Difference In Standardized Uptake Value Research Articles

Attenuation correction of emission PET images with average CT: Interpolation from breath-hold CT

Misregistration resulting from the difference of temporal resolution in PET and CT scans occur frequently in PET/CT imaging, which causes distortion in tumor quantification in PET. Respiration cine average CT (CACT) for PET attenuation correction has been reported to improve the misalignment effectively by several papers. However, the radiation dose to the patient from a four-dimensional CT scan is relatively high. In this study, we propose a method to interpolate respiratory CT images over a respiratory cycle from inhalation and exhalation breath-hold CT images, and use the average CT from the generated CT set for PET attenuation correction. The radiation dose to the patient is reduced using this method. Six cancer patients of various lesion sites underwent routine free-breath helical CT (HCT), respiration CACT, interpolated average CT (IACT), and 18F-FDG PET. Deformable image registration was used to interpolate the middle phases of a respiratory cycle based on the end-inspiration and end-expiration breath-hold CT scans. The average CT image was calculated from the eight interpolated CT image sets of middle respiratory phases and the two original inspiration and expiration CT images. Then the PET images were reconstructed by these three methods for attenuation correction using HCT, CACT, and IACT. Misalignment of PET image using either CACT or IACT for attenuation correction in PET/CT was improved. The difference in standard uptake value (SUV) from tumor in PET images was most significant between the use of HCT and CACT, while the least significant between the use of CACT and IACT. Besides the similar improvement in tumor quantification compared to the use of CACT, using IACT for PET attenuation correction reduces the radiation dose to the patient.

Squamous Cell Carcinoma of the Palatine Tonsils: FDG Standardized Uptake Value Ratio as a Biomarker to Differentiate Tonsillar Carcinoma from Physiologic Uptake

To quantify fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake in the palatine tonsils to identify a sensitive and specific metric for distinguishing physiologic asymmetric uptake from squamous cell carcinoma (SCC). This HIPAA-compliant retrospective study was approved by institutional review board. Informed consent requirements were waived. Twenty-six patients (seven female, 19 male; mean age, 53.46 years + or - 10.45 [standard deviation]) with tonsillar SCC were included. Twenty-six patients (seven female, 19 male; mean age, 61.77 years + or - 10.12) with head and neck carcinomas not involving the tonsils were included as control subjects. Tonsil standardized uptake values (SUVs) were measured bilaterally in each group. Independent-samples t test was used to compare mean SUVs, and Pearson correlation was used to evaluate association of FDG uptake between tonsils within control subjects. The mean maximum SUV (SUV(max)) of tonsil tumors was 9.36 + or - 4.54, which was significantly higher than that of contralateral cancer-free tonsils (2.54 + or - 0.88; P < .0001) and tonsils in control subjects (2.98 + or - 1.08; P < .0001). In patients with tonsillar cancer, the mean difference in SUV(max) between tonsils was 10.43 + or - 7.07, which was significantly greater than that in control subjects (0.62 + or - 0.54; P < .0001). The mean SUV(max) ratio between tonsils in patients with carcinoma was 3.79 + or - 1.69, which was threefold higher than in control subjects (1.18 + or - 0.13; P < .0001). For receiver operating characteristic analysis using SUV(max) ratio to differentiate benign uptake from SCC, the area under the curve was 1.00 (95% confidence interval: 1.00, 1.00). A cutoff ratio of 1.48 had 100% sensitivity and specificity. The SUV(max) ratio represents an accurate imaging biomarker for differentiating tonsillar SCC from physiologic (18)F-FDG uptake.

Glucose Uptake Patterns in Exercised Skeletal Muscles of Elite Male Long-Distance and Short-Distance Runners

