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1.
J Comput Assist Tomogr ; 44(1): 13-19, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939876

RESUMO

OBJECTIVE: To evaluate image quality and radiation dose exposure of low-kV setting and low-volume contrast medium (CM) computed tomography angiography (CTA) protocol for transcatheter aortic valve implantation (TAVI) planning in comparison with standard CTA protocol. METHODS: Sixty-patients were examined with 256-row MDCT for TAVI planning: 32 patients (study group) were evaluated using 80-kV electrocardiogram-gated protocol with 60 mL of CM and IMR reconstruction; 28 patients underwent a standard electrocardiogram-gated CTA study (100 kV; 80 mL of CM; iDose4 reconstruction). Subjective and objective image quality was evaluated in each patient at different aortic levels. Finally, we collected radiation dose exposure data (CT dose index and dose-length product) of both groups. RESULTS: In study protocol, significant higher mean attenuation values were achieved in all measurements compared with the standard protocol. There were no significant differences in the subjective image quality evaluation in both groups. Mean dose-length product of study group was 56% lower than in the control one (P < 0.0001). CONCLUSION: Low-kV and low-CM volume CTA, combined with IMR, allows to correctly performing TAVI planning with high-quality images and significant radiation dose reduction compared with standard CTA protocol.


Assuntos
Estenose da Valva Aórtica/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Meios de Contraste/administração & dosagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Estenose da Valva Aórtica/cirurgia , Feminino , Humanos , Bases de Conhecimento , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Multidetectores , Período Pré-Operatório , Doses de Radiação , Substituição da Valva Aórtica Transcateter
2.
J Comput Assist Tomogr ; 44(1): 26-31, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939878

RESUMO

Coronary computed tomography angiography is widely used in clinical practice. Although 3-dimensional (D) volume rendering is useful for interpretation of coronary path and territory, 2D output is common for image interpretation. Most picture archiving and communication system is incapable of manipulating 3D due to insufficient graphic specification. Thus, 2D bull's eye map display is frequently used in cardiac imaging. We developed a bull's eye map which emulated the anatomical information of individual coronary path and dominancy.


Assuntos
Vasos Coronários/diagnóstico por imagem , Ventrículos do Coração/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Idoso , Algoritmos , Angiografia por Tomografia Computadorizada , Feminino , Humanos , Imagem Tridimensional , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
3.
J Comput Assist Tomogr ; 44(1): 32-36, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939879

RESUMO

OBJECTIVE: To evaluate the effect of ultra high-resolution computed tomography (UHRCT) and model-based iterative reconstruction (MBIR) on the detectability of simulated submillimeter artery. METHODS: A small vessel phantom ranging from 0.4 to 2.0 mm in diameter and edge phantoms of low to high attenuation values were scanned by UHRCT (super-high-resolution mode and normal-resolution-mode) and conventional CT, and data were reconstructed by MBIR and filtered back projection (FBP). Vessel detectability was assessed subjectively and the effective size at which 50% of response was achieved (ES50 [mm]) was calculated. Modulation transfer function (MTF) was calculated by an edge spread function method. RESULTS: ES50 of super high-resolution mode (0.36 mm for MBIR and 0.50 mm for FBP) was significantly smaller than those of normal-resolution mode (P < 0.01). In the MTF analysis, the MTF of MBIR improved as the edge phantom attenuation increased, whereas that of FBP was stable. CONCLUSIONS: Both UHRCT and MBIR are effective for the detectability of simulated submillimeter artery.


