The effect of retroaortic left renal vein on lumbar osteophytes formation.

PURPOSE: Assess whether a Retroaortic left renal vein (RLRV) affects vertebral osteophyte formation in the lumbar spine, compared to normal anatomy left renal vein. METHODS: We conducted a retrospective case-control study. Computed tomography (CT) scans of individuals with a RLRV (study group) were compared to age- and gender-matched normal anatomy CT scans (control group). L1 to L4 vertebral levels were appreciated for: left renal vein level, osteophyte presence and the aorta-vertebral distance (AVD) at the left renal vein level. Univariate analyses were conducted using Chi-square test and Fisher's test for categorical variables, and Student's t-test for continuous variables. Logistic regression was used for multivariate analyses. RESULTS: A total of 240 patients were included in the study - equally distributed between the study and control groups. Normal anatomy left renal veins traversed the spine only at the L1 and L2 levels. RLRVs traversed the spine in all L1-L4 levels, mostly at the L3 and L2. Osteophyte prevalence at the level of left renal vein was significantly higher in the study group, compared with the control group [OR 2.54, P = 0.01]. Mean AVD was greater in the study group [9.2 mm ±3.6 mm Vs. 3.5 mm ± 2.6 mm, P < 0.001]. Increased AVD was found to be associated with a higher chance of osteophyte presence at the level of the left renal vein [OR 1.282, P = 0.025]. CONCLUSIONS: Osteophytes are more prevalent at the level of the RLRV variant compared to the normal anatomy. Furthermore, the RLRV is characterized by a lower lumbar level compared to the normal anatomy. CLINICAL RELEVANCE STATEMENT: This anatomic variation could assist in further understanding of osteophyte formation.

Women's Representation in RCTs Evaluating FDA-Supervised Medical Devices: A Systematic Review.

This systematic review evaluates the representation of women in randomized clinical trials (RCTs) of US Food and Drug Administration (FDA)­supervised medical devices.

Impact of Open Access status on journal metrics in infectious diseases and clinical microbiology - A cross-sectional study.

INTRODUCTION: While Open Access (OA) journals provide free access to articles, they entail high article processing charges (APC), limiting opportunities for young researchers and those from low-middle income countries to publish OA. METHODS: Cross-sectional study, evaluating APC and academic impact of full OA (FOA) journals in infectious diseases (ID) and clinical microbiology (CM) compared to hybrid journals. Data were collected from Journal Citation Reports and journals' websites. RESULTS: Among 255 journals, median APC was 2850 (interquartile range [IQR] 1325-3654$). Median APC for 120 FOA journals was significantly lower than for 119 hybrid journals (2000, IQR 648-2767$ versus 3550, IQR 2948-4120$, p < 0.001). FOA journals had lower citation numbers and impact metrics compared to hybrid journals. CONCLUSION: While FOA ID/CM journals have lower APCs, they also lower academic impact compared to hybrid journals. These findings highlight the need for reforms in the publication process in view of achieving equitable data dissemination.

Findings on emergent magnetic resonance imaging in pregnant patients with suspected appendicitis: A single center perspective.

This study's aim is to describe the imaging findings in pregnant patients undergoing emergent MRI for suspected acute appendicitis, and the various alternative diagnoses seen on those MRI scans. This is a single center retrospective analysis in which we assessed the imaging, clinical and pathological data for all consecutive pregnant patients who underwent emergent MRI for suspected acute appendicitis between April 2013 and June 2021. Out of 167 patients, 35 patients (20.9%) were diagnosed with acute appendicitis on MRI. Thirty patients (18%) were diagnosed with an alternative diagnosis on MRI: 17/30 (56.7%) patients had a gynecological source of abdominal pain (e.g. ectopic pregnancy, red degeneration of a leiomyoma); 8 patients (26.7%) had urological findings such as pyelonephritis; and 6 patients (20%) had gastrointestinal diagnoses (e.g. abdominal wall hernia or inflammatory bowel disease). Our conclusions are that MRI is a good diagnostic tool in the pregnant patient, not only in diagnosing acute appendicitis, but also in providing information on alternative diagnoses to acute abdominal pain. Our findings show the various differential diagnoses on emergent MRI in pregnant patients with suspected acute appendicitis, which may assist clinicians and radiologists is patient assessment and imaging utilization.

