Proton MR spectroscopy of the foramen of Monro region in patients with tuberous sclerosis complex

Arq Neuropsiquiatr 2008;66(2-B):303-307 Proton MR spectroscopy of the foramen of Monro region in patients with tuberous sclerosis complex Arnolfo de Carvalho-Neto1, Isac Bruck2, Sérgio A. Antoniuk2, Edson Marchiori3, Emerson L. Gasparetto3 Abstract – Purpose: To evaluate with 1H-magnetic resonance spectroscopy (MRS) the metabolites rations of the foramen of Monro’s region in patients with tuberous sclerosis complex (TSC).   Method: Twelve patients with TSC and an age and gender-matched control group underwent MR imaging at a 1.5T scanner, and 1H-MRS at the foramen of Monro level with a multivoxel acquisition. Similar volumes of interest were selected in each side of the foramen of Monro and in the basal ganglia (lentiform nuclei). The obtained N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) peak amplitude values and ratios were studied. The statistical analysis was performed and p<0.05 was considered statically significant.   Results: There was no significant difference between the NAA/Cr and Cho/Cr ratios near to the foramen of Monro and basal ganglia of the TSC patients compared with the controls (p>0.05).   Conclusion: The NAA/Cr and Cho/Cr ratios near to the foramen of Monro and basal ganglia of TSC patients are similar to the rations obtained in the control group. Key words: tuberous sclerosis complex, magnetic resonance imaging, proton spectroscopy. Espectroscopia de prótons por RM da região do forame de Monro em pacientes com complexo esclerose tuberosa Resumo – Objetivo: Avaliar através de espectroscopia de prótons as relações dos metabólitos da região do forame de Monro em pacientes com complexo esclerose tuberosa (CET).   Método: Doze pacientes com CET e um grupo controle pareado por sexo e idade realizaram RM em aparelho de 1,5T, e a espectroscopia de prótons foi obtida ao nível do forame de Monro com aquisição multi-voxel. Volumes de interesse similares foram posicionados em cada lado do forame de Monro e nos gânglios da base (núcleos lentiformes). Os valores das relações e amplitudes de pico do N-acetilaspartato (NAA), creatina (Cr) e colina (Cho) foram estudados. A análise estatística foi realizada e valores de p<0,05 foram considerados estatisticamente significativos.   Resultados: Não houve diferença significativa entre as relações NAA/Cr e Cho/Cr na região do forame de Monro e nos gânglios da base dos pacientes com CET comparados com os controles (p>0,05).   Conclusão: As relações NAA/Cr e Cho/Cr na região do forame de Monro e nos gânglios da base de pacientes com CET são semelhantes àquelas obtidas no grupo controle. Palavras-chave: complexo esclerose tuberosa, imagem por ressonância magnética, espectroscopia de prótons. Tuberous sclerosis complex (TSC) is an autosomal dominant disease with incidence of 1:10000 in North America. It is characterized by hamartomatous benign tumors in multiple organs1-3. Central nervous system (CNS) involvement in TSC invariably presents with cortical tubers, subependymal glial nodules, white matter hamartomas and subependymal giant cell astrocytoma (SGCA). Neurological manifestations range from slight or even inexistent to extremely severe symptoms. The most common neu- rological finding is seizure, however other manifestations such as mental retardation in different degrees and obstructive hydrocephaly secondary to the SGCA growth are frequently seen1,3-5. Imaging techniques, especially brain MR imaging and CT, are well established for the diagnosis and follow up of TSC patients4-6. In addition, advanced MR imaging techniques, such as proton magnetic resonance spectroscopy (1H-MRS), which allow non-invasive biochemical evalua- Departments of Radiology1 and Neuropediatrics2, University of Parana, Curitiba PR, Brazil; and Department of Radiology, University of Rio de Janeiro, Rio de Janeiro RJ, Brazil3. Received 16 January 2008, received in final form 31 March 2008. Accepted 26 April 2008. Dr. Arnolfo de Carvalho-Neto – Rua Rolfe Mertens 289 - 80520-670 Curitiba PR - Brasil. E-mail: 303 Tuberous sclerosis complex: foramen of Monro Carvalho-Neto et al. tion of the brain, have been studied in TSC patients. Reduced N-acetylaspartate/creatinine (NAA/Cr) ratio in the cortical tubers has been reported7-9, reflecting the presence of immature neurons and glia, or gliosis. One of the most important complications in patients with TSC is the growth of SGCA near to the foramen of Monro. Several studies have proposed that these tumors could arise from subependymal nodules10,11. In a previous report, the 1H-MRS of a proven SGCA showed high choline (Cho/Cr) (1.60) and low NAA/Cr (0.93) ratios, similar to other brain neoplasms12. The authors suggested the 1HMRS might be a valuable tool for early detection of neoplastic transformation in subependymal nodules arising near to the foramen of Monro in TSC patients. However, no other studies assessed the 1H-MRS features in this region, trying to define wherever the presence of non-neoplastic subependymal nodules and/or calcifications, frequently seen near to the foramen of Monro, could limit the use of the 1H-MRS for the follow up of TSC patients. We aimed to study the foramen of Monro’s region of TSC patients with 1H-MRS, trying to assess if there is any difference on the metabolites ratios comparing patients with and without non-neoplastic nodules in this area and healthy controls. We hypothesize that the metabolites ratios in patients with TSC and non-neoplastic subependymal nodules will be different from those cases without nodules, as well as from the healthy controls. As a result, we believe that these ratios seen in patients with nonneoplastic nodules could be used in the follow-up of TSC patients, aiming early diagnosis of SGCA. METHOD Studied population Twelve patients with TSC (9 females and 3 males; mean age 11.8 years, standard deviation (SD) 2.88) were prospectively recruited. All subjects had TSC diagnosed by standard criteria13. An age and gender paired control group composed of fifteen healthy volunteers (11 females and 4 males; mean age 11.3 years, SD 2.74) was also selected. The control group was recruited after a complete clinical history and detailed physical and neurological examinations, aiming to exclude CNS diseases. The patients and their parents received information regarding the purposes of the study, answered a clinical protocol, and signed the informed consent. The study was approved by the Institutional Review Board of our hospital. All TSC patients underwent brain CT scan with standard technique as a routine follow-up. Two independent radiologists evaluated these exams and compared with previous CT scans trying to define alterations in the size, enlargement or contrast enhancement of the lesions near to the foramen of Monro. No patients had clinical or imaging evidence of SGCA. 304 Arq Neuropsiquiatr 2008;66(2-B) MR imaging protocol All patients underwent MR imaging at a 1.5T scanner (GE Healthcare, Milwaukee, Wis, USA). Morphologic evaluatio (...truncated)