18F-FDG PET/CT in the evaluation of POEMS syndrome

In POEMS syndrome the identification and biopsy of an osteosclerotic lesion or a lymph node typical of Castleman's disease (CD) is essential to establish the diagnosis and plan appropriate treatment. We report four patients in whom the localisation and identification of diagnostic bone lesions or lymphadenopathies were guided by fluorodeoxyglucose positron emission tomography integrated with computerised tomography (FDG PET/CT). FDG PET/CT identified bone lesions not detected with other techniques in one patient, and revealed hypermetabolic characteristics in bone lesions or adenopathies in the others, thus guiding the diagnostic biopsy in those with hypermetabolism. In conclusion, FDG PET/CT may be useful in detecting and selecting bone lesions and lymph nodes for biopsy in patients with suspected POEMS syndrome.     

Multiple Skeletal Muscle Metastases in a Case of Transitional Cell Carcinoma of Bladder Detected by F-18 FDG PET/CT

We present a case of poorly differentiated muscle invasive transitional cell carcinoma in a 64-year-old male diagnosed with FDG-avid mass in the urinary bladder wall and multiple skeletal muscles visualised on F-18 FDG PET/CT.     

PET/CT in oncology--a major advance

The concept of hardware fusion between positron emission tomography (PET) and computed tomography (CT) has only been introduced commercially in the last 4 years. The advantages of this combined technique over PET alone have become obvious. There is increasing evidence to suggest that PET/CT adds complementary information in staging, re-staging and follow-up in oncology patients, leading to changes in management plans. The present paper is a review of the strengths, weaknesses, current evidence and future directions of this technique.     

The role of F-FDG PET or PET/CT in the detection of fever of unknown origin

Even with the recent advance in diagnostic tools and techniques, fever of unknown origin (FUO) remains a clinical challenge. A wide range of diseases, mainly infections, autoimmune conditions (inflammatory diseases), malignancies and miscellaneous can cause FUO. Positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) scanning makes a great contribution to the diagnosis and differential diagnosis of FUO due to the high sensitivity of pathological accumulation of ¹⁸F-FDG. The diagnostic yield of PET/CT is higher than traditional radiographic imaging and other nuclear medicine scanning. Owing to the numerous advantages of PET/CT including high sensitivity and the ability to perform whole-body scans, many rare diseases presenting with FUO can be detected and the spectrum of diseases that can exhibit FUO has been increasing. Recent studies utilizing FUO are discussed in this paper. However, there are limited data available about the role of ¹⁸F-FDG PET or PET/CT in evaluation of FUO.     

Attenuation correction in cardiac PET/CT with three different CT protocols: a comparison with conventional PET

Purpose CT-based attenuation correction may influence cardiac PET owing to its higher susceptibility to misalignment compared with conventional ⁶⁸Ge transmission scans. The aims of this study were to evaluate whether CT attenuation correction leads to changes in tracer distribution compared with conventional cardiac PET and to determine a suitable CT protocol. Methods A total of 27 patients underwent PET/CT and subsequently a PET scan. Twenty patients received a low-dose CT (LDCT group; 120 kV, 26 mA, 8-s scan time), seven patients a slow CT (SCT group; 120 kV, 99 mA, 46-s scan time) and ten patients an ultra-low-dose CT (ULDCT group; 80 kV, 13 mA, 5-s scan time) as the transmission scan in PET/CT. Polar maps were divided into 17 segments and regression analysis was computed in every scan pair (CT attenuation corrected–⁶⁸Ge attenuation corrected). Correlation coefficient (r), the slope (s) and the offset (os) of the regression line were determined. Visual assessment of misalignment between the transmission and emission data was performed. The effective dose of the different transmission scans was calculated. Results Overall, there was a moderate correlation between the mean values measured in all segments on PET/CT and on PET when using LDCT (r=0.78, p<0.0001), SCT (r=0.79, p<0.0001) and ULDCT (r=0.82, p<0.0001). No differences were observed when comparing the scores assigned in the visual misalignment assessment in the three groups (p=0.12). The differences between the results from the regression analysis observed in the respective groups were not statistically significant (Kruskal-Wallis p=0.11 for r, p=0.67 for s and p=0.27 for os). The effective dose was lowest for the ULDCT. Conclusion Our study shows that CT-based attenuation correction is feasible for cardiac PET imaging. The results indicate that ultra-low-dose CT is the preferable choice for transmission scanning.     

