The closed-loop control method based on dual-port adaptive internal model control for fine image stabilization of space telescopes.

In view of the complex working environment of space astronomical telescopes, the influence of various disturbance sources on the imaging quality cannot be ignored. This paper focuses on compensating for the space telescope line-of-sight (LOS) deviation and suppressing the low-frequency disturbance problem in astronomical observation. A closed-loop control method based on dual-port adaptive internal model control (AIMC) for the fine image stabilization system (FISS) was proposed. To be specific, the fine guidance sensor (FGS) as the high-precision detection unit of the FISS calculates the telescope LOS deviation and sends it to the controller unit in real time. The controller unit drives the large-aperture fast steering mirror (FSM), which performs high-precision two-dimensional rotation to compensate for the telescope LOS deviation, according to the dual-port AIMC control algorithm. Moreover, the dual-port AIMC control method adds an AIMC loop on the basis of the feedback loop and adjusts the filter parameters adaptively according to the target angular velocity of the FSM, achieving higher disturbance suppression capability. The experimental results verify that the control method proposed can effectively compensate for the LOS deviation and suppress the composite frequency disturbance. In the 0-8 Hz frequency band, the power spectral density integral values of the star centroid deviation in the X and Y directions of the FGS are, respectively, suppressed by 97.38% and 98.38%.

Sunglint reflection facilitates performance of spaceborne UV sensor in oil spill detection.

Ultraviolet Imager (UVI) onboard Haiyang-1C/D (HY-1C/D) satellites has been providing ultraviolet (UV) data to detect marine oil spills since 2018. Although the scale effect of UV remote sensing has been preliminarily interpreted, the application characteristics of spaceborne UV sensors with medium spatial resolution in oil spill detection deserve further investigation, especially the role of sunglint in the process of detection. In this study, the performance of the UVI is thoroughly assessed by the following aspects: image features of oils under sunglint, sunglint requirement for spaceborne UV detection of oils, and the stability of the UVI signal. The results indicate that in UVI images, it is sunglint reflection that determines the image features of spilled oils, and the appearance of sunglint can strengthen the contrast between oils and seawater. Besides, the required sunglint strength in spaceborne UV detection has been deduced to be 10-3 - 10-4 sr-1, which is higher than that in the VNIR wavelengths. Moreover, uncertainties in the UVI signal can meet the demand to discriminate between oils and seawater. The above results can confirm the capability of the UVI and the critical role of sunglint in spaceborne UV detection of marine oil spills, and provide new reference for spaceborne UV remote sensing.

Specular Surface Shape Measurement with Orthogonal Dual-Frequency Fourier Transform Deflectometry.

Three-dimensional (3D) shape measurement for specular surfaces is becoming increasingly important in various applications. A novel orthogonal dual-frequency fringe is proposed in the specular surface shape measurement to overcome the phase jumping and discontinuities in spatial phase unwrapping. The fringe recalibrated high-accuracy phase information from its high-frequency fringe component with low-ambiguity phase information from its low-frequency fringe component. An improved Fourier transform deflectometry method based on the orthogonal dual-frequency fringe is proposed to measure 3D specular surface shapes. Simulation results showed that the orthogonal dual-frequency Fourier transform deflectometry (ODD) method could precisely reconstruct flat surfaces with an error of 2.16 nm rms, and concave surfaces with an error of 1.86 µm rms. Experimental results showed that the reconstructed shapes of both the flat mirror and the concave mirror measured by the ODD measurement system were highly comparable to those obtained by the phase-measuring deflectometry (PMD) method. This new fringe provides a distinctive approach to structured pattern construction and reduces the phase unwrapping ambiguities in specular surface shape measurement. The ODD method can achieve accurate 3D shape measurement for specular surfaces by sampling only one fringe, providing a possible basis for future real-time measurement of specular surfaces.

Construction of the Guide Star Catalog for Double Fine Guidance Sensors Based on SSBK Clustering.

