Only heart. A cardiac perfusion scan measures the amount of blood supplied to your heart muscle. Radiotracers are injected intravenously and travel through blood to heart muscle. Indications for this study include chest pain, previous heart attack, heart surgery and coronary artery disease. Ultrasound, MRI, ct with contrast, arteriography, and brain scans address issues in head and neck.
No. Usually the camera only images your chest and abdomen. You would need a different scan to image arteries in the neck and head, a common one would be ultrasonography for carotid intima media thickness.
No. No it just looks at heart muscles uptake of a radioactive substance, which is correlated with blood flow to the heart.