Prognostic value of the standardized uptake value for (18)F-fluorodeoxyglucose in patients with stage IIIB 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.

The Role and Potential of 18F-FDG PET/CT in Malignant Melanoma: Prognostication, Monitoring Response to Targeted and Immunotherapy, and Radiomics

Novel therapeutic approaches, consisting of immune check-point inhibitors (ICIs) and molecularly targeted therapy, have thoroughly changed the clinical management of malignant melanoma (MM), the most frequent and deadly skin cancer. Since only 30-40% of MM patients respond to ICIs, imaging biomarkers suitable for the pre-therapeutic stratification and response assessment are warmly welcome. In this scenario, positron emission computed tomography (PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) has been successfully utilized for advanced MM staging and therapy response evaluation. Furthermore, several PET-derived parameters (SUVmax, MTV, TLG) were particularly impactful for the prognostic evaluation of patients submitted to targeted and immunotherapy. In this review, we performed a web-based and desktop research on the clinical applications of 18F-FDG PET/CT in MM, with a particular emphasis on the various metabolic criteria developed for interpreting PET/CT scan in patients undergoing immunotherapy or targeted therapy or a combination of both. Furthermore, the emerging role of radiomics, a quantitative approach to medical imaging applying analysis methodology derived by the field of artificial intelligence, was examined in the peculiar context, putting a particular emphasis on the potential of this discipline to support clinicians in the delicate process of building patient-tailored pathways of care.

Prognostic value of 2-[18F]FDG PET-CT in metastatic melanoma patients receiving immunotherapy

PURPOSE

The 2-fluorodeoxyglucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) is used for the evaluation of response to immunotherapy in malignant melanoma. Here, we evaluated the prognostic value of various metabolic parameters in baseline and different time points after therapy.

METHODS

In this retrospective study, 51 metastatic melanoma patients, who had received immunotherapy, were included. Patients with baseline and two follow-up 2-[¹⁸F]FDG PET/CT studies (3 and 6 months after therapy) were selected. Multiple metabolic parameters and tumor-to-background ratios (TBRs) were extracted and correlated with OS.

RESULTS

The 3- and 5-year OS rates were 49% and 43.1%, respectively. On baseline 2-[¹⁸F]FDG PET/CT, only standardized uptake value corrected for lean body mass (SUL_max and SUL_peak), as well as most of the TBRs were predictive for 3- and 5-year OS rates. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and most of the TBRs were predictive on both follow-up studies. Also, the changes in values of MTV, TLG and most of the TBRs from the baseline to the 3-month and 6- month follow-up studies were prognostic. On multivariate analysis, all of the most predictive parameters for OS were derived from the 3-month follow-up study. The ratio of TBR_mean to the mediastinum was the best factor (cutoff value of 2.15, sensitivity of 88.5% and specificity of 68.0% for 3-year survival).

CONCLUSION

Metabolic parameters derived from 2-[¹⁸F]FDG PET/CT are valuable tools for the prediction of 3- and 5-year OS rates in metastatic melanoma patients undergoing immunotherapy. The 3-month follow-up 2-[¹⁸F]FDG PET/CT is of particular importance in this regard.

18F-FDG PET/CT for post-treatment surveillance imaging of patients with stage III Merkel cell carcinoma

To investigate diagnostic and prognostic value of ¹⁸F-FDG PET/CT for surveillance imaging in patients treated for Stage III Merkel cell carcinoma (MCC). Methods: This retrospective study included 61 consecutive stage III MCC patients, who were clinically asymptomatic and underwent surveillance FDG-PET/CT. Findings were correlated with either pathology and/or clinical/imaging follow-up. Median follow-up period was 4.8 years. Statistical analyses were performed. Results: FDG-PET/CT detected unsuspected recurrences in 33% patients (20/61) with lesion-based sensitivity, specificity, and accuracy of 92%, 93%, and 93%, respectively. Mean±SD SUV for malignant and benign lesions was 7.5±3.9 and 3.8±2.0, respectively. Unknown distant metastases, as first recurrence site, were noted in 12 of 61 patients. Those with positive disease on FDG-PET/CT within one year of definitive treatment had relatively worse overall survival (p<0.0001). After adjustment on stage, risk of death increased with higher SUV_max (HR for one unit=1.17;P = 0.006) and with a higher number of positive lesions on FDG-PET/CT (HR for one additional lesion = 1.60;p<0.001). Conclusion: Post-definitive treatment surveillance FDG-PET/CT scan detects unsuspected recurrences and has prognostic value. Inclusion of FDG-PET/CT within the first 6 months after definitive treatment would be appropriate for surveillance and early detection of recurrence. Our data merits further studies to evaluate the prognostic implications.