The aim of this study was to determine glucose uptake patterns in exercised skeletal muscles of elite male long-distance and short-distance runners. Positron emission tomography (PET) using 18F-fluoro-2-deoxyglucose (FDG) was performed to determine the patterns of glucose uptake in lower limbs of short-distance (SD group, n=8) and long-distance (LD group, n=8) male runners after a modified 20 min Bruce treadmill test. Magnetic resonance imaging (MRI) was used to delineate the muscle groups in lower limbs. Muscle groups from hip, knee, and ankle movers were measured. The total FDG uptake and the standard uptake value (SUV) for each muscle group were compared between the 2 groups. For the SD and LD runners, the 2 major muscle groups utilizing glucose during running were knee extensors and ankle plantarflexors, which accounted for 49.3 +/- 8.1% (25.1 +/- 4.7% and 24.2 +/- 6.0%) of overall lower extremity glucose uptake for SD group, and 51.3 +/- 8.0% (27.2 +/- 2.7% and 24.0 +/- 8.1%) for LD group. No difference in muscle glucose uptake was noted for other muscle groups. For SD runners, the SUVs for the muscle groups varied from 0.49 +/- 0.27 for the ankle plantarflexors, to 0.20 +/- 0.08 for the hip flexor. For the LD runners, the highest and lowest SUVs were 0.43 +/- 0.15 for the ankle dorsiflexors and 0.21 +/- 0.19 for the hip. For SD and LD groups, no difference in muscle SUV was noted for the muscle groups. However, the SUV ratio between the ankle dorsiflexors and plantarflexors in the LD group was significantly greater than that in the SD group. We thus conclude that the major propelling muscle groups account for approximately 50% of lower limb glucose utilization during running. Thus, the other muscle groups involving maintenance of balance, limb deceleration, and shock absorption utilize an equal amount. This result provides a new insight into glucose distribution in skeletal muscle, suggesting that propellers and supporters are both energetically important during running. Furthermore, for each unit muscle volume, movers of ankle are more glucose-demanding than those of hip.

Use of 18F-fluorodeoxyglucose positron emission tomography for diagnosis of uterine sarcomas

We evaluated the use of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for the diagnosis of uterine sarcomas. FDG-PET combined with serum lactate dehydrogenase (LDH) levels were compared with FDG-PET alone for the diagnosis of leiomyosarcomas (LMS), which are the most difficult uterine sarcomas to diagnose. FDG-PET imaging of endometrial cancer (EC) was used as a reference. Immunoreactivity for glucose transporter-1 (GLUT-I) correlated with FDG uptake was evaluated in sarcomas and leiomyomas (LM), including cases not examined by FDG-PET. FDG was injected after at least 5 h fasting and standardized uptake values (SUVs) were analyzed quantitatively 50-70 min after injection. Immunohistochemical expression of GLUT-1 was studied in paraffin sections of tumors using anti-GLUT-1 antibodies and GLUT-1 expression scores were derived based on staining intensities. FDG-PET was performed preoperatively in a total of 53 patients including 10 with sarcomas, 19 with EC and 24 with LM. Immunohistochemical examination was performed in 17 sarcomas, 6 EC and 9 LM [6 usual LM, 1 uterine smooth muscle tumor of uncertain malignant potential (UMP), and 2 bizarre LM (BLM)]. SUVs for uterine sarcomas and EC were significantly higher (p=0.0001) than those for LMs. There were no significant differences in SUVs among ECs, carcinosarcomas (CS) and LMS. Significant differences in SUVs existed between LM and LMS (p=0.003). However, the diagnostic accuracy for LMS was only 73%. The diagnostic accuracy of FDG-PET combined with serum LDH was 100%. GLUT-1 expression scores were significantly higher in sarcomas and EC than in LM (p<0.0001). Intermediate GLUT-1 scores were found in two of the three cases of UMP and BLM. In conclusion, FDG-PET is useful for diagnosing uterine sarcomas, while FDG-PET combined with serum LDH is useful for diagnosing LMS. Immunohistochemical examination of GLUT-1 confirmed the high FDG uptake in LMS patients.

Assessment of Fluorodeoxyglucose Uptake by Leiomyomas in Relation to Histopathologic Subtype and the Menstrual State

The aim of this study was to assess fluorodeoxyglucose (FDG) uptake by leiomyomas in relation to histopathologic subtype and the menstrual state. We performed a retrospective study of 92 patients referred for uterine leiomyomas confirmed by histopathologic findings. On FDG-positron emission tomography, quantitative evaluation was performed using the mean values of the standardized uptake value (SUV) with reference to magnetic resonance imaging findings. Of the 92 patients, 56 had typical leiomyomas (41 premenopausal and 15 postmenopausal women), whereas 36 patients with subtype leiomyomas consisted of 21 premenopausal and 15 postmenopausal women. Although no significant differences in SUV were observed between the typical and subtype leiomyomas, tumoral SUV was significantly higher in the premenopausal patients than in the postmenopausal patients. Uterine tumoral FDG uptake during the proliferative phase was also slightly lower than in the other menstrual phases. The FDG uptake by leiomyomas in premenopausal women was greater than that in postmenopausal women.

