Transcript Bio-distribution

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RADIOPHARMACY
Diagnostic Nuclear Medicine
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LUNG IMAGING.
Lung Perfusion and Ventilation Scan
Definition
A lung perfusion scan is a nuclear medicine test that produces a
picture of blood flow to the lungs.
A lung ventilation scan measures the ability of the lungs to take in
air and uses radiopharmaceuticals to produce a picture of how air
is distributed in the lungs.
Purpose
Lung perfusion scans and lung ventilation scans are usually
performed in the same session.
They are done to detect pulmonary embolisms, determine how much
blood is flowing to lungs, determine which areas of the lungs are
capable of ventilation, and assess how well the lungs are functioning
after surgery.
These tests are called by different names, including perfusion lung
scan, ventilation lung scan, ventilation/perfusion scanning (VPS),
pulmonary scintiphotography, or, most commonly, V/Q scan.
Precautions
The amount of radioactivity a person is exposed to during these
tests is very low and is not harmful. However, if the patient has
had other recent radio-nuclear tests, it may be necessary to wait
until other radiopharmaceuticals have been cleared from the body
so that they do not interfere with these tests.
Radiopharmaceuticals are used to evaluate both pulmonary perfusion and
pulmonary ventilation, to detect pulmonary embolism and to assess
pulmonary function.
A. Pulmonary perfusion imaging
Tc-99m macro-aggregated albumin (Tc-99m MAA)
Physical properties
(1) The Tc-99m albumin aggregated kit contains human serum albumin
(HSA) that has been aggregated by heat denaturation.
(2) This kit exists as a sterile, pyrogen- free aggregated particles ready for
reconstitution (labelling) with Tc-99m pertechnetate.
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Bio-distribution
(1) After IV administration of Tc-99m MAA , the radiolabeled albumin particles
become trapped by capillary blockade in the pulmonary circulation.
(2) After trapping, the particles are cleared from the lungs mainly by
mechanical breakup.
(3) Particle size should be controlled, to ensure adequate trapping by the lung
capillary bed but no occlusion of the large bore vessels.
(4) Particle number should be controlled ,to obtain uniform imaging data
without compromising capillary blood flow.
Administration and dosage. IV, 4 mCi (148 MBq)
B. Pulmonary ventilation imaging with radioactive gases is a routine
nuclear medicine procedure that can provide valuable information about
regional lung ventilation.
Radiopharmaceuticals used are either radioactive gases or radio-aerosols.
1. Xenon-133 (Xe-133) Xe-133 Gas is for diagnostic inhalation use only. It is
supplied in vials containing 20 mCi ( 740 MBq ) of Xe-133 gas in 2 ml of carrier.
Xe-133 Gas is chemically and physiologically similar to elemental xenon, a nonradioactive gas which is physiologically inert.
Bio-distribution.
(1) Xe-133 is a readily diffusible gas, which is neither used nor produced by
the body.
(2) the gas is physiologically inactive.
c. Administration and dosage. Inhalation, 20 mCi (740 MBq)
2. Radioaerosols
have become increasingly used with the advent of nebulizers that
produce particles of a consistent size necessary for uniform
lung distribution.
Bio-distribution
(1) Tc-99m DTPA (Diethylene Triamine Penta Acetic acid)
radio-aerosols are useful in determining lung ventilation.
(2) After deposition of the nebulized droplets within the airways, the
Tc-99m DTPA is absorbed into the pulmonary circulation.
(3) The material is subsequently excreted by the kidneys.
Administration and dosage. Inhalation, 30 mCi (1110 MBq)
HEPATIC IMAGING
Overview.
Hepatic imaging requires the use of two different classes of radiopharmaceuticals
to evaluate the two cell types responsible for hepatic function.
1. Reticuloendothelial system imaging. The liver , spleen, and bone marrow are
evaluated with radiolabeled colloidal material. These particles are rapidly cleared
from the blood by phagocytosis by the Kupffer cells.
a. Liver spleen imaging. Radiopharmaceuticals are useful in imaging spaceoccupying lesions as tumours or any hepatic defects caused by abscesses, cysts,
and trauma.
b. Bone marrow imaging. Images that localize in the bone marrow are useful in the
evaluation of pathologies that affect bone marrow.
2. Hepatobiliary imaging. Liver function can be evaluated by substances excreted
by the Hepatocyte cells into the hepatobiliary system.
Hepatobiliary imaging radiopharmaceuticals are useful in the diagnosis of cystic
duct obstruction, gall-bladder function and post-cholecystectomy anatomy and
physiology.
Reticuloendothelial -imaging agents
Tc-99m sulfur 0r tin colloid
is a sterile, pyrogen- free IV radiopharmaceutical.
Bio-distribution
After administration, 80%-90% of the dose is phagocytized by the Kupffer cells
of the liver, 5%-10% by the spleen, and the balance by the bone marrow.
Particles are not metabolized and retained in the reticuloendothelial system
for a prolonged period enough for imaging.
