Resting-state fMRI using passband balanced steady-state free precession.

OBJECTIVE: Resting-state functional MRI (rsfMRI) has been increasingly used for understanding brain functional architecture. To date, most rsfMRI studies have exploited blood oxygenation level-dependent (BOLD) contrast using gradient-echo (GE) echo planar imaging (EPI), which can suffer from image distortion and signal dropout due to magnetic susceptibility and inherent long echo time. In this study, the feasibility of passband balanced steady-state free precession (bSSFP) imaging for distortion-free and high-resolution rsfMRI was investigated. METHODS: rsfMRI was performed in humans at 3 T and in rats at 7 T using bSSFP with short repetition time (TR = 4/2.5 ms respectively) in comparison with conventional GE-EPI. Resting-state networks (RSNs) were detected using independent component analysis. RESULTS AND SIGNIFICANCE: RSNs derived from bSSFP images were shown to be spatially and spectrally comparable to those derived from GE-EPI images with considerable intra- and inter-subject reproducibility. High-resolution bSSFP images corresponded well to the anatomical images, with RSNs exquisitely co-localized to the gray matter. Furthermore, RSNs at areas of severe susceptibility such as human anterior prefrontal cortex and rat piriform cortex were proved accessible. These findings demonstrated for the first time that passband bSSFP approach can be a promising alternative to GE-EPI for rsfMRI. It offers distortion-free and high-resolution RSNs and is potentially suited for high field studies.

Severe acute respiratory syndrome: temporal lung changes at thin-section CT in 30 patients.

PURPOSE: To evaluate lung abnormalities on serial thin-section computed tomographic (CT) scans in patients with severe acute respiratory syndrome (SARS) during acute and convalescent periods. MATERIALS AND METHODS: Serial thin-section CT scans in 30 patients (17 men, aged 42.5 years +/- 12.2 [SD]) with SARS were reviewed by two radiologists together for predominant patterns of lung abnormalities: ground-glass opacities, ground-glass opacities with superimposed linear opacities, consolidation, reticular pattern, and mixed pattern (consolidation, ground-glass opacities, and reticular pattern). Scans were classified according to duration in weeks after symptom onset. Longitudinal changes of specific abnormalities were documented in 17 patients with serial scans obtained during 3 weeks. Each lung was divided into three zones; each zone was evaluated for percentage of lung involvement. Summation of scores from all six lung zones provided overall CT score (maximal CT score, 24). RESULTS: Median CT scores increased from 1 in the 1st week to 12.5 in the 2nd week. Ground-glass opacities with or without smooth interlobular septal thickening and consolidation were predominant patterns found during the 1st week. Ground-glass opacities with superimposed irregular reticular opacities, mixed pattern, and reticular opacities were noted from the 2nd week and peaked at or after the 4th week. After the 4th week, 12 (55%) of 22 patients had irregular linear opacities with or without associated ground-glass opacities and CT scores greater than 5; five of these patients had bronchial dilatation. When specific opacities were analyzed in 17 patients, consolidation generally resolved completely (n = 4) or to minimal residual opacities; six (55%) of 11 patients with ground-glass opacities had substantial residual disease (CT scores > 5) on final scans. CONCLUSION: There is a temporal pattern of lung abnormalities at thin-section CT in SARS. Predominant findings at presentation are ground-glass opacities and consolidation. Reticulation is evident after the 2nd week and persists in half of all patients evaluated after 4 weeks. Long-term follow-up is required to determine whether the reticulation represents irreversible fibrosis.

Silicosis in 76 men: qualitative and quantitative CT evaluation--clinical-radiologic correlation study.

PURPOSE: To use qualitative and quantitative computed tomography (CT) to test the hypothesis that impaired lung function with silicosis is due to progressive massive fibrosis (PMF) and associated emphysema. MATERIALS AND METHODS: Seventy-six men with silicosis underwent volumetric and thin-section CT of the thorax. Lung function, Borg scale dyspnea grade, silica exposure duration, and cigarette consumption were determined. Nodular profusion (NP) at chest radiography was graded according to the International Labor Organization radiographic classification system; NP and PMF at CT were visually graded by using five-point (ie, grades 0-4) and four-point (grades 0-3) scales, respectively. Emphysema and NP, which together are defined as the NP index, were quantified by using attenuation threshold values of less than -950 HU and greater than -100 HU, respectively. Mean lung attenuation was also determined. Relationships among the CT, chest radiographic, and clinical parameters were analyzed by using Spearman correlation. RESULTS: NP at chest radiography correlated (r > 0.50) with all CT parameters of nodularity. CT PMF had the highest correlation with emphysema (r = 0.58, P <.001). NP at chest radiography and all CT parameters were inversely related to lung function. At multiple regression analysis, PMF and emphysema index (both at CT) were significant determinants of forced expiratory volume in 1 second (FEV1) (P =.006 and.03, respectively) and FEV1 to forced vital capacity (FVC) ratio (P =.007 and.02, respectively). Mean lung attenuation remained related to FVC (P =.03), diffusing capacity of lung for carbon monoxide (P =.04), and Borg scale grade (P =.01). Cigarette consumption and silica exposure duration had no independent effects on lung function. CONCLUSION: Qualitative and quantitative CT parameters can be used as indirect measures of functional impairment in silicosis. PMF and emphysema are independently related to airflow obstruction, whereas mean lung attenuation is related to clinical dyspnea and reduced lung volume.

