Preoperative staging of liver metastases from uveal melanoma by magnetic resonance imaging (MRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET)

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.

Management of Uveal Melanoma: Updated Cancer Care Alberta Clinical Practice Guideline

OBJECTIVE

The purpose of this guideline update is to reassess and update recommendations in the prior guideline from 2016 on the appropriate management of patients with uveal melanoma.

METHODS

In 2021, a multidisciplinary working group from the Provincial Cutaneous Tumour Team, Cancer Care Alberta, Alberta Health Services was convened to update the guideline. A comprehensive review of new research evidence in PubMed as well as new clinical practice guidelines from prominent oncology groups informed the update. An enhancement in methodology included adding levels of evidence and strength of recommendations. The updated guideline was circulated to all members of the Provincial Cutaneous Tumour Team for review and endorsement.

RESULTS

New and modified recommendations address provider training requirements, diagnostic imaging for the detection of metastases, neo-adjuvant pre-enucleation radiotherapy, intravitreal anti-vascular endothelial growth factor agents for radiation retinopathy, genetic prognostic testing, surveillance following definitive local therapy, and systemic therapy for patients with metastatic uveal melanoma.

DISCUSSION

The recommendations represent evidence-based standards of care agreed to by a large multidisciplinary group of healthcare professionals.

Surveillance for Metastasis in High-Risk Uveal Melanoma Patients: Standard versus Enhanced Protocols

PURPOSE

to evaluate the effectiveness of enhanced surveillance protocols (EP) utilizing high frequency (HF) or enhanced modality (EM) compared to the standard protocol (SP) in detecting metastasis and determining their impact on overall survival (OS) in high-risk uveal melanoma (UM) patients.

METHODS

A total of 87 consecutive patients with Class 2 (high risk) primary UM were enrolled, with negative baseline systemic staging. The patients underwent systemic surveillance with either SP (hepatic ultrasonography [US] every 6 months) or EP (either HF [US every 3 months] or EM [incorporation hepatic computed tomography/magnetic resonance imaging]) following informed discussion. The main outcome measures were largest diameter of largest hepatic metastasis (LDLM), number of hepatic metastatic lesions, time to detection of metastasis (TDM), and OS.

RESULTS

This study revealed significant differences in LDLM between surveillance protocols, with the use of EP detecting smaller metastatic lesions (HF, EM, and SP were 1.5 cm, 1.6 cm, and 6.1 cm, respectively). Patients on the EM protocol had a lower 24-month cumulative incidence of >3 cm metastasis (3.5% EM vs. 39% SP; p = 0.021), while those on the HF protocol had a higher 24-month cumulative incidence of ≤3 cm metastasis compared to SP (31% HF vs. 10% SP; p = 0.017). Hazard of death following metastasis was significantly reduced in the EP (HR: 0.25; 95% CI: 0.07, 0.84), HF (HR: 0.23; 95% CI: 0.06, 0.84), and EM (HR: 0.11; 95% CI: 0.02, 0.5) groups compared to SP. However, TDM and OS did not significantly differ between protocols.

CONCLUSIONS

Enhanced surveillance protocols improved early detection of hepatic metastasis in UM patients but did not translate into a survival advantage in our study cohort. However, early detection of metastasis in patients receiving liver-directed therapies may lead to improved overall survival.

Consensus statement for metastatic surveillance of uveal melanoma in Scotland

Ophthalmic treatments are successful in managing uveal melanomas achieving good local control. However, a large number still metastasise, primarily to the liver, resulting in mortality. There is no consensus across the world on the mode, frequency, duration or utility of regular liver surveillance for metastasis and there are no published protocols. The Scottish Ocular Oncology Service (SOOS) constituted a Scottish Consensus Statement Group (SCSG) which included ocular oncologists, medical oncologists, radiologists and a uveal melanoma patient as a lay member. This group carried out an extensive review of literature followed by discussions to arrive at a consensus regarding surveillance planning for posterior uveal melanoma patients in Scotland. The Consensus Statement would provide a framework to guide each patient's surveillance plan and provide all patients with clarity and transparency on the issue. The SCSG was unable to find adequate evidence on which to base the strategy. The consensus statement recommends a risk-stratified approach to surveillance for these patients dividing them into low to medium-risk and high-risk groups defining the mode and duration of surveillance for each. It supplements the UK-wide Uveal Melanoma National Guidelines and allows a more uniform consensus-based approach to surveillance in Scotland. It has been adopted nationally by all health care providers in Scotland as a guideline and is available to patients on a publicly accessible website.

Advances in the clinical management of uveal melanoma

Melanomas arising in the uveal tract of the eye are a rare form of the disease with a biology and clinical phenotype distinct from their more common cutaneous counterparts. Treatment of primary uveal melanoma with radiotherapy, enucleation or other modalities achieves local control in more than 90% of patients, although 40% or more ultimately develop distant metastases, most commonly in the liver. Until January 2022, no systemic therapy had received regulatory approval for patients with metastatic uveal melanoma, and these patients have historically had a dismal prognosis owing to the limited efficacy of the available treatments. A series of seminal studies over the past two decades have identified highly prevalent early, tumour-initiating oncogenic genomic aberrations, later recurring prognostic alterations and immunological features that characterize uveal melanoma. These advances have driven the development of a number of novel emerging treatments, including tebentafusp, the first systemic therapy to achieve regulatory approval for this disease. In this Review, our multidisciplinary and international group of authors summarize the biology of uveal melanoma, management of primary disease and surveillance strategies to detect recurrent disease, and then focus on the current standard and emerging regional and systemic treatment approaches for metastatic uveal melanoma.

Imaging of Uveal Melanoma—Current Standard and Methods in Development

Simple Summary

Uveal melanoma is the most prevalent intraocular tumor in adults, derived from melanocytes; the liver is the most common site of its metastases. Due to troublesome tumor localization, different imaging techniques are utilized in diagnostics, i.e., fundus imaging (FI), ultrasonography (US), optical coherence tomography (OCT), single-photon emission computed tomography (SPECT), positron emission tomography/computed tomography (PET/CT), magnetic resonance imaging (MRI), fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), or fundus autofluorescence (FAF). Specialists eagerly use these techniques, but sometimes the precision and quality of the obtained images are imperfect, raising diagnostic doubts and prompting the search for new ones. In addition to analyzing the currently utilized methods, this review also introduces experimental techniques that may be adapted to clinical practice in the future. Moreover, we raise the topic and present a perspective for personalized medicine in uveal melanoma treatment.