Assuntos
Angiografia por Tomografia Computadorizada/métodos , Vasos Coronários/diagnóstico por imagem , Algoritmos , Humanos , Imagens de Fantasmas , Doses de Radiação , Interpretação de Imagem Radiográfica Assistida por Computador
4.
J Comput Assist Tomogr ; 44(1): 37-42, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939880

RESUMO

OBJECTIVE: The purpose of this study was to determine whether computed tomography (CT) angiography with machine learning (ML) can be used to predict the rapid growth of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: This retrospective study was approved by our institutional review board. Fifty consecutive patients (45 men, 5 women, 73.5 years) with small AAA (38.5 ± 6.2 mm) had undergone CT angiography. To be included, patients required at least 2 CT scans a minimum of 6 months apart. Abdominal aortic aneurysm growth, estimated by change per year, was compared between patients with baseline infrarenal aortic minor axis. For each axial image, major axis of AAA, minor axis of AAA, major axis of lumen without intraluminal thrombi (ILT), minor axis of lumen without ILT, AAA area, lumen area without ILT, ILT area, maximum ILT area, and maximum ILT thickness were measured. We developed a prediction model using an ML method (to predict expansion >4 mm/y) and calculated the area under the receiver operating characteristic curve of this model via 10-fold cross-validation. RESULTS: The median aneurysm expansion was 3.0 mm/y. Major axis of AAA and AAA area correlated significantly with future AAA expansion (r = 0.472, 0.416 all P < 0.01). Machine learning and major axis of AAA were a strong predictor of significant AAA expansion (>4 mm/y) (area under the receiver operating characteristic curve were 0.86 and 0.78). CONCLUSIONS: Machine learning is an effective method for the prediction of expansion risk of AAA. Abdominal aortic aneurysm area and major axis of AAA are the important factors to reflect AAA expansion.


Assuntos
Aneurisma da Aorta Abdominal/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Idoso , Idoso de 80 Anos ou mais , Progressão da Doença , Feminino , Humanos , Aprendizado de Máquina , Masculino , Estudos Retrospectivos
5.
J Comput Assist Tomogr ; 44(1): 53-58, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939882

RESUMO

OBJECTIVE: In the diagnosis of superior semicircular canal dehiscence (SSCD), computed tomography (CT) is the only imaging method. The aims of the study were to show that reformat images are more accurate than standard planes for diagnosis of SSCD and to determine the prevalence of SSCD. METHODS: The retrospective review yielded 1309 temporal CTs performed in our radiology department for any reason. Two radiologist interpreted CTs in standard planes collaboratively. Patients with SSCD were reinterpreted in Pöschl and Stenvers planes by 2 radiologists separately. RESULTS: Statistical analysis was made by accepting that 2 radiologists diagnosis were accurate in Pöschl plane. Coronal plane sensitivity 86%, specificity 64%, Stenvers plane sensitivity 96%, and specificity 52% have been found in the mean result of 2 observers (P < 0.001). CONCLUSIONS: In the diagnosis of SSCD, standard and Stenvers planes can cause false-negative and false-positive diagnoses. Interpretation in Pöschl plane can significantly increase sensitivity, specificity, negative, and positive predictive values for diagnosing dehiscence.


Assuntos
Doenças do Labirinto/diagnóstico por imagem , Tomografia Computadorizada Multidetectores/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Canais Semicirculares/anormalidades , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Canais Semicirculares/diagnóstico por imagem , Sensibilidade e Especificidade , Adulto Jovem
6.
J Comput Assist Tomogr ; 44(1): 78-82, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939886

RESUMO

OBJECTIVE: This study aimed to evaluate virtual monochromatic images (VMIs) obtained using dual-layer dual-energy computed tomography (CT) for breast carcinoma. METHODS: We retrospectively enrolled 28 patients with breast cancer who were pathologically diagnosed using dual-layer dual-energy CT. Virtual monochromatic images (40-200 keV) were generated. We compared CT number, image noise, contrast, and contrast-to-noise ratio (CNR) between VMIs with the highest CNR and conventional CT images. We performed qualitative image analysis between VMIs at optimized energy and conventional CT images. RESULTS: Image noise of VMIs was not significantly different from that of the conventional CT images. As the x-ray energy decreased, CNR increased. The 40-keV VMIs were highest CNR and higher than that of the conventional CT images. In qualitative image analysis, the 40-keV images were significantly higher than conventional CT images. CONCLUSION: Both qualitative and quantitative analyses showed that the image quality of VMIs at 40 keV was significantly higher than that of conventional CT images.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Intensificação de Imagem Radiográfica , Interpretação de Imagem Radiográfica Assistida por Computador , Estudos Retrospectivos , Razão Sinal-Ruído
7.
J Comput Assist Tomogr ; 44(1): 83-89, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939887

