nuclear imaging, nephro emphasis

8/10/2019 Nuclear Imaging, nephro emphasis

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NUCLEAR IMAGING STUDIES OF

THE GUT

Dr. Loquiano

December 17, 2014

TigbaONE!

NUCLEAR MEDICINE

Medical specialty that uses SAFE, PAINLESS and

COST-EFFECTIVE techniques to both image the body

and treat disease.

A sensitive way to gather information that may

otherwise be unavailable, require surgery, or

necessitate more expensive and risky diagnostic

tests.

Body is imaged from the inside out

Radiotracers, in the form of radiopharmaceuticals,

administered internally (intravenous, inhalation or

orally)

*unlikeotherprocedures,itdoesnotneedtheuseof

dyessoyoudonthavetocheckkidneyfunctionslike

creatininelevelafteradministration.

Diagnostic inference is gained by recording the

distribution of radioactive materials in the body

Sequence of events - to understand nuclear med

procedures

Physics of radioactivity

Process of detecting radiation

Selection of appropriate radiopharmaceuticals

Uptake and distribution of radiopharmaceuticals inhealth and disease

TYPES OF RADIATION IMPORTANT IN NUCLEAR

MEDICINE

Gamma raysphotons originating in the nucleus

Characteristic x-rays photons originating outside

the nucleus

Negatrons (beta particles)high radiation dose; ex.

Iodine-131 for tx of thyroid cancer and

hyperthyroidism

Positrons (beta+

particles)Alpha particles helium nuclei; undesirable in

diagnostic applications due to high radiation to

patient

Gamma camera - Specialized equipment that detects,

records and process radioactivity emanating from the

patient in order to create scintigraphic images does

not emit radiation unlike X-ray machines

RADIONUCLIDES AND THEIR RADIATIONS

Alpha decay

Alpha particles are essentially helium nuclei with a

+2 charge and atomic mass number of 4

undesirable in diagnostic application because they

result in high radiation to the patient

Common in higher atomic number range of theperiodic table of elements

Not currently used as diagnostic

radiopharmaceuticals; only in therapeutic agents

ex. Radium-226 decays to radon-222 by emitting an

alpha particle

Negatron decay

Also called beta decay or beta-decay

Electron is ejected from the atomic nucleus, thereby

giving the decay process its name

Involves the conversion of a neutron into a protonan electron, and an antineutrino

Ex. Stable iodine has mass number of 127 (53

protons, 75 neutrons); I-131 has 78 neutrons (highe

number than stable iodine); I-131 undergoes a beta

decay

Disadvantage of beta emittershigh radiation dose

received by the px; for radioactive I-131, this

disadvantage becomes an advantage when the

radionuclide is used in the therapy of thyroid cance

and hyperthyroidism

Positron decay

positive electron or positively charged beta

particle is ejected from the nucleus; Ex

Fluorine-18

Electron capture

Electron from one of the orbital shells (typically

close to the nucleus) is incorporated into the

nucleus, converting a proton into a neutron


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Energy released from this transition appears either

as x-radiation or as kinetic energy of an Auger

electron

Some radionuclides decay by multiple modes,

including electron capture, positron decay and

negatron decay

Isomeric transition and internal conversion

Most gamma rays are emitted almost immediately

(

Radiopharmaceuticals ex.99mTc+monodiphosphate

travels to specific organs and tissues producing

morphologic images

*willeasilyknowwhetherthereismisadministrationor

notsincewhatisgivenisavidtoaspecificorgan

*no significant fluid overload, no siginificant

hypersensitivity,veryminuteamountsofradiation

*veryorganspecific(heart,bones,thyroid)

