18FDG-PET bei intrakraniellen Meningeomen versus Grading, Proliferationsindex, Zelldichte und zytogenetische Analyse

Correlation of 18F-FDG and 11C-methionine uptake on PET/CT with Ki-67 immunohistochemistry in newly diagnosed intracranial meningiomas

OBJECTIVE

We evaluated the uptake of 2-deoxy-2-¹⁸F-fluoro-D-glucose (FDG) and L-[methyl-¹¹C]-methionine (MET) in patients with newly diagnosed intracranial meningiomas and correlated the results with tumor proliferation.

METHODS

Data from 22 patients with newly diagnosed intracranial meningioma (12 grade I and 10 grade II) who underwent both FDG and MET brain PET/CT studies were retrospectively analyzed. The PET images were evaluated by a qualitative method and semiquantitative analysis using standardized uptake value (SUV) (SUV_max and SUV_peak) and tumor-to-reference tissue ratio (T_max/N ratio and T_peak/N ratio). Proliferative activity as indicated by the Ki-67 index was estimated in tissue specimens.

RESULTS

MET PET/CT showed a higher detection rate of meningioma than did FDG PET/CT (100 vs. 46%, respectively). The T_max/N ratio and T_peak/N ratio on MET PET/CT were significantly higher than those on FDG PET/CT (p < 0.001 and p < 0.001, respectively). There was a significant difference between grades I and II with respect to FDG SUVmax (p = 0.003), FDG SUV_peak (p = 0.003), FDG T_max/N ratio (p = 0.02), FDG T_peak/N ratio (p = 0.006), MET SUV_max (p = 0.002), MET SUV_peak (p = 0.002), MET T_max/N ratio (p = 0.002), and MET T_peak/N ratio (p = 0.002). There was a significant correlation between Ki-67 index and FDG PET/CT for SUV_max (p = 0.02), SUV_peak (p = 0.005), and T_peak/N ratio (p = 0.05) and between Ki-67 index and MET PET/CT for SUV_max (p = 0.004), SUV_peak (p = 0.007), T_max/N ratio (p = 0.002), and T_peak/N ratio (p = 0.004).

CONCLUSION

MET PET/CT showed a high sensitivity compared with FDG PET/CT for detection of newly diagnosed WHO grades I and II intracranial meningiomas. Both FDG and MET uptake were found to be useful for evaluating tumor proliferation in meningiomas.

National care among patients with WHO grade I intracranial meningioma

PURPOSE

To analyze the national treatment trends of patients diagnosed with benign intracranial meningioma.

METHODS AND MATERIALS

Data was obtained from the National Cancer Database (NCDB) for patients with WHO grade I meningioma tumors between 2004 and 2014 (190,527 patients), diagnosed by either surgical specimen or diagnostic imaging. Univariable and multivariable analyses (binary logistic models) were performed to generate odds ratios (OR) and investigate factors associated with definitive initial treatment compared to initial observation. Initial treatments considered included surgical resection and/or radiation, including either fractionated external beam radiotherapy (EBRT) or stereotactic radiosurgery (SRS).

RESULTS

The rate of observation increased over time, from 37% in 2004 to 55% in 2014 (p < 0.001). Conjointly, the rate of resection decreased from 50% to 37% from 2004 to 2014 (p < 0.001). The utilization of radiotherapy, including SRS, remained generally stable over time at 6% or less. SRS was more frequently utilized, compared to EBRT, as definitive treatment (4.6% versus 1.7%, respectively, p < 0.001). Compared to Community Cancer programs, patients at Academic/Research programs were more likely to receive definitive initial treatment over observation (OR = 2.909, each p < 0.001).

CONCLUSIONS

There is a national trend favoring initial observation for radiographically diagnosed WHO grade I meningioma. However, patients presenting to academic facilities are more likely to receive definitive initial treatment. Further research into differing approaches among treatment facilities for this common tumor may help clarify this trend.

MRI and FDG PET/CT Uncovered the Cause of a Paraneoplastic Leukemoid Reaction

An 18-year-old man with progressive headache and vomiting for 2 weeks had significantly elevated levels of WBC count, which kept on rising over time during in-hospital evaluation. Exhaustive examinations did not reveal infection or any other explanations of increased WBC count. Instead, brain MRI and FDG PET/CT identified a malignant lesion in the brain without abnormality elsewhere. The pathological examination revealed a rhabdoid meningioma. The level of the WBC counts returned to normal promptly after surgical resection of the tumor, which confirmed the diagnosis of paraneoplastic leukemoid reaction.

Primary Benign Intraosseous Meningioma on (18)F-FDG PET/CT Mimicking Malignancy

We present a case of primary benign intraosseous meningioma in the sphenoid bone mimicking malignancy. A 44-year-old female patient who had a protruding right eye and headache came to our hospital. MRI showed a large, destructive, heterogeneously well-enhancing soft tissue mass in the right sphenoid bone suggesting malignancy. ¹⁸F-FDG PET/CT showed a hypermetabolic mass in the same site with an SUV_max of 9.1 The pathological diagnosis by surgery revealed that this tumor was a WHO grade I transitional meningioma. This case suggests that primary benign intraosseous meningioma may show high ¹⁸F-FDG uptake mimicking a malignancy.

SPECT and PET imaging of meningiomas

Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.

