The skeleton is one of the most common sites for metastatic disease, particularly from breast and prostate cancer. Bone metastases are associated with considerable morbidity, and accurate imaging of the skeleton is important in determining the appropriate therapeutic plan. Sodium fluoride labeled with fluorine 18 (sodium fluoride F 18 [(18)F-NaF]) is a positron-emitting radiopharmaceutical first introduced several decades ago for skeletal imaging. (18)F-NaF was approved for clinical use as a positron emission tomographic (PET) agent by the U.S. Food and Drug Administration in 1972. The early use of this agent was limited, given the difficulties of imaging its high-energy photons on the available gamma cameras. For skeletal imaging, it was eventually replaced by technetium 99m ((99m)Tc)-labeled agents because of the technical limitations of (18)F-NaF. During the past several years, the widespread availability and implementation of hybrid PET and computed tomographic (CT) dual-modality systems (PET/CT) have encouraged a renewed interest in (18)F-NaF PET/CT for routine clinical use in bone imaging. Because current PET/CT systems offer high sensitivity and spatial resolution, the use of (18)F-NaF has been reevaluated for the detection of malignant and nonmalignant osseous disease. Growing evidence suggests that (18)F-NaF PET/CT provides increased sensitivity and specificity in the detection of bone metastases. Furthermore, the favorable pharmacokinetics of (18)F-NaF, combined with the superior imaging characteristics of PET/CT, supports the routine clinical use of (18)F-NaF PET/CT for oncologic imaging for skeletal metastases. In this article, a review of the indications, imaging appearances, and utility of (18)F-NaF PET/CT in the evaluation of skeletal disease is provided, with an emphasis on oncologic imaging.

Sarcoidosis is a multisystem disease characterized by the formation of noncaseating granulomas. Lung and intrathoracic lymph nodes are classic sites of involvement; however, sarcoidosis can affect any site in the body. The clinical course is extremely variable, and the imaging features are diverse and dependent on the affected site, degree of inflammation, and treatment the patient receives. Atypical manifestations and imaging findings can make diagnosis and/or management challenging. In addition, assessment of treatment response can be difficult in the setting of chronic disease. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT is sensitive for assessment of the inflammatory activity of sarcoidosis in any organ. Although FDG PET/CT is not included in the standard workup for sarcoidosis, there has been growing evidence that supports the value of this examination in guiding diagnosis and management. FDG PET/CT may be especially useful for assessing reversible granuloma, treatment response, disease extent, occult disease, and cardiac or osseous sarcoidosis, and determining the most suitable biopsy site. Capability to image the entire body during a single examination is advantageous in cases of systemic disease such as sarcoidosis. The authors review the use of FDG PET/CT, providing up-to-date evidence and describing various cases of sarcoidosis in which FDG PET/CT has an important role in diagnosis and/or management. They also discuss the usefulness of FDG PET/CT in cases of selective manifestations of sarcoidosis. RSNA, 2018.

