Pediatric CT Imaging - Pediatric Dual Energy CT Webcast

Well, I'm Marilyn Siegel at the Mallinckrodt Institute of Radiology, Washington University School of Medicine in Saint Louis. And I'm have the opportunity and privilege to speak on pediatric dual energy CT. The objectives of the lecturer discuss the role of dual energy CT and pediatric imaging. We'll look at the technical factors, discuss some selective clinical applications and finally address radiation dose, how do we do it. The protocols are the routine protocols used in clinical practice. We use them with the dose reduction tool same as single energy CT KERA dose 4D to adjust milliamperage and then iterative reconstruction to correct noise at lower doses. The images are acquired AT2 energy Spectra low energy 7G or 80KV and high energy 140 or 150KV with 10. Now I'm particularly focusing on dual source flash or force. I'll discuss the alpha the meatome in a different lecture. The columnation for dual energy CT is 0.6 millimeters. High pitch scan is acquired, preferably 3 or greater reconstructions. We get thin reconstructions and thicker reconstructions. Just routine. The only difference is acquiring AT2 energies. We initiate the scan depending on the area of interest. For the chest, we use a delay of 25 to 30 seconds. In the abdomen we use the delay of 55 to 60 seconds and CT angiography. We use automated bolas tracking and usually scan and only the arterial phase. The exception is the liver. For characterizing a liver mass we'll use both venous and arterial phases. Any other area for CT angiography, we use a single phase. The goal is to keep the dose as low as reasonably achievable and reducing the number of phases is a key factor in doing that. We acquire low and high KV blended and multi planar images at the console. The low and blended images are sent to packs for interpretation and then we do additional post processing as needed. So this is an example of the array of images 7080 KV great contrast 14150 KV, less contrast, less noise and the blended image was it's the best of both worlds, 50% of the low KV and 50% of the high KV. In Pediatrics we interpret the low contrast or low KV image and the blended image. We don't use the 14150 KV very much. In pediatric imaging, additional reconstructions are done as needed based on the clinical indication. Two types energy selective, which are the mono energetic images and material selective images. These can be set up at the time of the scanning use it rapid results are done manually at a later time. Virtual mono energetic images, Let's look at those for a moment. We have two options, Low Kev values between 40 and 60 Kev, great way to improve contrast, and high Kev values between 110 and 150 Kev. Great way to reduce noise from metal artifacts. So here's an example of a low Kev mono energetic image. 50K E V60K E V70 Kev. Lower Kev increases the conspicuity of vessels and subtle lesions. It is also a great way to compensate for slow injection rates and the use of small catheters in children. We use smaller volumes of contrast and the catheters are smaller compared to adults. So sometimes the contrast levels are a little lower than those in adults. But you can overcome that and optimize contrast with Lower Kev images. And here are the high Kev images. We use that to reduce artifacts from metal in children. We don't have metal artifacts from hip replacements. That's an issue in adults. In children, we have artifacts from spinal instrumentation for repair of scoliosis. It's a common issue we face in pediatric CT. So this is a patient who has metal fixation throughout the spine, 140 KVP, lots of artifacts at 1:30 Kev, very few artifacts. You can see the instrumentation and you can also see the underlying osseous and soft tissue structures and you get great reconstructions. The second type of reconstruction that we'll look at is material selective images and there are four major options and these are the workhorses and dual energy CT, the virtual non contrast image where contrast is subtracted from the image, the iodine overlay where the iodine image is superimposed on the grayscale virtual non enhanced image, we have the lung vessel image which shows the pulmonary arteries and the arteries that have relatively high iodine content are color-coded in blue. And the veins that have relatively low iodine content are color-coded in red and red which you can see here. And red also is the color that you will see when there's restrictive flow. When there's good flow, it's color-coded in blue. The other image is the pulmonary perfuse blood volume image. This is the standard image, the so-called default image. It's The lungs are color-coded orange. You can see they're relatively homogeneous, but if you would like colors and you want multi color images you can acquire that with the Siemens technology. So it's really a user preference how you want to view the images. The applications will start with the chest and we'll start with the thorax, 3 applications, pulmonary artery abnormalities, these include congenital pulmonary artery anomalies, pulmonary hypertension