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Lung diseases

Spiral CT scan versus high resolution scan

03/13/2008

Question:

I had a spiral CT scan which detected a noncalcified nodule at the base of my left lung. I am due to have a 3 month follow-up scan, and I was told it will also be a spiral CT scan. When is a high resolution scan done? Please explain the differenc between the two types of scans and when they are used. Thank you.

Answer:

A spiral CT is designed to evaluate localized abnormalities in the lungs such as nodules or masses--lower resolution images are taken at multiple points (or cuts) fairly close together (perhaps 10mm apart). High resolution CT scans are better equipped to evaluate abnormalities that involve the entire lung (or most of it) such as inflammation or fibrosis. Although the details of the image may be finer, the cuts (or individual images) are taken with a much greater distance in between the images (40 mm for example). The result is significantly fewer cuts (or images) with significantly finer detail....For abnormalities such as small pulmonary nodules, a high resolution CT scan may miss the abnormality all together (if the nodule happens to fall in between two images or cuts) or may distort the abnormality artificially.

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Response by:

Jennifer  McCallister, MD Jennifer McCallister, MD
Clinical Assistant Professor of Pulmonary, Allergy, Critical Care & Sleep
College of Medicine
The Ohio State University