FDG–PET can distinguish inflamed from non-inflamed plaque in an animal model of atherosclerosis

The presence of activated macrophages is an important predictor of atherosclerotic plaque rupture. In this study, our aim was to determine the accuracy of (18)F- fluorodeoxyglucose (FDG) microPET imaging for quantifying aortic wall macrophage content in a rabbit model of atherosclerosis. Rabbits were divided into a control group and two groups post aortic balloon injury: 6 months high-cholesterol diet (HC); and 3 months HC followed by 3 months low-cholesterol diet plus statin (LCS). In vivo and ex vivo microPET, ex vivo well counting and histological quantification of the atherosclerotic aortas were performed for all groups. Macrophage density was greater in the HC group than the LCS group (5.1 +/- 1.4% vs. 0.6 +/- 0.7%, P < 0.001) with a trend towards greater macrophage density in LCS compared to controls (P = 0.08). There was a strong correlation across all groups between macrophage density and standardized uptake value (SUV) derived from ex vivo microPET (r = 0.95, P < 0.001) and well counting (r = 0.96, P < 0.001). Ex vivo FDG SUV was significantly different between the three groups (P < 0.001). However, the correlation between in vivo microPET FDG SUV and macrophage density was insignificant (r = 0.16, P = 0.57) with no statistical differences in FDG SUV seen between the three groups. This study confirms that in an animal model of inflamed and non-inflamed atherosclerosis, significant differences in FDG SUV allow differentiation of highly inflamed atherosclerotic aortas from those stabilized by statin therapy and low cholesterol diet and controls.

6539 The difference in standardized uptake value on 18F-FDG-PET before and after pre-operative chemotherapy is a prognostic factor for recurrence and survival in patients with gastroesophageal cancer

6539 The difference in standardized uptake value on 18F-FDG-PET before and after pre-operative chemotherapy is a prognostic factor for recurrence and survival in patients with gastroesophageal cancer

A Pilot Study for Using 3′-Deoxy-3′-[18f]Fluorothymidine Positron Emission Tomography ([18F]FLT PET/CT) Imaging for Early Assessment of Response to Induction Chemotherapy in Acute Myeloid Leukemia (AML)

Background: AML patients that are treated with induction chemotherapy undergo an early bone marrow assessment approximately 10–14 days after beginning treatment to determine the response to therapy. This bone marrow assessment is an imperfect measure of disease response and lacks sensitivity and specificity in determining subsequent remission. A more accurate assessment of chemotherapy responsiveness performed early during induction chemotherapy could allow better prediction of later remission and earlier change in therapy to improve outcome among patients that are not responding well to treatment. Thymidine uptake can be used to assess chemotherapy sensitivity in vitro, and we hypothesized that this would also be true in vivo. We performed a pilot study of [18F] FLT PET/CT scans to predict response to induction chemotherapy among patients with AML.Methods: Eight patients with AML were treated with induction chemotherapy and whole body [18F]FLT PET/CT scans were performed at different time points (pre-treatment, day 1, 3, 4, 5 and 14) using approximately 5 mCi of [18F]FLT. Two patients had scans before treatment and day 14. Ten adult subjects without hematologic disease also underwent [18F] FLT PET/CT and these studies were used as normal controls. The CT images were used to reconstruct a skeletal mask that was then used to extract the bone marrow [18F]FLT signal from the PET images. The scans from those with normal bone marrow were used to establish baseline assessment parameters. The images from the scans could be quantified by computer analysis into bone marrow standardized uptake values (SUV). The bone marrow SUV were compared between the AML patients (responders vs. non-responders) relative to normal controls. The mean SUV values (SUVmean), max SUV values (SUVmax) and coefficient of variation (CV) were used in the comparison.Results: The PET/CT was well tolerated and no adverse events were noted, although one patient did not complete the scan due to the development of epistaxis. Of the seven patients who completed the scan, 3 patients entered a complete remission after a single course of induction (responders) and 4 patients either required two induction courses to achieve remission or had refractory disease (non-responders). The responders had recovery of an ANC > 500 by day 22, 28, and 35 suggesting the [18F]FLT did not delay bone marrow regeneration. The fall in the bone marrow SUV occurred quickly and as early as day 1 after the beginning of chemotherapy among responders. Both mean and maximum total bone marrow SUV was significantly lower in responders compared to non-responders: SUVmean: 0.76±0.04 vs. 1.23±0.22, SUVmax: 3.6±0.01 vs 7.7±2.2. In addition, it was noted that the variation in SUV throughout the skeleton was more uniform in responders than non-responders resulting in a difference in CV: 0.29±0.01 vs 0.54±0.10. The differences in SUV and signal variation in the bone marrow were easily apparent when viewing the images from the scans. The significant heterogeneity in axial skeletal uptake among non-responders was notable and suggests that chemotherapy responsiveness is not uniform throughout the bone marrow and that there likely are islands of persistent/unresponsive disease during therapy. It is not clear whether the variation is due to islands of drug resistance, differences in blood flow, or rates of response. This non-uniformity of marrow uptake among non-responders may explain the poor predictive value of the day 10–14 bone marrow aspirate drawn at the iliac crest.Conclusion: In our small pilot study, [18F]FLT PET/CT could distinguish between responders and non-responders among patients undergoing induction chemotherapy for AML possibly as early as one day following the beginning of treatment. Also, the scans suggest that response to chemotherapy in AML does not occur uniformly throughout the bone marrow space and that in non-responders, there are islands of disease that persist after chemotherapy. These finding warrant further study of [18F]FLT PET/CT as a tool for early response assessment in AML.

