Pulmonary Nodules

by Hetal Verma, MD

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    00:01 So in this lecture, we'll be discussing pulmonary nodules.

    00:03 We'll go over how you can determine whether a nodule is benign or malignant and we'll go over some of the follow-up that may be indicated if you do see a nodule.

    00:11 So, let's start off with this case.

    00:14 Let's take a look at the findings and keep this in mind as we go through the lecture.

    00:19 The finding is actually located in the left upper lung right here, we'll go back to this case at the very end.

    00:27 So the key question when you see a pulmonary nodule is, is it benign or is it malignant? Because obviously, there's a very different follow-up indicated depending on whether it's benign or malignant.

    00:38 So, in general, benign nodules tend to have very smooth margins while malignant nodules tend to be a little bit more spiculated.

    00:47 Benign nodules are usually smaller, they're usually about less than four millimeters in size while malignant nodules are usually much bigger, greater than about five centimeters in size.

    00:57 Benign nodules tend to have calcifications, malignant nodules tend to increase in size a lot more than benign nodules would. And an example of a benign nodule is usually a granuloma or a hamartoma, those are the two most common that are seen within the lung.

    01:11 In terms of malignancy, you can have bronchogenic carcinoma or metastasis.

    01:16 So when would you call it a nodule versus when would you call it a mass? Nodules are generally less than about three centimeters in size, masses are greater than or equal to about three centimeters in size so that's really the size criteria that you use when you're describing a nodule or a mass within the lung.

    01:32 So, what kind of work-up does the nodule need? If it's less than about a centimeter, a radiograph is really not reliable in terms of visualizing it so you have to go further and usually the next step would be a CT scan.

    01:46 Most nodules are actually found incidentally on a radiograph and if you do see an incidental nodule, you also want to recommend a CT scan to make sure that there aren't other nodules that you may be missing.

    01:56 So the CT scan is the first step for a full evaluation of the lungs.

    02:01 Follow-up is actually based on Fleishcner Society criteria, this is a group of international chest radiologists that have come up with a general criteria for follow-up of pulmonary nodules and we'll go over that.

    02:12 So, this is the chart that they use. Let’s start with solid Nodules. The left side refers to single nodules. If the nodule is less than 6 millimeters in size, in a low-risk patient no routine follow-up is needed. In a high-risk patient, you could consider an optional CT scan in about a year. If it’s anywhere between 6 and 8 millimeters in size, then for a low-risk patient, you would wanna perform a CT at 6 to 12 months and then consider another CT at 18 to 24 months.

    02:50 In a high-risk patient, you follow the same procedure but definitely repeat the scan at 18 to 24 months to ensure nodule stability.

    03:00 If a nodule is larger than 8 millimeters, consider a CT at 3 months, a PET-CT or tissue sampling in both low and high-risk patients.

    03:11 However, it’s important to consider that certain high-risk patients with suspicious nodule morphology, upper lobe location, or both may warrant a 12-month follow-up.

    03:22 Now let’s look at the chart for multiple solid nodules.

    03:25 You should use the most suspicious nodule as a guide for management.

    03:30 For nodules under 6 millimeters, the procedure is the same for single and multiple nodules, we already discussed that.

    03:37 But for multiple nodules between 6 and 8 millimeters in size, a CT scan should already be performed at 3 to 6 months and repeated after 18 to 24 months. The repeat is, again, optional for low-risk patients and recommended for high-risk patients.

    03:56 The same goes for nodules over 8 millimeters.

    04:01 Another type of nodule is a subsolid nodule.

    04:04 Again, let’s focus on single nodules first. These can be either ground glass or partly solid.

    04:11 For a nodule under 6 millimeters in size, no routine follow-up is required for either ground glass or partly solid nodules.

    04:20 However, for certain suspicious nodules, you should consider a follow-up at 2 and 4 years.

    04:27 If the solid component develops or grows, consider a resection.

    04:31 A ground glass nodule equal to or larger than 6 millimeters should be considered highly suspicious.

    04:38 You would want to perform a CT at 6 to 12 months to confirm persistence, then repeat the scan every 2 years up to 5 years.

    04:47 A partly solid nodule already requires a CT at 3 to 6 months.

    04:53 If the lesion remains unchanged, and the solid component stays under 6 millimeters, perform an annual CT for 5 years.

    05:01 In practice, partly solid nodules can’t be defined as such until they are about 6 millimeters.

    05:07 Multiple subsolid nodules under 6 millimeters require a CT at 3 to 6 months and are usually benign.

    05:14 If the lesion is stable, consider a CT at 2 and 4 years.

    05:19 Consider a follow-up for high-risk patients.

    05:22 If they are equal to or larger than 6 millimeters in size, you should also do a CT at 3 to 6 months.

    05:31 The subsequent management is, once again, based on the most suspicious nodule.

    05:37 A screening for lung cancer can be done in patients who are current or former smokers and at high risk for lung cancer.

    05:44 A low-dose chest CT is performed annually, and follow-up is determined by the Lung Imaging and Reporting Data System, called Lung-RADS, and not the Fleischner Society guidelines.

    05:57 So, you can keep this table with you.

    05:59 This is a great way to kind of take a look at the table whenever you do have a nodule that you see on a chest CT.

    06:07 So, what exactly is a PET CT? It stands for Positron Emission Tomography and it's a CT scan, so it's a combination of two different studies.

    06:17 It's a type of nuclear medicine examination which uses a radiotracer usually called FDG or fludeoxyglucose which concentrates in areas of high glucose uptake.

    06:28 It's paired with a CT scan to help delineate the anatomy and it allows for detection of malignancy and metastatic disease.

    06:35 The lesion threshold though is about seven millimeters.

    06:39 So if a lesion is smaller than seven millimeters, it's very unlikely to be seen on the PET.

    06:44 For lesions that are greater than seven millimeters, a PET CT is a great alternative to taking a look at whether the lesion is malignant or benign.

    About the Lecture

    The lecture Pulmonary Nodules by Hetal Verma, MD is from the course Thoracic Radiology. It contains the following chapters:

    • Pulmonary Nodules
    • PET CT

    Included Quiz Questions

    1. Chest CT today for complete initial evaluation of nodule
    2. CT chest in 6 months
    3. PET scan
    4. MRI
    5. Biopsy
    1. Spiculation
    2. Calcification
    3. Granuloma formation
    4. Size < 4 mm
    5. Smooth margins
    1. PET/CT scan and/or biopsy
    2. Repeat chest CT in 3 months
    3. CT pulmonary angiogram
    4. MRI of the chest
    5. Ultrasound

    Author of lecture Pulmonary Nodules

     Hetal Verma, MD

    Hetal Verma, MD

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