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At least 1,477 records · Page 82Linked to original sources

PubMed1999

Differential diagnosis of lymphocytic interstitial pneumonia and malignant lymphoma on high-resolution CT.

OBJECTIVE: Lymphoproliferative disorders span a spectrum from inflammatory lesions to malignant neoplasms. The purpose of this study was to compare high-resolution CT findings of lymphocytic interstitial pneumonia with those of malignant lymphoma of the chest. MATERIALS AND METHODS: The study included 17 patients with lymphocytic interstitial pneumonia and 44 patients with malignant lymphoma (35 with non-Hodgkin's lymphoma and nine with Hodgkin's disease). Without knowledge of the pathologic diagnosis, two chest radiologists evaluated the frequency and distribution of high-resolution CT findings in both groups of patients. RESULTS: Cysts were more common in patients with lymphocytic interstitial pneumonia (14/17, 82%) than in patients with malignant lymphoma (1/44, 2%) (p < .0001). Air-space consolidation was more commonly seen in patients with malignant lymphoma (29/44, 66%) than in patients with lymphocytic interstitial pneumonia (3/17, 18%) (p < .001). Large nodules (11-30 mm in diameter) were more common in patients with malignant lymphoma (41%) than in patients with lymphocytic interstitial pneumonia (6%). Pleural effusions (25%) were seen only in patients with malignant lymphoma. We found no statistically significant difference in the distribution of lung lesions between patients with lymphocytic interstitial pneumonia and patients with malignant lymphoma. CONCLUSION: On high-resolution CT, cysts are characteristic in patients with lymphocytic interstitial pneumonia, whereas consolidation, large nodules, and pleural effusions are characteristic in patients with malignant lymphoma. These findings on high-resolution CT help differentiate lymphocytic interstitial pneumonia from malignant lymphoma.

Adult↗

PubMed1999

High-resolution inspiratory and expiratory CT in older children and adults with bronchopulmonary dysplasia.

OBJECTIVE: The objective of this study is to correlate high-resolution inspiratory and expiratory CT findings with pulmonary function results in older children and adults who have bronchopulmonary dysplasia. SUBJECTS AND METHODS: High-resolution inspiratory and expiratory CT of the thorax was performed prospectively on 26 patients (16 male, 10 female) with a clinical history of bronchopulmonary dysplasia. The median age was 10 years old (range, 5-18 years). High-resolution CT during inspiration was scored for areas of decreased density and evidence of interstitial lung disease; expiratory CT was scored for air trapping. Findings were correlated with pulmonary function measurements and clinical history. RESULTS: Twenty-four (92%) of the 26 patients had abnormal CT findings. Of these 24, 22 had reticular opacities and 18 had areas of architectural distortion. Twenty patients had areas of relatively decreased density. In 24 patients, air trapping was seen on expiratory CT. Abnormal pulmonary function correlated significantly (p < .05) with abnormal decreases in density, air trapping on expiratory CT, and architectural distortion. CONCLUSION: Abnormal findings on inspiratory and expiratory high-resolution CT of older children with bronchopulmonary dysplasia include scarring and air trapping with architectural distortion. The correlation between these findings and physiologic evidence of air trapping and obstructive lung disease was statistically significant.

Adolescent↗

PubMed2000

Mycoplasma pneumoniae pneumonia: radiographic and high-resolution CT features in 28 patients.

