Average SUVmean Research Articles

Concurrent Respiratory Motion Correction of Abdominal PET and Dynamic Contrast-Enhanced-MRI Using a Compressed Sensing Approach.

We present an approach for concurrent reconstruction of respiratory motion-compensated abdominal dynamic contrast-enhanced (DCE)-MRI and PET data in an integrated PET/MR scanner. The MR and PET reconstructions share the same motion vector fields derived from radial MR data; the approach is robust to changes in respiratory pattern and does not increase the total acquisition time. Methods: PET and DCE-MRI data of 12 oncologic patients were simultaneously acquired for 6 min on an integrated PET/MR system after administration of 18F-FDG and gadoterate meglumine. Golden-angle radial MR data were continuously acquired simultaneously with PET data and sorted into multiple motion phases on the basis of a respiratory signal derived directly from the radial MR data. The resulting multidimensional dataset was reconstructed using a compressed sensing approach that exploits sparsity among respiratory phases. Motion vector fields obtained using the full 6-min (MC6-min) and only the last 1 min (MC1-min) of data were incorporated into the PET reconstruction to obtain motion-corrected PET images and in an MR iterative reconstruction algorithm to produce a series of motion-corrected DCE-MR images (moco_GRASP). The motion-correction methods (MC6-min and MC1-min) were evaluated by qualitative analysis of the MR images and quantitative analysis of SUVmax and SUVmean, contrast, signal-to-noise ratio (SNR), and lesion volume in the PET images. Results: Motion-corrected MC6-min PET images demonstrated 30%, 23%, 34%, and 18% increases in average SUVmax, SUVmean, contrast, and SNR and an average 40% reduction in lesion volume with respect to the non-motion-corrected PET images. The changes in these figures of merit were smaller but still substantial for the MC1-min protocol: 19%, 10%, 15%, and 9% increases in average SUVmax, SUVmean, contrast, and SNR; and a 28% reduction in lesion volume. Moco_GRASP images were deemed of acceptable or better diagnostic image quality with respect to conventional breath-hold Cartesian volumetric interpolated breath-hold examination acquisitions. Conclusion: We presented a method that allows the simultaneous acquisition of respiratory motion-corrected diagnostic quality DCE-MRI and quantitatively accurate PET data in an integrated PET/MR scanner with negligible prolongation in acquisition time compared with routine PET/DCE-MRI protocols.

Is 18F-FDG PET/CT a valuable diagnostic tool for verifying accelerated atherosclerosis secondary to diabetes mellitus on insulin in the aortic segments and large arteries?

Fluorine-18 fluorodeoxylglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has a well-established role for detection and quantification of atherosclerotic inflammatory disease using standardized uptake value (SUV) measurements. Our aim was to compare the inflammatory and macroscopic calcification processes of atherosclerosis in the aortic segments and large arteries of subjects with insulin dependent diametes mellitus (IDDM) compared to those of age-matched controls via 18F-FDG PET/CT. A hundred and ten subjects who underwent 18F-FDG PET/CT imaging for oncological diseases were retrospectively studied. Fifty five were diabetics on insulin and 55 were age-matched controls. Average SUVmax and SUVmean for four segments of aorta and for common iliac arteries and femoral arteries were measured and compared between subject groups. Presence or absence of macroscopic calcification on CT images for each arterial segment was also noted and compared between these groups. Average SUVmax and SUVmean were statistically significantly greater in subjects with IDDM compared to controls in all arterial segments (P≤0.001). Presence of calcification on CT was more frequently encountered in 6 of the 8 segments in subjects with IDDM, and there was statistically significantly difference for the descending aorta and abdominal aorta. Our results show that inflammatory component of atherosclerosis was more severe in all aortic segments in subjects with IDDM compared to those of controls. Presence of macroscopic calcification also detected to be more frequently encountered in the descending thoracic and abdominal aorta in subjects with IDDM. Fluorine-18-FDG PET/CT is a valuable diagnostic tool for detecting and semi-quantifying accelerated atherosclerotic inflammatory and calcific changes secondary to diabetes mellitus treated with insulin in the aortic segments and large arteries.

