What causes differences in reading of CAT Scan and MRI imaging?

Posted by splendrous @splendrous, Dec 4 6:38pm

I had a Cat Scan 9/5 that first identified the cancer. Then I had an MRI 11/19/24 and then a Cat Scan 12/3/2024.

I am wondering how much difference is due to who is doing the measuring or difference in equipment. The MRI measurement did not show the growth of the original mass from 4 x 3.1cm to 4.5 x 3.2cm as the latest cat scan did. The MRI was read as 4.2 x 3.1cm. Rounding error I would think from the original scan.

The most recent cat scan also did not reference the lesion seen in the 9/5 scan on image 84 in the right lobe. I would have expected them to say they no longer saw it or reference it had not changed.

I also am not sure when the reading says he thinks the lesions are stable. How is that determined by reading the scans?

I am not sure whether to believe the scan or the MRI. One indicating there was growth from 4.0 to 4.5cm and one that showed a 4.1 vs 4.0cm which I would think could easily be difference of who did the reading.

Appreciate the experience of others. Thanks.

12/3/2024 Cat Scan;
Liver: There has been increased size of metastatic disease to the liver. For example, the largest mass in the liver is located in the anterior liver segment 4! measuring 4.5 x 3.2 cm. Previously measuring 4.0 x 3.1cm.

MRI 11/19/24
Liver: Multiple metastatic lesions in the liver which are best seen on series 502, diffusion-weighted imaging. The largest lesion in segment IVa measures 4.2 x 3.1cm on image 24 series 801. The second largest lesion in segment VIII measures 1.5 cm on image 31 of series 601. There are 6 additional lesions annotated on diffusion-weighted series 502. There is a T2 hypertense focus on image 25 or series 502 and image 21 of series 801 which is favored to be a vascular structure, as can be best seen on coronal series 701, image 45.

Cat Scan 9/5/2024
There is a low density mass in the interior of the left lobe segment 4A measuring 4.0 x 3.1 cm on image 92. There are additional low-density lesions noted throughout the liver, many of which are stable. There is also a new low-density lesion in the anterior right lobe the liver, segment 8 measuring 0.8 x 0.9 cm on image 84..

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jessie59 | @jessie59 | Dec 7 4:39am

I am equally confused with all these scans reports. On 8 July 24, CT scan revealed several white spots lesions in liver. I had Whipple done in May 2020 as diagnosed with NPET Gastrinoma at head of pancreas (stage 1, Grade 1 & functional). Blood tests that indicated high Gastrin Level of 700+ from 200+ 6 months ago. On 19th done blood tests on Chromograni A & Gastrin again (same result). On 20th - Liver MRI also reflected lesions. Then followed by PET GA68 Doctate scan which revealed no light up. 25 Sep - endoscopy in stomach revealed polys. 8 Oct - oncologist ordered ultrasound on liver with contrast but it was not lighted up hence they forgo the contrast.
Oncologist unable to prescribe chemo as unable to detect the actual location for biopsy before order of chemo.
May I know is this the correct procedure? Have anyone experience this?
I am currently on 40mg Esomeprazole (morning & night before meals) to control my Gastrin symptoms which actually would caused Gastrin reflux if not taken. At time still have dull pains if bend down. This is so that my oncologist can focus on the tumor(s).
Done my blood tests on 3 Dec & scheduled Liver MRI on 16 Dec before seeing surgeon on 30 Dec & 3 Jan on both results.