Usefulness of [11C] Methionine PET in the Differentiation of Tumefactive Multiple Sclerosis from High Grade Astrocytoma

Value of 11C-Methionine PET Imaging in High-Grade Gliomas: A Narrative Review

11C-Methionine (MET) is a widely utilized amino acid tracer in positron emission tomography (PET) imaging of primary brain tumors. 11C-MET PET offers valuable insights for tumor classification, facilitates treatment planning, and aids in monitoring therapeutic response. Its tracer properties allow better delineation of the active tumor volume, even in regions that show no contrast enhancement on conventional magnetic resonance imaging (MRI). This review focuses on the role of MET-PET in brain glioma imaging. The introduction provides a brief clinical overview of the problems of high-grade and recurrent gliomas. It discusses glioma management, radiotherapy planning, and the difficulties of imaging after chemoradiotherapy (pseudoprogression or radionecrosis). The mechanism of MET-PET is described. Additionally, the review encompasses the application of MET-PET in the context of primary gliomas, addressing its diagnostic precision, utility in tumor classification, prognostic value, and role in guiding biopsy procedures and radiotherapy planning.

Tumefactive demyelinating lesions: A literature review of recent findings

Tumefactive demyelinating lesion is a variant of multiple sclerosis that is a diagnostic challenge. Tumefactive demyelinating lesion requires extensive work-up as its clinical and radiological features are often indistinguishable from other central nervous system lesions, such as tumors. Diagnosis is further complicated by the increasing recognition that tumefactive demyelinating lesions can occur alongside, evolve into, or develop from numerous conditions other than multiple sclerosis, pointing to a possible overlapping etiology. We review herein relevant studies from 2017 onwards to provide a current view on the pathogenesis, clinical and imaging findings, novel diagnostic techniques for differential diagnoses, and management of tumefactive demyelinating lesions.

Methionine-PET to differentiate between brain lesions appearing similar on conventional CT/MRI scans

BACKGROUND AND PURPOSE

11 C-Methionine (MET)-PET is a useful tool in neuro-oncology. This study aimed to examine whether a combination of diagnostic variables associated with MET uptake could help distinguish between brain lesions that are often difficult to discriminate in conventional CT and MRI.

METHODS

MET-PET was assessed in 129 patients with glioblastoma multiforme, primary central nervous lymphoma, metastatic brain tumor, tumefactive multiple sclerosis, or radiation necrosis. The accuracy of the differential diagnosis was analyzed using five diagnostic characteristics in combination: higher maximum standardized uptake value (SUV) of MET in the lesion/the mean normal cortical SUV of MET ratio, overextension beyond gadolinium, peripheral pattern indicating abundant MET accumulation in the peripheral region, central pattern denoting abundant MET accumulation in the central region, and dynamic-up suggesting increased MET accumulation during dynamic study. The analysis was conducted on sets of two of the five brain lesions.

RESULTS

Significant differences in the five diagnostic traits were observed among the five brain lesions, and differential diagnosis could be achieved by combining these diagnostic features. The area under the curve between each set of two of the five brain lesions using MET-PET features ranged from .85 to 1.0.

CONCLUSIONS

According to the findings, combining the five diagnostic criteria could help with the differential diagnosis of the five brain lesions. MET-PET is an auxiliary diagnostic technique that could help in distinguishing these five brain lesions.

18F-Fluorodeoxy Glucose and 11C-Methionine Accumulation in Demyelinating Lesions

Background Few studies have evaluated the accumulation of 18F-fluorodeoxyglucose (FDG), 11C-methionine (MET), and other positron emission tomography (PET) tracers in patients with demyelinating disease.

Purpose This study aimed to investigate the accumulation of FDG-PET/computed tomography (CT) and MET-PET/CT in demyelinating lesions.

Material and Methods A retrospective search of the patient database in our hospital identified five patients with demyelinating disease in whom PET studies performed in the past 10 years revealed accumulation of FDG or MET. The clinical diagnoses were multiple sclerosis (n=1), myelitis (n=1), limbic encephalitis (n=1), chronic inflammatory demyelinating polyneuropathy (CIDP; n=1), and acute demyelinating encephalomyelitis (ADEM; n=1). Two patients received FDG-PET/CT alone and three patients received both FDG-PET/CT and MET-PET/CT on the same day. Images were visually and conjointly reviewed by two radiologists. In semiquantitative evaluation, the maximum standardized uptake value (SUVmax) of the lesion was measured. The lesion-to-normal brain uptake ratio (L/N ratio) was calculated.

