Dual Energy Spectral Imaging White Paper

Dual Energy Spectral Imaging
The clinical benefits and how to choose the right solution

Dual Energy spectral imaging The clinical benefits and how to choose the right solution SIEMENS Healthineers 2 What is dual energy? Dual Energy provides everything you expect from conventional CT, transformed to deliver more value for your entire patient population. It’s the difference between images and answers. Visualization and characterization. Qualification and quantification. Built into all of our CT scanner platforms, it delivers powerful performance, incredible versatility for your entire patient population, and exceptional ease-of-use—all while integrating seamlessly with your current workflow. And that is a world of difference. Contents What it is and why it impacts patient care? 8 Dual energy in clinical practice Oncology 10 Emergency & Trauma 22 Additional applications 40 Dual energy types: how do they differ? 50 3 Dual Energy spectral imaging 4 Dual Energy spectral imaging What is dual energy spectral imaging? Analogous to the move from Black & White to Color TV --- O Traditional Single Energy Acquisition Dual Energy Spectral Acquisition Dual Energy, also called spectral and energy-selective CT, uses two energy images from different X-ray spectra—in one patient scan—to offer more clinical information than a single energy CT image. This can enable crisp images with sharp contrast and improved visualization and quantification, with broad applicability for numerous clinical questions and patients. 5 Dual Energy spectral imaging How Dual Energy helps separate materials Because X-ray absorption is energy dependent, changing the tube‘s kilo voltage (kV) results in a material specific change in attenuation. For example, this allows you to distinguish iodine from bone even when they would have the same HU value in a single energy image. Low kVp Image High kVp Image Iodine Bone CT-value 80 kV Identity 0 HU Blood Water Fat CT-value -1000 HU 140 kV Air 0 HU Material slope identifies and Slope = CT value low kV separates different materials CT value high kV 6 Dual Energy spectral imaging for a broader spectrum of information Certain materials change their attenuation value (HU) when exposed to different X-ray photon energies. This change facilitates material decomposition and characterization that can be used to identify, isolate, and eliminate 120 kVp Equivalent (Mixed Image) various materials (e.g., iodine, calcium, urate, etc.), providing additional diagnostic information. Low kVp Image + = An example of this function is the generation of virtual noncontrast (VNC) images and iodine overlays. In addition, monoenergetic Virtual Noncontrast Image images can be created over a range of virtual keV values from 40-190 keV. This requires the acquisition of a low and high energy dataset. High kVp Image Iodine Overlay 7 Dual Energy spectral imaging Why does it impact patient care? With their ability to help physicians diagnose a range of conditions, CT exams have long been Transforming Care Delivery and included in diagnosis and therapy strategies. Dual Improving Diagnostic Accuracy Energy CT—with its low and high energy images— • Greater depth of information can help identify material composition, which can in one scan be particularly helpful in oncology and trauma/ • Emergency Department cases, offering new insights Ability to uncover obscure that can impact clinical decision-making. pathology • Limit rescans/additional exams • Potentially reduce radiation and contrast dose • Improve the patient experience • Greater evaluation of therapy response 8 .::::::::: : :::: SIEMENS Healthineers SOMATOM Force VEMENS SIEMENS 9 Dual Energy spectral imaging 200 [HU] 10 0 [HU] Dual Energy spectral imaging Oncology Dual energy in clinical practice Oncology In oncology, lesion localization and characterization can help rule out malignancy. With the ability to better visualize subtly enhancing lesions and quantify iodine uptake, Dual Energy spectral imaging helps you differentiate lesions, monitor treatment response, and characterize incidental findings, helping you make a more confident diagnosis, which can reduce the need for additional workup. 11 Dual Energy spectral imaging Improve visualization of hypoenhancing liver lesions Oncology 120 kVp Equivalent (70 keV) Monoenergetic Plus 50 keV Notice the two additional lesions visible at lower keV. Images courtesy of Duke University 12 Dual Energy spectral imaging Visualize contrast uptake in Oncology subtly enhancing anatomy 120 kVp Equivalent (Mixed Image) Monoenergetic Plus 40 keV Notice the improved conspicuity of the pancreatic lesion at low keV. 13 Dual Energy spectral imaging Differentiate liver lesions Oncology A 54-year-old female patient with breast cancer, post- lumpectomy, underwent chest abdomen CT for the assessment of metastatic disease. The composed images reveal multiple liver lesions in both lobes. Some of these lesions, with HU values below 10, could be clearly diagnosed as simple hepatic cysts. Other lesions showed higher Composed Image CT values of up to 32 HU and the radiologists were unable to definitively classify