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Robert Maciunas

Publications and source records attributed to Robert Maciunas.

2 recordsLinked to original sources

Neurosarcoidosis presenting with simple partial seizures and solitary enhancing mass: case reports and review of the literature.

A 37-year old woman, who had presented 5 years earlier with suspected simple partial seizures, returned with seizures increasing in frequency and intensity, confirmed by video/electroencephalography (VEEG) monitoring with left frontotemporal onset. A low-grade tumor was suspected, given a magnetic resonance imaging (MRI) study demonstrating enlargement of the left amygdala, anterior hippocampus, and adjacent mesial temporal neocortex, with modest gadolinium enhancement, and a positron emission tomography (PET) scan showing increased metabolism within that region. Surgical resection of the left mesial temporal lobe was performed and pathology revealed pathogen-free granulomas. She was given a diagnosis of sarcoidosis (following chest computed tomography that showed hilar adenopathy). She was treated with oral steroids for neurosarcoidosis with no further epileptic seizures in 19 months of follow-up. The second case was a young man, with known pulmonary sarcoidosis, who developed simple partial seizures and, later, complex partial seizures, with MRI revealing a left insular mass. Stereotactic biopsy again demonstrated pathogen-free granulomas. He has also done well in 4 years of follow-up. Review of the literature suggests that seizures associated with sarcoidosis do not invariably imply a poor prognosis. Certain features-multifocal parenchymal involvement, hydrocephalus, and chronic meningitis-were associated with poor outcome. In contrast, cases with isolated mass lesions often fared well.

Adult↗

Plug pattern optimization for gamma knife radiosurgery treatment planning.

PURPOSE: To develop a novel dose optimization algorithm for improving the sparing of critical structures during gamma knife radiosurgery by shaping the plug pattern of each individual shot. METHOD AND MATERIALS: We first use a geometric information (medial axis) aided guided evolutionary simulated annealing (GESA) optimization algorithm to determine the number of shots and isocenter location, size, and weight of each shot. Then we create a plug quality score system that checks the dose contribution to the volume of interest by each plug in the treatment plan. A positive score implies that the corresponding source could be open to improve tumor coverage, whereas a negative score means the source could be blocked for the purpose of sparing normal and critical structures. The plug pattern is then optimized via the GESA algorithm that is integrated with this score system. Weight and position of each shot are also tuned in this procedure. RESULTS: An acoustic tumor case is used to evaluate our algorithm. Compared to the treatment plan generated without plug patterns, adding an optimized plug pattern into the treatment planning process boosts tumor coverage index from 95.1% to 97.2%, reduces RTOG conformity index from 1.279 to 1.167, lowers Paddick's index from 1.34 to 1.20, and trims the critical structure receiving more than 30% maximum dose from 16 mm(3) to 6 mm(3). CONCLUSIONS: Automated GESA-based plug pattern optimization of gamma knife radiosurgery frees the treatment planning team from the manual forward planning procedure and provides an optimal treatment plan.

Algorithms↗