Figure 1 - uploaded by Rajiv Gupta
Content may be subject to copyright.
Different dual-energy CT (DECT) scanners currently in clinical use. (A) Illustration of a dual source DECT, consisting of two source x-ray tubes with corresponding detectors; (B) Illustration of a single source DECT with rapid kVp switching. With this type of scanner, the tube voltage follows a pulsed curve, and projection data are collected twice for every projection, one at high and one at low tube voltage, during rapid kVp switching; (C) Illustration of a dual layer DECT, consisting of a single source and single (but layered) detector. The detector is composed of two scintillation layers enabling separation of high and low energy spectra produced by a single source.
Source publication
There is an increasing body of evidence establishing the advantages of dual-energy CT (DECT) for evaluation of head and neck squamous cell carcinoma (HNSCC). Focusing on a single-source DECT system with fast kVp switching, we will review the principles behind DECT and associated post-processing steps that make this technology especially suitable fo...
Similar publications
There are multiple emerging applications of dual-energy computed tomography (DECT) for the evaluation of pathology in the head and neck, in particular head and neck squamous cell carcinoma. Studies suggest that DECT image sets reconstructed as supplements to routine diagnostic images may improve lesion visualization, determination of tumor extent,...
Citations
... Aside from morphologic, size, and shape changes, iodine quantification has enabled an additional targeted analysis of tissue characteristics and organ perfusion in contrast-enhanced CT images [2]. Lam et al. [15] reported on an improved delineation of tumor edges of squamous cell carcinoma (one of the most common malignancies of the head and neck) on iodine overlay maps [16]. In another study on squamous cell carcinoma, Kuno et al. significantly increased the specificity of CT in the differentiation between healthy and tumor-infiltrated laryngeal cartilage via the application of iodine maps. ...
Background: Despite a considerable amount of literature on dual-energy CT (DECT) iodine uptake of the head and neck, the physiologic iodine uptake of this region has not been defined yet. This study aims to establish reference values for the iodine uptake of healthy organs to facilitate clinical application. Methods: Consecutive venous DECT scans of the head and neck were reviewed, and unremarkable exams were included (n = 617). A total of 35 region of interest measurements were performed in 16 anatomical regions. Iodine uptake was compared among different organs/tissues and subgroup analysis was performed (male (n = 403) vs. female (n = 214); young (n = 207) vs. middle-aged (n = 206) vs. old (n = 204); and normal weight (n = 314) vs. overweight (n = 196) vs. obese (n = 107)). Results: Overall mean iodine uptake values ranged between 0.5 and 9.4 mg/mL. Women showed higher iodine concentrations in the cervical vessels and higher uptake for the parotid gland, masseter muscle, submandibular glands, sublingual glands, palatine tonsils, tongue body, thyroid gland, and the sternocleidomastoid muscle than men (p ≤ 0.04). With increasing age, intravascular iodine concentrations increased as well as iodine uptake for cerebellum and thyroid gland, while values for the tongue and palatine tonsils were lower compared to younger subjects (p ≤ 0.03). Iodine concentrations for parotid glands and sternocleidomastoid muscles decreased with a higher BMI (p ≤ 0.004), while normal-weighted patients showed higher iodine values inside the jugular veins, other cervical glands, and tonsils versus patients with a higher BMI (p ≤ 0.04). Conclusion: physiologic iodine uptake values of cervical organs and tissues show gender-, age-, and BMI-related differences, which should be considered in the clinical routine of head and neck DECT.
... Aside from morphologic, size, and shape changes, iodine quantification has enabled an additional targeted analysis of tissue characteristics and organ perfusion in contrast-enhanced CT images [2]. Lam et al. [15] reported on an improved delineation of tumor edges of squamous cell carcinoma (one of the most common malignancies of the head and neck) on iodine overlay maps [16]. In another study on squamous cell carcinoma, Kuno et al. could significantly increase the specificity of CT in the differentiation between healthy and tumorinfiltrated laryngeal cartilage by application of iodine maps. ...
