RadionuclideRadionuclide ImagingImaging

PhD Lenchuk TatyanaPhD Lenchuk Tatyana

Radionuclide diagnosis - a method of diagnosing a patient based on the introduction of radiopharmaceutical (RPh) in organіzm. Using the radionuclide diagnostic can investigate virtually any organ or tissue in the body, as some of them in several ways. With clearly defined goals and a continuously feedback between a radiologist and doctors clinical departments, the possibilities of radionuclide diagnostics are almost limitless, especially in case of formulation particularly difficult diagnoses RPh consists :1. molecule, isotropic (native) to the target organ or tissue2. presence radiolabeling, allowing to determine the dynamics and the amount of accumulated RPh via an external encoder ( 99mTc, 18F, 123I )

3. 3. must emit detectable rays or photons. Most frequently use must emit detectable rays or photons. Most frequently use ƔƔ-radiated RPh.-radiated RPh.

4. 4. RPh must be radiochemically pure. The purity is RPh must be radiochemically pure. The purity is determined by concentration of main radionuclide.determined by concentration of main radionuclide.

5. 5. RPh must be apyrogenic. Apyrogenity is determined by RPh must be apyrogenic. Apyrogenity is determined by the use of reagents, solutionsthe use of reagents, solutions..

RPH Safety Regulations1. RPh must be physiologically determined, i.e. it must

selectively be absorbed by specific organ, inserted into it’s metabolism and show the function of organ or organism.

2. RPh must be low-radiotoxic, i.e. to give minimal radiation to organism and critical organ.

The radiotoxicity of RPh is determined by T 1/2 /Тphys/.Time of the half amount of radionuclide decay.

The widely used radionuclides are The widely used radionuclides are followingfollowing::99мТС99мТС - Т1/2- 6 - Т1/2- 6 hours, for brain tumors, thyriod hours, for brain tumors, thyriod gland, skeletal system, respiratory system gland, skeletal system, respiratory system diagnosticsdiagnostics..I131I131 – Т1/2 – 8,04 – Т1/2 – 8,04 days, for iodine metabolism, days, for iodine metabolism, liver, kidneys functionliver, kidneys function..51С51Сrr //27.7 days27.7 days/ - / - in hematologyin hematology..198Au 198Au //2.697 days2.697 days/ / andand In111 – In111 – for liver, brain for liver, brain diagnosticsdiagnostics..

Target (critical) OrganTarget (critical) OrganSo, what is target organSo, what is target organ? ?

Target organ – is organ in which the RPh is maximally Target organ – is organ in which the RPh is maximally accumulated and which is exposed by excessive accumulated and which is exposed by excessive radiationradiation. . Mostly, it is the organ we want to examineMostly, it is the organ we want to examine..

By safety regulations By safety regulations there are 3 groups of target there are 3 groups of target organs due to decreasing or radiosencitivityorgans due to decreasing or radiosencitivity::

1.1. groupgroup – – whole body, genitals, bone marrow, whole body, genitals, bone marrow, small intestine mucosasmall intestine mucosa..

2. 2. groupgroup – – muscles, thyroid, fat, liver, kidneys, muscles, thyroid, fat, liver, kidneys, spleen GI tract, lungs, lensspleen GI tract, lungs, lens. .

3. 3. groupgroup – – skin,bonesskin,bones..

Radionuclide LaboratoryRadionuclide Laboratory

All the activity with RPH must undergo in specific offices. All All the activity with RPH must undergo in specific offices. All equipment must be shielded and RPH should not waste the equipment must be shielded and RPH should not waste the environmentenvironment. . The laboratory must include following roomsThe laboratory must include following rooms: :

Storage facilityStorage facility – 8-10м2 – 8-10м2 ventilationventilation 5-10 5-10 times per hourtimes per hour.. Preparation room Preparation room - 8-20м2.- 8-20м2. Washing room Washing room – 10м2.– 10м2. Procedural room Procedural room - 16-20м2 . - 16-20м2 . Radiometry facility Radiometry facility – 20-25м2.– 20-25м2. Radiography facilityRadiography facility – 15-18м2. – 15-18м2. Gamma – topography facilityGamma – topography facility – 12-18м2. – 12-18м2. Room for detection of activity of biological substancesRoom for detection of activity of biological substances – 12м2 – 12м2 Observation room (for outpatients)Observation room (for outpatients).. Sanitary roomsSanitary rooms..