Abstract

Uveal melanoma is the most common primary intraocular malignancy in adults, characterized by an insidious onset and poor prognosis strongly associated with tumor size and the presence of distant metastases, most commonly in the liver. Contrary to most tumor identification, a biopsy followed by a pathological exam is used only in certain cases. Therefore, an early and noninvasive diagnosis is essential to enhance patients’ chances for early treatment. We reviewed imaging modalities currently used in the diagnostics of uveal melanoma, including fundus imaging, ultrasonography (US), optical coherence tomography (OCT), single-photon emission computed tomography (SPECT), fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), fundus autofluorescence (FAF), as well as positron emission tomography/computed tomography (PET/CT) or magnetic resonance imaging (MRI). The principle of imaging techniques is briefly explained, along with their role in the diagnostic process and a summary of their advantages and limitations. Further, the experimental data and the advancements in imaging modalities are explained. We describe UM imaging innovations, show their current usage and development, and explain the possibilities of utilizing such modalities to diagnose uveal melanoma in the future.

Metastatic uveal melanoma: The final frontier

Treatment of primary intraocular uveal melanoma has developed considerably, its driver genes are largely unraveled, and the ways to assess its risk for metastases are very precise, being based on an international staging system and genetic data. Unfortunately, the risk of distant metastases, which emerge in approximately one half of all patients, is unaltered. Metastases are the leading single cause of death after uveal melanoma is diagnosed, yet no consensus exists regarding surveillance, staging, and treatment of disseminated disease, and survival has not improved until recently. The final frontier in conquering uveal melanoma lies in solving these issues to cure metastatic disease. Most studies on metastatic uveal melanoma are small, uncontrolled, retrospective, and do not report staging. Meta-analyses confirm a median overall survival of 10-13 months, and a cure rate that approaches nil, although survival exceeding 5 years is possible, estimated 2% either with first-line treatment or with best supportive care. Hepatic ultrasonography and magnetic resonance imaging as surveillance methods have a sensitivity of 95-100% and 83-100%, respectively, to detect metastases without radiation hazard according to prevailing evidence, but computed tomography is necessary for staging. No blood-based tests additional to liver function tests are generally accepted. Three validated staging systems predict, each in defined situations, overall survival after metastasis. Their essential components include measures of tumor burden, liver function, and performance status or metastasis free interval. Age and gender may additionally influence survival. Exceptional mutational events in metastases may make them susceptible to checkpoint inhibitors. In a large meta-analysis, surgical treatment was associated with 6 months longer median overall survival as compared to conventional chemotherapy and, recently, tebentafusp as first-line treatment at the first interim analysis of a randomized phase III trial likewise provided a 6 months longer median overall survival compared to investigator's choice, mostly pembrolizumab; these treatments currently apply to selected patients. Promoting dormancy of micrometastases, harmonizing surveillance protocols, promoting staging, identifying predictive factors, initiating controlled clinical trials, and standardizing reporting will be critical steppingstones in reaching the final frontier of curing metastatic uveal melanoma.

Nuclear Medicine and Molecular Imaging in Nodal Staging and Surveillance of Ocular Melanoma: Case Reports and Review of the Literature

Ocular melanoma (OM) is a rare noncutaneous malignancy and consists of 2 different subtypes based on the anatomic location in the eye: uveal melanoma and conjunctival melanoma. Like cutaneous melanoma, OM benefits from nuclear medicine and molecular imaging in nodal staging and clinical management. Through the illustration of 2 distinctive cases, we aim to demonstrate the complementary roles of standard lymphoscintigraphy, advanced SPECT/CT, ¹⁸F-FDG PET/CT, and ¹⁸F-FDG PET/MRI in accurate nodal staging and surveillance of OM. We also review the epidemiology, existing staging guidelines, and management of uveal melanoma and conjunctival melanoma.

Application of Multimodal and Molecular Imaging Techniques in the Detection of Choroidal Melanomas

Choroidal melanomas are the most common ocular malignant tumors worldwide. The onset of such tumors is insidious, such that affected patients often have no pain or obvious discomfort during early stages. Notably, enucleation is required for patients with a severe choroidal melanoma, which can seriously impact their quality of life. Moreover, choroidal melanomas metastasize early, often to the liver; this eventually causes affected patients to die of liver failure. Therefore, early diagnosis of choroidal melanomas is extremely important. Unfortunately, an early choroidal melanoma is easily confused with a choroidal nevus, which is the most common benign tumor of the eye and does not often require surgical treatment. This review discusses recent advances in the use of multimodal and molecular imaging to identify choroidal melanomas and choroidal nevi, detect early metastasis, and diagnose patients with choroidal melanomas.

Cost-utility analysis of a decade of liver screening for metastases using the Liverpool Uveal Melanoma Prognosticator Online (LUMPO)

This paper outlines a method for cost-utility analysis of liver screening for metastases in patients with posterior uveal melanoma (UM). A semiparametric model of the cumulative incidence of onset of liver metastases was fitted to a retrospective data set of 615 subjects with clinical follow-up with respect to liver surveillance imaging and outcome. The model was internally validated via bootstrap resampling in terms of its discrimination and calibration performance. Receiver operating characteristics (ROC) were derived at different time points. The discrimination performances are consistent across time. The area under the ROC curve at 5 years post treatment was 0.85 [95% CI: 0.81-0.88]. A goodness-of-fit test gives χ²(10)=5.3,p=0.9 demonstrating no evidence against the null hypothesis of zero difference between observed and expected onset of metastatic events. Results showed that at 80% sensitivity, 87% of UM patients will avoid unnecessary radiological scans. This provides potential cost savings of between £46,000 and £97,000 per year to the National Health Service assuming 600 new cases per year.

Optimizing the treatment of liver metastases from uveal melanomas with transarterial chemoembolization using melphalan and calibrated microspheres

INTRODUCTION

Patients with liver metastasis from uveal melanoma have a poor prognosis. Efficacy and safety of hepatic transarterial chemoembolization (TACE) using melphalan and microspheres was evaluated.

MATERIALS AND METHODS

Monocentric retrospective study of all consecutive patients treated by TACE using melphalan and 250μm calibrated microspheres between 2004 and 2016. Radiological response was assessed according to RECIST 1.1, modified (m)-RECIST and EASL on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI). The primary endpoint was overall survival (OS). Liver metastasis response, hepatic, extrahepatic and global progression free survival (PFS) complications were evaluated with the common terminology criteria for adverse events version 4.0 (CTCAE 4.0) and survival factors were secondary endpoints.

RESULTS

Thirty-four patients underwent 138 TACE (4; 4.1 sessions; range 1-9). Median OS was 16.5 months (mean 21.6 months). Liver metastasis response combining partial and complete response was 42.4%, 97%, 97% with RECIST 1.1, mRECIST, EASL, respectively. There were 58 severe (CTCAE≥3) but manageable complications in 28 patients, except for 1 toxic death.

CONCLUSION

For patients with liver metastases from uveal melanoma ineligible for local treatments, TACE using melphalan may be performed as first line therapy in metastatic miliary disease from uveal melanomas with careful supportive care.

Clinical Value of PET/CT in Staging Melanoma and Potential New Radiotracers

BACKGROUND

18F-FDG PET/CT has been suggested as an effective tool to stage patients affected by melanoma. In the latest years, new radiopharmaceuticals have been proposed and the use of hybrid PET/ceCT has emerged.

