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1.
Acad Radiol ; 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32446765

RESUMO

RATIONALE AND OBJECTIVES: To evaluate the impact of noise-optimized virtual monoenergetic imaging (VMI) on lesion demarcation and measuring accuracy of hypoattenuating liver metastases in patients with fatty liver disease compared to standard reconstructions. MATERIALS AND METHODS: Twenty-eight patients (mean age 62.2 ± 7.7 years) with fatty liver disease and hypoattenuating liver metastases who underwent unenhanced and contrast-enhanced portal-venous dual-energy CT (DECT) were enrolled. Standard linearly blended and VMI series were reconstructed in 10-keV intervals. Lesion-to-parenchyma contrast-to-noise ratio (CNR) was calculated and the best VMI series was further investigated in a subjective evaluation of overall image quality and lesion demarcation. Size measurements were performed independently by measuring all hypodense lesions (n = 58) twice in a predefined sequence. Inter- and intra-rater agreement was assessed using intra-class correlation coefficient (ICC) statistics. RESULTS: The calculated CNR was greatest at 40-keV VMI (4.3 ± 2.6), significantly higher compared to standard reconstructions (2.9 ± 1.9; p < 0.001). Subjective ratings for overall image quality showed no significant difference between the 2 reconstruction techniques (both medians 4; p = 0.147), while lesion margin demarcation was found to be superior for 40-keV VMI (median 5; p ≤ 0.001). Inter- (ICC, 0.98 for 40-keV VMI; ICC, 0.93 for standard reconstruction) and intra-rater (ICC, 0.99 for 40-keV VMI; ICC, 0.94 for standard image series) analysis showed an excellent agreement for lesion measurements in both reconstruction techniques. CONCLUSION: Noise-optimized VMI reconstructions significantly improve contrast and lesion demarcation of hypoattenuating liver metastases in patients with the fatty liver disease compared to standard reconstruction.

3.
Eur Radiol Exp ; 4(1): 6, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31993795

RESUMO

BACKGROUND: Bone age (BA) assessment performed by artificial intelligence (AI) is of growing interest due to improved accuracy, precision and time efficiency in daily routine. The aim of this study was to investigate the accuracy and efficiency of a novel AI software version for automated BA assessment in comparison to the Greulich-Pyle method. METHODS: Radiographs of 514 patients were analysed in this retrospective study. Total BA was assessed independently by three blinded radiologists applying the GP method and by the AI software. Overall and gender-specific BA assessment results, as well as reading times of both approaches, were compared, while the reference BA was defined by two blinded experienced paediatric radiologists in consensus by application of the Greulich-Pyle method. RESULTS: Mean absolute deviation (MAD) and root mean square deviation (RSMD) were significantly lower between AI-derived BA and reference BA (MAD 0.34 years, RSMD 0.38 years) than between reader-calculated BA and reference BA (MAD 0.79 years, RSMD 0.89 years; p < 0.001). The correlation between AI-derived BA and reference BA (r = 0.99) was significantly higher than between reader-calculated BA and reference BA (r = 0.90; p < 0.001). No statistical difference was found in reader agreement and correlation analyses regarding gender (p = 0.241). Mean reading times were reduced by 87% using the AI system. CONCLUSIONS: A novel AI software enabled highly accurate automated BA assessment. It may improve efficiency in clinical routine by reducing reading times without compromising the accuracy compared with the Greulich-Pyle method.

4.
J Vasc Interv Radiol ; 31(2): 301-310, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31899107

RESUMO

PURPOSE: To examine predictive value of apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI) for response of patients with primary and secondary lung neoplasms undergoing transpulmonary chemoembolization (TPCE) and transarterial chemoperfusion (TACP) treatment. MATERIALS AND METHODS: Thirty-one patients (mean age ± SD 64 ± 12.4 y) with 42 lung target lesions (13 primary and 29 secondary) underwent DWI and subsequent ADC analysis on a 1.5T MR imaging scanner before and 30.3 days ± 6.4 after first session of TPCE or TACP. After 3.1 treatment sessions ± 1.4 performed in 2- to 4-week intervals, morphologic response was analyzed by comparing tumor diameter and volume before and after treatment on unenhanced T1-weighted MR images. On a per-lesion basis, response was classified according to Response Evaluation Criteria In Solid Tumors. RESULTS: Threshold ADC increase of 20.7% indicated volume response with 88% sensitivity and 78% specificity (area under the curve [AUC] = 0.84). Differences between ADC changes in volume response groups were significant (P = .002). AUC for volume response predicted by ADC before treatment was 0.77. Median ADC before treatment and mean ADC change were 1.09 × 10-3 mm2/second and 0.36 × 10-3 mm2/second ± 0.23, 1.45 × 10-3 mm2/second and 0.14 × 10-3 mm2/second ± 0.16, and 1.30 × 10-3 mm2/second and 0.06 × 10-3 mm2/second ± 0.19 in partial response, stable disease, and progressive disease groups. In primary lung cancer lesions, strong negative correlation of ADC change with change in diameter (ρ = -.87, P < .001) and volume (ρ = -.66, P = .016) was found. In metastases, respective correlation coefficients were ρ = -.18 (P = .356) and ρ = -.35 (P = .061). CONCLUSIONS: ADC quantification shows considerable diagnostic value for predicting response and monitoring TPCE and TACP treatment of patients with primary and secondary lung neoplasms.

