Evaluation of fluorodeoxyglucose positron emission tomography in the management of soft-tissue sarcomas

[18F]FDG PET/CT in the Initial Staging and Restaging of Soft-Tissue or Bone Sarcoma in Patients with Negative or Equivocal Findings for Metastases or Limited Recurrence on Conventional Work-up: Results of a Prospective Multicenter Registry

The purpose of this study was to determine the impact of [18F]FDG PET/CT on the initial staging, restaging, clinical management, and outcomes of patients with soft-tissue and bone sarcomas. Methods: This single-arm, prospective multicenter registry enrolled 304 patients with 320 [18F]FDG PET/CT scans (November 2018 to October 2021). Eligibility included the initial staging of a grade 2 or higher or ungradable soft-tissue or bone sarcoma, with negative or equivocal findings for nodal or distant metastases on conventional imaging before curative-intent therapy, or restaging of patients with a history of treated sarcoma with a suspicion or confirmation of local recurrence or limited metastatic disease who were being considered for curative-intent or salvage therapy. The presence of local recurrence or metastases on [18F]FDG PET/CT was recorded. Clinical management after [18F]FDG PET/CT compared with pre-[18F]FDG PET/CT planned management and quantitative metabolic tumor parameters (SUVmax, metabolic tumor volume, total lesion glycolysis) were correlated with the outcome data for 171 patients. Results: At the initial staging, [18F]FDG PET/CT detected metastases in 17 of 105 patients (16.2%) with no metastases on conventional work-up and confirmed metastases in 44 of 92 patients (47.8%) with equivocal findings for metastases. At the time of restaging, [18F]FDG PET/CT detected local recurrence in 37 of 123 patients (30.1%) and distant metastases in 71 of 123 patients (57.7%). Overall, the change in treatment intent and treatment type was recorded in 64 of 171 cases (37.4%) and 56 of 171 cases (32.8%), respectively. The presence of metastases on [18F]FDG PET/CT was associated with shorter progression-free survival at the initial staging (P = 0.04) and shorter overall survival at the time of recurrence (P = 0.002). All quantitative metabolic tumor parameters correlated with progression-free survival and overall survival. Conclusion: [18F]FDG PET/CT frequently detects additional sites of disease compared with conventional imaging in patients with sarcomas that were being considered for curative-intent or salvage therapy. This increased detection impacts the clinical management in a third of patients referred for initial staging or presumed limited recurrence after primary therapy. The presence of metastases on [18F]FDG PET/CT is associated with poorer outcomes.

Molecular imaging of sarcomas with FDG PET

Sarcoma comprises a heterogenous entity of musculoskeletal malignancies arising from a mesenchymal origin. The diagnosis and management of pediatric sarcoma requires a multidisciplinary approach and the use of various imaging modalities including CT, MRI and FDG PET scans. FDG PET/CT (FDG PET), as a metabolic imaging, complements and provides superior diagnostic information as against other imaging modalities alone. Advantages of FDG PET in differentiating malignant sarcomatous lesions from benign lesions, and value in staging and restaging have been noted in several studies. The use of FDG PET in clinical management has increased over the years. The data on prognostication of outcomes or predicting responders to therapy with FDG PET in patients with sarcoma is somewhat limited. This review will focus on the pearls and pitfalls of FDG PET and role of FDG PET in initial extent of disease assessment, treatment response, and surveillance imaging pertaining to osteosarcoma, chondrosarcoma, Ewing's sarcoma, and rhabdomyosarcoma. We also discuss the limitations and unmet needs of FDG PET in the management of patients with sarcoma.

Follow-up Strategies for Primary Extremity Soft-tissue Sarcoma in Adults: A Systematic Review of the Published Literature

AIM

Follow-up strategies for primary extremity soft-tissue sarcomas (eSTS) in adults were evaluated in a systematic review of the published literature.

MATERIAL AND METHODS

The published literature was reviewed using PubMed. Of 136,646 studies published between 1985 and 2019, 78 original articles met the inclusion criteria. Articles were selected on the basis of the PRISMA guidelines. The selected articles were then cross-searched to identify further publications. August 1, 2019 was used as the concluding date of publication.

RESULTS

A variety of follow-up schedules have been reported in recently published literature. Two official guidelines have been approved by international societies. The guidelines distinguish between high- and low-grade STS, but mention a wide range of follow-up intervals. Established tools of follow-up include computed tomograph, X-rays of the chest, and magnetic resonance imaging of the primary tumor site in addition to clinical observation and physical examination.

CONCLUSION

Further research will be needed to establish evidence-based guidelines and schedules for follow-up strategies in patients with eSTS.

PET in the Diagnostic Management of Soft Tissue Sarcomas of Musculoskeletal Origin

Soft tissue sarcomas (STSs) account for less than 1% of adult solid tumors and about 7% of pediatric malignancies, causing 2% of cancer-related deaths. With the advent of PET-computed tomography (CT), the value of (18) fluorine-2-fluoro-2-deoxy-d-glucose (FDG) PET imaging to improve the management of STSs has been explored. FDG PET imaging has been found useful in restaging and treatment response assessment. This article reviews current knowledge and application of FDG PET-CT in initial diagnosis, staging, restaging, treatment response monitoring, and prognosis, with a brief overview of the most common histologic subtypes of STS.