In the Chinese Survey Space Telescope (CSST), the Fine Guidance Sensor (FGS) is required to provide high-precision attitude information of the space telescope. The fine star guide catalog is an essential part of the FGS. It is not only the basis for star identification and attitude determination but also the key to determining the absolute attitude of the space telescope. However, the capacity and uniformity of the fine guide star catalog will affect the performance of the FGS. To build a guide star catalog with uniform distribution of guide stars and catalog capacity that is as small as possible, and to effectively improve the speed of star identification and the accuracy of attitude determination, the spherical spiral binary K-means clustering algorithm (SSBK) is proposed. Based on the selection criteria, firstly, the spherical spiral reference point method is used for global uniform division, and then, the K-means clustering algorithm in machine learning is introduced to divide the stars into several disjoint subsets through the use of angular distance and dichotomy so that the guide stars are uniformly distributed. We assume that the field of view (FOV) is 0.2° × 0.2°, the magnitude range is 9∼15 mag, and the threshold for the number of stars (NOS) in the FOV is 9. The simulation shows that compared with the magnitude filtering method (MFM) and the spherical spiral reference point brightness optimization algorithm (SSRP), the guide star catalog based on the SSBK algorithm has the lowest standard deviation of the NOS in the FOV, and the probability of 5∼15 stars is the highest (over 99.4%), which can ensure a higher identification probability and attitude determination accuracy.

HY-1C ultraviolet imager captures algae blooms floating on water surface.

Some species of algae such as cyanobacteria can vertically migrate through water during a day, which is a notable floating feature of harmful algae blooms. To date, this process has been observed and quantified using visible and near-infrared (VNIR) bands from spaceborne sensors with high temporal resolution (i.e., Geostationary Ocean Color Imager; GOCI). In this study, we conducted an in-situ measurement at Taihu Lake in China to investigate the ultraviolet (UV) reflection spectra of floating cyanobacteria blooms, and identified that they have significant UV reflection features (higher than that of background water) associated with their floating status. This has been demonstrated using spaceborne UV images at both 355 and 385 nm from the Ultraviolet Imager (UVI) onboard Haiyang-1C (HY-1C) of China. Compared with synchronous optical images from the Chinese Ocean Color and Temperature Scanner (COCTS), we found that UVI has a special ability to distinguish cyanobacteria floating on water surface. Additionally, the intensity of the UV signals obtained is positively correlated with the cyanobacterial equivalent density. Ultraviolet remote sensing, therefore, can work as a new approach for the detection of harmful algae blooms and help determine the floating status of them, which deserves further research.

Adaptive compound control based on generalized Bouc-Wen inverse hysteresis modeling in piezoelectric actuators.

This paper focuses on the study of the dynamic hysteresis compensation and control of piezoelectric actuators so as to improve the swing accuracy of the piezoelectric fast steering mirror mechanism in the photoelectric compound-axis control system. Moreover, in view of the rate dependence and asymmetry of piezoelectric hysteresis, and the complex inversion process of the generalized Bouc-Wen hysteresis model, the Hammerstein dynamic inverse hysteresis model of the piezoelectric actuator is established. To be specific, the static nonlinearity and rate dependence of the piezoelectric inverse hysteresis are represented by the generalized Bouc-Wen inverse model and the auto-regressive exogenous model, respectively, and the parameters of the model are identified by the adaptive beetle swarm optimization algorithm. In the process of the open-loop feedforward compensation, the dynamic positioning accuracy of the piezoelectric actuator is greatly affected by various disturbances and the uncertainty of the hysteresis compensation model. In this context, a compound control strategy that combines the feedforward compensation with the single-neuron adaptive proportion-integration-differentiation control is proposed based on the Hammerstein dynamic inverse hysteresis model of the piezoelectric actuator. The experimental results verify the effectiveness and superiority of the proposed control strategy.

Ultraviolet remote sensing of marine oil spills: a new approach of Haiyang-1C satellite.

