Positron Emission Tomography Combined With Computed Tomography Research Articles

Technical note: Can photon-counting CT improve PET/CT's quantitative accuracy?

Linear attenuation coefficients (LACs) in positron emission tomography combined with computed tomography (PET/CT) are derived from CT scans that utilize energy-integrating detectors (EID-CT). These LACs are inaccurate when iodine contrast has been injected. Photon counting detector CT (PCD-CT) may be able to improve the accuracy. To investigate whether PCD-CT can improve PET/CT quantitative accuracy. Two experiments were performed: one with CT only and one that combined PET and CT. The first experiment used an electron density phantom whose inserts were imaged with EID-CT and PCD-CT. The inserts simulated normal human tissues, including bone and iodinated blood. In the case of PCD-CT, virtual-monoenergetic images at 190keV were created. LACs were derived in each case and compared against known values. For inserts with iodine, more accurate LACs were expected with PCD-CT. The second experiment involved a custom PET phantom with various materials simulating human tissues (blood, iodinated blood, and bone) and 18F radioactivity. Data were first acquired with an EID-CT-based PET/CT system and then separately in a PCD-CT system without PET. PET images were reconstructed using LAC from EID-CT and PCD-CT. PET image values were compared against known activity values using recovery coefficients (RC). In the first experiment, LAC based on EID-CT were in error by as much as 18%, whereas the corresponding PCD-CT based measurements were within 3%. In the second experiment, minimum, maximum, and mean RC were (96.1%, 115.4%, and 103.8%) for the EID-CT method, and (95.8%, 105.5%, and 101.0%) for the PCD-CT method. The consistency of PET images in body and head orientations was improved. PCD-CT can acquire the information needed for accurate LAC for PET reconstruction in a single spiral acquisition.

Analysis of the performance of PET/CT using 18F-fluorodeoxyglucose in comparison with other diagnostic methods in drug-resistant epilepsy in children

Background. Epilepsy is one of the most common neurological diseases characterized by a persistent predisposition to epileptic seizures and the neurobiological, cognitive, psychological, and social consequences. In recent decades, despite the continuous development of antiepileptic drugs, there are still many patients with epilepsy that progresses to drug-resistant epilepsy. Currently, surgical treatment is one of the most important ways to treat such epilepsy. Collaboration between multidisciplinary teams and the combination of multiple neuroimaging methods are key to determining the exact localization of the epileptogenic zone. New diagnostic methods are being developed and the number of indications for their use is growing. The purpose of the study was to analyze the scientific literature on the effectiveness of positron emission tomography combined with computed tomography (PET/CT) using 18F-fluorodeoxyglucose compared to other diagnostic methods in drug-resistant epilepsy in children. Materials and methods. A literature search using keywords was conducted in Web of Science, Scopus, PubMed, and Elsevier databases. Results. Surgical treatment of drug-resistant epilepsy in children has become a specialized area in neurosurgery. Surgical removal or disconnection of a part of the brain, in which the epileptogenic zone is suspected, allows for a complete cure or a significant reduction in seizure frequency. It has been shown that a prerequisite for postoperative success is the accurate determination of the epileptogenic zone during a multistage preoperative diagnosis. Among many studies, nuclear medicine technologies play an important role in the presurgical examination of children with drug-resistant epilepsy. In combination with other methods, nuclear medicine helps identify the epileptogenic zone, especially in case of conflicting data, negative magnetic resonance imaging — negative epilepsy, focal cortical dysplasia or extratemporal lobe epilepsy. Single-photon emission CT and PET using functional neuroimaging with nuclear medicine indicators are classical methods and are recommended by neuroimaging specialists. In addition, one of the leading modern methods is PET/CT with 18F-fluorodeoxyglucose. It provides information that might be missed when using anatomical methods such as magnetic resonance imaging, and the area of hypometabolism detected with 18F-fluorodeoxyglucose PET/CT may be larger than the area of anatomical lesion detected on magnetic resonance imaging. Conclusions. For children with drug-resistant epilepsy, PET/CT using 18F-fluorodeoxyglucose is the most optimal method of preoperative diagnosis.

The impact of preliminary patient hydration on physiological [18F]PSMA-1007 uptake in the urinary bladder on PET/CT

