Differentiation of Benign Fluid Collections from Soft-Tissue Sarcomas on FDG-PET/CT

Telangiectatic soft tissue sarcoma and chronic expanding haematoma: a comparative review of MRI features

Soft tissue sarcomas containing a dominant component of haemorrhage are known to be aggressive tumours associated with a poor prognosis. Importantly, the clinical behaviour and imaging characteristics of extensively haemorrhagic soft tissue sarcomas (also termed telangiectatic soft tissue sarcomas) can resemble those of benign haematomas, particularly those that continue to expand over a prolonged period, so-called chronic expanding haematomas (CEH). The following review evaluates the current literature to identify the clinical, imaging and pathological characteristics of telangiectatic soft tissue sarcomas and to determine features that may help distinguish them from CEH. Ultimately, we suggest that lesions with sizeable regions of internal haemorrhage should be regarded with a high degree of suspicion for underlying malignancy and require referral to a tertiary sarcoma centre, where a carefully planned approach to biopsy and follow-up is needed to avoid errors in diagnosis.

PET-CT for the diagnosis and treatment of primary musculoskeletal tumors in Chinese patients - experience from 255 patients in a single center

OBJECTIVE

The current study was carried out to assess the value of positron emission tomography (PET)/CT on the diagnosis and staging of primary musculoskeletal tumors.

METHODS

PET-CT test results and histopathological study reports of all the patients with primary musculoskeletal tumors in our department from January 2006 to July 2015 were retrospectively reviewed. Maximum standardized uptake value (SUVmax) in these PET-CT reports were recorded and analyzed respectively for each type of sarcoma.

RESULTS

A total of 255 patients were included in the final analysis. Sensitivity of SUVmax based diagnosis was 96.6% for primary malignant osseous sarcomas and 91.2% for soft tissue sarcomas. SUVmax of high-grade osseous sarcomas (average 8.4 ± 5.5) was significantly higher (p < 0.001) than low-grade osseous sarcomas (average 3.9 ± 1.8); based on current case series, SUVmax of high-grade soft tissue sarcomas (7.5 ± 5.1) was not significantly different (p = 0.229) from that of low-grade soft tissue sarcomas (5.3 ± 3.7). Significant decrease of SUVmax value after chemotherapy was associated with favorable prognosis in patients with osteosarcoma.

CONCLUSION

Results of the current study indicate that, the SUVmax based application of PET-CT can be a valuable supplementary method to histopathological tests regarding the diagnosis and staging of primary musculoskeletal sarcomas.

ADVANCES IN KNOWLEDGE

SUVmax based application of PET-CT is a highly sensitive method in diagnosis of primary osseous and soft tissue sarcomas in Chinese patients.

Abnormal [18F]FDG PET/MRI findings in paraspinal structures of patients with suspected cerebrospinal fluid leak

A combination of magnetic resonance imaging (MRI), computed tomography (CT), and radionuclide cisternography are typically used to locate a cerebrospinal fluid (CSF) leak. However, the site of leakage cannot be determined, making treatment more difficult. Therefore, more sensitive imaging tools are needed. A whole-body [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/MRI was conducted on six patients with suspected CSF leak and the resulting images were reviewed in comparison with those from six healthy controls. Paraspinal regions of focally increased uptake of [18F]FDG were quantified using maximum standardized uptake values (SUVmax) and compared to the SUVmax of corresponding regions in the healthy controls. All six patients with suspected CSF leak showed paraspinal regions of significantly greater [18F]FDG uptake compared to the corresponding areas in controls (P < 0.05). Two patients treated with local injections (epidural blood patches and/or epidural fibrin patches) on the site of abnormal PET/MRI findings reported temporary but significant improvement in symptoms. Our results suggest [18F]FDG PET/MRI is sensitive to abnormalities potentially due to suspected CSF leak, which are not necessarily visible on conventional MRI alone or by the standard-of-care imaging methods.

Meta-Analysis of the Diagnostic Accuracy of Primary Bone and Soft Tissue Sarcomas by 18F-FDG-PET

OBJECTIVES

The goal of this meta-analysis was to assess the use of FDG-PET in the diagnosis of primary bone and soft tissue sarcomas.

SUBJECTS AND METHODS

Several databases, including PubMed, Embase, Cochrane Library, and Web of Science, were searched. In addition to sensitivity and specificity, the diagnostic accuracy region for detecting and grading sarcomas were pooled using bivariate and hierarchical summary receiver-operating characteristic (HSROC) models. Subgroup analysis included pooling soft tissue and bone sarcomas separately, and sensitivity analysis included high-quality studies. The quality of eligible studies was assessed using QUADAS-2.

