Three-dimensional ultrasound for the measurement of choroidal melanomas

Early anti-VEGF treatment for radiation maculopathy and optic neuropathy: lessons learned

Radiation therapy has saved both sight and life for eye cancer patients. The most common methods include ophthalmic plaque brachytherapy and external beam techniques. However, subsequent dose-dependent radiation vasculopathy invariably occurs within and around the targeted zone. In 2006, Finger discovered that periodic intravitreal anti-vascular endothelial growth factor (anti-VEGF) bevacizumab could reverse and suppress intraocular radiation vasculopathy. At first, it was administered at the onset of radiation-related vision loss. Though bevacizumab induced regression of macular oedema, retinal haemorrhages and cotton-wool infarcts, most patients were left with residual retinal damage, manifest as metamorphopsia and loss of vision. These results led to earlier and earlier anti-VEGF interventions: first after signs of progressive radiation retinopathy, and then for signs of radiation maculopathy, and finally for high-risk eyes with no clinical signs of retinopathy. Earlier initiation of intravitreal anti-VEGF therapy typically resulted in greater restoration and preservation of macular anatomy, reductions of retinal haemorrhages, resolution of cotton-wool spots and vision preservation. Recent research on optical coherence tomography angiography (OCT-A) has revealed that radiation vasculopathy occurs prior to clinical ophthalmic signs or symptoms. Therefore, it seemed reasonable to consider treating high-risk patients (considered certain to eventually develop radiation maculopathy) to prevent or delay vision loss. Herein, we describe the evolution of treatment for radiation maculopathy as well as recent research supporting anti-VEGF treatment of high-risk patients immediately following radiation to maximize vision outcomes.

HOW TO MEASURE THE LARGEST BASAL DIMENSION OF CHOROIDAL MELANOMA: A MATHEMATICAL STUDY

PURPOSE

To identify the most accurate ultrasonographic technique to measure the largest basal dimension (LBD) of choroidal melanoma.

METHODS

B-scan ultrasound images were retrospectively reviewed in 99 eyes of 99 choroidal melanoma patients. The LBD was measured using one, two, and three straight lines along the inner and outer sclera. Theoretical arc length, calculated using trigonometry formulas based on the spherical model with the axial length as the sphere diameter, was used for comparisons with the actual measurements using straight lines.

RESULTS

For straight-line measurements in the inner sclera, the lowest error was found when using two straight-line measurements (P = 0.118). Differences in measurement using one-segment or three-segment measurements as compared with the theoretical arc length were found to be statistically significant (P < 0.001 in both cases). For tumors with LBD smaller than 12 mm, the absolute error, compared with the theoretical arc length, was smaller than 1 mm. In the outer sclera, the smallest errors were also found for measurements using two straight-line segments; however, it was statistically different than the theoretical inner arc length (P < 0.001).

CONCLUSION

When using ultrasound to estimate LBD of ocular tumors, 2 straight-line measurements should be used when LBD is larger than 12 mm. For tumors with LBD smaller than 12 mm, measurements using 1 straight-line segment can provide accurate estimates.

Tumor Volumes in Choroidal Melanoma: Agreement Between Three-Dimensional Ultrasound and Two Mathematical Models

PURPOSE

To determine the degree of agreement between 2 mathematical models and 3-dimensional ultrasonography (3DUS) in estimating choroidal melanoma tumor volumes.

DESIGN

Reliability analysis.

METHODS

Tumor measurements estimated by 2 mathematical models (designated Formula 1 and Formula 2) were compared to those obtained by 3DUS in 45 consecutive patients with primary choroidal melanoma to determine the percentage agreement between the models and 3DUS.

