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1.
Radiol Med ; 125(1): 1-6, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31562581

RESUMO

PURPOSE: To evaluate the influence of fat deposition on T1 relaxation time of pancreatic parenchyma using dual-flip-angle T1 mapping with and without fat suppression. METHODS: Forty-five patients who underwent abdominal MR imaging including T1 mapping with dual-flip-angle method on 3T MRI were included. We measured T1 relaxation time of pancreatic parenchyma on the T1 map images with and without fat suppression. T1 relaxation time of bone marrow was also measured as a reference organ with abundant fat deposition. Fat signal fraction (FSF) was also measured at the same location as T1 map images. Then, the correlation between T1 relaxation time and FSF was assessed. RESULTS: T1 relaxation times of pancreatic parenchyma and bone marrow on the T1 map images without fat suppression showed significantly negative correlation with FSF (pancreas, r = - 0.394, P = 0.007; bone marrow, r = - 0.550, P < 0.001), while there were no significant correlations between them on the T1 map images with fat suppression. On the T1 map images without fat suppression, T1 relaxation times of pancreatic parenchyma as well as bone marrow in patients with FSF ≥ 10% were significantly shorter than those in patients with FSF < 10% (pancreas, P = 0.041; bone marrow, P = 0.005). Conversely, on the T1 map images with fat suppression, no significant differences in T1 relaxation times were found between two groups. CONCLUSION: T1 relaxation time of the pancreas on T1 mapping was influenced by the presence of fat deposition. Therefore, fat suppression technique in T1 mapping will be essential for evaluating T1 relaxation time of pancreatic parenchyma.


Assuntos
Tecido Adiposo/diagnóstico por imagem , Imagem por Ressonância Magnética/métodos , Pâncreas/diagnóstico por imagem , Pancreatopatias/diagnóstico por imagem , Técnica de Subtração , Idoso , Idoso de 80 Anos ou mais , Medula Óssea/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/diagnóstico por imagem , Padrões de Referência , Estudos Retrospectivos , Fatores de Tempo
2.
Vet Microbiol ; 237: 108385, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31585645

RESUMO

Streptococcus uberis is an important bovine mastitis pathogen, but not all isolates have equal capacity to cause disease. The aims of this study were to identify possible virulence-associated genes that could be used to identify isolates with enhanced virulence. DNA from a pool of putative commensals was subtracted from a clinical pool resulting in a set of DNA sequences (probes) that were enriched in the clinical mastitis group. The probes were hybridised with DNA from a collection 29 isolates from cases of clinical mastitis and isolates not associated with disease. Hybridization revealed five major clusters. The first cluster (7 isolates) consisted almost entirely of commensals, while the second (7 isolates) was mixed. The remaining three clusters contained 15 S. uberis isolates from cows with clinical mastitis. Twenty-six probes were selected for sequencing based on principal component analysis (PCA) or their presence mainly in clinical isolates. PCA identified five probes with clear differences in intensity between signals from clinical isolates and commensals; these probes could represent novel virulence determinants. Manual inspection of arrays identified genes prominent among clinical isolates that specify carbohydrate and lipid metabolism (possible role in the growth or survival of S. uberis in milk) and genes specifying hypothetical proteins, possibly novel virulence factors. The common occurrence, among clinical isolates, of probes having homology with transposases and insertion sequences suggests recent acquisition of factors that could be associated with virulence. These results suggest the existence of a subset of S. uberis with enhanced virulence, due possession of virulence-associated gene sequences.


Assuntos
Mastite Bovina/microbiologia , Infecções Estreptocócicas/veterinária , Streptococcus/patogenicidade , Técnica de Subtração , Animais , Bovinos , Clonagem Molecular , DNA Bacteriano , Feminino , Análise de Componente Principal , Infecções Estreptocócicas/microbiologia , Streptococcus/genética , Virulência
3.
Phys Med ; 63: 63-69, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31221410

RESUMO

INTRODUCTION: Bone density can interfere with fluoroscopy-guided tumor tracking in radiotherapy. To improve markerless tumor tracking accuracy, we developed a dual energy subtraction (DES) mechanical image mask to use with a single x-ray exposure. METHODS: The DES mask consists of 2-mm-thick stainless-steel with 128 pairs of slits (0.388 mm width and openings), designed to match the dynamic flat panel detector (DFPD) pixel size. This was set on the front of the DFPD. This results in a DFPD image with one containing the exposed pixels and one containing the masked pixels. The masked pixel columns were interpolated from adjacent pixels and a subtraction image was generated from the interpolated images to make a bone suppression (BS) image. A chest phantom was set on the commercially available moving table (CIRS DYNAMIC PLATFORM 008PL) and DFPD images were acquired. A reference BS image was generated by double-exposure DES with and without a 2-mm-thick stainless-steel plate. Image quality and markerless tumor tracking accuracy were then evaluated. RESULTS: The DES mask decreased most of the visible bone densities from the chest phantom image acquired with a single exposure for a peak-signal-to-noise-ratio/structural similarity index measure (PSNR/SSIM) of 25.3 db/0.685). The tracking positional error, originally 12.6 mm, was improved to 0.2 mm. CONCLUSIONS: The DES mask can aid in BS image on fluoroscopic imaging and may be useful in markerless tumor tracking.


