PET-CT Research Articles

P031 An case of cryofibrinogen associated necrotising cutaneous vasculitis on background of aortitis

Abstract Background/Aims Cryofibrinogen is an abnormal protein that forms precipitate in plasma but not in serum. Cryofibrinogenaemia can be detected in healthy individuals and patients with autoimmune diseases, cancer, and infections. Current data suggest that isolated cryofibrinogenaemia can be detected in up to 3% of healthy individuals and it is usually asymptomatic. However, cryofibrinogenaemia can be associated with systemic inflammatory manifestations, of which cutaneous involvement is the most prominent. Methods A 76-year-old male patient presented with acute and progressive necrotising ulcers in the lower limbs along with high inflammatory markers and general decline. He had a background of large vessel vasculitis (aortitis), which was diagnosed with a PET-CT scan three years prior to the current presentation. He was previously treated with oral steroids and eight cycles of cyclophosphamide demonstrating an excellent response with complete resolution of the aortitis on the follow-up PET-CT scan. The patient had remained on maintenance treatment with azathioprine (3mg/kg) as well as therapeutic anticoagulation for atrial fibirillation. Results After thorough investigations for an infective cause and poor response to broad spectrum antibiotics, he was reviewed further for recurrence of large vessel vasculitis. A CT angiogram showed concentric symmetrical soft tissue thickening surrounding the thighs and lower limb arteries without luminal stenosis, suggestive of periarterial inflammation. A further MR angiogram of the aorta did not confirm any evidence of aortic, iliac or visceral artery stenosis. A CT chest/abdomen/pelvis excluded any other pathology or malignancy. Additional investigations showed negative ANA and ENA screen, rheumatoid factor, antiphospholipid antibodies, cryoglobulins, hepatitis virus screen, whilst complement and immunoglobulin levels were normal. However, cryofibrinogen was reported positive and a diagnosis of cryofibrinogen-associated necrotising cutaneous vasculitis was concluded. The patent was started on IV cyclophosphamide (15mg/kg) along with IV methylprednisolone (250mg for the first 3 doses) along with each pulse therapy. After the first two pulses, the patient had a favourable clinical and serological response to the immunosuppressive treatment with improvement in cutaneous lesions and significant reduction in the inflammatory markers. He subsequently underwent an angioplasty for tightly stenotic/occluded tibioperoneal trunk with good recanalisation. Conclusion This is a rare overlap syndrome of new-onset small vessel necrotising cutaneous vasculitis on previous background of large vessel disease (aortitis). In most severe cases with essential cryofibrinogenaemia, the mainstay treatment is with corticosteroids and other immunosuppressive agents in combination with oral anticoagulants and/or low-dose aspirin. Post treatment, the risk of relapse remains high and immunosuppressive therapy may only have a limited impact on the course of thrombotic vasculopathy in the absence of inflammation. More research and longitudinal data are required to optimise treatment protocols and outcomes in patients with cryofibrinogen-associated systemic vasculitis. Disclosure A. Psarras: None. J. David: None. R. Luqmani: None. S. Dubey: Consultancies; Boehringer Ingelheim. Member of speakers’ bureau; Janssen.

E046 Lytic lesions; metastatic disease or gout?

Abstract Background/Aims Uric acid crystal deposition in the spine is uncommonly diagnosed, although the frequency of axial involvement is thought to be as high as 14-35%. Studies have shown that spinal gout is more common in men aged 35-75 years, with a history of chronic polyarticular tophaceous gout which is not optimally controlled being a key risk factor. Recent studies have shown that spinal gout is under and misdiagnosed due to its non-specific presentation of back pain or absence of symptoms. Our case report exemplifies this diagnostic challenge. Methods In this report we describe a case of a 79-year-old male with a history of polyarticular tophaceous gout, chronic kidney disease and previous renal carcinoma treated with curative radiotherapy. He presented with a 4-week history of progressive exertional dyspnoea and orthopnoea. He was commenced on intravenous diuretics which lead to an acute kidney injury, with his eGFR dropping to 14mL/min. His preadmission allopurinol and colchicine were held and clinically he developed a flare of gout affecting his right wrist and right second and third MCP joints. A CT scan of his abdomen and pelvis, carried out to investigate potential bowel obstruction, showed no evidence of obstruction but it did reveal multiple lytic lesions in the spine with potential extension into the spinal canal at T9 and L5. He did not have any back pain and his neurological examination was normal. Results A working diagnosis of spinal metastasis with potential cord compression was made and the patient was commenced on high dose steroids. He subsequently underwent an MRI whole spine which showed marrow abnormalities and destructive soft tissues changes affecting various facet joints in the thoracic and lumbar spine. The primary differential remained metastases but due to the unusual distribution of the marrow changes in which the vertebral bodies were completely spared, the initial CT images were reviewed on spectral scanning which demonstrated uric acid deposition in the affected facet joints. The diagnosis was confirmed as gout in the spine when a PET-CT scan revealed no potential primary source of malignancy. The gout flare in his hand settled with the steroids prescribed to treat the potential cord compression and he continued to deny suffering from back pain. Conclusion A literature search demonstrates that reports of spinal gout being described as lytic lesions on CT are rare. Spinal gout should be considered as a differential in a patient with facet joint lytic lesions on imaging, without involvement of the vertebral body and where no primary malignancy is found. Our case demonstrates how dual energy CT scanning can prevent the need for invasive biopsy in cases of diagnostic uncertainty in patients with a history of poorly controlled chronic tophaceous gout. Disclosure S.K. Stewart: None. D.J. Coulter: None. C. Masih: None.

