Ki Chun Im

[18F]Fluorothymidine Positron Emission Tomography before and 7 Days after Gefitinib Treatment Predicts Response in Patients with Advanced Adenocarcinoma of the Lung

Purpose: To evaluate the usefulness of 3′-deoxy-3′-[18F]fluorothymidine (FLT)-positron emission tomography (PET) for predicting response and patient outcome of gefitinib therapy in patients with adenocarcinoma of the lung. Experimental Design: Nonsmokers with advanced or recurrent adenocarcinoma of the lung were eligible. FLT-PET images of the thorax were obtained before and 7 days after the start of gefitinib (250 mg/d) therapy, the maximum standardized uptake values (SUVmax) of primary tumors were measured, and the percent changes in SUVmax were calculated. After 6 weeks of therapy, the responses were assessed by computed tomography of the chest. Results: Among 31 patients who were enrolled, we analyzed 28 patients for whom we had complete data. Chest computed tomography revealed partial response in 14 (50%), stable disease in 4 (14%), and progressive disease in 10 (36%) after 6 weeks of treatment. Pretreatment SUVmax of the tumors did not differ between responders and nonresponders. At 7 days after the initiation of therapy, the percent changes in SUVmax were significantly different (−36.0 ± 15.4% versus 10.1 ± 19.5%; P < 0.001). Decrease of >10.9% in SUVmax was used as the criterion for predicting response. The positive and negative predictive values were both 92.9%. The time to progression was significantly longer in FLT-PET responders than nonresponders (median, 7.9 versus 1.2 months; P = 0.0041). Conclusion: FLT-PET can predict response to gefitinib 7 days after treatment in nonsmokers with advanced adenocarcinoma of the lung. The change in tumor SUVmax obtained by FLT-PET seems to be a promising predictive variable.

Factors Affecting Accuracy of Ventricular Volume and Ejection Fraction Measured by Gated Tl-201 Myocardial Perfusion Single Photon Emission Computed Tomography

The electrocardiogram-gated single photon emission computed tomography (SPECT) measurement of left ventricular end-diastolic volume, end-systolic volume and ejection fraction may contain substantial errors. We evaluated whether patient-related factors affect the accuracy of left ventricular volume and ejection fraction measured by gated Tl-201 SPECT. A total of 518 patients without perfusion defects on Tl-201 SPECT or coronary artery disease were studied. Left ventricular volume and ejection fraction were measured from echocardiography and adenosine stress/redistribution gated Tl-201 SPECT using commercially available software packages (QGS and 4D-MSPECT). We identified factors affecting the accuracy of gated SPECT via multiple linear regression analysis of the differences between echocardiography and gated SPECT. Gated SPECT analyzed with QGS underestimated end-diastolic and end-systolic volume, and overestimated ejection fraction, but 4D-MSPECT overestimated all those values (P<0.001). Independent variables associated with increasing the difference in end-diastolic volume between echocardiography and gated SPECT were decreasing left ventricular end-diastolic wall thickness, decreasing body surface area, female sex and increasing end-diastolic volume (P<0.001). Those for end-systolic volume were decreasing left ventricular end-systolic wall thickness, female sex, and decreasing end-systolic volume (P<0.001). Increasing end-systolic wall thickness, male sex and decreasing age were independent determinants associated with an increased difference in ejection fraction (P<0.001). Adenosine stress SPECT showed significantly higher end-diastolic and end-systolic volume values and a lower ejection fraction than did redistribution SPECT (P<0.001). Patient-related factors affect the accuracy of left ventricular volume and ejection fraction measured by gated Tl-201 SPECT. Modification of gated SPECT measurements by taking account of these factors would lead to reduce systemic errors.

PET/CT Fusion Viewing Software for Use with Picture Archiving and Communication Systems

We developed positron emission tomography (PET)/computed tomography (CT) viewing software (PETviewer) that can display co-registered PET and CT images obtained by PET/CT and stored on picture archiving and communication systems (PACS). PETviewer has tools for presetting windows for CT display; control bars for PET window level; zoom, pan, and pseudo-color functions; and allows the user to draw a rectangular region of interest (ROI) for standardized uptake value (SUV) measurement. SUV was calculated using PET DICOM header information and the pixel intensity in PETviewer. Reconstructed datasets of PET/CT and maximum intensity projection (MIP) of the PET images were transferred and archived in PACS. Phantom experiments were performed to evaluate the validity of image fusion. PET/CT images were displayed on an independent window in PACS. Transaxial PET images were reformatted as sagittal and coronal PET images, which were displayed with the corresponding CT and PET/CT fusion images with adjustable color and transparency. Transaxial, sagittal, and coronal PET images corresponding to the location of the cursor were shown using cine display of MIP images. All images were displayed in PETviewer within 20xa0s on a personal computer for PACS, which was equipped with a P4, 1.3-GHz CPU, and 512xa0Mb of RAM. We could measure maximum and mean SUV in a ROI using PETviewer. Transaxial fused images of patients and phantoms showed excellent registration and fusion of PET and CT images in the X and Y directions. PETviewer provided very useful clinical tools for assessing PET/CT images on PACS and should assist in maximizing the benefits derived from PET/CT imaging.

SU‐FF‐J‐24: Investigate On the Deconvolution Method to Compensate the Movement of the Object During PET Scanning

Purpose: The deconvolution method to compensate the movement of the object during PET scanning was investigated. The motion artifact should be removed for exact staging of the patient. Method and Materials: The PETimages for movable object with FDG using Biograph(Siemens, USA) were obtained. The FDG drugged small object with 1mm diameter and 5 cm long was installed at the end of the cam of the moving phantom. The profiles for Z‐direction, movement direction, including the maximum intensity point, were extracted from the images. The 1‐D movement of the phantom was calculated from the physical distance of the moving phantom. The iterative deconvolution method was implemented on the profile obtained from the moving phantom to compensate the movement of the object. Results: The profile from convolution between profile for stationary case and 1‐dimensional movement of the scanning object was calculated. The maximum intensity of the stationary case (543,915 bq/ml) was 158% higher than the movable case(343,803 bq/ml). The calculated profile (319,685 Bq/ml) was well agreed with the movable one within 7%. Conclusion: Due to the movement during the PET scanning, the scanning signals are reduced and affect on the maximum SUV, derived from the maximum intensity in the interested region. The movement of the organ should be monitored by given solution such as RPM. The suggested iterative deconvolution method could be implemented on the most movable direction, and it could successfully remove at least 1‐dimentional motion artifact.