Оne of the most commonly used fluorine‑18 labeled prostate-specific membrane antigen (PSMA) ligands in positron emission tomography combined with computed tomography (PET/CT) is [18F]PSMA‑1007. In comparison to other clinically available PSMA radioligands characterized by renal clearance, [18F]PSMA‑1007 exhibits predominantly hepatobiliary excretion. It allows a better assessment of the pelvic area in patients with prostate cancer (PCa). Nevertheless, in our clinical practice, we routinely observed a notably high [ 18F]PSMA‑1007 uptake in the urinary bladder. The underlying reasons for this phenomenon remain inadequately explored.Purpose of the study. The purpose of this study was to assess the impact of preliminary hydration of patients on [18F]PSMA‑1007 uptake in the urinary bladder.Materials and methods. Prospective, multicenter, randomized controlled study included 180 patients with PCa who underwent [18F]PSMA‑1007 PET/CT. Scans were performed using three different PET/CT-systems: GE Discovery IQ Gen 2 (USA), Siemens Biograph 64 mCT and Biograph 64 TruePoint (Germany). All patients were divided into two groups: the group with hydration (n = 95, 53 %), which included the subgroups of patients with oral (n = 76, 80 %) and intravenous (n = 19, 20 %) routes of hydration, and the control group with no hydration (n = 85, 47 %). [18F]PSMA‑1007 uptake in the urinary bladder was quantified using SUVmean (Mean Standardized Uptake value), measured within a spherical VOI with a fixed volume of 2.5 cm3 delineating the bladder boundaries. Additionally, the TBRmean (Mean Target-to-Background Ratio), reflecting the ratio between urinary bladder and right gluteal muscles SUVmean.Results. SUVmean and TBRmean in urinary bladder were significantly lower (p < 0,001) in the group with hydration compared to the control group, with the following values: 1.3 [0.8; 2.0] versus 4.5 [2.7; 8.5] for SUVmean and 4.0 [2.3; 6.3] versus 13.0 [7.7; 24.0] for TBRmean. There was no significant differences in SUVmean and TBRmean between the subgroups with oral and intravenous routes of hydration (p = 0.95 for SUVmean, p = 0.49 for TBRmean). Additionally, comparatively lower interquartile range (IQR) values for both SUVmean and TBRmean in the group with hydration were noted: 1.2 versus 5.8 for SUVmean, 4.0 versus 16.3 for TBRmean.Conclusion. Preliminary hydration of patients in uptake period significantly reduces both the level and variability of [18F]PSMA‑1007 uptake in the urinary bladder.

Diagnostic capabilities of PET/CT with <sup>18</sup>F-DOPA in biochemical recurrence of medullary thyroid carcinoma: a retrospective study

INTRODUCTION: Medullary thyroid carcinoma (MTС) is a rare neuroendocrine malignant neoplasm of the thyroid gland. In most cases, sporadic MTС is diagnosed at late stages due to the absence of specific symptoms. The main method of treatment of MTС is surgical — thyroidectomy and in most cases cervical lymphodissection. Current international guidelines suggest the use of basal calcitonin levels and cancer embryonic antigen (CEA) as markers of biochemical recurrence. In biochemical recurrence of the disease, it is advisable to search for tumor foci regardless of the level of cancer markers. Positron emission tomography combined with computed tomography (PET/CT) has the highest sensitivity and specificity for searching for local recurrence and distant metastases. Anatomical imaging methods (computed tomography (CT), magnetic resonance imaging (MRI)) have suboptimal sensitivity and specificity in detection of a recurrent tumor.OBJECTIVE: To explore the diagnostic capabilities of PET/CT with 18F-DOPA in patients with biochemical recurrence of medullary thyroid carcinoma, depending on the concentration of calcitonin in blood plasma.MATERIALS AND METHODS: To evaluate the diagnostic capabilities of PET/CT with 18F-DOPA in patients with biochemical recurrence of medullary thyroid carcinoma, 81 PET/CT studies were analyzed in patients after thyroidectomy. In most cases (76/81), at the time of the study, patients had elevated basal calcitonin levels (>10 pg/ml, including in 52/81 cases >150 pg/ml), which corresponded to a biochemical recurrence of the disease. In 6 cases, the calcitonin level was <10 pg/ml. PET/CT results were processed by visual image analysis, measurement of a semi-quantitative indicator of the maximal standardized level of radiopharmaceutical accumulation normalized to lean body mass (SUVlbm max) and the total volume of PET-positive tumor tissue (metabolic tumor volume).RESULTS: In 41 studies, foci of pathological accumulation of 18F-DOPA were identified, corresponding to recurrent tumor foci. DOPA-negative results in patients with elevated calcitonin levels were regarded as false negative. The highest sensitivity of the method was achieved at calcitonin levels >150 pg/ml. A noticeable positive correlation was found between the concentration of basal serum calcitonin, the number of pathological foci of 18F-DOPA hyperaccumulation and the total metabolic volume of tumor tissue. In most cases of biochemical recurrence, the PET method was superior to the CT method in detecting recurrent tumor foci.CONCLUSION: PET/CT with 18F-DOPA is the most informative method for molecular and structural imaging in patients with biochemical recurrence of medullary thyroid carcinoma. The results of the study directly correlate with the level of basal calcitonin in the blood.

