Is a high-resolution computed tomography (CT) scan needed after a positive low-dose computed tomography (CT) lung screening?

From the Guidelines

A high-resolution CT scan is not routinely needed after a positive low-dose CT lung screening. When a low-dose CT scan identifies a suspicious nodule or abnormality, the next steps typically depend on the specific findings rather than automatically proceeding to a high-resolution CT. For nodules of concern, the most common follow-up approaches include:

• repeat low-dose CT scans at specific intervals (typically 3,6, or 12 months) to monitor for changes in size or appearance;
• PET scans to evaluate metabolic activity of concerning nodules;
• or proceeding directly to biopsy or surgical intervention for highly suspicious findings. The management pathway is determined by nodule characteristics (size, appearance, growth rate), patient risk factors, and established guidelines such as Lung-RADS criteria 1. High-resolution CT scans are generally reserved for specific clinical scenarios where detailed imaging of lung parenchyma is needed, such as evaluating interstitial lung disease or precisely characterizing complex abnormalities, rather than being a standard next step in the lung cancer screening pathway. This approach minimizes unnecessary radiation exposure while ensuring appropriate diagnostic follow-up. According to the most recent guidelines, the selection of screen-eligible individuals, the quality of imaging and image interpretation, the management of screen-detected findings, and the effectiveness of smoking cessation interventions can impact the balance of benefits and harms of low-dose CT screening for lung cancer 1.

In terms of specific management after a positive low-dose CT lung screening, the approach may vary based on the size of the nodule and other factors, as outlined in guidelines such as those from the European Respiratory Journal 1. However, the key principle is to tailor the follow-up to the individual's risk factors and the characteristics of the detected nodule, rather than automatically proceeding to a high-resolution CT scan. By doing so, it's possible to balance the need for accurate diagnosis with the potential risks and harms associated with additional testing, including unnecessary radiation exposure and invasive procedures 1.

Ultimately, the decision to proceed with a high-resolution CT scan or other diagnostic tests after a positive low-dose CT lung screening should be made on a case-by-case basis, taking into account the latest evidence and guidelines, as well as the individual patient's circumstances and preferences. The most recent study from 2021 1 supports the idea that low-dose CT screening for lung cancer can result in a favorable balance of benefit and harms, emphasizing the importance of careful management of screen-detected findings.

From the Research

High-Resolution CT Scan After Positive Low-Dose CT Lung Screening

• The need for a high-resolution computed tomography (CT) scan after a positive low-dose CT lung screening is a topic of interest in the medical field.
• A study published in 2013 2 compared image quality and radiation doses between low-dose CT and follow-up standard diagnostic CT for lung cancer screening, and found that low-dose CT can be effectively used as a follow-up standard diagnostic CT in place of standard-dose CT to reduce the radiation dose.
• Another study published in 2025 3 reported the results of a prospective, longitudinal cohort study on low-dose CT for lung cancer screening in a high-risk population, and found that large-scale lung cancer screening is effective and can be delivered efficiently to an ethnically and socioeconomically diverse population.
• A study published in 2022 4 investigated the qualitative and quantitative image quality of low-dose high-resolution lung CT scans acquired with a photon counting CT scanner, and found that low-dose high-resolution photon-counting CT scans of the lung provide better image quality while using significantly less radiation dose compared to conventional CT scans.
• However, the decision to perform a high-resolution CT scan after a positive low-dose CT lung screening should be based on individual patient factors and clinical judgment, as there is no one-size-fits-all approach.

Radiation Dose and Image Quality

• The radiation dose used in low-dose CT scans is significantly lower than that used in standard diagnostic CT scans, with a range of 1.3-3.4 mSv compared to 8.5-14.0 mSv 2.
• The image quality of low-dose CT scans is comparable to that of standard diagnostic CT scans, with no significant differences in image quality and diagnostic accuracy 2, 4.
• The use of photon counting CT scanners can provide better image quality while using significantly less radiation dose compared to conventional CT scanners 4.

Clinical Implications

• The results of these studies suggest that low-dose CT scans can be used as a screening tool for lung cancer, and that high-resolution CT scans may not be necessary for all patients with a positive low-dose CT lung screening result.
• However, the decision to perform a high-resolution CT scan should be based on individual patient factors, such as the presence of suspicious lesions or other clinical findings.
• Further research is needed to determine the optimal approach to lung cancer screening and diagnosis, and to evaluate the effectiveness of different imaging modalities in detecting and characterizing lung cancer 3, 5.