HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by McCarville, M. B. Articles by Kaste, S. C. Search for Related Content PubMed PubMed Citation Articles by McCarville, M. B. Articles by Kaste, S. C. Social Bookmarking                      What's this? Hotlight (NEW!) What's Hotlight?

PET/CT in the Evaluation of Childhood Sarcomas

¹ Department of Radiological Sciences, St. Jude Children's Research Hospital, 332 N Lauderdale St., Memphis, TN 38105.
² Department of Radiology, College of Medicine, University of Tennessee, Memphis, TN.
³ Department of Hematology-Oncology, St. Jude Children's Research Hospital, Memphis, TN.

Received July 9, 2004; accepted after revision September 13, 2004.

 
Address correspondence to M. B. McCarville.

Supported in part by Cancer Center Support grant CA21765 from the U.S. Public Health Service, by Childhood Solid Tumor Program Project grant CA-23099 and by the American Lebanese Syrian Associated Charities.

Abstract

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
OBJECTIVE. Our objective was to review our preliminary experience with PET/CT in evaluating childhood sarcomas including rhabdomyosarcoma (n = 28), the Ewing's sarcoma family of tumors (n = 14), nonrhabdomyosarcoma soft-tissue sarcoma (n = 9), osteosarcoma (n = 8), chondrosarcoma (n = 1), and embryonal sarcoma (n = 1).

CONCLUSION. We found PET/CT useful in depicting an unknown primary rhabdomyosarcoma and detecting unsuspected and unusual metastatic sites of childhood sarcomas. It was useful in monitoring response to chemotherapy, radiation therapy, and radiofrequency ablation and aided the postoperative evaluation of tumor resection sites.

Introduction

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
Fluorine-18 FDG is a radiolabeled glucose analogue that is transported across cell membranes and phosphorylated but cannot be dephosphorylated. As a result, FDG is trapped inside cells, where it emits a positron that undergoes an annihilation reaction with an electron to produce two 511-keV gamma rays, which are emitted in opposite directions. When a PET camera detects two 511-keV photons of energy coming from opposite directions at the same time, a signal is produced. PET of this nature capitalizes on the fact that tumors are highly metabolically active and accumulate more glucose (and FDG) than normal tissue [1, 2]. Currently FDG PET has been approved for Medicare reimbursement in the evaluation of adults with lymphoma, solitary pulmonary nodules, lung cancer, colorectal cancer, esophageal cancer, melanoma, head and neck cancer, and breast cancer [1, 2]. The utility of PET for pediatric oncologic applications, other than Hodgkin's lymphoma, has not been well evaluated.

Since 2002, we have performed PET/CT as part of the imaging evaluation of 61 children with a variety of sarcomas, including rhabdomyosarcoma (n = 28), Ewing's sarcoma family of tumors (n = 14), nonrhabdomyosarcoma soft-tissue sarcomas (n = 9), osteosarcoma (n = 8), chondrosarcoma (n = 1), and embryonal sarcoma (n = 1). PET/CT provides a method of obtaining both metabolic and morphologic information in one imaging session. Generally, a low-dose CT scan is obtained first and is used to determine attenuation correction factors for PET and also serves as an anatomic reference. Immediately after acquisition of the CT scan, a PET scan is obtained without moving the patient. This allows accurate coregistration of PET and CT images. The images are reviewed at a workstation that allows one to view the CT images alone, the PET images alone, and the CT images fused with the corresponding PET images in a side-by-side format. This hybrid technique has an important advantage over PET alone because it allows accurate anatomic localization of sites of increased FDG activity. The purpose of this pictorial essay is to review our preliminary experience with this fusion imaging technique in the evaluation of childhood sarcomas. We will illustrate and discuss applications of PET/CT that have been of benefit to us and may ultimately enhance the management of these malignancies.