RESUMO

RATIONALE AND OBJECTIVES: This novel study aims to investigate texture parameters in distinguishing malignant and benign breast lesions classified as Breast Imaging Reporting and Data System 4 in dynamic contrast-enhanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: This retrospective study included 203 patients with 136 breast cancer and 67 benign lesions who underwent breast MRI between November 23, 2016, and August 27, 2018. Co-occurrence matrix-based texture features were extracted from each lesion on T1-weighted contrast-enhanced MRI using MatLab software. The association between texture parameters and breast lesions was analyzed, and the diagnostic model for breast cancer was created. Classification performance was evaluated by the area under the receiver operating characteristic curve, sensitivity, and specificity. RESULTS: Significant differences were seen between malignant and benign lesions for a number of textural features, including contrast, correlation, autocorrelation, dissimilarity, cluster shade, and cluster performance (P < 0.05). After the analysis of the multicollinearity, 5 texture features (contrast, correlation, dissimilarity, cluster shade, and cluster performance) were included for the next principal component analysis. The differentiation accuracy of breast cancer based on the diagnostic model was 0.948 (95% confidence interval, 0.908-0.974). CONCLUSIONS: Texture features that measure randomness, heterogeneity, or homogeneity may reflect underlying growth patterns of breast lesions and show great difference in malignant and benign lesions. Therefore, texture analysis may be a valuable assisted tool for diagnostic analysis on breast.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Área Sob a Curva , Feminino , Humanos , Imagem por Ressonância Magnética , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade , Adulto Jovem
8.
J Comput Assist Tomogr ; 44(1): 95-101, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939889

RESUMO

PURPOSE: This study aimed to evaluate image quality of ultra-low dose chest computed tomography using 6 iterative reconstruction (IR) algorithms. METHOD: A lung phantom was scanned on 4 computed tomography scanners using fixed tube voltages and the lowest mAs available on each scanner, resulting in dose levels of 0.1 to 0.2 mGy (80 kVp) and 0.3 to 1 mGy (140 kVp) volume CT dose index (CTDIvol). Images were reconstructed with IR available on the scanners. Image noise, signal-to-noise ratios, contrast-to-noise ratios, uniformity, and noise power spectrum (NPS) were assessed for evaluation of image quality. RESULTS: Image quality parameters increased with increasing dose for all algorithms. At constant dose levels, model-based techniques improved the contrast-to-noise ratio of lesions more than the statistical algorithms. All algorithms tested at 0.1 mGy showed lower NPS peak frequencies compared with 0.39 mGy. In contrast to the statistical techniques, model-based algorithms showed lower NPS peak frequencies at the lowest doses, indicating a coarser and blotchier noise texture. CONCLUSION: This study shows the importance of evaluating IR when introduced clinically.


Assuntos
Pulmão/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/instrumentação , Algoritmos , Meios de Contraste , Humanos , Imagens de Fantasmas , Doses de Radiação , Razão Sinal-Ruído
9.
J Comput Assist Tomogr ; 44(1): 118-123, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939892

