my poster presentation in the jcms2011 conference
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my poster presentation in the jcms2011 conference Document Transcript

  • 1. PAWITRA MASA-AH, MALULEE TUNTAWIROON, SOMPHOB SOONGSATHITANONNuclear Medicine Division, Department of Radiology,Faculty of Medicine Siriraj Hospital, Mahidol University Background In PET scan, the standardized uptake value (SUV) is used for quantitative analysis of dynamic data and represents the ratio of 18F-FDG uptake within a region of interest (ROI) relative to its background. A malignant lesion is considered to have a high uptake of 18F-FDG radiopharmaceutical. In this research, we created a new Header image (metadata) scheme of SUV calculation from DICOM file by using MATLAB and tested performance by comparison the obtained SUV from the scheme to the SUV from the well-known application software by GE healthcare (Xeleris workstation). STEP 1 : Extract Pixel Intensity Value in Defined ROI (Region Of Interest). • Materials and Methods DICOM files from PET were used as a sample source. The scheme of SUV calculation was used the data from STEP 2 : Convert Intensity Pixel Value the PET images and the other related data such as patient to Activity concentration (Becquerel). (a) weight, activity dose, rescale slope, rescale intercept, etc. This data was taken from the DICOM files. 108 slices of DICOM files were STEP 3 : Calculate SUV in a slice. obtained from 11 patients (8 men, 3 women) and comparative analysis of both systems was done by drawing the region of interest (ROI) in a slice with the same size and position. STEP 4 : Integral SUV of ROIs (slice) to VOI • (volume) • Results The correlation between the two systems is statistically significant with a 99% confidence interval. The average percentage of accuracy is 85% for the report at a 95% confidence interval. The result showed a percentage of accuracy in the range of 83.91% to 86.48% at a 95% confidence interval. The performance test of the new scheme demonstrated agreeable results that are practical to (b) medical prognosis and research. Figure 2 SUV calculation process by Figure 3 Analysis screen of (a) Xeleris • MATLAB Workstation and (b) MATLAB • Conclusion The results showed that the SUV from the scheme created by MATLAB could be used interchangeably with a PET/CT Xeleris® workstation. The interchangeability of this scheme offers The SUV from Xeleris Workstation and MATLAB were compared by the Pearson correlation user convenience and approachability of data and is a stand-alone Test. The result showed high correlation coefficient of 0.974 indicating a close correlation of application that allows more accessibility. Physicians can interpret results from Xeleris workstation and MATLAB. R2 is 0.9487, we can say that about 99% of PET/CT scans without further applications of other software.. comparable capability to predict the SUVMATLAB from SUVXeleris, 1% remain for other factors plus randomness. The Accuracy of SUV of MATLAB scheme and Xeleris workstation, Table 1 Statistical an analysis of accuracy of SUVs obtained from MATLAB scheme. SUV (Standardized Uptake Value) is the value that often used in PET scan. It is most commonly used semi-quantitative parameter utilized for analyzing FDG-PET images in Std. Std. Mean % Accuracy routine clinical practice. It came to be used as a tool to supplement visual interpretation. Deviation Err. Standardized uptake values (SUVs) are a measure of the concentration of a radiotracer in a 11 Patients Mean 85.2036 6.7329 0.6479 defined region of interest (ROI) divided by the injected dose normalized for the patients N=108 body weight at a fixed time after tracer injection. Being a ratio, it is unit less and is calculated 95%Confidence Lower Bound 83.9193 by   Interval for Mean Upper Bound 86.4880        - Minimum 75.16                 - Maximum 99.96     …(1)       Comparison of Percentage Accuracy of SUV from Percentage Accuracy of SUV from MATLAB The cut-off value for malignant lesion is 2.5 and it has largely been proven to be an MATLAB to Xeleris Workstation Scheme (sorted by range from 0 to 30) 30 120 oversimplification. SUV does provide an objective parameter for image analysis and is useful for research purpose. For patients with cancer, it is important to report SUV of chosen index 25 100 ACCURACY (%) lesions. 20 80 To calculate the SUV, ROI was drawn on the image that was appeared on the screen by the 15 60 MATLAB reader (physician). The computer then calculates the average density or maximum density in 10 40 that ROI, then the decay of uptake in the period and counting efficiency were corrected. The Xeleris pixel intensity value in the ROI area finally was converted to the activity per gram of 5 20 tissue, assuming tissue density is equal to 1 g/cc. The body weight (kg) and injected dose (μCi 0 0 or Bq) were together used, the SUV is calculated for the ROI using Eq. 1. All process above 0 5 10 15 20 25 30 0 10 20 30 needs a specific application program. SUVmax SUV Figure 4 Scatter gram shows the percentage accuracy from the MATLAB scheme SUV Calculation Scheme REFERENCES 1. Masa-Ah P, Soongsathitanon S. A Novel Standardized Uptake Value (SUV) Calculation of PET DICOM Files Using MATLAB. In: Mastorakis PNE, Mladenov PV, Bojkovic PZ, editors. NEW ASPECTS of APPLIED SUV Calculation INFORMATICS, BIOMEDICAL ELECTRONICS & INFORMATICS and COMMUNICATIONS: WSEAS Scheme Input Press; 2010. p. 413-6. … Output 2. Masa-Ah P, Tuntawiroon M, Soongsathitanon S. A Novel Scheme for Standardized Uptake Value (SUV) Calculation in by SUVs PET Scans. INTERNATIONAL JOURNAL OF MATHEMATICAL MODELS AND METHODS IN APPLIED DICOM files SCIENCES, NAUN. 2010; 4(4):291-9. MATLAB Figure 1 Framework of the SUV calculation scheme