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.

Skin Cancer Pathobiology at a Glance: A Focus on Imaging Techniques and Their Potential for Improved Diagnosis and Surveillance in Clinical Cohorts

Early diagnosis is essential for completely eradicating skin cancer and maximizing patients' clinical benefits. Emerging optical imaging modalities such as reflectance confocal microscopy (RCM), optical coherence tomography (OCT), magnetic resonance imaging (MRI), near-infrared (NIR) bioimaging, positron emission tomography (PET), and their combinations provide non-invasive imaging data that may help in the early detection of cutaneous tumors and surgical planning. Hence, they seem appropriate for observing dynamic processes such as blood flow, immune cell activation, and tumor energy metabolism, which may be relevant for disease evolution. This review discusses the latest technological and methodological advances in imaging techniques that may be applied for skin cancer detection and monitoring. In the first instance, we will describe the principle and prospective clinical applications of the most commonly used imaging techniques, highlighting the challenges and opportunities of their implementation in the clinical setting. We will also highlight how imaging techniques may complement the molecular and histological approaches in sharpening the non-invasive skin characterization, laying the ground for more personalized approaches in skin cancer patients.

Staging 18F-FDG PET/CT influences the treatment plan in melanoma patients with satellite or in-transit metastases

Whole-body positron emission tomography/computed tomography (PET/CT) and brain magnetic resonance imaging (MRI) are commonly used to stage patients with palpable lymph node metastases from melanoma, but their role in patients with satellite and/or in-transit metastasis (S&ITM) is unclear. The aim of this study was to establish the diagnostic value of PET/CT and brain MRI in these patients, and to assess their influence on subsequent management decisions. In this prospective study, 25 melanoma patients with a first presentation of S&ITM who had no clinical evidence of palpable nodal or distant metastasis underwent whole-body ¹⁸F-FDG PET/CT and brain MRI after a tentative pre-scan treatment plan had been made. Sensitivity and specificity of imaging were determined by pathological confirmation, clinical outcome and repeat PET/CT and MRI at 6 months. PET/CT led to a modification of the initial treatment plan in four patients (16%). All four were upstaged (AJCC stage eighth edition). PET/CT was false-positive in one patient, who had a Schwannoma in his trapezius muscle. A thyroid carcinoma was an incidental finding in another patient. The sensitivity of PET/CT was 58% and specificity 83%. In 6 months following the baseline PET/CT, further sites of in-transit or systemic disease were identified in 10 patients (40%). Brain MRI did not alter the treatment plan or change the disease stage in any patient. Whole-body PET/CT improved staging in melanoma patients with S&ITM and changed the originally-contemplated treatment plan in 16%. MRI of the brain appeared not to be useful.

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.

Malignant Cutaneous Melanoma: Updates in PET Imaging

BACKGROUND

Cutaneous malignant melanoma is a neoplasm whose incidence and mortality are dramatically increasing. 18F-FDG PET/CT gained clinical acceptance over the past 2 decades in the evaluation of several glucose-avid neoplasms, including malignant melanoma, particularly for the assessment for distant metastases, recurrence and response to therapy.

OBJECTIVE

To describe the advancements of nuclear medicine for imaging melanoma with particular attention to 18F-FDG-PET and its current state-of-the-art technical innovations.

METHODS

A comprehensive search strategy was used based on SCOPUS and PubMed databases. From all studies published in English, we selected the articles that evaluated the technological insights of 18FFDG- PET in the assessment of melanoma.

RESULTS

State-of-the-art silicon photomultipliers based detectors ("digital") PET/CT scanners are nowadays more common, showing technical innovations that may have beneficial implications for patients with melanoma. Steady improvements in detectors design and architecture, as well as the implementation of both software and hardware technology (i.e., TOF, point spread function, etc.), resulted in significant improvements in PET image quality while reducing radiotracer dose and scanning time.

CONCLUSION

Recently introduced digital PET detector technology in PET/CT and PET/MRI yields higher intrinsic system sensitivity compared with the latest generation analog technology, enabling the detection of very small lesions with potential impact on disease outcome.

Ultrasound, CT, MRI, or PET-CT for staging and re-staging of adults with cutaneous melanoma

BACKGROUND

Melanoma is one of the most aggressive forms of skin cancer, with the potential to metastasise to other parts of the body via the lymphatic system and the bloodstream. Melanoma accounts for a small percentage of skin cancer cases but is responsible for the majority of skin cancer deaths. Various imaging tests can be used with the aim of detecting metastatic spread of disease following a primary diagnosis of melanoma (primary staging) or on clinical suspicion of disease recurrence (re-staging). Accurate staging is crucial to ensuring that patients are directed to the most appropriate and effective treatment at different points on the clinical pathway. Establishing the comparative accuracy of ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)-CT imaging for detection of nodal or distant metastases, or both, is critical to understanding if, how, and where on the pathway these tests might be used.