RESUMO

AIM: This study aimed to assess the interobserver agreement of magnetic resonance (MR) imaging of Liver Imaging Reporting and Data System version 2018 (LI-RADS v2018). SUBJECTS AND METHODS: Retrospective analysis was done for 119 consecutive patients (77 male and 42 female) at risk of hepatocellular carcinoma who underwent dynamic contrast MR imaging. Image analysis was done by 2 independent and blinded readers for arterial phase hyperenhancement, washout appearance, enhancing capsule appearance, and size. Hepatic lesions were classified into 7 groups according to LI-RADS v2018. RESULTS: There was excellent interobserver agreement of both reviewers for LR version 4 (κ = 0.887, P = 0.001) with 90.76% agreement. There was excellent interobserver agreement for nonrim arterial phase hyperenhancement (κ = 0.948; 95% confidence interval [CI], 0.89-0.99; P = 0.001), washout appearance (κ = 0.949; 95% CI, 0.89-1.0; P = 0.001); and enhancing capsule (κ = 0.848; 95% CI, 0.73-0.97; P = 0.001) and excellent reliability of size (interclass correlation, 0.99; P = 0.001). There was excellent interobserver agreement for LR-1 (κ = 1.00, P = 0.001), LR-2 (κ = 0.94, P = 0.001), LR-5 (κ = 0.839, P = 0.001), LR-M (κ = 1.00, P = 0.001), and LR-TIV (κ = 1.00; 95% CI, 1.0-1.0; P = 0.001), and good agreement for LR-3 (κ = 0.61, P = 0.001) and LR-4 (κ = 0.61, P = 0.001). CONCLUSION: MR imaging of LI-RADS v2018 is a reliable imaging modality and reporting system that may be used for standard interpretation of hepatic focal lesions.


Assuntos
Carcinoma Hepatocelular/diagnóstico por imagem , Neoplasias Hepáticas/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Retrospectivos
10.
J Comput Assist Tomogr ; 44(1): 124-130, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939893

RESUMO

OBJECTIVE: To review and describe imaging findings on multidetector computed tomography in the early postoperative period after cytoreductive surgery with concomitant hyperthermic intraperitoneal chemotherapy (CRS + HIPEC). METHODS: This was a retrospective review of consecutive patients undergoing early (≤60 days) postoperative abdominopelvic multidetector computed tomography scans after CRS + HIPEC from 2014 to 2018 at a single institution. Two radiologists separately assessed bowel wall thickening, bowel wall enhancement, bowel dilation, ascites, and pleural effusion(s) and identified any other significant finding(s). RESULTS: Thirty-two patients met the inclusion criteria. The majority of patients demonstrated bowel wall thickening (53%; n = 17) and ascites (72%; n = 23), whereas postoperative ileus (35%; n = 10), pleural effusion(s) (24%; n = 7), and bowel wall hyperenhancement (6%; n = 1) were less common. Significant findings included anastomotic leak/perforation (13%; n = 4), fistula (13%; n = 4), abscess (13%; n = 4), and bladder leak (6%; n = 2). CONCLUSIONS: Multidetector computed tomography is an excellent imaging modality to identify common postoperative findings as well as complications following CRS + HIPEC.


Assuntos
Terapia Combinada/métodos , Tomografia Computadorizada Multidetectores/métodos , Neoplasias Peritoneais/terapia , Complicações Pós-Operatórias/diagnóstico por imagem , Adulto , Idoso , Procedimentos Cirúrgicos de Citorredução , Feminino , Humanos , Hipertermia Induzida , Masculino , Pessoa de Meia-Idade , Neoplasias Peritoneais/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador , Estudos Retrospectivos , Resultado do Tratamento
11.
J Comput Assist Tomogr ; 44(1): 131-137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939894

RESUMO

OBJECTIVE: To identify multidetector computed tomography (MDCT) findings of surgically confirmed adhesive internal hernias (IHs). METHODS: Two gastrointestinal radiologists performed blinded, independent, and retrospective reviews of MDCT findings from a consecutive cohort of 35 adhesive IH and 41 adhesive small-bowel obstruction cases that had undergone surgery within 48 hours after MDCT. Univariate statistical analyses were performed to assess CT signs of adhesive IHs and CT findings of intestinal necrosis in patients presenting with adhesive IHs. RESULTS: Dislocated cluster of the intestine (P = 0.005), 2 transitional zones (P = 0.002), and presence of fat in the center sign (P = 0.001) were key CT outcomes that were significantly associated with adhesive IHs. Additionally, intramural hemorrhage was found the MDCT feature indicative of intestinal necrosis (P = 0.028). CONCLUSIONS: This study illustrates specific MDCT findings of IHs, and these observations may help guide early clinical management of the condition.


