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Purpose To assess 18F-Fluoroethylcholine (18F-FEC) as a PET/MRI tracer in the evaluation of breast lesions, breast cancer aggressiveness, and prediction of lymph node status. Materials and methods This prospective, monocentric study was approved by the ethics committee and patients gave written, informed consent. This clinical trial was registered in the EudraCT database (Number 2017-003089-29). Women who presented with suspicious breast lesions were included. Histopathology was used as reference standard. Simultaneous 18F-FEC PET/MRI of the breast was performed in a prone position with a dedicated breast coil. MRI was performed using a standard protocol before and after contrast agent administration. A simultaneous read by nuclear medicine physicians and radiologists collected the imaging data of MRI-detected lesions, including the maximum standardized 18F-FEC-uptake value of breast lesions (SUVmaxT) and axillary lymph nodes (SUVmaxLN). Differences in SUVmax were evaluated with the Mann–Whitney U test. To calculate diagnostic performance, the area under the receiver operating characteristics curve (ROC) was used. Results There were 101 patients (mean age 52.3 years, standard deviation 12.0) with 117 breast lesions included (30 benign, 7 ductal carcinomas in situ, 80 invasive carcinomas). 18F-FEC was well tolerated by all patients. The ROC to distinguish benign from malignant breast lesions was 0.846. SUVmaxT was higher if lesions were malignant (p p = 0.011), and were HER2-positive (p = 0.041). SUVmaxLN was higher in metastatic lymph nodes, with an ROC of 0.761 for SUVmaxT and of 0.793 for SUVmaxLN. Conclusion Simultaneous 18F-FEC PET/MRI is safe and has the potential to be used for the evaluation of breast cancer aggressiveness, and prediction of lymph node status.

Objectives Content-based image retrieval systems (CBIRS) are a new and potentially impactful tool for radiological reporting, but their clinical evaluation is largely missing. This study aimed at assessing the effect of CBIRS on the interpretation of chest CT scans from patients with suspected diffuse parenchymal lung disease (DPLD). Materials and methods A total of 108 retrospectively included chest CT scans with 22 unique, clinically and/or histopathologically verified diagnoses were read by eight radiologists (four residents, four attending, median years reading chest CT scans 2.1± 0.7 and 12 ± 1.8, respectively). The radiologists read and provided the suspected diagnosis at a certified radiological workstation to simulate clinical routine. Half of the readings were done without CBIRS and half with the additional support of the CBIRS. The CBIRS retrieved the most likely of 19 lung-specific patterns from a large database of 6542 thin-section CT scans and provided relevant information (e.g., a list of potential differential diagnoses). Results Reading time decreased by 31.3% (p < 0.001) despite the radiologists searching for additional information more frequently when the CBIRS was available (154 [72%] vs. 95 [43%], p < 0.001). There was a trend towards higher overall diagnostic accuracy (42.2% vs 34.7%, p = 0.083) when the CBIRS was available. Conclusion The use of the CBIRS had a beneficial impact on the reading time of chest CT scans in cases with DPLD. In addition, both resident and attending radiologists were more likely to consult informational resources if they had access to the CBIRS. Further studies are needed to confirm the observed trend towards increased diagnostic accuracy with the use of a CBIRS in practice. Key Points • A content-based image retrieval system for supporting the diagnostic process of reading chest CT scans can decrease reading time by 31.3% (p < 0.001). • The decrease in reading time was present despite frequent usage of the content-based image retrieval system. • Additionally, a trend towards higher diagnostic accuracy was observed when using the content-based image retrieval system (42.2% vs 34.7%, p = 0.083).

CA II makes a good PET: Discovering positron emission tomography (PET) probes with high target affinities is challenging. PET probe discovery using in situ click chemistry uses (19) F-bearing fragments as (18) F surrogates. This ensures that the lead hits and PET probes have equivalent chemical or biological characteristics, making PET probe discovery predictable and reliable.

