F-18 FDG PET and PET/CT evaluation of response to chemotherapy in bone and soft tissue sarcomas. Clin Nucl Med. 2008;33:8-13. [PMID: 18097248 DOI: 10.1097/rlu.0b013e31815c4fd4]

A bibliometric analysis based on hotspots and frontier trends of positron emission tomography/computed tomography utility in bone and soft tissue sarcoma

Purpose

This study aimed to analyze articles on the diagnosis and treatment of bone and soft tissue sarcoma using positron emission tomography (PET)/computed tomography (CT) published in the last 13 years. The objective was to conduct a bibliometric analysis and identify the research hotspots and emerging trends.

Methods

Web of Science was used to search for articles on PET/CT diagnosis and treatment of bone and soft tissue sarcoma published from January 2010 to June 2023. CiteSpace was utilized to import data for bibliometric analysis.

Results

In total, 425 relevant publications were identified. Publications have maintained a relatively stable growth rate for the past 13 years. The USA has the highest number of published articles (139) and the highest centrality (0.35). The UDICE-French Research Universities group is the most influential institution. BYUN BH is a prominent contributor to this field. The Journal of Clinical Oncology has the highest impact factor in the field.

Conclusion

The clinical application of PET/CT is currently a research hotspot. Upcoming areas of study concentrate on the merging of PET/CT with advanced machine learning and/or alternative imaging methods, novel imaging substances, and the fusion of diagnosis and therapy. The use of PET/CT has progressively become a crucial element in the identification and management of sarcomas. To confirm its efficacy, there is a need for extensive, multicenter, prospective studies.

Comparison of 3T diffusion-weighted MRI and 18F-FDG PET/CT in musculoskeletal tumours: quantitative analysis of apparent diffusion coefficients and standardized uptake values

OBJECTIVE

To determine whether the apparent diffusion coefficient (ADC) on 3T MR imaging including diffusion-weighted MR imaging (DWI) correlate with the standardized uptake value (SUV) on 18F-FDG PET/CT in musculoskeletal tumours.

METHODS

This retrospective cohort study included 57 patients (36 males, 21 females, mean age 54 years, range 12-90 years) with pathologically confirmed soft tissue (n = 32) and bone (n = 25) tumours who underwent 3T MR imaging including DWI and whole-body 18F-FDG PET/CT before treatment. 14 patients had follow-up MR imaging and 18F-FDG PET/CT after treatment. The minimum (ADC_min) and mean (ADC_mean) ADCs of musculoskeletal tumour, ADC of normal skeletal muscle (ADC_mus), SUV_max and SUV_mean of musculoskeletal tumour were obtained. Correlation between ADCs and SUVs was assessed using Pearson correlation coefficients (r). ADC_min and SUV_max were compared between pretreatment and posttreatment by t-test.

RESULTS

There was inverse correlation between SUV_max and the ratio ADC_min/ADC_mus (r = - 0.505 to - 0.495, p ≤ 0.001) and between SUV_mean and the ratio ADC_mean/ADC_mus (r = - 0.501 to - 0.493, p = 0.001). After treatment ADC was significantly increased whereas SUV was significantly decreased (p = 0.001). There was significant correlation in percent change between the initial and follow-up values of ADC_min and SUV_max (r = 0.750 to 0.773, p ≤ 0.005). The ADC_min was increased by 163% and SUV_max was decreased by 61% in 11 patients with treatment response.

CONCLUSION

ADC at 3T MR DWI and SUV at 18F-FDG PET/CT have an inverse correlation in musculoskeletal tumours.

ADVANCES IN KNOWLEDGE

Our study showed that ADC at 3T DWI and SUV at 18F-FDG PET/CT had an inverse correlation in musculoskeletal tumours.