and pulmonary embolus, Second application, lesion characterization and the third application assessment of treatment response. And we'll look at all of these congenital pulmonary artery anomalies. We're discussing pulmonary treation hyperplasia and that simply means the arteries are absent or small and they're associated with congenital heart disease. The clinical question that prompts CT because CT is done to respond to a clinical question. The clinical question is if the arteries are absent or they're small, how well is that long perfused? Is it getting vascularity and what is the anatomy of the vessels? So the dual energy tools that can answer this are their perfused blood volume image. In the iodine vessel NAP, you get both anatomic and perfusion data. This is an 11 month old girl. She has an absent pulmonary artery. This is a huge aorta. There is no pulmonary artery. We normally live here. These are collateral vessels that arose in utero and they are supplying the lung. So the question is how well are they supplying the lung and this is the pulmonary blood volume image and there's great perfusion to the lung. You can also see the right arch and some of the collateral vessels and it's done at a very low dose. Well, this is a 15 year old girl who was born with a small lung or small right pulmonary artery. This is the toprogram showing you the small right lung. Here's an image showing you the small right lung compared to the left. So the question is, is this lung being perfused? Here's the vessel image. This is the pulmonary artery, the main pulmonary artery. This is the left pulmonary artery. This is the small pulmonary right pulmonary artery. It's present, but it's small and you can see that there's normal flow vessel in the left lung, their color-coded blue and the right lung, the color-coded red means there's diminished or absent flow in that lung. And if we look at the vessel and pulmonary blood volume image combined, this lung is normal homogeneous red, orange color. You can see the blue vessels meaning high flow. The right lung is small, there's decreased iodine content and decreased flow. So great way of evaluating the status of this right lung second indication for thoracic dual energy CT&CTA is pulmonary hypertension and severe hypertension. The blood flow is restricted meaning there's less lung blood flow to the lungs that can lead to right sided heart failure and ultimately death. So the clinical question in pulmonary hypertension, are the lungs perfused? Is there flow restriction? This is a patient with mild pulmonary hypertension, homogeneous flow, sort of this red orange color, no defects. This is severe pulmonary hypertension, multiple small defects indicating flow restriction and similar to all of our scans, low dose another patient with severe pulmonary hypertension, the lung should be homogeneous. You've got multiple multiple defects here and if you look at the lung vessel image, blue being normal high flow, you're starting to see areas that are red meaning restricted flow. So dual energy CT is really an important tool in evaluating pulmonary hypertension and severity of disease. Another indication is pulmonary embolism and CT is the study of choice for looking at pulmonary embolism. We do the lung vessel image to detect the thrombus or the embolism, it color codes it red, so it's very conspicuous. The blood volume image is used to assess the downhill effect. How is it affecting the lungs? Is there an impact for the lungs being perfused and dual energy? CT is more sensitive than conventional CT angiography and showing subsegmental emboli and perfusion defects. This is your conventional CT and geographic image. It's routine and imaging. You can see there's thrombus in the pulmonary artery in a couple of areas. This is the iodine vessel map. Again you see the emboli, their color-coded red meaning diminished flow. But you also see multiple other areas that have subsegmental emboli, so improves detection of emboli. 14 year old girl with acute chest pain. Here's the embolus, pulmonary emboli and there is abnormal lung likely related to lung and fart. This is our vessel and pulmonary blood volume image. The infarct is much larger than we suspected on the conventional image. And in addition, you see multiple vessels that have thrombus, they're color-coded red, the left lung and areas in the right lung. So the perfused blood volume and vessel image gives us a lot of additional information compared to our conventional images. Well, we've looked at some angiography in the thorax. Let's move to another application which is lesion characterization. And now your post processing tool is iodine map and virtual non contrast image. Voxels that have iodine will appear bright and that suggests there's perfusion and that suggests it's a soft tissue mask and if it's soft tissue there's a higher risk of malignancy. Voxels without iodine will appear dark, suggesting there's an avascular lesion that's likely benign, maybe a cyst or maybe fibrosis. This is the 13 year old boy had a cough, had an abnormal chest X-ray and had a CT and there's a mass and it's 30 pounds filled units, so it's greater than the density of water, which should be close to 0. Is it a soft tissue mass or is it a complicated cyst that has a lot of protein or blood in it? The iodine overlay shows no iodine. This is a cyst. It was removed. It was a cyst that contained a lot of protein which can elevate the Hounsfield unit above water. Great way to characterize masses. 