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Journal of Clinical Oncology, Vol 24, No 7 (March 1), 2006: pp. 1178-1187 © 2006 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.03.5634 Diagnostic Performance of Whole Body Dual Modality 18F-FDG PET/CT Imaging for N- and M-Staging of Malignant Melanoma: Experience With 250 Consecutive PatientsFrom the Departments of Nuclear Medicine, Radiology, and Dermatology, University Hospital Bonn, Bonn, Germany Address reprint requests to Michael J. Reinhardt, MD, Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany; e-mail: michael.reinhardt{at}ukb.uni-bonn.de
PURPOSE: To assess the diagnostic performance of positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG) for N- and M-staging of cutaneous melanoma. PATIENTS AND METHODS: This is a retrospective and blinded study of 250 consecutive patients (105 women, 145 men; age 58 ± 16 years) who underwent FDG-PET/CT for staging of cutaneous melanoma at different time points in the course of disease. Whole-body FDG-PET/CT was performed 101 ± 21 minutes postinjection of 371 ± 41 MBq FDG. Diagnostic accuracy for N- and M-staging was determined for CT alone, PET alone, and PET/CT. RESULTS: PET/CT detected significantly more visceral and nonvisceral metastases than PET alone and CT alone (98.7%, 88.8%, and 69.7%, respectively). PET/CT imaging thus provided significantly more accurate interpretations regarding overall N- and M-staging than PET alone and CT alone. Overall N- and M-stage was correctly determined by PET/CT in 243 of 250 patients (97.2%; 95% CI, 95.2% to 99.4%) compared with 232 patients (92.8%; 95% CI, 89.6% to 96.0%) by PET, and 197 patients (78.8%; 95% CI, 73.7% to 83.9%) by CT. All differences were significant. Accuracy of PET/CT was significantly higher than that of PET and CT for M-staging (0.98 v 0.93 and 0.84) and significantly higher than that of CT for N-Staging (0.98 v 0.86). Change of treatment according to PET/CT findings occurred in 121 patients (48.4%). CONCLUSION: The diagnostic performance of FDG-PET/CT for N- and M-staging of melanoma patients suggests its use for whole-body tumor staging, especially for detection or exclusion of distant metastases.
The incidence of malignant melanoma is increasing dramatically in people with light-colored skin in all parts of the world.1 In 2004, an estimated 55,000 Americans were diagnosed with cutaneous melanoma, and 7,900 died from the disease.2 Fortunately, most new patients are diagnosed early in the clinical course of disease, when it can be cured with excision of the primary tumor and sentinel lymphadenectomy. Histologic confirmation of diagnosis and microstaging with an accurate tumor thickness are essential before embarking on treatment.3,4 Invasive primary melanomas to a depth of  2.0 mm without ulceration and negative nodal metastases are essentially curable, whereas melanomas of increasing depth become progressively less curable.4,5 Thus, the relationship between tumor thickness and 10-year survival rates is pivotal.5,6 Once a melanoma has acquired the ability to invade tissues, to continue to proliferate, and to escape immune recognition, metastatic spread is possible. Melanoma cells usually present with a high uptake of the glucose analog 18F-fluorodeoxyglucose (FDG).7,8 This high FDG uptake and the unpredictable metastatic spread of cutaneous melanoma are best conditions for functional imaging with whole-body positron emission tomography (PET) using FDG.9,10 Unfortunately, FDG-PET has shown a limited sensitivity for initial regional staging, especially in American Joint Committee on Cancer (AJCC) stage I and II disease because sentinel node biopsy is much more sensitive in detecting microscopic lymph node metastases.11,12 However, FDG-PET performance significantly improved for regional staging of AJCC stage III and stage IV disease, with a positive predictive value of up to 90%, and for detection and differentiation of distant metastases.10,12 The use of computed tomography (CT) is suggested for assessment of the extent of lymph node involvement and to indicate whether systemic metastatic disease is present, if there is clinical evidence of metastatic disease in regional lymph nodes at presentation.1,13 Similar as with PET, the yield of CT in patients with only microscopic metastases is limited.14 If evidence of systemic metastasis is obtained, full staging with thorax and abdomen CT, brain magnetic resonance imaging (MRI), or whole-body FDG-PET is warranted, because sometimes metastases that may be resectable with curative intent will be identified.1,13 The combination of functional and morphologic imaging using the new dual-modality PET/CT is supposed to provide superior performance in overall TNM staging of various oncologic diseases and to be significantly more accurate than CT alone and/or PET alone.15,16 The performance of PET/CT for staging of melanoma patients is currently unknown. Thus, the aim of our study was to assess the diagnostic accuracy of FDG-PET/CT for N- and M-staging of cutaneous melanoma.