Hypermetabolic Axillary Lymphadenopathy After Shingrix Vaccination for Varicella Zoster Virus.

ABSTRACT: A 67-year-old woman underwent staging 18 F-FDG PET/CT scan for recently diagnosed breast cancer. Her scan showed a highly hypermetabolic right breast mass, with ipsilateral hypermetabolic axillary lymph nodes. The contralateral axillary lymph nodes were also enlarged with avid FDG uptake, alongside focal increased uptake in the left deltoid muscle. Upon investigation, the patient reported receiving the new zoster recombinant adjuvanted varicella zoster vaccine (Shingrix, GlaxoSmithKline) 4 days before the scan. The lymph node uptake could be potential pitfall for cancer staging.

Retrospectively assessing evaluation and management of artificial-intelligence detected nodules on uninterpreted chest radiographs in the era of radiologists shortage.

PURPOSE: High volumes of chest radiographs (CXR) remain uninterpreted due to severe shortage of radiologists. These CXRs may be informally reported by non-radiologist physicians, or not reviewed at all. Artificial intelligence (AI) software can aid lung nodule detection. Our aim was to assess evaluation and management by non-radiologists of uninterpreted CXRs with AI detected nodules, compared to retrospective radiology reports. MATERIALS AND METHODS: AI detected nodules on uninterpreted CXRs of adults, performed 30/6/2022-31/1/2023, were evaluated. Excluded were patients with known active malignancy and duplicate CXRs of the same patient. The electronic medical records (EMR) were reviewed, and the clinicians' notes on the CXR and AI detected nodule were documented. Dedicated thoracic radiologists retrospectively interpreted all CXRs, and similarly to the clinicians, they had access to the AI findings, prior imaging and EMR. The radiologists' interpretation served as the ground truth, and determined if the AI-detected nodule was a true lung nodule and if further workup was required. RESULTS: A total of 683 patients met the inclusion criteria. The clinicians commented on 386 (56.5%) CXRs, identified true nodules on 113 CXRs (16.5%), incorrectly mentioned 31 (4.5%) false nodules as real nodules, and did not mention the AI detected nodule on 242 (35%) CXRs, of which 68 (10%) patients were retrospectively referred for further workup by the radiologist. For 297 patients (43.5%) there were no comments regarding the CXR in the EMR. Of these, 77 nodules (11.3%) were retrospectively referred for further workup by the radiologist. CONCLUSION: AI software for lung nodule detection may be insufficient without a formal radiology report, and may lead to over diagnosis or misdiagnosis of nodules.

Immunotherapy in mismatch repair-deficient metastatic colorectal cancer - Outcome and novel predictive markers.