Assuntos
Imagens de Fantasmas , Técnica de Subtração , Cirurgia Assistida por Computador/instrumentação , Movimento (Física) , Tórax/diagnóstico por imagem , Fatores de Tempo
4.
Injury ; 50(4): 939-949, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31003702

RESUMO

OBJECTIVES: The aim of this study was to develop a systematic three-dimensional (3D) classification of intertrochanteric fractures by clustering the morphological features of fracture lines using the Hausdorff distance-based K-means approach and assess the usefulness of it in the clinical setting. METHODS: We retrospectively analyzed the data of 504 patients with intertrochanteric fractures who underwent closed reduction and intramedullary internal fixation. The morphological fracture lines of all patients extracted from computed tomography were transcribed freehand onto the template. All fracture lines were then clustered into five distinct types using the Hausdorff distance-based K-means clustering method. Five radiographic parameters and four functional parameters were used to evaluate the postoperative functional states and mobilization levels. Postoperative complications were also recorded. RESULTS: Intertrochanteric fractures were classified into five types: type I (108/504, 21.4%), simple fracture with intact lateral femoral wall and greater trochanter fragment; type II (85/504, 16.9%), simple fracture with intact lateral femoral wall with/without lesser trochanter detachment; type III (147/504, 29.2%), fractures with intertrochanteric crest detachment involving the lesser trochanter and greater trochanter with an intact lateral femoral wall; type IV (113/504, 22.4%), fractures with large intertrochanteric crest detachment and large lesser trochanter and greater trochanter detachment partially involving the lateral femoral wall and less medial cortical support; type V (51/504, 10.1%), a combination of pertrochanteric and lateral fracture line involving the entire lateral femoral wall and lesser trochanter detachment. Parameters of femoral neck-shaft angle and sliding distance of the cephalic nail were significantly different among types. The complication rate generally increased from type I to type V (P = 0.035). CONCLUSIONS: The unsupervised clustering can achieve identification of the type of intertrochanteric fractures with clinical significance. The Tang classification can be used to describe fracture morphology, predict the possibility of achieving stable reduction and the risk of complications following intramedullary fixation.


Assuntos
Consolidação da Fratura/fisiologia , Fraturas do Quadril/classificação , Interpretação de Imagem Assistida por Computador , Imagem Tridimensional , Adulto , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Feminino , Fixação Intramedular de Fraturas , Fraturas do Quadril/diagnóstico por imagem , Fraturas do Quadril/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Reconhecimento Automatizado de Padrão , Reprodutibilidade dos Testes , Estudos Retrospectivos , Técnica de Subtração
5.
Adv Otorhinolaryngol ; 82: 12-31, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30947168

RESUMO

Multidetector computed tomography has been the benchmark for visualizing bony changes of the ear, but has recently been challenged by cone-beam computed tomography. In both methods, all inner ear bony structures can be visualized satisfactorily with 2D or 3D imaging. Both methods produce ionizing radiation and induce adverse health effects, especially among children. In 3T magnetic resonance imaging, the soft tissue can be imaged accurately. Use of gadolinium chelate (GdC) as a contrast agent allows the partition of fluid spaces to be visualized, such as the bulging of basilar and Reissner's membranes. Both intravenous and intratympanic administration of GdC has been used. The development of positive endolymph imaging method, which visualizes endolymph as a bright signal, and the use of image subtraction seems to allow more easily interpretable images. This long-awaited possibility of diagnosing endolymphatic hydrops in living human subjects has enabled the definition of Hydropic Ear Disease, encompassing typical Meniere's disease as well as its monosymptomatic variants and secondary conditions of endolymphatic hydrops. The next challenge in imaging of the temporal bone is to perform imaging at the cellular and molecular levels. This chapter provides an overview of current temporal bone imaging methods and a review of emerging concepts in temporal bone imaging technology.


Assuntos
Otopatias/diagnóstico por imagem , Osso Temporal/diagnóstico por imagem , Tomografia Computadorizada de Feixe Cônico , Meios de Contraste , Humanos , Imagem Tridimensional , Imagem por Ressonância Magnética , Técnica de Subtração , Tomografia Computadorizada por Raios X
6.
Med Phys ; 46(5): 2264-2274, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30888690

