[radio 250] lec 09 basic ultrasound (1).pdf

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RADIO 250: ICC in Radiology and Nuclear Medicine LEC 09: Basic Ultrasound

Exam 1 | Dr. Pauig| October 23, 2013

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I. PRINCIPLES OF ULTRASOUND

A. What is Ultrasonography • Use of sound waves beyond the audible frequency (>20,000 Hz)

for diagnostic purposes • Can be used for therapeutic purposes by using larger and

continuous dosages as in: o Generation of heat – treatment of low back pain and muscle

strains, promotion of tissue generation o Pulverization of kidney stones

B. Basic Physics

TRANSDUCER

• Probe holding a piezoelectric crystal that changes electrical current into sound waves and vice versa

• Generates the sound wave

SOUND WAVES • Are generated, reflected off tissues and “echo”

back • Then they are picked up by the transducer and

converted to electrical activity

• Image generated depends on the time it takes the sound waves to return to the transducer and the amplitude of the sound wave o Fat or bone is a reflective surface o Air or water does not reflect sound very well o Shorter the time, the nearer the body part is to the transducer. o Stronger amplitude, the better reflector is the body part such as

bone, fat, and calcification.

II. ULTRASOUND METHODS A. Pulse Echo

A MODE – Amplitude Modulation • Echoes are displayed in graphic form, such as in echocardiogram • Not used anymore

Figure 1. A-‐mode trace. The A-‐mode is a trace indicating echo

intensity tissue with depth. In this example, there is a fluid space (6–10 cm) from which no echoes arise. Tissues superficial and deep to this produce echoes of varying intensities and there is a particularly strong echo from the skin (0–5 cm). The time gain compensation

(TGC) curve is also shown.

B MODE – Brigthness Modulation • Echoes are displayed as different intensities of brightness, giving a

2D cross sectional image (“picture”) • Can be static or dynamic (“real time”) o Static – med tech does the procedure then results are

interpreted by doctor

o Dynamic – doctor does the procedure and results are interpreted right there

M MODE – Motion Mode • First ultrasound modality to record display moving echoes from

the heart. Good to get heart tone o Thus the motion could be interpreted in terms of myocardial

and valvular function • Combination of A and B modes • Determines velocity of a specific organ

Figure 2. M-‐mode trace. The echo intensity is displayed as

brightness and the trace is swept across the screen so that the x-‐axis represents time. This is an M-‐mode echocardiogram showing the rapid movement of the mitral valve apparatus within the left ventricle (LV), with thicker proximal and distal moving bands

representing the myocardium. RV = right ventricle.

B. Doppler Method • For vascular ultrasound • Sound waves bounced off of different objects have different

frequencies à use of these frequencies to check flow through arteries and vein

• With Doppler ultrasound, these different frequencies are transformed into audible sounds, of different frequency.

• The different frequencies can also be mapped to give a visual representation as well as an audible one

• Can assess patency of arterial grafts, obstruction to flow by thrombi or atherosclerosis

• Arterial flow can often be heard in cases where it cannot be palpated

• For moving objects, the velocity of the sound waves will depend on the velocity of the moving object

• Renal artery stenosis is diagnosed when velocity is more than 300 m/s.

• Carotid artery stenosis if more than 100 m/s

III. Image Interpretation Sagittal View • Entering beam is along the long axis of the patient

OUTLINE I. Ultrasound Principles II. Ultrasound Methods III. Image Interpretation IV. Advantages and Disadvantages V. Applications

A. Abdomen

B. Obstetrics and Gynecology C. Thyroid D. Scrotum E. Breast and Musculoskeletal F. Doppler Imaging G. Interventional Procedures




Figure 3. Ultrasound, sagittal view

Axial View • Beam is along the transverse (short) axis

Figure 4. Ultrasound, axial view

B. Information Provided

• Evaluate the size, shape and parenchyma of solid organs • Categorize lesions into solid (usually malignant), cystic (usually

benign) or complex (mixed) • Determine vascular supply of organs or masses • Localize site for biopsy, aspiration or interventional procedures

IV. ADVANTAGES AND DISADVANTAGES

Advantages • Non-‐invasive, simple and inexpensive • No ionizing radiation • Diagnosis is made during the procedure, unlike in x-‐ray • Infinite number of sections, not limited to sagittal and axial views • Portable machine, handheld even

Disadvantages

• Operator dependent • Gives only a morphologic diagnosis, the size and shape, but not the function, e.g., kidney may appear normal but may have high creatinine already; same goes for liver

