Pat CT scan for breast cancer. Contrast-enhanced CT scan - what will the study show? Indications and contraindications for CT

Breast oncology - website – 2010

Computed tomography

Computed tomography is a method of radiation diagnostics, which consists in the fact that rays pass through a particular area of ​​the body at different angles. After this, the information enters the computer, where it is processed and an image of a tissue section at a certain depth is formed.

Computed tomography is a non-invasive method (does not require surgery), safe and used for many diseases. Your doctor may order a CT scan if you have a large breast tumor to find out whether the tumor is operable or not due to its growth into the chest wall.

This method is better than plain mammography because mammography may have layers of tissue in the image, causing a small tumor not to be visible.

The installations for performing computed tomography are similar to those used for magnetic resonance imaging.

During a computed tomography scan, the patient lies down on a special plane, which smoothly gradually enters the cylindrical chamber where the X-ray emitter and sensor are located. As each slice is imaged, the emitter and probe make an arc around the area of ​​the patient that needs to be examined. Information from the sensor immediately enters the computer, where it is processed, combined with other images, and the result is a complete picture of the layer of a particular organ at a certain depth.

On average, the procedure takes from 30 to 60 minutes, but can reach 2 hours. It depends on the scope of the study.

Possible complications of CT scan

Possible complications of computed tomography include the development of claustrophobia in some patients. In this case, it is recommended to prescribe sedatives before the study. In addition, with numerous X-ray (including tomographic) research methods there is a slight risk of developing malignant tumors.

Computed tomography is contraindicated during pregnancy.

Magnetic resonance imaging – MRI

Magnetic resonance imaging is a method for examining the mammary glands using a powerful magnetic field. In this case, the mammary glands are irradiated with electromagnetic waves in a strong magnetic field. The principle of the method is that this releases electromagnetic energy, which is then recorded using sensors and subjected to computer processing.

Advantages of magnetic resonance imaging:

• allows you to identify a palpable tumor in women, in cases where it is not detected by mammography or ultrasound.
• Allows you to identify pathological changes in the case of high density of mammary gland tissue.
• allows screening of young women at high risk of developing breast cancer due to family history or the presence of an abnormal gene.
• Sometimes magnetic resonance imaging successfully detects a tumor in women with enlarged axillary lymph nodes, when the doctor cannot feel the tumor in the thickness of the breast or it is not visible on mammography. In such cases, where mastectomy is usually recommended, MRI can accurately reveal the location of the tumor in the breast. This allows you to avoid removing the entire gland and limit yourself to only a lumpectomy (removal of the tumor) followed by radiation therapy.
• Helps determine which area the cancerous tumor is limited to and its spread to neighboring areas. This influences the choice of surgical treatment tactics, since if the tumor is widespread and multicentric, mastectomy is recommended. This is especially true for patients with invasive lobular carcinoma, since the form of cancer most often tends to be widespread.
• Helps in the assessment of scar tissue in the thickness of the mammary glands, which allows you to monitor the area where the lumpectomy was performed for the presence of early relapses.
• Capable of detecting silicone leakage from a breast implant, as this test method can easily distinguish silicone gel from normal surrounding tissue.
• In the case of metastatic breast cancer, magnetic resonance imaging helps to examine other areas of the patient's body for the presence of metastases and changes in organs. For example, if in this case the patient begins to experience back pain, weakness of the arms and legs, which is a possible sign of cancer metastasis to the spinal cord, a magnetic resonance imaging study of the spine is performed.

Before conducting a magnetic resonance examination, the doctor finds out whether there are any metal objects in the patient’s body, for example, artificial heart pacemakers, artificial metal joints. For such patients, magnetic resonance imaging is contraindicated. In addition, immediately before the examination procedure, a woman must remove all metal objects from herself - jewelry, clothes with metal buttons, etc.

Magnetic resonance imaging is carried out in a special narrow cylindrical chamber. As a result, some patients may experience claustrophobia when in confined spaces. Therefore, they are given a sedative if necessary.

How is magnetic resonance imaging performed?

The patient is placed in a strong magnetic field and exposed to electromagnetic radiation. The resulting electromagnetic energy is processed on a computer. This allows the milk tissue to be layered from different positions and angles. The magnetic field knocks out atomic particles in the tissues - protons, which are then accelerated by electromagnetic radiation and produce signals. These signals are received by sensors and further processed by computer. The result is a very clear image, allowing you to see fine details.

