IMAGING OF THE TEMPORAL BONE
-MAJOR MODALITIES USED INCLUDE CT, MRI, AND ANGIOGRAPHY
-80% OF DISEASES REQUIRE ONLY ONE IMAGING STUDY
PLAIN FILMS -CAN USE TO CHECK PNEUMATIZATION OF THE MASTOID AND PETROUS APEX
-CAN USE TO CHECK INTEGRITY OF COCHLEAR IMPLANT LEADS
CT SCAN -DELINEATES INTRATEMPORAL PATHOLOGY WELL ESPECIALLY WITH CHL OR MIXED HL
-DYNAMIC SCANNING CAN HELP DIFFERENTIATE VASCULAR STRUCTURES
MRI -DELINEATES LESIONS EXTENDING OUT OF THE TEMPORAL BONE OR ORIGINATING AT THE CP ANGLE OR PETROUS APEX
-DELINEATES CENTRAL AUDITORY AND VESTIBULAR PATHWAYS
-T1 AND T2 IMAGES CAN HELP DIFFERENTIATE DIFFERENT DISEASE PROCESSES THAT AFFECT THE SAME AREA
ANGIOGRAPHY -IMPORTANT IN PRE-OP EVALUATION OF VASCULAR TUMORS FOR LOCATION OF FEEDING VESSELS AND POSSIBLE EMBOLIZATION
ANATOMIC VARIATIONS ARE IMPORTANT TO LOOK FOR ON ALL SCANS
-PNEUMATIZATION OF THE MASTOID OR PETROUS APEX
-LOCATION OF THE TEGMEN
-LOCATION OF THE JUGULAR BULB
-DEHISCENT FACIAL CANAL
PATHOLOGY OF THE MASTOID – USE CT SCAN
-ACUTE MASTOIDITIS -FLUID FILLED AIR CELLS WITH DESTRUCTION OF BONY TRABECULAE DESTRUCTION, MAY HAVE ASSOCIATED ABSCESSES
-CHRONIC MASTOIDITIS -THICKENED TRABECULAE AND NONHOMOGENEOUS CLOUDING OF THE AIR CELLS
PATHOLOGY OF EXTERNAL AUDITORY CANAL – USE CT SCAN
-CONGENITAL -CAN SHOW COMPLETE AGENESIS, A THIN OBSTRUCTING PLATE, OR STENOSIS OF EAC; MAY SHOW MALFORMED AND FUSED OSSICLES; MICROTIA AND INAPPROPRIATE ALIGNMENT OF EXTERNAL EAR TO EAC AND ME
-TRAUMA -POST/SUPERIOR WALL FX LINE ASS. WITH LONGITUDINAL FX
-ANT WALL FX ASS. WITH MANDIBULAR TRAUMA
-COMMINUTED FX SEEN WITH PROJECTILES
-MALIGNANT EXT. OTITIS -BONY EROSION OF THE EAC USUALLY ALONG THE FLOOR WITH ASSOCIATED SOFT TISSUE SWELLING
-EXT. CANAL CHOLESTEATOMA -OPEN EAC BUT LOCALIZED BONY DESTRUCTION USUALLY NEXT TO TYMPANIC MEMBRANE
-KERATOSIS OBTURANS/OBLITERANS -STENOTIC EAC WITH DEBRIS AND BONY DESTRUCTION MEDIAL TO STENOSIS
-CARCINOMA -SOFT TISSUE SWELLING WITH BONY DESTRUCTION OF VARIABLE EXTENT
PATHOLOGY OF THE MIDDLE EAR AND OSSICULAR CHAIN – USE CT SCAN
-CONGENITAL -VARY FROM MINIMAL HYPOPLASIA TO AGENESIS OF ME CLEFT; OSSICLE ARE USUALLY PRESENT BUT ARE USUALLY FUSED IF NOT SEVERALLY ATRETIC
