[Newly occurring loss of visual acuity in choroidal osteoma]. / Neu aufgetretene Visusminderung bei choroidalem Osteom.

PURPOSE: Approach to loss of visual acuity in a patient with a choroidal osteoma (CO) which had been stable for seven years. METHODS: Fluorescence angiography confirmed a choroidal neovascularization (CNV) as the cause of the loss of visual acuity. Treatment with intravitreal (IVT) injection of ranibizumab. RESULTS: Increase of visual acuity and decrease of edema after IVT injection. CONCLUSION: Monitoring is necessary even for primarily benign CO in order to detect secondary complications causing loss of visual acuity, e. g. secondary CNV. Anti-VEGF IVT represents an approved treatment option.

[Recurrent uveitis of unknown origin in childhood]. / Kindliche rezidivierende Uveitis unklarer Genese.

This report describes a 12-year-old girl with diffuse infiltrating retinoblastoma. This inflammatory condition belongs to the uveitis masquerade syndromes, which comprise a group of various ocular diseases such as chronic intraocular inflammation and ocular tumors.

High resolution magnetic resonance imaging of retinoblastoma.

BACKGROUND/AIMS: Diagnosis of retinoblastoma is mainly based on indirect ophthalmoscopy, but additional imaging techniques are indispensable for the staging of the disease. A new high resolution magnetic resonance imaging (MRI) technique for the examination of the eye was evaluated. A new surface coil with a diameter of 5 cm allows a field of view of 60 mm with an in-plane resolution of 0.8 mm. We compared preoperative MRI scans with the histology after enucleation in 21 cases of retinoblastoma. Parameters studied were appearance of retinoblastoma, choroidal and scleral infiltration, extraocular extension, optic nerve infiltration, and vitreous seeding. RESULTS: All retinoblastomas could be visualised as hypointense to vitreous on T2 weighted images and slightly hyperintense to vitreous on plain T1 weighted images with a moderate enhancement after contrast application. Histology revealed seven cases with infiltration of the optic disc or optic nerve. Preoperative MRI scans depict juxtapapillary tumour masses, but it was impossible to differentiate between a juxtapapillary retinoblastoma, a prelaminar infiltration of the optic disc, or a just postlaminar optic nerve infiltration. In five of 14 cases with a proved tumour infiltration of the choroid, MRI scans showed an inhomogeneous contrast enhancement of the choroid in enhanced T1 weighted sequences beneath the retinoblastoma. Whether this sign is specific for a choroidal infiltration or is just an artefact remains unclear. High resolution MRI scans did not allow the exclusion of this form of intraocular tumour extension. All nine cases with proved vitreous seeding were not detected by MRI scans. None of these cases showed scleral infiltration or orbital tumour extension. Therefore, it is not possible to judge the rank of this technique in detecting orbital tumour growth. CONCLUSION: The new MRI technique is of limited value in visualisation of prelaminar or postlaminar infiltration of the optic nerve. Advanced choroidal infiltration might be visualised by contrast enhanced T1 weighted MRI scans, but the available spatial resolution did not allow the exclusion this critical form of tumour growth by MRI scans. Nevertheless, high resolution MRI with the new surface coil has superior contrast and spatial resolution compared to computed tomograph (CT) or other available imaging techniques. MRI cannot replace CT in detecting tumour calcification but with increasing experience with this new technique it should be possible to renounce CT scans in the majority of cases of retinoblastoma.

Intraocular metastases: differential diagnosis from uveal melanomas with high-resolution MRI using a surface coil.

Magnetic resonance imaging with dedicated surface coils plays a pivotal role in differential diagnosis and staging of intraocular tumors. The purpose of this study was to establish MRI criteria for the differential diagnosis of uveal melanomas and intraocular metastases. In a prospective study 44 eyes in 36 patients with intraocular metastases and 200 patients with uveal melanomas were investigated with MRI using a 1.5-T scanner and a 5-cm surface coil. Both quantitative and qualitative evaluation of the resulting images was performed. The MR signal intensities typically expected for metastases (slightly hyperintense on non-contrast T1-weighted images and hypointense on T2-weighted images compared to the vitreous body) were seen in only 23.1%. The typical melanoma signal of either moderate or strong hyperintensity on T1-weighted images and hypointensity on T2-weighted images was seen in 69.4% of the proven melanomas. Contrast enhancement was observed in both metastases and melanomas. Morphological differences between metastases and melanomas were detected in tumor size, shape, position, frequency of retinal detachment, and homogeneity of the tumor. Differentiation between intraocular metastases and uveal melanoma is limited by overlap of signal intensities. Some improvement is achieved with morphologic criteria.

Contrast-enhanced color Doppler sonography of uveal melanomas.