BACKGROUND: This study aims to assess predictive markers for response to immunotherapy in dMMR/MSI-H metastatic colorectal cancer (mCRC) patients. MATERIALS AND METHODS: A study using two prospective cohorts from MD Anderson Cancer Center and Sheba Medical Center of consecutive patients with dMMR/MSI-H mCRC that were treated with immunotherapy between 2014-2022. Primary outcome was progression-free survival (PFS) and secondary outcome was overall response rate (ORR). Evaluated predictors included ECOG-PS score, RAS/BRAF status, single-agent versus doublet immunotherapy, metastatic sites, disease burden, and CEA levels prior to treatment initiation. Kaplan-Meier analysis and Cox proportional hazard regression model were used to analyze the effect of exposure variables on PFS. RESULTS: The study included 153 patients. Median follow-up time was 26 months (IQR 11-48). Median PFS was 51.6 months (95%CI 38.1-NR) and ORR was 58.1%. In a univariate analysis, male sex was associated with worse PFS with a HR of 1.67 (95% CI 1.00-2.79); Right-sided tumors were associated with improved PFS with a HR of 0.56 (95% CI 0.32-0.97); Liver or lung metastasis were associated with worse PFS with HRs of 2.35 (95%CI 1.43-3.88) and 2.30 (95%CI 1.31-4.04), respectively; ECOG-PS score ≥ 2, CEA levels ˃5 µg/L prior to treatment initiation and ≥ 3 metastatic sites were associated with worse PFS with HRs of 2.09 (95%CI 0.98-4.47), 2.23 (95%CI 1.30-3.81) and 3.11 (95%CI 1.61-6.03), respectively. Liver or lung metastasis remained significant in a multivariable model. CONCLUSIONS: Extent of disease (worse PFS with high CEA, poor ECOG-PS and ≥3 metastatic sites) and disease location (worse PFS with liver or lung metastasis and left sided tumor) were associated with immunotherapy outcome in dMMR/MSI-H mCRC.

Immunogenicity and Safety of Modified Vaccinia Ankara (MVA) Vaccine-A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Prevention of mpox has become an important public health interest. We aimed to evaluate the safety and immunogenicity of the Modified Vaccinia Ankara (MVA) vaccine. We conducted a systematic review and meta-analysis of randomized-controlled trials (RCTs) comparing MVA versus no intervention, placebo, or another vaccine. Outcomes included safety and immunogenicity outcomes. We also performed a systematic review of RCTs evaluating various MVA regimens. Fifteen publications were included in the quantitative meta-analysis. All but one (ACAM2000) compared MVA with placebo. We found that cardiovascular adverse events following two MVA doses were significantly more common compared to placebo (relative risk [RR] 4.07, 95% confidence interval [CI] 1.10-15.10), though serious adverse events (SAEs) were not significantly different. Following a single MVA dose, no difference was demonstrated in any adverse event outcomes. Seroconversion rates were significantly higher compared with placebo after a single or two doses. None of the RCTs evaluated clinical effectiveness in preventing mpox. This meta-analysis provides reassuring results concerning the immunogenicity and safety of MVA. Further studies are needed to confirm the immunogenicity of a single dose and its clinical effectiveness. A single vaccine dose may be considered according to vaccine availability, with preference for two doses.

The impact on clinical outcomes after 1 year of implementation of an artificial intelligence solution for the detection of intracranial hemorrhage.

BACKGROUND: To assess the effect of a commercial artificial intelligence (AI) solution implementation in the emergency department on clinical outcomes in a single level 1 trauma center. METHODS: A retrospective cohort study for two time periods-pre-AI (1.1.2017-1.1.2018) and post-AI (1.1.2019-1.1.2020)-in a level 1 trauma center was performed. The ICH algorithm was applied to 587 consecutive patients with a confirmed diagnosis of ICH on head CT upon admission to the emergency department. Study variables included demographics, patient outcomes, and imaging data. Participants admitted to the emergency department during the same time periods for other acute diagnoses (ischemic stroke (IS) and myocardial infarction (MI)) served as control groups. Primary outcomes were 30- and 120-day all-cause mortality. The secondary outcome was morbidity based on Modified Rankin Scale for Neurologic Disability (mRS) at discharge. RESULTS: Five hundred eighty-seven participants (289 pre-AI-age 71 ± 1, 169 men; 298 post-AI-age 69 ± 1, 187 men) with ICH were eligible for the analyzed period. Demographics, comorbidities, Emergency Severity Score, type of ICH, and length of stay were not significantly different between the two time periods. The 30- and 120-day all-cause mortality were significantly reduced in the post-AI group when compared to the pre-AI group (27.7% vs 17.5%; p = 0.004 and 31.8% vs 21.7%; p = 0.017, respectively). Modified Rankin Scale (mRS) at discharge was significantly reduced post-AI implementation (3.2 vs 2.8; p = 0.044). CONCLUSION: The added value of this study emphasizes the introduction of artificial intelligence (AI) computer-aided triage and prioritization software in an emergent care setting that demonstrated a significant reduction in a 30- and 120-day all-cause mortality and morbidity for patients diagnosed with intracranial hemorrhage (ICH). Along with mortality rates, the AI software was associated with a significant reduction in the Modified Ranking Scale (mRs).

