Diffusion MRI?

Men's health
1

Hi all,

I'm hoping some of you will be able to explain what diffusion MRI is. I'll try not to repeat myself too much, I have a couple of other posts on this forum regarding my partner. Anyway, he is due to have his 3T MRI scan next Wednesday. However, we don't think the diffusion is being carried out. We did ask but the receptionist wasn't sure. What I really want to know is if it is just a straightforward 3T scan will this give good enough clarity? We don't really know what diffusion is apart from it being something to do with cell density. Is it something that is likely to be routinely carried out during a 3T? We want to have the best tests available before proceeding to biopsy. We know they won't be using a contrast dye as they said it isn't necessary for prostate imaging. I'm hoping someone can help me with this. Thank you.

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wish I could help.  Good luck to your partner and you.

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Hi Caz,

It is super important that the place that produces the images are experienced with prostate imaging. Prostates are very difficult to get good images of unless the MRI is used properly. Current best MRI is the 3T machine, which is better at MRI images of the prostate without using internal 'coils'(common one was the T2 MRI endorectal coil, placed in the anus while imaging) 3T machines do not need this internal coil, but often use an external cage coil.

When you get a 3TmpMRI, the images come in several varieties, the most common are T1 and T2 weighted images. Often a cage coil is placed on your hips during the entire MRI to help with the image focus. There are usually a few other usual enhancements:

DCE, being Dynamic Contrast Enhancement, A contrast material is injected to see the prostates take up of fluids, the contrast(dye) helps make the prostate image much clearer. The contrast is usually Gadolinium, which most people do not have an allergy for, and is injected for the last 30 minutes or so of the MRI..

DWI, being Diffusion Weighted imaging, which is another way of measuring the image through ADC, Apparent Diffusion Coefficient. A very technical term saying the images are compared with different ratios applied.  

My 3TmpMRI included all four of these images calculations. I specifically chose a radiologist who specialises in images for the specialist and research centres. Good images require a highly trained technician to produce the images, and an experienced radiologist to read the images.

Talk to your urologist and or other MRI centres about their prostate MRI images and what images they will provide. Unless the images are top notch, they may not be useful.

Hope this helps.

​Geoff

 

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Diffusion-weighted MRI imaging is part of multiparametric MRI imaging mpMRI, which is the current technology to distinguish significant PCa from insignificant PCa with high accuracy.  Without diffusion-weighted imaging it’s not mpMRI and the imaging will only poorly be able to distinguish significant from insignificant PCa.  This is all explained in a 55-page article published by the American College of Radiology available online by searching for:  PI-RADS v2

 I copied only the first few paragraphs of that article’s INTRODUCTION, below:

[Sub-title] Prostate Imaging and Reporting and Data System: Version 2

INTRODUCTION

Magnetic Resonance Imaging (MRI) has been used for noninvasive assessment of the prostate gland and surrounding structures since the 1980s.  Initially, prostate MRI was based solely on  morphologic assessment using T1-weighted (T1W) and T2-weighted (T2W) pulse sequences, and its role was primarily for locoregional staging in patients with biopsy proven cancer.  However, it provided limited capability to distinguish benign pathological tissue and clinically insignificant prostate cancer from significant cancer.

Advances in technology (both in software and hardware) have led to the development of multiparametric MRI (mpMRI), which combines anatomic T2W with functional and physiologic assessment, including diffusion-weighted imaging (DWI) and its derivative apparent-diffusion coefficient (ADC) maps, dynamic contrast-enhanced (DCE) MRI, and sometimes other techniques such as in-vivo MR proton spectroscopy.  These technologic advances, combined with a growing interpreter experience with mpMRI, have substantially improved diagnostic capabilities for addressing the central challenges in prostate cancer care: 1) Improving detection of clinically significant cancer, which is critical for reducing mortality; and 2) Increasing confidence in benign diseases and dormant malignancies, which are not likely to cause problems in a man’s lifetime, in order to reduce unnecessary biopsies and treatment. 