Future Perspective of the Application of Positron Emission Tomography-Computed Tomography-MR Imaging in Musculoskeletal Disorders

Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is the imaging method of choice in sarcoma patients. PET may help in diagnosis, grading, staging, biopsy guidance, monitoring response to therapy, restaging for recurrence, and prognosis. 18F-FDG-PET/MRI combines the higher tissue contrast of MRI in the study of soft-tissue lesions and the peculiarities of PET imaging that allow the characterization of tissues. The use of 18F-FDG-PET/MRI in these patients has reduces the radiation dose, which is of great importance, particularly in children. Data support the routine use of 18F-FDG-PET either using CT or MRI in patients with sarcoma.

Occurrence and prognosis of lymph node metastases in patients selected for isolated limb perfusion with soft tissue sarcoma

Background and Objectives:Extensive surgery is often required for advanced soft tissue sarcoma (STS) of the limb. In the 1980s, a new approach was developed: isolated limb perfusion (ILP). This study aimed to assess incidence and impact on patient survival based on lymph node metastasis with systematic radical lymphadenectomy during ILP.

Methods: Retrospective study of 57 consecutive patients treated by ILP for limb STS with simultaneous radical lymph node dissection in our tertiary referral center between 1992 and 2015.

Results: Median age was 62 years (19-87) and 30 patients were male (53%). Lymph node involvement was observed in 13 patients (N1, 23%), regarded as metastatic spreading in 4 angiosarcomas, 3 epithelioid sarcomas, 2 leiomyosarcomas, 2 undifferentiated sarcomas and 2 synovial sarcomas. For the N0 patient group, median survival was 73.9 months (CI 95% 41.9-105.9) compared to 15.1 months (CI 95% 7.4-22.6) in case of metastatic lymph node (p=0.002). The median disease-free survival was 33,0 months (CI 95% 12,5-53.5) in N0 group and 8.0 months (CI 95% 4.0-11.9) in N1 (p=0.006).

Conclusions: Lymph node metastases of STS patients selected for ILP seemed to have a negative impact on both overall and disease-free survival. Radical lymph node dissection should be included in ILP procedure.

Positron emission tomography/computed tomography for osseous and soft tissue sarcomas: A systematic review of the literature and meta-analysis

In order to elucidate the value of positron emission tomography (PET)/computed tomography (CT) in the clinical diagnosis and treatment of osseous and soft tissue malignancies, two authors independently searched the PubMed, Medline, Elsevier, Embase and Cochrane Library databases for literature published between January 2003 and February 2016, using the key words 'PET/CT', 'positron emission tomography/computed tomography', 'osseous sarcoma', 'bone tumor', 'soft tissue sarcoma' and 'neoadjuvant', to identify prospective and retrospective studies on the applicability of PET/CT on the clinical diagnosis of bone and soft tissue lesions, and evaluation of their response to neoadjuvant therapies. Data were independently extracted by the two authors and any disagreements were resolved by a third author when necessary. Extracted data were analyzed by Meta-Disc 1.6 software. As a result, 16 trials with a total of 883 patients and 2,214 lesions were included in the present study. The overall diagnostic accuracy of PET/CT exhibited a sensitivity and specificity of 0.90 (0.86-0.92) and 0.89 (0.85-0.92), respectively, and the effect of neoadjuvant therapy was assessed with a sensitivity and specificity of 0.79 (0.30-0.93) and 0.79 (0.69-0.89), respectively. Thus, it may be concluded from the present study that PET/CT is a reliable imaging method to be applied in the diagnosis and treatment of osseous and soft tissue malignancies.

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 role of FDG PET/CT in patients treated with neoadjuvant chemotherapy for localized bone sarcomas

Purpose

The histological response to neoadjuvant chemotherapy is an important prognostic factor in patients with osteosarcoma (OS) and Ewing sarcoma (EWS). The aim of this study was to assess baseline primary tumour FDG uptake on PET/CT, and serum values of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH), to establish whether these factors are correlated with tumour necrosis and prognosis.

