Imre Fedorcsák

Abscess formation in Rathke's cleft cyst

SummaryTwo patients are discussed who presented at our Institute with endocrine dysfunction and sellar enlargement. CT scans revealed intra and suprasellar expanding lesions with ring enhancement. The postoperative histological examination showed remnants of Rathkes cleft cyst together with signs of inflammation. CT and MRI pictures, and possible mechanisms of abscess formation in this region are discussed.

Multiple intracranial melanoma metastases treated with surgery and radiosurgery with long term control. A case report.

SummaryA case of malignant melanoma with multiplex brain metastases is described, where both surgical and radiosurgical treatment was applied. Due to CNS manifestations the patient was operated on in two sessions. First the symptomatic large tumor was removed, and the other, small lesion which could not be reached from the same approach was operated later. The primary skin lesion was discovered and removed between the two operations. A CT scan three months after the second operation revealed recurrence at the site of the first operation, and the appearance of two new tumors. The intracranial neoplasms were treated in one session by stereotactic radiosurgery using a linear accelerator. Six months after this treatment a new skin lesion was removed and the patient received DTIC therapy. Successive CT scans after the irradiation showed a steady regression of the radiosurgically treated tumors, and more than one year after the irradiation no tumor could be detected on the CT scans.

The pre-requisite of a second-generation glioma PET biomarker

UNLABELLED Since the introduction of FDG into the field of molecular imaging with positron emission tomography (PET) more than three decades ago, FDG has been the tracer of choice for oncology PET imaging. Despite the relative disadvantages of FDG and the relative benefits of its challengers, FDG remains the most commonly used glioma tracer nowadays. The present article surveys the expectations of the field and gives a concise summary of recent developments; including the issues pertaining to the continued search for an optimal second-generation PET biomarker for glioma. MINI-ABSTRACT The present article gives a concise summary of recent developments; including the issues pertaining to the continued search for an optimal PET biomarker for glioma.

Intensity modulated operating mode of the rotating gamma system

PURPOSE The purpose of this work was to explore two novel operation modalities of the rotating gamma systems (RGS) that could expand its clinical application to lesions in close proximity to critical organs at risk (OAR). METHODS The approach taken in this study consists of two components. First, a Geant4-based Monte Carlo (MC) simulation toolkit is used to model the dosimetric properties of the RGS Vertex 360™ for the normal, intensity modulated radiosurgery (IMRS), and speed modulated radiosurgery (SMRS) operation modalities. Second, the RGS Vertex 360™ at the Rotating Gamma Institute in Debrecen, Hungary is used to collect experimental data for the normal and IMRS operation modes. An ion chamber is used to record measurements of the absolute dose. The dose profiles are measured using Gafchromic EBT3 films positioned within a spherical water equivalent phantom. RESULTS A strong dosimetric agreement between the measured and simulated dose profiles and penumbra was found for both the normal and IMRS operation modes for all collimator sizes (4, 8, 14, and 18 mm diameter). The simulated falloff and maximum dose regions agree better with the experimental results for the 4 and 8 mm diameter collimators. Although the falloff regions align well in the 14 and 18 mm collimators, the maximum dose regions have a larger difference. For the IMRS operation mode, the simulated and experimental dose distributions are ellipsoidal, where the short axis aligns with the blocked angles. Similarly, the simulated dose distributions for the SMRS operation mode also adopt an ellipsoidal shape, where the short axis aligns with the angles where the orbital speed is highest. For both modalities, the dose distribution is highly constrained with a sharper penumbra along the short axes. CONCLUSIONS Dose modulation of the RGS can be achieved with the IMRS and SMRS modes. By providing a highly constrained dose distribution with a sharp penumbra, both modes could be clinically applicable for the treatment of lesions in close proximity to critical OARs.

The Quest for Predictors of Seizure Improvement Following Arteriovenous Malformation Radiosurgery.

eizures are often associated with arteriovenous malformations (AVMs) and can have a significant negative S impact on patients’ quality of life. Prospective populationbased studies estimated that 25%e29% of all patients with a new diagnosis of AVM presented with seizures, which is the second most common presentation after hemorrhage. Moreover, seizure is the most common presenting symptom in patients harboring large AVMs, and nearly half of patients with unruptured AVMs present with seizures. The risk of developing seizures after incidental detection of an AVM is 2% per person-year, and the 5-year risk of developing epilepsy following a first seizure is 58%.