An Angiogram is essentially an x-ray or other image of an artery. It’s performed by obtaining an image while dye, injected into the blood, is flowing through it. This can be done invasively, which carries certain risks but obtains better information, or non-invasively, with no risks but an inferior picture.
An Arteriogram is the type of angiogram in which dye is injected directly into an artery. For the coronary arteries, it’s the only type of angiogram possible (also called “Cardiac Catheterization,” or “Cath” for short). An arteriogram is the clearest test to see the circulation in an area (brain, intestinal arteries), but runs an unlikely risk of causing stroke or tissue death there during the procedure.
A safer non-invasive image of arteries is by MRI- or CT-Angiogram. Here dye is injected into a vein. Then an MRI or CT scan takes images timed for when blood is expected to carry the dye to the organ. But for some conditions, a plain angiogram (i.e. arteriogram) is necessary.
Terminology can be confusing, especially for the lung. To rule out a Pulmonary Embolus, all that’s needed is the safer CT-Angiogram, since dye in a vein goes right into the pulmonary artery (see Diagrams: The Heart, and The Circulatory System). However, for unusual cases or conditions it’s necessary to enter the pulmonary artery, the catheter will be threaded into it.
The various dyes used to inject carry some risk of kidney damage, but almost only in people who have poor kidney function to begin with. Radiologists know how to deal with this if possible.