Comparison of long-labeled pseudo-continuous arterial spin labeling (ASL) features between young and elderly adults: special reference to parameter selection.

BACKGROUND: The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations. PURPOSE: To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL. MATERIAL AND METHODS: The perfusion signal was simulated in four LDs and theoretical signal-to-noise ratio efficiency (SNReff) was calculated. In vivo studies were performed on a 3.0 T magnetic resonance imaging (MRI) scanner and 15 volunteers were categorized into either the young or elderly adult groups. We compared the differences in CBF values with or without ATT correction. RESULTS: Regarding signal simulation, perfusion signal increased with the length of LD. SNReff also improved with LD, but SNReff plateaued at an LD of 3.0 s. As for the in vivo study, SNR linearly increased along with the LD. The CBF differences with the correction of ATT were larger in the elderly adult group. This trend was most prominent in the longer ATT area in the occipital cortical region. CONCLUSION: A combination of imaging settings of LD = 3.5 s and PLD = 2.0 s were suggested as optimal imaging parameters for allowing acceptable CBF quantification and sufficient SNR in both young and elderly individuals.

Evaluation of staging and early response to chemotherapy with whole-body diffusion-weighted MRI in malignant lymphoma patients: A comparison with FDG-PET/CT.

BACKGROUND: To examine the utility of diffusion-weighted MRI (DW-MRI) for staging and early response to chemotherapy assessment in lymphoma patients as compared with fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). METHODS: Twenty-eight patients with histologically confirmed malignant lymphoma underwent both MRI and FDG-PET/CT before (pretreatment) and after two courses of chemotherapy (mid-treatment). Staging with MRI (DW-MRI alone and with T2-weighted images) and FDG-PET was compared visually, and the concordance rate (kappa value, κ) was calculated. To evaluate early response to chemotherapy, patients were divided into two groups, lesion-positive (LP) and lesion-negative (LN), based on a proposed original criterion. Progression-free survival (PFS) was compared between the groups using the Kaplan-Meier method. RESULTS: The stage diagnosed with DW-MRI alone and with FDG-PET/CT was concordant in 22 patients (κ = 0.71; P < 0.05), and by adding T2-weighted images, the number of concordant patients increased to 26 (κ = 0.90; P < 0.05). On mid-treatment imaging, 19 patients were diagnosed as LN from both modalities. PFS differed significantly between LP and LN on both DW-MRI (P = 0.0013) and FDG-PET/CT (P = 0.037). CONCLUSION: DW-MRI is a promising tool for staging and evaluation of early response to chemotherapy in patients with lymphoma.

Standardized uptake value differences between primary and metastatic lesions in ¹8F-FDG PET/CT of patients with lung cancer.

BACKGROUND: FDG-PET/CT is a robust tool for staging of lung cancer, but the differences in FDG uptake between primary and metastatic lesions have not yet been well described. PURPOSE: To define the potential range of standardized uptake value (SUV) differences between primary and metastatic lesions in lung cancer patients and to identify the factors responsible for these differences. MATERIAL AND METHODS: FDG-PET/CT images of 75 lung cancers with 296 metastases were analyzed retrospectively. Histological types, primary locations, and metastatic sites were recorded. The average and maximum SUV (SUVavg, SUVmax) of each primary tumor and metastasis were measured, and the ratio of metastatic SUVs to primary SUVs (M/Pavg, M/Pmax), its difference from 100% (diff-M/Pavg, diff-M/Pmax), the ratio of ROI area of metastatic to primary lesions (ROI-M/P), and its difference from 100% (diff-ROI-M/P) were calculated. RESULTS: M/Pavg was in the range of 35.9-224.6% (mean ± SD: 97.9% ± 35.9%), while M/Pmax was in the range of 24.8-286.7% (98.1% ± 45.3%). Furthermore, values were in the range of 50-200% for M/Pavg in 280/296 lesions (94.6%) and for M/Pmax in 255/296 lesions (86.1%). M/Pavg and M/Pmax showed significant linear correlations with ROI-M/P (r = 0.62, 0.64, respectively). Multivariate analysis showed that diff-ROI-M/P had the greatest effect on diff-M/Pavg and diff-M/Pmax. CONCLUSION: The SUVs of most metastatic lesions ranged from half to double those of primaries in lung cancer patients. When the SUV of a suspected metastasis is beyond the range of half to double that of the primary lung cancer, other non-metastatic lesions should be considered, while taking ROI size into account.

