Adelabu Short Notes

7/27/2019 Adelabu Short Notes

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Write short notes on the

following: Blow-out fracture

Ossifying fibroma

Microcolon

Salter-Harris fracture

Technique of radioisotope scanning of

pulmonary embolism


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BLOW-OUT FRACTURE

Introduction

Aetiology

Incidence

Types

Clinical features

Imaging modalities

Complications


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INTRODUCTION

Blow-out fracture is defined as the fracture ofthe orbital wall with increase in intraorbital

pressure and soft tissue herniation.

It is usually the result of a direct blow to the

orbit. This results in a sudden increase in the

intraorbital pressure which in turn

causes decompression by fracture of one or

more of the bounding walls of the orbit.

Pure blowout fractures usually occurs in the

weakest parts where the wall is thin i.e the

floor, the medial wall or, occasionally, the roof.


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The orbit is a four-sided pyramidal spaceformed by seven bones

Lateral wall: zygoma, greater wing of sphenoid

Superior wall (Roof): orbital plate of the frontalbone, lesser wing of the sphenoid

Medial wall: ethmoid, lacrimal, maxilla and

sphenoid bones. There is a paper-thin bone,

lamina papyracea, between the orbit and theethmoids

Inferior wall (Floor): maxilla, zygoma, palatine


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BONY

ORBIT


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AETIOLOGY

Direct orbital blunt injury e.g via fists, elbows

Sports injury e.g via impact of squash ball,

baseball, tennis ball etc., all of which have

diameters greater than the orbital rim

Motor vehicle accidents

Facial trauma

INCIDENCEThe commonest group of patients are young men.

This is because blow-out fracture is usually due to

trauma, often of sporting origin.


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TYPES OF BLOW-OUT

FRACTURE Inferior blow-out fracture: It is the most common.

There is prolapse of orbital fat ( inferior rectus

muscle) into the maxillary sinus. In approximately

50% of cases, it is associated with fractures of the

medial wall Medial blow-out fracture: It is the second most

common type, occurring through the lamina

papyracea. Orbital fat and the medial rectus

muscle may prolapse into the ethmoid air cells. Superior blow-out fracture: Uncommon. Fractures

may involve the frontal sinus and/or the anterior

cranial fossa

Lateral blow-out fracture: It is rare and associatedwith significant craniofacial injuries


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CLINICAL FEATURES

Pain

Periorbital swelling

Temporary or permanent loss of vision

Limitation of range of ocular motion Subconjunctival haemorrhage

Facial asymmetry

Diplopia due to extra-ocular muscleentrapment


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IMAGING MODALITIES

Plain radiography

CT scan

MRI

Ultrasound

Angiography


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PLAIN RADIOGRAPHY

Views include OM, OF, lateral

Occipitomental (OM) view is the most suitable to assess

inferior orbital wall fractures. This may reveal discontinuity

within the orbital floor, air-fluid level or soft tissue density

within the maxillary sinus, a polypoid mass hanging from the

floor into the maxillary antrum (tear-drop sign). This polypoidmass consists of herniated orbital contents, periorbital fat and

inferior rectus muscle.

Occipitofrontal (OF) view better assesses medial orbital wall

fracture. Penetration of air from the ethmoidal sinus is seen

as lucency in the orbit (Orbital emphysema). Fluid may bealso seen in the ethmoidal sinus


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Plain skull radiograph (OM view) showing a mass projectingfrom the left orbital floor into the left maxillary sinus


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CT SCAN

Due to its good bony resolution and multi-slice properties, CTgives better localisation of fracture site by clearly defining

bone fragments, air and foreign body.

A hypodense discontinuity is seen within the hyperdense

orbital wall.

Associated findings include: presence of intra-orbital

haemorrhage, globe injury/rupture, extraocular muscle

entrapment and prolapse of orbital fat

CT may also reveal bleeding into the sinus, which, depending

on the duration, can be hyperdense (acute), isodense (sub-

acute) or hypodense (chronic)


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Coronal cranial CT image showing fracture of the right inferior

orbital wall with herniation of orbital contents into the right maxillary

sinus


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Coronal cranial CT image showing fractures of the left inferior

and medial orbital walls


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Cranial CT image (saggital reformat) demonstrating fracture of

the left inferior orbital wall with associated inferior rectus muscle

entrapment


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MRI

MRI gives excellent soft tissue resolution andmultiplanar images of the orbits.