Administration and dosage. IV, liver /spleen: 5 mCi (185 MBq)
liver scan, a noninvasive technique for
visualizing the size, shape, and
consistency of the liver and for assessing
the liver's functional status. It involves IV
injection of a radioactively labeled
compound that is readily taken up and
trapped in the Kupffer cells of the liver.
The radiation emitted by the compound
is recorded with a scintillation camera.
Liver scans are useful for diagnosing
three-dimensional lesions such as
abscesses and tumors, for performing
biopsies, and for evaluating
hepatomegaly.
Hepatobiliary- imaging agents
Overview
Iminodiacetic acid (IDA) derivatives (HIDA) , are useful as
hepatobiliary- imaging agents because of their lipophilicity, which
allows them to be selectively cleared by carrier -mediated
hepatocyte metabolic pathways. Because these agents share the
same excretion pathway as bilirubin , they are excreted in bile ,
allawing imaging and evalution of hepatobillary function.
Cholecystokinetic agents, such as cholecystokinin, may be used to
empty the contents of the gallbladder before 0r after injection of
an IDA compound .
A HIDA scan is an imaging procedure that helps track the
production and flow of bile from the liver to small intestine.
Bile is a fluid produced by the liver that helps the digestive
system break down fats in the foods we eat.
A HIDA scan, which stands for hepatobiliary iminodiacetic
acid scan, creates pictures of your liver, gallbladder, bile
ducts and small intestine. Cholescintigraphy, hepatobiliary
scintigraphy and hepatobiliary scan are alternative names
for HIDA scan.
Tc-99m disofenin (Tc-99m DISIDA)
Bio-distribution
(1) Tc-99m DISIDA is rapidly cleared from the blood.
(2) most of the the administered activity is excreted through
the hepatobiliary system.
(3) liver uptake is visualized within 10 min; gallbladder uptake is
by 30-40min ,intestinal visualization occurs within 60 min post
administration.
Administration and dosage. IV, : 5 mCi (185 MBq).
Kidney Nuclear Medicine Scan
Definition
A kidney nuclear medicine scan, or study, is a simple outpatient test that
involves administering small amounts of radioactive substances, called tracers,
into the body and then imaging the kidneys and bladder with a special camera.
The images obtained can help in the diagnosis and treatment of certain kidney
diseases.
Purpose
While many tests, such as x rays, ultrasound exams, or CT , can reveal the
structure of the kidneys (its anatomy), the kidney nuclear medicine scan is
unique in that it reveals how the kidneys are functioning. This is valuable
information in helping a doctor make a diagnosis. Therefore, the kidney nuclear
medicine scan is performed primarily to see how well the kidneys are working
and, at the same time, they can identify some of the various structures that
make up the kidney.
RENAL IMAGING
Overview
Radiopharmaceuticals are used in renal imaging to determine renal
function, renal vascular flow, and renal morphology. They are also useful
for the evaluation of renal function in post transplant patients.
The use of radiopharmaceuticals to determine renal function or renal
morphology is based on the two physiological mechanisms responsible for
excretion: glomerular filtration and tubular secretion.
Agents cleared by glomerular filtration are useful in determining the
glomerular filtration rate (GFR) , renal artery perfusion, and the visualization
of the collecting system.
1. Tc-99m Diethylene Triamine Penta Acetic acid
(Tc99m-DTPA)
A chelating agent. The test is often used in combination with a
diuretic drug such as lasix to determine if a kidney is obstructed.
Bio-distribution
(1) After administration,Tc-99m DTPA is rapidly distributed
throughout extracellular fluid space, from which it is rapidly cleared
by glomerular filtration only.
(2) After administration, most of the dose is cleared by the kidneys
within 2hrs.
Administration and dosage. IV, 10 mCi (370 MBq)
2. Tc-99m
mercapto acetyl triglycine (Tc99m-MAG3)
Description
(1) Supplied as a sterile, pyrogen- free, lyophilized kit containing MAG3, and
chelating adjutants.
(2) After the Tc-99m pertechnetate is added to the kit , it must be heated in
a hot water bath at 100°C for 10 min to form Tc-99m MAG3.
Bio-distribution
(1) MAG3 is renally excreted, most of the administered dose is excreted
within 3 hr post injection.
(2) It is primarily cleared via active tubular secretion.
Administration and dosage. IV, 5 mCi (185 MBq)
Renal cortical imaging agents are used to evaluate renal
anatomy ,because of their ability to accumulate in the kidney
and provide anatomical imaging data.
3. Tc-99m
Dimercaptosuccinic acid ( Tc-99m DMSA)
Tc-99m DMSA complex must be allowed to incubate for 10 min post
reconstitution .
Bio-distribution
(1) Within 3-6 hr post administration, most of the dose localizes in the
renal cortex, where it is taken up by the tubular cells.
(2) Unlike DTPA and MAG3,excretion into the urine is slow.
Administration and dosage. IV, 5 mCi (185 MBq)
Thank you and Good Luck
Prof. Dr. Omar Shebl Zahra