201Tl-SPECT and 1H-MRS study of benign lateral ventricle tumors: differential diagnosis of subependymoma

Parapharyngeal neuroglial heterotopia appearing as high uptake on 18F-FDG PET: case report and literature review of radiographical findings

Parapharyngeal neuroglial heterotopia is a rare entity, and the specific radiographical findings are unclear. We present a case of parapharyngeal neuroglial heterotopia examined with proton magnetic resonance spectroscopy (¹H-MRS) and ¹⁸F-fluorodesoxyglucose positron emission tomography (¹⁸F-FDG PET). Our neonate patient presented with neck mass and polyhydramnios during gestation. Computed tomography and magnetic resonance imaging demonstrated the morphological characteristics, but failed to establish the diagnosis. ¹H-MRS showed a non-malignant pattern, but ¹⁸F-FDG PET demonstrated high glucose metabolism. Complete resection was achieved and the histopathological diagnosis was neuroglial heterotopia. Assessment of biological activity may be useful for both preoperative diagnosis and postoperative evaluation of residual lesions.

MR Spectroscopy to Distinguish between Supratentorial Intraventricular Subependymoma and Central Neurocytoma

PURPOSE

The purpose of this study was to discriminate supratentorial intraventricular subependymoma (SIS) from central neurocytoma (CNC) using magnetic resonance spectroscopy (MRS).

METHODS

Single-voxel proton MRS using a 1.5T or 3T MR scanner from five SISs, five CNCs, and normal controls were evaluated. They were examined using a point-resolved spectroscopy. Automatically calculated ratios comparing choline (Cho), N-acetylaspartate (NAA), myoinositol (MI), and/or glycine (Gly) to creatine (Cr) were determined. Evaluation of Cr to unsuppressed water (USW) was also performed. Mann-Whitney U test was carried out to test the significance of differences in the metabolite ratios. Detectability of lactate (Lac) and alanine (Ala) was evaluated.

RESULTS

Although a statistically significant difference (P < 0.0001) was observed in Cho/Cr among SIS, control spectra, and CNC, no statistical difference was noted between SIS and control spectra (P = 0.11). Statistically significant differences were observed in NAA/Cr between SIS and CNC (P = 0.04) or control spectra (P < 0.0001). A statistically significant difference was observed in MI and/or Gly to Cr between SIS and control spectra (P = 0.03), and CNC and control spectra (P < 0.0006). There were no statistical differences between SIS and CNC for MI and/or Gly to Cr (P = 0.32). Significant statistical differences were found between SIS and control spectra (P < 0.0053), control spectra and CNC (P < 0.0016), and SIS and CNC (P < 0.0083) for Cr to USW. Lac inverted doublets were confirmed in two SISs. Triplets of Lac and Ala were detected in four spectra of CNC.

CONCLUSION

The present study showed that MRS can be useful in discriminating SIS from CNC.

Diffusion weighted MR imaging and proton MR spectroscopy findings of central neurocytoma with pathological correlation

PURPOSE

Three cases of histopathologically confirmed central neurocytoma (CN) are presented, emphasizing diagnostic imaging issues: conventional magnetic resonance imaging with Proton magnetic resonance spectroscopy (MRS) and diffusion-weighted imaging (DWI) findings of CN.

MATERIALS AND METHODS

Patients age ranged from 17 to 32 years, Imaging include a CT scan and MR examination with DWI and proton MRS on a 1.5-T system. DWI and subsequent apparent diffusion coefficient (ADC) were obtained in all. Single voxel MRS was performed prior to surgery using a point resolved spectroscopy sequence (PRESS) with short 35 ms and long echotime (TE) 144 ms, associated with a two-dimensional chemical Shift Imaging (2D-CSI) with 144 ms TE (one case). Histopathological examination included immunostaining with synaptophysin.

RESULTS

With the long TE, a variable amount of glycine with markedly increased choline, very small to almost complete loss of N-acetylaspartate and creatine, and inverted triplet of alanine-lactate were observed in all three patients. Increased glutamate and glutamine complex (Glx) was also observed in all with short TE. DWI demonstrated variable low ADC which appeared well correlated with the tumor signal intensity and cell density: the most homogeneous and highly dense cellular tumor with increased nucleus to cytoplasm ratio demonstrated the lower ADC. Histological pattern was typical in two cases and demonstrated an oligodendroglioma-like pattern in one case. Positivity for synaptophysin confirmed the neuronal origin in all.

CONCLUSION

The demonstration within an intraventricular tumor of both glycine and alanine on MRS along with high choline, bulky Glx and restricted diffusion appear diagnostic of CN.

