Magnetic resonance (MR) imaging of lung parenchyma is limited by the low proton density and short T2 in the lung as well as the effects of susceptibility and motion. The MR imaging appearance of lung parenchyma was investigated with a pulse sequence that offers some solutions to these problems. This sequence employs projection reconstruction (PR) acquisition gradients and a section-selective excitation pulse designed to eliminate the need to refocus and to allow low-frequency k-space data to be collected with minimal delay. Echo times as short as 50 microseconds can be achieved, producing a proton-density-weighted image. An excised inflated lung specimen and specimens from human subjects with normal lungs (n = 3), pulmonary arteriovenous malformations (n = 1), bronchogenic carcinoma (n = 1), and bullous lung disease with lung metastases (n = 1) were examined. Signal intensity from lung parenchyma and visibility of pulmonary structures were superior on images obtained with the PR MR imaging technique compared with spin-echo images.
PURPOSE:To compare lung densitometric measurements that use a threedimensional (3D) reconstruction of the lungs with those obtained from analysis of two-dimensional (2D) computed tomographic (CT) images, visual emphysema scores, and data from pulmonary function tests. MATERIALS AND METHODS:Thoracic helical CT scans were obtained in 60 adult patients (35 with no visual evidence of emphysema and 25 with emphysema). The lungs were reconstructed as a 3D model on a commercial workstation, with a threshold of Ϫ600 HU. By analysis of histograms, the proportions of lung volumes with attenuation values below Ϫ950, Ϫ910, and Ϫ900 HU were measured, in addition to mean lung attenuation. These values were compared with lung densitometric results obtained from 2D CT images, visual emphysema scores, and data from pulmonary function tests. RESULTS:Quantitation of emphysema with 3D reconstruction was efficient and accurate. Correlation was good among densitometric quantitation with 3D analysis, that obtained with 2D analysis (r ϭ 0.98-0.99), and visual scoring (r ϭ 0.74-0.82). Correlation was reasonable between 3D densitometric quantitation and the diffusing capacity of the lungs for carbon monoxide (DLCO) (r ϭ Ϫ0.57 to Ϫ0.64), total lung capacity (r ϭ 0.62-0.71), forced expiratory volume in 1 second (FEV 1 ) (r ϭ Ϫ0.57 to Ϫ0.60), and the ratio of FEV 1 to forced vital capacity (FVC) (r ϭ Ϫ0.75 to Ϫ0.82). The visual CT quantitation of emphysema correlated best with DLCO (r ϭ Ϫ0.82) and FEV 1 /FVC (r ϭ Ϫ0.89). CONCLUSION:Lung densitometry with 3D reconstruction of helical CT data is a fast and accurate method for quantifying emphysema.Computed tomographic (CT) quantitation of emphysema has been correlated with pulmonary function (1-4) and has been used to predict postoperative function in patients with lung cancer (5); more recently, such quantitation has been used to demonstrate a decrease in emphysema after lung-volume reduction surgery (6-10). The two systems that are used for quantitation of emphysema are visual grading and more objective techniques that use CT software to distinguish pixels with abnormally low attenuation, representing emphysema, from those of normal lung.First applied to two-dimensional (2D) CT sections, the ''density mask'' technique was shown to represent accurately the morphologic extent of emphysema (11) Abbreviations:DLCO ϭ diffusing capacity of the lungs for carbon monoxide FEV 1 ϭ forced expiratory volume in 1 second FVC ϭ forced vital capacity TLC ϭ total lung capacity 2D ϭ two-dimensional 3D ϭ three-dimensional
Magnetic susceptibility effects in magnetic resonance (MR) imaging of normal lung parenchyma occur because of magnetic-field inhomogeneities induced by the microscopic heterogeneity of the lung. The effects on MR imaging of the lung are loss of signal from intravoxel phase dispersion (measured with T2') and a shift in the macroscopic resonant frequency from that of water toward that of air (delta v). These effects of MR imaging at 1.5 T were quantitated by measuring T2' decay and delta v at different locations in the lungs of two adult volunteers and one excised inflated human lung. The average T2' was 7 msec in the excised inflated specimen and 6.3 msec in normal in vivo lungs. There was a gravitational increase in T2' from nondependent to dependent lung. T2' increased to 35 msec in atelectatic lung tissue and to more than 140 msec in tumor. The macroscopic resonant lung frequency increased to 3.6 ppm more than that of mediastinal muscle. These values are important for developing MR pulse sequences appropriate for imaging lung parenchyma.
Introduction Since the introduction of a shared e‐scooter service to Auckland in October there have been multiple media reports of associated injuries, but no quantitation of the number or severity of these injuries, or the impact on hospital emergency department services in Auckland. Methods We performed a retrospective chart review on all patients referred to Auckland hospital ED radiology with the indication containing ‘e‐scooter’ between 15 August 2018 and 15 December 2018. All requests were screened to ensure that the injury was caused by an e‐scooter. Recorded data included patient demographics, type of imaging utilised, injury type, and whether admission or surgery was required. Results Sixty‐four patients met the inclusion criteria, only one of these was prior to introduction of shared e‐scooters on 15 October 2018. Of these, there were 27 limb fractures, 3 dislocations, a fractured spine, 12 patients with concussion, 1 extra‐dural bleed, 9 facial/skull fractures and multiple soft tissue injuries. Almost 40% of the patients required admission to a specialty service following imaging, and 25.4% required surgery. A total of 221 plain films and 47 CT scans were performed for e‐scooter injuries in the 2‐month period after their introduction. Conclusion Introduction of shared e‐scooters has resulted in a large number of serious related injuries that have required urgent radiology imaging. Many of these patients required further specialist consultation or surgery, and place an increased burden on overstretched emergency department services.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.