Sarah Shaves, MD, reviews the various types of imaging studies including X-ray, CT, MRI, Ultrasound, nuclear medicine and their utilities; looking at current screening guidelines and online resources available to assist the provider.
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Hello, I'm Dr Sarah Shaves with medical center radiologists. I'm a body imager and I'm going to talk to you today about imaging ordering for common patient complaints. Today we will briefly review the types of images, studies and the relative strengths and weaknesses and those patient factors that may lead you to choose one test over another. After the talk, I hope you will be familiar with current disease screening guidelines that require image ing and some new updates, and I hope that you will become more familiar with online. Resource is that can assist you in ordering the appropriate imaging study. So image ING has developed over the past century. With the original discovery of X rays by Rankin in 18 95 and his still famous first X ray of his wife's hand, she was unimpressed and clearly conflicted about his discovery, as her comment was, I have seen my death from playing films and real time fluoroscope E in the fifties. Rapid changes came in each decade with further development of nuclear medicine, ultrasound and C T interventional radiology and Marie Pet CT, and the newest directions with molecular imaging, the assistance of artificial intelligence and functional memory. Therefore, basic types of imaging first is X rays or C T, where the images created from radiation passing through the patient. In nuclear medicine, the patient is administered a small dose of a radio pharmaceutical with images created from radiation emanating from the patient. In ultrasound, we use sound waves like dolphins, do with echo location and create images from echoes that return from the patient and in memory. We use a very strong magnet and radio waves to create images from the relax ation of protons in hydrogen atoms. A single X ray is a very one dimensional view. All the structures from front to back are compressed and superimposed into one image. It's often the first best test, particularly for chest or musculoskeletal concerns, although it imparts a small dose of radiation to the patient. There are also naturally occurring sources around us all the time, including foods that we eat like radioactive bananas. Only a single view is needed to show us that this feeding tube looks like it's in the right main right lower lobe bronchus. Although truly without seeing the patient and inspecting him, it could be also lying in front of the patient or behind the patient. We really can't tell because all the structures air overlapping. Yeah, a second perpendicular view often adds very useful additional information. For instance, in this patient we see a distal into articular fracture of the radius. The carpal rows look pretty well aligned, and the bones of the hand looked normal. But it is on the lateral view that we see that the lunatic bone is actually dislocated and clearly and in retrospect, the abnormal shape of a loon. Eight On this AP view tells us the same thing, and that's a clue that there's an abnormality that's better seen on the lateral view. So perpendicular orthogonal views are often extremely useful, and they're usually recommended. SETI allows not only differentiation among tissues of different densities, but with two D and three D capabilities. We can also show relationships between structures, even adding contrast when we need thio for identifying pathologies for surgical planning and so on. Without overlapping structures, we can more sensitively detect small abnormalities like pulmonary nodules that could be obscured on an X rayed by normal structures. Earlier detection may direct earlier treatment in a disease process and make a strong impact on the patient. SETI is really the workhorse of radiology and has applications in all body parts. On playing film, we see a large patient who's bone soft tissues all look pretty normal and a bowel gas pattern that looks non obstructive, although perhaps the loops are somewhat centrally located but no dilated loops. But the seat he gives us so much more detail we can see this patient is not chubby, rather, his flanks air distended due to a large quality of a site. He's fluid, and the loops were literally floating in the fluid, and that's why they were centrally located on the X ray. We can also see his left kidney is obstructed with the delayed Neff program and dilated renal pelvis, new information that was not visible on the cave. Although providing much more information, CT also exposes the patient to more radiation and is more costly than X rays. Some patients also have allergies that preclude them from contrast administration and SETI is much more expensive than X rays. Here's another example, however, of how CT can be so useful. For instance, notice how on a single AP view of pelvis and hips we see both femoral heads projected over the asset. Tabula looks like this hip is flexed, but it is the C t, with its two dimensional information that shows that this from your head is actually behind the acid tab. Um ah. Finding we would not know on a single compressed frontal view. Memorize another modality that allows two D or three D imaging. A very strong magnet is used to together with radio waves to create images. The magnet is about 20,000 times stronger than Earth's gravitation and using natural contrast in the body with fluid sensitive sequences, we can detect things like Kolelas thesis in the gall bladder or Coley Dokle apotheosis in the common bile duct, all without using radiation. There are some issues that limited to use, however. For instance, the study typically takes longer, and some patients can't cooperate like confused patients that we're trying to do it in memory of the brain on or patients who have pain may not be able to tolerate lying in the magnet for ah, long period of time, and many exams could take upwards of an hour. Some patients also claustrophobic and cannot be positioned in the magnet, and some patients with implantable devices like cochlear implants, older pacers or medication pumps like insulin pumps cannot go into magnet and be safely scanned unless these devices can be turned off. Ultrasound is a great tool, with many indications throughout the body. Most common applications are in patients with abdominal complaints like right upper quadrant pain