Evaluation of Segmental Pancreatic Function Using 11C-Methionine Positron Emission Tomography for Safe Operation of Living Donor Pancreas Transplantation

For the safe operation of living donor pancreas transplantation, we investigated the utility of 11C-methionine positron emission tomography (PET) to examine the function of the residual pancreatic head in patients with pancreatic disease undergoing distal pancreatectomy and in living donors of pancreas transplantation. After 6 hours of fasting, we intravenously injected 370 to 740 MBq 11C-methionine. PET was scanned 30 minutes after injection. 11C-methionine PET uptake by the pancreatic head versus body/tail was expressed as a standardized uptake value (SUV). The SUVs of the pancreatic head were compared before versus after surgery. The SUVs of the pancreatic head in patients before and after distal pancreatectomy were 15.3 ± 6.0 and 18.2 ± 2.4, respectively. The SUVs of the pancreatic head in donors before and after distal pancreatectomy were 16.1 ± 1.0 and 14.7 ± 1.4, respectively. Both patients and donors showed no significant difference in SUVs of the pancreatic head before and after surgery. However, the SUVs of the residual pancreatic head were elevated after distal pancreatectomy in 80% of patients and 50% of donors. These data indicated that the function of the pancreatic head may be maintained or improved after distal pancreatectomy. 11C-methionine PET may become a potent modality to evaluate segmental pancreatic function for a safe living donor operation.

Standardized uptake values of uterine leiomyoma with 18F-FDG PET/CT: variation with age, size, degeneration, and contrast enhancement on MRI

To assess the effect of age, size, the degree of degeneration, and contrast enhancement on magnetic resonance imaging (MRI) on 18F-fluoro-2-deoxyglucose (18F-FDG) uptake in uterine leiomyomas using quantitative standardized uptake values (SUVs). A total of 61 leiomyomas of 41 patients, who underwent combined positron emission tomography/computed tomography (PET/CT) using 18F-FDG and contrast-enhanced MRI were included in this study. Sixty-one leiomyomas were divided into two groups: "non-degenerated" leiomyomas showing distinct low signal intensity on T2-weighted images and intermediate signal intensity on T1-weighted images, and "degenerated" leiomyomas showing other types of signal intensity. Sixty-one leiomyomas were also divided into two groups of "strongly enhancing" leiomyomas and "weakly enhancing" leiomyomas in terms of their degree of contrast enhancement on MRI. The mean values of the maximum and average SUVs for the total of 61 leiomyomas were 2.34 +/- 0.75 (range 1.59-5.15) and 1.74 +/- 0.50 (0.66-3.95), respectively. There was a moderate negative correlation between the maximum and average SUVs and age (r = -0.43 and P = 0.00016, r = -0.31 and P = 0.029, respectively). Although there was a mild positive correlation between maximum SUV and size (r = 0.35 and P = 0.011), there was no significant difference between average SUV and size. Although there was no significant difference in average SUV between "degenerated" and "non-degenerated" leiomyomas, the maximum SUV of "degenerated" leiomyomas was significantly higher than that of "non-degenerated" leiomyomas (P = 0.0012). The degree of contrast enhancement on MRI was not significantly correlated with 18F-FDG uptake. Mild or moderate uptake of 18F-FDG is often observed in uterine leiomyoma and declines with age, and should not be confused with malignant accumulation.