However, the magnetic resonance imaging method also has its drawbacks. First of all, this diagnostic method is expensive. Not all medical centers (even large ones) have equipment for this study. In addition, very often strange findings are found on magnetic resonance imaging.

Magnetic resonance imaging also cannot detect calcifications. In addition, the powerful magnetic field and electromagnetic radiation used during magnetic resonance imaging can damage a device such as an artificial pacemaker. Therefore, magnetic resonance imaging cannot serve as a diagnostic screening method.

Positron emission tomography

Positron emission tomography is a radionuclide tomographic method for studying internal organs. Positron emission tomography is successfully used in the diagnosis of patients with cancer metastases. The method is especially effective for assessing the condition of lymph nodes.

The positron emission tomography method is based on the fact that a special radiopharmaceutical is injected into the tissue. It contains radionuclides characterized by so-called positron beta decay. After the radiopharmaceutical has been administered, so-called “gamma quanta” are registered.

As already indicated, tumor cells are characterized by increased metabolism. this leads to the fact that they absorb the injected radiopharmaceutical from the blood faster and more strongly. Once the radioactive substance enters the tumor cell, its decay begins. During decay, special particles (quanta) are formed, which are recorded using special equipment. This method allows you to determine the area of ​​suspicious activity of cancer cells.

The positron emission tomography method allows us to clarify the following questions:

• Whether tumor cells remain after radiation therapy or chemotherapy.
• Is there spread of tumor cells to the lymph nodes?

Unfortunately, positron emission tomography also has disadvantages: this method can only be used to detect small tumors. In addition, positron emission tomography is a rather expensive diagnostic method; it is not available in all medical centers.

Computed tomography of the mammary glands is one of the diagnostic methods using x-rays. CT scan is an efficient and effective way to examine breast tissue. The received data is processed by a computer into a picture, which is deciphered by the doctor.

About the breast CT method

The computed tomography machine generates a directed narrow beam of rays. These rays pass through the body, moving in a spiral.

To record the results, the sensor moves in the device simultaneously with the ray source. It collects the information received and transmits it to the computer. There, in turn, the data is processed. The output is a three-dimensional model of the breast and all its components. This picture can be viewed layer by layer.

The slice of the three-dimensional model is responsible for the quality of recorded changes. The thinner it is, the more layers can be seen. Consequently, smaller changes in the breast are effectively recorded. This characteristic directly depends on the model of the device.

That is why, before signing up for a procedure, ask what device the study is being used on, what its power and capabilities are.

Main objectives of CT examination

In case of breast cancer, CT scan is of a clarifying nature. For testing for the presence of cancer in the breast, it is of an auxiliary nature.

CT is effective for clarifying and assessing information such as:

• confirmation or refutation of the diagnosis, both controversial and preliminary;
• choice of treatment tactics;
• the nature and extent of breast lesions;
• dynamic observation during the treatment period.

What does a breast CT scan show?

With this method of examining the mammary glands, you can see the glandular tissue, the condition of the lymph nodes, the ducts of the mammary gland, cartilaginous bone structures, cavities and vessels, and connective tissues. In addition, a breast CT scan detects both benign and malignant neoplasms.

Advantages compared to other methods:

• accurate visualization of tumor-like formations that are located in the space behind the gland or along its posterior edge;
• reviewing and measuring the size of the affected part of the gland in comparison with the healthy area;
• fixation of thickening of the skin and glands, which is caused by edematous forms of cancer;
• determining how much the tumor has grown throughout various breast structures;
• in case of cancer, it helps to choose a treatment method and the volume of surgery based on accurate data on the size and location of the tumor.

Indications for use

Computed tomography is usually performed as an addition or clarification to the diagnosis. If the nature of the tumor in the breast is unclear, computed tomography is the best diagnostic method. It can help more effectively evaluate situations where ultrasound and mammography do not provide complete information.

If the presence of any neoplasm is detected, the procedure is carried out as a determinant of the malignancy of the tumor. So, with actual confirmation, a CT scan can either confirm or refute the diagnosis.

