Space-occupying Brain Lesions Research Articles

Enhancing the Reliability of Intraoperative Ultrasound in Pediatric Space-Occupying Brain Lesions

Intraoperative ultrasound (IOUS) may aid the resection of space-occupying brain lesions, though technical limits may hinder its reliability. IOUS (MyLabTwice®, Esaote, Italy) with a microconvex probe was utilized in 45 consecutive cases of children with supratentorial space-occupying lesions aiming to localize the lesion (pre-IOUS) and evaluate the extent of resection (EOR, post-IOUS). Technical limits were carefully assessed, and strategies to enhance the reliability of real-time imaging were accordingly proposed. Pre-IOUS allowed us to localize the lesion accurately in all of the cases (16 low-grade gliomas, 12 high-grade gliomas, eight gangliogliomas, seven dysembryoplastic neuroepithelial tumors, five cavernomas, and five other lesions, namely two focal cortical dysplasias, one meningioma, one subependymal giant cell astrocytoma, and one histiocytosis). In 10 deeply located lesions, IOUS with hyperechoic marker, eventually coupled with neuronavigation, was useful to plan the surgical route. In seven cases, the administration of contrast ensured a better definition of the vascular pattern of the tumor. Post-IOUS allowed the evaluation of EOR reliably in small lesions (<2 cm). In large lesions (>2 cm) assessing EOR is hindered by the collapsed surgical cavity, especially when the ventricular system is opened, and by artifacts that may simulate or hide residual tumors. The main strategies to overcome the former limit are inflation of the surgical cavity through pressure irrigation while insonating, and closure of the ventricular opening with Gelfoam before insonating. The strategies to overcome the latter are avoiding the use of hemostatic agents before IOUS and insonating through normal adjacent brain instead of corticotomy. These technical nuances enhanced the reliability of post-IOUS, with a total concordance to postoperative MRI. Indeed, the surgical plan was changed in about 30% of cases, as IOUS showed a residual tumor that was left behind. IOUS ensures reliable real-time imaging in the surgery of space-occupying brain lesions. Limits may be overcome with technical nuances and proper training.

The value of convolutional neural networks-based deep learning model in differential diagnosis of space-occupying brain diseases.

It is still a challenge to differentiate space-occupying brain lesions such as tumefactive demyelinating lesions (TDLs), tumefactive primary angiitis of the central nervous system (TPACNS), primary central nervous system lymphoma (PCNSL), and brain gliomas. Convolutional neural networks (CNNs) have been used to analyze complex medical data and have proven transformative for image-based applications. It can quickly acquire diseases' radiographic features and correct doctors' diagnostic bias to improve diagnostic efficiency and accuracy. The study aimed to assess the value of CNN-based deep learning model in the differential diagnosis of space-occupying brain diseases on MRI. We retrospectively analyzed clinical and MRI data from 480 patients with TDLs (n = 116), TPACNS (n = 64), PCNSL (n = 150), and brain gliomas (n = 150). The patients were randomly assigned to training (n = 240), testing (n = 73), calibration (n = 96), and validation (n = 71) groups. And a CNN-implemented deep learning model guided by clinical experts was developed to identify the contrast-enhanced T1-weighted sequence lesions of these four diseases. We utilized accuracy, sensitivity, specificity, and area under the curve (AUC) to evaluate the performance of the CNN model. The model's performance was then compared to the neuroradiologists' diagnosis. The CNN model had a total accuracy of 87% which was higher than senior neuroradiologists (74%), and the AUC of TDLs, PCNSL, TPACNS and gliomas were 0.92, 0.92, 0.89 and 0.88, respectively. The CNN model can accurately identify specific radiographic features of TDLs, TPACNS, PCNSL, and gliomas. It has the potential to be an effective auxiliary diagnostic tool in the clinic, assisting inexperienced clinicians in reducing diagnostic bias and improving diagnostic efficiency.

Familial and syndromic forms of arachnoid cyst implicate genetic factors in disease pathogenesis.