2-[Fluorine-18]-fluoro-2-deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-glucose positron emission tomography/computed tomography versus whole-body diffusion-weighted MRI for detection of malignant lesions: initial experience

Objectives The new magnetic resonance whole body diffusion-weighted imaging with background body signal suppression (DWIBS) uses short tau inversion recovery-echo planar imaging sequence under normal respiration. DWIBS is different from 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET) imaging in technology, but their images are similar. We compared the two modalities regarding the detection and characterization of malignant tumors. Methods DWIBS and ¹⁸F-FDG PET/computed tomography (CT) were performed on 16 cancer patients on the same day. The diagnoses were the following: lung cancer (n = 12), colon cancer (n = 2), breast cancer (n = 1), and pulmonary metastasis (n = 1). A total of 27 malignant tumors (15 lung cancer, 5 pulmonary metastases of parathyroid cancer, 3 pulmonary metastases of lung cancer, 3 colon cancer, 1 breast cancer) and seven reference organs around malignant lesions (two liver regions, four normal lymph nodes, one muscle region) were evaluated visually and quantitatively using the apparent diffusion coefficient (ADC) (×10⁻³ mm²/s) and standardized uptake value (SUV). Results Twenty-five (92.6%) of the 27 malignant lesions were detected visually with DWIBS imaging in contrast to 22 malignant tumors (81.5%) with ¹⁸F-FDG PET/CT imaging. The quantitative evaluation showed that there was a significant difference between the mean SUVs of the reference organs (n = 7, 1.48 ± 0.62) and the malignant (n = 22, 5.36 ± 2.80) lesions (P < 0.01). However, there was no significant difference between the mean ADCs of the reference organs (n = 7, 1.54 ± 0.24) and the malignant (n = 25, 1.18 ± 0.70) lesions. Conclusions DWIBS can be used for the detection of malignant tumors or benign tumors; however, it may be difficult to differentiate between benign and malignant lesions by ADC.     

18F FDG-PET/CT findings in recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) is an indolent and primary disease of the larynx and the trachea and rarely extends to smaller airways. F-18 fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/CT) evaluation in this condition has not been reported earlier. We report FDG-PET/CT findings in a case of RRP that included a large papillomatous lung mass resembling cancer.     

The Prognostic Value of 18F-Fluorodeoxyglucose PET/CT in the Initial Assessment of Primary Tracheal Malignant Tumor: A Retrospective Study

ObjectiveTo investigate the potential value of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in predicting the survival of patients with primary tracheal malignant tumors.Materials and MethodsAn analysis of FDG PET/CT findings in 37 primary tracheal malignant tumor patients with a median follow-up period of 43.2 months (range, 10.8–143.2 months) was performed. Cox proportional hazards regression analyses were used to assess the associations between quantitative ¹⁸F-FDG PET/CT parameters, other clinic-pathological factors, and overall survival (OS). A risk prognosis model was established according to the independent prognostic factors identified on multivariate analysis. A survival curve determined by the Kaplan-Meier method was used to assess whether the prognosis prediction model could effectively stratify patients with different risks factors.ResultsThe median survival time of the 37 patients with tracheal tumors was 38.0 months, with a 95% confidence interval of 10.8 to 65.2 months. The 3-year, 5-year and 10-year survival rate were 54.1%, 43.2%, and 16.2%, respectively. The metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value, age, pathological type, extension categories, and lymph node stage were included in multivariate analyses. Multivariate analysis showed MTV (p = 0.011), TLG (p = 0.020), pathological type (p = 0.037), and extension categories (p = 0.038) were independent prognostic factors for OS. Additionally, assessment of the survival curve using the Kaplan-Meier method showed that our prognosis prediction model can effectively stratify patients with different risks factors (p < 0.001).ConclusionThis study shows that ¹⁸F-FDG PET/CT can predict the survival of patients with primary tracheal malignant tumors. Patients with an MTV > 5.19, a TLG > 16.94 on PET/CT scans, squamous cell carcinoma, and non-E1 were more likely to have a reduced OS.     