Positron emission tomography in artificial stone silicosis

Artificial stone (AS) silicosis has emerged as a specially aggressive form of silicosis that can lead to pulmonary fibrosis and respiratory failure. The utility of positron emission tomography combined with computed tomography (PET/CT), an essential tool in oncological diseases that shows increased metabolic activity in neoplastic cells, is being evaluated in inflammatory pulmonary diseases. There are few publications about its use in silicosis, almost always referred to isolated cases in the context of studying a possible neoplasm. We present four cases of AS silicosis that underwent PET/CT and discuss its possible usefulness in this entity.

Automated multiclass segmentation, quantification, and visualization of the diseased aorta on hybrid PET/CT-SEQUOIA.

Cardiovascular disease is the most common cause of death worldwide, including infection and inflammation related conditions. Multiple studies have demonstrated potential advantages of hybrid positron emission tomography combined with computed tomography (PET/CT) as an adjunct to current clinical inflammatory and infectious biochemical markers. To quantitatively analyze vascular diseases at PET/CT, robust segmentation of the aorta is necessary. However, manual segmentation is extremely time-consuming and labor-intensive. To investigate the feasibility and accuracy of an automated tool to segment and quantify multiple parts of the diseased aorta on unenhanced low-dose computed tomography (LDCT) as an anatomical reference for PET-assessed vascular disease. A software pipeline was developed including automated segmentation using a 3D U-Net, calcium scoring, PET uptake quantification, background measurement, radiomics feature extraction, and 2D surface visualization of vessel wall calcium and tracer uptake distribution. To train the 3D U-Net, 352 non-contrast LDCTs from (2-[18F]FDG and Na[18F]F) PET/CTs performed in patients with various vascular pathologies with manual segmentation of the ascending aorta, aortic arch, descending aorta, and abdominal aorta were used. The last 22 consecutive scans were used as a hold-out internal test set. The remaining dataset was randomly split into training (n=264; 80%) and validation (n=66; 20%) sets. Further evaluation was performed on an external test set of 49 PET/CTs. The dice similarity coefficient (DSC) and Hausdorff distance (HD) were used to assess segmentation performance. Automatically obtained calcium scores and uptake values were compared with manual scoring obtained using clinical softwares (syngo.via and Affinity Viewer) in six patient images. intraclass correlation coefficients (ICC) were calculated to validate calcium and uptake values. Fully automated segmentation of the aorta using a 3D U-Net was feasible in LDCT obtained from PET/CT scans. The external test set yielded a DSC of 0.867±0.030 and HD of 1.0 [0.6-1.4] mm, similar to an open-source model with a DSC of 0.864±0.023 and HD of 1.4 [1.0-1.8] mm. Quantification of calcium and uptake values were in excellent agreement with clinical software (ICC: 1.00 [1.00-1.00] and 0.99 [0.93-1.00] for calcium and uptake values, respectively). We present an automated pipeline to segment the ascending aorta, aortic arch, descending aorta, and abdominal aorta on LDCT from PET/CT and to accurately provide uptake values, calcium scores, background measurement, radiomics features, and a 2D visualization. We call this algorithm SEQUOIA (SEgmentation, QUantification, and visualizatiOn of the dIseased Aorta) and is available at https://github.com/UMCG-CVI/SEQUOIA. This model could augment the utility of aortic evaluation at PET/CT studies tremendously, irrespective of the tracer, and potentially provide fast and reliable quantification of cardiovascular diseases in clinical practice, both for primary diagnosis and disease monitoring.

Management of idiopathic chylous peritonitis during laparoscopy: a case report and review of literature

Chylous ascites is rare. Etiology can be traumatic, atraumatic or idiopathic. We present a case of idiopathic peritonitis managed by laparoscopic drainage and a medium-chain triglyceride diet. We present a case of a 60-year-old white female who presented to the emergency department with diffused abdominal pain, migrated from the back, and clinical signs of peritonitis. Blood works showed high leukocytosis, and computed tomography showed a large amount of intraperitoneal and retroperitoneal fluid. During an emergency laparoscopy, a chylous ascites was seen and drained, but a causing factor was not identified intraoperatively. Postoperatively, medium-chain triglyceride diet was initiated for a period of 6 weeks, cytological, microbiological and chemical analysis showed elevated levels of triglycerides in absence of other disease. Multiple diagnostic tests revealed no malignancy nor another underlying pathological processes. patient recovered well with no complications. When confronted with chylous ascites, surgeons should drain the abdomen and do thorough evaluation. When no cause is found intraoperatively, surgeons should not take aggressive measures but instead initiate a medium-chain triglyceride diet and search for underlying causes by means of further laboratory testing and positron emission tomography combined with computed tomography (PET-CT). When no etiology is found, medium-chain triglyceride diet can be stopped with no reports of recurrence.

ПРИМЕНЕНИЕ ИНДЕКСА ТЯЖЕСТИ И ИНДЕКСА НЕОДНОРОДНОСТИ ПЕРФУЗИИ МИОКАРДА ДЛЯ ОЦЕНКИ ПЭТ-ИССЛЕДОВАНИЙ С РУБИДИЕМ-82.