Methods

Patients treated between 2009 and 2014 for localized EWS and OS, who underwent FDG PET/CT as part of their staging work-up, were included. The relationships between primary tumour SUVmax at baseline (SUV1), SUVmax after induction chemotherapy (SUV2), metabolic response calculated as [(SUV1 − SUV2)/SUV1)] × 100, LDH and ALP and tumour response/survival were analysed. A good response (GR) was defined as tumour necrosis >90 % in patients with OS, and grade II-III Picci necrosis (persitence of microscopic foci only or no viable tumor) in patients with Ewing sarcoma.

Results

The study included 77 patients, 45 with EWS and 32 with OS. A good histological response was achieved in 53 % of EWS patients, and 41 % of OS patients. The 3-year event-free survival (EFS) was 57 % in EWS patients and 48 % OS patients. The median SUV1 was 5.6 (range 0 – 17) in EWS patients and 7.9 (range 0 – 24) in OS patients (p = 0.006). In EWS patients the GR rate was 30 % in those with a high SUV1 (≥6) and 72 % in those with a lower SUV1 (p = 0.0004), and in OS patients the GR rate was 29 % in those with SUV1 ≥6 and 64 % in those with a lower SUV1 (p = 0.05). In the univariate analysis the 3-year EFS was significantly better in patients with a low ALP level (59 %) than in those with a high ALP level (22 %, p = 0.02) and in patients with a low LDH level (62 %) than in those with a high LDH level (37 %, p = 0.004). In EWS patients the 3-year EFS was 37 % in those with a high SUV1 and 75 % in those with a low SUV1 (p = 0.004), and in OS patients the 3-year EFS was 32 % in those with a high SUV1 and 66 % in those with a low SUV1 (p = 0.1). Histology, age and gender were not associated with survival. In the multivariate analysis, SUV1 was the only independent pretreatment prognostic factor to retain statistical significance (p = 0.017). SUV2 was assessed in 25 EWS patients: the median SUV2 was 1.9 (range 1 – 8). The GR rate was 20 % in patients with a high SUV2, and 67 % in those with a low SUV2 (p = 0.02). A good metabolic response (SUV reduction of ≥55 %) was associated with a 3-year EFS of 80 % and a poor metabolic response with a 3-year EFS of 20 % (p = 0.05). In the OS patients the median SUV2 was 2.7 (range 0 – 4.5). Neither SUV2 nor the metabolic response was associated with outcome in OS patients.

Conclusion

FDG PET/CT is a useful and noninvasive tool for identifying patients who are more likely to be resistant to chemotherapy. If this finding is confirmed in a larger series, SUV1, SUV2 and metabolic response could be proposed as factors for stratifying EWS patients to identify those with high-grade localized bone EWS who would benefit from risk-adapted induction chemotherapy.

Using fluorodeoxy-D-glucose-positron emission tomography to monitor neoadjuvant chemotherapy response in sarcoma: A meta-analysis

AIM: To systematically evaluate the accuracy of 18-fluorodeoxy-D-glucose-positron emission tomography (18-FDG PET) to assess response to neoadjuvant chemotherapy in bone and soft tissue sarcomas.

METHODS: Studies published in English language regarding the accuracy of F-18 FDG PET for the indication were retrieved from MEDLINE. The QUADAS tool was utilized for methodological quality appraisal. Relevant data were extracted, and quantitative data synthesis included pooled estimation and subgroup analysis.

RESULTS: A total of fifteen studies involving 420 patients with pathologically confirmed sarcoma were collected. Methodological quality was relatively high. The pooled sensitivity and specificity of PET to predict histopathological response were 87% (95%CI: 81%-91%) and 83% (95%CI: 77%-87%), respectively. Ten studies employed a lower standardized uptake value (SUV) after chemotherapies (mostly 2.5) and/or a higher SUV reduction rate (mostly around 50%) as PET criteria of good response. Subgroup analysis showed that PET exhibited a significantly better specificity in osteosarcoma (OS) and Ewing sarcoma (ES) than in soft-tissue sarcoma (STS) (91% vs 75%, P < 0.05), and a higher specificity in pediatric patients than in adults (90% vs 74%, P < 0.01). PET yielded a lower specificity in ifosfamide-contained chemotherapies than in the alternative regimen (70% vs 97%, P < 0.01).

