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18F-FDG uptake in irradiated non-tumour-affected oesophagus (NTO) on restaging PET is a potential surrogate for the measurement of radiation-induced inflammation. Radiation-induced inflammation itself has been shown to be of high prognostic relevance in patients undergoing preoperative radiochemotherapy (RCT) for locally advanced oesophageal cancer. We assessed the prognostic relevance of FDG uptake in the NTO in an independent cohort of patients treated with definitive RCT. This retrospective evaluation included 72 patients with oesophageal squamous cell carcinoma treated with definitive RCT with curative intent. All patients underwent pretreatment and restaging FDG PET after receiving a radiation dose of 40–50 Gy. Standardized uptake values (SUVmax/SUVmean), metabolic tumour volume (MTV) and relative changes from pretreatment to restaging PET (∆SUVmax/∆SUVmean) were determined within the tumour and NTO. Univariate Cox regression with respect to overall survival (OS), local control (LC), distant metastases (DM) and treatment failure (TF) was performed. Independence of parameters was tested by multivariate Cox regression. ∆SUVmax NTO and MTV were prognostic factors for all investigated clinical endpoints (OS, LC, DM, TF). Inclusion of clinical and PET tumour parameters in multivariate analysis showed that ∆SUVmax NTO was an independent prognostic factor. Furthermore, multivariate analysis of ∆SUVmax NTO using previously published cut-off values from preoperatively treated patients revealed that ∆SUVmax NTO was independent prognostic factor for OS (HR = 1.88, p = 0.038), TF (HR = 2.11, p = 0.048) and DM (HR = 3.02, p = 0.047). NTO-related tracer uptake during the course of treatment in patients with oesophageal carcinoma was shown to be of high prognostic relevance. Thus, metabolically activity of NTO measured in terms of ∆SUVmax NTO is a potential candidate for future treatment individualization (i.e. organ preservation).

Neoadjuvant chemoradiotherapy is increasingly used in oesophageal cancer patients. In general, small tumours are associated with a survival benefit compared to large tumours. Little is known, however, about the relationship between initial tumour volume and response to chemoradiotherapy. Therefore, the aim of this study was to determine whether the pretherapy metabolic tumour volume (MTV) on diagnostic PET/CT in oesophageal cancer patients is correlated with response to chemoradiotherapy in the resection specimen. A consecutive series of patients underwent diagnostic PET/CT scanning prior to chemoradiotherapy and oesophagectomy. MTVs were determined on PET/CT and an automated tumour contour was generated using specified standard uptake value thresholds. Response to chemoradiotherapy was determined in the resection specimen according to the scoring system developed by Mandard et al. Patients were divided into different groups according to response to chemoradiotherapy. Between January 2008 and May 2011 a total of 115 patients underwent an oesophagectomy. The MTV determined on diagnostic PET/CT scans was available in 79 patients. Of these 79 patients, 30 (38 %) showed no residual tumour cells at the location of the primary tumour. Three of these patients presented with residual tumour cells in the lymph nodes; 27 patients (34 %) had a complete pathological response. There was a trend towards a better response in patients with a smaller MTV (p = 0.084). This study demonstrated a trend towards a correlation between response to chemoradiotherapy in oesophageal cancer patients and smaller MTVs as determined on diagnostic PET/CT prior to neoadjuvant chemoradiotherapy. However, tumour volumes overlapped between groups, indicating the need for multifactorial parameters as predictors. In addition, a complete local tumour response may be accompanied by residual disease in the regional lymph nodes.

Purpose Intratumour uptake heterogeneity in PET quantified in terms of textural features for response to therapy has been investigated in several studies, including assessment of their robustness for reconstruction and physiological reproducibility. However, there has been no thorough assessment of the potential impact of preprocessing steps on the resulting quantification and its predictive value. The goal of this work was to assess the robustness of PET heterogeneity in textural features for delineation of functional volumes and partial volume correction (PVC).

The nucleoside analogue 3'-deoxy-3'-[18F]fluorothymidine (FLT) has been introduced for imaging of tumour cell proliferation by positron emission tomography (PET). This study evaluated the use of FLT in patients with thoracic tumours prior to treatment. Whole-body FLT PET was performed in 16 patients with 18 tumours [17 thoracic tumours (nine non-small cell lung cancers, five oesophageal carcinomas, two sarcomas, one Hodgkin's lymphoma) and one renal carcinoma] before treatment. Fluorine-18 fluorodeoxyglucose (FDG) PET was performed for comparison except in those patients with oesophageal carcinoma. For semi-quantitative analysis, the average and maximum standardised uptake values (avgSUV and maxSUV, respectively) (FLT, 114±20 min p.i.; FDG, 87±8 min p.i.; 50% isocontour region of interest) was calculated. All 17 thoracic tumours and 19/20 metastases revealed significant FLT accumulation, resulting in easy delineation from surrounding tissue. The additional small grade 1 renal carcinoma was not detected with either FLT or FDG. In most lung tumours (avgSUV 1.5–8.2) and metastases, FLT showed intense uptake. However, one of two spinal bone metastases was missed owing to the high physiological FLT uptake in the surrounding bone marrow. Oesophageal carcinoma primaries (avgSUV 2.7–10.0) and occasional metastases showed particularly favourable tumour/non-tumour contrast. Compared with FDG, tumour uptake of FLT was lower (avgSUV, P=0.0006; maxSUV, P=0.0001), with a significant linear correlation (avgSUV, r 2=0.45; maxSUV, r 2=0.49) between FLT and FDG. It is concluded that FLT PET accurately visualises thoracic tumour lesions. In the liver and the bone marrow, high physiological FLT uptake hampers detection of metastases. On the other hand, FLT may be favourable for imaging of brain metastases owing to the low physiological uptake.