Effect of Androgen on Normal Biodistribution of [18F]-2'-Fluoro-5-methyl-1-beta-D-arabinofuranosyluracil (18F-FMAU) in Athymic Non-tumor-bearing Male Mice.

We assessed the association between the presence and absence of androgen on the normal biodistribution of the positron emission tomography (PET) cellular proliferation imaging biomarker, [18F]-2'-Fluoro-5-methyl-1-beta-D-arabinofuranosyluracil (18F-FMAU), in mice. Non-castrated (n=4) and castrated (n=4) athymic non-tumor-bearing male mice served as models for presence and absence, respectively, of androgen. MicroPET-CT scans were performed 1 h following tail vein administration of 200 uCi of 18F-FMAU. Imaging was performed at baseline and then at 7-day intervals longitudinally for 35 days only in castrated mice following subcutaneous introduction of a 12.5 mg, 21-day release, dihydrotestosterone pellet. Mean standardized uptake values (SUVmean) were obtained for liver, heart, and muscle. Several two-group comparisons of average of SUVmean were performed. Pre-pellet baseline average SUVmean (±s.d.) values in castrated mice were significantly lower than baseline non-castrated values, increased on day 15 and reached peak values on day 28, at which time they were significantly higher than corresponding baseline levels in both non-castrated and pre-pellet castrated mice. The peak values decreased significantly following dihydrotestosterone withdrawal. There is a significant modulatory effect of androgen on normal 18F-FMAU uptake levels in mice liver, heart and muscle tissues.

Semiquantitative Parameters in PSMA-Targeted PET Imaging with 18F-DCFPyL: Variability in Normal-Organ Uptake.

18F-DCFPyL is a small-molecule inhibitor of the prostate-specific membrane antigen that has shown promise for evaluation of primary and metastatic prostate cancer using PET. Measuring the variability in normal-organ uptake of 18F-DCFPyL is necessary to understand its biodistribution, aid image interpretation, judge the reliability of scan quantification, and provide a basis for therapeutic monitoring. Methods: Sixty-five consecutive 18F-DCFPyL PET/CT scans from 64 patients with a history of prostate cancer were analyzed. Volumes of interest were defined for the lacrimal glands, major salivary glands, liver, spleen, and both kidneys. The mean SUV normalized to body mass or to lean body mass (SUL) was calculated for each volume of interest. The average SUV across all scans, the SD, and the coefficient of variation (COV) for each organ were calculated. The same parameters were also derived for a 3-cm sphere drawn in the center of the right lobe of the liver. Results: The average SUVmean for all selected organs measured was 6.6 ± 1.8 for the right lacrimal gland, 6.4 ± 1.8 for the left lacrimal gland, 9.1 ± 2.0 for the right parotid gland, 9.0 ± 2.1 for the left parotid gland, 9.6 ± 2.3 for the right submandibular gland, 9.4 ± 2.2 for the left submandibular gland, 5.0 ± 0.7 for the whole liver, 5.1 ± 0.7 for a 3-cm sphere in the liver, 4.0 ± 1.5 for the spleen, 20.1 ± 4.6 for the right kidney, and 19.4 ± 4.5 for the left kidney. SULmean was lower overall, although demonstrating similar trends. The COV of SUVmean and SULmean was lower in the liver (13.8% and 14.5%, respectively) than in any other organ and was less than the comparable COV for 18F-FDG PET. The COV of SUVmean and SULmean in the 3-cm sphere in the liver was also low and similar to the variability in the whole liver (14.2% and 14.7%, respectively). Conclusion:18F-DCFPyL uptake in normal liver demonstrates less variability than in other 18F-DCFPyL-avid organs, and its variability is less than the reported variability of 18F-FDG in liver. Variability was slightly less for SUVmean than for SULmean, suggesting that SUVmean may be the preferable parameter for quantification of images obtained with 18F-DCFPyL.