OBJECTIVE: The aim of the study was to compare the radiographic and the high-resolution CT findings of Mycoplasma pneumoniae pneumonia. MATERIALS AND METHODS: The chest radiographs and 1.5-mm collimation CT scans obtained in 28 patients with serologically proven M. pneumoniae pneumonia were retrospectively reviewed. The radiographs and CT scans were analyzed independently by two observers. RESULTS: The most common finding on radiography was the presence of air-space opacification (n = 24), which was patchy and segmental (n = 9) or nonsegmental (n = 15) in distribution. On high-resolution CT, areas of ground-glass attenuation were seen in 24 patients (86%) and air-space consolidation in 22 (79%). In 13 patients (59%), the areas of consolidation had a lobular distribution evident on CT. Nodules were seen more commonly on high-resolution CT (25 of 28 patients, 89%) than on radiography (14 patients, 50%) (p < 0.01, chi-square test). In 24 (86%) of the 28 patients, the nodules had a predominantly centrilobular distribution on CT. Thickening of the bronchovascular bundles was identified more commonly on CT (23 of 28 patients, 82%) than on radiography (five patients, 18%) (p < 0.01, chi-square test). CONCLUSION: The lobular distribution, centrilobular involvement, and interstitial abnormalities in M. pneumoniae pneumonia are often difficult to recognize on radiography but can usually be seen on high-resolution CT.

Adolescent↗

PubMed2000

Acute parenchymal lung disease in immunocompetent patients: diagnostic accuracy of high-resolution CT.

OBJECTIVE: The purpose of this study was to determine whether acute parenchymal lung diseases can be differentiated on the basis of the pattern and distribution of abnormalities revealed on high-resolution CT. MATERIALS AND METHODS: High-resolution CT scans of 90 patients with acute parenchymal lung diseases (19 with bacterial pneumonia, 13 with mycoplasmal pneumonia, 21 with acute interstitial pneumonia, 18 with hypersensitivity pneumonitis, 10 with acute eosinophilic pneumonia, and nine with pulmonary hemorrhage) were independently assessed by two observers who had no knowledge of clinical or pathologic data. The observers recorded abnormalities, their first-choice diagnosis, and their degree of confidence in their first-choice diagnosis. RESULTS: The two observers made a correct first-choice diagnosis in an average of 55 (61%) of 90 cases. Correct first-choice diagnosis was made in 50% of cases of bacterial pneumonia, 62% of mycoplasmal pneumonia, 90% of acute interstitial pneumonia, 72% of hypersensitivity pneumonitis, 30% of acute eosinophilic pneumonia, and 28% of pulmonary hemorrhage. CT findings allowed distinction between infectious and noninfectious causes in 81 (90%) of 90 cases. CONCLUSION: High-resolution CT is helpful in the differential diagnosis of infectious from noninfectious acute parenchymal lung disease. However, high-resolution CT is of limited value in making a specific diagnosis.

Acute Disease↗

PubMed2001

Selenium-based digital radiography versus high-resolution storage phosphor radiography in the detection of solitary pulmonary nodules without calcification: receiver operating characteristic curve analysis.

OBJECTIVE: The purpose of this study was to compare selenium-based digital radiography with high-resolution storage phosphor radiography for the detection of solitary pulmonary nodules without calcification. MATERIALS AND METHODS: One hundred twenty-four patients underwent selenium-based digital radiography, high-resolution storage phosphor radiography, and chest CT for evaluation of pulmonary nodules. Thirty-one patients with pulmonary nodules smaller than 3 cm in diameter and 40 patients with normal lungs were selected for receiver operating characteristic curve analysis. Five board-certified radiologists who were unaware of the CT results independently reviewed each of the hard copies of selenium-based digital radiography and storage phosphor radiography, identified pulmonary nodules, and graded their confidence for the presence of each nodule. For each radiologist, we calculated the areas under the receiver operating characteristic curve (AUC) for selenium-based digital radiography and storage phosphor radiography. RESULTS: The average performance of selenium-based digital radiography (AUC = 0.72) was higher than that of high-resolution storage phosphor radiography (AUC = 0.64), which is statistically significant (p <0.05). CONCLUSION: Our results indicate that selenium-based digital radiography is superior to high-resolution storage phosphor radiography for detecting solitary pulmonary nodules without calcification.

Adult↗

PubMed2002

Occult fractures of the waist of the scaphoid: early diagnosis by high-spatial-resolution sonography.