Arachnoid cysts (ACs) are the most common space-occupying lesions in the human brain and present significant challenges for clinical management. While most cases of ACs are sporadic, nearly 40 familial forms have been reported. Moreover, ACs are seen with increased frequency in multiple Mendelian syndromes, including Chudley-McCullough syndrome, acrocallosal syndrome, and autosomal recessive primary ciliary dyskinesia. These findings suggest that genetic factors contribute to AC pathogenesis. However, traditional linkage and segregation approaches have been limited in their ability to identify causative genes for ACs because the disease is genetically heterogeneous and often presents asymptomatically and sporadically. Here, we comprehensively review theories of AC pathogenesis, the genetic evidence for AC formation, and discuss a different approach to AC genomics that could help elucidate this perplexing lesion and shed light on the associated neurodevelopmental phenotypes seen in a significant subset of these patients.

Enhanced expression of autophagy-related p62 without increased deposits of neurodegeneration-associated proteins in glioblastoma and surrounding tissue - An autopsy-based study.

Neurodegenerative diseases are a major health burden. The underlying causes are not yet fully understood, but different mechanisms such as cell stress and chronic inflammation have been described as contributing factors. Neurodegenerative changes have been observed in the vicinity of brain tumors, typically around slowly growing benign lesions. Moreover, in‐vitro data suggest a potential induction of pathological tau deposits also in glioblastoma, a highly malignant and proliferative brain cancer. The aim of this study was to evaluate neurodegeneration‐associated protein deposition and autophagy as well as microglial activation within and surrounding glioblastoma. Post‐mortem brain tissue of 22 patients with glioblastoma was evaluated immunohistochemically for phosphorylated tau, beta‐amyloid, alpha‐synuclein and phosphorylated TDP‐43. Additionally, the autophagy marker p62 and the microglial marker HLA‐DR were investigated. The data was compared to 22 control cases and ten cases with other space occupying brain lesions. An increase of p62‐immunoreactivity was observed within and adjacent to the glioblastoma tumor tissue. Moreover, dense microglial infiltration in the tumor tissue and the immediate surrounding brain tissue was a constant feature. Deposition of neurodegeneration‐associated proteins was found in the majority of cases (86.4%) but in distant sites. These findings suggested a preexisting neurodegenerative pathology, which followed a typical distributional pattern: ten cases with Alzheimer disease neuropathological changes, including two severe cases, eight cases with primary age‐related tauopathy, six cases with aging‐related tau astrogliopathy and one case with progressive supranuclear palsy. Collectively, our data suggests enhanced autophagy in glioblastoma tumor cells and the surrounding brain. The variety and distribution of distant neurodegeneration‐associated protein aggregates observed in the majority of cases, suggest a preexisting rather than a tumor‐induced neurodegenerative condition.

A case of moderate depression with somatic symptoms and incidental finding of retrocerebellar arachnoid cyst

Arachnoid cysts are benign space-occupying brain lesions that contain cerebrospinal fluid which is mostly congenital in origin. Cases are mostly detected incidentally on neuro-imaging and neuropsychiatric manifestations are less common and under-recognized. Arachnoid cyst sometimes may be associated with seizure, headache, cranial nerve deficits, hydrocephalus, etc. A 23-year-old married female from rural India presented with headache, insomnia, low mood, lethargy, persisting for the past 6 months without any obvious stress factors. She also informed that she had few episodes of unresponsiveness without any features such as tongue biting, confusion, injury, or involuntary micturition and defecation. Her EEG report was within normal limit and MRI report confirmed the presence of Retro-cerebellar Arachnoid cyst in and around midline. Detail neurological and ophthalmological examination was done and findings were within normal limits. She was treated with Amitriptyline, Pregabalin, and Paracetamol. Psychotherapy was initiated for adequate management of her depressive symptoms and responded well. It can be emphasized that patients who are reporting with symptoms such as headache a detail evaluation should be done to find out organic etiology. Depressive and cognitive symptoms and its association with arachnoid cyst may depend upon the location of the lesion and further research is required to establish its causal relationship.

FMRI Retinotopic Mapping in Patients with Brain Tumors and Space-Occupying Brain Lesions in the Area of the Occipital Lobe.

