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PURPOSE: Breast density is a significant risk factor for breast cancer and can impact the sensitivity of screening mammography. Area-based breast density measurements may not provide an accurate representation of the tissue distribution, therefore volumetric breast density (VBD) measurements are preferred. Dual-energy mammography enables volumetric measurements without additional assumptions about breast shape. In this work we evaluated the performance of a dual-energy decomposition technique for determining VBD by applying it to virtual anthropomorphic phantoms. METHODS: The dual-energy decomposition formalism was used to quantify VBD on simulated dual-energy images of anthropomorphic virtual phantoms with known tissue distributions. We simulated 150 phantoms with volumes ranging from 50 to 709 mL and VBD ranging from 15% to 60%. Using these results, we validated a correction for the presence of skin and assessed the method's intrinsic bias and variability. As a proof of concept, the method was applied to 14 sets of clinical dual-energy images, and the resulting breast densities were compared to magnetic resonance imaging (MRI) measurements. RESULTS: Virtual phantom VBD measurements exhibited a strong correlation (Pearson's r > 0.95 $r > 0.95$ ) with nominal values. The proposed skin correction eliminated the variability due to breast size and reduced the bias in VBD to a constant value of -2%. Disagreement between clinical VBD measurements using MRI and dual-energy mammography was under 10%, and the difference in the distributions was statistically non-significant. VBD measurements in both modalities had a moderate correlation (Spearman's ρ $\rho \ $ = 0.68). CONCLUSIONS: Our results in virtual phantoms indicate that the material decomposition method can produce accurate VBD measurements if the presence of a third material (skin) is considered. The results from our proof of concept showed agreement between MRI and dual-energy mammography VBD. Assessment of VBD using dual-energy images could provide complementary information in dual-energy mammography and tomosynthesis examinations.

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Dual-energy CT has expanded the potential of thoracic imaging in both children and adults. Data processing allows material- and energy-specific reconstructions, which improve material differentiation and tissue characterization compared with single-energy CT. Material-specific reconstructions include iodine, virtual unenhanced, perfusion blood volume, and lung vessel images, which can improve assessment of vascular, mediastinal, and parenchymal abnormalities. The energy-specific reconstruction algorithm allows virtual monoenergetic reconstructions, including low-energy images to increase iodine conspicuity and high-energy images to reduce beam-hardening and metal artifacts. This review highlights dual-energy CT principles, hardware, and postprocessing algorithms; the clinical applications of dual-energy CT; and the potential benefits of photon counting (the most recently introduced iteration of spectral imaging) in pediatric thoracic imaging.

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Background Dual-energy CT enterography (DECTE) has been shown to be useful in characterizing Crohn disease activity compared with clinical markers of inflammation but, to the knowledge of the authors, comparison has not been made with histopathologic specimens. Purpose To compare mucosal iodine density obtained at DECTE from Crohn disease-affected bowel with histopathologic specimens from surgically resected ileocolectomy bowel segments or terminal ileum colonoscopic biopsies in the same patients. Materials and Methods This was a retrospective study. Bowel segments in adults with Crohn disease who underwent DECTE from January 2017 to April 2019 within 90 days of ileocolectomy or colonoscopy were retrospectively evaluated with prototype software allowing the semiautomatic determination of inner hyperdense bowel wall (mucosal) mean iodine density, normalized to the aorta. Mean normalized iodine density and clinical activity indexes (Crohn Disease Activity Index [CDAI] and Harvey-Bradshaw Index [HBI]) were compared with histologic active inflammation grades by using two-tailed t tests. Receiver operating characteristic curves were generated for mean normalized iodine density, CDAI, and HBI to determine sensitivity, specificity, and accuracy. A P value less than .05 was considered to indicate statistical significance. Results The following 16 patients were evaluated (mean age, 41 years ± 14 [standard deviation]): 10 patients (five men, five women; mean age, 41 years ± 15) with 19 surgical resection specimens and six patients with terminal ileum colonoscopic mucosal biopsies (four men, two women; mean age, 43 years ± 14). Mean normalized iodine density was 16.5% ± 5.7 for bowel segments with no active inflammation (n = 8) and 34.7% ± 9.7 for segments with any active inflammation (n = 17; P < .001). A 20% mean normalized iodine density threshold had sensitivity, specificity, and accuracy of 17 of 17 (100%; 95% CI: 80.5, 100), six of eight (75%; 95% CI: 35, 97), and 23 of 25 (92%; 95% CI: 74, 99), respectively, for active inflammation. Clinical indexes were similar for patients with and without active inflammation at histopathologic analysis (CDAI score, 261 vs 251, respectively [P = .77]; HBI score, 7.8 vs 6.4, respectively [P = .36]). Conclusion Iodine density from dual-energy CT enterography may be used as a radiologic marker of Crohn disease activity as correlated with histopathologic analysis. © RSNA, 2021 See also the editorial by Ohliger in this issue.

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Clinical use of dual-energy computed tomography (DECT) and dual-source computed tomography (DSCT) has been well established for more than a decade. Improved software and decreased postprocessing time have increased the advantages and availability of DECT and DSCT imaging. In this article, we will provide a practical guide for implementation of DECT and DSCT in clinical practice and discuss automated processing and selection of CT protocols in neurologic, cardiothoracic, vascular, body, and musculoskeletal imaging.