RESULTS

Both formulas tended to overestimate the tumor volume. Overall, the mean volume differences between 3DUS and Formula 1 and between 3DUS and Formula 2, respectively, were 51.7 mm(3) (95% confidence interval [CI], 187.6 to 84.3) and 23.8 mm(3) (95% CI, 122.5 to 74.8). Excluding mushroom-shaped tumors, the mean volume differences were 52.0 mm(3) (95% CI, 194.9 to 91.0) and 23.0 mm(3) (95% CI, 127.0 to 81.0), respectively. In mushroom-shaped tumors, mean volume differences were 49.9 mm(3) (95% CI, 135.7 to 35.9) and 29.3 mm(3) (95% CI, 87.6 to 29.0), respectively.

CONCLUSIONS

The agreement between these mathematical models and the measured 3DUS volume was high. The data obtained in this study show that both formulas provide a simple, fast, and accurate method of estimating tumor volumes in the clinical setting, suggesting that these models could be used as a reliable and inexpensive alternative to time-consuming procedures such as 3DUS or magnetic resonance imaging. The accurate tumor volume values provided by these formulas may help to provide more reliable estimates of tumor regression or regrowth following globe-preserving treatment of choroidal melanomas, and may be a valuable prognostic indicator.

Predictive Value of Estimated Tumor Volume Measured by Ultrasonography for Occult Central Lymph Node Metastasis in Papillary Thyroid Carcinoma

The clinical and prognostic value of tumor volume in various solid tumors has been investigated. However, there have been few studies on the clinical impact of tumor volume in papillary thyroid carcinoma (PTC). This study was performed to investigate the predictive value of estimated tumor volume measured by ultrasonography for occult central neck metastasis (OCNM) of PTC. A total of 264 patients with clinically node-negative PTC on ultrasonography and computed tomography who underwent total thyroidectomy in conjunction with at least ipsilateral prophylactic central neck dissection were enrolled in this study. Tumor volume was derived with the formula used to calculate ellipsoids from two orthogonal scans during 2-D ultrasonography at initial aspiration biopsy. We retrospectively evaluated demographic characteristics, pre-operative ultrasonographic features (tumor size, volume and multifocality) and pathologic results. The OCNM rate was 35.6%; estimated tumor volume was used to predict OCNM (p = 0.035). At 0.385 mL, sensitivity and specificity were 51.1% and 66.5%, and the area under the curve for OCNM detection was 0.610. In multivariate analysis, tumor volume, but not size, was an independent predictive factor for OCNM (odds ratio = 1.83, p = 0.029). The other factors were extrathyroidal extension (odds ratio = 2.39, p = 0.004) and male gender (odds ratio = 3.90, p < 0.001). The estimated tumor volume of PTC measured by ultrasonography could be a pre-operative predictor of OCNM.

Dosimetry of (125)I and (103)Pd COMS eye plaques for intraocular tumors: report of Task Group 129 by the AAPM and ABS

