FDG-PET sensitivity for melanoma lymph node metastases is dependent on tumor volume

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.

Diagnostic value of 18 F-fluoro-2-deoxyglucose positron emission tomography/computed tomography imaging in acral melanoma-predominant Asian patients

BACKGROUND

Tumor staging is crucial for melanoma, of which acral melanoma is the predominant subtype in Asians. 18 F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and 18 F-FDG-PET/computed tomography ( 18 F-FDG-PET/CT) serve as noninvasive imaging tools for tumor staging. However, the literature is scarce on the diagnostic value of PET for acral melanoma.

METHODS

From January 1, 2006 to November 30, 2022, a total of 352 patients were diagnosed with melanoma at our hospital. Of them, 90 were diagnosed with cutaneous melanoma and underwent preoperative PET/CT for staging and sentinel lymph node biopsy or complete lymph node dissection. Staging of PET/CT was confirmed by histopathology or following imaging. The lymph node biopsy, distant metastasis status, and PET/CT imaging results were analyzed.

RESULTS

Of all the 90 patients with cutaneous melanoma, 72 of them were diagnosed as acral melanoma (80.0%). Compared with the histopathologic results, the lymph nodes were true-positive, true-negative, false-positive, and false-negative in 12, 54, 7, and 17 cases, respectively. The sensitivity of PET/CT for local lymph nodes was 41.4% (95% CI, 23.5%-61.1%), whereas its specificity was 88.5% (95% CI, 77.8%-95.3%). As for the detection of distal metastasis, the PET results were true-positive, true-negative, false-positive, and false-negative in 6, 65, 15, and 4 cases, respectively. The sensitivity of PET for distal metastasis detection was 60.0% (95% CI, 26.2%-87.8%), whereas its specificity was 81.3% (95% CI, 71.0%-89.1%).

CONCLUSION

Although noninvasive, PET/CT has relatively low sensitivity in regional lymph node evaluations, and fair sensitivity in distal metastasis detection in Asian patients with acral melanoma. Thus, PET/CT may be more useful in patients with clinically palpable nodes or more advanced disease stages.

Prediction of Microscopic Metastases in Patients with Metachronous Oligo-Metastases after Curative Treatment of Non-Small Cell Lung Cancer: A Microsimulation Study

Simple Summary

Many patients with metachronous oligo-metastases in non-small cell lung cancer have their recurrences surgically removed, although the 5-year recurrence-free survival of this group is 16%. This does not provide any benefit for patients with additional undetected metastases. Therefore, we aim to find patient characteristics that are predictive for having additional undetected microscopic metastases. Based on a theoretical approach, we identified the size and number of detected oligo-metastases, as well as the presence of symptoms that are the most important risk predictors.

Abstract

Metachronous oligo-metastatic disease is variably defined as one to five metastases detected after a disease-free interval and treatment of the primary tumour with curative intent. Oligo-metastases in non-small cell lung cancer (NSCLC) are often treated with curative intent. However additional metastases are often detected later in time, and the 5-year survival is low. Burdensome surgical treatment in patients with undetected metastases may be avoided if patients with a high versus low risk of undetected metastases can be separated. Because there is no clinical data on undetected metastases available, a microsimulation model of the development and detection of metastases in 100,000 hypothetical stage I NSCLC patients with a controlled primary tumour was constructed. The model uses data from the literature as well as patient-level data. Calibration was used for the unobservable model parameters. Metastases can be detected by a scheduled scan, or an unplanned scan when the patient develops symptoms. The observable information at time of detection is used to identify subgroups of patients with a different risk of undetectable metastases. We identified the size and number of detected oligo-metastases, as well as the presence of symptoms that are the most important risk predictors. Based on these predictors, patients could be divided into a low-risk and a high-risk group, having a model-based predicted probability of 8.1% and 89.3% to have undetected metastases, respectively. Currently, the model is based on a synthesis of the literature data and individual patient-level data that were not collected for the purpose of this study. Optimization and validation of the model is necessary to allow clinical usability. We describe the type of data that needs to be collected to update our model, as well as the design of such a validation study.

The role of FDG-PET-CT is limited in initial staging of nodal metastasis for thin cutaneous melanoma

INTRODUCTION

Positron emission tomography computed tomography (PET-CT) is often used to stage nodal metastases in thin cutaneous melanoma, with limited evidence.