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OBJECTIVE: The aim of this study was to explore the usefulness of combined virtual monochromatic imaging and metal artifact reduction software (MARS) for the evaluation of musculoskeletal periprosthetic tissue. METHODS: Measurements were performed in periprosthetic and remote regions in 80 patients using a high-definition scanner. Polychromatic images with and without MARS and virtual monochromatic images were obtained. RESULTS: Periprosthetic polychromatic imaging (PI) showed significant differences compared with remote areas among the 3 tissues explored (P < 0.0001). No significant differences were observed between periprosthetic and remote tissues using monochromatic imaging with MARS (P = 0.053 bone, P = 0.32 soft tissue, and P = 0.13 fat). However, such differences were significant using PI with MARS among bone (P = 0.005) and fat (P = 0.02) tissues. All periprosthetic areas were noninterpretable using PI, compared with 11 (9%) using monochromatic imaging. CONCLUSIONS: The combined use of virtual monochromatic imaging and MARS reduced periprosthetic artifacts, achieving attenuation levels comparable to implant-free tissue.

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Las fracturas del fémur proximal, secundarias a caída de su altura, pacientes posmenopáusicas con osteoporosis, es un acontecimiento de fecuencia relativa. El médico tratante debe estar preparado para los eventos tanto pre como postoperatorio que suelen ocurrir. Se propone la creación de un Grupo de Atención Geriátrica (GAG) que enfoque los problemas médicos de este grupo de pacientes y sobre todo que tenga conocimiento de la osteoporosis, su dignóstico y tratamiento médico, para prevenir una nueva fracturas. Una vez que egresa del hospital se debe indicar una densitometría doble foton (DXA) e iniciar el tratamiento para la osteoporosis dos semanas luego del egreso y hasta el momento el ácido zoledronico es el único que ha demostrado que disminuye el riesgo de mortalidad y nueva fracturas.

A fracture of the proximal femur secondary to drop height in postmenopausal women with osteoporosis is a relative frequency of occurrence. The treating physician must be prepared for both pre-and postoperative events that do occur. It proposes the establishment of a Gerietric Care Group (GAG) that approach the medical problems of this group of patients and especially with knowledge of osteoporosis, its diagnosis and medical treatment to prevent a new fracture. Once discharged from the hospital should indicate two-photon densitometry (DXA) and initiate treatment for osteoporosis two weeks after graduation and until zoledronic acid is the only one that has been shown to decrease the risk of mortality and new fracture.

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Os valores de normalidade da densidade mineral óssea (DMO) da extremidade distal de rádio-ulna em 120 gatos clinicamente saudáveis foram determinados usando-se a técnica de densitometria óptica em imagens radiográficas. Para a padronização da técnica e interpretação da DMO, foi utilizado um programa computacional especialmente desenvolvido para a medida de densidade óptica em imagens radiográficas, que contém a imagem radiográfica da extremidade distal de rádio-ulna, e uma escala de alumínio (penetrômetro), usada como referencial densitométrico, permitindo a medida da densidade mineral óssea do rádio-ulna correspondente ao valor em milímetros da escala. Os valores médios da densidade mineral óssea da extremidade distal do rádio-ulna foram de 1,98 ± 0,52mmAl para os machos e de 1,76 ± 0,41mmAl para as fêmeas. Foram observadas correlações estatisticamente significativas entre a DMO, o peso e a idade dos animais estudados (P<0,0005).

The normal values of bone mineral density (BMD) at the distal end of the radius-ulna were established in 120 clinically healthy cats, using the technique of optical densitometry in radiographic images. The interpretation of BMD was performed using a computer software especially developed for measuring the optical density of the radiographic films, containing radiographic image of the distal extremity of the radius-ulna, and steps of an aluminum scale (penetrometer), used as a densitometric reference. This allowed the measurement of the BMD corresponding to the value in millimeters of the scale. The BMD mean values of the distal end of radius-ulna were: 1.98 ± 0.52mmAl for male and 1.76 ± 0.41 for female cats. Significant correlations were observed between BMD and weight and BMD and age (P<0.0005).

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O objetivo deste estudo foi avaliar se imagens digitalizadas obtidas de radiografias periapicais tomadas com tempo de exposiçäo reduzido podem ser melhoradas com o auxilio de um programa de computador (PhotoStyler) para tratamento digital. Foram empregadas radiografias de áreas de molares e pré-molares de mandíbulas secas, tomadas em série e padronizadas. Um total de 57 imagens equivalentes às radiografias com tempo de exposiçäo reduzido (60 por cento e 80 por cento do tempo considerado normal), digitalizadas e tratadas, foram submetidas à avaliaçäo de sete examinadores que as compararam com as imagens näo tratadas. Verificou-se que cerca de 80 por cento das imagens equivalentes às radiografias tomadas com reduçäo de 60 por cento da dose habitual foram consideradas de qualidade para elaboraçäo de diagnóstico. Quanto às imagens radiográficas tomadas com 80 por cento de reduçäo do tempo de exposiçäo, cerca de 50 por cento foram consideradas adequadas para o mesmo propósito

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