Anatomic details and computed tomographic method of imaging

1. SABITA MANDAL
ROLL NO. 3
B.SC MIT 3R D YEAR
NAMS, BIR HOSPITAL
CT procedure of neck

2. Contents
 Anatomy
 Modalities for imaging neck
 Indications
 contraindications
 Imaging techniques
 References

3. Anatomy

4. Anatomy

5. Anatomy
 The neck is the part of the human body, that separates the head from
the torso or is the part of the human body that attaches the head to the
rest of the body.
 It contains blood vessels and nerves that supply structures in the head
to the body.
 Neck extends from anteriorly located cervix to the posteriorly located
nucha.
 Nucha consists of vertebral column and its associated musculature.
 Cervix (simply neck is a cylinder of soft tissue whose superior extent
is line connecting the occiput and tip of the chin and its inferior extent
parallels the course of the first rib at the thoracic inlet.

6. Anatomy
 For imaging purposes, the boundaries of the neck are
 mandible and the mylohyoid muscles- anterosuperiorly
 the base of the skull- posterosuperiorly
 the scapulae- posteroinferiorly
 the thoracic inlet- centrally in the inferior aspect.

7. Muscles of neck
 Superficial muscles
 Platysma muscle
 Sternocleidomastiod muscle
 trapezius muscle
 Deep muscles
 Suboccipital muscles
 Suprahyoid muscles
 Infrahyoid muscles
 scalene muscles

8. Anatomy

9. Anatomy
 The neck is divided into six triangles.
 The Sternocleidomastiod (SCM) muscle divides the
neck into
large anterior triangle
large posterior triangle.

10. The anterior triangle is further divided by both bellies of the digastric muscle and the superior belly of
omohyoid muscle into four triangles :
Submental triangle
Submandibular
triangle
Carotid triangle Muscular triangle
Boundaries Superiorly: the chin
Laterally: the two anterior
bellies of the diagastric
muscle
Medially: the mid-line
The bellies of the
diagastric muscles and
the mandible
Superiorly: the posterior
belly of the diagastric
muscle
Laterally: the anterior
border of the
Sternocleidomastiod
muscle
Medially: the superior
belly of the omohyoid
muscle
The superior belly of the
omohyoid muscle and
the sternohyoid muscle
Contents The submental lymph nodes The Submandibular
salivary glands and
Submandibular lymph
nodes
The carotid artery, the
internal jugular vein,
the vagus nerve and the
internal and external
laryngeal nerves
The deep structures
including the larynx,
trachea, thyroid and the
oesophagus

11. The posterior triangle is further divided by the inferior belly of the omohyoid muscle into two triangles:
Occipital triangle
the larger subdivision of the posterior
triangle
Supraclavicular triangle
the smaller subdivision of the
posterior triangle
Boundaries Anteriorly:
the Sternocleidomastoid muscle
Posteriorly: the Trapezius muscle
Inferiorly: the Omohyoid muscle
Anteriorly: the posterior border of
the Sternocleidomastoid
Superiorly: the inferior belly of the
Omohyoid muscle
Inferiorly: the clavicle
Contents Most lumps arising from the posterior triangle are due to enlarged occipital or
Supraclavicular lymph nodes.
Other important structures include the subclavian artery, the external jugular vein, the
accessory nerve, the phrenic nerve and parts of the brachial plexus.

13. Spaces of neck
 The ‘neck space’ concept is a commonly used
method in radiology in organizing the neck and
establishing appropriate differential diagnosis for
pathology discovered within a specific space of the
neck.
 These spaces may limit to some degree the spread
of most infections and some tumors.

14. Spaces of neck
 These spaces are described in relation to the hyoid
bone.
• Suprahyoid Spaces.
• Infrahyoid Spaces.
• Spaces extending up to the entire length of the neck

15. SUPRAHYOID NECK SPACES
• Sublingual Space.
• Submandibular Space.
• Buccal Space.
• Masticator Space.
• Parotid Space.
• Pharyngeal mucosal Space.
• Parapharyngeal Space

16. Anatomy

17. Anatomy of neck

18. INFRAHYOID NECK SPACES
• Visceral Space.
• Anterior cervical Space.
• Posterior cervical Space.

19. Anatomy

20. Anatomy
SPACES COMMON TO BOTH
• Carotid Space.
• Retropharyngeal Space.
• Prevertebral Space.
• Danger Space.

21. Neck spaces

22. Anatomy

23. Nodes of neck
Cervical nodes are classified into seven groups, each designated by
a
roman numeral as follows:
Level I: Submandibular and submental lymph nodes.
Level LI: Internal jugular chain from the skull base to the
level of the carotid bifurcation.
Level 111: Internal jugular chain from the level of the carotid
bifurcation to the level of the intersection of the chain with the
omohyoid muscle.
Level IV: Infraomohyoid portion of the internal jugular chain.
Level V: Posterior triangle lymph nodes.
Level VI: Nodes related to the thyroid gland.
Level VII: Nodes in the tracheoesophageal groove and superior
mediastinum.