Grading of brain glioma with 1-11C-acetate PET: comparison with 18F-FDG PET

The objective of this study is to reevaluate the clinical significance of 1-11C-acetate (ACE) positron emission tomography (PET) in patients with brain glioma, in comparison with 18F-fluorodeoxyglucose (FDG) PET. Ten patients with histologically proven glioma were included in this study. They underwent PET examination with both FDG and ACE on separate days. For ACE PET, 20-min data acquisition was performed just after the administration of 740 MBq of ACE; 10-20-min data were used for the analysis. FDG PET data acquisition for 10 min started 60 min postinjection of 370 MBq of FDG, approximately. Both reconstructed images were converted to standardized uptake value (SUV) images for patient body weight and injected dose. Regions of interest were placed on the tumor and the contralateral cerebral cortex, and SUV and tumor-to-cortex ratio (T/C) were calculated; these values were compared between high- and low-grade gliomas. SUV and T/C of ACE PET showed significant difference (SUV: 2.63+/-0.46 vs. 1.85+/-0.56, P=.03; T/C: 2.36+/-0.63 vs. 1.14+/-0.36, P=.02). In contrast, FDG PET revealed no significant difference in SUV or T/C between high- and low-grade gliomas (SUV: 7.13+/-4.31 vs. 4.71+/-1.27, P=.31; T/C: 0.98+/-0.55 vs. 0.62+/-0.09, P=.22). This preliminary study revealed that ACE PET is a promising tracer for the grading of brain glioma.

Diagnosis of maxillofacial tumor withl-3-[18F]-fluoro-α-methyltyrosine (FMT) PET: a comparative study with FDG-PET

To compare L-3-[18F]-fluoro-a-methyltyrosine (FMT)-positron emission tomography (PET) and 2-[18F]-fluoro-2-deoxy-D-glucose (FDG)-PET in the differential diagnosis of maxillofacial tumors. This study included 36 patients (16 males, 20 females; 31-90 years old) with untreated malignant tumors (34 squamous cell carcinoma, one mucoepidermoid carcinoma, one rhabdomyosarcoma) and seven patients (five males, two females; 32-81 years old) with benign lesions. In all patients, both FMT-PET and FDG-PET were performed within two weeks before biopsy or treatment of the lesions. To evaluate the diagnostic usefulness of FMT-PET and FDG-PET, visual interpretation and semiquantitative analysis were performed. PET images were rated according to the contrast of tumor uptake as compared with background, and were statistically analyzed. As a semiquantitative analysis, standardized uptake values (SUV) of the primary tumors were measured, and the SUV data were analyzed using receiver operating characteristic (ROC) curves. The mean SUV of the malignant lesions were significantly higher than those of the benign lesions in both FMT-PET (2.62 +/- 1.58 vs. 1.20 +/- 0.30, p < 0.01) and FDG-PET (9.17 +/- 5.06 vs. 3.14 +/- 1.34, p < 0.01). A positive correlation (r = 0.567, p < 0.0001, n = 46) was noted between FMT and FDG. ROC analysis revealed that there was no statistically significant difference in SUVs between FMT and FDG for differentiating malignant tumors. In 27 of 36 patients, FMT-PET had better contrast of malignant tumor visualization to the surrounding normal structures by visual assessment (p < 0.005, binomial proportion test). Differential diagnosis of FMT-PET based on the uptake in maxillofacial tumors is equivalent to FDG-PET. However, the contrast of FMT uptake between maxillofacial tumors and the surrounding normal structures is higher than that of FDG, indicating the possibility of accurate diagnosis of maxillofacial tumors by FMT-PET.