A multidisciplinary consensus on the morphological and functional responses to immunotherapy treatment

The implementation of immunotherapy has radically changed the treatment of oncological patients. Currently, immunotherapy is indicated in the treatment of patients with head and neck tumors, melanoma, lung cancer, bladder tumors, colon cancer, cervical cancer, breast cancer, Merkel cell carcinoma, liver cancer, leukemia and lymphomas. However, its efficacy is restricted to a limited number of cases. The challenge is, therefore, to identify which subset of patients would benefit from immunotherapy. To this end, the establishment of immunotherapy response criteria and predictive and prognostic biomarkers is of paramount interest. In this report, a group of experts of the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Medical Radiology (SERAM), and Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM) provide an up-to-date review and a consensus guide on these issues.

Clinical and prognostic value of tumor volumetric parameters in melanoma patients undergoing 18F-FDG-PET/CT: a comparison with serologic markers of tumor burden and inflammation

BACKGROUND

To investigate the association of tumor volumetric parameters in melanoma patients undergoing 18F-FDG-PET/CT with serologic tumor markers and inflammatory markers and the role as imaging predictors for overall survival.

METHODS

A patient cohort with advanced melanoma undergoing 18F-FDG-PET/CT for planning metastasectomy between 04/2013 and 01/2015 was retrospectively included. The volumetric PET parameters whole-body MTV and whole-body TLG as well as the standard uptake value (SUV) peak were quantified using 50%-isocontour volumes of interests (VOIs) and then correlated with the serologic parameters lactate dehydrogenase (LDH), S-100 protein, c-reactive protein (CRP) and alkaline phosphatase (AP). PET parameters were dichotomized by their respective medians and correlated with overall survival (OS) after PET/CT. OS was compared between patients with or without metastases and increased or not-increased serologic parameters.

RESULTS

One hundred seven patients (52 female; 65 ± 13.1yr.) were included. LDH was strongly associated with MTV (rP = 0.73, p <  0.001) and TLG (rP = 0.62, p <  0.001), and moderately associated with SUVpeak (rP = 0.55, p <  0.001). S-100 protein showed a moderate association with MTV (rP = 0.54, p <  0.001) and TLG (rP = 0.48, p <  0.001) and a weak association with SUVpeak (rP = 0.42, p <  0.001). A strong association was observed between CRP and MTV (rP = 0.66, p <  0.001) and a moderate to weak association between CRP and TLG (rP = 0.53, p <  0.001) and CRP and SUVpeak (rP = 0.45, p <  0.001). For differentiation between patients with or without metastases, receiver operating characteristic (ROC) analysis revealed a cut-off value of 198 U/l for serum LDH (AUC 0.81, sensitivity 0.80, specificity 0.72). Multivariate analysis for OS revealed that both MTV and TLG were strong independent prognostic factors. TLG, MTV and SUVpeak above patient median were accompanied with significantly reduced estimated OS compared to the PET parameters below patient median (e.g. TLG: 37.1 ± 3.2 months vs. 55.9 ± 2.5 months, p <  0.001). Correspondingly, both elevated serum LDH and S-100 protein were accompanied with significantly reduced OS (36.5 ± 4.9 months and 37.9 ± 4.4 months) compared to normal serum LDH (49.2 ± 2.4 months, p = 0.01) and normal S-100 protein (49.0 ± 2.5 months, p = 0.01).

CONCLUSIONS

Tumor volumetric parameters in 18F-FDG-PET/CT serve as prognostic imaging biomarkers in patients with advanced melanoma which are associated with established serologic tumor markers and inflammatory markers.