2 other patients, adolescents. They have a lot of anopathy highly region mediastinum. The iodine map in this one, there's iodine. In these abnormal areas. This one there's no iodine. Iodine containing mass. This is malignant. This is lymphoma. No iodine. This was benign. This was fibrosis due to an infection. SO200G CT Great way to characterize masses. And the third application in the thorax is assessing treatment response response to chemotherapy. The clinical question is the patient responding or not responding? So your dual energy tools here or the iodine image just qualitative assessment and iodine quantification using regions of interest. The rationale behind this is the amount of iodine should decrease with successful treatment. This is a 15 year old girl, she received two courses of treatment for lymphoma but has a residual mass. So the question here is there tumor or is there fibrosis? Because fibrosis can develop at sites of tumor with treatment. Here's the iodine image, there is no iodine suggesting fibrosis in response to treatment and PET CT confirm that complete responder no tumor left. Well, here's another girl. Also lymphoma had two courses of treatments. Similar to the prior patient, there's a residual mass. Is it tumor or is it fibrotic tissue? Here's the dual energy CT, there's iodine, that's tumor. And by the way, here's the PET CT it's metabolically active, that's tumor. Iodine uptake suggest active tumor. In this case it was confirmed on PET. This is a non responder. Well, we looked at the thorax, we've looked at angiography, lesion characterization and treatment response and we'll turn to the abdomen and two main issues, lesion characterization and response assessment. We don't do as much CT angiography in pediatric abdomen as we do on the chest lesion characterization. This is an adolescent boy had a bone marrow transplant for lymphoma and it's hematocrit started to drop. So they did a CT to see if there was a source of bleeding and there's a mass. Now the question is, is this recurrence of tumor or is this a hematoma related to bleeding? This is the blended image. The virtual noncontrast shows high density, suggesting that should be blood, and the iodine overlay shows no iodine. That suggests hematoma, and this lesion resolved in a few weeks. And this is a hematoma. So lesion characterization is a great way to use dual energy CT Dual energy CT is a fabulous tool for lesion characterization. And here's another 1-2 patients with abdominal masses. They're retroperit. Neil. Here's an one. Here's one. This is no iodine. This is iodine. This was benign. Neurofibroma, that's a neurogenic tumor. This is neuroblastoma, the tumor of childhood, highly malignant. It's got iodine in it. So lesion characterization and you can assess treatment response in the abdomen. This is a patient with neuroblastoma, one of our common tumors, one year old. Here is the tumor in the abdomen. Baseline 80 KVP image, great image. Six months later, there's residual. Is it tumor? Is it fibrosis? Here's the baseline. Here's our iodine image and we can put regions of interest and the iodine content 2.0 milligrams per milliliter. We want to see an iodine content less than one. This is at six months follow up. No iodine visually and virtually no iodine on quantitative assessment. This is fibrosis. So assessment of tumor response. This is a complete responder. Finally, what about the radiation dose? If automated exposure control and iterative reconstruction are used, the radiation doses for dual energy C are similar or less than those of single energy CT This is the study we did on 860 children 430 Joe Energy CT430 Single Energy CT. The single energy CT was performed at eighty 100 or 120 KVP selected by CARE KV. We matched these patients for age and circumference and we found that the doses in dual energy CT were lower than those with single energy CT. The main CTDI valve was 5.6 milligrams for dual energy CT and 6.1 for single energy CT and that's the significant difference. Moreover, we found that the image quality and contrast to noise ratio were maintained. So to sum it up, material specific reconstructions. These are the workhorses, the virtual non contrast and iodine map for lesion characterization and treatment response and lung vessel image, pulmonary blood volume image for perfusion to assess vascular destruction such as the pulmonary arteries. We also reviewed mono energetic images to improve contrast and reduce artifact. So in summary, dual energy CT does not require additional radiation compared with conventional single energy CT Image quality is terrific. It's maintained. Overall, it's a win win scenario. Dual energy CT is a great tool. So thank you for your attention.

