Ultrasound uses sound waves with frequencies above 20 kHz to produce images of tissues and structures. Piezoelectric materials are used to generate ultrasound, and images are formed by detecting reflected sound waves. Echogenicity refers to a tissue's ability to reflect sound waves, with more echogenic tissues appearing lighter on images. Ultrasound is used to evaluate thyroid disorders, lymph nodes, salivary glands, and other neck structures. It is a valuable tool for diagnosis and guidance of procedures due to its low cost, lack of radiation, and portability.

2.  Ultrasound – Sound with frequency > 20kHz
 In Medical practice ultrasound frequency used
are 2.5MHz-30MHz
 Active piezoelectric material (Zirconium titrate)
is used to produce sound
 Ultrasound images are formed by detecting and
displaying reflected sound waves from various
tissues

3. SONAR
Speed of Sound in water
1540m/sec
Distance can be Calculated

4.  Echogenicity is the ability to bounce an echo, i.e,
return the signal in USG
 Echogenicity is higher when the surface bouncing
the sound echo reflects increased sound
waves. Tissues that have higher echogenicity are
called "hyperechogenic" and are usually
represented with lighter colors
 Tissues with lower echogenicity are called
"hypoechogenic" and are usually represented with
darker colors.
 Areas that lack echogenicity are called
"anechogenic" and are usually displayed as
completely dark.

5. Transducer frequency
Typical: 3Mhz-12MHz
Resolution
High Frequency > Higher
Low Frequency > Poor
Depth of Penetration
High Frequency >
Shallow
Low Frequency > Deep

6. UltrasonographyCT&MRI
 Cheap
 No Ionising Radiation
 Portable
 No Contraindications
 Gold standard for determining Cystic or solid
 Role in FNAC / Drainage Catheter
 User Variablity/Reliablity
 Costly
 Ionising Radiations in CT
 Lots of Contraindications
 Better deliniation for deeper anatomy

7. o Doppler effect is the change in frequency or wavelength
of a wave for an observer moving relative to its source
o Sonography can be enhanced with Doppler
measurements to assess whether blood is moving towards or
away from the probe, and its relative velocity
o Lack of standards in the various laboratories for colour
coding

8.  Thyroid disorders
 Lymphadenopathy in Neck
 Parathyroid gland evaluation
 Salivary gland & Ducts evaluation
 Thyroglossal Cyst
 Branchial Cyst
 Ranula
 Hemangioma
 Lipoma
 Malformations
 Lymphangiomas

9. Cystic
Echo free Centre
Smooth Back wall
Acoustic enhancement
Solid
Many Echo reflection
Back wall indistinct
No enhancement

10.  Size assessment
 Evaluation of Thyroid Nodule
› Detection of focal mass
› Differentiation of Multinodular goiter/Hyperplasia
from other nodular diseases
› Extent of Thyroid Malignancy
› Follow up for residulal, reccurent or metastatic
carcinoma
› USG guided FNAC / FNA biopsy

11.  Deliniates Thyroid
Nodule but non
specific except for
papilary carcinoma
where some usg
features are
characteristic
 Extracapsular and
Vascular invasion
not detected

12. USG helps to define
thyroid enlargement
 Colour doppler
shows “Thyroid Storm”
Diagnostic of Graves
disease

13.  Most commonly used for evaluation of
enlarged Lymph node.
 Regional Classification of Lymph nodes in 7
levels by AJC on cancer.
 Level of Lymphnode Metastasis helps to
determine Primary
 Assessment of Lymph node number , Level
in neck and extranodal spread helps in
prognostic and therapeuatic evaluation

14.  USG guided FNAC to differentiate Malignancy
from reactive hyperplasia or tubercular
infiltration
 USG morphology of Malignant infiltrated lymph
node
› Round shape
› Short axis diameter 8 mm or more
› Heterogenous echotexture
› Cystic or necrotic area
› No echogenic (fatty) hilum
› Perihilar Halo
› Ill defined margins
› Invasion of surrounding tissues
› Intranodal Calcification

15.  Both Parotid and Submandibular are superficial
gland so can be examined best by usg
 USG deliniates pleomorphic adenoma of parotid in
95% of cases
 Stensen’s and Warton’s duct are seen on USG
when dialated
 Calculi larger than 2mm is seen as echogenic rim
with posterior acoustic shadowing
 Calculi less than 2 mm or at ostium are not seen
generally but can be indicated by duct dilation

16.  Parathyroid evaluation in case of adenoma and
hyperplastic gland based on echogenicity
(Echogenic) and Doppler (Vascular)
 Evaluation of Cystic lesions of Neck
› Thyroglossal cyst
› Branchial cyst
› Dysontogenetic cysts
› Laryngocoeles
› Ranula
 Evaluation of Soft tissue Neoplasms
› Lipoma
› Paraganglioma
› Lymphangioma
› Neurofibroma and schwannoma

17.  USG Evaluation of Maxillary Sinuses
 USG evaluation of Middle ear effusion
 Transfrontanelle evaluation
› Circle of willis
› Cephalohaematoma
› Periventricular Leukomalacia
› Hypothalamo-Pitutary axis
› Encephalocoele
› SubGaleal cyst