Larynx and Hypopharynx

Imaging findings in the larynx have, in the past, helped confirm the limited extent of early larynx cancer allowing patients to decide between radiation and surgery for primary management. Imaging for advanced larynx and hypopharynx lesions helps confirm the need for surgery and single out the patients appropriate for organ preservation. Post-biopsy changes distort the narrow tissue planes within the larynx and patients should not be scanned prior to any endoscopic manipulation or biopsy. MRI provides exquisite soft tissue resolution40 even without intravenous contrast. That benefit is not necessary in early larynx cancer but has a bearing on prognosis for local recurrence for more locally advanced lesions.41 A negative CT is adequate for

Figure 3-15. Midline sagittal MR tongue with undifferentiated carcinoma. (1) Intact bone cortex of buccal plate at symphysis. (2) Tumor originating at oral tongue. (3) Intact geniohyoid muscle. (4) Tumor extension toward base of tongue. (5) Preserved pre-epiglottic space.

Figure 3-16. Nasopharynx cancer. Clockwise from upper left: semi-coronal T1-weighted, contrast T1-weighted, and fat-suppressed T2-weighted MR images and para-sagittal contrast T1-weighted MR images. (1) Mucosal mass. (2) Levator veli palatini muscles (invaded on the left). (3) Intact skull base (clivus) with normal marrow signal. (4) Early invasion of parapharyngeal space. (5) Benign reactive enhancement at foramen ovale, intracranial extension.

Figure 3-16. Nasopharynx cancer. Clockwise from upper left: semi-coronal T1-weighted, contrast T1-weighted, and fat-suppressed T2-weighted MR images and para-sagittal contrast T1-weighted MR images. (1) Mucosal mass. (2) Levator veli palatini muscles (invaded on the left). (3) Intact skull base (clivus) with normal marrow signal. (4) Early invasion of parapharyngeal space. (5) Benign reactive enhancement at foramen ovale, intracranial extension.

clearance of the paraglottic space and preepiglottic space42 (Figure 3-19). MRI better evaluates the sub-glottic extent and is more sensitive to early cartilage involvement.43 Neither of these features is common with early glottic cancer. Either modality can confirm a locally advanced lesion being restricted to the supraglottis or hemilarynx permitting a primary surgical approach.44,45 Advanced cancers of the larynx cause pain and difficulty managing secretions—limiting the success of MRI for staging. Tracheostomy alleviates some of these problems. Rapid CT scanners coupled with "slip ring" (helical/spiral) technology help produce images with less patient motion artifact.46 Reformatted images can be produced in the sagittal and coronal planes from the original axial scan plane (Figure 3-20). Either modality provides adequate surgical planning or baseline information prior to treatment. MRI is more sensitive but less specific than CT for cartilage invasion.47 Imaging of primary tumors of the hypopharynx is per-

Figure 3-17. Squamous cancer tonsillar pillar. (1) Large mass arising in right palatine tonsil. (2) Right medial pterygoid invaded. (3) Right base of tongue extension.
Figure 3-18. CT images of soft palate squamous cancer. Axial (L) and semi-coronal (R) tissue windows. (1) Soft palate component. (2) Tonsillar pillar extension. (3) Medial pterygoid muscle (normal).

formed with larynx style protocols. Local extension to the laryngeal framework is the most important component of extra-pharyngeal extension. Imaging detects cartilage invasion that can be clinically occult.48 CT can detect inferior extension of pyri-form sinus tumor (Figure 3-21) that cannot be assessed clinically.49 Surveillance follow-up imaging should take into account the risk for patient motion with MRI and the ability of the patient to tolerate intravenous contrast for CT.

One method to reduce the need for re-biopsy and avoid the difficulties of follow-up cross-sectional imaging is PET imaging.13,26 Non-surgical or organ preservation patients treated by chemo/radiotherapy frequently have persistent morphologic abnormalities on follow-up clinical evaluation and imaging despite maximal therapy. Often this represents sterilized tumor and fibrosis. Pain or dysfunction influence the decision to re-biopsy the primary site. In an effort to avoid the post-biopsy injury, a baseline

Figure 3-19. CT images of left transglottic squamous cancer. Clockwise from upper left panel: axial images through epiglottic, false cord and true cord levels of larynx and coronal reformatted image of same. (1) Supraglottic lesion. (2) Para-glottic component at false cord level. (3) Paraglottic extension to true cord level.

Figure 3-19. CT images of left transglottic squamous cancer. Clockwise from upper left panel: axial images through epiglottic, false cord and true cord levels of larynx and coronal reformatted image of same. (1) Supraglottic lesion. (2) Para-glottic component at false cord level. (3) Paraglottic extension to true cord level.

FDG-PET scan should be obtained and repeated after treatment.50 If the degree of metabolic activity has improved, biopsy could be deferred unless cross-sectional imaging shows a distinct progression and resection deferred unless the correlation of modalities indicates severe tissue necrosis. Another secondary benefit of the FDG-PET scan would be surveillance for second primaries. Nuclear scans with thallium-201 on more conventional equipment with single photon emission computed tomography (SPECT) capacity has been shown to be competitive with CT in the post-treatment larynx population.51 This method had an accuracy of 90 percent and does not require investment in PET technology.

Follow-up imaging of the reconstructed and irradiated laryngopharyngectomy is very important given the difficulty of examining the irradiated/ operated neck. Familiarity with the type of resections, flap reconstructions and patterns of recurrence is essential for accurate interpretation.52,53 Careful attention should be directed to the anastomotic level and peristomal region.

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