Usefulness of L-[Methyl-¹¹C]Methionine Positron Emission Tomography in the Treatment of Idiopathic Hypertrophic Cranial Pachymeningitis

Abstract

A 53-year-old man suffered from pulsating headache for 2 months. Magnetic resonance imaging with gadolinium revealed a linear or nodular mass along the left fronto-parietal convexity. Positron emission tomography (PET) with L-[methyl-11 C]methionine ( 11 C-MET) demonstrated increased uptake in the enhanced lesion. Biopsy, obtained by craniotomy, demonstrated granulation with lymphocyte and plasma cell infiltration, suggesting inflammatory changes, and a diagnosis of idiopathic hypertrophic cranial pachymeningitis (IHCP) was made. Steroid therapy resulted in improvement of the clinical symptoms and shrinkage of the enhanced lesion in a week. Follow-up 11 C-MET PET study, after 18 months of steroid therapy, demonstrated significantly decreased uptake in the lesion, so the steroid therapy was discontinued. Neither clinical nor radiological recurrence was observed one year after discontinuation of the steroid therapy. This case of IHCP with increased 11 C-MET uptake, which then decreased after steroid therapy suggests that 11 C-MET PET is a useful monitoring modality for therapeutic efficacy against IHCP, and can indicate the appropriate timing of therapy discontinuation.

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

“…Methionine is an essential neutral amino acid that can readily cross the blood–brain barrier through neutral amino acid transporters and accumulates in an active tumor ( 20 ). The uptake of methionine in a normal brain is relatively low as compared to those with gliomas, hence providing a potential advantage over 2-deoxy-2- 18 fluorodeoxyglucose ( 18 F-FDG) ( 21 , 22 ).…”

High 11C-Methionine Uptake in a Parasellar Inflammatory Pseudotumor

“…2,4,8 The reported histopathological findings of idiopathic hypertrophic cranial pachymeningitis patients with high MET uptake are collagen fibers containing lymphocytes, plasma cells, and histiocytic cells. 6 The present patient's case demonstrates that the mechanism of high MET uptake in an inflammatory pseudotumor (IPT) may be related to a high density of these inflammatory cells. To the best of our knowledge, marked MET uptake in an IPT had not been reported before this case.…”

“…11 C-methionine uptake in inflammation has been reported to involve increased metabolism and active amino acid transport as a result of increased density of inflammatory cells, as well as disruption of the brain-brain barrier 2,4,8 . The reported histopathological findings of idiopathic hypertrophic cranial pachymeningitis patients with high MET uptake are collagen fibers containing lymphocytes, plasma cells, and histiocytic cells 6 . The present patient's case demonstrates that the mechanism of high MET uptake in an inflammatory pseudotumor (IPT) may be related to a high density of these inflammatory cells.…”

“…Although MET PET has been suggested to have high sensitivity (76%–100%) and specificity (75%–100%) for untreated brain tumors, nontumor lesions have been reported to be associated with increased MET uptake 1,3–5 . 11 C-methionine uptake in inflammation has been reported in tumefactive demyelinaton, encephalitis (eg, Rasmussen syndrome, anti– N -methyl- d -aspartate receptor encephalitis), brain abscess, sarcoidosis, progressive multifocal leukoencephalopathy, tuberculoma, toxoplasma, progressive multifocal leukoencephalopathy, idiopathic hypertrophic cranial pachymeningitis, plasma cell granuloma, and more 2,4,6,7 . 11 C-methionine uptake in inflammation has been reported to involve increased metabolism and active amino acid transport as a result of increased density of inflammatory cells, as well as disruption of the brain-brain barrier 2,4,8 .…”

Hypertrophic Pachymeningitis Demonstrated by Whole-Body 67Ga Scintigraphy

“…MRI is useful for the diagnosis of HP as it identifies dural thickening and enhancement. In HP patients, accumulation of 67 Ga, 67 Tl, and 11 C-methionine, and usefulness of monitoring treatment response have been reported 6–9 . 67 Ga scintigraphy is recommended for identifying granuloma in granulomatosis with polyangiitis 10 .…”