Identification of an Unknown Primary Site

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
Although most sarcomas are evident on physical examination, it is estimated that 4% of rhabdomyosarcomas and 3-5% of all cancers present with metastatic disease and an unknown primary site [3, 4]. The imaging evaluation of such patients is focused on identifying the primary site and is guided by both clinical suspicion and the pathologic type of metastatic disease [3, 4]. Traditionally such evaluations could require the use of multiple imaging techniques suitable for assessing various anatomic sites. PET/CT allows evaluation of the entire patient in one sitting. PET has been shown to reveal the location of primary tumors in 21-30% of adults with occult head and neck or breast cancers but has also been shown to have a false-positive rate of approximately 20% in these patients [3]. PET/CT may reduce this false-positive rate because it allows sites of physiologically increased FDG activity (e.g., supraclavicular brown fat) to be accurately localized and distinguished from tumor-based activity. We found PET/CT useful in identifying an unknown primary site in a child with widely metastatic alveolar rhabdomyosarcoma (Figs. 1A, and 1B).

View larger version (34K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A. —12-year-old girl who presented with abdominal lymphadenopathy, anemia, and pleural effusion. Differential diagnosis included Burkitt's lymphoma versus solid tumor. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Primary site was not identified at physical examination. Maximum-intensity-projection PET image revealed primary site in left calf (arrow). Note also diffuse bone marrow metastatic disease evidenced by increased activity throughout skeleton relative to liver.

View larger version (70K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B. —12-year-old girl who presented with abdominal lymphadenopathy, anemia, and pleural effusion. Differential diagnosis included Burkitt's lymphoma versus solid tumor. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Primary site was not identified at physical examination. Contrast-enhanced axial MRI of left calf primary tumor was obtained after PET/CT. This deeply seated tumor (T) was missed at initial physical examination.

Initial Staging of a Sarcoma

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
The baseline imaging evaluation of bone and soft-tissue sarcomas in children currently includes MRI of the primary tumor, CT of the chest to evaluate pulmonary metastases, and technetium-99m-labeled methyldiphosphonate (^99mTc MDP) nuclear scintigraphy to identify bony metastatic disease [5]. In tumors with a propensity for regional nodal spread, such as rhabdomyosarcoma, MRI or CT of the draining lymph nodes must also be performed. We have found PET/CT useful in identifying and localizing unusual sites of soft-tissue and bony metastases not appreciated on physical examination or imaging performed during the conventional metastatic workup (Figs. 2A, 2B, 2C, 2D, and 2E). In our experience, PET/CT has had limited specificity in distinguishing benign and malignant nodal disease (Figs. 3A, 3B, 3C, 3D, 3E, 3F, 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, 4I, 5A, 5B, 5C, and 5D).

View larger version (65K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A. —19-year-old woman who presented with left thigh mass proven by biopsy to be high-grade malignant peripheral nerve sheath tumor. Anterior maximum-intensity-projection PET image shows primary left thigh tumor (straight arrow), abnormal left pelvic activity (arrowhead), and abnormal focus in thoracic vertebra (curved arrow).

View larger version (67K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B. —19-year-old woman who presented with left thigh mass proven by biopsy to be high-grade malignant peripheral nerve sheath tumor. STIR sagittal MR image of spine shows only subtle lesion (arrow) corresponding to abnormal focus seen on PET.

View larger version (62K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2C. —19-year-old woman who presented with left thigh mass proven by biopsy to be high-grade malignant peripheral nerve sheath tumor. Axial CT (C), PET (D), and fused PET/CT (E) images show intense activity in ninth thoracic vertebral body (arrows), which was proven by biopsy to be metastatic disease. Bone metastases are very rare in malignant peripheral nerve sheath tumor, and this metastatic deposit was not clinically suspected. Technetium-99m-labeled methyldiphosphonate bone scan obtained the day before PET showed no evidence of disease in thoracic spine.

View larger version (58K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2D. —19-year-old woman who presented with left thigh mass proven by biopsy to be high-grade malignant peripheral nerve sheath tumor. Axial CT (C), PET (D), and fused PET/CT (E) images show intense activity in ninth thoracic vertebral body (arrows), which was proven by biopsy to be metastatic disease. Bone metastases are very rare in malignant peripheral nerve sheath tumor, and this metastatic deposit was not clinically suspected. Technetium-99m-labeled methyldiphosphonate bone scan obtained the day before PET showed no evidence of disease in thoracic spine.