Simple SummaryFunctional magnetic resonance imaging (fMRI) in patients with brain tumors enables the visualization of eloquent cortical areas and can be used for planning surgical interventions and assessing the risk of postoperative functional deficits. While preoperative fMRI paradigms used to determine the localization of speech-critical or motor areas dominate the literature, there are hardly any studies that investigate the retinotopic organization of the visual field in patients with occipital lesions or tumors. The aim of this study was to evaluate the effect of a brain tumor or space-occupying brain lesions on the retinotopic organization of the occipital cortex, the activation of and the functional connectivity between cortical areas involved in visual processing. We found a high degree of similarity in the activation profiles of patients and healthy controls, indicating that the retinotopic organization of the visual cortex can reliably be described by fMRI retinotopic mapping as part of the preoperative examination of patients with tumors and space-occupying brain lesions.Functional magnetic resonance imaging (fMRI) is a valuable tool in the clinical routine of neurosurgery when planning surgical interventions and assessing the risk of postoperative functional deficits. Here, we examined how the presence of a brain tumor or lesion in the area of the occipital lobe affects the results of fMRI retinotopic mapping. fMRI data were evaluated on a retrospectively selected sample of 12 patients with occipital brain tumors, 7 patients with brain lesions and 19 control subjects. Analyses of the cortical activation, percent signal change, cluster size of the activated voxels and functional connectivity were carried out using Statistical Parametric Mapping (SPM12) and the CONN and Marsbar toolboxes. We found similar but reduced patterns of cortical activation and functional connectivity between the two patient groups compared to a healthy control group. Here, we found that retinotopic organization was well-preserved in the patients and was comparable to that of the age-matched controls. The results also showed that, compared to the tumor patients, the lesion patients showed higher percent signal changes but lower values in the cluster sizes of the activated voxels in the calcarine fissure region. Our results suggest that the lesion patients exhibited results that were more similar to those of the control subjects in terms of the BOLD signal, whereas the extent of the activation was comparable to that of the tumor patients.

The Safety and Efficacy of General Anesthesia Bronchoscopy in Patients With Metastatic Brain Lesions

Background: Lung cancer is the leading cause of cancer-related death in the United States and has a high propensity to metastasize to the brain. According to multiple studies, primary lung malignancy is the leading cause of brain metastasis. In many cases, patients with suspected lung cancer will present with brain metastasis and require bronchoscopy for diagnostic and therapeutic purposes, specifically, endobronchial ultrasound transbronchial needle aspiration, which can both diagnose and stage lung cancer. There is a concern that general anesthesia and bronchoscopic procedures can increase intracranial pressures and lead to neurological complications. Methods: We conducted a retrospective study evaluating the safety of performing bronchoscopy under general anesthesia in patients with known space-occupying brain lesions at Keck Hospital of the University of Southern California between 2015 and 2018. Results: Overall, 10% of patients who underwent bronchoscopy had brain lesions at the time of the procedure, similar to previous studies, which showed rates of 10% to 20%. Overall complication rate with general anesthesia and bronchoscopy was 21% in our patients with brain lesions; however, only 3.5% of patients experienced serious adverse events, including respiratory failure or neurological deterioration requiring intensive care unit admission and intervention. There was no difference in complications among those with brain metastasis and those without who underwent bronchoscopy. Conclusion: These results confirm that the rate of serious complications in patients with space-occupying brain lesions who undergo bronchoscopy with general anesthesia is similar to that in patients without brain lesions, indicating that bronchoscopy can be performed safely in this patient population.