We investigated the impact of 18F-DOPA brain PET/CT on the clinical management of patients with known or suspected brain tumors. Methods: A prospective survey of referring physicians was conducted. A pre-PET questionnaire inquired about indication, tumor histology or grade, level of suspicion for tumor recurrence, and planned management. Early post-PET questionnaires asked referring physicians to categorize PET findings as negative, equivocal, or positive; assessed the level of suspicion for primary or recurrent brain tumor; and recorded intended management changes prompted by PET findings. A late follow-up questionnaire 6 mo after the scan aimed at determining patient outcome (recurrence, survival). In addition, all referring physicians were contacted to determine whether management changes intended after 18F-DOPA PET/CT were implemented. Results: Fifty-eight consecutive patients were included. The clinical suspicion for recurrence increased in 33%, remained unchanged in 50%, and decreased in 17% of patients after adding the PET/CT result to the available diagnostic data. The late post-PET questionnaire confirmed recurrence in 26 patients whereas 32 had stable disease or remained disease-free. 18F-DOPA PET/CT resulted in intended management changes in 41% of patients. Changes in intended management from wait and watch to chemotherapy (6 patients [25%]) and from chemotherapy to wait and watch (4 patients [17%]) occurred most frequently. Clinical follow-up revealed that 75% of intended treatment changes were implemented. Conclusion:18F-DOPA PET/CT changed the intended management of 41% of patients with brain tumors, and intended management changes were implemented in 75% of these. These changes suggest a potentially important clinical role of imaging amino acid transport in the management of brain tumor patients.

6-(18)F-fluoro-l-dopa ((18)F-FDOPA) measured with PET as a biomarker of amino acid uptake has been investigated in brain tumor imaging. The aims of the current study were to determine whether the degree of (18)F-FDOPA uptake in brain tumors predicted tumor grade and was associated with tumor proliferative activity in newly diagnosed and recurrent gliomas.Fifty-nine patients (40 men, 19 women; mean age ± SD, 44.4 ± 12.3 y) with newly diagnosed (n = 22) or recurrent (n = 37) gliomas underwent (18)F-FDOPA PET perioperatively. Tumor tissue was obtained by resection or biopsy in all patients. The tumor grade and Ki-67 proliferation index were obtained by standard pathology assays. Tumor (18)F-FDOPA uptake was quantified by determining various standardized uptake value (SUV) parameters (mean SUV, maximum SUV [SUVmax], mean values of voxels with top 20% SUVs, and tumor-to-normal-brain tissue ratios) that were then correlated with histopathologic grade and Ki-67 proliferation index.Fifty-nine lesions in 59 patients were analyzed. (18)F-FDOPA uptake was significantly higher in high-grade than in low-grade tumors for newly diagnosed tumors (SUVmax, 4.22 ± 1.30 vs. 2.34 ± 1.35, P = 0.005) but not for recurrent tumors that had gone through treatment previously (SUVmax, 3.36 ± 1.26 vs. 2.67 ± 1.18, P = 0.22). An SUVmax threshold of 2.72 differentiated low-grade from high-grade tumors, with a sensitivity and specificity of 85% and 89%, respectively, using receiver-operating-characteristic curve analysis (area under the curve, 0.86). (18)F-FDOPA PET uptake correlated significantly with Ki-67 tumor proliferation index in newly diagnosed tumors (r = 0.66, P = 0.001) but not in recurrent tumors (r = 0.14, P = 0.41).(18)F-FDOPA uptake is significantly higher in high-grade than in low-grade tumors in newly diagnosed but not recurrent tumors that had been treated previously. A significant correlation between (18)F-FDOPA uptake and tumor proliferation in newly diagnosed tumors was observed, whereas this correlation was not identified for recurrent tumors. Thus, (18)F-FDOPA PET might serve as a noninvasive marker of tumor grading and might provide a useful surrogate of tumor proliferative activity in newly diagnosed gliomas.

Background 18 F-FDG PET has a high accuracy for re-staging of head and neck cancer. The purpose of this study was to determine whether the diagnostic accuracy can be further improved with integrated PET/CT. Materials and methods Forty-nine patients with a mean age of 59±18 years were studied retrospectively. Histo-pathological verification was available either from complete tumor resection with or without lymph node dissection ( n =27) or direct endoscopic biopsy ( n =16) or ultrasound guided biopsy ( n =6). Two reviewers blinded to the pathological findings read all PET images in consensus. An experienced radiologist was added for the interpretation of the PET/CT images. Results Tissue verification was available for 110 lesions in 49 patients. Sixty-seven lesions (61%) were biopsy positive and 43 (39%) were negative for malignant disease. PET and PET/CT showed an overall accuracy for cancer detection of 84 and 88% ( p =0.06), respectively. Sensitivity and specificity for PET were 78 and 93% versus 84 ( p =NS) and 95% ( p =NS) with PET/CT. A patient-by-patient analysis yielded a sensitivity, specificity and accuracy for PET of 80, 56 and 76%, compared to 88% ( p =NS), 78% ( p =NS) and 86% ( p =0.06) for PET/CT. Conclusion The results of this study indicate that PET/CT does not significantly improve the detection of recurrence of head and neck cancer. However, a trend towards improved accuracy was observed ( p =0.06).