View larger version (58K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2E. —19-year-old woman who presented with left thigh mass proven by biopsy to be high-grade malignant peripheral nerve sheath tumor. Axial CT (C), PET (D), and fused PET/CT (E) images show intense activity in ninth thoracic vertebral body (arrows), which was proven by biopsy to be metastatic disease. Bone metastases are very rare in malignant peripheral nerve sheath tumor, and this metastatic deposit was not clinically suspected. Technetium-99m-labeled methyldiphosphonate bone scan obtained the day before PET showed no evidence of disease in thoracic spine.

View larger version (97K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A. —Two opposing examples of benign nodal disease appearance on PET/CT. In 19-year-old woman who presented with large right popliteal fossa mass, mass was proven by biopsy to be embryonal rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show absence of FDG activity within enlarged retroperitoneal node (arrows). This node underwent biopsy and was found to be negative for tumor.

View larger version (62K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B. —Two opposing examples of benign nodal disease appearance on PET/CT. In 19-year-old woman who presented with large right popliteal fossa mass, mass was proven by biopsy to be embryonal rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show absence of FDG activity within enlarged retroperitoneal node (arrows). This node underwent biopsy and was found to be negative for tumor.

View larger version (68K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3C. —Two opposing examples of benign nodal disease appearance on PET/CT. In 19-year-old woman who presented with large right popliteal fossa mass, mass was proven by biopsy to be embryonal rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show absence of FDG activity within enlarged retroperitoneal node (arrows). This node underwent biopsy and was found to be negative for tumor.

View larger version (104K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3D. —Two opposing examples of benign nodal disease appearance on PET/CT. Same patient as described in Figures 2A, 2B, 2C, 2D, and 2E has malignant peripheral nerve sheath tumor. Axial CT (D), PET (E), and fused PET/CT (F) images show enlarged FDG-avid left external iliac node (arrows) that was not metastatic but contained follicular hyperplasia and sinus histiocytosis seen on pathologic review.

View larger version (55K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3E. —Two opposing examples of benign nodal disease appearance on PET/CT. Same patient as described in Figures 2A, 2B, 2C, 2D, and 2E has malignant peripheral nerve sheath tumor. Axial CT (D), PET (E), and fused PET/CT (F) images show enlarged FDG-avid left external iliac node (arrows) that was not metastatic but contained follicular hyperplasia and sinus histiocytosis seen on pathologic review.

View larger version (78K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3F. —Two opposing examples of benign nodal disease appearance on PET/CT. Same patient as described in Figures 2A, 2B, 2C, 2D, and 2E has malignant peripheral nerve sheath tumor. Axial CT (D), PET (E), and fused PET/CT (F) images show enlarged FDG-avid left external iliac node (arrows) that was not metastatic but contained follicular hyperplasia and sinus histiocytosis seen on pathologic review.

View larger version (87K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4A. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show numerous intensely FDG-avid metastatic deposits (arrows) in both breasts, not appreciated at initial physical examination.

View larger version (88K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4B. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show numerous intensely FDG-avid metastatic deposits (arrows) in both breasts, not appreciated at initial physical examination.

View larger version (64K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4C. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images show numerous intensely FDG-avid metastatic deposits (arrows) in both breasts, not appreciated at initial physical examination.

View larger version (84K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4D. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and fused PET/CT (F) images show presumed metastatic nodal disease in external iliac chain on opposite side of primary tumor (arrows).

View larger version (72K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4E. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and fused PET/CT (F) images show presumed metastatic nodal disease in external iliac chain on opposite side of primary tumor (arrows).

View larger version (69K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4F. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and fused PET/CT (F) images show presumed metastatic nodal disease in external iliac chain on opposite side of primary tumor (arrows).

