Hello, everybody. This is Dr. Ximena Wurzman. I will be your host in this exciting course of ultrasound imaging provided by AAD. This is my disclosure, and this is Dr. Ximena Wurzman. I have been working in dermatologic ultrasound for the last 20 years, and I truly believe this tool is a must in dermatology. In this imaging course, we will navigate through the basic concepts, protocols, and main applications of ultrasound, including benign cutaneous tumors and pseudo-tumors, vascular anomalies, inflammatory skin diseases, nail conditions, and aesthetics. In every section of this course, you will find helpful anatomical information that can modify the management of dermatologist patients and testimonies from dermatologists worldwide who use ultrasound in their daily practice. Enjoy the ride. First, what is ultrasound? This is an imaging technique that uses sound waves that are not audible, and these sound waves are transmitted and reflected by the body tissues. You can find ultrasound also as sonography or ultrasonography, and it has diagnostic and therapeutic applications. We will talk about mainly diagnostic applications. So, what is a high-frequency ultrasound? This means that the frequency emitted by the device is equal or higher than 15 MHz. Why is this important? Because this is the frequency normally used for studying superficial structures, I mean soft tissues, because if you are studying, for example, an abdominal cavity, you will need a much lower frequency, for example, 2 to 5 MHz. And what is the definition of ultra-high-frequency ultrasound? This means that the frequency emitted by the device is equal or higher than 15 MHz. This is relevant if you want to study, for example, very superficial layers such as epidermis and dermis. On ultrasound, I mean diagnostic ultrasound, multi-frequency probes are recommended because otherwise you may lose penetration. These multi-frequency probes present a range of frequencies. So, for example, you are seeing here a probe or transducer that goes from 5 to 17 MHz. This means that you can see very deep structures and superficial structures in the same field of view. And that is pretty relevant when you are, for example, studying a skin cancer and you cannot lose penetration. And this is a very big difference between ultrasound and other imaging modalities used in dermatology such as, for example, dermoscopy or confocal microscopy or optical corneous tomography. Because on ultrasound, you don't have really penetration problems because you have this range of frequency to move on. On the right, you can see a probe that goes from 21 to 71 MHz. That is a pretty wide range to move within the... So, how the skin looks on ultrasound. We have on the left an image of the skin with an 18 MHz probe and on the right, a 70 MHz probe. If we look on the left, you will see an hyper-echoic white layer on top that corresponds to the epidermis. And the ecogenicity of the epidermis is mainly provided by the keratin content. Then, you see a less bright hyper-echoic layer that corresponds to the dermis. And the ecogenicity of the dermis is mainly provided by the collagen content. And at the bottom, you can see an hyper-echoic gray layer that corresponds to the epidermis. And the ecogenicity of the epidermis is mainly provided by the fatty tissue. In between the fatty tissue, you are seeing these wavy hyper-echoic lines that correspond to the fibroceptor of the epidermis, also called subcutaneous tissue. On the right, you can see the anatomy with 70 MHz. And we can detect very exquisite details such as, for example, this hair follicle as an hyper-echoic oblique structure and a sebaceous gland here as an oval shape hyper-echoic structure. And even a hair tract here before going into the surface. And so you can see this very, very nice detail that are really very similar to the lower magnification of histology. If we compare ultrasound with other imaging techniques, such as computer tomography and MRI, we will notice that ultrasound is much better in resolution. You cannot detect, for example, a hair follicle or the dermal, hypodermal or dermal subcutaneous tissue interface with MRI or computer tomography in their current commercially available devices. Something that is very important in ultrasound is that we don't really have penetration problems. Here you can see epileptic soma, a benign cutaneous tumor. And you can notice that we can go deeper and deeper into the tissues and we don't need to change the probe. And of course, we need to go deeper into the abdominal cavity, we need to change the probe. But consider the situation when you are in front of a skin cancer and you need to know where is the deep border. So that is why ultrasound is a very good choice of imaging technique because you don't have a penetration problem. And if you have a skin cancer that is involving the subcutaneous tissue or the cartilage or the muscle, you will know. Another cool thing about ultrasound is that we can study the blood flow in real time. And you are seeing here different softwares of blood flow. On the left you have the power doppler, in the middle you are seeing an echo angio software, and on the right you are seeing a color doppler software. So this is pretty cool and you don't have to inject anything on the patient, I mean contrast media. So that is really real-time information. Another important structure that we need to know is the nail. Here you can see the nail at 18 megahertz. This is the index finger in longitudinal view and you can see on top a bilaminar hyperechoic structure which corresponds to the nail plate. And the nail plate has two layers, the dorsal one which is outer and the ventral plate which is inner. And then we have the nail bed which is hypoechoic and in the proximal part of the nail bed we can detect the matrix region. We cannot see the matrix cells but we can tell this is the matrix region because the nail bed turns slightly hypoechoic in that area underneath the matrix region. And on top you can see the dermis of the proximal nail fold and of course the epidermis. And on the right you can see a three-dimensional power angio reconstruction of the nail and the blood flow which is also very cool. On 70 megahertz you can see the same things like a zoom. The only difference is that the nail plate will have a less