MRI of the lung (2/3). Why … when … how?

Background Among the modalities for lung imaging, proton magnetic resonance imaging (MRI) has been the latest to be introduced into clinical practice. Its value to replace X-ray and computed tomography (CT) when radiation exposure or iodinated contrast material is contra-indicated is well acknowledged: i.e. for paediatric patients and pregnant women or for scientific use. One of the reasons why MRI of the lung is still rarely used, except in a few centres, is the lack of consistent protocols customised to clinical needs. Methods This article makes non-vendor-specific protocol suggestions for general use with state-of-the-art MRI scanners, based on the available literature and a consensus discussion within a panel of experts experienced in lung MRI. Results Various sequences have been successfully tested within scientific or clinical environments. MRI of the lung with appropriate combinations of these sequences comprises morphological and functional imaging aspects in a single examination. It serves in difficult clinical problems encountered in daily routine, such as assessment of the mediastinum and chest wall, and even might challenge molecular imaging techniques in the near future. Conclusion This article helps new users to implement appropriate protocols on their own MRI platforms. Main Messages • MRI of the lung can be readily performed on state-of-the-art 1.5-T MRI scanners. • Protocol suggestions based on the available literature facilitate its use for routine • MRI offers solutions for complicated thoracic masses with atelectasis and chest wall invasion. • MRI is an option for paediatrics and science when CT is contra-indicate

Magnetic resonance lung function – a breakthrough for lung imaging and functional assessment? A phantom study and clinical trial

BACKGROUND: Chronic lung diseases are a major issue in public health. A serial pulmonary assessment using imaging techniques free of ionizing radiation and which provides early information on local function impairment would therefore be a considerably important development. Magnetic resonance imaging (MRI) is a powerful tool for the static and dynamic imaging of many organs. Its application in lung imaging however, has been limited due to the low water content of the lung and the artefacts evident at air-tissue interfaces. Many attempts have been made to visualize local ventilation using the inhalation of hyperpolarized gases or gadolinium aerosol responding to MRI. None of these methods are applicable for broad clinical use as they require specific equipment. METHODS: We have shown previously that low-field MRI can be used for static imaging of the lung. Here we show that mathematical processing of data derived from serial MRI scans during the respiratory cycle produces good quality images of local ventilation without any contrast agent. A phantom study and investigations in 85 patients were performed. RESULTS: The phantom study proved our theoretical considerations. In 99 patient investigations good correlation (r = 0.8; p ≤ 0.001) was seen for pulmonary function tests and MR ventilation measurements. Small ventilation defects were visualized. CONCLUSION: With this method, ventilation defects can be diagnosed long before any imaging or pulmonary function test will indicate disease. This surprisingly simple approach could easily be incorporated in clinical routine and may be a breakthrough for lung imaging and functional assessment

Transforming growth factor beta-coated platinum coils for endovascular treatment of aneurysms:An animal study

Objective: To test the hypothesis that coating platinum coils with transforming growth factor beta (TGF beta) would improve the cellular proliferation within experimental aneurysms relative to uncoated coils. Materials and methods: Elastase-induced saccular aneurysms were created in 12 New Zealand White rabbits. These aneurysms were embolized with platinum coils, either "control" (unmodified) coils or "test" (coated with TGF beta) coils. Subjects were killed either 2 weeks (n = 3, control; n = 3, test) or 6 weeks (n = 3, control; n = 3, test) after embolization. Aneurysm tissue was embedded in plastic, sectioned, and stained with hematoxylin and eosin. The thickness of tissue covering the coils at the coil-lumen interface was measured by use of a digital microscope, and was compared between groups by use of the Student's t test (P less than or equal to 0.05). Results: Two-week implantation samples demonstrated mean thickness of tissue overlying TGF beta -coated coils of 36 +/- 15 mum and mean thickness of overlying control coils of 3 +/-5 mum, indicating significantly thicker tissue growth covering test versus control coils (P = 0.02). Six-week implantation samples demonstrated mean thickness of tissue overlying TGF beta -coated coils of 86 +/- 74 mum versus mean thickness overlying control coils of 37 +/-6 mu; this difference did not reach statistical significance (P = 0.30). Thickness of tissue covering TGF beta -coated coils did not change significantly from 2 to 6 weeks (P = 0.31). Tissue thickness over control coils increased significantly between 2 and 6 weeks (P = 0.002). Conclusion: TGF beta -coated platinum coils undergo earlier cellular coverage than standard platinum coils, but differences in coverage between coated and control coils are no longer present at later time points. These data suggest that improvements in intra-aneurysmal cellular proliferation resulting from coil modifications, although significant in the early postembolization phase, may dissipate over time

Magnetic Resonance Imaging of Pediatric Lung Parenchyma, Airways, Vasculature, Ventilation, and Perfusion State of the Art

Magnetic resonance (MR) imaging is a noninvasive imaging modality, particularly attractive for pediatric patients given its lack of ionizing radiation. Despite many advantages, the physical properties of the lung (inherent low signal-to-noise ratio, magnetic susceptibility differences at lung-air interfaces, and respiratory and cardiac motion) have posed technical challenges that have limited the use of MR imaging in the evaluation of thoracic disease in the past However, recent advances in MR imaging techniques have overcome many of these challenges. This article discusses these advances in MR imaging techniques and their potential role in the evaluation of thoracic disorders in pediatric patients

Validating excised rodent lungs for functional hyperpolarized xenon-129 MRI

Ex vivo rodent lung models are explored for physiological measurements of respiratory function with hyperpolarized (hp) 129Xe MRI. It is shown that excised lung models allow for simplification of the technical challenges involved and provide valuable physiological insights that are not feasible using in vivo MRI protocols. A custom designed breathing apparatus enables MR images of gas distribution on increasing ventilation volumes of actively inhaled hp 129Xe. Straightforward hp 129Xe MRI protocols provide residual lung volume (RV) data and permit for spatially resolved tracking of small hp 129Xe probe volumes during the inhalation cycle. Hp 129Xe MRI of lung function in the excised organ demonstrates the persistence of post mortem airway responsiveness to intravenous methacholine challenges. The presented methodology enables physiology of lung function in health and disease without additional regulatory approval requirements and reduces the technical and logistical challenges with hp gas MRI experiments. The post mortem lung functional data can augment histological measurements and should be of interest for drug development studies