Dosimetry of eye plaques for ocular tumors presents unique challenges in brachytherapy. The challenges in accurate dosimetry are in part related to the steep dose gradient in the tumor and critical structures that are within millimeters of radioactive sources. In most clinical applications, calculations of dose distributions around eye plaques assume a homogenous water medium and full scatter conditions. Recent Monte Carlo (MC)-based eye-plaque dosimetry simulations have demonstrated that the perturbation effects of heterogeneous materials in eye plaques, including the gold-alloy backing and Silastic insert, can be calculated with reasonable accuracy. Even additional levels of complexity introduced through the use of gold foil "seed-guides" and custom-designed plaques can be calculated accurately using modern MC techniques. Simulations accounting for the aforementioned complexities indicate dose discrepancies exceeding a factor of ten to selected critical structures compared to conventional dose calculations. Task Group 129 was formed to review the literature; re-examine the current dosimetry calculation formalism; and make recommendations for eye-plaque dosimetry, including evaluation of brachytherapy source dosimetry parameters and heterogeneity correction factors. A literature review identified modern assessments of dose calculations for Collaborative Ocular Melanoma Study (COMS) design plaques, including MC analyses and an intercomparison of treatment planning systems (TPS) detailing differences between homogeneous and heterogeneous plaque calculations using the American Association of Physicists in Medicine (AAPM) TG-43U1 brachytherapy dosimetry formalism and MC techniques. This review identified that a commonly used prescription dose of 85 Gy at 5 mm depth in homogeneous medium delivers about 75 Gy and 69 Gy at the same 5 mm depth for specific (125)I and (103)Pd sources, respectively, when accounting for COMS plaque heterogeneities. Thus, the adoption of heterogeneous dose calculation methods in clinical practice would result in dose differences >10% and warrant a careful evaluation of the corresponding changes in prescription doses. Doses to normal ocular structures vary with choice of radionuclide, plaque location, and prescription depth, such that further dosimetric evaluations of the adoption of MC-based dosimetry methods are needed. The AAPM and American Brachytherapy Society (ABS) recommend that clinical medical physicists should make concurrent estimates of heterogeneity-corrected delivered dose using the information in this report's tables to prepare for brachytherapy TPS that can account for material heterogeneities and for a transition to heterogeneity-corrected prescriptive goals. It is recommended that brachytherapy TPS vendors include material heterogeneity corrections in their systems and take steps to integrate planned plaque localization and image guidance. In the interim, before the availability of commercial MC-based brachytherapy TPS, it is recommended that clinical medical physicists use the line-source approximation in homogeneous water medium and the 2D AAPM TG-43U1 dosimetry formalism and brachytherapy source dosimetry parameter datasets for treatment planning calculations. Furthermore, this report includes quality management program recommendations for eye-plaque brachytherapy.

In vivo high-frequency, contrast-enhanced ultrasonography of uveal melanoma in mice: imaging features and histopathologic correlations

PURPOSE

To evaluate the usefulness of in vivo imaging of uveal melanoma in mice using high-frequency contrast-enhanced ultrasound (HF-CE-US) with 2D or 3D modes and to correlate the sonographic findings with histopathologic characteristics.

METHODS

Fourteen 12-week-old C57BL6 mice were inoculated into their right eyes with aliquots of 5 × 10(5)/2.5 μL B16LS9 melanoma cells and were randomly assigned to either of two groups. At 7 days after inoculation, tumor-bearing eyes in group 1 (n = 8) were imaged using HF-CE-US to determine the 2D tumor size and relative blood volume; eyes in group 2 (n = 6) were imaged by 3D microbubble contrast-enhanced ultrasound, and the tumor volume was determined. Histologic tumor burden was quantified in enucleated eyes by image processing software, and microvascular density was determined by counting von Willebrand factor-positive vascular channels. Ultrasound images were evaluated and compared with histopathologic findings.

RESULTS

Using HF-CE-US, melanomas were visualized as relatively hyperechoic regions. The intraobserver variability of sonographic measurements was 9.65% ± 7.89%, and the coefficient of variation for multiple measurements was 7.33% ± 5.71%. The correlation coefficient of sonographic volume or size and histologic area was 0.71 (P = 0.11) and 0.79 (P = 0.32). The relative blood volume within the tumor demonstrated sonographically correlated significantly with histologic tumor vascularity (r = 0.83; P < 0.001).

CONCLUSIONS

There was a positive linear correlation between sonographic tumor measurements and histologic tumor burden in the mouse ocular melanoma model. Contrast-enhanced intensity corresponded with microvascular density and blood volume. HF-CE-US is a real-time, noninvasive, reliable method for in vivo evaluation of experimental intraocular melanoma tumor area and relative blood volume.