2722 Thinking With the Gut: An Unfortunate Case of Metastatic Gastric Cancer

INTRODUCTION: Metastatic brain tumors represent 20-40% of intracranial neoplasms [Table 1]. Although rare, the incidence of brain metastasis from the gastrointestinal (GI) tract has increased likely secondary to prolonged survival of patients with GI cancers. Symptoms of metastatic spread parallels space-occupying lesions in brain: confusion, headache, visual disturbances, nausea, vomiting, altered mental status, gait abnormalities, seizures, and decreased consciousness. Current literature estimates 0.63% of gastric adenocarcinoma (GA) cases metastasize to the brain1. Here, we present an unusual case of metastatic brain spread of GA. CASE DESCRIPTION/METHODS: 59-year-old male with history of hypertension, tobacco use, GERD, and gastric cancer who presented with a one-week history of headaches, nausea and vomiting, and decreased visual acuity. His gastric cancer had previously been treated with neoadjuvant chemotherapy, radiation and partial esophagectomy with repeat screening via computed tomography (CT). A CT of his head showed vasogenic edema in the right frontal lobe, raising concern for metastatic disease versus primary CNS lesion [Figure 1]. A magnetic resonance imaging (MRI) brain showed an enhancing mass in the anterior-inferior right frontal lobe with metastatic disease as well as leptomeningeal carcinomatosis [Figure 2]. He underwent right frontal burr-hole for stereotactic biopsy of the right frontal tumor. Pathology was consistent with metastatic adenocarcinoma. He was started on IV steroids and began whole brain radiation therapy. He was not a surgical candidate and was unstable for chemotherapy. His family transitioned him to comfort care measures after which he shortly passed. DISCUSSION: Gastric cancer is the fourth most common cancer worldwide and the second most common cause of cancer-related death. Current literature estimates GA incidence rate to be 6.7/100,000 persons with a mortality rate of 3.4/100,000 persons in the United States. Risk factors include H. pylori, male sex, Asian/Pacific island ethnicity, obesity, smoking, and a diet rich in smoked, salted, pickled foods. Our patient demonstrated an unusual case of metastatic GA without evidence of visceral metastases. His case was further complicated as he had screening CT scans at six month intervals which had been within normal limits until his presentation. His case unfortunately demonstrates the ominous prognosis of patients with brain metastasis, prompting the need for increased surveillance and brain imaging.

Arachnoid Cyst Causing Depression and Neuropsychiatric Symptoms: a Case Report

Arachnoid cysts are benign space-occupying brain lesions that contain cerebrospinal fluid. Most cases are congenital in origin, caused by failed fusion of the arachnoid membrane early in fetal development. Cases are often incidentally detected on neuroimaging; however, rarely patients present with neuropsychiatric manifestations when cysts expand and cause a midline shift, compression of nearby brain tissue or cerebrospinal fluid compartments or both. We report a case of a 56-year-old woman with no past history or family history of psychiatric illness who developed acute-onset right-sided weakness, depressive symptoms, and other neuropsychiatric deficits. A diagnosis of organic mood disorder caused by an arachnoid cyst was made. Her symptoms and neuropsychiatric deficits remitted after cyst marsupialisation by open craniotomy. Therefore, it is important to investigate the organic aetiology in elderly patients who present with simultaneous mood disorder and cognitive dysfunction.

The role of diffusion-weighted MRI in the evaluation and differentiation of space-occupying brain lesions

Objectives: The aim of this study was to assess the role of diffusion-weighted MRI in the evaluation and differentiation of space-occupying brain lesions in patients whose conventional MRI (cMRI) examination revealed abnormal imaging features suggestive of space-occupying brain lesions. Diffusion-weighted imaging provides information about the physiological properties of the tumor that have been linked to cellularity, structural integrity, and necrotic transformation of brain or tumor tissue. MR diffusion imaging has become a powerful, multifaceted tool both for very basic clinical needs and for advanced, specialized diagnosis and treatment planning. Background: This study included 75 patients who presented with acute focal neurological deficit or with manifestations of space-occupying brain lesions. All of these patients were subjected to cMRI examination of the brain and to diffusion-weighted MRI. Postprocessing of apparent diffusion coefficient (ADC) maps was generated for all patients. Standard mean ADC values were calculated automatically and expressed in 10−S mm2/s. The cutoff value of 1 × 10−3 mm2/s was used to differentiate restricted areas from nonrestricted areas. Patients and methods: Among the 75 studied patients, the final diagnosis was intracranial neoplastic lesions (group A) in 46 patients (61.3%), non-neoplastic tumor-like lesions (group B) in 17 patients (22.6%), intracranial suppuration (group C) in seven patients (9.3%), and intracerebral hemorrhage (group D) in five patients (6.6%). Analysis of calculated ADC values using the t-test, the U-test, analysis of variance, and the c2-test revealed statistical difference of ADC values between high-grade/low-grade gliomas, abscesses, and intracranial necrotic neoplasms including glioblastoma multiforme, lymphoma/high-grade astrocytoma, medulloblastoma/ependymoma and pilocytic astrocytoma, and epidermoid/arachnoid cysts. Results On the basis of simplicity of the method and the results obtained, diffuse-weighted imaging should be used routinely as a valuable noninvasive tool besides cMRI, whenever available, to reach a definitive final diagnosis.