Comparison of MRI and PET-CT in detecting the loco-regional recurrence of soft tissue sarcomas during surveillance

OBJECTIVE

To investigate the diagnostic performance of MRI and PET-CT for the detection of loco-regional recurrences after soft tissue sarcoma (STS) excision.

MATERIALS AND METHODS

From Dec 2003 to Aug 2014, 394 patients with STSs, who were included in the electronic patient registry for initial or repeated surgery at our hospital, were retrospectively reviewed. We identified 152 patients who underwent regular postoperative follow-ups with both MRI and PET-CT, obtained within a 3 month period of each other. We analyzed differences in the performance of MRI and PET-CT for the diagnosis of loco-regional recurrences using McNemar's test. The receiver-operating characteristic curves and calculations of the area under the curve were used.

RESULTS

Twenty patients were found to have a loco-regional recurrence after tumor excision. For MRI and PET-CT, the sensitivities were 90.0 and 95.0 %, and the specificities 97.7 and 95.5 %, respectively, with positive predictive values of 85.7 and 76.0 % and negative predictive values of 98.5 and 99.2 %, respectively. No significant difference was detected between the sensitivities of MRI and PET-CT (p = 0.125). The area under the receiver-operating characteristic curve for PET-CT (0.952) was not significantly greater than that for MRI (0.939; p = 0.6).

CONCLUSION

MRI of the area of interest is recommended for evaluation of tumor recurrence after surgical excision of STS. PET-CT was shown to be effective for detection of STS recurrence, and comparable to MRI. However, if PET-CT or MRI findings are inconclusive, the other modality may be helpful in differentiating tumor recurrence from post-therapeutic tissue change.

The value of intratumoral heterogeneity of (18)F-FDG uptake to differentiate between primary benign and malignant musculoskeletal tumours on PET/CT

OBJECTIVE

The cumulative standardized uptake value (SUV)-volume histogram (CSH) was reported to be a novel way to characterize heterogeneity in intratumoral tracer uptake. This study investigated the value of fluorine-18 fludeoxyglucose ((18)F-FDG) intratumoral heterogeneity in comparison with SUV to discriminate between primary benign and malignant musculoskeletal (MS) tumours.

METHODS

The subjects comprised 85 pathologically proven MS tumours. The area under the curve of CSH (AUC-CSH) was used as a heterogeneity index, with lower values corresponding with increased heterogeneity. As 22 tumours were indiscernible on (18)F-FDG positron emission tomography, maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean) and AUC-CSH were obtained in 63 positive tumours. The Mann-Whitney U test and receiver operating characteristic (ROC) analysis were used for analyses.

RESULTS

The difference between benign (n = 35) and malignant tumours (n = 28) was significant in AUC-CSH (p = 0.004), but not in SUVmax (p = 0.168) and SUVmean (p = 0.879). The sensitivity, specificity and accuracy for diagnosing malignancy were 61%, 66% and 64% for SUVmax (optical threshold value, >6.9), 54%, 60% and 57% for SUVmean (optical threshold value, >3) and 61%, 86% and 75% for AUC-CSH (optical threshold value, ≤0.42), respectively. The area under the ROC curve was significantly higher in AUC-CSH (0.71) than SUVmax (0.60) (p = 0.018) and SUVmean (0.51) (p = 0.005).

CONCLUSION

The heterogeneity index, AUC-CSH, has a higher diagnostic accuracy than SUV analysis in differentiating between primary benign and malignant MS tumours, although it is not sufficiently high enough to obviate histological analysis.

ADVANCES IN KNOWLEDGE

AUC-CSH can assess the heterogeneity of (18)F-FDG uptake in primary benign and malignant MS tumours, with significantly greater heterogeneity associated with malignant MS tumours. AUC-CSH is more diagnostically accurate than SUV analysis in differentiating between benign and malignant MS tumours.

Noninvasive imaging of peripheral nerves

Recent developments in the field of peripheral nerve imaging extend the capabilities of imaging modalities to assist in the diagnosis and treatment of patients with peripheral nerve maladies. Methods such as magnetic resonance imaging (MRI) and its derivative diffusion tensor imaging (DTI), ultrasound (US) and positron emission tomography (PET) are capable of assessing nerve structure and function following injury and relating the state of the nerve to electrophysiological and histological analysis. Of the imaging methods surveyed here, each offered unique and interesting advantages related to the field. MRI offered the opportunity to visualize immune activity on the injured nerve throughout the course of the regeneration process, and DTI offered numerical characterization of the injury and the ability to develop statistical bases for diagnosing injury. US extends imaging to the treatment phase by enabling more precise analgesic applications following surgery, and PET represents a novel method of assessing nerve injury through analysis of relative metabolism rates in injured and healthy tissue. Exciting new possibilities to enhance and extend the abilities of imaging methods are also discussed, including innovative contrast agents, some of which enable multimodal imaging approaches and present opportunities for treatment application.