OBJECTIVES

Primary objectivesWe estimated accuracy separately according to the point in the clinical pathway at which imaging tests were used. Our objectives were:• to determine the diagnostic accuracy of ultrasound or PET-CT for detection of nodal metastases before sentinel lymph node biopsy in adults with confirmed cutaneous invasive melanoma; and• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for whole body imaging in adults with cutaneous invasive melanoma:○ for detection of any metastasis in adults with a primary diagnosis of melanoma (i.e. primary staging at presentation); and○ for detection of any metastasis in adults undergoing staging of recurrence of melanoma (i.e. re-staging prompted by findings on routine follow-up).We undertook separate analyses according to whether accuracy data were reported per patient or per lesion.Secondary objectivesWe sought to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for whole body imaging (detection of any metastasis) in mixed or not clearly described populations of adults with cutaneous invasive melanoma.For study participants undergoing primary staging or re-staging (for possible recurrence), and for mixed or unclear populations, our objectives were:• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of nodal metastases;• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of distant metastases; and• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of distant metastases according to metastatic site.

SEARCH METHODS

We undertook a comprehensive search of the following databases from inception up to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

We included studies of any design that evaluated ultrasound (with or without the use of fine needle aspiration cytology (FNAC)), CT, MRI, or PET-CT for staging of cutaneous melanoma in adults, compared with a reference standard of histological confirmation or imaging with clinical follow-up of at least three months' duration. We excluded studies reporting multiple applications of the same test in more than 10% of study participants.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2)). We estimated accuracy using the bivariate hierarchical method to produce summary sensitivities and specificities with 95% confidence and prediction regions. We undertook analysis of studies allowing direct and indirect comparison between tests. We examined heterogeneity between studies by visually inspecting the forest plots of sensitivity and specificity and summary receiver operating characteristic (ROC) plots. Numbers of identified studies were insufficient to allow formal investigation of potential sources of heterogeneity.

MAIN RESULTS

We included a total of 39 publications reporting on 5204 study participants; 34 studies reporting data per patient included 4980 study participants with 1265 cases of metastatic disease, and seven studies reporting data per lesion included 417 study participants with 1846 potentially metastatic lesions, 1061 of which were confirmed metastases. The risk of bias was low or unclear for all domains apart from participant flow. Concerns regarding applicability of the evidence were high or unclear for almost all domains. Participant selection from mixed or not clearly defined populations and poorly described application and interpretation of index tests were particularly problematic.The accuracy of imaging for detection of regional nodal metastases before sentinel lymph node biopsy (SLNB) was evaluated in 18 studies. In 11 studies (2614 participants; 542 cases), the summary sensitivity of ultrasound alone was 35.4% (95% confidence interval (CI) 17.0% to 59.4%) and specificity was 93.9% (95% CI 86.1% to 97.5%). Combining pre-SLNB ultrasound with FNAC revealed summary sensitivity of 18.0% (95% CI 3.58% to 56.5%) and specificity of 99.8% (95% CI 99.1% to 99.9%) (1164 participants; 259 cases). Four studies demonstrated lower sensitivity (10.2%, 95% CI 4.31% to 22.3%) and specificity (96.5%,95% CI 87.1% to 99.1%) for PET-CT before SLNB (170 participants, 49 cases). When these data are translated to a hypothetical cohort of 1000 people eligible for SLNB, 237 of whom have nodal metastases (median prevalence), the combination of ultrasound with FNAC potentially allows 43 people with nodal metastases to be triaged directly to adjuvant therapy rather than having SLNB first, at a cost of two people with false positive results (who are incorrectly managed). Those with a false negative ultrasound will be identified on subsequent SLNB.Limited test accuracy data were available for whole body imaging via PET-CT for primary staging or re-staging for disease recurrence, and none evaluated MRI. Twenty-four studies evaluated whole body imaging. Six of these studies explored primary staging following a confirmed diagnosis of melanoma (492 participants), three evaluated re-staging of disease following some clinical indication of recurrence (589 participants), and 15 included mixed or not clearly described population groups comprising participants at a number of different points on the clinical pathway and at varying stages of disease (1265 participants). Results for whole body imaging could not be translated to a hypothetical cohort of people due to paucity of data.Most of the studies (6/9) of primary disease or re-staging of disease considered PET-CT, two in comparison to CT alone, and three studies examined the use of ultrasound. No eligible evaluations of MRI in these groups were identified. All studies used histological reference standards combined with follow-up, and two included FNAC for some participants. Observed accuracy for detection of any metastases for PET-CT was higher for re-staging of disease (summary sensitivity from two studies: 92.6%, 95% CI 85.3% to 96.4%; specificity: 89.7%, 95% CI 78.8% to 95.3%; 153 participants; 95 cases) compared to primary staging (sensitivities from individual studies ranged from 30% to 47% and specificities from 73% to 88%), and was more sensitive than CT alone in both population groups, but participant numbers were very small.No conclusions can be drawn regarding routine imaging of the brain via MRI or CT.

