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CT vs MRI

NomadicMike's picture
NomadicMike
Posts: 33
Joined: Feb 2013

I'm a little concerned about the radiation dosage of frequent CT scans.  Does anyone use MRI instead of CT scans for followup?  Why would a CT scan be preferred?  Is it better at seeing mets?

hydrangea's picture
hydrangea
Posts: 14
Joined: Oct 2012

Due to an allergic reaction from my last CT scan w/ contrast of the chest/abdomen/pelvis in 9/2012, my urologist has requested that I now get an MRI w/ contrast of the abdomen next week for my 6 month follow-up.  I've had 4 previous CT scans w/ contrast in the past 14 months and only with the last one did I have an allergic reaction. 

I am now concerned if the MRI w/contrast is as good as the CT scan w/ contrast for detection of any changes and/or mets.  If it is why does the CT scan seem to be preferred. Prior to my allergic reaction to the CT scan w/ contrast I was under the impression from discussions with doctors that the CT scan was favored as it showed clearer more precise images (esp. of the kidney).  Another concern is then when the MRI w/contrast was requested, the doctor did not request the chest.  Do I just forget about the chest & pelvis now and just go with abdomen only?  This is a question I will ask at my appointmen when I receive the results from this MRI.

Could one of the reasons that CT scans are preferred be due to the cost of the MRI being more expensive than the CT scan?

 

 

 

todd121
Posts: 515
Joined: Dec 2012

I thought I heard the MRI machines aren't as readily available, and also more expensive.

I would want my chest done for follow ups. Lungs are often a site of first spreading in metastasis. If they won't scan the lungs, I would at least have an xray of the lungs. Or what about a CT without contrast?

My scans are being done on CT without contrast of lungs, abdomen and pelvis. Because I can't have the contrast due to my creatinine level too high. My doctor said at levels at or above 1.5 he wouldn't risk the contrast.

Todd

Digger95
Posts: 59
Joined: Jun 2010

I've had both CT and MRI scans during my annual follow-up exams over the past 12 years, depending upon which one my insurance would cover at the time.  I'm sure MedScanMan will come along here shortly to provide his expert point of view, but from what I understand a CT scan with contrast is pretty much the gold standard.  Regarding the radiation dosage, a full abdominal CT does zap us pretty good, but the risk/benefit ratio is still pretty good.  

I look forward to reading the responses to this thread as well.

NewDay's picture
NewDay
Posts: 170
Joined: May 2012

After my creatinine coming back high on several blood tests, I was told I could not have CTs with contrast.  When I was getting ready to go to NIH, I practically begged for an MRI because I thought I had read that the MRI contrast was not harmful to the kidneys like the CT contrast. They told me they could possibly hydrate me well before and after or give me a half dose.  When I got there and my creatinine was still 1.9, they would not allow me to get the contrast on the CT or MRI, not even with hydration, not even a half dose.  So, it appears I'm stuck with having scans with no contrast.  Does anyone here know about the safety of contrast used with MRI's?  I was surprised and disappointed.

 

Kathy

Texas_wedge's picture
Texas_wedge
Posts: 2807
Joined: Nov 2011

Kathy, you're capable of being forthright with your docs when the occasion arises and I think this is one such occasion.  It seems unlikely that you would respond adversely to both iodine and gadolinium based contrast media but perhaps highish creatinine is a contraindication for both because of the load on the kidney?  I think you should press them to explain their reluctance, after, perhaps, doing a bit more research on MRI contrast.

What is your eGFR running at now and how is your weight?  I presume both your GI issues and your actual histology are still shrouded in mystery?

Texas_wedge's picture
Texas_wedge
Posts: 2807
Joined: Nov 2011

Mike, generally CT outscores MRI and is less expensive, but neither is perfect.  The different scanning modalities all have things they're better at and things they're not good for.  You're young so radiation becomes a little more of an issue but consider these facts:  the latest generation of PET/CT scanners emit a lot less radiation than older machines;  your scans will become less frequent if you are NED and if you aren't the cost /benefit ratio favours early detection at the putative cost of extra radiation; the risks from the contrast dye are, these days, more of a concern than the radiation (but with appropriate care and emergency backup equipment in place shouldn't worry you until such stage as you should have an allergic reaction).

Rather than give a half-baked comment on the respective merits of CT and MRI, I'll leave it to our expert Jeff to do so but I know that Jeff is very busy currently and so may not come on for a while to answer queries.  Fortunately there's no urgency in your case and it's worth waiting to get an expert's analysis.  If you want to search a bit on these threads, you'll maybe find that Jeff (MedScanMan ) has already given all the info you need.

