RESUMO
Purpose: To report a case of recurrent retinoblastoma following transpupillary thermotherapy (TTT) with development of scleral ectasia, as well as their successful treatment with intra-arterial chemotherapy. Observations: A 15-month-old girl with bilateral retinoblastoma presented with recurrent retinoblastoma and associated scleral ectasia with concern for extraocular extension after receiving multiple round of systemic chemotherapy and TTT. Given her negative systemic evaluation, decision was made to pursue intra-arterial chemotherapy. After completion of six rounds of 3-agent intra-arterial chemotherapy, the recurrent retinoblastoma had completely regressed and the scleral ectasia had improved and fibrosed. Conclusions and importance: The sclera is classically viewed as hyperthermy-resistant to TTT. Here, we describe scleral ectasia due to aggressive TTT with recurrence of the retinoblastoma. Our treatment with intra-arterial chemotherapy not only caused complete regression of the recurrent retinoblastoma, but it also contributed to the stabilization and improvement of the weakened scleral.
Assuntos
Encéfalo/diagnóstico por imagem , Hemorragia Cerebral/diagnóstico por imagem , Hemorragia Cerebral/terapia , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/terapia , Substância Branca/diagnóstico por imagem , Animais , Humanos , Oxigenoterapia Hiperbárica/tendênciasRESUMO
PURPOSE: The therapeutic regimen for cranial arteriovenous malformations often involves both stereotactic radiosurgery and endovascular embolization. Embolization agents may contain tantalum or other contrast agents to assist the neurointerventionalists, leading to concerns regarding the dosimetric effects of these agents. This study investigated dosimetric properties of n-butyl cyanoacrylate (n-BCA) plus lipiodol with and without tantalum powder. METHODS: The embolization agents were provided cured from the manufacturer with and without added tantalum. Attenuation measurements were made for the samples and compared to the attenuation of a solid water substitute using a 6 MV photon beam. Effective linear attenuation coefficients (ELAC) were derived from attenuation measurements made using a portal imager and derived sample thickness maps projected in an identical geometry. Probable dosimetric errors for calculations in which the embolized regions are overridden with the properties of water were calculated using the ELAC values. Interface effects were investigated using a parallel plate ion chamber placed at set distances below fixed samples. Finally, Hounsfield units (HU) were measured using a stereotactic radiosurgery CT protocol, and more appropriate HU values were derived from the ELAC results and the CT scanner's HU calibration curve. RESULTS: The ELAC was 0.0516 ± 0.0063 cm(-1) and 0.0580 ± 0.0091 cm(-1) for n-BCA without and with tantalum, respectively, compared to 0.0487 ± 0.0009 cm(-1) for the water substitute. Dose calculations with the embolized region set to be water equivalent in the treatment planning system would result in errors of -0.29% and -0.93% per cm thickness of n-BCA without and with tantalum, respectively. Interface effects compared to water were small in magnitude and limited in distance for both embolization materials. CT values at 120 kVp were 2082 and 2358 HU for n-BCA without and with tantalum, respectively; dosimetrically appropriate HU values were estimated to be 79 and 199 HU, respectively. CONCLUSIONS: The dosimetric properties of the embolization agents are very close to those of water for a 6 MV beam. Therefore, treating the entire intracranial space as uniform in composition will result in less than 1% dosimetric error for n-BCA emboli smaller than 3.4 cm without added tantalum and n-BCA emboli smaller than 1.1 cm with added tantalum. Furthermore, when effective embolization can be achieved by the neurointerventionalist using n-BCA without tantalum, the dosimetric impact of overriding material properties will be lessened. However, due to the high attenuation of embolization agents with and without added tantalum for diagnostic energies, artifacts may occur that necessitate additional imaging to accurately identify the spatial extent of the region to be treated.