Usefulness of L-[methyl-11c]methionine positron emission tomography in the treatment of idiopathic hypertrophic cranial pachymeningitis--case report

Idiopathic hypertrophic pachymeningitis in a patient with a history of diffuse large B cell lymphoma

A man in his early 70s with a 4-year history of diffuse large B cell lymphoma (DLBCL) was admitted to our hospital with diplopia and achromatopsia. Neurological examination revealed visual impairment, ocular motility disorder and diplopia on looking to the left. Blood and cerebrospinal fluid investigations showed no significant findings. MRI revealed diffusely thickened dura mater and contrast-enhanced structures in the left apical orbit, consistent with hypertrophic pachymeningitis (HP). We performed an open dural biopsy to distinguish the diagnosis from lymphoma. The pathological diagnosis was idiopathic HP, and DLBCL recurrence was ruled out. Following methylprednisolone pulse and oral prednisolone therapy, his neurological abnormalities gradually receded. Open dural biopsy played an important role not only in diagnosing idiopathic HP but also in relieving the pressure on the optic nerve.

High 11C-Methionine Uptake in a Parasellar Inflammatory Pseudotumor

ABSTRACT

A 20-year-old man had left visual impairment and homonymous hemianopsia. MRI findings suggested enlargement of an optic glioma, because optic glioma was indicated by MRI 14 years earlier without a definite pathological diagnosis. 11C-methionine (MET) PET showed high uptake in the tumor in the parasellar region. Transnasal endoscopic biopsy was performed, and an inflammatory pseudotumor (IPT) was diagnosed based on histopathological findings. High MET uptake in a parasellar IPT has apparently not been previously reported. Clinicians should be aware of the possibility of high MET uptake in IPT, because this image could provide an interpretation pitfall.

Hypertrophic Pachymeningitis Demonstrated by Whole-Body 67Ga Scintigraphy

ABSTRACT

Hypertrophic pachymeningitis is a rare inflammatory process characterized by thickening of the dura mater that can be idiopathic or secondary to a variety of conditions such as ANCA-related vasculitis, IgG4-related disease, Sjögren syndrome, rheumatoid arthritis, sarcoidosis, and infections. It can cause various neurological alterations such as headache, cranial nerve disorder, cerebellar disorder, sensory impairment, and weakness. Brain MRI is useful for imaging diagnosis of hypertrophic pachymeningitis, showing focal thickening and enhancement of the dura mater. Here we report 4 cases of idiopathic hypertrophic pachymeningitis where 67Ga clearly accumulated in the dura mater.

Diagnostic and Prognostic Significance of Methionine Uptake and Methionine Positron Emission Tomography Imaging in Gliomas

The present most common image diagnostic tracer in clinical practice for glioma is ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for brain tumors diagnosis and prognosis. PET is a promising molecular imaging technique, which provides real-time information on the metabolic behavior of the tracer. The diffusive nature of glioblastoma (GBM) and heterogeneity often make the radiographic detection by FDG-PET inaccurate, and there is no gold standard. FDG-PET often leads to several controversies in making clinical decisions due to their uptake by normal surrounding tissues, and pose a challenge in delineating treatment-induced necrosis, edema, inflammation, and pseudoprogression. Thus, it is imperative to find new criteria independent of conventional morphological diagnosis to demarcate normal and tumor tissues. We have provided proof of concept studies for ¹¹C methionine-PET (MET-PET) imaging of gliomas, along with prognostic and diagnostic significance. MET-PET is not widely used in the United States, though clinical trials from Japan and Germany suggesting the diagnostic ability of MET-PET imaging are superior to FDG-PET imaging for brain tumors. A major impediment is the availability of the onsite cyclotron and isotopic carbon chemistry facilities. In this article, we have provided the scientific rationale and advantages of the use of MET-PET as GBM tracers. We extend our discussion on the expected pitfalls of using MET-PET and ways to overcome them by incorporating a translational component of profiling gene status in the methionine metabolic pathway. This translational correlative component to the MET-PET clinical trials can lead to a better understanding of the existing controversies and can enhance our knowledge for future randomization of GBM patients based on their tumor gene signatures to achieve better prognosis and treatment outcome.

Management of hypertrophied dural lesions: Is surgery a better option?

It is often difficult to definitively diagnose dural lesions with hypertrophy as they exhibit nonspecific imaging findings and clinical symptoms. Most cases require histopathological evaluation with surgical intervention (such as biopsy). However, complications related to surgical interventions remain as matter of concern. Herein, we analyzed and verified the significance of surgery in 39 patients with hypertrophic dural lesions who were histopathologically diagnosed with surgical interventions. Specimens of dural lesions were obtained successfully, and it was possible to make a definitive diagnosis for each case based on histopathological findings. All patients tolerate the procedures well, and there were no evidences of surgery-related complications during surgical approach to the dura mater. Preoperative and pathological diagnoses varied in eight cases. Our results indicate that histopathological evaluation is important for distinguishing diseases showing dural hypertrophy even if surgical invasiveness is concerned. Neurosurgeons should not hesitate to perform surgery for management of dural lesions with hypertrophy in order to achieve accurate diagnosis.