Prolapsed orbital fat appears hyperintense on both

T1 and T2 sequences

The signal intensity of any associatedhaemorrhage varies depending on the duration of

the bleed


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T1-weighted coronal cranial MR image showing inferior

herniation of the right orbital fat


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ULTRASOUND This employs the use of a high-frequency ultrasonic

transducer to assess for possible complications of orbitalcontents

Vitreous haemorrhage is seen as internal echoes within the

posterior segment.

Retinal or choroid detachment is seen as a V-shaped

echogenicity in the posterior part of the eye .

A foreign body within the orbit is echogenic with/without

posterior acoustic shadow

ANGIOGRAPHY This includes conventional angiography, CTA or MRA

Useful in the assessment of the ophthalmic artery


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COMPLICATIONS

Subluxation/dislocation/rupture of the lens

Vitreous haemorrhage

Retinal or choroid detachment


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OSSIFYING FIBROMA

Introduction

Incidence

Clinical features

Imaging modalities

Radiological features

Complications

Differentials


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INTRODUCTION

Ossifying fibroma is a benign slow-growing centralbone tumour composed of bone that develops

within fibrous connective tissue.

It is also known as Osteofibrous Dysplasia (OFD)

or Jaffe-Campanacci Syndrome. The pathology comprises maturing cellular fibrous

spindle cells with osteoblastic activity producing

many calcific cartilaginous and bone densities


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INCIDENCE

It occurs commonly in the 2nd to 4th decade of life

M < F

Common locations include:

Lower extremity:

Tibia: seen in 90% of cases. There is

predilection for the anterior tibial cortex

Femur: Usually occurs in the diaphysis

Jaw: maxilla and mandible. Also known ascemento-ossifying fibromas

Frontal bone, ethmoid bone etc


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CLINICAL FEATURES

Pain (though usually painless)

Swelling

Facial asymmetry due to bone

expansion

Tooth displacement


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IMAGING MODALITIES

Plain radiography

CT scan

MRI

Radionuclide imaging


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PLAIN RADIOGRAPHY

It is seen as a well circumscribedlesion surrounded by a thin line of

lucency (fibrous capsule), which is in

turn surrounded by thin sclerotic rim ofreactive bone (osteoblastic rimming).

May present as eccentric ground-

glass lesion, resembling fibrousdysplasia

There is moderate expansion of intact

cortex


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CT SCAN

CT demonstrates a well circumscribedhomogeneous lesion with evidence of

intracortical hypodensity and

characteristic hyperdense band(osteoblastic rimming)


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Axial CT of the lower jaw (bone window) showing a circular

partially calcified lesion within the mandible. There are

internal ground-glass calcifications


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MRI

The lesion is hypointense on T1 and (with typicalcontrast enhancement) and iso- to hyperintense on

T2

RADIONUCLIDE IMAGING It shows intense focal uptake on 99mTc bone scan.


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COMPLICATIONS

Pathological fracture Limb bowing

Recurrence

TREATMENT/PROGNOSIS Ossifying fibroma tends to regress over time.

For locally aggressive lesions, surgical resection is

often curative


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DIFFERENTIALS

Fibrous dysplasia: Has no osteoblastic rimming Adamantinoma: May share a common origin with

ossifying fibroma. It is distinguished from ossifying

fibroma by presence of soft tissue extension,

intramedullary extension and periosteal reaction. Osteoid osteoma: Consists of 3 concentric parts

nidus, fibrovascular rim and surrounding reactive

sclerosis


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MICROCOLON

Definition

Aetiology

Clinical presentation

Imaging modalities

Radiological features


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DEFINITION

Microcolon is a radiological finding of small-calibre unused colon, seen in the neonate

on radiographic contrast enema

It signifies intestinal obstruction above the

colon and it is probably caused in utero by

lack of appropriate distension of the colon

with intramural content

There are no absolute standards for themeasurement of this condition.


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AETIOLOGY

Mnemonic: MI MCA

Meconium ileus/meconium peritonitis

Ileal/jejunal atresia

Megacystis-microcolon-hypoperistalsis

syndrome

Colonic atresia

Aganglionosis (Hirschsprungs

disease)


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CLINICAL PRESENTATION Abdominal distension

Bilous vomiting

Failure to pass meconium within 48hours

IMAGING MODALITIES Plain radiography

Contrast enema Ultrasound

CT scan

MCUG


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MECONIUM ILEUS

This is the obstruction of the small bowel in theterminal ileum from impacted meconium

It manifests within 48 hours of birth. Meconium is

normally evacuated within first 6 hours

Majority of infants with meconium ileus prove tohave cystic fibrosis. Approximately 20% of infants

with cystic fibrosis present with meconium ileus at

birth. It may also be seen with pancreatic atresia or

stenosis of the pancreatic duct


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MECONIUM ILEUS (CONTD)Plain Radiography:

Non-specific. May show dilated small bowel loops without air-fluid levels (fluid not present)

Bubbly/frothy appearance of the distended intestinal loops

Soap bubble appearance in right lower quadrant due to

admixture of gas with meconium

Contrast Enema

Multiple round/oval filling defects in distal ileum & colon

Functional microcolon (unused colon in antenatal obstruction)

Obstetric ultrasound

Echogenic bowel which can be dilated and thick-walled

Polyhydramnios

Fetal ascites

Intra-abdominal cysts


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MECONIUM ILEUS CONTD)


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MECONIUM PERITONITIS

This refers to sterile chemical peritonitis secondaryto perforation of bowel proximal to complete

obstruction that seals in utero due to inflammatory

response

Causes as for microcolon Plain radiography: intra-abdominal calcifications

Contrast enema: separation of bowel loops by fluid;

microcolon

Ultrasound: highly echogenic material throughoutthe abdomen in between bowel loops (snowstorm

appearance)

Obstetric ultrasound: as for meconium ileus


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MECONIUM PERITONITIS (CONTD)


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JEJUNAL/ILEAL ATRESIA

This is a congenital anomaly characterized by closure of thejejunum or ileum.

The aetiology is thought to be from an intrauterine ischaemic

injury to the developing gut

May be associated with malrotation, volvulus, gastroschisis,

omphalocele

Plain radiography: Triple bubble appearance (double bubble

of duodenal atresia + third bubble due to air in the proximal

jejunum). Multiple dilated small bowel loops proximal to the

atresia

Contrast enema: Typically shows microcolon

Obstetric ultrasound: Dilated proximal bowel loops, often >

7mm


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JEJUNAL/ILEAL ATRESIA (CONTD)


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COLONIC ATRESIA

Less common than jejunal/ileal atresia

Plain radiography: massive dilatation of colon

proximal to obstruction. Mottled pattern of gas +

feces proximal to point of atresia

Contrast enema: Functional microcolon. There may

be obstruction to retrograde flow of contrast

Ultrasound: dilated echogenic distal small bowel +

proximal colon (from retained meconium)


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COLONIC ATRESIA (CONTD)


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MEGACYSTIS-MICROCOLON-

HYPOPERISTALSIS SYNDROME

Also known as Berdon syndrome. M:F is 1:7 This is a functional obstruction of bladder + colon

characterized by enlarged urinary bladder, small colon and

markedly enlarged hydronephrotic kidneys with little

remaining parenchyma

The prognosis is lethal in most cases

Obstetric ultrasound: female sex; normal amount of amniotic

fluid in spite of dilated bladder; bilateral megaloureters

hydronephrosis

Contrast enema: microcolon with narrow rectum + sigmoid;

malrotation or foreshortening of small bowel

MCUG: Distended unobstructed bladder with poor/absent

muscular function


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HIRSCHSPRUNGS DISEASE

This is caused by absence of parasympatheticganglia in muscle & submucosal layers due to an

arrest of craniocaudal migration of neuroblasts

along the vagal trunks

Microcolon is seen in less than one-quarter ofpatients with total colonic Hirschsprungs disease

Plain radiography: multiple dilatation of bowel loops

Contrast enema: rectosigmoid calibre ratio less

than one, microcolon, delayed/disorderedevacuation of contrast from the colon, bowel

shortening


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HIRSCHSPRUNGS DISEASE

SALTER HARRIS


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SALTER-HARRIS

FRACTURE IntroductionAetiology

Incidence

Types

Clinical features

Imaging modalities

Complications


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AETIOLOGY

Sports injuries (one-third of cases) Child abuse

Injury from extreme cold (e.g frostbite)

Neurological disorders that result in sensory deficit or

muscular imbalance

Metabolic diseases e.g CRF, hormone disorders etc

INCIDENCE

Peak age is 12years M:F = 2:1

Upper extremity > Lower extremity (typically the distal radius)

Mechanism: 80% shearing force; 20% compression


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ANATOMY

The epiphyseal growth plate (where cartilagedevelops into bone) has four stages:

germinal/resting zone, proliferative zone,

hypertrophy zone, ossification zone.

Hypertrophy zone is weakest and therefore isdamaged by shearing forces that extend from there

into epiphysis or metaphysis during Salter Harris

fractures.

Major blood supply to growth plate and its germinallayer is from epiphysis.

Damage to the blood supply causes healing

problems for Salter Harris fractures


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ANATOMY


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TYPES

Salter-Harris Fractures are categorized by the location of thefracture in one or more of the physis (epiphyseal plate),

epiphysis, and metaphysis.