AUTHORS' CONCLUSIONS

Review authors found a disappointing lack of evidence on the accuracy of imaging in people with a diagnosis of melanoma at different points on the clinical pathway. Studies were small and often reported data according to the number of lesions rather than the number of study participants. Imaging with ultrasound combined with FNAC before SLNB may identify around one-fifth of those with nodal disease, but confidence intervals are wide and further work is needed to establish cost-effectiveness. Much of the evidence for whole body imaging for primary staging or re-staging of disease is focused on PET-CT, and comparative data with CT or MRI are lacking. Future studies should go beyond diagnostic accuracy and consider the effects of different imaging tests on disease management. The increasing availability of adjuvant therapies for people with melanoma at high risk of disease spread at presentation will have a considerable impact on imaging services, yet evidence for the relative diagnostic accuracy of available tests is limited.

Melanoma & nuclear medicine: new insights & advances

The contribution of nuclear medicine to management of melanoma patients is increasing. In intermediate-thickness N0 melanomas, lymphoscintigraphy provides a roadmap for sentinel node biopsy. With the introduction of single-photon emission computed tomography images with integrated computed tomography (SPECT/CT), 3D anatomic environments for accurate surgical planning are now possible. Sentinel node identification in intricate anatomical areas (pelvic cavity, head/neck) has been improved using hybrid radioactive/fluorescent tracers, preoperative lymphoscintigraphy and SPECT/CT together with modern intraoperative portable imaging technologies for surgical navigation (free-hand SPECT, portable gamma cameras). Furthermore, PET/CT today provides 3D roadmaps to resect 18F-fluorodeoxyglucose-avid melanoma lesions. Simultaneously, in advanced-stage melanoma and recurrences, 18F-fluorodeoxyglucose-PET/CT is useful in clinical staging and treatment decision as well as in the evaluation of therapy response. In this article, we review new insights and recent nuclear medicine advances in the management of melanoma patients.

Futility of imaging to stage melanoma patients with a positive sentinel lymph node

The use of staging imaging in melanoma patients with a positive sentinel lymph node (SLN) has been reported to be of limited value. Improved accuracy resulting from the development of time-of-flight positron emission tomography (PET) and ongoing image quality improvement of computed tomography (CT) may challenge this statement. Our retrospective study assessed the clinical value of routine staging CT and PET/CT imaging in a recent cohort of asymptomatic SLN-positive patients. Between January 2011 and April 2014, 143 patients with a positive SLN were routinely staged using CT of various parts of the body or whole-body PET/CT. Scores were assigned for level of certainty for regional or distant metastases and incidental second primary malignancies. Diagnostic test performance was assessed, as well as the number and nature of ensuing additional diagnostic actions. CT was performed in 102 of 143 (71%) patients and PET/CT in 41 (29%) patients. The use of PET/CT increased over the study period. Metastases were found in two of the 143 patients (true-positive yield 1.4%). Sensitivity, specificity and positive predictive value were 11, 73 and 4% for CT and 17, 57 and 6%, respectively, for PET/CT. None of the 143 patients had a change in AJCC stage. Two other primary malignancies were found. Twenty-one (15%) patients were subjected to 37 additional investigations, referrals or procedures. Routine staging imaging with CT or PET/CT in SLN-positive patients is not useful. The yield is low and the results are often false positive, leading to unnecessary additional tests, most of which are costly and some potentially morbid.

Intraoperative Fluorescence Imaging and Multimodal Surgical Navigation Using Goggle System

Intraoperative imaging is an invaluable tool in many surgical procedures. We have developed a wearable stereoscopic imaging and display system entitled Integrated Imaging Goggle, which can provide real-time multimodal image guidance. With the Integrated Imaging Goggle, wide field-of-view fluorescence imaging is tracked and registered with intraoperative ultrasound imaging and preoperative tomography-based surgical navigation, to provide integrated multimodal imaging capabilities in real-time. Herein we describe the system instrumentation and the methods of using the Integrated Imaging Goggle to guide surgeries.