Terminologies

Radionuclide

o

refers to radioactive atomo all radionuclides are produced in eithe

nuclear reactors or cyclotrons or othe

types of accelerators

Radiochemical

o

when a radionuclide is combined with a

chemical molecule to confer desired

location properties

Radiopharmaceutical

o radioactive materials that have met the

legal requirements for the registration fo

administration to patients or subjects

HALF-LIFE

PHYSICAL HALF-LIFE (t 1/2)

o amount of time for a radionuclide to be

reduced to half of its existing activity

o Ex: t of99m

Tc = 6 hours

o 5 mCi99m

Tc2.5 mCi99m

Tc after 6 hrs

BIOLOGICAL HALF-LIFE

o time for an organism to eliminate half o

an administered compound on a strictly

biologic basis

EFFECTIVE HALF-LIFEo physical and biological half-lives


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Common Radionucleotides

RADIONUCLIDE HALF-LIFE TARGET

ORGAN/DISEASE

Technetium-

99m

6 hrs Thyroid, heart,

bone, lungs,

kidneys

Iodine-131 8 days Thyroid

Thallium-201 73 hrs Heart

Gallium-67 78 hrs lymphoma

inradionuclideswithhighhalf-life,increasefluidintake

toenhanceradionuclideexcretionsothatbefore60hrs

orat least24 hours, radioactivematerials are totally

excreted

Technetium 99m (99mTc)

ideal radionuclide

>70% nuclear imaging procedures

no particulate emission

6-hour t1/2

predominant 140-keV photon

rapidly concentrates in salivary glands, choroid

plexus, thyroid gland, gastric mucosa,

functioning breast tissue, placenta

excretion - GIT, kidneys and GUT

Nuclear Medicine Procedures

Identify abnormalities very early in the progression

of a disease long before some medical problems

are apparent with other diagnostic tests

e.g.breastcancerpxcomplainingofbackpainmay

havenormalCXRbutwhensubjectedto

bonescan,

earlychangesinbonesmayshowsignsofmetastasis

Early detection allows disease to be treated early in

its course when there may be a more successful

prognosis

Is it safe? Yes, it is among the safest means

available.

How much radiation does a Px Receive for a Nuclear

Med Procedure?

Comparable to, or often times, less than that of a

diagnostic X-Ray

Patient receives about the same amount of radiation

as that required in a few months of normal leaving

e.g.travelingfromPhtoUS/Europethroughairplane

exposesyoutomoreUVRadiationcomparedtothat

ofanuclearmedicineprocedure

Scope of Nuclear Medicine

Nuclear Imagingimaging or scanning

Radioimmunoassay sensitive blood examinations

using radioisotopes

Radioactive Iodine Therapy toxic goiter and

differentiated thyroid CA

Bone Palliationuncontrolled pain of carcinoma

Bone Densitometry diagnosis and management o

osteoporosis

PETfordiagnosingmetastasisofthyroidCA

Nuclear Imaging procedures

Cardiac scintigraphy

Renal scintigraphy

Bone scintigraphy

Scintimammography

Hepatobiliary scintigraphy

-radionuclide hepatobiliary scan esp. If ultrasound

does not provide positive frindingsGI bleeding scan-RBC tagging

-RBC tagging can localize source of bleed in the GIT

Liver/Spleen scintigraphy

Ventilation-Perfusion scintigraphy

Thyroid Uptake scintigraphy

Total body scintigraphyI131

Testicular scintigraphy

Radioimmunoassay procedures

T3T4

TSHIRMAEstrogen, estradiol, LH, FSH

Testosterone

Cortisol

Insulin

Lanoxin assay

Radioactive Iodine (RAI) Therapy

Graves disease

Toxic nodular goiter

For ablative treatment of residual thyroid tissue

post-thyroidectomy in patients with differentiated

thyroid CA: papillary and follicular thyroid CA

For treatment of distant metastasis of thyroid

metastasis

Bone pain palliation

Strontium-89 or Samarium-153

Single IV administration that delivers high loca

radiation dose directly to the sites of bony

metastasis

60-80% response rate, 20% pain-free


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Mild toxic effects, generally limited to platelet

