Diagnostic accuracy of integrated¹⁸F-FDG PET/CT for restaging patients with malignant germ cell tumours

Abstract

Objective: Evaluation of utility of fluorine-18 fludeoxyglucose ( 18 F-FDG) positron emission tomography/CT (PET/CT) for restaging patients with primary malignant germ cell tumours (GCTs). Methods: Data of 92 patients (age, 31.94 6 10.1 years; male/ female, 86/6) with histopathologically confirmed malignant GCTs (gonadal, 88; mediastinal, 4; seminomatous, 47 and non-seminomatous, 45) who underwent 18 F-FDG PET/CT for restaging (suspected recurrence/post-therapy evaluation) were retrospectively analysed. Two experienced nuclear medicine physicians reviewed the PET/CT images in consensus, qualitatively and semi-quantitatively [maximum standardized uptake value (SUVmax)]. Histopathology (if available) and clinical/imaging/biochemical follow-up (minimum of 6 months) were employed as the reference standard. Results:18 F-FDG PET/CT was interpreted as positive in 59 and negative in 33 patients. Local disease was seen in 5, nodal disease in 50 and distant metastasis in 22 patients. PET/CT was true positive in 49, false positive in 10, true negative in 30 and false negative in 3 patients. 18F-FDG PET/CT showed sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 94.2%, 75.0%, 83.0%, 90.9% and 85.8% overall; 90.0%, 74.0%, 72.0%, 90.9% and 80.8% in seminomatous GCT; and 96.8%, 76.9%, 91.1%, 90.9% and 91.1% in non-seminomatous GCT, respectively. Difference in PET/CT accuracy for seminomatous and non-seminomatous GCTs was not significant (p 5 0.263). PET/CT demonstrated disease in 13 patients with negative/equivocal conventional imaging findings and in 9 patients with normal tumour markers. No site-or histology-based difference was seen in SUVmax. Conclusion:18 F-FDG PET/CT demonstrates high diagnostic accuracy for restaging patients with malignant GCTs. It has comparable diagnostic performance in both seminomatous and non-seminomatous malignant GCTs. Advances in knowledge:The present article demonstrates high diagnostic accuracy of 18 F-FDG PET/CT for restaging both seminomatous and non-seminomatous malignant GCTs in a large patient population.Germ cell tumour (GCT) is the commonest malignancy in males aged between 20 and 35 years.1 With cisplatin-based chemotherapy, high long-term cure rates can be achieved in patients with GCTs.2 Traditionally, the follow-up of patients with GCT is carried out with clinical examination, measurement of serum tumour markers [alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (b-HCG) and lactate dehydrogenase (LDH)], and with conventional imaging investigations such as CT or MRI.3 A major issue in the management of GCTs is post-chemotherapy residual masses, which harbour viable tumour cells in about 11-37% of cases. 4 Unfortunately, CT or MRI cannot predict the histology of residual masses and has limited specificity in post-therapy setting.5

Mediastinal Masses in Children: Radiologic-Pathologic Correlation

“…MR images may show enhancing septa in cystic components. FDG avidity at PET is typical in the solid components of mediastinal GCTs, and FDG PET has a role in the evaluation of therapeutic response (51).…”

Positron‐emission tomography imaging in urological oncology: Current aspects and developments

“…Another study by Sharma et al . showed the high diagnostic accuracy of 18 F‐FDG PET/CT for restaging of both seminoma and non‐seminoma in 96 patients . 18 F‐FDG PET/CT showed sensitivity, specificity, PPV, NPV and accuracy of 94.2%, 75.0%, 83.0%, 90.9% and 85.8% overall; 90.0%, 74.0%, 72.0%, 90.9% and 80.8% in seminoma; and 96.8%, 76.9%, 91.1%, 90.9% and 91.1% for non‐seminoma, respectively.…”

18F-FDG PET/CT Finding of Drop Metastases from Germ Cell Tumor of Pineal Gland

“…18 F-FDG PET/CT may, in a single session, help in demonstrating not only the primary lesion but also the extent of disease. Most GCTs are hypermetabolic and show increased 18 F-FDG uptake, excepting mature teratomas, which show very little or no uptake (4). In one reported case-a 14-y-old boy with a pineal GCT of mixed histopathology-no 18 F-FDG uptake was observed in the tumor (5).…”