OBJECTIVE

To review recent evidence on the role of PET/CT in melanoma staging as well as its potential for future developments.

METHODS

A comprehensive computer literature search of PubMed/MEDLINE was carried out to find relevant published articles concerning the feasibility of PET/CT in patients with malignant melanoma.

RESULTS

Some recent studies about potentials and limitations of 18F-FDG PET/CT in staging melanoma, new PET radiotracers beyond 18F-FDG and application of hybrid PET/ceCT have been reviewed and discussed.

CONCLUSION

PET/CT plays an important role in the staging workup of patients affected by melanoma. New radiopharmaceuticals and hybrid PET/ceCT could improve the potential of this diagnostic tool in this field.

Hepatic Ultrasonography Compared With Computed Tomography and Magnetic Resonance Imaging at Diagnosis of Metastatic Uveal Melanoma

PURPOSE

To evaluate the consistency of hepatic ultrasonography (US) with staging computed tomography (CT) and magnetic resonance imaging (MRI), to analyze why US was inconsistent with CT/MRI, and to compare CT/MRI.

DESIGN

Reliability analysis.

METHODS

Two hundred fifteen patients whose primary uveal melanoma was managed in the Helsinki University Hospital and who were diagnosed with hepatic metastases by US within 60 days of staging CT/MRI from January 1999 to December 2016 were included. Patients attended a real-life follow-up schedule including hepatic US, liver function tests (LFT), and a confirmatory CT/MRI. We evaluated the consistency of US with staging CT/MRI regarding the presence and number of metastases.

RESULTS

The enrolled patients underwent 215 US, 167 CT, and 69 MRI examinations, and 67% of them had biopsy-confirmed metastases. Screening was regular for 98% of the patients, and 66% were asymptomatic. US was fully consistent with CT/MRI in detecting metastases in 113 (53%) patients, in 63 (29%) CT/MRI showed more metastases, and in 16 (7%) CT/MRI showed fewer metastases than US. CT/MRI was inconsistent with US in 23 (11%) patients. The sensitivity of US in detecting metastases was 96% (95% confidence interval, 92-98). US failed to suggest metastases in 10 patients. LFT were abnormal in 6 of them, and a newly detected hepatic lesion was present by US in 4.

CONCLUSIONS

Hepatic US is a sensitive screening modality in detecting metastases in patients with primary uveal melanoma, if combined with LFT and, in case of any newly detected lesion, a confirmatory MRI.

Comparison of Al18F- and 68Ga-labeled NOTA-PEG4-LLP2A for PET imaging of very late antigen-4 in melanoma

Malignant melanoma is an aggressive cancer with poor prognosis. Very late antigen-4 (VLA-4) is overexpressed in melanoma and many other tumors, making it an attractive target for developing molecular diagnostic and therapeutic agents. We compared Al18F- and 68Ga-labeled LLP2A peptides for PET imaging of VLA-4 expression in melanoma. The peptidomimetic ligand LLP2A was modified with chelator 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA), and the resulting NOTA-PEG4-LLP2A peptide was then radiolabeled with Al18F or 68Ga. The two labeled peptides were assayed for in vitro and in vivo VLA-4 targeting efficiency. Good Al18F and 68Ga radiolabeling yields were achieved, and the resulting PET tracers showed good serum stability. In the in vivo evaluation of the B16F10 xenograft mouse model, both tracers exhibited high accumulation with good contrast in static PET images. Compared with 68Ga-NOTA-PEG4-LLP2A, Al18F-NOTA-PEG4-LLP2A resulted in relatively higher background, including higher liver uptake (1 h: 20.1 ± 2.6 vs. 15.3 ± 1.7%ID/g, P < 0.05; 2 h: 11.0 ± 1.2 vs. 8.0 ± 0.8%ID/g, P < 0.05) and lower tumor-to-blood ratios (2.5 ± 0.4 vs. 3.3 ± 0.5 at 1 h, P < 0.05; 5.1 ± 0.9 vs. 7.3 ± 0.6 at 2 h, P < 0.01) at some time points. The results obtained from the mice blocked with unlabeled peptides and VLA-4-negative A375 xenografts groups confirmed the high specificity of the developed tracers. Despite the relatively high liver uptake, both Al18F-NOTA-PEG4-LLP2A and 68Ga-NOTA-PEG4-LLP2A exhibited high VLA-4 targeting efficacy with comparable in vivo performance, rendering them promising candidates for imaging tumors that overexpress VLA-4.

18F-Labeled Cyclized α-Melanocyte-Stimulating Hormone Derivatives for Imaging Human Melanoma Xenograft with Positron Emission Tomography

Since metastatic melanoma is deadly, early diagnosis thereof is crucial for managing the disease. We recently developed α-melanocyte-stimulating hormone (αMSH) derivatives, [⁶⁸Ga]Ga-CCZ01048 and [¹⁸F]CCZ01064, that target the melanocortin 1 receptor (MC1R) for mouse melanoma imaging. In this study, we aim to evaluate [¹⁸F]CCZ01064 as well as a novel dual-ammoniomethyl-trifluoroborate (AmBF₃) derivative, [¹⁸F]CCZ01096, for targeting human melanoma xenograft using μPET imaging. The peptides were synthesized on solid phase using Fmoc chemistry. Radiolabeling was achieved in a one-step ¹⁸F-¹⁹F isotope-exchange reaction. μPET imaging and biodistribution studies were performed in NSG mice bearing SK-MEL-1 melanoma xenografts. The MC1R density on the SK-MEL-1 cell line was determined to be 972 ± 154 receptors/cell (n = 4) via saturation assays. Using [¹⁸F]CCZ01064, moderate tumor uptake (3.05 ± 0.47%ID/g) and image contrast were observed at 2 h post-injection. Molar activity was determined to play a key role. CCZ01096 with two AmBF₃ motifs showed comparable sub-nanomolar binding affinity to MC1R and much higher molar activity. This resulted in improved tumor uptake (6.46 ± 1.42%ID/g) and image contrast (tumor-to-blood and tumor-to-muscle ratios were 30.6 ± 5.7 and 85.7 ± 11.3, respectively) at 2 h post-injection. [¹⁸F]CCZ01096 represents a promising αMSH-based μPET imaging agent for human melanoma and warrants further investigation for potential clinical translation.

Hepatic abnormalities identified by staging MRI and accuracy of MRI of patients with uveal melanoma

BACKGROUND

Metastases to the liver are often the first finding in patients with uveal melanoma with extraocular disease, but little has been published on the utility of staging MRI at initial diagnosis. We aimed to evaluate the proportion of abnormal hepatic findings on baseline MRI and accuracy of MRI in patients with newly diagnosed uveal melanoma.

