Combined C-11 methionine and F-18 FDG PET imaging in a case of neurosarcoidosis

PURPOSE: PET scanning of the brain with F-18 FDG and C-11 methionine (MET) is useful for characterizing brain lesions discovered at MRI or CT. Most positive PET scans indicate malignancy. However, this case report demonstrates positive F-18 FDG and C-11 MET PET scans in a patient with a nonmalignant condition, neurosarcoidosis. MATERIALS AND METHODS: We detail the history and evaluation of a 59-year-old woman who presented with ataxia. The patient's evaluation included a contrast-enhanced MRI followed by PET scanning of the brain with C-11 MET and of the brain and trunk with F-18 FDG. The patient subsequently underwent biopsy of a lesion as directed by MRI and PET. RESULTS: The MRI demonstrated multiple enhancing leptomeningeal lesions consistent with metastatic disease. PET with F-18 FDG and C-11 MET demonstrated lesions in both cerebellar hemispheres with F-18 FDG accumulation in the mediastinum and left hilum. Biopsy of a brain lesion directed by MRI and PET revealed sarcoidosis. CONCLUSIONS: In evaluating brain lesions, PET with F-18 FDG and C-11 MET can help localize the lesion best suited for biopsy. However, not all lesions that have increased uptake on C-11 MET or F-18 FDG PET are malignant. Granulomatous inflammatory diseases such as neurosarcoidosis should also be considered in the differential diagnosis.     

Magnetic resonance imaging of the body trunk using a single-slab, 3-dimensional, T2-weighted turbo-spin-echo sequence with high sampling efficiency (SPACE) for high spatial resolution imaging: initial clinical experiences

PURPOSE: The authors conducted a clinical evaluation of single-slab, 3-dimensional, T2-weighted turbo-spin-echo (TSE) with high sampling efficiency (SPACE) for high isotropic body imaging with large field-of-view (FoV). MATERIALS AND METHODS: Fifty patients were examined in clinical routine with SPACE (regions of interest: pelvis n=30, lower spine n=12, upper spine n=6, extremities n=4) at 1.5 T. For achieving a high sampling efficiency, parallel imaging, high turbofactor, and magnetization restore pulses were used. In contrast to a conventional TSE imaging technique with constant flip angle refocusing, the refocusing pulse train of the SPACE sequence consists of variable flip angle radiofrequency pulses along the echo train. RESULTS: Signal-to-noise ratio and contrast-to-noise ratio of SPACE images were of sufficient diagnostic value. The possibility of image reconstruction in multiple planes was of clinical relevance in all cases and simplified data analysis. CONCLUSION: The achievement of 3-dimensional, T2-weighted TSE magnetic resonance imaging with isotropic and high spatial resolution and interactive 3-dimensional visualization essentially improve the diagnostic potential of magnetic resonance imaging.     

Submandibular salivary gland transfer: a pitfall in head and neck imaging with F-18 FDG PET/CT

Xerostomia is a significant morbidity of radiation treatment in the management of head and neck cancers. To preserve salivary function, a surgical technique has been developed that involves the transfer of one submandibular gland to the ipsilateral submental space, where it can be shielded during radiation therapy. F-18 FDG PET/CT imaging characteristics of recently or remotely transferred submandibular glands have not been previously described in the literature. We report 2 cases of patients with surgically transferred submandibular glands, which highlight a potential pitfall in the interpretation of PET/CT of the head and neck region in oncologic patients.     

[11C]PIB, [18F]FDG and MR imaging in patients with mild cognitive impairment

Purpose

Cortical glucose metabolism, brain amyloid β accumulation and hippocampal atrophy imaging have all been suggested as potential biomarkers in predicting which patients with mild cognitive impairment (MCI) will convert to Alzheimer’s disease (AD). The aim of this study was to compare the prognostic ability of [¹¹C]PIB PET, [¹⁸F]FDG PET and quantitative hippocampal volumes measured with MR imaging in predicting conversion to AD in patients with MCI.

Methods

The study group comprised 29 patients with MCI who underwent [¹¹C]PIB PET and MR imaging. Of these, 22 also underwent [¹⁸F]FDG PET. All subjects were invited back for clinical evaluation after 2 years.