CONCLUSION: F-18 FDG PET is promising to predict neoadjuvant therapy response in sarcoma, especially in pediatric patients with OS or ES. Certain chemotherapeutic agents could potentially cause false positives of PET.

Sarcoma mid-therapy [F-18]fluorodeoxyglucose positron emission tomography (FDG PET) and patient outcome

BACKGROUND

Our previous research investigated the ability of [F-18]fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging results to predict outcome in patients with sarcoma. Tumor uptake of FDG before and after neoadjuvant chemotherapy was predictive of patient outcome. With this background, a prospective clinical study was designed to assess whether tumor FDG uptake levels in the middle of neoadjuvant chemotherapy added additional prognostic information to pre-therapy imaging data.

METHODS

Sixty-five patients with either bone or soft-tissue sarcoma were treated with neoadjuvant-based chemotherapy according to the standard clinical practice for each tumor group. All patients had FDG PET studies before therapy, mid-therapy (after two cycles of chemotherapy), and before resection. Tumor FDG uptake (SUVmax, the maximum standardized uptake value) at each imaging time point, tumor type (bone or soft-tissue sarcoma), tumor size, and histopathologic grade were recorded for each patient. The time from the pre-therapy FDG PET study to events of local tumor recurrence, metastasis, or death were extracted from the clinical records for comparison with the imaging data. Univariate and multivariate analyses of the imaging and clinical data were performed.

RESULTS

Univariate and multivariate data analyses showed that the difference (measured as the percentage reduction) between the pre-therapy and mid-therapy maximum tumor uptake values added prognostic value to patient outcome predictions independently of other patient variables.

CONCLUSIONS

The utility of a tumor pre-therapy FDG PET scan as a biomarker for the outcome of patients with sarcoma was strengthened by a mid-therapy scan to evaluate the interim treatment response.

The Role of Fluorine-18-fluorodeoxyglucose Positron Emission Tomography in Assessing the Response to Neoadjuvant Treatment in Patients with Osteosarcoma

Aim. The objective of this study is to systematically review the role of positron emission tomography (PET) and PET/computed tomography (PET/CT) with fluorine-18-fluorodeoxyglucose (FDG) in assessing the response to neoadjuvant treatment in patients with osteosarcoma (OS). Methods. A comprehensive literature search of published studies through March 2012 in PubMed/MEDLINE, Embase, and Scopus databases regarding whole-body FDG-PET and FDG-PET/CT in patients with OS was performed. Results. Twenty-two studies have investigated the role of FDG-PET and FDG-PET/CT in the evaluation of response to neoadjuvant treatment with either chemotherapy or radiation therapy in patients with OS. The main findings of these studies are presented. Conclusion. FDG-PET or PET/CT seems to be sensitive and reliable diagnostic tools in the assessment of metabolic response to treatment in patients with OS, after baseline PET evaluation has been performed in advance. However, false positive findings due to inflammation in sites of tumoral response should be considered.

Prognostic value of Tc-99m-MIBI performed during middle course of preoperative chemotherapy in patients with malignant bone and soft-tissue tumors

PURPOSE

This study was aimed to determine whether Tc-99m-hexakis-2-methoxyisobutylisonitrile (MIBI) scintigraphy performed in the middle of preoperative chemotherapy has a prognostic value in patients with malignant bone and soft tissue tumors (MBST).

