A pulmonary nodule is a discrete opacity in the lung which may be caused by: 1  Neoplasm: benign or malignant. 2  Granuloma: tuberculosis. 3  Infection: roundish pneumonia. 4  Vascular: infarct, varix, granulomatosis with polyangiitis, rheumatoid arthritis.
1 Helium is also commonly used to pressurize and purge systems of unwanted gases. 2  It is also used in controlled atmospheres when the levels of different gases have to be kept constant. 3  It is used as a protective gas when growing silicon and germanium crystals and when producing titanium and zirconium.
Most people know that helium is used as a lifting gas in blimps and party balloons, but they can't name another way in which it is used. The number one use of helium is as a cooling gas for magnetic resonance imaging (MRI) machines used in medical facilities. Other important uses of helium include: a protective gas for welding, an inert gas for controlled atmosphere manufacturing, a fugitive gas used for leak detection, and a low-viscosity gas for pressurized breathing mixtures.