Thrombus or tumor? A case report of a rare sarcoma entity: intimal sarcoma of the pulmonary arteries

BackgroundTumor embolism is a very rare primary manifestation of cancers and the diagnosis is challenging, especially if located in the pulmonary arteries, where it can mimic nonmalignant pulmonary embolism. Intimal sarcoma is one of the least commonly reported primary tumors of vessels with only a few cases reported worldwide. A typical location of this malignancy is the pulmonary artery. Herein, we present a case report of an intimal sarcoma with primary manifestation in the pulmonary arteries.Case summaryA 53-year-old male initially presented with dyspnea. On imaging, a pulmonary artery embolism was detected and was followed by thrombectomy of the right ventricular outflow tract, main pulmonary artery trunk, and right pulmonary artery after ineffective lysis therapy. Complementary imaging of the chest and abdomen including a PET-CT scan demonstrated no evidence of a primary tumor. Subsequent pathology assessment suggested an intimal sarcoma further confirmed by DNA methylation based molecular analysis. We initiated adjuvant chemotherapy with doxorubicin. Four months after the completion of adjuvant therapy a follow-up scan revealed a local recurrence without distant metastases.DiscussionPrimary pulmonary artery intimal sarcoma (PAS) is an exceedingly rare entity and pathological diagnosis remains challenging. Therefore, the detection of entity-specific molecular alterations is a supporting argument in the diagnostic spectrum. Complete surgical resection is the prognostically most important treatment for intimal cardiac sarcomas. Despite adjuvant chemotherapy, the prognosis of cardiac sarcomas remains very poor. This case of a PAS highlights the difficulty in establishing a diagnosis and the aggressive natural course of the disease.ConclusionIn case of atypical presentation of a pulmonary embolism, a tumor originating from the great vessels should be considered. Molecular pathology techniques support in establishing a reliable diagnosis.

New full-counts phase-matched data-driven gated (DDG) PET/CT.

Data-driven gated (DDG) PET has gained clinical acceptance and has been shown to match or outperform external-device gated (EDG) PET. However, in most clinical applications, DDG PET is matched with helical CT acquired in free breathing (FB) at a random respiratory phase, leaving registration, and optimal attenuation correction (AC) to chance. Furthermore, DDG PET requires additional scan time to reduce image noise as it only preserves 35%-50% of the PET data at or near the end-expiratory phase of the breathing cycle. A new full-counts, phase-matched (FCPM) DDG PET/CT was developed based on a low-dose cine CT to improve registration between DDG PET and DDG CT, to reduce image noise, and to avoid increasing acquisition times in DDG PET. A new DDG CT was developed for three respiratory phases of CT images from a low dose cine CT acquisition of 1.35mSv for a coverage of about 15.4cm: end-inspiration (EI), average (AVG), and end-expiration (EE) to match with the three corresponding phases of DDG PET data: -10% to 15%; 15% to 30%, and 80% to 90%; and 30% to 80%, respectively. The EI and EE phases of DDG CT were selected based on the physiological changes in lung density and body outlines reflected in the dynamic cine CT images. The AVG phase was derived from averaging of all phases of the cine CT images. The cine CT was acquired over the lower lungs and/or upper abdomen for correction of misregistration between PET and FB CT as well as DDG PET and FB CT. The three phases of DDG CT were used for AC of the corresponding phases of PET. After phase-matched AC of each PET dataset, the EI and AVG PET data were registered to the EE PET data with deformable image registration. The final result was FCPM DDG PET/CT which accounts for all PET data registered at the EE phase. We applied this approach to 14 18F-FDG lung cancer patient studies acquired at 2min/bed position on the GE Discovery MI (25-cm axial FOV) and evaluated its efficacy in improved quantification and noise reduction. Relative to static PET/CT, the SUVmax increases for the EI, AVG, EE, and FCPM DDG PET/CT were 1.67±0.40, 1.50±0.28, 1.64±0.36, and 1.49±0.28, respectively. There were 10.8% and 9.1% average decreases in SUVmax from EI and EE to FCPM DDG PET/CT, respectively. EI, AVG, and EE DDG PET/CT all maintained increased image noise relative to static PET/CT. However, the noise levels of FCPM and static PET were statistically equivalent, suggesting the inclusion of all counts was able to decrease the image noise relative to EI and EE DDG PET/CT. A new FCPM DDG PET/CT has been developed to account for 100% of collected PET data in DDG PET applications. Image noise in FCPM is comparable to static PET, while small decreases in SUVmax were also observed in FCPM when compared to either EI or EE DDG PET/CT.

