Radiological Anatomy - PNS

Dr.

Asst. Prof

Medical College

Ventral to Brain

Posterior to Facial Skeleton

Narrow Ext. Nose

Emil Zuckerkandl

Endoscopes & Imaging

WHERE ARE WE NOW…?

Introduction

Road map for endoscopic surgeon Anatomical variations Medico legal aspects

Changing Trends…

The Gold Standard- CT Scan

CT Scan MRI

Why Coronals…?

Plane almost identical to that approached by endoscopies

Best displays OMU UP & Bulla lie on a vertical plane

Axial- Complementary Pterygopalatine fossa, Fossa of Rossenmuller &

optic nerve better seen Thin slice helical scanning with reformatting

Patients who cannot tolerate hyperextension

Patients with extensive dental restorations

At optic nerve & at the narrowest AP diameter of frontal recess

Technology Advances…

Conventional CT replaced by helical or spiral CT

Shorter scan times Less motion artifact Minimisation of volume averaging artifact Permits real-time multiplanar display in OR

Newer MDCT scanners…

Allow acquisition of 4 to 32 (64) slices with each scanner rotation

Dramatically reduces motion artifacts With 0.5mm to 0.75mm beam collimation

permits very high resolution multiplanar reformatted images

Basic concepts…

Coronal 3mm cuts Bony & soft tissue windows Axial cuts Contrast enhanced CT Sagittal reconstruction

Timing of CT

A/C sinusitis adequately treated C/C inflammatory diseases- maximised medical therapy

Role of CT

to define PNS anatomy

to identify regional disease in medical non-responders

Screening CT ??

Thicker (5-10mm) axial cross section Poor diagnostic yield & eventual need for pre-

op. coronal cuts ??cost- effective

CT Patient Positioning

Patient preparation

A course of antibiotics, decongestants Sympathomimetic nasal spray 15mts

before CT To blow nose before CT

At Nasion

Frontal sinus

1. Present / absent

2. No. / size

3. Intersinus septum

• pneumatization

4. Scalloping +/ -

5. Frontal cell – I -IV

6. Aggar Nasi

7. Septal deviation

At Aggar Nasi

1. Nasl septal deviation

2. Aggar Nasi

– side , No. & size

3. Frontal cell Type- I-IV

4. Nasolacrimal duct & its relationship to aggar

At level of OMC

1. Nasl septal deviation

2. Uncinate process +/-

- Normal / Atelectatic

- bent Medially / laterally

- Superior attachment

3. Frontal recess

- Infundibular pattern / middle meatus

4. Skull base height- Type I,II,III

5. Relation to Ant.Ethmoidal A.

6. Bulla +/-

- Hypoplastic / large / lateral sinus

7. Middle turbinate- Concha bullosa- Paradoxical MTC

At level of

Posterior ethmoids

1. Nasal septum

-Deviations/spurs

2. Lamina papyracea dehiscence

3. Accessory ostia

4. Presence of superior/supreme turbinate

5. Onodi cells

At level of

Sphenoid sinus

1. Onodi cells

2. Optic nerve / Internal Carotid artery prominence/dehiscence

3. Vidian nerve / Maxillary branch of trigeminal nerve dehiscence

4. Intersinus septa

-No. / attachments to ICA / Optic nerve

5. Anterior clinoid process pneumatization

Optic foramenSOF

BASAL LAMELLA

Pterygoid plates

ppfPt max fissure

Fossa of Rosenmuller

Frontal Sinus

Extensive Pneumatisation

Frontal Recess

Uncinate Process

Terminal Recess

Frontal Cell

I

IVIII

II

Kero’s Classification

I IIIII

Agger Nasi

Pneumatisation of crista galli

Pneumatisation of Uncinate Process

Ostiomeatal Complex ( OMC)

B/L CB, Lateralised UP, Narrow Infundibulum

Elongated UP

Uncinate Process

Haller Cell

Ethmoid Infundibulum

Ethmoid Infundibulum

Large bulla & concha bullosa narrowing infundibulum

Infundibulum Variants

Middle Turbinate

Middle Turbinate Part 1

Middle Turbinate Part 2

Middle Turbinate Part 3

Middle turbinate variants

paradoxical interlamellar

Cocha Bullosa

Bulla Ethmoidalis Variants

Absent bulla Bulla with multiple cells

Sinus Lateralis

Sinus Lateralis = Suprabullar recess and retrobullar recess

Maxillary Sinus

Height of Skullbase at Post.Ethmoid

Sphenoethmoidal Cell

Sphenoid Sinus

Sphenoid variations

Pneumatisation

Anterior Clinoid Process Pneumatisn

Dehiscent Optic Nerve & ICA

Be careful…

Allergic Fungal Rhinosinusitis

MRI: Central hypointensity on T1, central signal void on T2; increased peripheral enhancement

Thank You

Haller cells

multiple Large & flat

UP blocking EI