Introduction and Basics of Ultrasonography.pptx

Introduction and Basics of Ultrasonography.pptx

1. Introduction and Basics of Ultrasonography By – Dr Chetan Salvatkar 1 st yr PGT Department of Radiodiagnosis Civil Hospital Shillong

2. Contents History Basic Science Behind Ultrasound Indications and Contraindications Ultrasonography Machine and Knobology Transducers and Probe Manipulation Imaging Modalities Compound Imaging and Harmonics Artifacts Fine Tuning The Image Care of USG Machine Guidelines for Infection Prevention and Control Abdominopelvic Anatomy (Sizes and Measurements)

3. 1794: Lezzaro Spallanzani Physiologist First deduced bats used ultrasound to navigate by echolocation

4. 1826: Jean Daniel Colladon Physicist Used under water church bells The first sound transducer Calculated speed of sound through water Proved sound travelled faster through water

5. 1880: Pierre & Jacques Curie -Discovery of the Piezo-electric Effect -The ability of certain materials to generate a certain charge in response to applied mechanical stress -piezo(Greek) = to squeeze or press

6. 1915: Paul Langevin Physicist Titanic sinks in 1912 Invented hydrophone – 1 ST transducer to detect icebergs Detects submarines in World War 1

7. 1942:Karl Dussik Neurologist, psychiatrist 1 ST Physician to use ultrasound Diagnosed brain tumours

8. 1948: Dr George Ludwig First described the use of ultrasound to diagnose gallstones

9. 1950: John J. Wild Physician who was part of the first group to use  ultrasound  for body imaging, most notably for diagnosing cancer. Modern ultrasonic diagnostic medical scans are descendants of the equipment Wild and his colleagues developed in the 1950s

10. 1958: Ian Donald Scottish physician Started at shipyard Pioneer of OBGYN Ultrasound Abdominal masses

11. 1950-1960s: Douglass howry & Joseph Holmes Pioneer 2D B-mode ultrasound First boom in diagnostic imaging Founded AIUM

12. 1970: Occular Imaging, Doppler & POCUS German and Japanese physicians begin to use ultrasound to diagnose pericardial effusions in trauma patients

13. 1980s : Power Doppler, 3D & POCUS

14. 2001:ACEP US Guidelines Resuscitative : us use as directly related to acute resuscitation Diagnostic : utilisation in emergent diagnostic imaging capacity Symptom/sign based : used in a clinical pathway based on patients clinical features( eg . s.o.b) Procedure guidance : used as an aid to guide a procedure Therapeutic and monitoring : in therapeutics or in physiological monitoring Trauma Intrauterine pregnancy AAA Cardiac Biliary Urinary tract DVT Soft tissue/musculoskeletal Thoracic Occular Procedural guidance

15. Why is Ultrasound Important ? The WHO estimates that upto 75% of the worlds population has no access to any diagnostic imaging Diagnostics that are versatile, portable, inexpensive,safe,practice changing Has changed the medical diagnostic landscape Power to the practitioners

16. Basic Science behind Ultrasound Sound requires medium Ultrasound is a mechanical,longitudinal pressure wave Humans hearing range : 20 Hz - 20KHz Diagnostic ultrasound : 2MHz – 15MHz Ultrasounds are produced by transducers Transducers converts one form of energy into another form Electrical energy into ultrasonic energy and the reflected ultrasonic energy into electrical signals by using piezoelectric materials.

