Chronic hand and wrist pain is a common presenting complaint. The intricate anatomy results in a variety of pain generators—multiple bones, articular cartilage, intrinsic ligaments, triangular fibrocartilage complex, joint capsules and synovium, tendons and tendon sheaths, muscles, and nerves—in a compact space. The need for imaging and the choice of the appropriate imaging modality are best determined by the patient’s presentation, physical examination, and the clinician’s working differential diagnosis. Radiography is usually appropriate as the initial imaging study in the evaluation of chronic hand or wrist pain.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

BACKGROUND:For patients with liver-confined metastatic colorectal cancer (mCRC), local therapy of isolated metastases has been associated with long-term progression-free and overall survival (OS). However, for patients with more advanced mCRC, including those with extrahepatic disease, the efficacy of local therapy is less clear although increasingly being used in clinical practice. Prospective studies to clarify the role of metastatic-directed therapies in patients with mCRC are needed.METHODS:The Evaluating Radiation, Ablation, and Surgery (ERASur) A022101/NRG-GI009 trial is a randomized, National Cancer Institute-sponsored phase III study evaluating if the addition of metastatic-directed therapy to standard of care systemic therapy improves OS in patients with newly diagnosed limited mCRC. Eligible patients require a pathologic diagnosis of CRC, have BRAF wild-type and microsatellite stable disease, and have 4 or fewer sites of metastatic disease identified on baseline imaging. Liver-only metastatic disease is not permitted. All metastatic lesions must be amenable to total ablative therapy (TAT), which includes surgical resection, microwave ablation, and/or stereotactic ablative body radiotherapy (SABR) with SABR required for at least one lesion. Patients without overt disease progression after 16-26 weeks of first-line systemic therapy will be randomized 1:1 to continuation of systemic therapy with or without TAT. The trial activated through the Cancer Trials Support Unit on January 10, 2023. The primary endpoint is OS. Secondary endpoints include event-free survival, adverse events profile, and time to local recurrence with exploratory biomarker analyses. This study requires a total of 346 evaluable patients to provide 80% power with a one-sided alpha of 0.05 to detect an improvement in OS from a median of 26 months in the control arm to 37 months in the experimental arm with a hazard ratio of 0.7. The trial uses a group sequential design with two interim analyses for futility.DISCUSSION:The ERASur trial employs a pragmatic interventional design to test the efficacy and safety of adding multimodality TAT to standard of care systemic therapy in patients with limited mCRC.TRIAL REGISTRATION:ClinicalTrials.gov: NCT05673148, registered December 21, 2022.

Department of Radiology, San Francisco VA Medical Center, San Francisco, California; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California; Ahmanson Translational Theranostics Division, Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, California; Molecular Imaging and Therapy Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, Weill Medical College of Cornell University, New York, New York; Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa; Department of Imaging, Dana-Farber Cancer Institute, Department of Radiology, Brigham and Women’s Hospital, Boston, Massachusetts; Department of Diagnostic Radiology, Oregon Health & Science University, Portland, Oregon; Wright Center of Innovation and Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio; Department of Nuclear Medicine, University of Duisburg-Essen and German Cancer Consortium (DKTK)-University Hospital Essen, Essen, Germany; Department of Nuclear Medicine, La Timone University Hospital, CERIMED, Aix-Marseille University, Marseille, France; and Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Department of Biomedical Sciences, Rigshospitalet and University of Copenhagen, Copenhagen, Denmark

As the immuno-oncology field continues the rapid growth witnessed over the past decade, optimising patient outcomes requires an evolution in the current response-assessment guidelines for phase 2 and 3 immunotherapy clinical trials and clinical care. Additionally, investigational tools-including image analysis of standard-of-care scans (such as CT, magnetic resonance, and PET) with analytics, such as radiomics, functional magnetic resonance agents, and novel molecular-imaging PET agents-offer promising advancements for assessment of immunotherapy. To document current challenges and opportunities and identify next steps in immunotherapy diagnostic imaging, the National Cancer Institute Clinical Imaging Steering Committee convened a meeting with diverse representation among imaging experts and oncologists to generate a comprehensive review of the state of the field.