these lesions as hepatic metastases. In this case, iodine overlays were calculated and enabled the evaluation of iodine uptake—helping the radiologist to differentiate between the simple benign hepatic cysts and the suspicious iodine up-taking lesions. Additionally, the Dual Energy acquisition eliminated the need for a true noncontrast acquisition resulting in significant dose reduction and workflow savings. Virtual Noncontrast 14 Dual Energy spectral imaging ROI left Oncology App: VNC/CM/Mixed 0.8 200 [HU] Mean: 1.3/18.8/20.3 HU Area: 8.6 mm2 Iodine Density: 3.4 mg/ml / 39.6% ROI Middle App: VNC/CM/Mixed 0.8 Mean: -5.7/8.8/3.0 HU Area: 0.2 cm2 Iodine Density: 0.2 mg/ml 39.6% Normalization ROI App: VNC/CM/Mixed 0.8 Mean: 171.5/127.9 HU Contrast Enhancement: 159.3 HU O O [HU] Iodine Overlay 15 Dual Energy spectral imaging Characterize Radiologist findings suspicious lesions Lesion 1 is hypodense in the VNC image (1a) and shows clear enhancement in the Oncology composed image (1b) and iodine overlay (1c). Dual Energy A 76-year-old male patient, suffering from metastatic clear ROI measurements reveal an cell renal cell carcinoma (RCC), underwent a right-sided increased CT value of 51.9 HU nephrectomy and was postoperatively treated with Pazopanib. A follow-up CT chest abdomen pelvis with contrast was ordered with an iodine density of for restaging and performed using Dual Energy. The images 2.3 mg/ml – characteristic of reveal two small, regularly shaped renal lesions—middle anterior a metastasis. (lesion 1) and upper posterior (lesion 2) to the left kidney, with elevated attenuation—suggesting metastasis. Lesion 2 is hyperdense in the VNC image (2a) and shows no Traditionally, this case would require the acquisition of an enhancement in the composed additional noncontrast scan for diagnosis. With a single Dual Energy contrast-enhanced scan, virtual noncontrast (VNC) and image (2b) or iodine overlay iodine map images can also be generated. Comparison of the (2c) – characteristic of a attenuation values in the VNC images, mixed images and iodine complicated cyst. maps reveal iodine uptake in lesion 1, but not in lesion 2. Iodine uptake in these lesions correlates with the characteristics of a metastasis (lesion 1) and a complicated cyst (lesion 2) without additional workup. ROI is from image 1c App: VNC/ CM/ Mixed 0.8 Mean: 16.9/ 51.9/ 68.5 HU Stddev: 8.6/ 7.2/ 11.2 HU Area: 1.1 cm2 For more case information see SOMATOM Session 37, p48 Iodine Density: 2.3 mg/ml 16 Dual Energy spectral imaging 1a 1b 1c 200 [HU] Oncology 200 [HU] InHIO F F 600 150 250 Virtual Noncontrast Composed Image Iodine Overlay 2a 2b 2c 200 [HU] 200 [HU] 200 [HU] O [HUI F O [HUI InHlo F W 76 51 W 500 32 Virtual Noncontrast Composed Image Iodine Overlay 17 Dual Energy spectral imaging Characterize incidental findings Oncology A 75-year-old male patient with recent unexplained bowel obstruction was sent for a follow-up CT enterography. The radiologist identified an incidental left renal soft tissue lesion with contrast enhancement compatible with a renal neoplasm. Virtual Noncontrast In this unsuspected renal mass case, the HU change in the ROI is close to what might be observed if a “traditional” noncontrast CT acquisition were to be compared to a contrast-enhanced acquisition. Pathology revealed a clear cell renal carcinoma. This is a common scenario, in which an incidental finding is observed that would require further testing to characterize for treatment decision. The Dual Energy data can be processed to create virtual noncontrast images and iodine overlays for presenting and quantifying iodine uptake. With this additional information, clinicians may be able to make a diagnosis faster, thus reducing patient stress inherent with diagnostic uncertainty Iodine Overlay and follow-up examination delays. App: VNC/ CM/ Mixed 0.8 Mean: 45.9/ 38.0/ 83.7 HU Stddev: 19.5/ 15.0/ 11.2 HU Area: 1.0 cm2 For more case information see SOMATOM Session 37, p50 Iodine Density: 1.7 mg/ml 18 Dual Energy spectral imaging Quickly characterize incidental findings Oncology without additional workup A A :76 122 404 50 466 214 nE NE DE 88 Composed Image Iodine Overlay 19 Dual Energy spectral imaging Monitor treatment Traditional CT response Oncology A 69-year-old female presented with acute exacerbation of the COPD. A left upper lobe lung lesion (49 × 38 × 34 mm) was detected incidentally on computed tomography (CT). A transbronchial biopsy confirmed a moderately differentiated squamous cell carcinoma (SCC). Due to severe emphysema and limited lung function, the patient did not meet the criteria for tolerance of definitive surgical therapy. Stereotactic radiotherapy was therefore recommended. In addition to the standard tracking of lesion size, Dual Energy spectral imaging supports improved monitoring of lung function (including lung perfusion) following SABR. This additional functional information may alert physicians about underlying perfusion changes in advance of the development of radiation pneumonitis (RP) following treatment. Early detection of RP is important as early application of steroids can reduce the severity—potentially preventing the progression to irreversible pulmonary fibrosis. For more case information see SOMATOM Session 36 Radiation Therapy Supplement, p18 20 Dual Energy spectral imaging Baseline CT 3-month follow-up 9-month follow-up Oncology 120 kVp Equivalent (Mixed Image) Iodine Overlay Tumor size significantly decreases over time. Note the surrounding minimal fibrotic changes. The iodine map is fairly inhomogeneous due to centrilobular emphysema. The perfusion map for lung parenchyma is slightly impaired in the vicinity of fibrotic changes. 