View larger version (54K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4G. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (G), PET (H), and fused PET/CT (I) images show abnormal focus of activity in small soft-tissue nodule in left thigh (arrows). All these sites of abnormal activity responded to chemotherapy and are presumed to have been metastatic.

View larger version (35K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4H. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (G), PET (H), and fused PET/CT (I) images show abnormal focus of activity in small soft-tissue nodule in left thigh (arrows). All these sites of abnormal activity responded to chemotherapy and are presumed to have been metastatic.

View larger version (33K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4I. —Same patient as in Figures 1A, and 1B. Bone marrow biopsy revealed alveolar rhabdomyosarcoma. Axial CT (G), PET (H), and fused PET/CT (I) images show abnormal focus of activity in small soft-tissue nodule in left thigh (arrows). All these sites of abnormal activity responded to chemotherapy and are presumed to have been metastatic.

View larger version (78K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5A. —19-year-old man who underwent reexcision of leiomyosarcoma from proximal left thigh in 1999. Follow-up MRI revealed enlarged left external iliac nodes, so PET/CT was performed for further evaluation. Maximum-intensity-projection PET image shows abnormal activity in left pelvis (arrow). Activity in chest muscles was believed to be physiologic in nature.

View larger version (94K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5B. —19-year-old man who underwent reexcision of leiomyosarcoma from proximal left thigh in 1999. Follow-up MRI revealed enlarged left external iliac nodes, so PET/CT was performed for further evaluation. Axial CT (B), PET (C), and fused PET/CT (D) images localize this activity to enlarged left external iliac nodes (arrow). These were proven by biopsy to be recurrent leiomyosarcoma.

View larger version (72K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5C. —19-year-old man who underwent reexcision of leiomyosarcoma from proximal left thigh in 1999. Follow-up MRI revealed enlarged left external iliac nodes, so PET/CT was performed for further evaluation. Axial CT (B), PET (C), and fused PET/CT (D) images localize this activity to enlarged left external iliac nodes (arrow). These were proven by biopsy to be recurrent leiomyosarcoma.

View larger version (85K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5D. —19-year-old man who underwent reexcision of leiomyosarcoma from proximal left thigh in 1999. Follow-up MRI revealed enlarged left external iliac nodes, so PET/CT was performed for further evaluation. Axial CT (B), PET (C), and fused PET/CT (D) images localize this activity to enlarged left external iliac nodes (arrow). These were proven by biopsy to be recurrent leiomyosarcoma.

Monitoring Response to Therapy

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
Evaluating response to neoadjuvant chemotherapy is crucial in the management of childhood sarcomas, particularly osteosarcoma, for which tumor response is highly predictive of patient outcome and may impact surgical planning for amputation or limb-salvage procedures [5, 6]. Currently, the therapeutic response of sarcomas in children is assessed by morphologic change seen on CT and MRI. These imaging techniques can be limited by distorted normal anatomy, indistinct tumor border, and a lack of reproducible quantitative information about tumor viability [5, 6]. Radiation therapy and chemotherapy may invoke significant changes in tumor viability, whereas only minimal change in morphology is apparent on conventional imaging [6]. Brenner et al. [7] and Hawkins et al. [8] showed that measurement of the standard uptake value of primary osteosarcoma, on serial FDG PET images is an accurate indicator of tumor response to preoperative chemotherapy. We have used PET/CT to qualitatively monitor the response of a variety of sarcomas to irradiation, chemotherapy, and radiofrequency ablation (Figs. 6A, 6B, 7A, 7B, 8A, 8B, 8C, 8D, 8E, and 8F). We have also found PET/CT to be a useful adjunct in assessing the adequacy of surgical tumor resection (Figs. 9A, 9B, 9C, 9D, 9E, and 9F).

View larger version (46K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6A. —16-year-old boy with large right pelvic Ewing's sarcoma, treated preoperatively with chemotherapy and radiation therapy. Maximum-intensity-projection PET image, obtained before neoadjuvant therapy, shows intense FDG activity in primary tumor (arrow) without evidence of metastatic disease.