OBJECTIVE: This study evaluated the diagnostic accuracy of high-spatial-resolution sonography in the diagnosis of occult fractures of the waist of the scaphoid. SUBJECTS AND METHODS: Sonography of the scaphoid bone with a 12-MHz transducer was performed in 54 patients with clinically suspected scaphoid fracture and normal findings on initial radiographs, including specific scaphoid images. Three levels of clinical suspicion were considered: high (20%), moderate (30%), and low (50%). Attention was paid to the continuity of the scaphoid cortex and to the surrounding soft tissues (i.e., hemarthrosis or hematoma). Data from early sonograms were then compared with the results of radiography repeated 10-14 days after the initial trauma. In cases of persistent suspicion despite normal findings on follow-up radiographs, the presence of fracture was evaluated on CT (four patients), MR imaging (one patient), or bone scanning (one patient). RESULTS: Follow-up examinations proved fracture of the scaphoid waist in five patients. In all patients, diagnosis of fracture was suspected on initial sonograms showing cortical disruption associated with soft-tissue abnormalities. There was one false-positive finding and no false-negative results. Using cortical disruption as a diagnostic criterion, we found the sensitivity, specificity, and accuracy of high-resolution sonography for the depiction of scaphoid fracture to be 100%, 98%, and 98%, respectively. Using soft-tissue abnormalities alone as a criterion, we found the sensitivity, specificity, and accuracy of high-resolution sonography to be 100%, 65%, and 68%, respectively. The overall prevalence of occult fracture was 9%, ranging from 3.7% for low suspicion to 27% for high suspicion of fracture. CONCLUSION: High-resolution sonography is a reliable and accurate method of evaluating occult fractures of the scaphoid waist. Cortical disruption is the diagnostic key. Soft-tissue abnormalities alone lack specificity.

Adolescent↗

PubMed2004

Coronal reformations of volumetric expiratory high-resolution CT of the lung.

OBJECTIVE: The purposes of this study were to evaluate the quality of coronal reformatted images obtained from volumetric expiratory high-resolution CT imaging and to compare coronal and axial images with regard to their usefulness in detecting and characterizing air trapping. SUBJECTS AND METHODS. We studied 40 consecutive patients with known or suspected diffuse lung diseases with airway abnormalities who underwent volumetric expiratory high-resolution CT between May and July 2003. Respiratory motion artifacts were evaluated at upper, middle, and lower lung areas. Cardiac motion, beam-hardening, and other artifacts were evaluated throughout the lung fields. Detectability, clarity of borders, size, distribution, and extent of air trapping were compared on axial versus coronal end-expiratory high-resolution CT images. RESULTS: Respiratory motion artifacts were either imperceptible or not diagnostically limiting in all patients except three (7%) with diagnostically limiting image degradation at lower lung areas. Other diagnostically limiting image degradation was caused by beam-hardening artifacts in two patients (5%) and by quantum noise in two other patients (5%). The borders of air trapping were more clearly identified on coronal images than on axial images (grade 1 [vague], nine vs three; grade 2 [partially clear], 23 vs 21; grade 3 [completely clear], eight vs 16; median, two vs two; p = 0.001). The coronal reformatted images were as informative as axial images for detecting and assessing the classification and extent of air trapping. CONCLUSION: Coronal reformations of volumetric expiratory high-resolution CT scans were acceptable in image quality and provided additional value by affording clearer visualization of the borders of air trapping than was found in contiguous axial images.

Adult↗

PubMed2004

High-resolution CT findings of respiratory syncytial virus pneumonia after bone marrow transplantation.