Results

During the follow-up time 17 patients had converted to AD while 12 continued to meet the criteria for MCI. The two groups did not differ in age, gender or education level, but the converter group tended to have lower MMSE and Word List learning than the nonconverter group. High [¹¹C]PIB retention in the frontotemporal regions and anterior and posterior cingulate (p?<?0.05) predicted conversion to AD. Also reduced [¹⁸F]FDG uptake in the left lateral temporal cortex (LTC) predicted conversion (p?<?0.05), but quantitative hippocampal volumes did not (p?>?0.1). In receiver operating characteristic (ROC) analysis the measurements that best predicted the conversion were [¹¹C]PIB retention in the lateral frontal cortex and [¹⁸F]FDG uptake in the left LTC. Both PET methods resulted in good sensitivity and specificity and neither was significantly superior to the other.

Conclusion

The findings indicate that [¹¹C]PIB and [¹⁸F]FDG are superior to hippocampal volumes in predicting conversion to AD in patients with MCI.     

特发性肺间质纤维化HRCT病变区与非病变区18F-FDG PET/CT表现分析

目的 对比分析特发性肺间质纤维化（IPF）高分辨率CT（HRCT）上病变区域和非病变区域的PET/CT表现及其诊断价值。 方法 按照IPF的临床诊断标准,选取接受PET/CT检查并有完整资料的IPF病例及健康体检者各27例,规定病变区域为HRCT上表现为磨玻璃密度影、网格影及蜂窝影等区域,非病变区域为肉眼可观察到的密度低于病变区的最小密度区,测定病变区域的SUV_max,分别在IPE组非病变区域和对照组肺部HRCT横断面图像上画取ROI,测量其CT值,并在PET/CT图像相应位置画取ROI,测量SUV_max、平均标准化摄取值（SUV_mean）,计算与纵隔大血管主动脉弓血池（SUV_max、SUV_mean）比值:肺组织/纵隔血池最大摄取比（LT/MB_max）和肺组织/纵隔血池平均摄取比（LT/MB_mean）。采用独立样本t检验比较组间LT/MB_max、LT/MB_mean及CT值差异。 结果 IPF组27例患者,其中肺部表现为磨玻璃密度影14例、网格影27例、蜂窝影13例,同一患者可有多种表现,以上表现均为放射性摄取增高,SUV_max值为2.32±1.10。IPF组非病变区域LT/MB_max（0.44±0.55 vs.0.32±0.05）和LT/MB_mean（0.55±0.38 vs.0.33±0.05）均高于对照组（t=5.87和2.89,P均 < 0.05）;但两组CT值（-836.59±32.33 vs.-837.99±29.90）比较,差异无统计学意义（t=-0.15,P>0.05）。 结论 IPF患者HRCT上显示的病变区与非病变区对18F-FDG摄取均增加,PET/CT在IPF诊断及治疗监测方面有一定优势。     

Toward rapid high resolution in vivo intravascular MRI: evaluation of vessel wall conspicuity in a porcine model using multiple imaging protocols

PURPOSE: To assess magnetic resonance (MR) pulse sequences for high resolution intravascular imaging. MATERIALS AND METHODS: Intravascular imaging of the abdominal aorta and iliac arteries was performed in vivo in a porcine model at 1.5 T using catheter-mounted micro-receive coils. Ten protocols, including spin-echo (SE)-echo planar imaging (SE-EPI), segmented EPI, half-Fourier single-shot turbo spin-echo (HASTE), fast imaging with steady-state free precession (TrueFISP), turbo spin-echo (TSE), and SE acquisition schemes were employed in 13 trials. Images were analyzed by six expert raters with respect to wall-conspicuity, wall-to-lumen/tissue contrast, visible layers of the arterial wall, anticipated clinical usefulness, and overall image quality. Mean differences between sequence-types were evaluated using analysis of variance (ANOVA) between groups with planned comparisons. RESULTS: The vessel wall was delineated in almost all protocols. Motion artifacts from physiological and device motion were reduced in fast techniques. The best contrast between the wall and surrounding tissue was provided by a HASTE protocol. Anatomic layers of the vessel wall were best depicted on dark blood T2-weighted TSE. Overall, TrueFISP was ranked highest on the remaining measures. CONCLUSION: Dedicated catheter-coils combined with fast sequences have potential for in vivo characterization of vessel walls. TrueFISP offered the best overall image quality and acquisition speed, but suffered from the inability to delineate the multiple layers of the wall, which seems associated with dark blood- and T2-weighted contrast. We believe future intra-arterial trials should proceed from this study in normal artery imaging and initially focus on fast T2-weighted dark blood techniques in trials with pathology.     

