dr ahmed esawy imaging of adeniod enlargment

Dr. Ahmed Esawy

MBBS M.Sc MD

Anatomy • The lymphoid tissue of the nasopharynx and

oropharynx is composed of the adenoids, the tubal

tonsils, the lateral bands, the palatine tonsils, and

the lingual tonsils.

• There are also lymphoid collections in the posterior

pharyngeal wall and in the laryngeal ventricles.

• These structures form a ring of tissue named

Waldeyer’s ring after the German anatomist who

described them.

The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior -most of the tonsils . It is a mass of lymphatic tissue situated posterior to the nasal cavity, in the roof of the nasopharynx it forms a soft mound in the roof and posterior wall of the nasopharynx , just above and behind the uvula .

Lateral neck radiograph

• The main imaging study to evaluate the adenoid is a lateral neck radiograph, as in the images below.

ENLARGED ADENIOD

AVERAGE SIZE ADENIOD

Requirement of Lateral neck radiograph in adenoid

• 1-true lateral view not oblique • 2-adjust X ray factors to differentiate between

soft tissue density of adenoid and bone density of mandible . high voltage lead to false –ve ,low voltage give false +ve

• 3-extend neck to pull mandible anteriorly away from adenoid bed prevent overlap on adeniod shadow

• 4-open mouth to clear identify air column • 5-no movement of patient to prevent haziness

,blurring

• The lateral neck x-ray is the main imaging study. The size of the adenoids is less of a consideration than the degree to which they encroach on the nasopharyngeal airway (adeniod grades) :

• if no adenoidal tissue after 6 months, suspect immune deficiency

• if enlarged adenoids well after childhood, suspect lymphatic malignancy

Method of assessing adenoid enlargement on lateral neck radiography. In this method the adenoidal measurement (A) represents the distance from the point of maximal convexity of the adenoid shadow to a line along the anterior margin of the basiocciput. The nasopharyngeal measurement (N) is the distance between the posterior border of the hard palate and the antero-inferior edge of the sphenobasioccipital synchondrosis.

Minimal (AN ratio < 0.50) Mild (0.50 ≤ AN ratio < 0.62) Moderate (0.63 ≤ AN ratio < 0.75) Severe (0.76 ≤ AN ratio < 0.88)

CASE 1 ENLARGED ADENIOD

CASE 2 ENLARGED ADENIOD

CASE 3 ENLARGED ADENIOD

CASE 4 ENLARGED ADENIOD

Three-dimensional (3D) measurements of the nasopharyngeal airway on the adenoid plane in this study. A, The nasopharyngeal airway on the midsagittal view. The most enlarged adenoid was tangential; the nasopharyngeal airway’s narrowest part is identified as Ad-En; and the nasopharyngeal airway is shown as the yellow area. B, The cross-sectional image of the nasopharyngeal airway in the frontal plane, in which the most enlarged adenoid was included (adenoid plane).

Minimal (AN ratio < 0.50) Mild (0.50 ≤ AN ratio < 0.62) Moderate (0.63 ≤ AN ratio < 0.75) Severe (0.76 ≤ AN ratio < 0.88) group

No enlarged adenoid and palatine tonsils

Enlarged adenoid and palatine tonsils

Axial T1-weighted contrast-enhanced MR image in a 56-year-old man shows smooth, thin, hyperenhancing tissue along the posterior nasopharyngeal wall (white long arrows). The right pharyngeal recess is collapsed (white short arrows), whereas the left recess is patent (black arrows), but both recesses show symmetric wall thickness.

Axial T1-weighted, A, nonenhanced and, B, contrast-enhanced MR images of the nasopharyngeal roof in a 34-year-old man show vertically aligned dark and bright stripes (arrows) within a grossly enlarged nasopharyngeal adenoid

C, Axial T1-weighted contrast-enhanced MR image in a 29-year-old man shows an enlarged adenoid composed of a central wedge of predominantly dark tissue (black arrow), flanked on each side by a thin stripe of bright tissue (white arrows).

D, Axial T1-weighted contrast-enhanced MR image in a 51-year-old woman shows small tags of tissue protruding from the nasopharyngeal roof (arrows),which probably represent tissue remnants after adenoid involution.

Axial T1-weighted, A, nonenhanced and, B, contrast-enhanced MR images in a 30-year-old man show a uniform hypoenhancing band of tissue in the posterior wall (arrows).

A, Axial T1-weighted contrast-enhanced MR image, and, B, axial T2-weighted fat-suppressed MR image in 45-year-old woman show numerous mucus retention cysts, which are hypointense and markedly hyperintense, respectively. A few cysts are indicated (arrows).