The Utility of [18]F-Fluorocholine Positron Emission Computed Tomography and [18]F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Evaluating Breast Cancer Phenotypes: A Pilot Study.

The utility of the [18]F fluorodeoxyglucose positron emission tomography-computed tomography ([18]F FDG PET-CT) marker for breast cancer is well established. Given its limitations in localizing FDG-negative malignant tumors, the expression of [18]F-fluorocholine ([18]-FCH) may potentially be helpful to improve the overall accuracy in evaluating breast cancer. This study determined the potential of [18]- FCH PET CT as a potential marker in assessing breast cancer phenotypes. We recruited consecutive patients with biopsy-proven breast carcinoma who underwent [18] F-FCH PET-CT following the [18]F-FDG PET-CT imaging. The subjects were dichotomized into human epidermal growth factor receptor 2 (HER2)-negative and HER2-positive genotypes. The maximum standardized uptake value (SUVmax; g/dL) was used to predict the two groups of variables. Global health status (GHS) score based on the EORTC quality of life questionnaire (QLQ) was used to evaluate the outcome of the cohort subjects at 6, 12, and 24 months. There were 21 females with a mean age of 54.48 ± 12.17 years. Eighteen patients had invasive ductal carcinoma (18/21;85.8%) on histology, with 11 (52.4%) were HER2-negative genotype. There was higher sensitivity and specificity of [18]-FCH-PET/CT in breast lesions at 40% and 68.8% compared to [18]FDGPET/CT with 33.3% and 66.7%, respectively. There were significant differences between [18]F-FCH SUVmax (g/dL) of the HER-negative as compared to the HER2- positive group (1.99 g/dL vs. 0.2 g/dL; P < .05). High SUVmax (g/dL) of [18]F-FCH had predicted the HER-negative genotype at the cutoff value of 0.75 (P < .05). High [18]F-FCH showed significantly poor scoring of GHS parameters compared to low FCH at 6 months (mean SUVmax 8.06 vs. 5.40 respectively; P < .05). [18]F-FCH PET-CT is a potential marker in localizing and predicting aggressive breast carcinoma phenotypes.

On variance estimation of the inverse probability-of-treatment weighting estimator: A tutorial for different types of propensity score weights.

Propensity score methods, such as inverse probability-of-treatment weighting (IPTW), have been increasingly used for covariate balancing in both observational studies and randomized trials, allowing the control of both systematic and chance imbalances. Approaches using IPTW are based on two steps: (i) estimation of the individual propensity scores (PS), and (ii) estimation of the treatment effect by applying PS weights. Thus, a variance estimator that accounts for both steps is crucial for correct inference. Using a variance estimator which ignores the first step leads to overestimated variance when the estimand is the average treatment effect (ATE), and to under or overestimated estimates when targeting the average treatment effect on the treated (ATT). In this article, we emphasize the importance of using an IPTW variance estimator that correctly considers the uncertainty in PS estimation. We present a comprehensive tutorial to obtain unbiased variance estimates, by proposing and applying a unifying formula for different types of PS weights (ATE, ATT, matching and overlap weights). This can be derived either via the linearization approach or M-estimation. Extensive R code is provided along with the corresponding large-sample theory. We perform simulation studies to illustrate the behavior of the estimators under different treatment and outcome prevalences and demonstrate appropriate behavior of the analytical variance estimator. We also use a reproducible analysis of observational lung cancer data as an illustrative example, estimating the effect of receiving a PET-CT scan on the receipt of surgery.

Splenic Embolism in Infective Endocarditis: A Systematic Review of the Literature with an Emphasis on Radiological and Histopathological Diagnoses.

Infective endocarditis (IE) is characterised by fever, heart murmurs, and emboli. Splenic emboli are frequent in left-sided IE. A systematic review of the literature published on splenic embolism (SE) between 2000 and 2023 was conducted. Search strategies in electronic databases identified 2751 studies published between 1 January 2000 and 4 October 2023, of which 29 were finally included. The results showed that the imaging tests predominantly used to detect embolisms were computed tomography (CT), magnetic resonance imaging, positron emission tomography (PET)/CT, single-photon emission computed tomography/CT, ultrasound, and contrast-enhanced ultrasound. More recent studies typically used 18F-FDG PET-CT. The proportion of SE ranged from 1.4% to 71.7%. Only seven studies performed systematic conventional CT screening for intra-abdominal emboli, and the weighted mean frequency of SE was 22% (range: 8-34.8%). 18F-FDG PET-CT was performed systematically in seven studies, and splenic uptake was found in a weighted mean of 4.5%. There was a lack of uniformity in the published literature regarding the frequency and management of splenic embolisation. CT scans were the most frequently used method, until recently, when 18F-FDG PET-CT scans began to predominate. More data are necessary regarding the frequency of SE, especially focusing on their impact on IE management and prognosis.