Inhibitors of the kinase mammalian target of rapamycin (mTOR) have shown sporadic activity in cancer trials, leading to confusion about the appropriate clinical setting for their use. Here we show that loss of the Von Hippel-Lindau tumor suppressor gene (VHL) sensitizes kidney cancer cells to the mTOR inhibitor CCI-779 in vitro and in mouse models. Growth arrest caused by CCI-779 correlates with a block in translation of mRNA encoding hypoxia-inducible factor (HIF1A), and is rescued by expression of a VHL-resistant HIF1A cDNA lacking the 5' untranslated region. VHL-deficient tumors show increased uptake of the positron emission tomography (PET) tracer fluorodeoxyglucose (FDG) in an mTOR-dependent manner. Our findings provide preclinical rationale for prospective, biomarker-driven clinical studies of mTOR inhibitors in kidney cancer and suggest that FDG-PET scans may have use as a pharmacodynamic marker in this setting.

Purpose To compare the diagnostic accuracy of positron emission tomography (PET) and integrated PET/CT and to evaluate the performance of software fusion for staging of non-small cell lung cancer (NSCLC). Methods Thirty-six patients (17 men and 19 women) with NSCLC underwent staging with integrated PET/CT followed by mediastinal lymph node dissection and tumor resection. Twenty-five of the 36 patients (69%) underwent separate CT studies for software fusion of images. Two blinded reviewers analyzed in consensus all PET images, and an experienced radiologist was added to assess integrated and software-fused PET/CT images. Histopathologic findings served as "gold standard" for determining the diagnostic accuracy of all modalities. Results Reviewers examining PET and integrated PET/CT classified T stage accurately in 67% (20 of 30 patients) and 97% (29 of 30 patients), respectively (p Conclusions Integrated PET/CT compared with PET alone was associated with 26% points-greater overall diagnostic accuracy (p = 0.01). The software fusion method failed to provide acceptable coregistration in > 30% of the patients.

An increased uptake of bone-seeking radiopharmaceuticals into malignant bone lesipns could further improve the diagnostic accuracy of routine bone scanning. The tracers used in clinical routine for bone scanning are methylene-diphosphonate (MDP), dicarboxypropane-diphosphonate (DPD) and ethylenediaminetetramethylene-phosphonate (EDTMP). MDP and DPD are usually labelled with 9 9 m Tc for diagnostic use, whereas EDTMP is labelled with 1 5 3 Sm for therapeutic purposes. this study aimed to compare, for the first time, bone scanning with an improved preparation of 9 9 m Tc-EDTMP (by the addition of rhenium) (carrier-added) with 9 9 m Tc-DPD. Twenty malignant bone lesions were investigated in 10 patients. The ratios of bone lesion to soft tissue (BL/ST) and of bone lesion to normal bone (BL/NB) were compared 3 h after the injection of either compound. Quantitative analysis demonstrated a significant (P < 0.05) difference in BL/ST ratio In favour of 9 9 m Tc-DPD. The BL/ NB ratio was not significantly different. Visual image analysis resulted in a clinically comparable interpretation of imaging studies with the use of 9 9 m Tc-DPD and carrier-added 9 9 m Tc-EDTMP. These preliminary data support the concept of carrier addition to increase bone uptake by the modification of the complex structure of 9 9 m Tc-EDTMP. However, any advantage over conventional 9 9 m Tc-based tracers for bone scintigraphy in clinical use needs to be demonstrated in controlled trials.

Summary objectives Hashimoto's encephalitis is a term which describes encephalopathy associated with autoimmune thyroiditis, but it is not based on evidence, whether Hashimoto's encephalitis is a distinct clinical entity by itself. In previously reported cases of Hashimoto's encephalitis, abnormal brain perfusion studies have been reported. The aim of this study was to evaluate the prevalence of brain perfusion abnormalities in euthyroid patients with autoimmune thyroiditis. methods 99mTc Ethyl cystein dimer (ECD) single photon emission computed tomography (SPECT) studies were performed in a study group of 41 euthyroid patients with autoimmune thyroiditis and a matched control group of 35 healthy individuals. All study participants had a normal neurological investigation and a detailed neurological history taking. Individuals with known or suspected morphological brain abnormalities were excluded from the study. Zung's Self-Rating Anxiety Scale (SAS) and Zung's Self-Rating Depression Scale (SDS) were used to detect depression and mood disorders. Automatic quantification of perfusion was performed with both a voxel-based analysis as well as a volume-of-interest (VOI) based analysis of 46 predefined cortical and subcortical regions. The findings from both groups were compared to a reference template. results In the voxel-based analysis, there was a significant difference between patients and controls in the mean volume of perfusion defects deviating 2SD below the normal values (21·8 ml vs. 10·4 ml; P = 0·02). Hyperperfused areas, however, did not differ significantly between study patients and controls. A significant correlation of the perfusion defects with time since diagnosis of autoimmune thyroiditis was seen (r = 0·42). In the VOI-based analysis, abnormal regions were more frequent in the study group when compared to controls (P