Fever, Hemiparesis and Hyponatraemia in a 63-year-old. HIV, another Great Masquerader?

The authors describe the unusual case of a 63-year-old patient who was referred with fever and lethargy, and was found to be hyponatraemic. The patient subsequently developed hemiparesis, and neuroradiology showed several space-occupying brain lesions. The cause was later identified as cerebral toxoplasmosis in undiagnosed Acquired Immunodeficiency Syndrome (AIDS).

Safety of Flexible Bronchoscopy, Rigid Bronchoscopy, and Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in Patients With Malignant Space-Occupying Brain Lesions

Bronchoscopy in patients with space-occupying brain lesions is anecdotally felt to carry a high risk of neurologic complications. We conducted a retrospective cohort study of patients with evidence of a malignant, space-occupying brain lesion who were referred for flexible or rigid bronchoscopy or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). The primary outcome of interest was the incidence of neurologic complications following the procedures in these patients. Of the 103 enrolled patients, flexible bronchoscopy was performed in 41, rigid bronchoscopy in 12, and EBUS-TBNA in 50. Among these patients, 41 (40%) had evidence suggestive of increased intracranial pressure on imaging. Among all study patients, none (95% CI, 0-0.035) had neurologic, procedure-specific, or sedation-specific complications, and the level of care was not escalated in any of these patients. On the basis of our findings, we recommend that procedures such as flexible or rigid bronchoscopy or EBUS-TBNA in patients with malignant space-occupying brain lesions should be considered reasonably safe as long as neurologic findings are stable.

CSF neopterin level as a diagnostic marker in primary central nervous system lymphoma.

The diagnosis of primary central nervous system lymphoma (PCNSL) can be challenging. PCNSL lesions are frequently located deep within the brain, and performing a cerebral biopsy is not always feasible. The aim of this study was to investigate the diagnostic value of CSF neopterin, a marker of neuroinflammation, in immunocompetent patients with suspected PCNSL. We retrospectively reviewed the characteristics of 124 patients with brain tumor (n = 82) or an inflammatory CNS disorder (n = 42) in whom CSF neopterin levels were assessed. Twenty-eight patients had PCNSL, 54 patients had another type of brain tumor (glioma n = 36, metastasis n = 13, other n = 5), and 13 patients had a pseudotumoral inflammatory brain lesion. CSF neopterin levels were significantly higher in the patients with PCNSL than in those with other brain tumors (41.8 vs 5.1 nmol/L, P < .001), those with pseudotumoral inflammatory brain lesions (41.8 vs 4.3 nmol/L, P < .001), and those with nontumefactive inflammatory CNS disorders (41.8 vs 3.8 nmol/L, P < .001). In the 95 patients with space-occupying brain lesions, at a cutoff of 10 nmol/L, the sensitivity of this approach was 96% and the specificity was 93% for the diagnosis of PCNSL. The positive and negative predictive values were 84% and 98%, respectively. Assessing CSF neopterin levels in patients with a suspected brain tumor might be helpful for the positive and differential diagnosis of PCNSL. A prospective study is warranted to confirm these results.

Corticospinal MRI tractography in space-occupying brain lesions by diffusion tensor and kurtosis imaging methods.

