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Choana

The choana (plural: choanae) are paired anatomical openings located at the posterior aspect of the nasal cavity, forming the communication between the nasal passages and the nasopharynx. They play a critical role in respiration and the passage of air from the nasal cavity to the lower airways. Radiological imaging of the choana, particularly with MRI and CT, is essential for evaluating normal anatomy, congenital anomalies (e.g., choanal atresia), and various pathologies including tumors, inflammatory diseases, and trauma.

MRI Appearance of the Choana

  • T2-Weighted Images:

    • Air within the choana appears as a signal void (black).

    • Surrounding soft tissues (mucosa, adenoids, nasopharynx) are typically hyperintense (bright) due to high water content.

    • Mucosal thickening, secretions, or masses may appear with intermediate to high signal intensity, depending on water content and pathology.

    • Fluid collections or inflammatory changes (e.g., sinusitis extending to the choana) are bright.

  • T1-Weighted Images:

    • Air within the choana appears as a signal void (black).

    • Normal mucosal lining is isointense to mildly hyperintense compared to adjacent muscle.

    • Fat (such as in the surrounding pterygopalatine fossa) appears hyperintense (bright).

    • Pathologic soft tissue (masses, polyps) generally appears iso- to hypointense compared to muscle.

    • Enhancement patterns after gadolinium administration can help distinguish tumors or inflammatory lesions.

  • STIR (Short Tau Inversion Recovery):

    • Highly sensitive for detecting edema and inflammation.

    • Fluid and edematous tissues appear hyperintense (bright).

    • Useful for highlighting subtle soft tissue abnormalities, especially in the setting of infection or neoplastic infiltration.

    • Air remains signal void (black).

CT Appearance of the Choana

  • Bone Window:

    • Clearly demonstrates the bony boundaries of the choana (vomer, medial pterygoid plate, palatine bone).

    • Useful for detecting congenital anomalies (choanal atresia, bony stenosis), fractures, or erosive changes due to neoplasm or infection.

    • Air within the choana appears as black (very low attenuation).

    • Mucosal thickening, polyps, or soft tissue masses can be seen as soft tissue density.

MRI images

Choana mri axial image -img-00000-00000