MATERIALS AND METHODS

In 90 patients with MBST, Tc-99m-MIBI scintigraphy was performed 15 minutes after tracer injection before the first and after the third chemotherapy cycles. After 5 cycles of chemotherapy and tumor resection, therapeutic effect was assessed by histopathology. The percent reduction of uptake ratio (ΔUR) was calculated according to the following equation: 100 × ([prechemotherapy UR - post-middle course of chemotherapy UR]/prechemotherapy UR).

RESULTS

The average follow-up for the entire population was 52 months. Twenty-one patients had clinically detectable metastases at initial presentation (primary metastasis). Kaplan-Meier analysis demonstrated that absence of metastasis was associated with good survival in all patients, in patients with bone tumor, and those with soft tissue tumor (P < 0.0001, P < 0.0001, and P = 0.0003, respectively), and ΔUR ≧30% was also associated with survival in all patients and patients with bone tumor (P = 0.011 and P = 0.047, respectively), but was marginal in those with soft tissue tumor (P = 0.091). Multivariate analysis showed that primary metastasis was the most powerful independent predictor of a lethal clinical outcome in all patients, in both patients with bone and soft tissue tumors (hazard ratio [HR]: 4.9, 95% confidence interval [CI]: 2.61-9.08, P < 0.0001; HR: 15.1, CI: 4.86-52.7, P < 0.0001; HR: 3.7, CI: 1.45-8.94, P = 0.0069, respectively) and showed that Tc-99m-MIBI scintigraphy had a good independent long-term prognostic value in all patients and patients with bone tumor (HR: 2.2, CI: 1.14-4.43, P = 0.017; HR: 6.0, CI: 2.01-21.6, P = 0.0009, respectively) but not in those with soft tissue tumor (HR: 1.5, CI: 0.61-4.09, P = 0.38). Good disease-free survival was associated with ΔUR ≧30% in all patients and patients with soft tissue tumor (P = 0.0093 and P = 0.017, respectively) but not in those with bone tumor (P = 0.19).

CONCLUSIONS

Tc-99m-MIBI scintigraphy at the middle course of preoperative chemotherapy could be used as a prognostic indicator in patients with MBST.

PET/CT allows stratification of responders to neoadjuvant chemotherapy for high-grade sarcoma: a prospective study

PURPOSE

The aim of the present study was to determine whether metabolic reduction is capable of reflecting the histopathologic response and outcome after neoadjuvant chemotherapy in patients with high-grade sarcoma.

PATIENTS AND METHODS

Forty-two patients with histologically proven high-grade sarcoma underwent neoadjuvant chemotherapy followed by surgical resection. Quantitative F-18 fluorodeoxyglucose (F-18-FDG) positron emission tomography (PET)/computed tomography scans were acquired before and after the first cycle and after completion of neoadjuvant chemotherapy. Standardized uptake values (SUVs) and metabolic reduction rates were compared with histopathologic response, progression-free survival, and overall survival.

RESULTS

Baseline SUVmax was 10.9 ± 3.6 (range, 3.8-19.6). Therapeutic effect resulted in 10 patients (24%) with a satisfactory response and in 32 patients (76%) with an unsatisfactory response after completion of neoadjuvant chemotherapy. The SUV decreased to 7.8 ± 3.4 after the first cycle (t1) of chemotherapy and to 5.2 ± 3.4 after completion (t2) of chemotherapy. Histopathologic response and percentage SUV (t2) reduction rate were independent predictors of progression-free survival and overall survival in the multivariate analyses.

CONCLUSION

Metabolic reduction after neoadjuvant chemotherapy evaluated by F-18 FDG PET or computed tomography can be used for stratification of the histopathologic response in patients with high-grade sarcoma.

18F-FDG PET response to neoadjuvant chemotherapy for Ewing sarcoma and osteosarcoma are different

OBJECTIVE

Ewing sarcoma (ES) and osteosarcoma (OS) have different biological characteristics and respond differently to chemotherapy. We reviewed (18)F-FDG PET imaging characteristics of ES and OS patients at baseline and following treatment to determine whether this biological variation is reflected in their imaging phenotype.

