Browsing by Author "Mereniuk, Todd R."

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    Discovery of increased number or interval growth of brain metastases on same-day GammaKnife™ planning MRI: Predicting factors and patient outcomes
    (Old City Publishing, 2022) Mereniuk, Todd R.; Burney, Heather N.; Lautenschlaeger, Tim; Watson, Gordon A.; Rhome, Ryan M.; Radiation Oncology, School of Medicine
    Purpose: To determine factors associated with increased risk of finding new and/or enlarged brain metastases (BM) on GammaKnife™ (GK) MRI and their impact on patient outcomes. Results: 43.9% of patients showed BM growth, 32.9% had additional brain metastases (aBM), and 18.1 % had both. Initial brain metastasis velocity (iBMV) was associated with finding aBM. Time between diagnostic MRI (dMRI) and GK MRI was associated with interval growth and each day increased this risk by 2%. Prior brain metastasectomy and greater time between either dMRI or latest extracranial RT and GK MRI predicted both aBM and BM growth. aBM and/or BM growth led to management change in 1.8% of cases and were not associated with OS or incidence of distant intracranial failure. Conclusions: Number of metastases seen on dMRI and iBMV predicted both aBM and/or BM growth, however, these factors did not significantly affect survival or incidence of distant intracranial failure.
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    Radiation Induced Cerebral Microbleeds in Pediatric Patients with Brain Tumors Treated with Proton Radiotherapy
    (Elsevier, 2018) Kralik, Stephen F.; Mereniuk, Todd R.; Grignon, Laurent; Shih, Chie-Schin; Ho, Chang Y.; Finke, Whitney; Coleman, Peter W.; Watson, Gordon A.; Buchsbaum, Jeffrey; Radiology and Imaging Sciences, School of Medicine
    Purpose Proton beam radiotherapy (PBT) has been increasingly utilized to treat pediatric brain tumors, however, limited information exists regarding radiation induced cerebral microbleeds (CMBs) among these patients. The purpose was to evaluate the incidence, risk factors, and imaging appearance of CMBs in pediatric patients with brain tumors treated with PBT. Methods A retrospective study was performed on 100 pediatric patients with primary brain tumors treated with PBT. CMBs were diagnosed by examining serial MRIs including susceptibility-weighted imaging. Radiation therapy plans were analyzed to determine doses to individual CMBs. Clinical records were used to determine risk factors associated with the development of CMBs in these patients. Results The mean age at time of PBT was 8.1 years. The median follow-up duration was 57 months. The median time to development of CMBs was 8 months (mean 11 months; range 3-28 months). The percentage of patients with CMBs was 43%, 66%, 80%, 81%, 83%, and 81% at 1-year, 2-years, 3-years, 4-year, 5-years, and greater than 5 years from completion of proton radiotherapy. The majority (87%) of CMBs were found in areas of brain exposed to ≥ 30 Gy. Risk factors included maximum radiotherapy dose (P=0.001), percentage and volume of brain exposed to ≥ 30 Gy (P=0.0004; P=0.0005), and patient age at time of PBT (P=0.0004). Chemotherapy was not a significant risk factor (P=0.35). No CMBs required surgical intervention. Conclusion CMBs develop in a high percentage of pediatric patients with brain tumors treated with proton radiotherapy within the first few years following treatment. Significant risk factors for development of CMBs include younger age at time of PBT, higher maximum radiotherapy dose, and higher percentage and volume of brain exposed to ≥ 30 Gy. These findings demonstrate similarities with CMBs that develop in pediatric brain tumor patients treated with photon radiotherapy.
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    Reduced radiation necrosis in radiosurgical treatment of small brain metastases with 22 Gy
    (Old City Publishing, 2021) McClelland, Shearwood, III.; Mereniuk, Todd R.; Elbanna, May F.; Huang, Christina C.; Lautenschlaeger, Tim; Miller, James C.; Watson, Gordon A.; Rhome, Ryan M.; Radiation Oncology, School of Medicine