PURPOSE: The purpose of our study was to evaluate the use of the galactose microbubble-based contrast agent Levovist in color Doppler sonography of uveal melanomas. We also evaluated the use of the resistance index and pulsatility index in differentiating tumor-associated vessels from normal vessels in patients with uveal melanomas. METHODS: In this prospective study, 40 patients with uveal melanoma were examined with color Doppler sonography before and after the administration of the contrast agent Levovist. The Doppler signals were recorded from both the tumor and the orbit and were evaluated quantitatively and qualitatively. RESULTS: Tumor-associated vessels were detected without contrast enhancement in 36 of 40 patients and with contrast enhancement in 38 of 40 patients. The spectral characteristics of the Doppler signals did not change after the injection of Levovist. There were no differences-qualitative or quantitative-in Doppler signals between normal and tumor-associated vessels. CONCLUSIONS: The injection of Levovist slightly improved the detection of small vessels in uveal melanomas and the orbit but did not help to differentiate between normal vessels and tumoral vessels. The differentiation of a solid tumor from subretinal hemorrhage or effusion was improved.

Choroidal hemangioma: MR findings and differentiation from uveal melanoma.

BACKGROUND AND PURPOSE: The aim of this study was to establish the MR imaging characteristics of choroidal hemangioma and to compare them with those of uveal melanoma. METHODS: Among 41 patients examined at 1.5 T (4-cm surface coil, T1-weighted and fast spin-echo T2-weighted sequences), 25 had uveal melanoma and 16 had circumscribed choroidal hemangioma. After i.v. bolus injection of gadopentetate dimeglumine, dynamic and T1-weighted sequences were acquired. RESULTS: In patients with choroidal hemangioma, uniform signal characteristics were detected on fast T2-weighted images. In 15 of 16 patients with choroidal hemangioma, lesions were isointense with vitreous on fast spin-echo T2-weighted images, whereas lesions in 24 of 25 patients with uveal melanoma were hypointense. Signal characteristics of uveal melanoma and hemangioma did not differ significantly on plain T1-weighted images. Enhancement was earlier and much stronger for circumscribed choroidal hemangioma than for uveal melanoma. After i.v. bolus application of gadopentetate dimeglumine, the increase of signal intensity was higher for circumscribed choroidal hemangioma (signal intensity ratio, 5.8) than for uveal melanoma (signal intensity ratio, 2.2). CONCLUSION: Circumscribed choroidal hemangioma may be difficult to differentiate from melanoma by ophthalmologic examination. Differentiation may not be possible if direct viewing of uveal space-occupying lesions is hampered by opaque vitreous media. The characteristic findings on fast spin-echo T2-weighted MR images and early enhanced images aid in differentiating choroidal hemangioma from uveal melanoma.

Monitoring the amplification of CATCH, a 3SR based cooperatively coupled isothermal amplification system, by fluorimetric methods.

Three different types of fluorescence detection methods were employed to monitor amplification of a previously established isothermal cooperatively coupled amplification system as it can serve as a tool for the investigation of fundamental issues in evolutionary optimization. By using 5'IRD-41 fluorescent labeled primers, the intercalating dye TOPRO-1 and a 5'fluorescin/3'DABCYL 4-(4-dimethylamino-phenylazo)benzoic acid labeled ss 24 nt DNA, evolving molecular cooperation is accessible, sequence specifically as well as non-sequence-specifically without using radioactivity.

Critical size and curvature of wave formation in an excitable chemical medium.

The critical radius for the outward propagation of waves in an excitable solution of the Belousov-Zhabotinskii reaction was experimentally analyzed and found to be approximately 20 mum, being in a range predicted by theory. Thus, the wave initiation depends on the critical radius in an all-or-none fashion. For waves having high positive curvature of wave fronts, a linear relationship between the curvature and their normal velocity was established, allowing computation of a diffusion coefficient of 1.9 x 10(-5) cm(2)/s for the autocatalytic species, which agrees well with results previously obtained for negatively curved wave fronts. The analysis of the dispersion of wave velocity yielded the decrease of wave velocity for small initiation periods as predicted theoretically.

Curvature and propagation velocity of chemical waves.

The collision of circular chemical waves in an excitable medium, the Belousov-Zhabotinskii reaction, leads to characteristic cusplike structures. The high curvatures of these structures are especially suitable for experimentally verifying the predicted proportionality between the velocity and the shape of traveling waves. A computerized spectrophotometric video technique with microscopic resolution was used to determine the proportionality factor (2 x 10(-5) square centimeter per second), which in this case is the diffusion coefficient of the autocatalytic species of the reaction system. A numerical calculation of the spatiotemporal evolution of the cusp structure is in good agreement with the experimental observations.