18F]fluorodeoxyglucose positron emission tomography imaging in a case of relapsing polychondritis

Relapsing polychondritis is a rare multisystemic disease that is characterized by recurrent inflammation of the cartilaginous structures of the external ear, nose, joint, larynx, and tracheobronchial tree. Airway involvement is present in up to 50% of patients with the disease and is a major cause of morbidity and mortality. We describe a patient with relapsing polychondritis presenting with tracheal and bronchial abnormalities that were identified by an increased uptake on [18F]fluorodeoxyglucose positron emission tomography.     

Pathology results in [18F]fluorodeoxyglucose positron emission tomography of the thyroid gland

The aim of this retrospective study was to evaluate pathologically increased uptake of [18F]fluorodeoxyglucose (18F-FDG) in positron emission tomography (PET) results of the thyroid gland. Results of 18F-FDG PET and [99mTc]pertechnetate scintigraphy of the thyroid gland are shown, compared to each other and discussed. In a retrospective study 16 patients underwent whole-body 18F-FDG PET and [99mTc]pertechnetate scintigraphy of the thyroid gland within 3 weeks. In addition, an examination of the thyroid gland by using ultrasound and laboratory tests was carried out. The 18F-FDG PET studies were carried out on a dedicated whole-ring PET scanner. Eight patients had a pathological FDG uptake in the thyroid and a cold nodule in [99mTc]pertechnetate scintigraphy of the thyroid gland (in 7/8 cases histology showed malignancy). Five patients had an inhomogeneous FDG uptake in the thyroid gland and were suspected of thyroiditis in 18F-FDG PET (in 3/5 cases thyroiditis was confirmed). Three patients had an especially low FDG uptake compared to normal physiological FDG uptake (no malignancy). Results from studies using 18F-FDG represent a growing body of evidence showing the differentiation between malignant and benign disease: we saw many pathological results in the thyroid gland. High uptake of 18F-FDG in the thyroid gland suggests possible malignancy. Thyroiditis can only be suspected based upon the results of 18F-FDG PET. We conclude that 18F-FDG PET has a potential clinical impact for detecting possible malignant lesions of the thyroid gland, but further studies, in which a higher number of patients are evaluated, are necessary.     

Quantification method in [18F]fluorodeoxyglucose brain positron emission tomography using independent component analysis

OBJECTIVE: To extract accurate image-derived input functions from dynamic brain positron emission tomography images (DBPIs) using independent component analysis (ICA). METHODS: A modified linear model with haematocrit correction was used to improve the accuracy of input functions estimated by independent component analysis and to reduce the error of quantitative analysis. Two types of material were examined: (1) a simulated dynamic phantom with a three-compartment, four-parameter model; (2) clinical 2-h DBPIs with a standard plasma sampling procedure. The input function was extracted from DBPIs using independent component analysis. The modified linear model with haematocrit correction was used to obtain the independent component analysis-estimated input function (Iica). For comparison, the input function derived from the last three blood samples (Iest) was used. The image-derived input functions (Iica and Iest) were compared with the input function from blood sampling (Itp). The mean percentage error of the metabolic rate of [F]-2-fluoro-2-deoxy-D-glucose (MRFDG) was calculated for both Iica and Iest against that of Itp. RESULTS: In simulated studies, the mean percentage errors of MRFDG between true simulated and estimated values of Iest and Iica were 8.2% and 4.2%, respectively. In clinical studies, six clinical cases were collected. The mean percentage errors and standard deviations of MRFDG with Iest and Iica were 12.6+/-7.5% and 7.7+/-3.3%, respectively. CONCLUSIONS: We have proposed a technique for estimating image-derived input functions using independent component analysis without blood sampling. The results of our method were highly correlated with those from standard blood sampling, and more accurate than those of other methods proposed previously.     

Evaluation of suspected recurrent papillary thyroid carcinoma with [18F]fluorodeoxyglucose positron emission tomography

We evaluated 10 patients with suspected recurrent papillary thyroid cancer using [18F]fluorodeoxyglucose positron emission tomography (FDG PET). Prior therapy included total (n = 8) or subtotal (n = 2) thyroidectomy, radiation therapy (n = 2) and radioiodine ablation (n = 2). All patients had an 131I scan and one or more of the following imaging studies: 99Tcm-sestamibi scan. 111In-octreotide scan, sonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). Both the PET and 131I scans were negative in four patients. The PET and 131I scan results were discordant in six patients. Of the six discordant cases, five had true-positive PET scans and false-negative 131I studies. Three of these patients underwent neck lymph node dissection that showed positive histology for metastatic papillary carcinoma. Another patient had fine-needle aspiration (FNA) of a parapharyngeal mass that was also positive for papillary carcinoma. One patient was treated with radiation to the thyroid surgical bed based on an elevated serum thyroglobulin and a positive PET finding. Tumour response with a decrease in the size of the lesion was documented by a follow-up MRI scan. The remaining patient had a presumed false-positive PET scan, since a difficult hypocellular FNA of a small palpable lymph node was negative for tumour. We conclude that FDG PET is useful in the evaluation of patients with suspected recurrent papillary thyroid cancer when the 131I scan is negative.     

Diagnosis of infection of implantable central venous catheters by [18F]fluorodeoxyglucose positron emission tomography

OBJECTIVE: The aim of this study was to evaluate the role of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging in the diagnosis of infection of implantable vascular catheters. METHODS: We evaluated six patients with haematological cancer and infection of their implantable vascular catheter and who underwent FDG PET imaging around the time of their infection. RESULTS: Six patients with multiple myeloma who developed infection of their implantable device (five port pocket infections and one tunnel infection) were identified. FDG PET revealed increased uptake at the site of the implantable catheter (SUV 2.7-4.5) in all six patients, even in the absence of signs or symptoms of infection at the site of the device (three), and the presence of severe neutropenia (four). The three patients who did not have local inflammation at the site of the device were profoundly neutropenic. The FDG PET diagnosis led to removal of the device in two patients. CONCLUSION: FDG PET is a safe, rapid and accurate tool for diagnosing infection of an implantable catheter, including among those patients not exhibiting local signs and symptoms of infection, and in whom the diagnosis of infected device may be difficult. FDG PET may help prevent the unnecessary removal of implantable intravascular catheters and the unwarranted use of antibiotics.     

F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma

OBJECTIVES: We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma. METHODS: The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2 months to 8 years). RESULTS: PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively. CONCLUSIONS: FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.     

Imaging atherosclerosis with hybrid [18F]fluorodeoxyglucose positron emission tomography/computed tomography imaging: What Leonardo da Vinci could not see

Prodigious efforts and landmark discoveries have led toward significant advances in our understanding of atherosclerosis. Despite significant efforts, atherosclerosis continues globally to be a leading cause of mortality and reduced quality of life. With surges in the prevalence of obesity and diabetes, atherosclerosis is expected to have an even more pronounced impact upon the global burden of disease. It is imperative to develop strategies for the early detection of disease. Positron emission tomography (PET) imaging utilizing [¹⁸F]fluorodeoxyglucose (FDG) may provide a non-invasive means of characterizing inflammatory activity within atherosclerotic plaque, thus serving as a surrogate biomarker for detecting vulnerable plaque. The aim of this review is to explore the rationale for performing FDG imaging, provide an overview into the mechanism of action, and summarize findings from the early application of FDG PET imaging in the clinical setting to evaluate vascular disease. Alternative imaging biomarkers and approaches are briefly discussed.     

Patient preparation for cardiac fluorine-18 fluorodeoxyglucose positron emission tomography imaging of inflammation

Although the number of clinical applications for fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) cardiac positron emission tomography (PET) has continued to grow, there remains a lack of consensus regarding the ideal method of suppressing normal myocardial glucose utilization for image optimization. This review describes various patient preparation protocols that have been used as well as the success rates achieved in different studies. Collectively, the available literature supports using a high-fat, no-carbohydrate diet for at least two meals with a fast of 4-12 hours prior to ¹⁸F-FDG PET imaging and suggests that isolated fasting for less than 12 hours and supplementation with food or drink just prior to imaging should be avoided. Each institution should adopt a protocol and continuously monitor its effectiveness with a goal to achieve adequate myocardial suppression in greater than 80% of patients.     

Head-to-head comparison of tau positron emission tomography tracers [18F]flortaucipir and [18F]RO948

European Journal of Nuclear Medicine and Molecular Imaging - [18F]flortaucipir binds to paired helical filament tau and accurately identifies tau in Alzheimer’s disease (AD). However,...     

Regional cerebral metabolic alterations in dementia of the Alzheimer type: positron emission tomography with [18F]fluorodeoxyglucose

Alzheimer disease is the most common cause of dementia in adults. Despite recent advances in our understanding of its anatomy and chemistry, we remain largely ignorant of its pathogenesis, physiology, diagnosis, and treatment. Dynamic positron emission tomography using [18F]fluorodeoxyglucose (FDG) was performed on the Donner 280-crystal ring in 10 subjects with dementia of the Alzheimer type and six healthy age-matched controls. Ratios comparing mean counts per resolution element in frontal, temporoparietal, and entire cortex regions in brain sections 10 mm thick obtained 40-70 min following FDG injection showed relatively less FDG uptake in the temporoparietal cortex bilaterally in all the Alzheimer subjects (p less than 0.01). Left-right alterations were less prominent than the anteroposterior changes. This diminished uptake was due to lowered rates of FDG use and suggests that the metabolic effects of Alzheimer disease are most concentrated in the temporoparietal cortex. Positron emission tomography is a most powerful tool for the noninvasive in vivo assessment of cerebral pathophysiology in dementia.     

In vivo imaging of synaptic loss in Alzheimer’s disease with [18F]UCB-H positron emission tomography

European Journal of Nuclear Medicine and Molecular Imaging - Loss of brain synapses is an early pathological feature of Alzheimer’s disease. The current study assessed synaptic loss in vivo...     

F-18 fluorodeoxyglucose positron emission tomography in pulmonary cryptococcoma

Cryptococcosis is not uncommon. Potential interpretation pitfalls should be kept in mind when fluorodeoxyglucose (FDG) positron emission tomography (PET) is used for differentiating pulmonary nodules and for discriminating infection from malignancy, especially in areas where the prevalence of granulomatous infection is high and in immunocompromised patients. In this case, a nodular mass was shown on chest radiography and computed tomographic (CT) scanning. A consolidated infection or a bronchioloalveolar carcinoma was suspected because the CT scan showed air bronchograms within the mass and another perihilar infiltration. The FDG PET scan clearly delineated the lesion and had intermediately high glucose uptake (standard uptake value, 3.8-4.0), which led to the exclusion of the possibility of bronchioloalveolar carcinoma because most of these tumors had normal or mildly increased FDG accumulation. Cryptococcoma was finally diagnosed. Hence, the CT scan and FDG PET played complementary roles in the differential diagnosis of this nodular mass.     

Evaluation of O-[18F]fluoromethyl-d-tyrosine as a radiotracer for tumor imaging with positron emission tomography

O-[¹⁸F]Fluoromethyl-d-tyrosine (d-[¹⁸F]FMT) has been reported as a potential tumor-detecting agent for positron emission tomography (PET). However, the reason why d-[¹⁸F]FMT is better than l-[¹⁸F]FMT is unclear. To clarify this point, we examined the mechanism of their transport and their suitability for tumor detection. The stereo-selective uptake and release of enantiomerically pure d- and l-[¹⁸F]FMT by rat C6 glioma cells and human cervix adenocarcinoma HeLa cells were examined. The results of a competitive inhibition study using various amino acids and a selective inhibitor for transport system L suggested that d-[¹⁸F]FMT, as well as l-[¹⁸F]FMT, was transported via system L, the large neutral amino acid transporter, possibly via LAT1. The in vivo distribution of both [¹⁸F]FMT and [¹⁸F]FDG in tumor-bearing mice and rats was imaged with a high-resolution small-animal PET system. In vivo PET imaging of d-[¹⁸F]FMT in mouse xenograft and rat allograft tumor models showed high contrast with a low background, especially in the abdominal and brain region. The results of our in vitro and in vivo studies indicate that l-[¹⁸F]FMT and d-[¹⁸F]FMT are specifically taken up by tumor cells via system L. d-[¹⁸F]FMT, however, provides a better tumor-to-background contrast with a tumor/background (contralateral region) ratio of 2.741 vs. 1.878 with the l-isomer, whose difference appears to be caused by a difference in the influence of extracellular amino acids on the uptake and excretion of these two isomers in various organs. Therefore, d-[¹⁸F]FMT would be a more powerful tool as a tumor-detecting agent for PET, especially for the imaging of a brain cancer and an abdominal cancer.     

[18F]-labeled 2-methoxyphenylpiperazine derivative as a potential brain positron emission tomography imaging agent

This study reports the synthesis and characterization of N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl-4-[¹⁸F]fluorobenzamide ([¹⁸F]MPP3F). The total reaction time for [¹⁸F]MPP3F, including final high-performance liquid chromatography purification, was about 3 h. Typical decay-corrected radiochemical yield was 18.4±3.1%. The radiochemical purity was >98%. Biodistribution in mice showed that [¹⁸F]MPP3F is a potential brain imaging agent for positron emission tomography. The brain uptake of [¹⁸F]MPP3F was 6.59±0.77% Injected Dose/g at 2 min post-injection time. A brain-to-blood ratio of 3.67 was reached at 15 min after injection.     

Noninvasive in vivo measurement of vascular inflammation with F-18 fluorodeoxyglucose positron emission tomography

BACKGROUND: Fluorine 18 fluorodeoxyglucose (FDG) has been shown to accumulate in inflamed tissues. However, it is not known whether vascular inflammation can be measured noninvasively. The aim of this study was to test the hypothesis that vascular inflammation can be measured noninvasively by use of positron emission tomography (PET) with FDG. METHODS AND RESULTS: Inflamed atherosclerotic lesions were induced in 9 male New Zealand white rabbits via balloon injury of the aortoiliac arterial segment and exposure to a high cholesterol diet. Ten rabbits fed standard chow served as controls. Three to six months after balloon injury, the rabbits were injected with FDG (1 mCi/kg), after which aortic uptake of FDG was assessed (3 hours after injection). Biodistribution of FDG activity within aortic segments was obtained by use of standard well gamma counting. FDG uptake was also determined noninvasively in a subset of 6 live atherosclerotic rabbits and 5 normal rabbits, via PET imaging and measurement of standardized uptake values over the abdominal aorta. Plaque macrophage density and smooth muscle cell density were determined by planimetric analysis of RAM-11 and smooth muscle actin staining, respectively. Biodistribution of FDG within nontarget organs was similar between atherosclerotic and control rabbits. However, well counter measurements of FDG uptake were significantly higher within atherosclerotic aortas compared with control aortas (P < .001). Within the upper abdominal aorta of the atherosclerotic group (area of greatest plaque formation), there was an approximately 19-fold increase in FDG uptake compared with controls (108.9 +/- 55.6 percent injected dose [%ID]/g x 10(3) vs 5.7 +/- 1.2 %ID/g x 10(3) [mean +/- SEM], P < .001). In parallel with these findings, FDG uptake, as determined by PET, was higher in atherosclerotic aortas (standardized uptake value for atherosclerotic aortas vs control aortas, 0.68 +/- 0.06 vs 0.13 +/- 0.01; P < .001). Moreover, macrophage density, assessed histologically, correlated with noninvasive (PET) measurements of FDG uptake (r = 0.93, P < .0001). In contrast to this finding, FDG uptake did not correlate with either aortic wall thickness or smooth muscle cell staining of the specimens. CONCLUSION: These data show that FDG accumulates in macrophage-rich atherosclerotic plaques and demonstrate that vascular macrophage activity can be quantified noninvasively with FDG-PET. As such, measurement of vascular FDG uptake with PET holds promise for the noninvasive characterization of vascular inflammation.     

Monitoring liver tumor therapy with [18F]FDG positron emission tomography

Positron emission tomography (PET) with [18F]-2-flurodeoxy-glucose (FDG) can be utilized as a functional imaging modality for monitoring liver tumor therapy. We report three cases in which PET-FDG was more useful for this purpose than other imaging methods and tumor markers.