Proton magnetic resonance spectroscopy: clinical applications in patients with brain lesions

Revisiting the use of proton magnetic resonance spectroscopy in distinguishing between primary and secondary malignant tumors of the central nervous system

BACKGROUND AND PURPOSE

Conventional magnetic resonance images (MRI) has limitations in distinguishing primary from secondary brain tumors. Proton magnetic resonance spectroscopy (1H-MRS) allows evaluation of the concentration of metabolites in a brain lesion and, hence, better characterization of the tumor. Considering that an accurate diagnosis determines the choice of treatment, our purpose was to assess the usefulness of spectroscopy data for differentiating between primary and secondary brain neoplasms.

MATERIALS AND METHODS

We undertook a retrospective analysis of 61 MRI and 1H-MRS images of patients with histologically confirmed tumors (30 primary tumors and 31 metastatic tumors). The metabolite ratios of Cho/Cr and NAA/Cr at short TE were determined from spectroscopic curves, with a single voxel positioned in the enhancing tumor. Additional variables analyzed along with the metabolites, like as age and gender, allowed the construction of a logistic regression model to predict the tumor's nature. The statistical analysis was done using the R software (version 4.0.3 R Core Team, 2020).

RESULTS

The mean NAA/Cr and Cho/Cr ratios were higher in secondary tumors, with a good correlation between NAA/Cr and Cho/Cr (r = 0.61). The mean age of patients with primary tumors was lower than for secondary tumors (43.9 vs 55.9, respectively). Receiver operating characteristic analysis yielded a cut-off value of 0.4 for the NAA/Cr ratio with an accuracy of 73.8%, a sensitivity of 73.3% and a specificity of 74.2% in predicting metastatic tumors.

CONCLUSION

The model was reasonable in predicting the nature of the tumor and provides an additional tool for analyzing brain tumors.

The human motor cortex microcircuit: insights for neurodegenerative disease

The human motor cortex comprises a microcircuit of five interconnected layers with different cell types. In this Review, we use a layer-specific and cell-specific approach to integrate physiological accounts of this motor cortex microcircuit with the pathophysiology of neurodegenerative diseases affecting motor functions. In doing so we can begin to link motor microcircuit pathology to specific disease stages and clinical phenotypes. Based on microcircuit physiology, we can make future predictions of axonal loss and microcircuit dysfunction. With recent advances in high-resolution neuroimaging we can then test these predictions in humans in vivo, providing mechanistic insights into neurodegenerative disease.

Inhibition of Pediatric Glioblastoma Tumor Growth by the Anti-Cancer Agent OKN-007 in Orthotopic Mouse Xenografts

Pediatric glioblastomas (pGBM), although rare, are one of the leading causes of cancer-related deaths in children, with tumors essentially refractory to existing treatments. Here, we describe the use of conventional and advanced in vivo magnetic resonance imaging (MRI) techniques to assess a novel orthotopic xenograft pGBM mouse (IC-3752GBM patient-derived culture) model, and to monitor the effects of the anti-cancer agent OKN-007 as an inhibitor of pGBM tumor growth. Immunohistochemistry support data is also presented for cell proliferation and tumor growth signaling. OKN-007 was found to significantly decrease tumor volumes (p<0.05) and increase animal survival (p<0.05) in all OKN-007-treated mice compared to untreated animals. In a responsive cohort of treated animals, OKN-007 was able to significantly decrease tumor volumes (p<0.0001), increase survival (p<0.001), and increase diffusion (p<0.01) and perfusion rates (p<0.05). OKN-007 also significantly reduced lipid tumor metabolism in responsive animals [(Lip1.3 and Lip0.9)-to-creatine ratio (p<0.05)], as well as significantly decrease tumor cell proliferation (p<0.05) and microvessel density (p<0.05). Furthermore, in relationship to the PDGFRα pathway, OKN-007 was able to significantly decrease SULF2 (p<0.05) and PDGFR-α (platelet-derived growth factor receptor-α) (p<0.05) immunoexpression, and significantly increase decorin expression (p<0.05) in responsive mice. This study indicates that OKN-007 may be an effective anti-cancer agent for some patients with pGBMs by inhibiting cell proliferation and angiogenesis, possibly via the PDGFRα pathway, and could be considered as an additional therapy for pediatric brain tumor patients.

Advances in high-field magnetic resonance spectroscopy in Alzheimer's disease

Alzheimer's disease (AD) affects several important molecules in brain metabolism. The resulting neurochemical changes can be quantified non-invasively in localized brain regions using in vivo single-voxel proton magnetic resonance spectroscopy (SV 1H MRS). Although the often heralded diagnostic potential of MRS in AD largely remains unfulfilled, more recent use of high magnetic fields has led to significantly improved signal-to-noise ratios and spectral resolutions, thereby allowing clinical applications with increased measurement reliability. The present article provides a comprehensive review of SV 1H MRS studies on AD at high magnetic fields (3.0 Tesla and above). This review suggests that patterned regional differences and longitudinal alterations in several neurometabolites are associated with clinically established AD. Changes in multiple metabolites are identifiable even at early stages of AD development. By combining information of neurochemicals in different brain regions revealing either pathological or compensatory changes, high field MRS can be evaluated in AD diagnosis and in the detection of treatment effects. To achieve this, standardization of data acquisition and analytical approaches is needed.