Serial changes of (18)F-FDG PET/CT findings in ischiopubic synchondrosis: comparison with contrast-enhanced MRI.

UNLABELLED: A 3 years old female patient underwent resection and chemotherapy for a yolk sac tumor of the retroperitoneum. Two years later, fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) showed high uptake in the right ischiopubic synchondrosis (IPS), which had a radiolucent structure on CT. The structure showed contrast enhancement on magnetic resonance imaging (MRI), which was a non-specific finding. Six weeks later, a follow-up (18)F-FDG PET/CT scan was performed which showed no abnormal uptake in the IPS. The disappearance of (18)F-FDG uptake preceded that of contrast enhancement on MRI, which was seen 7 months after the initial (18)F-FDG PET/CT scan. CONCLUSION: This is the first report showing serial changes of (18)F-FDG uptake in IPS, in comparison to MRI findings.

Imaging the early response to chemotherapy in advanced lung cancer with diffusion-weighted magnetic resonance imaging compared to fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography.

PURPOSE: To evaluate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) for assessment of the early response to chemotherapy and outcome in patients with advanced lung cancer through comparison with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT). MATERIALS AND METHODS: Twenty-eight lung cancer patients underwent DW-MRI, FDG-PET, and CT before and after one course of chemotherapy. Changes in the apparent diffusion coefficient (ΔADC), the mean standardized uptake value (ΔSUV), and the maximum diameter (ΔMD) were measured and compared. According to the response evaluation criteria, patients were divided into two groups, responders and nonresponders, and progression-free survival (PFS) and overall survival (OS) were estimated. RESULTS: The relationship between ΔADC and ΔSUV had the highest correlation coefficient. A cutoff value of ΔADC between responders and nonresponders was estimated as 21.5%. PFS and OS between responders and nonresponders were significantly different on DW-MRI (PFS, P = 0.012; OS, P = 0.006) and on FDG-PET (PFS, P = 0.017; OS, P = 0.036), but not on CT (PFS, P = 0.105; OS, P = 0.051). CONCLUSION: DW-MRI can be used to predict prognosis in patients with advanced lung cancer.

Prognostic value of dual-time-point 18F-fluorodeoxyglucose positron emission tomography in patients with pulmonary sarcoidosis.

BACKGROUND AND OBJECTIVE: The value of dual-time- point (18) F-FDG PET was investigated to predict the prognosis of patients with pulmonary sarcoidosis. METHODS: Twenty-one patients with pulmonary sarcoidosis underwent (18) F-FDG PET examinations at two time points: an early scan at 60min and a delayed scan at 180min after injection of (18) F-FDG. Standardized uptake values (SUVs) at the two time points and the retention index (RI-SUV) calculated from these were evaluated. To evaluate disease progression, all patients underwent chest CT 1year after (18) F-FDG PET. Using these results, the accuracy of (18) F-FDG PET parameters and (67) Ga uptake for predicting disease persistence were compared, and the correlations between those parameters and serum markers were assessed. RESULTS: RI-SUV was significantly higher in patients with increased or unchanged pulmonary lesions at follow-up CT (persistent group; 21.3±9.6%) than in patients with improved pulmonary lesions (improved group; -9.2±28.6%, P=0.0075). The diagnostic accuracy of RI-SUV in the persistent group was significantly greater than that of early SUV or (67) Ga uptake, and serum soluble IL-2 receptor showed a significant correlation with RI-SUV. CONCLUSIONS: RI-SUV showed better diagnostic accuracy compared with early SUV or (67) Ga uptake, in patients with persistent lung involvement at 1year. It may be a useful measure of persistent inflammation in patients with pulmonary sarcoidosis.