5.
Radiol Med ; 125(4): 384-397, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31925704

RESUMO

Unlike conventional computed tomography, dual-energy computed tomography is a relatively novel technique that exploits ionizing radiations at different energy levels. The separate radiation sets can be achieved through different technologies, such as dual source, dual layers or rapid switching voltage. Body tissue molecules vary for their specific atomic numbers and electron density, and the interaction with different sets of radiations results in different attenuations, allowing to their final distinction. In particular, iodine recognition and quantification have led to important information about intravenous contrast medium delivery within the body. Over the years, useful post-processing algorithms have also been validated for improving tissue characterization. For instance, contrast resolution improvement and metal artifact reduction can be obtained through virtual monoenergetic images, dose reduction by virtual non-contrast reconstructions and iodine distribution highlighting through iodine overlay maps. Beyond the evaluation of the abdominal organs, dual-energy computed tomography has also been successfully employed in other anatomical districts. Although lung perfusion is one of the most investigated, this evaluation has been extended to narrowly fields of application, such as musculoskeletal, head and neck, vascular and cardiac. The potential pool of information provided by dual-energy technology is already wide and not completely explored, yet. Therefore, its performance continues to raise increasing interest from both radiologists and clinicians.


Assuntos
Extremidades/diagnóstico por imagem , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Abdome/diagnóstico por imagem , Humanos
6.
Eur J Radiol ; 122: 108666, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31786506

RESUMO

PURPOSE: To define optimal kiloelectron volt (keV) settings for virtual monoenergetic imaging (VMI) reconstruction at dual-energy coronary computed tomography angiography (DE-CCTA). METHOD: Fifty-one DE-CCTA data sets (33 men; mean age, 63.9 ±â€¯13.2 years) were reconstructed as standard linearly-blended images (F_0.6; 60% of 90 kVp, 40% of 150 kVpSn), and with traditional (VMI) and noise-optimised (VMI+) algorithms from 40 to 100 keV in 10-keV intervals. Objective image quality was assessed with signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements. Three observers subjectively evaluated vascular contrast, image sharpness, noise and delineation of coronary plaques. RESULTS: Median values for objective image analysis were highest in VMI + series at 40 keV (SNR, 44.5; CNR: 33.5), significantly superior (allp < 0.001) to the best VMI series at 70 keV (SNR, 28.1; CNR, 18.4) and standard F_0.6 images (SNR, 23.2; CNR, 15.6). Overall subjective metrics achieved higher scores at 40-keV VMI+ series in comparison to 70-keV VMI series and F_0.6 images (all p < 0.001), with optimal vascular contrast (5; ICC, 0.90), good image sharpness (4; 0.88), low noise (4; 0.82), and optimal plaque delineation (5; 0.89). CONCLUSIONS: DE-CCTA image reconstruction with 40-keV VMI + allows for significant improvement of both objective and subjective image quality.