WE‐H‐207A‐04: Impact of Lesion Location On the Repeatability of 18F‐NaF PET/CT

Purpose:Quantifying the repeatability of imaging biomarkers is critical for assessing therapeutic response. While 18F‐NaF PET/CT has shown to be a repeatable imaging method, research has not shown which factors may influence its repeatability. The purpose of this study was to evaluate whether the location of the lesion impacts the repeatability of quantitative 18F‐NaF PET‐derived SUV metrics.Methods:Metastatic castrate‐resistant prostate cancer patients with multiple bone lesions received whole‐body test‐retest NaF PET/CT scans. Malignant bone lesions of PET‐defined volume greater than 1.5 cm3 were identified by a nuclear medicine physician and automatically delineated using a SUV>15 threshold. The maximum (SUVmax), average (SUVmean), and total (SUVtotal) SUV were extracted from each lesion. Atlas‐based segmentation was used to divide each patient skeleton into 25 skeletal regions. Test‐retest repeatability of each SUV metric was assessed with coefficient of variation (CV).Results:A total of 265 malignant bone lesions from 18 patients were identified by nuclear medicine physician. The largest proportion of bone lesions were localized to the spine (41%), with 41% of those lesions localized to the thoracic spine. One‐way ANOVA showed that measurement differences differed significantly for all three metrics across locations (p<0.01 for each metrics). Overall, CV was smallest for SUVmean at 5.3%, followed by SUVmax at 11.5% and SUVtotal at 20.4%. Lesions in the pubis were consistently the most repeatable (CV(SUVmax)= 5.6%, CV(SUVmean)= 0.6%, CV(SUVtotal)= 2.9%). According to SUVmean, repeatability was poorest in the cervical spine (CV = 6.2%), whereas according to SUVmax and SUVtotal, repeatability was poorest in the ribs (CV(SUVmax)= 15.0%, CV(SUVtotal)= 29.8%).Conclusion:Location of the lesion affects the repeatability of 18F‐NaF PET/CT, with the ribs and cervical spine having the lowest repeatability and the pubis having the highest repeatability. These results can be used to establish location‐specific response criteria for NaF PET‐based treatment response assessment.

(18)F Sodium Fluoride PET/CT in Patients with Prostate Cancer: Quantification of Normal Tissues, Benign Degenerative Lesions, and Malignant Lesions.

Understanding the range and variability of normal, benign degenerative, and malignant 18F sodium fluoride (18F NaF) positron emission tomography/computed tomography (PET/CT) uptake is important in influencing clinical interpretation. Further, it is essential for the development of realistic semiautomated quantification techniques and simulation models. The purpose of this study is to determine the range of these values in a clinically relevant patient population with prostate cancer. 18F NaF PET/CT scans were analyzed in patients with prostate cancer (n = 47) referred for evaluation of bone metastases. Mean and maximum standardized uptake values [SUVs (SUVmean and SUVmax)] were made in normal background regions (n = 470) including soft tissues (liver, aorta, bladder, adipose, brain, and paraspinal muscle) and osseous structures (T12 vertebral body, femoral diaphyseal cortex, femoral head medullary space, and ribs). Degenerative joint disease (DJD; n = 281) and bone metastases (n = 159) were identified and quantified by an experienced reader using all scan information including coregistered CT. For normal bone regions, the highest 18F NaF PET SUVmean occurred in T12 (6.8 ± 1.4) and it also showed the lowest coefficient of variation (cv = 21%). For normal soft tissues, paraspinal muscles showed very low SUVmean (0.70 ± 0.11) and also showed the lowest variability (cv = 16%). Average SUVmean in metastatic lesions is higher than uptake in benign degenerative lesions but values showed a wide variance and overlapping values (16.3 ± 13 vs 11.1 ± 3.8; P < 0.00001). The normal 18F NaF PET uptake values for prostate cancer patients in normal background, benign degenerative disease, and osseous metastases are comparable to those reported for a general population with a wide variety of diagnoses. These normal ranges, specifically for prostate cancer patients, will aid in clinical interpretation and also help to establish the basis of normal limits in a semiautomated data analysis algorithm.

Variability of Hepatic 18F-FDG Uptake at Interim PET in Patients With Hodgkin Lymphoma.