RESUMO

PURPOSE: The purpose of this study was to assess, using an anthropomorphic digital phantom, the accuracy of algorithms in registering precontrast and contrast-enhanced computed tomography (CT) chest images for generation of iodine maps of the pulmonary parenchyma via temporal subtraction. MATERIALS AND METHODS: The XCAT phantom, with enhanced airway and pulmonary vessel structures, was used to simulate precontrast and contrast-enhanced chest images at various inspiration levels and added CT simulation for realistic system noise. Differences in diaphragm position were varied between 0 and 20 mm, with the maximum chosen to exceed the 95th percentile found in a dataset of 100 clinical subtraction CTs. In addition, the influence of whole body movement, degree of iodine enhancement, beam hardening artifacts, presence of nodules and perfusion defects in the pulmonary parenchyma, and variation in noise on the registration were also investigated. Registration was performed using three lung registration algorithms - a commercial (algorithm A) and a prototype (algorithm B) version from Canon Medical Systems and an algorithm from the MEVIS Fraunhofer institute (algorithm C). For each algorithm, we calculated the voxel-by-voxel difference between the true deformation and the algorithm-estimated deformation in the lungs. RESULTS: The median absolute residual error for all three algorithms was smaller than the voxel size (1.0 × 1.0 × 1.0 mm3 ) for up to an 8 mm diaphragm difference, which is the average difference in diaphragm levels found clinically, and increased with increasing difference in diaphragm position. At 20 mm diaphragm displacement, the median absolute residual error after registration was 0.85 mm (interquartile range, 0.51-1.47 mm) for algorithm A, 0.82 mm (0.50-1.40 mm) for algorithm B, and 0.91 mm (0.54-1.52 mm) for algorithm C. The largest errors were seen in the paracardiac regions and close to the diaphragm. The impact of all other evaluated conditions on the residual error varied, resulting in an increase in the median residual error lower than 0.1 mm for all algorithms, except in the case of whole body displacements for algorithm B, and with increased noise for algorithm C. CONCLUSION: Motion correction software can compensate for respiratory and cardiac motion with a median residual error below 1 mm, which was smaller than the voxel size, with small differences among the tested registration algorithms for different conditions. Perfusion defects above 50 mm will be visible with the commercially available subtraction CT software, even in poorly registered areas, where the median residual error in that area was 7.7 mm.


Assuntos
Algoritmos , Pulmão/diagnóstico por imagem , Imagens de Fantasmas , Técnica de Subtração/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Artefatos , Humanos , Pulmão/fisiologia , Movimento , Razão Sinal-Ruído
7.
Osteoporos Int ; 30(5): 1051-1057, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30706095

RESUMO

Tc99m-sestamibi dual-time imaging is a standard tool for localization of adenomas/hyperplasia in hyperparathyroidism. We investigated the degree and causes of localization failure among different types of hyperparathyroidism. Pre-operative parathyroid hormone levels and size of the gland were major determinants of Tc99m-sestamibi positivity; 123I scan may be helpful in localization failures. INTRODUCTION: Tc99m-sestamibi dual-time imaging is a standard tool for localization of adenomas/hyperplasia in hyperparathyroidism. However, parathyroid adenomas/hyperplasia has been reported to washout as fast as normal thyroid tissue ("rapid washout") which may lead to diagnostic failure. We aimed to evaluate the determinants of rapid washout and to determine the role of subtraction imaging for detection of parathyroid adenomas/hyperplasia with rapid washout. METHODS: Retrospective analysis of patients with hyperparathyroidism who have undergone Tc99m-sestamibi dual-time imaging and parathyroid surgery. Rapid washout was correlated to the type of hyperparathyroidism in surgically confirmed cases. Biochemical and pathological data were reviewed. RESULTS: A total of 135 hyperparathyroidism patients met the inclusion criteria. Ninety-six (72%), 29 (21%), and 10 (7%) had primary, secondary, and tertiary hyperparathyroidisms, respectively. Rapid washout was identified in 28/87 glands (32%), 14/53 glands (26%), and 1/16 glands (6%) with primary, secondary, and tertiary hyperparathyroidisms, respectively. Glands that were positive on late-phase Tc99m-sestamibi scans were significantly large being 1.7 (IQR 1.4-2.3) vs. 1.45 (IQR 1-2) cm (p = 0.003). High parathyroid hormone levels (PTH) were associated with early-phase Tc99m-sestamibi positivity in both primary (p = 0.01) and secondary hyperparathyroidism (p = 0.03) but not with last phase (p = 0.11, p = 0.37, respectively). Correlative imaging with subtraction scintigraphy was positive in 14/16 (87.5%) parathyroid adenomas. CONCLUSION: Pre-operative PTH levels and size of the gland were major determinants of Tc99m-sestamibi positivity on early-phase Tc99m-sestamibi scans, whereas size is an independent predictor of late-phase Tc99m-sestamibi positivity. Subtraction scintigraphy might be a useful tool in suspected cases of rapid washout adenomas/hyperplasia.


