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.
What is helium used for? Helium is put into balloons to help float Helium is easily detected in minute quantites, and has a very small molecule. So helium is also used for checking vacum and other â¦enclosures for leaks. Helium is used in some noble gas (neon) signs, possibly mixed with other gases. Liquid helium is used as a coolant, like for MRI magnets and such. Liquid helium acts as a study in physics for superfluids (see link below).