When evaluating response of Hodgkin lymphoma (HL) to chemotherapy on interim (18)F-FDG-PET/CT, physiological liver uptake is used as reference. Hodgkin lymphoma sites with uptake greater than liver are interpreted as positive. We aimed at examining factors that might influence liver uptake as reference organ. Fifty patients with HL who received baseline (18)F-FDG-PET/CT (PET1) and interim PET (PET2), usually after 2 cycles of adriamycin bleomycin, vinblastine, and dacarbazine chemotherapy, were included retrospectively. SUVmean normalized for body weight (SUVmean) and for lean body mass (SULmean) were obtained from regions of interest in the right lobe of the liver. On univariate analysis, liver SUVmean on interim PET increased with increasing body mass index (BMI) (P = 0.0453) and were higher in women (P = 0.0401). These factors remained significant on multivariate analysis (P = 0.009 and P = 0.008, respectively). No significant correlation was found with postinjection delay, blood glucose level, and age. Liver SULmean were not affected by the studied variables. Average liver SUVmean in the 50 patients were similar at baseline and interim PET. In 11 patients (22%), however, there was 30% or greater variation in liver SUVmean between PET1 and PET2. No factors explaining intrapatient variation in hepatic uptake between PET1 and PET2 were found on correlation analysis. At interim PET in patients with HL, liver SUVmean depends on BMI and sex, but not liver SULmean. Furthermore, our study, conducted with standard clinical procedure, also confirmed the high range of liver uptake values from one patient to another. Caution is required when using liver SUV as reference in patients with high BMI. Intrapatient fluctuation in liver SUVmean should also be expected.

Dual Time Point FDG-PET/CT Imaging Can Distinguish Between Hodgkin Lymphoma and Diffuse Large B-Cell Lymphoma

▪Introduction: 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) has become a standard of care imaging modality for multiple types of lymphoma, including Hodgkin lymphoma (HL) and diffuse large B-cell lymphoma (DLBCL). However, many applications of PET/CT in lymphomas have not yet been explored. We investigated whether dual time point (DT) PET/CT would detect more sites of disease due to improved tumor to background ratio. It has also been reported that inflammatory lesions have decreased FDG accumulation over time, whereas malignant lesions accumulate FDG over time, becoming more FDG-avid. Histologically, HL lesions are predominantly composed of inflammatory cells and relatively few tumor cells. This tumor composition calls into question whether HL will behave as a malignancy or as an inflammatory lesion on DT PET/CT imaging compared to DLBCL and whether changes in FDG accumulation over time on DT PET/CT imaging will differ between HL and DLBCL.Methods: Patients (pts) with untreated, biopsy-confirmed, nodular sclerosing HL and DLBCL were prospectively enrolled on this clinical trial (clinicaltrials.gov NCT01004718). Pts with uncontrolled diabetes, active infection, and primary mediastinal large B-cell lymphoma were excluded. Following injection of FDG, pts underwent PET/CT at 60 minutes (DT60) and 180 minutes (DT180). Any lesion with a Deauville Score of 4-5 was considered positive (i.e. FDG uptake > liver at any site) (Meignan, Leuk Lymphoma 2012). SUVmax, SUVmean, and tumor to background ratio, defined as lesion SUVmax / liver SUVmean, were calculated for each lesion. Software using an automatic adaptive thresholding method (ROVER, ABX GmbH) was also used to measure the metabolically active volume (MAV) of lesions on PET images. Mean metabolic volumetric product (MVPmean) was calculated as MVPmean = SUVmean * MAV for each lesion, and total MVPmean for a given pt was calculated as the sum of MVPmean for all lesions.Results: 160 total lesions (78 lesions with DT60 and 82 lesions with DT180 images) were evaluated in this prospective study of 20 paired PET/CT scans in 10 pts. Five pts had HL and 5 had DLBCL. Median age was 51; 5 pts were men. Pts with DLBCL had higher SUVmax values at both 60 and 180 minutes than HL (DT60: DLBCL 22.4 v HL 10.8, p = 0.0007, t test; DT180: DLBCL 31.6 v HL 14.6, p = 0.0006, t test) as well as a higher average SUVmean than HL at both time points (DT60: DLBCL 9.2 v 4.5, p = 0.009 t test; DT180: DLBCL 12.7 v 5.8, p = 0.02 t test). We also observed that the average %change in tumor to background ratio for HL increased from DT60 to D180 by 75% whereas the %change in tumor to background ratio for DLBCL increased by 34% (p = 0.0001, t-test). DT180 detected 4 additional lesions that were not apparent on DT60; 3 lesions were in HL and 1 in DLBCL. The locations of these lesions were mesenteric, lung, external iliac, and subclavian regions. For each pt, %change in total MVPmean between DT60 and DT180 was higher in DLBCL (p=0.02, rank sum). Of interest, the %change in MAV between DT60 and DT180 decreased in HL compared to slight increase in DLBCL (HL 12% decrease v. DLBCL 2% increase in MAV). Thus, changes in MAV accounted for the difference detected in %change in total MVPmean between these histologies. There was no difference between HL and DLBCL in %change in SUVmean or %change in SUVmax.Conclusions: We report the first prospective study of dual time point PET/CT imaging of lymphomas, as well as the first study to specifically compare dual time point imaging of DLBCL and HL. Our results indicate that lesions of DLBCL are generally more FDG-avid than HL when measured as either SUVmax or SUVmean at 60 and 180 minutes. When measured as %change in total MVPmean, DLBCL accumulates significantly more FDG than HL, consistent with the differences in histologic composition of these tumors. Computerized algorithms for generation of MAV and SUVmean add additional information not reflected in measurement of SUVmax alone that may be useful for distinguishing between tumor histologies. Given variation between histologies, optimal timing of image acquisition for detection of lesions may be improved by choosing an imaging time point that optimizes tumor to background ratio. Tumor to background ratio is improved, especially for HL, with use of imaging that occurs at 180 minutes, and we demonstrate the ability to detect additional lesions not detected at 60 minutes. DisclosuresNo relevant conflicts of interest to declare.

