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J Heikkonen

Publications and source records attributed to J Heikkonen.

20 records · Page 2Linked to original sources

Theoretical analysis of regional blood flow studies.

Regional blood flow measurements were analyzed using a two-compartment model. The distribution of injected tracer between blood and tissue was assumed to be in equilibrium only at the beginning of the experiment. Equations for the determination of the partition coefficient of injected radionuclides from in vivo measurements were derived. These equations can also be used for estimation of the relative blood content of a tumor or an organ. The results were applied to experiments, where three diffusible radionuclides were injected simultaneously into patients with diagnosed tumors.

Argon↗

Visual outcome of eyes with malignant melanoma of the uvea after ruthenium plaque radiotherapy.

BACKGROUND AND OBJECTIVE: To analyze the overall visual outcome in 100 consecutive eyes with malignant uveal melanoma irradiated with ruthenium-106 plaques between 1981 and 1991. PATIENTS AND METHODS: The follow-up ranged from 4 months to 10.1 years (median 3.0 years). Scattergrams of equal follow-up periods, life-table survival analysis, and Cox's proportional hazards analysis were used to analyze visual outcome. RESULTS: VA increased for some time in 14 eyes. By 3 years, VA of at least 20/70, 20/200, counting fingers, and light perception were retained in 27%, 41%, 67% and 82% of eyes, respectively. Macular pathology cause loss of reading vision; neovascular glaucoma or enucleation caused loss of light perception. In univariate analysis, large tumor size (height > 5 mm or TNM class T3) predicted visual loss of all VA levels. For the loss of light perception, the tumor's largest basal diameter > 15 mm reached significance. In Cox's multivariate analysis tumor height > 5 mm was the only significant independent risk indicator for loss of VA levels 20/70 and 20/200. For the level CF, largest basal tumor diameter also reached significance, but location of the tumor within 1 disc diameter of the optic disc, either alone or in addition to the fovea, had the greatest risk ratio (6.3, 95% CI 4.1-9.8). For losing light perception, large TNM size (T3) was the strongest risk indicator (risk ratio 10.0; 95% CI 4.5-22.5), followed by proximity of the tumor to the optic disc (risk ratio 4.3, 95% CI 2.4-7.8). CONCLUSION: Ruthenium brachytherapy may retain vision in an eye with a malignant melanoma of the uvea for a considerable period of time. The data presented are useful in patient counseling and allow comparison to subsequent series.

Adult↗