Proton MR spectroscopy of central neurocytoma using short and long echo time: new proofs for the existence of glycine and glutamate

RATIONALE AND OBJECTIVES

Central neurocytomas (CNCs) are rare benign tumors typically located in the lateral ventricle of the central nervous system. The authors report five patients with CNCs and review 16 previously published studies that included 52 patients with CNCs to explore the magnetic resonance spectroscopic features of CNCs.

MATERIALS AND METHODS

Five patients with CNCs were retrospectively reviewed. They were examined using point-resolved spectroscopic series with short and/or long echo times. The integrals of choline, creatine, and the 3.55-ppm peak were determined using Magnetic Resonance User Interface software, and the metabolite ratios relative to creatine were obtained. In two cases, T2 relaxation times of choline and the metabolite resonance at 3.55 ppm were calculated using data points acquired with different echo times and an exponential decay model.

RESULTS

Consistent with previously published studies, all five patients showed highly increased choline and reduced N-acetylaspartate and creatine. Four patients in the present study and 35 in published data demonstrated prominent peaks at 3.55 ppm, which were assigned to glycine because of its relaxation pattern and long T2 relaxation time. In addition, increased in vivo glutamate and glutamine was also confirmed in three patients examined with short echo times. Alanine and lactate peaks were observed in three and two patients, respectively.

CONCLUSIONS

The present study shows that the 3.55-ppm peak characteristic of CNC should be assigned to glycine according to its T2 relaxation time. Besides increased glycine and choline, the presence of glutamate or glutamine, which appears on series with short echo times, may further confirm the diagnosis of CNC.

[Subependymomas of lateral ventricle. Analysis of our series and review of literature]

Subependymoma is a benign lesion, slow-growing neoplasm, representing 0.2 to 0.7 % of intracranial tumors. They are often clinically silent, incidentally discovered at autopsy. These symptoms are related to big volume. They are attached to the septum pellucidum, leading to hydrocephalus by Monro foramen obstruction. Overall mean age at diagnosis is 39 years with more males than females. At CT-scan, subependymoma shows a slightly low attenuation compared to gray matter. There is no or mild enhancement following contrast injection. On MR T1-weighted imaging, subependymoma is isointense and hyperintense on MR T2-weighted imaging. Intramural calcifications and cystic components are noted in 20 to 30 % of patients. Peritumoral oedema is absent. Immunohistochemicals studies show intense positivity for S-100 and GFAP. The treatment is surgical with an excellent prognosis.

[Imaging of lateral ventricle tumors]

Lateral ventricular neoplasms are rare, and account for 50% of all intraventricular tumors in adults and 25% in children. Although these neoplasms are easily detected with computed tomography (CT) and magnetic resonance imaging (MRI), both techniques are relatively unspecific in identifying the type of tumor. However, few imaging patterns are specific for a particular pathological process and useful conclusions can be made from the morphological appearance of the lesion, its location and enhancement pattern. The aim of this article was to review and illustrate the CT and MRI findings of a wide spectrum of tumors of the lateral ventricle. We reviewed choroid plexus tumors, meningioma, subependymal giant cell astrocytoma, central neurocytoma, and less frequent lesion such as lymphoma and metastases.

[Central neurocytoma: Study of 32 cases and review of the literature]

Central neurocytoma is a rare benign neoplasm of the central nervous system. The intraventricular location close to the Monro foramina and the attachment to the septum pellucidum are characteristic for the diagnosis. However, atypical appearances may be encountered and confused with other neoplasms. The authors report the radiological findings of 32 surgically treated and pathologically confirmed neurocytomas.

Central neurocytoma: proton MR spectroscopy and diffusion weighted MR imaging findings

PURPOSE

To present proton magnetic resonance spectroscopy and diffusion-weighted imaging (DWI) findings of central neurocytoma (CN).

METHODS AND MATERIALS

Imaging findings of seven patients with the histopathological diagnosis of CN (five male and two female; age range, 21-28 years of age) were evaluated retrospectively. In addition to conventional magnetic resonance imaging features, we also assessed the metabolite ratios and tumor normalized apparent diffusion coefficient (NADC), which was calculated by dividing the tumor apparent diffusion coefficient (ADC) values by normal ADC. Approval from our institutional review board was obtained for this review.

RESULTS

The tumor choline/creatine ratios were 5.17+/-2.38, while N-acetyl aspartate/choline and N-acetyl aspartate/creatine ratios were 0.33+/-0.15 and 1.84+/-1.38, respectively. On DWI, tumors had heterogeneous hyperintense appearances when compared with the contralateral parietal lobe white matter and tumor NADC values were 0.63+/-0.05.

