Uveal Melanoma
Figure 3: Color Fundus Photography and Ultrasonography is Useful in Differentiating Benign Lesions from Choroidal Melanoma
A
Figure 4: Colour Doppler Imaging in Choroidal Melanoma A
B
B
A colour Doppler image of a dome-shaped choroidal melanoma (A). Flow patterns establish the highly vascular nature of the tumour (B). Source: modified with permission from Torres et al., 2011.33
measurements of tumour size with A-scan, thus B-scan USG is usually preferred for tumour biometry.
Three-dimensional Ultrasonography C
While performing standard 2D-USG, the operator is required to create a mental 3D representation of the tumour. The captured 2D images do not show tumour volume or surface characteristics. The images may not include the tumour apex in atypically shaped tumours. In contrast, 3D-USG collects echographic data from a large series of 2D-USG images that are quickly acquired and assembled using a computer algorithm. The resulting 3D images can be rotated, sliced or viewed in different planes.7
Tumour biometry using 3D-USG in 42 patients with choroidal melanoma found this technique to be as reproducible as clinical examination and standard USG for measuring tumour diameter and height. 3D-USG was slightly more accurate in its ability to assess tumour volume as it accounts for geometry in a superior manner than standard USG.8
3D-USG has a shorter examination time and does not
An 83-year-old Caucasian woman was referred for a suspicious choroidal lesion in the inferonasal quadrant of the left eye. Clinical examination revealed an irregular pigmented mass (A) contiguous with regions of sub-retinal haemorrhage (B). B-scan ultrasonography showed high internal reflectivity, which helped to differentiate this benign lesion from choroidal melanoma (C).
require additional operator training.7 Colour Doppler Imaging
reflectivity, internal structure and sound attenuation. Reflectivity is graded by the height of the spike on A-scan compared with a zero baseline and a 100 % spike of retina and all tissues equal or higher in density. Reflectivity can only be accurately determined when the A-scan probe is directed perpendicular to the lesion. Choroidal melanoma has a low-to-medium reflectivity and a high initial spike on standardised A-scan USG (see Figure 3). Sound attenuation is often observed at the base of the tumour. It is often difficult to obtain
58
Based on the Doppler phenomenon, colour Doppler imaging (CDI) is a non-invasive technique used to study blood flow. The Doppler phenomenon states that the frequency of a wave changes when the observer or source move relative to one another. CDI displays colour-encoded flow information in a 2D-USG image and can be used to visualise small blood vessels in the intrinsic circulation of the tumour. Reduction in the number of vascular regions may also serve as an indicator of response to treatment.
In one study of 44 intraocular mass lesions, abnormal Doppler shifts were demonstrated in 39 cases.9
Using CDI, orbital haemangioma and EUROPEAN OPHTHALMIC REVIEW
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68