RESULTS

Of the 1,258 papers screened, 21 studies satisfied the inclusion criteria. The pooled sensitivity and specificity of FDG-PET combined with CT for the detection of sarcomas were 89.2 and 76.3%, respectively. These diagnostic accuracy measures were higher when combined with CT than those of PDG-PET alone. Diagnostic accuracy for bone and soft tissue lesions were comparable but slightly better for soft tissue tumors. Pooling only the high-quality studies with low risk of bias yielded a sensitivity of 88.5% and specificity reduced to 65.6%. There was no evidence for publication bias, but significant heterogeneity among the studies was apparent. This study also showed that FDG-PET can efficiently differentiate between benign and malignant tumors, with a mean standard uptake value of maximally 2.52 units in benign and 6.81 units in malignant tumors (89.2% sensitivity and 75.1% specificity).

CONCLUSION

Our findings indicate FDG-PET can efficiently differentiate between benign and malignant bone and soft tissue tumors. We also found that FDG-PET improves accuracy in diagnosing soft tissue sarcomas when combined with CT.

The Role of Positron Emission Tomography/Magnetic Resonance Imaging in Gynecological Malignancies

Accurate oncological staging for early detection is of utmost importance in patient care and increasing the overall patient survival outcome. Hybrid imaging in the form of positron emission tomography (PET)/computed tomography has been successfully implemented in oncological imaging and, where available, has been used consistently in patients with gynecologic malignancies. The implementation of PET/magnetic resonance imaging (MRI) enables high-quality assessment of gynecological malignancies by combining the diagnostic advantages of metabolic information of PET along with the high-resolution anatomical and functional information from the MRI to provide precise information about staging, recurrence, and metastases. This article will review the various applications of PET/MRI in gynecological cancer.

Periprosthetic seroma with false-positive FDG PET-CT reactive nodes mistaken for metastases in a patient previously treated of metastasic melanoma. Potential source of diagnostic errors

INTRODUCTION

FDG PET/CT is believed to be crucial in oncology, but its limited specificity represents a challenge. Prosthetic meshes used for repair abdominal defects may lead to false-positives FDG PET/CT uptake, over staging malignancies and inducing inappropriate treatments. A false-positive FDG PET/CT uptake mimicking metastatic disease during the follow-up of a previously treated metastatic melanoma patient is presented.

Assessing the role of ¹⁸F-FDG PET and ¹⁸F-FDG PET/CT in the diagnosis of soft tissue musculoskeletal malignancies: a systematic review and meta-analysis

PURPOSE

Twelve years ago a meta-analysis evaluated the diagnostic performance of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in assessing musculoskeletal soft tissue lesions (MsSTL). Currently, PET/CT has substituted PET imaging; however, there has not been any published meta-analysis on the use of PET/CT or a comparison of PET/CT with PET in the diagnosis of MsSTL. Therefore, we conducted a meta-analysis to identify the current diagnostic performance of (18)F-FDG PET/CT and determine if there is added value when compared to PET.

METHODS

A systematic review of English articles was conducted, and MEDLINE PubMed, the Cochrane Library, and Embase were searched from 1996 to March 2015. Studies exploring the diagnostic accuracy of (18)F-FDG PET/CT (or dedicated PET) compared to histopathology in patients with MsSTL undergoing investigation for malignancy were included.

RESULTS

Our meta-analysis included 14 articles composed of 755 patients with 757 soft tissue lesions. There were 451 (60 %) malignant tumors and 306 benign lesions. The (18)F-FDG PET/CT (and dedicated PET) mean sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for diagnosing MsSTL were 0.96 (0.90, 1.00), 0.77 (0.67, 0.86), 0.88 (0.85, 0.91), 0.86 (0.78, 0.94), and 0.91 (0.83, 0.99), respectively. The posterior mean (95 % highest posterior density interval) for the AUC was 0.92 (0.88, 0.96). PET/CT had higher specificity, accuracy, and positive predictive value when compared to a dedicated PET (0.85, 0.89, and 0.91 vs 0.71, 0.85, and 0.82, respectively).

CONCLUSION

(18)F-FDG PET/CT and dedicated PET are both highly accurate in the diagnosis of MsSTL. PET/CT is more accurate and specific and has a higher positive predictive value than PET.