Scintigraphy

A patient is given a radio indicator (radiopharmaceutical (RFP)) - a drug consisting of a vector molecule and a radioactive marker (isotope). A vector molecule is absorbed by a specific body structure (organ, tissue, fluid). The radioactive label serves as a “transmitter”: emits gamma rays, which are recorded by a gamma camera.

The amount of radiopharmaceutical administered is such that the radiation emitted by it is readily captured, but it does not have a toxic effect on the body.

Currently, scintigraphy is widespread in the United States, Europe and several other countries. So in the USA in 2007 more than 17 million radionuclide studies were conducted in more than 15 million people. In Europe in the same year over 12 million studies. In the United States today, more than 12.5 thousand single-photon emission computed tomographs (gamma cameras) are installed and actively used. Unfortunately, in Russia the situation with radionuclide diagnostics is much worse. To date, about 200 gamma cameras are installed in the Russian Federation, and the vast majority of them are morally obsolete. While in the USA and Europe 40–50% of radionuclide studies are performed in outpatient facilities (polyclinics), in the Russian Federation scintigraphy is the destiny of large medical centers and leading hospitals in Moscow (First Sechenov Moscow State Medical University, Cardiovascular Surgery Institute named after Bakuleva, Russian Cardiological Research and Production Complex (RCNPK), Russian Research Center for X-ray Radiology (RRCR), Blokhin Oncological Research Center, Medical and Rehabilitation Center (FGU LRC), Hospital named after Botkin, Clinical Hospital No. 1 of the UDP of the RF (Volynskaya olnitsa), Moscow Clinical Scientific Center, etc.), Obninsk (Medical Radiological Scientific Center (FSBI MRRC)), St. Petersburg (St. Petersburg State Medical University named after I.P. Pavlov, Central Scientific Research Radiological Institute), Kazan (Republican Clinical Oncology Dispensary), Tomsk (Research Institute of Cardiology), Tyumen ( Radiological Center ), etc. The number of studies in the Russian Federation does not reach even one million.

• MIBI, sestamibi (technetril), tetrofosmin (Mioview) labeled with ^99m Tc - radiopharmaceutical, tropic to intact cardiomyocytes. It is used for single-photon emission computed tomography (OEKT, SPECT) of the myocardium, in order to diagnose ischemic heart disease (IHD) and its complications (myocardial infarction, post-infarction cardiosclerosis, ischemic cardiomyopathy), including ECG - synchronized tomography.
• Mono- and Bisphosphonates labeled with ^99m Tc (e.g., pyrophosphate) are radiopharmaceuticals that are tropic to emerging bone tissue. They are used in bone scintigraphy to diagnose distant blast metastases, primary malignant bone tumors, as well as inflammatory, degenerative and traumatic changes.
• Diethylenetriaminepentaacetic acid ( DTPA ) labeled with ^99m Tc is a radiopharmaceutical that is tropic to the renal glomeruli. Used in kidney scintigraphy (dynamic nephroscintigraphy).
• Pertechnetate ( ^99m Tc ) - a solution of pure technetium is used for thyroid scintigraphy.
• Albumin Macroaggregates (MAA) labeled with ^99m Tc - radiopharmaceutical for perfusion lung scintigraphy.
• Hexamethylpropyleneaminoxime (HMPAO) labeled with ^99m Tc - RFP for brain scintigraphy (single photon emission computed tomography)
• ¹²³ I - is both a vector for the thyroid gland and a radioisotope.
• Tl ²⁰¹ - accumulates in cardiomyocytes similarly to potassium, a marker for myocardial scintigraphy.

There are radiopharmaceuticals tropic to a certain pathology (including certain forms of cancer) - 111ln - Octreoscan ™, 123I - MIBG (MIBG).

The indicator (radiopharmaceutical) in the vast majority of studies is administered intravenously.

• static - the result is a flat (two-dimensional) image. This method is most often examined bones, thyroid gland, etc.
• dynamic - the result of the addition of several static, obtaining dynamic curves (for example, in the study of the function of the kidneys, liver, gallbladder)
• ECG-synchronized study - ECG- sync allows you to visualize the contractile function of the heart in tomographic mode.

