SUMMARY:The current standard of care for newly diagnosed cases of high-grade glioma is surgical resection followed by RT with concurrent chemotherapy. The most widely used criteria for assessing treatment response are based on a 2D measurement of the enhancing area on MR imaging known as the Macdonald Criteria. Recently, nontumoral increases (pseudoprogression) and decreases (pseudoresponse) in enhancement have been found, and these can confuse outcome evaluation. Here we review pseudoprogression and pseudoresponse and describe how better understanding of these phenomena can aid interpretation.ABBREVIATIONS: ADC ϭ apparent diffusion coefficient; BBB ϭ blood-brain barrier; Cho ϭ choline; DSC ϭ dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging; DTI ϭ diffusion tensor imaging; DWI ϭ diffusion-weighted imaging; FDG ϭ fluorodeoxyglucose; FLAIR ϭ fluidattenuated inversion recovery; GBM ϭ glioblastoma multiforme; MGMT ϭ methyltransferase; NAA ϭ N-acetylaspartate; PET ϭ positron-emission tomography; PSR ϭ percentage of signalintensity recovery; RANO ϭ Response Assessment in Neuro-Oncology; rCBV ϭ relative cerebral blood volume; RECIST ϭ Response Evaluation Criteria in Solid Tumors; ROC ϭ receiver operating characteristic analysis; RT ϭ radiation therapy; TMZ ϭ temozolomide; VEGF ϭ vascular endothelial growth factor G BM is the most common primary malignant type of brain neoplasm in adults and is associated with a dismal prognosis. The current standard of care is surgical resection followed by RT and concomitant and adjuvant TMZ chemotherapy. This is a relatively recent standard, with pivotal data published in 2005, and it represents a milestone, because this approach has been shown to prolong the overall survival of these patients.1 With the standardization of treatment around surgery/RT/TMZ, certain patterns are beginning to emerge that were not previously noticed. In addition, in May 2009, the US Food and Drug Administration approved bevacizumab for recurrent glioblastoma. This anti-VEGF agent also can have a marked pattern of change on MR imaging. In addition to impacting individual patient care, these changes have also had an impact on clinical trials of new therapies. Macdonald CriteriaThe Macdonald Criteria 2 are currently the most widely used guideline for assessing response to therapy in patients with highgrade gliomas. These are based on 2D tumor measurements made in MR imaging scans, in conjunction with clinical assessment and corticosteroid dose. According to the Macdonald Criteria, tumor progression is considered to have occurred when an increase of Ͼ25% in the size of the contrast-enhancing lesion is observed. There are important limitations to these criteria, which only address the contrast-enhancing component of the tumor, and various updated guidelines for RANO have been published.3,4 As radiologists learn early in their training, contrast enhancement in posttreatment brain tumors is nonspecific and may not always be considered a true surrogate of tumor response.The limitations of th...

The diffusion tensor imaging findings in children with autistic disorder suggest impairment of white matter microstructure, possibly associated with reduced connectivity in corpus callosum, internal capsule, and superior and middle cerebellar peduncles.

BACKGROUND AND PURPOSE:The T2-weighted gradient-echo (GRE) imaging is currently the gold standard MR imaging sequence for the evaluation of patients with cerebral cavernous malformation (CCM) lesions. We aimed to compare the sensitivity of susceptibility-weighted imaging (SWI) with T2-weighted fast spin-echo (FSE) and GRE imaging in assigning the number of CCM lesions in patients with the familial form of the disease.

Key Points Question Are neuroimaging findings of infants exposed to Zika virus associated with infant clinical outcomes and gestational age of antenatal Zika virus infection? Findings In this cohort study of 110 infants with confirmed or suspected antenatal exposure to Zika virus evaluated at a referral center from 2015 to 2016, 96% of abnormal neuroimaging occurred among Zika virus–exposed infants with severe clinical findings at birth; however, 10% of infants without severe clinical manifestations also had neuroimaging abnormalities. In addition, an increased risk of abnormal imaging was associated with Zika virus exposure in the first trimester compared with later trimesters. Meaning Neuroimaging of infants exposed to Zika virus is an important part of evaluating infants with a history of Zika virus in utero exposure, particularly for those exposed in the first trimester.

Purpose: To compare the hippocampal volumes in patients with bipolar disorder (BD) and healthy controls, obtained by applying different segmentation methods (manual, Freesurfer [FS], and FSL). Materials and Methods:The study included 27 patients with BD and 40 healthy controls. T1-weighted images in the sagittal plane were acquired on a 3 Tesla (T) MR scanner. Hippocampal volumetry was performed using one manual and two automated methods (FS and FSL). One-way repeated analysis of variance was applied to test the differences in hippocampal volumes using the three segmentation methods. To evaluate the agreement among the three tested volumetric segmentation methods the intraclass correlation coefficients (ICCs) were calculated.Results: Hippocampal volumes obtained from all methods were significantly different (P < 0.05) in BD patients after intracranial volume correction, indicating a reduction in volume, unless from the manual method of the left hippocampal volume. The ICCs of the hippocampal volume between the manual method and FS were 0.846 (right) and 0.859 (left), and between the manual method and FSL were 0.746 (right) and 0.654 (left).Conclusion: Both manual and automatic segmentation methods detected reductions in the hippocampal volumes in BD patients. Automated segmentation methods are a robust and reproducible option for assessing hippocampal volume.

Diffusion tensor imaging is a promising technique for the evaluation of patients with probable mild cognitive impairment. Early detection of the disease expands the treatment options, increasing the likelihood of a good clinical response and enhancing the quality of life of patients and their relatives. Further studies with larger populations are needed to confirm the role of diffusion tensor imaging in the evaluation of memory impairment.

Neurologic complications are being recognized as important outcomes of coronavirus disease 2019 (COVID-19). Pathogenesis is varied and incompletely understood, and may include neuroinvasion, indirect post-infectious neuroinflammation, and cerebrovascular pathologies. We present a case of COVID-19-related encephalomyeloradiculitis with clinical and magnetic resonance imaging characteristics of neuromyelitis optica spectrum disorders that was associated with anti-aquaporin-4 antibodies. Our case suggests post-infectious autoimmunity as a mechanism in at least a subset of patients with COVID-19-related neurologic disease.

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