Evaluation of 18F-FDG PET/CT Parameters for Detection of Lymph Node Metastasis in Cutaneous Melanoma

Diagnostic Performance of [18F]F-FDG Positron Emission Tomography (PET) in Non-Ophthalmic Malignant Melanoma: A Systematic Review and Meta-Analysis of More Than 10,000 Melanoma Patients

We described the diagnostic performance of [18F]F-FDG-PET in malignant melanoma by conducting a comprehensive systematic review and meta-analysis of the existing literature. The study was designed following PRISMA-DTA. Original articles with adequate crude data for meta-analytic calculations that evaluated [18F]F-FDG-PET and compared it with a valid reference standard were considered eligible. The pooled measurements were calculated based on the data level (patient/lesion-based). Regarding sub-groups, diagnostic performances were calculated for local, regional and distant involvement. The bivariate model was employed to calculate sensitivity and specificity. The initial search resulted in 6678 studies. Finally, 100 entered the meta-analysis, containing 82 patient-based (10,403 patients) and 32 lesion-based (6188 lesions) datasets. At patient level, overall, [18F]F-FDG-PET had pooled sensitivity and specificity of 81% (95%CI: 73-87%) and 92% (95%CI: 90-94%), respectively. To detect regional lymph node metastasis, the pooled sensitivity and specificity were 56% (95%CI: 40-72%) and 97% (95%CI: 94-99%), respectively. To detect distant metastasis, they were 88% (95%CI: 81-93%) and 94% (95%CI: 91-96%), respectively. At lesion level, [18F]F-FDG-PET had a pooled sensitivity and specificity of 70% (95%CI: 57-80%) and 94% (95%CI: 88-97%), respectively. Thus, [18F]F-FDG-PET is a valuable diagnostic modality for melanoma assessment. It was accurate in various clinical scenarios. However, despite its high specificity, it showed low sensitivity in detecting regional lymph node metastasis and could not replace lymph node biopsy.

Nivolumab-induced systemic lymphadenopathy occurring during treatment of malignant melanoma: a case report

Nivolumab is an anti-programmed cell death protein 1 monoclonal antibody that exhibits significant efficacy in treating melanoma and other malignancies. However, various nivolumab-induced immune-related adverse events (irAEs) have been reported, and differentiating irAEs from tumor progression is sometimes difficult. Here, we report a case of reactive lymphadenopathy occurring after treatment with nivolumab. A 56-year-old man with stage IIIC melanoma received adjuvant therapy with nivolumab after wide local excision. He developed systemic lymphadenopathy and autoimmune hemolytic anemia 1 month after receiving seven cycles of nivolumab. Pathological analysis of a cervical lymph node biopsy specimen revealed no metastatic lesion or any other malignancy, including lymphoma. Thus, the patient was diagnosed with nivolumab-induced reactive lymphadenopathy. Systemic corticosteroids were administered to reduce hemolysis, which led to the resolution of lymphadenopathy. When progressive lymphadenopathy is observed in a patient who received immune checkpoint inhibitor therapy, reactive lymphadenopathy should be carefully distinguished from progression to lymphoid metastasis, and biopsy should be performed if needed.

Interference of COVID-19 Vaccination With PET/CT Leads to Unnecessary Additional Imaging in a Patient With Metastatic Cutaneous Melanoma-Case Report

The COVID-19 pandemic has widely influenced oncological imaging mainly by presenting unexpected pulmonary and mediastinal lesions. The ongoing global program of vaccination has led to incidental diagnosis of axillary lymphadenopathy. We present a case of increased accumulation of ¹⁸F-FDG in an axillary lymph node in a PET/CT scan performed in a 43-year-old female patient with metastatic melanoma. The scan was performed 4 days after the AZD1222 vaccination. The occurrence of lymphadenopathy was verified with another PET/CT scan scheduled one month later. This case report presents a possible misinterpretation of PET/CT images caused by the recent COVID-19 vaccination. To avoid distress of the patient and unnecessary oncological diagnostics to verify the findings, we recommend avoiding scheduling PET/CT shortly after vaccination.

Visceral hepatic leishmaniasis in a melanoma patient in FDG-PET

BACKGROUND

Leishmaniasis is caused by protozoans that depend on female phlebotomine sandflies as vectors. The natural habitat of these sandflies is changing due to climate change. More patients will get immunocompromised due to cancer therapy.

CASE REPORT

We report the case of a 72-year-old patient with melanoma in whom we found visceral leishmaniasis mimicking hepatic metastasis in routine FDG-PET/CT. The patient was hospitalized due to fever and pancytopenia in the general hospital Steyr. The diagnosis was made by biopsy of the iliac crest with cytological study and polymerase chain reaction. After treatment with amphotericin B, the patient recovered, and tests became negative, including FDG-PET/CT. Because of climate change and the increasing use of immunomodulatory medication, our awareness of such findings should grow.

CONCLUSION

New pitfalls in diagnosis and surveillance of cancer patients because of altered environmental conditions and immunocompromised patients have to be considered.

Practical Considerations When Interpreting FDG PET/CT Imaging for Staging and Treatment Response Assessment in Melanoma Patients

While FDG PET/CT bears a high sensitivity and specificity for the staging of stage III and IV melanoma as well as for the purpose of melanoma recurrence detection, overall results tend to vary from one part of the body to another as well as for melanoma from cutaneous or choroidal origin. In this paper, organ or site-related differences in sensitivity and specificity in melanoma patients, both from cutaneous and choroidal origin, as well as their impact on clinical decision making are discussed. Furthermore, with the advent of immunotherapy for the treatment of malignant melanoma, post-treatment related potential false positive findings have emerged, the knowledge of which is essential for accurate treatment response assessment. These post-treatment related potential false positive findings are summarized in this paper so as to help the nuclear medicine physician in avoiding erroneous interpretation of acquired FDG PET/CT images in melanoma patients receiving immuntherapy.