METHODS

A retrospective review of patients with cutaneous malignant melanoma treated at our institution was performed from 2005 to 2015, identifying those who received a PET-CT prior to lymphadenectomy. Biopsy features, lymph node status, and PET-CT results were collected. We calculated the overall sensitivity, specificity, accuracy, likelihood ratios, and positive predictive value of PET-CT in identifying nodal metastases. Results were stratified by initial biopsy tumor depth.

RESULTS

We identified 367 cases; 95 obtained a PET-CT prior to lymphadenectomy. Overall, sensitivity and specificity of PET-CT was 34.6% and 95.4%, respectively. The positive likelihood ratio and negative likelihood ratio were 7.62 and 0.68, respectively. The accuracy was 78.2%. The positive predictive value for T3 and T4 melanomas were 100% and 81.4%, respectively. For thin melanomas, specificity and accuracy was 88.2% and 88.2%, respectively.

CONCLUSIONS

PET-CT has low specificity and its use alone is not recommended for initial staging of nodal metastases in thin cutaneous malignant melanoma.

Pretreatment tumor-related leukocytosis misleads positron emission tomography-computed tomography during lymph node staging in gynecological malignancies

The accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET/CT) can be influenced by the increased glycolytic activity of inflammatory lesions. Here, using clinical data obtained from gynecological cancer patients, tumor samples and animal models, we investigate the impact of pretreatment tumor-related leukocytosis (TRL) on the diagnostic performance of 18F-FDG-PET/CT in detecting pelvic and paraaortic lymph node metastasis. We demonstrate that pretreatment TRL misleads 18F-FDG-PET/CT during lymph node staging in gynecological malignancies. In the mechanistic investigations, we show that the false-positive 18F-FDG-PET/CT result for detecting nodal metastasis can be reproduced in animal models of TRL-positive cancer bearing G-CSF expressing cervical cancer cells. We also show that increased 18F-FDG uptake in non-metastatic nodes can be explained by the MDSC-mediated premetastatic niche formation in which proinflammatory factors, such as S100A8 or S100A9, are abundantly expressed. Together, our results suggest that the MDSC-mediated premetastatic niche created in the lymph node of TRL-positive patients misleads 18F-FDG-PET/CT for detecting nodal metastasis.

Detection of Lymph Node Metastases by Ultra-pH-Sensitive Polymeric Nanoparticles

Lymph node (LN) dissection followed by histological analysis is the current standard for diagnosis of LN metastasis but the method suffers from patient morbidity and low sensitivity of detection. Ultra-pH sensitive (UPS) nanoparticles show remarkable accuracy in the delineation of primary tumor margins for precision cancer surgery. Herein we investigate the effectiveness of UPS nanoparticles to detect cancer-involved LNs. Methods: We synthesized a series of indocyanine green (ICG) conjugated UPS nanoparticles with distinct pK_a (UPS_5.3, UPS_6.1, and UPS_6.9). Systemically administered UPS-ICG nanoparticles in the 4T1.2-BALB/cj mouse model were imaged with real-time, near-infrared fluorescence (NIRF) to guide removal of LNs. Ex vivo imaging of gross tissue enabled quantification of fluorescence intensity. Histological analysis was used as the gold standard diagnostic test. Results: Macrophage uptake of UPS nanoparticles elevates the background signal in benign LNs. However, cancer foci within LNs show distinctive clustering of UPS-ICG fluorescence. UPS_5.3 achieves accurate detection of metastatic LNs as shown by a receiver operating characteristic (ROC) area under the curve (AUC) of 0.96 ± 0.03. UPS_6.1 and UPS_6.9 offer decreased discriminatory power at ROC AUC of 0.73 ± 0.1 and 0.88 ± 0.07, respectively. Conclusions: All UPS compositions show cancer-specific discrimination of metastatic LNs over benign LNs with the best outcomes from UPS_5.3. Detection of micro-metastatic LNs (cancer foci < 2 mm) remains a challenge. This study provides information on the detection of LN status for image-guided resection of metastatic LNs.

Surgical management of the neck in patients with metastatic melanoma in parotid lymph nodes

BACKGROUND

The role and extent of neck dissection in patients with parotid metastatic cutaneous head and neck melanoma remain unclear. The aims of this study were to determine the incidence and patterns of cervical node involvement in patients with parotid metastatic melanoma, and to determine if a limited lymphadenectomy of the clinically negative neck is appropriate.