MATERIALS AND METHODS

A retrospective review of ES and OS patients treated with neoadjuvant chemotherapy and surgery was done, correlating PET results with histologic response to chemotherapy.

RESULTS

Change in the maximum standardized uptake value (SUVmax) between baseline and post-treatment scanning was not significantly associated with histologic response for either ES or OS. Metabolic tumor volume (MTV) and the percentage of injected (18)F-FDG dose (%ID) in the primary tumor were found to be different for ES and OS response subgroups. A 50% reduction in MTV (MTV2:1 < 0.5) was found to be significantly associated with favorable histologic response in OS. Using the same criteria for ES incorrectly predicted good responders. Increasing the cut-off values for ES to a 90% reduction in MTV (MTV2:1 < 0.1) resulted in association with favorable histologic response.

CONCLUSION

Response to neoadjuvant chemotherapy as reflected by changes in PET characteristics should be interpreted differently for ES and OS.

Tandem dosing of samarium-153 ethylenediamine tetramethylene phosphoric acid with stem cell support for patients with high-risk osteosarcoma

BACKGROUND

Samarium-153 ethylenediamine tetramethylene phosphoric acid (153Sm-EDTMP) is a radiopharmaceutical that has been used to treat osteosarcoma. The authors conducted a phase 2 study to test safety and response of high-risk osteosarcoma to tandem doses of 153Sm-EDTMP and to determine correlation between radiation delivered by low and high administered activities.

METHODS

Patients with recurrent, refractory osteosarcoma detectable on standard 99mTc bone scan received a low dose of 153Sm-EDTMP (37.0-51.8 MBq/kg), followed upon count recovery by a second, higher dose (222 MBq/kg). Fourteen days later, patients were rescued with autologous hematopoietic stem cells. The authors assessed response to therapy, performed dosimetry to determine the relationship between administered activity and tumor absorbed dose, and investigated whether changes in 2-(fluorine-18) fluoro-2-deoxy-d-glucose (18F-FDG) tumor uptake upon hematologic recovery reflected disease response.

RESULTS

Nine patients were given tandem doses of 153Sm-EDTMP; 2 received only the initial dose because of disease progression. Six patients experienced radiographic disease stabilization, but this was not considered a response, so the study was terminated early. There was a linear relationship between administered activity and tumor absorbed dose, but there was no correlation between change in 18F-FDG positron emission tomography tumor uptake and tumor absorbed dose or time to progression. The median time to progression for the entire group was 79 days.

CONCLUSIONS

Tandem doses of 153Sm-EDTMP were safe for this cohort of heavily pretreated patients with very high-risk disease. The strong correlation between absorbed dose and administered activity within each evaluable patient provides a methodology to individually tailor tandem doses of this agent.

Added value of baseline 18F-FDG uptake in serial 18F-FDG PET for evaluation of response of solid extracerebral tumors to systemic cytotoxic neoadjuvant treatment: a meta-analysis

The purpose of this study was to test the hypothesis that the level of baseline (18)F-FDG uptake in the primary tumor adds value to its relative change in (18)F-FDG uptake in serial PET scans in predicting the histopathologic response to systemic cytotoxic neoadjuvant treatment of patients with solid extracerebral tumors.

METHODS

We performed a literature search from January 1995 through November 2008 using PubMed and Embase. Two reviewers independently selected eligible studies for possible inclusion in the meta-analysis by reviewing titles and abstracts. Inclusion criteria were at least 10 patients, (18)F-FDG PET before and after therapy, (18)F-FDG PET performed with the intention of monitoring the response of solid extracerebral tumors in humans to cytotoxic neoadjuvant systemic therapy, attenuation-corrected (18)F-FDG PET studies, and studies presenting individual patient data (PET results and histopathologic reference test after treatment). Multilevel logistic regression was used to assess the effect of relative change of (18)F-FDG uptake ([baseline - end]/baseline) and baseline (18)F-FDG uptake value with type of tumor and type of treatment as level 1 covariates.

