Comparison of 11C-Methionine and 18F-FDG PET/CT for Staging and Follow-up of Pediatric Lymphoma

The Role of 11C-Methionine PET Imaging for the Evaluation of Lymphomas: A Systematic Review

Background: In the last years, different evidence has underlined a possible role for [11C]-methionine ([11C]MET) positron emission tomography (PET) imaging for the evaluation of lymphomas. The aim of this paper was, therefore, to review the available scientific literature focusing on this topic. Methods: A wide literature search of the PubMed/MEDLINE, Scopus and Cochrane Library databases was conducted in order to find relevant published articles investigating the role of [11C]MET in the assessment of lymphomas. Results: Eighteen studies were included in the systematic review and the main fields of application of this imaging modality were the evaluation of disease, therapy response assessment, prognostic evaluation and differential diagnosis with other pathological conditions. Conclusion: Even with heterogeneous evidence, a possible role for [11C]MET PET imaging in the assessment of lymphomas affecting both the whole body and the central nervous system was underlined. When compared to [18F]fluorodesoxyglucose ([18F]FDG) imaging, in general, similar results have been reported between the two modalities in these settings.

Intracranial residual lesions following early intensification in a patient with T-cell acute lymphoblastic leukemia: a case report

BACKGROUND

T-cell acute lymphoblastic leukemia (T-ALL) tends to involve central nervous system (CNS) infiltration at diagnosis. However, cases of residual CNS lesions detected at the end of induction and post early intensification have not been recorded in patients with T-ALL. Also, the ratio and prognosis of patients with residual intracranial lesions have not been defined.

CASE PRESENTATION

A 9-year-old boy with T-ALL had multiple intracranial tumors, which were still detected post early intensification. To investigate residual CNS lesions, we used 11C-methionine (MET)-positron emission tomography. Negative MET uptake in CNS lesions and excellent MRD status in bone marrow allowed continuing therapies without hematopoietic cell transplantation.

CONCLUSIONS

In cases with residual lesions on imaging studies, treatment strategies should be considered by the systemic response, direct assessment of spinal fluid, along with further development of noninvasive imaging methods in CNS. Further retrospective or prospective studies are required to determine the prognosis and frequency of cases with residual intracranial lesions after induction therapy.

FDG-PET/CT in Lymphoma: Where Do We Go Now?

18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) is an essential part of the management of patients with lymphoma at staging and response evaluation. Efforts to standardize PET acquisition and reporting, including the 5-point Deauville scale, have enabled PET to become a surrogate for treatment success or failure in common lymphoma subtypes. This review summarizes the key clinical-trial evidence that supports PET-directed personalized approaches in lymphoma but also points out the potential place of innovative PET/CT metrics or new radiopharmaceuticals in the future.

Enzyme-mediated depletion of serum l-Met abrogates prostate cancer growth via multiple mechanisms without evidence of systemic toxicity

Extensive studies in prostate cancer and other malignancies have revealed that l-methionine (l-Met) and its metabolites play a critical role in tumorigenesis. Preclinical and clinical studies have demonstrated that systemic restriction of serum l-Met, either via partial dietary restriction or with bacterial l-Met-degrading enzymes exerts potent antitumor effects. However, administration of bacterial l-Met-degrading enzymes has not proven practical for human therapy because of problems with immunogenicity. As the human genome does not encode l-Met-degrading enzymes, we engineered the human cystathionine-γ-lyase (hMGL-4.0) to catalyze the selective degradation of l-Met. At therapeutically relevant dosing, hMGL-4.0 reduces serum l-Met levels to >75% for >72 h and significantly inhibits the growth of multiple prostate cancer allografts/xenografts without weight loss or toxicity. We demonstrate that in vitro, hMGL-4.0 causes tumor cell death, associated with increased reactive oxygen species, S-adenosyl-methionine depletion, global hypomethylation, induction of autophagy, and robust poly(ADP-ribose) polymerase (PARP) cleavage indicative of DNA damage and apoptosis.

The Role of Positron Emission Tomography Imaging in Radiotherapy Target Delineation

Positron emission tomography (PET) is an advanced functional imaging modality in oncology care for the diagnosis, staging, prognostication, and surveillance of numerous malignancies. PET can also offer considerable advantages for target volume delineation as part of radiation treatment planning. In this review, data and clinical practice from 6 general oncology disease sites are assessed to descriptively evaluate the role of PET in target volume delineation. Also highlighted are several specific and practical utilities for PET imaging in radiation treatment planning. Publication of several ongoing prospective trials in the future may further expand the utility of PET for target delineation and patient care.