METHODS

Patients who underwent parotidectomy and neck dissection for clinically apparent parotid metastatic melanoma, irrespective of neck status, were identified from two prospectively maintained databases.

RESULTS

A total of 276 patients fulfilled the study criteria. Median follow-up was 23 months. A total of 185 necks were clinically negative, 82 were clinically positive. A total of 36 elective neck-dissection specimens harbored occult metastases; these were found in levels I (16.7%), II (58.3%), III (36.1%), IV (13.9%), and V (30.6%). Regional recurrence occurred in 32 patients with a clinically negative neck, the majority being in-transit metastases (n = 15). Only one case of recurrence could have potentially been avoided by a comprehensive lymphadenectomy.

CONCLUSIONS

In patients with clinically apparent parotid melanoma metastases, elective comprehensive neck dissection reduces failure rates in cervical nodes, and provides more accurate staging and prognostic information. However, our findings support the emerging trend for more limited elective neck dissection. Levels I and IV can probably be safely omitted.

Imaging of pediatric cutaneous melanoma

Melanoma accounts for 7% of all cancers in adolescents ages 15-19 years but is an unexpected malignancy in younger children. The prevalence of malignant melanoma is very rare in children ages 1-4 years, but certain non-modifiable risk factors such as xeroderma pigmentosum, congenital melanocytic nevus syndrome and other inherited traits increase the risk for its development in these young children. Recent genomic studies have identified characteristics of pediatric melanoma that differ from conventional melanoma seen in adults. In this review the authors inform on the types of melanoma seen in children and adolescents, discuss similarities and differences in melanoma between children and adults, and discuss the role of imaging in the care of these children.

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.

Bridging from Brain to Tumor Imaging: (S)-(-)- and (R)-(+)-[18F]Fluspidine for Investigation of Sigma-1 Receptors in Tumor-Bearing Mice

Sigma-1 receptors (Sig1R) are highly expressed in various human cancer cells and hence imaging of this target with positron emission tomography (PET) can contribute to a better understanding of tumor pathophysiology and support the development of antineoplastic drugs. Two Sig1R-specific radiolabeled enantiomers (S)-(-)- and (R)-(+)-[18F]fluspidine were investigated in several tumor cell lines including melanoma, squamous cell/epidermoid carcinoma, prostate carcinoma, and glioblastoma. Dynamic PET scans were performed in mice to investigate the suitability of both radiotracers for tumor imaging. The Sig1R expression in the respective tumors was confirmed by Western blot. Rather low radiotracer uptake was found in heterotopically (subcutaneously) implanted tumors. Therefore, a brain tumor model (U87-MG) with orthotopic implantation was chosen to investigate the suitability of the two Sig1R radiotracers for brain tumor imaging. High tumor uptake as well as a favorable tumor-to-background ratio was found. These results suggest that Sig1R PET imaging of brain tumors with [18F]fluspidine could be possible. Further studies with this tumor model will be performed to confirm specific binding and the integrity of the blood-brain barrier (BBB).

PET Scan Misses Cutaneous Melanoma Metastasis with Significant Tumour Size and Tumour Thickness

BACKGROUND

Although PET-scan is an advanced, innovative and widely used method for monitoring patients with different types of cancer diseases, it is important to note that its application in patients with cutaneous melanoma is limited and should be reconsidered.

CASE REPORT

To affirm this new statement, we are presenting a case from our clinical practice of a patient with melanoma of the interdigital space (with resected in sano primary melanoma and performed complete lymphadenectomy) that showed locoregional and systemic progression in two months post operation. The PET scan performed within the second hospitalization (and before the second operation) did not detect the presence of any cutaneous metastases, which were clinically and histologically verified after the second operative procedure.

CONCLUSIONS

This data suggests that shortly more reliable and sensitive imaging methods for monitoring patients with cutaneous melanoma should be found. Having in mind that our patient has been operated twice in the area of the primary lesion (as the surgical wound underwent secondary healing), theoretically, the abundant cicatrization could have led to reduced glucose uptake in the surrounded cancerous tissue. Monitoring of a larger number of patients with locoregional metastases and surgical interventions in different locations would shed light on the observations shared by us.

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.

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.

Radioactive seed localization for excision of non-palpable in-transit metastatic melanoma

We report the case of a 73-year-old who presented with multiple, small, in-transit melanoma nodules located in her right lower extremity below her knee. Positron emission tomography detected two additional non-palpable subcutaneous lesions posterior and medial to the area of previous wide local excision. A novel approach of radioactive seed localization was employed to guide the surgeon to successful surgical resection of all metastatic disease. To our knowledge, the application of radioactive seed localization to melanoma has not been previously reported.