Retracted publications in infectious diseases and clinical microbiology literature: an analysis using the retraction watch database.

OBJECTIVES: We aimed to examine the rate and characteristics of retracted articles in infectious diseases and clinical microbiology. METHODS: Using the Retraction Watch Database, we conducted a cross-sectional study for retracted publications categorized as 'Infectious Disease' or 'Microbiology' until June 30 2022. We included publications for which citation information was available through the Web of Science database. Study characteristics, retraction trends and number of citations before and after the retraction year were analysed. RESULTS: Overall, 1004 retracted publications were included, retracted between August 1968 and June 2022. The number of retractions climbed through the years, peaking in 2020-2021. A total of 614 retractions originated from USA, China, and India, of total 183 736 PubMed publications from these countries. Overall, 378 (38%) were retracted because of errors; 182 (18%) because of plagiarism; and 142 (14%) because of falsification/fabrication. Specific reasons included 'concerns/issues about data' (158, 16%); 'duplication of image' (127, 13%); and 'unreliable results' (116, 12%). Of the 347 retractions during 2020 to June 2022, 91 (26%) were COVID-19 related. Fifty of 895 (5.6%) first authors had two retracted papers, and 14 (1.6%) had ≥2 retractions. Of 824 publications cited at least once, 466 (57%) were cited more often after retraction. DISCUSSION: Retractions of infectious diseases and clinical microbiology publications are increasing. Concerning reasons such as plagiarism, falsification/fabrication and errors are not uncommon. Nonetheless, these publications continue to be commonly cited after being retracted.

Trabecular Bone Score Change Is Not Predicted by Bone Turnover: Short-term Sequential Follow-up.

BACKGROUND: Trabecular bone score (TBS) reflects vertebrae microarchitecture and assists in fracture risk assessment. The International Society of Clinical Densitometry postulates that the role of TBS in monitoring antiresorptive therapy is unclear. Whether changes in TBS correlate with bone resorption measured by bone turnover markers is not known. OBJECTIVES: To determine whether longitudinal changes in TBS correlate with C-terminal telopeptide (CTX) of type I collagen. METHODS: Examinees with two bone mineral density (BMD) measurements were detected via the institutional database. Over 5.8% change in TBS was considered least significant and patients were grouped accordingly (increment, decrement, or unchanged). CTX, BMD, co-morbidities, incident fractures, and medication exposure were compared between the groups by Kruskal-Wallis. The correlation between TBS and BMD change and CTX in a continuous model was analyzed by Pearson's correlation coefficient. RESULTS: In total, 110 patients had detailed medical records. In 74.5%, TBS change was below least significant change. Two other TBS categories, fracture incidence or medication exposure, did not differ by CTX. In the continuous model, BMD and TBS change was positively correlated (r = 0.225, P = 0.018). A negative correlation was observed between BMD change and CTX. The decrease in BMD level was associated with higher CTX (r = -0.335, P = 0.004). No correlation was observed between CTX and TBS. CONCLUSIONS: No correlation between TBS dynamics and bone resorption marker was found. Clinical interpretation and implication of longitudinal TBS changes should be further explored.

The Role of 68 Ga-FAPI PET/CT in Breast Cancer Response Assessment and Follow-Up.