Prognostic value of 18F-FDG PET/CT in patients with soft tissue sarcoma: comparisons between metabolic parameters

OBJECTIVES

To investigate the relationship between volume-based PET parameters and prognosis in patients with soft tissue sarcoma (STS).

METHODS

We retrospectively reviewed 55 patients with pathologically proven STS who underwent pretreatment with (18) F-Fluorodeoxyglucose ((18)F-FDG) PET/CT. The maximum standardized uptake value (SUVmax), average SUV (SUVavg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of primary tumors were measured using a threshold SUV as liver activity for determining the boundary of tumors. Univariate and multivariate survival analyses for overall survival were performed according to the metabolic parameters and other clinical variables.

RESULTS

Cancer-related death occurred in 19 of 55 patients (35 %) during the follow-up period (29 ± 23 months). On univariate analysis, AJCC stage (stage IV vs. I-III, hazard ratio (HR) = 2.837, p = 0.028), necrosis (G2 vs. G0-G1, HR = 3.890, p = 0.004), SUVmax (1 unit - increase, HR = 1.146, p = 0.008), SUVavg (1 unit - increase, HR = 1.469, p = 0.032) and treatment modality (non-surgical therapy vs. surgery, HR = 4.467, p = 0.002) were significant predictors for overall survival. On multivariate analyses, SUVmax (HR = 1.274, p = 0.015), treatment modality (HR = 3.353, p = 0.019) and necrosis (HR = 5.985, p = 0.006) were identified as significant independent prognostic factors associated with decreased overall survival.

CONCLUSIONS

The SUVmax of the primary tumor is a significant independent metabolic prognostic factor for overall survival in patients with STS. Volume-based PET parameters may not add prognostic information outside of the SUVmax.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

PET/MRI Imaging in High-Risk Sarcoma: First Findings and Solving Clinical Problems

Simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) is a new whole-body hybrid PET/MR imaging technique that combines metabolic and cross-sectional diagnostic imaging. Since the use of MRI in imaging of soft-tissue sarcoma is extremely beneficial, investigation of the combined PET/MRI is of great interest. In this paper, we present three cases and first data. Combined PET/MRI technique can support the process of clinical decision-making and give answers to some meaningful questions when treating patients with STS. Therefore, the combined modality of simultaneous PET/MRI offers new pieces to the puzzle of sarcoma treatment.

(18) F-fluorodeoxyglucose positron emission tomography/computed tomography for the detection of recurrent bone and soft tissue sarcoma

BACKGROUND

The clinical utility of modern hybrid imaging modalities for detecting recurrent bone or soft tissue sarcoma remains to be determined. In this report, the authors present a clinical study on the diagnostic accuracy and incremental value of integrated (18) F-fluorodeoxyglucose positron emission tomography/computed tomography ((18) F-FDG PET/CT) in patients with a history of sarcoma who have clinically suspected disease recurrence.

METHODS

Forty-three patients who had a history of bone or soft tissue sarcoma and had documented complete remission underwent (18) F-FDG PET/CT. Image analysis was performed independently for (18) F-FDG PET (n = 43) and for contrast-enhanced spiral CT (CE-CT) (n = 30) by 2 separate readers, whereas combined (18) F-FDG PET/CT (n = 43) images were analyzed in consensus by both readers. Imaging findings were rated on a 5-point scale and finally were reported as malignant, benign, or equivocal. Imaging findings were validated either by histopathology (n = 24) or by clinical follow-up (n = 19).

RESULTS

(18) F-FDG PET/CT had greater sensitivity and specificity compared with CE-CT alone (94% and 92% vs 78% and 67%, respectively), resulting in significantly greater accuracy (93% vs 73%; P = .03). (18) F-FDG PET/CT was particularly superior regarding detection of local recurrence or soft tissue lesions (sensitivity and specificity: 83% and 100% vs 50% and 100%, respectively) or bone metastases (100% and 100% vs 85% and 88%, respectively).

CONCLUSIONS

(18) F-FDG PET/CT had greater diagnostic accuracy in the detection of recurrent bone or soft tissue sarcoma compared with CE-CT alone. The detection of local recurrence was the most evident advantage of (18) F-FDG PET/CT over CE-CT. Cancer 2013. © 2012 American Cancer Society.

FDG PET/CT in Initial Staging of Adult Soft-Tissue Sarcoma

Soft-tissue sarcomas spread predominantly to the lung and it is unclear how often FDG-PET scans will detect metastases not already obvious by chest CT scan or clinical examination. Adult limb and body wall soft-tissue sarcoma cases were identified retrospectively. Ewing's sarcoma, rhabdomyosarcoma, GIST, desmoid tumors, visceral tumors, bone tumors, and retroperitoneal sarcomas were excluded as were patients imaged for followup, response assessment, or recurrence. All patients had a diagnostic chest CT scan. 109 patients met these criteria, 87% of which had intermediate or high-grade tumors. The most common pathological diagnoses were leiomyosarcoma (17%), liposarcoma (17%), and undifferentiated or pleomorphic sarcoma (16%). 98% of previously unresected primary tumors were FDG avid. PET scans were negative for distant disease in 91/109 cases. The negative predictive value was 89%. Fourteen PET scans were positive. Of these, 6 patients were already known to have metastases, 3 were false positives, and 5 represented new findings of metastasis (positive predictive value 79%). In total, 5 patients were upstaged by FDG-PET (4.5%). Although PET scans may be of use in specific circumstances, routine use of FDG PET imaging as part of the initial staging of soft-tissue sarcomas was unlikely to alter management in our series.