Label-free Detection of Lymph Node Metastases with US-guided Functional Photoacoustic Imaging

PURPOSE

To determine the ability of ultrasonography (US)-guided spectroscopic photoacoustic (sPA) imaging to depict changes in blood oxygen saturation (SO2) in metastatic lymph nodes of a mouse model of oral cancer.

MATERIALS AND METHODS

All studies were performed by following protocols approved by the institutional animal care and use committee at the University of Texas at Austin. Coregistered US and photoacoustic images were acquired spanning volumes containing a total of 31 lymph nodes in 17 female nu/nu mice. The mice were either healthy (three mice, five nodes) or bearing a primary tumor consisting of luciferase-labeled FaDu cells (14 mice, 26 nodes). Ten photoacoustic images acquired with optical wavelengths spanning from 680 to 860 nm were spectrally unmixed by using a linear least-squares method to obtain sPA images. After imaging, histologic analysis enabled confirmation of the presence of micrometastases. Generalized estimating equations were used to compare metastatic and normal lymph nodes, with a P value of .05 taken to indicate a significant difference. Sensitivity and specificity were determined with a receiver operator characteristic curve constructed from the background-subtracted SO2 values.

RESULTS

Metastatic lymph nodes (n = 7) exhibited a significantly (P = .018) lower spatially averaged background-subtracted SO2 (mean, 5.4% ± 3.5 [standard error]) when compared with lymph nodes without metastases (mean, 13.7% ± 1.3; n = 24). This effect was observed throughout the entire volume of the nodes rather than being limited to the metastatic foci. The change in SO2, which was inversely related to the size of the metastasis, was detectable in metastases as small as 2.6 × 10(-3) mm(3).

CONCLUSION

The results show that US-guided sPA imaging is capable of depicting changes in SO2 in lymph nodes that were correlated with metastatic invasion.

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.

Sentinel lymph node biopsy revisited: ultrasound-guided photoacoustic detection of micrometastases using molecularly targeted plasmonic nanosensors

Metastases rather than primary tumors are responsible for killing most patients with cancer. Cancer cells often invade regional lymph nodes (LN) before colonizing other parts of the body. However, due to the low sensitivity and specificity of current imaging methods to detect localized nodal spread, an invasive surgical procedure--sentinel LN biopsy--is generally used to identify metastatic cancer cells. Here, we introduce a new approach for more sensitive in vivo detection of LN micrometastases, based on the use of ultrasound-guided spectroscopic photoacoustic (sPA) imaging of molecularly activated plasmonic nanosensors (MAPS). Using a metastatic murine model of oral squamous cell carcinoma, we showed that MAPS targeted to the epidermal growth factor receptor shifted their optical absorption spectrum to the red-near-infrared region after specific interactions with nodal metastatic cells, enabling their noninvasive detection by sPA. Notably, LN metastases as small as 50 μm were detected at centimeter-depth range with high sensitivity and specificity. Large sPA signals appeared in metastatic LN within 30 minutes of MAPS injection, in support of the clinical utility of this method. Our findings offer a rapid and effective tool to noninvasively identify micrometastases as an alternate to sentinal node biopsy analysis.

Preoperative imaging for early-stage cutaneous melanoma: predictors, usage, and utility at a single institution

BACKGROUND

Preoperative imaging for early-stage cutaneous melanoma is not recommended by current guidelines. Our goal was to investigate our institutional usage and utility.

METHODS

Patients with clinically node-negative cutaneous melanoma undergoing surgery with sentinel lymph node biopsy were identified retrospectively. Any melanoma-related imaging after diagnosis and before surgery was considered a staging study.

RESULTS

Five hundred fifteen studies were performed in 409 of 546 (75%) patients. Chest x-rays was performed in 70% and advanced imaging in 14% (computed tomography imaging, magnetic resonance imaging, ultrasound, and positron-emission computed tomography imaging). No metastatic lesions were identified. A Breslow thickness greater than 4 mm (odds ratio = 6.46 vs <1 mm; 95% confidence interval, 2.07 to 20.15) and male sex (odds ratio = 2.62 vs female; 95% confidence interval, 1.26 to 5.46) were associated with an increased likelihood of advanced imaging.