Coronary artery disease (CAD) is one of the most common causes of mortality both in Russia and worldwide, which necessitates the development of diagnostic methods for detecting and localizing pathology in coronary vessels at the earliest stages. Among the non-invasive diagnostic methods, one of the most common and effective is myocardial perfusion imaging using single-photon emission computed tomography (SPECT), which, however, only allows for semi-quantitative assessment. Quantitative assessment is possible using positron emission tomography combined with computed tomography (PET/CT), including the use of 82Rb-chloride as a tracer. The aim of this study was to evaluate the feasibility of applying the SPECT technique proposed by Ansheles et al. in 2015, for the detection of early perfusion abnormalities, analyze the results obtained, and determine the differences in the use of the 15-segment and 17-segment myocardial division schemes in PET with rubidium-82 chloride. Materials and methods: PET studies with rubidium-82 chloride were conducted on 10 patients with symptoms of CAD but without coronary artery stenosis according to coronary angiography. Perfusion severity indices and perfusion heterogeneity indices were calculated for each patient using both the standard 17-segment model and the previously proposed 15-segment model. Results: Statistically significant differences between the 17-segment and 15-segment models were only observed when assessing the heterogeneity index at rest; in other cases, no statistically significant differences were found between the two models, indicating the possibility of using the 15-segment model for calculating quantitative parameters. Both models showed a lack of correlation between perfusion severity indices during rest and stress studies, which may allow for the use of this index in evaluating the presence of microvascular abnormalities. No statistically significant differences were found between men and women in the analysis of these indices...

PET/CT Reconstruction and Its Impact on [Measures of] Metabolic Tumor Volume

In oncological imaging, the use of metabolic tumor volume (MTV) for further prognostic differentiation and the development of risk adapted strategies appears promising. The aim of this analysis was to evaluate ultra-high definition (UHD) and ordered subset expectation maximization (OSEM) PET/CT reconstructions for their potential impact on different methods of MTV measurement. We analyzed positron emission tomography combined with computed tomography (PET/CT) scans of 40 Hodgkin lymphoma patients before first-line treatment who had undergone fluorodeoxyglucose (FDG) PET/CT. The MTVs were determined taking an SUV of 4.0 (MTV4.0) as a fixed threshold or 41% of the single hottest voxel (MTV41%) as an adaptive threshold for automated lymphoma delineation in both UHD and OSEM reconstructions. We then compared the absolute and relative differences between MTV4.0 and MTV41% in UHD and OSEM reconstructions. The relative distribution of MTV4.0 and MTV41% in relation to the reconstruction method applied was recorded and respective differences were tested for statistical significance using the paired sample t-test. A comparison of MTV4.0 and MTV41% showed smaller relative and absolute differences in MTV between different reconstruction settings for the MTV4.0 method. Conversely, the absolute as well as the relative differences between MTVs obtained from different reconstructions settings were significantly greater when the MTV41% method was applied (p<0001). MTV4.0 brings higher robustness between different reconstruction settings, while with MTV41% the deviation between volumes obtained with different reconstruction settings is greater. For clinical routine and for multicenter settings, the MTV4.0 therefore appears most promising.

ТЕХНОЛОГИИ ИСКУССТВЕННОГО ИНТЕЛЛЕКТА В ОЦЕНКЕ ПЕРФУЗИИ МИОКАРДА С ПОМОЩЬЮ ПОЗИТРОННОЙ ЭМИССИОННОЙ ТОМОГРАФИИ С ИСПОЛЬЗОВАНИЕМ 82Rb-ХЛОРИДА

At the moment, one of the most common causes of morbidity and mortality is coronary heart disease, which determines the need to develop methods for its diagnosis. Among diagnostic methods, non-invasive methods occupy a special place, in particular, determination of myocardial perfusion. One of the “gold standards” for assessing cardiac muscle perfusion is positron emission tomography combined with computed tomography (PET/CT) with 82Rb-chloride. Recently, attempts have been actively made to introduce the use of artificial intelligence in a variety of areas of medical clinical practice, including the development of medical decision support systems, as well as neural networks for assessing the results of diagnostic studies. In particular, there is information about attempts to use artificial intelligence in assessing myocardial perfusion using PET/CT with 82Rb-chloride. This paper analyzes the possibilities and prospects for using artificial intelligence in assessing the results of PET/CT with 82Rb-chloride. The use of well-trained neural networks and machine learning algorithms can significantly increase the accuracy of diagnosing coronary heart disease by improving the quality of images, analyzing the data obtained, or calculating characteristics and indicators, the quantitative interpretation of which may be difficult for a doctor. Neural networks are able to take into account in the prognosis both clinical and anamnestic data and additional parameters determined from research data, which the doctor may not pay attention to, which determines the relevance and prospects for the use of artificial intelligence in relation to the interpretation of 82Rb-PET/CT results.