PET and SPECT imaging of melanoma: the state of the art

Melanoma represents the most aggressive form of skin cancer, and its incidence continues to rise worldwide. 18F-FDG PET imaging has transformed diagnostic nuclear medicine and has become an essential component in the management of melanoma, but still has its drawbacks. With the rapid growth in the field of nuclear medicine and molecular imaging, a variety of promising probes that enable early diagnosis and detection of melanoma have been developed. The substantial preclinical success of melanin- and peptide-based probes has recently resulted in the translation of several radiotracers to clinical settings for noninvasive imaging and treatment of melanoma in humans. In this review, we focus on the latest developments in radiolabeled molecular imaging probes for melanoma in preclinical and clinical settings, and discuss the challenges and opportunities for future development.

Vemurafenib plus cobimetinib in unresectable stage IIIc or stage IV melanoma: response monitoring and resistance prediction with positron emission tomography and tumor characteristics (REPOSIT): study protocol of a phase II, open-label, multicenter study

BACKGROUND

In patients with BRAFV600 mutated unresectable stage IIIc or metastatic melanoma, molecular targeted therapy with combined BRAF/MEK-inhibitor vemurafenib plus cobimetinib has shown a significantly improved progression-free survival and overall survival compared to treatment with vemurafenib alone. Nevertheless, the majority of BRAFV600 mutation-positive melanoma patients will eventually develop resistance to treatment. Molecular imaging with 18F-Fluorodeoxyglucose (18F-FDG) PET has been used to monitor response to vemurafenib in some BRAFV600 mutated metastatic melanoma patients, showing a rapid decline of 18F-FDG uptake within 2 weeks following treatment. Furthermore, preliminary results suggest that metabolic alterations might predict the development of resistance to treatment. 18F-Fluoro-3'-deoxy-3'L-fluorothymidine (18F-FLT), a PET-tracer visualizing proliferation, might be more suitable to predict response or resistance to therapy than 18F-FDG.

METHODS

This phase II, open-label, multicenter study evaluates whether metabolic response to treatment with vemurafenib plus cobimetinib in the first 7 weeks as assessed by 18F-FDG/18F-FLT PET can predict progression-free survival and whether early changes in 18F-FDG/18F-FLT can be used for early detection of treatment response compared to standard response assessment with RECISTv1.1 ceCT at 7 weeks. Ninety patients with BRAFV600E/K mutated unresectable stage IIIc/IV melanoma will be included. Prior to and during treatment all patients will undergo 18F-FDG PET/CT and in 25 patients additional 18F-FLT PET/CT is performed. Histopathological tumor characterization is assessed in a subset of 40 patients to unravel mechanisms of resistance. Furthermore, in all patients, blood samples are taken for pharmacokinetic analysis of vemurafenib/cobimetinib. Outcomes are correlated with PET/CT-imaging and therapy response.

DISCUSSION

The results of this study will help in linking PET measured metabolic alterations induced by targeted therapy of BRAFV600 mutated melanoma to molecular changes within the tumor. We will be able to correlate both 18F-FDG and 18F-FLT PET to outcome and decide on the best modality to predict long-term remissions to combined BRAF/MEK-inhibitors. Results coming from this study may help in identifying responders from non-responders early after the initiation of therapy and reveal early development of resistance to vemurafenib/cobimetinib. Furthermore, we believe that the results can be fundamental for further optimizing individual patient treatment.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02414750. Registered 10 April 2015, retrospectively registered.

Melanoma patient imaging in the era of effective systemic therapies

Imaging plays a critical role in the current multi-disciplinary management of patients with melanoma. It is used for primary disease staging, surgical planning, and surveillance in high-risk patients, and for monitoring the effects of systemic or loco-regional therapies. Several different imaging modalities have been utilised in the past. Contemporary imaging practises vary geographically depending on clinical guidelines, physician preferences, availability and cost. Targeted therapies and immunotherapies have revolutionised the treatment of patients with metastatic melanoma over the last few years. With this have come new patterns of disease that were not observed after conventional therapies, and new criteria to assess therapeutic responses. In this article we review the role of imaging for patients with melanoma in the era of effective systemic therapies and discuss likely future developments.