Impairment of the lacrimal glands after external radiation has been well documented, but there are only a few reports on the effects of radioiodine therapy on the lacrimal glands. Long-term effects of high-dose radioiodine therapy on tear secretion have not previously been studied. We investigated 175 eyes of 88 patients with a history of radioiodine therapy for thyroid carcinoma (68 females, 20 males; mean age 55±16 years, range 17–81 years) and compared them with a sex- and age-matched control group (n=39). All patients had been given at least 2.96 GBq iodine-131 (maximal administered activity 22.3 GBq 131I). An ophthalmological investigation was performed 64±71 months (range 3–317 months) after initial radioiodine therapy by a single ophthalmologist. Lacrimal gland function was evaluated with three different function tests. External eye morphology was considered, and detailed ophthalmological history-taking was performed. Patients with factors known to affect lacrimal gland function (contact lenses, autoimmune disorders, history of additional radiation exposure) were excluded from the study. A total of 81 patients (92%) had at least one abnormal function test indicating impaired lacrimal gland function. Schirmer's tear test was decreased (

Summary objective Surgery of bone metastases from differentiated thyroid carcinoma seems indicated in individual patients. This study was performed (1) to analyse retrospectively patients with bone metastases from differentiated thyroid carcinoma and (2) to evaluate the impact of surgery of bone metastases on survival. patients and design We analysed 41 consecutive patients with bone metastases from differentiated thyroid carcinoma who had undergone thyroid surgery at Vienna University Hospital since 1966. The median follow-up time was 12 years. There were 24 females and 17 males with a mean age of 60 ± 12 years. Primary tumour histology was follicular in 35 and papillary in six patients. Radioiodine treatment was performed in 32 with a mean administered activity of 27 ± 24 GBq 131I. Metastases restricted to the skeleton were found in 22 whereas in 19 individuals additional extraskeletal distant metastases were seen. Twenty-seven patients had multiple bone metastases. In 21 individuals, up to five bone metastases were surgically removed with the intention of cure. results Univariate analysis identified total thyroidectomy (P = 0·003), lymph node surgery (P = 0·001), radioiodine therapy (P = 0·036), and the absence of extraskeletal distant metastases (P = 0·017) as significant predictors of survival. Multivariate analysis failed to identify significant prognostic factors. In the subgroup of patients with distant metastases limited to the bones, univariate analysis identified, in addition to thyroid and lymph node surgery, the surgical extirpation of the bone metastases as a significant prognostic factor associated with improved survival (P = 0·025). conclusions These findings indicate that in patients without additional extraskeletal distant metastases, the radical surgical extirpation of bone metastases from differentiated thyroid carcinoma might be associated with improved survival.