Assuntos
Adenoma/diagnóstico por imagem , Hiperparatireoidismo Primário/diagnóstico por imagem , Neoplasias das Paratireoides/diagnóstico por imagem , Adenoma/complicações , Adulto , Idoso , Feminino , Humanos , Hiperparatireoidismo Primário/etiologia , Radioisótopos do Iodo , Masculino , Pessoa de Meia-Idade , Hormônio Paratireóideo/sangue , Neoplasias das Paratireoides/complicações , Cintilografia/métodos , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Técnica de Subtração , Tecnécio Tc 99m Sestamibi
8.
Eur Radiol ; 29(9): 4930-4936, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30770970

RESUMO

This technical note describes a novel CT scan protocol that includes a non-enhanced CT, dynamic CTA, and perfusion of the whole brain and CTA of the carotid arteries using a 320-row area detector CT scanner, with a unique contrast injection and acceptable radiation exposure dose in patients presenting with acute ischemic stroke. The acquisition parameters and reconstruction parameters will be discussed including the use of model-based iterative reconstruction (MBIR), time summing (tMIP), and subtraction techniques to optimize the results of this protocol.Key Points• Scanning on a 320-row area detector CT can achieve both brain perfusion with dynamic angiography and reconstructed arterial and venous CTA, and supra aortic trunk angiography, in a single acquisition. • It provides, in a single exam, a full diagnostic workup, i.e., all the acquisitions that are needed to make a quick decision, with reasonable exposure to ionizing radiation and reduced amount of medium contrast, in case of acute ischemic stroke presentation.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Artérias Carótidas/diagnóstico por imagem , Meios de Contraste/administração & dosagem , Humanos , Imagem de Perfusão , Doses de Radiação , Exposição à Radiação , Interpretação de Imagem Radiográfica Assistida por Computador , Técnica de Subtração
9.
Eur J Radiol ; 110: 136-141, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30599850

RESUMO

PURPOSE: Run-off Computed Tomography Angiography (run-off CTA) of the lower extremities has become the method of choice for the diagnostic imaging of patients suffering from peripheral arterial disease (PAD). However, it remains a challenging radiological examination with a considerable risk of non-diagnostic image quality for the assessment of below-the-knee arteries. In this study, we investigate the diagnostic benefit of adding time-resolved CT scan series to the standard run-off CTA by performing repeated axial acquisitions over the calves of the patient during a second bolus of iodinated contrast injection. MATERIALS AND METHODS: This prospective study included 20 patients (9 male, 11 female; mean age 66.1 ± 14.9 years) who received a standard run-off CTA and an additional time-resolved CT scan series after a 10 min delay. The time-resolved series consisted of 18 repeated axial acquisitions over the calves directly below the knee with a 2 s interphase delay. For both series, two observers independently assessed the anterior tibial, posterior tibial and peroneal arteries of both legs for following criteria: arterial enhancement, presence and degree of stenosis, the confidence of grading, degree of stenosis and venous overlay. Quantitative assessment of arterial enhancement was performed by measuring the mean CT values (HU) in all arteries. Radiation exposure was quantified by the effective dose. RESULTS: A total of 118 arteries were assessed. The observer study showed that the additional time-resolved series improved both arterial enhancement (64% considered optimal enhanced versus 44%) and diagnostic confidence (59% considered as certain versus 33%) for the assessment of arterial stenosis (all p < 0.05). Venous overlay reduced from 15% to 6%. In all three arteries, the measured contrast enhancement by CT values (HU) was considerably higher (average 48%, p < 0.05) with the time-resolved series. The time-resolved series had an effect on stenosis classification (p = 0.03): a higher number of arteries were graded as having a non-significant stenosis (78.8% versus 71.2%). The interobserver variability in stenosis classification improved from κ = 0.39 to κ = 0.61. The mean effective dose was 5.1 ± 1.3 mSv for the run-off CTA and 0.2 ± 0.07 mSv for the time-resolved series. Per patient, a total volume of 140 mL contrast agent was injected. CONCLUSION: A dynamic CT scan protocol with repeated axial series can be added to a standard helical run-off CTA sequence for the lower extremities within the same CT examination, and it increases image quality and diagnostic confidence for the assessment of presence and degree of arterial stenosis in below-the-knee arteries.


Assuntos
Angiografia por Tomografia Computadorizada/instrumentação , Perna (Membro)/irrigação sanguínea , Doença Arterial Periférica/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Arteriopatias Oclusivas/diagnóstico por imagem , Artérias , Bovinos , Angiografia por Tomografia Computadorizada/métodos , Constrição Patológica/diagnóstico por imagem , Meios de Contraste/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Prospectivos , Reprodutibilidade dos Testes , Técnica de Subtração , Tomógrafos Computadorizados , Tomografia Computadorizada por Raios X/métodos
10.
J Endocrinol Invest ; 42(8): 889-895, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30600433