Molecular Imaging of Radiation-Induced Lung Injury Using [18F]AlF Labeled Polypeptide Targeting C-X-C-Chemokine-Receptor-Type-4

Radiation-induced lung injury (RILI) is a severe side effect of radiotherapy (RT) for thoracic malignancies and we currently lack established means for the early detection of RILI. In this study, we synthesized a new tracer, [18F]AlF-NOTA-QHY-04, targeting C-X-C-chemokine-receptor-type-4 (CXCR4) and investigated the feasibility of using this tracer in positron emission tomography combined with computed tomography (PET/CT) for detecting RILI. An RILI model was established using a high-dose single RT (50 Gy/Fraction) to the right lung of female Wistar rats. Experimental animals were scanned with [18F]AlF-NOTA-QHY-04 PET/CT and [18F]FDG PET/CT at various time-points post-RT. MicroCT imaging was conducted weekly till 11 weeks post-RT. Dynamic, competition, autoradiography and histopathological studies were performed on day 14 post-RT. Biodistribution study was further performed on day 18 post-RT. Lung QHY-04 uptake was analyzed in twelve patients with radiation pneumonia, developed during or after thoracic RT. The yield of [18F]AlF-NOTA-QHY-04 was 28.5-43.2%, and the specific activity was 27-33 GBq/μmol. Significantly increased [18F]AlF-NOTA-QHY-04 uptake in the damaged lung compared with that in the normal lung was observed in the experimental animal model on 6 post-RT and peaked on day 14 post-RT (0.96 ± 0.06 vs. 0.50 ± 0.05 %ID/mL, P<0.05), whereas no apparent uptake of [18F]FDG was shown on day 7 and 15 post-RT. Significant intense [18F]AlF-NOTA-QHY-04 uptake was confirmed by autoradiography. No significant difference in CT density was observed between the damaged and normal lung tissues until six weeks post-RT. Immunofluorescence staining demonstrated expression of CXCR4 was significantly increased in the damaged lung tissue, which correlated with results obtained from hematoxylin-eosin and Masson's trichrome staining. Maximum standardized uptake values (SUVmax) were significantly higher in the irradiated lung compared with that in the normal lung in 12 patients with radiation pneumonia (3.07 ± 0.86 vs. 0.585 ± 0.17, P<0.001). SUVmax of patients with grade 2 RILI was significantly higher than that of patients with grade 1 RILI (3.30 ± 0.65 vs. 1.64 ± 0.08, P<0.05). This study indicated that [18F]AlF-NOTA-QHY-04 PET/CT imaging can detect RILI noninvasively and earlier than [18F]FDG PET/CT in a rat model. Clinical studies verified its' feasibility, suggesting the clinical potential of [18F]AlF-NOTA-QHY-04 as a PET/CT tracer for early monitoring of RILI.

Bone marrow composition features and possibilities of tumor involvement diagnosing in patients with classic Hodgkin’s lymphoma

Background. Classical Hodgkin’s lymphoma is a B-cell lymphoproliferative disease, the tumor substrate of which is Berezovsky–Reed–Sternberg cells, characterized by CD30, PAX-5, CD15 expression and the absence of CD3, CD45. In some cases, tumor cells express CD20. modern anticancer therapy has increased the survival probability for most patients, not only with early but also with advanced stages of classical Hodgkin’s lymphoma. Such successes are mainly due to the distribution of patients into prognostic groups and the choice of an appropriate treatment regimen. tumor infiltration of the bone marrow suggests assigning patients to the advanced stages group, followed by the choice of an intensive therapy program. Aim. To determine the bone marrow involvement frequency according to positron emission tomography combined with computed tomography (PET/CT), with 18F-fluorodeoxyglucose (FDG) and bone marrow trephine biopsy (bmtb), to compare the results obtained with primary tumor immunophenotype and bone marrow cellular composition, and to identify of prognostic risk factors. Materials and methods. The study included 107 patients with newly diagnosed classical Hodgkin’s lymphoma, who underwent a diagnostic examination at the moscow research institute of oncology named after P. A. Herzen – a branch of the National Medical Research Center for Radiology and the “Lapino” clinical Hospital from 2015 to 2022, followed by anticancer therapy and further follow-up. Morphology of the primary tumor biopsy specimen in all patients and immunohistochemical (IHC) study using a wide panel of monoclonal antibodies (CD15, CD30, CD3, CD45, CD20, PAX-5 anti-gens; in some cases epstein–barr virus proteins expression) in most cases were performed. All patients underwent a morphological and / or IHC study of BMTB and the majority underwent aspiration biopsy and PET/CT with 18F-FDG. Results. The most common histological variant of classical Hodgkin’s lymphoma was nodular sclerosis (86.9 %). The majority of patients (51.4 %) were assigned to the advanced stage prognostic group. bone marrow tumor infiltration was statistically significantly more frequently diagnosed during PET/CT with 18F-FDG compared with the results of the BMTB – in 27.1 % and 12.1 % of cases, respectively (p &lt; 0.05). when comparing the results of both diagnostic methods, it was found that in 17.1 % of cases, bone marrow infiltration, detected during PET/CT, was not confirmed by IHC examination of the trephine biopsy. In addition, it was found that the majority of cases with CD20+/± and CD15+/± expression in the primary tumor were observed in the group of patients without bone marrow involvement. when assessing the cellular composition of bone marrow aspirates, it was revealed that in patients with bone marrow tumor infiltration, an increase in cellularity and megakaryocytes number along with a decrease in the plasma cells number is observed. Conclusion. The results suggest further study of bone marrow immunomorphological features in order to identify prognostic factors and search for new therapeutic targets. a more extended analysis of bone marrow aspirate immunomor-phological characteristics using new modern diagnostic methods, minimal residual disease status as a surrogate marker seems to be relevant and necessary to confirm the depth of the antitumor response achieved. Detection of CD20+/±- and cd15+/±-Berezovsky–Reed–Sternberg cells according to primary tumor IHC analysis indicates a low probability of bone marrow tumor infiltration, but further analysis is required on a large clinical and laboratory material.