CONCLUSIONS

Preoperative imaging was performed in the majority of patients with node-negative melanoma, with 14% undergoing advanced studies. No metastatic lesions were identified, confirming the limited utility in this setting.

Role of high-resolution ultrasound and PET/CT imaging for preoperative characterization of sentinel lymph nodes in cutaneous melanoma

The purpose of our study was the comparison of high-resolution ultrasound (HRUS) and positron emission tomography combined with computerised tomography (PET/CT) in the preoperative characterization and identification of subclinical nodal metastases focusing on sentinel lymph nodes (SLN) in melanoma patients. Patients with cutaneous melanoma (CM) who received sentinel lymph node biopsy at the Department of Dermatology and Allergy, University of Bonn, between January 2009 and January 2011 had been evaluated with a retrospective computer-aided search concerning preoperative staging procedures. A combination of PET/CT and HRUS had been performed preoperatively in 20 of 123 patients. A total of 59 SLNs had been removed in those 20 patients followed by histopathologic examination. HRUS correctly identified two of 17 positive SLNs whereas PET/CT imaging identified none. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HRUS were 11.8 % (95 % confidence interval [CI] = 3.3-34.3), 100 % (95 % CI = 91.6-100.0), 100.0 % (95 % CI = 34.2-100.0), and 73.7 % (95 % CI = 61.0-83.3), respectively. On the basis of this limited study cohort, HRUS had a better value than PET/CT in preoperative identification of positive SLNs, suggesting a possible diagnostic superiority of HRUS in general characterization of peripheral nodal disease in CM.

Metabolic positron emission tomography imaging in cancer detection and therapy response

Positron emission tomography (PET) is a noninvasive imaging technique that provides a functional or metabolic assessment of normal tissue or disease conditions. Fluorine 18-fluorodeoxyglucose PET imaging (FDG-PET) is widely used clinically for tumor imaging due to increased glucose metabolism in most types of tumors, and has been shown to improve the diagnosis and subsequent treatment of cancers. We review its use in cancer diagnosis, staging, restaging, and assessment of response to treatment. In addition, other metabolic PET imaging agents in pre-clinical research or clinical trial stages of development are discussed, including amino acid analogs based on increased protein synthesis, and choline, which is based on increased membrane lipid synthesis. Amino acid analogs and choline are more specific to tumor cells than FDG, so they play an important role in differentiating cancers from benign conditions and in the diagnosis of cancers with low FDG uptake or high background FDG uptake. For decades, researchers have shown that tumors display altered metabolic profiles with elevated uptake of glucose, amino acids, and lipids. This can be used for cancer diagnosis and monitoring of the therapeutic response with excellent signal-to-noise ratios.

Whole body positron emission tomography in follow-up of high risk melanoma

The aim of this study was to determine the clinical impact of whole body positron emission tomography (FDG PET) to detect clinically silent metastases in the follow-up of patients with high risk melanoma. FDG PET was performed to 30 asymptomatic melanoma patients (AJCC stage IIB-IIIC) 7-24 months after the primary surgery and sentinel node biopsy. FDG PET was able to detect six of seven recurrences, constituting 20% of all study patients. One patient presented with a negative FDG PET finding at the very first scanning, but was positive later in a repeated scan after manifestation of palpable mass in the axilla. The positive PET finding had an impact on treatment decisions in every case: three patients underwent surgical resection and four patients received chemotherapy or interferon. The mean follow-up time was 27 months (range, 12-48 months) and during that time the other 23 patients with true negative FDG PET were disease-free. One of the seven recurrences was in remission after surgical metastasectomy. In conclusion, whole body FDG PET is a valuable follow-up tool in high risk melanoma to diagnose recurrences and to select the patients, who are suitable for surgical metastasectomy.

Non-invasive molecular imaging of prostate cancer lymph node metastasis

Imaging in medicine has been classically based on the anatomical description of organs. In the past 15 years, new imaging techniques based on gene expression that characterize a pathological process have been developed. Molecular imaging is the use of such molecules to image cell-specific characteristics. Here, we review recent advances in molecular imaging, taking as our prime example lymph node (LN) metastasis in prostate cancer. We describe the new techniques and compare their accuracy in detecting LN metastasis in prostate cancer. We also present new molecular strategies for improving tumor detection using adenoviruses, molecular promoters and amplification systems. Finally, we present the concept of 'in vivo pathology', which envisages using molecular imaging to accurately localize metastatic lesions based on the molecular signature of the disease.