In vivo imaging of estrogen receptor concentration in the endometrium and myometrium using FES PET — influence of menstrual cycle and endogenous estrogen level

The goals of this study were to measure estrogen receptor (ER) concentration in the endometrium and myometrium using 16alpha-[(18)F]fluoro-17beta-estradiol (FES) positron emission tomography (PET) and to investigate the relationship between changes in these parameters with the menstrual cycle and endogenous estrogen levels. Sixteen female healthy volunteers were included in this study. After blood sampling to measure endogenous estrogen level, FES PET image was acquired 60 min postinjection of FES. After whole-body imaging of FES PET, averaged standardized uptake values (SUVs) in the endometrium and myometrium were measured, and the relationship between FES uptake and menstrual cycle or endogenous estrogen level was evaluated. Endometrial SUV was significantly higher in the proliferative phase than in the secretory phase (6.03+/-1.05 vs. 3.97+/-1.29, P=.022). In contrast, there was no significant difference in myometrial SUV when the proliferative and secretory phases were compared (P=.23). Further, there was no correlation between SUV and endogenous estrogen level in the proliferative phase. The change of ER concentration relative to menstrual cycle as characterized by FES PET was consistent with those from previous reports that used an immunohistochemical technique. These data suggest that FES PET is a feasible, noninvasive method for characterizing changes in ER concentration.

Investigating the Existence of Quantum Metabolic Values in Non-Hodgkin’s Lymphoma by 2-Deoxy-2-[F-18]fluoro-d-glucose Positron Emission Tomography

To investigate the existence of quantum metabolic values in various subtypes of non-Hodgkin's lymphoma (NHL). Fifty-eight patients with newly diagnosed NHL and positron emission tomography (PET) performed within three months of biopsy were included. The standardized uptake value (SUV) from PET over the area of biopsy and serum glucose [Glc] were recorded. The group glucose sensitivity(G) for indolent and aggressive NHL was obtained by linear regression with ln(SUV) = G x ln[Glc] + C, where C is a constant for the group. Finally, the individual's glucose sensitivity (g) was obtained by g = {ln(SUV)-C}/ln[Glc], along with their means in various subtypes of NHL. To further investigate the influence of extreme [Glc] conditions, the SUVs corrected by the individually calculated g at various glucose levels, [Glc'] using SUV' =SUV x {[Glc']/[Glc]}(g), were compared to the original SUVs for both indolent and aggressive NHL. The averaged g (=G) for aggressive was significant different from that for indolent NHL (-0.94 +/- 0.51 vs. +0.13 +/- 0.10, respectively, p < 0.00005). There were significant differences in SUV for [Glc] < 80 or >110 mg/dl for both types of NHL. Unlike overlap among SUVs between NHL subtypes, the g value clearly categorized them into two distinct groups with positive (near-zero) and negative g values (around -1) for the indolent and aggressive NHLs, respectively. Distinct quantum metabolic values of -1 and 0 were noted in NHL. Aggressive NHL has a more negative value (or higher glucose sensitivity) than that of indolent and, thus, is more susceptible to extreme glucose variation.

Standardized Uptake Values of Normal Breast Tissue with 2-Deoxy-2-[F-18]Fluoro-d-glucose Positron Emission Tomography: Variations with Age, Breast Density, and Menopausal Status

This study was conducted to assess the effect of breast density, age, and menopausal status on the 2-deoxy-2-[F-18]fluoro-D: -glucose (FDG) uptake in normal breast tissue by quantitative standardized uptake values (SUV). A total of 96 patients (premenopausal 54; postmenopausal 42) with histologically proven unilateral breast cancer who underwent FDG-positron emission tomography (PET) scans for staging were included in this study. The median age was 52+/-11 years (range 32-79 years). Fifty-nine patients had grade III or IV mammographic density (dense breast), whereas 37 patients had grade I or II breast density (nondense) according to the ACR Lexicon criteria. In the present study, we analyzed maximum and average SUVs for contralateral normal breast. Maximum and average SUVs for normal dense breasts were 1.02+/-0.30 and 0.84+/-0.27, respectively. Similar values for the nondense breasts were 0.66+/-0.24 and 0.53+/-0.23, respectively. Both maximum and average SUVs of dense breasts were significantly higher than those of nondense breasts (p<0.001). There was no significant difference in SUVs of nipple in patients with dense and nondense breasts. There was no significant effect of age and menopausal status on SUVs of normal breast. However, there were trends of negative relationship, i.e., decreasing SUVs with increasing age. There was a significant difference in SUVs between the dense and nondense normal breast. However, the maximum SUVs in the dense breasts were well below the threshold of 2.5, a widely used cutoff value for malignancy. Menopausal status and age do not significantly affect the uptake of FDG.