21 SIEMENS Healthineers 2.01 0016 22 Dual Energy spectral imaging Jane Doc Dual energy in clinical practice Emergency and Emergency and trauma G trauma SOMATOM In trauma and/or emergent cases, time to correct diagnosis is critical. Here, Dual Energy spectral imaging can enable quick assessment of many conditions, including hemorrhages, edema, and fractures. The significant, relevant clinical information provided by the two energy sets can also support improved visualization of solid organ injuries, and better visualization and assessment of structures—while limiting contrast dose. 23 Dual Energy spectral imaging Rule-in/Rule-out perfusion defects in the lung BO [HU] -.....----.... O [HU] Emergency and trauma 120 kVp Equivalent (Mixed Image) Iodine Overlay A young patient after a motor vehicle accident had no obvious lung ® 143 injury on a conventional 120 kVp equivalent image, but complained of shortness of breath and pain. Iodine overlays generated from the Dual Energy acquisition provided quick visualization of the perfusion defect. The PE was thought to correlate with a emboli resulting from the significant bone fracture. Images courtesy of the University of Maryland X-ray 24 Dual Energy spectral imaging without previously required additional workup 80 [HU] Emergency and trauma 0 [HU] 120 kVp Equivalent (Mixed Image) Iodine Overlay In a busy radiology environment, classical pulmonary embolism wedge defects can be easily overlooked with traditional CT acquisitions in a lung window. Easily visualize defects with an iodine overlay. Images courtesy of the Hopital Calmette Lille 25 Dual Energy spectral imaging 200 [HU] Contrast-enhanced abdominal CT in a pedestrian patient struck by a car. On the 120 kVp equivalent images, there are multiple bowel loops in the left hemi-abdomen which have a thickened wall and appear to be non-enhancing. The iodine overlay images reveal complete lack of iodine content within these loops, which were infarcted due to serosal avulsion and were subsequently resected. Emergency and trauma There is also a moderate volume of hemoperitoneum and hemorrhage along the mesenteric root; mesenteric 0 [HU] injury was also confirmed intraoperatively. Wortman JR et al. Radiographics. 2018 Mar-Apr;38(2):586-602. 26 Dual Energy spectral imaging Emergency and trauma 120 kVp Equivalent (70 keV Image) 40 keV Image Virtual Noncontrast Image Utilizing spectral imaging in the emergency/ trauma setting offers new possibilities to characterize tissue and increase contrast, changing the way you see your patient. 27 Dual Energy spectral imaging Highlight suspicious organ structures to identify fractures 100 HUI .150 [HUI 100 PM Emergency and trauma Bone Marrow Edema VRT Bone Marrow Edema Color Overlay T2 Weighted MRI Image Despite being restrained at the time of a high speed, head on, motor vehicle collision, a 41-year-old male patient suffered significant dashboard contact. Clinical examination revealed increased anterior translation of the left knee easily visualized with the bone marrow edema color overlay. DECT images confirmed the posterior cruciate ligament was intact, but had an irregular buckled contour consistent with proton MRI. For more case information see SOMATOM Session 34, p60 28 Dual Energy spectral imaging Diagnosis of bone marrow edema associated with metastases 100 [HU Emergency and trauma -150 [HL 120 kVp Equivalent (Mixed Image) Bone Marrow Edema Color Overlay A 73-year-old male patient, with palliatively treated small cell lung cancer of the right lung, presented for an oncological re-staging CT. To date, there were no known bone metastases. The patient had a history of chronic back pain with slight aggravation during the weeks prior to the planned CT scan. The clinical examination revealed slightly diffuse pain over the middle thoracic spine with no neurological deficits. For more case information see SOMATOM Session 36, p58 29 Dual Energy spectral imaging Improve differentiation 1a between hematoma and a potential bleed A 17-year-old female patient, suffering from an acute onset of a severe headache for the past 24 hours, was admitted to the ED with no neurological symptoms or recent history of trauma. An immediate noncontrast CT exam showed a hematoma (1a) with peripheral edema in the left cerebellar hemisphere. The corresponding MIP (1b) Single Energy Axial revealed an anomalous feeding artery, malformed vessels, and an enlarged vein draining into the torcular herophili. 