Comparison of thyroid stimulating activities measured by cyclic AMP production, those by radioiodine uptake in FRTL-5 cells and TSH-binding inhibitory activities in patients with hyperthyroid and euthyroid Graves' diseases

By using an assay measuring cAMP production in FRTL-5 thyroid cells, thyroid stimulating antibodies (TSab) were detected in all of 15 patients with euthyroid Graves' disease (EG) and of 26 patients with hyperthyroid Graves' disease (HG). There was no significant difference between TSab activities in EG and in HG. In an effort to elucidate why EG patients remain euthyroid in spite of having TSab, we investigated the effect of the patient's crude immunoglobulin fractions on 125I uptake in FRTL-5 thyroid cells, one of the indices of stimulation subsequent to cAMP production. The 125I uptake stimulating (IUS) activity was positive in 46.7% (7/15) of EG patients and 88.5% (23/26) of HG patients, being significantly lower in the former than in the latter (P less than 0.02). Although the IUS activities significantly correlated with TSab activities in 41 patients with EG and HG (r = 0.784, P less than 0.001), the ratio of IUS to TSab in EG tended to be lower than that in HG. TSH-binding inhibitor immunoglobulins (TBII) activities in EG patients were negative or weakly positive, being significantly lower than those in HG patients (P less than 0.001). Thus, the ratios of TBII to both TSab and IUS activities were significantly higher in HG than in EG (P less than 0.01, P less than 0.001, respectively). The in vitro IUS activities also correlated with TBII activities (r = 0.441, P less than 0.001) and in vivo 99mTc thyroid uptake (r = 0.401, P less than 0.001) in both EG and HG patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multislice CT evaluation of airway stents

Tracheobronchial stents are playing an increasing role in the palliative treatment of large airway obstruction due to a variety of conditions, including extrinsic compression, intraluminal disease, and malacia. Computed tomography (CT) plays an important role in aiding planning of stent placement and in detecting various stent complications. In this pictorial essay, we illustrate and review the role of multislice CT in the pre- and post-stent placement settings. A special emphasis is placed upon the characteristic CT appearance of specific stent complications and upon the role of CT multiplanar reformations and 3-dimensional (3-d) reconstruction techniques.     

MR imaging of benign and malignant pleural disease

MR imaging serves as a problem-solving tool in the diagnosis of inflammatory and infectious pleural diseases and primary and secondary pleural malignancies. Knowledge of MR imaging appearance of pleural diseases, including pleural effusions and empyema, benign and malignant pleural tumors, and especially mesothelioma, helps guide treatment decisions and surgical planning.     

Basics concepts and clinical applications of oxygen-enhanced MR imaging

Oxygen-enhanced MR imaging is a new technique, and its physiological significance has not yet been fully elucidated. This review article covers (1) the theory of oxygen enhancement and its relationship with respiratory physiology; (2) design for oxygen-enhanced MR imaging sequencing; (3) a basic study of oxygen-enhanced MR imaging in animal models and humans; (4) a clinical study of oxygen-enhanced MR imaging; and (5) a comparison of advantages and disadvantages of this technique with those of hyperpolarized noble gas MR ventilation imaging. Oxygen-enhanced MR imaging provides not only the ventilation-related, but also respiration-related information. Oxygen-enhanced MR imaging has the potential to replace nuclear medicine studies for the identification of regional pulmonary function, and many investigators are now attempting to adapt this technique for routine clinical studies. We believe that further basic studies as well as clinical applications of this new technique will define the real significance of oxygen-enhanced MR imaging for the future of pulmonary functional imaging and its usefulness for diagnostic radiology and pulmonary medicine.     

MR microscopy of the lung in small rodents

Understanding how the mammalian respiratory system works and how it changes in disease states and under the influence of drugs is frequently pursued in model systems such as small rodents. These have many advantages, including being easily obtained in large numbers as purebred strains. Studies in small rodents are valuable for proof of concept studies and for increasing our knowledge about disease mechanisms. Since the recent developments in the generation of genetically designed animal models of disease, one needs the ability to assess morphology and function in in vivo systems. In this article, we first review previous reports regarding thoracic imaging. We then discuss approaches to take in making use of small rodents to increase MR microscopic sensitivity for these studies and to establish MR methods for clinically relevant lung imaging.     