or screening for happiness. Senator carcinoma in patients with cirrhosis or searching for obstructive your apathy in patients with new renal failure. Also, of course, we see it all the time used in pregnant patients because there's no radiation involved and we can use it for evaluation of soft tissues. Are looking for fluid collections or looking at vascular structures like when you are concerned that your patient has a DVT ultrasound is generally cheaper than a CT or emery. It is a shorter exam, doesn't use radiation, and it's portable. Since gas and bone, however, cause significant artifact, they can limit evaluation on an ultrasound, and it's generally not useful for these structures. Here's a nice pretty example off a pregnant patient hears and vaginal probe, we're seeing the uterus. We see a little, um, fetus here and a nice round yolk sac and the Amazon. And what is really beautifully demonstrated on this study is that this is a corner will ectopic with very little biometric, um, around the gestational sac. And this represents a surgical emergency. Nuclear medicine is slightly different and has a strong emphasis on physiology. And your patient with biliary colic. An ultrasound may show Kohli death iesus, but it is the highest scan that will tell you if the cystic duct is obstructed and the patient needs a surgical consultation. Or, if you're patient, has a biliary leak. Like in this study, where we can see activity pooling around the port, hepatitis, draining out through the Jackson front drain and also with some anti grade flow into bowel as it should. An X ray may show a pathologic fracture in your patient with lung cancer, but it is the ability to admit to image the whole body with one small dose of radiation with a bone scan that could tell you if metastases air widespread, we're localized, and some agents can be used not only for imaging but for therapies like I won 31 for thyroid cancer or Bluetooth era for patients with your under consumers, diagnostic studies do expose patients to small doses of radioactive materials, so precautions must be taken. Another downside to these studies is that some of the tests have poor an atomic detail. As in this hiatus, can we can see the liver? Ah, little bit of foul, but not much else. Now I'd like to move on to discussion of current image based screening recommendations without evidence based guidelines. Clinicians, they find themselves over ordering or under ordering necessary, unnecessary tests. There could be side effects to the patient and requires a time commitment from the patient to come in for the exam, maybe has to arrange for a ride or time off from work. It could result in over utilization of resource is and certainly can drive up the cost of health care. And both clinician and patient may have to deal with fallout from false positive results or complications. Patients concern or inconvenience. There are many common reasons that people do over order. You may just want to reassure the patient. Well, you know, I'm sure it's not broken, but we'll just do an X ray just to prove it to you. That kind of thing or maybe feeling uncomfortable dealing with uncertainty. You know, we really should just watch a wait and see what happens. But you know what if and so they order people, order unnecessary tests. Or perhaps people are just unfamiliar with the best practices. Sometimes people over order because they're trying to speed up the work up. So with a patient of right upper quadrant pain, maybe they ordered the ultrasound and the CAT scan and the high to scan Um, rather than waiting for the results of one test to inform them as to whether or not additional information is needed. So there are a number of initiatives that have been developed their aimed at improving our best practices when it comes to imaging tests published in JAMA was an initiative called Less is More and published in the British Journal of Medicine. Was too much medicine on both of these air searchable on the Web The American College of Radiology has developed an initiative called Choosing Wisely to help choose good appropriate of medical tests imaging tests. They're also published guidelines. The USPS TF has guidelines not only for non imaging but imaging recommendations for your patients. The A F p Also as clinical recommendations, including imaging recommendations and the A. C R has developed a large compendium of appropriateness criteria to help you with choosing imaging studies. And then, of course, we all participate in life long learning to try and improve our clinical care. So now I'd like to turn to screening tests that require imaging. The U. S. P S T F has three areas where they recommend imaging for screening. One is lung cancer screening with low dose chest CT, and they're actually new updates from the very end of last year, and I'll go over those. They also recommend screening for Triple A with aortic ultrasound, and these recommendations were just developed in 2019, so also fairly recent. And then, of course, we have been screening patients for a long time with mammography. The U. S P S T F. Has updated its recommendations for lung cancer screening, and I have them here on the screen. They've lowered the age for screening from 55 to 50 to start screening and have lowered the exposure to cigarettes from 30 to 20 a pack years. In this way, they're hoping to pick up more lighter smokers or patients that have higher risk, like women or African Americans, and try and detect more cancers. They still have the advisement that the current that should be a current smoker or someone who has quit within the past 15 years. And they have now added, Um ah, component that states. When the patient is no longer a surgical candidate, they should not be screened. So the USPS TF lung cancer screening recommendations were modeled from the national lung screening trial. This was a randomized controlled trial and the references down here for you, where 53,000 high risk smoking patients from 50 to 74 years old who had 30 plus pack years, were screened over a three year period at 33 major medical centers and randomized to either receiving annual screening C T or screening chest X ray to look for new lung cancer. And what they found was 1000 and 60 cancers on the C T group and 941 in the chest X ray group, and the difference was significant. So they concluded that C T was more sensitive for cancer detection than chest X ray. They also found fewer cancer mortalities in the SETI