7.
Eur Radiol ; 30(1): 141-150, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31350586

RESUMO

OBJECTIVES: To evaluate the diagnostic accuracy of dual-energy computed tomography (CT) virtual non-calcium (VNCa) reconstructions for the depiction of traumatic knee bone marrow edema. METHODS: Fifty-seven patients (mean age, 50 years; range, 20-82 years) with acute knee trauma further divided into 30 women and 27 men, who had undergone third-generation dual-source dual-energy CT and 3-T magnetic resonance imaging (MRI) within 7 days between January 2017 and May 2018, were retrospectively analyzed. Six radiologists, blinded to clinical and MRI information, independently analyzed conventional grayscale dual-energy CT series for fractures; after 8 weeks, readers evaluated color-coded VNCa reconstructions for the presence of bone marrow edema in six femoral and six tibial regions. Quantitative analysis of CT numbers on VNCa reconstructions was performed by a seventh radiologist. Two additional radiologists, blinded to clinical and CT information, analyzed MRI series in consensus to define the reference standard. Sensitivity, specificity, and the area under the curve (AUC) were the primary metrics of diagnostic accuracy. RESULTS: MRI revealed 197 areas with bone marrow edema (91/342 femoral, 106/342 tibial). In the qualitative analysis, VNCa showed high overall sensitivity (1108/1182 [94%]) and specificity (2789/2922 [95%]) for depicting bone marrow edema. The AUC was 0.96 (femur) and 0.97 (tibia). A cutoff value of - 51 Hounsfield units (HU) provided high sensitivity (102/106 [96%]) and specificity (229/236 [97%]) for differentiating tibial bone marrow edema. CONCLUSIONS: In both quantitative and qualitative analyses, dual-energy CT VNCa reconstructions yielded excellent diagnostic accuracy for depicting traumatic knee bone marrow edema compared with MRI. KEY POINTS: • Dual-energy CT (DECT) virtual non-calcium (VNCa) reconstructions are highly accurate in depicting bone marrow edema of the femur and tibia. • Diagnostic confidence, image noise, and image quality were rated as equivalent in VNCa reconstructions and MRI (magnetic resonance imaging) series. • VNCa images may serve as an alternative imaging approach to MRI.


Assuntos
Doenças da Medula Óssea/patologia , Edema/patologia , Fraturas Ósseas/patologia , Traumatismos do Joelho , Tomografia Computadorizada por Raios X/métodos , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Cálcio , Feminino , Humanos , Traumatismos do Joelho/diagnóstico por imagem , Traumatismos do Joelho/patologia , Articulação do Joelho/patologia , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade , Tíbia/patologia , Adulto Jovem
8.
Acad Radiol ; 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31727567

RESUMO

RATIONALE AND OBJECTIVES: To compare dual-energy CT virtual monoenergetic images (VMI) and standard reconstructions for reliability of quantitative size measurements and diagnostic accuracy for the detection of colorectal liver metastases (CRLM). MATERIALS AND METHODS: We retrospectively included 98 patients (mean age, 61.1±11.5 years) with colorectal cancer, of whom 49 subjects had CRLM. All patients underwent a portal-venous phase dual-energy CT examination. Standard linearly-blended reformats and 40-keV VMI were reconstructed. For both reconstruction techniques, two blinded readers performed measurements of CRLM twice in a preset sequence. Three additional radiologists independently assessed all liver lesions in terms of dignity (benign vs. malignant). Sensitivity, specificity and diagnostic accuracy were calculated on a per-patient basis using MRI as reference standard. Readers scored the suitability for metric measurements and their diagnostic confidence using 5-point Likert scales. Inter-rater agreement was evaluated using intraclass correlation coefficient (ICC). RESULTS: Inter-rater agreement for lesion size measurements was higher for 40-keV VMI (ICC, 0.88) compared to standard linearly-blended series (ICC, 0.80). Sensitivity and diagnostic accuracy for the detection of CRLM were significantly higher for VMI at 40-keV compared to standard reconstructions (90.6% vs. 80.6%, and 89.1% vs. 81.3%; p < 0.001). Reader scores indicated that 40-keV VMI were more suitable for metric lesion measurements and provided greater diagnostic confidence compared to standard reformats (median, 5 vs. 3, and 5 vs. 4; both p < 0.001). CONCLUSION: Low-keV VMI reconstructions improve reliability of quantitative size measurements and diagnostic accuracy for the assessment of CRLM compared to standard linearly-blended images.

9.
Am J Cardiol ; 124(9): 1340-1348, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31481177

RESUMO

This study investigated the impact of coronary CT angiography (cCTA)-derived plaque markers and machine-learning-based CT-derived fractional flow reserve (CT-FFR) to identify adverse cardiac outcome. Data of 82 patients (60 ± 11 years, 62% men) who underwent cCTA and invasive coronary angiography (ICA) were analyzed in this single-center retrospective, institutional review board-approved, HIPAA-compliant study. Follow-up was performed to record major adverse cardiac events (MACE). Plaque quantification of lesions responsible for MACE and control lesions was retrospectively performed semiautomatically from cCTA together with machine-learning based CT-FFR. The discriminatory value of plaque markers and CT-FFR to predict MACE was evaluated. After a median follow-up of 18.5 months (interquartile range 11.5 to 26.6 months), MACE was observed in 18 patients (21%). In a multivariate analysis the following markers were predictors of MACE (odds ratio [OR]): lesion length (OR 1.16, p = 0.018), low-attenuation plaque (<30 HU) (OR 4.59, p = 0.003), Napkin ring sign (OR 2.71, p = 0.034), stenosis ≥50% (OR 3.83, p 0.042), and CT-FFR ≤0.80 (OR 7.78, p = 0.001). Receiver operating characteristics analysis including stenosis ≥50%, plaque markers and CT-FFR ≤0.80 (Area under the curve 0.94) showed incremental discriminatory power over stenosis ≥50% alone (Area under the curve 0.60, p <0.0001) for the prediction of MACE. cCTA-derived plaque markers and machine-learning CT-FFR demonstrate predictive value to identify MACE. In conclusion, combining plaque markers with machine-learning CT-FFR shows incremental discriminatory power over cCTA stenosis grading alone.