Pulmonary nodule detection in CT images with quantized convergence index filter

A novel filter termed quantized convergence index filter (QCI filter) that is capable of enhancing the conspicuity of rounded lesions is proposed as part of a CAD (computer-aided diagnosis) scheme for detecting pulmonary nodules in computed tomography (CT) images. In this filter and its predecessor, the convergence index filter (CI filter), the output at a pixel represents the degree of convergence toward the pixel shown by the directions of gray-level gradients at surrounding pixels. The QCI filter and the CAD scheme were evaluated using five clinical datasets containing 50 nodules. With the support region of 9 x 9 pixels, the QCI filter showed more selective response to the nodules than the CI filter. In the CAD scheme, intermediate nodule candidates are generated based on the QCI filter output and then classified using linear discriminant analysis of eight features that are attributed to each intermediate nodule candidate. The QCI filter output level itself was used as one of the features. The scheme achieved a sensitivity of 90% with 1.67 false positives per slice. The QCI filter output level was most effective among the features in correctly classifying intermediate nodule candidates. The QCI filter is promising as a tool of preprocessing for automated pulmonary nodule detection in CT images.     

Fetal lung volume measurements: determination with MR imaging--effect of various factors

PURPOSE: To retrospectively determine the effect of gestational age (GA), imaging plane, section thickness, and inter- and intraobserver variability on fetal lung volume (FLV) measurements obtained with magnetic resonance (MR) imaging in a cohort of fetuses without thoracic abnormalities. MATERIALS AND METHODS: Institutional review board approval was obtained. Informed consent for this retrospective cohort study was waived, and the conduct of this study was HIPAA compliant. FLV was measured in 30 fetuses (GA, 17-36 weeks) referred for MR imaging for indications other than pulmonary abnormalities. Measurements were made on single-shot fast spin-echo images by tracing free-form regions of interest on individual consecutive sections in the transverse, sagittal, and coronal planes. Measurements were performed twice by two observers independently. Correlations between FLV and GA, imaging plane, and section thickness were assessed, as were intra- and interobserver variability. Time to perform FLV was assessed in a subset of fetuses. RESULTS: Total FLV ranged from 2 to 110 mL. Mixed-effects regression model showed significant quadratic trend in FLV with increasing GA, with comparable strength of correlation (r = 0.89-0.91) in the three imaging planes of measurement. Intraobserver agreement was good in all three planes (r = 0.65-0.83) and was highest in the transverse plane. Interobserver agreement was good in all three planes (r = 0.68-0.76). FLV showed no significant dependence on section thickness (P = .23) or imaging plane (P = .82). Mean time to obtain FLV measurements ranged from 48 seconds at GA of 21 weeks to 77 seconds at GA of 29-30 weeks. CONCLUSION: GA-based FLV measurements obtained with MR images are independent of section thickness and imaging plane and can be performed with good inter- and intraobserver agreement in less than 2 minutes.     

Demonstration of gravity-dependent lung perfusion with contrast-enhanced magnetic resonance imaging

Imaging of lung perfusion using contrast-enhanced dynamic magnetic resonance (MR) was performed in both the supine and prone positions in six volunteers. Regions of interest (ROIs) were chosen in the dependent and non-dependent portions of the right lung. The percentage increase in signal intensity (SI) and the mean slope were calculated. In the supine position, the dorsal ROI had a greater increase in SI (236.0% vs. 156.9%, P < 0.05) and a faster rise in the slope of enhancement (55.1%/sec vs. 30.1%/sec, P < 0.05) than the ventral ROI. After changing to the prone position, higher peak enhancement (234.3% vs. 177.4%, P < 0.05) and faster slopes (59.6%/sec vs. 35.3%/sec, P < 0.05) shifted to the anterior ROI. We conclude that dynamic contrast-enhanced MR imaging is sensitive to demonstrate gravitationally dependent differences in lung perfusion.