Diagnostic Accuracy and Impact of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Preoperative Staging of Cutaneous Malignant Melanoma: Results of a Prospective Study in Indian Population

The aim of the study was to evaluate the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) in staging patients with primary cutaneous malignant melanoma (CMM). We further compared the performance of PET/CT with conventional imaging (CI) (CT and ultrasonography [USG]) and assessed the impact of PET/CT on disease management. This was a single institution, prospective, double-blinded study, recruiting a total of 70 treatment naïve patients. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of PET/CT for N staging were 86%, 96%, 80%, and 97%, respectively. The sensitivity, specificity, NPV, and PPV of PET/CT for M staging were 87%, 100%, 93%, and 100%, respectively. The diagnostic accuracy of the PET/CT was superior to CI for N staging (90% vs. 84% for CT and 80% for USG) and M staging (95% vs. 90% for CT). No statistically significant difference was noted between PET/CT and CI for N staging (PET/CT vs. CT, P = 0.125; PET/CT vs. USG, P-0.063) or M staging (PET/CT vs. CT, P = 0.125). PET/CT upstaged 23% of patients with clinically localized disease and 58% of patients with clinically palpable regional nodes. To conclude, fluorodeoxyglucose PET/CT is a highly sensitive and specific imaging modality for preoperative staging of primary CMMs. PET/CT impacts disease management in significant number of patients and should be especially recommended in all patients with clinically palpable regional nodes.

Primary cerebral malignant melanoma in insular region with extracranial metastasis: case report and review literature

BACKGROUND

Primary brain melanomas are very infrequent and metastasis outside central nervous system very uncommon. There are some cases in the literature about primary melanoma in the temporal lobe; nevertheless, the insular location has never been described.

CASE PRESENTATION

The patient presented as left insular intraparenchymal hematoma with multiple bleedings. Complementary tests did not show any tumoral nor vascular pattern in relation with these bleedings. A complete surgical resection was performed, and the diagnosis of malignant melanoma, with BRAF mutation, was obtained after histology exam. Extension studies were negative for skin or mucous melanoma. 18F-FDG PET/CT was performed and a metastatic lymph node was found. The diagnosis was primary brain melanoma with extracerebral metastasis. Dabrafenib 150 mg/12 h was the only chemotherapy during 5 months. After that, Trametinib 2 mg/24 h was added to the treatment. Eighteen months after surgery, the patient is independent, with stable situation, and without new metastasis.

CONCLUSIONS

Although malignant melanomas have poor prognosis, total surgical resection and new therapies are increasing the overall survival and improving quality of life. In a patient with suspected brain melanoma, in spite of having extracerebral metastasis, aggressive treatment may be considered.

Melanoma and nuclear medicine

Supported by a large body of published work, the contribution of nuclear medicine technologies to the assessment of melanoma has been increasing in recent years. Lymphoscintigraphy-assisted sentinel lymph node biopsy and PET are in continuous evolution with the aid of technological imaging advances, making it possible to fuse functional and anatomic images (e.g., with SPECT/CT, PET/CT and 3D rendering systems). The development of hybrid fluorescent-radioactive tracers that enable high-quality preoperative lymphoscintigraphy and SPECT/CT, and the optimization of modern intraoperative portable imaging technologies, such as free-hand SPECT and portable γ-cameras, are important innovations that have improved sentinel lymph node identification in complex anatomical areas, such as the pelvis and head and neck. Concurrently, ¹⁸F-fluorodeoxyglucose-PET has proved its usefulness in the clinical staging and treatment decision-making process, and there is also emerging evidence regarding its utility in the evaluation of therapeutic response. The potential uses of other novel PET radiotracers could open up a new field of use for this technique. In this article, we review the current and future role of nuclear medicine in the management of melanoma.

The clinical use of PET/CT in the evaluation of melanoma

Positron emission tomography combined with computed tomography (PET/CT) has emerged in the last decade as a dominant imaging modality used for staging, monitoring response and surveillance of various cancers, including melanoma. Using 2-deoxy-2-((18)F)fluoro-D-glucose ((18)F-FDG) as the radiopharmaceutical, PET/CT has demonstrated its efficacy and its utility in the management of patients with advanced melanoma. Nonetheless, challenges remain in the early stage evaluation of melanoma and in the development of novel radiotracers to better characterize lesions found on PET/CT. This chapter focuses on the advantages and limitations of this imaging modality in melanoma. We also detail and describe the approach to perform (18)F-FDG PET/CT, the methods to accurately quantify lesions, as well as the pearls/pitfalls of image interpretation. Finally, an overview of preclinical and investigational clinical radiopharmaceuticals is presented.