Methods of radionuclide Methods of radionuclide diagnosticsdiagnostics

1. 1. ііnn vivo vivo i/venously or per os i/venously or per os..2. 2. In vitroIn vitro (blood, urina, other biological fluids) (blood, urina, other biological fluids).. Radioimmunoassay in comparison with biological Radioimmunoassay in comparison with biological and biochemical research methods has several and biochemical research methods has several advantages: high sensitivity, which allows to advantages: high sensitivity, which allows to determine small amounts of the substance, determine small amounts of the substance, specificity, due to the principle of immunological specificity, due to the principle of immunological reactions, high accuracy and reproducibility of the reactions, high accuracy and reproducibility of the method. The disadvantages include a relatively high method. The disadvantages include a relatively high cost of a standard set of reagents for each blood cost of a standard set of reagents for each blood component.component.

Methods of radionuclide diagnostics (in vivo)Methods of radionuclide diagnostics (in vivo)

1. 1. RadiometryRadiometry – – is method, which determines is method, which determines radioactivity of the body, organ. This method allows to radioactivity of the body, organ. This method allows to detect amount of radionuclide in organ or organism.detect amount of radionuclide in organ or organism.

2.2. RadiographyRadiography..This method allows to detect distribution, This method allows to detect distribution,

accumulation and elimination of RPHaccumulation and elimination of RPH.. The result is a The result is a curve of the intensity of RPH in target organ during curve of the intensity of RPH in target organ during period of time (blood circulation, liver, kidneys function). period of time (blood circulation, liver, kidneys function). This method allows to estimate clearance of blood.This method allows to estimate clearance of blood.

Methods of radionuclide Methods of radionuclide diagnosticsdiagnostics

Blood clearanceBlood clearance – the velocity of blood – the velocity of blood

purification from RPH per time. The faster is clearance - purification from RPH per time. The faster is clearance -

the better is the organ function. A typical example is the the better is the organ function. A typical example is the

radiographic study of the accumulation and excretion of radiographic study of the accumulation and excretion of

the radiopharmaceutical from lungs, kidney, liver. the radiopharmaceutical from lungs, kidney, liver.

Radiographic function in modern devices is combined in Radiographic function in modern devices is combined in

a gamma camera with visualization of organsa gamma camera with visualization of organs

Methods of radionuclide Methods of radionuclide diagnosticsdiagnostics

3. 3. Radionuclide imagingRadionuclide imaging. The technique of painting . The technique of painting the spatial distribution in the organs of the the spatial distribution in the organs of the radiopharmaceutical injected into the body. radiopharmaceutical injected into the body. Radionuclide imaging currently includes the Radionuclide imaging currently includes the following: following: • a) scanning, • a) scanning, • b) scintigraphy with the use of gamma camera, • b) scintigraphy with the use of gamma camera, • c) single-photon emission tomography and two-• c) single-photon emission tomography and two-photon positron emission tomography (PET).photon positron emission tomography (PET).

Scanning - method visualization of organs and Scanning - method visualization of organs and tissues by moving over the body of the scintillation tissues by moving over the body of the scintillation detector. The device is conducting a study called detector. The device is conducting a study called the scanner. The main drawback - the long the scanner. The main drawback - the long duration of the study.duration of the study.

Scintigraphy. Method of imaging the spatial distribution in organ of RFh and photon detection with a scintillation detector or detectors. The method makes it possible to evaluate the morphological and functional state of the body. Scintigraphy - is currently the main method of radionuclide imaging in the clinic.

Gamma radiation from the body of the patient is recorded by the detector gamma camera and computer after processing the obtained information is converted into a functional image of the investigated body.

