CAT scans vs MRI scans
 

Just finished the 3rd CAT scan over 6 years and now they want MRI for the first time. What differences do these these pick up? Besides I lose at least an hour.

MRI can look deeper and see small tumors.

Also can see greater layering

CT scans are like hundreds of X-rays of a cross-section of your body. When using contrast of a radio opaque dye, it can determine soft tissue abnormalities, like a pulmonary embolism.

MRI uses a magnetic field to realign polar (i.e. water molecules) back and forth. That reorientation creates an image. It's why MRI is good for assessing soft-tissue injury, like a ligament tear. Conversely, bone does not image well on MRI due to lack of water molecules.

MRI has better spatial resolution than CT. Both have their benefits.

What body part are they scanning?

Wait for it...

What Hamas said ,

But sometimes they don’t know what they want lol , I had a patient this year where I found an atypical renal lesion on ultrasound , they recommended follow up ultrasound in a few months , that ultrasound recommended a CT , the CT recommended and MRI which then recommended Ultrasound , good times.

Can you tell us what are the different types of CT scans?

I got an ultrasound done on my balls by the hottest Asian woman I have ever seen. Luckily it was nothing but that's my story. I also found 20 bucks on the ground in the parking lot.

CT generally has better spatial resolution (distinguish objects that are near to each other). MRI has better contract resolution (distinguishing similar types of tissue near each other, like tumor vs normal tissue)
A big advantage to CT is how quick it is.


A big problem with X-ray is shadowing. Meaning an object obscures objects behind it. In a CT the X-Rays rotate around the body allowing a 3-D reconstruction

I would default to Monticore, I think it's his field of expertise. I mainly know about them via their association with nuclear medicine procedures (PET/CT, PET/MRI).

I had a shoulder replacement done about 8 years ago, it needs to be replaced again but my doc said he couldn't see what ne needed to see on the MRI so he sent me for a CT. Maybe that's because of the things Hamas talked about.

His balls as he is trying to make Lewdog's Alpha list.

1) don’t listen to scho.

2) CT-as Hamas/Monti said, it’s an array of detectors moving in a circular motion using radiation. It constructs an image from those detectors. Imagine that your body is a loaf of bread. And you are able to pick the most middle slice of bread out @ as small as 1 cm, look at closely, then place it back into the loaf. Then put this slices into a series of images that a radiologist can scroll through.

Essentially, that’s what CT does. Software allows reconstruction in several planes and also, allows bone to removed from area to create and show (soft tissue and brain) images of specific areas.

Source- years at companies that engineer these scanners.

If you're claustrophobic I would suggest some valium about 15 mins before hand.

We just recently got a CT at our hospital and since I do t do x-rays anymore so my practical knowledge is still limited lol , so glad I don’t do call anymore the girls look stressed lol.

Our other ultrasound tech is pretty cute but for some reason a lot of the male patient ask for a mail tech , lucky me.

I had a girl insist on watching me scan her boyfriends balls, people are weird.

I always just take a nap during MRI's. Was in the f'ing tube for over an hour once time when they were scanning my entire spine.

Same here. Used to never bother me but about 3-4 yrs ago claustrophobia hit me out of nowhere. I've had about 4 or 5 in the last couple years, always for my ****ed up spine and always last an hour or more. 10mg valium about 15 mins before and a take a nice nap.

Prime candidate for MRI?

https://api.time.com/wp-content/uplo...1204123901.jpg

CT shows the bone and realtionship of the humeral head in the socket and the density of the bone
MRI shows the rotator cuff tendon and ligaments and bursa and the cartilage surface/labrum better

I was getting a pet scan every 3 months after my immunotherapy infusions. After the 3rd one, my insurance company started bitching about it, so now I get 2 ct scans, one upper body and one lower body every 3 months.
sec

I specialize mostly in breast ultrasounds on women between the age of 20-25 , I have an assortment of flavoured gels available, pass the word.

I like to think I’m pretty good at training for those myself.
sec

I had an MRI back in June. I was in there about 30 minutes but it damn near killed my back.

What are the advantages of MRI?
Where MRI really excels is showing certain diseases that a CT scan cannot detect. Some cancers, such as prostate cancer, uterine cancer, and certain liver cancers, are pretty much invisible or very hard to detect on a CT scan. Metastases to the bone and brain also show up better on an MRI. This imaging is also used for many purposes unrelated to cancer, including injuries to soft tissue or joints, and injury or disease of internal organs including the brain, heart, and digestive organs.

Also WilliamtheIrish can STFU.

I know as much as he thinks he does.

Schmo, shut the **** up. You’re functionally reeruned and don’t know what the **** you’re talking about.

If anybody wanted to know about imaging the inside of a trans hookers molded vagina, the board would gladly come to you as the Britannica.

Until that’s asked, eat a dick.

**** you you jealous douche.

You build scanners as an engineer so you think you a rocket scientist.