10.
Eur J Radiol ; 119: 108657, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31521876

RESUMO

PURPOSE: This study investigated the impact of gender differences on the diagnostic performance of machine-learning based coronary CT angiography (cCTA)-derived fractional flow reserve (CT-FFRML) for the detection of lesion-specific ischemia. METHOD: Five centers enrolled 351 patients (73.5% male) with 525 vessels in the MACHINE (Machine leArning Based CT angiograpHy derIved FFR: a Multi-ceNtEr) registry. CT-FFRML and invasive FFR ≤ 0.80 were considered hemodynamically significant, whereas cCTA luminal stenosis ≥50% was considered obstructive. The diagnostic performance to assess lesion-specific ischemia in both men and women was assessed on a per-vessel basis. RESULTS: In total, 398 vessels in men and 127 vessels in women were included. Compared to invasive FFR, CT-FFRML reached a sensitivity, specificity, positive predictive value, and negative predictive value of 78% (95%CI 72-84), 79% (95%CI 73-84), 75% (95%CI 69-79), and 82% (95%CI: 76-86) in men vs. 75% (95%CI 58-88), 81 (95%CI 72-89), 61% (95%CI 50-72) and 89% (95%CI 82-94) in women, respectively. CT-FFRML showed no statistically significant difference in the area under the receiver-operating characteristic curve (AUC) in men vs. women (AUC: 0.83 [95%CI 0.79-0.87] vs. 0.83 [95%CI 0.75-0.89], p = 0.89). CT-FFRML was not superior to cCTA alone [AUC: 0.83 (95%CI: 0.75-0.89) vs. 0.74 (95%CI: 0.65-0.81), p = 0.12] in women, but showed a statistically significant improvement in men [0.83 (95%CI: 0.79-0.87) vs. 0.76 (95%CI: 0.71-0.80), p = 0.007]. CONCLUSIONS: Machine-learning based CT-FFR performs equally in men and women with superior diagnostic performance over cCTA alone for the detection of lesion-specific ischemia.


Assuntos
Angiografia por Tomografia Computadorizada/normas , Estenose Coronária/diagnóstico por imagem , Isquemia Miocárdica/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Angiografia Coronária/métodos , Angiografia Coronária/normas , Estenose Coronária/fisiopatologia , Métodos Epidemiológicos , Feminino , Reserva Fracionada de Fluxo Miocárdico/fisiologia , Hemodinâmica/fisiologia , Humanos , Aprendizado de Máquina , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/fisiopatologia , Fatores Sexuais , Tomografia Computadorizada Espiral/métodos , Tomografia Computadorizada Espiral/normas
11.
Radiology ; 293(2): 260-271, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31502938

RESUMO

In this article, the authors discuss the technical background and summarize the current body of literature regarding virtual monoenergetic (VM) images derived from dual-energy CT data, which can be reconstructed between 40 and 200 keV. Substantially improved iodine attenuation at lower kiloelectron volt levels and reduced beam-hardening artifacts at higher kiloelectron volt levels have been demonstrated from all major manufacturers of dual-energy CT units. Improved contrast attenuation with VM imaging at lower kiloelectron volt levels enables better delineation and diagnostic accuracy in the detection of various vascular or oncologic abnormalities. Low-kiloelectron-volt VM imaging may be useful for salvaging CT studies with suboptimal contrast material delivery or providing additional information on the arterial vasculature obtained from venous phase acquisitions. For patients with renal impairment, substantial reductions in the use of iodinated contrast material can be achieved by using lower-energy VM imaging. The authors recommend routine reconstruction of VM images at 50 keV when using dual-energy CT to exploit the increased contrast properties. For reduction of beam-hardening artifacts, VM imaging at 120 keV is useful for the initial assessment.