RESUMO

PURPOSE: Parathyroid scintigraphy is superior to other imaging techniques in detecting hyperfunctioning parathyroid glands. It is mainly performed using double-phase or dual-tracer subtraction methods. Neither of the techniques is perfect and different protocols are being used. We aimed to evaluate the accuracy of double-phase and subtraction methods in detecting abnormal gland as well as the potential effects of coexisting thyroid disease and clinical-laboratory data. METHODS: We considered patients with primary hyperparathyroidism who underwent parathyroid surgery, after a parathyroid scintigraphy between April 2015 and February 2017. Sixty-eight patients were included; in 45 cases (66.2%), a thyroid disease was coexistent. Diagnostic performances of the two techniques were compared. The effect of thyroid disease and clinical-pathological data on examination interpretation was considered. RESULTS: Double-phase scintigraphy showed higher sensitivity and accuracy in detecting the exact abnormal gland compared to the digital subtraction (90% and 75% vs. 76% and 66%, respectively). For double-phase technique, sensitivity and accuracy were higher in cases with no thyroid disease when compared to those with thyroid disease (92% and 86% vs. 88% and 69%, respectively). Similarly, for digital subtraction, sensitivity and accuracy were higher in the absence of thyroid disease compared to their presence (84% and 79% vs. 70% and 58%, respectively). There was no significant variation in the performance of both techniques, considering clinical-laboratory data. CONCLUSIONS: Double-phase scintigraphy has been more accurate than digital subtraction. The presence of thyroid disease could be a possible limit, affecting the subtraction more than the double-phase technique. Clinical data did not influence the scintigraphic outcome.


Assuntos
Hiperparatireoidismo Primário/diagnóstico por imagem , Glândulas Paratireoides/diagnóstico por imagem , Cintilografia/métodos , Compostos Radiofarmacêuticos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Técnica de Subtração , Adulto Jovem
11.
Radiol Phys Technol ; 12(1): 40-45, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30460476

RESUMO

The temporal subtraction (TS) technique requires the same patient's chest radiographs (CXRs) acquired on different dates, whereas the similar subtraction (SS) technique can be used in patients who have no previous CXR, using similar CXRs from different patients. This study aimed to examine the depiction ability of SS images with simulated nodules in comparison with that of TS images with 2- and 7-year acquisition intervals. One hundred patients were randomly selected from our image database. The most recently acquired images of the patients were used as target images for subtraction. The simulated nodule was superimposed on each target image to examine the usefulness of the SS technique. The most (Top 1) and ten most (Top 10) similar images for each target image were identified in the 24,254-image database using a template-matching technique, and used for the SS technique. SS and TS images were obtained using a previously developed nonlinear image-warping technique. The depiction ability of SS and TS images was evaluated using the contrast-to-noise ratio (CNR). The proportion of Top 1 SS images showing higher CNR than that of the TS images with 2- and 7-year acquisition intervals was 28% (28/100) and 33% (33/100), respectively. Moreover, the proportion of cases that had any of the Top 10 SS images with higher CNRs than those of TS images with 2- and 7-year acquisition intervals was 56% (56/100) and 72% (72/100), respectively. Our study indicates that the SS technique can potentially be used to detect lung nodules on CXRs.


Assuntos
Radiografia Torácica/métodos , Técnica de Subtração , Humanos , Processamento de Imagem Assistida por Computador , Neoplasias Pulmonares/diagnóstico por imagem
12.
Clin Anat ; 32(1): 35-40, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30260507

RESUMO

Developmental remnants may follow segmental canalization of ectodermal epithelial cords forming the nasolacrimal drainage apparatus (NDA). This can result in false luminal "valves" along the path of the NDA, many of which have been named, but most have not been anatomically identified with consistency. By 1908, eight such "valves" were documented, those of: Foltz, Bochdalek, Rosenmüller, Huschke, Aubaret, Béraud or Krause, Taillefer, and Hasner or Cruveilhier or Bianchi. Digital subtraction dacryocystography (DS-DCG) is the highest spatial resolution imaging technique available to outline in vivo NDA anatomy, luminal profile, and pathology. We believe this is the first report of the conspicuousness and frequency of these "valves" on DS-DCG. We retrospectively analyzed routine DS-DCGs with normal findings for the presence and frequency of the eight NDA "valves." We examined 92 normal DS-DCGs on patients aged 14-82 years (71% female, 29% male). We observed "valves" most reliably in the inferior nasolacrimal duct: the inferior valve of Hasner (plica lacrimalis) was present in 98.9% of cases, and more superiorly, the valve of Taillefer (93.5%) and the valve of Krause (79.3%). Contrastingly, we infrequently identified the very superior "valves": Foltz or Bochdalek in 17.1%, Rosenmüller or Huschke in 46.4%, and Auberat in 40% of cases. Therefore, unlike the inferior NDA valves, these more superior "valves" were less consistently identified and are presumed to be simple mural mucosal irregularities rather than true structural valves. These findings will be useful in diagnostic interpretation of DS-DCGs and therapeutic planning for patients undergoing luminal procedures on the NDA. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc.