Purpose Deoxycytidine kinase (dCK) is a rate-limiting enzyme in deoxyribonucleoside salvage, a metabolic pathway involved in the production and maintenance of a balanced pool of deoxyribonucleoside triphosphates (dNTPs) for DNA synthesis. dCK phosphorylates and therefore activates nucleoside analogs such as cytarabine, gemcitabine, decitabine, cladribine, and clofarabine that are used routinely in cancer therapy. Imaging probes that target dCK might allow stratifying patients into likely responders and nonresponders with dCK-dependent prodrugs. Here we present the biodistribution and radiation dosimetry of three fluorinated dCK substrates, 18F-FAC, L-18F-FAC, and L-18F-FMAC, developed for positron emission tomography (PET) imaging of dCK activity in vivo. Methods PET studies were performed in nine healthy human volunteers, three for each probe. After a transmission scan, the radiopharmaceutical was injected intravenously and three sequential emission scans acquired from the base of the skull to mid-thigh. Regions of interest encompassing visible organs were drawn on the first PET scan and copied to the subsequent scans. Activity in target organs was determined and absorbed dose estimated with OLINDA/EXM. The standardized uptake value was calculated for various organs at different times. Results Renal excretion was common to all three probes. Bone marrow had higher uptake for L-18F-FAC and L-18F-FMAC than 18F-FAC. Prominent liver uptake was seen in L-18F-FMAC and L-18F-FAC, whereas splenic activity was highest for 18F-FAC. Muscle uptake was also highest for 18F-FAC. The critical organ was the bladder wall for all three probes. The effective dose was 0.00524, 0.00755, and 0.00910 mSv/MBq for 18F-FAC, L-18F-FAC, and L-18F-FMAC, respectively. Conclusion The biodistribution of 18F-FAC, L-18F-FAC, and L-18F-FMAC in humans reveals similarities and differences. Differences may be explained by different probe affinities for nucleoside transporters, dCK, and catabolic enzymes such as cytidine deaminase (CDA). Dosimetry demonstrates that all three probes can be used safely to image the deoxyribonucleoside salvage pathway in humans. Electronic supplementary material The online version of this article (doi:10.1007/s00259-010-1666-z) contains supplementary material, which is available to authorized users.

The aim was to investigate the potential impact of positron emission tomography (PET)/computed tomography (CT) as compared to PET and CT on the staging of patients with indolent lymphoma. PET/CTs from 45 patients with indolent lymphoma undergoing staging or restaging were studied. Clinical follow-up, additional imaging, and histology served as the gold standard. PET/CT correctly diagnosed 92 nodal regions as positive for lymphomatous involvement and 458 as disease free vs 68 and 449 for PET and 64 and 459 for CT, respectively. The respective sensitivities, specificities, and accuracies were 99%, 100%, and 99.8% for PET/CT, 68%, 97.5%, and 92.2% for PET, and 70%, 100%, and 94.7% for CT. PET/CT performed significantly better than PET (p

PURPOSE: Gefitinib, an inhibitor of the epidermal growth factor receptor-tyrosine kinase (EGFR-TK), has shown potent effects in a subset of patients carrying specific EGFR-TK mutations in advanced non-small-cell lung cancer. In this study, we asked whether PET with [(18)F]gefitinib may be used to study noninvasively the pharmacokinetics of gefitinib in vivo and to image the EGFR status of cancer cells. MATERIALS AND METHODS: Synthesis of [(18)F]gefitinib has been previously described. The biodistribution and metabolic stability of [(18)F]gefitinib was assessed in mice and vervet monkeys for up to 2 h post injection by both micropositron emission tomography (PET)/computed tomography (CT) scans and postmortem ex vivo tissue harvesting. Uptake levels of radiolabeled gefitinib in EGFR-expressing human cancer cell lines with various levels of EGFR expression or mutation status were evaluated both in vivo and in vitro. RESULTS: MicroPET/CT scans in two species demonstrated a rapid and predominantly hepatobiliary clearance of [(18)F]gefitinib in vivo. However, uptake levels of radiolabeled gefitinib, both in vivo and in vitro, did not correlate with EGFR expression levels or functional status. This unexpected observation was due to high nonspecific, nonsaturable cellular uptake of gefitinib. CONCLUSION: The biodistribution of the drug analogue [(18)F]gefitinib suggests that it may be used to assess noninvasively the pharmacokinetics of gefitinib in patients by PET imaging. This is of clinical relevance, as insufficient intratumoral drug concentrations are considered to be a factor for resistance to gefitinib therapy. However, the highly nonspecific cellular binding of [(18)F]gefitinib may preclude the use of this imaging probe for noninvasive assessment of EGFR receptor status in patients.

