Imaging update on soft tissue sarcoma

Soft tissue sarcomas (STS) are rare tumours presenting as soft tissue lumps. Ultrasound is often the primary modality for the initial assessment, with MRI the mainstay for lesion characterisation. PET/CT along with other emerging MRI sequences are used in certain situations as an adjunct and problem solving tool in STS staging and assessment of disease recurrence. Recent advances include the promise of whole body MRI, hybrid PET/MRI, diffusion weighted imaging, dynamic contrast enhanced MRI and advances in artificial intelligence. This article discusses current concepts in extremity STS imaging and highlights recent advances.     

Prognostic utility of pre-transplantation [18F] fluorodeoxyglucose positron emission tomography/computed tomography in patients with diffuse large B-cell lymphoma who underwent rituximab,dexamethasone, high-dose cytarabine,carboplatin salvage chemotherapy

We analysed the outcomes of 62 patients with refractory/relapsed diffuse large B-cell lymphoma (rrDLBCL) who had pre-transplantation fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) after R-DHAC (rituximab, dexamethasone, high-dose cytarabine, carboplatin) salvage chemotherapy, and were evaluated using Deauville criteria and total lesion glycolysis (TLG). A positive pre-transplantation PET/CT with Deauville score of 5 was associated with shorter progression-free survival (PFS) (P = 0·01), while a Deauville score of 4 was not predictive of outcome. Only pre-transplant TLG was significantly associated with both PFS (P = 0·005) and overall survival (P = 0·03). TLG deserves to be further investigated in prospective studies.     

Vascular Positron Emission Tomography and Restenosis in Symptomatic Peripheral Arterial Disease: A Prospective Clinical Study

ObjectivesThis study determined whether in vivo positron emission tomography (PET) of arterial inflammation (¹⁸F-fluorodeoxyglucose [¹⁸F-FDG]) or microcalcification (¹⁸F-sodium fluoride [¹⁸F-NaF]) could predict restenosis following PTA.BackgroundRestenosis following lower limb percutaneous transluminal angioplasty (PTA) is common, unpredictable, and challenging to treat. Currently, it is impossible to predict which patient will suffer from restenosis following angioplasty.MethodsIn this prospective observational cohort study, 50 patients with symptomatic peripheral arterial disease underwent ¹⁸F-FDG and ¹⁸F-NaF PET/computed tomography (CT) imaging of the superficial femoral artery before and 6 weeks after angioplasty. The primary outcome was arterial restenosis at 12 months.ResultsForty subjects completed the study protocol with 14 patients (35%) reaching the primary outcome of restenosis. The baseline activities of femoral arterial inflammation (¹⁸F-FDG tissue-to-background ratio [TBR] 2.43 [interquartile range (IQR): 2.29 to 2.61] vs. 1.63 [IQR: 1.52 to 1.78]; p < 0.001) and microcalcification (¹⁸F-NaF TBR 2.61 [IQR: 2.50 to 2.77] vs. 1.69 [IQR: 1.54 to 1.77]; p < 0.001) were higher in patients who developed restenosis. The predictive value of both ¹⁸F-FDG (cut-off TBR_max value of 1.98) and ¹⁸F-NaF (cut-off TBR_max value of 2.11) uptake demonstrated excellent discrimination in predicting 1-year restenosis (Kaplan Meier estimator, log-rank p < 0.001).ConclusionsBaseline and persistent femoral arterial inflammation and micro-calcification are associated with restenosis following lower limb PTA. For the first time, we describe a method of identifying complex metabolically active plaques and patients at risk of restenosis that has the potential to select patients for intervention and to serve as a biomarker to test novel interventions to prevent restenosis.     

Contribution of 18F-fluorodeoxyglucose positron emission tomography to the diagnosis of early pancreatic carcinoma

Background/Purpose

Pancreatic carcinoma has a poor prognosis, and early detection is essential to allow potentially curative resection. Despite the wide array of diagnostic tools available, the detection of small pancreatic tumors remains difficult. The aim of this study was to investigate the contribution of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) to the diagnosis of early pancreatic cancer.