There are several types of scintigraphy.There are several types of scintigraphy. Static planar scintigraphy Static planar scintigraphy. The simplest type of . The simplest type of scintigraphy. After the introduction of RPh, registration its scintigraphy. After the introduction of RPh, registration its distribution in the target organ by fixed detector. Determine distribution in the target organ by fixed detector. Determine the shape, size and nature of the organ contours, and the shape, size and nature of the organ contours, and most importantly, areas of abnormal accumulation indicator most importantly, areas of abnormal accumulation indicator - high or low ("hot" or "cold" lesions). The method is - high or low ("hot" or "cold" lesions). The method is applicable for the detection of tumor lesions in parenchymal applicable for the detection of tumor lesions in parenchymal organs.organs.

Scintigraphy result of the healthy liver thyrotoxic adenoma, hot node

Whole-body scintigraphyWhole-body scintigraphy. Variant static . Variant static scintigraphy, however, here the table with the scintigraphy, however, here the table with the patient or the detector are moved in a horizontal patient or the detector are moved in a horizontal plane, which allows to detect of photons from all plane, which allows to detect of photons from all Rph tracers of organism or a part of it. Widely used Rph tracers of organism or a part of it. Widely used in the study of skeletal - in the study of skeletal - bone scintigraphy bone scintigraphy to to identify multiple lesions pathological process, such identify multiple lesions pathological process, such as searching for metastases.as searching for metastases.

metastases in bone

arthrosis

Dynamic scintigraphy. In contrast to the static, here, a series of scintigrams with a certain time interval. This allows, in addition to anatomical characteristics, to study organs function ( eg. excretory function of the liver, the filtration and excretory function of the kidneys, etc).

Immunoscintigraphy - imaging of tumors by monoclonal antibodies with RPh are obtained by immunization of animals extracts antigens from remote malignant tumors. Sufficiently accurate method for the diagnosis of malignancy.

Single photon emission computed tomography (SPECT tomoscintigraphy) - registration of photons RPh of the examined organ by using one, two or three detectors rotate around the patient's body for some orbit (circular, elliptical, or difficult-adaptive). The number of slices obtained from 32 to 128, slice thickness of 4 to 10 mm, reconstruction is possible in different projections. This allows not only the anatomical and topographical characteristics of the organ, but also allows to study the biochemical, physiological, and transport processes. Used for the diagnosis of volumetric formations and vascular disorders of the brain, for the early detection of pulmonary embolism, coronary artery disease.

Slice imagesaccumulationOf RPh

Positron emission tomography (PET) - a method of nuclear medicine based

on the use of ultra-short-lived radiopharmaceuticals labeled with positron

emitters - 15O, 13N, 11C, 18F-FDG. T- aff. these drugs is 2, 10, 20.4 and

110 minutes. Sensitivity of the method is fantastic. PET allows us to

conclude the change rate of glucose labeled with C11 in the "eye center" of

the brain when you open the eyes, it is possible to detect changes at the

thinking process, and even to determine the so-called "Soul". PET enables

the study of functional changes and ability to live of tissue at the molecular

level, such as glucose metabolism, oxygen utilization, assessment of blood

flow and perfusion assessment . As well as functional changes precede

morphological, cellular metabolism study provides an opportunity to

diagnose a number of diseases earlier than with CT and MRI.

PET CT

Essentially this is the only method to evaluate the metabolic processes

in vivo. The method is used in cardiology for the study of perfusion and

blood flow in the myocardium with coronary artery disease, to determine

the viability of the myocardium after myocardial infarction; neurology for

the detection of epileptogenic foci in the diagnosis of various types of

dementia , in oncology for the diagnosis and staging of brain tumors,

lung, breast, colon, for evaluating chemotherapy for detecting tumor

recurrence. The disadvantage of this method is that its use is possible

only with the cyclotron, the radiochemical laboratory for short-lived

nuclides, positron tomography and computer information processing,

which is very expensive and cumbersome.

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