530 False Positive Rate from Pet-Ct in Cutaneous Malignant Melanoma – a Systematic Review and Meta-Analysis

Abstract Aim Cutaneous Malignant Melanoma (CMM) is increasing in incidence and is the leading cause of skin cancer mortality. Diagnosis involves primary excision followed by appropriate staging tests. Positron Emission Tomography combined with Computed Tomography (PET-CT) use has increased in recent years for clinical staging and detection of recurrence. False positive (FP) results are not uncommon and can have deleterious psychological, physical, and economic consequences. Few studies have quantified this. Thus, we present the first systematic review and meta-analysis of the pooled proportion of FP results in prospective studies of CMM and distribution of these by system. Method A systematic review and meta-analysis of FP results in prospective CMM PET-CT studies with distribution of FP results by body system. Results 14 studies were included with 851 patients. Primary reasons for exclusion were lack of FP reporting or studies being retrospective. Patient-based reporting had the lowest pooled proportion of 5.8% (95% CI = 3.5% to 8.6%), lesion-based was highest with 9.6% (95% CI = 3.1% to 19.1%) and combined was 6.9% (95% CI = 4.4% to 10.2%). Bias was low to unclear other than for FP reporting. Heterogeneity (I2) was considerable for all analyses. FP findings were mainly lymphatic, dermatological, respiratory, or skeletal. Conclusions Our data suggest that between 5.8% and 9.6% of PET-CT results are FPs; far higher than reported FP rates in current CMM literature. FP reporting was often inconsistent between studies and lacking in detail. Future work should include retrospective studies also and PET-CT research should consistently report FP results in more detail.

Atypical Uptake of 18&lt;sup&gt;F&lt;/sup&gt;DG in White Adipose Tissue During PET/CT in Children

Positron emission tomography combined with computed tomography (PET/CT) with 18F-fluoro-deoxyglucose (18F-FDG) plays an important role in the management of cancer patients and is mainly used for primary staging, evaluation of treatment response and detection of disease recurrence. Due to non-specific nature of 18F-FDG uptake, a radiologist must be familiar with both physiological and atypical distribution of radiopharmaceuticals. Inappropriate patient preparation for the study and/or taking certain drugs can lead to abnormal 18F-FDG distribution. Our clinical case demonstrates an atypical uptake of 18F-FDG in white adipose tissue in a child treated with glucocorticoids for a long time.

Pretreatment and Posttreatment Tumor Metabolic Activity Assessed by FDG-PET/CT as Predictors of Tumor Recurrence and Survival Outcomes in Early-Stage Non-Small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy

Stereotactic body radiation therapy (SBRT) is considered the standard of care for medically inoperable early-stage non-small cell lung cancer. There is mixed evidence on the prognostic significance of tumor metabolic activity assessed by positron emission tomography combined with computed tomography (PET/CT) using F-18 fluorodeoxyglucose (FDG). The objectives of this study were to evaluate the maximum standardized uptake value (SUVmax) pretreatment and at 3 and 6 months after SBRT for prediction of tumor control and survival outcomes. Consecutive patients from a single institution with T12N0M0 non-small cell lung cancer receiving primary treatment with SBRT with pretreatment FDG-PET/CT (n=163) and follow-up FDG-PET/CT at 3 or 6 months (n=71) were included. Receiver operator characteristic analysis was performed to dichotomize variables for Kaplan-Meier survival analysis. Multivariate analysis was performed with Cox proportional hazards regression. Median follow-up was 19 months. For the whole cohort, 1-year and 2-year local control, progression-free survival (PFS), and overall survival (OS) were 95.0% and 80.3%, 87.1% and 75.4%, and 67.0% and 49.6% respectively. The following pre-SBRT SUVmax cutoffs were significant: SUV > 4.0 for distant failure-free survival (adjusted hazard ratio [aHR], 3.33, P=.006), >12.3 for PFS (aHR, 2.80, P=.011), and >12.6 for OS (aHR, 3.00, P=.003). SUVmax decreases of at least 45% at 3 months (aHR, 0.15, P=.018), and 53% at 6 months (aHR, 0.12, P=.046) were associated with improved local failure-free survival. Pre-SBRT SUVmax cutoffs can predict distant failure, PFS, and OS. At both 3 and 6 months after SBRT, cutoffs for percentage change in SUVmax can potentially stratify risk of local recurrence.