• Cannot penetrate air or bone so do only chest ultrasound if you’re suspecting pleural effusion and joint effusion, bursitis, etc. Bone tumors, marrow pathologies, don’t use ultrasound

• Requires good contact of transducer with skin: this is a problem for burn patients especially if with bandage and infection

V. APPLICATIONS

• Abdominal • Obstretics and Gynecology • Small organs:breast, thyroid, scrotal, musculoskeletal • Neurosonology for pediatric patients, if fontanels are still open;

for adults can also look at Circle of Willis; not used to visualize brain parenchyma

• Vascular • Interventional procedures

A. Abdomen Liver • Describe the parenchyma Normal Appear homogenously grey Blood vessels are dark

Fatty liver (Steatosis) Appear bright (hyperechoic)

Liver Cirrhosis Small liver Heterogenous

Cystitic Lesion Hypo-‐ or anechoic (dark) with thin walls Posterior acoustic enhancement (PAE): since sound waves passes through fluid only, they are not as attenuated as passing through a normal liver parenchyma Abscess looks similar

Masses/ Modules Picture:liver metastasis of a colon carcinoma Also hypoechoic BUT NO PAE

Calcifications Picture: arrows point to a liver calcification secondary to a CMV infection Hyperechoic followed by hypoechoic portion

Pancreas




Figure 5. Pancreas

• Usually taken in axial view • Tadpole-‐shaped, with the spleen on the left • Hypoechoic relative to others • Organ is anterior to the splenic artery and portal vein (markers) • Any structure anterior to your splenic vein is the pancreas.

Spleen

Also homogenously gray May be compared with liver, but smaller Figure 5 (left). Normal spleen ultrasound.

Gallbladder and Biliary Tree • Normally, gallbladder is thinwalled. • If painful, gallbladder is edematous.

Calcification (Stones) • Picture: cholelithiasis with mobile gallstones

• Hyperechoic with shadow • Settle on the dependent portion

• Presence of stones but px is asymptomatic, gall bladder would have thin walls

• (+) stones & (+) symptoms (pain, etc), gall bladder would be thick walled

Crystals (e.g Cholesterolosis) • Picture: cholesterol crystals in the intrahepatic bile ducts in a patient after cholecystectomy

• Hyperechoic with comet-‐tail artifact

• Not seen on CT or MRI, only in UTZ

Polyps • Nodular structure, not

dependent on gravity • Wall-‐adherent,

hyperechoic with no shadow

Ascariasis • Calcified if dead

Cholecystitis • Wall thickening (gray)

Doppler • Uncolored tubular

structure above colored tubular structure (portal vein) is the common bile duct.

• To look for the common bile duct, look for the portal vein first. The portal vein is parallel to the common bile duct. It would be helpful to trace the bileduct to the pancreas since most pathologies are found in that location.

Gastrointestinal Tract • Ultrasound is usually not used for the gastrointestinal tract

because it is mostly air-‐filled structures

Figure 6. GI tract

1st figure: sagittal view; 2nd figure: axial view; 3rd figure: thickening of wall

Appendix




• A blind-‐ending non-‐compressible structure that does not exceed 6 mm in length

• If structure is very firm, more than 6 mm, and hypervascular/hyperemic (in doppler) à consider appendicitis

• Negative ultrasound result does not rule out appendicitis. • If appendix is retrocecal in location, it cannot be visualized in UTZ

Figure 7. Appendix

TOP: Normal (left) versus inflamed (right) appendix. BOTTOM: thickened appendix (you know because it is a dead end).

Only find it if it is inflamed

Kidney

NORM

AL KIDNEY

• Homogenous parenchyma with uniform contour

• Central echocomplex (corresponds to pelvocalices; only seen when dilated)

• Hypoechoic focus in the middle (medulla with collecting tubules) with grey in the periphery (cortex with glomeruli)

STAG

HORN

CAL

CULI

• Large calculi that takes the shape of the medulla

HYD

RONEP

HRO

SIS

• Distension and dilation of the renal pelvis and calyces

MED

ULLAR

Y NEP

HRO

CALCINOSIS

• Calcified renal medulla

• Seen in distal renal tubular acidosis, renal tuberculosis and medullary sponge kidney disease

RENAL

CYSTS

• Picture: multiple renal cysts in right kidney

END-‐STA

GE KIDNEY

• Hyperechoic parenchyma (significantly more echogenic than adjacent liver parenchyma)

• Differentiation of cortex from medulla, and even from the renal sinus, is lost

• Irregular kidney borders + small kidney size • Etiology: Infection, hypertensive nephropathy, diabetes

• There are normal variants of the kidney. Such are the Dromedory humps and hypertrophied column of Bertin

Ureter • Normally should not be distended • it can’t be seen in the UTZ if there are no pathologies • Calculi (stones) of the ureters are usually detected through UTZ

Figure 8. Ureteral Stones.