Assuntos
Ducto Nasolacrimal/diagnóstico por imagem , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Ducto Nasolacrimal/anatomia & histologia , Radiografia , Estudos Retrospectivos , Técnica de Subtração , Adulto Jovem
13.
Artigo em Inglês | MEDLINE | ID: mdl-30334791

RESUMO

In ultrasonic imaging, reduction of lateral sidelobes can result in an improved image with less distortion and fewer artifacts. In general, apodization is used to lower sidelobes in exchange for increasing the width of the main lobe, and thus decreasing lateral resolution. Null subtraction imaging (NSI) is a nonlinear image processing technique that uses different receive apodizations on copies of the same RF data to maintain low sidelobe levels while simultaneously improving lateral resolution. The images created with three different apodization functions are combined to form an image with low sidelobe levels and apparent improvements in lateral resolution compared to conventional rectangular apodization. To evaluate the performance of this technique for different imaging tasks, experiments were performed on an ATS539 phantom containing wire targets to assess lateral resolution and cylindrical anechoic and hyperechoic targets to assess contrast. NSI images were compared against rectangular apodized images and minimum variance beamformed images. In experiments, the apparent lateral resolution was observed to improve by a factor of more than 35× when compared to rectangular apodization. Image quality was assessed by the estimation of lateral resolution (-6-dB receive beamwidth), main-lobe-to-sidelobe ratio, and contrast-to-noise ratio (CNR). Imaging with NSI using a focal number of 2 (f/2), the -6-dB beamwidth on receive as measured from a small wire target in the ATS phantom was 0.03λ compared to 2.79λ for rectangular apodization. Sidelobes were observed to decrease by 32.9 dB with NSI compared to rectangular apodization. However, the ability to observe the contrast of anechoic and hyperechoic targets reduced when utilizing the NSI scheme, i.e., the CNR decreased from -3.05 to -1.01 for anechoic targets and 1.65 to 0.45 for the hyperechoic targets.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Ultrassonografia/métodos , Artérias Carótidas/diagnóstico por imagem , Bases de Dados Factuais , Humanos , Imagens de Fantasmas , Técnica de Subtração
14.
IEEE Trans Biomed Eng ; 66(1): 273-282, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29993440

RESUMO

OBJECTIVE: Subtraction-based techniques are known for being theoretically rigorous and accurate methods for solving the forward problem in electroencephalography (EEG-FP) by means of the finite-element method. Within them, the projected subtraction (PS) approach is generally adopted because of its computational efficiency. Although this technique received the attention of the community, its sensitivity to degenerated elements is still poorly understood. In this paper, we investigate the impact of low-quality tetrahedra on the results computed with the PS approach. METHODS: We derived upper bounds on the relative error of the element source vector as a function of geometrical features describing the tetrahedral discretization of the domain. These error bounds were then utilized for showing the instability of the PS method with regards to the mesh quality. To overcome this issue, we proposed an alternative technique, coined projected gradient subtraction (PGS) approach, that exploits the stability of the corresponding bounds. RESULTS: Computer simulations showed that the PS method is extremely sensitive to the mesh shape and size, leading to unacceptable solutions of the EEG-FP in case of using suboptimal tessellations. This was not the case of the PGS approach, which led to stable and accurate results in a comparable amount of time. CONCLUSION: Solutions of the EEG-FP computed with the PS method are highly sensitive to degenerated elements. Such errors can be mitigated by the PGS approach, which showed better performance than the PS technique. SIGNIFICANCE: The PGS is an efficient method for computing high-quality lead field matrices even in the presence of degenerated elements.


Assuntos
Eletroencefalografia/métodos , Processamento de Sinais Assistido por Computador , Algoritmos , Encéfalo/fisiologia , Análise de Elementos Finitos , Cabeça/fisiologia , Humanos , Modelos Biológicos , Técnica de Subtração
15.
Am J Surg ; 217(1): 108-113, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29980283

RESUMO

BACKGROUND: Primary hyperparathyroidism/(PHPT) is one of the most common endocrinological conditions. Surgery remains the only curative option. We have evaluated the performance of double isotope 123I/99mTc-sestamibi parathyroid scintigraphy/(PS) with subtraction SPECT/CT in PHP for identifying uniglandular disease. METHODS: Ninety PHPT patients undergoing parathyroidectomy (December 2015-August 2016) were included. All patients were evaluated with neck ultrasound/(US), PS and SPECT/CT with a new protocol. Outcomes from imaging modalities were reported as: uniglandular disease/(UGD), multiglandular disease/(MGD), or negative, and were compared to post-operative diagnoses. RESULTS: Post-operatively, 72 and 18 patients had true UGD and MGD, respectively. Sensitivities and specificities of US, pinhole scintigraphy with subtraction, pinhole and SPECT/CT with subtraction, and all modalities combined were 91.7%/38.9%, 88.9%/72.2%, 93%/66.7% and 84.72%/77.78%, respectively: specificity of US + PS superior to US alone, p = 0.074. SPECT/CT enables reclassification of doubtful uptake foci. CONCLUSIONS: Combination of neck US and PS with subtraction SPECT/CT offers a higher specificity for guiding towards minimally invasive parathyroidectomy.