Differentiation of histological subtypes in lung cancer with 18F-FDG-PET 3-point imaging and kinetic analysis.

The purpose of this study was to evaluate differences in histological subtypes of lung cancer using (18)F-FDG-PET 3-point imaging and kinetic analysis. Subjects comprised 44 patients with histologically proven lung cancer (squamous cell carcinoma (SCC), n=18; well-differentiated adenocarcinoma (WDA), n=9; poorly/moderately differentiated adenocarcinoma (non-WDA), n=17) who underwent (18)F-FDG-PET/CT examinations at 1, 2 h and 3 h after injection of 185 MBq of (18)F-FDG, approximately. Mean standardized uptake value (SUV) in each lesion was measured at each time point and the increase rate of SUV (IR_SUV) was calculated. SUV and IR_SUV were compared among the 3 groups. In addition, to estimate differences in kinetic parameters for each group, kinetic analysis based on a 3-compartment model was performed. Our results showed SUV differed significantly at every time point among the 3 groups. IR_SUV between 2 and 3 h post-injection (IR_SUV (2-3)) differed significantly among the 3 groups, while both IR_SUV(1-3) and IR_SUV(1-2) were significantly higher in SCC than in WDA. In kinetic analyses, both K1 and k3 showed significant differences among the 3 groups, with highest values in SCC and lowest in WDA. In conclusion, (18)F-FDG-PET 3-point imaging and kinetic analysis enabled the differentiation of histological subtypes in lung cancer, arising from differences in glucose transporter density and enzymatic activity of hexokinase.

The effectiveness of 18F-FDG PET/CT combined with STIR MRI for diagnosing nodal involvement in the thorax.

UNLABELLED: The purpose of this study was to compare the efficacy of short-tau inversion-recovery (STIR) MRI and 18F-FDG PET/CT for the detection of metastasis in mediastinal and hilar lymph nodes in patients with lung cancer. METHODS: Ninety-three patients with known or suspected lung cancer with mediastinal and hilar lymph node swelling underwent STIR MRI and 18F-FDG PET/CT examinations. STIR MRI scans were obtained with a 2% copper sulfate phantom placed along the back of each patient, with the lymph node-to-phantom ratio calculated for quantitative analysis. For qualitative analysis, the results of all STIR MRI scans were evaluated using a 5-point visual scoring system. To evaluate the diagnostic capabilities of STIR MRI and 18F-FDG PET/CT, we used receiver-operating-characteristic curve analysis to determine the optimal thresholds for the lymph node-to-phantom ratio, visual score, and maximal standardized uptake value. Further, the capability of each to determine N-stage was compared in each patient using the McNemar test. RESULTS: A total of 137 lymph nodes (82 malignant lesions, 55 benign lesions) were analyzed. When optimal threshold values were adopted, the quantitative and qualitative sensitivity, specificity, and accuracy of STIR MRI were not significantly different from those of 18F-FDG PET/CT. However, 18F-FDG PET/CT in combination with qualitative STIR MRI analysis had a significantly higher capability to detect nodal involvement on an individual-patient basis (96.9% specificity, 90.3% accuracy) than did 18F-FDG PET/CT alone (65.6% specificity, 81.7% accuracy). CONCLUSION: We found that the diagnostic capability of STIR MRI was not significantly different from that of 18F-FDG PET/CT. However, when those methods were combined, the diagnostic capability for N-staging was significantly improved.

Usefulness of 18F-fluorodeoxyglucose positron emission tomography for diagnosing disease activity and monitoring therapeutic response in patients with pulmonary mycobacteriosis.

