Additional diagnostic role of MRI spectroscopy, diffusion and susceptibility imaging in differentiation of CPA masses: our experience with emphasis on schwannomas and meningiomas

Abstract

Background CPA masses are uncommon lesions and usually have quite distinctive imaging features. Still, diagnosis can be challenging in some cases, carrying a significant impact on the choice of treatment and surgical approach. The purpose of this study was to validate the usefulness of MRI spectroscopy, diffusion, and susceptibility in the characterization of CPA masses with the emphasis on the two commonest lesions: schwannomas and meningiomas. Results The study included a total of 27 cases: schwannomas (n = 12), meningiomas (n = 7), epidermoid cysts (n = 2), two chondrosarcomas (n = 2), arachnoid cyst (n = 1), glomus tumor (n = 1), a meningeal metastasis (n = 1), and an endolymphatic sac tumor (n = 1). DWI revealed: eight lesions showed low ADC (<1 × 10−3 mm2/s), 15 lesions with intermediate ADC values (1–1.8 × 10−3 mm2/s), and 4 lesions had high ADC (>1.8 × 10−3 mm2/s.) Meningiomas showed low to intermediate ADC values while schwannomas showed intermediate to high ADC values. A cut-off ADC value of (1 × 10−3 mm2/s) is statistically significant in the differentiation of meningioma from schwannoma. A myoinositol peak was in all 12 schwannomas and single meningioma while 6 meningiomas displayed alanine peak, with a very good statistical significance. Remaining lesions revealed non-specific spectra. SWI made in 18 lesions revealed signal voids in three schwannomas and glomus. Conclusions Though MRI features of CPA masses are distinctive in most clinical settings; MRI spectroscopy, diffusion, and susceptibility can provide highly informative additional data in problematic cases. An intermediate to high ADC value plus myoinositol peak and signal voids of micro-bleeds are highly suggestive of schwannomas. This is in contrary to meningiomas displaying low to intermediate ADC and an alanine peak with no micro-bleeds. The less common lesions revealed non-specific data.

Multicompartmental cystic trigeminal schwannoma as an uncommon differential diagnosis of cerebellopontine angle tumors

“…In more ambiguous cases, a higher ADC value in large neurogenic tumors may be a distinguishing feature from other cerebellopontine angle tumors including meningiomas, which is related to a larger proportion of loose-textured and cystic areas (i.e., Antoni B tissue) [ 23 , 24 ]. It is also suggested that the presence of non-calcification microbleeds, which is also present in our reported case, as well as a myoinositol peak in magnetic resonance spectroscopy, are features for differentiating schwannoma from meningioma [25] .…”

Primary large B-cell lymphoma involving the cerebellopontine angle mimic acoustic schwannoma: Role of MR Spectroscopy in differential diagnosis. A case report

“…These MRS findings were quite similar to primary CNS lymphoma magnetic resonance spectroscopy (MRS) features, which are a significant rise of choline, NAA, and creatine decrease, high Choline/Creatine (Cho/Cr) and Choline/N-acetylaspartate (Cho/NAA) ratios and lipidic peak [ 2 , 3 , 5 , 7 ]. MRS helps to differentiate primary CNS lymphoma from other lesions, such as acoustic neuroma and meningioma: in fact, acoustic neuroma shows myo-inositol peak and high choline peak; myo-inositol peak is maybe related to microglial activation and astrogliosis, a feature that is observed in this lesion [ 2 , 3 , 11 ]. On MRS meningioma spectra are marked by an alanine peak, high choline peak, glutamate (Glu) peak, and low NAA peak; its higher alanine/creatine ratios are useful to differentiate it from other intracranial neoplasms [ 3 , 11 ].…”

“…MRS helps to differentiate primary CNS lymphoma from other lesions, such as acoustic neuroma and meningioma: in fact, acoustic neuroma shows myo-inositol peak and high choline peak; myo-inositol peak is maybe related to microglial activation and astrogliosis, a feature that is observed in this lesion [ 2 , 3 , 11 ]. On MRS meningioma spectra are marked by an alanine peak, high choline peak, glutamate (Glu) peak, and low NAA peak; its higher alanine/creatine ratios are useful to differentiate it from other intracranial neoplasms [ 3 , 11 ]. MRS findings may not be useful to distinguish primary CNS lymphoma from glioblastoma and metastases, but some authors reported higher Glu/Cr, Cho/Cr, and glutamate/glutamate+glutamine (Glu/Glu+Gln) ratios in primary CNS lymphoma than in glioblastoma [ 2 , 5 ].…”

“…All these tumors can cause hearing loss, a condition that is considered an otologic emergency requiring an immediate assessment and therapy when it appears suddenly [6] . Magnetic resonance imaging (MRI) is the gold standard imaging diagnostic tool to evaluate cerebellopontine angle masses and it is considered the method of choice to diagnose and follow-up primary CNS lymphoma [ 2 , 4 , 8 , 10 , 11 ]. Radiological features of this tumor are not specific in conventional MRI and advanced imaging techniques, such as diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), magnetic resonance perfusion (MRP), and MR spectroscopy (MRS) have revealed themselves as useful to differentiate primary CNS lymphomas from other neoplasms [ 2 , 3 , 7 ].…”

Differentiating Pyogenic Brain Abscesses and Tuberculous using Magnetization Transfer MR Imaging and in Vivo Proton MR Spectroscopy

“…Tuberculous brain abscess can be diagnosed only through histopathologic examination as neuroimaging is non-specific. Different studies have been conducted on the use of in vivo proton MR spectroscopy for specifying pyogenic brain abscess and differentiating between brain abscess and glioblastoma multiforme (4)(5)(6)(7)(8)(9) . The cause of brain abscesses can not be specified using conventional MR imaging.…”