Investigation of Blood Vessels of the Brain :
The test known as Angiography is the most important test. MR Angiography makes the use of the MRI magnetfor the examination of the blood vessels In this test no catheter is required to be introduced in the blood vessels. Therefore, it is called a Non Invasive test. For coronary angiography, a catheter has to be introduced in a blood vessel and therefore there is a slight risk involved, which is not the case in a MR Angiography. This test can give an accuracy of only 90 to 95% and therefore, can be used only as a screening test. The gold standard tests are the conventional 4 vessel angiography or Digital Substraction Angiography (DSA). An aneurysm is immediately detected on angiography. In 15% cases more than one aneurysm can be present and so it is imperative that the angiography is done on all the four blood vessels of the brain, so that if surgery becomes necessary it can be planned keeping all the aneurysms in mind.
The angiography can also detect another vascular condition, i:e the entanglement of blood vessels known as arteriovenous malformation (AN. Malformation). These patients have a history of severe headache; with an occasional seizure, and some of them may..already be suffering from the paralysis of a limb.
In some cases of sub-arachnoid hemorrhage DSA angiography may show normal results. Out of these cases a few may have a very small aneurysm or a cryptic AN. malformation or a vasospasm, which may not be detected on angiography. Therefore in such cases angiography is repeated after 3 months. Only then it can be confirmed that these are not the causes of hemorrhage. This kind of hemorrhage is termed as Idiopathic Sub-arachnoid Hemorrhage.