anechoic interplate space in comparison to the 18 or 24 megahertz but still we have a little bit of difference in the outer and inner layer of the nail plate in comparison with the center because these are different types of keratin, soft and hard. So that's why you see those difference. Okay this type of ultrasound examination has some requisites. First you need a color doppler ultrasound machine with a multi-frequency probe equal or higher than 50 megahertz. Now in the market we have a lot of machines that can go up to 70 megahertz and at the same time a train operator on ultrasound and of course dermatologic conditions. In any of these conditions you need imaging technique. You have to be clear about the limitations of this technique. So what are the limitations of ultrasound? First if you're working with 18 megahertz the limitations will be the lesions that measure less than 0.1 millimeters and if you're working with a 70 megahertz probe the limitations will be the lesions that measure less than 0.03 millimeters. Other limitations are the lesions located in the epidermis only and the detections of pigments such as melanin. Currently we have guidelines published in the literature about the performance of dermatologic ultrasound and these guidelines are published in the Journal of Ultrasound in Medicine which is the official journal of the American Society of Ultrasound and in the Journal of the European Society of Ultrasound. This is important because it creates a standardization of the protocols and requisites for practicing dermatologic ultrasound. What are the main applications of ultrasound in dermatology? We have a wide variety of applications and among these we can find benign tumors and pseudo tumors, vascular anomalies, skin cancer, inflammatory conditions, aesthetic and nail lesions and we will go through these applications through this course. Before entering to the pathology we have to speak the same language. So to know something about ultrasound we have to know about the language of ultrasound and this is the ecogenicity. So what are the patterns of ecogenicity? What is something hypoechoic? This is something that looks white on ultrasound because it has a high reflection and it looks bright. What is hypoechoic? This means that the structure has low reflection of the sound and it will appear as gray on the screen. And what is something anechoic? It means that it has no reflection of the sound and appears a black structure on the skin. Examples of hypoechoic tissues or structures are some fillers. For example, this is a synthetic filler called silicone oil and you can see here at the upper and lower lip in a longitudinal view and you can notice the hypoechoic deposit of this filler. Another structure that is hypoechoic is the bony margin. You can notice here the bony margin of the anterior aspect of the tibia and another hypoechoic structure is the tendon. You can notice here the fibular pattern of the tendon, in this case the Achilles tendon. Examples of hypoechoic tissues or structures are fatty tumors like lipomas. For example, this is a fibro-lipoma which is hypoechoic and another hypoechoic structure is the muscle. You can see here the medial gastrocnemius muscle and the soleus muscle. Examples of anechoic tissues or structures are the fluid-filled lesions like the cystic structures, vessels, lymphatic channels, and pure silicone which is found in breast implants. You can notice here this anechoic breast pure silicone implant on the left and a lymphatic vascular malformation on the right. We have modes on ultrasound. One is the gray scale that will show you the extractor of the tissues without the blood flow and the other is the color gobbler that allows you to detect the real-time vascularity. There is also a difference between color gobbler and power gobbler. Color gobbler which means the detection of movement and direction of the blood flow and power gobbler which is the detection of a slow flow and it has a single color map. In color gobbler you are seeing you are seeing these red and blue colors and these red and blue colors are not arteries or veins. They are related to the direction of the blood flow and usually is red when it goes to the transducer and blue when it goes away from the transducer. And but on ultrasound you can even invert this map so don't think that these are arteries or veins because for that we will need to pick a spectral curve analysis. Regarding power gobbler this is a more sensitive mode so it is usually used when you want to detect a low vascularity. Another modes are the three-dimensional images as you see here and this is an image that is usually not diagnostic it's because it's more understandable by the clinicians and another mode called elastography that detects the stiffness of the tissues. So far elastography has proven not to be very effective for dermatological lesions because it has been a little bit chaotic despite the publication of some experiences. In my opinion it still needs a lot of work from the companies. Another mode is a panoramic view and this is important if you are studying a very large lesion for example a 20 centimeters lesion or more than 10 centimeters lesion because it will allow you to pick the whole tumor in one picture. That's why it's very important so it can allow you to measure well and that is a very big difference with other imaging techniques using dermatology such as dermoscopy confocal microscopy or OCT because here you have really a panoramic view of the lesion. I mentioned before some echo angio softwares that show you the vessels and subtract the tissues and this could be relevant if you are looking for slow flow vascularity in some lesions because they can show you in a pretty evident way that the lesion is vascular. Another thing that you can do is to fuse imaging for example ultrasound with computer tomography in this case we are making a fusion of the aorta in both technologies. On ultrasound it is possible to perform percutaneous guided procedures you are looking here on the left a percutaneous fine needle aspiration of a lymph node and on the right the injection with hyaluronidase of hyaluronic acid. So we have some options and this is pretty cool. The important thing is that this examination has a protocol and the protocol starts with a grayscale