CONTENTS:

2.4 Lung Imaging Reporting and Data System (Lung RADS)
2.4.1 Lung RADS Diagnostic Categories
2.4.2 LU-RADS (Canada)
2.4.3 Quality Control: the Lung Cancer Screening Registry

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2.4 Lung Imaging Reporting and Data System (Lung RADS)

The ACR Lung Cancer Screening Committee subgroup on Lung RADS has produced the Lung Imaging Reporting and Data System (Lung-RADS) as a quality assurance (QA) guide. The way that Lung-RADS ensures CT reporting ‘quality’ is by standardizing CT image reporting in lung screening and standardizing patient clinical management recommendations.  The result of these standardized and widely used guidelines is to reduce ambiguity in lung cancer screening CT interpretation; they also facilitate patient outcome monitoring.

Lung-RADS was released by the Radiological Society of North America (RSNA) in April 2014. It is to be used in compiling data for patients in line with lung screening diagnoses and mandated clinical registries.

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Figure 2.2 Version 1.0 of Lung RADS:

Assessment categories and management recommendations.
(From the ACR, 2014).

The American College of Radiology (ACR) have modelled Lung RADS after the well-accepted BI-RADS scoring used in diagnosing breast tissue density for mammography screening.

A complete lexicon and atlas are awaited for Lung RADS.  In 2014, McKee and colleagues published their report to the ACR on the results of implementation of LungRADS in a screening population.

In their study, McKee and colleagues examined a total of 2,180 ‘high-risk‘ individuals who underwent CT lung screening. They found that the ACR Lung-RADS reduced the overall ‘positive‘ rate from 27.6% to 10.6%. They found that there were no ‘false-negative‘ diagnoses in a 12-month follow-up period.

Applying ACR Lung RADS guidelines increased the ‘positive predictive value‘ for diagnosed malignancy in 1,603 patients with follow-up from 6.9 % to 17.3 %. These results are promising, particularly in view of the improved positive predictive value of Lung-RADS but without an increase in the number of examinations resulting in ‘false-negative’ results.

So if I had a LungRADS score of 3, I would have lung nodules with a low chance of developing  lung cancer?

That’s right, the LungRADS means radiologists assign a category which has important follow-up implicatons.

So I would then have to have a CT screening scan every 6 months to keep an eye on the nodules.

2.4.1 Lung RADS Categories

Category 0: Incomplete

CT imaging studies cannot be evaluated due to technical problems or missing information. Patients are advised to have additional lung cancer screening CT images and / or comparisons to prior chest CT examinations if needed.

Category 1: Negative

Findings of no lung nodules and / or definitely benign nodules. Patients should continue to have annual screening with low-dose CT.

Category 2: Benign appearance or behavior

Lung nodules with a very low chance of developing into clinically active cancer due to size or lack of growth. Patients are advised to continue to have annual screening with LDCT.

Category 3: Probably benign

Probably benign LDCT findings, but a short-term follow-up is advised. This category includes lung nodules with a low chance of being cancer. Patients should be screened every six months with LDCT.

Are lung nodules something to worry about?

Nodules are quite common. The most recent estimate is that around 20% of people screened have at least one nodule and quite a few of those will turn out to be benign.

But what does that mean?

A ‘nodule’ is used to describe an abnormality less than 3cms in size.

Category 4A and 4B: Suspicious –

These imaging findings require additional diagnostic testing and / or a tissue diagnosis.

In 4A, patients are advised to have Low Dose CT scanning  (LDCT)  at three months; PET / CT may be used when there is an 8-mm or larger solid component to an imaged lung lesion.

In 4B, patients are advised to undergo chest X-ray, PET / CT, and / or tissue diagnosis, depending on the probability of cancer and co-morbidities. PET / CT may be used when there is an 8-mm or larger solid component to the lung lesion.

The categories also come with the following ‘modifiers:’

An ‘S’ modifier: This suggests the screening examinations discover ‘clinically significant or potentially clinically significant finding that are non-lung-cancer,’ such as emphysema.

A ‘C’ modifier: This refers to patients with prior diagnoses of lung cancer who return for screening.