METHODS

This is a single-centre, retrospective, institutional review board-approved study of 145 consecutive patients diagnosed with uveal melanoma, at Memorial Sloan Kettering Cancer Center between 2004 and 2016, who had staging MRI within 1 month of diagnosis. Scans were classified as normal or abnormal, and further distinguished as abnormal non-metastatic, uncharacterisable lesions and suspicious for metastasis. Where available, follow-up MRI (at ~1 year) or biopsies were reviewed.

RESULTS

MRI in 145 patients revealed 62% (90) with abnormal hepatic findings; out of these 87% (78) had non-metastatic benign findings, 6.7% (6) had unclassifiable lesions and 6.7% (6) were suspicious for metastasis (6). Abnormal non-metastatic findings included 72 focal (36 solitary and 36 multiple) and 12 diffuse lesions. Lesions suspicious for metastases were found in 6 of 145 patients (4%), despite normal liver function tests. Of these, five had confirmed liver metastases and one patient had a stable, presumed non-metastatic lesion on follow-up. In this study, the sensitivity and specificity of staging MRI for all findings were 83.3% (95% CI 35.9 to 99.6) and 99.0% (95% CI 94.3 to 99.9), respectively.

CONCLUSION

Staging MRI of patients with newly diagnosed uveal melanoma accurately identified early metastases. Furthermore, imaging revealed hepatic abnormalities in the majority of patients, although as expected few of these represented metastatic disease.

Molecular Imaging and Radionuclide Therapy of Melanoma Targeting the Melanocortin 1 Receptor

Melanoma is a deadly disease at late metastatic stage, and early diagnosis and accurate staging remain the key aspects for managing melanoma. The melanocortin 1 receptor (MC1 R) is overexpressed in primary and metastatic melanomas, and its endogenous ligand, the α-melanocyte-stimulating hormone (αMSH), has been extensively studied for the development of MC1 R-targeted molecular imaging and therapy of melanoma. Natural αMSH is not well suited for this purpose due to low stability in vivo. Unnatural amino acid substitutions substantially stabilized the peptide, while cyclization via lactam bridge and metal coordination further improved binding affinity and stability. In this study, we summarized the development and the in vitro and in vivo characteristics of the radiolabeled αMSH analogues, including ^99mTc-, ¹¹¹In-, ⁶⁷ Ga-, or ¹²⁵I-labeled αMSH analogues for imaging with single-photon emission computed tomography; ⁶⁸Ga-, ⁶⁴Cu-, or ¹⁸F-labeled αMSH analogues for imaging with positron emission tomography; and ¹⁸⁸Re-, ¹⁷⁷Lu-, ⁹⁰Y-, or ²¹²Pb-labeled αMSH analogues for radionuclide therapy. These radiolabeled αMSH analogues showed promising results with high tumor uptake and rapid normal tissue activity clearance in the preclinical model of B16F1 and B16F10 mouse melanomas. These results highlight the potential of using radiolabeled αMSH analogues in clinical applications for molecular imaging and radionuclide therapy of melanoma.

Staging Uveal Melanoma with Whole-Body Positron-Emission Tomography/Computed Tomography and Abdominal Ultrasound: Low Incidence of Metastatic Disease, High Incidence of Second Primary Cancers

PURPOSE:

The purpose of this study was to report the results of staging primary uveal melanoma with whole-body (18) fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) and abdominal ultrasound.

MATERIALS AND METHODS:

From January 2012, patients with uveal melanoma over 4 mm in thickness were staged with FDG PET/CT and abdominal ultrasound.

RESULTS:

Over 2 years, 108 patients with medium-to-large melanoma underwent dual imaging. According to the tumor, node, and metastasis classification, there were 75% T3, 11% T2, and 14% T1 uveal melanomas. Only, three of 108 patients (2.8%) were found to have metastatic uveal melanoma. All three had liver metastases confirmed following biopsy; one of three had additional extrahepatic widespread metastases. In these three patients, liver findings using both imaging techniques were consistent in one patient. In the second case, abdominal ultrasound missed the diagnosis of metastatic disease; however, FDG PET/CT revealed intense metabolic activity of the liver. In the third case, PET/CT missed the liver metastases; however, this was identified on abdominal ultrasound. PET/CT identified incidental second primary malignancies in 10 patients (9%). Second malignancies were found in the lung, breast, colon, thyroid, and adrenal gland. Abdominal ultrasound detected benign hepatic abnormalities in 20 patients (18%).

CONCLUSIONS:

Whole-body PET/CT and abdominal ultrasound complement each other in the staging of uveal melanoma. Benign hepatic abnormalities found using ultrasound is common. Of importance, a second asymptomatic primary malignancy associated with uveal melanoma was detected almost one in 10 patients.

Melanoma Imaging Using 18F-Labeled α-Melanocyte-Stimulating Hormone Derivatives with Positron Emission Tomography

Melanocortin 1 receptor (MC1R) is specifically expressed in the majority of melanomas, a leading cause of death related to skin cancers. Accurate staging and early detection is crucial in managing melanoma. Based on the α-melanocyte-stimulating hormone (αMSH) sequence, MC1R-targeted peptides have been studied for melanoma imaging, predominately for use with single-photon emission computed tomography, with few attempts made for positron emission tomography (PET). ¹⁸F is a commonly used PET isotope due to readily available cyclotron production, pure positron emission, and a favorable half-life (109.8 min). In this study, we aim to design and evaluate αMSH derivatives that enable radiolabeling with ¹⁸F for PET imaging of melanoma. We synthesized three imaging probes based on the structure of Nle⁴-cyclo[Asp⁵-His-d-Phe⁷-Arg-Trp-Lys¹⁰]-NH₂ (Nle-CycMSH_hex), with a Pip linker (CCZ01064), an Acp linker (CCZ01070), or an Aoc linker (CCZ01071). ¹⁸F labeling was enabled by an ammoniomethyl-trifluoroborate (AmBF₃) moiety. In vitro competition binding assays showed subnanomolar inhibition constant ( K_i) values for all three peptides. The ¹⁸F radiolabeling was performed via a one-step ¹⁸F-¹⁹F isotope exchange reaction that resulted in high radiochemical purity (>95%) and good molar activity (specific activity) ranging from 40.7 to 66.6 MBq/nmol. All three ¹⁸F-labeled peptides produced excellent tumor visualization with PET imaging in C57BL/6J mice bearing B16-F10 tumors. The tumor uptake was 7.80 ± 1.77, 5.27 ± 2.38, and 5.46 ± 2.64% injected dose per gram of tissue (%ID/g) for [¹⁸F]CCZ01064, [¹⁸F]CCZ01070, and [¹⁸F]CCZ01071 at 1 h post-injection (p.i.), respectively. Minimal background activity was observed except for kidneys at 4.99 ± 0.20, 4.42 ± 0.54, and 13.55 ± 2.84%ID/g, respectively. The best candidate [¹⁸F]CCZ01064 was further evaluated at 2 h p.i., which showed increased tumor uptake at 11.96 ± 2.31%ID/g and further reduced normal tissue uptake. Moreover, a blocking study was performed for CCZ01064 at 1 h p.i., where tumor uptake was significantly reduced to 1.97 ± 0.60%ID/g, suggesting the tumor uptake was receptor mediated. In conclusion, [¹⁸F]CCZ01064 showed high tumor uptake, low normal tissue uptake, and fast clearance and is therefore a suitable and promising candidate for PET imaging of melanoma.