Purpose Despite a considerable amount of literature on dual-energy-CT(DECT) iodine uptake of the head and neck, the physiologic iodine uptake of this region has not been defined yet. This study aims to establish reference values for the iodine uptake of healthy organs to facilitate clinical application. Material and Methods: Consecutive venous DECT scans of head and neck were reviewed, and unremarkable exams were included (n=617). 35 region of interest measurements were performed in 16 anatomical regions. Iodine uptake was compared among different organs/tissues and subgroup analysis was performed (male [n=403] vs female [n=214]; young [n=207] vs middle-aged [n=206] vs old [n=204]; normal weight [n=314] vs overweight [n=196] vs obese [n=107]]). Results: Overall mean iodine uptake values ranged between 0.5 and 9.4mg/ml. Women showed higher iodine concentration in the cervical vessels and higher uptake for the parotid gland, masseter muscle, submandibular glands, sublingual glands, palatine tonsils, tongue body, thyroid gland, and the sternocleidomastoid muscle than men (p0.04). With increasing age, intravascular iodine concentrations increased as well as iodine uptake for cerebellum and thyroid gland, while values for tongue and palatine tonsils were lower compared to younger subjects (p0.03). Iodine concentrations for parotid glands and sternocleidomastoid muscles decreased with higher BMI (p0.004), while normal-weighted patients showed higher iodine values inside the jugular veins, other cervical glands, and tonsils versus patients with higher BMI (p0.04). Conclusion: Physiologic iodine uptake values of cervical organs and tissues show gender-, age-, and BMI-related differences, which should be considered in clinical routine of head and neck DECT.
... Therefore, the 2 scintillation layers can separate the high-and low-energy spectra. [26] MRI has traditionally been the gold standard for diagnosing BME [27] ; however, there may be situations where MRI is unavailable owing to contraindications or patient noncompliance. [28] There is an increasing interest in determining the extent to which DECT can reliably reflect BME. ...
Background
This systematic literature review and meta-analysis aimed to assess the accuracy, sensitivity, and specificity of dual-energy computed tomography (DECT) of the sacroiliac joint. Bone marrow edema (BME) of the sacroiliac joint is an early manifestation of some diseases, such as ankylosing spondylitis, and is usually examined by nuclear magnetic resonance imaging (MRI); however, MRI can be intolerable for some patients; hence, numerous studies have analyzed DECT examinations.
Methods
We searched PUBMED, CNKI, and EMBASE in 2023 for articles containing the following terms (DECT) or (DE-CT) or (dual-energy CT) or “dual-energy CT” or (dual-energy computed tomography) and ((sacroiliac joint) or (ankylosing spondylitis) or (sacroiliac arthritis) or (sacroiliitis)). An initial search identified 444 articles, of which 7 met the criteria. Data were extracted to calculate the sensitivity, specificity, and diagnostic odds for analysis using R software.
Results
Out of 291 patients and 577 sacroiliac joints, 429 (74.35%) exhibited BME. All studies used magnetic resonance as the control group. The overall sensitivity and specificity of DECT were 79%, and 92%, respectively, with positive prediction rate of 92.55% and negative prediction rate of 83.73%.
Conclusion
DECT appears to be a promising diagnostic tool for detecting BME in the sacroiliac joint and can be used as an alternative examination method for patients in whom MRI is contraindicated.
... DECT arises from the need to improve detection and discrimination in measurements of multi-material objects or objects with large variations in the aspect ratio, which has proven to be a challenge for single energy computed tomography (SECT) equipment 9 . Tissue attenuation depends not only on the energy spectrum of the X-ray beam, but also on the density and elemental composition of the material that it passes through 10 . ...
... The principle of DECT is to use two sets of data acquired with different X-ray spectra to form a set of volumetric images, which contain more information than either of them on their own. The fusion of data sets can be done before, after or in the iterative reconstruction 10 . ...
... La DECT surge de la necesidad de mejorar la detección y la discriminación en las mediciones de objetos multimateriales o de objetos con grandes variaciones en la relación de aspecto, lo cual ha demostrado ser un reto para los equipos de SECT (single energy computed tomography) 9 . La atenuación del tejido no depende solo del espectro de energía del haz de rayos X, sino también de la densidad y la composición elemental del material que este atraviesa 10 . ...
... El principio de la DECT consiste en utilizar dos conjuntos de datos adquiridos con diferentes espectros de rayos X para formar un conjunto de imágenes volumétricas, que contienen más información que cualquiera de ellos por separado. La fusión de los conjuntos de datos se puede realizar previa, posterior o en la reconstrucción iterativa 10 . ...
The implementation of dual energy computed tomography (DECT) equipment, among many other advantages, has allowed a substantial reduction in the dose of iodinated contrast media (ICM). This study constitutes the first part of a systematic review on the subject using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) through an electronic search in the Lilacs, PubMed, Scopus and Web of Science databases. Of 482 potential articles, 23 articles were ultimately included in this review. The results showed that it is feasible to reduce the MCY doses between 15.8% and 83% in DECT equipment, obtaining excellent image quality, with signal-to-noise ratio and contrast-to-noise ratio comparable or better than 120 kVp images obtained in conventional CT equipment with standard dose of MCY. The foregoing, thanks to the use of iterative reconstruction and noise reduction algorithms that allow the improving of low-energy images obtained by means of DECT.