When cancer progresses and metastases appear, CT scans are performed not only of the chest, but also of the abdominal cavity, as well as the brain. When metastases spread to other organs, CT results reveal the operability of the tumor.

The examination helps determine the possibility of surgical intervention for tumor formation. At the same time, thanks to a clear picture of the tumor, it is possible to immediately determine the course and extent of the operation.

Contraindications and effects on humans

Absolute contraindications to the procedure:

1. Pregnancy period: Breast CT is performed only in urgent cases when life is threatened.
2. Person weight over 120 kg: standard devices are not designed for heavier weights. For people whose weight exceeds 120 kg, a special tomograph model is required, which is quite rare.

1. Under 18 years of age: Children may only have a breast CT scan if there is a health risk to monitor for cancer.
2. Multiple myeloma.
3. Kidney failure.
4. Severe claustrophobia.

The tomograph is a narrow tube, that is, a limited space. To avoid the negative effects of claustrophobia, many hospitals offer CT scans under short-term anesthesia or sedation. This way, the patient will be able to calmly endure the examination and not worry that fear can lead to inappropriate behavior in the tomograph and distortion of the examination results.

The computed tomography method is a virtually harmless procedure. There are no side effects when irradiated with a tomograph. In rare cases, this radiation increases the risk of developing cancer.

CT scans use the lowest possible dose of radiation. This does not affect the condition of the body.

Risks during the examination

During the procedure, some radiation to the body occurs. That is why the procedure is contraindicated for pregnant girls. Radioactive radiation can cause congenital abnormalities in the fetus due to cell mutation. Therefore, computed tomography of the breast during pregnancy is used in conditions of urgent need.

During lactation, CT scanning is possible. In this case, after the procedure, you must stop feeding the child for 48 hours. You will have to express milk all this time.

When using the method of introducing contrast material into the blood, notify your doctor about any allergic reactions.

Preparing for CT

This examination does not require special preparation methods. In this case, you need to adhere to some rules and recommendations:

1. If a medical facility asks you to change out of your clothes into a sterile gown, then this rule must be followed. This precaution helps to avoid malfunctions of the tomograph.
2. Jewelry, metal objects, and a telephone must either not be taken for examination at all, or left in a specialized place in the hospital. This information should be clarified at the reception desk or with a doctor before the examination.
3. Sometimes diet adjustments are required. The doctor will warn you about this during your consultation before the CT scan. In some cases, a fasting diet is required for 12 hours before the examination.
4. If you suffer from claustrophobia, you need to warn your doctor about this. You will be given a sedative to calm you down.
5. If there are foreign objects in the body, you need to notify the radiologist. Foreign bodies that affect the course of computed tomography include implants, metal plates, neurostimulators, shunts, and pacemakers.

How is a breast CT scan performed?

To carry out diagnostics, a computed tomograph is used, which is located in a specialized room. The device looks like a cylindrical chamber. It contains both X-ray emitters and signal reception sensors.

The patient lies on a special flat surface on his back. Next, this surface smoothly enters the ring of the device. You must lie absolutely still during the procedure. Changes in body position significantly distort the final picture of the examination.

The procedure time is up to 1 hour. If additional examinations other than the breast are required, the time can be increased to 2 hours.

A radiologist monitors the progress of the examination. He is in the next room to avoid exposure to radiation to the body. The doctor looks at the data coming from the tomograph. The information is saved to the computer's hard drive. Thanks to this, you can view the result of a specific examination at any time.

Use of contrast agent

Most often, the procedure requires the use of a contrast agent. It is injected through a catheter into the patient's blood.

Saline solution can be used together with the contrast agent. It allows you to quickly and easily administer the contrast agent. After the procedure, the catheter is removed.

If you are predisposed to allergies, please notify your doctor before the procedure.

Results and doctor's opinions

A radiologist interprets the results of a breast CT scan. He studies the image on the screen. Thanks to this picture, the condition of the tissues, internal systems and organs of the chest is assessed. The picture looks like thin sections, which shows the chest area in different planes.

A conclusion based on the results of a CT scan of the breast is issued immediately after the examination. Sometimes it takes a doctor up to a couple of hours to decipher the data received and draw up a conclusion.

The resulting conclusion must be passed on to the attending physician. He will study the examination results in detail, make an accurate diagnosis and be able to select further treatment.

