Objectives: to assess the possibility of using ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in patients with carcinoma of unknown primary (CUP); to determine the effectiveness of PET/CT for detecting a primary tumor lesion in patients with a histologically verified diagnosis of CUP and the contribution of PET/CT procedure to the process of disease staging in these patients.
Material and methods. From September 2018 to March 2019, the retrospective study included a total of 187 patients (64 (34.2%) females and 123 (65.8%) males) diagnosed with CUP. The patients’ mean age was 61.9 ± 7.5 years. Before PET/CT, all the patients underwent puncture biopsy of at least one metastatic lesion, which histologically verified the malignant nature of the neoplasm. A number of conventional studies were also performed as part of an oncosearch to identify the nature of a primary cancer lesion.
Results. Biopsy of lymph node metastases in 187 patients included in the study showed the following distribution according to the histological types of the tumor: 87 (46.5%) patients were diagnosed with squamous cell carcinoma, 15 (8%) with melanoma, 45 (24.1%) with undifferentiated carcinoma, 23 (12.3%) with adenocarcinoma, 17 (9.1%) with undifferentiated malignant neoplasm. The examination could identify a primary tumor site in 93 (49.7%) patients; no primary source was found in 94 (50.3%) patients. After PET/CT, there were no significant differences in the age of patients with and without CUP. PET/CT revealed new, previously undetected metastatic lesions in 93 cases, accounting for 49.7% of the entire sample. It is worth noting that after PET/CT, a change in the stage of tumor development tool place in 131 (70.1%) cases, which was associated with both the detection of the primary tumor and the identification of new metastatic lesions. The stage change was significantly more frequently observed in patients with detected CUP than in those with undetected CUP (100% vs. 40.4%; p < 0.001).
Conclusion. PET/CT can more accurately determine the stage of cancer in a large proportion of patients with CUP. The technique is able to identify the primary tumor in a significant number of cases, which in turn affects treatment policy and prognosis in these patients. The use of PET/CT should be obligatorily included in the examination protocol for patients with CUP.

Acute mesenteric ischemia is an acute disruption of blood supply to part of the intestine, which, if untreated, leads to bowel wall necrosis and a patient’s death. Computed tomography (CT) plays a leading role in detecting mesenteric ischemia and in making the initial diagnosis, especially in patients with chronic critical illness, when productive contact is impossible. The final diagnosis is established during surgery or postmortem examination. Timely diagnosis and surgical treatment are a basic tool to reduce high mortality rates from this disease. The article presents the possibilities of CT in imaging and making the primary diagnosis of mesenteric ischemia and mesenteric thrombosis.

The early and complete diagnosis of lung carcinoid tumors is of great interest in clinical oncology, since this is the basis for the possibility of using options for organ-sparing surgical treatment. According to the 2015 WHO classification, carcinoids belong to the group of neuroendocrine tumors and are divided into two types: a typical carcinoid and an atypical one. Based on the data available in the literature, there are from 0.2 to 2 cases per 100,000 population. The paper considers the possibilities of radiation studies in the early diagnosis of this tumor, as well as those of determining the tactics, type, and scope of surgical treatment.

Androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone agonists is the basis for drug treatment in patients with metastatic prostate cancer (PC). An accurate assessment of the response of the tumor and its metastases is of primary importance for making a clinical decision regarding the continuation of treatment, changing the line of drugs or the nature of therapy. The presented clinical case illustrates the possibilities of ^99mTc-pyrophosphate skeletal scintigraphy for monitoring the response of PC bone metastases to ADT. The efficiency of hormone therapy with Triptorelin has been confirmed by positive changes in the visual and quantitative scintigraphic signs that manifest the metabolic activity of bone tissue in the area of a metastatic lesion. This was manifested by a marked decrease in the intensity of ^99mTc-pyrophosphate accumulation in the foci of bone pathology, by a reduction in the number of visualized hot foci, and by a gradual normalization of the scintigraphic pattern. This variant of the metabolic response of bone metastases to ADT correlated with the positive changes in laboratory parameters, as well as with the signs of reversal of the tumor and its metastases, as evidenced by magnetic resonance imaging.

At the present stage of scientific and technological progress, high-dose radiotherapy has become a common way to combat severe cancers. However, this treatment option is limited by normal tissues radiosensitivity. The developed technology of ultrashort pulse delivery of a dose of ionizing radiation to the zone of interest (FLASH radiotherapy) can achieve a high local control over tumor growth while sparing healthy tissues. This review summarizes the experimental findings supporting the possibility of transitioning to clinical studies of FLASH radiotherapy.

The review presents data on the comparison of the features of liver and spleen stiffness measurements and those on the impact of various conditions on the measurement results (the type of a sensor used, food intake, number of measurements, patient position, breathing phase, etc.). Literature has been sought in the PubMed and eLibrary databases. In particular, the liver and spleen stiffness values vary differently at the height of inspiration and expiration. This is due to organ engorgement with a change in intrathoracic and intraabdominal pressures, as well as to a reduction in splenic arterial flow during exhalation. The review gives published data on liver and spleen stiffness values in healthy volunteers. The spleen is a stiffer organ than the liver. The different liver and spleen stiffness is explained by the features of blood supply (the spleen receives the most blood supply from the intensive-flow artery; the liver does from the portal vein). The reasons for increasing the stiffness of these organs in both health and disease are described. Estimation of liver stiffness can be used to diagnose cirrhosis and portal hypertension. That of spleen stiffness can help in the diagnosis of portal hypertension and in the indirect diagnosis of the presence of esophageal varices and the nature of a splenic lesion.

The possibilities of rational use of iodine radiopaque agents in computed tomography and percutaneous coronary interventions are considered, taking into account the route, method of their administration and the viscosity of their solutions. When fixing the rate of iodine administration and the temperature of the injected solution, the required injection pressure of the contrast media is determined by the solution viscosity.