18F-FDG PET/CT based spleen to liver ratio associates with clinical outcome to ipilimumab in patients with metastatic melanoma

Background

Immune checkpoint blockade such as ipilimumab and anti-PD1 monoclonal antibodies have significantly improved survival in advanced melanoma. Biomarkers are urgently needed as a majority of patients do not respond, despite treatment-related toxicities. We analysed pre-treatment ¹⁸F-fluorodeoxyglucose positron emission tomography/computerised tomography (FDG PET/CT) parameters to assess its correlation with patient outcome.

Methods

This retrospective study evaluated pre-treatment FDG PET/CT scans in a discovery cohort of patients with advanced melanoma treated with ipilimumab or anti-PD1. Pre-treatment scans were assessed for maximum tumoral standardised uptake value (SUVmax), metabolic tumour volume (MTV) and spleen to liver ratio (SLR). Progression-free survival (PFS) and overall survival (OS) were characterised and modelled using univariable and multivariable analyses. Correlation of SLR and OS was validated in an independent cohort. Blood parameters and stored sera of patients from the discovery cohort was analysed to investigate biological correlates with SLR.

Results

Of the 90 evaluable patients in the discovery cohort: 50 received ipilimumab monotherapy, 20 received anti-PD1 monotherapy, and 20 patients received ipilimumab followed by anti-PD1 upon disease progression. High SLR > 1.1 was associated with poor PFS (median 1 vs 3 months; HR 3.14, p = 0.008) for patients treated with ipilimumab. High SLR was associated with poor OS after ipilimumab (median 1 vs 21 months; HR 5.83, p = 0.0001); as well as poor OS after first line immunotherapy of either ipilimumab or anti-PD1 (median 1 vs 14 months; HR 3.92, p = 0.003). The association of high SLR and poor OS after ipilimumab was validated in an independent cohort of 110 patients (median 2.3 months versus 11.9 months, HR 3.74). SLR was associated with poor OS in a multi-variable model independent of stage, LDH, absolute lymphocyte count and MTV.

Conclusions

Pre-treatment Spleen to liver ratio (SLR) > 1.1 was associated with poor outcome after ipilimumab in advanced melanoma. This parameter warrants prospective evaluation.

Prognostic and theranostic 18F-FDG PET biomarkers for anti-PD1 immunotherapy in metastatic melanoma: association with outcome and transcriptomics

PURPOSE

An imaging-based stratification tool is needed to identify melanoma patients who will benefit from anti Programmed Death-1 antibody (anti-PD1). We aimed at identifying biomarkers for survival and response evaluated in lymphoid tissue metabolism in spleen and bone marrow before initiation of therapy.

METHODS

This retrospective study included 55 patients from two institutions who underwent 18F-FDG PET/CT before anti-PD1. Parameters extracted were SUVmax, SUVmean, HISUV (SUV-based Heterogeneity Index), TMTV (total metabolic tumor volume), TLG (total lesion glycolysis), BLR (Bone marrow-to-Liver SUVmax ratio), and SLR (Spleen-to-Liver SUVmax ratio). Each parameter was dichotomized using the median as a threshold. Association with survival, best overall response (BOR), and transcriptomic analyses (NanoString assay) were evaluated using Cox prediction models, Wilcoxon tests, and Spearman's correlation, respectively.

RESULTS

At 20.7 months median follow-up, 33 patients had responded, and 29 patients died. Median PFS and OS were 11.4 (95%CI 2.7-20.2) and 28.5 (95%CI 13.4-43.8) months. TMTV (>25cm³), SLR (>0.77), and BLR (>0.79) correlated with shorter survival. High TMTV (>25 cm3), SLR (>0.77), and BLR (>0.79) correlated with shorter survival, with TMTV (HR PFS 2.2, p = 0.02, and HR OS 2.5, p = 0.02) and BLR (HR OS 2.3, p = 0.04) remaining significant in a multivariable analysis. Low TMTV and TLG correlated with BOR (p = 0.03). Increased glucose metabolism in bone marrow (BLR) was associated with transcriptomic profiles including regulatory T cell markers (p < 0.05).

CONCLUSION

Low tumor burden correlates with survival and objective response while hematopoietic tissue metabolism correlates inversely with survival. These biomarkers should be further evaluated for potential clinical application.