International audience; It has been suggested that FDG PET has predictive value for the prognosis of treated oesophageal carcinoma. However, the studies reported in the literature have shown discordant results. The aim of this study was to determine whether pretherapy quantitative metabolic parameters correlate with patient outcomes. Included in the study were 67 patients with a histological diagnosis of oesophageal squamous cell carcinoma. Each patient underwent (18)F-FDG PET (4.5 MBq/kg) before chemoradiotherapy. Quantitative analysis was performed using the following parameters: age, weight loss, location, N stage, OMS performance status, MTVp and MTVp' (metabolic tumour volume determined by two different physicians), MTV40% (volume for a threshold of 40 % of SUVmax), MTVa (volume automatically determined with a contrast-based adaptive threshold method), SUVmax, SUVmean and TLG (total lesion glycolysis). MTVp and MTV40% were highly correlated (Pearson's index 0.92). SUVmeanp and SUVmean40% were also correlated (Pearson's index 0.86), as were TLGp and TLG40% (Pearson's index 0.98). Similarly, the parameters obtained with the adaptive threshold method (MTVa, SUVmeana and TLGa) were correlated with those obtained manually (MTVp, SUVmeanp and TLGp). The manual metabolic tumour volume determination (MTVp and MTVp') was reproducible. Multivariate analysis for disease-free survival (DFS) showed that a larger MTVp was associated with a shorter DFS (p = 0.004) and that a higher SUVmax was associated with a longer DFS (p = 0.02). Multivariate analysis for overall survival (OS) showed that a larger MTVp was associated with a shorter OS (p = 0.01) and that a tumour in the distal oesophagus was associated with a longer OS (p = 0.005). The associations among the other parameters were not statistically significant. Metabolic tumour volume is a major prognostic factor for DFS and OS in patients with oesophageal squamous cell carcinoma. Higher SUVmax values were paradoxically associated with longer survival. The location of the tumour also appeared to affect prognosis.

A recent paper from the University of Cologne [1] cast some doubts on the usefulness of F-FDG PET in evaluating the response to chemotherapy of patients affected by oesophageal carcinoma. The authors reported on 55 patients recruited from a prospective trial on neoadjuvant radio-chemotherapy. Patients were studied before and at least 3 weeks after the completion of the treatment. Maximum and mean standardized uptake value (SUV) were measured using two different methods and compared with the histopathology assessment of tumour regression. Briefly, the authors reported that: (1) baseline SUV values were higher in responders; (2) after therapy, SUV was lower in responders; and (3) there were no significant differences between the SUV values of responders and those of non-responders. The conclusion of this paper is that F-FDG PET is not a suitable tool for measuring response to radio-chemotherapy in oesophageal carcinoma. Besides several differences in patient populations and technical aspects between studies, these conclusions cast some doubts on the reports by the Munich group, which assessed F-FDG PET as a useful tool in evaluating response in patients with carcinoma of the oesophagogastric junction [2–4]. Levine reported results going in the same direction on patients affected by locally advanced oesophageal cancer [5]. Also, some reviews on the use of F-FDG PET in oesophageal carcinoma [6, 7] concluded enthusiastically on the future use of F-FDG PET not only for staging, but also for prognostic stratification and response evaluation. It must be underlined that other authors [8–10] were already critical of the use of F-FDG PET in making important clinical decisions on patient treatments. Oesophageal carcinoma is only one of the solid tumours and lymphomas that are studied with F-FDG PET in order to assess tumour response to radiation and chemotherapy treatments, which has been recently summarized [11] in a literature review. Above and beyond the general enthusiasm which every new application of nuclear medicine procedures evokes in the nuclear medicine community, we have to be aware that controversial results may emerge in the medium and long term when limited series of patients are studied. Moreover, the large variety of pathologic types of tumours which may be studied must be carefully taken into consideration, as they have different biological behaviour, which ends up in a different capacity to take up a particular biological probe such as F-FDG. The first issued to be faced and solved is the standardization of the technical parameters. We, as nuclear medicine physicians, should do our best to establish some standard parameters to be employed when assessing solid tumours. These parameters are not required to have a general value for all tumour types, but must be determined for as many tumours as possible. This is not an easy task, but the consensus conference on Hodgkin’s lymphoma [12] demonstrated that it is possible, and some efforts have already been made on the technical issues concerning multicentre trials [13]. General issues like ROI drawing and timing of acquisition must be the subject of harmonization proEur J Nucl Med Mol Imaging (2009) 36:733–734 DOI 10.1007/s00259-009-1092-2