Consequently, clinical applications of prostate MRI have expanded to include, not only locoregional staging, but also tumor detection, localization (registration against an anatomical reference), characterization, risk stratification, surveillance, assessment of suspected recurrence, and image guidance for biopsy, surgery, focal therapy and radiation therapy. 

In 2007, recognizing an important evolving role for MRI in assessment of prostate cancer, the AdMeTech Foundation organized the International Prostate MRI Working Group, which brought together key leaders of academic research and industry.  Based on deliberations by this group, a research strategy was developed and a number of critical impediments to the widespread acceptance and use of MRI were identified.  Amongst these was excessive variation in the performance, interpretation, and reporting of prostate MRI exams.  A greater level of standardization and consistency was recommended in order to facilitate multi-center clinical evaluation and implementation.  

Harvey in Southern California.

I had an mpMRI in Jan, 2015, in Thousand Oaks, California, after a scary leap of PSA from 8.5 to 14.  The reading came back as PI-RADS 2 (out of 5), which is: Low (clinically significant cancer is unlikely to be present), so I had no biopsy taken.   A month later my PSA zoomed back down to 8.5, where it has remained since, approximately.

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Interesting. Harvey is that your baseline PSA?

Geoff

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FWIW,  a contrast dye was used when I had my 3TMRI scan to see if there was PCa.

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Geoff, My PSA in 1999, the first time I had a PSA test, was 6.2.  I then had a 10-core random biopsy that were negative.  Five years later, my PSA rose to 8, and I had another 10-core random biopsy that was negative.  Six months later PSA dropped back to 6.2.  From then, it slowly rose to 8.3 in 2014, with a few peaks up to 9.2, that fell back.  Then, in Nov, 2014, it zoomed up to 12.5, when i began my research into mpMRI.  In January it continued to rise, to 14.70.  After my negative mpMRI also in Jan, 2015, PSA fell back to 9.1 in May, 2015, and fell further, to 8.8 a few months ago.  My % free PSA has steadily risen from 5% (not good) to the current 20.2% (pretty good).

Harvey

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I have emailed the clinic and they have confirmed that they carry out diffusion-weighted imaging as standard protocol in prostate 3T MRI, so we feel a lot happier now. Fingers crossed we will get the best images possible and see where we go from here. The downside is that he has not to urinate for 2 hours before the scan and last time he had to do this for a bladder scan it enlarged his prostate so much he had to get a catheter in! Don't know of any way around this, we are probably best to hang around the hospital for a while afterwards to make sure he can go ok. His burning and frequency came back with a vengeance last night, the worst since all this began 5 months ago. We just need answers now.

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Hi Caz,

Umm, strange, I had to do the opposite. Use my bladder and the MRI place gave me an enema for my bowels 1 hour before the images were taken. Their logic was this is a prostate exam and did not want any obstructions.

Geoff

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Yes Rich, the MRI place I used said they always use the contrast.My urologist said those images were pretty important.

Geoff 

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My last PSA free 8.5% and PHI 75.4% both indicate I had a high chance of prostate cancer, while the MRI said PIRAD2 (no meaningful cancer present, being Gleason 5/6- this can mean I may have Gleason 2-4, and is still too undefined to see).  Urologist thought the prostate, following the UTI, now had prostatitus, and these two blood tests may be reporting false positives. My PSA since retreated a little. 

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Geoff, Thanks.  I was unaware of the PHI until you mentioned it above.  However, as you found out, it's still not accurate enough to depend on to determine if a biopsy is necessary.  However, it's probably better than PSA to determine if an mpMRI is warranted; however, would it really make any difference in decision making of whether to have an mpMRI, or not?  A burning question I have is whether it's possible to have a significant PCa with a declining PSA (or improving PHI)?  I've never run into any discussion of that.  Personally, I'm relieved when my PSA declines and am not motivated at all to do anything.

Harvey  

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Does that clinic not follow the PIRAD assessment protocol?  Did they develop their own using DWI?  If I remember correctly, PIRAD was developed with international participation. 

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Yeah Harvey...the million dollar question...when to biopsy or not!!!

