what are ct scans unable to see

[Elaine]

My tumor started in my right main bronchus. There has always been somewhat of a question as to if the area in the lung is turmor or a small area of collapsed lung. At one point they thought it was the beginning of a different tumor. Whatever it is, it hasn't grown much at all in 10 months.

I assumed a spiral CT scan could "see" tumors within a bronchus or within the trachea, but the tech today told me that a CT scan is not a good way to "see" either place.

However, my first scan report does indicate an area that he presumes is the mass within the bronchus.

So is the tech right or wrong?

[kimblanchard]

The tech is right. CT scans do not see the details of the airways very well. They will sometimes see a tumor in a major bronchus but they miss a lot. There is a new technology called virtual bronchoscopy that allows a CT scanner to do 3D reconstruction of the bronchial tree that is much better at seeing inside of the airways. I have only seen demos, have never actually ordered one.

[SDianneB]

If I may, I'd like to piggyback a question to this topic that I think is related.

Elaine describes a "small area of collapsed lung." Is this what is referred to as atelectasis?

Between the latest CT and PET scans I had, there has been a place at my right lower lobe that they weren't quite sure of, and I think have finally decided is scarring/radiation pneumonitis. (It was the site of the largest original tumor where I had pneumonia at the time I was diagnosed in early June 2004.)

The Oncologist said atelectasis, and based on all the scans I've had, it's about the same as it's been all along, except that the latest PET scan showed no uptake there like on the first PET scan.

Thanks in advance,

Di

[SDianneB]

Guess not.

[teresag]

Elaine describes a "small area of collapsed lung." Is this what is referred to as atelectasis?

No. Atelectasis means that the tiny air sacs called alveoli have collapsed and are unable to open & fill with inhaled air. This will look hazy on the chest xray. A lung collapse means that the two linings of the lung, called the pleura, have separated, causing part of the lung to collapse in on itself. Both have the same effect of limiting the amount of lung that can fill with air each time you inhale, but they have different causes and treatments.

[SDianneB]

Thanks, teresag

[kimblanchard]

Technically what teres is referring to is a pneumothorax which is also often referred to as a collapsed lung. There is another type of "lung collapse" where something obstructs a bronchus (main lung airway) which doesn't allow the distal part of the lung to fill with air and hence collapse. With a pneumothorax the lung collapses in on itself. With bronchial obstruction, the contents of the chest will shift towards the side of the obstruction (referred to as mediastinal shift).

Atelectasis is technically, as described, non-filling of the small airways of the lungs although some doctors will use this term interchangeably with the type of lung collapse I am describing above.