1. Paranasal sinuses By Dr. Mohsen Dashti Imaging Procedures 362 April 11 & 25, 2010

2. Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Anatomy Review Paranasal Sinuses Slide 2

3. Slide 3 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Paranasal Sinuses  Defined as the air-filled cavities located in the frontal, ethmoid, and sphenoid bones of the cranium, as well as the maxillae of the face  So named because of their formation from the nasal mucosa and their continued communication with the nasal fossas

4. Slide 4 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Functions  Serve as resonating chamber for the voice  Decrease weight of skull  Aid in warming and moisturizing inhaled air  Act as shock absorbers in trauma  Possibly control the immune system

5. Slide 5 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Development  Begins in fetal life  Maxillary sinuses are usually the only ones developed enough to be demonstrated radiographically at birth  By 6 to 7 years of age, frontal and sphenoid are distinguishable from ethmoids  Ethmoids do not fully develop until 17 to 18 years of age

6. Slide 6 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Maxillary Sinuses  Largest and most symmetric  Paired (one in each facial bone)  Vary in size and shape but are roughly pyramidal in shape

7. Slide 7 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Frontal Sinuses  Second largest  Paired  Located between vertical plates of frontal bone  Vary greatly in size and shape  Occasionally absent  Rarely symmetric

8. Slide 8 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.

9. Slide 9 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Ethmoid Sinuses  Located within lateral masses of labyrinths  Comprised of varying number of air cells, which are divided into three main groups  Anterior (2 to 8)  Middle (2 to 8)  Posterior (2 to 6)

10. Slide 10 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.

11. Slide 11 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Sphenoid Sinuses  Normally paired  Occupy body of sphenoid bone  Often only one sinus develops, but never more than two  Vary in size and shape  Usually asymmetric  Located below sella and extend between dorsum and posterior ethmoids

12. Slide 12 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.

13. Slide 13 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.

14. Slide 14 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Essential Projections  Lateral  PA axial (Caldwell method)  Parietoacanthial (Waters method)  Parietoacanthial (Waters) open-mouth modification  Submentovertical

15. Slide 15 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Technical Considerations  Density most critical to demonstrate pathology  Upright position necessary to demonstrate fluid levels  CR should remain horizontal  Shielding must be used on pregnant patients and pediatric patients  Proper collimation critical in reducing scatter radiation and patient dose

16. Slide 16 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Lateral Projection Demonstrates  All four sets of sinuses  AP and superoinferior dimensions of paranasal sinuses  Thickness of frontal bone  Detail of side closer to IR

17. Slide 17 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Lateral Projection  Patient position  Seated erect in anterior oblique position  Part position  MSP (mid-sagittal plane) of head parallel with IR plane  IPL (Interpupillary line) perpendicular to IR plane  IOML (Infraorbitomeatal line) parallel to transverse axis of cassette

19. Slide 19 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Lateral Projection  CR  Horizontal and perpendicular to IR  Enters ½  to 1  (1.3 to 2.5 cm) posterior to outer canthus  Center IR to CR

21. Slide 21 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Lateral Projection  All four sinus groups  Sphenoid of primary importance  No rotation of sella turcica  Superimposed orbital roofs  Superimposed mandibular rami  Clearly visible sinuses  Close beam restriction  Clearly visible air-fluid levels, if present

22. Slide 22 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Lateral Projection

23. Slide 23 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial Projection (Caldwell Method) Demonstrates  Frontal sinuses above frontonasal suture  Anterior ethmoid air cells  Sphenoid sinuses seen through nasal fossa below or between ethmoids  Petrous pyramids in lower third of orbits

24. Slide 24 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method) Angled Grid Technique  Patient position  Seated upright facing Bucky  MSP centered to midline

25. Slide 25 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method)  Patient position  Tilt vertical Bucky down 15 degrees  Rest patient’s forehead and nose on device  Center nasion to IR  MSP and OML perpendicular to IR plane

