Whole-brain white matter network reorganization in HIV.

The human immunodeficiency virus (HIV) causes an infectious disease with a high viral tropism toward CD4 T-lymphocytes and macrophage. Since the advent of combined antiretroviral therapy (CART), the number of opportunistic infectious disease has diminished, turning HIV into a chronic condition. Nevertheless, HIV-infected patients suffer from several life-long symptoms, including the HIV-associated neurocognitive disorder (HAND), whose biological substrates remain unclear. HAND includes a range of cognitive impairments which have a huge impact on daily patient life. The aim of this study was to examine putative structural brain network changes in HIV-infected patient to test whether diffusion-imaging-related biomarkers could be used to discover and characterize subtle neurological alterations in HIV infection. To this end, we employed multi-shell, multi-tissue constrained spherical deconvolution in conjunction with probabilistic tractography and graph-theoretical analyses. We found several statistically significant effects in both local (right postcentral gyrus, right precuneus, right inferior parietal lobule, right transverse temporal gyrus, right inferior temporal gyrus, right putamen and right pallidum) and global graph-theoretical measures (global clustering coefficient, global efficiency and transitivity). Our study highlights a global and local reorganization of the structural connectome which support the possible application of graph theory to detect subtle alteration of brain regions in HIV patients.Clinical Relevance-Brain measures able to detect subtle alteration in HIV patients could also be used in e.g. evaluating therapeutic responses, hence empowering clinical trials.

Decompressive craniectomy may cause diagnostic challenges to assess brain death by computed tomography angiography.

According to Italian legislation to diagnose brain death (BD) after the initial documentation of the clinical signs, repetition of clinical testing and confirmation of the loss of bioelectrical activity of the brain (EEG) is required. However, when EEG is unreliable it is necessary to demonstrate cerebral circulatory arrest (CCA). Accepted imaging techniques to demonstrate CCA include: cerebral angiography, cerebral scintigraphy, transcranial Doppler (TCD) and computed tomography angiography (CTA). This latter technique, due to its large availability, low invasivity and easy and fast acquisition is widely used over the country. Nevertheless its diagnostic reliability is affected by some limitations in patients with decompressive craniectomy. Here we report two cases of brain injury with clinical signs of BD and at the same time, opacification of intracranial arteries on CTA and a pattern consistent with flow arrest on the corresponding insonable arteries on TCD. The discrepancy between CTA and TCD results points out a methodology limitation that could be overcome by updating Italian legislation according to other European Countries legislation.

A Case of Primary T-Cell Central Nervous System Lymphoma: MR Imaging and MR Spectroscopy Assessment.

Primary central nervous system lymphomas (PCNSLs) are mainly B-cells lymphomas. A risk factor for the development of PCNSL is immunodeficiency, which includes congenital disorders, iatrogenic immunosuppression, and HIV. The clinical course is rapidly fatal; these patients usually present signs of increased intracranial pressure, nausea, papilledema, vomiting, and neurological and neuropsychiatric symptoms. PCNSL may have a characteristic appearance on CT and MR imaging. DWI sequences and MR spectroscopy may help to differentiate CNS lymphomas from other brain lesions. In this paper, we report a case of a 23-year-old man with T-primary central nervous system lymphoma presenting with a mass in the right frontotemporal lobe. We describe clinical, CT, and MRI findings. Diagnosis was confirmed by stereotactic biopsy of the lesion.