Multi-detector CT (MDCT) evaluation in interstitial lung disease (ILD): Comparison of MinIP and volumetric high resolution CT (HRCT) images

The aim of the study

Is to compare the role of minimum intensity projection (MinIP) images with that of volumetric high resolution computed tomography (HRCT) images in the diagnosis of interstitial lung diseases (ILD).

First evaluation of a 99mTc-tricarbonyl complex, 99mTc(CO)3(LAN), as a new renal radiopharmaceutical in humans.

(99m)Tc-Mercaptoacetyltriglycine ((99m)Tc-MAG3), (99m)Tc-dd- and ll-ethylene-dicysteine ((99m)Tc-EC), and (99m)Tc-mercaptoacetamide-ethylene-cysteine ((99m)Tc-MAEC) contain N(3)S or N(2)S(2) ligands designed to accommodate the 4 ligating sites of the ((99m)TcO)(3+) core; they are all excellent renal imaging agents but have renal clearances lower than that of (131)I-orthoiodohippurate ((131)I-OIH). To explore the potential of the newly accessible but less polar [(99m)Tc(CO)(3)](+) core with 3 ligating sites, we decided to build on the success of (99m)Tc-EC, with its N(2)S(2) ligand and 2 dangling carboxylate groups; we chose an N(2)S ligand that also has 2 dangling carboxylate groups, lanthionine, to form (99m)Tc(CO)(3)(LAN), a new renal radiopharmaceutical. METHODS: Biodistribution studies were performed on Sprague-Dawley rats with (99m)Tc(CO)(3)(LAN) isomers, meso-LAN and dd,ll-LAN (an enantiomeric mixture), coinjected with (131)I-OIH. Human studies also were performed by coinjecting each (99m)Tc-labeled product ( approximately 74 MBq [ approximately 2 mCi]) and (131)I-OIH ( approximately 7.4 MBq [ approximately 0.2 mCi]) into 3 healthy volunteers and then performing dual-isotope imaging by use of a camera system fitted with a high-energy collimator. Blood samples were obtained from 3 to 90 min after injection, and urine samples were obtained at 30, 90, and 180 min. RESULTS: Biodistribution studies in rats revealed rapid blood clearance as well as rapid renal extraction for both preparations, with the dose in urine at 60 min averaging 88% that of (131)I-OIH. In humans, both agents provided excellent renal images, with the plasma clearance averaging 228 mL/min for (99m)Tc(CO)(3)(meso-LAN) and 176 mL/min for (99m)Tc(CO)(3)(dd,ll-LAN). At 3 h, both (99m)Tc(CO)(3)(meso-LAN) and (99m)Tc(CO)(3)(dd,ll-LAN) showed good renal excretion, averaging 85% and 77% that of (131)I-OIH, respectively. Plasma protein binding was minimal (10% and 2%, respectively), and erythrocyte uptake was similar (24% and 21%, respectively) for (99m)Tc(CO)(3)(meso-LAN) and (99m)Tc(CO)(3)(dd,ll-LAN). CONCLUSION: Although the plasma clearance and the rate of renal excretion of the (99m)Tc(CO)(3)(LAN) complexes were still lower than those of (131)I-OIH, the results of this first application of a (99m)Tc-tricarbonyl complex as a renal radiopharmaceutical in humans demonstrate that (99m)Tc(CO)(3)(LAN) complexes are excellent renal imaging agents and support continued renal radiopharmaceutical development based on the (99m)Tc-tricarbonyl core.     

Hyperpolarized 3helium magnetic resonance ventilation imaging of the lung in cystic fibrosis: comparison with high resolution CT and spirometry

The purpose of this study was to compare hyperpolarized ³helium magnetic resonance imaging (³He MRI) of the lungs in adults with cystic fibrosis (CF) with high-resolution computed tomography (HRCT) and spirometry. Eight patients with stable CF prospectively underwent ³He MRI, HRCT, and spirometry within 1 week. Three-dimensional (3D) gradient-echo sequence was used during an 18-s breath-hold following inhalation of hyperpolarized ³He. Each lung was divided into six zones; ³He MRI was scored as percentage ventilation per lung zone. HRCT was scored using a modified Bhalla scoring system. Univariate (Spearman rank) and multivariate correlations were performed between ³He MRI, HRCT, and spirometry. Results are expressed as mean±SD (range). Spirometry is expressed as percent predicted. There were four men and four women, mean age=31.9±9 (20–46). Mean forced expiratory volume in 1 s (FEV)₁=52%±29 (27–93). Mean ³He MRI score=74%±25 (55–100). Mean HRCT score=48.8±24 (13.5–83). The correlation between³He MRI and HRCT was strong (R=±0.89, p<0.001). Bronchiectasis was the only independent predictor of ³He MRI; ³He MRI correlated better with FEV₁ and forced vital capacity (FVC) (R=0.86 and 0.93, p<0.01, respectively) than HRCT (R=±0.72 and ±0.81, p<0.05, respectively). This study showed that ³He MRI correlates strongly with structural HRCT abnormalities and is a stronger correlate of spirometry than HRCT in CF.     