... The major disadvantage of this method is the need of reducing the rotation speed of the system to acquire the extra projections and to account for the rise and fall times required for voltage modulation (Lam et al. 2015). Due to fast switching it is not possible to modulate the tube current between high and low energy simultaneously. ...
The multi-channel joint reconstruction technique is a highly suited method for multimodal medical imaging reconstruction. In the technique, the unknown images are reconstructed simultaneously by solving a single combined inverse problem and exploiting structural similarities between the images. The hypothesis behind this approach is that the image modalities inform each other during the reconstruction allowing artifact reduction and image quality enhancement. The present thesis develops three image reconstruction models for multi-channel image reconstruction. The first methodology consists of a Coupled Image-Motion Dictionary Learning algorithm for Motion Estimation Compensation in Cone-Beam Computed Tomography (CBCT). The second approach proposes a Multi-channel Convolutional Analysis Operator Learning (MCAOL) for Dual-Energy CT (DECT) Reconstruction. In the third technique, we focus on the sparse view single source fast KVp switching acquisition setup in Dual Energy CBCT to reduce the total dose delivered during a CT acquisition. The proposed methodologies were compared with the current state-of-the-art reconstruction algorithms for sparse-view and low-dose CT. The three methodologies outperform the methods used for comparison. They were published in peerreviewed journals and international conferences.
... Все вышеперечисленное, за исключением йодных карт, автор предлагает использовать для визуализации опухолей полости рта и ротоглотки и уменьшения дентальных артефактов [47]. Похожие данные приводит и другой коллектив учёных [48]. Изучение дифференциальной диагностики спектральной томографии в исключении остаточной или рецидивной опухоли после специального лечения приводится в работе международной группы авторов. ...
This study reviewed the head and neck cancer diagnosis publications using dual-energy computed tomography (DECT). The qualitative and quantitative analysis of the data was DECT obtained using intravenous contrast enhancement for localized tumors, which shows the importance of constructing iodine maps for obtaining additional diagnostic information. Including the article is described aspects of improving visualization of the oropharyngeal region against the background of artifacts from dental implants. Several research articles highlight the current state of the issue and the role of post-processing of raw data DECT, obtaining a range of monochromatic images of a tumor and other pathological changes in the head and neck region in the article. Several learned treatises were also reflected. DECT with intravenous contrast enhancement and routine computed tomography to reduce radiation exposure to patients were compared particularly due to the possibility of obtaining virtual native diagnostic images from a contrasting series of DECT volumes during post-processing. In addition, this review also includes references to works that highlight the development of DECT as the method. Finally, the physical principles underlying DECT and the prospects for the development of the method are briefly represented.
... However, using this information efficiently and finding the best balance in terms of image quality, reading time, and ease of interpretation is challenging. The use of spectral SCTbased virtual monoenergetic images (VMIs) and iodine maps (IMs) significantly improves the detection of tumor lesions [4][5][6][7][8][9][10]. Furthermore, VMIs and IMs have shown some potential to improve the diagnostic performance of CT in the differentiation of several types of tumors and pathologies and therapy monitoring in these patients [11][12][13][14]. ...
Background:
This study aimed to investigate the use of spectral computed tomography (SCT) hybrid images combining virtual monoenergetic images (VMIs) and iodine maps (IMs) as a potentially efficient search series for routine clinical imaging in patients with hypervascular abdominal tumors.
Methods:
A total of 69 patients with hypervascular abdominal tumors including neuroendocrine neoplasms (NENs, n = 48), renal cell carcinoma (RCC, n = 10), and primary hepatocellular carcinoma (HCC, n = 11) were analyzed retrospectively. Two radiological readers (blinded to clinical data) read three CT image sets (1st a reference set with 70 keV; 2nd a 50:50 hybrid 140 keV/40 keV set; 3rd a 50:50 hybrid 140 keV/IM set). They assessed images subjectively by rating several parameters including image contrast, visibility of suspicious lesions, and diagnostic confidence on five-point Likert scales. In addition, reading time was estimated.
Results:
Median subjective Likert scores were highest for the 1st set, except for image contrast, for which the 2nd set was rated highest. Scores for diagnostic confidence, artifacts, noise, and visibility of suspicious lesions or small structures were significantly higher for the 1st set than for the 2nd or 3rd set (p < 0.001). Regarding image contrast, the 2nd set was rated significantly higher than the 3rd set (p < 0.001), while the median did not differ significantly compared with the 1st set. Agreement between the two readers was high for all sets. Estimated potential reading time was the same for hybrid and reference sets.