Dynamic contrast-enhanced MRI coupled with a subtraction technique is useful for treatment response evaluation of malignant melanoma hepatic metastasis

PURPOSE

To determine whether contrast-enhanced MRI including subtraction sequences can predict the treatment response of melanoma liver metastasis.

RESULTS

High precontrast T1 signal intensity (SI) of melanoma lesions obscured detection of enhancement after contrast injection. It was impossible to determine whether or not enhancement occurred in the majority of lesions (85.4%, n = 35/41) without including the subtraction technique. Positive enhancement was identified in 14.6% (n = 6/41) of patients without subtraction images, but increased to 68.3% (n = 28/41) by including subtraction images. Follow-up studies determined lesion progression in 34.1% (n = 14/41) of patients. Positive enhancement on the subtraction image (odds ratio = 12.1, P = 0.048) and intermediate high T2 SI (odds ratio = 8.16, P = 0.040) were significantly associated with higher risk of lesion progression.

MATERIALS AND METHODS

Patients who underwent MRI for melanoma liver metastases between January 2007 and February 2015 were enrolled. The study analyzed 41 liver metastases in 15 patients [11 male and four female; median age 56 years (range 21-81)] for size, lesion enhancement with and without subtraction images, and T2 SI. Follow-up imaging studies were used to determine treatment response. Data were analyzed with generalized estimating equations.

CONCLUSIONS

MRI including the subtraction technique is useful for determining the treatment response of melanoma liver metastases. Lesion contrast enhancement and intermediate high T2 SI increased the risk of lesion progression.

Preclinical Melanoma Imaging with 68Ga-Labeled α-Melanocyte-Stimulating Hormone Derivatives Using PET

It is estimated that melanoma accounted for 76,380 new cases and 10,130 deaths in the United States in 2016. The melanocortin 1 receptor (MC1R) is highly expressed in the vast majority of melanomas, which makes it an attractive target for molecular imaging and radionuclide therapy. Lactam bridge-cyclized α-melanocyte-stimulating hormone (Ac-Nle⁴-cyclo[Asp⁵-His-D-Phe⁷-Arg-Trp-Lys¹⁰]-NH₂, or Nle-CycMSH_hex) analogues have been successfully developed and studied for MC1R-targeted imaging, predominantly with single-photon emission computed tomography (SPECT). The goal of this study was to design and evaluate novel peptides for melanoma imaging with positron emission tomography (PET). We designed and synthesized three peptides, DOTA-PEG₂-Nle-CycMSH_hex (CCZ01047), DOTA-4-amino-(1-carboxymethyl) piperidine (Pip)-Nle-CycMSH_hex (CCZ01048), and DOTA-Pip-Pip-Nle-CycMSH_hex (CCZ01056). All three peptides exhibited high binding affinity to MC1R with sub-nanomolar K_i values, rapid internalization into B16F10 melanoma cells and high in vivo stability with more than 93% remaining intact at 15 min post-injection (p.i.) in blood plasma. All three ⁶⁸Ga-labeled tracers produced high contrast PET images in C57BL/6J mice bearing B16F10 tumors, and their respective tumor uptakes were 8.0 ± 3.0, 12.3 ± 3.3, and 6.5 ± 1.4 %ID/g at 1 h p.i. Minimal normal organ activity was observed at 1 h p.i., except for kidneys (5.1 ± 1.4, 4.7 ± 0.5, and 6.2 ± 2.0 %ID/g, respectively), and thyroid (4.1 ± 0.6 %ID/g for CCZ01047 and 2.4 ± 0.6 %ID/g for CCZ01048). Due to high accumulation at tumor sites and rapid background clearance of ⁶⁸Ga-CCZ01048, we further evaluated it at 2 h p.i., and a tumor uptake of 21.9 ± 4.6 %ID/g was observed, with background activity further decreased. Exceptional image contrast was also achieved, i.e. tumor-to-blood, tumor-to-muscle, tumor-to-bone and tumor-to-kidney ratios were 96.4 ± 13.9, 210.9 ± 20.9, 39.6 ± 11.9 and 4.0 ± 0.9, respectively. A blocking study was also performed by co-injection of excess amount of non-radioactive Ga-coupled of CCZ01048, which confirmed that the tumor uptake was MC1R mediated. In conclusion, the introduction of a cationic Pip linker to Nle-CycMSH_hex, CCZ01048, not only improved tumor uptake, but also generated high tumor-to-normal tissue contrast with PET imaging in a preclinical melanoma model. Therefore, CCZ01048 is a promising candidate for PET imaging of melanoma, and potentially as a theranostic agent for radionuclide therapy of melanoma when labeled with α or β emitters.

Dual-energy CT of liver metastases in patients with uveal melanoma

Objective

To investigate the value of different kVp images of dual-energy CT (DECT) for the detection of liver metastases.

Methods

20 Patients with uveal melanoma were investigated with DECT of the liver. In each patient contrast-enhanced DECT imaging with arterial delay was performed. Number and size of metastases were documented on arterial phase 80-kVp images, virtual 120-kVp images and following angiographic images (DSA) as part of hepatic chemoperfusion. Attenuation of metastases and several anatomic regions, subjective (image noise, image quality) and objective (SNR, CNR) parameters were documented.

Results

The mean number of liver metastases detected was significant higher on 80-kVp images than on virtual 120-kVp/DSA images (5.6 ± 2.1 vs. 4.1 ± 1.8/4.3 ± 1.6); (p < 0.001). All lesions sizes were significant better detected with 80 kVp images than with virtual 120 kVp and DSA-Images (80 kVp vs. 120 kVp: <10 mm: 34 vs. 19, p < 0.05; 10–20 mm:, 33 vs. 25, p < 0.05; >20 mm: 56 vs. 42, p < 0.05/80 kVp vs. DSA: <10 mm: 34 vs. 18 p < 0.05; 10–20 mm: 33 vs. 24, p < 0.05; >20 mm: 56 vs. 41, p < 0.05). Number of detected small lesions <10 mm with 120 kVp compared to DSA-images were significant higher (19 vs. 13; p < 0.05), lesions 10–20 mm and >20 mm were measured statistically equally. Noise, SNR and CNR of 80 kVp images were higher compared to 120 kVp images. Image quality of 120 kVp images was higher compared to 80 kVp images.