Comparative assessment of 18F-PSMA-1007 biodistribution at 60 and 120 minutes after administration by PET/CT in prostate cancer patients

INTRODUCTION: Positron emission tomography combined with computed tomography (PET/CT) with prostate-specific membrane antigen-targeted (PSMA) radiopharmaceuticals is a valuable method for prostate cancer (PCa) imaging. Both 68Ga- and 18F-labelled PSMA ligands are used in clinical practice now, for example, 18F-PSMA-1007. Currently there is no consensus on time interval between 18F-PSMA-1007 administration and scanning start that served as the basis for this study. OBJECTIVE: The aim of this study was to determinate the optimal time interval between 18F-PSMA-1007 administration and scanning start at PET/CT in PCa patients. MATERIALS AND METHODS: This prospective analysis included the results of 18F-PSMA-1007 PET/CT of 26 patients with PCa (mean age — 69.1±7.1 years, mean PSA value — 3.9 (0.5; 10) ng/ml), 4 patients — at primary staging, 10 patients — with therapy assessment and 12 patients — with biochemical recurrence. The PET/CT scanning was performed at 60 and 120 minutes after 18F-PSMA-1007 administration with subsequent measurement and comparison of the pathological and physiological uptake. TBR value (Tumor-to-Background Ratio) was calculated for the pathological uptake in the prostate or prostate bed and lymph nodes lesions relative to the physiological uptake in urinary bladder and abdominal aortic blood pool respectively. Statistics: Statistical analysis was carried out using the software SPSS Statistics 28 to analyse the significance of the differences in median SUVmax (for pathological 18F-PSMA-1007 uptake), SUVmean (for physiological 18F-PSMA-1007 uptake) and TBR between two stages of scanning. RESULTS: There was a significant decrease of physiological 18F-PSMA-1007 uptake from median SUVmean 1.5 (1.0; 1.73) to 0.9 (0.5; 0.9), p&lt;0.001 in the abdominal aortic blood pool, 2.6 (1.3; 3.6) to 1.7 (1.1; 2.8), p&lt;0.05 in the urinary bladder, 0.4 (0.35; 0.44) to 0.33 (0.3; 0.37), p&lt;0.05 in the right gluteus medius muscle in the second scan. Moreover, there was a significant increase of physiological 18F-PSMA-1007 uptake from median SUVmean 8.9±2.8 to 10.3±3.4, p&lt;0.001 in the liver, 7.5±3.5 to 8.3±3.8, p&lt;0,001 in the spleen, 9.8±3.7 to 11.6±4.3, p&lt;0.001 in the right parotid salivary gland. Uptake in the bone marrow remained stable with median SUVmean 1 (0.8; 1.3), p=0.917. There was a significant increase of pathological uptake from median SUVmax 4.6 (2.7; 7.7) to 5.25 (3.2; 9.0), p&lt;0.001 in 76 lesions without appearance of new lesions in the second scan at 120 minutes. Mean TBR value also significantly increased for the ratios «prostate or prostate bed/urinary bladder» from 1.7 (1.1; 4.7) to 3.6 (2.1; 9.5), p&lt;0.05 and «lymph node/aortic blood pool»: per-lesion analysis from 2.8 (2.5; 5.2) to 6.2 (5; 10.1), p&lt;0.001 and per-patient analysis from 4,6 (2.7; 5.5) to 9.8 (4.9; 12.1), p&lt;0.05. DISCUSSION: It’s not justified to use time interval in 120 minutes routinely because of the lack of new lesions in the second scan, irrational spending of the department resources and time of medical staff. However, there was an increase in the TBR values indicating the higher quality of images in the second scan at 120 minutes. CONCLUSION: Due to the lack of clinical benefits of the 120 minutes interval and the associated time cost, a 60 minutes interval between 18F-PSMA-1007 administration and the start of a PET/CT scan in PCa patients is more optimal, however, delayed scan is justified in cases of obtaining unclear results.