Three-dimensional ultrasound imaging

This review is about the development of three-dimensional (3D) ultrasonic medical imaging, how it works, and where its future lies. It assumes knowledge of two-dimensional (2D) ultrasound, which is covered elsewhere in this issue. The three main ways in which 3D ultrasound may be acquired are described: the mechanically swept 3D probe, the 2D transducer array that can acquire intrinsically 3D data, and the freehand 3D ultrasound. This provides an appreciation of the constraints implicit in each of these approaches together with their strengths and weaknesses. Then some of the techniques that are used for processing the 3D data and the way this can lead to information of clinical value are discussed. A table is provided to show the range of clinical applications reported in the literature. Finally, the discussion relating to the technology and its clinical applications to explain why 3D ultrasound has been relatively slow to be adopted in routine clinics is drawn together and the issues that will govern its development in the future explored.

Measurement of human choroidal melanoma xenograft volume in rats using high-frequency ultrasound

PURPOSE

The purpose of this study was to test the hypothesis that the volume of primary orthotopic human choroidal melanoma xenografts can be quantified noninvasively in the same nude rat over time using a portable, high-resolution, high-frequency ultrasound (HF-US) system.

METHODS

C918 human choroidal melanoma spheroids were implanted in the superior suprachoroidal space of 26 WAG/RijHsd-rnu nude rats. Fourteen rats were anesthetized 14 days after tumor implantation, and HF-US B-scan images of the tumor-bearing eye were captured at 250-mum intervals. Tumor areas were measured on each image and numerically integrated to calculate volume. Tumor volumes were also estimated from serial histologic sections in six rats. Twelve other rats were anesthetized and weighed every 4 to 5 days after implantation for 2 weeks, and HF-US B-scan image series were acquired for subsequent measurement of tumor volume.

RESULTS

Tumors could be visualized as heterogeneous, relatively hyperechoic regions in the superior portion of the eye. These regions were verified as tumor by comparison with histologic sections, and histologic and HF-US volumes were highly correlated (r = 0.961; P = 0.002). For the determination of HF-US volume, the intraobserver variability was 9.7% +/- 5.1% (n = 8), and the coefficient of variation for multiple measurements was 12.1% +/- 6.8% (n = 12). Tumor volume could be repeatedly measured in the same rat every 4 to 5 days for 2 weeks without significant weight loss.

CONCLUSIONS

HF-US is a safe, practical method to measure tumor volume in the same nude rat over time in this orthotopic xenograft model of human choroidal melanoma.

Baseline echographic characteristics of tumors in eyes of patients enrolled in the Collaborative Ocular Melanoma Study: COMS report no. 29

PURPOSE

To report baseline echographic characteristics of tumors in patients enrolled in the Collaborative Ocular Melanoma Study (COMS) randomized trials, to determine how often these characteristics matched prespecified criteria for choroidal melanoma, to explore associations between echographic variables, and to compare specific echographic characteristics with pathologic characteristics of tumors in enucleated eyes.

DESIGN

Retrospective analyses of baseline data from multicenter randomized clinical trials.

PARTICIPANTS

Patients enrolled in the COMS large trial or medium tumor trials (N = 2320).

METHODS

Standardized echography was used to document selected characteristics of tumors at baseline. Criteria were established to assess the consistency of echographic features with the diagnosis of melanoma. For eyes assigned to enucleation, the echographic diagnosis and evaluation for extraocular extension by the Echography Center were compared with gradings made by the Pathology Center and Pathology Review Committee.

MAIN OUTCOME MEASURES

Presence of various echographic and pathologic characteristics.

RESULTS

Two thousand forty-three tumors (88%) exhibited low to medium reflectivity (n = 1409), a mushroom shape (n = 101), or both (n = 533). Tumors with apical height > 10 mm were more likely (P<0.001) to have a mushroom shape and less likely to have a posterior location (P<0.001) than less elevated tumors. One thousand five hundred fifty-nine (99.7%) of 1563 tumors judged by echography to be consistent with the diagnosis of melanoma were confirmed by pathology to be choroidal melanoma. For measurable extrascleral tumors < 1.5 mm in height by pathology, the Echography Center graders judged extrascleral extension as possibly present in only 1 of 16 (6%) tumors, compared with 57% (4/7) of eyes with extrascleral extension measuring > or = 1.5 mm in height.