Haiyang-1C (HY-1C) is the first operational ocean color satellite of China, which is intended to obtain daily global ocean color data. The Ultraviolet Imager (UVI) onboard provides a potential novel detector for the detection of marine oil spills. Although airborne UV sensors have shown great efficiency for the detection of spilled oils, the capability of spaceborne UV sensor is not yet clear. In this study, we designed a ground-based experiment to interpret the UV characteristics of various weathered oils, and found that very thin oil films are quite sensitive to the UV radiation due to the surface interference light. Moreover, by comparing spaceborne and airborne UV images of spilled oils collected from HY-1C UVI and AVIRIS, the scale effect of ultraviolet remote sensing has been interpreted clearly. The interference light and sunglint reflection play different roles in the imaging process of spilled oils, leading them to appear radical different features (brighter or darker than the background oil-free seawater) in ground, airborne and spaceborne observation, which deserves further research. Ultraviolet remote sensing, therefore, can work as a new approach and improve the detection and monitoring of marine oil spills.

[Experimental Methods and Result Analysis of a Variety of Spectral Reflectance Properties of the Thin Oil Film].

In order to analysis the oil spill situation based on the obtained data in airborne aerial work, it's needed to get the spectral reflectance characteristics of the oil film of different oils and thickness as support and to select the appropriate operating band. An experiment is set up to measure the reflectance spectroscopy from ultraviolet to near-infrared for the film of five target samples, which means petrol, diesel, lubricating oil, kerosene and fossil, using spectral measurement device. The result is compared with the reflectance spectra of water in the same experimental environment, which shows that the spectral reflection characteristics of the oil film are related to the thickness and the type of the oil film. In case of the same thickness, the spectral reflectance curve of different types of film is far different, and for the same type of film, the spectral reflectance curve changes accordingly with the change of film thickness, therefore in terms of the single film, different film thickness can be distinguished by reflectance curves. It also shows that in terms of the same film thickness, the reflectance of diesel, kerosene, lubricants reaches peak around 380 nm wavelength, obviously different from the reflectance of water, and that the reflectance of crude oil is far less than that of water in more than 340 nm wavelength, and the obtained reflection spectrum can be used to distinguish between different types of oil film to some extent. The experiment covers main types of spilled oil, with data comprehensively covering commonly used detect spectral bands, and quantitative description of the spectral reflectance properties of film. It provides comprehensive theoretical and data support for the selection of airborne oil spill detection working band and the detection and analysis of water-surface oil spill.

[Study on in-orbit Vis/SWIR relative calibration monitoring system with high stability].

The present paper studied the in-orbit relative calibration monitoring system with high stability for onboard remote sensing calibration. The realizing principle and the critical technologies are described in detail. The calibration detector assembly with high stability was developed based on both visual (Vis) and shortwave infrared (SWIR) trap structure. Vis and SWIR photodetectors with high sensitivity were chosen to realize the photoelectric conversion. On the one hand, the detectors worked in the zero-bias photovoltaic mode with better linearity and lower dark current. On the other hand, the critical parameters of the analog operational amplifier circuit and data acquisition circuit were designed so that the trap-structure detector assembly could work properly. Thus the relative calibration monitoring system with high stability for measurement of spaceborne calibration radiance source was realized. The experiments were carried out using the laboratory integrating spheres and the standard lamps provided by the national measurement institution. The results showed that the relative standard deviation of the digital numbers that the system acquired reached to 0.030%-0.046% (Vis) and 0.040%-0.059% (SWIR). It was proved that the accuracy and the stability of the monitoring system could meet the in-orbit calibration system requirement and it could serve as a good solution for in-orbit relative calibration of remote sensor in the future.

Does the novel integrated PET/MRI offer the same diagnostic performance as PET/CT for oncological indications?

