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Ultrasonography

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Basics of Ultrasound
Basics of Ultrasound
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Ultrasonography

  1. 1. ULTRASONOGRAPHY TYPES & INDICATIONS IN MAXILLOFACIAL REGION PRESENTED BY V.ANUSHA MDS
  2. 2. contents • Introduction • Characteristics of sounds • Display modes • Recent advances in display modes • Indications of usg in maxillofacial region • Advantages • Disadvantages • Recent advances
  3. 3. INRODUCTION • Ultrasound is an imaging modality that utilizes high-frequency sound waves to produce cross-sectional images of the body
  4. 4. SOUND • Sound is result of mechanical energy transmitted through the medium as a pressure wave • In resting state, pressure is uniform through out medium • Physical displacement of materials cause transmission of sound • The sound wave produced has areas of high pressure (or high density) and low pressure (or low density)
  5. 5. • The high-pressure areas (compression) are where the sound waves are compressed together • The low-pressure areas (rarefaction) are where the sound waves are spaced apart
  6. 6. • The distance between corresponding points on the time pressure curve is defined as the wavelength (λ), • Time (T) to complete a single cycle is called the period. • The number of complete cycles in a unit of time is the frequency (f ) of the sound. • Frequency and period are inversely related. • f = 1/T
  7. 7. • The unit of acoustic frequency is the hertz (Hz) • 1 Hz = 1 cycle /second. • Audible sound frequency: 15 to 20,000cycles /sec • US has a frequency greater than 20,000cycles/sec • High frequencies are expressed in kHz/ MHz • 1 kHz = 1000 Hz • 1 MHz = 1,000,000 Hz (or)1 million cycles / second • Diagnostic US – 2 TO 20 MHz
  8. 8. Display modes A M B DOPPLER
  9. 9. A-mode (amplitude) • Used to measure distance by displaying the amplitude of the wave versus time (ie, depth) for the return of that pulse. • Echoes are displayed as spikes projecting from base line.
  10. 10. Measured spectrum is a graph of amplitude versus time. The time for a pulse to come back is proportional to the distance.
  11. 11. • This mode allows for precise measurements, it was used in ophthalmology for ocular measurements. • HELPS IN RECORDING POSITION & STRENGTH OF REFLECTING SURFACE • LIMITATION : presents echo data from a single beam.
  12. 12. M-MODE & TM-MODE • Detects motion of structures- cardiac valves and of cardiac chambers , vessels. • Echoes are displayed as dots of varying intensity. • It displays echo amplitude & Shows position of moving reflectors
  13. 13. M mode • M-Mode does not have Time factor • TM-Mode has Time factor • M – mode US – functional Assesment of striated muscles
  14. 14. Brightness mode(B mode)  Echo signals as – Line of dots.  Intensity of dot gives relative size of echo  It provides depth of information and variations in direction of beam
  15. 15. GRAY SCALE IMAGING • Displays the variation of Amplitudes of echoes arising from tissues as varying shades of gray on monitor Real time imaging • The images change with each movement of the transducer or if any part of the body is moving • The movement is shown on the monitor in real time as it occurs
  16. 16. Colour doppler imaging
  17. 17. • Doppler effect is a change in the perceived frequency of sound emitted by a moving source Us beam with a frequency hits a stationary reflector Echoes will be of same frequency as transmitted Us beam hits a moving reflector ( towards transducer) increased in frequency Decrease in frequency hits a moving reflector ( away from transducer)
  18. 18. Doppler equation
  19. 19. Types of doppler • Continuous – rare – only in cardiac scanners • Pulse/ Spectral ( duplex) • triplex – colour + spectral • Power doppler Intra Oral doppler • Indirect – intracavitary transducer covered with gloves filled with water • Direct oral – small specialised probe
  20. 20. Colour doppler • Blood vessel is located by B- mode ultrasound imaging and then the blood flow is measured by colour doppler • Computer overlays a colour box • The operator positions a box on the image, and colour is superimposed wherever the scanner detects a moving structure, usually blood • velocities are distinguished by different colours
  21. 21. Spectral doppler
  22. 22. Power doppler : • Technique that uses amplitude of doppler signal to detect moving reflectors • It is independent of velocity , direction of flow & Angle of insonation • Highly sensitive for low velocity flow lesions • Grading stenosis
  23. 23. ADVANTAGES • Color Doppler depicts - anatomic view and identifies the presence, quantity, & type of vascularization • Mean velocity and direction of blood flow in ROI • To identify feeding and draining vessels • spectral curve analysis of a blood vessel determines the arterial or venous nature of the flow, as well as its velocity (cm/s) • Help in the Dd of vascular & nonvascular nodular lesions in the oral cavity
  24. 24. Recent Advances • DYNAMIC MUSCLE US : • US tech with improved spatial resolution, frame rate ( 15/sec) • Helps to detect smaller movements of muscle • Fasiculations - short jerky movements • Fibrillations – small, irregular oscillatory movements
  25. 25. Panoramic imaging / extended field of view • Static image was produced by moving a 1-D probe across the examination area. • Extended view is created by sweeping the probe in the lateral direction over a region of interest in freehand.