12.
Artigo em Inglês | MEDLINE | ID: mdl-31422141

RESUMO

OBJECTIVES: This study was conducted to investigate the influence of coronary artery calcium (CAC) score on the diagnostic performance of machine-learning-based coronary computed tomography (CT) angiography (cCTA)-derived fractional flow reserve (CT-FFR). BACKGROUND: CT-FFR is used reliably to detect lesion-specific ischemia. Novel CT-FFR algorithms using machine-learning artificial intelligence techniques perform fast and require less complex computational fluid dynamics. Yet, influence of CAC score on diagnostic performance of the machine-learning approach has not been investigated. METHODS: Four hundred eighty-two vessels from 314 patients (62.3 ± 9.3 years, 77% male) who underwent cCTA followed by invasive FFR were investigated from the MACHINE (Machine Learning based CT Angiography derived FFR: a Multi-center Registry) registry data. CAC scores were quantified using the Agatston convention. The diagnostic performance of CT-FFR to detect lesion-specific ischemia was assessed across all Agatston score categories (CAC 0, >0 to <100, 100 to <400, and ≥400) on a per-vessel level with invasive FFR as the reference standard. RESULTS: The diagnostic accuracy of CT-FFR versus invasive FFR was superior to cCTA alone on a per-vessel level (78% vs. 60%) and per patient level (83% vs. 73%) across all Agatston score categories. No statistically significant differences in the diagnostic accuracy, sensitivity, or specificity of CT-FFR were observed across the categories. CT-FFR showed good discriminatory power in vessels with high Agatston scores (CAC ≥ 400) and high performance in low-to-intermediate Agatston scores (CAC >0 to <400) with a statistically significant difference in the area under the receiver-operating characteristic curve (AUC) (AUC: 0.71 [95% confidence interval (CI): 0.57-0.85] vs. 0.85 [95% CI: 0.82-0.89], p = 0.04). CT-FFR showed superior diagnostic value over cCTA in vessels with high Agatston scores (CAC ≥ 400: AUC 0.71 vs. 0.55, p = 0.04) and low-to-intermediate Agatston scores (CAC >0 to <400: AUC 0.86 vs. 0.63, p < 0.001). CONCLUSIONS: Machine-learning-based CT-FFR showed superior diagnostic performance over cCTA alone in CAC with a significant difference in the performance of CT-FFR as calcium burden/Agatston calcium score increased. (Machine Learning Based CT Angiography Derived FFR: a Multicenter, Registry [MACHINE] NCT02805621).

13.
Eur J Radiol ; 118: 207-214, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31439244

RESUMO

PURPOSE: To investigate the diagnostic accuracy of dual-energy computed tomography (CT) virtual non-calcium (VNCa) reconstructions for the depiction of traumatic bone marrow edema of the calcaneus. METHOD: Data from 62 patients (33 women, 29 men; mean age: 41 years, range: 19-84 years) with acute tarsal trauma who had undergone third-generation dual-source dual-energy CT and 3-T magnetic resonance imaging (MRI) within seven days between January 2017 and July 2018 were retrospectively analyzed. Five radiologists, blinded to clinical and MRI information, independently assessed conventional grayscale dual-energy CT series for the presence of fractures; after at least eight weeks, readers re-evaluated all cases using color-coded VNCa reconstructions for the presence of bone marrow edema. Quantitative analysis of CT numbers on VNCa reconstructions was performed by a sixth radiologist. Two additional experienced radiologists, blinded to clinical and CT information, assessed MRI series in consensus to define the reference standard. Sensitivity, specificity and the area under the curve (AUC) were the primary indices for diagnostic accuracy. RESULTS: MRI revealed 62 areas with bone marrow edema in 39 patients. In the qualitative analysis, VNCa showed high overall sensitivity (286/310 [92%]) and specificity (899/930 [97%]) for the depiction of bone marrow edema. A cut-off value of -53 Hounsfield units (HU) provided a sensitivity of 82% (51/62) and specificity of 95% (176/186]) for differentiating bone marrow edema. The overall AUC was 0.98. CONCLUSIONS: In both quantitative and qualitative analyses, dual-energy CT VNCa reconstructions show excellent diagnostic accuracy for the visualization of traumatic calcaneal bone marrow edema compared to MRI.