BACKGROUND: We compared PET/MRI with PET/CT in terms of lesion detection and quantitative measurement to verify the feasibility of the novel integrated imaging modality for oncological applications. METHODOLOGY/PRINCIPAL FINDINGS: In total, 285 patients referred to our PET/CT center for oncological indications voluntarily participated in this same-day PET/CT and PET/MRI comparative study. PET/CT images were acquired and reconstructed following routine protocols, and then PET/MRI was performed at a mean time interval of 28±11 min (range 15-45 min). PET/MRI covered the body trunk with a sequence combination of transverse T1WI 3D-volumetric interpolated breath-hold, T2WI turbo spin echo with fat saturation, diffusion-weighted imaging with double b values (50 and 800 s/mm2), and simultaneous PET acquisition over 45 min/5 bed positions. The maximum standardized uptake value (SUVmax) was assessed by manually drawn regions of interest over fluorodeoxyglucose-positive lesions. Among 285 cases, 57 showed no abnormalities, and 368 lesions (278 malignant, 68 benign and 22 undetermined) were detected in 228 patients. When stand-alone modalities were evaluated, PET revealed 31 and 12 lesions missed by CT and MRI, respectively, and CT and MRI revealed 38 and 61 more lesions, respectively, than PET. Compared to CT, MRI detected 40 more lesions and missed 8. In the integrated mode, PET/CT correctly detected 6 lesions misdiagnosed by PET/MRI, but was false-negative in 30 cases that were detected by PET/MRI. The overall diagnosis did not differ between integrated PET/MRI and PET/CT. SUVmax for lesions were slightly higher from PET/MRI than PET/CT but correlated well (ρ = 0.85-0.91). CONCLUSIONS/SIGNIFICANCE: The novel integrated PET/MRI performed comparatively to PET/CT in lesion detection and quantitative measurements. PET from either scanner modality offered almost the same information despite differences in hardware. Further study is needed to explore features of integrated PET/MRI not addressed in this study.

[Validation of standardized uptake values for ¹8F-FDG in normal organs: comparison of whole-body PET/CT and PET/MRI].

OBJECTIVE: To validate whether PET/MR could provide a semi-quantitative measurement (SUV(max)) comparable to that produced by PET/CT in normal organs. METHODS: 277 subjects underwent an ordinary ¹8F-FDG PET/CT followed by a PET/MR scan with a 25-45 min interval. Region of interest (ROIs) were drawn in 4 reference normal organs/tissues in both MRAC-PET and CTAC-PET images and the liver and erector spinae in the dual-time point PET/CT images. RESULTS: 259 malignant and 21 benign lesions, pathologically confirmed, were detected in the 220 subjects. SUV(max) derived from PET/CT (SUV(max)-CT) and PET/MR (SUV(max)-MRI) was highly correlated over the reference organ ROIs (r = 0.62-0.73), except lung (r = 0.44). The SUV(max)-MRI was significantly lower than the respective SUV(max)-CT in all 4 organs and after delay-correction in liver and muscle. CONCLUSION: The results indicate that PET/MR can provide reliable measurement in physiological organs.

Neovascularization in the carotid atherosclerotic plaque is not associated with inflammatory cell aggregation.

BACKGROUND: Monocytes and macrophages in atherosclerotic plaque lead to plaque instability. The aim of the study was to determine if plaque neovascularization led to inflammation. METHODS: Patients were consecutively enrolled if their carotid intimal media thickness was > 2 mm, as revealed by duplex ultrasound. The patients then underwent dynamic contrast enhanced magnetic resonance imaging (DCE MRI) and fluorine-18 fluorodeoxyglucose ((18)F-FDG) positron emission tomography combined with computed tomography (PET CT). A target to background ratio (TBR) of ≥ 1.25 or < 1.25 served as the cutoff point for the presence and absence of inflammation, respectively. RESULTS: Twenty-six patients underwent bilateral carotid DCE MRI and 24 patients also underwent PET CT. One hundred and fifty-five plaques were evaluated by both DCE MRI and PET CT. There was no significant difference in plaque morphology between the TBR ≥ 1.25 (n = 61) and TBR < 1.25 (n = 94) groups. No significant differences were found in plasma volume and transfer constant between the TBR ≥ 1.25 and TBR < 1.25 groups. CONCLUSION: Our study did not find a significant correlation between plaque neovascularization and the aggregation of inflammatory cells.