26. Imaging modalities
 CT
 MRI
 US
 Plain X ray and conventional studies
 Isotope scan
 Angiography

27. Indications
 Inflammatory, nodal and tumoral diseases including
lymphoma and metastases.
 Thyroid diseases
 Pharyngeal lesions
 Salivary glands pathologies
 Detection /confirmation of lesions
 Follow-ups
 Trauma

28. Contra-indications
 Hypersensitivity to iodinated contrast media
 Pregnancy(relative)
 Renal diseases

29. Patient Preparation
 Clear history should be taken along with reports of
previous investigations.
 Pregnancy needs to be ruled out.
 Radiopaque materials should be removed from FOV.
 Proper information and instruction about the
procedure.
 NPO for 4-5 hours prior to procedure for CECT

30. Patient Preparation
 Blood Creatinine levels should be in its normal limit
(M=0.6 to 1.5,F=0.5-1.2 mg/dl) and Blood urea level
should range between 9 to 42 mg/dl
 Signed informed consent from patient or his/her
close relatives.
 Irritable/uncooperative and Pediatric patients
should be sedated.
 Neck should be in neutral position.
 The patient should be instructed to avoid
swallowing movements.

31. Routine Neck protocol
Patient positioning
 Head first, supine with arms by the sides of the trunk with
hands tucked under the hips.
 Head rest/support can be applied to restrict the neck
movement.
Topogram position/Landmark
 lateral; level of forehead

32. Routine Neck protocol
 Mode of scanning
 Helical with single breath-hold technique
 Scan orientation
 Cranio-caudal
 Starting location
 Base of the skull
 End location
 Arch of the aorta
 Cranio-caudal orientation reduces artifacts at the level of the
thoracic inlet caused by the beam-hardening effects of the
contrast agent.
 FOV
 Just fitting the ROI.

33. Routine Neck protocol
 Gantry tilt
 To make the plane of the scanning parallel to the hard palate or
perpendicular to the plane of larynx.
 Contrast administration
 Intravenous and monophasic
 Volume of contrast
 80-100 ml
 Rate of injection of contrast
 2-3 ml/sec
 Scan delay
 30-40 sec

34. Routine Neck protocol
Slice thickness in reconstruction
 3-5 mm
Slice interval in reconstruction
 1.5-2.5 mm
Reconstruction algorithm/kernel
 Medium smooth for soft tissue.
 Sharp for cartilage, bone and lung parenchyma in the scan
range.
3D-Reconstructions
 MPR
 MIP

35. Comments
 Unless contraindicated , IV contrast media is used
when scanning the neck.
 The goals in CT scanning of the neck are to allow
sufficient time after contrast administration for
mucosa , lymph nodes , and pathology tissue to
enhance , yet acquire images while the vasculature
remains opacified .
 Scanning too early after the contrast media injection
could result in certain types of neoclassic and
inflammatory processes going undetected .

36. Cont…
 However, by delaying scan acquisition , the injected
contrast agent will no longer opacify the vasculature .
 One strategy for addressing these contradictory goals
is a split bolus .
 The total contrast dose is split , often in half .
 The first dose is given and a delay of about 2 minutes
is observed .
 This allows time for structures that are slower to
enhance to be opacified.

37. Cont…
 This allows time for structures that are slower to
enhance to be opacified.
 The delay is followed by a second bolus containing
the remainder of the contrast ; scanning is initiated
soon after the second injection to more fully opacify
the vessels .
 The split bolus injection technique is also frequently
used for maxillofacial studies in which contrast
media is indicated .

38. Protocol for Larynx and Hypopharynx
 Over 90% of all masses in the region of hypopharynx
and larynx are squamous cell carcinoma.
 Tumors of hypopharynx most often arises in the
pyriform sinus.

39. Protocol for Larynx and Hypopharynx
Indications
 Screening for inflammatory or mass/tumoral diseases of the
larynx and hypopharynx.
 Traumatic lesion.
 Preoperative baseline scan
 Post-surgery or post-chemotherapy follow-ups.
Patient positioning
 Head first, supine with arms by the sides of the trunk with
hands tucked under the hips.
 Head rest/support can be applied to restrict the neck
movement.

40. Protocol for Larynx and Hypopharynx
 Topogram position/Landmark
 lateral; level of forehead
 Mode of scanning
 Helical with single breath-hold technique
 Scan orientation
 Cranio-caudal
 Starting location
 Base of the skull
 End location
 Arch of the aorta
 FOV
 Just fitting the ROI.