TPS3629 Background: For patients with oligometastatic colorectal cancer (CRC), aggressive local therapy of isolated metastases, particularly in the liver, has been associated with long-term progression-free survival and overall survival (OS) primarily based on retrospective evidence. However, in patients with limited metastatic CRC that is deemed inoperable or those with additional disease outside of the liver or lungs, the role of local ablative therapies, including microwave ablation (MWA) and stereotactic body radiation therapy (SBRT), to render patients disease free is less clear. Further, despite the long history of treating oligometastatic CRC with local therapy, which is provider biased and not evidence based, questions remain regarding the benefit of extending the paradigm of metastatic directed therapy to patients with more extensive disease. This trial seeks to use a pragmatic multimodality approach that mirrors the current clinical dilemma. This study is designed to evaluate the safety and efficacy of adding total ablative therapy (TAT) of all sites of disease to standard of care systemic treatment in those with limited metastatic CRC. Methods: A022101 is a National Clinical Trials Network randomized phase III study planned to enroll 364 patients with newly diagnosed metastatic CRC (BRAF wild-type, microsatellite stable) with ≤4 sites of metastatic disease on baseline imaging. Liver-only metastatic disease is not permitted, and lesions must be amenable to any combination of surgical resection, MWA, and/or SBRT with SBRT required for at least one lesion. Patients receive first-line systemic therapy for 4-6 months and are then randomized 1:1, stratified by number of metastatic organ sites (1-2 vs. 3-4), timing of metastatic disease diagnosis (de novo vs. secondary), and presence of metastatic disease outside the liver and lungs in at least one site. Patients in Arm 1 will receive TAT which consists of treatment of all metastatic sites with SBRT ± MWA ± surgical resection followed by standard of care systemic therapy. Patients in Arm 2 will continue with standard of care systemic therapy alone. The primary endpoint is OS. Secondary endpoints include event-free survival, treatment-related toxicities, and local recurrence with exploratory biomarker analyses. The study needs 346 evaluable patients combined in the 2 arms to demonstrate an improvement in OS with a hazard ratio of 0.7 to provide 80% power with a one-sided alpha of 5%. The trial utilizes a group sequential design with two interim analyses (25% and 50% of events) for futility. The trial activated in January 2023 and recruitment is ongoing. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org. U10CA180820 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG); Clinicaltrials.gov identifier: NCT05673148 Clinical trial information: NCT05673148 .