17. - Frequency = No of oscillations/ sec ( expressed in Hertz ) 1 cycle in 1 sec = 1 Hz - Wavelength = Distance between two successive areas of compression or rarefaction , denoted by “Lambda “ ( λ ) - Velocity : distance travelled in unit time , ( expressed in cm /sec ) velocity (v) = wavelength x Frequency Frequency and wavelength : inversely proportional The velocity of sound in tissue is assumed constant at 1540 m/sec Determined by density and stiffness of media- Slowest in air/gas- Fastest in solids - Amplitude The strength/intensity of a sound wave at any given time Represented as height of the wave Decreases with increasing depth Velocity=Distance/time

18. Frequency-Penetration-Wavelength-Resolution

19. -Quartz/synthetic ceramic -Lead zirconate titanate Piezoelectric Effect

20. Acoustic Impedance(Z) (MegaRaylz) Tissue Density * Velocity of sound within tissue Resistance to the propagation of sound and this depend on density and velocity of sound Amplitude of returning echo is proportional to the difference in acoustic impedance between the two tissues When an ultrasound beam encounters two regions of very different acoustic impedances, the beam is reflected or absorbed Velocity:- Soft tissues = 1400-1600m/sec- Bone = 4080 Air = 330 Z soft tissue - Z bone interface = {Lesser penetration} Air = 0.0004 Z. (Low acoustic impedance). Bone = 7.8 Z. (High acoustic impedance). Adipose = 1.34 Z. Liver = 1.65 Z.

21. US And Tissues Reflection-: Occurs at a boundary between 2 adjacent tissues or media- The amount of reflection depends on differences in acoustic impedance (z) between mediums Refraction-: Happens when ultrasound waves pass from one tissue to another with different sound speeds, causing the wave to bend Absorption-: As ultrasound waves travel through tissue, some of their energy is converted into heat, a process known as absorption Transmission-: Not all the sound wave is reflected, some continues deeper into the body These waves will reflect from deeper tissue structures Attenuation-: The deeper the wave travels in the body, the weaker it becomes The amplitude of the wave decreases with increasing depth Air (lung)> bone > muscle > soft tissue >blood > water. Scattering:- Redirection of sound in several directions Caused by interaction with small reflector or rough surface Only some portion of sound wave returns to transducer

22. Image Formation on Monitor The amplitude of each reflected wave is represented by a dot The position of the dot represents the depth from which the echo is received The brightness of the dot represents the strength of the returning echo These dots are combined to form a complete image Electrical signal produces 'dots ' on the screen. Brightness of the dots is proportional to the strength of the returning echoes Location of the dots is determined by travel time. Reflected Echoes Strong Reflections = White dots - Pericardium, calcified structures, diaphragm Weaker Reflections = Grey dots - Myocardium, valve tissue, vessel walls, liver No Reflections = Black dots - Intra-cardiac cavities, gall bladder Acoustic Window Good:- Liver Spleen Urine filled bladder Poor:- Gas Strong reflectors

23. Echogenicity

24. 256 Shades of Grey

25. Indications and Contraindications Imaging solid organs – Liver Kidney Spleen Fluid filled structures- Bladder NO real absolute contraindications - if unlikely to answer clinical problem - and/or another imaging modality is more appropriate Diagnostic accuracy reduced –as patients size increases - may not be useful in some VERY large patients - un-cooperative / confused patients Uses no Ionising radiation no significant adverse effect safe to use in all patients

26. Ultrasound gel Ultrasound waves -travel well through solid and liquid media -scattered by gases Gel is used as an interface between transducer and the patient - to improve transmission between transducer and body Ultrasound gels are prepared using fresh aloe vera gel, which does not irritate the skin and makes them safe for people with sensitive skin -noncorrosive and nontoxic material 

27. USG Machine and Knobology

28. Probes Types :- Phased array(2-8) Linear array(5-13) Curved array :-- Short – Endoluminal (8-13) Large – Transabdominal (2-5)

29. Probe Manipulation Translation in 3 axes – sweep slide compression Pivot in 3 axes - rock fan rotation

30. Planes of imaging

31. Imaging Modalities Grey scale Imaging Doppler Imaging power color duplex continuous wave pulsed wave

32. Compound Imaging and Harmonics Multiple frames generated from different steered angles Averaged together the frame , to create the image Reduction of noises increasing high level reflectors reducing low level reflectors Takes more time for each image Decreased shadowing Higher frequency integers of generated frequency Formed in the tissue Turn on harmonics- filter that removes original frequencies from image generation Decrease attenuation from subcutaneous fat Improved lateral resolution Reduced side lobes Improves image quality and may reduce artifacts , even helpful artifacts like posterior Acoustic shadowing and enhancement