Positron-emission tomography as a prognostic tool for early-stage lung cancer

Background Positron-emission tomography (PET) shows tissue metabolic activity in the form of the standard uptake value (SUV). This study examines the prognostic value of the SUV for early-stage lung cancer. Methods A retrospective review of 187 patients undergoing PET for potential lung cancer. Data collected included patient demographics, tumor pathology, and survival information. Data were correlated with PET results to determine if a prognostic relationship exists. Results The sensitivity and specificity of PET for detecting malignant lesions were 98% and 24%. Malignant lesions had a higher SUV than benign lesions (5.9 ± 6.2 versus 2.2 ± 1.8, P < .0001). The average SUV of well-differentiated tumors was 2.6 ± 3.1 versus 5.9 ± 5.5 for other tumors ( P = .010). There was a strong correlation between tumor stage and SUV (analysis of variance, P < .0001). There was no difference in tumor SUV for survivors versus nonsurvivors. Conclusions The SUV correlates with prognostic indicators, such as tumor stage and grade. The SUV alone was not an independent predictor of survival.

The Usefulness of Integrated PET/CT to Distinguish between Benignancy and Malignancy in Solitary Pulmonary Nodule

Background: Malignant pulmonary nodules account for about 30 to 40 percent of solitary pulmonary nodules (SPN). Therefore, tissue characterization of SPNs is very important. Recently, PET/CT has been widely used for tissue characterization, and has become of importance. The purpose of this study was to compare and to assess multiple factors in PET/CT comparing benign and malignant nodules. Materials and Method: Nineteen patients with SPN underwent PET/CT and biopsy. The difference of standardized uptake value 1 (SUV1), standardized uptake value 2 (SUV2) and retention index in PET/CT between malignancy and benignancy were compared by Levene's test. Result: There were twelve malignant and seven benign nodules. SUV1 and SUV2 were significantly different between malignant nodule and benign nodule (p=0.006 and 0.022), but retention index was not significantly different between malignant nodule and benign nodule (p=0.526). By receiver-operating-characteristic (ROC) analysis, the sensitivity was 66.7% and the specificity was 71.4% at a cut off value of 5.40 in SUV1. The sensitivity was 75% and the specificity was 71.4% at cut off value of 7.45 in SUV2. Conclusion: There was a statistically significant difference in SUV1 and SUV2 between benign and malignant nodules. However, the cut off value of SUV1 and SUV2 by receiver-operating-characteristic (ROC) analysis was 5.40 and 7.45 which is different from previous studies. Therefore, studies on a larger sample of patients are required for confirmation.

Correlative investigation of dynamic contrast CT and positron emission tomography with 18-fluorodeoxy glucose standardized uptake value in non-small cell lung cancer

目的 探讨非小细胞肺癌动态CT增强值与正电子发射计算机体层摄影(PET)中18氟-脱氧葡萄糖(18F-FDG)标准摄取值(SUV)的相关性.方法搜集行PET-CT和动态增强CT检查的28例非小细胞肺癌和13例良性肺结节病例,测量结节增强前后各时相的平均CT值、18F-FDG标准摄取值的最大值和平均值,计算结节增强峰值,用Pearson相关分析方法评价良恶性结节动态CT增强峰值和18F-FDG SUV的相关性.结果非小细胞肺癌和良性结节CT增强峰值[(35.09±11.41)、(26.92±19.98) HU]的差异无统计学意义(t=1.374,P=0.189),SUV最大值(7.23±4.38、2.97±2.80)差异有统计学意义(t=-3.972,P<0.001),SUV平均值差异有统计学意义(t=-4.061,P<0.001).非小细胞肺癌CT增强峰值[(35.09±11.41) HU]和18F-FDG SUV的平均值(4.93±3.53)及最大值(7.23±4.38)之间均无相关关系(r=-0.040,P=0.839及r=0.056,P=0.778).结论非小细胞肺癌动态CT增强值与FDG SUV之间无相关关系,FDG SUV可能不适用于非小细胞肺癌抗肿瘤血管生成治疗的疗效评价。

