How easy is it to differentiate between benign liver spots and small mets on a CT scan?

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Static500
Posts: 2
Joined: Tue Jan 12, 2021 6:48 pm

How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby Static500 » Tue Jan 12, 2021 7:24 pm

Hi,

Currently undergoing 3m of CAPOX for stage IIIb ascending colon cancer following successful right sided hemicolectomy in October.

Just revisiting my (second) CT scan at diagnosis and for the lungs there were “no significant pulmonary nodules” whereas for the liver there were “sub centimetre simple hepatic cysts unchanged” and “focal low attenuation change adjacent to falciform ligament likely to represent focal fatty deposition”. Note that where it mentions unchanged / changed this is in relation to the first CT scan 7 weeks earlier (which only said inflammation in colon rather than diagnosing cancer).

Have read some research saying that it can be hard to differentiate between very small liver mets, cysts and fatty deposition so just wondering if anyone has had similar and know how certain they can be from the scan that the above findings are not infact v early mets? Oncologist has never raised it and I’m not worried about it, more of general interest having done some research and re read my reports. My CEA has also doubled from 1.6 to 3.2 in the 3 weeks between first and second CAPOX cycles but again these are normal type levels and can often increase during chemo so don’t think anything to be concerned about.

Thanks.
41m, stage IIIb
BRAF V600E mutation

10/20 dx stage IIIb colon cancer after severe anaemia (shortness of breath when running)
T3/4 N1 M0 R0 L1 V1
ascending colon tumour 65mm, poorly differentiated
Lymphatic and venous invasion
2 of 28 lymph nodes positive
Various polyps incl one with low grade dysplasia (to be removed via polypectomy post chemo)

10/20 laparoscopic right-sided hemicolectomy with clear margins

12/20 started 3m CAPOX
Targeting normal running regime through chemo (100 miles per week)

User avatar
GrouseMan
Posts: 849
Joined: Mon Aug 12, 2013 12:30 pm
Location: SE Michigan USA

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby GrouseMan » Wed Jan 13, 2021 12:48 am

Imaging is not a very good means of differentiating one thing from another and it really takes specialists with a good eye to even see the very subtle changes in between scans. One would like to have the same radiologist compare the scans and hopefully not be the first or last of the day that they do. It can be quite subjective when looking for a needle in a hay stack! The physics involved the imaging technology and resolution makes it a very difficult task. Additionally you probably don't want just any radiologist to do this. Best if one that is a specialist in abdominal cancers does it as they have a practiced eye verses someone that is a general radiologist looking for fractures or orthopedics issues.

Benign can really only be determined by a biopsy. Visually they probably look to be very much the same. My wife's liver mets looked like they had calcified according to her oncologist after Chemo, and he said probably dead. The one on her spleen disappeared completely. But the one that was in her peri cavity was very hard to visualize and wasn't really able to resolve very well until about 2 months before she passed away! That was the one that really did her in. It caused a blockage pinching off her colon basically from the outside and also pinched off one of her ureters' from her kidney to her bladder. The spots they thought might be mets in her lungs never ever changed and early on after initial chemo her oncologist believed they were not mets. So CT PET etc are only good for monitoring progress really.

Your CEA test are well within what is considered normal range. Doubling could be well within the range of testing error. And as some will indicate it can be raised by other factors. For many its not a good test at all. If it continues to climb out of the 5.0 range over several tests during the next 6 weeks then you might become concerned. My wife's started to go down and was in/near the normal range for quite some time but towards the end it started to climb back out again. So it was an indicator in her case of further growth when the chemo no longer was effective.

Good luck and try not to stress too much. If you haven't had a second opinion you might look into that. But still it appears your treatment is the standard one almost everyone starts out with in Stage IIIb. They don't seem to think there are any mets as far as I can see. If there where they would have staged you at stage IV.

GrouseMan
DW 53 dx Jun 2013
CT mets Liver Spleen lung. IVb CEA~110
Jul 2013 Sig Resct
8/13 FolFox,Avastin 12Tx mild sfx, Ongoing 5-FU Avastin every 3 wks.
CEA: good marker
7/7/14 CT Can't see the spleen Mets.
8/16/15 CEA Up, CT new abdominal mets. Iri, 5-FU, Avastin every 2 wks.
1/16 Iri, Erbitux and likely Avastin (Trial) CEA going >.
1/17 CEA up again dropped from Trial, Mets growth 4-6 mm in abdomen
5/2/17 Failed second trial, Hospitalized 15 days 5/11. Home Hospice 5/26, at peace 6/4/2017