Patients Whole-body FDG-PET/CT imaging was performed in 255 consecutive patients who were referred from the department of dermatology for staging of cutaneous melanoma in a university hospital setting from November 2002 until June 2004. All melanoma patients undergoing PET/CT imaging during that period were included in this study. Only five patients had to be excluded from additional evaluation due to a lack of confirming data for suspected metastatic disease or insufficient follow-up of at least 1 year. Thus, the present retrospective analysis is based on 250 melanoma patients (105 women, 145 men; age 58 ± 16 years). In detail, these were 113 nodular melanomas, 81 superficial spreading melanomas, 27 acral lentiginous melanomas, six lentigo maligna melanomas, and 23 occult melanomas. Tumor depth was 1.0 mm in 29 patients, 1.01 to 2.0 mm in 68 patients, 2.01 to 4.0 mm in 66 patients, and greater than 4.0 mm in 64 patients. Staging of melanoma patients was performed according to the AJCC staging classification.5 Initial pathology staging showed AJCC stage I in 22 patients, AJCC stage II in 88 patients, AJCC stage III in 108 patients, and AJCC stage IV in 32 patients. PET/CT imaging was performed at different time points in the course of disease: 75 patients were evaluated for primary staging after sentinel node biopsy, 42 patients for therapy control after chemotherapy of metastatic disease, 65 patients for staging of clinically-suspected recurrent disease, and 68 patients during follow-up within 5 years of primary treatment. Additional details of patient and tumor characteristics are presented in Table 1. This study was approved by the local institutional review board.
Imaging Studies All imaging studies were performed on a dual modality PET/CT system (Biograph; Siemens Medical Solutions Inc, Hoffman Estates, IL). The biograph scanner consists of a combination of a dual-detector helical CT and a high-resolution PET scanner with a 15.8-cm axial field of view and an in-plane spatial resolution of 4.6 mm. PET imaging started 101 ± 21 minutes after intravenous injection of 371 ± 41 MBq FDG through an anterior cubital vein. Blood glucose measured before FDG injection was 5.55 ± 1.11 mmol/L. PET acquisition was performed in three parts, from the base of the skull to the apex of the lungs in two bed positions at 5 minutes per bed position with the arms down, from the shoulders to upper thighs in five to seven bed positions at 5 minutes per bed position with the arms up, and finally from the proximal femura to the tip of the toes in six to either bed positions at 3 minutes per bed position. CT imaging was performed within 1 minute before PET-imaging with the patient in precisely the same position. The acquisition parameters for dual-detector helical CT were 130 kV, 40 mAs, 0.8 seconds per CT rotation, 5-mm slice thickness, and pitch 1.5. One liter of an iodinated oral contrast agent (Peritrast-oral-GI; Köhler Chemie GmbH, Alsbach, Germany) was applied within 1 hour before CT imaging for better delineation of intestinal structures. No intravenous contrast agent was given to these patients. Limited breath hold technique was used for CT and shallow breathing for PET imaging to avoid motion-induced artifacts in the area of the diaphragm.17 In brief, patients were asked to breathe quietly throughout the CT scan, but to hold their breath for about 10 seconds when the CT tube approached the lower mediastinum until it passed the liver.17 Total acquisition time varied between 40 and 50 minutes and up to 70 minutes, when a patient with melanoma of the leg was scanned down to the toes. PET images were iteratively reconstructed with attenuation correction based on a rescaling of the CT image as described elsewhere.18 All patients provided written informed consent after the nature of the imaging studies was fully explained.