Optimal management of pulmonary metastases from colorectal cancer

The incidence of colorectal cancers is rising worldwide and pulmonary metastases were seen in approximately 10-15% of all patients. Surgical metastasectomy is a widely accepted procedure in selected patients and is considered as the only curative option in patients with secondary pulmonary malignancy. But surgical resection remains controversial due to the lack of randomized trials, comparing pulmonary metastasectomy to control, either medical therapy, or observation. This article will discuss the differentiated therapeutic strategies for patients with pulmonary metastases of colorectal cancer, focusing on surgical resection, patient evaluation, prognostic factors, interdisciplinary therapeutic approaches and current trials.

Value of PET scan in patients with retroperitoneal sarcoma treated with preoperative radiotherapy

PURPOSE

Preoperative radiotherapy provides advantages in the management of retroperitoneal sarcoma (RPS). We describe our experience treating a cohort who underwent pre- and post-radiotherapy functional imaging with FDG-PET scan.

METHODS AND MATERIALS

Consecutive patients presenting between January 1999 and December 2009 with a diagnosis of either primary or recurrent RPS were identified from the hospital patient record database using ICD codes, and cross-referenced with the completed radiotherapy course database. Those patients suitable for preoperative radiotherapy and surgery who underwent both pre- and post-radiotherapy FDG-PET were included. Exclusions included presence of metastatic disease, age under 18 years and/or paediatric histology, and treatment with palliative intent.

RESULTS

Eleven patients were included, of whom six were male. Median age was 63 years (range, 38-78 years). The majority of patients had Stage T2b, high-grade disease. Ten patients were treated at initial presentation and one at first local recurrence. A malignant diagnosis was confirmed in all patients who underwent CT-guided core biopsy; a diagnosis of sarcoma was reached in 91%. Sensitivity of FDG-PET imaging was 100%. Metabolic partial or complete response did not correlate with change in tumour size, nor pathological response assessment. Pulmonary and hepatic metastatic disease was detected in one patient on post-treatment imaging. All patients in the cohort completed preoperative radiotherapy. There was no grade 3 or 4 toxicity. Sixty-four percent proceeded to radical resection. Complete macroscopic excision was achieved in all cases. There was no perioperative mortality.

CONCLUSION

Combined therapy with preoperative radiotherapy and surgery has acceptable levels of toxicity. CT-guided core biopsy is an accurate means of confirming a diagnosis of RPS prior to definitive treatment. Utility of PET scan in the management of RPS is evolving and further investigation is warranted.

F18-FDG PET/CT Scanning in Angiosarcoma: Report of Two Cases

Angiosarcomas are uncommon tumors and constitute less than 5% of all soft tissue sarcomas. They are aggressive tumors with poor prognosis, therefore, it is quite important to determine disease extension and detect local recurrence and/or distant metastases for appropriate therapy management. In this paper, we aimed to demonstrate the potential role of 1F18-FDG PET/CT imaging by reporting two cases with angiosarcoma.

Conflict of interest:None declared.

Soft tissue tumours of the retroperitoneum

Purpose. This review summarizes the more prevalent soft tissue tumours arising in the retroperitoneum and highlights some recent fundamental and diagnostic developments relevant to mesenchymal tumours.

Discussion. The retroperitoneum is an underestimated site for benign and malignant neoplastic disease, and represents the second most common site of origin of primary malignant soft tissue tumours (sarcomas) after the deep tissues of the lower extremity. In contrast to the predominance of benign soft tissue lesions over malignant sarcomas elsewhere, retroperitoneal mesenchymal lesions are far more likely to be malignant. The differential diagnosis is primarily with the more common lymphoproliferative and parenchymatous epithelial lesions arising in this area, and with metastatic disease from known or unknown primary sites elsewhere.The most prevalent mesenchymal tumours at this site are of a lipomatous, myogenic or neural nature.Their generally late clinical presentation and poorly accessible location provides numerous clinical challenges; optimal radiological imaging and a properly performed biopsy are essential cogs in the management route. Histopathological diagnosis may be complicated, but has been aided by developments in the fields of immunohistochemistry and tumour (cyto)genetics. Despite significant advances in oncological management protocols, the prognosis remains generally less favourable than for similar tumours at more accessible sites.

PET imaging for pediatric oncology: an assessment of the evidence

Positron emission tomography (PET) has shown potential benefits when used in therapeutic clinical trials for children with cancer. However, existing trials are limited in scope with small numbers of patients and varied observations, making accurate conclusions about the usefulness of PET scanning impossible. This review examines PET and its applications in pediatric oncology. While evidence is limited, there appears to be a basis for rigorous evaluation of this imaging modality before widespread application without validation from clinical trials.

