If a doctor feels that the biochemical tests show a reasonable chance for pheochromocytoma, the doctor will order abdominal CT or MRI to see if there is an adrenal tumor. Abdominal ultrasound is not good enough for characterizing an adrenal tumor. On CT, most pheochromocytomas appear as a high-density mass, and on MRI, several protocols will determine if an adrenal mass is more likely to be a benign adenoma or "atypical" or "consistent with" pheochromocytoma.
A contrast material will be given intravenously. The contrast material is given because it will tell if a given organ or tumor has a lot fo blood supply or not. Pheochromocytoma has many blood vessels in it, thus it shows "enhancement" (just means it appears much brighter after contrast material is given.)
Sometimes, the biochemical tests suggest pheochromocytoma but CT or MRI does not find any adrenal masses. Now two things are possible: either the patient has pheochromocytoma but the tumor is somewhere else, or the patient does not actually have pheochromocytoma. The doctor should pause and weigh the evidence and decide which way to go.
If the biochemical tests strongly suggest that a patient has pheochromocytoma, regardless of imaging results, a functional scan called "MIBG" is done afterwards. Pheochromocytoma is very savvy in taking up MIBG. The value of MIBG scan is questionable for most patients but is considered an extra layer of caution. The MIBG scan can be falsely positive for some patients.
Subscribe to:
Post Comments (Atom)
so if CT has already found a pheo, why is MIBG then needed? (this is happening to my mum)
ReplyDeleteIn most people, MIBG scan gave little extra information. Occasionally MIBG can identify pheos in other organs. I still order MIBG scan just to be safe.
ReplyDeleteDr. Pheo
Thanks - the MIBG showed nothing new, so now she is booked to go into hospital on 9 June to have the BP reduced prior to surgery on 15 June.
ReplyDeleteWhile I'm at it, Dr Pheo, my mother is currently on Dibenyline and is not quite clear what it is for; she reckons that since she has been on it she has had bad bowel symptoms that make it difficult for her to be away from the toilet. She has a pre-existing problem whereby one of her sphincters doesn't work. Is this drug associated with problems like this?
ReplyDeleteSorry for my late answer.
ReplyDeleteDibenzyline should be started as soon as the pheo diagnosis is made. Please read the post on preoperative preparation on this blog. I am not aware of bowel incontinence as a side effect of this drug.
For most patients, the preparation can be done safely at home. She probably does not need to stay in the hospital for 6 days before the operation, unless there are other issues.
Dr. Pheo
Thanks - this is very timely as she has her pre-op meeting with the surgeon tomorrow and I'll be present at this!
ReplyDeleteThey say she may be allowed home for the weekend in between the preparation and the operation, if the preparation is sufficiently successful. Which is something to hope for...
ReplyDeleteHi Dr. Pheo. What do you think of the Octreoscan? I recently had a plasma-free metanephrines test come back with about four times the normal levels. My dr. consulted with some radiologists here in Tallahassee and they decided this was the best next test. I am in day two of scanning and am curious if I will get kicked back for an MRI regardless of what the Octreoscan uncovers.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteGreat post! You have made some really good points here. The choice of diagnostic test should be based on the clinical suspicion of a pheochromocytoma.
ReplyDeleteHi Dr Pheo, I have been having episodes of symptoms that mimic pheochromocytoma but blood and urine tests are normal. Is it possible to still have a pheochromocytoma?
ReplyDeleteDear TraceyK,
ReplyDeletePheo is ruled out in your case.
Dr. Yu
I am having symptoms of pheo. Uncontrolled, unstable blood pressure, sometimes 220'/130's then it will drop to 130/90 in the same day without medication. I have panic like attacks. Crushing headaches that sometimes last days. Hot flashes with sweating. I have pvcs and they are coming more frequently. Also a side note, I have a parathyroid tumor, hyperaldoseronism and had an ovarian tumor in the past removed. I have only had urine catecholamines checked once and epinephrine was undetectable and norepinephrine was low. Others were normal. Blood results showed slightly elevated norepinephrine. (Suggesting I had stress due to blood draw) I had a ct scan (without contrast) and it showed nothing. Do you think I may have a pheo?
ReplyDelete