Assuntos
Hiperparatireoidismo Primário/diagnóstico por imagem , Hiperparatireoidismo Primário/cirurgia , Paratireoidectomia , Cintilografia , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único , Técnica de Subtração , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Radioisótopos do Iodo , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Minimamente Invasivos , Seleção de Pacientes , Compostos Radiofarmacêuticos , Sensibilidade e Especificidade , Tecnécio Tc 99m Sestamibi , Adulto Jovem
16.
Eur Radiol ; 29(2): 759-769, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30062525

RESUMO

OBJECTIVE: To assess whether temporal subtraction (TS) images of brain CT improve the detection of suspected brain infarctions. METHODS: Study protocols were approved by our institutional review board, and informed consent was waived because of the retrospective nature of this study. Forty-two sets of brain CT images of 41 patients, each consisting of a pair of brain CT images scanned at two time points (previous and current) between January 2011 and November 2016, were collected for an observer performance study. The 42 sets consisted of 23 cases with a total of 77 newly developed brain infarcts or hyperdense artery signs confirmed by two radiologists who referred to additional clinical information and 19 negative control cases. To create TS images, the previous images were registered to the current images by partly using a non-rigid registration algorithm and then subtracted. Fourteen radiologists independently interpreted the images to identify the lesions with and without TS images with an interval of over 4 weeks. A figure of merit (FOM) was calculated along with the jackknife alternative free-response receiver-operating characteristic analysis. Sensitivity, number of false positives per case (FPC) and reading time were analyzed by the Wilcoxon signed-rank test. RESULTS: The mean FOM increased from 0.528 to 0.737 with TS images (p < 0.0001). The mean sensitivity and FPC improved from 26.5% and 0.243 to 56.0% and 0.153 (p < 0.0001 and p = 0.239), respectively. The mean reading time was 173 s without TS and 170 s with TS (p = 0.925). CONCLUSION: The detectability of suspected brain infarctions was significantly improved with TS CT images. KEY POINTS: • Although it is established that MRI is superior to CT in the detection of strokes, the first choice of modality for suspected stroke patients is often CT. • An observer performance study with 14 radiologists was performed to evaluate whether temporal subtraction images derived from a non-rigid transformation algorithm can significantly improve the detectability of newly developed brain infarcts on CT. • Temporal subtraction images were shown to significantly improve the detectability of newly developed brain infarcts on CT.


Assuntos
Infarto Encefálico/diagnóstico por imagem , Técnica de Subtração , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Curva ROC , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Estudos Retrospectivos , Sensibilidade e Especificidade
17.
Clin Oral Investig ; 23(7): 3005-3020, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30374832

RESUMO

OBJECTIVES: The main objectives of this study were (1) to evaluate bone/graft density alterations by digital subtraction radiography; (2) to determine factors associated with favorable clinical and radiographic outcomes, and (3) to report on patient morbidity after guided tissue regeneration (GTR) in aggressive periodontitis (AgP) patients. MATERIALS AND METHODS: Adapting a split-mouth design, 30 comparative intrabony defects in 15 patients were randomly treated with xenogenic graft plus modified perforated membranes (MPM, tests) or xenogenic graft plus standard collagen membranes (CM, controls). The time period of observation was 12 months. RESULTS: There were significant improvements in clinical and radiographic parameters within each group, without intergroup differences. However, higher PPD reduction for three-wall defects was noted in MPM sites (5.22 versus 3.62 mm; p = 0.033). Moreover, a significant gain in bone/graft density of 4.9% from 6 to 12 months post-operatively was observed in test sites. Multivariate analysis demonstrated that morphology of intrabony defects was a predictor of CAL gain (p = 0.06), while independent prognostic variables effecting changes in bone/graft density were radiographic defect depth (p = 0.025) and radiographic angle (p = 0.033). The majority of patients reported some discomfort, pain, and edema with mild intensity without any significant differences between treatment modalities. CONCLUSIONS: This study demonstrated enhanced bone/graft density gain after GTR with MPM, which may indicate greater area of new bone formation. Independent variables effecting treatment outcomes were intrabony defect morphology, radiographic defect depth, and radiographic angle. CLINICAL RELEVANCE: This study supports the regenerative treatment of intrabony defects in AgP patients and identifies some variables with prognostic value.