Characterization of a pulmonary lesion is a well-established indication for metabolic imaging with 18F-FDG. There is extensive literature on the use of PET and CT in the characterization of a solitary pulmonary nodule (SPN). The performance of dual-modality imaging with PET/CT for characterizing SPNs was investigated in a clinical referral setting.We performed a retrospective study involving patients referred for SPN characterization with PET/CT between September 2002 and June 2004, for whom a pathologic diagnosis was available. The group consisted of 12 men and 30 women whose age ranged from 35 to 84 y (mean age +/- SD, 67 +/- 11 y). A dual-slice CT/lutetium oxyorthosilicate PET system was used for imaging. CT images were acquired without intravenous contrast. Blinded interpretation was performed by 1 chest radiologist for CT and 2 nuclear medicine physicians for PET. PET/CT images were read in consensus. Lesions were analyzed by location, texture, axial dimension, and metabolic activity and visually scored on a 5-point scale from benign to malignant; the maximum standardized uptake value (SUVmax) was measured.Lesion diameter varied from 7 to 30 mm (mean +/- SD, 15 +/- 6 mm). The SUVmax ranged from 0.5 to 17.2 (mean +/- SD, 3.0 +/- 3.0). SUVmax corrected for lean body mass was 0.4-12.1 (mean +/- SD, 2.1 +/- 2.0). Comparison of CT versus PET versus PET/CT yielded accuracies of 74%, 74%, and 93%, respectively. PET and CT correctly characterized 31 and PET/CT correctly characterized 39 of the 42 lesions as malignant or benign. The sensitivity and specificity for CT, PET, and PET/CT was 93%/31%, 69%/85%, and 97%/85%, respectively. There were significant differences (P0.05) between PET/CT and PET for accuracy, sensitivity, and specificity. Accuracy did not improve by quantitative analysis using an SUVmax cutoff of 2.0 for malignancy. Lean body mass correction of the SUVmax did not change accuracy.PET/CT demonstrates an excellent performance in classifying SPNs as benign or malignant. The combination of anatomic and metabolic imaging is synergistic by maintaining the sensitivity of CT and the specificity of PET, resulting in an overall significantly improved accuracy. Visual interpretation is sufficient for characterizing an SPN. Quantitative analysis does not improve accuracy of PET/CT for SPN characterization.

Small-animal PET scanning with (18)F-FDG is increasingly used in murine models of human diseases. However, the impact of dietary conditions, mode of anesthesia, and ambient temperature on the biodistribution of (18)F-FDG in mice has not been systematically studied so far. The aim of this study was to determine how these factors affect assessment of tumor glucose use by (18)F-FDG PET and to develop an imaging protocol that optimizes visualization of tumor xenografts.Groups of severe combined immunodeficient (SCID) mice were first imaged by microPET with free access to food, at room temperature (20 degrees C), and no anesthesia during the uptake period (reference condition). Subsequently, the impact of (a) fasting for 8-12 h, (b) warming the animals with a heating pad (30 degrees C), and (c) general anesthesia using isoflurane or ketamine/xylazine on the (18)F-FDG biodistribution was evaluated. Subcutaneously implanted human A431 epidermoid carcinoma and U251 glioblastoma cells served as tumor models.Depending on the study conditions, (18)F-FDG uptake by normal tissues varied 3-fold for skeletal muscle, 13-fold for brown adipose tissue, and 15-fold for myocardium. Warming and fasting significantly reduced the intense (18)F-FDG uptake by brown adipose tissue observed under the reference condition and markedly improved visualization of tumor xenografts. Although tumor (18)F-FDG uptake was not above background activity under the reference condition, tumors demonstrated marked focal (18)F-FDG uptake in warmed and fasted animals. Quantitatively, tumor (18)F-FDG uptake increased 4-fold and tumor-to-organ ratios were increased up to 17-fold. Ketamine/xylazine anesthesia caused marked hyperglycemia and was not further evaluated. Isoflurane anesthesia only mildly increased blood glucose levels and had no significant effect on tumor (18)F-FDG uptake. Isoflurane markedly reduced (18)F-FDG uptake by brown adipose tissue and skeletal muscle but increased the activity concentration in liver, myocardium, and kidney.Animal handling has a dramatic effect on (18)F-FDG biodistribution and significantly influences the results of microPET studies in tumor-bearing mice. To improve tumor visualization mice should be fasted and warmed before (18)F-FDG injection and during the uptake period. Isoflurane appears well suited for anesthesia of tumor-bearing mice, whereas ketamine/xylazine should be used with caution, as it may induce marked hyperglycemia.