SPECT of the mammary glands

SPECT is single photon emission computed tomography. It allows you to most accurately obtain the result of the examination. It is a hybrid diagnostic technology.

This emission tomography method works by creating tomographic patterns of the distribution of radionuclides. This procedure uses radiopharmaceuticals (RPs). They are administered intravenously to the patient. The radiopharmaceutical is distributed through the blood throughout the body. The drugs are labeled with radioisotopes, which emit a photon with each radioactive decay. This is recorded by gamma camera detectors. The received data goes to the collection station and is compiled into an image.

Thanks to this technology, a complete 3D image of the chest cavity is formed. It displays the structure of the mammary glands layer by layer. This determines the presence of a tumor in the mammary gland, its stage of development, and severity. After SPECT, the most effective treatment is prescribed.

How often can you do a CT scan of the mammary glands?

When diagnosed using computed tomography, the body is exposed to x-rays. Therefore, the maximum number of examinations cannot exceed 2 times a year. More frequent diagnosis only contributes to the development of cancerous tumors.

Prices for CT

Computed tomography of the breast can be performed only if there is high-quality hardware and medical equipment in combination with the necessary qualifications of personnel. Due to the high cost of equipment, not all clinics can afford to perform this breast diagnostic method.

Prices by federal districts:

1. Central Federal District: 2500-15000 rub.
2. Northwestern Federal District: 4000-11500 rub.
3. Southern Federal District: 4500-11000 rub.
4. North Caucasus Federal District: 3500-10000 rubles.
5. Volga Federal District: 3500-9000 rubles.
6. Ural Federal District: 4000-10000 rubles.
7. Siberian Federal District: 3000-9000 rubles.
8. Far Eastern Federal District: 3000-8500 rub.

As you can see, the difference in average prices throughout Russia is insignificant. The average price for a breast examination varies depending on the region, but usually ranges from 4,000 to 9,000 rubles.

Examination of the mammary glands using computed tomography (CT) allows you to fully examine the structure of the chest area. This method is safe and does not involve side effects. Suitable for girls over 18 years of age who are not pregnant. When cancer cells are detected, a breast CT scan can reveal the volume and distribution of the tumor. This allows you to determine an accurate treatment plan. Due to its high efficiency and accuracy, breast CT is a popular diagnostic method. Clarifies information about lesions of the mammary glands when ultrasound and mammography cannot provide this.

Breast cancer is the most common malignant tumor in women around the world and in Russia. In the last decade, more than 50 thousand new cases of this type of cancer are registered annually in our country. In 2010, breast cancer ranked first both in terms of the incidence of malignant neoplasms in Russian women (20.5%) and in their mortality from malignant neoplasms (17.2%). Breast cancer is much less common in men than in women.

PET/CT diagnostics for breast cancer

High-quality screening is of great importance for early detection and effective treatment of breast cancer. If the disease is detected early, the chances of its successful treatment are significantly higher. Current methods for diagnosing breast cancer are based on mammography, ultrasound and biopsy identified neoplasm. PET/CT examination can show whether a breast mass is benign or malignant and can also provide useful complements to the data obtained from mammography. PET/CT may also provide additional benefits when evaluating patients with breast implants and women with non-standard breasts. This type of examination is effective in planning a biopsy.

Results of PET/CT examination with 18F-FDG. Focal formation
in the left mammary gland with metabolic activity
radiopharmaceutical.

PET/CT has shown high efficiency in detecting metastasis for breast cancer. This diagnostic method allows for precise staging of mammary and axillary lymph node involvement. Lymphadenectomy (removal) of axillary lymph nodes is currently a standard element of complex treatment of breast cancer, as this was the only way to adequately stage this disease in the absence of access to PET/CT diagnostics. However, lymphadenectomy can cause various complications, including decreased arm mobility, swelling, and pain. The use of PET/CT makes it possible not to perform lymphadenectomy in patients who do not have lymph node involvement.

You can ask a question about the use of PET/CT diagnostics
for breast tumors, our leading specialists:

Abashin Sergey Yurievich, MD, PhD, professor, oncologist, chemotherapy doctor, Moscow

Rucheeva Natalia Alexandrovna, Ph.D., Head. Department of Radionuclide Diagnostics, radiologist-radiologist, Moscow

Ivannikov Vitaly Valerievich, head of the “Radiation diagnostics” department, radiologist-radiologist, Moscow

The role of PET/CT in treatment

Treatment of breast cancer, like treatment of other types of cancer, depends significantly on the stage of the disease. In some cases, surgery may be recommended to remove the cancer, followed by radiation therapy, chemotherapy, or hormonal therapy.