Assuntos
Medula Óssea/diagnóstico por imagem , Calcâneo/diagnóstico por imagem , Edema/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Medula Óssea/patologia , Doenças da Medula Óssea/patologia , Calcâneo/patologia , Cor , Edema/patologia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , Adulto Jovem
14.
Eur J Radiol ; 116: 68-75, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31153576

RESUMO

PURPOSE: To investigate and optimize the impact of different exposure parameters on image quality and radiation dose for a latest generation orthopedic cone-beam CT system. MATERIALS AND METHODS: 110 consecutive scans of the same cadaver forearm were performed before and after the insertion of a distal radius plate on the palmar radius to achieve highest intra-individual comparability. All scans were conducted on a latest generation cone-beam CT scanner (Carestream OnSight 3D Extremity System, Carestream Health, Rochester, NY, USA). Extremity imaging was performed using different combinations of tube voltage (kV) and tube current - exposure time product (mAs). Radiation dose (DLP and CTDIVOL) was recorded to widely varying combinations. Subjective and objective image quality analysis included a blinded evaluation by five different readers independently using 5-point-Likert scales. RESULTS: Highest radiation dose was achieved using the manufacturers' suggested standard protocol (90-kV and 5.0 mAs with DLP of 111.91 mGy*cm and CTDIVOL of 4.49 mGy), while 70-kV and 2.0 mAs provided the most dose reduction with DLP of 20.34 mGy*cm and CTDIVOL of 0.79 mGy. Regarding subjective image quality, higher tube voltage improved depiction of cortical bone (p ≤ 0.038) and cancellous bone (p ≤ 0.001) as well as overall image quality (p ≤ 0.027). Changes of the tube current - exposure time product did not show significant alterations of image quality (p ≥ 0.063). After plate insertion, only the subjective overall image quality showed reduced subjective perception (p < 0.001). Between the different scan protocols, no relevant changes were observed in the objective image quality analysis (SNR: p ≥ 0.125; CNR: p ≥ 0.086). However, presence of osteosynthesis significantly lowered the mean SNR and CNR (p < 0.001). CONCLUSION: Even with lowest exposure settings, orthopedic extremity CBCT revealed good overall image quality. The best result regarding subjective image quality was achieved with 85-kV / 4.7 mAs with a dose reduction of 18,9% compared to the manufacturer's recommended protocol (90-kV and 5.0 mAs).


Assuntos
Braço/anatomia & histologia , Tomografia Computadorizada de Feixe Cônico/métodos , Doses de Radiação , Cadáver , Humanos
15.
Br J Radiol ; 92(1098): 20180546, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30919651

RESUMO

Dual energy CT (DECT) has evolved into a commonly applied imaging technique in clinical routine due to its unique post-processing opportunities for improved evaluation of all body areas. Reconstruction of virtual monoenergetic imaging (VMI) series has shown beneficial effects for both non-contrast and contrast-enhanced DECT due to the flexibility to calculate low-keV VMI reconstructions to increase contrast and iodine attenuation, or to compute high-keV VMI reconstructions to reduce beam-hardening artefacts. The goal of this review article is to explain the technical background of VMI and noise-optimized VMI+ algorithms and to give an overview of useful clinical applications of the VMI technique in DECT of various body regions.


Assuntos
Tomografia Computadorizada por Raios X/métodos , Algoritmos , Artefatos , Sistema Cardiovascular/diagnóstico por imagem , Cabeça/diagnóstico por imagem , Humanos , Pulmão/diagnóstico por imagem , Sistema Musculoesquelético/diagnóstico por imagem , Pescoço/diagnóstico por imagem , Ruído , Radiografia Abdominal/métodos , Interface Usuário-Computador
16.
Eur Heart J Cardiovasc Imaging ; 20(6): 636-643, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30789223

RESUMO

AIMS: Increased attenuation of pericoronary adipose tissue (PCAT) around the proximal right coronary artery (RCA) from coronary computed tomography angiography (CTA) has been shown to be associated with coronary inflammation and improved prediction of cardiac death over plaque features. Our aim was to investigate whether PCAT CT attenuation is related to progression of coronary plaque burden. METHODS AND RESULTS: We analysed CTA studies of 111 stable patients (age 59.2 ± 9.8 years, 77% male) who underwent sequential CTA (3.4 ± 1.6 years between scans) with identical acquisition protocols. Total plaque (TP), calcified plaque (CP), non-calcified plaque (NCP), and low-density non-calcified plaque (LD-NCP) volumes and corresponding burden (plaque volume × 100%/vessel volume) were quantified using semi-automated software. PCAT CT attenuation (HU) was measured around the proximal RCA, the most standardized method for PCAT analysis. Patients with an increase in NCP burden (n = 51) showed an increase in PCAT attenuation, whereas patients with a decrease in NCP burden (n = 60) showed a decrease {4.4 [95% confidence interval (CI) 2.6-6.2] vs. -2.78 (95% CI -4.6 to -1.0) HU, P < 0.0001}. Changes in PCAT attenuation correlated with changes in the burden of NCP (r = 0.55, P < 0.001) and LD-NCP (r = 0.24, P = 0.01); but not CP burden (P = 0.3). Increased baseline PCAT attenuation ≥-75 HU was independently associated with increase in NCP (odds ratio 3.07, 95% CI 1.4-7.0; P < 0.008) and TP burden on follow-up CTA. CONCLUSION: PCAT attenuation measured from routine CTA is related to the progression of NCP and TP burden. This imaging biomarker may help to identify patients at increased risk of high-risk plaque progression and allow monitoring of beneficial changes from medical therapy.