[Combined functional and morphological imaging of sarcomas: significance for diagnostics and therapy monitoring]

(18)F-fluorodeoxyglucose positron-emission tomography (FDG-PET) and especially hybrid FDG-PET/CT is becoming more and more accepted for the clinical management of adult and pediatric patients with sarcomas. By integrating the CT component the specificity in particular but also the sensitivity of the modality are improved further. With PET/CT a complete staging including the detection of lung metastases is feasible in a single examination. For patients with primary bone and soft tissue sarcomas FDG-PET/CT is utilized for diagnosis, staging and restaging, metabolic tumor grading, guidance of biopsies, detection of tumor recurrence and therapy monitoring. Furthermore, it has been demonstrated that FDG uptake of the tumor prior to treatment and changes of FDG uptake after therapy significantly correlate with histopathologic response and survival of patients. Therefore, PET and PET/CT have a prognostic value. In the future new perspectives of hybrid PET/CT imaging will arise by introducing novel radiotracers and combined functional imaging of tumor metabolism and perfusion. High resolution MRI is essential for local evaluation of the primary tumor and preoperative planning with assessment of possible infiltration of vascular or neural structures. Contrast-enhanced MRI remains a key tool in the diagnosis of recurrent disease, especially in tumors which are not hypermetabolic. Dynamic contrast-enhanced MR sequences can significantly contribute to therapy monitoring. More research is necessary to prospectively compare dynamic contrast-enhanced MRI and FDG-PET/CT for evaluation of local and recurrent diseases.

Integrated FDG-PET-CT: its role in the assessment of bone and soft tissue tumors

PURPOSE

The purpose of this study was to evaluate prospectively, whether integrated 2-deoxy-2-[(18)F]fluoro-D: -glucose positron emission tomography-computed tomography (FDG-PET-CT) is more accurate for determination musculoskeletal tumors compared with separate interpretation of CT and FDG-PET, because most of the current clinical data come from patients studied with PET.

METHODS

Eighty patients with newly diagnosed musculoskeletal tumors underwent FDG-PET-CT. CT, FDG-PET, and FDG-PET-CT were interpreted separately to determine the performance of each imaging modality.

RESULTS

Assuming that equivocal lesions are benign, performance of diagnostic tests was as follows: sensitivity, specificity and accuracy for CT alone was 81, 84, 83%, for PET 71, 82, 76, and for PET-CT 80, 83 and 86%. Assuming that equivocal lesions are malignant, sensitivity, specificity, and accuracy for CT was 61, 100, 70%, for PET 69, 100, 79, and for PET-CT 69, 100 and 79%.

CONCLUSIONS

Combined FDG-PET-CT reliably differentiates soft tissue and bone tumors from benign lesions. The value of the information provided by FDG-PET-CT for planning surgical procedures must be evaluated in further studies.

Pulmonary metastasectomy for soft tissue sarcomas: is it justified?

Pulmonary metastases are common in patients following resection for soft tissue sarcoma. Pulmonary resection of metastatic soft tissue sarcomas is widely practiced in surgical oncology. No randomized phase III trials are available, and data for this review were retrieved only from retrospective studies. This article addresses the issues of patient selection, surgical technique, and adjuvant chemotherapy, and provides the surgical oncologist with a current review of pulmonary metastasectomy in metastatic soft tissue sarcoma. In summary, there is a substantial body of evidence demonstrating that resection of soft tissue pulmonary metastases can be performed safely and with a low mortality rate. For a subset of highly selected patients, the overall results of a 5-year actuarial survival rate ranged between 25% and 37.6%. These outcomes exceed those normally associated with metastatic soft tissue sarcoma and are well comparable with surgical resection for other malignancies.

Occult myofibroblastic sarcoma detected on FDG-PET performed for cancer screening

We present a rare case of occult low-grade myofibroblastic sarcoma (LGMFS) detected by marked 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) uptake on positron emission tomography (PET). A 46-year-old woman presented with abnormal FDG uptake in her back when FDG-PET was performed for cancer screening. The maximum standard uptake values (SUVmax) were 9.8. Physical examination and laboratory investigations revealed no abnormalities. Magnetic resonance images demonstrated an ill-defined 2 x 3 cm mass in the multifidus muscle. Excisional biopsy led to a pathological diagnosis of LGMFS. Additional wide resection was performed for local control. No local recurrence or distant metastasis was observed 12 months after the initial operation. This is the first report describing FDG-PET findings of LGMFS, suggesting a discrepancy between histological grade and SUV intensity in this low-grade entity.

Guidelines for 18F-FDG PET and PET-CT imaging in paediatric oncology

OBJECTIVE

The purpose of these guidelines is to offer to the nuclear medicine team a framework that could prove helpful in daily practice. These guidelines contain information related to the indications, acquisition, processing and interpretation of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) in paediatric oncology. The Oncology Committee of the European Association of Nuclear Medicine (EANM) has published excellent procedure guidelines on tumour imaging with (18)F-FDG PET (Bombardieri et al., Eur J Nucl Med Mol Imaging 30:BP115-24, 2003). These guidelines, published by the EANM Paediatric Committee, do not intend to compete with the existing guidelines, but rather aim at providing additional information on issues particularly relevant to PET imaging of children with cancer.