Quantitative assessment of global hepatic glycolysis in patients with cirrhosis and normal controls using 18F-FDG-PET/CT: a pilot study

To compare differences in global measures of hepatic metabolism between control subjects and subjects with cirrhosis. FDG-PET/CT scans of 33 subjects either without or with cirrhosis were analyzed retrospectively and classified as follows: group 1 includes subjects without cirrhosis or extrahepatic malignancy (1a) (n=11) and subjects without cirrhosis but with history of extrahepatic malignancy (1b) (n=10); group 2 includes subjects with cirrhosis and history of extrahepatic malignancy (n=12). Subjects with focal hepatic lesions, prior hepatic surgery, co-existing liver pathology, or who received chemotherapy or radiation therapy within the last 6 months were excluded. The hepatic volumes, hepatic mean standardized uptake value (SUVmean), and global hepatic glycolysis (GHG) were compared between groups. Subjects with cirrhosis showed a lower average hepatic SUVmean as compared to non-cirrhotic patients (1.55±0.29 for group 2 versus 1.81±0.23 for group 1; p value=0.009) and lower average values for GHG (2238.29±903.60 for group 2 versus 2974.67±829.16 for group 1; p value=0.024). No differences were noted between the non-cirrhotic subgroups (i.e., between the groups 1a and 1b) without and with associated extrahepatic malignancy, respectively. We hypothesize that presence of fibrosis, reduction of active inflammation, and decreased hepatic metabolism and function are potential causes of the lower FDG uptake in cirrhotic livers. Our results also indicate that extrahepatic cancer status does not influence FDG uptake in the non-cirrhotic liver in subjects without hepatic metastases.