17.
Eur Radiol ; 29(9): 4783-4793, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30805703

RESUMO

OBJECTIVES: To investigate the diagnostic accuracy of a modified three-material decomposition calcium subtraction (CS) algorithm for the detection of arterial stenosis in dual-energy CT angiography (DE-CTA) of the lower extremity runoff compared to standard image reconstruction, using digital subtraction angiography (DSA) as the reference standard. METHODS: Eighty-eight patients (53 males; mean age, 65.9 ± 11 years) with suspected peripheral arterial disease (PAD) who had undergone a DE-CTA examination of the lower extremity runoff between May 2014 and May 2015 were included in this IRB-approved, HIPAA-compliant retrospective study. Standard linearly blended and CS images were reconstructed and vascular contrast-to-noise ratios (CNR) were calculated. Two independent observers assessed subjective image quality using a 5-point Likert scale. Diagnostic accuracy for ≥ 50% stenosis detection was analyzed in a subgroup of 45 patients who had undergone additional DSA. Diagnostic accuracy parameters were estimated with a random-effects logistic regression analysis and compared using generalized estimating equations. RESULTS: CS datasets showed higher CNR (15.3 ± 7.3) compared to standard reconstructions (13.5 ± 6.5, p < 0.001). Both reconstructions showed comparable qualitative image quality scores (CS, 4.64; standard, 4.57; p = 0.220). Diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) for CS reconstructions was 96.5% (97.5%, 95.6%, 90.9%, 98.1) and 93.1% (98.8%, 90.4%, 82.3%, 99.1%) for standard images. CONCLUSIONS: A modified three-material decomposition CS algorithm provides increased vascular CNR, equivalent qualitative image quality, and greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff on DE-CTA compared with standard image reconstruction. KEY POINTS: • Calcified plaques may lead to overestimation of stenosis severity and false positive results, requiring additional invasive digital subtraction angiography (DSA). • A modified three-material decomposition algorithm for calcium subtraction provides greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff compared with standard image reconstruction. • The application of this algorithm in patients with heavily calcified vessels may be helpful to potentially reduce inconclusive CT angiography examinations and the need for subsequent invasive DSA.


Assuntos
Angiografia Digital/métodos , Arteriopatias Oclusivas/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Extremidade Inferior/irrigação sanguínea , Idoso , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , Calcificação Vascular/diagnóstico por imagem
18.
Radiology ; 290(2): 446-455, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30615548

RESUMO

Purpose To assess the diagnostic performance of dual-energy CT with reconstruction of virtual noncalcium (VNCa) images for the detection of lumbar disk herniation compared with standard CT image reconstruction. Materials and Methods For this retrospective study, 41 patients (243 intervertebral disks; overall mean age, 68 years; 24 women [mean age, 68 years] and 17 men [mean age, 68 years]) underwent clinically indicated third-generation, dual-source, dual-energy CT and 3.0-T MRI within 2 weeks between March 2017 and January 2018. Six radiologists, blinded to clinical and MRI information, independently evaluated conventional gray-scale dual-energy CT series for the presence and degree of lumbar disk herniation and spinal nerve root impingement. After 8 weeks, readers reevaluated examinations by using color-coded VNCa reconstructions. MRI evaluated by two separate experienced readers, blinded to clinical and dual-energy CT information, served as the standard of reference. Sensitivity and specificity were the primary metrics of diagnostic performance. Results A total of 112 herniated lumbar disks were depicted at MRI. VNCa showed higher overall sensitivity (612 of 672 [91%] vs 534 of 672 [80%]) and specificity (723 of 786 [92%] vs 665 of 786 [85%]) for detecting lumbar disk herniation compared with standard CT (all comparisons, P < .001). Interreader agreement was excellent for VNCa and substantial for standard CT (κ = 0.82 vs 0.67; P < .001). VNCa achieved superior diagnostic confidence, image quality, and noise scores compared with standard CT (all comparisons, P < .001). Conclusion Color-coded dual-energy CT virtual noncalcium reconstructions show substantially higher diagnostic performance and confidence for depicting lumbar disk herniation compared with standard CT. © RSNA, 2018.