1b A Dual Energy CT (DECT) was requested to further investigate the cause and to rule out active bleeding. Virtual noncontrast images Emergency and trauma from the arterial phase (2a and 2b) and in the later phase (2c and 2d) show irregular contrast enhancement around the malformed vessels, implying active bleeding. Additionally, DE enables image generation at energy levels between 40 and 190 keV (3a – 3d). Image contrast can be significantly enhanced at lower energy levels (3a) compared to a conventional 120 kVp acquisition—resulting in greatly improved differentiation between the hematoma and the active bleeding areas. For more case information see SOMATOM Session 37, p66 Single Energy MIP 30 Dual Energy spectral imaging 2a 2b Norm: ROI CT App: 80/Sn150 Mean: 242.7/95.2 HU Contrast Enhancement: 133.8 HU DE Iodine Map Arterial Phase DE Iodine Map Arterial Phase O 2c 2d Emergency and trauma O DE Iodine Map Later Phase DE Iodine Map Later Phase o 3a 3b ROI Middle App: VNC/CM/Mixed 0.5 Mean: 73.4/6.2/80.4 HU Stddev: 3.2/3.6/4.6 HU Area: 9.2 mm2 Monoenergetic Plus 40 keV Monoenergetic Plus 70 keV Iodine Density: 0.1 mg/ml/2.5 % 3c 3d ROI Bottom App: VNC/CM/Mixed 0.5 Mean: 33.2/73.1/108.5 HU Stddev: 4.5/13.5/12.0 HU Area: 0.1 cm2 Iodine Density: 3.0 mg/ml 58.4 % Monoenergetic Plus 90 keV Monoenergetic Plus 120 keV 31 Dual Energy spectral imaging Differentiate hemorrhage and iodine uptake 120 kVp Equivalent (Mixed Image) Virtual Noncontrast Image Iodine Overlay Emergency and trauma App: VNC/CM/Mixed 0.3 App: VNC/CM/Mixed 0.5 Mean: 49.7/193.0/242.9 HU Mean: 67.0/9.6/76.6 HU Stddev: 3.9/7.0/6.0 HU Stddev: 3.6/5.0/5.5 HU Area: 0.2 cm2 Area: 0.4 cm2 Iodine Density: 7.3 mg/ml / 83.1 % Iodine Density: 0.4 mg/ml / 4.9% 32 Dual Energy spectral imaging Improve contrast enhancement to better visualize bleeding Emergency and trauma 120 kVp Equivalent (Mixed Image) Cinematic VRT Iodine Overlay Virtual Noncontrast Image Images courtesy of the University of Maryland 33 Dual Energy spectral imaging Better visualize vascular trauma with automated bone removal Emergency and trauma VRT MIP Image 34 Images courtesy of the University of Maryland Dual Energy spectral imaging View even the most complex vasculature with Emergency and trauma 120 kVp Equivalent Image (Axial, Coronal, Sagittal) MIP Image automated bone removal and metal artifact reduction 35 Dual Energy spectral imaging Assess the extent of calcification or... Emergency and trauma ....... MIP (Plaques ON) MIP (Plaques OFF) Cinematic VRT 36 Dual Energy spectral imaging ...vascular injury with automated body bone removal Emergency and trauma MIP (Plaques ON) MIP (Plaques OFF) Cinematic VRT 37 Dual Energy spectral imaging Improve visualization of tissue contrast at high keV Emergency and trauma 120 kVp Equivalent (Mixed Image) 190 keV Image 190 keV Monoenergetic Plus demonstrates acute left Trauma patient found after fall. The 120 kVp equivalent frontal and bilateral tentorial SDH – but also older image demonstrates a left frontal and bilateral tentorial SDH. bilateral SDH indicative of recurrent hemorrhage. Images courtesy of the University of Maryland 38 Dual Energy spectral imaging “Dual-energy computed tomography (DECT) is a disruptive technology Emergency and trauma that has the potential to change the way that CT is performed and interpreted.” Wortman J, Sodickson A. Pearls, Pitfalls, and Problems in Dual-Energy Computed Tomography Imaging of the Body. Radio Clin N Am. 2018;(56):625-640. 39 40 Dual Energy spectral imaging Beyond oncology, emergency, and trauma Additional applications Beyond oncology, emergency, and trauma, there are a wide number of additional applications for Dual Energy spectral imaging with tremendous clinical value. They support a more efficient workflow, higher patient satisfaction, and, Additional applications ultimately, a faster path to diagnosis and treatment. 41 Dual Energy spectral imaging Spectral imaging for bariatric patients... popul 200 [H] F Virtual Noncontrast Image Iodine Overlay (Patient weight 425 lbs) Topogram Images courtesy of the Northwestern University 120 kVp Equivalent (Mixed Image) Additional applications 42 Dual Energy spectral imaging ...diagnostic confidence without exclusion Virtual Noncontrast Image Iodine Overlay Additional applications (Patient BMI 40) Topogram Images courtesy of the Northwestern University 120 kVp Equivalent (Mixed Image) 43 Dual Energy spectral imaging See around metal artifacts with high keV monoenergetic 120 kVp Equivalent (Mixed Image) 190 keV images For more case information see article N Engl J Med. 2015;372(20):1945-1952. Additional applications 44 Dual Energy spectral imaging Highlight perfusion defects in the Additional applications myocardium without a 4D acquisition 45 Dual Energy spectral imaging Identify and characterize kidney stones for more confident therapeutic and diagnostic decisions 120 kVp Equivalent (Mixed Image) Color overlay: Helps in differentiating stone composition: calcium stones (blue) and uric acid stones (red) For more case information see SOMATOM Session 33, p64 Additional applications 46 Dual Energy spectral imaging Reveal and quantify uric acid deposits from small to large Additional applications Color overlay: Helps visualize uric 120 kVp Equivalent (Mixed Image) acid deposits (green) in relation to the calcium in bone (blue) For more case information see SOMATOM Session 37, p60 47 Dual Energy spectral imaging Spectral imaging for pediatric patients... 