Conventional and Advanced Magnetic Resonance Imaging Assessment of Non-Enhancing Peritumoral Area in Brain Tumor.

The non-enhancing peritumoral area (NEPA) is defined as the hyperintense region in T2-weighted and fluid-attenuated inversion recovery (FLAIR) images surrounding a brain tumor. The NEPA corresponds to different pathological processes, including vasogenic edema and infiltrative edema. The analysis of the NEPA with conventional and advanced magnetic resonance imaging (MRI) was proposed in the differential diagnosis of solid brain tumors, showing higher accuracy than MRI evaluation of the enhancing part of the tumor. In particular, MRI assessment of the NEPA was demonstrated to be a promising tool for distinguishing high-grade gliomas from primary lymphoma and brain metastases. Additionally, the MRI characteristics of the NEPA were found to correlate with prognosis and treatment response. The purpose of this narrative review was to describe MRI features of the NEPA obtained with conventional and advanced MRI techniques to better understand their potential in identifying the different characteristics of high-grade gliomas, primary lymphoma and brain metastases and in predicting clinical outcome and response to surgery and chemo-irradiation. Diffusion and perfusion techniques, such as diffusion tensor imaging (DTI), diffusional kurtosis imaging (DKI), dynamic susceptibility contrast-enhanced (DSC) perfusion imaging, dynamic contrast-enhanced (DCE) perfusion imaging, arterial spin labeling (ASL), spectroscopy and amide proton transfer (APT), were the advanced MRI procedures we reviewed.

Assessment of brain tumors by magnetic resonance dynamic susceptibility contrast perfusion-weighted imaging and computed tomography perfusion: a comparison study.

PURPOSE: To investigate the association and agreement between magnetic resonance dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI) and computed tomography perfusion (CTP) in determining vascularity and permeability of primary and secondary brain tumors. MATERIAL AND METHODS: DSC-PWI and CTP studies from 97 patients with high-grade glioma, low-grade glioma and solitary brain metastasis were retrospectively reviewed. Normalized cerebral blood flow (nCBF), cerebral blood volume (nCBV), capillary transfer constant (nK2) and permeability surface area product (nPS) values were obtained. Variables among groups were compared, and correlation and agreement between DSC-PWI and CTP were tested. RESULTS: All DSC-PWI and CTP parameters were higher in high-grade than in low-grade gliomas (p < 0.01 and p < 0.001). Metastases had greater DSC-PWI nCBV (p < 0.05), nCTP-CBF (p < 0.05), nCTP-CBV (p < 0.01) and nCTP-PS (p < 0.0001) than low-grade gliomas and more elevated nCTP-PS (p < 0.01) than high-grade gliomas. The correlation was strong between DSC-PWI nCBF and CTP nCBF (r = 0.79; p < 0.00001) and between DSC-PWI nCBV and CTP nCBV (r = 0.83; p < 0.00001), weaker between DSC-PWI nK2 and CTP nPS (r = 0.29; p < 0.01). Bland-Altman plots indicated that the agreement was strong between DSC-PWI nCBF and CTP nCBF, good between DSC-PWI nCBV and CTP nCBV and poorer between DSC-PWI nK2 and CTP nPS. CONCLUSION: DSC-PWI and CTP CBF and CBV maps were comparable and interchangeable in the assessment of tumor vascularity, unlike DSC-PWI K2 and CTP PS maps that were more discordant in the analysis of tumor permeability. CTP could be an alternative method to quantify tumor neoangiogenesis when MRI is not available or when the patient does not tolerate it.

The Effectiveness of Bevacizumab in Radionecrosis After Radiosurgery of a Single Brain Metastasis.

Radionecrosis (RN) of brain tissue is a serious late complication of brain irradiation and historically has been treated with corticos-teroid therapy and alternatively surgical decompression. Recently, bevacizumab has been suggested for treatment of cerebral radiation necrosis. We present a case of a 73-years-old women affected by a primary non-small cell lung cancer with a single brain metastasis treated with radiosurgery. Two years after radiosurgery the patient referred neurological symptoms and a brain magnetic resonance confirmed the presence of RN. The patient refused surgical decompression so underwent at the treatment with bevacizumab 7.5 mg/kg/2 weeks for a total of 4 cycles. After two months of treatment the patient reported strumental and clinical improvement. Ten months after bevacizumab discontinuation the patient experienced a recurrence of RN with evident clinical manifestation and confirmed by radiological imaging. A new treatment with bevacizumab was not performed due to the systemic progression disease and the worsening of clinical status. Despite limited to only one clinical case, our study suggests the efficacy of bevacizumab to treat RN. Future studies are needed to confirm its mechanism and to properly define the optimal scheduling, dosage and duration of therapy.

Cerebellar mass as a location of acute lymphoblastic leukaemia.

A 22-year-old man with acute lymphoblastic leukaemia was referred to our observation for headache, cervical pain and sopor. A computed tomography study revealed triventricular obstructive hydrocephalus due to a left cerebellar hyperdense mass impinging on the fourth ventricle. A magnetic resonance study demonstrated an area of hyperintensity on T2-weighted images, hypointensity on T1, restricted diffusivity and contrast enhancement involving the left hemispherical cerebellar cortex and the vermis and causing cerebellar herniation. After surgical excision of the lesion, histological examination revealed an infiltrate of lymphoblastic leukaemia with B cells. Leukaemic intracranial masses are rare. Our report describes a case presenting a cerebellar mass of leukaemic tissue characterized by high cellularity and low apparent diffusion coefficient value comparable to acute ischaemia. Therefore leukaemic intracranial mass has to be considered in the differential diagnosis of cerebellar masses.

3-T magnetic resonance angiography in primary angiitis of the central nervous system.

OBJECTIVE: Primary angiitis of the central nervous system (PACNS) is a rare disease characterized by an inflammatory process of intracranial vessels. Magnetic resonance angiography (MRA) (3 T) offers increased signal-to-noise ratio and background suppression, leading to better depiction of the intracranial vessels. The aim of our work was to compare the sensitivity of 3-T MRA to that of 1.5-T MRA in the diagnosis of PACNS. METHODS: Eight patients with PACNS and signs of angiitis at digital subtraction angiography (DSA) underwent MRA at 1.5 and 3 T. Magnetic resonance angiograms obtained with time-of-flight (TOF) technique were evaluated for the presence of stenosis with respect to DSA. RESULTS: In PACNS patients, DSA identified 827 intracranial stenoses. Sensitivity for vessel stenosis of 3-T TOF MRA was 47% and 14% for 1.5-T TOF. CONCLUSIONS: Time-of-flight MRA at 3 T improved the sensitivity of MRA in the noninvasive preliminary evaluation of patients with PACNS.