CONCLUSIONS

Eighty-eight percent of the tumors in the COMS exhibited features characteristic for melanoma: low to medium reflectivity, the classic mushroom shape, or both. Using additional preset criteria, 96% of tumors exhibited baseline echographic characteristics consistent with the diagnosis of melanoma. Echography graders were able to detect extrascleral nodules > or = 1.5 mm in elevation but not minimally elevated extraocular tumor extension. Clinicians and echographers can use these data to improve their understanding of the echographic features of untreated uveal melanomas.

Estimating choroidal melanoma volume: comparison of methods

PURPOSE

To evaluate published methods of estimating choroidal melanoma volume.

DESIGN

Prospective consecutive case series.

PARTICIPANTS

Ten consecutive patients with primary choroidal melanoma.

METHODS

After determination of tumor dimensions (largest tumor basal diameter, basal perpendicular diameter, and height), tumor volume was calculated for each tumor by using the 5 published methods. Percent differences in tumor volume were determined for each tumor as calculated by different methods.

MAIN OUTCOME MEASURE

Choroidal melanoma volume.

RESULTS

The mean variation in estimated tumor volume expressed as a ratio was 2.33 (range, 1.64-3.84).

CONCLUSIONS

Choroidal melanoma volume calculation methods are inconsistent and caution is needed when volume measures are used for prognostic classification.

A reference standard for the measurement of macular oedema

Macular oedema is associated with several conditions that lead to blindness. Accurate measurement of macular thickness is important in order to follow disease progression and evaluate treatments. Four techniques are examined to determine the best reference standard for the detection and quantification of macular oedema: ultrasound, optical coherence tomography, the retinal thickness analyser, and the scanning laser ophthalmoscope. The three optical techniques have the highest resolution and sensitivity, in particular optical coherence tomography. Ultrasound can be useful where dense opacities preclude optical imaging.

Calculated tumour volume as a prognostic parameter for survival in choroidal melanomas

PURPOSE

Tumour diameter, tumour height, and tumour volume are considered important prognostic indicators of survival in choroidal melanomas. In this study, we investigated the prognostic impact on survival of the easily calculated volume estimate based on the assumption of a half-rotation ellipsoid.

METHODS

The largest tumour diameter and tumour height were measured by ultrasound A- and B-scan in 93 patients with choroidal melanoma. Tumour volume was calculated by the half volume of a rotation ellipsoid formula, rotated around the y-axis, and compared to tumour diameter and tumour height. All parameters were correlated to the clinical outcome of the patients.

RESULTS

At the time of diagnosis, the mean diameter was 10.4 mm (range 4.1-18.9 mm), and the mean height was 5.7 mm (range 1.74-14.9 mm). The range of the calculated tumour volume was between 11 and 628 mm(3) (mean volume 190 mm(3)). Among all patients, distant metastases occurred in 10 patients (10.8%). In a univariate approach using Mantel-Haenszel log-rank test, the calculated tumour volume at the time of diagnosis was the best prognostic indicator of survival followed by tumour diameter and tumour height (P=0.028). When tumour volume, horizontal and vertical tumour diameter, age, sex, and primary tumour therapy were considered in a multivariate approach using Cox proportional Hazard model, only tumour volume turned out as a significant prognostic parameter (P=0.001).

CONCLUSIONS

Calculated tumour volume is a better prognostic indicator of survival of patients with choroidal melanomas than the largest tumour diameter and tumour height, and might be established in daily routine.

Three-dimensional ultrasonography for volume measurement of thyroid nodules in children

OBJECTIVE

The aim of this study was to compare the accuracy of thyroid nodule volume measurements performed by 2- and 3-dimensional ultrasonography and to evaluate the dependence of volume measurement results on nodule size and echographic characteristics.