9-year-old female 200 [HUI 0 [HUI 120 kVp Equivalent (Mixed Image) 120 kVp Equivalent (Mixed Image) Iodine Overlay Iodine Overlay For more case information see SOMATOM Session 37, p58 Additional applications 48 Dual Energy spectral imaging ...all the benefits, free of additional radiation 13-year-old male Additional applications MIP (Plaques ON) MIP (Plaques OFF) Automated head bone removal 49 50 Dual Energy spectral imaging Dual energy types— how do they differ? In clinical use, the terms dual energy, energy selective,and spectral CT all refer to the same technique—the acquisition of low and high energy data to create one clinical image. Yet, these two energy datasets are acquired and constructed differently. And those acquisition differences can drastically impact your clinical practice and departmental efficiency. 51 Dual Energy spectral imaging How Siemens Healthineers creates dual energy Dual Energy data processing is sensitive to small 50 changes in Hounsfield units, making image quality crucial for Dual Energy spectral imaging. In addition, dose efficiency and workflow aspects play an Sn important role in enabling efficient Dual Energy imaging in daily routine. Regardless of your unique challenges, Dual Energy Tin spectral imaging offers a transformative CT advantage. All of our solutions help you visualize 118.710 differences in the energy-dependent makeup of your patients, revealing critical information about anatomical and pathological structures. Pb 52 Dual Energy spectral imaging Dual Energy acquisition techniques across the Siemens Healthineers portfolio for every size, practice, and budget Sn Sn Au high low kV kV TwinBeam Dual Energy Dual Source Dual Energy 53 Dual Energy spectral imaging TwinBeam Dual Energy By splitting the X-ray beam into two energy Gold Filter to create a spectra before it reaches the patient, TwinBeam low energy level Dual Energy enables examination of the same body region at two different energy levels simultaneously. These two image datasets provide additional information about the tissue, making it particularly beneficial in soft tissue differentiation and oncology. With full-dose modulation and iterative reconstruction as well, TwinBeam is dose neutral and ready for clinical routine. Sn Au Tin Filter to create a high energy level 54 Dual Energy spectral imaging Dual Source Dual Energy With industry-leading acquisition speed, Dual Source Dual Energy systems can handle patients from typical to critical. With two imaging chains, Imaging Imaging each acquiring about half the projections per Chain A Chain B rotation, these systems are able to generate a full Dual Energy dataset. Combining full dose modulation and iterative reconstruction with the ability to independently filter the X-ray beam results in improved spectral separation and dose neutral acquisition for every patient in the clinical routine. Sn . high low kV kV Full rotation time (down to ~0.25 s) Tin Filter for enhanced for highest spectral separation for temporal resolution high energy level 55 Dual Energy spectral imaging Other dual energy acquisition methodologies Dual Energy acquisitions rely on two datasets— a low and high kV—to provide additional clinical information. This is what makes them unique. Yet, how those two datasets are acquired, where and how they overlap, and if additional dose is necessary to maintain image quality—all of these factors can significantly impact the efficiency and clinical effectiveness of the data. 56 This presentation uses the preinstalled Office font Calibri. If you send it to Dual Energy spectral imaging someone internally or externally, please convert it To ensure a clean and • into a pdf to ensure that the content stays as intended. Non-Siemens Healthineers Dual Energy Acquisition Methods swift workflow with bullet points, please use the This presentation uses the PRE-SET PLACEHOLDERS or Fast kV Switching preinstalled Office font Calibri. If you send it to FORMATTED TEXTBOXES – someone internally or do not use “normal” Our template contains externally, please convert it textboxes that have been To ensure a clean and • layout guidelines. into a pdf to ensure that the added via the steps swift workflow with bullet content stays as intended. 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Unrestricted "Content Slide" The copied placeholder Placeholders can be • – be categorized, with the choosing the right category: Restricted will keep its formatting filled and then copied. – author being responsible for Confidential – Unrestricted Strictly confidential Placeholders can be The copied placeholder • – – choosing the right category: Restricted The preset default category filled and then copied. will keep its formatting – Computed Tomography Edit “Author | Department” Confidential for presentations is 3 in the “Header and footer” – Unrestricted Strictly confidential “restricted”. The copied placeholder for all pages. – – Start > Replace > insert Restricted The preset default category will keep its formatting “Restricted ©” and “the – Computed Tomography Edit “Author | Department” Confidential for presentations is new category ©” 3 in the “Header and footer” – Strictly confidential “restricted”. for all pages. Add a Footnote/Source/ – Start > Replace > insert Disclaimer directly into the The preset default category “Restricted ©” and “the footer. Edit “Author | Department” for presentations is new category ©” Computed Tomography 2 in the “Header and footer” “restricted”. for all pages. Add a Footnote/Source/ Start > Replace > insert Disclaimer directly into the “Restricted ©” and “the footer. new category ©” Slow kV switching Fast kV switching Dual layer detector Add a Footnote/Source/ Disclaimer directly into the footer. An acquisition comprised of two An acquisition composed of two An acquisition that utilizes a detector partial scans at two different kV interleaved datasets with different kV comprised of two layers of detector settings. These two acquisitions can settings. Unfortunately, the transition material and electronics on top of one be acquired with any modern CT between low and high kV can result in another doubling the electronic noise. scanner. As a result, this technology blurring in the spectral overlap, which Since the two layers are exposed to a does not offer the high-image quality reduces the image quality. In addition, single X-ray beam, without dedicated advantages of a dedicated Dual while the tube voltage can be changed filtration, there is poor spectral Energy spectral imaging solution with quickly, tube current cannot; thus separation resulting in reduced image additional beam filtration. resulting in either poor image quality clarity. Even with the benefit of dose or an increased radiation dose to the modulation, this method requires the patient. use of high kV, eliminating the benefit of low kV imaging for smaller patients Furthermore, without additional and increasing radiation dose over filtration, this method suffers from traditional methods. poor spectral separation and reduced image quality with higher dose. 57 Dual Energy spectral imaging Key criteria 1 Spectral separation The amount of overlap of the polychromatic X-ray spectrum between the low and high kV datasets. To consider when selecting a Dual Energy spectral imaging system 2 Temporal coherence The relative time difference between low- and high-energy acquisitions. Spectral imaging comes by many names in the market — Dual Energy, TwinBeam, Fast kV Switching, Dual Source Dual Energy, Dual Layer, and more. Due to high sensitivity to small Temporal resolution changes of the Hounsfield units, the ultimate measure of a 3 The time it takes to collect a complete set of spectral imaging system performance is image quality. projections necessary to create an image. Eliminate the confusion. Gain a better understanding 4 Spatial resolution The level of detail that can be resolved, important of the key criteria you need for for lung, bone, vasculature, etc. your next Dual Energy spectral imaging system. Dose efficiency 5 It is critically important for the success of dual energy imaging to provide added value without additional risk to the patient. Workflow 6 A streamlined workflow can offer time savings by eliminating steps, providing better consistency and an easier to use process. 58 Dual Energy spectral imaging 1 Spectral separation The spectral separation refers to the amount spectral separation necessary for challenging of overlap between the detected low and high spectral imaging tasks such as differentiation of energy X-ray spectrum. Greater spectral separation bone marrow edema. The spectral separation can results in more reliable and quantitative material be evaluated quantitatively using the iodine ratio decomposition—relevant for better image quality, (ratio = [email protected] energy/[email protected] energy). A larger as illustrated in the figure below. iodine ratio means a better spectral separation. This Acquisition methods have unique levels of spectral ratio describes how well a material can be separated from soft tissue or water-like materials that have a separation. Techniques that can incorporate additional dedicated beam filtration (e.g., Dual ratio of 1. This is also directly related to radiation Source Dual Energy) have considerably improved dose: with better spectral separation, less dose is required to obtain the same image quality1,2. DE The single energy gray-scale image (left) does not allow for differentiation of the two materials. Spectral imaging with inferior spectral separation (middle; i.e., kV switching, dual layer detector, TwinBeam) allows material differentiation but with limited differentiation (noise in the green/orange material space). With excellent spectral separation, the differentiation is clear (right; i.e., Dual Source Dual Energy). 