Basil
Posts: 272
Joined: Thu Mar 16, 2017 12:33 pm

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby Basil » Wed Jan 13, 2021 7:14 pm

I was on my second to last scan before being released from surveillance and they found a small liver spot “not definitively seen” on my prior. My onc is not concerned about it (and my CEA is unchanged) but he ordered a MRI for my next scan, which was then eight months away. Says it’s probably a cyst. We’ll see in March!
40 y/o male (now 43), kids 9 & 12
Dx 3/16/17, rectal cancer s3,t3,n1,m0
PROSPCT trial (FOLFOX in lieu of chemorad)
FOLFOX 4/5/17 - 6/26/17
LAR 7/31/17, temp ileo
pathological complete response
Adjuvant chemo cancelled (IDEA Study)
Ileo reversed 9/25/17
NED
1 year scans - clear
2 year scans - clear
3 year scans - clear

boxhill
Posts: 673
Joined: Fri Apr 06, 2018 11:40 am

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby boxhill » Thu Jan 14, 2021 11:10 am

In my experience, a regular CT can't even pick up a 5 mm or so liver thing. It's too small. A multiphase CT may be able to. An MRI definitely can. But none of them, not even the MRI, can definitively say what they are and whether they are malignant. Only a biopsy can do that. And for a spot that small, it likely makes more sense to just remove it, depending on where it is in the liver. But even if it is on the surface of the liver, like my little mass, they are likely to say that it isn't worth even the small risk of liver injury unless it changes. Which is why my little liver thing is still there, but after 2+years of no change at all is considered to be something inert. So I am NED.

BTW, it is my understanding that a PET scan has the same size constraints as a CT scan, so if a mass is tiny it is not likely to pick it up.

Please note that everything I've said pertains strictly to VERY SMALL liver masses. Under a cm.
F, 64 at DX CRC Stage IV
3/17/18 blockage, r hemi
11 of 25 nodes,5 mesentery nodes
5mm liver met out
pT3 pN2b pM1
BRAF wild, KRAS G12D
dMMR, MSI-H
5/18 FOLFOX
7/18 and 11/18 CT NED
12/18 MRI 5mm liver mass, 2 lymph nodes in porta hepatis
12/31/18 Keytruda
6/19 Multiphasic CT LNs normal, Liver stable
6/28/19 Pause Key, predisone for joint pain
7/31/19 Restart Key
9/19 CT stable
Pain: all fails but Celebrex
12/23/19 CT stable
5/19 MRI stable/NED
Stop Key
8/20 MRI NED

I_will_fight
Posts: 62
Joined: Mon Jun 29, 2020 3:38 pm

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby I_will_fight » Sat Jan 16, 2021 2:06 pm

Not sure if this helps, but I am asking myself the same question:

I have a 1cm nodule in my liver, the report mentioned it was more likely an hemoangioma.

This is what the CAT report says:

"In the periphery of liver's segment VIII a high-gain 10mm lesion in arterial-phase which becomes homogeneous in portal-phase, unchanged from previous CAT study, this suggest hemoangioma, but given the clinical context RMI is advised"

I was a bit nervous so I asked my surgeon and oncologist.

My surgeon (really great guy!) opened my last CT scan in his screen, and he patiently explained to me the following:

- The lesion has not changed in 6 months
- The lesion shows up with due to contrast when filled by artery blood.
- The lesion does not show up with Porta vein contrast.

Apparently this is not the way colon carcinoma mets show up in TACs, so they think it is not a MET, but being a cancer patient they still recommend an MRI which I will have in three weeks time.
46 yo male Spain
06/20 - 6cm T3N0M0 CC splenic flex
No liver mets, 3 and 4 mm lung dots (unlikely to be mets)
lymp 0/37
MSH6- other MMR+
KRAS mt G13D
V/LNI absent
PNI present
07/20 - hemicol surg, 13cm clear margins, optimistic surgn.
08/20 - CAPOX regime, 4 cycles.
11/20 - CAPOX completed. CAT scan: lesion in liver, suspect hemoangioma, no changes lung dots.
12/20 - Clean colonoscopy
02/21 - MRI liver lesion is nonspecific, stable.

jts
Posts: 48
Joined: Sat Aug 24, 2019 3:07 pm

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby jts » Mon Feb 01, 2021 8:52 am

I have a similar problem ATM. A MRI in December showed a 5mm thing in my liver that the radiologist judged to be a cyst. Looking at my most recent CT scans, the thing is clearly visible (once you know it's there), but in the CT it's just a slightly darker spot in one slice. In the MRI you can make out a high-intensity center surrounded by a dark shell, whereas the rest of the liver looks greyish with whitish vasculature.