The application of different machine learning models based on PET/CT images and EGFR in predicting brain metastasis of adenocarcinoma of the lung

ObjectiveTo explore the value of six machine learning models based on PET/CT radiomics combined with EGFR in predicting brain metastases of lung adenocarcinoma.MethodsRetrospectively collected 204 patients with lung adenocarcinoma who underwent PET/CT examination and EGFR gene detection before treatment from Cancer Hospital Affiliated to Shandong First Medical University in 2020. Using univariate analysis and multivariate logistic regression analysis to find the independent risk factors for brain metastasis. Based on PET/CT imaging combined with EGFR and PET metabolic indexes, established six machine learning models to predict brain metastases of lung adenocarcinoma. Finally, using ten-fold cross-validation to evaluate the predictive effectiveness.ResultsIn univariate analysis, patients with N2-3, EGFR mutation-positive, LYM%≤20, and elevated tumor markers(P<0.05) were more likely to develop brain metastases. In multivariate Logistic regression analysis, PET metabolic indices revealed that SUVmax, SUVpeak, Volume, and TLG were risk factors for lung adenocarcinoma brain metastasis(P<0.05). The SVM model was the most efficient predictor of brain metastasis with an AUC of 0.82 (PET/CT group),0.70 (CT group),0.76 (PET group).ConclusionsRadiomics combined with EGFR machine learning model as a new method have higher accuracy than EGFR mutation alone. SVM model is the most effective method for predicting brain metastases of lung adenocarcinoma, and the prediction efficiency of PET/CT group is better than PET group and CT group.

The Role of PET-CT Scans in the Diagnosis and Outcome in Autoimmune Encephalitis (P5-14.014)

The Role of PET-CT Scans in the Diagnosis and Outcome in Autoimmune Encephalitis (P5-14.014)

Management of Abdominal Paraganglioma: A Single Center's Experience.

Background and Objectives: Paragangliomas (PGLs) are rare neuroendocrine extra-adrenal tumors that could be secreting mass. The symptoms are the typical triad of paroxysmal headache, hypertension and sweating, but could also be accompanied by symptoms involving multiple organs. Surgery is the gold standard treatment for both PGLs and pheochromocytomas (PHEOs). Material and Methods: We used a computerized endocrine surgery registry to record the demographic and clinical data of 153 patients who underwent surgery for PPGL between 2010 and 2023 at our hospital. Results: Thirteen patients (8.43%) with paragangliomas underwent surgery at our institute. Five patients presented symptomatic syndrome. Preoperative investigations included enhanced abdominal CT (nine patients) and enhanced MRI (seven patients). In cases of suspicious mass, we performed 131I-MIBG scans (two patients) or 68GA-DOTATOC PET-CT scans (11 patients). Laparoscopic approach was used in four cases (30.7%) and abdominal laparotomy in the other nine (69.3%). Biochemical tests were performed on all patients. Conclusions: In this retrospective study, we discuss the multidisciplinary management in our institute of this rare disease, from its challenging diagnosis to the surgical strategy for PGLs. Laparoscopic surgery is the gold standard, but a tailored approach should be adopted for each patient.

Abstract LB236: Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses

Abstract Background: The undeniable success of CD19 CAR-T cell therapy in managing relapsed or refractory (r/r) B-cell hematological malignancies, such as diffuse large B-cell lymphoma (DLBCL) and B-cell acute lymphoblastic leukemia (B-ALL), underscores its significance. Despite the favorable complete remission (CR) rates of around 50% for r/r DLBCL and up to 90% for r/r B-ALL, a notable challenge persists as more than half of patients experiencing CR after CD19 CAR-T cells treatment encounter relapse within a year, attributed to inadequate CAR-T persistence in both indications. Urgent attention is required to devise innovative strategies to overcome these challenges. Recently, we developed metabolically armed CD19 CAR-T cells expressing IL-10 can enhance OXPHOS metabolism, proliferation, and persistence of CAR-T cells in vivo. Significantly, these IL-10-expressing CAR-T cells trigger stem-like memory responses in various lymphoid organs, leading to robust tumor eradication and durable protection. Motivated by these promising findings, an open-label, single arm, investigator-initiated trial (IIT, ClinicalTrials.gov identifier: NCT05715606, NCT05747157) was conducted to assess the safety and efficacy of newly developed metabolically armed IL-10-expressing CD19 CAR-T (product name: Meta10-19 infusion) for treating patients with r/r DLBCL or r/r B-ALL. Method: From Feb 2023 to Dec 2023, this IIT clinical trial evaluated Meta10-19 infusion in adult patients with r/r DLBCL or r/r B-ALL. The patients were recruited and treated at the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China. Patients in 3 dose cohorts (2.0 × 104, 5.0 × 104, or 1.0 × 105 CAR-T cells/kg, corresponding to 1%, 2.5%, or 5% doses of commercialized CAR-T infusion) underwent lymphodepleting chemotherapy with cyclophosphamide and fludarabine before Meta10-19 infusion. The primary endpoint was the incidence of dose-limiting toxicities. The secondary endpoint was the response and survival. Results: The treatment with Meta10-19 infusion has successfully induced CR in all 12 cases of r/r DLBCL (n=6) or r/r B-ALL (n=6), as evaluated by PET-CT scan, NMR spectroscopy or minimal residual disease assessment of bone marrow. No server cytokine storm syndrome or neurotoxicity was observed. All treated patients achieved CR at 3 months post treatment, with the first patient maintaining continuous remission up to 9 months until now. Notably, these metabolically armed CD19 CAR-T cells demonstrated efficacy even for patients with bulky mass (≥7.5 cm) of DLBCL at extremely low infusion dose (1~5% doses of commercialized CAR-T). Conclusion: Preliminary findings suggest that Meta10-19 infusion exhibits promising breakthrough efficacy and safety profile, and active enrollment is ongoing to validate the initial results. Citation Format: Yugang Guo, Qianwen Xu, Lei Xue, Erling Chen, Chonglin Liu, Min Gao, Youjia Li, Jingjing Ren, Jinping Li, Li Tang, Xingbing Wang. Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB236.