I must say I was flopping back and forth between biopsy or not after the PSA, PSA Free and the PHI both strongly suggest I have a PCa issue. I did my tests in this order, PSA,PSA Free, mpMRI,PHI.

So, If I did not have the MRI images and PIRAD report saying no significant cancer, and a slight reduction in PSA, I would have had the biopsy. My urologist said if I had not had the MRI images AND the last PSA reduction, he would have carried out the biopsy. But, his caveat is...MRI images miss 20% of significant cancer lesions. You need to "gamble" that you are not in the 20% and the blood tests are wrong.... 

But, he also said, if a PSA is reducing, it usually means no significant cancer, as a cancer will produce more PSA, even small amounts, as it grows and produce the typical upward curve graph.

Hence why in my case we have suspended PCa hunting until I get a bladder stricture resolved, and then we will resume hunting. Hopefully, my PSA is still falling, and as you say, due to the decline, it sort of stops the motivation for hunting.

Geoff

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I don't know why they are not using contrast. They seem to think that it wouln't be needed as the 3T gives a very clear image of prostate including the edges, without dye. He would be happier if they did use it. He is speaking to GP this morning and asking for a kidney function blood test as this seems to be a requirement before they inject dye in other clinics. Our centre is in a large teaching hospital and is classed as a centre of excellence so based on that we just trusted that they would do all that was necessary in order to give the best scan possible. We will ask on arrival for the contrast and see what the response is then.

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yes, that makes sense to me Geoff. I hope someone hasn't sent the wrong information to him. As for an enema, that could be a problem. They don't want us arriving till scan time exactly and we will be on route an hour before so enema definitely not practical. Hoping they can get their images regardless.

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I'm about to rack out now (navy talk), so I'm doing this from memory and I might be wrong.  However, I thought the sole purpose of the dye was to distinguish the rate of its diffusion into PCa tumor compared to normal cells, which is very different, as well as the rate of washout.  That's the DCE parameter, which is Dynamic Contrast Enhanced.   And this is one of the parameters used in the mpMRI to distinguish significant cancer from insignificant cancer or benign cells, and not to miss anything.  According to the PI-RAD document, "DCE should be included in all prostate mpMRI exams so as not to miss some small significant cancers."  

I don't believe it has anything to do with getting a clear image of the prostate or its edges.  I still don't understand.  Are they doing PIRADS mpMRI or not?  That article to which I referred spells out exactly what that is and what each parameter is.  Without use of the gadolinium (sp?) contrast material, i don't think it can be called modern mpMRI.  Why all this guessing?

Harvey

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I'm so glad to hear that your consultant said that about reducing PSA levels. My partners, on the last test about 6 weeks ago, had fallen from 9 something to 7.6. New test is being done the morning of his scan, before the scan, incase it may affect the levels. Hoping and praying it has continued to fall. Fingers crossed that yours is also continuing to fall. The difference in your urologist and ours is that ours is saying if the scan shows nothing suspicious but the level is same or higher than before he will definitely be doing the biopsy. I hope if he does go ahead with this he doesn't let infection out into the bloodstream which is our biggest concern. How does he know the prostate isn't infected??

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In the 80's I had a kidney X-Ray with contrast dye and had a reaction to it. When I needed another about six years ago at a BUPA hospital I warned them in advance about it. They said it is a very different dye we use now from at that time and it should be all right but they had a doctor there as it was done.  

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In Australia, when you book in for a prostate MRI, they say you need to be here 1 hour before the actual procedure... Check in, complete billing etc, fill out a health questionnaire, have the enema(DIY) wait 40 mins for the result, and use the toilet to make sure bladder empty, get into gown, get plastic shunt put in your arm for contrast, wait 5 mins in MRI waiting room. Actual procedure took 55 minutes. The use of contrast was for the last 25 minutes of images being taken. They stop the machine, Technician comes in the room, injects the contrast, walks out and machine restarts. A coil cage was placed on my pelvis area for the entire procedure. It was @#$% cold in the MRI room, so they gave me a heavy warm blanket. 

​Geoff