Impact of Clinical and Dosimetric Factors on Pericardial Effusion in Patients With Stage I Esophageal Cancer Treated With Definitive Chemoradiation Therapy

Purpose/Objective(s): The aim of this study was to quantitatively evaluate the value of diagnostic information provided by both F-FDG and F-FLT PET and quantitatively investigated whether F-FLT PET had a better performance compared with F-FDG PET in esophageal squamous cell carcinoma (ESCC) staging and delineation. Materials/Methods: Twenty-six patients with newly diagnosed ESCC and underwent pretreatment F-FDG and F-FLT PET were included in this study. The indices such as the standardized uptake value (SUV), gross tumor length and extracted texture parameters between F-FDG and F-FLT PET were compared, respectively. Moreover, the indices’ relationship between F-FDG and F-FLT PET mentioned above, were analyzed using Spearman’s correlation coefficient and Paired T-test. Subsequently all patients received esophagectomy and the extracted PET indices’ capability in ESCC pathological staging were assessed by Kruskal-Wallis test and Mann-Whitney test. In addition, tumor delineation length on F-FDG (SUV threshold 2.5) and F-FLT (SUV threshold 1.4) PET were validated by pathologic gross tumor length. Results: F-FDG highly correlated with F-FLT possessing a high correlation coefficient value r approximate 0.8 and p < 0.001 in SUVmax or SUVmean. F-FDG uptake was significantly higher than F-FLT with respect to average SUVmax(F-FDG: 11.48, F-FLT: 6.07) or average SUVmean (F-FDG: 6.09, F-FLT: 3.80), with Paired T-test result p < 0.001. In terms of texture parameters’ relationship Entropy and Correlation (two derived texture parameters) showed statistically significant difference. Both of F-FDG and F-FLT PET SUV, some of texture parameters, gross tumor length and shape feature showed statistically significant difference with respect to their feasibility in ESCC staging. The mean standard deviation pathologic longitudinal tumor length was 5.52 2.56 cm and delineation length for F-FDG and F-FLT were 5.60 2.32 cm and 5.49 2.43 cm, respectively. Conclusions: The F-FDG and F-FLT PET scans have their own advantages in ESCC staging and tumors were well identified as the nonphysiologic distribution of radiotracers intensity typically higher than normal tissues on either PET scans. Delineation on the two types of PET with proper threshold can both provide accuracy estimation of pathologic tumor length. Those different indices extracted from PET scans can be potentially employed to differentiate AJCC and TNM in ESCC stage. Author Disclosure: C. Ma: None. Y. Yin: None.

Variability of Total Lesion Glycolysis by 18F-FDG-Positive Tissue Thresholding in Lung Cancer

The aim of this work was to assess the variability of total lesion glycolysis (TLG) measurements in lung cancer patients, obtained with fixed percentages of the maximum standardized uptake value (SUVmax) thresholds. Thirteen lesions (10 patients) were analyzed in 10 successive 2.5-min frames of an (18)F-FDG PET dynamic acquisition obtained between 60 and 110 min after injection. (18)F-FDG-positive lesion volume, associated average SUV (SUVmean), and TLG (volume × SUVmean) were assessed in each frame using thresholds of 40%, 50%, 60%, 70%, and 80%. For each threshold, the average relative SD of TLG, leading to relative measurement error and repeatability, was calculated over the lesion series. The dependence of TLG variability on volume and SUVmean variability was also assessed. The average relative SD of TLG correlated strongly with threshold: 1.0866 × exp(0.0472 × threshold) (r = 0.999; P < 0.01). For the 40% threshold, average TLG over the series was 225.9 g (range, 41.7-1,086.3), relative measurement error and repeatability were 14.5%-20.4% (95% confidence interval), and no significant difference was found between TLG and volume variability. For the other thresholds, TLG variability was significantly lower or greater than volume or SUVmean variability, respectively. In current clinical practice, a formula allows quick estimation of TLG variability for any percentage of the SUVmax threshold: the higher the threshold the greater the TLG variability.