Variation in FDG uptakes in different regions in normal human brain as a function of the time (30 and 60 minutes) after injection of FDG

OBJECTIVE: The authors' goal was to determine whether FDG uptakes in various regions of the brain are different for early and late scanning time in positron emission tomography (PET). METHOD: F-18 fluorodeoxyglucose (FDG) PET was performed on 15 healthy normal subjects to obtain early and late acquisition glucose metabolic images (30 and 60 min after FDG injection), respectively. The two sets of images were compared in a voxel-by-voxel analysis. RESULTS: In the bilateral posterior cingulate gyrus, parietal and frontal association cortices, and subcallosal cortices, the FDG uptakes were larger on the late scan image than on the early scan image, and the FDG uptakes were larger in the cerebellar hemisphere, vermis and frontal basis on the early scan image than on the late scan image. CONCLUSIONS: These results suggest that there are different regional FDG uptakes depending on the scanning time after FDG injection and we must be careful in replacing conventional FDG PET scanning with early scanning in FDG PET study.     

皮病性淋巴结炎的FDG PET/CT表现及临床病理研究(附2例报告及文献复习)

目的 探讨皮病性淋巴结炎(DL)的临床病理及18F-FDG PET/CT表现特点,提高对本病的诊断水平.方法 搜集本院2例病理确诊为DL的患者资料,并检索国内外近10年关于DL的文献,回顾性分析DL的临床病理及PET/CT表现特点.结果 2例患者临床均表现为反复发热,全身浅表淋巴结肿大,皮肤瘙痒伴红斑,骨髓增生活跃.PET/CT检查发现2例患者全身多处淋巴结肿大伴糖代谢增高,SUVmax＞ 2.5,摄取18FDG最高的部位在腋窝,SUVmax达12,同时均伴有脾肿大伴糖代谢增高,骨髓浓聚增高.结论 DL患者在PET/CT上多表现为全身多处淋巴结肿大伴18FDG摄取增高,腋窝、腹股沟、颈部多见,呈对称性分布,无融合趋势.DL的主要临床表现为全身多发无痛性淋巴结肿大,常伴有皮肤改变.病理为非特异性淋巴结反应性增生.     

A method for measuring the absolute sensitivity of positron emission tomographic scanners

A need exists to measure the absolute sensitivity of a positron emission tomographic (PET) scanner in units of counts. s^–1.MBq^–1. At present sensitivity is generally determined by measurement of a radionuclide of known concentration distributed in a water-filled cylindrical phantom, usually 20 cm in diameter. The measurement is confounded by self-attenuation of the source and scatter within the cylinder and does not give a true absolute sensitivity measurement. Due to variations in the magnitude and treatment of these factors, meaningful comparison between different manufacturer's scanners is difficult, as are comparisons between different acquisition geometries (e.g. with and without interplane septa present). A method has been developed in our laboratory that provides measurements of absolute sensitivity in air for a scanner independent of attenuation and scatter within the source. The method involves measurements of a thin-line source of fluorine 18 contained within an aluminium housing to which successive aluminium sleeves are added. The extrapolation of these measurements allows an effective counts. s^–1.MBq^–1 measurement to be made for zero thickness of aluminium. Measurements have yielded absolute sensitivities of 3 926 ± 61 counts. s^–1.MBq^–1 (0.39% efficiency), 5079±26 counts. s^–1.MBq^–1 (0.51%), and 32312±544 counts. s^–1.MBq^–1 (3.2%) for a whole-body PET scanner with interplane septa and for a NeuroPET operating with and without interplane septa, respectively.     

Cardiac nuclear medicine tomographic systems

There are two competitive measuring techniques in emission tomography: SPECT and PET. The superiority of PET is founded not only on using physiological radionuclides and tracers such as carbon 11, oxygen 15, and nitrogen 13, but also on achieving a physical performance far in excess of that of SPECT. Considering the demands of cardiac studies, the performance of both methods is analyzed and compared and the inherent limitations are stated.Dedicated to Prof. Heinz Hundeshagen on the occasion of his 60th birthday     

Cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography in tumours other than lung cancer: A systematic review