study at least in two perpendicular axis and then a color doppler at least in two perpendicular axis and then we make a spectral curve analysis also called pulse doppler. This pulse doppler allows you to see what type of vascularity you have in the lesion. If you are looking arterial vessels, venous vessels, the velocity of the vessels, the thickness of the vessel, everything and this is also relevant because if you move the probe just for moving you create colors so it is very important to know if this color is real or not. That's why we pick this corpse. Well this is an ultrasound machine. At the beginning it looks complex like a pilot cabin but it's not so terrible. Believe me. You can see here the screen and then the probes also called transducers and you can see that the probes present different surface. That's why we name these probes differently. For example this probe is called convex probe and these two other located on the right are called linear probes because they are straight on the surface. This small probe that looks like a hockey stick is normally used in dermatology especially on nails. You can also use this other type of probes that are named linear probes in general. You can also see the control panel, the gel bottle. We use a lot of gel on dermatological ultrasound which is a little bit different from other types of ultrasound examinations. When we look at the panel, the control panel, you can see a lot of buttons and you can adjust these buttons. For example this is the time gain compensation curve. The gain is like the power of the emission of the sun waves. Also you can create dual images to compare. Let's say right and left. You can push the color doppler, you can adjust the depth of where you want to look, you can press the power doppler, the pulse doppler for your core. You can make a zoom and you can freeze of course the image for taking a picture. What about the gain? I mentioned the gain and the gain is like the power of the sun waves and you should correct this power to not be too much or too high or too low as you see in these examples. And also you can adjust the depth. Here you are if you want to look for example this hyperechoic line here in the center. Here you have a very low depth and then you have the correct one and then you have a very high depth so you are missing this hyperechoic line here. So you are missing your target because you are showing a lot of shadow that you don't want to see. So you have to adjust your image. There are some artifacts on ultrasound that we need to know. I will mention the most common ones. Some of them are grayscale and others are color doppler. The most common artifact is the posterior acoustic reinforcement artifact also called posterior acoustic enhancement artifact and it appears as an hyperechoic wide band beneath the fluid field structures. This is because the sun waves can pass very easily through the structures so the importance of this artifact is that it can help us to identify the fluid field lesions such as cyst. Another artifact is the posterior acoustic shadowing artifact and this means that you will see an anechoic black band beneath a structure usually a calcified structure and this artifact occurs because of the obstructions of the sun waves by structures that contain calcium. So it helps us to identify calcified lesions such as for example epilometrixoma or a calcified granuloma or a filler like calcium hydroxyapatite. Another important artifact is the reverberation artifact and this is produced by structures that are strong reflectors of the sound. This is an artifact that appears as an hyperechoic or wide blurry band underneath this structure. So examples of these structures that are strong reflectors are fragments of glass or metals which are falling bodies. So this artifact is very useful to us. Another relevant artifact is the comet tail artifact and the importance of this artifact is that it can help us to identify some endogenous or exogenous components that produce highly reflection and among these are for example a polymethylmethacrylate filler a cosmetic filler and it appears like hyperechoic dots with a tiny reverberant tail. The noise artifact is also important to know because it is produced by a too high gain on the color doppler or a movement of the probe and this will show in the screen as multiple colors and this can be mistaken for inflammation or a disease progression or a bad response to a treatment so we have to be careful to have good settings in our machine. I will show you some technical problems for example I mentioned that we need a lot of gel on top of the lesions of or the skin. What happens if you don't use gel such as the image on the left? You cannot delineate well the lesion in contrast to the right image where you can delineate this tumor located in the dermis and subcutaneous tissue. We don't use a stand of pads because they can compress the skin vessels so we try to keep it as natural as possible. Another technical problem is the use of the wrong frequency. Here you have an example this is a lesion in the skin that was studied with a 10 megahertz probe and on the right you have the same lesion studied with the 18 megahertz probe and the difference is that on the left you can see that the lesion appears as hypovascular because of the lower sensitivity of this device and if you look on the right it's very clear that the lesion is hypervascular and so consider the recommendations published in the literature. Don't use devices that present probes working with less than 15 megahertz. What about changing the frequency and can this change the detection of our lesions or structures? Yes of course yes. Here you can see for example we are changing the frequency in the lower eyelid for the detection of hyaluronic acid and we are using 24 megahertz. This is a longitudinal view so you are seeing the orbicularis muscle of the eyelid of the lower eyelid and you can barely see the anechoic deposits of hyaluronic acid but if you change to 70 megahertz you can see a lot of these anechoic or black cell cystic areas that corresponds to the hyaluronic acid. So the answer is yes it can influence the detection. So the highest you can go is better. So in the market we have a lot of machines. We have some portable ones that look like smartphones