59 Dual Energy spectral imaging 2 Temporal coherence Temporal coherence denotes the time delay A low temporal coherence may lead to increased between the acquisition of the low- and high-energy misalignment between the low and high energy data. Ideally, this delay is as small as possible to images, which in turn may lead to artifacts in the avoid mis-registration due to motion or problems post-processed images (below). It is important to with contrast agent dynamics, e.g., a change in note that a high temporal coherence alone does contrast agent concentration over time. not help much without a good temporal resolution, which will be discussed on the next page. A low temporal coherence (left) in combination with moving objects can lead to artifacts. A high temporal coherence helps to avoid such problems. 60 Dual Energy spectral imaging 3 Temporal resolution The temporal resolution of the low- and high-energy The temporal resolution determines the amplitude images is defined as the time required to collect the of motion artifacts. Temporal resolution should be data for image reconstruction, which is usually a half clearly differentiated from temporal coherence, but rotation. This is independent of the spectral imaging they should be considered together. approach with the exception of Dual Source Dual Energy. In that case, special hardware and algorithms combine 90° of data from the two imaging chains to reconstruct images with a temporal resolution of about a quarter rotation time. With motion, a low temporal resolution (left) leads to blurred images. High temporal resolution (right) renders motion less problematic. 61 Dual Energy spectral imaging 4 Spatial resolution Spatial resolution, i.e., image “sharpness,” is It should also be mentioned that the detectability an important image quality parameter for the of small structures like iodine in small vessels or visualization of small objects as illustrated in the the characterization of small kidney stones is not figure below. Assuming that the image data is only related to the spatial resolution but also to the not already blurred from poor spectral separation, spectral separation. motion, or poor temporal resolution, the spatial resolution is mainly determined by focal spot size, detector element size, and the number of projections per rotation. DE DE Low spatial resolution (left) caused by a large focal spot or by a low number of projections makes clear visualization of objects difficult, especially for small structures. A high spatial resolution (right) generates a sharp delineation of objects. 62 Dual Energy spectral imaging 5 Dose efficiency Dual Energy spectral imaging can provide additional It is important to note that spectral separation also diagnostic information, however, this should plays an important role here since a system with not come at the expense of an increased patient limited spectral separation requires an increased dose compared to a conventional single energy radiation dose to achieve acceptable image quality. examination. Therefore, it is important that the Systems with dedicated filtration (e.g., Dual Source respective acquisition solutions incorporate all state- Dual Energy) achieve the highest spectral separation of-the-art dose reduction features like tube current without a dose comprise1,2. modulation or iterative reconstruction to allow dose neutral spectral imaging acquisitions. Higher dose is often used to compensate for poor dual energy image quality. However, the lack of spectral separation cannot be overcome despite increased dose. 63 Dual Energy spectral imaging 6 Workflow While the additional information from spectral Basic reconstruction and image processing with imaging has clear diagnostic advantages, image FAST DE and FAST DE Results acquisition and processing must not interfere With FAST DE, reconstruct only the images you need with clinical workflow. In order to overcome at the scanner including low energy, high energy, and these pitfalls, software features are required to mixed images (with an adjustable weighting factor)— automatically handle image data and send ready- sent directly to PACS. With FAST DE Results, process to-read images to PACS. standard spectral images (e.g., monoenergetic plus, virtual noncontrast, and iodine overlay images) at the scanner and directly send to PACS. Retrospective modification of algorithm parameters can be undertaken in syngo®.via if necessary. Standardized and Ready-to-read consistent image quality results wherever independent of operator PACS-Ready Workflow you are in your PACS environment SOMATOM CT scanner PACS 64 Dual Energy spectral imaging syngo.via Rapid Results and Recon&GO Improves your efficiency by reducing several workflow steps. Just define your workflow once and let it do the work It enables direct communication, triggering a zero-click for you, from virtual noncontrast images or iodine processing within the selected scan protocol. As a result, overlays—key in oncology cases and pulmonary embolism ready-to-read images are automatically created and sent assessment—to monoenergetic images for visualizing wherever you are, to your PACS. contrast improvements. Bring spectral imaging into your routine, without needing Equipped with this technology, you are prepared for any to change your clinical workflow. Automatically generate emergency—e.g., at night, when experienced technologists standard visualizations of different anatomies in the may not be available. required orientation and thickness. Read the way you want. See everything simultaneously. PACS-Ready solution to improve your efficiency without additional software. 