Intraoperative ultrasonography-guided positioning of iodine 125 plaque brachytherapy in the treatment of choroidal melanoma.

PURPOSE: To report intraoperative ultrasonography-guided positioning of iodine 125 (I(125)) plaques for brachytherapy of choroidal melanoma as a quality improvement measure. DESIGN: Retrospective, single-center, consecutive case-cohort study. PARTICIPANTS: One hundred fifty consecutive patients with choroidal melanoma. METHODS: Patients with choroidal melanoma who were treated with I(125) plaque brachytherapy from January 2007 through January 2011 with at least 6 months of clinical follow-up were included. MAIN OUTCOME MEASURES: Patient and tumor characteristics at diagnosis were tabulated. The need for plaque repositioning if intraoperative ultrasonography showed the plaque to be either not centered on the tumor or if there was less than 1.0 mm of plaque margin beyond the tumor border was recorded. The rate of local treatment failure and occurrence of distant metastasis were determined. RESULTS: The average interval from surgery to last follow-up was 21.5 months. Fifty-four (36%) of 150 patients required plaque repositioning. Of tumors located in the macula, equator, and periphery, 15 (36.6%), 26 (36.6%), and 13 (34.2%) required repositioning. There was no case of local treatment failure during a mean follow-up of 21.5 months (range, 6-48 months). Clinical evidence of choroidal melanoma metastasis developed in 9 patients. The cumulative 2-year Kaplan-Meier rate of local treatment failure in the cohort was statistically lower compared with the Collaborative Ocular Melanoma Study, which did not require ultrasonography-guided plaque positioning. CONCLUSIONS: Intraoperative ultrasonography identified the need to reposition I(125) plaques to achieve centration and plaque margin (>1.0 mm) beyond the tumor border in 36% of eyes. Neither tumor size nor tumor location correlated with the need to reposition the plaque. There was no case of local treatment failure during follow-up in this series. Correct plaque position is an essential component of quality outcomes in brachytherapy. Intraoperative ultrasonography reduces geographic errors in placement in eye plaque therapy and may help to reduce local treatment failure in choroidal melanoma.

Ocular response of choroidal melanoma with monosomy 3 versus disomy 3 after iodine-125 brachytherapy.

PURPOSE: To report the ocular response of choroidal melanoma with monosomy 3 vs. disomy 3 after (125)I brachytherapy. METHODS AND MATERIALS: We evaluated patients with ciliochoroidal melanoma managed with fine needle aspiration biopsy immediately before plaque application for (125)I brachytherapy between January 1, 2005 and December 31, 2008. Patients with (1) cytopathologic diagnosis of melanoma, (2) melanoma chromosome 3 status identified by fluorescence in situ hybridization, and (3) 6 or more months of follow-up after brachytherapy were sorted by monosomy 3 vs. disomy 3 and compared by Kruskal-Wallis test. RESULTS: Among 40 ciliochoroidal melanomas (40 patients), 15 had monosomy 3 and 25 had disomy 3. Monosomy 3 melanomas had a median greatest basal diameter of 12.00 mm and a median tumor thickness of 6.69 mm before brachytherapy; at a median of 1.75 years after brachytherapy, median thickness was 3.10 mm. Median percentage decrease in tumor thickness was 48.3%. Disomy 3 melanomas had a median greatest basal diameter of 10.00 mm and median tumor thickness of 3.19 mm before brachytherapy; at a median of 2.00 years after brachytherapy, median tumor thickness was 2.37 mm. The median percentage decrease in tumor thickness was 22.7%. Monosomy 3 melanomas were statistically greater in size than disomy 3 melanomas (p < 0.001) and showed a greater decrease in tumor thickness after brachytherapy (p = 0.006). CONCLUSION: In this study, ciliochoroidal melanomas with monosomy 3 were significantly greater in size than disomy 3 melanoma and showed a significantly greater decrease in thickness at a median of 1.75 years after brachytherapy. The greater decrease in monosomy 3 melanoma thickness after brachytherapy is consistent with other malignancies in which more aggressive pathology has been shown to be associated with a greater initial response to radiotherapy.

Attenuation of iodine 125 radiation with vitreous substitutes in the treatment of uveal melanoma.