Assuntos
Hérnia Abdominal/diagnóstico por imagem , Obstrução Intestinal/diagnóstico por imagem , Intestinos/diagnóstico por imagem , Tomografia Computadorizada Multidetectores/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Omento/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador , Estudos Retrospectivos , Adulto Jovem
12.
J Comput Assist Tomogr ; 44(1): 138-144, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939895

RESUMO

OBJECTIVE: The aim of this study was to determine the influence of virtual monoenergetic images (vMEIs) on renal cortex volumetry (RCV) and estimation of split-renal function. METHODS: Twenty-five patients (mean ± SD, 64.7 ± 9.9 years) underwent a contrast-enhanced dual-layer spectral detector computed tomography. Images were reconstructed with a reference standard (iterative model reconstruction, IMRRef), a newly spectral detector computed tomography algorithm (SPcon) and vMEI at 40, 60, 80, 100, and 120 keV. Two blinded independent readers performed RCV on all data sets with a semiautomated tool. RESULTS: Total kidney volume was up to 15% higher in vMEI at 40/60 keV compared with IMRRef (P < 0.001). Total kidney volume with vMEI at 80/100 keV was similar to IMRRef (P < 0.001). Split-renal function was similar in all reconstructions at approximately 50% ± 3%. Bland-Altman analysis showed no significant differences (P > 0.05), except for 40 keV versus SPcon (P < 0.05). The time required to perform RCV was reasonable, approximately 4 minutes, and showed no significant differences among reconstructions. Interreader agreement was greatest with vMEI at 80 keV (r = 0.68; 95% confidence interval, 0.39-0.85; P < 0.0002) followed by IMRRef images (r = 0.67; 95% confidence interval, 0.37-0.84; P < 0.0003). IMRRef showed the highest mean Hounsfield unit for cortex/medulla of 223.4 ± 73.7/62.5 ± 19.7 and a ratio of 3.7. CONCLUSIONS: Semiautomated RCV performed with vMEI and IMRRef/SPcon is feasible and showed no clinically relevant differences with regard to split-renal function. Low-kiloelectron volt vMEI showed greater tissue contrast and total kidney volume but no benefit for RCV. Moderate-kiloelectron volt vMEI (80 keV) results were similar to IMRRef with a faster postprocessing time.


Assuntos
Córtex Renal/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso , Algoritmos , Feminino , Humanos , Córtex Renal/patologia , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Retrospectivos , Sensibilidade e Especificidade , Razão Sinal-Ruído
13.
J Comput Assist Tomogr ; 44(1): 145-152, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939896

RESUMO

OBJECTIVES: We investigated the computed tomographic characteristics of gastrointestinal air motion artifact (GIAMA), which can be misinterpreted as active gastrointestinal bleeding. METHODS: We simulated GIAMA using 3 types of air-ball phantoms (air-ball in water, air-ball in oil, air-water-ball in oil) and a bovine intestine in oil phantom. We also performed a retrospective clinical review of precontrast abdominal computed tomography images of 76 patients to investigate the frequency, location, shape, and maximum density of hyperdense GIAMA. RESULTS: In phantom studies, air motion artifacts appeared as dark and bright streak artifacts at the borders of a moving air-ball and water or oil. In the clinical study, hyperdense GIAMA was visualized in 60 (79.0%) of 76 patients. The small intestine was most commonly affected (46.4%), and the intramural type had the highest frequency (58.0%). CONCLUSION: Knowing the radiologic features of GIAMA can assists radiologists in identifying active gastrointestinal bleeding sites accurately.