PURPOSE: To evaluate the usefulness of (18)F-FDG PET in the imaging of pulmonary lesions related to disease activity and in monitoring responses to treatment in patients with pulmonary mycobacteriosis (PM). MATERIALS AND METHODS: We used high-resolution computed tomography (HRCT) and (18)F-FDG PET to evaluate 47 consecutive untreated patients with PM, 25 with tuberculosis (TB) and 22 with Mycobacterium avium-intracellulare complex (MAC), who presented with small peripheral pulmonary nodules

Dual-time-point 18F-FDG PET imaging for diagnosis of disease type and disease activity in patients with idiopathic interstitial pneumonia.

PURPOSE: Individual clinical courses of idiopathic interstitial pneumonia (IIP) are variable and difficult to predict because the pathology and disease activity are contingent, and chest computed tomography (CT) provides little information about disease activity. In this study, we applied dual-time-point [(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET), commonly used for diagnosis of malignant tumours, to the differential diagnosis and prediction of disease progression in IIP patients. METHODS: Fifty patients with IIP, including idiopathic pulmonary fibrosis (IPF, n = 21), non-specific interstitial pneumonia (NSIP, n = 18) and cryptogenic organizing pneumonia (COP, n = 11), underwent (18)F-FDG PET examinations at two time points: scan 1 at 60 min (early imaging) and scan 2 at 180 min (delayed imaging) after (18)F-FDG injection. The standardized uptake values (SUV) at the two points and the retention index (RI-SUV) calculated from them were evaluated and compared with chest CT findings, disease progression and disease types. To evaluate short-term disease progression, all patients were examined by pulmonary function test every 3 months for 1 year after (18)F-FDG PET scanning. RESULTS: The early SUV for COP (2.47 +/- 0.74) was significantly higher than that for IPF (0.99 +/- 0.29, p = 0.0002) or NSIP (1.22 +/- 0.44, p= 0.0025). When an early SUV cut-off value of 1.5 and greater was used to distinguish COP from IPF and NSIP, the sensitivity, specificity and accuracy were 90.9, 94.3 and 93.5%, respectively. The RI-SUV for IPF and NSIP lesions was significantly greater in patients with deteriorated pulmonary function after 1 year of follow-up (progressive group, 13.0 +/- 8.9%) than in cases without deterioration during the 1-year observation period (stable group, -16.8 +/- 5.9%, p < 0.0001). However, the early SUV for all IIP types provided no additional information of disease progression. When an RI-SUV cut-off value of 0% and greater was used to distinguish progressive IIPs from stable IIPs, the sensitivity, specificity and accuracy were 95.5, 100 and 97.8%, respectively. CONCLUSION: Early SUV and RI-SUV obtained from dual-time-point (18)F-FDG PET are useful parameters for the differential diagnosis and prediction of disease progression in patients with IIP.

Comparison of 18F-FDG PET and MRI in assessment of uterine smooth muscle tumors.

UNLABELLED: The purpose of this study was to prospectively determine whether combined MRI and (18)F-FDG PET is more accurate than MRI in assessing nonbenign uterine smooth muscle tumors (USMTs). METHODS: Seventy patients (mean age, 49+/-10 y; range, 28-77 y) suspected of having nonbenign USMTs underwent both MRI and (18)F-FDG PET before surgery. Results were evaluated using receiver-operating-characteristic (ROC) analyses and the Cochran Q test. RESULTS: The area under the ROC curve for MRI with (18)F-FDG PET was significantly higher than that for MRI (0.97 vs. 0.89, P<0.05). Although multiple comparisons using the Cochran Q test were not significant, the sensitivity, specificity, and accuracy for MRI with (18)F-FDG PET with probable nonbenign USMT cases considered to be positive were higher than those for MRI (93.3% vs. 73.3%; 92.7% vs. 85.5%; and 92.9% vs. 82.9%, respectively). CONCLUSION: MRI with (18)F-FDG PET is useful in assessing nonbenign USMTs, as compared with MRI.