Conclusion

Low-kVp images of DECT datasets are more sensitive in detecting liver metastases of patients with uveal melanoma than virtual 120 kVp- and DSA images.

Uveal Melanoma: Current Trends in Diagnosis and Management

Uveal melanoma, which is the most common primary intraocular malignancy in adults, arises from melanocytes within the iris, ciliary body and choroid. The diagnosis is based principally on clinical examination of the tumor with biomicroscopy and indirect ophthalmoscopy and confirmed by diagnostic techniques such as ultrasonography, fundus fluorescein angiography and optical coherence tomography. The clinical diagnosis of posterior uveal melanomas can be made when the classical appearance of a pigmented dome-shaped mass is detected on dilated fundus exam. Uveal melanomas classically show low to medium reflectivity on A-scan ultrasonography and on B-scan ultrasonography the tumor appears as a hyperechoic, acoustically hollow intraocular mass. Management of a suspicious pigmented lesion is determined by its risk factors of transforming into a choroidal melanoma, such as documentation of growth, thickness greater than 2 mm, presence of subretinal fluid, symptoms and orange pigment, margin within 3 mm of the optic disc, and absence of halo and drusen. Advances in the diagnosis and local and systemic treatment of uveal melanoma have caused a shift from enucleation to eye-conserving treatment modalities including transpupillary thermotherapy and radiotherapy over the past few decades. Prognosis can be most accurately predicted by genetic profiling of fine needle aspiration biopsy of the tumor before the treatment, and high-risk patients can now be identified for clinical trials that may lead to target-based therapies for metastatic disease and adjuvant therapy which aims to prevent metastatic disease.

Imaging of ocular melanoma metastasis

Ocular melanoma is the most common adult primary intraocular tumour. Although <1% of patients have metastatic disease at the time of initial diagnosis, most will develop metastasis at varying lengths of time. Metastasis surveillance is therefore critical in the follow-up of patients with ocular melanoma. Liver is the most common site of metastasis and prognosis is based on the treatment of liver metastasis. Hence, imaging of liver metastasis is vital. MRI is the most specific modality for imaging liver metastasis and is at least as sensitive as CT. Extrahepatic metastasis such as retroperitoneal nodules and bone metastases are also better evaluated on MRI. Gadolinium-based contrast agents are extremely helpful for detecting liver lesions. In particular, newer hepatobiliary contrast agents which offer an additional hepatobiliary phase of excretion help in the detection of even tiny liver metastases. Diffusion-weighted imaging is helpful when an i.v. contrast cannot be administered. Treated lesions are also better evaluated with MRI. CT is useful for evaluating lung nodules, large liver metastasis or in patients in whom MRI is medically contraindicated. The disadvantage lies in its inability to detect small liver metastasis and the radiation dose involved. The lesions treated with iodized oil as part of chemoembolization procedures can be followed on CT. Ultrasound can be used only for detecting hepatic metastases. However, it is heavily operator dependent, technically challenging and time consuming especially in patients who are large. Extrahepatic metastasis cannot be seen on ultrasound. Its utility is primarily for the biopsy of liver lesions. Positron emission tomography (PET)-CT can detect lung nodules and large liver lesions but is insensitive to small liver lesions. Moreover, the high radiation dose is a major disadvantage.

Prospective study of surveillance testing for metastasis in 100 high-risk uveal melanoma patients

Despite advances in the local treatment of UM, half of patients develop metastases typically to the liver with poor survival. Microscopic complete surgical resection (R0) of liver metastases improves survival in high selected patients. Early identification of high-risk patients might allow detection of asymptomatic metastases, and increase R0 liver surgery rate. From October 2006 to December 2009, we conducted a prospective study to detect early minimal lesions with 6-monthly liver function tests (LFTs) and liver MRI in 100 high-risk patients. High risk was defined by primary tumor clinical or genomic criteria: thickness>8mm or diameter>15 mm, or extra-scleral extension, or monosomy 3 by FISH or aCGH. With a median follow-up of 49 months, the 5-year metastasis-free survival and overall survival were 47 and 33%, respectively. Of the 60 patients who became metastatic, 50 (83%) had exclusive liver metastasis. LFTs screening had no sufficient accurary, but biannual MRI showed high predictive value to detect metastasis and select patients eligible for curative surgery: 25/50 underwent laparotomy and among them, 8/25 (32%) had a R0 surgery. Median survival after metastasis was 14 months, mean survival reached 40 months in the R0 resected population. Six-monthly liver MRI screening is recommended in patients with large tumors or genomic high risk in order to detect early patient candidates to complete resection of liver metastases.

PET/CT, MR, and PET/MR in Lymphoma and Melanoma

With the introduction of hybrid imaging technologies such as PET/CT and recently PET/MRI, staging and therapy-response monitoring have evolved. PET/CT has been shown to be of value for routine staging of FDG-avid lymphomas before as well as at the end of treatment. For interim staging, trials are ongoing to evaluate the use of PET/CT. In melanoma, PET/CT can be recommended for stages III and IV diseases for initial staging and before surgery. Studies investigating the use of PET/CT for early therapy response are promising. The role of PET/MR in lymphoma and melanoma imaging has to be defined because no larger studies exist so far. There may be an application of PET/MR in research especially for tumor characterization and therapy response. Furthermore, the potential role of non-FDG tracers is elucidated regarding the assessment of treatment response in targeted drug regimens.

Management of uveal melanoma: a consensus-based provincial clinical practice guideline

INTRODUCTION

Survival in uveal melanoma has remained unchanged since the early 1970s. Because outcomes are highly related to the size of the tumour, timely and accurate diagnosis can increase the chance for cure.

METHODS

A consensus-based guideline was developed to inform practitioners. PubMed was searched for publications related to this topic. Reference lists of key publications were hand-searched. The National Guidelines Clearinghouse and individual guideline organizations were searched for relevant guidelines. Consensus discussions by a group of content experts from medical, radiation, and surgical oncology were used to formulate the recommendations.

RESULTS

Eighty-four publications, including five existing guidelines, formed the evidence base.

SUMMARY

Key recommendations highlight that, for uveal melanoma and its indeterminate melanocytic lesions in the uveal tract, management is complex and requires experienced specialists with training in ophthalmologic oncology. Staging examinations include serum and radiologic investigations. Large lesions are still most often treated with enucleation, and yet radiotherapy is the most common treatment for tumours that qualify. Adjuvant therapy has yet to demonstrate efficacy in reducing the risk of metastasis, and no systemic therapy clearly improves outcomes in metastatic disease. Where available, enrolment in clinical trials is encouraged for patients with metastatic disease. Highly selected patients might benefit from surgical resection of liver metastases.