e16573 Background: Identifying osseous lesions and quantifying their response to therapy is challenging. 18 F-fluorodeoxyglucose (FDG) and 18 F-sodium Fluoride (NaF) PET/CT are both functional imaging modalities with increased sensitivity and specificity for detecting osseous lesions. This study analyzed the association of baseline FDG PET/CT and NaF PET/CT semi-quantitative parameters of bone lesions with or without additional visceral metastasis with survival for patients (pts) with non-prostate mGU malignancies treated on a phase I study with Cabozantinib (Cabo), Nivolumab (Nivo) +/- Ipilimumab (Ipi). Methods: Patients underwent sequential FDG PET/CT and NaF PET/CT scans at baseline. Semi-quantitative imaging parameters were measured including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for FDG and fluoride uptake tumor volume (FTV) and total lesion fluoride uptake (TLF) for NaF. Total bone lesion number was captured for all scans. Bone lesion CT characteristics were grouped into 4 categories (0 = normal, 1 = osteolytic, 2 = osteoblastic and 3 = mixed). Semi-quantitative parameters were divided to create two equally sized groups (low vs high) and the association of imaging parameters and survival was determined with Kaplan-Meier curves. Results: We analyzed 40 pts with non-prostate mGU cancers and osseous metastases with or without additional visceral metastasis. Thirty-four (85%) were males; median age was 56 (range 23-81); Histologically, 19 (48%) had urothelial carcinoma, 8 renal carcinoma, 5 testicular, 2 penile cancer, 2 renal medullary, 2 urachal/adenocarcinoma, 1 mucinous and 1 bladder clear cell. Eighteen pts had mixed bone lesion CT characteristic, 8 osteolytic, 4 osteoblastic and 10 normal. A total of 111 osseous lesions were detected on FDG PET/CT while 251 lesions were detected on NaF PET/CT. FDG PET/CT low vs high SUVmax and low vs high TLG were associated with improved OS [25 months(mo) (95% CI: 14.0 – not estimable) vs 8.8 mo (2.9-25.4), p = 0.034], and [25.4mo (17.0 – not estimable) vs 8.8 mo (2.9 -24.9), p = 0.018], respectively. There was no difference in OS for pts with bone only disease compared to pts with bone and visceral disease [21mo (8.4-37.2 vs 14 mo (3.2-25.4), p = 0.12] though there was a difference in PFS [13.4mo (4.8-18.3) vs 4.5 mo (1.7-5.8), p = 0.044]. There were no NaF PET/CT semi-quantitative parameters that were associated with survival outcomes, and CT characterization of osseous lesions was also not found to be associated with survival outcomes. Conclusions: FDG PET/CT semi-quantitative parameters showed potential prognostic capabilities in pts with non-prostate mGU malignancies with bone +/- visceral metastases treated on a phase I study with CaboNivo +/- Ipi. Additional parameters and histologic subsets will be presented.

Abdominopelvic hernias are common clinical entities composed of a wide variety of congenital, traumatic, and iatrogenic etiologies. Any weakness in the body wall may result in hernia of cavity contents with concomitant risks of morbidity and mortality. Presentations may be specific, palpable body wall mass/bulge, or vague, nonspecific pain through bowel obstruction. This document focuses on initial imaging of the adult population with signs of symptoms prompting suspicion of abdominopelvic hernia. Imaging of the abdomen and pelvis to evaluate defects is essential for prompt diagnosis and treatment. Often CT and ultrasound are the first-line modalities to quickly evaluate the abdomen and pelvis, providing for accurate diagnoses and management of patients. MRI protocols may be useful as first-line imaging studies, especially in patients with orthopedic instrumentation. Although often performed, abdominal radiographs and fluorographic procedures may provide indirect evidence of hernias but are usually not indicated for initial diagnosis of hernia. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

The aim of the study was to assess the quality and reproducibility of reducing the injected [ 18 F] sodium fluoride ([ 18 F]NaF) dose while maintaining diagnostic imaging quality in bone imaging in a preclinical skeletal model using digital photon counting PET (dPET) detector technology. Beagles ( n = 9) were administered three different [ 18 F]NaF doses: 111 MBq ( n = 5), 20 MBq ( n = 5), and 1.9 MBq ( n = 9). Imaging started ≃45 min post-injection for ≃30 min total acquisition time. Images were reconstructed using Time-of-Flight, ultra-high definition (voxel size of 1 × 1 × 1 mm 3 ), with 3 iterations and 3 subsets. Point spread function was modeled and Gaussian filtering was applied. Skeleton qualitative and quantitative molecular image assessment was performed. The overall diagnostic quality of all images scored excellent (61%) and acceptable (39%) by all the reviewers. [ 18 F]NaF SUV mean showed no statistically significant differences among the three doses in any of the region of interest assessed. This study demonstrated that a 60-fold [ 18 F]NaF dose reduction was not significantly different from the highest dose, and it had not significant effect on overall image quality and quantitative accuracy. In the future, ultra-low dose [ 18 F]NaF dPET/CT imaging may significantly decrease PET radiation exposure to preclinical subjects and personnel.