METHODS

Results of multiple 2- and 3-dimensional ultrasonographic volume measurements of thyroid nodules in 102 children with different variants of thyroid nodular disease were reviewed retrospectively. The standardized difference, within-observer variability, and repeatability were estimated for both 2- and 3-dimensional ultrasonography. The mean age of the patients +/- SD in the examined group was 14.9 +/- 2.8 years; the mean volume of thyroid nodules was 0.78 +/- 0.13 mL.

RESULTS

The SD of the normalized difference for 3-dimensional ultrasonography (2.8%) showed the clear superiority of its accuracy over 2-dimensional ultrasonography (15.9%; F test, P < .01). Intraobserver variability and repeatability for both examined methods had significant dependence on the nodule outline. For 2-dimensional ultrasonography, the intraobserver variability increased from 14.0% in nodules with a regular outline to 24.5% in those with an irregular outline (P < .001), and for 3-dimensional ultrasonography, it increased from 5.1% to 9.3% (P < .001). Intraobserver repeatability dropped from 85.4% in regular nodules to 74.6% in irregular nodules (P < .001) for 2-dimensional ultrasonography and from 94.7% to 90.4% (P < .001) for 3-dimensional ultrasonography.

CONCLUSIONS

Volume measurements by 3-dimensional ultrasonography are more accurate, showing lower intraobserver variability and higher repeatability, than those made by 2-dimensional ultrasonography with less dependence on nodule size and echographic characteristics.

Accuracy of three-dimensional ultrasound for thyroid volume measurement in children and adolescents

The aim of this study was to estimate accuracy, intraobserver variability, and repeatability of thyroid volume measurement by ultrasound using conventional two-dimensional ellipsoid model (2D US) and manual planimetry of three-dimensional images (3D US). The sonographic images of 47 children with thyroid nodular pathology who were referred for thyroid surgery in Belarus were evaluated prospectively. Two-dimensional images were acquired using the ultrasound scanner with 7.5-MHz linear probe. Three-dimensional data sets were created using three-dimensional system, FreeScan. For each patient thyroid volume was measured three times using both two- and three-dimensional methods. Results of volume estimation were then compared to the volume of thyroid gland determined after surgery. Standardized difference between thyroid volume estimated by ultrasound and surgery (mean +/- standard deviation (SD), %) for 3D and 2D US methods was 1.8 +/- 5.2% and 3.2 +/- 15.3%, respectively. The 3D US has lower intraobserver variability (3.4%) and higher repeatability (96.5%) than 2D US with 14.4% variability and 84.8% repeatability (p < 0.001). In conclusion, three-dimensional sonography allows accurate measurement of thyroid volume with low intraobserver variability and high repeatability.

Three dimensional ultrasound of retinoblastoma: initial experience

AIM

To use 3D ultrasonography (3DUS) for the diagnosis of retinoblastoma.

METHODS

Five eyes of three children with retinoblastoma were evaluated using a commercially available computerised 3DUS system. Interactive sectioning of the stored and reconstructed 3D volumes were performed. 3DUS and histopathological findings were correlated after enucleation.

RESULTS

3DUS examination revealed characteristics consistent with retinoblastoma: endophytic mass, retinal detachment, intratumoural calcifications, and secondary orbital shadowing. Unlike 2D imaging, 3DUS allowed for analysis of the acquired and stored volumes. Rotation and sectioning of this volume allowed the discovery of new oblique and coronal views. For example, calcium related orbital shadows were seen as 3D volumes and (coronal) cross sections of the optic nerve were evaluated for evidence of intraneural invasion by retinoblastoma.

CONCLUSION

This is the first reported series of patients examined with 3DUS imaging for retinoblastoma. This technique allowed for new oblique and coronal views of the tumour and optic nerve. The ability to retrospectively analyse the (scanned and stored) ocular volume facilitated patient care, teaching, tumour-volume analysis, and telemedicine.