OBJECTIVE: To demonstrate attenuation of radiation from iodine 125 ((125)I) to intraocular structures using liquid vitreous substitutes. METHODS: Four candidate vitreous substitutes were tested for attenuation using empirical measurement and theoretical calculation. In vitro and ex vivo cadaveric dosimetry measurements were obtained with lithium fluoride thermoluminescent dosimeters to demonstrate the attenuation effect of vitreous substitution during (125)I simulated plaque brachytherapy. Theoretical dosimetry calculations were based on Monte Carlo simulation. RESULTS: In a cylindrical phantom at a 17-mm depth, liquid vitreous substitutes as compared with saline showed significant reduction of radiation penetration (48% for 1000-centistoke [cSt] silicone oil [polydimethyl-n-siloxane], 47% for 5000-cSt silicone oil [polydimethyl-n-siloxane], 40% for heavy oil [perfluorohexyloctane/polydimethyl-n-siloxane], and 35% for perfluorocarbon liquid [perfluoro-n-octane]). Human cadaveric ex vivo measurements demonstrated a 1000-cSt silicone oil to saline dose ratio of 35%, 52%, 55%, and 48% at arc lengths of 7.6, 10.6, 22.3, and 28.6 mm from the plaque edge, respectively, along the surface of the globe. Monte Carlo simulation of a human globe projected attenuation as high as 57% using 1000-cSt silicone oil. CONCLUSIONS: Intraocular vitreous substitutes including silicone oil, heavy oil, and perfluorocarbon liquid attenuate the radiation dose from (125)I. Cadaveric ex vivo measurements and Monte Carlo simulation both demonstrate radiation attenuation using 1000-cSt silicone oil at distances corresponding to vital ocular structures. Clinical Relevance Attenuation of radiation with silicone oil endotamponade in the treatment of uveal melanoma may significantly reduce radiation-induced injury to vital ocular structures.

Assessment of central vision and macular structure in patients undergoing iodine-125 brachytherapy for ciliochoroidal melanoma.

OBJECTIVES: To prospectively report standardized visual function and macular structural assessment in patients undergoing iodine-125 brachytherapy for choroidal and ciliary body melanoma. MATERIALS AND METHODS: Patients were enrolled for pretreatment and annual posttreatment assessment. Evaluations included ophthalmic history; standardized refraction; visual acuity, contrast sensitivity, and color vision measurement; comprehensive ophthalmic examination; fundus photography; fluorescein angiography; optical coherence tomography; and ultrasonography. Radiation doses to the foveola and optic disc margin were calculated. RESULTS: Forty-two patients were enrolled. Melanoma location included 3 in the ciliary body, 7 anterior, 11 equatorial, 13 posterior, and 8 macular tumors. Mean apical tumor height was 4.45 mm (range 1.79-9.83 mm) and mean longitudinal tumor diameter was 9.41 mm (range 4.52-4.73 mm). Pretreatment mean best-corrected Ferris-Bailey early treatment diabetic retinopathy study visual acuity was 50 (standard deviation +/- 15) letters (Snellen equivalent 20/32, range 20/15 to hand motions). The mean Pelli-Robson contrast threshold percentage was 4.1% (+/- 2.5%). The mean Hardy-Rand-Rittler color vision score was 13/14 (+/- 2.7). Mean distances from the posterior edge of the tumor to the foveola and the optic disc margin were 6.99 mm (+/- 6.22 mm) and 7.28 mm (+/- 5.98 mm), respectively. At the foveola, median total radiation dose was 36.2 Gy (+/-50.6 Gy) and median dose rate was 31.6 cGy/h (+/- 39.8 cGy/h). At the optic nerve, median total radiation dose was 42.8 Gy (+/- 30.8 Gy) and median dose rate was 36.2 cGy/h (+/- 21.4 cGy/h). CONCLUSION: This prospective assessment of macular structure and function will provide more complete understanding of the ocular effects of radiation therapy for ocular melanoma.

Quick determination of malodor-causing fatty acids in manure by capillary electrophoresis.

The analysis of odor components in livestock waste has been extensively studied. Past research has identified volatile fatty acids, especially from C3 to C6, as indicators of malodor. Originally, the odorous components were analyzed by gas chromatography after a tedious absorption and troublesome extraction procedure or by a subjectively olfactory system or sense of smell. Thus, there is a need for the development of highly specific, quantitative analytical methods. In this research, a comprehensive liquid manure analysis approach-capillary electrophoresis (CE) with a systematic optimization procedure-was adopted to measure the concentration of propanoic acid (C2H5COOH, C3), butyric acid (C3H7COOH, C4), valeric acid (C4H9COOH, C5) and caproic acid (C5H11COOH, C6) in swine manure. Liquid samples after filtration were injected into CE directly. The following condition is finally proposed: fused-silica capillary, effective length 40 cm, 50 microm I.D.; buffer, 20 mM Tris and 10 mM p-anisate, pH 8.0; voltage 30 kV; temperature 25 degrees C. The results showed that CE provided a quantitative analysis of volatile fatty acids in liquid manure at the ppm level with minimum sample needed (nanoliter). Moreover, the use of CE is a timesaving technique; one measurement for the separation of those VFAs could be completed within 10 min.