Procedure Appropriateness Category Relative Radiation Level US abdomen Usually Appropriate O CT abdomen and pelvis with IV contrast Usually Appropriate ☢☢☢ CT abdomen and pelvis without IV contrast Usually Appropriate ☢☢☢ MRI abdomen without and with IV contrast May Be Appropriate O MRI abdomen without IV contrast May Be Appropriate O US pelvis Usually Not Appropriate O Radiography abdomen and pelvis (KUB) Usually Not Appropriate ☢☢ Fluoroscopy upper GI series Usually Not Appropriate ☢☢☢ Fluoroscopy upper GI series with small bowel follow-through Usually Not Appropriate ☢☢☢ MRI pelvis without and with IV contrast Usually Not Appropriate O MRI pelvis without IV contrast Usually Not Appropriate O CT abdomen and pelvis without and with IV contrast Usually Not Appropriate ☢☢☢☢

Ectopic parathyroid glands are not rare. They are usually located between the mandible and mediastinum, and usually localized with standard imaging modalities (99mTc-sestamibi subtraction scintigraphy and 4D-CT). We report the case of a 67-year-old woman with severe hypercalcemia due to symptomatic primary hyperparathyroidism whose preoperative 99mTc-sestamibi and 4D-CT scans were non-localizing. During 4-gland exploration, one hypercellular parathyroid was excised, two normocellular parathyroids were biopsied, and bilateral low internal jugular vein sampling showed similar parathyroid hormone (PTH) levels. Despite treatment with zolendronic acid and cinacalcet, symptomatic PHPT persisted. A99mTc-sestamibi study using a modified anterior and posterior whole-body scintigraphy protocol with SPECT/CT revealed mild focal uptake in the right para-tracheal area, correlating with a mass on SPECT/CT. Sestamibi uptake was visually more conspicuous on posterior projection whole-body image. Thoracoscopic resection of this mass revealed a parathyroid gland (2.6 × 1.5 × 0.7 cm) composed almost entirely of chief cells. The lack of identifiable oxyphil content could explain the lack of or limited radiotracer uptake. The modified protocol differed from standard parathyroid imaging in the timing of radiotracer administration, timing of image capture, and types of images obtained could account for the eventual visualization of the ectopic tissue, and may be considered in challenging cases of suspected ectopic parathyroid gland.

TPS7593 Background: While PTCL is treated for curative intent, 5-year (yr) overall survival (OS) remains 20-25% with CHOP based therapy. For pts <60 yrs old, the addition of etoposide to CHOP has been associated with improved outcomes. Brentuximab vedotin in combination with chemotherapy demonstrated an OS benefit in PTCL with CD30 >10% by immunohistochemistry, and most significantly improved outcomes in anaplastic large cell lymphoma. This served as proof of principle that biomarker driven therapy can lead to improved outcomes in this rare disease (Horwitz et al Lancet 2019). Duvelisib is a gamma delta PI3 kinase inhibitor with a 50% overall response rate in PTCL and a trend toward a higher response rate in PTCL with a T-follicular helper (TFH) phenotype (Brammer et al. Blood 2021). Azacitidine is a hypomethylating agent that has shown a 75% overall response rate (ORR) in PTCL with TFH phenotype. CC-486, oral azacitidine, has been safely combined with CHOP and showed a 75% ORR with a higher ORR in PTCL with TFH phenotype (Ruan et al. Blood 2021). Methods: A051902 is a 3 arm randomized phase II US intergroup study in previously untreated PTCL with CD30 expression <10% comparing standard chemotherapy (CHOP or CHOEP) to CHOP/CHOEP with duvelisib 25mg PO BID or CHOP/CHOEP with azacitidine 300mg PO. Pts will be stratified by age (>60, ≤60) and TFH phenotype. Pts over age 60 will receive CHOP and those ≤60 will receive CHOEP. Prior to the randomized study, there is a safety lead-in study for the first 12 pts combining duvelisib 15mg BID with CHOP/CHOEP. The primary endpoint of the phase II study is complete remission (CR) rate by the Lugano 2014 criteria. The phase II study is powered for a 25% improvement in CR rate (45% vs 70%) in an experimental arm compared to CHOP/CHOEP with a 90% power and type I error rate of 10%. The phase II will enroll 159 pts (53 per arm). Key eligibility: 1. untreated PTCL (nodal T-cell lymphoma with TFH phenotype, follicular T-cell lymphoma, PTCL-NOS, angioimmunoblastic T-cell lymphoma, enteropathy associated T-cell lymphoma, monomorphic epitheliotropic intestinal T-cell lymphoma) with CD30 expression <10%, 2. Stage I-IV, PS 0-2. Pts with transformed mycosis fungoides or anaplastic large cell lymphoma are excluded. Standard CHOP and CHOEP are administered every 21 days with growth factor support. Azacitadine 300mg will be taken on days -6 to -1 prior to cycle 1 and then on days 8 to 21 for cycles 1-5. Duvelisib 25mg BID will be taken continuously. Correlative studies include evaluation of TFH phenotype (by immunohistochemistry, gene expression profiling and DNA sequencing) and cell free DNA evaluation to predict outcomes as well as patient reported outcomes. The study was activated 7/30/2021 and the safety lead-in portion is currently enrolling. Support: U10CA180821, U10CA180882. Clinical trial information: NCT04803201.