  26. 26. • 3D : reconstructed from multiple 2D/1D images • 4D : If a 3-D volume is recorded over time and if the frame rate is high enough to cover a single cardiac cycle, this technique is called 4-D ultrasound. • Results in live action images
  27. 27. • US ELASTOGRAPHY: • Gives info about consistency of structures ( soft /firm) Red – increased stifness, purple – decreased stifness
  28. 28. Applications of USG & doppler in maxillofacial region
  29. 29. • sonographic images are identified in terms of echoes • A mass is hypoechoic- intensity lower than that of the adjacent tissue • Hyperechoic - masses of higher intensity ( bright) • Isoechoic - masses with intensity similar to the adjacent tissue. • Anechoic – no internal echoes, appears darker • A calcified mass - hyperechoic • clear fluid or blood – anechoic
  30. 30. • Homogeneous - even echo pattern or reflections that are relative and uniform in composition • Heterogeneous - to an uneven echo pattern or reflections of varying echo densitities. • If a mass lesion contains hyperechoic and hypoechoic areas, it is described as a heterogeneous mass
  31. 31. • Peri apical lesions – abscess, cyst, granuloma • Soft tissue lesions – fibroma, pyogenic granuloma, space infections, Peritonsillar abscess • Osmf • Salivary : Mucocele , ranula, sialadenitis, sialoliths, tumors • Maxillofacial AV anomalies • IO jaw lesions • Assesing nature of lymphnodes • Muscles of mastication & other facial muscles • TMJ ?
  32. 32. • Prognostic denture failure • Viability of mucocutaneous flap • Guiding FNAC
  33. 33. • Ultrasonography has been used by a few researchers ( Shawker 1984; Vinka – puhakka (1989) to examine soft tissues surrounding oral cavity • Wilson IR ( An intro to USG in oral surgery. Oral surg oral med oral pathol.1985;59: 236 – 241) HR USG to examine facial tissues before & after surgical removal of impacted 3rd molar • Info concerning site & dimensions of post surgical edema & hematoma can be obtained
  34. 34. Periapical abscess , space infection : poorly defined, hypoechoic Periapical granuloma: • Poorly defined lesion • Internal echoes – hyper/ hypoechoic • Rich vascularity
  35. 35. • Simple cyst : anechoic to hypoechoic ( as it is a fluid filled cavity) • Smooth walled with acoustic enhancement • No vascularity in colour doppler
  36. 36. • Gundappa M “Comparison of ultrasound, digital and conventional radiography in differentiating periapical lesions”. Dentomaxillofacial Radiology (2006) 35, 326–333 • US imaging is possible through thinned or perforated cortical bone. • It underestimates the dimensions of the lesions, but can provide accurate information on the pathological nature of periapical disease • They confirmed US as a reliable tech for differentiating peri apical cysts & granulomas
  37. 37. • US provides accurate info on pathological nature of lesions, inflammatory process, capsular thickness of lesion. • It also differentiates b/n simple & complex cyst • Nature of content differentiation into solid/ semisolid cyst
  38. 38. • Tikku AP et.al evaluated “Use of US & CD imaging and radiography to monitor periapical healing after endodontic surgery”Journal of Oral Science.2010; 52:411-416) • USG in combo CD yields considerable info on nature of bone healing & vascularity. • Detecting changes in the healing of hard tissue at the surgical site by this tech was stat. sig when compared to conventional imagimg. (P < 0.004).