Conclusions:
Hybrid images have the potential to efficiently exploit the additional information provided by SCT in patients with hypervascular abdominal tumors. However, the use of rigid weighting did not significantly improve diagnostic performance in this study.
... Therefore, the 2 scintillation layers enable a separation between the high and low energy spectra. 37 There are several limitations to this study as this is a systematic analysis and meta-analysis. Four studies were performed by Dr Diekhoff's group. ...
Background:
The purpose of this study was to perform a systematic literature review and meta-analysis to evaluate the sensitivity, specificity, and accuracy of dual-energy computed tomography (DE-CT) of bone marrow edema and disc edema in spine injuries.In vertebral injuries, prompt diagnosis is essential to avoid any delays in treatment. Conventional radiography may only reveal indirect signs of fractures, such as when it is displaced. Therefore, to detect the presence of bone marrow or disc edemas, adjunctive tools are required, such as magnetic resonance imaging (MRI) or DE-CT.
Methods:
Search terms included ((DECT) OR (DE-CT) OR (dual-energy CT) OR "Dual energy CT" OR (dual-energy computed tomography) OR (dual energy computed tomography)) AND ((spine) OR (vertebral)), and the PubMed, EMBASE, and MEDLINE databases and the Cochrane Library and Google were used. We found 1233 articles on our preliminary search, but only 13 articles met all criteria. Data were extracted to calculate the pooled sensitivity, specificity, and diagnostic odds ratio for analysis using R software.
Results:
Within the 13 studies, 515 patients, 3335 vertebrae, and 926 acute fractures (27.8%) defined by MRI were included. The largest cohort included 76 patients with 774 vertebrae. In 12 publications, MRI was reported for comparison. For DE-CT, the overall sensitivity was 86.2% with a specificity of 91.2% and accuracy of 89.3%. Furthermore, 5 studies reported the accuracy of CT with an overall sensitivity of 81.3%, specificity of 80.7%, and accuracy with 80.9%. Significant differences were found for specificity (P < .001) and accuracy (P = .023). However, significant interobserver differences were reported.
Conclusions:
DE-CT seems to be a promising diagnostic tool to detect bone marrow and disc edemas, which can potentially replace the current gold standard, the MRI.
Level of evidence:
2.
Clinical relevance:
This study shows that DE-CT seems to be a promising diagnostic tool with an accuracy of 89.3%.
... DECT is therefore interesting for applications with contrast media (5,6), e.g., the reconstruction of virtual non-enhanced images (7,8) or iodine maps (9,10). The quantification of iodine uptake using DECT iodine maps in patients with squamous cell carcinomas showed value for the prediction of recurrence after radiotherapy (11). ...
Background:
Dual-energy computed tomography (DECT) is increasingly used in studies and clinical practice. However, the best protocol is controversially discussed and whether it exhibits more radiation exposure compared to conventional protocols. Thus, the purpose of the study was to determine optimal tube current settings for DECT in a 3D-printed anthropomorphic phantom of the neck.
Methods:
A 3D-printed iodinated ink based phantom of a contrast enhanced CT of the neck was imaged. Six dual-energy multi-detector computed tomography scans were performed with six different tube currents (80 kVp: 30-400 mAs; 135 kVp: 5-160 mAs). 120 virtual blended images (VBIs) and 66 virtual monochromatic images (VMIs) were reconstructed and 12 regions of interest (bilaterally: common carotid arteries, subcutaneous soft tissue, mandibular bone, sternocleidomastoid muscle, submandibular gland, and mid-image: vertebral body of C2 and pharyngeal space) in six consecutive slices resulting in 96 measurements per scan were performed. Hounsfield units and signal- and contrast-to-noise ratio were compared to single-energy computed tomography as standard of reference.
Results:
VBIs overestimated the Hounsfield units (P<0.0001). Optimal dual-energy scanning parameters resulted in 120% (100 kVe: 51.2 vs. 61.7 and 65.2, for signal and contrast-to-noise ratio, respectively; 120 kVe: 60.8 vs. 72.1 vs. 128.3) of the radiation exposure with about 80% of the signal/contrast-to-noise ratio of the corresponding single-energy images. However, optimal weighting of tube currents for both voltages depended on the desired reconstruction.
Conclusions:
Dual-energy protocols apply an estimated 120% of the single-energy radiation exposure and result in approximately 80% of the image quality. Tube current settings should be adapted to the desired information.