CONCLUSION

The guidelines summarize the views of the Paediatric Committee of the European Association of Nuclear Medicine. They should be taken in the context of "good practice" of nuclear medicine and of any national rules, which may apply to nuclear medicine examinations. The recommendations of these guidelines cannot be applied to all patients in all practice settings. The guidelines should not be deemed inclusive of all proper procedures or exclusive of other procedures reasonably directed to obtaining the same results.

Diagnostic efficacy of bone scintigraphy, magnetic resonance imaging, and positron emission tomography in bone metastases of myxoid liposarcoma

Myxoid liposarcomas (MLS) have a tendency to metastasize to unusual sites. We report an unusual case of bone metastases not detected by bone scan and neither by fluorodeoxyglucose positron emission tomography (PET-FDG) and successfully identified with magnetic resonance imaging (MRI) in a patient with metachronic MLS. Histopathological examination of the primary tumor evidenced a tumor with unfavorable prognostic markers, and the biopsy of an iliac bone lesion confirmed the diagnosis of metastatic disease. On histological grounds, the tumor showed features of a more differentiated neoplasm without foci of round cells or necrosis in the latter. MRI allowed the identification of disseminated disease compared to computed tomography (CT) and PET scans. Thus, because of the heterogeneous histological features of MLS and the biological behavior of the disease, a combined approach of FDGPET-CT and MRI, may allow a more accurate staging of soft tissue sarcomas.

Unusual metastases from extremity soft tissue sarcomas

The most common metastatic route for extremity soft-tissue sarcomas is via the venous system to the lungs. Metastases to other sites such as the brain, liver, and soft tissue distant from the primary tumor are rare. A tumor registry, prospectively kept since 1986, was reviewed for unusual metastatic spread. Of 3671 tumors, 346 high-grade extremity soft-tissue sarcomas were evaluated. A total of 15 patients (4.3%) presented with initial recurrence of disease that was extrapulmonary and distant from the site of the primary tumor. Four of these patients (27%) were successfully treated for their recurrence. Based on these findings, a different strategy for follow-up of patients after treatment of a high-grade extremity soft-tissue sarcoma is suggested.

Bone and soft-tissue sarcoma: preoperative staging with fluorine 18 fluorodeoxyglucose PET/CT and conventional imaging

PURPOSE

To retrospectively compare the diagnostic accuracy of positron emission tomography (PET)/computed tomography (CT), PET, conventional imaging, and combined PET/CT and conventional imaging for tumor staging of bone and soft-tissue sarcomas, by using histologic or follow-up imaging findings as the reference standard.

MATERIALS AND METHODS

Institutional review board approval was received for this HIPAA-compliant study; informed consent was obtained. Integrated PET/CT was performed in 117 patients (69 male patients, 48 female patients; mean age, 42 years +/- 21 [standard deviation]; range, 9-86 years). Conventional imaging consisted of magnetic resonance imaging of the primary site, chest radiography, whole-body contrast material-enhanced CT, and bone scintigraphy. A total of four reviewers assessed all images. Overall and T staging were evaluated in 69 (59%) patients who underwent surgical removal of the primary tumors and had pathologically proved results. N and M staging were evaluated in all patients, and their reference methods were based on histologic findings (n = 101) and follow-up CT findings (n = 16).

RESULTS

Interpretations based on combined PET/CT and conventional imaging findings correctly staged tumors in 60 (87%) of 69 patients, overstaged tumors in eight (12%) patients, and understaged tumors in one (1%) patient. Overall staging accuracy of combined PET/CT and conventional imaging was significantly higher than that at PET (P < .0001). Combined PET/CT and conventional imaging resulted in correct N staging in 114 (97%) of 117 patients and M staging in 109 (93%) of 117 patients. Combined PET/CT and conventional imaging helped reduce overstaging in three (4%) patients and helped change tumor diagnosis from unresectable to resectable in two (2%) patients compared with PET/CT.

CONCLUSION

The combination of PET/CT and conventional imaging is accurate in preoperative staging of bone and soft-tissue sarcoma.

Positron emission tomography/computed tomography with 18fluoro-deoxyglucose in the detection of local recurrence and distant metastases of pediatric sarcoma

BACKGROUND

Combined positron emission tomography with (18)fluoro-deoxyglucose and computed tomography (FDG-PET/CT) has been used in the diagnosis and staging of various malignancies, but their use in the management of pediatric sarcomas is less well defined. The potential role of FDG-PET/CT in the diagnosis of local recurrence and distant metastases of pediatric sarcomas was investigated.

PROCEDURE

Nineteen children (aged 2-21) with sarcoma (9 Ewing sarcoma, 3 osteogenic sarcoma, 7 rhabdomyosarcoma) were evaluated between January 2000 and December 2005 by FDG-PET/CT for suspected local relapse or distant metastases. The results of 21 FDG-PET studies, 16 CT scans, 9 magnetic resonance imaging (MRI) studies, and 7 bone scans (BSs) were compared with surgical pathology or clinical follow-up for at least 3 months.

RESULTS

FDG-PET detected local relapse in all seven patients and distant metastases in 10/13 (77%). FDG-PET/CT and CT/MRI/BS results were discordant in eight patients. FDG-PET/CT was the only modality that detected distant metastases in two patients. PET/CT was true negative and excluded disease in three patients with abnormal CT/BSs and was false negative in three patients with distant metastases.

