Rex,
Not trivializing at all! AVM (and aneurysms) can be life threatening.

I was responding to Chris in what I thought was a calming manner about her AVM. She has one, it is being watched, and her doc thinks it might have always been there , is small, and is not likely ever to cause a problem. You were the one who magnified things by showing the horrific AVM example which is a worst case, life threatening scenario.

My sister has an AVM and a benign brain tumor. Neither is being looked at as something to correct. Neither seems to be affecting level of function. My dad, on the other hand, has a tiny aneurysm on the carotid artery. Because of its location, it is likely to need intervention soon.

Teri Garr: IF the aneurysm was in the brain with the MRI, MRA, SPECT and PET scans done, there is no doubt in my mind that they knew about it. In fact, that may be why she had it repaired.

Now, please stop the hair splitting (mine's thin enough already) and accept the fact that I spoke from some knowledge of the situation with Chris and also some knowledge of the testing Teri had undergone in the previous year. You apparently had neither so spoke out of concern.

I'll leave you to your speculation, Cherie. I'm certainly not trying to split hairs. But I will say that SPECT and PET will not reveal a brain aneurysm. MRI might and it might not. The MRA would show an aneurysm, provided the lesion existed at the time of imaging. When did Teri have her MRI and MRA scans?

Radiologists tend to call any blood vessel that looks funny an AVM; it's become something of a catch-all, usually written as "most likely represents a small AVM." These things don't come with labels on them, so the radiologist takes his best guess; the more brains you look at, the more you realize that there are a myriad of common anatomical variations which are "of no clinical significance."

OTOH, any aneurysm is a significant finding, no matter how small it is.


rex

I love this thread....."The Battle of the Experts"

Of course, none of you are "experts", but you are all, certainly, experienced, and while you are debating, I'm learning. Thanks.

Cherie, you were trivializing, on Chris's (who is also a nurse) behalf, and Rex, you did over-react by bombarding us with the worse case of an AVM. I did appreciate the films, Rex.

My conclusion...You were both wrong and you were both right, and I learned much, from both of you. Just try to remember, not to take these debates personally.

Debating can sometimes appear as personal attacks, but it is not, rather it is the argument/attack of an Idea, not the person.

If I came across as trivializing, I am sorry. That was never my intent.

SPECT looks at the blood flow in the brain so would pick up an AVM and an aneurysm.

Any aneurysm is cause for concern and is generally repaired shortly after discovery if it is not in an area that repair would likely cause more damage than leaving it alone.

Cherie...you are wrong. I know you think you're right...maybe you're Googling this stuff and you found something linking SPECT to bloodflow (which is true), but that does not mean that SPECT can depict anatomy. I suspect you've never seen a SPECT image, so I'll post one here:





SPECT shows blood perfusion to areas of the brain; it does not show anatomical structures. Neither does PET, which is why the PET/CT machine was developed. PET just shows a dark spot, but it's essentially floating - there are no anatomical structures seen. The CT scan is done immediately after the PET, while the patient is still on the table. The machine then fuses the two different scans into a single set of images which show both the lesion and its precise anatomical location:






SPECT will demonstrate that there is a lack of perfusion (blood flow) to a part of the brain, but it will not show the defect causing it.

Rex,
You are WRONG to call me wrong. I have had a SPECT scan and I have seen several. I had the scan because I had already had an MRI and MRA of the optic pathways, and had a bilateral hononymous hemianopia and had the doc's stymied as to the cause. You can see blood actually moving as the scan is being done and you can see areas of narrowing or buldging of vessels.

Now, I don't know you or your credentials but I do know mine. And you sound dangerous with your misinformation and googling(?) of information. You see, I don't need to google info of this nature because I've either experienced it or been taught it.


Nuff said!

Cherie,

I'm a 20-year radiology professional. I don't care what you say...you are dead wrong about using SPECT to visualize an aneurysm.

Enough said...I certainly am not here to battle with you. I can assure you, though, that I am neither dangerous or a Googler. If you want to believe otherwise, or that SPECT is diagnostic for aneurysm, be my guest. Nuclear medicine exams are (in these cases) done to visualize perfusion - as I have said - but it is not an anatomically diagnostic procedure. It gives metabolic information which is useful for correlating with other modalities like MRA, plain-film/digital angiography and CTA. It would be very unusual to order a SPECT exam to r/o aneurysm, as they are far better-visualized by angio procedures. To draw a close parallel - I had my stress test (nuclear exam) to assess the patency of the coronary arteries. The camera detects the radioactive tracer as it seeks out the heart muscle (certain isotopes seek out certain tissues). Had the images revealed that the tracer was not reaching the heart muscle in sufficient quantity, the conclusion would have been that the coronary arteries were to some degree blocked. At that point, a cardiac catheterization might be done - angiography - to visualize the coronary arteries in real-time as the iodinated contrast material is injected.

Brain angiography is done in a similar manner. If the physicians decide that a less invasive procedure would be diagnostic to visualize the vessels, then an MRA is substituted for the plain-film/digital angiography...that way, no catheterization is necessary.

These are the universal protocols for visualizing vascular structures. Nuclear scans raise the possibilities, angiography (CTA, MRA or plain-film/digital angiography) visualizes the lesion.


Whatever...no use arguing or beating a dead horse.

.

king rex,

thank you for sharing your knowledge on this subject with us. i'm glad to know that it is backed up by experience and education. so often stuff is posted and we have no idea if it is valid. i guess some just assume it is correct when it may not be even close.

thanks --

Last February I underwent a SPECT scan as part of a Parkinson's disease research program, the object of which is to determine if it is possible to diagnose PD before its overt symptoms appear. There seems to be a familial form of PD in my family, since my mother and older brother had it, and I was diagnosed with it 5 years ago. My unaffected sister and two unaffected nieces, daughters of my late affected brother, were also scanned.

Before we went to have the scans done, I read up on the SPECT procedure and instrumentation as it is used in imaging brain structures of particular interest for this particular program. In our case, the target was the dopamine transporter function in the putamen of the basal ganglia, and the tracer that was used was an Iodine 125-labeled compound taken up specifically by certain cells in that organ. The amount of the label taken up 61-18 hours after IV injection is measured as a surrogate marker for dopamine re-uptake by dopaminergic neurons in the putamen. As PD progresses, this function decreases, and is 70-80% gone before clinical symptoms appear. The researchers doing the study have apparently identified the gene mutation in our family related to PD, and they are looking for changes in dopamine transproter function in the yet unaffected family members that might indicate early stages of PD.

My point in posting this is simply to share with you what I know about SPECT; that the technique may be used to image different functional areas in the brain, depending on the chemical nature of the tracer substances that are utilized.

Robert

You're correct; each tracer (isotope) is specific to a certain area or function. It's essentially a metabolic study.