Occult Breast Cancer Presenting as Sternum Pain.

Bone metastasis has been reported in up to 70% of patients with advanced breast cancer. A total of 55.76% of skeletal metastases in women were derived from breast cancer. However, patients with bone metastasis from an occult primary breast cancer are a rare subset of patients. Here, we present the case of a 38-year-old woman who had sternum pain for 4 months. A whole-body PET-CT scan revealed that the FDG uptake of both the sternum and internal mammary node was significantly increased. The final diagnosis of occult breast cancer was established by immunohistochemical (IHC) staining, which is of great significance for identifying the origin of a metastatic tumor despite no visualized lesions of mammary glands.

An Unusual Presentation of Squamous Cell Carcinoma in a Never Smoker: A Case Report

Lung Cancer is one of the most common types of cancer found among smokers. However, approximately 10% of lung cancer patients are non-smokers. Non-smokers are frequently seen developing Adenocarcinoma, a type of non-small cell carcinoma with a female predominance. The incidence of Squamous cell carcinoma among non-smokers is very low. Moreover, studies have shown that tetra site metastasis in the case of Squamous cell carcinoma of the lung is almost as rare as 0.6% [1]. The authors report here in this article a case report of a rare and aggressive presentation of Squamous cell carcinoma in a non-smoker. This is a case of a 50-year-old male patient who is a non-smoker, presented with complaints of exertional dyspnoea and cough with expectoration for 3 months which had aggravated since 15 days, associated with hoarseness of voice and diffuse headache since 15 days. There was a history of significant weight loss and loss of appetite for 3 months. CECT thorax revealed a heterogeneously enhancing mass lesion in the anterior segment of the left upper lobe encasing the left pulmonary artery with evidence of liver, adrenal and vertebral metastasis. During the hospital stay, the patient developed complete ptosis of the right eye. MRI brain was done which showed features suggestive of metastasis involving bilateral cerebral and cerebellar hemispheres. USG guided lung biopsy was done and was suggestive of moderately differentiated Squamous cell carcinoma. The patient was planned to be further worked up for IHC markers and PET CT scan to determine the further line of treatment however, unfortunately, the patient succumbed to the disease within 1 week of histopathological diagnosis.

Use of Multimodality Imaging in the Evaluation of Patients With Spondyloarthropathies and Sacroiliitis.

Spondyloarthropathy (SpA) is one of the most common causes of low back pain. It is caused by inflammatory arthritis in the spine, manifesting in various forms such as psoriatic arthritis (PsA), ankylosing spondylitis (AS), and sacroiliitis. A comprehensive systematic literature search was done to evaluate and compare MRI, CT, single-photon emission CT, PET, ultrasound (US) imaging, low-dose CT, and diffusion-weighted imaging (DWI) techniques in assessing SpAs. The search strategy was constructed by an analysis of key terms from relevant articles in MEDLINE ProQuest, Embase, and PubMed. The key terms used to search for these articles were "SpA," "sacroiliitis," "spondylitis," "psoriatic arthritis," "MRI," "CT scan," "x-ray," "magnetic resonance imaging," "computed tomography," "bone density," and "ultrasound." A total of 1,131 articles published in English between January 1, 2003, and October 15, 2023 were identified and screened for eligibility by members of the research team, which resulted in 69 total articles selected for the final review. US has played an important role in visualizing joint inflammation and enthesitis (inflammation of the enthesis), which are common features of PsA. Although MRI and CT are considered more reliable modalities for diagnosing active sacroiliitis, US imaging with Doppler flow can also be useful in conjunction with CT images to visualize abnormal blood flow in the sacroiliac joints, as well as other joints affected by inflammatory arthritis. MRI provides increased diagnostic confidence in the diagnosis of sacroiliitis in active AS patients when compared to CT. CT is more sensitive than plain radiographs. The PET activity score showed a good correlation in diagnosing inflammatory sacroiliitis but lacked in identifying structural lesions. CT has high diagnostic accuracy, but it exposes patients to a high radiation dose. MRI visualizes joint and tissue inflammation, bone, and bone marrow change and can identify peripheral inflammation in soft tissue and joints in patients diagnosed with PsA. MRI can also visualize bone marrow changes and subchondral edema, which can aid in the early diagnosis of ankylosing SpA and gauge disease severity. DWI and short-tau inversion recovery imaging are both MRI techniques used in detecting sacroiliitis. MRI and CT are shown to be reliable imaging modalities for the diagnosis of sacroiliitis; however, it was found that Doppler US played an accurate role in the diagnosis as well. MRI visualizes joints and tissue with the most precision, making it useful in evaluating patients with PsA, while PET CT is useful in the diagnosis of inflammatory sacroiliitis patients. There is limited literature available comparing the multiple modalities of imaging available for each SpA. The review's objective is to analyze imaging findings in patients diagnosed with sacroiliitis and SpAs. The findings in this literature review are valuable for properly assessing and diagnosing patients suffering from SpAs.