Evaluation Assessment of malignant disease by CT, PET, and PET/CT was done according to the current AJCC staging classification.5 The overall accuracy of CT, PET, and PET/CT was compared with regard to N- and M-staging, and after differentiation of N-stage in N1 (one lymph node), N2 (two or three regional nodes), and N3 (four or more regional nodes or intransit metastases) and in dependence on the clinical setting (initial staging, treatment evaluation, restaging, and follow-up) as well as after differentiation of M1-stage in M1A (distant lymph nodes), M1B (lung metastases), and M1C (metastases to other organs) and in dependence on the clinical setting. Although malignant melanoma has the capability to set metastases at different sites, a lesion-based analysis of visceral and nonvisceral metastases was also included. The impact of CT, PET, and PET/CT on patient management was evaluated concerning intermodality and intramodality changes of treatment as intended before the PET/CT study. These changes were retrospectively assessed by the colleagues from dermatology department considering all diagnostic information available with and without the PET/CT study. Intermodality changes included a change of treatment modality (ie, no treatment, surgery, medical treatment, and radiation therapy). Intramodality changes included a change within a therapeutic approach (eg, the expansion of areas to be surgically resected with curative intent). Histology and clinical follow-up served as standards of reference for evaluation of diagnostic performance of FDG-PET/CT. Primary malignant disease was confirmed by histopathologic verification in all patients. Initial staging included the results of sentinel node biopsies for N-staging in 15 patients, who underwent PET/CT imaging before the sentinel node biopsy was performed. If discrepant findings between CT and PET imaging could not be dissolved by image fusion or by other imaging modalities such as bone scan or MRI, or any uncertainty remained about the character of a lesion, suspected metastatic sites were verified by biopsy before a treatment decision was made. Pathologic N-staging was available in 100 patients, and M-stage was pathologically verified in 20 patients. In patients without histologic N- or M-stage verification, clinical follow-up served as standard of reference. Patients were seen regularly in 3-month intervals for a minimum follow-up period of 1 year, if there was no evidence for earlier tumor progression. Clinical follow-up included all available clinical information, laboratory tests, radiologic and nuclear medicine imaging studies such as MRI, contrast-enhanced CT, ultrasound, and bone scans. The data collection for the reference standard was done by a physician unaware of the results of PET/CT imaging.
Statistics
Overall Staging Analysis and Impact on Patient Management The standard of reference defined 116 patients (46.4%) as having metastatic melanoma. Prevalence of metastatic disease changed with the different time points of staging: it was 89.2% for staging of clinically-suspected recurrence, 66.7% for therapy control, 34.7% for primary staging, and 5.9% for follow-up. PET/CT provided significantly more accurate interpretations of overall N- and M-stage than PET or CT alone. Overall N- and M-stage was correctly determined by PET/CT in 243 of 250 patients (97.2%; 95% CI, 95.2% to 99.4%) compared with 232 patients (92.8%; 95% CI, 89.6% to 96.0%) by PET, and 197 patients (78.8%; 95% CI, 73.7% to 83.9%) by CT. All differences were significant (P < .02 for PET v PET/CT; P < .00001 for PET v CT and for PET/CT v CT). The frequency of over- or understaging according to the results of different imaging modalities was lowest for PET/CT: overstaging occurred in 31 patients according to CT imaging, in 10 patients according to PET imaging, and in three patients according to PET/CT. Understaging occurred in 22 patients according to CT imaging, in eight patients according to PET imaging, and in four patients according to PET/CT. Change of treatment according to PET/CT findings was recorded in 121 patients (48.4%). Intermodality changes were observed in 100 patients (40.0%) and intramodality changes in 21 patients (8.4%). Change of treatment occurred most frequently in patients studied for staging of recurrence (n = 47; 72.3%), followed by therapy control (n = 27; 64.3%) and primary staging (n = 32; 42.7%), and finally by follow-up (n = 15; 22.1%). Change of treatment occurred in 40 of 97 patients with T1 and T2 tumors (41.2%), in 69 of 130 patients with T3 and T4 tumors (53.1%), and in 16 of 23 patients with occult melanoma (69.6%). All these differences were significant (P < .025). Additional details of clinical management changes are presented in Table 2.
N-Staging Seventy-eight patients (31.2%) were defined as N-positive according to the standard of reference. N-stage was correctly determined by PET/CT in 246 of 250 patients (98.4%; 95% CI, 96.8% to 100%) compared with 240 patients (96.0%; 95% CI, 93.6% to 98.4%) by PET, and 216 patients (86.4%; 95% CI, 82.1% to 90.7%) by CT. The difference between PET and CT as well as between PET/CT and CT was significant (P < .001). Overstaging occurred in 22 patients according to CT imaging, in four patients according to PET imaging, and in no patients according to PET/CT. Understaging occurred in 12 patients according to CT imaging, in six patients according to PET-imaging, and in four patients according to PET/CT. Additional statistics of N-stage assessment are presented in Table 3.