Carrying out PET/CT examination in the nuclear center
medicine "PET-Technology", Moscow

PET/CT provides oncologists with additional information to better plan the nature and extent of chemotherapy. This diagnostic method also provides doctors with valuable information regarding the optimal localization of radiation therapy. The information provided by PET/CT serves to develop personalized treatment that takes into account the individual characteristics of the tumors of a particular patient.

Throughout the entire treatment program for a patient suffering from breast cancer, it is necessary to know how the body reacts to the therapy and whether it is effective. As a rule, metabolic changes occur earlier than anatomical ones. When PET/CT reveals a significant reduction in tissue uptake of radiopharmaceuticals (diagnostic drugs used to detect cancer), this indicates that the treatment is effective.

The information provided by PET/CT allows physicians to adequate monitoring of the effectiveness of antitumor therapy and provides the possibility of prompt adjustment, if the current antitumor effect does not meet the expectations of the patient and the doctor. Typically, the doctor performs a repeat PET/CT scan after 1-2 cycles of treatment and compares it with the results of the previous PET/CT scan. In any case, both during diagnosis and treatment of breast cancer, the decision on the timing of PET/CT is made by the attending physician.

PET/CT and postoperative follow-up

After completing a comprehensive treatment program for breast cancer, it is important to find out whether there are active cancer cells left in the patient’s body, that is, to carry out restaging. To do this, a PET/CT scan of the whole body is performed to detect the remains of a malignant neoplasm. With effective treatment and complete destruction of cancer cells, PET/CT does not detect foci of accumulation of radioactive glucose.

Often, on a CT scan, scar tissue at the site of surgery or radiation may appear abnormal. In such cases, a PET/CT study is helpful, allowing one to observe the accumulation of radioactive glucose in suspicious areas. Thanks to this, it becomes possible to differentiate healthy scar tissue from relapses of malignant neoplasms and residual effects of the disease. Applications of PET/CT Helps eliminate unnecessary biopsy and surgery in cases where mammography does not provide a clear understanding of the situation.

Benefits of PET/CT

PET/CT technology offers numerous benefits to breast cancer patients. PET/CT is a non-invasive type of examination used to stage breast cancer, localize the tumor, develop an optimal radiation therapy program, assess the response of the malignant neoplasm to treatment and detect relapses.

Advantages of PET-Technology nuclear medicine centers

The PET Technology company, thanks to the expert level of qualifications of its specialists and the availability of modern equipment, is able to provide the best quality of diagnosis, observation and therapy for patients suffering from breast cancer. The high-tech equipment we use helps ensure maximum diagnostic accuracy for this disease.

The following literature was used in preparing the material:
Conti, Peter S., Aarti Kaushik. PET-CT: A Case-Based Approach // Springer. – 2015.
Kim, E. Edmund, Myung-Chul Lee, Tomio Inoue, Wai-Hoi Wong. Clinical PET and PET/CT: Principles and Applications // Springer Science & Business Media. – 2012.
Peller, Patrick, Rathan Subramaniam, Ali Guermazi. PET-CT and PET-MRI in Oncology: A Practical Guide // Springer Berlin Heidelberg. – 2012.
Shreve, Paul, David W. Townsend. Clinical PET-CT in Radiology: Integrated Imaging in Oncology // Springer. – 2010. –
Waterstram-Rich, Kristen M., David Gilmore. Nuclear Medicine and PET/CT: Technology and Techniques // Elsevier Health Sciences. – 2016.

Positron emission tomography (PET) has recently become an increasingly popular research method used to detect, stage and monitor various malignant tumors. The method is based on recording gamma radiation emitted by radioactive elements (radionuclides), which are introduced into the human body as part of special labeled substances - radiopharmaceuticals (RP). When combining a PET scanner with one, they talk about combined positron emission and computed tomography (PET-CT).