41. Protocol for Larynx and Hypopharynx
 Gantry tilt
 To make the plane of the scanning parallel to the hard palate or
perpendicular to the plane of larynx.
 Contrast administration
 Intravenous , monophasic
 Volume of contrast
 80-100 ml
 Rate of injection of contrast
 2-3 ml/sec
 Scan delay
 30-40 sec

42. Protocol for Larynx and Hypopharynx
 Slice thickness in reconstruction
 3-5 mm
 Slice interval in reconstruction
 1.5-2.5 mm
 Reconstruction algorithm/kernel
 Medium smooth for soft tissue.
 Sharp for cartilage, bone and lung parenchyma in the scan range.
 3D-Reconstructions
 MPR
 MIP
 Virtual endoscopy
 Dynamic manouvers (in MDCT)
 e phonation (for a better visualization of the laryngeal ventricle)
 modified Valsalva-cheeks puffed with a gradual escape of air
(for a better visualization/dilation of the pyriform sinuses).

43. Protocol for nasopharynx, oropharynx and
oral cavity
Indication
 Staging of malignant tumors.
 Suspected arrosion of the skull base, the hard palate
or the mandible.
 Parapharyngeal masses, inflammatory processes
such as para or retropharyngeal abscess.
 Detection and differentiation of benign lesions.

44. Protocol for nasopharynx, oropharynx and oral
cavity
Patient preparation
 Remove dental prosthesis, etc
 Instruct the patient to perform quite breathing and
not to swallow.

45. Protocol for nasopharynx, oropharynx and oral
cavity
 A. Topogram covering the entire pharynx and neck
 B. Topogram showing two spirals avoiding dental
artifacts (possible with 4 row scanner)

46. Scan Parameters 16 slice scanner
Scanner settings
Tube voltage (kv) 120
Rotation time (s) 0.75-1
Tube current time product(mAs) 180
Pitch corrected tube current time product
(eff.mAs)
140-230
Collimation (mm) 1.25/1.5
Normal pitch 1-1.3
Recon. – slice increment(mm) 2-3 For recon .- 1
Recon. – slice thickness(mm) 3 For recon .- 1.5-2
Convolution kernel Standard and bone
Scan direction Caudocranial
CM application Yes
Conc. Of CM (mg I / ml) 300
Volume (ml) 100
Inj. Rate (ml/s) 1.5-2.0
Saline chaser (ml/s) No
Delay (s) 55 (fixed)

47. Cont…
 Regarding bony erosions ct is regarded to be
superior to MRI , but regarding perineural tumor
spread through skull base foramina and/or Dural
infiltration MRI (lateral infiltration of the
Parapharyngeal fat space) is superior to CT.
 Thus a combination of both , CT and MRI , is
necessary.

48. CT Carotid Angiography
Indications
 Suspected occlusion of the carotid arteries, their aneurisms,
dissections.
 Preoperatively for head /neck tumors to detect the origin of
their feeding vessels for the purpose of ligation.
Patient positioning
 Head first, supine with arms by the sides of the trunk with
hands tucked under the hips.
 Head rest/support can be applied to restrict the neck
movement.

49. CT Carotid Angiography
 Topogram position/Landmark
 lateral; level of forehead
 Mode of scanning
 Helical with single breath-hold technique
 Scan orientation
 Caudo-Cranial
 Starting location
 Arch of the aorta
 End location
 2-3 cm above the sella
 FOV
 Just fitting the ROI.

50. CT Carotid Angiography
Gantry tilt
 Nil
Contrast administration
 Intravenous , monophasic
Volume of contrast
 100-120 ml
Rate of injection of contrast
 4-5 ml/sec
Scan delay
 10-15 sec

51. CT Carotid Angiography
Slice thickness in reconstruction
 1.0-1.5 mm
Slice interval in reconstruction
 0.5-0.75 mm
Reconstruction algorithm/kernel
 smooth
3D-Reconstructions
 MIP
 VRT (preferably after bone subtraction)

52. Advantages of MRI over CT
• Multiplanar capability
• Lack of ionizing radiation
• Safer contrast agents
• Better imaging of soft tissues of neck
Advantages of CT over MRI
• Superior assessment of osseous integrity
• Shorter examination time
• Wider patient access
• Lower cost

53. Limitations of CT
 It is an expensive technique.
 Very high density restorations as dental restorations
produce severe artifacts on the CT scan.
 High dose of radiation.
 There is an inherent risk with the use of contrast
media.

54. References
 CT and MRI protocol- a practical approach, Satish K
Bhargava.
 CT and MRI of whole body, Fifth edition, Johan R.
Hagga.
 Protocols for multislice CT, 2nd edition.
 Internet sources

55. THANK YOU