  39. 39. OSMF • Normal mucosa - the connective tissue was loosely woven - only low echogenicity was induced • Fibrotic bands – increase no.of echoes – brighter • Manjunath K “(Evaluation of oral submucous fibrosis using ultrasonographic technique: A new diagnostic tool. Indian Journal of Dental Research. 2011)” • USG – delineates normal mucosa with uniform fine mottled appearance with interspersed hypoechoic areas.
  40. 40. • osmf pts USG – no, length, thickness of fibrotic bands • CD, Spectral doppler – decreased vascularity & PSV in lesional areas. • (normal pts venous flow – continued pattern with avg. PSV – 1-2 cm/sec, arterial flow – pulsatile pattern . PSV – 3- 9 cm/sec)
  41. 41. • Thapasum AF (Gray-scale ultrasonographic imaging of the buccal mucosa in various stages of osmf. Oral radiol. 2014) • Correlated these findings with clinical, hp • The results – stage progresses – statistically significant increase in echogenecity ( corresponding to fibrotic component)
  42. 42. Salivary gland Indications : • Acute infl. Conditions – to diff obstructive & non obstructive sialadenitis • Abscess, I& D – US guidance • Cystic lesions , Mucocele, ranula • Salivary gland tumors – benign & malignant • Sialoliths – intraductal/ glandular • Ductal dilatation/ inflammatory changes • Multi locular lesions – sarcoidosis, lymphoma, metastasis, cystlymphadenoma • Pseudotumorous lesions – MMH, TB, sarcoidosis, lymphoepithelial lesions
  43. 43. Sonographic anatomy : • All salivary glands are homogeneous echogenic glandular organs. Parotid : homogeneous & echogenicity is comparable to that of the thyroid gland. • Deep part of parotid – not seen ( ramus) • retro mandibular vein can be visualised • Intra glandular ducts are rarely visualised • Stensons duct visualised ( when it is dilated)
  44. 44. Parotid : superficial lobe, deeplobe, duct, masseter, ramus
  45. 45. • Sub mandibular gland : oblique section – triangular • On a typical oblique section of gland , tonsils are visualized as hypoechogenic areas cranio-posterior to the submandibular glands. • The main duct originates from the deep portion of the gland and runs in an ascending way in fom • The main duct can be differentiated from the lingual vessels by color Doppler.
  46. 46. • Inflammatory diseases : • Acute sialadenitis : • Sonographically, the glands are enlarged with a more rounded shape, with a convex lateral surface and a hypoechoic structure • ColorDoppler – hyperemia • 50% cases , sialolith leads to sialadenitis, sonography helps in excluding obstruction) • Helps in identifying liquefaction • In case of abscess – puncturing US guidance
  47. 47. • Chronic sialadenitis : • Sonographic changes are less prominent than acute disease • Ductal ectasia can be seen • Sialography is superior to sonography in visualization of ductal chronic inflammatory obstructions • Post Radiation : gland is inhomogeneous, hypoechogenic • chronic fibrotic form • Diminished Vascularizationof the gland is diminished
  48. 48. • In children chronic recurrent cystic sialadenitis is a typical form of chronic inflammation • Multiple hypoechoic, cystoid areas in the parotid glands are visualized • These are caused by peripheral ductal ectasias and chronic lymphatic infiltrations
  49. 49. • Sjogrens syndrome : all major salivary glands are involved • Acute stage : glands are in homogenous due to inflammation . Hypervascularisation seen • Enlarged, hypoechoic transformations are seen • Long standing : glands are usually small, hypoechoic • Glands are difficult to delineate. • Fibrotic changes, diminished vascularity (If hypoechogenic lesions > 2cms – biopsy)
  50. 50. Sjogrens syndrome Multiple rounded, hypoechoic areas with relatively normal parenchyme
  51. 51. Sialoliths : • Calculi have a typical appearance - bright curvilinear echo complexes with posterior shadowing Calculi in distal part of left sub mandibular gland (8mm) Accuracy of US in detecting calculi – 90% Helps in differentiating calculi from calcified nodes, phleboliths in veins
  52. 52. Salivary gland tumors : Pleomorphic adenoma: tumor is well circumscribed usually shows a homogeneous hypoechogenicity A sharp, lobulated margin is regarded as typical
  53. 53. • Warthins tumor/ cystadenolymphoma : • Warthin’s tumors are sharply bordered masses. • On sonograms the lesion is usually more inhomogeneous than the pleomorphic adenoma • Hypoechoic with Multiple cystic lesions