The combination of PET and CT allows you to combine “functional” (PET) and “anatomical” (CT) tomograms, which provides advantages over using only CT, because anatomical sections are supplemented with information reflecting functional changes. Thus, when comparing the changes detected by PET-CT (58 patients took part in the study) with data obtained only on the basis of CT, combined PET-CT showed better results in identifying small tumors and multiple metastases; as well as in detecting tumor-affected lymph nodes and assessing response to chemotherapy for breast cancer.

What is the difference between CT and PET-CT for breast cancer?

Methods such as CT and MRI are based on visualization of anatomical structures in order to identify pathological changes in patients with breast cancer, staging and control. At the same time, positron emission tomography (PET) makes it possible to detect pathological changes in the metabolism of 18-fluoro-2-deoxy-D-glucose (FDG), which makes it possible to obtain high-quality information about its accumulation in the tumor, and is a critical point in the diagnosis diagnosis and during control studies. The combination of PET-CT has advantages over the isolated use of PET, since it becomes possible to more accurately assign foci of increased FDG uptake to specific anatomical areas. In addition, this method reduces the research time. PET-CT also makes it possible to partially overcome the limited specificity of PET, which can detect foci of glucose hypermetabolism in benign tumors and inflammatory tissues (for example, in tuberculosis). A necessary condition for the information content of the method is a reliable assessment of the images by an experienced radiologist, sometimes using.

Early diagnosis of breast cancer

Breast cancer is the most common neoplasm in women worldwide and the leading cause of cancer-related mortality in women. Worldwide, there are approximately 1.38 million new cases of the disease each year, as well as 458,000 annual deaths due to the disease. Many risk factors are well known. However, the exact causes of breast cancer have not been determined. For example, having the disease in relatives and ancestors is a well-known risk factor: it increases the likelihood of developing cancer by two or three times. It is also assumed that mutations in the BRCA gene (1 and 2) and mutations in the p53 protein significantly increase the risk of tumor development. Early diagnosis is a fundamental method of control, as it determines the method of treatment, as well as the patient’s prognosis and chances of survival.

How to detect breast cancer

Diagnostic methods based on the detection of anatomical changes include ultrasound examination (ultrasound), and. They are widely used in clinical practice to identify the primary tumor and determine the stage of breast cancer. These diagnostic methods are constantly improving, in addition, new methods of studying the mammary glands are also being introduced into practice: optical mammography, single photon emission tomography (SPECT) and positron emission tomography (PET), which allow transferring information regarding anatomical changes, function, metabolism from the macroscopic to the molecular level.

Radionuclide research methods, including SPECT and PET, make it possible to assess in vivo the cellular, molecular and biochemical features of neoplasms and normal tissues. While "anatomical" diagnostic methods emphasize increasing spatial resolution and image quality, the goal of using radionuclide methods is more specific - increasing the contrast between the tumor and normal tissues.

In combination with traditional radiation diagnostic methods, radionuclide research methods, which allow visualization of biological processes, have made it possible to take a step forward in cancer detection. And now the new goals of using radionuclide methods are to separate various biochemical changes in tissues.

Evaluation of the Primary Tumor

The ability to detect breast cancer using PET depends on the size and tissue structure of the tumor. The sensitivity of PET is reported to be 68% for small tumors (less than 2 cm), and 92% for larger tumors (2-5 cm), however, the overall accuracy for detecting cancer in situ is low (sensitivity is 2-25%) . Thus, the main factor limiting the use of PET in breast imaging is the low detection rate of small tumors and noninvasive cancers.

Ductal carcinoma insitu in a 49-year-old woman. A: Ultrasound reveals a hypoechoic mass formation measuring 2.5 cm with indistinct edges, located in the upper parts of the left breast (marked by arrows). B: PET-CT scan shows no evidence of increased FDG uptake in the left breast. Surgery confirmed non-invasive ductal carcinoma.

However, the method plays an important role for some groups of patients, for example, with dense mammary glands or with the presence of implants. Positron emission tomography is used to determine the multiplicity of tumor lesions; to identify the location of the primary tumor in patients with metastases, when mammography is uninformative; as well as in those patients for whom biopsy is contraindicated. PET-CT has potential advantages over isolated PET in the evaluation of small lesions that may show reduced FDG uptake due to the partial volume effect of PET, since glucose hypermetabolism can be characteristic of both pathological and normal anatomical structures.

