Brief Answer:
If you are in low risk group and nodules are solid then no follow up reqd

Detailed Answer:
Hi XXXX,
Thanks for writing in to us.

I have read through your query in detail.
There are 3 stable lung nodules with largest one measuring 6 mm, persisting on 6 months scan.

My answers are as follows

1. One nodule was 1 mm difference on one side example 4x5mm to 5x5mm, but on inquiring with several people that would just seem to be down to a very slight variation in image or the radiologists interpretation -is this correct?

It is correct that a 1 mm difference in measurement of lung nodule as above might occur due to slight variations in appearance or the radiologists interpretation. In your case, the 1 mm difference does not seem to be significant.

2. Would you still advise another CT scan in 12 months as per the Fleischner Society Recommendations or not?

The Fleischner society recommends the following,
(i) In a person with low risk (Minimal or absent history of smoking and of other known risk factors): Follow-up CT at 12 mo; if unchanged, no further follow-up

(ii) In a person with high risk (History of smoking or of other known risk factors): Initial follow-up CT at 6–12 mo then at 18–24 mo if no change

Further it is mentioned that nonsolid (ground-glass) or partly solid nodules may require longer follow-up to exclude indolent adenocarcinoma.

From the above if I suppose that you are in low risk group and the nodules are solid in appearance then you do not require further imaging. However, the first CT scan was done at 6 months (probably assuming you were in high risk group or worst case scenario).

Hope this answers your question. Please feel free to correct any oversight in my interpretation of your problems and discuss them in detail as per your requirements.

Wish you a Merry Christmas.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

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Brief Answer:
No follow up CT scan required as you are in low risk with solid nodules

Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.

I appreciate your clarification. The 6 months follow up was certainly due to the probable diaphragmatic node.

If you are in the low risk group then, going by the Fleischner society recommendations, no follow up CT scan is required.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

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Brief Answer:
Please find details below

Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.

Your concern is understood and I wish to explain things in detail and discuss further.

1. Right now there are 3 nodules, largest about 6 mm in diameter, solid ones and not showing change in size during last 6 months.
2. As per statistics, your nodules are small enough and most likely benign and related to scar.
3. A nodule is termed malignant if it has a quick doubling time, which is on an average 120 days or 4 months.
4. However, malignant nodules have shown doubling times of 7 to 590 days, which is statistically significant.
5. Taking the worst case scenario, if they are malignant (which looks unlikely at the moment) then they will surely have doubled in size at the end of 590 days or 20 months. This is the reason a repeat CT scan is offered to high risk individuals after 24 months.

Coming to your particular case, with my experience after working in a cancer institute for some years, I would consider your nodules benign after verifying with the images myself.

For peace of mind and to be technically correct, if the nodules remain of unchanged after 590 days or 20 months following detection then malignancy is certainly ruled out without any confusion.

Regarding the radiation exposure, to be seen on an X ray a malignant nodule must grow to about 1 cm in diameter and this require 30 doubling times. Therefore X ray is not a suitable follow up investigation right now.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

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Brief Answer:
20-24 months CT scan is final authority as per current imaging guidelines

Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.

Glad to have been able to discuss your point in detail. Everything in place and with no added risks, I would consider your 6 months scan confirmatory in stating you have benign nodules.

Coming to your comment about being double sure after 12 months, let us say that the largest nodule is 6 mm and it is malignant with doubling time of 590 days (hypothetical) then it should measure 9 mm on the 12 months scan. Similarly the 4 mm nodule will measure 6 mm should it be malignant. Then we have to account for any small errors in appearance of nodule due to respiratory motion or observer variability by the radiologist (again hypothetical) and in the end you will still have persisting confusion because literature says that the slowest growing nodule will take 20 months to double.

If you go for a 20 to 24 months CT scan then the slowest growing nodules presently measuring 6 mm and 4 mm in side with measure 8 mm and 12 mm respectively. The wrong estimations due to technical errors and observer variability will be much lesser in the 20 to 24 months scan. Besides the 20 months CT scan will be the final authority with present day guidelines.

If it is possible to send me the CT scan images by uploading CD or DVD contents online using file sharing programs like Dropbox or Google drive and sending me the download link then I will be glad to see through them.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

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Brief Answer:
Welcome, you can get a CT scan done after another 12 months

Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.

It is normal for any patient to get worried when nodules are found in the lungs. Your doctors have taken the right decisions and there is no reason to get worried because the nodules are stable. Getting a CT scan in another 12 months should confirm the benign nature of the nodules.

Hope your query is answered.
Do write back if you have any doubts.

Regards,
Dr.Vivek

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