Reproducibility of semi-quantitative parameters in FDG-PET using two different PET scanners: influence of attenuation correction method and examination interval.

PURPOSE: The aim of this study is to evaluate the reproducibility of semi-quantitative parameters obtained from two 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) studies using two different PET scanners. METHODS: Forty-five patients underwent FDG-PET examination with two different PET scanners on separate days. Two PET images with different attenuation correction method were generated in each patient, and three regions of interest (ROIs) were placed on the lung tumor and normal organs (mediastinum and liver) in each image. Mean and maximum standardized uptake values (SUVs), tumor-to-mediastinum and tumor-to-liver ratios (T/M and T/L), and the percentage difference in parameters between two PET images (% Diff.) were compared. RESULTS: All measured values except maximum SUV in the liver and tumor-related parameters (SUV in lung tumor, T/M, T/L) showed no significant difference between two PET images. CONCLUSION: The mean measured values showed high reproducibility and demonstrate that follow-up study or measurement of tumor response to anticancer drugs can be undertaken by FDG-PET examination without specifying the particular type of PET scanner.

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

UNLABELLED: 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. METHODS: 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. RESULTS: 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). CONCLUSION: This preliminary study revealed that ACE PET is a promising tracer for the grading of brain glioma.

18F-FDG PET of common enhancing malignant brain tumors.

OBJECTIVE: The purpose of our study was to determine whether (18)F-FDG PET can be used to differentiate among common enhancing brain tumors such as lymphoma, high-grade glioma, and metastatic brain tumor. MATERIALS AND METHODS: We evaluated 34 patients with an enhancing brain tumor on MRI, including seven lymphomas, nine high-grade gliomas, and 18 metastatic tumors. All patients also underwent FDG PET. For PET image analysis, regions of interest were placed over the tumor (T), contralateral cortex (C), and white matter (WM). Average and maximum pixel values were determined at each site. On the basis of these measurements, average and maximum standard uptake values (SUV(avg) and SUV(max)) were calculated, along with activity ratios (T/C(avg), T/WM(avg), T/WM(max), and T/C(max)), and comparisons among lesions were then made. RESULTS: All parameters were significantly higher for lymphoma than for other tumors (p < 0.01). High-grade gliomas showed significantly higher SUV(avg) and SUV(max) than metastatic tumors (p < 0.05). Other parameters did not differ between lesion types. SUV(max) was the most accurate parameter for distinguishing lymphomas. Using an SUV(max) of 15.0 as a cutoff for diagnosing CNS lymphoma, only one high-grade glioma was found as a false-positive (SUV(max), 18.8). CONCLUSION: FDG PET may be useful for differentiating common enhancing malignant brain tumors, particularly lymphoma versus high-grade glioma and metastatic tumor. FDG PET can provide useful information for distinguishing between lymphoma and other malignant enhancing brain tumors and is recommended when differential diagnoses are difficult to narrow using MRI alone.

Distinctive FDG and FES accumulation pattern of two tamoxifen-treated patients with endometrial hyperplasia.

16alpha-[(18)F]Fluoro-17beta-estradiol (FES) is an estrogen receptor (ER) ligand used for the detection of ER-positive malignant tumors such as breast cancer. We recently reported the feasibility of combined FES-and 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) scans for the differential diagnosis of endometrial tumors. ER expression measured by FES-PET was preserved in endometrial hyperplasia, whereas ERs were assumed to be reduced in endometrial carcinoma with accelerated glucose metabolism measured by FDG-PET. We report two postmenopausal patients under suspicion of endometrial carcinoma on the basis of cytology and/or magnetic resonance imaging (MRI), who were on tamoxifen treatment since undergoing surgery for breast cancer. Pelvic MRI suggested endometrial carcinomas, whereas FDG-and FES-PET showed no abnormal tracer accumulation. A postoperative histopathologic examination revealed that the lesions were endometrial hyperplasias with no malignant findings. FES-PET enables us to evaluate the ERalpha expression of endometrium noninvasively, whereas the evaluation of ER expression using FES-PET requires careful attention regarding the influence of hormonal therapy because tamoxifen greatly affects FES accumulation of even endometrial hyperplasia, which should be an FES-avid lesion.

