Congenital agenesis/aplasia of the internal carotid arteries: MRA and SPECT findings.

Single photon emission CT (SPECT) and MRI and MR angiography studies were performed in a patient with right internal carotid artery (ICA) agenesis, left ICA aplasia, and multiple associated vascular abnormalities identified with digital subtraction angiography. Magnetic resonance angiography provided an excellent depiction of the extra and intracranial vascular abnormalities. No evidence of brain lesions or perfusion defects was demonstrated with MRI and SPECT, despite the markedly altered vascular anatomy.