  54. 54. • Muco epidermoid carcinoma: low grade :< 2 cm diameter - homogeneous structure with smooth borders • Incorrectly regarded as benign lesions by imaging • High grade : larger lesions, irregular borders and a typical heterogeneous echo pattern. Frequently irregular necrosis is found. • Infiltrations to base of skull, parapharyngeal.s, mandible – not detected
  55. 55. • In malignant tumors , color Doppler usually present a higher degree of vascularization compared with the normal parenchyma or with benign tumors • High systolic values & abnormal pattern of tumors vessels are suspicious for malignancy even when gray-scale imaging suggests a benign lesion
  56. 56. Limitations of sonography in salivary gland tumors • Deeply situated tumors • Some tumors cannot be delineate completely by sonography • extremely sensitive , but specificity – low • Difficult to differentiate tumors from inflammatory lesions. “Gritzmann G. sonography of salivary glands. Eur radiol. 2003.”
  57. 57. Maxillo Facial Vascular Anomalies Hemangiomas • usually poorly defined solid masses • show different echogenicity & vascularization – acc to stage • Pulse Doppler indicates peak systolic flow of up to 90 cm/s. • The diastolic flow is pronounced with spectral broadening and a low resistive index (RI: 0.4–0.7)
  58. 58. Low flow VENOUS VM: • hypoechoic, heterogeneous appearance • with multiple anechoic sinusoidal spaces • Usually characterized by compressible ducts by the US probe • Venous flow on spectral analysis. • Phleboliths may be present within the lesions. • hyperechoic foci with posterior acoustic shadowing
  59. 59. VENOUS MALFORMATION
  60. 60. • Lymphatic malformations : • Macrocystic - large, anechoic cavity separated by septa at US • Microcystic - consists of multiple microscopic cavities • appear hyperechoic. • Usually both are avascular, except for the septa, • A mixed type of vascular flow both venous and arterial sometimes may be depicted
  61. 61. High flow Arterial / AV malformations : • A mass composed entirely of vascular spaces with aberrant arterial and venous vessels within the mass.
  62. 62. CAROTID DOPPLER • Carotid arteries can become narrowed due to atherosclerosis (furring up) or other causes, and this can lead to transient ischemic attack (mini-stroke) or stroke. • The carotid doppler test can help to determine stroke risk and the need for preventive measures
  63. 63. Muscles of mastication • Wilson IR (1985) HR USG - examine masseter muscle • Normal masseter – relatively smooth internal texture of moderate echogenicity • Muscle is clearly demarcated from more superficial tissues & is seen to abut directly against mandibular ramus. • US is capable of providing information regarding muscle pathologies by depicting structural alterations
  64. 64. • Healthy masseter muscles have a heterogeneous speckled appearance in cross-section on US scan because of the irregular connective tissue bundles that randomly permeate their structure (Kiliaridis et al. 1995). • Hyperechoic bands - internal fascia, are referred to as septa (Bakke et al. 1992). • These bands diminish or disappear with inflammation; hence, this is an important structural index of masseteric infection
  65. 65. • Temporal muscle : • Thin hypoechogenic band lying adjacent to the medial relations of the temporal fossa • The bony landmark is identified as a hyperdense line
  66. 66. • MP , LP – not superficial muscles • Other muscles of the head and neck : • Digastrics • Sternocleidomastoid • Trapezius • lip muscle • “Serra MD. The use of ultrasound in the investigation of the muscles of mastication. Ultrasound in Medicine and Biology. 2008;34:1875-1885”
  67. 67. • Accurate and reliable imaging technique for measuring the thickness and cross sectional area of the masticatory muscles , facial & neck muscles in vivo • Precision analysis of muscle shape • CD USG - demonstrating the arteries in and around the muscle • Evaluate pathological changes in the muscles and arteries
  68. 68. TMJ • DISK DISPLACEMENTS • OSTEOARTHROSIS • JOINT EFFUSION
  69. 69. Lymphnodes • Normal lymphnodes are difficult to detect because of their high echogenicity, which is similar to that of the surrounding fatty tissue. • In acute, nonspecific lymphadenitis the lymphnodes are painful and markedly enlarged. • display a hypoechoic area. • The hilus of the lymphnode is not always apparent.