OBJECTIVE: The aim of this study was to describe the high-resolution CT findings of respiratory syncytial virus pneumonia in 20 patients who had undergone allogeneic bone marrow transplantation. MATERIALS AND METHODS: The study included 20 consecutive patients who developed respiratory syncytial virus pneumonia after bone marrow transplantation and who had high-resolution CT of the chest performed within 24 hr after the onset of symptoms. The CT scans were reviewed by two chest radiologists who assessed the pattern and distribution of findings. RESULTS: Bone marrow transplantation was performed on 12 male and eight female patients ranging from 3 to 48 years old (mean age, 25 years) for treatment of various forms of leukemia (n = 12), severe aplastic anemia (n = 6), Fanconi's syndrome (n = 1), and paroxysmal nocturnal hemoglobinuria (n = 1). Sixteen patients (80%) had abnormal CT findings. The predominant patterns of abnormality on high-resolution CT scans were small centrilobular nodules (10/20, 50%), air-space consolidation (7/20, 35%), ground-glass opacities (6/20, 30%), and bronchial wall thickening (6/20, 30%). The abnormalities were distributed in the central and peripheral areas of the lungs in nine cases, only in the periphery in five cases, and only in the central regions in two cases. The abnormalities were bilateral and asymmetric in distribution in 13 patients, bilateral and symmetric in two patients, and unilateral in one patient. CONCLUSION: The most common high-resolution CT findings in patients with respiratory syncytial virus pneumonia after bone marrow transplantation consist of small centrilobular nodules and multifocal areas of consolidation and ground-glass opacities in a bilateral asymmetric distribution.

Adolescent↗

PubMed2006

Genotyping of human platelet antigens 1 to 6 and 15 by high-resolution amplicon melting and conventional hybridization probes.

High-resolution melting techniques are a simple and cost-effective alternative to other closed-tube genotyping methods. Here, we genotyped human platelet antigens (HPAs) 1 to 6 and 15 by high-resolution melting methods that did not require labeled probes. Conventional melting analysis with hybridization probes (HybProbes) was also performed at each locus. HybProbe assays were performed individually, whereas amplicon melting (HPAs 1 to 5 and 16) and unlabeled probe (HPA 6) assays were duplexed when possible. At all loci for each method, both homozygous and heterozygous genotypes were easily identified. We analyzed 100 blinded clinical samples (33 amniotic fluid, 12 cultured amniocytes, and 55 blood samples) for all 7 single-nucleotide polymorphisms (SNPs) by each method. Genotype assignments could be made in 99.0% of the SNPs by high-resolution melting and in 98.7% of the SNPs with HybProbes with an overall genotype concordance of 98.8%. Errors included two sample misidentifications and six incorrect assignments that were all resolved by repeating the analysis. Advantages of high-resolution melting include rapid assay development and execution, no need for modified oligonucleotides, and similar accuracy in genotyping compared with other closed-tube melting methods.

Antigens, Human Platelet↗

PubMed2006

Magnetic resonance microscopy of the equine hoof wall: a study of resolution and potential.

REASONS FOR PERFORMING STUDY: Obtaining magnetic resonance images of the inner hoof wall tissue at the microscopic level would enable early accurate diagnosis of laminitis and therefore more effective therapy. OBJECTIVES: To optimise magnetic resonance imaging (MRI) parameters in order to obtain the highest possible resolution of the structures beneath the equine hoof wall. METHODS: Magnetic resonance microscopy (MRM) was performed in front feet from 6 cadaver horses using T2-weighted fast spin echo (FSE-T2), and T1-weighted gradient echo (GRE-T1) sequences. RESULTS: In T2 weighted FSE images most of the stratum medium showed no signal, however the coronary, terminal and sole papillae were visible. The stratum lamellatum was clearly visible and primary epidermal lamellae could be differentiated from dermal lamellae. CONCLUSION: Most structures beneath the hoof wall were differentiated. Conventional scanners for diagnostic MRI in horses are low or high field. However this study used ultra-high field scanners currently not available for clinical use. Signal-to-noise ratio (S/N) increases as a function of field strength. An increase of spatial resolution of the image results in a decreased S/N. S/N can also be improved with better coils and the resolution of high field MRI scanners will increase as technology develops and surface array coils become more readily available. POTENTIAL RELEVANCE: Although MR images with microscopic resolution were obtained ex vivo, this study demonstrates the potential for detection of lamellar pathology as it occurs. Early recognition of the development of laminitis to instigate effective therapy at an earlier stage and may improve the outcome for laminitic horses. Clinical MR is now readily available at 3 T, while 4 T, 7 T and 9 T systems are being used for human whole body applications.