PET vs sentinel lymph node biopsy for staging melanoma: a patient intervention, comparison, outcome analysis

BACKGROUND

Sentinel lymph node biopsy (SLNB) is the gold standard to assess local lymph nodes in patients with melanoma. Positron emission tomography (PET) has been investigated as a noninvasive alternative to SLNB.

METHODS

A systematic literature review was conducted to evaluate PET and PET/computed tomography (CT) compared with SLNB for staging local lymph nodes in patients with intermediate-risk melanoma using the patient, intervention, comparison, outcome (PICO) search strategy. The PubMed, Medline, CancerLit, and Cochrane Library databases were searched for relevant published materials. Guidelines of the American Society of Clinical Oncology (ASCO), and Cancer Care Ontario (CCO) were reviewed, as was the clinical resource, UpToDate. Studies were classified on the basis of levels of evidence delineated by the Oxford Centre for Evidence-Based Medicine.

RESULTS

The PICO search criteria identified 20 studies. There was no level 1 evidence. There were 7 level 2b articles. One review article was consecutive and thus classified as level 3a evidence. Three review articles were retrieved and categorized as level 3b. Three single-center studies were classified as level 3b, and another 3 were classified as level 4. There were two published letters, considered expert opinion and thus classified as level 5 evidence. All identified papers favored SLNB over PET or PET/CT for identifying occult locoregional lymph node metastases.

CONCLUSION

Despite a lack of high-level evidence, the studies concluded that SLNB is superior to PET for local lymph node staging in patients with intermediate-risk melanoma. National guidelines confirmed these conclusions. The likelihood of PET/CT identifying distant metastases in this patient population is equally low because of the small risk for having distant metastases at diagnosis. Further study is required, including larger multicenter prospective trials.

Role of radiologic imaging at the time of initial diagnosis of stage T1b-T3b melanoma

BACKGROUND

In patients with T1b-T3b cutaneous melanoma the utility of radiologic imaging at the time of diagnosis is unclear. Whether initial imaging led to a change in stage or treatment plan was investigated.

METHODS

The melanoma database was searched for patients with T1b-T3b primary lesions, clinically N0, and asymptomatic for metastatic disease. Radiologic studies conducted before wide local excision +/- sentinel lymph node biopsy as well as all further imaging and investigations were analyzed. Outcome measures included upstaging, change in initial surgical management, true-positive, false-positive, true-negative, and false-negative rates of each imaging modality.

RESULTS

In all, 344 preoperative imaging studies (chest x-ray [CXR], computed tomography [CT], positron emission tomography [PET]/CT) were performed on 158 patients, resulting in 49 findings suspicious for metastatic melanoma and 134 findings suggestive of nonmelanoma pathology. Only 1 of 344 (0.3%) studies, a PET/CT, correlated with confirmed metastatic melanoma. The false-positive rates were CXR 5 of 7 (71.4%), chest CT 21 of 24 (87.5%), abdomen/pelvis CT 10 of 11 (90.9%), head CT 2 of 2 (100.0%), PET/CT 3 of 5 (60.0%). No patient was upstaged or had a change in initial surgical management based on preoperative imaging. The cost of all initial imaging and imaging to follow-up abnormal findings was estimated as $555,308 for the 158 patients studied.

CONCLUSIONS

Imaging at the time of initial diagnosis of T1b-T3b, clinically N0, M0 melanoma was of low yield with a high false-positive rate, and did not lead to upstaging or change in initial surgical management. These findings suggest that imaging of asymptomatic patients at the time of diagnosis may not be warranted.

High-Risk Melanoma: Accuracy of FDG PET/CT with Added CT Morphologic Information for Detection of Metastases

PURPOSE

To prospectively determine the accuracy of positron emission tomography (PET)/computed tomography (CT) with added CT morphologic information for depiction of metastases in patients with high-risk melanoma and negative findings for metastases at PET, by using histologic findings or additional imaging and/or follow-up findings as reference standard.

MATERIALS AND METHODS

Institutional review board approval was obtained. Informed consent was obtained from patients. One hundred twenty-four consecutive high-risk melanoma patients (65 female, 59 male; mean age, 54.4 years; range, 15-82 years) were included. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT was performed. First, PET/CT scans were evaluated for presence of metastases with increased FDG uptake; CT anatomic location was determined. Lesions were considered metastases if there was focal uptake higher than that of background tissue. Second, coregistered CT images of combined PET/CT scans were evaluated for presence of lesions without FDG uptake. Findings were compared with reference standard findings to determine the accuracy of each evaluation. McNemar test was used to assess statistical differences in accuracy.