Invasive breast cancer in a 57-year-old woman. A: a screening radiograph of the left breast in an oblique mediolateral projection reveals a space-occupying formation with spicule-shaped edges, about 1.1 cm in size (marked by an arrow). B: PET scan revealed a focus of mild FDG hypermetabolism (standardized uptake level = 1.2) in the left breast. The lesion is difficult to detect due to the partial volume effect. C: PET-CT identifies a focus of FDG hypermetabolism in a limited area (marked by an arrow) in the left mammary gland.

Assessment of secondary lymph node involvement

The second objective of the method is to detect breast cancer metastases in the lymph nodes. Metastatic lesions of the axillary lymph nodes are an important factor determining the prognosis. Patients suffering from breast cancer with secondary damage to four or more axillary lymph nodes have a significantly higher risk of relapse. PET sensitivity for imaging axillary lymph nodes in patients with breast cancer has been reported to range from 79% to 94% and specificity to 86% to 92%. With PET-CT, it is possible to accurately determine the location and distinguish from each other lymph nodes secondarily affected by the tumor and reactively changed (non-cancerous) lymph nodes, while CT will reveal only multiple enlarged lymph nodes of the axillary group without clear differential signs.

Axillary lymph node metastases in a 45-year-old woman with invasive ductal breast cancer. A: PET shows a focus of FDG hypermetabolism in the right gland (black arrow) and in the axillary region (white arrow). B: CT scan reveals two enlarged axillary lymph nodes on the right (marked by arrows). C: PET-CT allows you to determine the exact localization of lymph nodes secondarily affected by the tumor (white arrow, standardized level of radiopharmaceutical accumulation = 9.9); a reactively changed lymph node is also visualized (black arrow). Among 21 lymph nodes removed during surgery, metastases were detected in only one.

Metastases of breast cancer to intrathoracic or mediastinal lymph nodes often do not manifest themselves clinically. The number of detected pathological changes in intrathoracic or mediastinal nodes (in patients with metastatic or recurrent breast cancer) with PET is almost twice as large as compared with traditional CT. In addition, PET-CT appears to be more useful than CT for the evaluation of hilar and mediastinal lymph nodes, since the ability of CT to detect metastases in small lymph nodes is quite limited.

Metastases to the mediastinal lymph nodes in a woman who underwent a modified radical left mastectomy 10 months ago. A: PET scan reveals multiple areas of radiopharmaceutical hypermetabolism in the left upper chest. B: CT image shows a small area of ​​soft tissue density in the anterior mediastinum (marked with an arrow). B: PET-CT revealed that the soft tissue area in the anterior mediastinum identified on CT correlates with an area of ​​FDG hypermetabolism, suggesting metastases to the hilar lymph nodes.

Evaluation of distant metastases

Breast cancer often gives distant metastases to, and. The advantage of whole body PET over traditional diagnostic methods, such as chest radiography, skeletal scintigraphy and abdominal ultrasound, is the ability to detect distant metastases in various areas of the body and organs during one study. Whole body PET has been found by Moon et al to have high diagnostic accuracy in patients suspected of having recurrent or metastatic cancer. Based on the number of lesions detected, the sensitivity of the method in detecting distant metastases was 85% and the specificity was 79%.

Multiple distant metastases in a 44-year-old female patient suffering from cancer of both glands. A: PET scan shows multiple areas of FDG hypermetabolism in the chest and abdomen. B,C: PET also revealed areas of FDG hypermetabolism in both mammary glands (marked with white arrows on the tomogramB), in the lymph nodes of the mediastinum (marked with black arrows on the tomogramB), and in internal organs (marked with arrows on the tomogramC).

In a study (Cook et al.), PET was found to be superior to skeletal scintigraphy in detecting osteolytic metastases from breast cancer. Conversely, osteoblastic metastases are characterized by low metabolic activity and are often undetectable by PET. However, PET-CT overcomes this limitation: osteoblastic metastases, even if not visible on PET, will be visualized on CT scans.

Bone metastases in a 64-year-old woman who underwent right modified radical mastectomy 36 months ago. A: Skeletal scintigraphy reveals foci of FDG hyperfixation in the first rib on the right and the seventh rib on the left (arrows), which are most likely associated with metastatic disease of the ribs.B: PET-CT shows no FDG hypermetabolism in the left seventh rib (arrow).C: CT scan reveals an osteoblastic lesion on the left seventh rib (arrow).

