Siemens PET Scan-MRI Combo Gets FDA Clearance

[Agloco]

PET/MRI machines win FDA approval!! Great news for patients, clinicians and physicists alike.

http://online.wsj.com/article/BT-CO-...10-709151.html

Can't wait to get my hands on one of these new toys.....

http://coolmristuff.wordpress.com/20...etmri-scanner/

[Wild Cobra]

Back in 1993, I had a temporary job at Oregon Health Sciences University, at the Electronics/Audio Visual department. Simple job, taping heart transplants and other surgeries and running the equipment for lectures. There was a lecture one guy gave where I ran the equipment. It was about the new high resolution MRI's at the time. Pretty interesting, but I'm sure it means much less to me than it would you.

I've worked on some types of Seimens automation equipment. Pretty solid stuff.

[Agloco]

Back in 1993, I had a temporary job at Oregon Health Sciences University, at the Electronics/Audio Visual department. Simple job, taping heart transplants and other surgeries and running the equipment for lectures. There was a lecture one guy gave where I ran the equipment. It was about the new high resolution MRI's at the time. Pretty interesting, but I'm sure it means much less to me than it would you.

I've worked on some types of Seimens automation equipment. Pretty solid stuff.

Yeah, Siemens products are some of the best we work with. Consistent quality.

There are some interesting challenges regarding the fusion of radiology and nuclear medicine imaging modalities such as these. You mentioned high res MRI scans. We've been working on improving pulse sequences to give us better resolution, SNR, contrast, etc. Today on our high res anatomic scans, we can achieve an in-plane resolution of about 150 microns. The limiting clinical factor with MRI? Time. It just takes so damn long to do a high res scan. And with all of the different imaging permutations available, a scan can get quite lengthy.

Nuclear medicine has long had a reputation as being "Unclear Medicine". The primary reason for this contrasts with MRI. In a PET scan, we use positron emitters which interact with tissue and produce photons which we then detect. Unfortunately, the resolution of these scans is fundamentally limited by positron physics and detector geometry to a resolution of about 3mm for clinical scans. Creating a hybrid unit will allow both to be registered accurately and this is the primary benefit.

So what does that mean for fusing these two into a single unit? Well, the primary challenge is the design of the PET detectors. In a hybrid unit, they'll be exposed to a perturbing magnetic field. The material that most detectors are composed of today are resistant to MR artifacts, but the hardware after that is not. Detected photons are converted to electrons in a photomultiplier tube (PMT). If you remember basic physics at this point, you realize the issue. So what's to be done? Do we use avalanche photodiodes (APDs)? Do we shield the PMTs? Standardization of design is going to be key though. And, it should be much faster than doing each alone which is good given the length of MRIs already.

This paper outlines some of the technical challenges awaiting us:

http://ukpmc.ac.uk/articles/PMC29345...479D7D4F5.jvm1

[tlongII]

It's nice to know that your pet will now be able to get an MRI!

[boutons_deux]

Have the figured out how to prevent gadolinium from causing nephrogenic systemic fibrosis or other kidney damage? or another contrast agent?

[Wild Cobra]

Have the figured out how to prevent gadolinium from causing nephrogenic systemic fibrosis or other kidney damage? or another contrast agent?

Can't it be flushed out with Prussian Blue?

[boutons_deux]

The first side effects of gadolinium were discovered in 1997; since then, more than 1,000 cases have been diagnosed worldwide. A recent Yale report stated that 95 percent of people suffering from NSF/NFD had undergone an MRI involving a gadolinium-based contrast agent. All known cases of the disease involve patients suffering from severe kidney dysfunction.

Nephrogenic systemic fibrosis / Nephrogenic fibrosing dermopathy (NSF/NFD) causes fibrosis of the skin and connective tissues throughout the body. Patients may experience skin hardening, which leads to decreased mobility of the joints. NSF/NFD can also affect the diaphragm, thigh muscles, lower abdomen and lung vessels. The disease may lead to severely restricted movement, breathing troubles and, in some cases, death. There is currently no consistently effective treatment for nephrogenic systemic fibrosis / nephrogenic fibrosing dermopathy (NSF/NFD).