-TRAUMA -USUALLY AFFECTED BY THE LONGITUDINAL FX WITH OSSICULAR DISCONTINUITY AND TEGMEN FX
-ACUTE OM -HOMOGENOUS FLUID FILLED ME CLEFT AND MASTOID BUT MAY PROGRESS TO TRABECULAR LOSS AND/OR ABSCESS FORMATION
-CHRONIC OM -ME SPACE CLOUDED DUE TO THICKENED ME MUCOSA OR GRANULATION TISSUE; OSSICULAR EROSION OR TYMPANOSCLEROTIC PLAGUES MAY BE PRESENT
-CHOLESTEATOMA-CONGENITAL- WELL DEFINED ME SOFT TISSUE MASS
-ACQUIRED – SOFT TISSUE MASS THAT MAY BE ASS. WITH SCUTAL EROSION AND LATERAL TO OSSICLES IF ATTIC ORIGIN; SOFT TISSUE MASS MEDIAL TO OSSICLES IF PARS TENSA ORIGIN; MAY HAVE OSSICULAR EROSION, TEGMEN DEFECT, OR LAT. SCC FISTULA, ISODENSE TO CSF, NONENHANCING
-TUMORS -OSTEOMAS, GLOMUS, MALIGNANCY
-OTOSCLEROSIS -USEFUL FOR PERSISTENT POST-OP COMPLAINTS TO CHECK PROSTHESIS PLACEMENT
PATHOLOGY OF THE INNER EAR – USE CT SCAN
-CONGENITAL -MONDINI – LOSS OF COCHLEAR TURNS
-MICHEL – COMPLETE AGENESIS
-TRAUMA -TRANSVERSE SKULL FX WITH FX LINE THROUGH IAC AND LABYRINTH
-OBLITERATIVE LABYRINTHITIS
PATHOLOGY OF PETROUS APEX – COMBINATION OF CT AND MRI MAY BE NEEDED
-GLOMUS JUGULARE- CT SHOWS ENLARGED JUGULAR BULB WITH SOFT TISSUE MASS SHOWING WASHOUT; MRI SHOWS MEDIUM INTENSITY LESION ON BOTH T1 AND T2 WITH POSSIBLE SIGNAL VOID
-CONGENITAL CHOLESTEATOMA VS CHOLESTEROL GRANULOMAS
-CT SCAN SHOWS BOTH TO BE CYSTIC WITH NO OR FAINT PERIPHERAL ENHANCEMENT
-MRI -CONG. CHOL. – HIGH INTENSITY ON T2 AND LOW INTENSITY T1
-CHOL. GRAN. – HIGH INTENSITY ON BOTH T1 AND T2 IMAGES
-MENINGIOMA -CT SHOWS HYPEROSTOSIS OF INVOLVED BONE
-MRI SHOWS MENINGEAL EXTENSION ON CONTRASTED T1 IMAGES
-PAGET’S DZ -CT SCAN SHOWS WASHED OUT APPEARANCE OF PETROUS APEX
PATHOLOGY OF FACIAL NERVE – USE CT TO EVALUATE CANAL AND MRI TO EVALUATE NERVE
-CONGENITAL -CT TO LOOK FOR ABNL COURSE OF NERVE
-TRAUMA -CT TO LOOK FOR DISRUPTION OF CANAL
-BELL’S PALSY -MRI SHOWS INCREASED INTENSITY OF NERVE ON CONTRASTED T1 IMAGES
-TUMOR -MRI PRECONTRAST WILL SHOW LOW INTENSITY T1 AND INTERMEDIATE INTENSITY T2 AND POSTCONTRAST T1 WILL BE HIGH INTENSITY
PATHOLOGY OF CP ANGLE – USE MRI
-ACOUSTIC -T1 ISODENSE TO GRAY MATTER AND BRIGHTER THAN CSF; T2 ISODENSE TO CSF AND BRIGHTER THAN GRAY MATTER; ENHANCES ON T1 CONTRASTED STUDY
-MENINGIOMA