Liver metastases from non-gastrointestinal non-neuroendocrine tumours: review of the literature

Liver resection is integrated in the oncological surgical management of metastatic gastrointestinal and neuroendocrine tumours. However, the good prognosis reached in these cases has not been obtained for metastatic tumours of other histological types. In this review, we analysed the published case reports and series of hepatectomies in patients with metastatic breast cancer, melanoma, sarcoma, genitourinary tumours, pulmonary and adrenocortical tumours. From the reported data the surgical resection of oligometastases yields good results in terms of improved survival, in particular when the disease-free time period is longer than 1 year. Hepatic resection can be a valid surgical strategy to obtain a survival benefit in patients with liver metastases from non-gastrointestinal, non-neuroendocrine tumours. However, a careful patient selection is needed in order to obtain a real survival benefit; patients with a good performance status, with a disease-free period longer than 1 year and with oligometastases may obtain the best advantage from this approach.

Multi-modal acousto-optic/ultrasound imaging of ex vivo liver tumors at 790 nm using a Sn2 P2 S6 wavefront adaptive holographic setup

Biological tissues are very strong light-scattering media. As a consequence, current medical imaging devices do not allow deep optical imaging unless invasive techniques are used. Acousto-optic imaging is a light-ultrasound coupling technique that takes advantage of the ballistic propagation of ultrasound in biological tissues to access optical contrast with a millimeter resolution. We have developed a photorefractive-crystal-based system that performs self-adaptive wavefront holography and works within the optical therapeutic window. As it works at an appropriate wavelength range for biological tissues imaging, it was tested on ex vivo liver samples containing tumors as a pre-clinical study. Optical contrast was obtained even if acoustical one was not significant. Ultrasound image (left) and acousto-optic image (right) of a liver biopsy with tumors. Acousto-optic imaging exhibits tumors that are not detected through ultrasound.

Initial Experience of Utilizing Real-Time Intra-Procedural PET/CT Biopsy

OBJECTIVES

Nonreal-time Positron Emission Tomography/Computed Tomography (PET/CT) biopsies that use the image co-registration of a prior PET with an intra-procedural CT have been reported. The aim of this study was to report the initial experience of performing real-time intra-procedural PET/CT-guided biopsies.

MATERIALS AND METHODS

All patients (n = 4) had a prior PET/CT examination of the concerning lesion and no significant CT correlate. On the day of the biopsy, 5 mCi of 18F-fluorodeoxyglucose (FDG) or NaF18 was intravenously injected. After 60 min of biodistribution of the molecular probe, PET/CT images were obtained in a limited one bed position over the region of the concerning lesion to be biopsied.

RESULTS

One patient had a mesenteric mass and the other three had bone lesions, one located in the rib and two in the iliac bone. The pathology report revealed that two lesions (50%) were malignant and two lesions (50%) were benign. The results of the biopsy changed management in all cases. There was 0% complication rate.

CONCLUSIONS

No additional software or hardware is required to perform real-time intra-procedural PET/CT-guided biopsies. It can optimize the yield, especially in cases where there are no anatomical abnormalities. Real-time intra-procedural PET/CT biopsy may have benefits over conventional biopsy techniques in terms of accuracy.

[18F]Fluorodeoxyglucose PET for Interventional Oncology in Liver Malignancy

[(18)F]Fluorodeoxyglucose (FDG) PET is a functional imaging tool that provides metabolic information, which has the potential to detect a lesion before it becomes anatomically apparent. This ability constitutes a strong argument for using FDG-PET/computed tomography (CT) in the management of oncology patients. Many studies have investigated the accuracy of FDG-PET or FDG-PET/CT for these purposes, but with small sample sizes based on retrospective cohorts. This article provides an overview of the role of FDG-PET or FDG-PET/CT in patients with liver malignancies treated by means of surgical resection, ablative therapy, chemoembolization, radioembolization, and brachytherapy, all being liver-directed oncologic interventions.

The Liverpool uveal melanoma liver metastases pathway: outcome following liver resection

AIM

To determine the outcome of patients that underwent liver resection for metastases from uveal melanoma.

METHODS

Over a 9-year period, patients referred with uveal melanoma metastases were included. Following treatment of primary uveal melanoma, high-risk patients were offered to be enrolled into a 6-monthly non-contrast liver magnetic resonance imaging (MRI) surveillance. Following detection of liver metastases, patients were staged with a contrast-enhanced (Primovist(®)) liver MRI, computer tomography (CT) of the thorax and staging laparoscopy.

RESULTS

155 patients were referred with uveal melanoma liver metastases, of which 17 (11.0%) patients had liver resection and one patient was treated with percutaneous radio-frequency ablation. The majority of patients undergoing liver resection were treated with multiple metastectomies (n = 8) and three patients had major liver resections. The overall median survival for patients treated with surgery/ablation was 27 (14-90) months, and this was significantly better compared to patients treated palliatively [median = 8(1-30) months, P < 0.001]. Following surgery, 11 patients had recurrent disease [median = 13(6-36) months]. Patients who had undergone a major liver resection had a significantly poorer disease-free survival (P = 0.037).

CONCLUSIONS

Patients who can undergo surgical resection for metastatic uveal melanoma have a more favorable survival compared to those who do not.

Clinical, pathologic, and imaging features and biological markers of uveal melanoma

Uveal melanoma has unique clinical and pathologic features including virtually exclusive metastasis to the liver in high-risk cases. In this chapter, the clinical findings in uveal melanoma and diagnostic methods including imaging tests and serum markers are described. Additionally, the histopathologic features including the modified Callender classification and immunohistochemical findings of uveal melanoma are described.

Imaging-guided biopsy of (18)F-FDG-avid extrapulmonary lesions: do lesion location and morphologic features on CT affect the positive predictive value for malignancy?

OBJECTIVE

The purpose of our study was to analyze the effect of lesion location and morphologic appearance on CT on the positive predictive value (PPV) for malignancy of all extrapulmonary lesions that were (18)F-FDG avid on PET/CT and that were biopsied under imaging guidance.

MATERIALS AND METHODS

Between January 2004 and December 2010, 227 patients underwent imaging-guided biopsy of 231 PET-positive extrapulmonary lesions with diagnostic pathologic results. The PET PPV for malignancy was retrospectively calculated and stratified according to lesion location and morphologic appearance.

RESULTS

The overall PET PPV for malignancy was 72%. Inflammatory processes accounted for the majority of benign biopsy results. Lesion location significantly affected the PPV (p < 0.001). Bone (96%) and liver (90%) lesions had significantly higher PPVs for malignancy compared with other locations, whereas lymph nodes (60%) had a significantly lower PPV for malignancy. Lesions that were morphologically suspicious and morphologically benign according to CT findings alone were associated with PPVs of 74% and 57%, respectively (p = 0.05). FDG-avid subcentimeter lymph nodes (n = 8) had a PPV for malignancy of 38%.

CONCLUSION

Over half of PET-avid morphologically benign-appearing lesions and one third of PET-avid subcentimeter lymph nodes were found to be malignant at biopsy, suggesting that benign morphologic appearance alone should not preclude further workup of a PET-positive lesion. Biopsies of FDG-avid lesions in liver and bone yielded high rates of true malignancy, whereas biopsies of lymph nodes yielded a lower rate of malignancy compared with other lesion locations.