Melanotic and non-melanotic malignancies of the face and external ear - A review of current treatment concepts and future options

Skin has the highest incidence and variety of tumors of all organs. Its structure is of great complexity, and every component has the potential to originate a skin neoplasm (SN). Because of its exposed nature, skin is vulnerable to carcinogenic stimuli such as UV radiation. Various entities can cause SN. Nonmelanotic skin cancers (NMSC) are the most common of all cancers, with over one million cases diagnosed annually in the US. Basal cell carcinoma (BCC) accounts for approximately 80% of all NMSC, most of the remaining 20% being squamous cell carcinoma (SCC). The skin of the head and neck is the most common site for tumors, accounting for more than 80% of all NMSC. BCC, SCC, and malignant melanomas (MM) represent 85-90% of all SN. Merkel cell tumors (MCC), lymphoepithelioma-like carcinomas of the skin (LELCS), dermato-fibro-sarcomas, leiomyosarkomas, and Kaposi-sarcomas are less frequent in the facial skin region and the external ear. Based on data from the German Federal Cancer Registry (2003/2004), 140,000 people in Germany were affected by SN (100,000 BCC, 22,000 SCC, 22,000 MM). This number increases considerably if malignant precursors, such as actinic keratosis, are included. Each year, the frequency of SN diagnosis rises by 3-7%. Among all known malignant tumors, MM exhibits the highest rate of increase in incidence. In the past, SN was primarily diagnosed in people aged 50 years or older. However, recently, the risk for developing SN has shifted, and younger people are also affected. Early diagnosis is significantly correlated with prognosis. Resection of SN creates defects that must be closed with local or microvascular flaps to avoid functional disturbing scar formation and deflection of the nose, eyelids, or lips. All therapeutic strategies for SN, the current standard for adjuvant and systemic treatment, and the management of the increasing number of patients under permanent blood thinner medication are described with regard to the treatment of SN.

Comparison of whole-body versus limited whole-body 18F-FDG PET/CT scan in malignant cutaneous melanoma

OBJECTIVES

The objectives of this study were to estimate retrospectively the incidence of clinically significant findings in the lower extremities in patients with malignant cutaneous melanoma scanned from the skull vertex to the bottom of the feet and whether these add additional diagnostic and prognostic information and to demonstrate a confidence interval that would support exclusion of lower-extremity scans in these patients.

METHODS

This is a retrospective study of 200 patients who underwent (18)F-FDG PET/CT for staging melanoma. Whole-body PET/CT scans including the lower extremities were reviewed. PET/CT findings in the lower extremities were tabulated by location, pathology, and clinical progress notes with documented clinical history and physical examination correlation.

RESULTS

Among the 200 PET/CT scans, 3 scans had positive findings in the lower extremities. A biopsy was performed on 1 lesion, which was found to be an incidental squamous cell carcinoma. One lesion was considered a benign finding from inflammation demonstrated by clinical follow-up. One scan had a metastasis to the proximal femur, which is included in the standard FOV (eyes to midthighs). In this case series, the lower extremities' true-positive findings never impacted or changed clinical management.

CONCLUSIONS

Our study confirms with a high degree of confidence that in patients with malignant cutaneous melanoma, additional lower-extremity scan results in little additional useful information and could be discontinued in patients whose melanoma did not arise in the lower extremities. PET/CT acquisition of the lower extremities results in increased scan time and unnecessary extra radiation dose from CT to melanoma patients.

Clinical impact of (18)F-FDG PET-CT in recurrent stage III/IV melanoma: a tertiary centre Specialist Skin Cancer Multidisciplinary Team (SSMDT) experience

Objectives

To assess the clinical impact of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) compared with contrast-enhanced computed tomography (CECT) in patients referred via the Specialist Skin Cancer Multidisciplinary Team (SSMDT) with recurrent stage III/IV malignant melanoma (MM).

Methods

Forty-five patients were referred for further evaluation with FDG PET-CT. Findings on FDG PET-CT were compared with prior CECT and the clinical impact on subsequent management decisions was determined retrospectively. A major clinical impact was defined as a change in treatment plan resulting from identification of additional sites of disease or by characterisation of indeterminate findings on prior imaging. A minor impact was defined as confirmation of known sites of disease as identified on prior CECT.

Results

Fifty-one PET-CT examinations were performed. FDG PET-CT had a major clinical impact in 21 cases (41.2 %), of which 18 examinations were performed in patients with proven or suspected stage IV MM. FDG PET-CT had a minor impact in 23 cases (45.1 %), and there were five false-positive cases (9.8 %) and two false-negative cases (3.9 %).

Conclusion

FDG PET-CT is an effective tool in recurrent stage III/IV MM with a significant clinical impact on management decisions in patients who are appropriately referred via the highly specialised forum of the SSMDT.

Key Points

• FDG PET-CT is an effective tool in recurrent stage III/IV malignant melanoma.

• FDG PET-CT has a significant clinical impact on management decisions.