452 Background: This study determined the association of functional imaging parameters obtained on FDG PET/CT and NaF PET/CT with OS for pts with mGU malignancies treated on a phase I study with CaboNivo +/- Ipi. Methods: Pts on this phase I study underwent sequential (1-hour apart) FDG PET/CT and NaF PET/CT imaging at baseline and at first-restaging (8 weeks follow up). Scan semi-quantitative parameters measures included: maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for FDG and MTV for NaF. Total lesion number was captured for all scans. The association of imaging parameters and survival was determined with Kaplan-Meier curves. Baseline values and percent change values were calculated. Results: 81 pts were included in the analysis. 67 (83%) were males; Median age was 63 (range 25-86); Histologically, 30 pts had urothelial carcinoma, 15 clear cell renal cell carcinoma, 9 germ cell tumors, 8 urachal/adenocarcinoma, 8 prostate cancer, 3 penile cancer, 3 squamous cell carcinoma, 3 renal medullary carcinoma, and 2 small cell (1 bladder, 1 prostate). All 81 had a baseline FDG PET scan, 78 pts received baseline NaF PET scans; 66 received both FDG PET and NaF PET baseline and follow up scans. 957 total lesions were detected on FDG PET across all histologies, 87 liver (9%), 252 lung (26%), 152 bone (16%), 411 lymph node (43%), and 55 other visceral metastases (6%). 414 total lesions were detected on NaF imaging. Low vs high baseline FDG MTV (31 vs 11 months, p = 0.0002), TLG (30 vs 11 months, p = 0.0004), Lesion number (49 vs 15 months, p = 0.0005), and SUVmax (25 vs 12 months, p = 0.025), FDG lesion number decrease or no change vs increase (24 vs 12 months, p = 0.0068), and low vs high baseline NaF MTV (26 vs 16 months, p = 0.007), and lesion number (26 vs 16 months, p = 0.007) showed the strongest associations with OS. A multivariable Cox analysis demonstrated that baseline FDG MTV (HR = 2.87, 95% CI 1.62-5.08, p = 0.0003) and FDG lesion number percent change (HR = 2.71, 95% CI 1.40-5.24, p = 0.0031) were jointly associated with OS. Conclusions: Baseline functional imaging parameters and percent change seen on follow imaging with FDG PET and NaF PET are prognostic in mGU pts treated with CaboNivo +/- ipi. Additional parameters and histologic subsets will be presented.

