies are Usually Appropriate. These include a baseline Radiography chest, resting transthoracic or transesophageal echocardiography (TTE/TEE) to assess cardiac function and valve integrity, and Arteriography coronary to define the coronary anatomy for grafting. In this context, advanced imaging like CT or MRI is often reserved for specific clinical questions and is rated as May be appropriate.

The recommendations change significantly for a patient with a history of cardiothoracic surgery undergoing either coronary or noncoronary cardiac surgery. In these “redo” scenarios, a CT chest with or without IV contrast becomes Usually Appropriate. This is critical for surgical planning to evaluate the proximity of the heart and bypass grafts to the sternum, identify adhesions, and map vascular anatomy to minimize the risk of catastrophic injury upon re-entry. Chest radiography and echocardiography remain Usually Appropriate as well.

When planning for noncoronary cardiac surgery (e.g., valve surgery) in a patient with no prior operations, the recommendations mirror those for primary coronary surgery. Radiography chest, US echocardiography (transthoracic or transesophageal), and Arteriography coronary (to rule out concurrent coronary disease) are all Usually Appropriate.

For thoracic (non-cardiac) surgery, the focus shifts from cardiac to general thoracic anatomy. In a patient with no history of cardiothoracic surgery, a Radiography chest and a CT chest with or without IV contrast are Usually Appropriate to delineate the primary pathology (e.g., lung nodule, mass) and its relationship to adjacent structures. Cardiac-focused studies like coronary angiography are Usually not appropriate unless there is a specific cardiac concern. For patients with a prior history of cardiothoracic surgery undergoing a thoracic procedure, CT chest remains Usually Appropriate to assess for postoperative changes and adhesions that may complicate the planned surgery.

ACR Imaging Recommendations Table

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

While this ACR document focuses on adult scenarios, the provided Relative Radiation Levels (RRL) include pediatric estimates, highlighting the importance of radiation safety in younger patients. Children are more sensitive to the long-term effects of ionizing radiation than adults due to their longer life expectancy and the higher rate of cell division in their developing tissues. Consequently, the ALARA (As Low As Reasonably Achievable) principle is paramount. For studies like a CT chest, the pediatric RRL is often in a higher tier (e.g., ☢ ☢ ☢ ☢) even if the absolute dose in millisieverts (mSv) is lower than the adult dose. This reflects the greater relative biological risk. When ionizing radiation is necessary, protocols should be optimized for pediatric patients to minimize dose without compromising diagnostic quality. Non-radiation modalities like ultrasound (echocardiography) and MRI are particularly valuable in the pediatric population and should be prioritized when clinically appropriate.

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 crucial for obtaining the necessary diagnostic information. A well-designed protocol ensures that the surgical team gets the answers they need regarding anatomy, function, and potential operative hazards. Our protocol guides cover technique, contrast administration, and interpretation principles for many of the studies recommended in these guidelines.

• 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 reference tools designed to help clinicians make evidence-based decisions quickly and efficiently at the point of care.

For clinical scenarios beyond preprocedural cardiothoracic imaging, the ACR Appropriateness Criteria Lookup provides a comprehensive, searchable interface to the full ACR guidelines, covering thousands of clinical variants across all organ systems.

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, helping to standardize care and improve diagnostic quality.

To help manage and communicate radiation exposure with patients, the Radiation Dose Calculator allows you to estimate effective dose for various studies and track cumulative exposure over time, facilitating informed discussions about the risks and benefits of imaging.

Why is a CT scan ‘Usually Appropriate’ for patients with a history of cardiothoracic surgery but not for those without?

In a patient with a prior sternotomy, scar tissue (adhesions) can form, causing the heart, aorta, or bypass grafts to stick to the back of the sternum. A preoperative CT scan is crucial to map this anatomy. It shows the surgeon the exact distance between the sternum and these vital structures, significantly reducing the risk of life-threatening injury during sternal re-entry. In a patient without prior surgery, this risk is absent, so a CT is not routinely required and is only considered ‘May be appropriate’ if specific anatomical questions arise.

Is a chest X-ray always necessary before cardiothoracic surgery?

According to the ACR criteria, a chest radiograph is rated as ‘Usually Appropriate’ for all listed pre-cardiothoracic surgery scenarios. It provides a valuable baseline assessment of the heart size, pulmonary vasculature, lungs, and pleura. It can reveal unexpected findings like a lung mass, pneumonia, or large pleural effusion that might need to be addressed before or during the planned surgery.

When should I consider cardiac MRI or MRA before surgery?

Cardiac MRI and MRA are rated as ‘May be appropriate’ in most pre-coronary surgery scenarios. They are not typically first-line tools but become valuable for answering specific questions that are not well-addressed by echocardiography or CT. For example, cardiac MRI is excellent for assessing myocardial viability, quantifying ventricular function and volumes with high precision, and characterizing cardiac masses. MRA can be used to evaluate complex aortic or great vessel anatomy, especially in patients with contraindications to iodinated contrast.

What is the role of coronary angiography if CTA is an option?

Invasive coronary angiography remains the gold standard (‘Usually Appropriate’) for defining coronary artery anatomy before coronary artery bypass surgery. It provides high-resolution images of the coronary lumen, allowing for precise grading of stenosis and planning of bypass targets. While Coronary CT Angiography (CTA) is also rated as ‘May be appropriate’, its primary role is often in the diagnostic workup of coronary artery disease. For definitive preoperative planning, especially when intervention is certain, most surgeons still rely on the detailed anatomical and physiological data from invasive angiography.

Does every patient undergoing non-cardiac thoracic surgery need a preoperative echocardiogram?

Not necessarily. For pre-thoracic surgery, echocardiography is rated as ‘May be appropriate’. Its use depends on the patient’s overall clinical status, risk factors for heart disease, and the nature of the planned surgery. An echocardiogram is often ordered if there are clinical signs or symptoms of heart failure, a significant heart murmur, or known cardiac disease to assess ventricular function and valvular integrity, as these factors can impact perioperative risk and management.

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