To compare the diagnostic accuracy of positron emission tomography (PET) and integrated PET/CT and to evaluate the performance of software fusion for staging of non-small cell lung cancer (NSCLC).Thirty-six patients (17 men and 19 women) with NSCLC underwent staging with integrated PET/CT followed by mediastinal lymph node dissection and tumor resection. Twenty-five of the 36 patients (69%) underwent separate CT studies for software fusion of images. Two blinded reviewers analyzed in consensus all PET images, and an experienced radiologist was added to assess integrated and software-fused PET/CT images. Histopathologic findings served as "gold standard" for determining the diagnostic accuracy of all modalities.Reviewers examining PET and integrated PET/CT classified T stage accurately in 67% (20 of 30 patients) and 97% (29 of 30 patients), respectively (p0.05). Overall, interpretations based on PET staged 57% (17 of 30 patients) correctly, over-staged 6 patients (20%), and under-staged 7 patients (23%). Interpretations based on integrated PET/CT correctly staged 83% (25 of 30 patients), over-staged 3 patients (10%), and under-staged 2 patients (7%). The overall staging accuracy of integrated PET/CT was significantly higher than that of PET (p0.05). Automatic software fusion of separately obtained PET and CT studies was successful in 68% of the patients but failed in 32%. In successful software fusion cases, the results of software fusion with regards to T stage and N stage were not different from integrated PET/CT.Integrated PET/CT compared with PET alone was associated with 26% points-greater overall diagnostic accuracy (p = 0.01). The software fusion method failed to provide acceptable co-registration in30% of the patients.

This study was conducted to compare the clinical stage derived from 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) to that of integrated PET/computed tomography (CT) in restaged breast cancer patients.Fifty-eight female patients (age range 29-80 years, mean age +/-SD, 53.3 +/- 11.7 years) underwent PET/CT restaging for breast cancer. Two experienced nuclear medicine physicians interpreted PET images. A radiologist was added for reading PET/CT studies. A patient-based analysis was performed. Histopathological findings, correlative imaging studies, changes in number, size, and hypermetabolic activity of suspicious lesions and/or patient outcome served as standard of reference for determining the diagnostic accuracy of both modalities.PET staged 79.3% (46/58) of the patients correctly, overstaged seven (12.1%), and understaged five patients (8.6%). Integrated PET/CT staged 89.7% (52/58) of the patients correctly, overstaged four (6.9%), and understaged two patients (3.4%). The staging accuracy of PET/CT was not significantly better than that of PET alone (p = 0.059). Lesions exhibiting mild hypermetabolic activity, benign inflammatory lesions, and physiological variants largely explained incorrect PET findings.Integrated PET/CT only marginally improves the restaging accuracy over PET alone (p = 0.059) in breast cancer patients.

The aim of this study was to compare PET with (18)F-FDG PET, in-line PET/CT, and software fusion of independently acquired CT and PET scans for staging of recurrent colorectal cancer (CRC).Fifty-one patients with suspected recurrent CRC were studied with in-line PET/CT. Thirty-four of these patients underwent an additional CT scan of the chest or abdomen within 4 wk of PET/CT. Software fusion of PET and CT was performed using a fully automated, intensity-based algorithm. The accuracy of the coregistration of PET and CT scans was evaluated by measuring the distance between landmarks visible in the PET and CT images. Histologic evaluation and follow-up for 6 mo served as the gold standard for the presence or absence of recurrent CRC.On a patient basis, the accuracy of staging was significantly higher for in-line PET/CT than for PET (88% vs. 71%, P = 0.01). Software fusion of the independently acquired PET and CT images was unsuccessful in 8 patients (24%). In the remaining patients, the mean distance between 62 landmarks visible in PET and CT was 12.9 +/- 7.9 mm, whereas it was only 7.7 +/- 4.7 mm for in-line PET/CT (P0.001).In patients with suspected recurrent CRC, in-line PET/CT significantly improves staging compared with PET alone. Due to its high failure rate, software fusion of independently acquired PET and CT studies cannot be considered to represent an alternative to in-line PET/CT.

High photon attenuation and scatter in obese patients affect image quality. The purpose of the current study was to optimize lutetium orthosilicate (LSO) PET image acquisition protocols in patients weighingor =91 kg (200 lb).Twenty-five consecutive patients (16 male and 9 female) weighingor =91 kg (200 lb; range, 91-168 kg [200-370 lb]) were studied with LSO PET/CT. After intravenous injection of 7.77 MBq (0.21 mCi) of 18F-FDG per kilogram of body weight, PET emission scans were acquired for 7 min/bed position. Single-minute frames were extracted from the 7 min/bed position scans to reconstruct 1-7 min/bed position scans for each patient. Three reviewers independently analyzed all 7 reconstructed whole-body images of each patient. A consensus reading followed in cases of disagreement. Thus, 175 whole-body scans (7 per patient) were analyzed for number of hypermetabolic lesions. A region-of-interest approach was used to obtain a quantitative estimate of image quality.Fifty-nine hypermetabolic lesions identified on 7 min/bed position scans served as the reference standard. Interobserver concordance increased from 64% for 1 min/bed position scans to 70% for 3 min/bed position scans and 78% for 4 min/bed position scans. Concordance rates did not change for longer imaging durations. Region-of-interest analysis revealed that image noise decreased from 21% for 1 min/bed position scans to 14%, 13%, and 11% for, respectively, 4, 5, and 7 min/bed position scans. When compared with the reference standard, 14 lesions (24%) were missed on 1 min/bed position scans but only 2 (3%) on 4 min/bed position scans. Five minute/bed position scans were sufficient to detect all lesions identified on the 7 min/bed position scans.Lesion detectability and reader concordance peaked for 5 min/bed position scans, with no further diagnostic gain achieved by lengthening the duration of PET emission scanning. Thus, 5 min/bed position scans are sufficient for optimal lesion detection with LSO PET/CT in obese patients.