PURPOSE: 68 Ga-fibroblast activation protein inhibitor (FAPI), a new PET/CT radiotracer targeting cancer-associated fibroblasts in tumor microenvironment, can detect many types of cancer. We aimed to assess whether it can also be used for response assessment and follow-up. METHODS: We followed up patients with FAPI-avid invasive lobular breast cancer (ILC) before and after treatment changes and correlated qualitative maximal intensity projection images and quantitative tumor volume with CT results and blood tumor biomarkers. RESULTS: Six consenting ILC breast cancer patients (53 ± 8 years old) underwent a total of 24 scans (baseline for each patient and 2-4 follow-up scans). We found a strong correlation between 68 Ga-FAPI tumor volume and blood biomarkers ( r = 0.7, P < 0.01), but weak correlation between CT and 68 Ga-FAPI maximal intensity projection-based qualitative response assessment. CONCLUSIONS: We found a strong correlation between ILC progression and regression (as assessed by blood biomarkers) and 68 Ga-FAPI tumor volume. 68 Ga-FAPI PET/CT could possibly be used for disease response assessment and follow-up.

Interrupted inferior vena cava with deep vein thrombosis.

A 22-year-old healthy man presented to the emergency department with worsening left flank and testicular pain. Lower abdominal pain and lower urinary tract symptoms, were also noted. Contrast-enhanced CT demonstrated several vascular malformations: both common iliac veins converging to an infrarenal inferior vena cava (IVC) with an absent cephalad IVC. Multiple collateral veins were noted, and both the Azygos and Hemiazygos veins were seen dilated, serving as an alternative venous drainage path due to the interrupted IVC. The patient's CT was also notable for several pathologies: bilateral iliac vein thrombosis and left-sided testicular vein thrombus with surrounding fat stranding, suggestive of testicular vein thrombophlebitis. The patient was admitted, and received antibiotic and anticoagulation treatment, with clinical improvement. Hypercoagulability work-up was obtained, and the patient was found to be heterozygous for Factor V Leiden. Interrupted IVC with azygos continuation is an uncommon, and mostly a benign vascular malformation, resulting from abnormal development of IVC-contributing segments during embryogenesis. It is associated with lower limb deep vein thombosis and hypercoagulable states. It is imperative for radiologists to be acquainted with this entity, in order to avoid misdiagnosis. Testicular vein thrombosis is uncommon, mostly associated with prothrombotic disorders, and it should be considered when coagulopathy is suspected.

The Role of 68 Ga-FAPI PET/CT in Detection of Metastatic Lobular Breast Cancer.

PURPOSE: Invasive lobular breast cancer (ILC) may be hard to detect using conventional imaging modalities and usually shows less avidity to 18 F-FDG PET/CT. 68 Ga-fibroblast activation protein inhibitor (FAPI) PET/CT has shown promising results in detecting non- 18 F-FDG-avid cancers. We aimed to assess the feasibility of detecting metastatic disease in patients with non- 18 F-FDG-avid ILC. METHODS: This prospective study included patients with metastatic ILC, infiltrative to soft tissues, which was not 18 F-FDG avid. The patients underwent 68 Ga-FAPI PET/CT for evaluation, which was correlated with the fully diagnostic CT performed at the same time. RESULTS: Seven women (aged 57 ± 10 years) were included. Among the 30 organs and structures found to be involved by tumor, the number of findings observed by FAPI PET/CT was significantly higher than that observed by CT alone ( P = 0.022), especially in infiltrative soft tissue and serosal locations. CONCLUSIONS: This small pilot trial suggests a role for 68 Ga-FAPI PET/CT in ILC, which needs to be confirmed by subsequent trials.

CT signs of hypovolemic shock complex in patients with non-traumatic shock.