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TYPE I (Slipped physis)

There is slip of epiphysis due to shearing forceseparating epiphysis from physis. The surrounding

bone is not involved.

Line of cleavage is confined to the physis

Seen in 6 8.5% of cases There is widening of the growth plate as well as

displacement of the epiphyseal ossification centre

Commonly seen in the phalanges and distal radius.

Slipped capital femoral epiphysis is a type I SHF Prognosis is favourable, irrespective of the location

It is treated by simple closed reduction and

immobilization


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TYPE I (CONTD)
http://www.emedicine.com/radio/images/336139-412956-1355.jpg


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Salter Harris type I of distal radius

SLIPPED CAPITAL FEMORAL


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SLIPPED CAPITAL FEMORAL

EPIPHYSIS


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TYPE II (Above physis)

Shearing force splits the epiphyseal plate. The line of fracture passes across the epiphyseal

plate and extends through the metaphysis. This

separates a triangular metaphyseal fragment

known as Thurston Holland fragment (Corner sign) This type is the most common, seen in 73 75% of

cases.

Commonly seen in distal radius (33 50%), distal

tibia & fibula, phalanges. It is treated by closed reduction and immobilization

The prognosis is good and complications are

uncommon. However, it may result in minimal

shortening


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TYPE II (CONTD)

Salter Harris type II of the distal radius There is also a


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Salter Harris type II of the distal radius. There is also a

fracture of the distal ulna


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TYPE III (Lower than physis)

This is an intraarticular fracture, often occurringafter partial closure of physis

The line of fracture is vertically/obliquely through

the epiphysis and extending horizontally to

periphery of physis. Seen in 6.5 8% of cases.

Commonly seen in distal tibia, distal phalanx, rarely

distal femur

The prognosis is fair. This type damages theproliferative and resting zones of the growth plate

with fracture extending to articular surface of the

bone.

Treatment often requires surgery.


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TYPE III (CONTD)

Salter Harris type III of distal


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Salter Harris type III of distal

tibia


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TYPE IV (Through physis)

This is also an intraarticular fracture. The line of fracture passes directly through the

metaphysis, epiphyseal plate and through the

epiphysis

Seen in 10 12% of cases. Commonly seen in lateral condyle of humerus and

distal tibia

The prognosis is guarded. This type interferes with

the germinal layer and can cause premature focalfusion of involved bone thereby causing limb

shortening.

Treatment requires surgery in order to properly

realign the joint surface


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TYPE IV (CONTD)

Salter Harris t pe IV of the distal


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Salter Harris type IV of the distal

tibia
http://www.learningradiology.com/caseofweek/caseoftheweekpix2007-1/cow241arr.jpg


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TYPE V (Rammed physis)

This type is due to crush injury with injury to thevascular supply.

Crush injury does not displace the growth plate but

damages it by direct compression.

Commonly found in distal femur, proximal tibia,distal tibia

Seen in


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TYPE V (CONTD)

Salter Harris type V of right distal radius. There is a "sclerotic" band


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across the distal metaphysis of the right radius where the impaction has

taken place, and a small area of bulging on the ulnar aspect of the distal

radius


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CLINICAL FEATURES

Joint pain Joint swelling

Limited range of motion in joint

Point tenderness over the growth plate

IMAGING MODALITIES Plain radiography

CT scan MRI

Ultrasound


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PLAIN RADIOGRAPHY

This is the sole imaging method required in themajority of epiphyseal injuries.

AP and lateral views are usually required.

Comparison study of contralateral limb is also

done. The epiphyseal plate is originally radiolucent. So,

its fractures are not directly evident on plain x-rays.

Fractures through the bones appear as linear

radiolucency (area of discontinuity) within the bony

outlines


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CT SCAN

CT with its multiplanar reconstruction is required todemonstrate improved fracture anatomy for

potential surgical intervention

The fracture appears as linear hypodense area

within the hyperdense bony outline

MRI SCANThe fracture appears as focal hyperintense linear

area (line of cleavage) within a hypointense physis

on T1 and T2 images

CT scan of the right knee (volume rendering images)


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C sca o e g ee ( o u e e de g ages)

showing Salter-Harris type 2 supracondylar fracture of the

right femur


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ULTRASOUND

It is useful as ancillary imagingmodality in assessing joint effusion,

ligamental rupture, vascular injury etc


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COMPLICATIONS

Progressive angular deformity Limb length discrepancy from growth arrest

Articular incongruity from disruption of articular

surface

Bone infarction in metaphysis/epiphysis

TECHNIQUE OF RADIOISOTOPE


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SCANNING OF PULMONARY

EMBOLISM

Definition

Contraindications

Radiopharmaceuticals

Equipment

Patient preparation

Technique

Aftercare

Complications

DEFINITION


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DEFINITION

Radioisotope scanning of pulmonaryembolism is otherwise known as ventilation-

perfusion scintigraphy

It is a non-invasive technique for the

assessment of the distribution of pulmonary

blood flow and alveolar ventilation.