The present state of radiation exposure from pediatric CT examinations in Japan-what do we have to do?

The use of computed tomography (CT) has increased dramatically over the past several decades and has resulted in a concurrent increase in medical exposure to ionizing radiation. Several recent studies have examined the link between medical radiation and the risk of cancer, especially in children. The cancer risk associated medical exposure has not been definitively confirmed. However, we have to reduce unwarranted medical radiation exposure in pediatric patients. Justification and optimization are of great importance in order to minimize these risks, and the standardization of CT usage is essential. However, in Japan no clinical guidelines for the use of CT have been commonly agreed upon, especially in children. Furthermore, the CT-associated radiation exposure in Japan varies widely among the different facilities. Further studies based on a nationwide survey in Japan will be required in order to establish simple and useful clinical guidelines.

Evaluation of respiratory chain failure in mitochondrial cardiomyopathy by assessments of 99mTc-MIBI washout and 123I-BMIPP/99mTc-MIBI mismatch.

Cardiomyopathy is one of the main features that determines prognosis in patients with mitochondrial encephalomyopathy. We investigated respiratory chain failure using 99mTc-MIBI- and 123I-BMIPP-SPECT in vivo in five patients with mitochondrial cardiomyopathty. With the lowering of cardiac function, the 99mTc-MIBI-washout rate (WOR) increased, and the 99mTc-MIBI-uptake decreased, conversely. In patients who showed severe cardiac involvement, 99mTc-MIBI-uptake was markedly reduced, and by contrast, 123I-BMIPP-uptake increased (123I-BMIPP/99mTc-MIBI mismatch). There were significant correlations between the WOR on 99mTc-MIBI-SPECT and interventricular septal thickness (IVST) on echocardiography and between WOR and left ventricular ejection fraction (LVEF) on 99mTc-MIBI-SPECT. The increased WOR and decreased uptake of 99mTc-MIBI were reflected by the lowered mitochondrial membrane potential created by mitochondrial respiratory chain whereas 123I-BMIPP/99mTc-MIBI mismatch may be created by the enhanced triglyceride-pool. These nuclear medicine techniques are the potential tools to evaluate the energy state in mitochondrial cardiomyopathy.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

A 18F-FDG-positive, 67Ga-negative, and transferrin receptor expression-negative patient with diffuse large B-cell lymphoma.

We recently experienced a case with uveitis suffering from fever of unknown origin suspected of being caused by sarcoidosis. Chest computed tomography showed right supraclavicular, bilateral mediastinal, and right hilar lymphadenopathy, and intensive abnormal uptake of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) was observed on positron emission tomography with 18F-FDG (FDG-PET). On the other hand, 67Ga scintigraphy showed almost no abnormal findings. Histopathological examination revealed the lesion to be a diffuse large B-cell lymphoma (DLBCL), namely, an aggressive non-Hodgkin lymphoma from a right supraclavicular lymph node biopsy specimen. Additional immunohistochemical analysis showed the negative expression of transferrin receptor (TfR) on the formalin-fixed paraffin-embedded specimen. Although DLBCL is generally considered to be a 67Ga-avid tumor, it does not always have a large number of TfRs and that leads to a discrepancy between the 67Ga scintigraphy and FDG-PET findings. FDG-PET should be more appropriate for the initial staging of DLBCL than 67Ga scintigraphy, whereas 67Ga scintigraphy might be able to provide additional information including prognostic factors and to support strategies that target TfR for cancer therapy.