Hashimoto's encephalitis is a term which describes encephalopathy associated with autoimmune thyroiditis, but it is not based on evidence, whether Hashimoto's encephalitis is a distinct clinical entity by itself. In previously reported cases of Hashimoto's encephalitis, abnormal brain perfusion studies have been reported. The aim of this study was to evaluate the prevalence of brain perfusion abnormalities in euthyroid patients with autoimmune thyroiditis.99mTc Ethyl cystein dimer (ECD) single photon emission computed tomography (SPECT) studies were performed in a study group of 41 euthyroid patients with autoimmune thyroiditis and a matched control group of 35 healthy individuals. All study participants had a normal neurological investigation and a detailed neurological history taking. Individuals with known or suspected morphological brain abnormalities were excluded from the study. Zung's Self-Rating Anxiety Scale (SAS) and Zung's Self-Rating Depression Scale (SDS) were used to detect depression and mood disorders. Automatic quantification of perfusion was performed with both a voxel-based analysis as well as a volume-of-interest (VOI) based analysis of 46 predefined cortical and subcortical regions. The findings from both groups were compared to a reference template.In the voxel-based analysis, there was a significant difference between patients and controls in the mean volume of perfusion defects deviating 2SD below the normal values (21.8 ml vs. 10.4 ml; P = 0.02). Hyperperfused areas, however, did not differ significantly between study patients and controls. A significant correlation of the perfusion defects with time since diagnosis of autoimmune thyroiditis was seen (r = 0.42). In the VOI-based analysis, abnormal regions were more frequent in the study group when compared to controls (P0.01) However, no topographic pattern was apparent. Regarding neurological findings, no significant difference was found between study patients and controls. However, both the SAS and SDS scores differed significantly between the two groups, but there was neither a correlation between the two scores and perfusion abnormalities nor an association with depression in our study group.These findings of impaired brain perfusion in patients with autoimmune thyroiditis further strengthen the hypothesis of a possible cerebral involvement in autoimmune thyroiditis in individual cases. The presence of cerebral hypoperfusion suggests a cerebral vasculitis as the most likely pathogenetic model.

Surgery of bone metastases from differentiated thyroid carcinoma seems indicated in individual patients. This study was performed (1) to analyse retrospectively patients with bone metastases from differentiated thyroid carcinoma and (2) to evaluate the impact of surgery of bone metastases on survival.We analysed 41 consecutive patients with bone metastases from differentiated thyroid carcinoma who had undergone thyroid surgery at Vienna University Hospital since 1966. The median follow-up time was 12 years. There were 24 females and 17 males with a mean age of 60 +/- 12 years. Primary tumour histology was follicular in 35 and papillary in six patients. Radioiodine treatment was performed in 32 with a mean administered activity of 27 +/- 24 GBq 131I. Metastases restricted to the skeleton were found in 22 whereas in 19 individuals additional extraskeletal distant metastases were seen. Twenty-seven patients had multiple bone metastases. In 21 individuals, up to five bone metastases were surgically removed with the intention of cure.Univariate analysis identified total thyroidectomy (P = 0.003), lymph node surgery (P = 0.001), radioiodine therapy (P = 0.036), and the absence of extraskeletal distant metastases (P = 0.017) as significant predictors of survival. Multivariate analysis failed to identify significant prognostic factors. In the subgroup of patients with distant metastases limited to the bones, univariate analysis identified, in addition to thyroid and lymph node surgery, the surgical extirpation of the bone metastases as a significant prognostic factor associated with improved survival (P = 0.025).These findings indicate that in patients without additional extraskeletal distant metastases, the radical surgical extirpation of bone metastases from differentiated thyroid carcinoma might be associated with improved survival.