Assuntos
Hemorragia Gastrointestinal/diagnóstico por imagem , Tomografia Computadorizada Multidetectores/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Bovinos , Reações Falso-Positivas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Estudos Retrospectivos , Sensibilidade e Especificidade , Adulto Jovem
14.
J Comput Assist Tomogr ; 44(1): 43-46, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31789683

RESUMO

OBJECTIVE: The objective of this study was to investigate the frequency of hippocampal sulcus remnants (HSRs) in nonelderly adults using ultra-high-resolution 7T magnetic resonance (MR) images and their imaging features. METHODS: A total of 33 healthy adults underwent 7T MR, and multiplanar images of 66 temporal lobes were reviewed independently by 2 neuroradiologists. The detectability of the HSR was calculated. In addition, the interobserver agreement on the rating scale was evaluated using the κ statistic. RESULTS: Both observers identified HSRs with 7T MR images in all subjects. Excellent interobserver agreement was shown (κ = 1.0). The shape of HSRs was variable (spot-like, curvilinear, ovoid, or beaded appearance). Volumes of the HSRs were not correlated with age. CONCLUSIONS: Hippocampal sulcus remnants are commonly seen in healthy nonelderly adults using 7T MR imaging. Accurate diagnosis of HSR based on the microanatomy of hippocampus makes it easier to differentiate them from lesions, and it may help prevent unnecessary treatment.


Assuntos
Hipocampo/diagnóstico por imagem , Imagem por Ressonância Magnética/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Adulto , Algoritmos , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Adulto Jovem
15.
J Comput Assist Tomogr ; 44(1): 75-77, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31804241

RESUMO

Computed tomography perfusion (CTP) is increasingly used to determine treatment eligibility for acute ischemic stroke patients. Automated postprocessing of raw CTP data is routinely used, but it can fail. In reviewing 176 consecutive acute ischemic stroke patients, failures occurred in 20 patients (11%) during automated postprocessing by the RAPID software. Failures were caused by motion (n = 11, 73%), streak artifacts (n = 2, 13%), and poor contrast bolus arrival (n = 2, 13%). Stroke physicians should review CTP results with care before they are being integrated in their decision-making process.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Processamento Eletrônico de Dados/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagem de Perfusão/métodos , Fatores de Risco , Sensibilidade e Especificidade , Software , Tomografia Computadorizada por Raios X
16.
Br J Radiol ; 93(1105): 20190069, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31642702

RESUMO

OBJECTIVE: To evaluate the impact of different metal artifact reduction (MAR) algorithms on Hounsfield unit (HU) and standardized uptake values (SUV) in a phantom setting and verify these results in patients with metallic implants undergoing oncological PET/CT examinations. METHODS AND MATERIALS: In this prospective study, PET-CT examinations of 28 oncological patients (14 female, 14 male, mean age 69.5 ± 15.2y) with 38 different metal implants were included. CT datasets were reconstructed using standard weighted filtered back projection (WFBP) without MAR, MAR in image space (MARIS) and iterative MAR (iMAR, hip algorithm). The three datasets were used for PET attenuation correction. SUV and HU measurements were performed at the site of the most prominent bright and dark band artifacts. Differences between HU and SUV values across the different reconstructions were compared using paired t-tests. Bonferroni correction was used to prevent alpha-error accumulation (p < 0.017). RESULTS: For bright band artifacts, MARIS led to a non-significant mean decrease of 12.0% (345 ± 315 HU) in comparison with WFBP (391 ± 293 HU), whereas iMAR led to a significant decrease of 68.3% (125 ± 185 HU, p < 0.017). For SUVmean, MARIS showed no significant effect in comparison with WFBP (WFBP: 0.99 ± 0.40, MARIS: 0.96 ± 0.39), while iMAR led to a significant decrease of 11.1% (0.88 ± 0.35, p < 0.017). Similar results were observed for dark band artifacts. CONCLUSION: iMAR significantly reduces artifacts caused by metal implants in CT and thus leads to a significant change of SUV measurements in bright and dark band artifacts compared with WFBP and MARIS, thus probably improving PET quantification. ADVANCES IN KNOWLEDGE: The present work indicates that MAR algorithms such as iMAR algorithm in integrated PET/CT scanners are useful to improve CT image quality as well as PET quantification in the evaluation of tracer uptake adjacent to large metal implants. A detailed analysis of oncological patients with various large metal implants using different MAR algorithms in PET/CT has not been conducted yet.


