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CT Scan reliability?

Hatshepsut's picture
Posts: 340
Joined: Nov 2006

How reliable are CT scan results?

Can a doctor tell the difference between a cancer and scar tissue (if a surgery has previously been performed at the same site?)

Thank you.


chicoturner's picture
Posts: 285
Joined: Apr 2009

Hi, I just had scans yesterday, and consistant with previous scans I have had, prior to, they asked me lots of questions about meds, health and such but also about previous surgeries. My best guess is that having that info helps them read the scans! Good luck on those results! Jean

PhillieG's picture
Posts: 4912
Joined: May 2005

I was wondering on Wednesday when the surgeon was looking at my "spots" and I commented on how after years of looking at them how they can distinguish between a cancerous spot and just regular stuff. I thought my clear lung looked worse but I do not really know what i am looking at, I just see light and dark blotches.

One this about scar tissue and cancer is that I don't think scar tissue grows. I think there are also shades of gray that mean different things.
Hopes this helps a bit.

PamPam2's picture
Posts: 376
Joined: Jan 2009

I know in my case, when they saw "suspicious" areas on CT, they followed up with PET to check for uptake, and also did MRI with and without contrast, depending on what they are looking at and location, some tests show different things up better, and having the different tests to compare gives a better picture of exactly what they are seeing. In my case, the MRI is showing liver lesion the best out of the three types of scans, so every 3 to 4 months am having MRI with and without contrast to check for changes or growth on liver. I think once they have scans for a baseline, then they can see if there are changes in your subsequent scans.

John23's picture
Posts: 2140
Joined: Jan 2007

"I think once they have scans for a baseline, then they can see if
there are changes in your subsequent scans."

It should be noted, that often subsequent scans are taken at a slightly
different angles, resulting in wider or narrower "slices" that cause a
spot to appear larger or smaller, depending on the angle.

Nothing is perfect with diagnostics. There are variables in machines,
technicians, and other technical situations that can make a big difference.

Hatshepsut's picture
Posts: 340
Joined: Nov 2006

The reason I'm asking this question is that my husband has a recurrence in his abdominal wall. The CT scan, according to our oncologist, showed the mass at the surgical site where the pins were located during his major surgery in 2007. The CT did not show a recurrence at any other place. This happened last year in the same place and we do not anticipate that the surgeon, in removing the current mass, will have to go any deeper than the abdominal wall during the surgery that my husband now faces.

According to the oncologist, the mass is about 2 inches by 3 inches. Yesterday we saw the surgeon and he did a physical examination of my husband's abdomen and seemed to think the mass was larger. We have surgery scheduled for the 23rd and the surgeon plans to remove the mass and as much tissue as possible in the area as he can. In fact, he plans to do a hernia procedure (with mesh) at the site of the surgery because he anticipates taking connective tissue there to be sure the site is clean. Our oncologist then plans for some focused radiation at that site. (The radiation is new ground for us. I'm assuming that that will not happen until after my husband has healed.)

As we drove home, I began to wonder if the physical examination could possibly have led the surgeon to think the mass was larger because there would be scar tissue at that site from the 2008 surgery (in addition to the new mass). Hence, I asked the question whether the CT could distinguish between scar tissue and cancer and might have shown a smaller mass while the surgeon's tactile examination could not.


mcsauder's picture
Posts: 68
Joined: Nov 2009

I don't know about you guys but I have got scans for 4 yeas and the best one for myself is a PET SCAN it is the only one that shows the hot spots.
I had a cat scans, ct sans liver scan and MRI's and the only one that gave myself a true reading was the PET SCAN
tell us what you think

Posts: 163
Joined: Apr 2009

On a CT scan they see light and darkness and the dark spots can be tumors, old injuries, infection or scars. There is no way they can determine exactly what the spots are unless they do a repeat CT and the area is bigger or if they do a PET scan in which the spot "lights up" with the radioactive glucose. Then they usually do repeat PET scans to see if the lighting up spot gets bigger.......scars don't get bigger, tumors do.
If you have had recent surgery ( say 6 weeks or so it is possible that the lit up spot is the healing of the surgical incision.
Another way of knowing what a spot really is is a biopsy.
There is another way to do all this and that is a PET/CT all in one test.
No one should be having surgery based on a CT without a PET and /or a biopsy to define what is going on.

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