PET/CT DISADVANTAGES IN PATIENTS WITH LYMPHOMA: А LITERATURE REVIEW

Relevance: Positron emission tomography combined with computed tomography (PET/CT) is a young and promising technique for lymphoproliferative diseases’ primary detection, staging, and evaluation of the treatment results. However, at this stage of nuclear medicine development, some shortcomings in PET/CT diagnostics of lymphomas using 18Fluorodeoxyglucose (F18-FDG) affect its reliability to a certain extent.&#x0D; The study aimed to evaluate the physical and technical weaknesses of F18-FDG PET/CT in diagnosing lymphomas and review the analytical methods that affect opinion accuracy.&#x0D; Methods: The articles on the use of F18-FDG PET/CT in diagnosing lymphomas, its reliability, and methods for optimizing were searched in the PUBMED database for 2012-2022.&#x0D; Results: One of the main shortcomings of F18-FDG PET/CT in diagnosing lymphomas is the Deauville 5-point scale, which does not fully meet clinical requirements. This scale has some disadvantages, including low inter-reader agreement and an unreliable reference organ for F18-FDG accumulation. Mathematical algorithms for correction to the patient’s weight also require optimization.&#x0D; Conclusion: Some of the existing deficiencies can be improved at the software level and through educating staff about the importance of changing the SUV calculation method. However, other deficiencies, such as classifications that do not meet clinical requirements, require more efforts at the level of international experts and much more in-depth study of this issue to avoid such shortcomings of new staging methods. However, even considering all the shortcomings described, at the moment, PET/CT with F18-FDG is one of the most reliable modalities available, both for the initial detection and for evaluating the therapy effectiveness in patients with lymphomas.

PET/CT DISADVANTAGES IN PATIENTS WITH LYMPHOMA: А LITERATURE REVIEW

Relevance: Positron emission tomography combined with computed tomography (PET/CT) is a young and promising technique for lymphoproliferative diseases’ primary detection, staging, and evaluation of the treatment results. However, at this stage of nuclear medicine development, some shortcomings in PET/CT diagnostics of lymphomas using 18Fluorodeoxyglucose (F18-FDG) affect its reliability to a certain extent.&#x0D; The study aimed to evaluate the physical and technical weaknesses of F18-FDG PET/CT in diagnosing lymphomas and review the analytical methods that affect opinion accuracy.&#x0D; Methods: The articles on the use of F18-FDG PET/CT in diagnosing lymphomas, its reliability, and methods for optimizing were searched in the PUBMED database for 2012-2022.&#x0D; Results: One of the main shortcomings of F18-FDG PET/CT in diagnosing lymphomas is the Deauville 5-point scale, which does not fully meet clinical requirements. This scale has some disadvantages, including low inter-reader agreement and an unreliable reference organ for F18-FDG accumulation. Mathematical algorithms for correction to the patient’s weight also require optimization.&#x0D; Conclusion: Some of the existing deficiencies can be improved at the software level and through educating staff about the importance of changing the SUV calculation method. However, other deficiencies, such as classifications that do not meet clinical requirements, require more efforts at the level of international experts and much more in-depth study of this issue to avoid such shortcomings of new staging methods. However, even considering all the shortcomings described, at the moment, PET/CT with F18-FDG is one of the most reliable modalities available, both for the initial detection and for evaluating the therapy effectiveness in patients with lymphomas.

Lung Stereotactic Body Radiation Therapy in a Patient with Severe Lung Function Impairment Allowed by Gallium-68 Perfusion PET/CT Imaging: A Case Report

Lung stereotactic body radiotherapy (SBRT) is increasingly proposed, especially for patients with poor lung function who are not eligible for surgery. However, radiation-induced lung injury remains a significant treatment-related adverse event in these patients. Moreover, for patients with very severe COPD, we have very few data about the safety of SBRT for lung cancer. We present the case of a female with very severe chronic obstructive pulmonary disease (COPD) with a forced expiratory volume in one second (FEV1) of 0.23 L (11%), for whom a localized lung tumor was found. Lung SBRT was the only possible treatment. It was allowed and safely performed, based on a pre-therapeutic evaluation of regional lung function with Gallium-68 perfusion lung positron emission tomography combined with computed tomography (PET/CT). This is the first case report to highlight the potential use of a Gallium-68 perfusion PET/CT in order to safely select patients with very severe COPD who can benefit from SBRT.

The role of PET/CT in oncogynecology (literature review)

Purpose: to consider the modern possibilities of positron emission tomography combined with computed tomography (PET/CT) with FDG in the diagnosis of oncological formations in gynecology.Materials and methods. Search, selection and evaluation of existing foreign and domestic research included in the peer-reviewed E-library, PubMed, GoogleScholar, Scopus.Results. This article summarizes the existing evidence base to establish the clinical relevance and new possibilities for the use of FDG PET/CT in common gynecological malignancies.Conclusion. The use of FDG PET/CT can have a significant impact on patient management by improving cancer staging, influencing patient choice for treatment, and detecting early disease recurrence.