Results FDG and/or MET accumulated to a part of the lesions seen on MRI. SUVmax on FDG-PET/CT ranged from 3.8 to 10.3, and L/N ratio on MET-PET/CT ranged from 16.6 to 2.4.

Conclusion It has been established that neoplastic and demyelinating lesions can be differentiated on the basis of FDG or MET uptake. However, as accumulation of FDG and MET can also occur in demyelinating lesions; knowledge of this possibility is of clinical importance.

Correlation of Intraoperative 5-ALA-Induced Fluorescence Intensity and Preoperative 11C-Methionine PET Uptake in Glioma Surgery

Simple Summary

In malignant brain tumor surgery, precise identification of the tumor is essential. 5-Aminolevulinic acid (5-ALA) labels tumor cells with red fluorescence to facilitate tumor resection. On the other hand, the nuclear medicine imaging technique, positron emission tomography with ¹¹C-methionine (MET-PET), can delineate tumors precisely but is not widely available. This study aimed to determine the correlation between intraoperative 5-ALA-induced fluorescence and preoperative MET-PET signals of gliomas. We quantitatively measured the fluorescence intensity from tumor samples and calculated the MET-PET uptake by the tumor. Our study showed that strong tumor fluorescence correlated with high MET-PET uptake and cellular proliferation. Our findings might be valuable to rapidly provide information on tumor biology at the time of surgery in circumstances where MET-PET is inaccessible.

Abstract

Background: 5-Aminolevulinic acid (5-ALA) is widely employed to assist fluorescence-guided surgery for malignant brain tumors. Positron emission tomography with ¹¹C-methionine (MET-PET) represents the activity of brain tumors with precise boundaries but is not readily available. We hypothesized that quantitative 5-ALA-induced fluorescence intensity might correlate with MET-PET uptake in gliomas. Methods: Adult patients with supratentorial astrocytic gliomas who underwent preoperative MET-PET and surgical tumor resection using 5-ALA were enrolled in this prospective study. The regional tumor uptake of MET-PET was expressed as the ratio of standardized uptake volume max to that of the normal contralateral frontal lobe. A spectrometric fluorescence detection system measured tumor specimens’ ex vivo fluorescence intensity at 635 nm. Ki-67 index and IDH mutation status were assessed by histopathological analysis. Use of an antiepileptic drug (AED) and contrast enhancement pattern on MRI were also investigated. Results: Thirty-two patients, mostly with Glioblastoma IDH wild type (46.9%) and anaplastic astrocytoma IDH mutant (21.9%), were analyzed. When the fluorescence intensity was ranked into four groups, the strongest fluorescence group exhibited the highest mean MET-PET uptake and Ki-67 index values. When rearranged into fluorescence Visible or Non-visible groups, the Visible group had significantly higher MET-PET uptake and Ki-67 index compared to the Non-visible group. Contrast enhancement on MRI and IDH wild type tumors were more frequent among the Visible group. AED use did not correlate with 5-ALA-induced fluorescence intensity. Conclusions: In astrocytic glioma surgery, visible 5-ALA-induced fluorescence correlated with high MET-PET uptake, along with a high Ki-67 index.

Cognitive Dysfunction after Heart Disease: A Manifestation of the Heart-Brain Axis

The functions of the brain and heart, which are the two main supporting organs of human life, are closely linked. Numerous studies have expounded the mechanisms of the brain-heart axis and its related clinical applications. However, the effect of heart disease on brain function, defined as the heart-brain axis, is less studied even though cognitive dysfunction after heart disease is one of its most frequently reported manifestations. Hypoperfusion caused by heart failure appears to be an important risk factor for cognitive decline. Blood perfusion, the immune response, and oxidative stress are the possible main mechanisms of cognitive dysfunction, indicating that the blood-brain barrier, glial cells, and amyloid-β may play active roles in these mechanisms. Clinicians should pay more attention to the cognitive function of patients with heart disease, especially those with heart failure. In addition, further research elucidating the associated mechanisms would help discover new therapeutic targets to intervene in the process of cognitive dysfunction after heart disease. This review discusses cognitive dysfunction in relation to heart disease and its potential mechanisms.

Tumefactive demyelination: updated perspectives on diagnosis and management

INTRODUCTION

Tumefactive demyelination (TD) can be a challenging scenario for clinicians due to difficulties distinguishing it from other conditions, such as neoplasm or infection; or with managing the consequences of acute lesions, and then deciding upon the most appropriate longer term treatment strategy.