CONCLUSION

FDG-PET/CT may be useful and complementary to other imaging modalities for the detection of recurrent pediatric sarcomas, especially at the primary site. Its potential advantages and limitations compared with conventional imaging modalities need to be further investigated in larger homogenous patient groups.

18fluorodeoxyglucose positron emission tomography in the prediction of relapse in patients with high-risk, clinical stage I nonseminomatous germ cell tumors: preliminary report of MRC Trial TE22--the NCRI Testis Tumour Clinical Study Group

PURPOSE

There are several management options for patients with clinical stage I (CS1) nonseminomatous germ cell tumors (NSGCT); this study examined whether an 18fluorodeoxyglucose positron emission tomography (18FDG PET) scan could identify patients without occult metastatic disease for whom surveillance is an attractive option.

METHODS

High-risk (lymphovascular invasion positive) patients with CS1 NSGCT underwent 18FDG PET scanning within 8 weeks of orchidectomy or marker normalization. PET-positive patients went off study; PET-negative patients were observed on a surveillance program. The primary outcome measure was the 2-year relapse-free rate (RFR) in patients with a negative PET scan (the negative predictive value). Assuming an RFR of 90% to exclude an RFR less than 80% with approximately 90% power, 100 PET-negative patients were required; 135 scanned patients were anticipated.

RESULTS

Patients were registered between May 2002 and January 2005, when the trial was stopped by the independent data monitoring committee due to an unacceptably high relapse rate in the PET-negative patients. Of 116 registered patients, 111 underwent PET scans, and 88 (79%) were PET-negative (61% of preorchidectomy marker-negative patients v 88% of marker-positive patients; P = .002); 87 proceeded to surveillance, and one requested adjuvant chemotherapy. With a median follow-up of 12 months, 33 of 87 patients on surveillance relapsed (1-year RFR, 63%; 90% CI, 54% to 72%).

CONCLUSION

Though PET identified some patients with disease not detected by computed tomography scan, the relapse rate among PET negative patients remains high. The results show that 18FDG PET scanning is not sufficiently sensitive to identify patients at low risk of relapse in this setting.

Advances in metabolic imaging for surgical oncology

This review focuses on several aspects of molecular imaging. First, current positron emission tomography (PET)/CT scanner technology and several novel imaging techniques that are being developed are briefly discussed. Next, current clinical indications for (18)F FDG PET and PET/CT that are relevant to the surgical oncologist are discussed. Finally, advances in molecular imaging that may herald the next generation of PET radiotracers beyond (18)F FDG are reviewed.

Role of PET/PET-CT in the management of sarcomas

Positron emission tomography (PET) is a functional diagnostic imaging technique that provides very different information from that obtainable with other imaging modalities. The most widely used radiotracer is F-18 fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. The FDG uptake in cells is directly proportional to glucose metabolism, which is increased many times in malignant cells. FDG-PET is now the standard of care in initial staging, monitoring the response to therapy and management of various cancers (e.g., breast cancer, lung cancer and lymphoma). However, the paucity of anatomical landmarks on PET images makes a consistent hardware fusion to anatomical cross-sectional data extremely useful. The introduction of combined PET-computer tomography (CT) scanners, which provide not only functional, but also structural information leading to a detection of subcentimeter lesions, made this technique useful in the early detection of the disease process and decreasing false-positive lesions. The aim of this article is to review the clinical applications (i.e., diagnosis, staging, evaluation of treatment response and restaging) using PET in patients with bone and soft-tissue sarcoma.

Is PET useful in detecting occult nonpulmonary metastases in pediatric bone sarcomas?

Orthopaedic oncologists are increasingly utilizing positron emission tomography (PET) technology in the initial workup and staging of sarcomas and for monitoring treatment response. We evaluated the use of PET with fluorine-18-fluoro-2-deoxy D-glucose (FDG) to detect occult nonpulmonary metastases in patients < age 30 newly diagnosed with either Ewing's or osteosarcoma, and the impact of this information upon therapeutic decision making. We retrospectively reviewed prospectively collected data (1994-2004) on 55 patients age < 30 years old over a 10 year span. PET detected metastases in 12/55 (22%) of these patients, eight of whom (67%) harbored disease outside the lung; however, only 4/55 (7%) were upstaged to Stage IV specifically due to findings determined by PET alone. Three of 17 (18%) Ewing's sarcoma patients, but only one of 38 (3%) osteosarcoma patients, were upstaged by PET alone. The most important alteration in treatment decisions was the substitution of irradiation in lieu of surgery for local control in Ewing's sarcoma patients.

LEVEL OF EVIDENCE

Diagnostic study, level II.