Role of F-18 FDG PET-CT in neuropsychiatric systemic lupus erythematosus

BackgroundNeuropsychiatric systemic lupus erythematosus (NPSLE) is a major contributor to morbidity and mortality in systemic lupus erythematosus (SLE) patients. To date no single clinical, laboratory or imaging test has proven accurate for NPSLE diagnosis which is a testament to the intricate and multifactorial pathophysiological mechanisms suspected to exist. Functional imaging with FDG PET-CT has shown promise in NPSLE diagnosis, detecting abnormalities prior to changes evident on anatomical imaging. Research indicates that NPSLE may be more aggressive in people of African descent with higher mortality rates, making rapid and correct diagnosis even more important in the African context. MethodsIn this narrative review, we provide a thorough appraisal of the current literature on the role of FDG PET-CT in NPSLE. Large, well-known databases were searched using appropriate search terms. Manual searches of references of retrieved literature were also included. FindingsA total of 73 article abstracts were assessed, yielding 26 papers that were directly relevant to the topic of FDG PET-CT in NPSLE. Results suggest that FDG PET-CT is a sensitive imaging test for NPSLE diagnosis and may play a role in assessing treatment response. It is complementary to routine anatomical imaging, particularly in diffuse manifestations of the disease. Newer quantitative analyses are commonly used for interpretation and can detect even subtle abnormalities, missed on visual inspection. Findings of group-wise analyses of FDG PET-CT scans in NPSLE patients are important in furthering our understanding of the complicated pathophysiological mechanisms involved. Limitations of FDG PET-CT include its lack of specificity, high cost and poor access. ConclusionFDG PET-CT is a sensitive test for NPSLE diagnosis but is hampered by lack of specificity. It is a valuable tool for clinicians managing SLE patients, particularly when anatomical imaging is negative. Its exact application will depend on the local context and clinical scenario.

Warthin's Tumour as a Parotid Gland Incidentaloma Identified by PET-CT Scan in a Large Series of Cases.

Occasionally in imaging scans there are findings unrelated to the pathology for which the scan was indicated, findings that are called incidentalomas. Warthin tumors have a high glucose avidity, being one of the common incidentalomas in PET-CT scans. The aim of the present study is to analyze the frequency of occurrence of Warthin's tumor as an incidental finding in a large series of patients undergoing 18F-FDG PET-CT. Retrospective analysis of 18F-FDG PET-CT scans performed in our center during the period 2010-2021. Parotid hypermetabolic lesions were identified, as well as their SUVmax, size, smoking habit, BMI (body mass index), and otorhinolaryngology follow-up. 31,423 PET-CT-18FDG studies corresponding to 12,806 patients were analyzed. The frequency of incidentalomas at the parotid level with a diagnosis compatible with Warthin's tumor was 0.87% (n = 111). Eighty percent of the patients with incidentalomas accordant to Warthin's tumor had a history of tobacco use. The highest percentage of incidentalomas compatible with a Warthin tumor was found in patients in whom the indication for PET-CT was the study of a lung carcinoma (1.44%). Only 37% of patients with a PET-CT lesion compatible with a Warthin's tumor were referred for evaluation by the Otorhinolaryngology service. The incidence of Warthin's tumor in 18-FDG PET-CT scans in our center was 0.87%.

Abstract 1305: Comparison of HPV-DNA testing to PET-CT imaging as prognostic test following definitive treatment for cervical cancer: A retrospective proof-of-concept study