Assuntos
Degeneração do Disco Intervertebral/diagnóstico por imagem , Deslocamento do Disco Intervertebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Disco Intervertebral/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade
19.
Eur Radiol ; 29(9): 4603-4612, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30666446

RESUMO

OBJECTIVES: To evaluate radiation exposure and image quality in matched patient cohorts for CT pulmonary angiography (CTPA) acquired in single- and dual-energy mode using second- and third-generation dual-source CT (DSCT) systems. METHODS: We retrospectively included 200 patients (mean age, 65.5 years ± 15.7 years) with suspected pulmonary embolism-equally divided into four study groups (n = 50) and matched by gender and body mass index. CTPA was performed with vendor-predefined second-generation (group A, 100-kV single-energy computed tomography (SECT); group B, 80/Sn140-kV dual-energy computed tomography (DECT)) or third-generation DSCT (group C, 100-kV SECT; group D, 90/Sn150-kV DECT) devices. Radiation metrics were assessed using a normalized scan range of 27.5 cm. For objective image quality evaluation, dose-independent figure-of-merit (FOM) contrast-to-noise ratios (CNRs) were calculated. Subjective image analysis included ratings for overall image quality, reader confidence, and image artifacts using five-point Likert scales. RESULTS: Calculations of the effective dose (ED) of radiation for a normalized scan range of 27.5 cm showed nonsignificant differences between SECT and DECT acquisitions for each scanner generation (p ≥ 0.253). The mean effective radiation dose was lower for third-generation groups C (1.5 mSv ± 0.8 mSv) and D (1.4 mSv ± 0.7 mSv) compared to second-generation groups A (2.5 mSv ± 0.9 mSv) and B (2.3 mSv ± 0.6 mSv) (both p ≤ 0.013). FOM-CNR measurements were highest for group D. Qualitative image parameters of overall image quality, reader confidence, and image artifacts showed nonsignificant differences among the four groups (p ≥ 0.162). CONCLUSIONS: Third-generation DSCT systems show lower radiation dose parameters for CTPA compared to second-generation DSCT. DECT can be performed with both scanner generations without radiation dose penalty or detrimental effects on image quality compared to SECT. KEY POINTS: • Radiation exposure showed nonsignificant differences between SECT and DECT for both DSCT scanner devices. • Dual-energy CTPA provides equivalent image quality compared to standard image acquisition. • Subjective image quality assessment was similar among the four study groups.


Assuntos
Angiografia por Tomografia Computadorizada/métodos , Embolia Pulmonar/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Angiografia por Tomografia Computadorizada/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doses de Radiação , Exposição à Radiação/análise , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Estudos Retrospectivos , Adulto Jovem
20.
Acad Radiol ; 26(10): 1309-1317, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30655052

RESUMO

RATIONALE AND OBJECTIVES: To evaluate the diagnostic accuracy of a prototype noncontrast, free-breathing, self-navigated 3D (SN3D) MR angiography (MRA) technique for the assessment of coronary artery anatomy in children with known or suspected coronary anomalies, using CT angiography (CTA) as the reference standard. MATERIALS AND METHODS: Twenty-one children (15 male, 12.3 ± 2.6 years) were prospectively enrolled between July 2014 and August 2016 in this IRB-approved, HIPAA-compliant study. Patients underwent same-day unenhanced SN3D-MRA and contrast-enhanced CTA. Two observers rated the visualization of coronary artery segments and diagnostic confidence on a 3-point scale and assessed coronary arteries for anomalous origin, as well as interarterial and intramural course. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of SN3D-MRA for the detection of coronary artery abnormalities were calculated. Interobserver agreement was assessed using Intraclass Correlation Coefficients (ICC). RESULTS: Fourteen children showed coronary artery abnormalities on CTA. The visualization of coronary segments was rated significantly higher for CTA compared to MRA (p <0.015), except for the left main coronary artery (p = 0.301), with good to excellent interobserver agreement (ICC = 0.62-0.94). Diagnostic confidence was higher for CTA (p = 0.046). Sensitivity, specificity, PPV, and NPV of MRA were 92%, 92%, 96%, and 87% for the detection of coronary artery anomalies, 85%, 85%, 74%, and 92% for high origin, 71%, 92%, 82%, and 87% for interarterial, and 41%, 96%, 87%, and 80% for intramural course. CONCLUSIONS: Noncontrast SN3D-MRA is highly accurate for the detection of coronary artery anomalies in pediatric patients while diagnostic confidence and coronary artery visualization remain superior with CTA.

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