Image at Left is a stone in the ureterovesical junction Urinary Bladder • Normally should not be distended • If there is cystitis, the urinary bladder can have thick walls. • Hemorrhage in the urinary bladder will appear hyperechoic




NORM

AL BLA

DDER

• Appears hypoechoic with well-‐defined borders

BLAD

DER

TUMORS

• Picture: large bladder carcinoma with bladder wall invasion

STONES

• Picture: mobile bladder stones

• Hyperechoic with posterior shadowing

CYSTITIS

• Cystitis: irregular thickening of wall, balloon of foley catheter is seen at the right.

FOLEY CA

THETER

BAL

LOON

• Picture: balloon catheter placed in the vagina and not in the bladder

Prostate • Two views: transrectal (good view since few structures are in the

way) and transabdominal (bladder must be full) • Central (slightly hypoechoic) and peripheral (hyperechoic) gland

can be seen • Normal volume: 20 cc

NORM

AL PRO

STAT

E

• Picture: arrows point to each lobe of the prostate

BENIGN PRO

STAT

IC

ENLA

RGEM

ENT

• Usually located on the central zone

PROSTAT

IC CAR

CINOMA

• Picture: note hypoechoic nodule (arrow) located on the peripheral zone

CALCIFICAT

IONS

• Appear as hyperechoic foci usually from 4-‐7 mm in the inner gland of the prostate and also along the prostatic urethra

B. Obstetrics and Gynecology

Transabdominal vs. Transvaginal Ultrasound

Table 1. Comparison between transabdominal and transvaginal UTZ.

TRANSABDOMINAL TRANSVAGINAL • Distended urinary bladder • Low frequency transducer (up to 5)

• For visualizing the global picture

• Poor resolution

• Empty urinary bladder • High frequency transducer (up to 7.5)

• Limited range (8 to 10 cm away from probe only)

• Excellent resolution • Long axis and short axis orientation




Figure 9. Transabdomial VS Transvaginal

Figure 10. Transabdominal orientation

Figure 11. Transvaginal orientation

The Fetus • UTZ is useful for visualizing fetal organs (feet, genitals, face,

cranium, hands, etc.) • Fetal assessment for sex:

o Not easily detectable, can take up to 30 minutes o Turtle sign is for male, hamburger sign is for female

Figure 12. Early Intrauterine

Figure 13.

TOP: 19-‐week baby boy showing turtle sign on ultrasound. BOTTOM: 20-‐week baby girl showing hamburger sign on ultrasound.

C. Thyroid

• Very radiosensitive organ, hence best examined through UTZ

NORM

AL THYR

OID

• Picture: right lobe of thyroid relative to other organs

• Homogenously gray

• Hyperechoic when compared to muscle

• Normal size threshold: 5 cm

GRA

VES' DISEA

SE

• Picture: hyper-‐vascularized thyroid gland (thyroid inferno) on color Doppler

• Enlarged and relatively hypoechoic

• heterogenous parenchyma, >5cm, isthmus and AP diameter are measured




HAS

HIM

OTO

'S THYR

OIDITIS

• Enlarged and non-‐homogenous; hypervascular in its acute stage

• Hypoechoic compared to normal thyroid with lobulations inisde

BENIGN THYR

OID M

ASS

• Picture: hyperplastic adenomatous nodule with a slightly hyperechoic vascularized mass

THYR

OID CAR

CINOMA

• Picture: nonhomogeneous hypervascularized solid and partly cystic thyroid mass that proved to be extensive papillary carcinoma

COLLOID NODU

LE

• Picture: cystic changes in an adenomatous nodule (colloid nodule) in the right thyroid lobe

• Looks like sponge (multiple small internal cystic structures) • Does not warrant a biopsy

Thyroid Lesions: Benign vs. Malignant

PARAMETER BENIGN MALIGNANT

Height vs. width Wider than tall (usually ovoid) Taller than wide

Capsule Usually present Usually absent

Edge of mass Smooth, well-‐defined Poorly defined

Intra-‐lesional peripheral vascularity Absent Present

Calcifications Positioned peripherally (“egg-‐shell” configuration)

Located inside the mass

• Hyperechoic à benign • Hyperechoic + crystals à benign

• Cyst most likely benign • Thin rim calcification ath the PERIPHERY à benign

Figure 14. ????