RESULTS

In 53 of 124 patients, metastases were found. In 46 of 53 patients with metastases, lesions had increased FDG uptake. In seven patients with metastatic disease, metastases did not have increased FDG uptake (maximum standard uptake value [SUV], <1.5; n = 5) or had faint FDG uptake (maximum SUV, 2.5 and 2.9; n = 2)-findings that were inconclusive with PET alone. These lesions were interpreted as metastases only with coregistered CT images. Lesions missed with PET were located in the lungs, iliac lymph nodes, subcutis, and psoas muscle. Sensitivity, specificity, and accuracy, respectively, of PET/CT for depiction of metastases were 85%, 96%, and 91%, and those of PET/CT with dedicated CT interpretation were 98%, 94%, and 96% (P = .016).

CONCLUSION

Dedicated analysis of coregistered CT images significantly improves the accuracy of integrated PET/CT for depiction of metastases in patients with high-risk melanoma.

F-18 fluorodeoxy-D-glucose positron emission tomography scan in the initial evaluation of patients with a primary melanoma thicker than 4 mm

Metabolic imaging with F-18 fluorodeoxy-D-glucose positron emission tomography is one of the most sensitive and non-invasive techniques, and has proved useful in melanoma. We designed, in 2004, at the Institute Gustave Roussy, a prospective study to determine the value of F-18 fluorodeoxy-D-glucose positron emission tomography scanning in the detection of regional and/or distant metastasis in 25 new patients referred for the treatment of a primary melanoma thicker than 4 mm (tumor node metastases stage T4). The sentinel lymph node biopsy was proposed for all the patients without a palpable regional lymph node. Abnormal positron emission tomography scan findings were correlated to available histological data and to the course of the disease. The F-18 fluorodeoxy-D-glucose positron emission tomography scan identified 0/2 intact primary melanomas, 1/4 residual primary melanomas after limited excision, 0/6 lymph node basins with micrometastasis, 4/4 lymph node basins with enlarged palpable lymph nodes and 0 distant metastasis. The sensitivity and specificity of positron emission tomography scans for microscopic lymph node disease in basins were, respectively, 0 and 92%. A false-positive F-18 fluorodeoxy-D-glucose positron emission tomography result in a cervical basin led to a useless cervical lymph node dissection. In three patients, the positron emission tomography scan was positive in distant sites but none of these foci represented a true metastasis. In conclusion, it is not useful to include a positron emission tomography scan in the initial work-up of patients with primary melanoma, even in patients with thick primary melanomas (>4 mm). Sentinel lymph node biopsy remains the technique of choice for the most accurate initial staging.

Imaging Studies in Patients with Melanoma

The incidence of malignant cutaneous melanoma is rising. Imaging studies represent a major component of the staging work-up and follow-up of melanoma patients and are used to facilitate preoperative planning and intraoperative management. Study benefits are not clear, and evidence does not support any particular protocol for their use. The National Comprehensive Cancer Network's updated guidelines for use of imaging studies in melanoma patients represent a consensus based on lower level evidence, including clinical experience. The utility of individual imaging studies in melanoma patients depends on disease stage. Chest radiography, CT, MRI, lymphoscintigraphy, ultrasonography, PET, and PET/CT have specific roles in patient evaluation. Clinicians must use available evidence to guide decisions regarding which imaging modalities are appropriate for a given indication.

Tumour assessment in advanced melanoma: value of FDG-PET/CT in patients with elevated serum S-100B

PURPOSE

To evaluate the usefulness of PET/CT in melanoma patients with an elevated serum S-100B tumour marker level.

METHODS

Out of 165 consecutive high-risk melanoma patients referred for PET/CT imaging, 47 had elevated (>0.2 microg/l) S-100B serum levels and a contemporaneous 18F-FDG PET/CT scan. PET/CT scans were evaluated for the presence of metastases. To produce a composite reference standard, we used cytological, histological, MRI and PET/CT follow-up findings as well as clinical and S-100B follow-up.