Abattoirs↗

PubMed1996

The selective effect of optical defocus on detection and resolution acuity in peripheral vision.

Detection and resolution acuity was measured at 30 degrees in the periphery for sinusoidal gratings under differing amounts of optical defocus. Within the range -2.0 to +2.5 diopters defocus, detection acuity was higher than resolution acuity. As defocus increased, detection acuity decreased continuously but resolution acuity was little affected until around 2.0 diopters defocus. The results indicate that resolution performance is sampling limited in peripheral vision, even for significant refractive error, and is more robust than detection acuity to the effects of optical defocus.

Humans↗

PubMed1998

High-resolution T2-reversed magnetic resonance imaging on a high magnetic field system. Technical note.

Because of the high signal-to-noise (S/N) ratio, T2-weighted images obtained using high-field magnetic resonance (MR) imaging systems can be expected to provide high anatomical and contrast resolution. Furthermore, the improved structural and contrast resolution of these high S/N T2-weighted images can be processed for optimum perceptual resolution through the application of gray-scale reversal and expansion of the gray-scale window, known as T2-reversed (T2R) imaging. In this study, the authors investigated high-resolution T2R MR imaging performed on a high-field (3-tesla) system for its clinical utility in detecting various physiological and pathological conditions.

Adolescent↗

PubMed2005

High-resolution three-dimensional T2-weighted sequence for neuronavigation: a new setup and clinical trial.

OBJECT: Conventional imaging for neuronavigation is performed using high-resolution computerized tomography (CT) scanning or a T1-weighted isovoxel magnetic resonance (MR) sequence. The extension of some lesions, however, is depicted much better on T2-weighted MR images. A possible fusion process used to match low-resolution T2-weighted MR image set with a referenced CT or T1-weighted data set leads to poor resolution in the three-dimensional (3D) reconstruction and decreases accuracy, which is unacceptable for neuronavigation. The object of this work was to develop a 3D T2-weighted isovoxel sequence (3D turbo-spin echo [TSE]) for image-guided neuronavigation of the whole brain and to evaluate its clinical application. METHODS: The authors performed a phantom study and a clinical trial on a newly developed T2-weighted isovoxel sequence, 3D TSE, for image-guided neuronavigation using a common 1.5-tesla MR imager (Siemens Sonata whole-body imager). The accuracy study and intraoperative image guidance were performed with the aid of the pointer-based Medtronic Stealth Station Treon. The 3D TSE data set was easily applied to the navigational setup and demonstrated a high registration accuracy during the experimental trial and during an initial prospective clinical trial in 25 patients. The sequence displayed common disposable skin fiducial markers and provided convincing delineation of lesions that appear hyperintense on T2-weighted images such as low-grade gliomas and cavernomas in its clinical application. CONCLUSIONS: Three-dimensional TSE imaging broadens the spectrum of navigational and intraoperative data sets, especially for lesions that appear hyperintense on T2-weighted images. The accuracy of its registration is very reliable and it enables high-resolution reconstruction in any orientation, maintaining the advantages of image-guided surgery.

Adult↗

PubMed2000

Spontaneous resolution and recurrence of a Chiari I malformation and associated syringomyelia. Case report.

The spontaneous resolution of syringomyelia has been reported infrequently. In patients with Chiari I malformations, resolution of the syringomyelia has sometimes been associated with improvement of their malformation. The authors present a case of spontaneous resolution followed by recurrence of syringomyelia and a corresponding change in the Chiari malformation. This case is of interest in light of the theories postulated to explain spontaneous resolution of syringomyelia.

Arnold-Chiari Malformation↗

PubMed2026

Longitudinal In Vivo Imaging at Single-Lesion Resolution Identifies Allele-Associated Response and Resistance Dynamics in EGFR-Mutant Lung Cancer.