2-Deoxy-2-[F-18]fluoro-D-glucose-Positron Emission Tomography in Characterization of Solid Renal Masses

The present study was aimed to evaluate the ability of 2-deoxy-2-[F-18]fluoro-D -glucose (FDG)-positron emission tomography (PET) in characterization of solid renal masses visualized by computed tomography (CT)/magnetic resonance imaging (MRI) in patients with suspected or known malignancies. Twenty-eight solid renal masses (20 unilateral and four bilateral, Size ranges, 1.0-8.4 cm) were evaluated in 24 patients. The results were correlated with histopathology in 15 patients, and clinical follow-up and conventional imaging in all patients. Of the 28 solid renal masses, 10 were primary (nine malignant, one benign) and 18 were metastatic renal tumors. FDG-PET accurately depicted 23 of 27 (85%) malignant renal masses. Of the 10 primary renal tumors, FDG-PET was true positive in eight of nine (89%), true negative in one and false negative in one. The maximum and average standardized uptake values (SUVs) for FDG positive primary renal malignant tumors were 7.9 +/- 4.9 and 6.0 +/- 3.6, respectively. In addition to the characterization of primary tumors, FDG-PET was valuable in primary staging and altered treatment in 30% of patients (three of 10). Of the 18 metastatic renal masses, FDG-PET was positive in 15 (83%) masses. The maximum and average SUVs of metastatic renal masses were 6.1+/- 3.4 and 4.7+/- 2.8, respectively. There was no significant difference in maximum and average SUVs between primary and metastatic renal masses (p=0.3 and p=0.3). Despite the physiological excretion of FDG by the kidneys, FDG-PET can be employed effectively in characterization of solid renal masses in patients with suspected or known malignancies. We propose that FDG-PET could be useful as a complimentary modality to conventional imaging in these patients.

FDG-PET for staging of rhabdomyosarcoma

8545 Background: Complete staging of rhabdomyosarcoma is critical for delivery of appropriate therapy. Current diagnostic tools have known limitations. We have evaluated the role of 18F fluorodeoxyglucose positron emission tomography (PET) in the staging of patients with rhabdomyosarcoma. Methods: Since 1997, 60 patients with rhabdomyosarcoma underwent 159 PET scans. Of these, 21 patients with a median age of 11 years had a PET scan as part of their initial staging evaluation, before or within 13 days of initiation of therapy. Twelve patients had alveolar and 9 had embryonal histology. Primary sites included parameningeal (11), extremity (4), trunk (3), bladder/prostate (2), and head and neck (1). Results from CT, MRI, bone scan, and pathology within 1 month of the PET were compared. Results: A total of 83 sites were evaluated. All 21 patients had positive PET scans at the primary site. Twenty six PET positive sites at primary or nodal regions were biopsied and in all sites disease was confirmed. Standardized uptake value (SUV) for the primary site at the time of diagnosis ranged from 2.4 to 12.7 (mean 5.7). All SUVs prior to therapy were ≥4. There was no significant difference in SUV when evaluated by primary site or histology. PET showed involvement of regional lymph nodes in 12 patients. Five of the 12 patients underwent lymph node biopsy, all confirming involvement. In 3 of these cases, CT or MRI failed to detect the regional involvement identified on PET. At 11 sites, CT or MRI was equivocal for detection of regional or distant spread. In these cases, PET confirmed disease in one case and excluded disease in 10 cases. PET failed to capture sites of disease visualized by CT, MRI, or bone scan at 10 sites, including pelvic, paraaortic, mediastinal, cervical and retropharyngeal lymph nodes as well as vertebral bodies. When comparing PET to the final clinical determination of disease extent, PET was 83% sensitive and 97% specific. Conclusion: These preliminary data indicate that PET is a useful adjunct in the initial staging of rhabdomyosarcoma. In 3 of 21 cases (14%), therapy was altered because of nodal disease detected only on PET. A prospective study of PET for staging of rhabdomyosarcoma is warranted. No significant financial relationships to disclose.