CAT scans vs MRI scans

[WilliamTheIrish]

Originally Posted by Monticore

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.

[Monticore]

Originally Posted by WilliamTheIrish

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.

[WilliamTheIrish]

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?

[Monticore]

Originally Posted by WilliamTheIrish

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?

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.

[SupDock]

Originally Posted by WilliamTheIrish

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?

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.

[SupDock]

Originally Posted by Monticore

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.

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.

['Hamas' Jenkins]

Originally Posted by SupDock

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.

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.

[SupDock]

Originally Posted by 'Hamas' Jenkins

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.

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.

[Monticore]

Originally Posted by SupDock

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.

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.

[SupDock]

Originally Posted by Monticore

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

['Hamas' Jenkins]

Originally Posted by Monticore

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.

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.

['Hamas' Jenkins]

Originally Posted by SupDock

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

An excellent point.

Originally Posted by SupDock

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

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.

[Monticore]

Originally Posted by SupDock

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.

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.

[SupDock]

Originally Posted by Monticore

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.

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.

[Monticore]

Originally Posted by SupDock

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.

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.