Introduction Current guidelines recommend the use of semiautomated assessment of F-18 FDG PET brain studies. Accuracy is influenced by the normal data, which requires knowledge of the included subjects and how they were acquired. Due to confidentiality, such information is often not completely disclosed. Our aim was to determine the variation in FDG uptake between several commercially available and our in-house normal database. Methods Our database contains 83 healthy subjects. Outlier detection using SPM further ensured normality, resulting in exclusion of three subjects. The remaining 80 subjects were analyzed using three commercially available software packages. Z-score data per patient and per lobe were extracted and pooled in predefined age groups (18–40, 41–60 and 61–80 years old) with a calculation of mean Z-scores and SD. Correlation between Z-score output of different software was investigated. Results In the 18–40 years age group, frontotemporal hypermetabolism was found with all software. Decreased cerebellar uptake was found with two software packages. Mean Z-scores are closer to zero in the 41–60 years age group compared to the younger group, and mostly within the normal range in the 61–80 years age group with all software. A moderate to high linear correlation between Z-score output was found, but individual Z-scores varied widely. Conclusions The three software packages yielded varying Z-score output, partially explained by an age mismatch between our subjects and subjects in their normal databases. A definitive explanation for the remaining differences is lacking. This emphasizes the importance of age-matched normal data and knowledge of the included databases to allow adequate preprocessing.
Human planning is a complex mental process that may be evaluated by the 'Tower of London' (TOL) task, which includes setting up and maintaining multiple subgoals at the same time. Although positron emission tomography and functional magnetic resonance imaging have provided reliable data on the recruitment of a neural network engaged in planning tasks, the experimental settings of these studies cannot be applied in clinical conditions. Hence, this study reports on the TOL task under classical neuropsychological test conditions using single photon emission computed tomography (SPECT) activation in 10 healthy subjects.Participants first performed a control task and then an activation task, i.e., the TOL planning task In the planning task, subjects were required to change, in the minimum number of moves possible, an initial arrangement of beads to match a goal arrangement. Subjects solved a set of eight TOL problems of increasing difficulty. A control task was designed such that it eliminates planning abilities, which is the process of interest. Planning times and accuracy were measured as performance parameters and functional imaging data were analysed with statistical parametric mapping (SPM99) to determine significant voxel-wise activations between the planning task and the control task.Both overall and for each difficulty level, measures of accuracy were within the normal range. Similar results were found for the overall thinking time and thinking times of each difficulty level. That is, performance of the healthy subjects during the TOL task replicated the typical pattern of results found with appropriate control samples in the literature. Also, activation of the right prefrontal cortex was consistent with other functional imaging results, thereby validating the use of the TOL task in a SPECT activation paradigm.Based on the present study it may be concluded that the close resemblance of the test conditions of the SPECT activation procedure with those of the TOL task in the investigation room constitutes a major advantage for future application of the SPECT activation procedure in clinical conditions.
dequate staging is essential in patients with peritoneal carcinomatosis (PC) from colorectal cancer (CRC) who are candidates for cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC). Metabolic imaging using (18)F-FDG-PET-CT is commonly used to exclude distant metastasis in these patients. Here, we aimed to assess the performance of (18)F-FDG-PET-CT in locoregional staging of the extent of PC.Patients with PC from CRC underwent staging including 18F-FDG-PET-CT. In the absence of systemic -dissemination, CRS and oxaliplatin based HIPEC were performed. The extent of PC was quantified during surgery using the modified 7 region count (7RC). The correlation between imaging based estimation of PC extent and surgical 7RC was analyzed using Pearson correlation using both patient based and region based analyses.Fifty-five patients were included between February 2005 and October 2018. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 57%, 98%, 95%, 78% and 82% respectively for non-mucinous tumors and 32%, 100%, 100%, 55% and 63% respectively. (18)F-FDG-PET-CT detected the presence of colorectal PC in 96% of patients suffering from PC with nonmucinous histology and in 60% of patients suffering from PC with mucinous histology. Correlation between imaging 7RC and surgical 7RC was better for PC with nonmucinous histology (r = 0.623) than for PC with mucinous histology (r = -0.180).Despite of underestimating the exact extent of disease involvement, (18)F-FDG-PET-CT shows good performance in detecting colorectal PC with nonmucinous histology. For colorectal PC with mucinous histology, (18)F-FDG-PET-CT, however, shows poor performance. Since (18)F-FDG-PET-CT did not detect the presence of colorectal PC in all patients in whom long-term survival could be achieved, (18)F-FDG-PET-CT should be implemented into a broad pre-operative assessment strategy.