My escorts are better than what you're ****ing.
That's your pussy retort to anything I post. A one trick pony.

I know more than you tinker toy builder. Another person who thinks they know about me and what I know.

For the record scumbag, my paternal grandmother lost a breast to cancer, both grandfathers died of lung cancer, my mother died at 60 from ling and brain cancer, my father dies at 57 from liver cancer, my sister had aggressive skin cancer on her leg and had all her lymph nodes removed in her one leg, my two aunts died of cancer and one uncle died of cancer.

I've dealt with more cancers, doctors, CAT scans, MRIs, radiation, chemo than 95% of the people here.

So you can go **** yourself and take your shitty engineering degree with you blowhard.

Next he will whine and get you banned for that post.

LMAO
Furiously googling web MD to discern differences in imaging platforms makes you exactly what you are every day. A dumpy ****ing moron.

Go dive deep into a tranny, schmo.

^

Looking to be hired by schmo on a slow Friday.

And yet Irish the Blowhard ALL my posts are accurate, including my simple first two.

I'll leave the trannies for you to deal with.

LMAO

Okay schmo.

Too much alpha in this thread.

Geez, wtf. A fight over who knows more about medical scanning equipment.

In my best Rodney king voice "can't we all just get along?"

Agree. I tried some levity several posts up but it landed like a thud. Tough crowd lol

Wait...

...did I just read trash talking, "shut up engineer, in this thread about million dollar equipment that takes amazing images inside the human body... my whores are great.... ?

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LMAO

“I’ve had a hundred car crashes! My mother, 2 brothers, 7 stepchildren and 3 hired hookers died from me crashing cars.

I know more about automotive crash design than anybody”!!!

It sucks, and I went through the same thing. PET scan at the start of treatment, PET scan at the halfway point, and a PET scan two months after finishing.


PET/CT scans are preferable, as the FDG (likely the tracer they were using unless you have prostate cancer or a specicic type of neuroendocrine tumor) will localize in tumor cells due to their preferential use of glucose. And since positron emission creates an annihilation event that produces two gamma rays emitting 180 degrees from one another, you get good visualization of areas with higher glucose uptake (tumors), and a 3D field of view. From there, they just overlay the PET scan on top of the CT to gives you functionality and anatomy.

Worst part about getting an FDG scan is that you can't have carbs the day before. My first one was the day before SB XLIV. That was suboptimal timing.

Nah, bro. You're much better off using PET/CT for oncology. F18 Sodium Fluoride is also better than MRI and bone scintigraphy for skeletal lesions related to prostate and breast cancer.

PET/CT is not as readily available at least around here, for staging it is the gold standard for most CA I would assume but MRI has the advantage of not using radiation. Our CT vendor said that CT’s cause 2% of all CA in the US , didn’t fact check that but figured the guy trying to sell us his equipment would lie a bout that , doses are getting lower every year though .

CT has just become such a crutch for doctors it often over prescribed, if I have already located and sized a kidney stone or confirmed an appendicitis on ultrasound you do t really need the CT , but they still order it.

Accumulated dose is an overriding factor in medicine. About 20 years ago, I attended my first dose reduction conference. It really opened eyes about the technical factors used and taught to end users. Just after the turn of the century, end users were using a one size fits all technique. Even for children. Images were incredible. Just outstanding.
And nobody thought much about dose. Since that conference, we worked with a group from Duke University setting up pediatric weight based protocols reducing dose by 75%.

As for the 2% claim, I’d like to see what that’s based on. The risk/benefit factor plays a large role in CT usage. And yes, while you can localize a stone in renal pelvis or lower pole with US, a urologist wants to be sure it hasn’t made its way down to the UPJ or deeper before navigating a wire into the ureter and following that with a rigid scope. Or a flexible scope into the kidney. Delicate surgery, that.

I can usually see stones at the UVJ or anywhere along the tract and size will probably determine is it needs i intervention , CT might be better To R/O septic stones as U/S isn’t great for acute pyelo.

Monti,

I totally agree with you about the overuse of CT. Curious about your thoughts on that in the Canadian health system.

In US health systems, it’s (IMO) overused because of our “business model”. The more scans, the more revenue generated, the greater profit by individual health care systems. And as you know, CT/MRI generate a ton of revenue vs US. (At least in the systems in which I operate).

How does it work in your world?

The linear no threshold model suggests there is no safe dose of radiation, only increasing risk. The last info I saw suggested every mSV of radiation exposure conferred a 0.005% chance of fatal cancer. For example, my last chest CT was 10mSV, so a 1/2000 chance. It was also more radiation than I got in an entire year of working with high energy radiopharmaceuticals.

It’s getting overused a little because it’s just easy and quick , ER are packed new doctors don’t have the same clinical skills as the older ones and liability is becoming an issue up here more than ever or at least the fear of suits .

