Regression of uveal melanoma after ru-106 brachytherapy and thermotherapy based on metabolic activity measured by positron emission tomography/computed tomography

A Systematic Review and Meta-Analysis on the Diagnostic and Prognostic Values of 18F-FDG PET in Uveal Melanoma and Its Hepatic Metastasis

In this systematic review and meta-analysis (PRISMA-compliant), we tried to investigate diagnostic and prognostic values of 18F-FDG PET in uveal melanoma. A systematic search was conducted on the main medical literature databases to include studies that evaluated 18F-FDG PET as the imaging modality to evaluate patients with uveal melanoma. Overall, 27 studies were included. Twelve had data about the detection rate of 18F-FDG PET in primary intra-ocular tumours. The pooled sensitivity was 45% (95%CI: 41-50%). Furthermore, studies showed that the larger the primary tumour, the higher its uptake. Among the included studies, 13 assessed 18F-FDG PET in detecting metastasis. The pooled sensitivity and specificity were 96% (95%CI: 81-99%) and 100% (95%CI: 94-100%), respectively. Regarding liver metastasis, they were 95% (95%CI: 79-99%) and 100% (95%CI: 91-100%), respectively. Noteworthy, the level of 18F-FDG uptake was a strong predictor of patient survival. Lastly, 18F-FDG PET could characterise lesions from the histopathology perspective, distinguishing high-risk from low-risk diseases. Overall, although not reliable in detecting primary intra-ocular tumours, 18F-FDG PET is highly accurate for diagnosing metastatic uveal melanomas. It can also be a highly valuable modality in terms of patient prognostication. Thus, 18F-FDG PET can be recommended in patients diagnosed with uveal melanoma to enhance decision-making and patient management.

Imaging Techniques in the Diagnosis and Management of Ocular Tumors: Prospects and Challenges

Different types of imaging modalities are used in the diagnosis of ocular cancer. Selection of an imaging modality is based on the features of a tumor as well as the inherent characteristics of the imaging technique. It is vital to select an appropriate imaging modality in diagnosis of ocular tumor with confidence. This review focuses on five most commonly used imaging modalities, i.e., positron emission tomography-computed tomography (PET/CT), single photon emission computed tomography (SPECT), optical coherence tomography (OCT), ultrasound (US), and magnetic resonance imaging (MRI). The principal of imaging modalities is briefly explained, along with their role in the diagnosis and management of the most common ocular tumors such as retinoblastoma and uveal melanoma. Further, the diagnostic features of ocular tumors corresponding to each imaging modality and possibilities of utilizing imaging techniques in the process of ocular drug development are included in this review.

Regression patterns of choroidal melanoma: After palladium-103 (103Pd) plaque brachytherapy

Purpose:

To describe the patterns of regression of choroidal melanoma after treatment with plaque brachytherapy.

Methods:

Retrospective interventional case series including 170 consecutive patients treated with ¹⁰³Pd eye plaque radiation for choroidal melanoma. Outcome measures were changes in tumor thickness, surface characteristics, tumor vascularity, ultrasonography, fluorescein angiography, optical coherence tomography, and histopathology.

Results:

The mean initial tumor thickness was 3.9 mm (median 2.8 mm; range 2–11.3 mm) that decreased to 1.7 mm (median 1.2 mm; range 0–7.1 mm) after plaque brachytherapy. On imaging, tumors were pigmented in 51% (n = 86/170), amelanotic in 10% (n = 17/170), and variably pigmented in 39% (n = 67/170). Tumor pigmentation increased in 64% (n = 106/166), decreased in 18% (n = 30/166), and was unchanged in 18% (n = 30/166). Of the 120 that demonstrated intrinsic vascularity, 10% (n = 12/120) had decreased tumor-related vascularity and 90% (n = 108/120) showed complete resolution. Subretinal fluid was present in 34% (n = 58/170) of eyes at presentation. Of them, 15% (9; n = 9/58) had persistent SRF at last follow-up. On ultrasound imaging, 88% (n = 149/170) tumors presented with low to moderate internal reflectivity of which 61% (n = 91/149) showed increased reflectivity on regression. We noted a crescendo–decrescendo fluctuation in the presence of orange pigment lipofuscin along with complete resolution of drusenoid retinal pigment epithelial detachments. In the entire series of 170 patients, there was 0.5% (1) failure of local control, 2% (4) secondary enucleations, and 6% (10) patients developing metastasis.

Conclusion:

Findings related to choroidal melanoma regression after ¹⁰³Pd plaque brachytherapy included decreased intrinsic tumor vascularity, decreased tumor-related subretinal fluid, increased pigmentation, specific changes in orange pigment lipofuscin and resolution of drusenoid retinal pigment epithelial detachments, as well as decreased tumor thickness with an increase in internal reflectivity on ultrasound.

Clinical Predictors of Regression of Choroidal Melanomas after Brachytherapy: A Growth Curve Model

PURPOSE

To build multivariate models to assess correctly and efficiently the contribution of tumor characteristics on the rate of regression of choroidal melanomas after brachytherapy in a way that adjusts for confounding and takes into account variation in tumor regression patterns.

DESIGN

Modeling of longitudinal observational data.

PARTICIPANTS

Ultrasound images from 330 of 388 consecutive choroidal melanomas (87%) irradiated from 2000 through 2008 at the Helsinki University Hospital, Helsinki, Finland, a national referral center.

METHODS

Images were obtained with a 10-MHz B-scan during 3 years of follow-up. Change in tumor thickness and cross-sectional area were modeled using a polynomial growth-curve function in a nested mixed linear regression model considering regression pattern and tumor levels. Initial tumor dimensions, tumor-node-metastasis (TNM) stage, shape, ciliary body involvement, pigmentation, isotope, plaque size, detached muscles, and radiation parameters were considered as covariates.

MAIN OUTCOME MEASURES

Covariates that independently predict tumor regression.

RESULTS

Initial tumor thickness, largest basal diameter, ciliary body involvement, TNM stage, tumor shape group, break in Bruch's membrane, having muscles detached, and radiation dose to tumor base predicted faster regression, whether considering all tumors or those that regressed in a pattern compatible with exponential decay. Dark brown pigmentation was associated with slower regression. In multivariate modeling, initial tumor thickness remained the predominant and robust predictor of tumor regression (P < 0.0001). In addition, use of ruthenium isotope as opposed to iodine isotope (P = 0.018) independently contributed to faster regression of tumor thickness. For both isotopes considered alone, initial tumor thickness was the sole clinical predictor of regression (P < 0.0001).

CONCLUSIONS

Regression of choroidal melanoma after brachytherapy was associated with several clinical tumor and treatment parameters, most of which were shown to reflect initial tumor size. An independent predictor of regression of tumor thickness was the isotope used. These 2 covariates need to be adjusted for when exploring the associations with the rate of regression of histopathologic or genetic features of the tumor. Our model allows such future analyses efficiently without matching.