or ipads and also we have other machines that appear as notebooks and some machines that are very high-end and very big and of course very expensive. So where are we going to buy? That is a big question when you are planning right and I would tell you that the decision will rely on the objectives because it is very different if you are going to use this machine only for the observations of let's say the main vessels of the face because you are dedicated to aesthetics and or if you want to use it really for percutaneous procedures for studying skin cancer or other types of dermatologic lesions. If you are focused on let's say the observation of the main vessels because you want to avoid the puncture of the facial artery of the angular artery when you are injecting a filler. Maybe you will need just a portable ultrasound unit like a tablet or a smartphone type which is something that is affordable. So you will detect the main vascularity arteries and vessels. As you see here you can detect here the facial artery and the angular artery and the superior labial artery in color because we are using the color Doppler. We have to be aware that there are variants of the main vessels. Here you can you are seeing some variants of the facial artery which can complicate the procedures for example injections of fillers which is important for the patient and of course. So if we want to focus on aesthetic practice but we also want to see some dermatologic lesions perhaps a portable unit like a notebook could be something reasonable. I always recommend to go as much as you can in frequency because you will detect better the lesions. If you want to perform percutaneous procedures guided by the ultrasound these machines usually present a lighter probe more ergonomic and so this tablet or smartphone type or notebook could be something let's say reasonable. This could allow you for example to see the location of a filler and not inject the harmonic acid in within the parotid gland such as in this case. On the other side we have a high-end device that usually goes from 18 to 70 megahertz that's what we have in the market and these machines usually present a sensitive color Doppler or power Doppler they present this echo angio and microvascular imaging softwares and that we have to know what we need so we have to really think the decision. What are the advantages and disadvantages of these very small portable ultrasound devices? Of course the advantages are the reasonable cost, the portability and the disadvantages are the heating of the probe, the loss of the wi-fi signal, a potential loss of the bluetooth connection and probably the pavement for storage servers in a night cloud otherwise you may lose your information. On the other side we have these high-end ultrasound devices and the advantages of these devices are better definition and discrimination, a higher color Doppler or power Doppler sensitivity, the access to microvascular angio software, light and small probes and access to different systems of imaging storage. The disadvantage of course is the high cost. Another important thing is the footprint or the surface of the probe. If you have a very wide surface you may cover things that you don't want to cover for example you are injecting a filler on the lips and your probe is covering the whole lips so you don't do that or you are studying a nail and the probe is too big so it would cover the whole nail. So for that we usually prefer these compact linear probes that appear as a hockey stick probe. Another important detail is that when you consider a machine is to have a good technical support and maintenance service so pick the brand that presents service in your city or your country otherwise it will be difficult to call somebody in case that you have some problems with the machine. It is important to decide the export type of file for your device and of course the image storage system that you will need. So for images I would recommend JPEG or DICOM. For videos you can use MOV, MPEG or AV among others. For the storage of your ultrasound images there are several ways to do it. If you are in a big institution you can use the institutional server that commonly has PAX systems. If you are in your office you can use a high capacity external hard drive. There are many on the market and also you can use a cloud storage. There are many on the market. My best choice if you are in an office for example I would select a high capacity external hard drive because it will give you control with these images. But never ever storage your images in the ultrasound machine because the ultrasound machines will become very slow and it will be very difficult. It has low capacity over time so definitely it's not an option to storage your image. Where to view the images because it's different to storage and to view. To view the images you can use your institutional server and therefore the PAX system and the PAX system has a special viewer and if you are in an office for example and you are using MAT you can use OSIRIS or OROS. OROS is free. OSIRIS is paid. These are softwares and if you are a PC user you can use EFILM which is paid. This is an example of a database. In this case storage in an external hard drive and with an OSIRIS viewer and the important thing about this database is that you can make smart albums and you need to make a tag or a comment in the patient line and then you can make smart albums and look these smart albums according to pathology. Another relevant issue is that you need to find out the confidentiality regulations in your place because there are some regulations that are very strict in some countries. For example in my place we need to keep the images for 10 years. I don't know in your place but for certain you need to know the regulations. So in conclusion the knowledge of the basic concepts, requisites, protocols, limitations and guidelines is important. We need to standardize the quality of the ultrasound examinations and the decision of the type of ultrasound device and if you want to buy one it will depend on the main objectives of your practice. So thank you for your attention and see you soon in the next class.

ultrasound imaging

dermatology

skin conditions

high-frequency probes

vascular anomalies

image storage

standardizing examinations