U.S. F&A and F&B state-of-the-art, as well as which needle should I use, my disclosures, and the objectives of this talk are to discuss the F&A, F&B concepts, indications and applications, as well as the devices and techniques, and some of the summarized data sets that we have on this topic. So, that will be the goal. The diagnostic applications have been very well covered by Dr. Ahmed. EUS is really capable of finding disease pathology and targeting tissue virtually in almost every area of the body, except for the small bowel, which remains a challenge still. The EUS F&A needles are shown on this slide. You can see here, hopefully it transmits well, is where there is a special treatment to the end of the needle. This is a typical F&A needle, which increases the ecogenicity of the needle when you're performing EUS, and then there's various sizes and shapes and forms available, but that's the basic construct of an EUS F&A needle. EUS F&B, or core needle, on the other hand, has a different design, and one of the earlier ones was a reverse bevel needle, where when you pull back the needle after insertion, that's when the core is cut, and along came a transformational needle known as the fork tip needle design, where you can see it's almost like a sharp tip out here at the tip of the needle, and then the Francine needle design, which is the more later ones, which is also a core needle, where they're really unique and different designs. So these are core needle designs that are now pretty much the mainstay for some of these applications. Now, overview for the sensitivity of EUS F&A. For solid pancreatic lesions, both F&A and F&B have a very high diagnostic accuracy and yield. As was mentioned by Dr. Ahmed, the current expectation is to be in the 90 to 95% diagnostic yield and accuracy benchmark. For pancreatic cysts, of course, we all know that the yield is relatively lower, and for indeterminability strictures, it goes even further down, but for lymphadenopathy, particularly lymphadenopathy that has cancer, the yield should be nearly 100%, but for more reactive lymph nodes and nonmalignant diagnoses, this can go down. Subepithelial lesions remain a challenge, particularly when they are small, certainly smaller than two centimeters, and we'll review that in the panel discussion, but for larger lesions such as gists and neuroendocrine tumors, the yield can be fairly high. So the obvious question comes is, why should we do an F&B or a core biopsy? Well, the F&B or a fine needle biopsy does give us overall larger volume of tissue, allows pattern recognition, such as for liver biopsies, and then increasingly for lymphoma treatments, the treatments are so sophisticated based on lymphoma subtypes and sub-subtypes, it's almost even difficult for a core needle to provide that level of detail. That is why we always compete with excisional lymph node biopsies when it comes to lymphoma. Special staining for certain disease states is important, and the core biopsy affords us the amount of tissue that we can use for special staining. Now when you compare the FNA versus F&B needles and the devices, they are shown back to back here in this slide, the needle sizes are pretty much the similar across the board, but the FNA will get you fewer cells that will be placed on the slide, and then most of it will be sent to the cell block. But the nuclear material and the cell quality and the DNA quality will be quite high even with an FNA, and should be for the most part adequate for most malignancy diagnosis, which is a yes or no diagnosis as long as you're using the appropriate techniques. For core biopsies, of course, as I mentioned earlier, tissue architecture is the key. You get a large volume, and some of these disease states that are listed here will require that large volume and pattern and architecture and so forth. And certainly, it has been well published and documented that for salvage FNA cases where you are going after one or two non-diagnostic FNA attempts, core biopsies really up the ante there and are able to get the diagnosis nine times out of 10, even in those difficult tissue cases. Mention about FNA technique, regardless of which needle or FNA versus FNB you're using, technique is important. And when it comes to FNA technique, which is the traditional fine needle aspiration, it seems that the fanning technique, which is basically puncturing the lesion at different locations and doing the actuations across the span of the lesion seems to be the more preferred technique, which gets the best and most likely the diagnostic tissue. Now, for smaller lesions, particularly those that are up against a vessel, I'll show you a video demonstrating that. The door knock technique, where you lock the slider and then hit the slider at a particular speed, it is required for harder and firmer lesions, but also for small lesions where the traversing length is very small, and we'll see that in a video. For smaller pulls, always try to target the hypoechoic areas, the solid areas, stay away from