Molecular imaging (PET) of brain tumors

Despite the recognized limitations of (18)Fluorodeoxyglucose positron emission tomography (FDG-PET) in brain tumor imaging due to the high background of normal gray matter, this imaging modality provides critical information for the management of patients with cerebral neoplasms with regard to the following aspects: (1) providing a global picture of the tumor and thus guiding the appropriate site for stereotactic biopsy, and thereby enhancing its accuracy and reducing the number of biopsy samples; and (2) prediction of biologic behavior and aggressiveness of the tumor, thereby aiding in prognosis. Another area, which has been investigated extensively, includes differentiating recurrent tumor from treatment-related changes (eg, radiation necrosis and postsurgical changes). Furthermore, FDG-PET has demonstrated its usefulness in differentiating lymphoma from toxoplasmosis in patients with acquired immune deficiency syndrome with great accuracy, and is used as the investigation of choice in this setting. Image coregistration with magnetic resonance imaging and delayed FDG-PET imaging are 2 maneuvers that substantially improve the accuracy of interpretation, and hence should be routinely employed in clinical settings. In recent years an increasing number of brain tumor PET studies has used other tracers (like labeled methionine, tyrosine, thymidine, choline, fluoromisonidazole, EF5, and so forth), of which positron-labeled amino acid analogues, nucleotide analogues, and the hypoxia imaging tracers are of special interest. The major advantage of these radiotracers over FDG is the markedly lower background activity in normal brain tissue, which allows detection of small lesions and low-grade tumors. The promise of the amino acid PET tracers has been emphasized due to their higher sensitivity in imaging recurrent tumors (particularly the low-grade ones) and better accuracy for differentiating between recurrent tumors and treatment-related changes compared with FDG. The newer PET tracers have also shown great potential to image important aspects of tumor biology and thereby demonstrate ability to forecast prognosis. The value of hypoxia imaging tracers (such as fluoromisonidazole or more recently EF5) is substantial in radiotherapy planning and predicting treatment response. In addition, they may play an important role in the future in directing and monitoring targeted hypoxic therapy for tumors with hypoxia. Development of optimal image segmentation strategy with novel PET tracers and multimodality imaging is an approach that deserves mention in the era of intensity modulated radiotherapy, and which is likely to have important clinical and research applications in radiotherapy planning in patients with brain tumor.

Evaluation of metastatic meningioma with 2-deoxy-2-[18F]fluoro-D-glucose PET/CT

PURPOSE

The purpose of this study was to characterize the 2-deoxy-2-[18F]fluoro-D-glucose (FDG) PET/CT imaging findings of sacral metastatic meningioma.

MATERIALS AND METHODS

An 18-year-old woman with a history of metastatic meningioma, who presented with intractable pain and spasm of the right lower extremity, underwent FDG PET/CT imaging.

RESULTS

FDG PET/CT scan demonstrated a moderately hypermetabolic sacral mass. The biopsy of the lesion was consistent with a high-grade malignant meningioma.

CONCLUSIONS

Although meningioma is typically a benign tumor, in rare instances, it metastasizes. The current case example exhibits moderately increased metabolism despite findings of high-grade malignancy on biopsy.

Positronenemissionstomographie in den Neurowissenschaften

The role of molecular neuroimaging techniques is increasing in the understanding of pathophysiological mechanism of diseases. To date, positron emission tomography is the most powerful tool for the non-invasive study of biochemical and molecular processes in humans and animals in vivo. With the development in radiochemistry and tracer technology, a variety of endogenously expressed and exogenously introduced genes can be analyzed by PET. This opens up the exciting and rapidly field of molecular imaging, aiming at the non-invasive localisation of a biological process of interest in normal and diseased cells in animal models and humans in vivo. Besides its usefulness for basic research positron emission tomography has been proven to be superior to conventional diagnostic methods in several clinical indications. This is illustrated by detection of biological or anatomic changes that cannot be demonstrated by computed tomography or magnetic resonance imaging, as well as even before symptoms are expressed. The present review summarizes the clinical use of positron emission tomography in neuroscience that has helped elucidate the pathophysiology of a number of diseases and has suggested strategies in the treatment of these patients. Special reference is given to the neurovascular, neurodegenerative and neurooncological disease.

Positron emission tomography in a case of intracranial hemangiopericytoma

Due to the low prevalence of hemangiopericytomas (HPCs), data on the biophysiological characteristics of this tumor are rare. Positron emission tomography (PET) demonstrated a sixfold increased uptake of [11C]methionine and hyperperfusion in the HPC, whereas glucose utilization was decreased in this area. This low glucose utilization is in contrast to the high [11C]methionine uptake and the malignancy of these tumors. The characteristics of HPCs in PET described herein for the first time offer additional diagnostic criteria and may help especially to differentiate these tumors from meningiomas.

PET-methionine of skull base neuromas and meningiomas

Eighteen patients with intracranial skull base tumours diagnosed at CT or MR as neuromas or meningiomas were studied with positron emission tomography (PET) using L-(methyl-11C) methionine. Compared with normal cerebellar tissue, the uptake of methionine in the tumours increased more rapidly and reached a higher level, and showed a slow decline after a peak occurring about 5 min after the injection. All the meningiomas exhibited considerably higher accumulation of the tracer compared with the surrounding cerebellar tissue, which made the tumour easy to identify and to demarcate from the surrounding cerebellar tissue, which made the tumour easy to identify and to demarcate from the surrounding structures (tumour to cerebellum ratios 2.62-5.37, mean 3.63). The uptake was homogeneous in all meningiomas, which were all of the syncytial type. The neuromas showed lower contrast against the cerebellum (tumour to cerebellum ratios 1.1-1.87, mean 1.48). Some neuromas displayed an irregular pattern with regions of decreased tracer uptake corresponding to small cystic areas within the neuroma. There was no overlap in methionine uptake between the two tumour groups. The results indicate that PET-methionine may contribute to the evaluation, treatment planning and follow-up of patients with skull base meningiomas and neuromas.