RADIOPHARMACY

Diagnostic Nuclear Medicinecontinue

5

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.

LUNG IMAGING.

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 andpulmonary ventilation, to detect pulmonary embolism and to assesspulmonary 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.- .

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 bymechanical 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 routinenuclear medicine procedure that can provide valuable information aboutregional 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 non-radioactive gas which is physiologically inert. Bio-distribution.(1) Xe-133 is a readily diffusible gas, which is neither used nor produced bythe 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 uniformlung 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 space-occupying 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

DefinitionA 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.

PurposeWhile 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 renalfunction, renal vascular flow, and renal morphology. They are also usefulfor the evaluation of renal function in post transplant patients. The use of radiopharmaceuticals to determine renal function or renalmorphology is based on the two physiological mechanisms responsible forexcretion: glomerular filtration and tubular secretion. Agents cleared by glomerular filtration are useful in determining theglomerular filtration rate (GFR) , renal artery perfusion, and the visualizationof 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 excretedwithin 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 therenal 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