Assuntos
Artefatos , Metais , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons/métodos , Próteses e Implantes , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Idoso , Algoritmos , Feminino , Fluordesoxiglucose F18 , Humanos , Masculino , Imagens de Fantasmas , Estudos Prospectivos , Compostos Radiofarmacêuticos
17.
Br J Radiol ; 93(1105): 20181019, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31724436

RESUMO

OBJECTIVE: The aim of this phantom study was to investigate the effect of scan parameters and noise suppression techniques on the minimum radiation dose for acceptable image quality for CT emphysema densitometry. METHODS: The COPDGene phantom was scanned on a third generation dual-source CT system with 16 scan setups (CTDIvol 0.035-10.680 mGy). Images were reconstructed at 1.0/0.7 mm slice thickness/increment, with three kernels (one soft, two hard), filtered backprojection and three grades of third-generation iterative reconstruction (IR). Additionally, deep learning-based noise suppression software was applied. Main outcomes: overlap in area of the normalized histograms of CT density for the emphysema insert and lung material, and the radiation dose required for a maximum of 4.3% overlap (defined as acceptable image quality). RESULTS: In total, 384 scan reconstructions were analyzed. Decreasing radiation dose resulted in an exponential increase of the overlap in normalized histograms of CT density. The overlap was 11-91% for the lowest dose setting (CTDIvol 0.035mGy). The soft kernel reconstruction showed less histogram overlap than hard filter kernels. IR and noise suppression also reduced overlap. Using intermediate grade IR plus noise suppression software allowed for 85% radiation dose reduction while maintaining acceptable image quality. CONCLUSION: CT density histogram overlap can quantify the degree of discernibility of emphysema and healthy lung tissue. Noise suppression software, IR, and soft reconstruction kernels substantially decrease the dose required for acceptable image quality. ADVANCES IN KNOWLEDGE: Noise suppression software, IR, and soft reconstruction kernels allow radiation dose reduction by 85% while still allowing differentiation between emphysema and normal lung tissue.


Assuntos
Imagens de Fantasmas , Enfisema Pulmonar/diagnóstico por imagem , Doses de Radiação , Tomografia Computadorizada por Raios X/métodos , Humanos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos
18.
Br J Radiol ; 93(1105): 20190003, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31738082