the necrotic areas, go towards the periphery of the lesion, that's where a lot of the mitosis is occurring, contact the lesion wall, let the needle kind of suction, if you're using suction, some of the material at the outer wall layer level, even for solid lesions, and then using whatever technique you're using, whether it's slow stylet pull or suction, allow the cells to come into the needle. For FNA, typically we'll do anywhere between three to five passes, with each pass, we'll have five to 15 actuations, depending on your particular practice, the size of the lesion, and so forth. So, all of this has been well described in literature, but just wanted to highlight what the high points are there. Now, the FNB technique is a little bit different, typically fewer passes and fewer actuations per pass. Most of the time, you don't even need any kind of suction or, or a special technique here, the core needles are very well designed to grab a lot of tissue, just with the act of puncturing the lesion. It's important for core needles, especially those with the larger hefty sheets, to lock the sheath lock, because you don't want to drive the sheath into the target organ, particularly a large organ, such as the liver where the sheath will enter the organ very easily and create some problems, if you're not careful. So which technique should we use, which needle should be used, that's really the meat of the lecture here. Essentially, the short answer is a needle size really doesn't seem to matter based on the literature, similar sensitivities and diagnostic yields are available, depending on what technique you're using. The 25 gauge needle is, I mean, if you look at the literature, has been preferred because it is less traumatic overall, less blood in the specimen, but it may be difficult to work with some of your technical assistance, especially if the needle is coiled and they're not extending it, it gets clogged a little easier, especially if there's a lot of blood in the channel, and a little more force is required to deliver the specimen. But all techniques have been looked at, overall data is relatively limited as to which might be the more advantageous one, but a lot of the folks will use low stylet pull at the beginning, and may use half suction, especially where material is scant on just the FNA or FNB. Slight prep pulls are important. It's important to have a slide which has some tissue on it, rather than just fluid. This is going to be a relatively less yield, the tissue will have a little bit higher yield of course, and then of course a lot of that tissue will also be need to be in the cell block. Expressing the material after the FNA has been done on the table, on the slide, on the back table is really, really important, and that's where some of your rapid on-site evaluation technology and expertise comes into play. Sometimes physicians will themselves hand over the scope to an assistant and go on the back table and prepare the slide, because all the work of the FNA and of the procedure really boils down to initially with how well the slides are prepped and what material ends up in the cell block. So it's important to keep, pay a note to that and develop that team concept where this part of the procedure is paid attention to. Now what about the concept of rapid on-site evaluation in the FNB era? Just to summarize the slide, rapid on-site evaluation was in vogue, still is in many cases. It has suffered a little bit in the pandemic due to staffing issues, but safe to say it's still a paradigm in play, but do we really need it in patients who have core biopsies? So this study looked, a relatively recent study looked at this question in solid pancreatic lesions and in about 700 patients equally divided between rows versus no rows. The new generation FNB needles were used and diagnostic accuracies were comparable with or without rows, but samples without rows had a significantly higher tissue core and had a shorter procedure time, obviously because you're not waiting for pathology to come up and spend time on interpreting. So an important concept that if you're doing rows, if you're doing FNB, then rows may not be essential for the typical case. And here's a study which is even more recent looking at US FNA with rapid on-site evaluation versus just doing a core biopsy, a sizable number of patients and US core biopsies had fewer needle passes and shorter procedure time and was equally as good to rapid on-site evaluation with FNA. So another concept that has become very prevalent is that if you're doing core biopsies, you may not need rows and especially in smaller community hospitals, if you're practicing there, it may be difficult to get that type of help, especially in the post-pandemic area. So these are two important studies to keep in mind. So here's a video demonstrating where an FNB might be more useful. This is a classic example of a cyst that has transformed into a carcinoma. You see the cystic elements here and you see some ductal structures, and this is a perfect