Clinicopathological correlation for the role of fluorodeoxyglucose positron emission tomography computed tomography in detection of choroidal malignant melanoma

BACKGROUND

The purpose of this study was to redefine the role of whole-body 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography fused with computed tomography (PET/CT) in the clinical diagnosis of choroidal malignant melanoma.

METHODS

The study design was a retrospective case series involving 7 consecutive patients with choroidal malignant melanoma who underwent enucleation to reach the final pathological diagnosis. FDG-PET/CT was performed together with magnetic resonance imaging and ophthalmological examinations before the surgery. The area, thickness, longest diameter, and circumference of the tumor mass were measured on pathological sections, and were correlated with maximum standardized uptake values (SUVmax) of the tumors on FDG-PET/CT.

RESULTS

Abnormally high uptake of FDG was noted in the affected eyes of 5 patients, but not in the eyes of 2 patients. The 5 patients with high uptake showed nodular tumors extruding into the vitreous cavity while the 2 patients with absence of uptake showed diffusely infiltrating tumors in the wide area of the choroid with or without a small mushroom-like protrusion. One patient with diffuse infiltration showed concurrent liver metastases with high uptake on PET/CT while another patient with a nodular tumor developed liver metastases a year later. The tumors with higher SUVmax had a tendency to have a wider area and greater thickness on pathological sections (ρ = 0.775, P = 0.0557, Spearman rank correlation test).

CONCLUSIONS

FDG-PET/CT showed correlation of the uptake with tumor sizes but was limited in detecting diffusely infiltrating tumors in the choroid without nodular formation.

Progress in the management of patients with uveal melanoma. The 2012 Ashton Lecture

Uveal melanomas are diverse in their clinical features and behaviour. More than 90% involve the choroid, the remainder being confined to the ciliary body and iris. Most patients experience visual loss and more than a third require enucleation, in some cases because of pain. Diagnosis is based on slit-lamp biomicroscopy and/or ophthalmoscopy, with ultrasonography, autofluorescence photography, and/or biopsy in selected cases. Conservation of the eye with useful vision has improved with advances in brachytherapy, proton beam radiotherapy, endoresection, exoresection, transpupillary thermotherapy, and photodynamic therapy. Despite ocular treatment, almost 50% of patients develop metastatic disease, which occurs almost exclusively in patients whose tumour shows chromosome 3 loss and/or class 2 gene expression profile. When the tumour shows such lethal genetic changes, the survival time depends on the anatomical stage and the histological grade of malignancy. Prognostication has improved as a result of progress in multivariate analysis including all the major risk factors. Screening for metastases is more sensitive as a consequence of advances in liver scanning with magnetic resonance imaging and other methods. More patients with metastases are living longer, benefiting from therapies such as: partial hepatectomy; radiofrequency ablation; ipilumumab immunotherapy; selective internal radiotherapy; intra-hepatic chemotherapy, possibly with isolated liver perfusion; and systemic chemotherapy. There is scope for improvement in the detection of uveal melanoma so as to maximise any opportunities for conserving the eye and vision, as well as preventing metastatic spread. Patient management has been enhanced by the formation of multidisciplinary teams in specialised ocular oncology centres.

(18)F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging in patients with liver metastases from uveal melanoma: results from a pilot study

PURPOSE

(18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and MRI are used for detecting liver metastases from uveal melanoma. The introduction of new treatment options in clinical trials might benefit from early response assessment. Here, we determine the value of FDG-PET/CT with respect to MRI at diagnosis and its potential for monitoring therapy.

MATERIAL AND METHODS

Ten patients with biopsy-proven liver metastases of uveal melanoma enrolled in a randomized phase III trial (NCT00110123) underwent both FDG-PET coupled with unenhanced CT and gadolinium-diethylene triamine pentaacetic acid-enhanced liver MRI within 4 weeks. FDG-PET and MRI were evaluated blindly and then compared using the ratio of lesion to normal liver parenchyma PET-derived standardized uptake value (SUV). The influence of lesion size and response to chemotherapy were studied.

RESULTS

Overall, 108 liver lesions were seen: 34 (31%) on both modalities (1-18 lesions/patient), four (4%) by PET/CT only, and 70 (65%) by MRI only. SUV correlated with MRI lesion size (r=0.81, P<0.0001). PET/CT detected 26 of 33 (79%) MRI lesions of more than or equal to 1.2 cm, whereas it detected only eight of 71 (11%) lesions of less than 1.2 cm (P<0.0001). MRI lesions without PET correspondence were small (0.6±0.2 vs. 2.1±1.1 cm, P<0.0001). During follow-up (six patients, 30 lesions), the ratio lesion-to-normal-liver SUV diminished in size-stable lesions (1.90±0.64-1.46±0.50, P<0.0001), whereas it increased in enlarging lesions (1.56±0.40-1.99±0.56, P=0.032).

CONCLUSION

MRI outweighs PET/CT for detecting small liver metastases. However, PET/CT detected at least one liver metastasis per patient and changes in FDG uptake not related to size change, suggesting a role in assessing early therapy response.

Whole-body F-18-fluoro-2-deoxyglucose positron emission tomography/computed tomography imaging in the follow-up of metastatic uveal melanoma

Metastasis has been reported in the follow-up of up to 50% of uveal melanoma patients. Established oncological diagnostic modalities in tumor follow-up so far have limited sensitivity and specificity. The diagnostic value of combined positron emission tomography (PET)/computed tomography (CT) scans in the follow-up of patients with metastatic uveal melanoma was assessed. Eleven patients with successfully treated and one patient with suspected uveal melanoma underwent combined PET/CT scan. The indication for PET/CT scan was heterogenous and ranged from suspected metastatic choroidal melanoma in conventional imaging (n=3) to exclusion of further organ involvement before local therapy of liver metastases (n=5) and restaging after local or systemic therapy of metastases (n=4). PET/CT scan showed vital metastases from uveal melanoma in all patients (n=12). Ten patients showed vital hepatic metastases (83%), five osseous (42%), four lymphatic (33%), two pulmonary (17%), one adrenal (8%) and one had muscular metastases (8%). Six patients showed multiple organ involvement (50%). In addition, PET/CT scan correctly identified a primary intraocular tumor and ruled out pulmonary metastatic involvement with suspicious intrapulmonary findings in a CT scan and chest X-ray in two patients. It could also confirm an equivocal intrahepatic finding in an MRI scan as a vital metastasis. PET/CT scan is a very sensitive and specific tool for the detection and localization of metastatic disease in patients with uveal melanoma, assessing both anatomical morphology and cell metabolism in one single examination. With novel therapeutic approaches in evolution, PET/CT scanning can be of great importance for therapy planning and monitoring.