Imaging cholesteatoma

Classification:

Congenital (2%)


Acquired (98%)


--Pars flaccida (82%)


--Pars tensa (18%)


---- Posterosuperior (78%)


---- Anteroinferior (22%)

Congenital cholesteatoma:

= Epidermoid Epithelial rest cells

Can be seen in middle ear, mastoid, squamous temporal, petrous apex, CP angle

Common in anterior middle ear cavity near ET tube and stepes

Acquired cholesteatoma:

= Prusaac's cholesteaoma, attic cholesteatoma

Sequele to middle ear infection

MRI:




Useful in evaluating post operative/ recurrent cholesteatomas; differentiating




Delayed post-Gd T1 SE is useful




Cholesterol granuloma: increased signal on T1, no change on delayed Gd T1, low signal on DWI


with b factor of 800 sec/mm².




Granulation tissue without recurrence: low signal on T1, high signal on T2, enhance on delayed


Gd T1, low signal on DWI b factor of 800 sec/mm²




Recurrent cholesteatoma: low signal on T1, no change on delayed Gd T1, and high signal on DWI


with b factor of 800 sec/mm²






Cholesteatoma shows increased signal on DWI, whereas granulation tissue, fibrous tissue, cholesterol granuloma, or serous fluid show low


signal intensity.






Reference:




http://radiology.rsnajnls.org/cgi/content/full/238/2/604




Diffusion-weighted MR Imaging Sequence in the Detection of Postoperative Recurrent Cholesteatoma


Radiology 2005;238:604-610

Imaging Neck

Approach to ultrasound of the neck

Approach to ultrasound of the neck

Start with submental region:
Structures to be identified: anterior belly of digastric, myelohyoid, geniohyoid, genioglossue from superfical to deep. Sublingual glands are more deep and lateral.
Lesions superficial to digastric will be submental space
Lesions superficial to myelohypoid will be submandibular space
Lesions deep to myelohypid will be sublingual space
There might be defect in the myelohyoid - from which sublingual lesions may plunge into submandibular space

Midline sagittal scan of the submental space:
Probe netween mandible and hyoid will show myelohyoid and anterior belly of digastric
Evaluate submental region

Then move laterally to submandibular space:
Trace the myelohyoid muscle laterally to its free border to come to submandibular gland and space
Myelohyoid is superficial and hyoglossus is deep. Between them is submandibular duct and lingual vein. The lingual artery lies deep to hyoglossus.
Evaluate submandibular gland and fat anterior to it for lymphnodes

Then image parotid glands:
Identify retrmandibular vein and extrenal carotid artery. Retromandibular vein is landmark for facial nerve.
parotid duct is seen as then echogenic line, pierces buccinator
Messeter is a landmark anteriorly and mandible posteriorly
Common to find accessory partotid along the cheek

Then scan cervical chain:
Identify IJV in cross section, follow it from superior to inferior to look for level 2, 3 and 4 nodes.
Look for thrombosis of IJV

Then scan posterior triangle:
Look for nodes in the superficial fat between trapezius and sternomastoid, superficial to scalene and splenius muscles

Then scan supraclavicular region:
Along the superior border of the clavicle
Identify sternomastoid, trepezius and omohyoid
Identify scalene muscles and brachail plexus

Then scan laryngeal region:
Identify thyroid lamina, strap muscles

Then do not scan thyroid and carotid:
Unless asked, do not ultrasound thyroid and carotids!

(images will be uploaded shortly...)

Differentials in petrous apex

Pseudolesions:
Diploic fat marrow
Simple petrous effusion
Congenital:
Cephalocele
Benign:
Cholesterol granuloma
Mucocele
Cholesteatoma
Infection:
Petrous apicitis
Vascular:
Carotid artery aneurysm
Malignant:
Rhabdomyosarcoma
Metastasis
Lymphoma
Bone and cartilage tumors:
Osteosarcoma
Chondrosarcoma
Others:
Histiocytosis X
Paget's fibrous dysplasia

Reference:
Connor SEJ et al. Imaging of the petrous apex: a pictorial review. British Journal of Radiology (2008) 81, 427-435

Petrous apex

IAM divides petrous apex into
1. anterior portions - contains marrow and air cells
2. posterior otic capsule

Aereated in 1/3rd by peritubal, posteromedial and subarcuate tracts which extend superior and inferior to cochlea to communicate with middle ear

Anterior compartment:
Contains horizontal portion of petrous carotid canal and foramen lacerum

Relations:
VI N medial and V N superomedial

Reference:
Connor SEJ et al. Imaging of the petrous apex: a pictorial review. British Journal of Radiology (2008) 81, 427-435