depression

Kidney or Renal Scan

To know how the kidney is working

To monitor the flow of urine in mL/min

To check for the degree of any blockage

To assess the effect of recurrent urinary tractinfection

To know how the transplanted kidney is

functioning

Renal Anatomy

lie retroperitoneally between T11 & L3; lower

poles 2-3 cm above iliac crest

average length 12 cm; L slightly larger &

higher than R; R more mobile & ptotic in

women

divided into cortex & medulla

Cortex contains

a. glomeruli

b. proximal & distal convoluted tubules

Medulla contains

a. remaining tubular segments

b. pyramids portion of medulla that

extends from just below outer cortex down

to renal pelvis

c. columns of Bertini cortical projections

between pyramids

Physiology

Blood Supply main renal artery, rarely

duplicated, branches into segmental arteries

arcuateinterlobar arteriesglomeruli

Drugs may be excreted via:

a)

Glomerular filtration blood enters

glomerulus through afferent arteriole;

filtration occurs; filtrate moves into

Bowmans Capsule and into PCT

- GFR number of mL of blood

completely cleared of material in 1

min.; 125mL/min (80-120mL/min);affectedbyheight,weightandBSAof

patient

b)

Proximal Convoluted Tubule (PCT)

Function - urine filtrate radically

altered; most of water reabsorbed

plus NA+, Cl-, and HCO3-; glucose,

amino acids reabsorbed; many drugs

including Hippuran actively secreted

c)

Loop of Henle electrolytes

reabsorbed; water not

d)

Distal Convoluted Tubule (DCT)

resorption of Na under hormona

control: ADH or Angiotensin System

e) Collecting System final part o

system

Arterial blood pressure affects tubula

function; results in prolonged intrarena

transit time of hippuran in renal stenosis Hippuran is a radiopharmaceutical used to

measure the GFR but has a very high dose of

radiation so it is now replaced by newe

radiopharmaceuticals

Radiopharmaceuticals

1.

Glomerular Filtration Rate agents should:

completely filteredby glomerulus

not be protein-bound (cant be

filtered if it is) not be resorbed nor secreted by rena

tubules

be excreted only by kidney (so that

plasma sampling techniques can be

used rather than urine sampling

a.

99m

Tc-DTPA (technetium 99m

diethylenetriamine pentaacetic acid)

-used in the localsetting

completely eliminated by glomerula

filtration; no tubular secretion occurs

-meets the requirement for measuring GFR

except for the 3-5% that is protein-bound

b.

Chromium 51 EDTA

- GFR slightly lower than inulin

c.

I123/I131 iodothalamate

-radioactive contrast

d.

I131 diatrizoate

-radiographic contrast used in xrays and CT

scans

2. Tubular agents

ideal agent for measuring effective renaplasma flow (ERPF)

Also used for renal function

In the local setting, we only have GFR

radiopharmaceutical agents

a.

131

I OIH (Iodine 131 orthoiodohippurate)

chemically similar to paraaminohippuric acid

(PAH)

gold standardfor measurement of ERPF


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b.

99m

Tc MAG

3

(Technetium 99m

mercaptoacetyltriglycine)99mTc replacement

for IOH; excreted by PCT like OIH, not retained

in parenchyma; lower radiation dose; superior

quality of renal images than IOH & DTPA

3.

Parenchymal Agent

a.

99mTc DMSA (Technetium 99mdimercaptosuccinic acid) taken up by renal

cortex in proximal convoluted tubule; 90%

protein bound preventing significant

glomerular filtration

Technique for doing Nuclear Renal Study

1.

Flow study:

-rapid sequential images every 2 seconds for

30-60 seconds

-10-15 mCi of 99mTc-DTPA or 5-10 mCi MAG3

via bolus injection Unit of radiation is in Curie (Ci). What

is being given to patients is only in

milliCuries (mCi).

2.

Excretion study:

-serial 3-minute images for 30 minutes

-Adequate hydration; let px void before the

study

full bladder can simulate upper tract

obstruction if the px is dehydrated-will give

falselylowresults

Different types of nuclear medicine studies for kidney

diseases

1. Glomerular Filtration Rate used tomonitor

urineflowinmL/min(normal:80-120mL/min);

goes lower as the person ages; measured

according to the patients height andweight

andbodysurfacearea;lastsfor6min

2.