High-resolution CT quantification of bronchiectasis: clinical and functional correlation.

PURPOSE: To evaluate clinical relevance of high-resolution computed tomographic (CT) findings in patients with bronchiectasis by using a quantitative high-resolution CT protocol to assess extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic pattern. MATERIALS AND METHODS: Sixty Chinese patients with steady-state bronchiectasis underwent thoracic high-resolution CT and lung function tests. Exacerbation frequency per year and 24-hour sputum volume were determined. Extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic attenuation were evaluated in each lobe, including the lingula. Differences between sex and smoking status with respect to high-resolution CT, lung function, and clinical parameters were tested with either the independent sample t test or the Mann-Whitney test. Spearman rank correlation was used to evaluate associations between clinical, lung function, and high-resolution CT scores. Multiple regression analyses were performed to determine which high-resolution CT parameters would best predict lung function and clinical parameters, adjusted for smoking. RESULTS: Exacerbation frequency was associated with bronchial wall thickening (r = 0.32, P =.03); 24-hour sputum volume with bronchial wall thickening and small-airway abnormalities (r = 0.30 and 0.39, respectively; P <.05); and forced expiratory volume in 1 second (FEV(1)), ratio of FEV(1) to forced vital capacity (FVC), and midexpiratory phase of forced expiratory flow (FEF(25%-75%)) (r = -0.33, -0.29, and -0.32, respectively; P <.05). Extent of bronchiectasis, bronchial wall thickening, and mosaic attenuation, respectively, were related to FEV(1) (r = -0.43 to -0.60, P <.001), FEF(25%-75%) (r = -0.38 to -0.57, P <.001), FVC (r = -0.36 to -0.46, P <.01), and FEV(1)/FVC ratio (r = -0.31 to -0.49, P <.01). After multiple regression analysis, bronchial wall thickening remained a significant determinant of airflow obstruction, whereas small-airway abnormalities remained associated with 24-hour sputum volume. Women had milder disease than men but showed more high-resolution CT functional correlations. CONCLUSION: Findings of this study establish a link between morphologic high-resolution CT parameters and clinical activity and emphasize the role of bronchial wall thickening in patients with bronchiectasis.

Severe acute respiratory syndrome: radiographic evaluation and clinical outcome measures.

PURPOSE: To evaluate the relationship among chest radiographs, oxygen supplementation requirement, and treatment response in severe acute respiratory syndrome (SARS). MATERIALS AND METHODS: Forty patients (20 women, 20 men; mean age, 42.90 years +/- 14.01 [SD]; median age, 41.5 years; age range, 25-82 years) with SARS were evaluated. Daily chest radiographs were graded according to percentage of lung involvement during 20.15 days +/- 5.56 (median, 20 days; range, 14-38 days). Times between symptoms and treatment and time to reach maximal radiographic score from admission and treatment day were determined. Daily oxygen saturation (Sao2) and oxygen supplementation including mechanically assisted ventilation were recorded. Treatment response was defined as good, fair, and poor. Patterns of radiographic opacity at admission and at maximal radiographic score were noted. Differences in radiographic and clinical parameters with respect to oxygen supplementation and treatment response were respectively evaluated with Mann-Whitney and Kruskal-Wallis tests. RESULTS: Larger maximal radiographic scores, lower Sao2 at maximal radiographic change, longer time from treatment to maximal radiographic score (P <.01), and diffuse consolidation at maximal radiographic score were associated with oxygen supplementation. Parameters that influenced treatment response were time from symptom onset to treatment day (P =.003), time from admission to treatment day (P <.001), time to maximal radiographic score from treatment day (P =.001), maximal radiographic score (P =.009), Sao2 at maximal radiographic score (P =.13), and treatment radiographic score (P =.03). Fair responders had shorter time between admission and treatment than did either good (P <.001) or poor responders (P =.002) and shorter time between symptoms and treatment (P <.001) and lower treatment radiographic score (P =.012) than did good responders. Good (82%), poor (36%), and fair (33%) responders developed maximal chest radiographic scores within 4 days of treatment (P =.008). Radiographic patterns at both admission and maximal radiographic score did not influence treatment response. CONCLUSION: There are significant relationships among radiographic parameters, oxygen supplementation, and treatment response, and these relationships appear to be clinically useful in the treatment of SARS.