AIM: To systematically review published data on the cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography (FDG-PET) or PET/computed tomography (PET/CT) in tumours other than lung cancer.METHODS: A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus and Embase databases through the 10^th of October in 2013 was carried out. A search algorithm based on a combination of the terms: (1) “PET” or “ PET/computed tomography (PET/CT)” or “positron emission tomography”; and (2) “cost-effectiveness” or “cost-utility” or “cost-efficacy” or “technology assessment” or “health technology assessment” was used. Only cost-effectiveness or cost-utility analyses in English language were included. Exclusion criteria were: (1) articles not within the field of interest of this review; (2) review articles, editorials or letters, conference proceedings; and (3) outcome evaluation studies, cost studies or health technology assessment reports. For each included study, information was collected concerning basic study, type of tumours evaluated, perspective/type of study, results, unit and comparison alternatives.RESULTS: Sixteen studies were included. Head and neck tumours were evaluated in 4 articles, lymphoma in 4, colon-rectum tumours in 3 and breast tumours in 2. Only one article was retrieved for melanoma, oesophagus and ovary tumours. Cost-effectiveness results of FDG-PET or PET/CT ranged from dominated to dominant.CONCLUSION: Literature evidence about the cost-effectiveness of FDG-PET or PET/CT in tumours other than lung cancer is still limited. Nevertheless, FDG-PET or PET/CT seems to be cost-effective in selective indications in oncology (staging and restaging of head and neck tumours, staging and treatment evaluation in lymphoma).     

锰中毒的神经影像学研究进展

近二十年来,医学影像学对临床医学的影响非常深刻,在疾病的诊断和治疗中的作用是具革命性的。核磁共振成像(MRI)、正电子发射断层摄影(PET)和单光子发射断层摄影(SPECT)等神经影像学方法在最近十年中已应用于锰中毒和其神经毒理学研究。MRI T1加权图像信号强度增加会反映锰的沉积,功能神经影像学如:PET、SPECT,能早期发现黑质纹状体多巴胺系统的异常,因此MRI、PET、SPECT对于锰中毒的诊断非常重要。     

Comparison of FDG-PET and IMP-SPECT in patients with dementia with Lewy bodies

OBJECTIVES: To investigate regional differences in cerebral glucose metabolism and blood flow of dementia with Lewy bodies (DLB), we studied 7 subjects with DLB and 20 normal controls using F-18 fluorodeoxyglucose (FDG) and positron emission tomography (PET) and then examined the same 7 subjects and 20 other normal controls with I-123 iodoamphetamine (IMP) and single photon emission computed tomography (SPECT). METHODS: The anatomically standardized images were produced with NEUROSTAT and the regional relative metabolic and perfusional values were calculated. RESULTS: The mean reduction ratios of FDG uptake in the DLB group relative to the mean normal controls in the parietal lobe and occipital lobe were 0.72 and 0.83, respectively, while the corresponding mean reduction ratios of IMP uptake were 0.81 and 0.88, respectively. In the DLB group, parietal FDG uptake was significantly lower than parietal IMP uptake (p < 0.05), occipital FDG uptake was significantly lower than occipital IMP uptake (p < 0.05), and parietal IMP uptake was significantly lower than occipital IMP uptake (p < 0.01), but there was no difference between parietal and occipital FDG uptake. CONCLUSIONS: Our findings suggest that parietal metabolism and perfusion are severely affected in DLB patients, though the occipital metabolic and perfusional reduction is thought to be a feature of DLB. FDG-PET is thought to be superior to IMP-SPECT in detecting functional changes in the DLB brain.     

Quantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT

ObjectivesTo evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging.MethodsTwenty min ¹⁸F-FDG phantom measurements and 10 min ¹⁸F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n = 8) and a Biograph mMR PET/MR (n = 16). Listmode data were repeatedly split into frames of 1 min to 10 min length and reconstructed using two different reconstruction settings of a 3D-OSEM algorithm: with post-filtering (“OSEM”), and without post-filtering but with resolution recovery (“PSF”). Recovery coefficients (RC_max, RC_A50) and standard uptake values (SUV_max, SUV_A50) were evaluated.ResultsRC_max (phantom) and SUV_max (patients) increased significantly when reducing the frame duration. Significantly lower deviations were observed for RC_A50 and SUV_A50, respectively, making them more appropriate to compare PET studies at different number of counts. No statistical significant differences were observed when using post-filtering and reducing the frame time to 4 min (RC_A50, reference 20 min, phantom) and to 3 min (SUV_A50, reference 10 min, patients).ConclusionsFor hybrid aminoacid brain imaging, frame duration (or injected activity) can potentially be reduced to 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images if adequate reconstruction settings and quantitative measures are used. Frame times below 4 min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.