Magnetic resonance spectroscopy detection of high lipid levels in intraaxial tumors without central necrosis: a characteristic of malignant lymphoma.
OBJECTIVE
The differentiation of malignant lymphomas from gliomas or malignant gliomas by conventional MRI can be difficult. The authors studied Gd-enhanced MR images to obtain a differential diagnosis between malignant lymphomas and gliomas without central necrosis or cystic changes and investigated the diagnostic value of single-voxel proton MR spectroscopy ((1)H-MRS) using different parameters, including lipid levels.


METHODS
This was a retrospective study of patients with primary malignant CNS lymphoma (n = 17) and glioma (n = 122 [Grades I, II, III, and IV in 10, 30, 33, and 49 patients, respectively]) who were treated between 2007 and 2013. The authors focused on 15 patients with homogeneously enhanced primary malignant CNS lymphomas and 7 homogeneously enhanced gliomas. Images of all the included tumors were acquired with (1)H-MRS at 3 T, and the diagnoses were histologically confirmed.


RESULTS
Using a short echo time (1)H-MRS, large lipid peaks were observed in all 17 patients with a malignant lymphoma, in 39 patients (79.6%) with a Grade IV glioma, and in 10 patients (30.3%) with a Grade III glioma. A focus on homogeneously enhanced tumors revealed large lipid peaks in 15 malignant lymphomas that were free of central necrosis on Gd-enhanced T1-weighted images. Conversely, in the 7 homogeneously enhanced gliomas (glioblastoma and anaplastic astrocytoma, n = 2 each; anaplastic oligodendroglioma, diffuse astrocytoma, and pilomyxoid astrocytoma, n = 1 each), lipid peaks were small or absent.


CONCLUSIONS
Large lipid peaks on (1)H-MRS images of tumors without central necrosis were characteristic of malignant lymphomas. Conversely, small or absent lipid peaks in intraaxial tumors without central necrosis were strongly suggestive of glioma.
Departments of 1Neurosurgery and.
Fumiyuki
F
Yamasaki
Departments of 1Neurosurgery and.
Takeshi
T
Takayasu
Departments of 1Neurosurgery and.
Ryo
R
Nosaka
3Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Kasumi, Minami-ku; and 
Vishwa Jeet
VJ
Amatya
Departments of 1Neurosurgery and.
Aidos
A
Doskaliyev
4Department of Clinical Radiology, Hiroshima University Hospital, Hiroshima, Japan.
Yuji
Y
Akiyama
Departments of 1Neurosurgery and.
Atsushi
A
Tominaga
3Pathology, Institute of Biomedical and Health Sciences, Hiroshima University, Kasumi, Minami-ku; and 
Yukio
Y
Takeshima
Department of 2Clinical Oncology and Neuro-oncology Program, and.
Kazuhiko
K
Sugiyama
Departments of 1Neurosurgery and.
Kaoru
K
Kurisu
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007223:Infant; D008055:Lipids / Q000032:analysis*; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism* / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000378:metabolism / Q000473:pathology; D012189:Retrospective Studies; D055815:Young Adult
D008055:Lipids
1H-MRS = proton MR spectroscopy; ADC = apparent diffusion coefficient; ADCMIN = minimum absolute ADC; Cr = creatine; DWI = diffusion-weighted imaging; FLAIR = fluid-attenuated inversion recovery; MRS = MR spectroscopy; NAA = N-acetyl aspartate; ROI = region of interest; VOI = volume(s) of interest; b-n = b value of n sec/mm2; cho = choline; glioma; lipids; mI = myoinositol; malignant lymphoma; oncology; proton MR spectroscopy