  70. 70.  Cervical lymphnode metastases in H&N - SCC (80%)  US findings: enlargement with a round to spherical shape, hypoechogenic, in homogenously echogenic, with loss of hilar definition.  Common findings of metastases from SCC are extranodal spread and central necrosis together with liquid areas in the lymphnode.  INCREASED VASCULARITY
  71. 71.  The round to spherical shape of the nodes is the most important criteria in the diagnosis of metastatic lymphnode disease.
  72. 72. • Size, Shape • Cortical thickness, CAPSULAR THICKNESS • Loss of Hilar echogenicity, • Hilar displacement • Echogenicity of node • Necrosis • Extracapsular spread • Color flow • Number • Calcification
  73. 73. • SIZE: short axis > 1cm • size alone should not be considered • Shape : Benign nodes are elongated and fusiform in shape • Malignant nodes have more transverse diameter (more rounded in shape • Cortical thickness – uniform in benign node • Increased in malignancy
  74. 74. hilum • A normal benign lymphnode is an elliptical structure with an outer hypoechoic cortex and a central echogenic hilus - a sign of benignity. Hilar compression / displacement is a sign of malignancy
  75. 75. hilum • Diffuse hypoechogenicity of the nodes – characteristic feature of lymphomas • If a node has fluid like appearance i.e uniformly hypo- echoic with acoustic enhancement (pseudo cystic appearance)
  76. 76.  Presence of necrosis in a node is strong sign of malignancy
  77. 77.  Extracpsular spread can be seen clearly in the ultrasound.
  78. 78. Malignant nodes shows features like 1. Displacement of vessels 2. Aberrant vessels 3. Focal absence of perfusion 4. Subscapular vessels 5. More peripheral than central vascularity
  79. 79.  Presence of cluster of nodes in a draining region from a primary tumor is regarded as a sign of malignancy
  80. 80.  Presence of punctate areas of calcifications in a node has a possibility of metastases from papillary carcinoma of thyroid  Bright echogenic flecks can be seen in metastatic nodes
  81. 81. Dental scanning • Dental scanning. Most solids, including enamel and dentin, can be penetrated by ultrasound, and it is possible to detect caries and cracks • Due to the irregular tooth anatomy, some errors were evident in the US images , as US hits sharp or undulated surfaces, it is usually distorted upon reflection and transmission leading to errors
  82. 82. INTERVENTIONAL USG US GUIDED FNAC • Used for abscess, salivary gland lesions, lymphnodes • The usually used outer diameter of the needle is 1.2 mm. • Can be performed statically / real time • Advantage : With US guidance it is possible to monitor the pass of the needle in real time. • Avoid puncturing of necrotic areas • laceration of the great cervical vessels
  83. 83. ADVANTAGES • For soft-tissue imaging, ultrasound is superior to conventional radiographs • Best modality for near field imaging • US provides information about size, localization, echogenicity, margins and tendency of the lesion to invade the surrounding structure • It can also provide a clearer definition and spatial resolution of the cutaneous, muscular, and mucosal layers, using its HR sonographic equipment
  84. 84. • Relatively inexpensive • Non invasive, non ionising radiation is used • Easily reproducible • Short scan time ( compared to MRI) • Equipment can be easily handled & transported • Children & mentally challenged
  85. 85. BIO EFFECTS • There are no confirmed biological effects on patients or instrument operators caused by exposures from present diagnostic ultrasound “American Institute of ultrasound in Medicine medical ultrasound safety”. American Institute of Ultrasound in Medicine; 2009.