Assuntos
Periodontite Agressiva , Perda do Osso Alveolar , Regeneração Tecidual Guiada Periodontal , Radiografia , Periodontite Agressiva/diagnóstico por imagem , Periodontite Agressiva/terapia , Seguimentos , Humanos , Membranas Artificiais , Perda da Inserção Periodontal , Prognóstico , Radiografia/métodos , Técnica de Subtração , Resultado do Tratamento
18.
Sci Rep ; 8(1): 15694, 2018 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-30356090

RESUMO

Optical coherence tomography angiography (OCTA) seems not to image the choroidal blood flow pattern in the normal individual because of the OCT light attenuation. Our purpose in the current study was to visualize the large choroidal blood flow pattern after subtraction of the choriocapillaris projection artifact in normal eyes non-invasively by swept source (SS) OCTA. Sixty-one eyes of 45 individuals (19 men, 26 women) without ocular disease were examined by SS-OCTA (AngioPlex Elite 9000, Zeiss, Germany). A 12 × 12 mm macular area was scanned. Subfoveal choroidal thickness (SCT) was measured, and the choroidal blood flow pattern in a slab of 30 µm width at one-half of SCT was analyzed. In examining the choroidal blood flow pattern, a slab that was between 30 to 60 µm posterior to the retinal pigment epithelium, in which the choriocapillaris blood flow was most clearly imaged, was used for the subtraction of the projection artifacts from the choriocapillaris on the stromal area of choroid. The ratio (%) of the choroidal blood flow area in the whole choroidal region was calculated after binarization. Thirty-four eyes of 27 individuals (12 men, 15 women) were also examined by spectral domain OCTA (SD-OCTA). After the subtraction, the middle and large choroidal blood flow were clearly visible in SS-OCTA in all eyes. The mean SCT was 297 ± 61 µm, and the mean ratio of the choroidal blood flow area was 27.3 ± 8.2%, which was significantly correlated with SCT (R = 0.738, P < 0.01). SD-OCTA did not show the choroidal blood flow pattern. In conclusion, removal of the projection artifacts of choriocapillaris can make the choroidal blood flow visible in SS-OCTA of normal eyes. Because the ratio of choroidal blood flow area was correlated with SCT, the choroidal blood flow might be an important factor related to the choroidal thickness.


Assuntos
Angiografia/métodos , Corioide/irrigação sanguínea , Tomografia de Coerência Óptica/métodos , Adulto , Idoso , Algoritmos , Artefatos , Corioide/diagnóstico por imagem , Sistemas de Computação , Movimentos Oculares , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Estudos Retrospectivos , Técnica de Subtração
19.
Eur J Radiol ; 107: 54-59, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30292273

RESUMO

PURPOSE: To assess the effectiveness of a CT temporal subtraction (TS) method on radiologists' performance in sclerotic metastasis detection in the thoracolumbar spine. MATERIALS AND METHODS: 20 pairs (current and previous CTs) of standard-dose CT and their TS images in patients with sclerotic bone metastasis and 20 pairs (current and previous CTs) of those in patients without bone metastasis were used for an observer performance study. A total of 135 lesions were identified as the reference standard of actionable lesions (sclerotic metastasis newly appeared or increased in size or in attenuation). 4 attending radiologists and 4 radiology residents participated in this observer study. Ratings and locations of "lesions" determined by the observers were utilized for assessing the statistical significance of differences between radiologists' performances without and with the CT-TS images in JAFROC analysis. The statistical significance of differences in the reviewing time was determined by a two-tailed paired t-test. RESULTS: The average figure-of-merit (FOM) values for all but one radiologist increased to a statistically significant degree, from 0.856 without the CT-TS images to 0.884 with the images (P = .037). The average sensitivity for detecting the actionable lesions was improved from 60.7 % to 72.5% at a false-positive rate of 0.15 per case by use of the CT-TS images. The average reading time with CT-TS images was significantly shorter than that without (150.6 s vs. 166.5 s, P = .004). CONCLUSION: The use of CT-TS would improve the observer performance for the detection of the sclerotic bone metastasis in the thoracolumbar spine.


Assuntos
Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/secundário , Neoplasias da Coluna Vertebral/diagnóstico por imagem , Neoplasias da Coluna Vertebral/secundário , Técnica de Subtração , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Vértebras Lombares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Coluna Vertebral/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem
20.
Comput Math Methods Med ; 2018: 5284969, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30363945

RESUMO

The clarity improvement and the noise suppression of digital subtraction angiography (DSA) images are very important. However, the common methods are very complicated. An image time-domain integration method is proposed in this study, which is based on the blood flow periodicity. In this method, the images of the first cardiac cycle after the injection of the contrast agent are integrated to obtain the time-domain integration image. This method can be used independently or as a postprocessing method of the denoising method on the signal image. The experimental results on DSA data from an aortic dissection patient show that the image time-domain integration method is efficient in image denoising and enhancement, which also has a good real-time performance. This method can also be used to improve the denoising and image enhancement effect of some common models.


Assuntos
Angiografia Digital/métodos , Aumento da Imagem/métodos , Técnica de Subtração , Aneurisma Dissecante/diagnóstico por imagem , Aorta/diagnóstico por imagem , Meios de Contraste , Humanos , Modelos Cardiovasculares , Modelos Estatísticos , Processamento de Sinais Assistido por Computador , Fatores de Tempo
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