Sometimes a related method of single-photon emission computed tomography (SPECT), which allows obtaining tomograms (three-dimensional images), is referred to scintigraphy. When applying SPECT / CT technology, a hybrid tomographic study of a given area is recorded with fusion images combining isotope tomography (SPECT) and computer (CT). As a result, the functional image is combined with the anatomical image, often increasing the sensitivity and specificity of the detected changes. Using SPECT technology, studies of the myocardium and the brain are carried out. SPECT / CT is used in the study of skeleton bones, thyroid and parathyroid glands, lungs, and liver, as well as in studies with tumor-specific drugs (octreotide, sestamibi, MIBG, etc.)

Gamma camera - a scintillation camera that detects gamma radiation . In a scintillator of a gamma camera, absorbed or scattered gamma rays are converted into photons of visible radiation, and the number of emitted photons is proportional to the energy of the gamma quantum absorbed in the scintillator. Photomultipliers convert a light flash in a scintillator into a current pulse, which is recorded by spectrometric equipment. The pulse amplitude is proportional to the gamma-quantum energy absorbed in the scintillator; therefore, it is possible to separate flares from gamma-quanta with the energy characteristic of the marker used from the background. The use of the assembly of photomultipliers makes it possible to restore the coordinates of the flash and, thus, measure the spatial distribution of the marker in the patient’s body.

• Diagnosis of coronary heart disease (CHD), including by detecting transient myocardial ischemia, cicatricial changes, studies of cardiac contractility.
• Diagnosis of pulmonary embolism .
• Diagnosis of metastases and primary tumors of bone tissue, fractures, inflammation, and infections ( osteoscintigraphy ).
• The study of the blood supply to the brain - is used in the diagnosis of Alzheimer's disease, some forms of dementia, infectious diseases. There are markers to track the distribution of receptors of certain neurotransmitters in brain tissue, for example, dopamine , which can be used in the diagnosis of Parkinson's disease .
• Diagnosis of diseases of the thyroid and parathyroid glands.
• Assessment of kidney function and their blood supply.
• Identification of liver diseases, functional disorders of the hepatobiliary system.

Myocardial scintigraphy

Myocardial scintigraphy is the leading method for the diagnosis of coronary artery disease worldwide, the annual number of patients in Europe and the United States exceeds 10 million people. During the study, the patient is given a radiopharmaceutical that is tropic to unchanged cardiomyocytes of the heart muscle (myocardium) in order to visualize them. Myocardial scintigraphy is carried out in 2 stages: a study with exercise and at rest. The method has wide capabilities in the diagnosis of coronary heart disease. Transient myocardial ischemia is detected due to damage to the coronary arteries by atherosclerotic plaques, including in patients without an angina pectoris clinic. Depending on the location and prevalence of transient ischemia, indications for coronary angiography are determined. In patients with acute myocardial infarction, a determination is made of its location and the volume of damaged myocardium, regardless of the statute of limitations. Myocardial scintigraphy is a highly accurate method for evaluating the effectiveness of drug treatment, the effectiveness of endovascular interventions (coronary balloon angioplasty with stenting), open heart surgery (coronary artery bypass grafting), cardiac rehabilitation, including enhanced external counterpulsation and shock wave therapy. The approximate time of the study is 2-3 hours.

Skeleton bone scintigraphy

Skeleton bone scintigraphy (synonyms: osteoscintigraphy , scanning, bone scanning) is the leading radiation method for the diagnosis of osteoblastic bone metastases. Bone visualization is performed using technetium-99 labeled and phosphonates that are tropic to the bone tissue. The method allows with high sensitivity to detect bone metastases in cancer of the lung, breast, prostate, thyroid gland, cancer of the kidneys, bladder and other types of malignant neoplasms. It is also possible to visualize primary malignant neoplasms of bone tissue, including osteoma, osteosarcoma, chondrosarcoma, etc. The sensitivity of the method in the diagnosis of bone metastases is comparable to PET and MRI , at a significantly lower cost and time for direct examination. The use of SPECT / CT technology increases the sensitivity of the method, including in unclear situations and in the differential diagnosis of metastatic, traumatic and degenerative processes. A study is carried out on average 3 hours after the administration of the radiopharmaceutical. When analyzing images, not only the identification of focal changes in the bones characteristic of metastatic lesions is carried out, but also the activity of the accumulation of the drug in metastases is calculated, which allows us to evaluate the dynamics of the disease during treatment. The total study time is about four hours.