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RADIOPHARMACEUTICALS


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RADIOPHARMACEUTICALS

Perfusion imaging This method demonstrates the distribution of lung

perfusion using a 99mTc (Technetium)-labelled

albumin tracer in the form of small particles. Adult

dose is about 40 000 - 200 000 particles The particles are of such a size (about 10 40m

in diameter) that they will be trapped in the

precapillary arterioles of the lung in their first

passage after intravenous injection. The injectedparticles occlude less than 0.5% of the vascular

bed.

After trapping in the lung, the particles are removed

by the reticuloendothelial system over several


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RADIOPHARMACEUTICALS (CONTD)

Ventilation imaging

81mKr (Krypton) gas: Optimal imaging agent. It

has a short T of 13s and gamma-energy of

190keV. Simultaneous dual isotope

ventilation and perfusion imaging is possiblebecause of different energy to 99mTc. However,

it is expensive and not readily available.

99mTc-Technegas: Similar diagnostic efficacy

to krypton. Simultaneous imaging notpossible. It is expensive.


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RADIOPHARMACEUTICALS (CONTD)

Ventilation imaging

99mTc-DTPA: Cheap and readily available.

Simultaneous imaging is not possible. Less

suitable in patients with COPD or chronic

asthma due to likelihood of clumping ofaerosol particles

133Xe (Xenon) gas: It has a long T of

5.25days and a gamma energy of 81keV.

Ventilation must precede perfusion studybecause low gamma-energy would be

swamped by scatter from 99mTc. Its images

are of poor quality.

Q


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EQUIPMENT

Gamma-camera Low-energy general purpose collimator

Gas-dispensing system and breathing circuit for

ventilation

PATIENT PREPARATION For ventilation, familiarization with breathing

equipment

A current CXR is required to assist with

interpretation.

TECHNIQUE


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TECHNIQUE

Perfusion scintigraphy This method demonstrates the distribution of lung

perfusion using a 99mTc-labelled albumin tracer inthe form of small particles.

The tracer is given intravenously in the supine,

semi-recumbent or sitting position The syringe is shaken to prevent particles settling.

A slow IV injection is given directly into a vein overabout 10s. The patient must remain in position for

2-3mins while the particles become fixed in thelungs

Imaging may begin immediately, preferrably in thesitting position

TECHNIQUE (CONTD)


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TECHNIQUE (CONTD)

Ventilation Scintigraphy If81mKr gas is used, simultaneous Q/V imaging

can be performed either by dual isotope

acquisition or swapping energy windows at each

patient position. The patient is positioned to obtain identical views

to the perfusion images and asked to breathe

normally through the mouthpiece

The air supply attached to the generator is turnedon and imaging commenced.

TECHNIQUE (CONTD)


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TECHNIQUE (CONTD)

Ventilation Scintigraphy

If99mTc-DTPA is used, this imaging is performed before theperfusion study.

99mTc-DTPA is drawn into a 5ml syringe with 2ml air, theninjected into the nebulizer and flushed through with air

The patient is positioned sitting with their back to the camera

The air supply is turned on to deliver a rate of 10L/min and anose-clip is placed in the patient, who is asked to breathenormally through the mouthpiece

After reaching a sufficient count rate, the air supply is turnedoff. The patient continues to breathe through the

mouthpiece for a further 15s The nose-clip is removed and the patient is given a mouth

wash, then imaging is commenced.

TECHNIQUE (CONTD)


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TECHNIQUE (CONTD)

The images taken include anterior, posterior, leftand right posterior obliques. These are preferred to

lateral views in order to avoid small defects in one

lung being obscured by counts shining through

from the opposite lung.

Characteristically, pulmonary embolism results in

severe reduction or total loss of perfusion to the

areas of lung supplied by the affected arteries,

while ventilation remains unchanged or shows only

a minor reduction.

AFTERCARE


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AFTERCARE

None

COMPLICATIONS Worsening of right heart failure in patients

with severe pulmonary hypertension

Risk of systemic embolisation in patientswith right-to-left cardiac shunt


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