27. Slide 27 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method) Vertical Grid Technique  Position patient’s OML at 15-degree angle to horizontal CR  Center nasion to IR  MSP perpendicular  Radiolucent support may be needed at forehead  This method is not preferred due to increased OID, which results in decreased resolution

28. Slide 28 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method)  CR  Horizontal  Exits nasion  Center IR and CR

30. Slide 30 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method)  No rotation  Equal distance between lateral border of skull and lateral border of orbits  Petrous ridges symmetric  Petrous ridge lying in lower third of orbit  Frontal sinuses above frontonasal suture and anterior ethmoidal air cells above petrous ridges

31. Slide 31 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method)  Frontal and anterior ethmoidal air cells  Clearly visible air-fluid levels, if present  Close beam restriction

32. Slide 32 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. PA Axial (Caldwell Method)

33. Slide 33 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Parietoacanthial Projection (Waters Method) Demonstrates  Maxillary sinuses  Petrous pyramids lying inferior to maxillary floor  Frontal and ethmoid sinuses are distorted

34. Slide 34 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  Patient position  Seated erect facing Bucky  MSP centered to midline  Part position  Hyperextend neck to place OML at 37-degree angle from IR plane  MSP and MML (Mentomeatal line) perpendicular to IR plane Parietoacanthial Projection (Waters Method)

36. Slide 36 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  CR  Horizontal  Exits acanthion Parietoacanthial Projection (Waters Method)

38. Slide 38 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  Petrous pyramids immediately inferior to floor of maxillary sinuses  No rotation  Equal distance between lateral border of skull and lateral border of orbit  Orbits and maxillary sinuses symmetric  Maxillary sinuses  Close beam restriction  Clearly visible air-fluid levels, if present Parietoacanthial Projection (Waters Method)

39. Slide 39 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Parietoacanthial (Waters)

40. Slide 40 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. Parietoacanthial Projection (Open- Mouth Waters Method) Demonstrates  Sphenoid sinuses through open mouth  Maxillary sinuses  Petrous pyramids lying inferior to maxillary floor

41. Slide 41 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  Patient position  Seated erect facing Bucky  MSP centered to midline  Part position  Hyperextend neck to place OML at 37-degree angle from IR plane  MSP and MML perpendicular to IR plane  Open mouth wide while holding position Parietoacanthial Projection (Open- Mouth Waters Method)

43. Slide 43 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  CR  Horizontal  Exits acanthion Parietoacanthial Projection (Open- Mouth Waters Method)

45. Slide 45 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  Petrous pyramids immediately inferior to floor of maxillary sinuses  No rotation  Equal distance between lateral border of skull and lateral border of orbit  Orbits and maxillary sinuses symmetric  Maxillary sinuses Parietoacanthial Projection (Open- Mouth Waters Method)

46. Slide 46 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.  Close beam restriction  Clearly visible air-fluid levels, if present  Sphenoid sinuses projected through open mouth Parietoacanthial Projection (Open- Mouth Waters Method)

47. Slide 47 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. SMV Projection Demonstrates  Sphenoid and ethmoid sinuses  Mandible  Bony nasal septum

48. Slide 48 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. SMV Projection  Patient position  Upright  Part position  Hyperextend neck and rest vertex of head on vertical grid device  MSP perpendicular to IR plane  Neck extended to place IOML parallel to IR plane

50. Slide 50 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. SMV Projection  CR  Horizontal and perpendicular to IOML  Enters MSP ¾  (1.9 cm) anterior to level of EAM

52. Slide 52 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc. SMV Projection  No tilt  Equal distance from lateral border of skull to mandibular condyles on both sides  Anterior frontal bone superimposed by mental protuberance  Indicates IOML is parallel (full extension)  Mandibular condyles anterior to petrous pyramids  Clearly visible air-fluid levels, if present

53. Fun take away  Answer the following to the best of your abilities…….. Slide 53 Mosby items and derived items © 2007, 2003, 1999 by Mosby, Inc., an affiliate of Elsevier Inc.