RESUMO

OBJECTIVE: This study aimed to assess and compare the diagnostic performance of the coronary artery to aortic luminal attenuation ratio (CAR), transluminal attenuation gradient (TAG), and corrected coronary opacification (CCO) difference on coronary CT angiography (cCTA) for detecting haemodynamically significant coronary artery stenosis. METHODS: 33 patients who underwent cCTA, gated SPECT myocardial perfusion imaging (MPI), and invasive coronary angiography within 3 months were included in this retrospective study. The degree of coronary stenosis on cCTA was visually assessed in all patients. Additionally, CAR, TAG, and CCO difference were analyzed and calculated in all patients. Haemodynamically significant coronary stenosis was defined as a vessel with ≥50% luminal stenosis on invasive coronary angiography and an associated abnormal perfusion defect on MPI in the same territory. Diagnostic performance was assessed on a per-vessel basis by the area under the receiver operating characteristic (ROC) curve (AUC). RESULTS: Among 99 vessels, 12 were excluded and the remaining 87 were analyzed. 17 (19.5%) vessels were determined as haemodynamically significant coronary artery stenosis. On ROC analysis, the AUC was 0.71 for cCTA, 0.80 for CAR, 0.61 for TAG, 0.74 for CCO, 0.87 for combined CAR and cCTA, 0.77 for combined TAG and cCTA, and 0.75 for combined CCO and cCTA. The AUC for combined CAR and cCTA was significantly greater compared with cCTA alone (p < 0.01). CONCLUSION: Non-invasive CAR derived from 64-detector row CT was feasible and might be helpful for the detection of haemodynamically significant coronary artery stenosis. Still, further investigations such as intra- and inter-reader correlation, evaluation of larger numbers in different settings, and time efficiency are required for applying CAR in various situations. ADVANCES IN KNOWLEDGE: CAR could be used as novel noninvasive technique to detect haemodynamically significant coronary artery stenosis.


Assuntos
Angiografia por Tomografia Computadorizada/métodos , Angiografia Coronária/métodos , Estenose Coronária/diagnóstico por imagem , Idoso , Aorta Torácica/diagnóstico por imagem , Estenose Coronária/fisiopatologia , Feminino , Hemodinâmica , Humanos , Masculino , Interpretação de Imagem Radiográfica Assistida por Computador , Estudos Retrospectivos , Tomografia Computadorizada de Emissão de Fóton Único
19.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(6): 969-977, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31875371

RESUMO

A method was proposed to detect pulmonary nodules in low-dose computed tomography (CT) images by two-dimensional convolutional neural network under the condition of fine image preprocessing. Firstly, CT image preprocessing was carried out by image clipping, normalization and other algorithms. Then the positive samples were expanded to balance the number of positive and negative samples in convolutional neural network. Finally, the model with the best performance was obtained by training two-dimensional convolutional neural network and constantly optimizing network parameters. The model was evaluated in Lung Nodule Analysis 2016(LUNA16) dataset by means of five-fold cross validation, and each group's average model experiment results were obtained with the final accuracy of 92.3%, sensitivity of 92.1% and specificity of 92.6%.Compared with other existing automatic detection and classification methods for pulmonary nodules, all indexes were improved. Subsequently, the model perturbation experiment was carried out on this basis. The experimental results showed that the model is stable and has certain anti-interference ability, which could effectively identify pulmonary nodules and provide auxiliary diagnostic advice for early screening of lung cancer.


Assuntos
Neoplasias Pulmonares , Nódulos Pulmonares Múltiplos , Algoritmos , Humanos , Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X
20.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(6): 978-985, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31875372

RESUMO

Accurate segmentation of pulmonary nodules is an important basis for doctors to determine lung cancer. Aiming at the problem of incorrect segmentation of pulmonary nodules, especially the problem that it is difficult to separate adhesive pulmonary nodules connected with chest wall or blood vessels, an improved random walk method is proposed to segment difficult pulmonary nodules accurately in this paper. The innovation of this paper is to introduce geodesic distance to redefine the weights in random walk combining the coordinates of the nodes and seed points in the image with the space distance. The improved algorithm is used to achieve the accurate segmentation of pulmonary nodules. The computed tomography (CT) images of 17 patients with different types of pulmonary nodules were selected for segmentation experiments. The experimental results are compared with the traditional random walk method and those of several literatures. Experiments show that the proposed method has good accuracy in the segmentation of pulmonary nodule, and the accuracy can reach more than 88% with segmentation time is less than 4 seconds. The results could be used to assist doctors in the diagnosis of benign and malignant pulmonary nodules and improve clinical efficiency.


Assuntos
Análise por Conglomerados , Neoplasias Pulmonares , Nódulos Pulmonares Múltiplos , Algoritmos , Humanos , Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X
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