• Colloid nodule: with internal reticulations, no calcifications • Ultrasound guided FNAB slide: Anything you can ultrasound, you

can biopsy

D. SCROTUM

NORM

AL TESTIS

• Ovoid, homogenously gray

• No calcifications or masses within

VARICO

COELE

• Picture: varicocoele with dilatated venous plexus and reflux during straining

• Looks like “bag of worms”

• Hypervascular with dilated vessels

• Can cause infertility

ORC

HITIS

• Picture: orchitis with a focal hypoechoic area with increased flow

• Whole testis enlarged, hypervascular, not homogenous




EPIDIDYM

ITIS W

ITH ABS

CESS

• Picture: arrow points to abscess below an inflamed epididymis

• Hyperemic wall

Spermatocoele vs. Epididymal Cysts • Cannot be distinguished via ultrasound

Figure 15. Epididymal cyst or spermatocele in the epididymal head. Testicular Tumors

PROBABILITY OF MALIGNANCY HIGH INTERMEDIATE LOW VERY LOW

Solid palpable Solid non-‐palpable

Simple cystic palpable

Simple cystic non-‐palpable

Complex cystic palpable

Complex cystic non-‐palpable

*Complex: presence of both solid and cystic parts

Microlithiasis and Seminoma • Microlithiasis: post-‐infection, hypoechoic with microcalcifications

à must follow-‐up for possible seminoma • Seminoma: hyperechoic, highly vascularized • Torsion: hypovascular • Infarct: avascular

Figure 16. Testicular

microlithiasis and a

seminoma with a vascularized hypoechoic

mass.

E. BREAST AND MUSCULOSKELETAL

Breast • UTZ usually for fibroadenomas o Flat ovoid masses with smooth well-‐defined borders o Solid nodule with PAE (an exception! Recall that solid masses in the GI tract do not have PAE)

o No need for biopsy, may regress normally

Figure 17. Fibroadenoma

with a hypoechoic slightly lobulated oval lesion with sharp margins.

Musculoskeletal

TENOSYNOVITIS

• Picture: tenosynovitis of the flexor digitorum tendons

• Abnormal fluid collection within synovium around covering of tendon

NEO

NAT

AL UTZ

• Picture: hemangioma with a hypechoic compressible highly vascularized lesion

• UTZ probe made to pass through fontanelles

F. CRANIAL • Assessed in neonates through the fontanelles. • Used just to rule out pathologies especially in preterms • UTZ can rule out intracranial hemorrhages.

Figure 18. Cranial UTZ

LEFT: Subarachnoid Hemorrhage: RIGHT: Hydrocephalus

G. DOPPLER IMAGING Standard Doppler Imaging • Flow direction and velocity must be shown on the color Doppler image by shifting and changing shade method

• Different colors are used to represent different frequencies and color gets lighter as the frequency increases o Color used can be changed by the technician




o Usual color spectrum: § Blood coming TOWARDS the probe appears blue § Blood going AWAY FROM the probe appears red § NOT red = artery, blue = vein!

• Shows direction of blood BUT is not sensitive to slow movements

Figure 19. Standard Doppler Imaging

Power Doppler Flow Imaging • Frame rate is too slow and cannot provide flow direction and velocity

• Sensitive to even slow movements • Does not assign direction • Any flowing blood is yellow.

Figure 20. Power Doppler Flow Imaging

Resistive index, acceleration index. Insert slide-‐ no pic L

H. INTERVENTIONAL PROCEDURES

Treatment Modalities Utilizing Ultrasound • Biopsy • Aspiration • Thoracentesis / Paracentesis • Percutaneous biliary drainage • Nephrostomy / Cystostomy • IV insertion / central venous lines

Ultrasound-‐Guided Procedures: Examples • Liver abscess aspiration: Abscess appears hypoechoic. Vascularity is only in the periphery. You see a collapsed wall after aspiration.

Figure 21. Liver abscess aspiration

• Prostate biopsy

Figure 22. Prostate Biopsy

• Paracentesis: evacuation of fluid within the cavity, avoid puncturing bowels

• Thoracentesis: evacuation of fluid within the pleural cavity; avoid puncturing diaphgram

END

[radio 250] lec 09 basic ultrasound (1).pdf

Documents

mode motion mode

mode trace

sound wave sound waves

sound wave o fat

o shorter

different frequencies

mode echocardiogram

o stronger amplitude