[Hybrid imaging in lymphoma]

Hybrid imaging using the tracer [18F]FDG (2‑deoxy-2-fluoro-D-glucose) is regarded as the backbone of the diagnostic workup of lymphomas. All international guidelines, and especially the Lugano and RECIL (Response Evaluation Criteria in Lymphoma) guidelines, currently recommend [18F]FDG-PET/CT (positron emission tomography/computed tomography) for staging and treatment response assessment. With the exception of pediatric lymphomas, neither PET/MRI (magnetic resonance imaging) nor whole-body MRI are currently endorsed by international guidelines, despite the fact that both techniques have clear advantages over [18F]FDG-PET/CT in the assessment of lymphomas with variable FDG avidity. Of the new, more specific PET tracers that are being evaluated for the use in lymphomas, the CXCR4 (CXC motif chemokine receptor 4) tracer [68Ga]Pentixafor is of particular interest, as initial studies have shown that it may be used to visualize frequently non-FDG-avid lymphomas such as small-cell lymphocytic lymphoma, mucosa-associated lymphoid tissue (MALT) lymphoma and lymphomplasmacytic lymphoma.

A metabolic profile of routine needle biopsies identified tumor type specific metabolic signatures for breast cancer stratification: a pilot study

INTRODUCTION

Metabolomics has recently emerged as a tool for understanding comprehensive tumor-associated metabolic dysregulation. However, only limited application of this technology has been introduced into the clinical setting of breast cancer.

OBJECTIVES

The aim of this study was to determine the feasibility of metabolome analysis using routine CNB/VAB samples from breast cancer patients and to elucidate metabolic signatures using metabolic profiling.

METHODS

After breast cancer screenings, 20 consecutive patients underwent CNB/VAB, and diagnosed with benign, DCIS and IDC by histology. Metabolome analysis was performed using CE-MS. Differential metabolites were then analyzed and evaluated with MetaboAnalyst 4.0.

RESULTS

We measured 116-targeted metabolites involved in energy metabolism. Principal component analysis and unsupervised hierarchical analysis revealed a distinct metabolic signature unique to namely "pure" IDC samples, whereas that of DCIS was similar to benign samples. Pathway analysis unveiled the most affected pathways of the "pure" IDC metabotype, including "pyrimidine," "alanine, aspartate, and glutamate" and "arginine and proline" pathways.

CONCLUSIONS

Our proof-of-concept study demonstrated that CE-MS-based CNB/VAB metabolome analysis is feasible for implementation in routine clinical settings. The most affected pathways in this study may contribute to improved breast cancer stratification and precision medicine.

MRI and PET/MRI in hematologic malignancies

The role of MRI differs considerably between the three main groups of hematological malignancies: lymphoma, leukemia, and myeloma. In myeloma, whole‐body MRI (WB‐MRI) is recognized as a highly sensitive test for the assessment of myeloma, and is also endorsed by clinical guidelines, especially for detection and staging. In lymphoma, WB‐MRI is presently not recommended, and merely serves as an alternative technique to the current standard imaging test, [¹⁸F]FDG‐PET/CT, especially in pediatric patients. Even for lymphomas with variable FDG avidity, such as extranodal mucosa‐associated lymphoid tissue lymphoma (MALT), contrast‐enhanced computed tomography (CT), but not WB‐MRI, is presently recommended, despite the high sensitivity of diffusion‐weighted MRI and its ability to capture treatment response that has been reported in the literature. In leukemia, neither MRI nor any other cross‐sectional imaging test (including positron emission tomography [PET]) is currently recommended outside of clinical trials. This review article discusses current clinical applications as well as the main research topics for MRI, as well as PET/MRI, in the field of hematological malignancies, with a focus on functional MRI techniques such as diffusion‐weighted imaging and dynamic contrast‐enhanced MRI, on the one hand, and novel, non‐FDG PET imaging probes such as the CXCR4 radiotracer [⁶⁸Ga]Ga‐Pentixafor and the amino acid radiotracer [¹¹C]methionine, on the other hand.

Level of Evidence: 5

Technical Efficacy Stage: 3

J. Magn. Reson. Imaging 2020;51:1325–1335.

11C-Methionine-Avid Plasmablastic Lymphoma

A 73-year-old woman had a diagnosis of a plasmablastic lymphoma by the excision of the right parotid gland. Two years after the diagnosis, the patient underwent a whole-body C-methionine PET/CT in order to evaluate the amino acid avidity of a scalp metastasis and for plasmablastic lymphoma restaging. C-methionine uptake was detected in the scalp, in several bone sites, and in the cricoid cartilage. Plasmablastic lymphoma is a subtype of B-cell lymphoma with an aggressive behavior and a poor prognosis. C-methionine appears to be a promising tracer for paraprotein-producing neoplasms.

Clinical Applications of Small-molecule PET Radiotracers: Current Progress and Future Outlook

Radiotracers, or radiopharmaceuticals, are bioactive molecules tagged with a radionuclide used for diagnostic imaging or radiotherapy and, when a positron-emitting radionuclide is chosen, the radiotracers are used for PET imaging. The development of novel PET radiotracers in many ways parallels the development of new pharmaceuticals, and small molecules dominate research and development pipelines in both disciplines. The 4 decades since the introduction of [¹⁸F]FDG have seen the development of many small molecule PET radiotracers. Ten have been approved by the US Food and Drug Administration as of 2016, whereas hundreds more are being evaluated clinically. These radiotracers are being used in personalized medicine and to support drug discovery programs where they are greatly improving our understanding of and ability to treat diseases across many areas of medicine including neuroscience, cardiovascular medicine, and oncology.