Group. And so they concluded that screening with low dose CT reduces mortality from lung cancer you may have seen on the previous image. This novel here in this super segment left lower lobe certainly difficult to see because of overlapping ribs, whereas on the fall of SETI, much easier to detect now. There is controversy, however, about screening for lung cancer and the A F P does not recommend lung cancer screening. In fact, they noted that the U. S. P S T F group had many false positives. In addition to cancers, there were granulomas, other benign lesions and so on. And 40% of positive results had to have some sort of follow up with scans or interventions. And most of those have benign disease. Also, the A F P calculates in the original study that to save one person from a lung cancer death, you would have to screen 312 patients over five years with three screenings. And so they concluded that the cost to society and the radiation exposure to the population was not worth it. And so the AFP, while not recommending lung cancer screening does heavily recommend educating patients on smoking cessation. The USPS TF also recommends screening for Triple A and the A F P is an agreement with these recommendations. So Triple A screening is recommended one time for all men between 65 75 who have ever smoked so one time ultrasound during that decade. They also recommend selective screening for men 65 to 75 who have never smoked if they have strong medical history, family history or other risks or other factors that are important. There are no recommendations for women, and this is because there is a much lower risk of Triple A and women, and also women tend to be poor surgical outcomes. Here we see two views from an aortic ultrasound in our department, and we can see the proximate aortas, normal caliber and the distal aorta, his aneurysm all. And it has soft plaque on the wall as well as some shadowing calcifications. Breast cancer screening, of course, as you know, has been controversial, even though it has been going on for a long period of time. So the USPS sorry USPS TF recommends starting screening at age 50 and then screening every other year After that. The American Cancer Society disagrees and wants toe women to start screening age 45 doing it annually. The National Comprehensive Cancer Network says 40 and annually and a cog recommends 50 annually, and American College of Radiology recommends starting at 45 annually, so there is no consensus here about when to start screening. There are a lot of disagreements among these groups because of false positives of the cost of the population and individual patients. Three anxiety that could be provoked by callbacks forces for diagnostic mammograms, inconvenience that's involved and the complications of over biopsies or over treating or addressing what might be benign lesions or, um, uh, indolent lesions that may not kill, say, an elderly person on the right. Here is an example, actually, of a male breast cancer. This was a mass that was picked up on a chest C. T. Um, and we noticed this asymmetric density in a man who did have gynecomastia when he was brought in for a mammogram and then a follow up ultrasound to guide biopsy. We see a solid mass and retro really region lobby elated, heterogeneous mass on ultrasound with some ill defined borders, and this was the breast cancer. So finally, I'd like to talk about some resource is that can assist you in choosing appropriate tests. U S P S T f. In addition, Thio recommendations for all kinds of screening, like for hepatitis and and clinical recommendations, also has the imaging recommendations that I went over today, and their website is readily available online. Theeighties P also has published its screening recommendations online, and there's actually a new app that you can download on your mobile phone if you want to keep it with you to help you make those decisions. Three. American College of Radiology, Um Developed and Appropriateness Criteria, which was a set of guidelines developed by expert panels, reviewing the literature and developing a consensus about when to order tests. The appropriate is criteria lists best imaging exams for specific All I'm sorry specific medical conditions, and it's also free and online. And the symbol here is what you'll see when you look online, uh, and search for it on your search engine. You type a CR appropriateness criteria, and you'll have free access here to a list of topics and disease processes. So, for instance, another way of searching is to type in a Google search or your own search engine. A CR appropriateness criteria. Let's say abdominal pain. You have a patient with abdominal pain. So if you go to this link and click on the link, what you will see is a list that asked you, is your patient, um neutral painting with abdominal pain or post up in abdominal pain? Or perhaps you have acute pain and fever or suspected abscess, so you select that choice, and that will bring you to a table that looks like this. The chart shows you a rating from least appropriate to most appropriate tests to order, as well as the relative radiation that's involved in the kind of test that you're ordering. So you can see here that for your patients suspected abscess, that ultrasound in memory don't, um, exposed the patient to any radiation. But neither is felt to be as appropriate for making a diagnosis of a suspected abscess as a CT scan of contrast. Also include with each chart is a discussion of how the recommendations were made and supporting literature that the, uh that the clinicians used to make their their consensus statement. Okay, in conclusion, when choosing imaging, keep in mind which type of test will best answer your clinical question when possible, wait for the results of one test. People are ordering another. Even if you suspect one test may not provide all the information you may need, avoid excessive ordering. May limit cost, patient anxiety, false positives and unnecessary interventions. Whenever you need Thio, call a radiologist for consultation so that we can discuss with you the patient's clinical information and help you choose the most efficacious image ng work up for the patient. I want to thank you for listening to my presentation today. Included Here is a bibliography of references I used for the discussion today and you will be given, um ah, code and a link that you can use for obtaining CMI. Thank you
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