Tumor Heterogeneity on FDG PET/CT and Immunotherapy: An Imaging Biomarker for Predicting Treatment Response in Patients With Metastatic Melanoma

OBJECTIVE. The purpose of this study is to evaluate the ability of quantitative ¹⁸F-FDG PET parameters to predict outcomes of patients with malignant melanoma who have been treated with immune modulation therapy. MATERIALS AND METHODS. We retrospectively investigated 34 patients with malignant melanoma. Twenty-three patients received immunotherapy as first-line therapy, and 11 patients received it as second-line therapy. The maximum standardized uptake value (SUV_max), metabolic tumor volume, tumor lesion glycolysis, and intratumoral metabolic heterogeneity (as measured by the tumor heterogeneity [TH] index) were measured for the primary tumors and metastatic sites associated with up to five of the most FDG-avid lesions per patient. The TH index was calculated as the AUC value of a cumulative SUV volume histogram curve for all patients. The median follow-up was 29.5 months (range, 3-288 months). Outcome endpoints were progression-free survival and overall survival. Kaplan-Meier survival plots were used, and Cox regression analysis was performed for predictors of survival. RESULTS. A total of 101 lesions were analyzed. Five lesions were analyzed in 12 patients, four lesions in three patients, three lesions in three patients, two lesions in four patients, and one lesion in 12 patients. Of the 34 patients included in the study, 15 (44.1%) had disease progression and 11 (32.3%) had died by the time the last follow-up occurred. The mean (± SD) SUV_max, peak SUV, metabolic tumor volume, tumor lesion glycolysis, and TH values for all lesions were 9.68 ± 6.6, 7.82 ± 5.83, 81.96 ± 146.87 mL, 543.65 ± 1022.92 g, and 5841.36 ± 1249.85, respectively. TH had a negative correlation with SUV_max, peak SUV, and tumor lesion glycolysis (p < 0.0001 for all). CONCLUSION. The TH index is significantly associated with overall survival in patients with metastatic melanoma treated with immune modulation therapy as first-line or second-line therapy.

Role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in restaging and prognosis of recurrent melanoma after curative surgery

Malignant melanoma is a highly aggressive tumor and surgical resection is the primary treatment. However, the chances of recurrence are quite high despite complete resection. The aim of study was to evaluate the 18F-fluorodeoxyglucose(18F-FDG) positron emission tomography-computed tomography (PET/CT) in detection of recurrent melanoma after curative surgery and its prognostic value. Fifty-four melanoma patients (32 women) with prior primary lesion resection were evaluated with 18F-FDG PET/CT for clinically suspicious recurrent disease. The diagnostic accuracy of 18F-FDG PET/CT (visual interpretation as well as semi-quantitative parameter) was determined on the basis of subsequent imaging and clinical follow-up. Melanoma-specific survival and risk of progression (hazard ratio [HR]) were assessed using Kaplan-Meier method and Cox regression analysis. 18F-FDG PET/CT detected recurrent diseases in 36 (66%) patients including distant metastases in 13 patients and second synchronous malignancy in 2 patients. Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of 18F-FDG PET/CT were 91.2%, 80.0%, 88.6%, and 84.2%, respectively, with area under the curve of 0.86 (95% confidence interval: 0.74-0.97; P < 0.05). Positive 18F-FDG PET/CT study was associated with a significantly shorter overall survival than negative study (30.8 ± 4.6 vs. 64.5 ± 6.9 months, P < 0.05). Apart from positive 18F-FDG PET/CT scan, maximum standardized uptake value (SUVmax) >2.7 and combination of both were independently associated with an increased risk of disease progression (HR = 7.72, 21.58, and 11.37, respectively; P < 0.05). 18F-FDG PET/CT showed enhanced diagnostic performance in patients with suspicious recurrent malignant melanoma leading to appropriate management. FDG positivity along with SUVmax >2.7 provides important prognostic value in predicting the survival outcomes and assessing the risk of disease progression.

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.

Diagnostic accuracy of (18)F-FDG-PET/CT in early and late stages of high-risk cutaneous malignant melanoma

BACKGROUND

The precise role of total body (18) F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) in the clinical management of patients with cutaneous malignant melanoma (CMM) is not well established.

OBJECTIVE

The purpose of this study was to investigate the diagnostic accuracy of PET/CT in early- and late-stage patients with high-risk CMM.