40 133 190 80 542 200 5.6 6.1 Siemens Healthineers are neither the provider nor legal manufacturer of this video. Any claims and statements made in this video and any content shown in the video are under the sole responsibility of the provider. Additionally, the training may not be available in all countries and the content may not be commercially available in all countries. Please contact the provider for more information. Pediatric Dual Energy CT Marilyn J. Siegel, M.D. Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis, MO Objectives · Discuss role of dual-energy CT (DECT) in pediatric imaging -Technical factors Selected clinical applications Radiation dose How We Do It . Protocols are the routine protocols used in clinical practice · Use with dose reduction tools, same as single-energy CT CARE Dose 4D to adjust mAs Iterative reconstruction to correct noise at lower doses DECT Technical Factors Dual Source Flash/Force · Images acquired at two energy spectra Low energy 70/80 High energy 140/150 Sn Collimation: 0.6 mm High pitch (3.0) Reconstructions: Scan Initiation Times · Routine chest: fixed delay - 25 to 30 s · Routine abdomen: fixed delay - 55 to 60 s CT Angiography automated bolus tracking -usually scan in only arterial phase · KEY CONCEPT: image during one phase · Keep the dose low: ALARA principle DECT Workflow · Low and high kV, blended and multiplanar images are generated at console in all cases · Low and blended images sent to PACs for interpretation Additional post-processing done as needed Scanner syngo.via PACS Basic Anatomic DECT Images Dual Source Scanner 70/80 kV 140/150 kV Blended 50% low and More contrast Less contrast 50% high kV Addtional Reconstructions · Done as needed, based on clinical indication · 2 types -Energy-selective image »Monoenergetic images Material-selective images · Post-processing can be set up at the time of the CT scan using Rapid Results or done manually at a later time Virtual Monoenergetic Images Reconstruct at Single Kiloelectron Volt · Low keV values (40 - 60 keV) to improve contrast · High keV values (110 - 150 keV) to reduce noise from metal artifacts Appli ... Tools Evalu. Monoenergetic Energy [keV] Low keV Monoenergetic Images · Increase conspicuity of subtle lesions · Compensate for slow injection rates via small catheters 50 keV 60 keV 70 keV Contrast = 1140 HU Contrast = 740 Contrast = 580 High keV images (110-150 keV) · Reduces strength of metal artifacts 140 kVp 130 keV DECT Reconstructions · Energy-selective image »Virtual monoenergetic images Material Specific DECT Images 4 major options Virtual non contrast Iodine Overlay Lung vessel map Perfused blood volume Material Specific Imaging Thoracic Applications Pulmonary artery abnormalities Congenital pulmonary artery anomalies -Pulmonary hypertension Pulmonary embolus Lesion characterization · Assessment of treatment response · Pulmonary atresia and hypoplasia -Arteries are absent or small · Clinical questions prompting CT? -How well is the lung perfused? -What is the vascular anatomy? DECT specific tools -Perfused blood volume DECT provides Anatomic + Perfusion data 11-month-old girl Absent Pulmonary Artery · Collateral vessels arising from aorta . Are they perfusing the lung? 80 kV CTDIvol 1.03 mGy 15-year-old girl with congenitally small right pulmonary artery and lung Iodine vessel image Vessel + PBV image 5 yo Pulmonary Hypertension In severe hypertension, pulmonary blood flow becomes restricted Untreated hypertension leads to decreased pulmonary blood flow, right-sided heart failure and death Clinical question: Are the lungs perfused? Is there