CONCLUSION

Significantly increased choline/creatine and decreased N-acetyl aspartate/choline ratios with lower NADC values in CN resemble high-grade gliomas and complicate the diagnosis. Familiarity its physiologic features would help to presurgical diagnosis of ventricular and exraventricular CNs.

Central neurocytoma: a clinical, radiological and pathological study of nine cases

PURPOSE

Central neurocytoma is a rare intraventricular brain tumor that affects young adults and presents with increased intracranial pressure secondary to obstructive hydrocephalus. Typically, it has a favorable prognosis after adequate surgical intervention, but in some cases the clinical course is more aggressive. In this report, we describe the diagnosis and treatment of central neurocytoma in a series of patients at our institution.

PATIENTS AND METHODS

Our series of nine patients (M:F=2:7, mean age, 28.2 years) with ventricular tumors showed typical radiological, histologic and immunohistochemical features of central neurocytoma. Most patients received craniotomy with removal of the tumor through transcallosal or transcortical approach. The surgical and histopathologic data of these patients were reviewed and analyzed.

RESULTS

The prognosis is generally favorable. Although most patients were alive and well at the last follow-up, two developed recurrence. Typical histologic features of recurrent neurocytoma include high proliferative activity (MIB-1 labeling index: 2.0-6.8%), prominent vascular proliferation and remarkable synaptophysin expression. Two patients (non-recurrent) died during follow-up due to sepsis or central failure. The MIB-1 labeling indices were as high as 2.2-5.4% for these two patients.

CONCLUSION

Although central neurocytoma is generally a benign neoplasm, some variant forms of recurrence are also present. Complete resection provides favorable long-term prognosis in most cases. Recurrent tumors are often local and the patients seem to recover well after a second resection followed by radiotherapy. Histologic features such as tumor proliferation (MIB-1 labeling index), vascular proliferation, and synaptophysin expression are often prominent in the recurrent tumor. We recommend that these histologic features be considered for tumor recurrence during treatment and follow-up of these patients.

Automated MR spectroscopy of intra- and extraventricular neurocytomas

PURPOSE

We evaluated the automated magnetic resonance spectroscopic (MRS) characteristics of intra- and extraventricular neurocytomas.

MATERIALS AND METHODS

One extra- and 4 intraventricular neurocytomas were studied. Automated single-voxel proton MRS was performed with a 1.5 T MR scanner. The results of 6 total automated MR spectra were analyzed for each tumor.

RESULTS

Lactate resonance was detected as a doublet in 3 MR spectra of 2 intraventricular neurocytomas. A peak corresponding to N-acetylaspartate (NAA) was small in 5 MR spectra of 4 intraventricular neurocytomas. Creatine (Cr) resonance was detected in all 6 MR spectra. Prominent choline (Cho) resonance was found in all 6 MR spectra. The myoinositol (MI) and/or glycine (Gly) peaks were large in 3 MR spectra of 2 intraventricular neurocytomas.

CONCLUSION

The presence of the NAA signal and high MI and/or Gly signals may be characteristic features of intraventricular neurocytomas. A combination of prominent Cho resonance and detectable Cr resonance is a common feature of both intra- and extraventricular neurocytomas.

Central neurocytoma: typical magnetic resonance spectroscopy findings and atypical ventricular dissemination

PURPOSE

Central neurocytomas (CNCs) are rare neuronal tumors that have a favorable prognosis and lower rate of recurrence compared with other intraventricular neoplasms. Although it may be difficult to distinguish CNC on conventional neuroimaging, typical MR spectroscopy (MRS) features have been reported. We describe the MRI and MRS features of CNC.

MATERIALS AND METHODS

Eight patients with CNC were reviewed. Three patients underwent presurgical in vivo single-voxel MRS at short echo time (TE, 35 ms) and multi-voxel MR spectroscopic imaging at long TE (144 ms). The surgically resected tumor specimen of one of these patients was also studied ex vivo using high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance.

RESULTS

All eight tumors were located in the lateral ventricles. In six patients, CNC extended into the third ventricle, and in two patients the tumor showed further contiguous intraventricular dissemination into the fourth ventricle. In all three patients who underwent MRS, a characteristic metabolite peak was detected at 3.55 parts per million (ppm) at both long and short TE. HRMAS confirmed the presence of elevated glycine (Gly) at 3.55 ppm, without increase in the concentration of myo-inositol found at the same chemical shift. Elevated choline (at 3.2 ppm) was also seen in all three patients.

CONCLUSION

On MRS, CNCs have a typical appearance with a metabolite peak at 3.55 ppm due to increased Gly, and this feature may be helpful in presurgical diagnosis. Although they are rare benign intraventricular tumors, in atypical cases, CNCs can show extensive intraventricular dissemination into the fourth ventricle.