F-18 Fluorodeoxyglucose PET/CT as an Imaging Tool for Staging and Restaging Cutaneous Angiosarcoma of the Scalp

Cutaneous angiosarcoma of the scalp is a rare highly aggressive malignant tumor that typically afflicts elderly patients and commonly presents with extensive local spread and distant metastasis. Distant metastases favor lung, liver, lymph nodes, and skin. Overall, the prognosis is poor. It differs from other soft tissue sarcomas in that the size of the lesion at presentation instead of tumor grade is the important prognostic factor. Optimal treatment is yet to be determined. Wide-margin complete excision with postoperative radiotherapy has been the most effective therapy. Chemotherapy and gene therapy have been used with some success. Local extent is critical in surgical planning, especially in the head and face, and is difficult to determine accurately with clinical examination and morphologic imaging tools. We report the case of a 70-year-old man diagnosed with multifocal angiosarcoma of the scalp. PET/CT imaging with F-18 2-fluoro-2-deoxyglucose (F-18 FDG) not only showed avid FDG uptake by an angiosarcoma (SUVmax = 10.7), but also simultaneously showed local extension of multifocal lesions with periosteal involvement and excluded metastatic abdominal nodal disease. PET/CT imaging after chemotherapy and before radiation therapy showed complete resolution of FDG uptake in the scalp and osseous lesions. Evaluation of more cases of this subset of soft tissue sarcoma with FDG PET/CT may suggest a possible role in not only staging angiosarcomas to determine the extent of local as well as distant disease, but also to potentially help determine response to therapy and early recognition of local or distant recurrence.

Tumors of the peripheral nerves and plexuses

Peripheral nerve tumors are a diverse group of lesions histologically and in their clinical behavior. The genetic disorders neurofibromatosis type 1 and 2 and schwannomatosis are significant risk factors for the development of peripheral nerve tumors. An understanding of these disorders is important in allowing appropriate management. Active treatment of peripheral nerve tumors is reserved for lesions that are malignant or causing neurologic dysfunction, pain, compressive symptomatology, or cosmetic concern. The mainstay of treatment is surgical intervention, the nature of which will vary with the type of tumor and anatomical location. In the case of malignant tumors, adjuvant chemotherapy and radiotherapy are commonly used. Developments in the understanding of the genetics and molecular biology of peripheral nerve tumors are opening up potentially exciting new avenues of treatment. The prognosis of benign peripheral nerve tumors is excellent, with a recurrence rate of just 5% or less after successful surgery. Malignant tumors have proven to be more challenging, with a much higher recurrence rate and a 5-year survival rate of 64%.

Sarcomes des tissus mous des extrémités. Rôle de l'imagerie dans la prise en charge initiale

Soft tissue sarcomas are uncommon heterogeneous group of tumour derived from mesenchym. The most common location is the lower extremity, but they can occur in the upper extremity, and abdominal and chest walls. The first radiological evaluation may include plain films and ultrasonography in viewing to assess the probability of soft tissue sarcomas. MRI with contrast is the main modality to evaluate these lesions and choose which part of tumour must be biopsied. Computer tomography (CT) is secondary used to perform core needle biopsy and detect lung metastases. The role of PET begins to be more clear in case of need global assessment before radical surgery. A multidisciplinary approach is essential to perform rational treatment planning and avoid partial surgery.

Imaging and diagnostic strategy of soft tissue tumors in children

The diagnosis of a soft tissue mass in children is a common clinical situation. Most of the lesions are benign and can be treated conservatively or by non-mutilating surgery. Nevertheless, the possibility of a malignant soft tissue tumor must be systematically considered. The most frequent benign soft tissue lesions in children are vascular lesions, fibrous and fibrohistiocytic tumors and pseudotumors, whereas rhabdomyosarcomas account for 50% of all soft tissue sarcomas. A child presenting an atypical soft tissue mass should be managed by a multidisciplinary centre, and primary resection must be proscribed until a definite diagnosis has been established. The role of imaging is essential either to confirm the benign nature of the mass or to give arguments to perform a diagnostic biopsy. Clinical examination, conventional radiography and ultrasound with Doppler represent the first-line examinations and are sometimes sufficient to assess a diagnosis. In all other situations, MRI is mandatory to establish the probable nature of the lesion and to assess local extension.

Primary synovial sarcoma of the lung

A 45 -year-old woman presented chest pain and a well-defined oval shaped mass on a chest radiograph. A malignant pulmonary tumor was suspected and a right pneumonectomy was performed. The tumor measured about 13 x 12 cm, was pale-yellow in color and soft in texture. Histologically, it had round to oval and spindle-shaped cells with minimal cytoplasm, hyperchromatic nuclei, inconspicuous mitoses and only slight fibrous stroma. Immunohistochemically, the tumor cells were positive for vimentin, CD 99, BCL-2 protein and EMA. The reverse transcriptase-polymerase chain reaction (RT-PCR), using RNA extracted from fresh-frozen tissue, demonstrated SYT/SSX-2 fusion transcripts, confirming the diagnosis of synovial sarcoma.

Imaging of Metastatic Disease to the Thorax

Tumor imaging is at the forefront of radiology technology and is the focus of most cutting edge research. Radiologic applications for imaging of metastases are applied to initial staging, restaging after neoadjuvant therapy, and follow-up surveillance after therapy for tumor recurrence. CT is the routine imaging choice in staging, restaging, and detection of recurrence. Fluorodeoxyglucose-positron emission tomography has evolved as an imaging modality that further improves staging as well as the detection of recurrent and metastatic disease.