Which window is used to assess the retromandibular and proximal intracranial ICA?

• A. Transtemporal
• B. Transforamenal
• C. Submandibular
• D. Transorbital

Answer: (C)

In transcranial Doppler imaging, different acoustic windows let you access different parts of the intracranial circulation. The retromandibular portion and the proximal intracranial internal carotid artery lie close to the skull base behind the mandible, so placing the transducer in the submandibular region and angling the beam upward toward the skull base allows insonation of these segments. This window complements the transtemporal window (which targets vessels like the MCA, ACA, and PCA through the temporal bone) and the transorbital window (used for orbital/ophthalmic portions). The submandibular window is specifically best for the retromandibular and proximal intracranial ICA.