Anyhow, the cyst is visible in my CT scans back to late last summer, but not visible before that. So it's safe to say the blob is either new or growing. Meanwhile the upward trend of my CEA continues with a new high measurement in January.

The MRI also notes a smaller cyst in my kidney, but my amateur eyes have trouble seeing it. That is a much less likely location for mets, anyhow.

There are some open access papers talking about how to distinguish between benign and metastatic liver cysts on MRI.
"Differentiating metastatic mucinous colorectal adenocarcinomas from simple cysts of the liver using contrast-enhanced and diffusion-weighted MRI" is not hard to read and has lots of picture examples.

"Colorectal liver metastases: radiopathological correlation" is harder to read but has lots of pictures of different types of scans compared to pictures of actual resected tumors.

My impression is that on an MRI an expert can have some clues about whether a small cyst is a met or benign, but the CT can only check for the presence and maybe the size of the thing. Another option is ultrasound. Much easier to get.
Male 42 — stage IV RC
08/2019 DX 6 cm long tumor
09-10/2019 Chemo-radiation
12/2019 TME Surgery, clear margins, 7/16 nodes positive
Pathology: ypT3 ypN2b M0
01-06/2020 - FOLFOX
CEA only goes up during chemo: 2.4 --> 6.2
07/2020 6 mm tumor in lung, was growing fast during chemo
09/2020 VATS
NRAS mutant - KRAS, BRAF wt
01/2021 new 5mm cyst in liver, CEA continues to increase

menreeq
Posts: 70
Joined: Fri Jun 30, 2017 10:26 am

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby menreeq » Mon Feb 01, 2021 4:39 pm

I may have replied to this in the past, but I'll do a brief response. I am a radiologist, but this is NOT medical advice. I saw some information in the other posts that I wanted to comment on.

CT has better spatial resolution than MRI, but MRI has better contrast resolution. They have different pros/cons. CT slices can be as thin as 0.625 mm. MR slices tend to be significantly bigger (5 mm for example) -- depending on the protocol that is in use, which varies from place to place. But "spots" will show up as bright on the MRI on certain sequences, so they can be easier to see. Regarding "regular" CT vs "multiphase" CT --> it really depends what is meant by "regular." If it is without contrast, mets are very difficult to see. CT for CRC mets should be done with contrast, but sometimes people cannot have contrast for other reasons. Multiphase CT means you do multiple CT exams in different phases of where the contrast is in your body (no contrast, contrast in the arteries, contrast in the portal veins, contrast in the systemic veins, delayed phases, etc) -- and this also depends on the protocol being used by your hospital or imaging center. Seeing the liver in different phases makes it easier to see "spots." Ultrasound is less sensitive than CT and MRI, so this is not typically recommended in the US, but may be recommended in other healthcare settings. Ultrasound is less expensive and has no radiation. PET/CT requires that a lesion be at least 8mm to be detected (sometimes smaller spots can be detected if they are very active).

If a "spot" is less than 8-10mm, it can be difficult to tell on CT if it contains water only (a cyst). The phrase "too small to characterize" is often used. If it's bigger than 10mm, looks like water (this is determine by density on CT and signal on MRI), and does not enhance (meaning the contrast gets into it and it gets brighter), it is called a cyst (a benign finding). Anything that does not meet the criteria for water or that enhances is looked at much more carefully --> maybe it is a complex cyst, a benign liver tumor, or cancer. There are many enhancing tumors in the liver that are not cancer, and they have certain patterns on CT and MRI (especially the latter) that a radiologist can evaluate. But if your CT is for colon cancer surveillance, the radiologist is looking with special attention to where CRC mets go (liver, lungs, brain, peritoneum, ovaries, bones, etc). Fatty infiltration looks different than a "spot" - it is shaped differently and not as well defined. It looks different from typical metastases. Small mets will be indistinguishable from benign lesions, which is why surveillance and looking at change over time is necessary, as well as following CEA levels and any other markers that are helpful for that cancer.

I hope everyone's spots stay small and benign!
Stage IIA rectosigmoid CC (T3N0M0)
Dx 6/5/17 @age 41ls
Workup: c-scope, EUS, rectal MRI, CT C/A/P
AdenoCA 5.5cm, WHO Grade 2, 0/22 LN, no distant mets
CEA 1.9 (6/5/17), 0.8 (2/28/18), 1.0 (9/17/18), 1.1 (4/16/19), 1.0 (9/24/19), 1.7 (7/8/20)
No lymphovasc/perineural invasion, clear margins
MSI intact, OncotypeDx RS 7
Lap sig colectomy 6/23/17, no ileo/colostomy
Genetics neg for mutations, 4 VUS
Xeloda monotherapy 8/13/17-1/22/18
PET/CT 3/21/18 NED
CT C/A/P 9/17/18 NED, 3/8/19 NED, 9/19/19 NED, 5/13/20 NED

Jess83
Posts: 34
Joined: Sun Dec 02, 2012 7:06 am

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby Jess83 » Mon Feb 01, 2021 8:22 pm

menreeq wrote:I may have replied to this in the past, but I'll do a brief response. I am a radiologist, but this is NOT medical advice. I saw some information in the other posts that I wanted to comment on.

