tag:blogger.com,1999:blog-1592992209402300549.post2851907808363358551..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: Enginerds - For The UnfamiliarSiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1592992209402300549.post-2637395624850002132014-03-24T00:42:23.456-04:002014-03-24T00:42:23.456-04:00The energy from the RF coils in a magnet is defini...The energy from the RF coils in a magnet is definitely not insignificant. All modern machines require a weight be input as part of the process so that inherently programmed safeguards in the software can limit the energy input. A good but not perfect process. As an aside people with tattoos that have ink with lots of metallic content can absorb enough RF to get real skin burns.....prison tattoos that use iron filings/rust are highly susceptible to this issue.<br /><br />As for Raymond Damadian he did not "invent" NMR.....he did however discover that using the technology behind NMR allowed for the differentiation between different tissue types with a high degree of specifity. This phenomenon which he realized just as modern computing was becoming available and affordable allowed engineers to take the fundamental principles being learned in creating cross sectional images in CAT scanning and apply it to machines that collect data from RF signals used on tissues in a magnetic field....and voila MRI was born.Dannoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-58484493693346127062014-03-23T05:24:50.780-04:002014-03-23T05:24:50.780-04:00Concerning MRIs: I'm not claustrophobic, but o...Concerning MRIs: I'm not claustrophobic, but on the one and only occasion I had to get one, the damned thing very nearly cooked me. I don't know of anyone else who's ever had that reaction.<br /><br />Apropos of MRIs, Damadian had <b><i>nothing</i></b> to do with the development of Nuclear Magnetic Resonance Imaging. The entire development of the procedure belongs to Nobel Laureate Dr. Paul Lauterbur, during his years at SUNY Stony Brook -- and I know this for a fact, because <b><i>I worked on the project with him.</i></b><br /><br />Damadian has been trying to appropriate Lauterbur’s accomplishment ever since.<br />Francis W. Porrettohttps://www.blogger.com/profile/05862584203772592282noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-44247199779947726122014-03-23T02:26:26.777-04:002014-03-23T02:26:26.777-04:00Numbness and tingling are symptoms of paresthesia....Numbness and tingling are symptoms of paresthesia....not at all uncommon as we age and gravity has it's way with our spines. An MRI is the single best method of determining if there is a structural defect compressing a nerve root from the spine or in the case of the lower lumbar the Cauda Equina. <br /><br />And the loud knocking noises in an MRI are the sounds of the gradient coils that produce the RF signal that causes the hydrogen atoms in your body to shift out of and back into precessional alignment with the <br />magnetic field that is aligned along the axis of the magnet bore. It takes a fair amount of energy to create enough RF to cause the atoms to respond....this causes the coils to heat up and cool down which is where the noise comes from. The variation in the noises are determined by machine settings that involves which coils are energized.....this determines which image plane is visualized....and for how long they are energized. The physics behind signal creation and acquisition is complex but relatively straightforward. Where it gets really complex is the 2D and 3D Fournier calculations used to translate signal data into pixels on an image that represent signal intensity.Dannoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-39081822005392279782014-03-22T23:12:03.649-04:002014-03-22T23:12:03.649-04:00It certainly seems that meralgia paresthetica woul...It certainly seems that meralgia paresthetica would be the name for what's going on. Fits it quite well. <br /><br />The PT was somewhat uncomfortable with making zero progress, but after various things, she'd have me stand around and stay still to see if the onset was always the same delay. It was. <br /><br />DrJim, my GP has already referred me to a neurosurgeon. Probably will see him next month. <br /><br />It's probably residual from getting hit by a pickup truck while riding my bike, back in 1999. <br /><br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-22893811771286196302014-03-22T23:01:53.998-04:002014-03-22T23:01:53.998-04:00I've got the same thing, but in my right thigh...I've got the same thing, but in my right thigh.<br /><br />I have a referral to the neurology department, and have to get some X-rays and ultrasound scans done to pin it down.<br /><br />My Doctor thinks it's a pinched nerve somewhere, so we're going to start as soon as this nutty work schedule I'm on settles down.drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-4166163296257785272014-03-22T22:33:44.105-04:002014-03-22T22:33:44.105-04:00look up meralgia parestheticalook up meralgia parestheticaAnonymousnoreply@blogger.com