• Effective use of FDG PET-CT is via referral from the Specialist Skin Cancer Multidisciplinary Team.

F-18-fluoro-2-deoxyglucose positron emission tomography (PET) and PET/computed tomography imaging in primary staging of patients with malignant melanoma: a systematic review

PURPOSE

The aim of this systematic review was to systematically assess the potential patient-relevant benefit (primary aim) and diagnostic and prognostic accuracy (secondary aim) of positron emission tomography (PET) and PET/computed tomography (CT) in primary staging of malignant melanoma. This systematic review updates the previous evidence for PET(/CT) in malignant melanoma.

MATERIALS AND METHODS

For the first aim, randomized controlled trials (RCTs) investigating patient-relevant outcomes and comparing PET and PET(/CT) with each other or with conventional imaging were considered. For the secondary aim, a review of reviews was conducted, which was amended by an update search for primary studies. MEDLINE, EMBASE and four databases of the Cochrane Library were searched. The risk of bias was assessed using a modified QUADAS tool.

RESULTS

No RCTs investigating the patient-relevant benefit of PET(/CT) and no prognostic accuracy studies were found. Seventeen diagnostic accuracy studies of varying quality were identified. For patients with American Joint Committee on Cancer (AJCC) stages I and II, sensitivity mostly ranged from 0 to 67%. Specificity ranged from 77 to 100%. For AJCC stages III and IV, sensitivity ranged from 68 to 87% and specificity from 92 to 98%.

CONCLUSION

There is currently no evidence of a patient-relevant benefit of PET(/CT) in the primary staging of malignant melanoma. RCTs investigating patient-relevant outcomes are therefore required. The diagnostic accuracy of PET(/CT) appears to increase with higher AJCC stages.

Role of imaging methods in metastatic melanoma

Melanoma is a malignant neoplasm of the skin deriving from melanocytes. Accounting for less than 5% of all skin cancers, melanoma is associated with approximately 75% of skin cancer-related mortality. Early detection of melanoma with surgical resection remains one of the critical factors determining favorable clinical outcomes for melanoma. Up to now, many imaging methods, such as ultrasound, computed tomography (CT), magnetic resonance imaging, and positron emission tomography/CT, have been used in the diagnosis of melanoma and metastases. This article reviews the application of imaging methods in metastatic melanoma.

A multicenter prospective evaluation of the clinical utility of F-18 FDG-PET/CT in patients with AJCC stage IIIB or IIIC extremity melanoma

OBJECTIVE/BACKGROUND

There is a high risk of relapse in stage IIIB/IIIC melanoma. The utility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography integrated with computed tomography (FDG-PET/CT) in these patients to evaluate response to treatment or for surveillance after treatment is currently not well defined.

METHODS

Prospective data from 2 centers identified 97 patients with stage IIIB/IIIC extremity melanoma undergoing isolated limb infusion (ILI) who had whole body FDG-PET/CT scans before and every 3 months after treatment. Clinical response was determined at 3 months by Response Evaluation Criteria In Solid Tumors.

RESULTS

Complete response (CR) after ILI occurred in 33% (32/97) of patients. FDG-PET/CT accurately identified 59% of patients who were CRs (19/32), whereas 41% (13/32) had residual metabolic activity in the extremity that was histologically negative for melanoma. The 3-year disease-free rate was 62.2% (95% CI: 40.1%-96.4%) for those patients who were CRs by both clinical/pathologic examination and FDG-PET/CT (n = 19) compared to only 29.4% (95% CI: 9.9%-87.2%) of those CRs who still had residual FDG-PET/CT activity (n = 13). FDG-PET/CT was utilized for surveillance of disease recurrence outside the regional field of treatment. Fifty-two percent (51/97) of patients developed disease outside the extremity at a median time of 212 days from pre-ILI FDG-PET/CT. In 47% (29/62) of these cases, the recurrence was resected.

CONCLUSIONS

Although FDG-PET/CT does not appear to accurately identify patients who appear to be CRs to ILI, it does appear to identify a subgroup of patients whose regional progression-free survival is markedly worse. However, FDG-PET/CT appears to be an excellent method for surveillance in stage IIIB/IIIC patients after ILI with ability to identify surgically resectable recurrent disease in these high-risk patients.

Preoperative ultrasound is not useful for identifying nodal metastasis in melanoma patients undergoing sentinel node biopsy: preoperative ultrasound in clinically node-negative melanoma

BACKGROUND

Sentinel lymph node biopsy (SLNB) is widely used in melanoma. Identifying nodal involvement preoperatively by high-resolution ultrasound may offer less invasive staging. This study assessed feasibility and staging results of clinically targeted ultrasound (before lymphoscintigraphy) compared to SLNB.