SU‐E‐J‐116: Quantitative Study of 18F‐Fluorodeoxyglucose and 18F‐Fluorothymidine PET Characteristics in Esophageal Squamous Cell Carcinoma Staging

Purpose: The aim of this study was to quantitatively evaluate the value of diagnostic information provided by both 18F‐FDG and 18F‐FLT PET and quantitatively investigated whether 18F‐FLT PET had a better performance compared with 18F‐FDG PET in esophageal squamous cell carcinoma (ESCC) staging and delineation. Methods: 26 patients with newly diagnosed ESCC and underwent pretreatment 18F‐FDG and 18F‐FLT PET were included in this study. The indices such as the standardized uptake value (SUV), gross tumor length and extracted texture parameters between 18F‐FDG and 18F‐FLT PET were compared, respectively. Tumor delineation length on 18F‐FDG (SUV threshold 2.5) and 18F‐FLT (SUV threshold 1.4) PET were validated by pathologic gross tumor length. Results: 18F‐FDG highly correlated with 18F‐FLT possessing a high correlation coefficient value r approximate 0.8 and p&lt;0.001 in SUVmax or SUVmean. 18F‐FDG uptake was significantly higher than 18F‐FLT with respect to average SUVmax(18F‐FDG: 11.48, 18F‐FLT: 6.07) or average SUVmean (18F‐FDG: 6.09, 18F‐FLT: 3.80), with Paired T‐test Result p&lt;0.001. In terms of texture parameters relationship Entropy and Correlation (two derived texture parameters) showed statistically significant difference. Both of 18F‐FDG and 18F‐FLT PET SUV, some of texture parameters,gross tumor length and shape feature showed statistically significant difference with respect to their feasibility in ESCC staging. The mean±standard deviation pathologic longitudinal tumor length was 5.52±2.56 cm and delineation length for 18F‐FDG and 18F‐FLT were 5.60±2.32 cm and 5.49±2.43 cm, respectively. Conclusion: The 18F‐FDG and 18F‐FLT PET scans have their own advantages in ESCC staging and tumors were well identified as the nonphysiologic distribution of radiotracers intensity typically higher than normal tissues on either PET scans. Those different indices extracted from PET scans can be potentially employed to differentiate AJCC and TNM in ESCC stage.

Evaluation of hepatic metabolic activity in non-alcoholic fatty livers on 18FDG PET/CT

ObjectiveThe liver has been used as a reference organ for the assessment of abnormal 18F-fluoro-2-deoxy-d-glucose (18FDG) in the body. Some researchers found that hepatosteatosis significantly changed the hepatic 18FDG uptake, while others did not. This study investigated whether the liver's 18FDG uptake was affected by the diffuse fatty infiltration of the liver. Material and methodsA total of 156 cases were included in this study. Different patient groups were defined according to the liver Hounsfield unit (HU). The HU was calculated from an unenhanced CT, for all patients, and we calculated the mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on an 18FDG PET scan. For this purpose, we placed regions of interest (ROIs) on the liver image. We statistically compared the SUVmean and SUVmax measured in the fatty liver patients and the control group. ResultsThe average SUVmean and SUVmax values were calculated as 2.58±0.66 and 3.94±1, respectively, in the patient group and 2.54±0.57 and 3.7±0.88, respectively, in the control group. We found the average SUVmean and SUVmax values in the fatty liver group and its subsets were not significantly different from the values in the control group (p>0.05). We also did not find any statistically significant correlation between average liver density (HU) and the average SUV values (p>0.05). ConclusionFatty infiltration may not have a significant effect on the liver's 18FDG uptake. Thus, the liver may be used as a reference or comparator on 18FDG PET scans in patients with fatty liver disease.

NON-INVASIVE SERIAL MONITORING OF ATHEROSCLEROTIC PLAQUE PROGRESSION AND THROMBOSIS WITH PET-CT IN A RABBIT MODEL

Objectivesto investigate the characteristics of atherosclerotic plaque progression at different stages with PET-CT imaging as well as the feasibility and accuracy of detecting vulnerable plague using this fused imaging techniques.MethodsEighteen...