METHODS

We retrospectively analysed various imaging, histopathological and clinical data from 97 patients also examined by PET/CT during a 5-year period (2007-2011). Three groups were assessed: stage I/II, resected stage III and unresectable stage III/stage IV.

RESULTS

The median follow-up time of living patients was 43.48 ± 19.67 (15-142) months. We observed a high diagnostic accuracy in all stages (91.3%, 92.5% and 96.2% respectively). PET/CT appeared to be reliable diagnostic tool even for the detection of small lymph node metastases. PET/CT was informative in 14 of 19 cases wherein another imaging examination provided inconclusive results regarding lesion dignity. However, PET/CT was less suitable for properly evaluating the dignity of a lung lesion. A true positive scan was twice as likely in clinically negative patients with resected stage III disease than in patients with stage I/II disease (35.9% and 14.5%, P = 0.007).

CONCLUSIONS

These results confirm that PET/CT is an important diagnostic tool in the management of patients with high-risk CMM, but it cannot replace the standard of care examinations. More accurate clinicopathological and timing criteria must be defined to best utilize the advantages of this imaging method.

Correlation of PUV and SUV in the extremities while using PEM as a high-resolution positron emission scanner

OBJECTIVE

Owing to its unique configuration of two adjustable plate detectors positron emission mammography, or PEM, could theoretically also function as a high-resolution positron emission scanner for the extremities or neck. PEM quantitates its activity via a "PEM uptake value," or PUV, and although its relationship to the standardized uptake value, or SUV, has been demonstrated in the breasts, to our knowledge there are no studies validating PUV in other sites such as the extremities.

MATERIALS AND METHODS

This was a retrospective chart review of two separate protocols of a total of 15 patients. The patients all had hypermetabolic lesions in the extremities or neck on imaging with PET/CT and were sent after their PET/CT to PEM for further imaging. Owing to the sequential nature of these examinations no additional radiotracer was administered.

RESULTS

Spearman's rank order correlation was calculated between the PUVmax obtained from PEM images, and the SUVmax for all. Spearman's rank order correlation for all sites was 0.42, which is not significantly different from 0 (p = 0.13). When neck lesions were excluded from the group, there was a strong and statistically significant correlation between PUVmax and SUVmax, with Spearman's rank correlation of 0.73, and significantly different from 0 (p = 0.0068).

DISCUSSION

The correlation of PUV and SUV in the extremities indicates the potential use of PEM as a semiquantitative, high-resolution positron emission scanner and warrants further investigation, especially in the realms of disease processes that often present in the extremities, such as melanoma, osteomyelitis, and arthritis, as well as playing a role in the imaging of patients with metallic hardware post-limb salvage surgery.

Incorporating prognostic imaging biomarkers into clinical practice

A prognostic imaging biomarker can be defined as an imaging characteristic that is objectively measurable and provides information on the likely outcome of the cancer disease in an untreated individual and should be distinguished from predictive imaging biomarkers and imaging markers of response. A range of tumour characteristics of potential prognostic value can be measured using a variety imaging modalities. However, none has currently been adopted into routine clinical practice. This article considers key examples of emerging prognostic imaging biomarkers and proposes an evaluation framework that aims to demonstrate clinical efficacy and so support their introduction into the clinical arena. With appropriate validation within an established evaluation framework, prognostic imaging biomarkers have the potential to contribute to individualized cancer care, in some cases reducing the financial burden of expensive cancer treatments by facilitating their more rational use.

Focused regional FDG PET/CT detects more osseous metastases than does whole-body PET/CT

A patient with melanoma underwent FDG PET/CT for surveillance of metastatic disease. The whole-body PET/CT scan demonstrated a single FDG-avid lesion in the left ilium, suggestive of an osseous metastasis. Because there was no corresponding CT abnormality, biopsy was planned using PET/CT guidance. The PET/CT for biopsy guidance focused over a single pelvic bed position demonstrated at least 12 FDG-avid osseous metastases, which were not apparent on the original whole-body PET/CT. This case highlights the limitations of whole-body PET/CT in the detection of small metastases and suggests that a PET/CT focused over a specific body region can improve the sensitivity of detecting small metastases.