RESULTS

Among the 47 patients with increased S-100B levels, PET/CT correctly identified metastases in 38 (30 distant metastases and eight lymph node metastases). In one patient with cervical lymph node metastases, PET/CT was negative. Eight patients had no metastases and PET/CT correctly excluded metastases in all of them. Overall sensitivity for metastases was 97% (38/39), specificity 100% (8/8) and accuracy 98% (46/47). S-100B was significantly higher in patients with distant metastases (mean 1.93 microg/l, range 0.3-14.3 microg/l) than in patients with lymph node metastases (mean 0.49 microg/l, range 0.3-1.6 microg/l, p=0.003) or patients without metastases (mean 0.625 microg/l, range 0.3-2.6 microg/l, p=0.007). However, 6 of 14 patients with a tumour marker level of 0.3 microg/l had no metastases.

CONCLUSION

In melanoma patients with elevated S-100B tumour marker levels, FDG-PET/CT accurately identifies lymph node or distant metastases and reliably excludes metastases. Because of the significant number of false positive S-100B tumour marker determinations (17%), we recommend repetition of tumour marker measurements if elevated S-100B levels occur before extensive imaging is used.

PET CT imaging in patients undergoing sentinel node biopsy for melanoma

AIMS

Sentinel lymph node biopsy (SLNB) has been adopted in the surgical treatment of melanoma to reduce morbidity and enhance staging. Positron emission tomography with computerised tomography (PET/CT) has been utilised in the staging of patients with malignancy though the role of this imaging modality in early stage melanoma is unclear. This study examined the preoperative value of PET/CT in patients undergoing SLNB for malignant melanoma.

METHODS

Patients presenting with primary melanoma without evidence of either locoregional or systemic metastasis were considered candidates for SLNB. Selected patients underwent preoperative PET/CT followed by definitive surgical therapy including SLNB with regional lymphadenectomy, where indicated.

RESULTS

During a 12-month period 83 patients were identified as having undergone SLNB for melanoma, of which 37 (45%) had preoperative PET/CT. Mean melanoma thickness 1.9 mm and 2.4 mm (PET/CT vs. no PET/CT, p>0.05). 13 (15.6%) patients were found to have lymphatic metastasis at SLNB; nine of these patients underwent PET/CT, only two of these scans were suggestive of lymphatic metastasis (positive predictive value 24%, negative predictive value 76%). PET/CT revealed no unheralded metastatic disease but did identify a second occult malignancy in 4 (10.8%) patients undergoing therapy for melanoma.

CONCLUSIONS

The results of this study do not support the use of PET/CT in patients undergoing SLNB for melanoma. SLNB appears to be a more sensitive staging modality in the detection of lymphatic metastasis; however PET/CT may have a future role as a screening tool for malignancy.

Utility of Computed Tomography and Magnetic Resonance Imaging Staging Before Completion Lymphadenectomy in Patients With Sentinel Lymph Node–Positive Melanoma

Purpose

Although melanoma patients with regional nodal metastases are frequently imaged with computed tomography (CT) and magnetic resonance imaging (MRI) scans, the efficacy of routine radiologic staging in asymptomatic patients with microscopic nodal involvement has not been established. To determine the utility of this approach, we analyzed the incidence of synchronous distant metastases (SDM) detected by CT or MRI of the head, chest, and abdomen in a large group of patients with sentinel lymph node (SLN) –positive melanoma.

Patients and Methods

Positive SLNs were identified in 314 (16.2%) of the 1,934 melanoma patients who underwent sentinel lymphadenectomy at our institution from 1996 to 2003. Within 3 months of sentinel lymphadenectomy, 270 (86.0%) of the 314 SLN-positive patients were radiologically staged. To determine which prognostic factors were associated with SDM, associations between final staging outcomes and clinicopathologic variables, including SLN tumor burden, were analyzed.

Results

CT and/or MRI scans identified lesions that were suspicious for SDM in 23 (8.6%) of the 270 patients who underwent staging. In eight of these patients, further diagnostic studies determined that these abnormalities were benign. The remaining 15 suspicious lesions were percutaneously biopsied (10 negative and five positive), yielding a radiologically detectable SDM rate of 1.9%. Detection of SDM was associated with primary tumor thickness (P = .011), ulceration (P = .018), and SLN tumor burden (P = .018).

Conclusion

These data suggest that the vast majority of asymptomatic patients with a new diagnosis of microscopic SLN-positive melanoma do not harbor radiologically detectable SDM and can proceed to completion lymph node dissection without immediate CT or MRI staging.