Development of Program for Renal Function Study with Quantification Analysis of Nuclear Medicine Image / 대한핵의학회잡지

PURPOSE: In this study, we developed a new software tool for the analysis of renal scintigraphy which can be modified more easily by a user who needs to study new clinical applications, and the appropriateness of the results from our program was studied. MATERIALS AND METHODS: The analysis tool was programmed with IDL5.2 and designed for use on a personal computer running Windows. For testing the developed tool and studying the appropriateness of the calculated glomerular filtration rate (GFR), 99mTc-DTPA was administered to 10 adults in normal condition. In order to study the appropriateness of the calculated mean transit time (MTT), 99mTc-DTPA and 99mTc-MAG3 were administered to 11 adults in normal condition and 22 kidneys were analyzed. All the images were acquired with ORBITOR, the Siemens gamma camera. RESULTS: With the developed tool, we could show dynamic renal images and time activity curve (TAC) in each ROI and calculate clinical parameters of renal function. The results calculated by the developed tool were not different statistically from the results obtained by the Siemens application program (Tmax: p=0.68, Relative Renal Function: p=1.0, GFR: p=0.25) and the developed program proved reasonable. The MTT calculation tool proved to be reasonable by the evaluation of the influence of hydration status on MTT. CONCLUSION: We have obtained reasonable clinical parameters for the evaluation of renal function with the software tool developed in this study. The developed tool could prove more practical than conventional, commercial programs.

Role of PET in Evaluating Indeterminate Solitary Pulmonary Nodule with CT / 대한핵의학회잡지

About one-third of radiologically indeterminate solitary pulmonary nodules (SPN) are eventually turned out to be malignant. It is very important to noninvasively determine whether the SPN is malignant or not for the decision of its way of management. PET imaging is highlighted by its unique ability of imaging the function and metabolism of cells. Glucose metabolism is increased in malignant transformed cells. We performed FDG-PET studies in patients who ha radiologi- cally indeterminate SPN and compared the findings with histologic diagnoses to assess the diagnostic accuracy in the detection of malignancy and to decide which parameter is the most suitable for clinical practice among peak SUV (pSUV), average SUV (aSUV), 50/10 ratio, and time-activity curve (TAC). Thirty patients were included in this study and the most useful parameter was pSUV. The sensitivity and specificity in the detection of malignant SPN using 3.5 as a cut off pSUV were both 87%. Interestingly, all 2 false-negative cases were bronch- ioloalveolar carcinoma on histologic examination. If these cases, which could be strongly suspected by CT findings, were excluded, the sensitivity of pSUV was 100%. In conclusion, PET imaging is very helpful for determining malignancy in indeterminate SPN and pSUV is a conveniently measurable parameter which is valuable for interpretation.

The Differentiation of Benign from Malignant Soft Tissue Lesions using FDG-PET: Comparison between Semi-quantitative Indices / 대한핵의학회잡지

The purpose of this study is to evaluate the diagnostic accuracy of various quantitative indices for the differentiation of benign from malignant primary soft tissue tumors by FDG-PET. A series of 32 patients with a variety of histologically or clinically confirmed benign (20) or malignant (12) soft tissue lesions were evaluated with emission whole body (5min/bed position) PET after injection of [18F]FDG. Regional 20min transmission scan for the attenuation correction and calculation of SUV was performed in 16 patients (10 benign, 6malignant) followed by dynamic acquisition for 56min. Postinjection transmission scan for the attenuation correction and calculation of SUV was executed in the other 16 patients (10 benign, 6 malignant). The following indices were obtained : the peak and average SUV (pSUV, aSUV) of lesions, tumor-to-background ratio acquired at images of 51 min p.i. (TBR51), tumor-to-background ratio of areas under time-activity curves (TBRarea) and the ratio between the activities of tumor ROI at 51 min p.i. and at the time which background ROI reaches maximum activity on the time-activity curves (T51/Tmax). The pSUV, aSUV, TBR51, and TBRarea, in malignant lesions were significantly higher than those in benign lesions. We set the cut-off values of pSUV, aSUV, TBR51, TBRarea and T51/Tmax for the differentiation of benign and malignant lesions at 3.5, 2.8, 5.1, 4.3 and 1.55, respectively. The sensitivity, specificity and accuracy were 91.7%, 80.0%, 84.4% by pSUV and aSUV, 83.3%, 85.0%, 84.4% by TBR51, 83.3%, 100%, 93.8% by TBRarea and 66.7%, 70.0%, 68.8% by Tsl/Tmax. The time-activity curves did not give additional information compared to SUV or TBR. The one false negative was a case with low-grade fibrosarcoma and all four false positives were cases with inflammatory change on histology. The visual analysis of FDG-PET also detected the metastatic lesions in malignant cases with comparable accuracy. In conclusion, all pSUV, aSUV, TBR51, and TBRarea are useful metabolic semi-quantitative indices with good accuracy for the differentiation of benign from malignant soft-tissue lesions.