example of where a core needle sampling into the solid area of the lesion will provide a higher yield for a diagnosis typically. These are difficult lesions because the cancer is prevalent only a small area of this lesion and may not be picked up without using such techniques. Here's another example of a core biopsy where we're looking at a metastatic carcinoma in the liver. You can see here liver lesions can be either hyper-echoic, hypo-echoic or in this case almost iso-echoic. And this core needle is getting adequate tissue because we don't know where this metastatic focus came from. The patient's carcinoma was of unknown primary, and every attempt that we can provide the pathologist to stage and diagnose this lesion and stain them properly is good. So a core biopsy would be very useful here. Here's another patient who had a periportal lymph node from bladder cancer. Bladder cancer is usually relatively indolent, and to find a periportal lymph node, lymphadenopathy, you can even see there's another bigger node here. A core needle will confirm this diagnosis much more efficiently, and that's what's shown here. The other thing that's shown here is we're hitting the wall, the outer wall of the lesion where some of the active cells are prevalent, and the center tends to have a little bit more of the necrosis. These are the kind of samples we get with core biopsies in today's day and age, and this is not uncommon. This happens to be a liver biopsy specimen, and these are more than adequate for at least initial diagnosis. Histopathology, you know, there's tissue architecture, just like you would see from a percutaneous biopsy. Now looking at some of the constructs for solid pancreatic lesions, as I mentioned before, EUSFNA and FNB both have a similar diagnostic yield, and however, FNB provides a greater tissue volume, and there's a marginal cost difference, but significant value in the salvage cases where you have prior failed FNA, and now you're doing FNB. So that's important to keep in mind, especially for referral centers and for those high volume units where we get a lot of referrals for second and third repeat EUSs, we go straight to the FNB paradigm in those cases, and are able to get a diagnosis most of the time. For subepithelial lesions, the FNA-FNB construct is reflected here in a meta-analysis of 10 studies, also a relatively recent study. So subepithelial lesions, FNB appears to be superior to FNA. I've rarely seen an odds ratio of 40, so that's quite impressive. So keep in mind that for subepithelial lesions, especially where the lesion is sizable enough, you know, so you can do a meaningful core biopsy safely, then maybe that's the way to go, and that's become kind of our mainstay at this point. For lymphadenopathy, it's interesting to note that lymph nodes that have cancer in them, either FNA or FNB will be good enough, and typically you get adequate cells starting to come even in the first pass. But for those lymph nodes that have lymphoma, the sensitivity of even FNB is low, and look at the sensitivity of EUS FNA is only at 9%. So lymphoma diagnosis remains a challenge, especially low-grade, slow-growing, indolent lymphomas. You almost always will need an excisional biopsy at expert lymphoma centers, but the core biopsy does come pretty close to at least getting the diagnosis started, and if that's not good enough for the team, then they can always proceed to an excisional biopsy, even in today's day and age, and that's important specifically for lymphoma. But if you have cancer in the lymph node, that should be picked up relatively easily. Now a couple of slides looking at which core needles are better than the other ones. So we have relatively recent studies on this topic of fork-tip versus reverse bevel was one of the first ones that came out and clearly showed that the fork-tip design is actually much superior, regardless of needle size, where the overall sensitivities, accuracies, and specimen adequacy were all quite superior to the reverse bevel design. Now comparing FNB needles, this is a meta-analysis looking at FNB needles against all other needles, and you can focus your attention to this side, which is the comparison with the other FNA and both the Francine and fork-tip needles significantly outperformed any other needle type. And this really, you know, is a very recent study, which I would encourage you to look at. It really has set the stage for these two needles to be the go-to needles and for our diagnostic purposes for a wide variety of indications. I have to put a note for EOS-guided liver biopsy. It's a relatively novel paradigm in the last decade or so, but it's really found home in many practices. 