Acquired resistance to targeted therapies is inevitable in EGFR-mutant non-small cell lung cancer (NSCLC), yet the principles governing its emergence in vivo remain incompletely understood. In particular, how lesion-level response patterns vary across distinct EGFR allele contexts during therapy has not been systematically examined at single-lesion resolution. Here, we establish a longitudinal in vivo imaging platform enabling single-lesion resolution tracking of tumor behavior during therapy in genetically engineered mouse models representing clinically relevant EGFR alleles. Using high-resolution micro-computed tomography (micro-CT) and three-dimensional reconstruction, we monitor tumor growth, therapeutic response, and resistance during osimertinib treatment. EGFR genotype is associated with distinct patterns of tumor growth, response kinetics, and resistance timing. Therapeutic response is spatially heterogeneous, with coexisting lesions undergoing complete regression, persistence, or progression within the same lung. During treatment, spatially distinct lesion-level behaviors included persistent growth during therapy and initial regression followed by regrowth. These findings demonstrate the utility of longitudinal micro-CT imaging to investigate allele-associated differences in treatment response and resistance timing at single-lesion resolution in vivo.

Animals↗

PubMed2006

How attention enhances spatial resolution: evidence from selective adaptation to spatial frequency.

In this study, we investigated how spatial resolution and covert attention affect performance in a texture segmentation task in which performance peaks at midperiphery and drops at peripheral and central retinal locations. The central impairment is called the central performance drop (CPD; Kehrer, 1989). It has been established that attending to the target location improves performance in the periphery where resolution is too low for the task, but impairs it at central locations where resolution is too high. This is called the central attention impairment (CAI; Yeshurun & Carrasco, 1998, 2000). We employed a cuing procedure in conjunction with selective adaptation to explore (1) whether the CPD is due to the inhibition of low spatial frequency responses by high spatial frequency responses in central locations, and (2) whether the CAI is due to attention's shifting sensitivity to higher spatial frequencies. We found that adaptation to low spatial frequencies does not change performance in this texture segmentation task. However, adaptation to high spatial frequencies diminishes the CPD and eliminates the CAI. These results indicate that the CPD is primarily due to the dominance of high spatial frequency responses and that covert attention enhances spatial resolution by shifting sensitivity to higher spatial frequencies.

Attention↗

PubMed2005

Comparison of children's performance on four tests of temporal resolution.

This paper presents a brief review of temporal processing, its relevance to audiologists, and methods for its clinical evaluation. Results are then summarized from the administration of four tests of auditory temporal resolution (Auditory Fusion Test-Revised [AFTR], Random Gap Detection Test [RGDT], Binaural Fusion Test [BFT], and Gaps-In-Noise Test [GIN]) to ten children with normal hearing (mean age = 8.7 years). Statistically significant differences in mean temporal resolution thresholds derived from the four tests resulted from differences in stimulus and task variables. From a clinical perspective, however, all tests yielded comparable results, indicating normal temporal resolution for all 10 children. Differences among the four tests with regard to ease of use, time required for administration and scoring, and face validity are discussed. Additional research is needed to determine the relative sensitivity and specificity, and, therefore, the clinical utility of these four temporal resolution tests in both pediatric and adult populations.

Acoustic Stimulation↗

PubMed1986

Experimental study on the collimator for increasing the resolution of N-isopropyl-p-(123I)iodoamphetamine (IMP) SPECT imaging of the brain.

This study was carried out to design a new collimator for the present 123I-IMP SPECT imaging of the brain, which is hindered by the contamination of 124I and 126I. In this study we intended to increase spacial resolution along the transaxial direction and, at the same time, to compensate for the decrease of sensitivity by sacrificing the resolution along the axial direction to some extent. For this purpose, we developed 4 kinds of slat type units; ultrahigh resolution (UHR), high resolution (HR), high sensitivity (HS), and ultrahigh sensitivity (UHS). In practice, either UHR or HR is set to the detector together with either HS or UHS. After testing 4 kinds of combinations, we found that the combination of UHR-HS gave us far better images than those obtained with the conventional medium energy parallel hole collimator and was best suited for 123I-IMP SPECT imaging of the brain at present. We are now thinking of fusing these two units together into one collimator.

Amphetamines↗