N-Staging at Several Clinical Settings When the performance of PET/CT was analyzed at several clinical settings (ie, initial staging [n = 75], treatment evaluation [n = 42], restaging [n = 65], and follow-up [n = 68]), some tendencies became obvious. Diagnostic accuracy of PET/CT was highest at each setting, followed by that of PET alone, and that of CT alone. However, the gap between FDG-PET and PET/CT became small for initial staging. Sensitivity and NPV of CT alone for treatment evaluation was higher than that of PET and PET/CT, but specificity and PPV of CT alone was lowest. Sensitivity and PPV of PET/CT, PET alone, and CT alone was lowest in the follow-up group, due to the low number of three N-positive patients according to the standard of reference. In the follow-up group PET/CT performed best with no false-positive and one false-negative case, while these numbers were each two for PET alone, and seven and one for CT alone. Additional details of N-stage assessment at several clinical settings are presented in Table 4.
Differentiation of N1-N3 Stage The standard of reference defined 32 patients as N1-stage, and 23 patients as N2- and N3-stage each. N1-stage was correctly determined by PET/CT in 30 of 32 patients (93.8%; 95% CI, 88.4% to 99.2%) and by PET in 31 of 32 patients (96.9%; 95% CI, 93% to 100%) compared with 25 patients by CT (78.1%; 95% CI, 68.9% to 87.3%). The difference between PET and CT was significant (P < .05). The numbers of false-positives and false-negatives were one and two for PET/CT, respectively, one each for PET, and five and seven for CT, respectively. N2-stage was correctly determined by PET/CT in 20 of 23 patients (87%; 95% CI, 79.5% to 94.5%) and by PET in 19 of 23 patients (82.6%; 95% CI, 74.2% to 91%) compared with 15 patients by CT (65.2%; 95% CI, 54.6% to 75.8%). These differences were not significant. The numbers of false-positives and false-negatives were one and three for PET/CT, three and four for PET, and six and eight for CT. N3-stage was correctly determined by PET/CT in all 23 patients (100%) and by PET in 21 of 23 patients (91.3%; 95% CI, 85% to 97.6%) compared with 18 patients by CT (78.3%; 95% CI, 69.1% to 87.5%). The difference between PET/CT and CT was significant (P < .05). The numbers of false-negatives were zero for PET/CT, two for PET, and five for CT. There were no false-positives. Additional details of statistical evaluation for differentiation of N-stages are presented in Table 5.
M-Staging Eighty-four patients (33.6%) were defined as M-positive according to the standard of reference. M-stage was correctly determined by PET/CT in 245 of 250 patients (98.0%; 95% CI, 96.3% to 99.7%) compared with 233 patients (93.2%; 95% CI, 90.1% to 96.3%) by PET, and 209 patients (83.6%; 95% CI, 79.0% to 88.2%) by CT. All differences were significant (P < .005). Overstaging occurred in 20 patients according to CT imaging, in eight patients according to PET imaging, and in four patients according to PET/CT. Understaging occurred in 21 patients according to CT imaging, in nine patients according to PET imaging, and in one patient according to PET/CT. Additional statistics of M-stage assessment are presented in Table 6.
M-Staging at Several Clinical Settings When the performance of PET/CT was analyzed at several clinical settings (ie, initial staging [n = 75], treatment evaluation [n = 42], restaging [n = 65], and follow-up [n = 68]), some tendencies became obvious. CT was best for initial staging where the sensitivity of CT was equally high as that of PET and PET/CT. FDG-PET and PET/CT performed identical at follow-up. Larger differences between the three imaging modalities occurred for treatment evaluation and especially for restaging, where PET/CT and PET alone had a significantly higher accuracy than CT alone. Due to the lower number of patients in each subgroup, the differences between FDG-PET and PET/CT was not significant. Additional details of M-stage assessment at several clinical settings are presented in Table 7.