RESULTS

Nineteen studies (all observational; a total of 438 patients [median, 23 patients per study; range, 10-40]) were included, aiming at the accuracy of PET versus histopathology. To quantify PET, maximum standardized uptake value (SUV) was used in 6 studies, mean SUV in 7, SUV (subtype unclear) in 1, tumor-to-background ratio in 3, and dose uptake ratio in 1. The average overall histopathologic response rate was 0.47 (median, 0.50), ranging from 0.17 to 0.88. The relative change in (18)F-FDG uptake was the strongest indicator (P < 0.0001) for tumor response. Baseline (18)F-FDG was not significantly associated as a main factor; however, a significant interaction of baseline uptake and relative change after therapy was observed (P < 0.001).

CONCLUSION

Relative change in (18)F-FDG uptake was the strongest indicator for tumor response, but the level of baseline (18)F-FDG uptake in the primary tumor provided additional information about prediction of response to therapy. These data corroborate and extend the need for standardization, quality assurance, and control of PET studies quantifying (18)F-FDG in oncologic treatment monitoring.

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.

Early prediction of histopathological tumor response to preoperative chemotherapy by Tc-99m MIBI imaging in bone and soft tissue sarcomas

PURPOSE

Tc-99m-methoxyisobutylisonitrile (MIBI) accumulates in only viable cells. In patients with bone and soft tissue sarcomas, preoperative chemotherapy is essential and the early prediction of the tumor response to chemotherapy would be beneficial for the planning of treatment strategy. The purpose of this study was to assess whether the change of Tc-99m-MIBI images from the prechemotherapy state to the early to midportion of chemotherapy can predict the final histopathological tumor response as accurately as the change of imaging after completion of chemotherapy.

METHODS

Seventy-three patients with bone and soft tissue sarcomas underwent Tc-99m-MIBI scintigraphy before chemotherapy and at least 2 times after the second or third or fifth course of chemotherapy. The changes of the tracer uptake (DeltaUR) and perfusion (DeltaPI) from prechemotherapy to postchemotherapy were compared with histologic response.

RESULTS

The sensitivity, specificity, and accuracy for the prediction of effective chemotherapy in DeltaPI were 88%, 83%, 85% after second, 85%, 72%, 78% after third, and 81%, 71%, 76% after 5th chemotherapy, and those in DeltaUR were 88%, 83%, 85% after 2nd, 85%, 92%, 89% after 3rd, and 94%, 77%, 85% after fifth chemotherapy, respectively. The area under the receiver operator characteristic curve of the DeltaPI after second, third, and fifth chemotherapy were similarly good (0.842, 0.858, 0.811, respectively) and those of DeltaUR were similarly excellent (0.915, 0.936, 0.931, respectively).

CONCLUSION

In patients with bone and soft tissue sarcomas, the change of Tc-99m-MIBI images from prechemotherapy to early to middle of chemotherapy can predict the final histopathological tumor response to chemotherapy as accurately as the change of Tc-99m-MIBI images from prechemotherapy to the completion of the preoperative chemotherapy.

Promises and challenges of positron emission tomography for assessment of sarcoma in daily clinical practice

A correct histological diagnosis, careful staging and detection of tumour response to treatment are all crucial in the management of sarcomas. Imaging is important in all of these stages. Sarcomas have distinct biological and treatment-related features posing challenges for imaging. For example, size measurements may not adequately reflect response rates. Techniques which can measure tissue function rather than generate merely anatomical data such as positron emission tomography (PET) are rapidly gaining interest. We discuss the importance of imaging in different stages of patient management, emphasising the unique characteristics of sarcoma. Furthermore, we discuss the potential of PET for the various indications, focussing on therapy evaluation.