  86. 86. DISADVANTAGES • Deeper structures visualised with less accuracy • Operator dependent • Sound beam beams cannot penetrate thick bone • Sound beams are scattered by gas
  87. 87. CONCLUSION • Ultrasound imaging in dentistry has been increasingly developed and studied in recent years and it seems that this technology will gain even more space in dental practices.
  88. 88. References • Shriki. Ultrasound physics. Crit Care Clin .2014; 30.1–24 • Rumack . Diagnostic ultrasound. Volume 1. 4th edition. Mosby: elsevier. 2011. chapter 1: physics of ultrasound • Goel S et.al. Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions. Indian J Radiol Imaging. 2011;21:279-83. • Gaimari G et.al. Color-Doppler Ultrasound in the Diagnosis of Oral Vascular Anomalies. North American Journal of Medical Sciences | January 2014
  89. 89. References • Marotti j . Recent advances of ultrasound imaging in dentistry - a review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol 2013
  90. 90. Thank you !!!

Notas del editor

  • Pressure wave producing alt compressions & rare
  • or f = T × sec–1.
  • Amplitude – size of wave………distance between max value to average value
  • Brightness display mode - gray scale imaging:
    Blacks, grays and whites assigned according to density and penetration/absorption.
    Denser/less penetration = bright gray/white; air Tissue/organs = gray Fluid = black; blood, ascites, bile
  • This combination of B-mode and doppler system allows the doppler beam to be accurately at any particular blood vessel.
  • Doppler frequency spectrum………The operator can adjust the position and size of the sample volume from which the returned Doppler information is obtained
  • Pyo.granuloma – poorly defined , hypoechoic
  • Journal of Oral Science.2010; 52:411-416
  • Us was initially used for scleroderma pts…collagen bundles appear hyperechoic…………
  • Us was initially used for scleroderma pts…collagen bundles appear hyperechoic…………
  • Due to their superficial position, the parotid, the submandibular,and the sublingual glands can be imaged with high-resolution
    Transducers.
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Sucking a lemon stick usually induces salivary gland stimulation. The normal reaction caused by lemon sticks is a significant elevation of the arterial blood flow. Usually, the maximum systolic flow velocity is doubled.
  • The accuracy of sonography in assessment of sialolithiasis is approximately 90% [28]. It is possible to differentiate calcified lymph nodes and phleboliths in facial veins.
  • In a diffuse pathological parenchyma it can be impossible to diagnose small tumors. This might be the case in Sjögren’s syndrome and malignant lymphoma.
  • VENOUS MALFORMATION OF CHEEK………..SPECTRAL CURVE SHOWING VENOUS FLOW…..HYPOECHOIC LESION WITH MULTIPLE ANECHOIC AREAS….
  • whereas the course of the temporal muscle is demonstrated by clenching
  • Variables, such as ,,,,,,,,,,,,,, maintain a slight interocclusal contact, clench or
    maintain a physiologic rest position (Kiliaridis and
    Kälebo 1991; Raadsheer et al. 1994).
  • Due to the superficial position of the major salivary glands, most parts are accessible by high-resolution
    transducers. Only a little portion of the parotid gland may be hidden by the acoustic shadow of the mandible
  • Static – insertion site, angle, depth are identified. Probe is laid aside before procedure
    Real time – both are performed simultaneously
  • At high levels of exposure, ultrasound waves can damage tissues, in addition to having teratogenic effects, due to heat, and acoustic cavitation. However, within the diagnostic range at low intensities and pressure levels, the probability for heating beyond the normal physiological range, or cavitation in the absence of gas bubbles is very low

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