Over the course of five years, a total of ten cases were collected of glioma patients in whom a distant lesion at the fourth ventricle was noted. A ‘distant lesion’ was defined as a lesion with a normal appearing tissue bridge at imaging between the primary and secondary locations. Previous imaging of these patients was reviewed along with clinical history, course of therapy, and available histology. A review of the literature was performed with respect to present knowledge on patterns of glioma proliferation and dissemination. This case series is the first to describe the fourth ventricle as a location that may be prone to secondary lesions in glioma patients. Further investigation on this subject may yield deeper insights into the mechanisms by which glial tumors spread within the brain, with the hope of developing or improving therapeutic targets.

Tumefactive demyelination refers to large focal demyelinating lesions in the brain, which can be mistaken for malignancy. In some patients, these lesions are monophasic with a self-limited course; however, other patients demonstrate recurrent disease with new tumefactive or non-tumefactive lesions, and a subsequent diagnosis of relapsing-remitting multiple sclerosis is not uncommon. Owing to the limited data available in the literature, many questions about the patterns and prognostic significance of recurrent tumefactive lesions remain unanswered. The current case report involves a patient who recovered from tumefactive demyelination and presented two years later with a new recurrent tumefactive lesion in the contralateral brain.

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The present study utilized a porcine model for qualitative and quantitative assessment of the diagnostic quality of non-contrast abdominal computed tomography (CT) images generated by Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare, Waukesha, Wisconsin, USA), Model-Based Iterative Reconstruction (GE company name VEO), and conventional Filtered back projection (FBP) technique. Methods: Multiple CT whole-body scans of a freshly euthanized pig carcass were performed on a 64-slice GE CT scanner at varying noise indices (5, 10, 15, 20, 30, 37, 40, 45), and with three different algorithms (VEO, FBP, and ASIR at 30%, 50%, and 70% levels of ASIR-FBP blending). Abdominal CT images were reviewed and scored in a blinded and randomized manner by two board-certified abdominal radiologists. The task was to evaluate the clarity of the images according to a rubric involving edge sharpness, presence of artifact, anatomical clarity (assessed at four regions), and perceived diagnostic acceptability. This amounted to seven criteria, each of which was graded on a scale of 1 to 5. A weighted formula was used to calculate a composite score for each scan. Results: VEO outperforms ASIR and FBP by an average of 0.5 points per the scoring system used (p < 0.05). Above a threshold noise index of 30, diagnostic acceptability is lost by all algorithms, and there is no diagnostic advantage to increasing the dose beyond a noise index of 10. Between a noise index of 25-30, VEO retains diagnostic acceptability, as opposed to ASIR and FBP which lose acceptability above noise index of 25. Conclusion: Model-based iterative reconstruction provides superior image quality and anatomical clarity at reduced radiation dosages, supporting the routine use of this technology, particularly in pediatric abdominal CT scans.