Hello, another question. I wrote earlier about trying to get my mom a diagnosis(lung cancer). My mom had a ct scan without contrast done about 5 weeks ago, which showed an area of concern in her left lung. She had a ct done yesterday (7/14)) with contrast. The report came back today and stated "no change" from 5 weeks ago, however the first ct scan (without contrast) measured the spot at 2.4 cm. The second one done yesterday (with contrast) measured 1.9 cm. The doctor explained that the reason for "no change" and different measurements is because of the contrast and perhaps a new angle. Can anyone explain this further? Just for reference she has not been treated for cancer, still trying to find out what it is. Thanks again for your help.
Nicole
ct vs ct with contrast. - 1264990
nicole80
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Reply # - July 16, 2014, 09:08 AM
Reply To: ct vs ct with contrast.
Hi Nicole,
Though CTs are high resolution, a millimeter or two is a very small amount and can be the result of using two different CT machines, or how the images “slice” (the scans consist of a series of images taken from slightly different angles and it is easy to add or subtract a millimeter or two depending on where the “cut” falls). Dr. West describes this in detail here: http://cancergrace.org/lung/2011/08/09/limits-of-ct-scanning/
JimC
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Reply # - July 16, 2014, 09:53 PM
Reply To: ct vs ct with contrast.
Imagine slicing an orange. Depending on where you slice it, the diameter of the slice of orange might be different.
A millimeter or two is definitely within the range of error. Studies have shown you can get more variability than that, typically as a combination of slight differences in how the CT slices cut a nodule or mass and how humans measure the nodule. Depending on where and how they measure even the same nodule at different times, or different radiologists having slightly different techniques/interpretation of how to measure a nodule diameter, that error can be several millimeters here or there.
Either way, having it measure smaller can only be reassuring.
Good luck.
-Dr. West
Reply # - March 18, 2015, 05:27 AM
My husband, 53 @ dx of stage
My husband, 53 @ dx of stage 3 squam nsclc R. pancoast tumor 8/09 caused destruction of 3 ribs, touching brachial plexus. 2 core and 1 VATS undx biopsies. Open thoracotomy for 1 positive biopsy (unresectable). Chemorads, 9/09. MRI by pancoast specialist surgeon 11/09 spine met found, stage IV, Rad to spine, Chemo changed from cis/etop to navelbine/carbo. 6 cycles total.
:*RosE*: