Fluorine-18 fluorodeoxyglucose positron emission tomography in the follow-up of differentiated thyroid cancer

Whole-body fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging was performed during the follow-up of 33 patients suffering from differentiated thyroid cancer. Among them there were 26 patients with papillary and seven with follicular tumours. Primary tumour stage (pT) was pT1 in six cases, pT2 in eight cases, pT3 in three cases and pT4 in 14 cases. FDG PET was normal in 18 patients. In three patients a slightly increased metabolism was observed in the thyroid bed, assumed to be related to remnant tissue. In one case local recurrence, in ten cases lymph node metastases (one false-positive, caused by sarcoidosis) and in three cases distant metastases were found with FDG PET. In comparison with whole-body scintigraphy using iodine-131 (WBS) there were a lot of discrepancies in imaging results. Whereas three patients had distant metastases (proven with¹³¹I) and a negative FDG PET, in four cases¹³¹I-negative lymph node metastases were detectable with PET. Even in the patients with concordant staging, differences between¹³¹I and FDG were observed as to the exact lesion localization. Therefore, a coexistence of¹³¹I-positive/FDG-negative,¹³¹I-negative/FDG-positive and¹³¹I-positive/FDG-positive malignant tissue can be assumed in these patients. A higher correlation of FDG PET was observed with hexakis (2-methoxyisobutylisonitrile) technetium-99m (I) (MIBI) scintigraphy (performed in 20 cases) than with WBS. In highly differentiated tumours¹³¹I scintigraphy had a high sensitivity, whereas in poorly differentiated carcinomas FDG PET was superior. The clinical use of FDG PET can be recommended in all cases of suspected or proven recurrence and/or metastases of differentiated thyroid cancer and is particularly useful in cases with elevated serum thyroglobulin levels and negative WBS.     

Radiation doses of yttrium-90 citrate and yttrium-90 EDTMP as determined via analogous yttrium-86 complexes and positron emission tomography

Yttrium-90 is used for palliative therapy for the treatment of skeletal metastases, but because it is a pure - emitter, data on the pharmacokinetics and radiation doses to metastases and unaffected organs are lacking. To obtain such data, the present study employed yttrium-86 as a substitute for⁹⁰Y, with detection by positron emission tomography (PET). The study compared the properties of two different⁸⁶Y complexes —⁸⁶y-citrate and⁸⁶Y -ethylene diamine tetramethylene phosphonate (EDTMP) — in ten patients with prostatic cancer who had developed multiple bone metastases (the ten patients being divided into two groups of five). Early dynamics were measured up to 1 h post injection (p.i.) over the liver region, followed by subsequent whole-body PET scans up to 3 days p.i. Absolute uptake data were determined for normal bone, bone metastases, liver and kidney. Radiation doses were calculated according to the MIRD recommendations. Based on the pharmacokinetic measurements of the distribution of the⁸⁶Y complexes, it was possible to calculate radiation doses for the bone metastases and the red bone marrow delivered by complexes containing⁹⁰Y. In 1 cm³ of bone metastasis, doses of 26±11 mGy/MBq and 18±2 mGy/MBq were determined per MBq of injected⁹⁰Y- citrate and⁹⁰Y- EDTMP, respectively. The doses to the bone marrow were 2.5±0.4 mGy/MBq for⁹⁰Y- citrate and 1.8±0.6 mGy/MBq for⁹⁰Y-EDTMP.⁸⁶Y and PET provide quantitative information applicable to the clinical use of⁹⁰Y. This method may also be useful for the design of other⁹⁰Y radiopharmaceuticals and for planning radiotherapy dosages.     

A high-yield and simplified procedure for the synthesis of α-[C]Methyl-l-tryptophan

Alpha-[¹¹C]methyl-l-tryptophan (AMT) has been synthesized by stereoselective methylation with [¹¹C]methyl iodide of the lithium-enolate generated by treating dimethyl 2(S),3a(R),8a(S)-(+)-hexahydro-8(phenylsulfonyl) pyrrolo[2,3-b]indole-1,2-dicarboxylate (2) with lithium diisopropyl amide (LDA) at −55 °C, followed by ring opening using trifluoroacetic acid and alkaline hydrolysis of the protecting groups. The crude product was purified by a simple reverse-phase C-18 Sep-Pak procedure. The purified product was isolated with an average radiochemical yield of 53 ± 12% (decay corrected) in 30–35 min from [¹¹C]methyl iodide. At end of synthesis (EOS), 138 ± 35 mCi (n = 24) of product was collected with a specific activity of ca. 1–1.3 Ci/μmol (EOS) (4–5 Ci/μmol @ EOB) starting from 1.5 Ci (EOB) of [¹¹C]CO₂.     

Role of Sialylglycoconjugate(s) in the Initial Phase of Metastasis of Liver-metastatic RAW117 Lymphoma Cells

To elucidate the early events of blood-borne metastasis under actual blood flow, real-time trafficking of RAW117 large cell lymphoma cells, namely parental RAW117-P and liver-metastatic RAW117-H10 cells, was investigated using positron emission tomography (PET). Both types of cells accumulated in the liver immediately after injection via the portal vein, and were eliminated from the liver time-dependently. The elimination rate of RAW117-H10 cells, however, was slower than that of RAW117-P cells, suggesting that RAW117-H10 cells interact more strongly with hepatic sinusoidal endothelium than the parental cells. This result correlated with the metastatic potential of these cells: RAW117-H10 cells metastasized in the liver to a greater extent than RAW117-P cells after injection via this route. To investigate the role of sialylglycoconjugates in the interaction of RAW117-H10 cells with the hepatic endothelium after injection via the portal vein, the trafficking of RAW117-H10 cells was examined after the cells had been treated with sialidase. The elimination rate of RAW117-H10 cells from liver was observed to be greatly accelerated by sialidase treatment. To elucidate what kind of sialylglycoconjugates is related to this phenomenon, we analyzed the distribution of sialyl Lewis A and sialyl Lewis X antigens of both sublines of RAW117 by using flow cytometry. RAW117-H10 cells were found to express a much higher level of sialyl Lewis A than RAW117-P cells, whereas the amount of sialyl Lewis X did not differ significantly. These findings suggest that some sialylglycoconjugates, perhaps sialyl Lewis A in particular, play an important role in the initial interaction of RAW117-H10 cells with the hepatic endothelium, leading to metastasis.     