Methods

FDG-PET was performed in 56 patients with pancreatic cancer who underwent curative surgery. The standardized uptake value (SUV) for FDG was calculated in each patient and the relationships between the SUV and various clinicopathological factors were analyzed.

Results

The tumors ranged from 0.8 to 6.5 cm in diameter. When the cutoff value for the SUV was set at 2.5, 51 of the 56 patients (91%) had a positive FDG-PET study. The SUV did not show a significant difference in relation to tumor differentiation or pTS and pT factors. There was also no correlation between the SUV and the maximum tumor diameter (r = 0.22; P = 0.1). Five tumors had an SUV below the cutoff value, and all of these lesions had intermediate or scirrhous stroma rather than medullary stroma.

Conclusions

These results indicate that FDG-PET is useful for the detection of small early pancreatic cancers.     

18F-FDG PET/CT显像在进展期前列腺癌诊断和分期中的应用

目的探讨^18F-FDG PET/CT显像在进展期前列腺癌诊断和分期中的临床价值.方法20例临床进展期前列腺癌患者行^18F-FDG PET/CT全身显像,同时行B超和骨扫描检查.结果①9例未经治疗者中^18F-FDG PET/CT确诊8例;全雄激素阻断治疗（MAB）后前列腺特异性抗原（PSA）值较稳定者及逐渐升高者共5例,PET/CT均准确显示;6例MAB反应良好者,^18F-FDG PET/CT示其病灶均无放射性浓聚（即阴性）.②6例盆腔淋巴结转移和6例骨转移者中^18F-FDG PET/CT分别发现5例和4例,假阴性者均为MAB后反应良好患者.结论^18F-FDG PET/CT显像是评估进展期前列腺癌激素治疗效果的无创性检查方法,有利于未治疗、激素治疗有部分反应及激素难治性进展期前列腺癌的诊断和临床分期.     

18F‐FDG PET/CT and MRI in the follow‐up of head and neck squamous cell carcinoma

We evaluated the diagnostic performance of ¹⁸F‐FDG PET/CT and MRI for the assessment of head and neck squamous cell carcinoma (HNSCC) relapse. Since early treatment might prevent inoperable relapse, we also evaluated THE performance of early unenhanced ¹⁸F‐FDG PET/CT in residual tumor detection. The study was prospectively performed on 32 patients who underwent ¹⁸F‐FDG PET/CT and MRI before treatment and at 4 and 12 months after treatment. ¹⁸F‐FDG PET/CT was also performed 2 weeks after the end of radiotherapy. Histopathology or a minimum of 18 months follow‐up were used as gold standard. Before treatment ¹⁸F‐FDG PET/CT and MRI detected all primary tumors except for two limited vocal fold lesions (sensitivity 94%). MRI was more sensitive than ¹⁸F‐FDG PET/CT for the detection of local extension sites (sensitivity 75 vs 58%), but at the cost of a higher rate of false positive results (positive predictive value 74 vs 86%). For relapse detection at 4 months, sensitivity was significantly higher for ¹⁸F‐FDG PET/CT (92%) than for MRI (70%), but the diagnostic performances were not significantly different at 12 months. For the detection of residual malignant tissue 2 weeks post‐radiotherapy, sensitivity and specificity of ¹⁸F‐FDG PET/CT were respectively 86 and 85% (SUV cut‐off value 5.8). ¹⁸F‐FDG PET/CT is effective in the differentiation between residual tumor and radiation‐induced changes, as early as 2 weeks after treatment of a primary HNSCC. For follow‐up, performance of ¹⁸F‐FDG PET/CT and MRI are similar except for a higher sensitivity of ¹⁸F‐FDG PET/CT at 4 months. Copyright © 2011 John Wiley & Sons, Ltd.