Kidney scintigraphy

Kidney scintigraphy (dynamic nephroscintigraphy with indirect angiography) is based on the use of radiopharmaceuticals tropic to the glomerulus and tubular system. Dynamic research allows real-time visualization of the accumulative and excretory function of each kidney individually. In the framework of indirect angiography, the speed and volume characteristics of renal blood flow are determined. Kidney scintigraphy provides important diagnostic information for patients with various diseases of the urinary system: to evaluate excretion in inflammatory kidney diseases and nephrolithiasis; determine the presence of renal failure and its severity, determine the indications for surgical treatment in patients with obstructive diseases of the urinary tract, determine the presence of vesicoureteral reflux. If there is a suspicion of renal artery stenosis, a diagnosis of renal blood supply disorders is performed. The duration of the study is less than 30 minutes.

Thyroid scintigraphy

Thyroid scintigraphy is performed to visualize the anatomy of the gland (including the retrosternal location of the lobes, the presence of additional lobes) and impaired function. The nodes are also visualized and their functional autonomy is determined: diagnostics of non-functioning ("cold") nodes, including those with suspected malignant neoplasm, and hyper-functioning ("hot") nodes, including toxic adenoma. The study takes about 20 minutes.

Parathyroid scintigraphy is used to detect hormone-producing adenomas in patients with an increase in parathyroid hormone, an increase in parathyroid glands, as well as with nephrolithiasis and osteoporosis. In addition to visualization of parathyroid adenoma, the anatomy and function of the thyroid gland, including autoimmune diseases, are evaluated as part of the study. The duration of the study is an average of 3 hours.

The use of SPECT / CT technology increases the sensitivity of methods for multinodular goiter, heterotopy of thyroid tissue, and the detection of atypically parathyroid adenomas.

Brain Scintigraphy

Single photon emission computed tomography of the brain is performed with radiopharmaceuticals (radiopharmaceuticals) that accumulate in proportion to cerebral blood flow. The study is carried out 20-30 minutes after the introduction of radiopharmaceutical. As a result, a topical diagnosis of a stroke, cerebral ischemia caused by damage to the cerebral arteries, perfusion disorders in neurodegenerative diseases is performed. The method allows to evaluate the effect of drug therapy, endovascular interventions on the carotid, vertebral and cerebral arteries, the effectiveness of rehabilitation measures. The duration of the study is less than 1 hour.

Lung scintigraphy

Currently, the main field of application of perfusion lung scintigraphy is the diagnosis of thromboembolism of the pulmonary artery and its branches. The use of a radiopharmaceutical of albumin macroaggregates labeled with technetium - 99 m, makes it possible to determine violations of the blood supply to the lungs, starting from the level of the great vessels (pulmonary arteries and their branches), and ending with microcirculatory disorders in systemic diseases, including primary pulmonary hypertension and Takayasu disease. As a result, in the presence of thrombosis or embolism of the pulmonary artery and its branches during lung scintigraphy, perfusion defects corresponding to the level of damage are detected. The method has great value in the dynamic control of the disease. With repeated studies, they can determine both signs of repeated thromboembolism and positive dynamics of perfusion with successful treatment. The duration of the study is about 20 minutes.

Liver and Gallbladder Scintigraphy

Scintigraphy of the liver and gallbladder is a complex radionuclide study aimed at identifying functional disorders in the hepatobiliary system. The study includes an assessment of the functional state of hepatocytes, the concentration and motor function of the gallbladder, patency of the biliary tract, the presence of dysfunction of the sphincter of Oddi, duodeno-gastric reflux. Indications for use: inflammatory and metabolic diseases of the liver, gall bladder, including cholecystitis, biliary dyskinesia, condition after surgical interventions on the hepatobiliary system. The time of the study is about 1 hour.

• http://medical-dictionary.thefreedictionary.com/scintigraphy
• http://www.medterms.com/script/main/art.asp?articlekey=9136
• https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/gamma-scintigraphy