How accurate are MRI scans? possible false result on liver tumour? magnetic resonance imaging / radiology accuracy ?

[leeteeh]

ive previously posted about an ultrasound of my liver detecting NAFLD and a tumour, I had an MRI scan of my liver and was told they couldn't see the lump on the MRI so they are not worried. my concern is if that may be a false result? is it common or easy to have false results on MRI scans or for it to miss something?
the growth was on the right side of my liver and the results of the MRI didn't show any lump on the right side of my liver, they did find a smaller sized cyst on the left side that they aren't bothered by.
I refused gadolinium contrast dye and the MRI machine was a 1.5 T or Tesla which ive read is the weakest so im curious if that could be a factor for a false result. I dont want to have this in the back of my mind so I want to accept the clear result but I have a hard time trusting drs especially in this circumstance where it shows a 11mm growth on the ultrasound but nothing on the MRI that sounds strange to me. I'd hate to accept these possible false results and it be something deadly that becomes a future issue.
Im in the UK and paid to have the scan privately instead of waiting. now I wish I would have waited to have the scan done by NHS because Im sure they use 3 T / Tesla MRI machines at NHS hospitals as they are much much larger than the 1.5 T / Tesla they used at the private hospital, the issue is now Ive had a scan on the 1.5 T every Dr is accepting those results and will not refer me for a second MRI privately or with the NHS so Im pretty certain I wont be able to get a second scan done with a stronger 3T / Tesla MRI machine in hopes for a more certain result.
any Magnetic Resonance Imaging techs or Radiologists or anyone with more knowledge on this topic able to give me some insight?

 

[Ras]

Of the two modalities, ultrasound is more prone to artifacting (i.e., showing stuff that isn't there) and false-positives. I trust it less.

There is no need to use gadolinium to see if something exists. Gadolinium only changes the T1 relaxation rate of fluid, which can suggest diagnoses to a Radiologist, but it will not make something visible that would have been invisible on a non-contrasted study. Accredited facilities will use a standardized range of imaging sequences for every type of procedure, so that tissues and pathologies are well-differentiated in every exam. I would never accept gadolinium contrast, and trust me: the Technologist doesn't feel like consenting, sticking, and injecting you.

Of the two magnet strengths, a 1.5T is weaker than a 3T, but it is not as weak as an MRI magnet can be. Open magnets are the weakest, and suffer from the worst image quality; these are not used for abdominal imaging. A 1.5T is better for certain things, as a 3T is prone to certain artifacts (e.g., chemical shift), but a 3T is better suited for some imaging. At my facility, we use the 1.5T and 3T for abdominal imaging, but a 3T is better for fine detail and for patients that struggle holding their breath or for machines without respiratory gating.

Eleven millimeters is very small, but it is unlikely to go unrecorded, whether your scan was on a 1.5T or a 3T. Radiologists will not suffer non-diagnostic imaging with blurry, fat slices, except in extenuating circumstances, so both the 1.5T and 3T protocols will be optimized for image quality in the interest of study time and patient compliance. So, even though eleven millimeters is very small, it most likely would be visible on a 1.5T scan. The 1.5T imaging may lack detail the 3T would have provided, but for a simple fishing trip (i.e., "Is something there?"), a 1.5T is adequate. If the exam was non-diagnostic, because the slices were too fat and the detail too low, the Radiologist would dictate as much.

Your more realistic issue is that a Radiologist missed the mass. I can't speak for the facility at which you got your scan, but at those facilities at which I've worked, Radiologists read very quickly. In the United States, Radiologists are paid a salary that has performance standards applied which affect their final pay. These standards evaluate their reads based on RVUs. Radiologists want to read the fewest, simplest studies that are worth the most RVUs in the least time. If you could see a Radiologist read uninhibited, you'd be shocked at how quickly they skim through the images to fire off a dictation. Howbeit, you'd also be impressed at the details they record, at that speed. Nevertheless, they do miss things. This study is a humorous, realistic, and alarming example. Many times I've had to hand-hold a seasoned Radiologist through the most mundane technological task that required them to find a certain, obvious thing on the screen. I am always surprised at how they can see a hairline fracture on a shadowy x-ray, but miss an obvious thing in their software.

 

[leeteeh]

Of the two modalities, ultrasound is more prone to artifacting (i.e., showing stuff that isn't there) and false-positives. I trust it less.

There is no need to use gadolinium to see if something exists. Gadolinium only changes the T1 relaxation rate of fluid, which can suggest diagnoses to a Radiologist, but it will not make something visible that would have been invisible on a non-contrasted study. Accredited facilities will use a standardized range of imaging sequences for every type of procedure, so that tissues and pathologies are well-differentiated in every exam. I would never accept gadolinium contrast, and trust me: the Technologist doesn't feel like consenting, sticking, and injecting you.

Of the two magnet strengths, a 1.5T is weaker than a 3T, but it is not as weak as an MRI magnet can be. Open magnets are the weakest, and suffer from the worst image quality; these are not used for abdominal imaging. A 1.5T is better for certain things, as a 3T is prone to certain artifacts (e.g., chemical shift), but a 3T is better suited for some imaging. At my facility, we use the 1.5T and 3T for abdominal imaging, but a 3T is better for fine detail and for patients that struggle holding their breath or for machines without respiratory gating.

Eleven millimeters is very small, but it is unlikely to go unrecorded, whether your scan was on a 1.5T or a 3T. Radiologists will not suffer non-diagnostic imaging with blurry, fat slices, except in extenuating circumstances, so both the 1.5T and 3T protocols will be optimized for image quality in the interest of study time and patient compliance. So, even though eleven millimeters is very small, it most likely would be visible on a 1.5T scan. The 1.5T imaging may lack detail the 3T would have provided, but for a simple fishing trip (i.e., "Is something there?"), a 1.5T is adequate. If the exam was non-diagnostic, because the slices were too fat and the detail too low, the Radiologist would dictate as much.

Your more realistic issue is that a Radiologist missed the mass. I can't speak for the facility at which you got your scan, but at those facilities at which I've worked, Radiologists read very quickly. In the United States, Radiologists are paid a salary that has performance standards applied which affect their final pay. These standards evaluate their reads based on RVUs. Radiologists want to read the fewest, simplest studies that are worth the most RVUs in the least time. If you could see a Radiologist read uninhibited, you'd be shocked at how quickly they skim through the images to fire off a dictation. Howbeit, you'd also be impressed at the details they record, at that speed. Nevertheless, they do miss things. This study is a humorous, realistic, and alarming example. Many times I've had to hand-hold a seasoned Radiologist through the most mundane technological task that required them to find a certain, obvious thing on the screen. I am always surprised at how they can see a hairline fracture on a shadowy x-ray, but miss an obvious thing in their software.

thank you for the detailed response. this is the information provided why the dr from the ultrasound. I dont have the findings of the MRI yet sent to me.
"the liver is of normal shape and size, with a smooth outline, the liver is of increased echogenicity in keeping with fatty infiltration. there is subtle, 13mmx9mm focal, well circumscribed, heterogeneous area within the anterior right lobe. no vascularity. aetiology includes focal fatty sparing, however due to the location a focal lesion cannot be excluded" so its 13mmx9 not 11 my mistake. everything else with kidneys, speed, pancreas and duct are normal it says.
would this information make your response to my original post any different ?

 

[Ras]

would this information make your response to my original post any different ?

It doesn't change my response.