Nuclear Imaging, nephro emphasis
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Transcript of 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
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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)
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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
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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