Differentiation of Distant Metastatic Sites The standard of reference defined 54 patients as M1A-stage, 32 patients as M1B-stage, and 40 patients as M1C-stage. M1A-stage was correctly determined by PET/CT and by PET in 53 of 54 patients (98.1%; 95% CI, 94.5% to 100%) compared with 43 patients (79.6%; 95% CI, 68.8% to 90.4%) by CT. This difference was significant (P < .005). The number of false-positives and false-negatives were one each for PET/CT, three and one for PET, and 12 and 11 for CT. M1B-stage was correctly determined by PET/CT in 32 of 32 patients, by PET in 21 of 32 patients (65.6%; 95% CI, 49.1% to 82.1%), and by CT in 30 of 32 patients (93.8%; 95% CI, 85.4% to 100%). The differences between CT and PET and between PET/CT and PET were significant (P < .005). The number of false-positives and false-negatives were two and zero for PET/CT, zero and 11 for PET, and seven and two for CT. M1C-stage was correctly determined by PET/CT and by PET in 40 of 40 patients compared with 26 patients (65.0%; 95% CI, 48.2% to 81.8%) by CT. This difference was significant (P < .00005). The number of false-positives and false-negatives were two and zero for PET/CT, five and zero for PET, and nine and 14 for CT. Details of statistical evaluation for differentiation of M-stage are presented in Table 8.
Detection of Visceral and Nonvisceral Metastases A total of 670 visceral and nonvisceral metastases were identified according to the standard of reference. The number of metastases identified increased significantly from CT (69.7%; 95% CI, 66.2% to 73.2%) to PET (88.8%; 95% CI, 86.4% to 91.2%) and to PET/CT (98.7%; 95% CI, 97.9% to 99.5%). The most significant advantage of PET/CT in comparison to the single modalities PET or CT was observed for detection of visceral metastases, which were identified in 100% by fused imaging, in 82.6% by PET alone, and in 64.2% by CT alone. Additional details of metastases detection by CT, PET, and PET/CT are presented in Table 9.
Both PET alone and CT alone shared a significant increase in sensitivity and accuracy for M-stage assessment of melanoma patients following image fusion with PET/CT. PET/CT was significantly more specific and accurate than CT alone, but not than PET alone for N-stage assessment. Thus, the most significant advantage of combined PET/CT imaging in comparison to the single modalities was an improved detection and differentiation of distant metastases, especially of visceral metastases. The differences of diagnostic accuracy between CT alone, PET alone, and PET/CT were highest when performed for treatment evaluation and for restaging. PET alone has already proven useful for patient management of AJCC stage III and IV disease.19,20 In a prospective study of 106 PET scans in 95 melanoma patients with AJCC stage III regional disease, a sensitivity of 87%, and a PPV of 90% was observed with the application of pertinent clinical information to reduce the number of false-positive PET findings.19 More importantly, it was shown that unexpected findings on PET imaging resulted in a change of management in 15% of patients, including the detection of distant metastases.19 It should be noted that in this study, up to 740 MBq FDG were applied, resulting in a potentially higher tumor-to-background ratio than in most other PET studies. Another prospective study compared performance of PET for detection of distant metastases to that of conventional imaging including CT and/or MRI in 18 patients with AJCC stage IV melanoma scheduled for metastasectomy.20 Finkelstein et al reported a comparable sensitivity for PET and conventional imaging of 79% and 76% and the same PPV of 86%, which could be increased to 88% sensitivity and 91% PPV by side-by-side reading of PET and CT.20 In addition, it has been suggested that PET should be considered as the first-line imaging procedure for recurrent disease because it had a higher sensitivity and specificity than CT in three series including 84, 104, and 156 melanoma patients, respectively.21-23 These three studies reported sensitivities of PET and CT of 74% to 85%, and 58% to 81%, and the specificities for PET and CT were 86% to 97%, and 45% to 87%, respectively.21-23 Our study observed that PET alone provided the same high sensitivity as PET/CT for detection of distant lymph node metastases and metastases to all other organs but the lungs. However, the specificity of PET significantly improved following image fusion with CT from 90% to 97% for distant lymph node metastases and from 88% to 95% for visceral metastases. The accurate anatomic correlation of areas of more or less increased FDG-uptake led to a significant reduction of false-positive and false-negative findings by PET/CT in this study. A similar observation has been made for PET/CT imaging of tumors other than cutaneous melanoma.16 It may be supposed that the complement of the anatomic information derived from CT imaging to functional imaging with PET can hardly be overestimated. A significant contribution of CT was observed for detection of pulmonary metastases, where PET is highly specific but has a limited sensitivity, as presented in this study (Table 4). However, even specificity of CT for differentiation of pulmonary metastases significantly improved after image fusion with PET from 86.5% to 96%. The usefulness of combined PET/CT imaging for assessment of pulmonary metastases was recently evaluated in a series of 92 patients with 438 