Palpable scrotal abnormalities are caused by a variety of disorders, ranging from indolent benign conditions to aggressive tumors, and infectious and vascular processes. In these patients the diagnostic workup typically begins with a complete clinical, history, and physical examinations, including analysis of risk factors. If imaging is required, ultrasound examination is the diagnostic modality of choice. In few select patients with very large scrotal masses, MRI may be appropriate. However, the use of gadolinium-based contrast should be evaluated critically depending on specific patient factors. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Abstract Background 18 F‐Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) positive (PET+) cytologically indeterminate thyroid nodules (ITNs) have variable cancer risk in the literature. The benign call rate (BCR) of Afirma Gene Classifier (Gene Expression Classifier, GEC, or Genome Sequence Classifier, GSC) in (PET +) ITNs is unknown. Methods This is a retrospective study at our institution of all patients with (PET+) ITNs (Bethesda III/IV) from 1 January 2010 to 21 May 2019 who underwent Afirma testing and/or surgery or repeat FNA with benign cytology. Results Forty‐five (PET+) ITNs were identified: 31 Afirma‐tested (GEC = 20, GSC = 11) and 14 either underwent surgery (n = 13) or repeat FNA (Benign cytology) (n = 1) without Afirma. The prevalence of cancer and noninvasive follicular thyroid neoplasm with papillary‐like nuclear features (NIFTP) including only resected nodules and ITN with repeat benign FNA (n = 33) was 36.4% (12/33). Excluding all Afirma “suspicious” non‐resected ITNs and assuming all Afirma “benign” ITNs were truly benign, that prevalence was 28.6% (12/42). The BCR with GSC was 64% compared to 25% with GEC (p = 0.056). Combining GSC/GEC‐tested ITNs, the BCR was higher in ITNs demonstrating low/very low‐risk sonographic pattern by the American Thyroid Association (ATA) classification and ITNs scoring <4 by the American College of Radiology Thyroid Imaging, Reporting and Data System (ACR‐TI‐RADS) than ITNs with higher sonographic pattern/score (p = 0.025). Conclusions The prevalence of cancer/NIFTP in (PET+) ITNs was 28.6–36.4% depending on the method of calculation. The BCR of Afirma GSC was 64%. Combining Afirma GEC/GSC‐tested ITNs, BCR was higher in ITNs with a lower risk sonographic pattern.

1693 Objectives: Sodium fluoride-18 (Na18F) PET/CT is used clinically for routine oncologic and non-oncologic bone imaging evaluation in order to detect, assess and characterize osteoblastic lesions. In those patients with symptomatic osseous lesions, new approaches are needed to substantially reduce whole-body Na18F PET image acquisition times (usually 60-120 s/bed). The recent introduction of next-generation PET/CT systems equipped with digital photon counting PET (dPET) detector technology enables faster PET image acquisition as well as PET imaging at lower administered radiotracer doses. The objective is assess the clinical potential of a 10x faster Na18F dPET imaging approach for whole-body assessment and characterization of malignant and non-malignant osteoblastic lesion and compare to standard PET image acquisition times. Methods: In this intra-individual comparison trial, investigational whole-body Na18F dPET/CT imaging (Vereos, Philips Healthcare) was performed in 50 oncologic patients using a target Na18F dose of 185 MBq. At 80 min post injection, whole-body dPET acquisition was performed using a substantially faster 9 s/bed (1/10 of the standard PET acquisition time) followed by a standard 90 s/bed acquisition at ~85 min post injection. Standard definition dPET image data sets (voxel volume = 4x4x4 mm3) were reconstructed using Time-of-Flight for each acquisition and then evaluated by matched pair comparison for overall image quality, background quality and lesion detectability by a blinded reader panel using an Intellispace Portal workstation. Results: All 100 data sets were rated as evaluable for qualitative assessment of 18F biodistribution and osteoblastic lesions. When compared to standard 90 s/bed acquisitions, the faster 9 s/bed dPET acquisitions demonstrated visually comparable 18F-avidity in both normal bone and osteoblastic lesions. A total of 213 discrete Na18F-avid foci were detected on the 9 s/bed and 90 s/bed acquisitions with no discordant osteoblastic lesions identified. A total of 47 foci were characterized as malignant and the remaining 166 as non-malignant. All 50 patients demonstrated non-malignant foci with the majority reflecting degenerative change but only 17 patients demonstrated malignant lesions. Quantitatively, there was no significant difference in SUVmax values for all 213 lesions on the 9 s/bed (20 ± 15) and 90 s/bed (23 ± 16) acquisitions regardless of lesion type. For 9 s/bed acquisitions, there was no difference in SUVmax between non-malignant (20 ± 13) and malignant (20 ± 20) lesions, and likewise for 90 s/bed acquisitions, there was no difference between non-malignant (23 ± 14) and malignant (24 ± 24) lesions [ANOVA, p>0.19]. There was excellent linear correlation (R2 = 0.97) between the SUVmax values for all 213 NaF-avid foci between the 9 and 90 s/bed acquisitions. Conclusions: Ultra-fast digital PET/CT imaging with a 9 s/bed acquisition using 185 MBq of Na18F is clinically feasible for the whole-body assessment of malignant and non-malignant lesions as well as qualitatively and quantitatively comparable to more traditional PET acquisition times (e.g., 90 sec/bed). Research Support: Ohio Third Frontier (TECH 09-028, TECH 10-012, TECH 13-060).