The clinical usefulness of F-18 FDG coincidence PET without attenuation correction and without whole-body scanning mode in pulmonary lesions comparison with CT, MRI, and clinical findings

PURPOSE: This study was undertaken to assess the clinical usefulness of fluorine-18 flurodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomography (PET) of various lung lesions by comparing it with CT, MRI, and clinical findings. MATERIALS AND METHODS: Forty-two patients with pulmonary lesions underwent CoDe PET using a dual-head gamma camera equipped with a 5/8 inch thick NaI (Tl) crystals. The patients were prepared for the study by overnight fasting. Data was acquired at approximately 1 hour after the intravenous injection of 111 to 370 MBq (3 to 10 mCi) of F-18 FDG. A spinal scan of the thorax was performed using a slip ring gantry for 30 minutes. After rebinning, routine tomographic slices were reconstructed without attenuation correction and the images were analyzed visually. RESULTS: Pathologic diagnoses and staging were obtained at surgery in nine patients; in the remaining 33 patients, aspiration cytology was available. CoDe PET detected all 35 pathologically proved malignant lesions. In nine patients who underwent surgery, seven CoDe PET studies corresponded with pathologic staging, whereas in six of the nine patients, CT and MRI corresponded with the pathologic findings. Seven patients also had benign lesions that showed FDG uptake. CONCLUSIONS: F-18 FDG CoDe PET was sensitive in the evaluation of lung lesions but was not specific for malignancy. F-18 FDG CoDe PET was more sensitive than CT and MRI in nodal staging in the limited number of patients studied thus far.     

动态比浊法鲎试验定量测定~(18)F-FDG的细菌内毒素含量

目的　快速测定18F 脱氧葡萄糖 (FDG)的细菌内毒素含量。方法　应用动态比浊法鲎试验 ,经抑制 /增强实验表明 ,18F FDG(Lot No 0 0 0 113)未稀释、2、5、10倍稀释样品中定量添加标准浓度内毒素 ,其回收率分别为 176% ,131% ,131% ,15 0 % ;18F FDG(Lot No 99112 8、9912 0 8)经 10倍稀释 ,样品中定量添加标准浓度内毒素 ,其回收率分别为 80 2 %和 98 2 %。结果　标准内毒素使用 5 0 0、0 5 0 0、0 0 5 0 0EU/mL ,将18F FDG进行 10倍稀释 ,样品中定量添加标准浓度内毒素回收率在 5 0 %～2 0 0 % ,无干扰作用 ,可用于有效的日常检查。结论　所用方法可高效率地测定18F FDG中的细菌内毒素含量。     

Quantitative evaluation of myocardial blood flow and ejection fraction with a single dose of (13)NH(3) and Gated PET.

To evaluate myocardial blood flow (MBF) and cardiac function with a single dose of (13)NH(3), electrocardiographically (ECG) gated PET acquisition was performed after a dynamic PET scan was obtained. Gated blood-pool (GBP) imaging with C(15)O PET was also performed to compare the left ventricular ejection fraction (LVEF) obtained using the 2 methods. METHODS: Six healthy volunteers and 34 patients with cardiovascular disease were studied. Each subject underwent dynamic PET scanning after a slow intravenous injection of approximately 740 MBq (13)NH(3), followed by ECG gated PET scanning. MBF images were calculated by the Patlak plot method. Before obtaining the (13)NH(3) scan, the GBP image was obtained with a bolus inhalation of C(15)O. Twenty patients also underwent left ventriculography (LVG) to compare the value of the LVEF obtained using this technique with that determined using the gated PET method. RESULTS: The mean regional value of MBF calculated for healthy volunteers in the resting condition was 0.61 +/- 0.10 mL/min/g. The LVEF obtained using GBP PET (EF(CO)) was consistent with that obtained using LVG. The LVEF calculated from gated (13)NH(3) scans (EF(NH3)) correlated well with EF(CO), although EF(NH3) slightly underestimated the LVEF (EF(NH3) = 0.97. EF(CO) - 2.94; r = 0.87). EF(NH3) was significantly different from EF(CO) in patients with a perfusion defect in the cardiac wall (EF(NH3) = 39% +/- 11% vs. EF(CO) = 45% +/- 11%; n = 19; P < 0.001), whereas no significant difference was found between them in subjects with no defect (EF(NH3) = 58% +/- 13% vs. EF(CO) = 61% +/- 10%; n = 21). CONCLUSION: Gated PET acquisition accompanied by obtaining a dynamic PET scan with a single dose of (13)NH(3) is a promising method for the simultaneous clinical evaluation of MBF and cardiac function. However, in patients with a defect in the cardiac wall, EF(NH3) showed a tendency to underestimate the EF compared with EF(CO).     