[Evaluation of carotid artery plaque stability with ¹8F-FDG PET/CT and contrast-enhanced ultrasonography].

OBJECTIVE: To assess the value of contrast-enhanced ultrasonography (CEUS) and fluorodeoxyglucose positron emission tomography-computed tomography (¹8F-FDG PET/CT) in evaluating the stability of carotid atherosclerosis. METHODS: Seventeen patients with 21 carotid artery plaques received examinations with CEUS. According to the nature of the plaques, the patients were divided into soft and mixed plaque group and hard and calcified plaque group. The maximal enhancement intensity of the plaques (I(MAX)) and maximal plaque density (D(MAX)) were measured to quantify the neovasculature. The patients also underwent concurrent ¹8F-FDG PET/CT, and ¹8F-FDG uptake was quantified by the mean standard uptake values (SUV(mean)), an index reflecting the inflammatory activity in the plaque. The findings in CEUS and PET/CT were comparatively analyzed for these cases. RESULTS: The D(MAX) of the plaque in soft and mixed plaque group was significantly greater than that in hard and calcified plaque group (4.26±3.65 vs 1.41±1.47, P<0.05); the I(MAX) was also greater in the former group, but this difference was not statistically significant (26.83±19.61 vs 24.73±29.85, P=0.869). The soft and mixed plaques tended to have higher SUVmean than the hard and calcified plaques (1.70±0.45 vs 1.47±0.12, P=0.099). The values of I(MAX) and D(MAX) were not found to correlate to SUV(mean) in these patients. CONCLUSION: CEUS can sensitively show the status of neovascularization within the carotid atherosclerosis plaques, and PET/CT reflects the inflammatory activity in the plaques. The combination of these two imaging modalities allows the evaluation of plaque stability in terms of neoangiogenesis and inflammatory activity.

Comparison of diffusion-weighted MRI with 18F-fluorodeoxyglucose-positron emission tomography/CT and electroencephalography in sporadic Creutzfeldt-Jakob disease.

18F-fluorodeoxyglucose-positron emission tomography/CT (18F-FDG PET/CT) scanning may be a useful tool for early diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD), as it may reveal lowered cellular glucose transport and metabolism in the cortex, cerebellum and basal ganglia. The aim of the present study was to compare the findings from PET/CT, MRI and electroencephalography (EEG) for patients with sCJD, to explore whether typical sites or reliable patterns of regional metabolic change could be found and to evaluate the results of diagnostic imaging in the light of clinical symptomatology. Five patients with biopsy-confirmed sCJD and nine with probable sCJD (aged 36-68 years) were evaluated using PET/CT, diffusion-weighted (DW)-MRI and EEG. In 13 of the 14 patients (92.86%), PET/CT imaging detected extra regions with abnormalities in addition to the hyperintense areas shown with DW-MRI. Two patients with no abnormal DW-MRI findings in the basal ganglia had bilateral extrapyramidal signs accompanied by basal ganglia hypometabolism on PET. Eight patients (57.14%) had decreased FDG uptake in the thalamic nuclei on PET scans; however, DW-MRI did not identify corresponding hyperintense changes in the thalamic nuclei. In 11 patients (78.57%), DW-MRI revealed more regions with abnormalities than EEG, and 10 patients (71.43%) had DW-MRI abnormalities in the thalamic nuclei and basal ganglia that EEG was unable to detect. There was a high level of correspondence among the PET/CT, DW-MRI and EEG results, with PET revealing more abnormal regions than the other imaging modalities. In the absence of neuropathological findings, FDG-PET could improve the accuracy of sCJD diagnosis when combined with DW-MRI and EEG, particularly for differentiating sCJD from paraneoplastic syndromes. Our results suggest that PET/CT is able to detect sCJD at an earlier stage and with greater sensitivity than DW-MRI.

Can multimodality imaging using 18F-FDG/18F-FLT PET/CT benefit the diagnosis and management of patients with pulmonary lesions?

