CT vs. CT/PET and what they show

Hi,

PET/CAT go hand in hand;they are both useful diagnostic tools and often are assigned together:CAT scan imaging  shows actual tumors  similar to the  ultra sound,  whilst PET scans  show areas of increased metabolic activity and it is preferred by doctors as  indication about  a possible metastatic spread and how far it had gone:the PET  looks like holographic image where areas of suspicious activities light up in yellow-orange color. 

Thus being said, you are right, PET do not pick up tumors less than 6 mm:I've had a clear PET in March just to have a recurrence confirmed one week later that was less than  2 mm /melanoma is a hiding bitch!/Talk about emotioal rollercoaster!!!

Having clear CAT/PET DOES NOT mean you are cancer free!/sad but truth/, as I came to find out.

It means there is no resectable disease, but there stiil might be microscopic amounts of cancer lurking underneath or circulating in the blood stream/sad but true/, or you might not have any cancer at all.At this point in time there is no way this can be known for sure-and that's in my opinion is where the medicine has to catch up, and  quick!Myself I believe in prevention, and acton-ASAP!and stay on top if it as a key to survival.

Good luck to you.

Teodora

Hi,

PET/CAT go hand in hand;they are both useful diagnostic tools and often are assigned together:CAT scan imaging  shows actual tumors  similar to the  ultra sound,  whilst PET scans  show areas of increased metabolic activity and it is preferred by doctors as  indication about  a possible metastatic spread and how far it had gone:the PET  looks like holographic image where areas of suspicious activities light up in yellow-orange color. 

Thus being said, you are right, PET do not pick up tumors less than 6 mm:I've had a clear PET in March just to have a recurrence confirmed one week later that was less than  2 mm /melanoma is a hiding bitch!/Talk about emotioal rollercoaster!!!

Having clear CAT/PET DOES NOT mean you are cancer free!/sad but truth/, as I came to find out.

It means there is no resectable disease, but there stiil might be microscopic amounts of cancer lurking underneath or circulating in the blood stream/sad but true/, or you might not have any cancer at all.At this point in time there is no way this can be known for sure-and that's in my opinion is where the medicine has to catch up, and  quick!Myself I believe in prevention, and acton-ASAP!and stay on top if it as a key to survival.

Good luck to you.

Teodora

PET scans do not trell the doctors that there is a tumor.  Pet scans show where the glucose taken before the scan is absorbed the most in the body.  Since it is known that cancerous tumors "like" the glucose and a larger amount is likely to settle in tumors from the blood flow in them.   "Hot spots" Indicates locations to be checked out, they do not automatically say cancer.  There are other reasons for hot spots, They told my Onc to take a close look at my leg which was mangled in a car wreck.  They also told him to follow my mouth where I had oral surgery  as well as other places that I have injuried in previoius years.  Those were all "False Positives".  PET scans are well known for false positives.  PET scans are also known for false negatives.  If a mole (or tumor) does not have a blood supply network to feed the glucose to it, then it will not light up.  I have had several fast growing tumors that I spotted and the PET/CT reading missed.   I would expect  it to be rare for a PET to light up on even a melanoma mole that was not very invasive. 

   The reason that MRI's are used for brain scans rather than using PETS is that the brain has much blood flow and therefore collects much glucose.  That would be a LARGE hot spot! (and hopefully a false positive.)

   Most Scans are done using 5 mm slices.  if an tumor is not large enough to be where a slice is taken it could be up to almost 5 mm and not be seen on the scan.  If it is sliced by one reading, but not shown on two adjucant slices than the size cannot be told exactly.  A CT scan is more exact for the size of tumors than the hot spot from a PET.  A PET is a tool to follow up on, not a definition by itself.  Growth over time as seen on CT is the most definitive item short of a biopsy.  PET shows where to look at on later CT's.

PET scans do not trell the doctors that there is a tumor.  Pet scans show where the glucose taken before the scan is absorbed the most in the body.  Since it is known that cancerous tumors "like" the glucose and a larger amount is likely to settle in tumors from the blood flow in them.   "Hot spots" Indicates locations to be checked out, they do not automatically say cancer.  There are other reasons for hot spots, They told my Onc to take a close look at my leg which was mangled in a car wreck.  They also told him to follow my mouth where I had oral surgery  as well as other places that I have injuried in previoius years.  Those were all "False Positives".  PET scans are well known for false positives.  PET scans are also known for false negatives.  If a mole (or tumor) does not have a blood supply network to feed the glucose to it, then it will not light up.  I have had several fast growing tumors that I spotted and the PET/CT reading missed.   I would expect  it to be rare for a PET to light up on even a melanoma mole that was not very invasive. 

   The reason that MRI's are used for brain scans rather than using PETS is that the brain has much blood flow and therefore collects much glucose.  That would be a LARGE hot spot! (and hopefully a false positive.)

   Most Scans are done using 5 mm slices.  if an tumor is not large enough to be where a slice is taken it could be up to almost 5 mm and not be seen on the scan.  If it is sliced by one reading, but not shown on two adjucant slices than the size cannot be told exactly.  A CT scan is more exact for the size of tumors than the hot spot from a PET.  A PET is a tool to follow up on, not a definition by itself.  Growth over time as seen on CT is the most definitive item short of a biopsy.  PET shows where to look at on later CT's.