Preparation of 99mTc(CO)3-Carboxymethylthioethyl iminodiacetic acid and evaluation as a potential renal imaging agent

The ligand, carboxymethylthioethyl iminodiacetic acid (CMT-IDA) has a suitable array of donor atoms for coordination with [99mTc(CO)3]+ core, wherein the resultant complex is expected to possess free carboxylic residues contributing towards hydrophilicity of the complex. The aim of the studies was to study the renal clearance of 99mTc(CO)3- labeled CMT-IDA and determine the potential of the complex towards its use as a renal tubular imaging agent. Methods: CMT-IDA was radiolabeled with the [99mTc(CO)3(H2O)3]+ precursor and was characterized by reverse phase HPLC gradient elution system. Stability, hydrophilicity and plasma protein binding studies were carried out for the complex. Biodistribution studies were carried out in normal male Swiss mice at 10 min.p.i. and 2 h.p.i. The clearance was estimated from the activity observed in the urinary bladder by tying the urethra prior to injection of the complexes under study. Imaging studies were performed with male Swiss mice administered with [99mTc(CO)3(CMT-IDA)]-2 at 30 min. p.i. and blocking studies were carried out by intraperitoneal injection of probenecid 10 min. prior to the injection of the radiotracer. Results: [99mTc(CO)3(CMT-IDA)]-2 could be obtained in > 98% radiochemical purity. The complex showed renal clearance of 71.0? 5.9% ID at 10 min.p.i. which increased to 84.1? 10.6% ID at 2 h.p.i., with no major activity in blood, liver, heart, lungs, stomach and spleen. However, the intestinal uptake was high (10.3? 2.0% ID) at 2 h.p.i. Scintigraphic image of the animal injected with probenecid showed an increase in the activity in kidneys indicating excretion of the [99mTc(CO)3(CMT-IDA)]-2 complex via tubular pathway. Conclusion: The complex, [99mTc(CO)3(CMT-IDA)]-2 has shown excellent renal clearance and thereby can be explored further for potential use as an agent towards assessing effective renal plasma flow.     

A multicenter clinical trial on the diagnostic value of dual-tracer PET/CT in pulmonary lesions using 3'-deoxy-3'-18F-fluorothymidine and 18F-FDG.

Some new radiotracers might add useful information and improve diagnostic confidence of (18)F-FDG imaging in tumors. A multicenter clinical trial was designed to investigate the diagnostic performance of dual-tracer ((18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine [(18)F-FLT]) PET/CT in pulmonary nodules. METHODS: Fifty-five patients underwent dual-tracer imaging in 6 imaging centers using the same models of equipment and standardized protocols. The images were interpreted by a collective group of readers who were unaware of the clinical data. The diagnostic performance using either tracer alone or dual-tracers together, with or without CT, was compared. The histological diagnosis or clinical findings in a 12-mo follow-up period served as the standard of truth. RESULTS: In 16 patients with malignant tumor, 16 with tuberculosis, and 23 with other benign lesions, the sensitivity and specificity of (18)F-FDG and (18)F-FLT were 87.5% and 58.97% and 68.75% and 76.92%, respectively. The combination of dual-tracer PET/CT improved the sensitivity and specificity up to 100% and 89.74%. The 3 subgroups of patients could be best separated when the (18)F-FLT/(18)F-FDG standardized uptake value ratio of 0.4-0.90 was used as the threshold. CONCLUSION: By reflecting different biologic features, the dual-tracer PET/CT using (18)F-FDG and (18)F-FLT favorably affected the diagnosis of lung nodules.