65 Dual Energy spectral imaging Spectral imaging in routine How does it make an impact? Improve diagnostic accuracy in challenging cases by Improve efficiency, helping save time and reduce costs. improving visualization and providing quantitative information for personalized precision medicine. • An increase in diagnostic confidence may enable you to provide answers more quickly • Visualize subtly enhancing lesions with the ability to uncover obscure pathology • Characterize incidental findings as they are detected rather than waiting for additional workup • Characterize lesions based on visualization and quantification of iodine uptake • Potentially avoid rescans, additional workup, and separate noncontrast scan, thus reducing dose to patients • Enable quick clinical decision-making thru a rule in/rule out approach (e.g., PE, hemorrhage) • Reduce recalls for metal artifacts with virtual high keV images Answer more diagnostic questions by expanding • Automate bone removal in the head and body, freeing up beyond your conventional CT services. time for other tasks Identify bone marrow edema without MRI • Spectral imaging across our platforms may reduce the • need to triage patients to a certain scanner • Visualize uric acid crystals and evaluate gout burden 66 80 [HU] O [HU] Dual Energy spectral imaging The Dual Energy difference At Siemens Healthineers, we understand that you want better clinical answers, more confident decisions, and most importantly, early diagnoses. You want a CT solution that gets it right the first time, is easy to use, and is able to serve your entire patient population. Discover Dual Energy—it’s more than a feature, it’s the future—and that’s a world of difference. 68 69 At Siemens Healthineers, our purpose is to enable healthcare providers On account of certain regional limitations of sales rights and service to increase value by empowering them on their journey toward availability, we cannot guarantee that all products included in this expanding precision medicine, transforming care delivery, and brochure are available through the Siemens Healthineers sales improving patient experience, all enabled by digitalizing healthcare. organization worldwide. Availability and packaging may vary by country and is subject to change without prior notice. Some/All of the An estimated 5 million patients globally benefit every day from our features and products described herein may not be available in the innovative technologies and services in the areas of diagnostic and United States. therapeutic imaging, laboratory diagnostics and molecular medicine, as well as digital health and enterprise services. The information in this document contains general technical descriptions of specifications and options as well as standard and We are a leading medical technology company with over 170 years optional features, which do not always have to be present in of experience and 18,000 patents globally. With more than 48,000 individual cases. dedicated colleagues in 75 countries, we will continue to innovate and shape the future of healthcare. Siemens Healthineers reserves the right to modify the design, packaging, specifications, and options described herein without prior The outcomes and statements provided by customers of notice. For the most current information, please contact your local Siemens Healthineers are unique to each customer’s setting. Since sales representative from Siemens Healthineers. there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, and level of service/technology adoption), there can Note: Any technical data contained in this document may vary within be no guarantee that others will achieve the same results. defined tolerances. Original images always lose a certain amount of detail when reproduced. Resources 1Krauss B, Grant KL, Schmidt BT, Flohr TG. The importance of spectral separation: an assessment of dual energy spectral separation for quantitative ability and dose efficiency. Invest Radiol. 2015;50(2):114-118. 2Faby et al. Performance of today’s dual energy CT and future multi energy CT in virtual noncontrast imaging and in iodine quantifications: A simulation study. Med Phys. 2015;42(7):4349-4366. 3Wortman JR, Uyeda JW, Fulwadhva UP, Sodickson AD. Dual-Energy CT for Abdominal and Pelvic Trauma. Radiographics. 2018;38(2): 586-602. 4Wortman J; Sodickson A. Pearls, Pitfalls, and Problems in Dual-Energy Computed Tomography Imaging of the Body. Radiol Clin N Am. 2018;56:625-640. Siemens Healthineers USA Headquarters Siemens Medical Solutions USA, Inc. Siemens Healthcare GmbH Healthcare Henkestr. 127 40 Liberty Boulevard 91052 Erlangen, Germany Malvern, PA 19355-9998, USA Phone: +49 913184-0 Phone: +1-888-826-9702 Published by Siemens Medical Solutions USA, Inc. · Order No. CT-18-1167 · Printed in USA · 11-2018 · ©Siemens Medical Solutions USA, Inc., 2018 Published by Siemens Medical Solutions USA, Inc. · Order No. CT-18-1167 · Printed in USA · 11-2018 · ©Siemens Medical Solutions USA, Inc., 2018

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