CT has better spatial resolution than MRI, but MRI has better contrast resolution. They have different pros/cons. CT slices can be as thin as 0.625 mm. MR slices tend to be significantly bigger (5 mm for example) -- depending on the protocol that is in use, which varies from place to place. But "spots" will show up as bright on the MRI on certain sequences, so they can be easier to see. Regarding "regular" CT vs "multiphase" CT --> it really depends what is meant by "regular." If it is without contrast, mets are very difficult to see. CT for CRC mets should be done with contrast, but sometimes people cannot have contrast for other reasons. Multiphase CT means you do multiple CT exams in different phases of where the contrast is in your body (no contrast, contrast in the arteries, contrast in the portal veins, contrast in the systemic veins, delayed phases, etc) -- and this also depends on the protocol being used by your hospital or imaging center. Seeing the liver in different phases makes it easier to see "spots." Ultrasound is less sensitive than CT and MRI, so this is not typically recommended in the US, but may be recommended in other healthcare settings. Ultrasound is less expensive and has no radiation. PET/CT requires that a lesion be at least 8mm to be detected (sometimes smaller spots can be detected if they are very active).

If a "spot" is less than 8-10mm, it can be difficult to tell on CT if it contains water only (a cyst). The phrase "too small to characterize" is often used. If it's bigger than 10mm, looks like water (this is determine by density on CT and signal on MRI), and does not enhance (meaning the contrast gets into it and it gets brighter), it is called a cyst (a benign finding). Anything that does not meet the criteria for water or that enhances is looked at much more carefully --> maybe it is a complex cyst, a benign liver tumor, or cancer. There are many enhancing tumors in the liver that are not cancer, and they have certain patterns on CT and MRI (especially the latter) that a radiologist can evaluate. But if your CT is for colon cancer surveillance, the radiologist is looking with special attention to where CRC mets go (liver, lungs, brain, peritoneum, ovaries, bones, etc). Fatty infiltration looks different than a "spot" - it is shaped differently and not as well defined. It looks different from typical metastases. Small mets will be indistinguishable from benign lesions, which is why surveillance and looking at change over time is necessary, as well as following CEA levels and any other markers that are helpful for that cancer.

I hope everyone's spots stay small and benign!


This was super insightful- thank you so much sharing!!!
2012 - Stage 1 - 29 yo in Australia
Diagnosed whilst pregnant
18mm Polyp - T1 NX M0
May 13 - TEMS procedure - Clear margins!!!
Feb 14 - Had a baby!
June 14 - clean colonoscopy & PET
June 15 - clean sigmoidoscopy & PET
July 17 - clean colonoscopy
August 19 - clean colonoscopy
Dec 2020 - It's back :( 35mm tumor next to original resection
Confirmed Stage 4 with met to adrenal gland
Jan 2021 - Adrenal gland removed
Started 3 rounds of FOLFOX

Static500
Posts: 2
Joined: Tue Jan 12, 2021 6:48 pm

Re: How easy is it to differentiate between benign liver spots and small mets on a CT scan?

Postby Static500 » Thu Feb 11, 2021 9:27 pm

Thanks for all the detailed replies. Turns out I have the BRAF V600E mutation so rather than waiting till post chemo (just started cycle 4 Capox) then my oncologist has scheduled a CT with contrast for tomorrow. If anything concerning re small spots in the liver then will have MRI to follow. My CEA has only risen slightly since last read a few weeks back now 3.5 so still normal and oncologist not concerned about it.
41m, stage IIIb
BRAF V600E mutation

10/20 dx stage IIIb colon cancer after severe anaemia (shortness of breath when running)
T3/4 N1 M0 R0 L1 V1
ascending colon tumour 65mm, poorly differentiated
Lymphatic and venous invasion
2 of 28 lymph nodes positive
Various polyps incl one with low grade dysplasia (to be removed via polypectomy post chemo)

10/20 laparoscopic right-sided hemicolectomy with clear margins

12/20 started 3m CAPOX
Targeting normal running regime through chemo (100 miles per week)


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