帕金森病脑深部刺激术后FDG—PET／CT变化及临床意义

目的研究帕金森病（PD）脑深部刺激术（DBS）后全脑葡萄糖代谢（FDG）正电子发射断层扫描（PET）／计算机断层扫描（CT）功能影像学变化，探讨其评估手术疗效的临床价值。方法2011年2月至2011年7月，18例接受丘脑底核（STN）DBS治疗的PD患者分别在术前1w和术后6个月进行脑部18-F—FDG—PET／CT。结果术前大部分PD患者FDG影像学表现符合PD相关模式（PDRP）。术后异常代谢区域代谢趋向正常改变：纹状体区、中脑、感觉运动区和运动前区皮层的异常高代谢有明显下降；双侧前额叶、扣带回和辅助运动区皮层的异常低代谢有轻度升高。结论FDG影像对PD的诊断、鉴别诊断、病情评估和手术疗效有指导意义，但目前尚不能指导临床手术。     

Value of positron emission tomography/computed tomography in diagnosis and staging of primary ocular and orbital tumors

Accurate and reliable staging methods are crucial for optimal care of patients with ocular and orbital malignancies. Positron emission tomography/computed tomography (PET/CT) has recently emerged as a staging tool in the field of ophthalmic oncology. For detecting primary ocular or orbital lesions, PET/CT does not seem to provide an advantage over clinical ophthalmologic examination or conventional imaging studies such as CT or magnetic resonance imaging of the orbit. However, PET/CT may detect distant metastatic lesions that conventional imaging studies miss. For orbital and ocular adnexal lymphoma, use of PET/CT has been proven to be feasible and is now accepted both as a standard part of the initial staging work-up and for the assessment of response to therapy. For other ophthalmic tumors, PET/CT seems most appropriate for advanced metastatic tumors of the orbit, eyelid, and eye, for which the detection of distant metastasis with 1 comprehensive study may be preferable to performing multiple CT scans with contrast.     

Neuroimaging markers of glutamatergic and GABAergic systems in drug addiction: Relationships to resting-state functional connectivity

Drug addiction is characterized by widespread abnormalities in brain function and neurochemistry, including drug-associated effects on concentrations of the excitatory and inhibitory neurotransmitters glutamate and gamma-aminobutyric acid (GABA), respectively. In healthy individuals, these neurotransmitters drive the resting state, a default condition of brain function also disrupted in addiction. Here, our primary goal was to review in vivo magnetic resonance spectroscopy and positron emission tomography studies that examined markers of glutamate and GABA abnormalities in human drug addiction. Addicted individuals tended to show decreases in these markers compared with healthy controls, but findings also varied by individual characteristics (e.g., abstinence length). Interestingly, select corticolimbic brain regions showing glutamatergic and/or GABAergic abnormalities have been similarly implicated in resting-state functional connectivity deficits in drug addiction. Thus, our secondary goals were to provide a brief review of this resting-state literature, and an initial rationale for the hypothesis that abnormalities in glutamatergic and/or GABAergic neurotransmission may underlie resting-state functional deficits in drug addiction. In doing so, we suggest future research directions and possible treatment implications.     

Prognostic value of myocardial perfusion imaging after first-line coronary computed tomography angiography: A multi-center cohort study

PurposeFurther diagnostic testing may be required after a coronary computed tomography angiography (CTA) showing suspected coronary stenosis. Whether myocardial perfusion imaging (MPI) provides further prognostic information post-CTA remains debated. We evaluated the prognosis for patients completing CTA stratified for post-CTA diagnostic work-up using real-world data.MethodsWe identified all patients in our uptake area with angina symptoms undergoing first-time CTA over a 10-year period. Follow-up time was a median of 3.7 years [1.9–5.8]. The primary endpoint was a composite of myocardial infarction or death. The secondary endpoint was late revascularization.ResultsDuring the study period 53,351 patients underwent CTA. Of these, 24% were referred for further down-stream testing, 3,547 (7%) to MPI and 9,135 (17%) to invasive coronary angiography (ICA). The primary and secondary endpoints occurred in 2,026 (3.8%) and 954 (1.8%) patients. Patient-characteristic-adjusted hazard ratios for the primary and secondary endpoint using patients with a normal CTA as reference were 1.37 (1.21–1.55) and 2.50 (1.93–3.23) for patient treated medically, 1.68 (1.39–2.03) and 6.13 (4.58–8.21) for patients referred to MPI and 1.94 (1.69–2.23) and 9.18 (7.16–11.78) for patients referred for ICA, respectively. Adjusted analysis with stratification for disease severity at CTA showed similar hazard ratios for patients treated medically after CTA and patients referred for MPI and treated medically after the MPI.ConclusionIn patients completing coronary CTA, second-line MPI testing seems to identify patients at low risk of future events. MPI seems to have the potential to act as gatekeeper for ICA after coronary CTA.