Imaging of the Paranasal Sinuses

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1 14. Sommerschule Imaging of the Paranasal Sinuses Bettlach Christoph Schlegel

2 Conventional Radiology NNH-Status: okzipito-frontal: frontal sinus, anterior ethmoid okzipito-nasal : maxillary and frontal sinus axial: sphenoid and ethmoidal sinus Radiation exposure: 2 mgy per exposure (dose for cataract 2 Gy)

3 Conventional Radiology inadequate sensivity and specifity superseded by CT

4 Single detector row CT Multi detector row CT Multislice Spiral CT Zeilen Zeilen Zeilen Zeilen Zeilen x 64 Zeilen x 128 Zeilen 2009

5 Paranasal Sinus CT Protocol high resolution axial scan from alveolar process to frontal sinus collimation 0.6mm overlapping slice reconstruction 0.6/0.4mm, mas <200 reconstruction: axial, coronal, sagittal iv contrast*: tumor, inflammation, vascular lesion not required for preop assessment of anatomy

6 Review: Radiation Dose radiation dose paranasal sinus CT conventional x-ray paranasal sinus average diagnostic dose /per capita transatlantic flight (round trip) 0.5-1mGy 0.2 mgy/expos. CH: 1mGy, GB 0.33mGy 0.1mGy cataract of eye lens: > 2 Gy

7 CT preoperative anatomy, residual mucosal disease pattern of bone destruction, skull base defects navigation- CT, CT guided biopsies MRI soft tissue differentiation: retention, tumor, cellularity, vascularity meningeal, neural, vascular involvement

8 Complementary Role CT MR

9 Meningo-Encephalocele

11 Clival Chordoma

12 Angiography diagnostic use for selected cases superselective embolisation: intractable epistaxis; M. Osler embolisation of tumors

13 Juvenile Nasopharyngeal Angiofibroma

14 Orbital Complication: Subperiostal Abscess

15 Endocranial Complikation: Epidural and Soft Tissue Abscess in Frontal Sinusitis

16 Chronic Rhinosinusitis (without Nasal Polyps) N.B.: after medical treatment

17 Chronic Rhinosinusitis (with Nasal Polyps) N.B.: after medical treatment

18 Red Flags Consider other diagnosis: unilateral symptoms bleeding, crusting cacosmia orbital symptoms( oedema, displaced globe, double vision) severe frontal headache, frontal swelling signs of meningitis neurological signs urgent investigation and intervention

19 Granulomatose mit Polyangiitis (M. Wegener)

20 Aspergilloma (fungus ball)

21 Odontogenic Sinusitis

22 Inverted Papilloma

23 Inverted Papilloma

24 Mucocele of Maxillary Sinus

25 Mucocele of Sphenoid Sinus Dehiscent Internal Carotid Artery

26 Complicated Nose Fracture

27 Zygomatic Fracture

28 CSF-Leak High resolution CT MRI (T2) β2-transferrin or β-trace In selected cases: Intrathecal fluorescein injection

29 CSF-Leak

30 Dacryo CT Scan

31 Dacryo CT Scan

32 FESS: Preoperative Evaluation (CT Checklist) uncinate process ethmoidal roof, skull base ethmoidal arteries orbit, optic nerve internal carotid artery anatomical variations of ethmoidal cells

33 Uncinate Process A B1 B2 Simmen D, Jones N: Manual of Endoscopic Sinus Surgery. Thieme 2014

34 Preoperative Checklist: Uncinate Process Typ A (~ 75%): Insertion at Lamina papyracea «Recessus terminalis» Frontal sinus drainage pathway directly in middle meatus

35 Preoperative Checklist: Uncinate Process Typ B1: Insertion at skull base Frontal sinus drainage pathway in ethmoidal infundibulum

36 Preoperative Checklist: Uncinate Process Typ B2: Insertion at middle turbinate Frontal sinus drainage pathway in ethmoidal infundibulum

37 Frontal Recess Wormald PJ: The agger nasi cell: the key to understand the anatomy of the frontal recess Otolaryngol Head Neck Surg 2003; 129:

38 Anatomy of the Frontal Recess "frontal drainage pathway" "fronto-ethmoidal cell" "agger nasi cell"

39 Frontal Recess: Sagittal Reconstruction Suprabullar cells Frontal bullar cells Interfrontal sinus septal cell Fronto-ethmoidal cells: Agger nasi cell K1 to K4 cells

41 anterior (medial) posterior

43 Preoperative Checklist: Ethmoid Roof Cribriform Plate

44 Preoperative Checklist: Anterior Ethmoidal Artery

45 Preoperative Checklist: Optic nerve

46 Preoperative Checklist: Internal Carotid Artery

47 Concha bullosa media

48 Haller Cell

49 Haller Cell

50 Onodi Cell

51 Pneumatized Inferior Turbinate

52 3 Nervs??? Nervus opticus Nervus maxillaris Nervus vidianus

53 Cone Beam CT (Digitale Volumentomographie)

54 Cone Beam CT Corresponds to a C-arm with 3D images Digital volume tomography Cone revolves around patient for 360 Since 2000 Office use, no need for a radiologist

55 Low dose multislice CT Cone beam CT Acquisition time ( motion artefacts) Radiation exposure MSCT DVT 2 sec sec msv ( %) Image homogenity + + Bone window Soft tissue window Cost - + Image reconstruction msv + - De Cock et al. A comparative study for image quality and radiation dose of a cone beam computed tomography scanner and a multislice computed tomography scanner for paranasal sinus imaging. Eur Radiol (2015) 25: Al Abduwani et al. Cone beam CT paranasal ainuses versus low dose meltidetector CT studies. Am J Otolaryngol (2016)37:59-64

56 Navigation: Localization Systems Optical tracking systems Electromagnetic tracking systems + cordeless + free movement of surgeon - line of sight - magnetic interference

57 Accuracy Depends on: CT scan and its reconstruction Registration! Patient motion, motion of reference points! Generally accepted range: ± 1 mm (=2 mm) Shift in accuracy from anterior to posterior up to 9 mm (z axis)

58 Intraoperative Manual Registration Refinement New feature to adjust disaccuracy i.e. in the depth Before After

59 Navigation starts the day before surgery by: Analysis of the CT-scan (coronar,axial,sagittal): where is the frontal drainage pathway? Step by step surgical plan

60 Suggested Reading Simmen D, Schuknecht B: Computed tomography of paranasal sinuses. A preoperative checklist. Laryngo-Rhino-Otology 1997; 76:8-13 Simmen D, Jones N: Manual of endoscopic Sinus and Skull Base surgery. Thieme 2014, second edition Wormald PJ: Endoscopic Sinus Surgery: Anatomy, Three-Dimensional Reconstruction, and Surgical Technique. Thieme 2018, fourth edition

Radiological anatomy of frontal sinus By drtbalu

2009 Radiological anatomy of frontal sinus By drtbalu Anatomy of frontal sinus is highly variable. Precise understanding of these variables will help a surgeon to avoid unnecessary complications during