View larger version (81K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6B. —16-year-old boy with large right pelvic Ewing's sarcoma, treated preoperatively with chemotherapy and radiation therapy. Maximum-intensity-projection PET image, obtained after neoadjuvant therapy, shows minimal activity within tumor (arrow), suggestive of good response. Pathologic inspection of resected tumor showed less than 5% residual viable tumor.

View larger version (78K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7A. —18-year-old woman with widely metastatic alveolar rhabdomyosarcoma who developed palpable metastatic soft-tissue nodules on anterior abdominal wall. PET/CT was performed as part of metastatic evaluation. Maximum-intensity-projection PET image shows multiple sites of abnormal FDG activity in chest, abdomen, pelvis, femurs, and right humerus, which were better localized on PET/CT than on PET alone.

View larger version (64K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7B. —18-year-old woman with widely metastatic alveolar rhabdomyosarcoma who developed palpable metastatic soft-tissue nodules on anterior abdominal wall. PET/CT was performed as part of metastatic evaluation. Maximum-intensity-projection PET image, obtained after bone marrow transplantation and treatment with chemotherapy, shows dramatic response of all metastatic sites.

View larger version (82K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8A. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (A), PET (B), and fused PET/CT (C) images obtained before radiofrequency ablation show abnormal activity within right upper lobe pulmonary nodule (arrows). Biopsy of this nodule at time of radiofrequency ablation confirmed presence of osteosarcoma.

View larger version (61K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8B. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (A), PET (B), and fused PET/CT (C) images obtained before radiofrequency ablation show abnormal activity within right upper lobe pulmonary nodule (arrows). Biopsy of this nodule at time of radiofrequency ablation confirmed presence of osteosarcoma.

View larger version (60K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8C. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (A), PET (B), and fused PET/CT (C) images obtained before radiofrequency ablation show abnormal activity within right upper lobe pulmonary nodule (arrows). Biopsy of this nodule at time of radiofrequency ablation confirmed presence of osteosarcoma.

View larger version (73K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8D. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (D), PET (E), and fused PET/CT (F) images obtained after radiofrequency ablation show minimal activity only at periphery of the tumor (arrows), which may be due to inflammation or flare phenomenon.

View larger version (53K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8E. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (D), PET (E), and fused PET/CT (F) images obtained after radiofrequency ablation show minimal activity only at periphery of the tumor (arrows), which may be due to inflammation or flare phenomenon.

View larger version (60K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8F. —This 10-year-old boy had previously undergone left pneumonectomy for metastatic osteosarcoma when he presented with new right pulmonary metastases that were treated with radiofrequency ablation. Axial CT (D), PET (E), and fused PET/CT (F) images obtained after radiofrequency ablation show minimal activity only at periphery of the tumor (arrows), which may be due to inflammation or flare phenomenon.

View larger version (68K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9A. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images at baseline show intense FDG activity within primary tumor.

View larger version (70K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9B. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images at baseline show intense FDG activity within primary tumor.

View larger version (45K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9C. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (A), PET (B), and fused PET/CT (C) images at baseline show intense FDG activity within primary tumor.

View larger version (66K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9D. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and PET/CT (F) images obtained after surgical resection show no evidence of residual disease in operative bed. Surgical resection margins were negative for tumor on pathologic review.

View larger version (58K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9E. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and PET/CT (F) images obtained after surgical resection show no evidence of residual disease in operative bed. Surgical resection margins were negative for tumor on pathologic review.

View larger version (53K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9F. —6-year-old boy who presented with right forearm mass that was proven by biopsy to be alveolar rhabdomyosarcoma. Axial CT (D), PET (E), and PET/CT (F) images obtained after surgical resection show no evidence of residual disease in operative bed. Surgical resection margins were negative for tumor on pathologic review.