Basic Renal Scan native and transplanted

kidneys; usualrenalscan;assessrenalfunction

and urodynamics or the excretion of the

kidneys;lastsfor20min;patienthastowaitfor

onehourbeforeextractionofthebloodandfor

thethirdhourforanotherre-extraction

3.

Diuretic renal scan to diagnose or exclude

urinary tract obstruction; diuretic-augmented

renal scan; we give diuretics like furosemide

and observe whether patients excretion

improveswithdiuresis;ifitimproves,itmeans

that the obstruction is just temporary; if

obstructionpersists,thereistrueobstruction

4.

Captopril-augmented renal scan captoprilis

givenonehourprior todoingthe renalscan

helpsindiagnosingrenovascularhypertension

5.

Renal cortex scan (DMSA scan) used fo

diagnosingpyelonephritis6.

Radionuclide cystography to detect

quantitate or follow-up reflux

Radionuclide renal scan

Three Parts:

1.

Angiographic imagesperfusion phase

2.

Time activity histograms

a.

Perfusion

b.

excretion

3. Excretory images

A.

Perfusion Phase

*in secs.(1-16 secs.)

*w/in3secs,aorta should beseenandafter 3secs.

Kidney should already be seen. Hypoperfusion is

presentif itismorethan thenormal time.Theabove

imageshowsthatthe uptake ornumber ofcounts is

veryhighwhichis1800counts/secwhichmeansthat

mostoftheradioactivematerialshavebeentakenup

bythatkidneysinthatspanoftime(kidneyshavevery

goodperfusion).


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B.

Excretory phase

*in

Patient should be adequately hydrated unless the

patient is hypertensive; should void before the study

becauseafullbladdermaymimicobstruction;supine

orpronepositionisadvised;uprightpositionmayshow

ashortenedkidney

0-30seconds;inthreeseconds,urineshouldalreadybe

seenintheurinarybladdertosaythatithasanormal

excretoryphase;In1st-20thminute,thereshouldbe

filling up of the bladder and the kidneys should have

decreasingactivityuntilalmostnoneintheendofthestudy. In histogram, there is intense uptake in the

aortaandgradualdecreasesasthetracerisexcreted

intheurinarybladder;leftkidney isthegreengraph;

right kidney is the purple graph; black graph is the

aorta;leftandrightkidneyshouldovershoottheaorta;

activity ismeasured in counts per second; the count

should be high, like 1200 counts/sec; if it is low, it

meansthatithaslowerperfusionorpoorfunctionof

thekidneys

NORMAL SCAN

Renal flow study

- Both kidneys visualize symmetrically and

with similar intensities (differ depending

on renal size); intensity of kidney should

equal or exceed early activity in spleen

- Slope of curve of activity entering each

kidney should parallel aortic curves

- Peak should occur no more than 3

seconds later than aortic peak

- Splenic and liver activity may stimulate

kidney activity

Normal values

- GFR: 125mL/min

- Effective renal plasma flow (ERPF): 500

600 mL/min

- Filtration index: 0.2

-Excretory index: 1

Static images

- Smooth renal contour

- Note: normally defects are seen due to

collecting system and irregularities at

corticomedullary junction

NORMAL RENAL CORTEX SCAN

*left image:diffuse pyelonephritison the left kidney;

reducedtraceractivity

*rightimage:abnormalrenalcortexstudy;contracted

rightkidney;defectinthesuperiorleftkidney

*multiplescars-->contraction-->smallkidney


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OTHER NUCLEAR IMAGING TESTS

1.

Bone scan or scintigraphy to evaluate

unexplained bone pain in patients with and

without cancer, to detect arthritis, fractures,

sports injuries, bone tumors and even cases of

child abuse; normalbonescan shouldappear

symmetrical, no trace of increase tracer

activity;increaseintraceractivityinacertainarea may indicate inflammation or

degeneration

*top image: normal scan

*below: abnormal scan

2.