flow restriction? Blood Volume Images Mild CTDIvol < 1 mGy W 542 DECT Pulmonary Embolism · Lung vessel image basis for PE detection · Codes thrombus as red, increases conspicuity · Blood volume image is used to assess parenchymal infarct (downhill effect) DECT more sensitive than conventional CTA in showing subsegmental emboli and perfusion defects Pulmonary Embolism: Vessel Image Angiographic Image Iodine vessel map Vessel image highlights the emboli Improves detection of segmental emboli Perfused Blood Volume + Vessel Images 14-year-old girl acute chest pain 40 keV image Emboli, infarcts Thorax DECT: 2nd Application Lesion Characterization · Post-processing tool is iodine map and VNC · Voxels with iodine appear bright Suggests perfusion / soft mass, higher risk of malignancy · Voxels without iodine appear dark Suggests avascular, likely benign lesion - cyst or fibrosis 13-Year-Old Boy, Mediastinal Mass Blended image- Iodine Overlay- density > water no iodine content Two Adolescents, Suspected Lymphoma LOC Lymphoma No iodine Fibrosis Thoracic DECT: 3rd application Assessing Treatment Response Clinical question is patient a responder or non-responder DECT post-processing tools iodine image (qualitative assessment) iodine quantification (ROIs) · Rationale: Amount of iodine should decrease with successful treatment 15-Year-Old Girl Lymphoma, 2 Courses Treatment Residual mass: tumor or fibrosis? No iodine uptake, suggests fibrosis Complete response, confirmed on PET-CT Qualitative Assessment DECT PET CT Iodine uptake, suggests active tumor Residual tumor, confirmed on PET-CT Abdomen/Pelvis Example: Lesion Characterization Adolescent boy, bone marrow transplant dropping hematocrit- tumor or hematoma? Blend (0.5) VNC Iodine overlay Two Patients With Masses 200 H Neurofibroma Neuroblastoma Assessment Tumor Response Neuroblastoma 1-Year-Old optiray 320 Baseline 6 month follow up lodine Maps [1] CT App: VNC/ CM/ Mixed 0.6 Mean: 29.3/ 55.8/ 85.5 HU Stddev: 10.4/ 8.1/ 12.3 HU Mean: 51.0/-0.9/ 50.6 HU lodine Density: 2.0 mg/ml / 34.7 % Stddev: 6.5/ 7.2/ 7.5 HU lodine Density: 0.1 mg/ml / 2.8 % Baseline Iodine 2.0 mg/ml Follow up Iodine 0.1 mg/ml Complete Response What About Radiation Dose in DECT? · If automated exposure control and iterative reconstruction are used, DECT radiation doses are similar or less those of Radiation Dose 2019 · 860 children (430 DECT, 430 SECT) · SECT performed at 80, 100 or 120 kVp (CARE kV) · Matched for circumference (12 days to 18 years) . Doses in DECT scans were lower than those with SECT -Mean CTDIvol of 5.6 mGy vs 6.1 mGy, P< 0.001. Image quality and contrast to noise ratio maintained CTDIvol (mGy) P Value <. 001 SECT Recap: DECT Material Specific Reconstructions and treatment response Pulmonary arteries Perfusion image Summary · DECT does NOT require additional radiation compared with conventional single-energy CT · Image quality is maintained WiN The End The statements by Siemens Healthineers' customers described herein are based on results that were achieved in the customer's unique setting. Because there is no "typical" hospital or laboratory and many variables exist (e.g ., hospital size, samples mix, case mix, level of IT and/or automation adoption) there can be no guarantee that other customers will achieve the same results. Please note that the learning material is for training purposes only. For the proper use of the software or hardware, please always use the Operatol Manual or Instructions for Use (hereinafter collectlvely "Operator Mannal") issued by Siemens Healthineers. 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