Severe acute respiratory syndrome: relationship between radiologic and clinical parameters.

PURPOSE: To quantify severity of severe acute respiratory syndrome (SARS) on chest radiographs and to determine its relationship with clinical parameters. MATERIALS AND METHODS: Forty patients (mean age, 42.90 years +/- 14.01 [SD]; median age, 41.5 years; age range, 25-82 years) with clinically diagnosed SARS were evaluated. Heart rate, oxygen saturation, temperature, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were recorded daily. Severity of lung changes on chest radiographs was scored according to percentage of involved lung. Radiographic scores at days of admission, treatment, and maximal radiographic score were extracted for statistical analysis with clinical parameters. Time to maximal radiographic score from admission and days between onset and beginning of treatment were determined. Correlations between radiographic and clinical parameters were evaluated with Spearman rank correlation. Sex differences with respect to clinical and radiographic parameters were evaluated with Mann-Whitney test. RESULTS: Median chest radiographic scores peaked 5 days after beginning of treatment before they declined. Maximal and treatment radiographic scores were inversely related to oxygen saturation (r = -0.67, P <.001; r = -0.35, P =.03). Admission radiographic score was correlated with admission AST level (r = 0.53, P =.003); treatment radiographic score, with treatment ALT and AST levels (r = 0.43, P =.007; r = 0.42, P =.019); and time to maximal radiographic score, with AST level at maximal radiographic score (r = -0.45, P =.006), admission radiographic score (r = -0.55, P <.001), treatment radiographic score (r = -0.58, P <.001), and admission ALT and AST levels (r = -0.44, P =.007; r = -0.58, P =.001). Treatment delay was associated with AST level at maximal radiographic score (r = 0.53, P =.001), treatment radiographic score (r = 0.60, P <.001), and time to maximal radiographic score (r = -0.36, P =.02). No sex differences occurred with respect to radiographic and clinical parameters (P >.05). CONCLUSION: Severity of lung abnormalities quantified on chest radiographs correlates with clinical and laboratory parameters.

Severe acute respiratory syndrome (SARS): chest radiographic features in children.

BACKGROUND: Severe acute respiratory syndrome (SARS) is a recently recognized condition of viral origin associated with substantial morbidity and mortality rates in adults. Little information is available on its radiologic manifestations in children. OBJECTIVE: The goal of this study was to characterize the radiographic presentation of children with SARS. MATERIALS AND METHODS: We abstracted data (n=62) on the radiologic appearance and course of SARS in pediatric patients with suspect (n=25) or probable (n=37) SARS, diagnosed in five hospital sites located in three cities: Toronto, Singapore, and Hong Kong. Available chest radiographs and thoracic CTs were reviewed for the presence of the following radiographic findings: airspace disease, air bronchograms, airways inflammation and peribronchial thickening, interstitial disease, pleural effusion, and hilar adenopathy. RESULTS: A total of 62 patients (suspect=25, probable=37) were evaluated for SARS. Patient ages ranged from 5.5 months to 17 years and 11.5 months (average, 6 years and 10 months) with a female-to-male ratio of 32:30. Forty-one patients (66.1%) were in close contact with other probable, suspect, or quarantined cases; 10 patients (16.1%) had recently traveled to WHO-designated affected areas within 10 days; and 7 patients (11.2%) were transferred from other hospitals that had SARS patients. Three patients, who did not have close/hospital contact or travel history to affected areas, were classified as SARS cases based on their clinical signs and symptoms and on the fact that they were living in an endemic area. The most prominent clinical presentations were fever, with a temperature over 38 degrees C (100%), cough (62.9%), rhinorrhea (22.6%), myalgia (17.7%), chills (14.5%), and headache (11.3%). Other findings included sore throat (9.7%), gastrointestinal symptoms (9.7%), rigor (8.1%), and lethargy (6.5%). In general, fever and cough were the most common clinical presentations amongst younger pediatric SARS cases (age<10 years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were common in older patients (age>/=10 years). The chest radiographs of 35.5% of patients were normal. The most prominent radiological findings that were observed in the remaining patients were areas of consolidation (45.2%), often peripheral with multifocal lesions in 22.6%. Peribronchial thickening was noted on chest radiographs of 14.5% of patients. Pleural effusion was observed only in one patient (age 17 years and 11.5 months), whereas interstitial disease was not observed in any patient. CONCLUSION: In pediatric cases, SARS manifests with nonspecific radiographic features making radiological differentiation difficult, especially from other commonly encountered childhood respiratory viral illnesses causing airspace disease. The radiographic presentation of suspected SARS cases ranged from normal to mild perihilar peribronchial thickening. The radiographic presentations, as expected, were relatively more pronounced in the SARS probable cases.