The symptoms of these gadolinium side effects can appear relatively quickly following a single procedure or can take over a year to present. Common symptoms of NSF/NFD include:

Burning, swelling, itching and hardening of the skin.
Reddened or darkened patches on the skin.
Raised yellow spots on the whites of the eyes.
Inability to properly straighten the arms, hands and legs.
Muscle weakness.
Deep hip bone or rib pain.

http://www.levinsimeskaisergornick.c...um-nsfnfd.html

=========

A read where there is a protocol that nearly eliminates NSF, but as with many medical treatments, it's a roll of the dice whether you'll come out ok, or damaged, or dead.

[ashbeeigh]

The day doctors/nurses/techs/whatever figure out how to make that ty dye hurt less when they put it in my arm will be the day I cheer for the advancement of MRIs.

[Viva Las Espuelas]

Boutons with the goods

[Agloco]

Can't it be flushed out with Prussian Blue?

No, it's used for Cesium and Thallium poisoning. There are new experiments using Gd doped Prussian Blue nanoparticles as contrast agents though:

http://etd.ohiolink.edu/view.cgi/Sho...kent1275612500

The first side effects of gadolinium were discovered in 1997; since then, more than 1,000 cases have been diagnosed worldwide. A recent Yale report stated that 95 percent of people suffering from NSF/NFD had undergone an MRI involving a gadolinium-based contrast agent. All known cases of the disease involve patients suffering from severe kidney dysfunction.

Nephrogenic systemic fibrosis / Nephrogenic fibrosing dermopathy (NSF/NFD) causes fibrosis of the skin and connective tissues throughout the body. Patients may experience skin hardening, which leads to decreased mobility of the joints. NSF/NFD can also affect the diaphragm, thigh muscles, lower abdomen and lung vessels. The disease may lead to severely restricted movement, breathing troubles and, in some cases, death. There is currently no consistently effective treatment for nephrogenic systemic fibrosis / nephrogenic fibrosing dermopathy (NSF/NFD).

The symptoms of these gadolinium side effects can appear relatively quickly following a single procedure or can take over a year to present. Common symptoms of NSF/NFD include:

Burning, swelling, itching and hardening of the skin.
Reddened or darkened patches on the skin.
Raised yellow spots on the whites of the eyes.
Inability to properly straighten the arms, hands and legs.
Muscle weakness.
Deep hip bone or rib pain.

http://www.levinsimeskaisergornick.c...um-nsfnfd.html

=========

A read where there is a protocol that nearly eliminates NSF, but as with many medical treatments, it's a roll of the dice whether you'll come out ok, or damaged, or dead.

First, Gd isn't necessary in order to perform an MRI scan. It helps in certain diagnoses, but it's not given to every patient coming in for an exam. There's a large investigation into what is going on with the contrast agent. You see, Gd is only toxic if it separates from it's chealate (DTPA). That's the worry: How well characterized is the in vivo stability of the Gd-DTPA complex? Is there a process in the circulation that contributes to it's breakdown (like say Hoffman degradation does for some anesthesia agents).

~80 cases/yr is a lot. Overall incidence is about 1 in 100000 though this creates much more press than Iodine based reactions since it's much more damaging to the body.

As for a protocol, are you referring to medical treatment or an MRI protocol. Medically, you can do a few things like steroids or photophoresis. Newer MRI pulse sequences are geared towards creating intrinsic contrast utilizing susceptibility imaging like Arterial Spin Labeling (ASL) or Blood Oxygen Level Dependent (BOLD) imaging.

The day doctors/nurses/techs/whatever figure out how to make that ty dye hurt less when they put it in my arm will be the day I cheer for the advancement of MRIs.

Sorry Ash, it's gotta be bolused in order to be imaged correctly. The acquisition window is a narrow one and accurately quantifying things is tricky. Hopefully the next generation of contrast agents wont be as uncomfortable.

Boutons with the goods

Yeah, he might put me out of a job if he keeps it up.

EDIT: Typed kidneys instead of body. Corrected.

[mrsmaalox]

A read where there is a protocol that nearly eliminates NSF, but as with many medical treatments, it's a roll of the dice whether you'll come out ok, or damaged, or dead.

"All known cases of the disease involve patients suffering from severe kidney dysfunction."

Well I'd venture to say that it's a roll of the dice whether you'll come out ok, or damaged, or dead, even without gadolinium, if you have severe kidney dysfunction.

A patient with normal kidney function will most likely not have a problem excreting the gadolinium.