PURPOSE: Dual-tracer, (18)F-fluorodeoxyglucose and (18)F-fluorodeoxythymidine ((18)F-FDG/(18)F-FLT), dual-modality (positron emission tomography and computed tomography, PET/CT) imaging was used in a clinical trial on differentiation of pulmonary nodules. The aims of this trial were to investigate if multimodality imaging is of advantage and to what extent it could benefit the patients in real clinical settings. METHODS: Seventy-three subjects in whom it was difficult to establish the diagnosis and determine management of their pulmonary lesions were prospectively enrolled in this clinical trial. All subjects underwent (18)F-FDG and (18)F-FLT PET/CT imaging sequentially. The images were interpreted with different strategies as either individual or combined modalities. The pathological or clinical evidence during a follow-up period of more than 22 months served as the standard of truth. The diagnostic performance of each interpretation and their impact on clinical decision making was investigated. RESULTS: (18)F-FLT/(18)F-FDG PET/CT was proven to be of clinical value in improving the diagnostic confidence in 28 lung tumours, 18 tuberculoses and 27 other benign lesions. The ratio between maximum standardized uptake values of (18)F-FLT and (18)F-FDG was found to be of great potential in separating the three subgroups of patients. The advantage could only be obtained with the full use of the multimodality interpretation. Multimodality imaging induced substantial change in clinical management in 31.5% of the study subjects and partial change in another 12.3%. CONCLUSION: Multimodality imaging using (18)F-FDG/(18)F-FLT PET/CT provided the best diagnostic efficacy and the opportunity for better management in this group of clinically challenging patients with pulmonary lesions.

[Research on the ultraviolet reflectivity characteristic of simulative targets of oil spill on the ocean].

The authors set up an experiment instrument to measure the ultraviolet (UV) characteristic of oil spill simulation targets for the marine oil spill. After selecting appropriate conditions for experiments, the authors tested UV reflective spectrum of four simulation targets for oil spill (gasoline, kerosene, diesel fuel, lubricating oil). The authors calculated the UV absolute spectrum reflectivity of all testing targets from the standard white board as reference, whose UV reflectivity was given. With processing and analyzing the data from experiments, the authors got the reflective characteristics of them in contrast to the reflectivity of water, which was measured in the same conditions. All targets were tested from 320 to 400 nm, and UV reflectivity wave-band between 360 and 380 nm was representative. Testing data were shown as follows: (1) The reflectivity of water was from 5.3% to 5.5%. (2) When the thickness of oil film was 400 microm, the reflectivity of gasoline was from 8.5% to 8.8%, 5.4%-5.8% for kerosene, 8.3%-8.4% for diesel fuel, and 9.4%-9.7% for lubricating oil in the same wave-band between 360 and 380 nm. Correspondingly, the indeterminacy of reflectivity was 0.32%, 0.45%, 0.25%, and 0.33% respectively. (3) Hence the thickness of oil film changed, the rule of the UV reflectivity varied depending on the sort of oil spill. The results show that there were some obvious reflectivity differences among oil films and water, which were mainly determined by the sort and thickness of oil film. This experiment method is also fit for the actual oil spill target, and it will fulfill some theory and experimental foundation for inspecting the marine oil spill by UV remote sensing in the future.

In-vivo PET imaging of implanted human retinal pigment epithelium cells in a Parkinson's disease rat model.

BACKGROUND AND AIM: Researchers find that monitoring the differentiation of implanted cells in vivo is difficult. This study was designed to show that it is possible to track the efficacy of transplanted human retinal pigment epithelial cells (RPE cells) in a rat model of Parkinson's disease by using positron emission tomography (PET). METHODS: RPE cells or normal saline were injected into striatum of the injured side of the rat model in treated and control groups, respectively. PET imaging of both groups was undertaken before transplantation and at intervals afterwards, using C-raclopride and C-beta-CFT as the markers. Observation of the rats' behaviour and immunofluorescence confocal microscopy were also used to prove the PET results. RESULTS: PET studies showed increased accumulation of C-raclopride and decreased C-beta-CFT in the injured side of striatum in both groups. C-raclopride decreased along with a concomitant increase of C-beta-CFT after transplantation in the treated group. The changes shown by the PET studies paralleled the behavioural states and confocal microscopy observations in the treated animals. CONCLUSION: These results suggest that even a clinical PET scanner could, to a certain extent, provide some information on the existence and in-vivo differentiation of RPE cells in a rat model of Parkinson's disease.