Recently, DKI-based tractography has been developed, showing improved crossing-fiber resolution in comparison to deterministic DTI-based tractography in healthy subjects. In this work, DTI and DKI-based tractography methods were compared regarding the assessment of the corticospinal tract in patients presenting space-occupying brain lesions near cortical motor areas. Nine patients (4 males) aged 23 to 62 years old, with space-occupying brain lesions (e.g. tumors) were studied for pre-surgical planning using a 1.5T MRI scanner and a 12-channel head coil. In 5 patients diffusion data was acquired along 64 directions and in 4 patients along 32 directions both with b-values 0, 1000 and 2000 s/mm2. Corticospinal tracts were estimated using deterministic DTI and DKI methods and also using probabilistic DTI. The superior cerebellar peduncles and the motor cortical areas, ipsilateral and contralateral to the lesions, were used as seed regions-of-interest for fiber tracking. Tracts courses and volumes were documented and compared between methods. Results showed that it was possible to estimate fiber tracts using deterministic DTI and DKI methods in 8/9 patients, and using the probabilistic DTI method in all patients. Overall, it was observed that DKI-based tractography showed more voluminous fiber tracts than when using deterministic DTI. The DKI method also showed curvilinear fibers mainly above lesions margins, which were not visible with deterministic DTI in 5 patients. Similar tracts were observed when using probabilistic DTI in 3 of those patients. Results suggest that the DKI method contribute with additional information about the corticospinal tract course in comparison with the DTI method, especially with subcortical lesions and near lesions’ margins. Therefore, this study suggests that DKI-based tractography could be useful in MRI and hybrid PET-MRI pre-surgical planning protocols for improved corticospinal tract evaluation.

Role of dynamic CT perfusion study in evaluating various intracranial space-occupying lesions.

Aims:Differentiating intracranial mass lesions on CT scan is challenging. The purpose of our study was to determine the perfusion parameters in various intracranial space-occupying lesions (ICSOL), differentiate benign and malignant lesions, and differentiate between grades of gliomas.Materials and Methods:We performed CT perfusion (CTP) in 64 patients, with age ranging from 17 to 68 years, having space-occupying lesions in brain and calculated relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV).Results:We found significantly lower perfusion in low-grade gliomas as compared to high-grade tumors, lymphoma, and metastases. Similarly in infective lesions, TWT and abscesses showed significantly lower perfusion compared to TOT. In ring enhancing lesions, capsule of TWT showed significantly lower perfusion as compared to abscesses, TOT, and metastases.Conclusion:Thus, in conclusion, infective lesions can be differentiated from tumors like lymphomas, high-grade gliomas, or metastases based on perfusion parameters. The cut off value of rCBV 1.64 can be used to differentiate between low grade and high grade gliomas. However, depending only on perfusion parameters, differentiation between the tumors like lymphomas, high-grade gliomas, and metastases may not be possible.

Optochiasmatic tuberculoma as the sole manifestation of late recurrent tuberculosis

Brain tuberculomas account for 10-20% of space occupying brain lesions in developing countries. Most lesions are observed at time of tuberculosis diagnosis or soon after starting treatment. We herein describe a 32 year-old patient with a 14-month history of headache and progressive visual loss. Her past medical history revealed pulmonary tuberculosis treated eight years before. A brain MRI showed a T1- and T2-weighted isointense contrast-enhancing lesion in the optic chiasm. A presumptive diagnosis of optochiasmatic tuberculoma was made and isoniazid, rifampin, pyrazinamide, and ethambutol were started. Despite treatment, the patient evolved to blindness. The prompt recognition of this condition is extremely important since the presence of optochiasmal enhancement is associated with blindness in patients with tuberculosis.

Transcranial sonography of the cerebral parenchyma: Update on clinically relevant applications

Transcranial B-mode sonography (TCS) is a neuroimaging technique that displays the brain parenchyma and the intracranial ventricular system through the intact skull. Sophisticated TCS systems can currently achieve a higher image resolution of echogenic deep brain structures than MRI under clinical conditions. The different imaging principle of TCS allows visualization of characteristic changes in several neurodegenerative diseases that can hardly be visualized with other imaging methods, such as substantia nigra hyperechogenicity in Parkinson's disease (PD), and lenticular nucleus hyperechogenicity in atypical Parkinsonian syndromes. The intracranial ventricular system and a midline shift due to space-occupying brain lesions (e.g., intracerebral hematomas) are reliably assessed with TCS. The present paper reviews recent studies on diagnostic TCS applications that, as a result, can be recommended for routine use in clinical practice. These applications include the bedside monitoring of space-occupying lesions in acute stroke patients, the early and differential diagnosis of PD, and the postoperative position control of deep brain stimulation electrodes. Novel technologies such as in-time fusion of TCS with MRI scans, automated detection of intracranial target structures, and improved 3D-image analysis promise an even wider application of TCS in the coming years.