Detecting Recurrence

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
Children with soft-tissue and bone sarcomas are generally followed clinically and radiographically for 3-5 years after treatment for evidence of tumor recurrence [5]. The likelihood of disease recurrence depends on histologic and biologic characteristics of the tumor and on clinical variables. Approximately 25-35% of children and adolescents with sarcomas will experience tumor recurrence after primary therapy [5]. Recurrences may be local, regional, or distant to the bones, lungs, or other soft tissues. Follow-up imaging currently includes MRI of the primary site (for soft-tissue sarcomas), ^99mTc MDP bone scanning, and chest CT [5]. In our experience, PET/CT has been useful in the follow-up evaluation of these patients, particularly those with alveolar rhabdomyosarcoma because this tumor can metastasize to unusual soft-tissue sites that may be missed by physical examination and conventional imaging techniques (Figs. 5A, 5B, 5C, 5D, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 11A, 11B, and 11C).

View larger version (113K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10A. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (A), PET (B), and fused PET/CT (C) images show left breast metastasis (arrows).

View larger version (71K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10B. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (A), PET (B), and fused PET/CT (C) images show left breast metastasis (arrows).

View larger version (73K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10C. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (A), PET (B), and fused PET/CT (C) images show left breast metastasis (arrows).

View larger version (114K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10D. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (D), PET (E), and fused PET/CT (F) images show abnormal FDG activity in pancreas (straight arrows), mesenteric nodule (curved arrows), and subcutaneous nodule (arrowheads), all unusual sites of metastatic rhabdomyosarcoma. Pancreatic and mesenteric sites, shown here, were present but overlooked on conventional CT performed 1 week before PET/CT.

View larger version (73K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10E. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (D), PET (E), and fused PET/CT (F) images show abnormal FDG activity in pancreas (straight arrows), mesenteric nodule (curved arrows), and subcutaneous nodule (arrowheads), all unusual sites of metastatic rhabdomyosarcoma. Pancreatic and mesenteric sites, shown here, were present but overlooked on conventional CT performed 1 week before PET/CT.

View larger version (67K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10F. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (D), PET (E), and fused PET/CT (F) images show abnormal FDG activity in pancreas (straight arrows), mesenteric nodule (curved arrows), and subcutaneous nodule (arrowheads), all unusual sites of metastatic rhabdomyosarcoma. Pancreatic and mesenteric sites, shown here, were present but overlooked on conventional CT performed 1 week before PET/CT.

View larger version (118K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10G. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (G), PET (H), and fused PET/CT (I) images show additional mesenteric metastasis missed by conventional CT (arrows).

View larger version (75K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10H. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (G), PET (H), and fused PET/CT (I) images show additional mesenteric metastasis missed by conventional CT (arrows).

View larger version (64K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10I. —Same 18-year-old woman with recurrent metastatic alveolar rhabdomyosarcoma as seen in Figures 6A, and 6B. PET/CT, performed as part of metastatic evaluation, revealed many unsuspected sites of soft-tissue metastatic disease. Axial CT (G), PET (H), and fused PET/CT (I) images show additional mesenteric metastasis missed by conventional CT (arrows).

View larger version (87K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11A. —16-year-old girl with previously treated alveolar rhabdomyosarcoma who was being evaluated for bone marrow transplantation. Axial CT (A), PET (B), and fused PET/CT (C) images show clinically unsuspected left breast metastasis (arrows).

View larger version (61K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11B. —16-year-old girl with previously treated alveolar rhabdomyosarcoma who was being evaluated for bone marrow transplantation. Axial CT (A), PET (B), and fused PET/CT (C) images show clinically unsuspected left breast metastasis (arrows).

View larger version (56K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11C. —16-year-old girl with previously treated alveolar rhabdomyosarcoma who was being evaluated for bone marrow transplantation. Axial CT (A), PET (B), and fused PET/CT (C) images show clinically unsuspected left breast metastasis (arrows).

Conclusion

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 
We have found PET/CT to be useful in the identification of unknown primary rhabdomyosarcoma and in the detection of unsuspected and unusual metastatic sites of a variety of childhood sarcomas. It has been a useful adjunct in monitoring the response to chemotherapy, radiation therapy, and radiofrequency ablation and in the postoperative evaluation of these tumors. It has shown variable specificity as a marker of nodal disease. Although the value of PET in the evaluation of a number of solid tumors in adults has been validated, further prospective clinical trials are necessary to determine the role of PET and PET/CT in the management of pediatric sarcomas.