Abstract Cervical cancer is a significant global health issue, with oncogenic HPV-High Risk (HPV) responsible for over 99% of cases. Despite the prevalence of HPV-related malignancies, current guidelines by the National Comprehensive Cancer Center (NCCN) do not recommend post-treatment HPV-DNA testing. Instead, PET-CT imaging is recommended as a prognostic test. This retrospective proof-of-concept study aims to evaluate current NCCN guidelines and examines whether post-treatment HPV-HR DNA testing is a cost-effective, reliable alternative to PET-CT imaging in cervical cancer prognosis. Methods: The study included female patients diagnosed with cervical or vaginal carcinomas (2011-2021), ensuring comprehensive records of both pre-treatment and post-treatment high-risk HPV (HPV-HR) testing, alongside PET-CT imaging results. Utilizing the FDA-approved HPV-HR DNA test, capable of detecting 14 oncogenic HPV strains, the study conducted rigorous statistical analyses via STATA software to determine significance of the study results. Results: Our analysis of 53 patients who met the inclusion criteria demonstrated that post-treatment assessments using both HPV status and PET-CT imaging exhibited high levels of sensitivity and specificity, as well as impressive negative and positive predictive values (NPV and PPV, respectively). There was a statistically significant correlation between the likelihood of cancer recurrence and the results obtained from HPV status and PET-CT imaging post-treatment (p-value &amp;lt; 0.001). A critical observation was the superior sensitivity and improved NPV of post-treatment HPV status compared to PET-CT scans. Specifically, the sensitivity for HPV status post-treatment was quantified at 92.31, surpassing the 76.92 sensitivity rating of PET-CT scans. Furthermore, the NPV for post-treatment HPV status was measured at 97.44, which is better than the 92.31 NPV for PET-CT scans. Notably, no patients with negative post-treatment HPV-HR tests had a recurrence. Discussion: The results of this study underscore the clinical significance of assessing HPV-HR DNA status post-treatment, particularly when HPV-HR DNA is negative. If future prospective studies confirm these findings, it may eliminate the need for post-treatment PET-CT scans, providing significant survivorship benefits for patients by reducing follow-up visits and eliminating unnecessary imaging. This would also result in substantial financial savings, estimated to be over $75,000,000 per year in the US alone, based on 2023 data. The limitations of the study include small sample size, single-institution data, and biases associated with retrospective studies. Future multi-institutional prospective studies are necessary to improve current guidelines further and validate the findings of this study. Citation Format: Cameron Huddleston, Aya Bou Fakhreddine, Stephanie Stroever, Robert Young, Naresh Sah, Komaraiah Palle, Mark Reedy. Comparison of HPV-DNA testing to PET-CT imaging as prognostic test following definitive treatment for cervical cancer: A retrospective proof-of-concept study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1305.

Abstract 2585: First in human study with a novel peptide binder to glypican-3, demonstrates high specificity as a PET imaging agent in patients with hepatocellular carcinoma

Abstract Introduction: Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. The American Association for the Study of Liver Disease recommends surveillance for high-risk individuals with abdominal ultrasound, triple phase contrast CT or MRI. However, these imaging techniques have limited sensitivity in classifying lesions smaller than 2 centimeters. The use of [18F]FDG Positron Emission Tomography (PET) is constrained due to insufficient uptake by HCC lesions over background liver uptake. Hence, there is an urgent need for more precise radiotracers for HCC. This study introduces the development of a novel radiotracer that binds to glypican-3 (GPC3), a cell membrane-anchored oncofetal protein overexpressed in HCC with minimal normal tissue expression. Methods: [68Ga]Ga-RYZ-GPC3 is composed of a small macrocyclic peptide binder with high affinity to GPC3 linked with a tetraxetan moiety capable of chelating a variety of radioisotopes including positron-emitting 68Ga and other radiometals. The unlabeled binder to GPC3 was synthesized by the sponsor and provided to three imaging centers in India as part of investigator-initiated trials reviewed and approved by each site’s institutional review board and ethics committee. Labeling with 68Ga and quality checks of the product was performed locally at each center. Patients with high clinical suspicion or with confirmed HCC who gave informed consent received injections of 1.5-5.5 mCi of [68Ga]Ga-RYZ-GPC3 and underwent PET-CT scanning at predetermined intervals. Some patients underwent companion [18F]FDG PET-CT scans in accordance with local guidelines. Results: A total of 64 patients underwent [68Ga]Ga-RYZ-GPC3 PET-CT scans. The median age within the cohort was 61 (41-83), 22% were female. Liver cirrhosis was present in 72% of patients, attributed to hepatitis B, hepatitis C or NASH in 17%, 13% and 20% of cases. Notably, 92% of patients exhibited at least one positive lesion on [68Ga]Ga-RYZ-GPC3 scans. The median SUVmax of GPC3-avid liver lesions was 15.5 (range 1.1 to 137.0) while the median liver SUVmean was 1.6 (0.3-7.9). Physiologic uptake was predominantly observed in the kidneys, the primary route of clearance, with a median SUVmean of 10.9 (2.2-20.7). Additionally, 20 patients underwent [18F]FDG PET-CT scan for comparison. The median SUVmax of lesions on 68Ga-RYZ-GPC3 vs [18F]FDG PET was 11.0 (1.1-137.0) vs 3.8 (1.2-12.2). Conclusion: Early human imaging results in patients with HCC indicate that [68Ga]Ga-RYZ-GPC3 has high tumor lesion specificity compared to normal liverand demonstrates the potential of [68Ga]Ga-RYZ-GPC3 to improve detection of HCC over conventional [18F]FDG PET-CT. In addition, the binder could be complexed with a therapeutic radioisotope as a novel targeted therapeutic option for HCC. Further investigation of this first-in-class binder to HCC is warranted. Citation Format: Chandresakhar Bal, Sanjana Ballal, Kumar Kallur, Anna Karmann, Ye Yuan, Jessica Rearden, Kathryn Shah, Charlotte Lorenz, Susan Moran, Ken Song, Ishita Sen. First in human study with a novel peptide binder to glypican-3, demonstrates high specificity as a PET imaging agent in patients with hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2585.

