Use of FDG-PET/CT for systemic assessment of suspected primary central nervous system lymphoma: a LOC study.

INTRODUCTION: Primary Central Nervous System Lymphoma (PCNSL) is a rare disease with different therapeutic implications than systemic lymphoma. In this study, we evaluated whole-body 18FDG-PET/CT for pre-chemotherapy imaging of suspected PCNSL. METHODS: One hundred and thirty consecutive immunocompetent patients were retrospectively included. The results of initial 18FDG-PET/CT, contrast-enhanced CT (CeCT) and bone marrow biopsy (BMB) when available were compared to a gold standard based on pathological diagnosis or follow-up. RESULTS: CNS lesion pathology showed large B-cell lymphoma in 95% of patients, including 11 patients with primary vitro-retinal lymphoma. Ten patients (8%) where ultimately diagnosed with systemic lymphoma involvement, including five pathologically confirmed cases, all of which were detected by 18FDG-PET/CT. 18FDG-PET/CT showed incidental systemic findings unrelated to lymphoma in 14% of patients. An SUVmax threshold of nine enabled good discrimination between systemic lymphoma and other lesions (sensitivity 92% and specificity 89%). CeCT and BMB performed in 108 and 77 patients respectively revealed systemic lesions in only three patients. CONCLUSION: 18FDG-PET/CT detected concomitant occult systemic involvement in a non-negligible proportion of suspected PCNSL cases (8%). In this setting its sensitivity is higher than that of CeCT. All of our patients ultimately diagnosed with concomitant systemic involvement had positive 18FDG-PET/CT. We believe it constitutes a safe one-stop shop evaluation for the systemic pre-treatment imaging of suspected PCNSL.

Assessment of response to endocrine therapy using FDG PET/CT in metastatic breast cancer: a pilot study.

PURPOSE: The purpose of this pilot study was to assess whether outcome in metastatic or recurrent breast cancer patients is related to metabolic response to endocrine therapy determined by (18)F-FDG PET/CT. METHODS: The study group comprised 22 patients with breast cancer (age 58 ± 11 years, mean ± SD) who were scheduled to receive endocrine therapy. They were systematically assessed by PET/CT at baseline and after a mean of 10 ± 4 weeks for evaluation of response after induction. All patients demonstrated FDG-avid lesions on the baseline PET/CT scan. The metabolic response was assessed according to EORTC criteria and based on the mean difference in SUV(max) between the two PET/CT scans, and the patients were classified into four groups: complete or partial metabolic response, or stable or progressive metabolic disease (CMR, PMR, SMD and PMD, respectively). All patients were followed in our institution. RESULTS: Metastatic sites were localized in bone (n = 15), lymph nodes (n = 11), chest wall (n = 3), breast (n = 5), lung (n = 3), soft tissue (n = 1) and liver (n = 1). PMR was observed in 11 patients (50%), SMD in 5 (23%) and PMD in 6 (27%). The median progression-free survival (PFS) times were 20, 27 and 6 months in the PMR, SMD and PMD groups, respectively. PFS in the SMD group differed from that in the PMR and SMD groups (p < 0.0001). CONCLUSION: Metabolic response assessed by FDG PET/CT imaging in patients with metastatic breast cancer treated with endocrine therapy is predictive of the patients' PFS.

Imaging of malignant tumours of the long bones in children: monitoring response to neoadjuvant chemotherapy and preoperative assessment.

This review focuses on imaging of osteosarcoma and Ewing's sarcoma of the long bones in children during preoperative neoadjuvant chemotherapy. Morphological criteria on plain films and conventional static MRI are insufficiently correlated with histological response. We review the contribution of dynamic MRI, diffusion-weighted MR and nuclear medicine (18FDG-PET) to monitor tumoural necrosis. MRI is currently the best method to evaluate local extension prior to tumour resection, especially to assess the feasibility of conservative surgery. Quantitative models in dynamic MRI and 18FDG-PET are currently being developed in order to find new early prognostic criteria, but for the time being, treatment protocols are still based on the gold standard of histological response.