PURPOSE: To assess the frequency of hypovolemic shock complex (HSC) signs on CT in patients who presented to the emergency department (ED) with undifferentiated non-traumatic shock. Secondary aim was to assess the correlation between HSC signs and all-cause mortality. METHODS: This retrospective, single-center study included 100 patients who underwent contrast-enhanced thoraco-abdominal CT in the ED to evaluate the etiology for non-traumatic undifferentiated shock. All patients were retrospectively assigned a shock subtype (i.e., distributive, cardiogenic, hypovolemic, obstructive, multifactorial, and unknown) based on medical records. Patients' demographics and time to all-cause mortality up to 90 days were collected. All CT studies were re-assessed for the presence of HSC signs. Correlation between HSC signs, mortality and shock subtype was assessed. RESULTS: Overall, 58% (58/100) of all patients had at least one HSC sign. Flattened inferior vena cava and adrenal hyper-enhancement were the most common HSC signs (27.3%, 27/99; in both). Overall mortality was 59% (59/100). When evaluated separately, shock liver was the only HSC sign to significantly correlate with increased mortality (84.6% vs. 55.2%, p = .04). However, patients with at least two HSC signs had a significantly higher mortality rate compared to patients without any HSC signs (73.5% vs. 45.2%, p = .017). CONCLUSION: Most patients with non-traumatic shock had at least one HSC sign. Mortality rates were significantly higher in patients with two or more HSC signs compared to patients without any signs. Patients with shock liver sign had significantly higher mortality rates.

Underrepresentation of women in randomized controlled trials: a systematic review and meta-analysis.

BACKGROUND: Although regulatory changes towards correcting the underrepresentation of women in randomized controlled trials (RCTs) occurred (National Institutes of Health 1994), concerns exist about whether an improvement is taking place. In this systematic review and meta-analysis, we aimed to assess the inclusion rates of women in recent RCTs and to explore the potential barriers for the enrollment of women. METHODS: RCTs published in 2017 examining any type of intervention in adults were searched in PubMed and Cochrane Library. The following predefined medical fields were included: cardiovascular diseases, neoplasms, endocrine system diseases, respiratory tract diseases, bacterial and fungal infections, viral diseases, digestive system diseases, and immune system diseases. Studies were screened independently by two reviewers, and an equal number of studies was randomly selected per calendric month. The primary outcome was the enrollment rate of women, calculated as the number of randomized women patients divided by the total number of randomized patients. Rates were weighted by their inverse variance; statistical significance was tested using general linear models (GLM). RESULTS: Out of 398 RCTs assessed for eligibility, 300 RCTs were included. The enrollment rate of women in all the examined fields was lower than 50%, except for immune system diseases [median enrollment rate of 68% (IQR 46 to 81)]. The overall median enrollment rate of women was 41% (IQR 27 to 54). The median enrollment rate of women decreased with older age of the trials' participants [mean age of trials' participants ≤ 45 years: 47% (IQR 30-64), 46-55 years: 46% (IQR 33-58), 56-62 years: 38% (IQR 27-50), ≥ 63 years: 33% (IQR 20-46), p < 0.001]. Methodological quality characteristics showed no significant association with the enrollment rates of women. Out of the 300 included RCTs, eleven did not report on the number of included women. There was no significant difference between these studies and the studies included in the analysis. CONCLUSIONS: Women are being inadequately represented, in the selected medical fields analyzed in our study, in recent RCTs. Older age is a potential barrier for the enrollment of women in clinical trials. Low inclusion rates of elderly women might create a lack of crucial knowledge in the adverse effects and the benefit/risk profile of any given treatment. Factors that might hinder the participation of women should be sought and addressed in the design of the study.

Liver Attenuation Assessment in Reduced Radiation Chest Computed Tomography.