METHODS

From 2005 to 2009, a total of 325 patients with melanoma underwent ultrasound before SLNB. We reviewed demographics and histopathologic characteristics, then compared ultrasound and SLNB results. Sensitivity, specificity, and positive and negative predictive value were determined.

RESULTS

A total of 325 patients were included, 58% men and 42% women with a median age of 58 (range 18-86) years. A total of 471 basins were examined with ultrasound. Only six patients (1.8%) avoided SLNB by undergoing ultrasound-guided fine-needle aspiration of involved nodes, then therapeutic lymphadenectomy. Sixty-five patients (20.4%) had 69 SLNB positive nodal basins; 17 nodal basins from 15 patients with positive ultrasounds were considered truly positive. Forty-five SLNB positive basins had negative ultrasounds (falsely negative). Seven node-positive basins did not undergo ultrasound because of unpredicted drainage. A total of 253 patients with negative SLNBs had negative ultrasounds in 240 nodal basins (truly negative) but falsely positive ultrasounds occurred in 40 basins. Overall, sensitivity of ultrasound was 33.8%, specificity 85.7%, positive predictive value 36.5%, and negative predictive value 84.2%. Sensitivity and specificity improved somewhat with increasing Breslow depth. Sensitivity was highest for the neck, but specificity was highest for the groin.

CONCLUSIONS

Routine preoperative ultrasound in clinically node-negative melanoma is impractical because of its low sensitivity. Selected patients with thick or ulcerated lesions may benefit. Because of variable lymphatic drainage patterns, preoperative ultrasound without lymphoscintigraphic localization will provide incomplete evaluation in many cases.

Current trends in regional therapy for melanoma: lessons learned from 225 regional chemotherapy treatments between 1995 and 2010 at a single institution

BACKGROUND

Hyperthermic isolated limb perfusion (HILP) and isolated limb infusion (ILI) are used to manage advanced extremity melanoma, but no consensus exists as to which treatment is preferable and how to monitor patients post-treatment.

STUDY DESIGN

Using a prospectively maintained database, we reviewed our experience with melphalan-based HILP (which included 62 first-time and 10 second-time) and ILI (which included 126 first-time and 18 second-time) procedures performed in 188 patients. PET/CT was obtained 3 months postregional treatment for 1 year and then every 6 months thereafter.

RESULTS

Overall response rate (complete response [CR] + partial response) of HILP was 81% (80% CI, 73-87%), and overall response rate from ILI was 43% (80% CI, 37-49%) for first-time procedures only. HILP had a CR rate of 55% with a median duration of 32 months, and ILI had a CR rate of 30% with median duration of 24 months. Patients who experienced a regional recurrence after initial regional treatment were more likely to achieve a CR after repeat HILP (50%, n = 10) compared with repeat ILI (28%, n = 18). Although the spectrum of toxicity was similar for ILI and HILP, the likelihood of rare catastrophic complication of limb loss was greater with HILP (2 of 62) than ILI (0 of 122). PET/CT was effective for surveillance after regional therapy to identify regional nodal and pulmonary disease that was not clinically evident, but often amenable to surgical resection (25 of 49; 51% of cases). In contrast, PET/CT was not effective at predicting complete response to treatment with an accuracy of only 50%.

CONCLUSIONS

In the largest single-institution regional therapy series reported to date, we found that although ILI is effective and well-tolerated, HILP is a more definitive way to control advanced disease.

Nuclear Medicine in Early-Stage Melanoma: Sentinel Node Biopsy-FDG-PET/CT

Sentinel node status is the most powerful prognostic factor in patients with early-stage melanoma. This review discusses several issues of clinical interest and technical points for an optimized sentinel node biopsy (SNB) procedure. The role of fluorodeoxyglucose positron emission tomography/computed tomography is clearly established in patients with suspicion of locoregional or distant recurrence of melanoma before any surgical decision. However, its role at initial staging or follow-up of patients with localized disease or with positive SNB is less clear. Further research and efforts should focus on identifying which groups of patients are at specific high risk of early distant recurrence.

Molecular imaging in oncology: the acceptance of PET/CT and the emergence of MR/PET imaging

In the last decade, PET-only systems have been phased out and replaced with PET-CT systems. This merger of a functional and anatomical imaging modality turned out to be extremely useful in clinical practice. Currently, PET-CT is a major diagnostic tool in oncology. At the dawn of the merger of MRI and PET, another breakthrough in clinical imaging is expected. The combination of these imaging modalities is challenging, but has particular features such as imaging biological processes at the same time in specific body locations.