Because the National Lung Screening Trial (NLST) showed a ‘false-positive’ diagnosis of 1 in 4 with LDCT, it is hoped that the use of LungRADS can reduce this to 1 in 10 or less. To reduce the false-positive rate, LungRADS also describes lung nodule size, lung nodule consistency, benign appearance and benign behavior.

It is important to keep individuals who smoke informed that although LungRADS offers a guide to the likelihood of lung cancer, the ACR guidelines still emphasize that best way to reduce lung cancer is to stop smoking.

The Lung RADS guidelines also indicate that for a screening center to achieve accreditation, the screening program should have processes in place to refer patients for counseling to give up smoking or to provide smoking cessation materials.

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What does that mean?

When certain chemicals in the brain are altered, mood and concentration levels change, many smokers find this enjoyable.

It has been suggested that over 70% of smokers want to quit. If you’re one of these, go to your family doctor and join a stop smoking support service. It’s really hard but you CAN do it.

2.4.2 LU-RADS

In 2014, a Canadian study by Manos and colleagues, led to the proposal for a 6-level Lung-Reporting and Data System (LU-RADS). This system has classified lung screening CT scan reports according to the lung nodule with the ‘highest malignancy risk.’

These authors report that as the LU-RADS level increases the risk of malignancy increases. The LU-RADS level is linked directly to patient clinical follow-up pathways.

Why is it important to classify CT reports in screening?

A standardized reporting and management model reduces confusion in lung cancer screening CT interpretations and facilitates treatment and outcome monitoring

The LU-RADS categories are:

Category 1: CT’s with no nodules and returns the subject to routine screening.

Category 2: CT scans with minimal risk lung lesions, including < 5 mm, peri-fissural, or long-term stable nodules that require no further work-up before the next routine screening CT.

Category 3: CT scans containing indeterminate nodules and requiring CT follow-up with the interval dependent on lung nodule size (small [5-9 mm] or large [≥ 10 mm] and possibly transient).

Category 4: CT scans that are ‘suspicious for malignancy‘ and are sub-divided into:

4A – low risk of malignancy;

4B – likely low-grade adenocarcinoma and

4C – likely to be malignant.

The 4B and 4C lung nodules have a high likelihood of being tumors, based on the screening CT features, even if PET,  FNA, and / or bronchoscopy are negative.

Category 5: CT scan shows lung nodules demonstrating malignant behavior.

Category 6: CT scans show tissue-proven malignancy.

One of the aims of the Lu-Rads reporting system is to introduce an evidence-based classification for lung nodules found on CT scan.

What exactly is a lung nodule?

A lung nodule is a small round (or oval) growth in the lung. It is sometimes called a ‘spot’ on the lung or a ‘coin lesion’.

2.4.3 Quality Control: the Lung Cancer Screening Registry

The ACR Guidelines of 2014 which contain the Lung-RADS categories, also contain recommendations for ensuring quality control (QC) in lung CT reporting. The ACR is in the process of developing a Lung Cancer Screening Registry to support clinical practice audits. The registry structure will be similar to that for Bi-RADS and will include the identity of reporting radiologists.

The ACR intends to apply to the Centers for Medicare and Medicaid Services (CMS) for approval of its registry that may then be used by providers billing Medicare for lung cancer screening examinations.

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References:

McKee BJ, Regis SM, McKee AB et al. (2014). Performance of ACR Lung-RADS in a Clinical CT Lung Screening Program. JACR S1546-1440(14)00473-6. (Retrieved 29th Jan 2015): http://www.jacr.org/article/S1546-1440(14)00473-6/pdf

Manos D, Seely JM, Taylor J et al. (2014). The Lung Reporting and Data System (LU-RADS): a proposal for computed tomography screening. Can Assoc Radiol J 65(2), 121-34. (Retrieved 30^th Jan 2015): http://www.ncbi.nlm.nih.gov/pubmed/24758919

More references for this section are on this page.

Patient Information:

National Lung Screening Trial (NLST). Study Facts from the NCI. (Retrieved 22^nd Jan 2015): http://www.cancer.gov/clinicaltrials/noteworthy-trials/nlst

American College of Radiology (ACR) (2014). Lung CT Screening Reporting and Data System (Lung-RADS). (Retrieved 29th Jan 2015): https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/Lung-Rads

More patient information for this section is on this page.

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