OBJECTIVE: This study aimed to evaluate the reliability of liver and spleen Hounsfield units (HU) measurements in reduced radiation computed tomography (RRCT) of the chest within the sub-millisievert range. METHODS: We performed a prospective, institutional review board-approved study of accrued patients who underwent unenhanced normal-dose chest CT (NDCT) and with an average radiation dose of less than 5% of NDCT. In-house artificial intelligence-based denoising methods produced 2 denoised RRCT (dRRCT) series. Hepatic and splenic attenuations were measured on all 4 series: NDCT, RRCT, dRRCT1, and dRRCT2. Statistical analyses assessed the differences between the HU measurements of the liver and spleen in RRCTs and NDCT. As a test case, we assessed the performance of RRCTs for fatty liver detection, considering NDCT to be the reference standard. RESULTS: Wilcoxon test compared liver and spleen attenuation in the 72 patients included in our cohort. The liver attenuation in NDCT (median, 59.38 HU; interquartile range, 55.00-66.06 HU) was significantly different from the attenuation in RRCT, dRRCT1, and dRRCT2 (median, 63.63, 42.00, and 33.67 HU; interquartile range, 56.19-67.19, 37.33-45.83, and 30.33-38.50 HU, respectively), all with a P value <0.01. Six patients (8.3%) were considered to have fatty liver on NDCT. The specificity, sensitivity, and accuracy of fatty liver detection by RRCT were greater than 98.5%, 50%, and 94.3%, respectively. CONCLUSIONS: Attenuation measurements were significantly different between NDCT and RRCTs, but may still have diagnostic value in appreciating hepatosteastosis. Abdominal organ attenuation on RRCT protocols may differ from attenuation on NDCT and should be validated when new low-dose protocols are used.

FDG PET/CT radiomics as a tool to differentiate between reactive axillary lymphadenopathy following COVID-19 vaccination and metastatic breast cancer axillary lymphadenopathy: a pilot study.

OBJECTIVES: To evaluate if radiomics with machine learning can differentiate between F-18-fluorodeoxyglucose (FDG)-avid breast cancer metastatic lymphadenopathy and FDG-avid COVID-19 mRNA vaccine-related axillary lymphadenopathy. MATERIALS AND METHODS: We retrospectively analyzed FDG-positive, pathology-proven, metastatic axillary lymph nodes in 53 breast cancer patients who had PET/CT for follow-up or staging, and FDG-positive axillary lymph nodes in 46 patients who were vaccinated with the COVID-19 mRNA vaccine. Radiomics features (110 features classified into 7 groups) were extracted from all segmented lymph nodes. Analysis was performed on PET, CT, and combined PET/CT inputs. Lymph nodes were randomly assigned to a training (n = 132) and validation cohort (n = 33) by 5-fold cross-validation. K-nearest neighbors (KNN) and random forest (RF) machine learning models were used. Performance was evaluated using an area under the receiver-operator characteristic curve (AUC-ROC) score. RESULTS: Axillary lymph nodes from breast cancer patients (n = 85) and COVID-19-vaccinated individuals (n = 80) were analyzed. Analysis of first-order features showed statistically significant differences (p < 0.05) in all combined PET/CT features, most PET features, and half of the CT features. The KNN model showed the best performance score for combined PET/CT and PET input with 0.98 (± 0.03) and 0.88 (± 0.07) validation AUC, and 96% (± 4%) and 85% (± 9%) validation accuracy, respectively. The RF model showed the best result for CT input with 0.96 (± 0.04) validation AUC and 90% (± 6%) validation accuracy. CONCLUSION: Radiomics features can differentiate between FDG-avid breast cancer metastatic and FDG-avid COVID-19 vaccine-related axillary lymphadenopathy. Such a model may have a role in differentiating benign nodes from malignant ones. KEY POINTS: • Patients who were vaccinated with the COVID-19 mRNA vaccine have shown FDG-avid reactive axillary lymph nodes in PET-CT scans. • We evaluated if radiomics and machine learning can distinguish between FDG-avid metastatic axillary lymphadenopathy in breast cancer patients and FDG-avid reactive axillary lymph nodes. • Combined PET and CT radiomics data showed good test AUC (0.98) for distinguishing between metastatic axillary lymphadenopathy and post-COVID-19 vaccine-associated axillary lymphadenopathy. Therefore, the use of radiomics may have a role in differentiating between benign from malignant FDG-avid nodes.