DocLightning From United States of America, joined Nov 2005, 19371 posts, RR: 58 Posted (2 years 1 month 2 weeks 23 hours ago) and read 2828 times:
Note: this is NOT an abortion discussion. Bring up the topic and I will SD.
Video MRI is a relatively new technique. MRI is typically a slow process with several minutes required to acquire a single image. Images are acquired volumetrically (the whole volume is captured in a run) and this takes time. Movement during an MRI creates "motion artefact" that can show up as blurring or echoing of the image:
With improvements in computer power and detector types, MRI can be done in real-time now (albeit with lower resolution). Because MRI involves only magnetic fields and radio waves, it does not involve any ionizing radiation (like X-rays) and so it is safe for use in pregnancy if needed. The video is here: http://www.newscientist.com/article/...-video-mri-for-the-first-time.html
To orient you, I am going to refer to "left, right, top, bottom" in terms of the frame, rather than the mother: the mother's legs are towards the top of the frame and her head is to the bottom (the twins have turned head-down). The bladder is seen as a turnip-shaped white structure just above the uterus (this is a T2, or water-enhancing sequence, in which water shows up as white and water-poor areas like bone and fat are darker). To right, just below the bladder you can see a loop of colon the right-hand fetus has the back of her(?) head to it. You can also see the motions of the mother's breathing (the video is sped up) and also flow through her femoral arteries as they course into the leg as a series of pulsatile white flashes. On the left, you can see a white line leading to the bladder, which I suspect is a ureter. To the left and just above the bladder, you can see the mother's hip joint. Right at about 0:11 you can see the left fetus swallow.
Pretty darned cool stuff, I must say. This is why I love my profession.
DocLightning From United States of America, joined Nov 2005, 19371 posts, RR: 58
Reply 9, posted (2 years 1 month 1 week 6 days 1 hour ago) and read 2407 times:
Quoting francoflier (Reply 7):
It's a cool new bit of tech, but Doc, what is the usefulness of a video MRI?
First of all, as a research tool it is useful. Second, it can be used to watch organs at work. As the resolution improves, we might be able to catch heart valves in action, track fluid flows (which can be done with short-pulses and diffusion-weighted imaging), follow labeled contrast agents (C-13, gadolinium) through arteries looking for obstructions, etc.
At present, there are only two imaging modalities that can be used to generate real-time video images: ultrasound and fluoroscopy.
Ultrasound has a number of limitations. While it can track fluid flow and relative motion (toward or away from the probe) and generate real-time images, it is a poor choice for certain types of imaging (brain [because it's surrounded by bone], perfusion studies, bone, etc.). It also works poorly in the obese patient. While it can generate 3-D images in real-time due to advances in scanning technology and computer reconstruction, fidelity . Ultrasound is fantastic for pregnancy and cardiac studies because it involves no ionizing radiation (like X-rays or gamma rays) and it can generate very good 3-D images when used in a newer scanning mode, but it's also difficult to interpret and operator-dependent. This video shows how ultrasound can be used to image the heart: http://www.youtube.com/watch?v=4vBJoWP-zBM
Fluoroscopy is basically video X-ray. This is a video of fluoroscopy (suggest you mute sound to eliminate boring music): http://www.youtube.com/watch?v=q0cKhkJk30A. Fluoroscopy cannot generate 3-D images and is limited because it can only image radiopaque structures (those that are opaque to X-ray). So, for example, if you want to image swallowing, you need to have the patient swallow a barium-laced substrate. If you want to image coronary blood flow, you need to snake a catheter into the coronary circulation (which is a very invasive procedure) and inject the tracer that way. The other problem with fluoroscopy is that it uses X-rays, which are ionizing radiation, and the dose is much higher than that for a single film.
There is some research into using high-speed volumetric CT as a video imaging modality, but this research is hampered by the excessive radiation doses delivered to the patients and so until much more sensitive detectors can be developed, this modality will probably be stalled in development.
So video MRI will enable us to image entire volumes in four dimensions (three space, one time) without the need for radiopaque tracers (although contrast agents might still be useful in some studies) or ionizing radiation. MRI magnets are expensive to purchase and to operate (think bizjet). They require liquid helium cooling, magnetic shielding, and lots of electricity, which is why even a short scan will run you over $1000, but they are very useful for a lot of different types of imaging that were once essentially impossible to obtain.
starbuk7 From United States of America, joined Apr 2008, 599 posts, RR: 5
Reply 10, posted (2 years 1 month 1 week 5 days 9 hours ago) and read 2333 times:
I could never be a doctor (can't stand the ER aspect of it mostly with the trauma injuries) and really appreciate everything that doctors do for us.
Thanks DocLightning for this link and video because I found it truly amazing to watch. My daughter had some things like this done to her when she was having extreme nausea for several months and they were trying to figure out why. We got to watch her insides work and I found that amazing as well. She had a virus and is better now after some antibiotics but the processes were truly amazing. Doctors are some truly amazing individuals.
Well, I knew I'd get an answer, and I was aware I probably wouldn't understand all of it, so thanks!
I unfortunately underwent my share of medical explorations the last few years, including MRIs (now I know where dubstep comes from), ultrasound, CT scans and more. I'm actually casually interested in these technologies, though I content myself with understanding the basic physical principles they exploit, and I know little about the stuff they're used to observe. They're also mighty impressive machines, under their cold and depressing clinical look...
Any advancement in medical science is always welcome, and I suppose it often starts with exploring the workings of the human body and its ailments.
Looks like I picked the wrong week to quit posting...
canoecarrier From United States of America, joined Feb 2004, 2838 posts, RR: 12
Reply 12, posted (2 years 1 month 1 week 3 days 4 hours ago) and read 2123 times:
Quoting DocLightning (Reply 2): Sometimes I am reminded about how I am comfortable looking at things that wig most people out. Never go to dinner with a bunch of doctors...
I wish I had the option of not having to listen into those discussions. What's probably worse, IMO is having a PICU nurse wife and a toddler. She'll come home from a shift at work and every cough or sniffle from our kid is immediately some kind rare pediatric condition.
Quoting DocLightning (Reply 9): Ultrasound is fantastic for pregnancy and cardiac studies because it involves no ionizing radiation (like X-rays or gamma rays) and it can generate very good 3-D images when used in a newer scanning mode, but it's also difficult to interpret and operator-dependent.
I had little knowledge of sonography until recently. My brother in law is now a sonographer and when the wife got pregnant I was there for every imaging session. So, I paid a little more attention to what was going on than most people, I imagine. The initial vaginal sonogram really didn't show much (to me) other than the heartbeat, but as she progressed and they were able to use other techniques it really did give an amazing picture of the fetus. However, they were well off on the expected birth weight, which I am told is normal.
That said, this MRI technique is amazing. Thanks for sharing Doc.
As I mentioned, my brother in law is a sonographer. I knew he'd know she was pregnant if we showed him the L2 image they send you back with. I told him I had to take off work and see my doctor for a knee injury. When we came back I said they imaged my knee and I couldn't understand what they said was wrong and asked him to look at the picture. There was the first look of "they must have mixed up the images" then the "WTF is this?!" and then "I'm going to be an uncle??" At 3 months our son looked like a soft boiled egg to me, but he figured it out pretty quick.
See what happens when you make a statement like this? No one wants to reply! Haha
Quick questions, do twins normally move in sync with each other in the womb? As in, will they normally go head down and so forth? Also, will this kind of technology help Dr.'s with identifying anything any faster such as potential complications and so forth or will multiple styles of scans still need to be used? I am not a woman nor really know anything about pregnancy so pardon my ignorance.