Cutoff Value of Choline Concentration Reliably Reveals High-Grade Brain Tumors among Other Contrast-Enhancing Brain Lesions

To evaluate whether there is a cutoff value for a metabolite concentration measured by 1 H MR spectroscopy (MRS), which can be used to differentiate malignant brain tumors (high-grade gliomas, primary CNS lymphomas [PCNSL] and metastases) from other contrast-enhancing lesions like low-grade gliomas and non-neoplastic lesions. 1 H MRS was performed in 252 consecutive patients with space-occupying brain lesions which were enhanced with application of a contrast agent. Concentrations of N-acetyl-aspartate, total creatine, choline containing metabolites (total choline, tCho), lipids, and lactate were evaluated from the contrast-enhancing part of the lesions and from the normal appearing brain tissue. Linear discriminant analysis was used to find the best predictor for malignant brain tumors. In addition, receiver operating characteristic analysis (ROC) was performed to determine a cutoff value for the best predictor in detecting malignant brain tumors with a specificity of >95%. All brain tumors and 20 out of 47 nonneoplastic lesions were examined histopathologically. The remaining 27 diagnoses were based on MR imaging, clinical findings, and follow-up. The final diagnosis was 134 high-grade gliomas (WHO grade III/IV), 36 metastases, 9 PCNSL, 8 low-grade gliomas (WHO grade I/II), 34 infections, 9 infarctions, 2 hematomas, and 2 vasculitides. 18 patients were excluded due to insufficient spectral quality. The tCho concentration was the best predictor to differentiate malignant brain tumors from enhancing low-grade gliomas or non-neoplastic lesions (F=26.6 [df: 25.833], p<0.0005). The ROC revealed that a cutoff tCho value, based on an increase of ≥40% compared to normal, yielded a specificity of 100% and a sensitivity of 89.4% to correctly diagnose a malignant brain tumor. 1 H MRS reliably differentiates malignant brain tumors from other contrast-enhancing brain lesions. At least a 40% increase of tCho compared to normal brain tissue indicates a malignant tumor (WHO grade III/IV gliomas, PCNSL, metastases) with >90% specificity and sensitivity.

Neuroradiological Viewpoint on the Diagnostics of Space-Occupying Brain Lesions

Conventional magnetic resonance (MR) imaging of space-occupying lesions may answer most of the questions concerning the diagnosis and subsequent treatment strategies if patient age, clinical and paraclinical findings are considered as well. However, crucial and relevant differential diagnoses require additional MR methods, such as diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and magnetic resonance spectroscopy (MRS). In necrotic ring-enhancing lesions DWI may detect inflammatory processes, whereas characteristics of the peritumoral area may help to distinguish between metastases and glioblastomas. In solid tumors DWI, PWI and MRS may also aid the differentiation between low-grade gliomas and malignant tumors, such as gliomas WHO (World Health Organization) gradeIII and IV and lymphomas. This review briefly explains special MR methods with respect to brain tumors and illustrates the diagnostic pathways necessary for supplying a reliable diagnosis as well as optimal pre-operative imaging of space-occupying brain lesions.

Asymptomatic Motor Cortex Displacement due to a Giant Arachnoid Cyst

Cerebral lesions are held to induce plastic changes of the brain. Less well established, however, is how much space-occupying brain lesions may only displace functional representations. In a 66-year-old man we show, by means of functional magnetic resonance imaging and transcranial magnetic stimulation, a profound displacement of the motor cortex due to a large asymptomatic arachnoid cyst. Thus, the chronically compressed brain is capable of sustaining normal brain function without utilizing the potential of cortical plasticity.