Checkpoint Inhibitors Prior to Autologous Stem Cell Transplantation for Relapsed/ Refractory Hodgkin Lymphoma

Aim: To present the evolution of our patients treated with checkpoint inhibitors before high-dose chemotherapy and autologous stem cell transplantation (ASCT) and to compare the results with data from the literature. Material and methods: We evaluate 3 patients with relapsed/refractory Hodgkin’s Lymphoma, who failed to achieve complete remission after 2 or more lines of salvage chemotherapy and were treated with anti PD1 inhibitors as a bridging therapy to autologous stem cell transplant. To evaluate the treatment response, we used PET CT scan before and 100 days after ASCT. Results: In our study, heavily pre-treated and chemo-refractory patients had increased response rates to conditioning chemotherapy followed by ASCT given after exposure to immune-checkpoint inhibitors. All 3 patients remain in complete response at 14 months, 20 months and respectively 32 months of follow-up. Conclusions: High-dose chemotherapy and ASCT can be curative for many patients with relapsed or refractory Hodgkin’s Lymphoma (HL), but the outcome depends on disease status at ASCT. Patients who have chemorefractory disease, particularly those who fail more than 2 lines of salvage therapy, are considered poor candidates for ASCT. Checkpoint inhibitors are routinely employed in relapsed/refractory classical Hodgkin lymphoma. The results from our center are similar with those from several studies which have suggested that treatment with anti PD1 can sensitize previously chemorefractory HL patients to subsequent high-dose therapy and ASCT.

Abstract 6294: Subclinical atherosclerosis in newly diagnosed colorectal cancer patients

Abstract Introduction: Recent advances in early detection and treatment have improved survival rates for patients with colorectal cancer (CRC), and emerging data suggests patients may be at elevated risk of cardiovascular disease (CVD). However, there are no standard recommendations for assessing CVD risk in patients with CRC. Coronary artery calcium (CAC) is a measure of the quantity of coronary artery calcification using noninvasive scanning and has been shown to be predictive of CVD risk. This prospective cohort study utilizes CAC to evaluate the occurrence of subclinical atherosclerosis at the time of CRC diagnosis and the risk of major adverse cardiovascular events (MACE). Methods: The ColoCare Study is a prospective cohort study across six U.S. and European sites. Data from one of the ColoCare consortium sites in Los Angeles, California was analyzed. Adults with newly diagnosed stage I- IV colorectal cancer and available non-contrast CT scans were included. Electronic medical records were reviewed for assessment of baseline cardiovascular risk factors and adverse events. Subclinical atherosclerosis was defined as the presence of CAC (CAC&amp;gt;0). CAC was manually measured from routine oncologic diagnostic CT and PET-CT scans at the time of cancer diagnosis using the Agatston method. MACE was defined as hospitalization due to heart failure, cardiomyopathy, ischemic heart disease, or ischemic stroke after the diagnosis of CRC cancer. Multivariable-adjusted Cox regression was used to evaluate the association between CAC at diagnosis and the risk of MACE. Results: Among 109 individuals with CAC measured at the time of CRC diagnosis, 41 (37.6%) had subclinical atherosclerosis (CAC=1-399 [n=29], CAC&amp;gt;400 [n=12]). Individuals with CAC&amp;gt;0 were older (67.0 vs. 51.9 years, p&amp;lt;0.01), more likely to be former or current smokers (48.0 vs. 29.0 years, p=0.04), and to have hypertension (61% vs. 23%, p&amp;lt;0.01) compared to those without CAC (CAC=0). Among individuals with CAC (n=41), 51.2% had scores &amp;gt;100, and 29.2% had scores &amp;gt;400, indicating moderate and severe atherosclerosis respectively. Among patients with moderate or greater CAC burden (&amp;gt;100; statin therapy indicated), 28.6% were not on statin therapy. CAC&amp;gt;0 was associated with an increased incidence of MACE (13% vs. 53%, p&amp;lt;0.01). Discussion: Subclinical atherosclerosis was observed in nearly 40% of patients with CRC at diagnosis and MACE occurred in 38.2% of patients. Most patients were under-optimized for CVD risk, with nearly 30% of statin-eligible patients with at least moderate CAC burden not prescribed statin therapy. These findings highlight an opportunity for improved CVD risk mitigation in patients with CRC, including guidelines-based CVD risk factor modification. Citation Format: Julia A. Levy, Maimoona Nadri, Elham Kazemian, Katelyn M. Atkins, Jordan O. Gasho, Katrina D. Silos, Cody Ramin, Andriana P. Nikolova, Erin M. Siegel, Biljana Gigic, Adetunji T. Toriola, Jennifer Ose, Christopher I. Li, David Shibata, Cornelia M. Ulrich, Jane C. Figueiredo. Subclinical atherosclerosis in newly diagnosed colorectal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6294.