What’s New in Nuclear Medicine – July 2021

2 months ago
Association of COVID-19 mRNA Vaccine with Ipsilateral Axillary Lymph Node Reactivity on Imaging

Mehmet Emin Adin, Edvin Isufi, Michal Kulon, and Darko Pucar.

JAMA Oncology. Published online June 10, 2021. doi:10.1001/jamaoncol.2021.1794

Background: There are multiple reports of COVID-19 vaccines resulting in ipsilateral axillary lymph node uptake on PET/CT imaging, which has led to unnecessary biopsies and diagnostic challenges.

Purpose: To investigate the association between COVID-19 vaccination with Moderna and Pzifer-BioNTech vaccines and 18-fluorodeoxyglucose (FDG) activity on PET/CT.

Methods: Of all patients who underwent FDG-PET/CT between December 2020 and March 2021, the authors identified that 68 had received at least one dose of a COVID-19 vaccine. Their demographics, indications for imaging, and degree of lymph node activity as measured by the Deauville score were collected.

Results: Of the 68 patients, 41 patients had received one vaccine dose and 27 had received two doses; 51 patients had received the Pzifer vaccine while 17 had received the Moderna version. 9 patients (13%) were found to have ipsilateral axillary adenopathy, 2 of whom had received one dose and 7 of whom had received two doses. FDG uptake at the injection site was identified in 8 patients up to 32 days after injection.

Conclusions: The authors propose that given the chance of lymphadenopathy following COVID-19 vaccine, patients with malignancies which may spread to the ipsilateral axillary lymph nodes should have the vaccine injected on the contralateral site. Details about the patient’s vaccination status, including the site of injection, should be noted when presenting for nuclear medicine imaging.

 

Real-World Data Analysis of Efficacy and Survival after Lutetium-177 Labelled PSMA Ligand Therapy in Metastatic Castration-Resistant Prostate Cancer

Danielle Meyrick, Marat Gallyamov, Shanthi Sabarimurugan, Nadia Falzone, and Nat Lenzo.

Targeted Oncology. 2021; 16: 369-80. DOI: 10.1007/s11523-021-00801-w

Background: As many prostate cancers overexpress prostate-specific membrane antigen (PSMA), radioligand therapy with 177Lu targeted at the PSMA ligand is being investigated as a treatment option that is more specific to the prostate cancer cells and therefore potentially less toxic than current chemotherapies used to treat metastatic castration-resistant prostate cancer (mCRPC).

Purpose: To examine the efficacy and toxicity of 177Lu-PSMA radioligand therapy in mCRPC.

Methods: This is a retrospective cohort study of 191 otherwise healthy patients with mCRPC known to be PSMA overexpressing who underwent 177Lu-PSMA radioligand therapy for progressive disease. All patients underwent initial 68Ga-PSMA to identify that they had PSMA overexpressing disease, and contrast-enhanced CT at clinically indicated points during their care to assess response/progression. Toxicity was assessed two weeks before and four weeks after each treatment. Follow-up times varied based on when the patient underwent therapy and the study cut-off date.

Results: Patients underwent between one and five cycles of 177Lu-PSMA therapy, most having undergone two cycles (46% of patients). Almost all (89.5%) had undergone systemic therapy prior to this. Following their 177Lu-PSMA cycle(s), 56% of patients had a biochemical response of greater than 50% reduction in PSA, while 49.6% had a radiographic response. Overall survival rate was 12 months, biochemical progression-free survival was 4 months, and radiographic progression-free survival was 6 months. 52% had no progression at 6 months and 35% had no progression at 12 months. In subgroup analysis, those who had a response had statistically significant increased overall and progression-free survival compared to those who did not respond.

The most common treatment-related adverse events were hematologic (anemia, thrombocytopenia, and neutropenia), occurring in 12%. Renal disease was also noted (1.7% developed AKI, 2.9% developed CKD). Two patients (1.1%) experienced adverse events leading to treatment cessation, including severe bone pain and anemia.

Conclusions: 177Lu-PSMA therapy was shown to have a low toxicity profile and to be effective in provoking a response in 56% of patients with improved overall survival and progression-free survival rates in these patients.

 

18F-FDG PET is Superior to WHO Grading as a Prognostic Tool in Neuroendocrine Neoplasms and Useful in Guiding PRRT: A Prospective 10-Year Follow-up Study.

Tina Binderup, Ulrich Knigge, Camilla Bardram Johnbeck, Annika Loft, Anne Kiil Berthelsen, Peter Oturai, Jann Mortensen, Birgitte Federspiel, Seppo W. Langer, and Andreas Kjaer.

Journal of Nuclear Medicine. 2021; 62(6): 808-15. DOI: https://doi.org/10.2967/jnumed.120.244798

Background: The WHO classification for neuroendocrine tumors (NETs) assigns a tumor grade based on the degree of tumor proliferation by immunohistochemical assay. This grade (G1-3) is then used for treatment decisions and prognostication. Assigning a grade in this way is subjected to heterogeneity in an individual tumor and could reflect a non-representative subsection of the tumor. This has been shown to be an issue especially for low-grade NETs, which, despite being classified as G1 or G2, can turn out to be rapidly progressive or very stable. 18F-FDG PET is widely used for staging other cancers and has been recently shown to be useful in assessing NETs and their metastases.

Purpose: To evaluate the prognostic value of risk stratifying neuroendocrine tumors with 18F-FDG PET, and to compare this utility with that of current WHO neuroendocrine tumor grading.

Methods: This prospective cohort study followed 166 patients with gastroenteropancreatic (GEP) NETs to determine overall survival (OS) and progression-free survival (PFS) as markers for prognostic value. Histopathology was obtained and the WHO classification determined for all tumors. All patients underwent 18F-FDG PET/CT which were interpreted by a nuclear medicine specialist and a radiologist. Retrospectively, the authors assessed the outcomes of peptide receptor radionuclide therapy (PRRT) with respect to the 18F-FDG PET tumor grading.

Results: Of the 166 patients included, 87% had already undergone treatment and 92% had metastatic disease. Average time from diagnosis to the 18F-FDG PET/CT for this study was 39 months. Median follow-up time was 9.8 years.

Both OS and PFS were greater for those cases which were 18F-FDG PET negative than positive: five-year OS and PFS for 18F-FDG PET negative tumors were 79% and 49%, respectively; five-year OS and PFS for 18F-FDG PET positive tumors were 35% and 18%, respectively. By WHO classification, OS and PFS were longer for G1 than G3 and for G2 than G3 tumors, but there was no statistical difference in OS or PFS comparing G1 and G2 tumors. Multivariate analysis revealed that positive-vs-negative 18F-FDG PET was an independent prognostic factor for survival (both OS and PFS), but that status as G1 or G2 was not. While outcomes were better for 18F-FDG PET negative tumors than 18F-FDG PET, there was no significant impact of PRRT on outcomes for these tumors. For those with 18F-FDG PET positive tumors, survival was longer if they did receive PRRT than if they did not.

Conclusions: The authors found that 18F-FDG PET provides a more useful risk stratification of GEP-NETs than the WHO classification, especially for WHO G1 and G2 tumors. Previous smaller studies have found similar results. The nature of the tumor as 18F-FDG PET positive or negative may also help guide the decision to treat with PRRT, in that while 18F-FDG PET negative tumors have better outcomes overall, PRRT does provide survival benefits for those with 18F-FDG PET positive tumors to a greater degree than for those with 18F-FDG PET negative tumors.

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