Spectroscopic correlation and role of Azathioprine in long-term remission in patients of Hashimoto encephalopathy

Hashimoto encephalopathy remains a Rubik's cube for the present generation of clinical research. Myriad presentations have been noted, and observations recorded in few subgroups of patients have gone on only to be trashed by a second group of patients with a completely different clinical profile. Steroids have been traditionally held to be the treatment for this condition, but long-term side effects associated with it limits its use. Although multiple drugs have been tried, yet there exists no data for their long-term efficacy in maintaining remission. No radiological findings have been consistently associated with this condition. We report the use of azathioprine in maintaining long-term remission in one such patient with Hashimoto encephalopathy and the presence of lactate peak in magnetic resonance spectroscopy of the patient, which showed dramatic regression with institution of immunosuppression.

Proton magnetic resonance spectroscopy of periventricular white matter and hippocampus in obstructive sleep apnea patients

BACKGROUND

The purpose of this study was to diagnose the hypoxic impairment by Magnetic resonance spectroscopy (MRS), an advanced MR imaging technique, which could not be visualised by routine imaging methods in patients with obstructive sleep apnea (OSA).

MATERIAL/METHODS

20 OSA patients and 5 controls were included in this prospective research. MRS was performed on these 25 subjects to examine cerebral hypoxemia in specific regions (periventricular white matter and both hippocampi). Polysomnography was assumed as the gold standard. Statistical analysis was assessed by Mann-Whitney U test and Receiver operating characteristics (ROC) curve for NAA/Cho, NAA/Cr and Cho/Cr ratios.

RESULTS

In the periventricular white matter, NAA/Cho ratio in OSA patients was significantly lower than in the control group (p<0.05). There were no statistical differences between the OSA and the control group for NAA/Cho, NAA/Cr and Cho/Cr ratios for both hippocampal regions. Additionally, Cho/Cr ratio in the periventricular white matter region of OSA group was higher than in the control group (p<0.05).

CONCLUSIONS

Hypoxic impairment induced by repeated episodes of apnea leads to significant neuronal damage in OSA patients. MRS provides valuable information in the assessment of hypoxic ischemic impairment by revealing important metabolite ratios for the specific areas of the brain.

Análise do masseter, por espectroscopia de próton, em pacientes com esclerose sistêmica

OBJETIVO: Avaliar a concentração de metabólitos no masseter em portadores de esclerose sistêmica, analisando os índices de creatina, colina, lipídio e lactato, e relacionar com a presença de osteólise mandibular. MATERIAIS E MÉTODOS: Foram selecionados 25 pacientes, sendo 15 com diagnóstico de esclerose sistêmica e agrupados de acordo com a presença (grupo I) ou ausência (grupo II) de osteólise, e 10 indivíduos normais (grupo III, controle). Todos foram submetidos a exame de espectroscopia de próton por ressonância magnética, com técnica PRESS e aquisição tridimensional. RESULTADOS: O estudo dos metabólitos dos três grupos apresentou os mesmos valores absolutos de creatina e lipídio. Os pacientes do grupo I apresentaram maior quantidade de colina em relação aos do grupo III. Já os indivíduos dos grupos I e II apresentaram menor quantidade de lactato em relação aos indivíduos normais. Os índices creatina/lipídio e colina/lactato foram os mesmos em todos os grupos. CONCLUSÃO: Observamos menor quantidade de lactato nos pacientes com esclerose sistêmica (grupos I e II). A colina está aumentada nos pacientes com osteólise mandibular (grupo I). Os índices creatina/colina, creatina/lactato, lipídio/lactato e colina/lipídio foram diferentes entre os grupos estudados. Mais estudos são necessários para a compreensão da participação do masseter no desenvolvimento da osteólise mandibular.

Primary brain T-cell lymphoma after kidney transplantation: a case report

BACKGROUND

Development of primary brain PTLD after kidney transplantation is uncommon, and the incidence of T-cell phenotypes is much more rarely reported in the previous literature. However, prognosis of T-cell PTLD is typically grave, so early diagnosis and treatment are crucial to patient survival.

CASE DESCRIPTION

A 60-year-old woman, who had received a kidney transplant 4 years previously, presented with focal seizures and left hemiparesis. She underwent serial diagnostic neuroimaging, which revealed an undefined etiology of an intracerebral tumor. Pathologic biopsy was mandatory. The tumor was grossly removed and its pathology was determined to be monomorphic T-cell lymphoma. No other organ involvement was noted. The patient underwent chemotherapy with a combination of carmustine, oncovin, and methylprednisolone. The patient's neurologic signs, however, deteriorated rapidly, and the patient finally died of neutropenia and septic shock 1 month after chemotherapy.

CONCLUSIONS

Development of primary brain T-cell PTLD after kidney transplantation is rare and typically has a grave prognosis, emphasizing the importance of early diagnosis and treatment. This case illustrates that the diagnosis of lymphoma can only be confirmed by pathologic biopsy; however, magnetic resonance imaging, in particular magnetic resonance spectroscopy, is a powerful tool for differential diagnosis.