Predictive value of FDG-PET imaging for relapse in metastatic melanoma patients treated with immunotherapy

BACKGROUND

Anti-PD1 immunotherapy has shown a sustainable clinical activity in patients with metastatic melanoma. However, strong predictive factors of the long-term response or risk of relapse remain to be identified.

OBJECTIVES

To determine whether FDG-PET imaging could be superior to CT scan in distinguishing residual tumours versus the absence of tumour in patients with a partial response (PR) or stable disease (SD) and whether a complete metabolic response (CMR) was associated with better outcomes.

METHODS

Retrospective study conducted in all patients with metastatic melanoma treated with anti-PD1 immunotherapy between October 2014 and October 2017 considered to be in complete remission. The primary outcome was the occurrence of a relapse during the follow-up. CT scan and FDG-PET scan had to be performed within a maximum of 2 months of treatment discontinuation. For CT imaging, the Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 were used and included progressive disease (PD), SD, PR and complete response (CR). For FDG-PET imaging, the metabolic responses were classified as progressive metabolic disease, stable metabolic disease, residual FDG avidity (RFA) and CMR.

RESULTS

Twenty-six patients were in complete remission after collegial decision. Two patients had a SD on CT scan and a CMR on FDG-PET scan, and none of them relapsed. Ten patients had a PR on CT scan and a CMR on FDG-PET scan, and none of them relapsed. The mean treatment duration to achieve a complete remission was 7 months (3-23). A univariate analysis showed that a RFA assessed on the FDG-PET scan was significantly associated with a relapse (P = 0.00231).

CONCLUSIONS

Most patients with a PR on the CT scan and a CMR on the FDG-PET scan should be considered with a CR. Our study showed that FDG-PET imaging could play a crucial role in predicting the long-term outcome and help to decide whether treatment should be discontinued.

Efficacy of positron emission tomography and computed tomography in clinical staging of cutaneous malignant melanoma

Accurate staging is very important for determining the prognosis and appropriate treatment for malignant melanoma (MM). The aim of this study is to determine the effectiveness of positron emission tomography and computed tomography (PET/CT) imaging in staging MM. Patients diagnosed with MM who then underwent PET/CT metastasis before treatment were assessed retrospectively. For each patient, the following variables were recorded: Breslow thickness, Clark's level, number of mitoses, the presence of ulceration detected in the pathology report, and the presence of lymph nodes and/or distant metastases detected by PET/CT. The pathology and PET/CT reports of 139 patients (79 female and 60 male) were retrospectively evaluated for staging after MM diagnosis. Patients with a Breslow thickness greater than 3.4 mm and Clark's level of 4 to 5 were found to be statistically significantly higher with regional lymph node metastasis after PET/CT scans. Patients with Breslow thickness greater than 2.85 mm and Clark's level of 4 to 5 were found to be statistically significantly higher with distant metastasis after PET/CT scan. The results of our study suggest that PET/CT imaging for metastasis scanning, starting with T2 patients, may be used in MM staging to reduce the need for sentinel lymph node (SLN) biopsy and lymph node dissection.

Computed tomography texture features can discriminate benign from malignant lymphadenopathy in pediatric patients: a preliminary study

BACKGROUND

Differentiation of benign from malignant lymphadenopathy remains challenging in pediatric radiology. Textural analysis (TA) quantitates heterogeneity of tissue signal intensities and has been applied to analysis of CT images.

OBJECTIVE

The purpose of this study was to establish whether CT textural analysis of enlarged lymph nodes visualized on pediatric CT can distinguish benign from malignant lymphadenopathy.

MATERIALS AND METHODS

We retrospectively identified enlarged lymph nodes measuring 10-20 mm on contrast-enhanced CTs of patients age 18 years and younger that had been categorized as benign or malignant based on the known diagnoses. We placed regions of interest (ROIs) over lymph nodes of interest and performed textural analysis with and without feature size filtration. We then calculated test performance characteristics for TA features, along with multivariate logistic regression modeling using Akaike Information Criterion (AIC) minimization, to determine the optimal thresholds for distinguishing benign from malignant lymphadenopathy.

RESULTS

We identified 34 enlarged malignant nodes and 29 benign nodes from 63 patients within the 10- to 20-mm size range. Filtered image TA exhibited 82.4% sensitivity, 86.2% specificity and 84.1% accuracy for detecting malignant lymph nodes using mean and entropy parameters, whereas unfiltered TA exhibited 88.2% sensitivity, 72.4% specificity and 81.0% accuracy using mean and mean value of positive pixels parameters.

CONCLUSION

This preliminary study demonstrates that the use of TA features improves the utility of pediatric CT to distinguish benign from malignant lymphadenopathy. The addition of TA to pediatric CT protocols has great potential to aid the characterization of indeterminate lymph nodes. If definitive differentiation between benign and malignant lymphadenopathy is possible by TA, it has the potential to reduce the need for follow-up imaging and tissue sampling, with reduced associated radiation exposure. However future studies are needed to confirm the clinical applicability of TA in distinguishing benign from malignant lymphadenopathy.