A tale of 3 tracers : contrasting uptake patterns of 18F-fluciclovine, 68Ga-PSMA, and 18F-FDG in the uterus and adnexa

A 41-year-old woman with newly diagnosed invasive lobular carcinoma of the breast underwent sequential 68Ga-PSMA-11 PET/CT and 18F-fluciclovine PET/CT as part of an ongoing clinical trial (NCT04750473). 68Ga-PSMA PET/CT showed increased radiotracer uptake in the uterine endometrium and left adnexa. 18F-fluciclovine PET/CT showed increased radiotracer uptake in an enlarged uterus in a known uterine leiomyoma. A clinical 18F-FDG PET/CT demonstrated radiotracer uptake in the endometrium and a circumferential area of uptake in the left adnexa, a pattern more similar to the 68Ga-PSMA uptake pattern. This case highlights the discordance in the uptake pattern of two radiotracers in different benign gynecological conditions. While these tracers are approved for prostate cancer imaging, they are increasingly being used in other malignancies.http://journals.lww.com/nuclearmed/pages/default.aspxhj2023Nuclear Medicin

Minimal residual disease in Myeloma: Application for clinical care and new drug registration

The development of novel agents has transformed the treatment paradigm for multiple myeloma, with minimal residual disease (MRD) negativity now achievable across the entire disease spectrum. Bone marrow–based technologies to assess MRD, including approaches using next-generation flow and next-generation sequencing, have provided real-time clinical tools for the sensitive detection and monitoring of MRD in patients with multiple myeloma. Complementary liquid biopsy–based assays are now quickly progressing with some, such as mass spectrometry methods, being very close to clinical use, while others utilizing nucleic acid–based technologies are still developing and will prove important to further our understanding of the biology of MRD. On the regulatory front, multiple retrospective individual patient and clinical trial level meta-analyses have already shown and will continue to assess the potential of MRD as a surrogate for patient outcome. Given all this progress, it is not surprising that a number of clinicians are now considering using MRD to inform real-world clinical care of patients across the spectrum from smoldering myeloma to relapsed refractory multiple myeloma, with each disease setting presenting key challenges and questions that will need to be addressed through clinical trials. The pace of advances in targeted and immune therapies in multiple myeloma is unprecedented, and novel MRD-driven biomarker strategies are essential to accelerate innovative clinical trials leading to regulatory approval of novel treatments and continued improvement in patient outcomes

False-positive FDG PET/CT due to liver parenchymal injury caused by a surgical retractor.

A 70-year-old man underwent partial gastrectomy with pathology demonstrating gastric follicular lymphoma. After surgery, a staging FDG PET/CT study demonstrated an FDG-avid low-attenuation band in the liver. Corresponding MRI demonstrated a high T2 signal abnormality. This was believed to represent liver parenchymal injury due to liver retraction during surgery. The patient was managed conservatively. MRI at 1 month of follow-up demonstrated resolution of the T2 signal abnormality. FDG PET/CT at 6 months of follow-up demonstrated resolution of FDG uptake. Tissue injury from surgical retraction can produce FDG-avid lesions that need to be distinguished from malignancy on PET/CT

Identifying and distinguishing treatment effects and complications from malignancy at FDG PET/CT.

Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is increasingly used in the initial staging, evaluation of treatment response, and surveillance of many malignancies. Uptake of FDG is substantially increased in most malignancies, compared with its uptake in normal tissues, and the finding of FDG avidity often leads to cancer detection earlier than abnormalities can be seen at anatomic imaging. However, FDG is not a cancer-specific agent, and FDG avidity can be seen in many benign processes. It can be particularly challenging to discriminate malignancy from benign FDG-avid changes caused by surgery and procedures, radiation therapy, and chemotherapy. FDG-avid abnormalities caused by surgery and procedures include inflammation at sites of incision or dissection, inflammation from vascular compromise or surgical retraction, surgical transposition of structures with physiologic FDG avidity (such as ovaries or testes), and pleurodesis inflammation. Radiation therapy may induce FDG-avid pneumonitis, esophagitis, or hepatitis, as well as osteoradionecrosis or fractures. FDG-avid chemotherapy complications include pneumonitis, osteonecrosis, enterocolitis, and pancreatitis. Use of granulocyte colony stimulating factor for treatment of bone marrow suppression after chemotherapy induces temporary increases of FDG avidity in the bone marrow and spleen. Familiarity with common and unusual iatrogenic causes of FDG avidity that can confound interpretation of FDG PET/CT results will improve the accuracy of distinguishing treatment effects and complications from residual or recurrent malignancy at FDG PET/CT examinations

Current and potential applications of positron emission tomography for multiple myeloma and plasma cell disorders

Fluorine-18 (18F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) allows evaluation of elevated glucose metabolism in malignancies. There has been increasing interest in FDG PET/CT for plasma cell disorders since the International Myeloma Working Group outlined multiple applications of this imaging modality, including distinguishing smoldering myeloma from active multiple myeloma, confirmation of solitary plasmacytoma, and multiple indications in patients with known multiple myeloma, including determining extent of initial disease, monitoring therapy response, and detection of residual disease following therapy. The field of molecular imaging is now shifting focus from evaluation of metabolism to targeted evaluation of specific tumor markers. Targeted PET imaging targeted of CXCR4 and CD38 has advanced into translational clinical trials, bringing us closer to powerful imaging options for myeloma. In this review we discuss the current applications of FDG PET/CT in plasma cell disorders, as well as advances in targeted PET imaging

Improved image reconstruction of

Purpose: The aim of this study was to evaluate the use of a Bayesian penalized likelihood reconstruction algorithm (Q.Clear) for 89Zr-immunoPET image reconstruction and its potential to improve image quality and reduce the administered activity of 89Zr-immunoPET tracers. Methods: Eight 89Zr-immunoPET whole-body PET/CT scans from three 89Zr-immunoPET clinical trials were selected for analysis. On average, patients were imaged 6.3 days (range 5.0-8.0 days) after administration of 69 MBq (range 65-76 MBq) of [89Zr]Zr-DFO-daratumumab, [89Zr]Zr-DFO-pertuzumab, or [89Zr]Zr-DFO-trastuzumab. List-mode PET data was retrospectively reconstructed using Q.Clear with incremental β-values from 150 to 7200, as well as standard ordered-subset expectation maximization (OSEM) reconstruction (2-iterations, 16-subsets, a 6.4-mm Gaussian transaxial filter, heavy z-axis filtering and all manufacturers\u27 corrections active). Reduced activities were simulated by discarding 50% and 75% of original counts in each list mode stream. All reconstructed PET images were scored for image quality and lesion detectability using a 5-point scale. SUVmax for normal liver and sites of disease and liver signal-to-noise ratio were measured. Results: Q.Clear reconstructions with β = 3600 provided the highest scores for image quality. Images reconstructed with β-values of 3600 or 5200 using only 50% or 25% of the original counts provided comparable or better image quality scores than standard OSEM reconstruction images using 100% of counts. Conclusion: The Bayesian penalized likelihood reconstruction algorithm Q.Clear improved the quality of 89Zr-immunoPET images. This could be used in future studies to improve image quality and/or decrease the administered activity of 89Zr-immunoPET tracers. Keywords: 89Zr-immunoPET; BSREM; OSEM; Q.Clear; Reconstruction algorithms