33. Artifacts Useful Acoustic enhancement – Helps in diagnosing (cystic lesions). Acoustic shadowing - in diagnosing calculi Non useful Lateral cyst shadowing Wide beam artifacts Side lobe artifact Reverberation artifact Gain artifact Contrast artifact Mirror image artifact

34. increased echogenicity (whiteness) posterior to the cystic area. The presence of acoustic enhancement aids in the identification of cystic masses but some solid masses, especially lymphoma, may also show acoustic enhancement posteriorly visual artifact, a dark or obscured area behind a structure, caused by a high impedance mismatch where the sound wave is largely reflected or absorbed rather than transmitted. This occurs when ultrasound waves encounter a boundary between tissues with significantly different acoustic properties, such as bone, calcifications, or air.   a shadowing artifact that occurs at the sides of a cyst, causing a dark or hypoechoic line extending away from the cyst wall. This artifact is due to the way sound waves are reflected or refracted as they interact with the cyst's edges and surrounding tissue.   a phenomenon where structures that are actually smaller than the ultrasound beam's width appear larger or blurred on the image. This artifact can make it difficult to accurately determine the size and location of objects, particularly in areas where the beam is wide. 

35.   Side lobe artifacts  occur where  side lobes  reflect sound from a strong reflector that is outside of the central beam. Reverberation artifact  occurs when an ultrasound beam encounters two strong parallel reflectors. Artifacts are echoes that appear on the image but do not correspond to actual anatomical structures, and can be influenced by gain settings

36.  distortions or inaccuracies in the image caused by the interaction of sound waves with the contrast agent, leading to misinterpretations of the underlying tissue or blood flow. These artifacts can manifest in various ways, such as blooming, pseudo-enhancement, and signal saturation occur when the transmitted pulse and returning echo reflect off of a highly reflective interface (an acoustic mirror) and change direction before returning to the transducer

37. Fine Tuning The Image Choose the correct transducer Adjust the depth to the centre area of interest Actively adjust the gain Images in 2 views

38. Care of USG Machine Clean machine and probes with soft cloth Use recommended disinfectant on probes DO NOT - use commercial cleaners or alcohol on machine or probes DO NOT – drop probe run over cords place probes and cords in matted/complicated manner

39. Guidelines for Infection Prevention and Control Perform rinsing and drying after sterilization or disinfection, if required based on the reprocessing method and requirements of the manufacturer's IFU. Thoroughly dry the transducer before storing. These steps can help ensure that no chemical residues remain on the transducer after reprocessing.

40. Abdominopelvic Anatomy LIVER UPPER BORDER – 5 th ICS LOWER BORDER - extends to or slightly below costal margin Liver length – in mid hepatic line (15.5cm) - homogeneous , contains fine-level echoes , and is either minimally hyperechoic or isoechoic compared to the normal renal cortex - hypoechoic compared to the spleen

41. Couinaud functional anatomy Universal nomenclature for hepatic lesion localization , this description is based on portal segments , and is of both functional and pathological importance.

42. PORTAL VEIN Liver – dual blood supply Portal vein hepatic artery Portal pressure – 5-10 mmHg Portal triad – portal vein hepatic artery common bile duct inside connective tissue sheath gives portal vein echogenic wall

43. SPLEEN convex superolateraly concave inferomedially homogenous echo pattern . Lies between fundus of stomach and diaphragm , with its long axis of left 10 th rib suspended by the splenorenal ligament ,in contact with posterior peritoneal wall , phreniccolic ligament , and gastrosplenic ligament splenic parenchyma - homogenous , echogenicity is more than liver . length - 10.65 cm .