19-gauge fork-tip or Francine needles, diagnostic accuracy for this is variable, but as you get better with it and depending on the nature of liver tissue that you're targeting, especially non-serotic tissue tends to yield better tissue, you get enough portal tracts and so forth. So EOS liver biopsy specimens obtained with Francine needles even outperformed the fork-tip ones, but both tend to be pretty good and in expert hands with some experience, you can get a good amount of tissue, good enough for a diagnosis. Recently, a top 10 tips kind of article came out. David Deal has really pioneered this technique and this clinical paradigm. And it really involves all the aspects that you need to consider when you're planning to set up an EOS liver biopsy program, because remember, unlike pancreatic head cancers or lymphomas that come in spurts, this will be a paradigm in your practice. And if you do start it, you will be likely doing it every week, several cases a week. So speaking to a hepatologist, getting a program together, identifying which needle you're going to use, making sure there are no procedure contraindications and so forth. And then of course, assessing the patient. So this is a nice article to review if this is a direction you're taking your practice in. So strategy for determining needle type and size. Well, the first question I asked is, what is the question being asked? What is the suspected diagnosis here? Are we looking at a possible cancer? Is this a primary metastatic disease? Where is the lesion located? If the lesion is located in the pancreatic head and the patient had a Roux-en-Y gastric bypass, that's not something I want to deal with necessarily at this point, unless I'm planning some avant-garde U.S. guided interventions, which Nantali will tell us about. Is tissue architecture needed or are cells enough? That's an important question. What's the lesion size? Is this a five millimeter lymph node in the aortopulmonary window, or is this something different, something more sizable that I can plan differently for? Are special stains needed? Is molecular profiling on hand? And of course, is this a first attempt or is this a salvage procedure? So when I'm planning my procedure, my device is my time and my approach and my informed consent with the patient. These are the questions I'm asking on a daily basis. How do I use U.S. FNA and FNB needles? I'll use a 19-gauge needle for liver biopsies and lymphomas whenever I get a chance. I think that is the go-to needle at this point, based on the literature and our own experience. But typically for all the rest of the indications, a 22-gauge core needle should be adequate. I must add that for pancreatic garden variety pancreatic carcinoma diagnosis, I still go with FNA most of the time, unless there is a special ask. But core needles are definitely very helpful for all the other indications we have reviewed. Complications of EUS have been reviewed by Dr. Ahmed already. Just a couple of notes here. I have seen intracystic bleeding in a cyst in a pancreas. It usually is of no clinical consequence. Infection does occur and there is a controversy around antibiotic use with FNA, which we can have a discussion on in the panel. Bile leak in the pancreatic head FNAs can be quite traumatic for the patient. It is extremely rare, especially when you are doing an FNA with the intrapancreatic bile duct in the way. But occasionally, the thin bile duct will get compressed around the second duodenum, and you may not even know about it. And the patient will have normal pancreatic enzymes, but severe abdominal pain. And I would look for a bile leak in that patient. Death from EUS-related complications is not common, fortunately, but it is not zero. And that is something we can talk about under what situations is there significant morbidity and mortality. Take home points from my topic here. EUS-FNA and FNB have a comparable diagnostic accuracy in garden variety pancreatic cancer cases or other carcinomas, where the answer is yes, cancer or no cancer. But definitely, EUS-FNB has significant advantages for subepithelial lesions, for lymphomas, for liver biopsies, for gist, and particularly useful for salvage procedures where initial EUS-FNA has failed to answer the question. Additionally, to note that FNB typically does require fewer passes, study after study has shown us that. It does provide us with a higher volume of tissue, preserves the architecture for the most part, best we can with an endoscopic procedure. And the fork tip and the Francine needle designs have really proven to be consistently high yield in even the most challenging situations. And that's a truly remarkable step forward in tissue acquisition space. I have to overemphasize the importance of the EUS-FNA and FNB technique. And that's where training comes in, experience comes in, and learning from videos and learning from hands-on workshops comes in. The technique of FNA is really even more important than what needle you're using and so forth. And of course, we are blessed that the complication profile of the EUS-FNA procedure is very, very favorable. And that is what has allowed this paradigm to really blossom and flourish over the last three decades. So with that, I'll stop my lecture.

endoscopic ultrasound

fine-needle aspiration

fine-needle biopsy

EUS FNA

EUS FNB

diagnostic accuracy