References

Top Abstract Introduction Identification of an Unknown... Initial Staging of a... Monitoring Response to Therapy Detecting Recurrence Conclusion References

 

1. Kostakoglu L, Agress H, Goldsmith SJ. Clinical role of FDG PET in evaluation of cancer patients. RadioGraphics2003; 23:315 -340[Abstract/Free Full Text]
2. Rohrn E, Turkington T, Coleman E. Clinical applications of PET in oncology. Radiology2004; 231:305 -332[Abstract/Free Full Text]
3. Varadhachary GR, Abbruzzese JL, Lenzi R. Diagnostic strategies for unknown primary cancer. Cancer2004; 100:1776 -1785[Medline]
4. Etcubanas E, Peiper S, Stass S, Green A. Rhabdomyosarcoma, presenting as disseminated malignancy from an unknown primary site: a retrospective study of ten pediatric cases. Med Pediatr Oncol 1989;17:39 -44[Medline]
5. Pizzo PA, Poplack DG. Principles and practice of pediatric oncology. Philadelphia, PA: Lippincott Williams & Wilkins, 2002
6. Bredella MA, Caputo GR, Steinbach LS. Value of FDG positron emission tomography in conjunction with MR imaging for evaluating therapy response in patients with musculoskeletal sarcomas. AJR 2002;179:1145 -1150[Abstract/Free Full Text]
7. Brenner W, Bohuslavizki KH, Eary JF. PET imaging of osteosarcoma. J Nucl Med2003; 44:930 -942[Abstract/Free Full Text]
8. Hawkins DS, Rajendran JG, Conrad EU 3rd, Bruckner JD, Eary JF. Evaluation of chemotherapy response in pediatric bone sarcomas by [F-18]-fluorodeoxy-D-glucose positron emission tomography. Cancer 2002;94:3277 -3284[Medline]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				J. M. Bestic, J. J. Peterson, and L. W. Bancroft Use of FDG PET in Staging, Restaging, and Assessment of Therapy Response in Ewing Sarcoma RadioGraphics, September 1, 2009; 29(5): 1487 - 1500. [Abstract] [Full Text] [PDF]

				B. H. Kushner, M. P. Laquaglia, W. L. Gerald, K. Kramer, S. Modak, and N.-K. V. Cheung Solitary Relapse of Desmoplastic Small Round Cell Tumor Detected by Positron Emission Tomography/Computed Tomography J. Clin. Oncol., October 20, 2008; 26(30): 4995 - 4996. [Full Text] [PDF]

				N. Federman and S. A. Feig PET/CT in Evaluating Pediatric Malignancies: A Clinician's Perspective J. Nucl. Med., December 1, 2007; 48(12): 1920 - 1922. [Full Text] [PDF]

				H. U. Gerth, K. U. Juergens, U. Dirksen, J. Gerss, O. Schober, and C. Franzius Significant Benefit of Multimodal Imaging: PET/CT Compared with PET Alone in Staging and Follow-up of Patients with Ewing Tumors J. Nucl. Med., December 1, 2007; 48(12): 1932 - 1939. [Abstract] [Full Text] [PDF]

				S. D. Brown and E. vanSonnenberg Issues in Imaging-Guided Tumor Ablation in Children Versus Adults Am. J. Roentgenol., September 1, 2007; 189(3): 626 - 632. [Abstract] [Full Text] [PDF]

				C. Franzius, K. U. Juergens, J. Vormoor, and M. B. McCarville PET/CT with Diagnostic CT in the Evaluation of Childhood Sarcoma Am. J. Roentgenol., February 1, 2006; 186(2): 581 - 582. [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by McCarville, M. B. Articles by Kaste, S. C. Search for Related Content PubMed PubMed Citation Articles by McCarville, M. B. Articles by Kaste, S. C. Social Bookmarking                      What's this? Hotlight (NEW!) What's Hotlight?