metastases to the lungs of different primary tumors including malignant melanoma.24 PET performed as part of PET/CT imaging detected 39.7% of all lung metastases.24 In this study, pulmonary metastases greater than 10 mm in diameter were detected with a high sensitivity of 0.935, but sensitivity fell rapidly below that nodule size. Diagnostic accuracy of PET for staging of regional lymph-node metastases was often compromised by the fact that micrometastases cannot be detected due to the limited spatial resolution of PET.12 A few years ago, a clear volume dependency of PET for detection on melanoma lymph node metastases was reported with a reliable detection of tumor deposits of approximately 80 mm3 volume and more.25 This amount of tumor is most likely to occur in patients with AJCC stage III and IV. Because the axial and transaxial spatial resolution of current generation PET in PET/CT scanners is about 6 to 7 mm according to National Electrical Manufacturers Association standards, the detection limit of lymph node metastases may be further reduced to that size.26 However, the use of PET/CT for smaller metastases must await additional technologic refinements. Several studies compared the results of sentinel node biopsy with that of whole-body FDG-PET for primary staging of melanoma.27-30 All studies but one included AJCC stage I and II patients and observed FDG-PET to be an insensitive indicator of occult regional lymph node metastases.28-30 The better results of FDG-PET in the other study may be a result of higher tumor masses, because 60% of patients in this study were AJCC stage III.27 Unfortunately, our study on FDG-PET/CT imaging could not contribute to this discussion, because the subgroup of 15 melanoma patients receiving PET/CT for primary staging before sentinel node biopsy was too small for precise calculation of diagnostic accuracy. Diagnostic accuracy of CT for detection and differentiation of distant lymph node metastases is usually limited by the morphologic size criteria, because enlarged distant lymph nodes do not necessarily harbor metastases and vice versa.31 Thus, the specificity of CT in this study was lowest for differentiation of distant lymph node metastases, even lower than that for regional metastases. This observation may be explained in part by the fact that most patients studied for primary staging received PET/CT after the sentinel node biopsy. Another reason may be that we did not use the full potential of CT, whereas we did not apply intravenous contrast medium in the present series of patients. However, an improved diagnostic accuracy of contrast-enhanced CT would affect both regional and distant lymph node metastases. The application of intravenous contrast medium may significantly improve the performance of CT for M-staging as part of a PET/CT study.16 An analysis of the performance of PET/CT imaging in 260 patients with various tumors other than malignant melanoma demonstrated a similar sensitivity and specificity of CT and PET (82% and 78% sensitivity; 95% and 99% specificity). Antoch et al observed a significant increase in sensitivity to 94% after image fusion, which was almost as high as the 98.8% sensitivity reported in this study.16 Nonetheless, it has been shown that a contrast-enhanced CT performed in addition to a PET/CT study with oral contrast only as in our study was of limited value in Hodgkin's and non-Hodgkin's lymphoma patients.32 It remains to be studied whether contrast-enhanced CT as part of a PET/CT study might have a significant impact on the overall performance of PET/CT in melanoma patients. From the referring physician's perspective, the use of PET resulted in a change of intermodality management in 29% and in a change of intramodality management in 18% of melanoma patients, that is an overall treatment change in 47% of all cases.33 A most recent retrospective analysis reported an impact of FDG-PET on the clinical decision making process in 34% of 126 melanoma patients with stage III or IV disease.34 This study used a rigorous approach to impact on clinical management such that the FDG-PET results were not considered to have affected decision making if it confirmed the CT or clinical impression of multiple metastases or of no active disease.34 Our study shows similar results with an overall treatment change in 48.4% of melanoma patients according to the results of FDG-PET/CT imaging. The observed frequency of intermodality management change after FDG-PET/CT imaging was 40.4%, which was higher than that of FDG-PET alone reported in the two other studies (29% and 34%).33,34 The most significant changes occurred in melanoma patients for staging of recurrence (53.8%) and for therapy control (52.4%). This study demonstrates a superior performance of fused images obtained from dual-modality FDG-PET/CT imaging compared with that obtained from PET alone and CT alone showing an increased clinical impact in melanoma patients. The use of PET/CT as a possible first-line modality for detection and differentiation of metastases in areas inaccessible by physical examination and biopsy may be suggested in patients with suspected recurrence, for therapy control, and for primary staging.
The authors indicated no potential conflicts of interest.
Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
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Copyright © 2006 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