Breast cancer treatment

To treat patients whose tumor is large or has local spread, neoadjuvant chemotherapy is used to reduce the stage of the primary tumor before surgery and eliminate metastases. In addition, several studies have demonstrated that survival of patients with refractory tumors may be improved by using alternative chemotherapy and/or by lengthening chemotherapy courses. Since chemotherapy has side effects, it is necessary to identify patients who do not benefit from the treatment as quickly as possible.

Currently, radiodiagnostic methods are often used to determine the response to therapy by assessing changes in tumor size. However, serial measurements of tumor size in many cases do not allow inferring the presence of an early response. The effectiveness of PET in assessing response to therapy has been confirmed for various types of neoplasms. A study by Smith et al showed that the mean reduction in FDG uptake after the first course of chemotherapy was greater in lesions that showed a macroscopic partial or complete response, or a microscopic complete response, compared with resistant lesions. in histopathological studies. According to (Rose et al.), after a single course of chemotherapy, positron emission tomography was able to predict complete response to therapy on pathological examination, with a sensitivity of 90% and a specificity of 74%. If we take the degree of decrease in FDG uptake less than 55% of the initial value as the threshold value indicating the presence of a response to treatment, changes in PET in all respondents in this study were correct and confirmed pathologically (100% sensitivity and 85% specificity).

Images illustrate chemotherapy management in a 35-year-old female patient with breast cancer with bone metastases. A-C: Initial PET (A, B) and PET-CT (C) show significant FDG hypermetabolism in both breasts and in many vertebrae.D-F: on control PET ( D,E) and PET-CT (F), performed after three courses of chemotherapy, a significant decrease in FDG hypermetabolism in both mammary glands and vertebrae is determined.

PET-CT also plays a role in radiotherapy because it allows accurate assessment of tumor extent.

Tumor recurrence control

Early recognition of tumor recurrence is important in improving survival by prompting clinicians to use different treatment modalities. However, it is difficult to distinguish a true relapse from postoperative and radiation changes when using only traditional methods of radiation diagnosis. With limited, regional relapse, the mammary gland, skin, axillary and supraclavicular lymph nodes, and the chest wall are predominantly affected.

The sensitivity and specificity of PET in detecting recurrence were found to be 84% and 78%, respectively, while the sensitivity and specificity of conventional imaging were 63% and 61%, respectively. PET has been suggested to be a more effective method for assessing breast cancer recurrence than traditional imaging techniques in detecting changes throughout the body. CT data obtained from PET-CT allow us to establish the correspondence of anatomical structures and foci of FDG hypermetabolism.

Local tumor recurrence in a 74-year-old woman who underwent a modified right radical mastectomy 8 years ago. A: Ultrasound revealed an ovoid-shaped mass, 1.4 cm, with increased blood flow, located in the right pectoral muscle in the mastectomy area. B, C: PET scan reveals a localized focus of FDG hypermetabolism (standardized uptake level = 3.3) (arrows) on the right side of the chest. D: PET-CT identifies a focus of FDG hypermetabolism (arrow) in the right pectoral muscle, while using PET alone is difficult to determine the exact location of the focus.

Deciphering PET-CT for breast cancer

In some cases, to increase the reliability of the assessment of PET-CT results, it is recommended to obtain a second opinion from a specialized radiologist. This may be necessary if the results of the initial reading of the images are dubious or ambiguous. A second opinion on PET-CT helps solve the following problems: reducing the risk of medical error, more reliable assessment of the primary tumor, clarifying the stage of the disease, reliably excluding signs of metastatic lesions of the bones, liver or lungs. In addition, as a result of such a consultation, the oncologist receives a more detailed description of the study, which helps him choose the most appropriate treatment protocol.

Conclusion

PET/CT plays an important role in the diagnosis of breast cancer, which consists of detecting and locating metastases, monitoring treatment and early detection of relapses. However, the limiting factor of PET/CT in detecting breast cancer is its insufficient ability to detect small tumors.

Vasily Vishnyakov, radiologist

Materials used in preparing the text:

https://www.researchgate.net/publication/5920836_The_role_of_PETCT_for_evaluating_breast_cancer

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4665546/