NewDay's picture
NewDay
Posts: 170
Joined: May 2012

Hi Tex,

My eGFR is 29.  At NIH, they were adamant that I needed to see my Nephrologist so I did last week.  He is not alarmed reminding that we had already discussed that my creatinine was elevated prior to the Nephrectomy and it is  normal for it to increase after.  He said a women my age and weight with two healthy kidneys should have a eGFR around 80.  He is not alarmed and will continue to keep and eye on it.  They had told me at NIH that it would take about a month to get the pathology results and I know they got the slides from Emory on Feb 15th, so I'm resisting the urge to call and will wait until the 15th.  The genetic testing was to take a couple of months.

As to my general health status, there is good news and bad news.  None of this is RCC related, so feel free to skip the rest of this if you want.

 

The REALLY good news is that I have lately been working a little solid food back into my diet and so far have only had a little discomfort, not what I would call pain.  When I tried the gluten free diet for a couple of weeks, I was still getting pain so gave up.  I probably should have given it more time.  I am optimistic that the pain issue may be resolving itself.  The early satiety, however has not changed and the challenge is that the volume of solid food I can eat has less calories than I can get from ensure, so when I try eating solid food, I end up losing weight.  I can't remember if I mentioned this on another thread, but after my second gastroenterologist performed my third endoscopy, she said she was prescribing an appetite stimulant and said she thought my pain was due to depression.  First of all, I felt she did not even listen to me when I had told her my appetite was fine.  I was hungry.  Food looked, smelled, and tasted good.  I just could it very little due to gastroparesis and it resulted in pain.  So, what is the piont of an appetite stimulant?  To increase my cravings for food I can't eat?  The pain coming from depression is a copout.  I know that isn't the case.  It is the other way around, The pain is causing depression.  So, I give up on investigating that and work at just trying keep my weight stable (hard work).

 

The bad news is that my syncope and dizzy episodes are becoming more frequent.  I have had five or six episodes in the last year.  In the cases where others present have called an ambulance, I am told by the witnesses present and by the EMT's that I was extremely pale - even gray, extremely cold, and they could not get a radial pulse and I had extremely low blood pressure.  The last episode a couple of weeks ago was the worst.  I had taken my dog to the vet and while waiting in the examining room, I started feeling very ill and a few minutes later passed out.  I came to just as the EMT's arrived and I started announcing I was OK because I didn't want another pointless trip to the ER, but passed out again.  I'm told I came to again but don't remember it and when they stood me up to put me on the stretcher, I passed out again.  But, as has been the case with each episode, once I get to the hospital, I have returned to normal and the doctor just kind of shrugs his shoulders and says I was probably dehydrated.  I have now had to get a letter from my doctor allowing me to get permission to park in the special parking spots in the lower parking lot at work because I can no longer make it to the upper parking lot because I am so weak.  So, I mentioned all of this to the Nephrologist when I saw him.  He said my bloodwork showed I am anemic, but not enough to explain the syncope.  He does not understand why a woman my age would not be absorbing iron, but he did send me for a couple of iron infustions.  My red blood cell and white blood cell counts have been low for the last few months, but nobody has been concerned.  The nephrologist commented that it was curious why my white blood cell count is so low.  So, he promised he would run tests and give me an answer better than just "you were probably dehydrated".  He did order a lot of blood tests and we will see what we learn from that next week.

 

My biggest fears have shifted from cancer and weight loss and pain to fearing I will pass out while driving without enough warning to pull over.  I have gotten very dizzy and pulled over and even sat on the side of the expressway for an hour and a half.  The episodes while driving have, so far, not reached the point of actually passing out, but it is only a matter of time.  I started feeling REALLY bad at work yesterday.  I know I'm going on and on about something not appropriate to this board because it has nothing to do with cancer, but it might be theraputic just to unload it.  I'm just at my wit's end and feel like, until now, I have not been able to get doctors to take my problems seriously.  We will see what develops this week, cross our fingers and hope I don't get fired because it is hard to functon at work, and, more imprtantantly don't pass out while driving and take a few innocent people out with me.

 

End of rant (for now)

 

Kathy

Texas_wedge's picture
Texas_wedge
Posts: 2807
Joined: Nov 2011

Just a passing thought, Kathy.

So sorry you've got so much to be concerned about and hoping they crack the sycope nut soon.  I suppose the low BP is an integral part and might call for continuing medical management?

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