Epigastric pain can have multiple etiologies including myocardial infarction, pancreatitis, acute aortic syndromes, gastroesophageal reflux disease, esophagitis, peptic ulcer disease, gastritis, duodenal ulcer disease, gastric cancer, and hiatal hernia. This document focuses on the scenarios in which epigastric pain is accompanied by symptoms such as heartburn, regurgitation, dysphagia, nausea, vomiting, and hematemesis, which raise suspicion for gastroesophageal reflux disease, esophagitis, peptic ulcer disease, gastritis, duodenal ulcer disease, gastric cancer, or hiatal hernia. Although endoscopy may be the test of choice for diagnosing these entities, patients may present with nonspecific or overlapping symptoms, necessitating the use of imaging prior to or instead of endoscopy. The utility of fluoroscopic imaging, CT, MRI, and FDG-PET for these indications are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

1373 Objectives: To assess the utility of dynamic perfusion PET imaging for the evaluation of esophageal tumors over the course of radiation therapy. Methods: Eleven patients with esophageal tumors were imaged over one bed position at the site of the primary tumor for 15 minutes immediately following injection of 5 mCi 18F-FDG. Imaging was performed on a digital photon counting system (Philips Vereos). Patients spent the remaining uptake period in the injection suite followed by whole body imaging at 75 minutes post-injection as standard imaging. Listmode data from the dynamic acquisition were reconstructed with 1 minute per frame. Regions of interest were placed over the primary tumor, aorta, and a portion of healthy liver. Imaging was performed prior to radiation therapy, at a 3 month interim timepoint, and post-therapy, about 6 months after baseline imaging. Results: Excellent image quality and quantifiably robust data were produced for all acquisitions. Physiologic motion could readily be corrected for, however very little motion was observed on the 1 minute per frame dynamic images. Differences in perfusion and dynamic uptake patterns in the individual tumors were identifiable. In general patients who eventually responded well to treatment showed greater initial perfusion rates over the 15 minute dynamic acquisition than did those who did not respond well to treatment. Patients with Grade 1 and 2 (well and moderately differentiated) tumors had greater decreases in the initial dynamic uptake between baseline and interim imaging than those who had Grade 3 (poorly differentiated) tumors, who showed little change in the uptake curves between baseline and interim imaging. Correlation with pathology results and clinical outcomes is ongoing. Conclusions: We have demonstrated that dynamic perfusion FDG PET/CT of esophageal tumors is robustly achievable. Quantification of tumor features is achievable, changes in perfusion and uptake characteristic over the course of therapy are readily quantifiable. This PET-based methodology can be applied to assess changes in rates of tumor perfusion and radiotracer uptake over the course of therapy, adding additional insight beyond delayed, static measures of SUV. Research Support: ODSA TECH 13-060 (IPP), R01 CA-195513, RSNA Research Seed Grant - Utilization of Dynamic Digital PET for Prediction of Histopathologic Response Following Neoadjuvant Chemoradiation for Esophageal Cancer