Background: When initial therapy for cHL fails, the standard approach is multiagent salvage chemotherapy followed by autologous stem cell transplant (ASCT). The success of ASCT can be predicted by achievement of complete remission (CR) by fluorodeoxyglucose positron emission tomography (PET) following salvage chemotherapy (Moskowitz, et al. Blood 2012;119:1665-70). Unfortunately, about half of patients (pts) are unable to achieve CR with first salvage. The anti-CD30 antibody-drug conjugate BV is effective as a single agent in rel/ref cHL (Younes, et al. JCO 2012;30:2183-9). Pre-ASCT salvage chemotherapy combinations with BV have been explored (LaCasce, et al. ASH 2015, #293; Garcia-Sanz, et al. ASH 2015, #582), as has a PET-adapted sequential approach with BV then ICE (Moskowitz, et al. Lancet Oncol 2015;16:284-92). We hypothesized that concurrent therapy with BV and ICE would be safe and produce high CR rates. We also sought to explore inflammatory microenvironment prognostic factors. (ClinicalTrials.gov #NCT02227199) Methods: Pts ≥ 18 years old with first relapse or primary refractory CD30+ cHL were eligible. Key inclusion criteria were ≥ 1 FDG-avid site of disease ≥ 1 cm; adequate marrow, hepatic, and renal function; and HIV-. Key exclusions were any prior BV; chemotherapy ≤ 3 weeks of enrollment; and pre-existing neuropathy > NCI-CTCAE Grade 1. All pts signed IRB-approved informed consent forms. Treatment included BV on Days 1 and 8, ifosfamide and mesna 5 g/m2 each on Day 2, carboplatin AUC 5 (capped at 800 mg) on Day 2, and etoposide 100 mg/m2daily on Days 1-3. A 3+3 dose-escalation schema for BV was used to determine the maximum tolerated dose (MTD) with ICE: starting dose was 1.2 mg/kg on Days 1 and 8, escalated to 1.5 mg/kg on Days 1 and 8 or de-escalated to 1.2 mg/kg on Day 1 only, based on rate of dose-limiting toxicity (DLT). Once MTD of BV was established, subsequent pts received this dose. 2 21-day cycles were given with G-CSF support. PET was performed after Cycle 2, with response assigned per Cheson 2007. Stem cells were collected after Cycle 2 at discretion of treating investigator. Peripheral blood (PB) pre- and post-treatment, stem cell (PBSC) product, and (when available) archived formalin-fixed paraffin-embedded tissue from presentation and relapse were collected for correlative studies. Pre-treatment PB PD-L1 levels were measured by ELISA. Results: To date, 16 pts have enrolled and completed study treatment. Median age was 32 (range, 23-60). All received ABVD-based initial chemotherapy, and 5 (31%) received radiation. 11 (69%) did not obtain CR with initial therapy. Grade 3-4 neutropenia, lymphopenia, and anemia was seen in 2 (12%) pts each; thrombocytopenia in 4 (25%) pts. 6 (38%) pts experienced Grade 3-4 non-heme toxicity, but no single toxicity occurred in > 1 pt. Neuropathy was seen in 5 (31%) pts: 4 Grade 1, and 1 Grade 3. 1 DLT (sepsis) was observed in the 9 pts treated in the dose-escalation phase, defining 1.5 mg/kg on Days 1 and 8 as the MTD of BV with ICE. Overall response rate for all enrolled patients was 94% (n=14), with 88% (n=14) and 69% (n=11) achieving CR by investigator and central independent radiographic review, respectively. 15 (94%) pts underwent PBSC collection, all of which were successful. 12 (75%) pts proceeded to ASCT immediately following this treatment. With a median follow-up of 6.5 (range, 2-20) months, there have been 3 (19%) relapses (2 were in CR after BV-ICE) and no deaths. Counts of CD68+ macrophages (15%, 14%), granzyme+ cytotoxic cells (6.2%, 8.7%), and CD20+ B cells (24%, 14%) by immunohistochemistry were not significantly different between presentation and relapse (respectively). Levels of PD-L1 were below the limit of detection (500 pg/mL) in all pts. Conclusions: Pts with rel/ref cHL can safely receive BV up to 1.5mg/kg on Days 1 and 8 per cycle of ICE. Apart from generally-mild neuropathy, adding BV does not appreciably change the toxicity profile of ICE. Observed response rates by PET are very encouraging. Inflammatory cell composition appears similar at presentation and relapse. Without more sensitive testing, circulating levels of PD-L1 are unlikely to be of use in this setting. Enrollment is ongoing, and updated clinical and correlative data, including the use of next-generation sequencing-based detection of lymphoma-specific DNA sequence as a novel method of response assessment, will be presented at the meeting. Disclosures Gopal: Seattle Genetics: Research Funding.

Summary Background Merkel cell carcinoma (MCC) is an aggressive, high‐grade, cutaneous neuroendocrine tumour (NET). Agents blocking programmed death 1/programmed death ligand 1 have efficacy in metastatic MCC (mMCC), but half of patients do not derive durable benefit. Somatostatin analogues (SSAs) are commonly used to treat low‐ and moderate‐grade NETs that express somatostatin receptors (SSTRs). Objectives To assess SSTR expression and the efficacy of SSAs in mMCC, a high‐grade NET. Methods In this retrospective study of 40 patients with mMCC, SSTR expression was assessed radiologically by somatostatin receptor scintigraphy (SRS; n = 39) and/or immunohistochemically when feasible (n = 9). Nineteen patients (18 had SRS uptake in MCC tumours) were treated with SSA. Disease control was defined as progression‐free survival (PFS) of ≥ 120 days after initiation of SSA. Results Thirty‐three of 39 patients (85%) had some degree (low 52%, moderate 23%, high 10%) of SRS uptake. Of 19 patients treated with SSA, seven had a response‐evaluable target lesion; three of these seven patients (43%) experienced disease control, with a median PFS of 237 days (range 152–358). Twelve of 19 patients did not have a response‐evaluable lesion due to antecedent radiation; five of these 12 (42%) experienced disease control (median PFS of 429 days, range 143–1757). The degree of SSTR expression (determined by SRS and/or immunohistochemistry) did not correlate significantly with the efficacy endpoints. Conclusions In contrast to other high‐grade NETs, mMCC tumours appear frequently to express SSTRs. SSAs can lead to clinically meaningful disease control with minimal side‐effects. Targeting of SSTRs using SSA or other novel approaches should be explored further for mMCC.

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