Scintimammography to more accurately

identify and locate cancerous tissue in the

breasts, especially when the mammograms

are difficult to interpret because of dense

breast tissue, previous biopsy, surgery, silicone

implants

*leftpicture:normal;patientisinproneposition;

uniformradiotracerdistributioninthebreast

*right picture: abnormal; known breast mass with

increasedradiotraceractivity

3. Hepatobiliary scan to evaluate uppe

abdominal pain, know the cause of yellowing

of the skin or jaundice and identify obstruction

in the gallbladder.

*normalscan;gallbladdershouldbeseeninonehour


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*patient with persistent right upper quadrant paindespite normal hepatobiliary ultrasound; no

appearanceofthegallbladder;levelofobstructionisat

thecysticduct;preparethepatientforsurgery

*acute acalculous cholecystitis; no obstruction

*bile leak; very sensitive and non-invasive

*HIDA scan (hepatobiliary iminodiacetic acid scan)

there is gradual reduction of tracer activity in the liver

biliary atresia failure of the development of bile

ducts;hepatitisinfectionintheliver


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4.

Bleeding scanidentify the source of bleeding

in a patient with melena, hematochezia

*active bleeding in the sigmoid colon

*bleeding hemangioma in the latter portion of the

duodenum

5. eckels diverticulum scan

to detect the

presence of a Meckels diverticulum(remnan

oftheomphalomesenterialcap;ectopicgastric

mucosa)

*meckels diverticulum should be seen within one

hour; 99% specific

6. Perfusion-ventilation lung scan to diagnose

pulmonary emboli or blood clots in the lungs

- To quantify lung function

- To detect lung transplant rejection


10/12

7.

Thyroid scan differentiates thyroiditis from

Graves disease

- Differentiates hot vs cold nodulesFinds

96% of nodule; palpation only 60%

- Risk of malignancy in cold nodules: 10-

20%

*left: cold nodule; right: hot nodule

*left: thyroiditis; right: toxic goiter

*left: toxic goiter (less background); right: toxic

adenoma (hot nodule as big as 3cmwith signs and

symptoms or toxic goiter; treatment includes

medication,radioactiveiodineandsrugery)


11/12

8.

Testicular scan to detect acute testicular

torsion in patients with testicular pain

9.

Dacryoscintigraphy to know the cause of

frequent tearing of the eyes or to evaluate the

nasolacrimal system

*complete obstruction of the right nasolacrimal

system

10.

Parathyroid adenoma scan help localize a

hyperfunctioning parathyroid adenoma before

initial surgery in a patient with primary

hyperparathyroidism

- Help localize a hyperfunctioning adenoma

in a patient with primary

hyperparathyroidism after parathyroid

surgery

11.

Total body scanused for diagnosing patients

with thyroid carcinoma, who has undergone

thyroidectomy and underwent radioactive

iodine treatment for ablating thyroid

carcinoma

*isolate those exposed to radiation for two weeks to

one month


12/12

RADIOACTIVE IODINE THERAPY (RAI)

- Over-all survival rate is 80-90%

- Patients untreated with I131 ahve

cumulative tumor recurrence rate of 40%

in 30 years

- Higher recurrence rate in tumors >1cm,

poorly differentiated follicular subtypes,

Hurthle cell cancers, lymph nodemetastasis, distant metastasis, age 46 years old

References:

- DocAudioandLecture

- Notes thatwere partof the old notes and not the

lecture

Notetakers:

- Arielle

- Boni

- Jan

Editor:- Lauren

Tigbauan Fun Fact: During October they celebrate the Adlaw

sangTigbauan or otherwise known as the Saludan Festival

comingfromtherootwordsaludwhichwasusedtodescribethe

wayfishermencaughtfish

nuclear imaging, nephro emphasis

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