44. GALL BLADDER Pear shaped mid hepatic vein – lies in same anatomical plane - used to find GB fossa Divided into – fundus -body -neck Hartmann pouch – in area of neck - an infundibulum -common location for impact of gallstones

45. COMMON BILE DUCT Diameter -normally 6 mm or less - larger - elderly patients - Post cholecystectomy status Longitudinal view of gall bladder CBD has no color flow unlike portal vein and hepatic artery

46. PANCREAS - 8 HOURS Fast -obliquely in the anterior pararenal space of the retroperitoneum , with the head caudal to the body and tail . -The pancreas is draped over the spine and aorta -the neck and body are more superficial than the head and tail landmarks- for body of the pancreas - the splenic vein , - its confluence with SMV and SMA pancreas varies in parenchymal echogenicity ,texture , shape and size . The pancreatic parenchyma usually isoechoic or hyperechoic compared with hepatic parenchyma . pancreatic echogenicty increases with age .

47. KIDNEY Paired ,retroperitoneal,bean shaped T12-L3 vertebrae , with the left kidney typically somewhat more superior in position than the right. The upper poles are normally oriented more medially and posteriorly than the lower poles . heterogeneous - mixed echo pattern renal cortex - midgray and homogeneous (uniform echo pattern ) with smooth contour , where as the renal sinus present as bright with irregular border The kidney cortex is described as hypoechoic compared to the adjacent normal liver . The pyramids as well as the infundibulum and renal pelvis are only visualized when they contain urine. The ureters are not normally visualized .

48. URINARY BLADDER hollow muscular, elastic, subperitoneal organ , located at the lesser  pelvic   cavity 400–500 mL . The ureters enter the bladder posteriorly in an oblique manner . The orifices are situated approximately 2.5cm apart. The trigone occupies the area between the two orifices and the bladder neck . In males , the bladder is related posteriorly to the seminal vesicles, vasa deferentia, ureters, and rectum . In females , the uterus and vagina are interposed between the bladder and the rectum . In both males and females, the bladder is related to the posterior surface of the pubic symphysis   Width x Depth x Height x Correction Coefficient(0.7)

49. OVARY Difficult to visualise d/t overlying bowel gases full bladder- good acoustic window transvaginal ultrasound should be used to evaluate the ovaries. • With the probe still in the transverse position, rock the tail of the probe to the patient's left to visualize the right ovary .

50. POUCH OF DOUGLAS Small amounts of free fluid in the pelvis (usually <10 mL but up to ~20 mL near ovulation) can be normal in females. This is especially true in patients following ovulation , after menopause , or during early pregnancy. Menstrual cycle Small to moderate amounts of fluid can be normal, depending on the phase Ruptured follicle or cyst Fluid can build up after a ruptured follicle or ovarian cyst Ectopic pregnancy Blood from a ruptured ectopic pregnancy can collect in the pouch of Douglas Infection Inflammatory debris from a pelvic or appendiceal infection can build up Fertility treatment Some fertility treatments can cause extra fluid

51. APPENDIX Tubular bowel structure < 6mm Non compressible , tubular blind ended structure Aperistaltic

52. Normal Measurements Adominal aorta : < 3cm diameter IVC : 12 to 17 mm Appendix : < 6mm caliber Gall bladder wall : < 3mm ( well distended state) CBD : < 6mm add 1mm for each decade over 60yrs , upto 10 mm postcholecystectomy Hepatic vein : 5.6 to 6.2 mm Portal vein : < 13 mm Splenic vein : < 10 mm Kidney : 8-10 cm x 4-6 cm Liver : <15.5 cm Spleen : < 12 cm Endometrial thickness : premenopausal : 3-15mm , post menopausal : <6mm Ovarian follicle : < 2.5 – 3 cm Ovaries volume : premenopausal : <10ml , post menopausal : <8ml Pancreas : head : 3.5mm , neck : 2.5mm , tail : 1.5 mm Prostate volume : < 25-30ml Testis : size 5 x 3 x 2 cm ( volume 12.5-19 ml)

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