Evaluation of hepatic metabolic activity in non-alcoholic fatty livers on 18FDG PET/CT

The liver has been used as a reference organ for the assessment of abnormal (18)F-fluoro-2-deoxy-d-glucose ((18)FDG) in the body. Some researchers found that hepatosteatosis significantly changed the hepatic (18)FDG uptake, while others did not. This study investigated whether the liver's (18)FDG uptake was affected by the diffuse fatty infiltration of the liver. A total of 156 cases were included in this study. Different patient groups were defined according to the liver Hounsfield unit (HU). The HU was calculated from an unenhanced CT, for all patients, and we calculated the mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on an (18)FDG PET scan. For this purpose, we placed regions of interest (ROIs) on the liver image. We statistically compared the SUVmean and SUVmax measured in the fatty liver patients and the control group. The average SUVmean and SUVmax values were calculated as 2.58±0.66 and 3.94±1, respectively, in the patient group and 2.54±0.57 and 3.7±0.88, respectively, in the control group. We found the average SUVmean and SUVmax values in the fatty liver group and its subsets were not significantly different from the values in the control group (p>0.05). We also did not find any statistically significant correlation between average liver density (HU) and the average SUV values (p>0.05). Fatty infiltration may not have a significant effect on the liver's (18)FDG uptake. Thus, the liver may be used as a reference or comparator on (18)FDG PET scans in patients with fatty liver disease.

Abstract 5308: PET imaging of hypoxia with [64]Cu-ATSM in human ovarian cancer: Comparison of xenografts in mice and rats

Abstract Aim: [64]Cu-ATSM (Cu-ATSM) is a promising hypoxia tracer for PET imaging. However, relatively low uptake is seen in human xenografts in mice compared to patients. We hypothesized that human xenografts in rats might render higher uptake and be a better and clinically more relevant model for study of hypoxia in tumors. Accordingly, we compared hypoxia imaging in human ovarian cancer xenografts implanted in nude mice and nude rats. In addition, the hypoxia tracer accumulation was compared to that of [18]F-FDG (FDG), as well as to gene expression of HIF-1α. Methods: All animals had 10⁁7 A2780 human ovarian cancer cells inoculated into each flank. After 2-3 weeks all animal were subjected to a FDG scan 1 hr post injection. The following day each animal were PET scanned again, both 1hr and 22 hrs after injection of Cu-ATSM. Immediately after the 22 hr scan the animals were euthanized and the tumors resected. Total RNA was isolated from whole tumor tissue extracts (mice xenografts n=12; rat xenografts n=8) and gene expression measurements performed, using quantitative real-time PCR. PET data were reconstructed using the MAP algorithm, regions of interest drawn on the PET images and tracer uptake (SUV) calculated. Finally, correlation between tracer uptake and gene expression was analyzed by linear regression. Results: Cu-ATSM uptake in A2780 xenografts from mice had average SUVmean value of 0.32±0.02 and 0.30±0.01, at 1 and 22 hrs post injection, respectively. Compared to this, the xenografts from rats had an average SUVmean value of 1.73±0.09 1 hr post injection, and like in the mice, had a small decrease to 1.35±0.05 at 22 hrs post injection. The same pattern was seen for the Cu-ATSM SUVmax values decreasing from 0.71±0.04 to 0.64±0.02 in mice and from 3.75±0.09 to 3.39±0.20 in rats. The average SUVmean and SUVmax values for FDG 1 hr post injection was 0.38±0.02 and 0.79±0.03 in mice and 3.27±0.34 and 6.83±0.80 in rats, respectively. No correlation between SUV for Cu-ATSM and FDG was seen. For the mice, gene expression of HIF-1α showed a positive correlation with SUVmean values of Cu-ATSM both 1 and 22 hrs post injection (r=0.77, p=0.004; r=0.65, p=0.02, respectively). In the same way HIF-1α also correlated with SUVmax 1 hr post injection (r=0.60, p=0.04). No correlations were found between HIF-1α and FDG SUV values. Gene expression measurements of tumors from rats are currently being conducted. Conclusion: A 5-6 fold higher uptake of Cu-ATSM was seen in human ovarian cancer xenograft tumors when implanted in nude rats compared to nude mice. The SUV values in rats was of the same magnitude as seen in patients making the rat model promising as a tool for further translational research on hypoxia imaging. The Cu-ATSM tumor uptake showed good correlation with gene expression of HIF-1α but did not correlate with FDG uptake. This indicates that Cu-ATSM is indeed reflecting hypoxia and that information is different than that obtained with FDG PET. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5308. doi:10.1158/1538-7445.AM2011-5308