AREAS COVERED

The authors review the literature regarding TD covering its clinic-radiological features, association with multiple sclerosis (MS), and its differential diagnosis with other neuroinflammatory and non-inflammatory mimicking disorders with an emphasis on atypical forms of demyelination including acute disseminated encephalomyelitis (ADEM), MOG antibody-associated demyelination (MOGAD) and neuromyelitis spectrum disorders (NMOSD). We also review the latest in the acute and long-term treatment of TD.

EXPERT OPINION

It is important that the underlying cause of TD be determined whenever possible to guide the management approach which differs between different demyelinating and other inflammatory conditions. Improved neuroimaging and advances in serum and CSF biomarkers should one day allow early and accurate diagnosis of TD leading to better outcomes for patients.

Progressive Tumefactive Demyelination as the Only Result of Extensive Diagnostic Work-Up: A Case Report

Tumefactive demyelinating lesions belong to the rare variants of multiple sclerosis, posing a diagnostic challenge since it is difficult to distinguish them from a neoplasm or other brain lesions and they require a careful differential diagnosis. This contribution presents the case report of a young female with progressive tumefactive demyelinating brain and spinal cord lesions. An extensive diagnostic process including two brain biopsies and an autopsy did not reveal any explanatory diagnosis other than multiple sclerosis. The patient was treated by various disease-modifying treatments without significant effect and died from ascendent infection via ventriculoperitoneal shunt resulting in Staphylococcus aureus meningitis.

Machine learning-based differentiation between multiple sclerosis and glioma WHO II°-IV° using O-(2-[18F] fluoroethyl)-L-tyrosine positron emission tomography

INTRODUCTION

This study aimed to test the diagnostic significance of FET-PET imaging combined with machine learning for the differentiation between multiple sclerosis (MS) and glioma II°-IV°.

METHODS

Our database was screened for patients in whom FET-PET imaging was performed for the diagnostic workup of newly diagnosed lesions evident on MRI and suggestive of glioma. Among those, we identified patients with histologically confirmed glioma II°-IV°, and those who later turned out to have MS. For each group, tumor-to-brain ratio (TBR) derived features of FET were determined. A support vector machine (SVM) based machine learning algorithm was constructed to enhance classification ability, and Receiver Operating Characteristic (ROC) analysis with area under the curve (AUC) metric served to ascertain model performance.

RESULTS

A total of 41 patients met selection criteria, including seven patients with MS and 34 patients with glioma. TBR values were significantly higher in the glioma group (TBRmax glioma vs. MS: p = 0.002; TBRmean glioma vs. MS: p = 0.014). In a subgroup analysis, TBR values significantly differentiated between MS and glioblastoma (TBRmax glioblastoma vs. MS: p = 0.0003, TBRmean glioblastoma vs. MS: p = 0.0003) and between MS and oligodendroglioma (ODG) (TBRmax ODG vs. MS: p = 0.003; TBRmean ODG vs. MS: p = 0.01). The ability to differentiate between MS and glioma II°-IV° increased from 0.79 using standard TBR analysis to 0.94 using a SVM based machine learning algorithm.

CONCLUSIONS

FET-PET imaging may help differentiate MS from glioma II°-IV° and SVM based machine learning approaches can enhance classification performance.

11C-Methionine PET Identifies Astroglia Involvement in Heart-Brain Inflammation Networking After Acute Myocardial Infarction

Acute myocardial infarction (MI) triggers a local and systemic inflammatory response. We recently showed microglia involvement using translocator protein imaging. Here, we evaluated whether ¹¹C-methionine provides further insight into heart-brain inflammation networking. Methods: Male C57BL/6 mice underwent permanent coronary artery ligation followed by ¹¹C-methionine PET at 3 and 7 d (n = 3). In subgroups, leukocyte homing was blocked by integrin antibodies (n = 5). The cellular substrate for PET signal was identified using brain section immunostaining. Results: ¹¹C-methionine uptake (percentage injected dose/cm³) peaked in the MI region on day 3 (5.9 ± 0.9 vs. 2.4 ± 0.5), decreasing to the control level by day 7 (4.3 ± 0.6). Brain uptake was proportional to cardiac uptake (r = 0.47, P < 0.05), peaking also on day 3 (2.9 ± 0.4 vs. 2.4 ± 0.3) and returning to baseline on day 7 (2.3 ± 0.4). Integrin blockade reduced uptake at every time point. Immunostaining on day 3 revealed colocalization of the l-type amino acid transporter, with glial fibrillary acidic protein-positive astrocytes but not CD68-positive microglia. Conclusion: PET imaging with ¹¹C-methionine specifically identifies an astrocyte component, enabling further dissection of the heart-brain axis in post-MI inflammation.