Lung-RADS® calculator for pulmonary nodules on CT (volume-based)

Note to first time users: This calculator can be used to calculate the Lung-RADS score of pulmonary nodules based on their volume. This should be ideally done with volumetry, however an approximate volume can be calculated with this spherical formula here. Bear in mind that for non-spherical nodules this can introduce inaccuracy, thus if only caliper measurements are available the diameter-based Lung-RADS calculator is recommended instead.

This calculator is based upon the American College of Radiology (ACR) Lung-RADS^® reporting and data system, however it is neither supported, nor endorsed by the aforementioned organization.

Notes

The Lung-RADS^® system

• Assessment categories are excellently summarized by this table released by the ACR. First time users should familiarize themselves with the categories and criteria.
• A succinct summary of the Lung-RADS system can also be found in this Radiopaedia.org article.

Practical points

• The Lung-RADS 0 (incomplete) category should be used if either relevant prior imaging is unavailable or a part of the lungs cannot be evaluated on the exam, and therefore further imaging is required.
• A screen is:
  • negative: Lung-RADS 1-2
  • positive: Lung-RADS 3-4
• The S modifier indicates clinically significant or potentially significant non lung cancer findings, and can be added to any category from 0-4.
• Growth is defined as an increase in size of > 2 mm³.
• Nodules should be measured using lung window.
• For new large nodules that develop on an annual screening LDCT, a 1 month follow-up CT may be recommended to rule out potentially infectious or inflammatory conditions. (version 1.1 addition).
• The Lung-RADS system is designed for screening. Once a patient has been diagnosed with lung cancer, further management (including additional imaging e.g. PET/CT) may be performed for lung cancer staging, which is no longer screening.
• A comparison of Lung-RADS 1.1 to the 1.0 version showed that the new reporting system has reduced the number of false positives due to the downclassification of subcentimeter typical perifissural nodules.
  • ^{Kastner J, Hossain R, Jeudy J, Dako F, Mehta V, Dalal S, Dharaiya E, White C. Lung-RADS Version 1.0 versus Lung-RADS Version 1.1: Comparison of Categories Using Nodules from the National Lung Screening Trial. Radiology. 2021 Jul;300(1):199-206. doi: 10.1148/radiol.2021203704. Epub 2021 May 4. PMID: 33944631.}

Last updated: 2021-10-07