[Fluorine-18 fluorodeoxyglucose uptake in patients with benign pulmonary nodules].

OBJECTIVE: To assess the features of fluorine-18 fluorodeoxyglucose (FDG) uptake in patients with benign pulmonary nodules. METHODS: From October 1998 to July 2004, 47 patients with benign pulmonary nodules were imaged with FDG-positron emission tomography (PET). Diagnoses were confirmed by surgery. FDG-PET data was analyzed by visual method and semi-quantitive method. When pulmonary nodules with abnormal FDG intake appeared in PET scans confirmed by visual method, their maximum and mean standard uptake value (SUVmax and SUVmean) and SUV of normal lung (SUVlung) were measured using semiquantitative method. RESULTS: Twenty-one cases showed nothing abnormal in PET scans, including 17 calcification and fibrosis, 2 hamartomas and 2 sclerosing hemangiomas. 26 pulmonary nodules were detected by FDG-PET (17 active tuberculous, 6 inflammatory pseudotumors, 3 cryptococcosis). FDG uptake of these 26 nodules was higher than that of normal lung (SUVmax, SUVmean and SUVlung were 3.04 +/- 1.65, 2.48 +/- 1.35 and 0.40 +/- 0.07, respectively, P < 0.001). Correlations were not found between FDG uptake and nodule size or SUV of normal lung or age or blood glucose level in these 26 patients (P > 0.05). SUV in 9 cases (9/26, 35%) were beyond 2.5. CONCLUSIONS: Some benign pulmonary nodules were FDG avid.

[Value of carbon-11 choline positron emission tomography in patients with pulmonary abnormalities].

OBJECTIVE: To assess the value of carbon-11 choline (CH) positron emission tomography (PET) in patients with pulmonary nodules. METHODS: From September 2002 to December 2004, 39 patients with pulmonary nodules were imaged with CH-PET. CH-PET data was analyzed by visual method and semiquantitative method. When pulmonary nodules with abnormal CH uptake appeared in PET scans confirmed by visual method, their maximum and mean standard uptake value (SUVmax and SUVmean) were measured using semiquantitative method. Diagnoses were confirmed by surgery or biopsy and follow-up survey. RESULTS: Twenty-four cancerous and 3 inflammatory nodules and 1 bronchogenic cyst were detected by CH-PET and were diagnosed malignant with visual method. Three bronchial alveolar carcinoma, 2 metastatic tumor from kidney and colon, 3 fibrous nodules, 1 cryptococcosis, 1 hamartoma and 1 sclerosing hemangioma showed nothing abnormal in PET scans. For identification of pulmonary nodules with CH-PET, the sensitivity was 89% (24/29), the specificity was 60% (6/10), and the accuracy was 77% (30/39). There were differences in SUV between 8 squamous cell carcinomas and 9 adenocarcinomas (Z = -2.937, -2.887, P < 0.01). In diagnosing 70 resected enlarged lymph nodes beyond 1 cm in 17 lung cancer patients, CH-PET had the sensitivity of 86% (25/29), the specificity of 90% (37/41), and the accuracy of 89% (62/70). CH-PET confirmed 7 distant metastases in 25 lung cancer patients. In 5 cases suspected brain metastases CH-PET identified 2 cases positive correctly. CONCLUSIONS: CH-PET can confirm malignant pulmonary nodules, but still there were false positive and false negative cases. CH-PET can evaluate N stage effectively in patients with lung cancer. CH-PET can depict brain metastases accurately.