Hospitals lose money on CT up here because they don’t get a technical fee whether they are out patient or inpatient. Hospitals get a specific amount of funding per bed , the more tests you order you kinda hurt your bottom line , they make more money with empty beds.

The ordering of elective diagnostic exams on inpatient costs the hospitals a lot of money , I don’t think a patient in hospital with a broken toe ( extreme example) needs thyroid/LFTs /renal function work ups etc.

Ordering tests is just easy but it’s going to destroy our system treating patients is getting way more expensive and the funding hasn’t adjusted.

A DR asked me to do a scrotal ultrasound on someone who says he doesn’t have testes anymore because she didn’t ****ing believe him and she didn’t want to check herself , she wanted to try to figure out why he was taking testosterone.He was in hospital for a ****ing spinal cord injury ffs.

I never see US used for stones unless the patient is pregnant or Low Dose CT is not available

This is from Uptodate

Ultrasound is less accurate and demonstrates greater variability than CT of the abdomen and pelvis without contrast for the diagnosis of nephrolithiasis (image 4). Pooled sensitivity and specificity of ultrasound is 0.70 (95% CI 0.67-0.73) and 0.75 (95% CI 0.73-0.78), respectively [40]. Because CT detects nephrolithiasis not diagnosed with ultrasound, a CT is sometimes performed after a negative ultrasound to evaluate for a stone if the index of clinical suspicion remains high. Ultrasound is less accurate than CT at measuring stone size, stone number, and defining ureteral location. Thus, a positive ultrasound may lead to a follow-up CT to enable treatment planning.

Providers are using it because it’s quick and easy. Providers realistically don’t get paid more for ordering a CT scan, and I have never seen an administrator encouraging providers to order more tests to make more money for the hospital system.

It probably does happen at times, but I cant imagine that it occurs in any significant volume, and I don’t imagine many providers actually listening.

I'm too lazy to remote in to work to check UpToDate right now. Does that article list the negative predictive value of US? Just curious.

The problem with U/S is it is very user dependent tons of shitty techs out there or are expected to do things they are not qualified to do . CT has limitations as well I can see a stone in a ureterocele /UVJ but on CT it will look like it is the Bladder .

Most tech will just look for hydro and not bother going further and tracking the ureter all the way down trying to find the stone , being also an X-ray my training just wants to try and avoid this patient getting radiation so I would say I find it 90% of the time.

Just checked. Went to the source article and it wasn’t in the abstract.

I brief lit review indicates 60-80 percent negative predictive value.

My opinion is that even with a higher negative predictive value you are still left with no diagnosis.

I am thinking of a patient in the ED with flank pain and hematuria. CT just makes more sense to me.

Your point about cumulative radiation exposure is a good one though. A major bias in medicine is worrying more about a missed diagnosis than the risk of the test or procedure.

The problem is, you cannot decide if you are not seeing it because of the limitations of the study, or because it isn’t there.

Our department didn’t have a CT until recently so U/S was the go to otherwise the patient had to be shipped to another hospital, so I tried getting good at it.

I have no doubt you were very good at it. I’m sure the familiarity and determination of the performing person is very important

If you guys are passing on the trannies, can you send them my way? Been a slow month for me...

If there is hydro then it’s probably there if I can’t find it or there is another cause that would need a CT anyways , if no hydro they probably treat conservatively and follow up if patient isn’t getting better.

Why do some of y'all mother****ers push so hard :). Two of the more painful experiences I've ever had as a patient were an echo and a renal ultrasound. ****ers just dig in.

Not a lot of meat with intercostal scanning and some tech don’t give a shit.

An excellent point.

I figured the ED docs just immediately ordered ceftriaxone, gave them an outpatient script for tamsulosin, and streeted them.

...and then the nurse calls because they're trying to give a gram of ceftriaxone IM and we have to page the provider to change the route.

The most user dependent modality but also the least regulated .

Just because it doesn’t use radiation doesn’t mean it can’t cause harm but it does but the only people who use it know this and aren’t really pushing for more regulation.

ROFLROFLROFLROFLROFL


Only on CP.

There's the phrase "you're comparing apples and oranges." It's a useful phrase.

This though is like that phrase with an exponent. It's that phrase squared or cubed. It's like comparing hookers to ultrasounds....

Also, increase in dose can vary with certain radiolgist groups.

In this area, US Midwest, on ABD/ABD PELVIS scans, so many groups demand delayed imaging through the abdomen. So they inject, scan, get the series, and then wait on the order of 5 to 8 minutes and scan again diaphragm through the crest of the pelvis. And it’s done on damn near every patient. I can understand it on a trauma situation

That’s a lot of extra dose for low yield return on most patients.

Good on you for being thorough. In diagnostic X-ray and US, it’s totally dependent on the individual. I made my radiology bones 3 decades back. From darkroom processing to daylight cassette to digital. Incredible strides in a short period. CT and all that.

And it opened doors in education and employment that I never dreamed of in the beginning.