Effective dose of intranasal remimazolam for preoperative sedation in preschool children: a dose-finding study using Dixon's up-and-down method.

Background: Most preschool children are distressed during anesthesia induction. While current pharmacological methods are useful, there is a need for further optimization to an "ideal" standard. Remimazolam is an ultra-short-acting benzodiazepine, and intranasal remimazolam for pre-induction sedation may be promising. Methods: This study included 32 preschool children who underwent short and minor surgery between October 2022 and January 2023. After pretreatment with lidocaine, remimazolam was administered to both nostrils using a mucosal atomizer device. The University of Michigan Sedation Score (UMSS) was assessed for sedation 6, 9, 12, 15, and 20 min after intranasal atomization. We used Dixon's up-and-down method, and probit and isotonic regressions to determine the 50% effective dose (ED50) and 95% effective dose (ED95) of intranasal remimazolam for pre-induction sedation. Results: Twenty-nine pediatric patients were included in the final analysis. The ED50 and ED95 of intranasal remimazolam for successful pre-induction sedation, when processed via probit analysis, were 0.65 (95% confidence interval [CI], 0.59-0.71) and 0.78 mg/kg (95% CI, 0.72-1.07), respectively. In contrast, when processed by isotonic regression, they were 0.65 (95% CI: 0.58-0.72 mg/kg) and 0.78 mg/kg (95% CI: 0.69-1.08 mg/kg), respectively. At 6 min after intranasal remimazolam treatment, 81.2% (13/16) of "positive" participants were successfully sedated with a UMSS ≧ 1. All the "positive" participants were successfully sedated within 9 min. Conclusion: Intranasal remimazolam is feasible for preschool children with a short onset time. For successful pre-induction sedation, the ED50 and ED95 of intranasal remimazolam were 0.65 and 0.78 mg/kg, respectively.

Glial IL-33 signaling through an ST2-to-CXCL12 pathway in the spinal cord contributes to morphine-induced hyperalgesia and tolerance.

Morphine and other opiates are highly effective for treating moderate to severe pain. However, morphine-induced hyperalgesia and analgesic tolerance prevent durable efficacy in patients. Here, we investigated the underlying molecular mechanisms of this phenomenon. We found that repeated subcutaneous injections of morphine in mice increased the abundance of the cytokine interleukin-33 (IL-33) primarily in oligodendrocytes and astrocytes and that of its receptor ST2 mainly in astrocytes. Pharmacological inhibition or knockdown of IL-33 or ST2 in the spinal cord attenuated morphine-induced hyperalgesia and analgesic tolerance in mice, as did global knockout of either Il33 or St2, which also reduced morphine-enhanced astroglial activation and excitatory synaptic transmission. Furthermore, a pathway mediated by tumor necrosis factor receptor­associated factor 6 (TRAF6) and the kinase JNK in astrocytes was required for IL-33­mediated hyperalgesia and tolerance through promoting the production of the chemokine CXCL12 in the spinal cord. The findings suggest that targeting IL-33­ST2 signaling could enable opioids to produce sustained analgesic effects in chronic pain management.

Study on the mechanism of anti-MIRI action of total flavones of Fructus Chorspondiatis by PET/CT imaging.

BACKGROUND: To investigate anti myocardial ischemia/reperfusion injury (MIRI) action of total flavones of Fructus Chorspondiatis (TFFC) in rats by 13N-ammonia micro PET/CT imaging, etc. METHODS: Male Sprague-Dawley rats were randomly divided into 6 groups. Micro PET/CT imaging was performed before and after modeling to calculate the volume (VOI) and SUVmean of myocardial ischemic area. The oxidative stress index [(superoxide dismutase (SOD), malondialdehyde (MDA)] and the marker enzymes [creatine kinase (CK), lactate dehydrogenase (LDH)] of myocardial injury were detected. The pathological changes of myocardial were observed via HE staining. A MIRI model of rat cardiomyocytes in vitro was established, the damage and apoptosis of myocardial cells in each group were observed, and the apoptosis rate of cardiomyocytes was detected. RESULTS: The imaging viscosities of the imaging agents were observed at 24 and 48 h in each group. The VOI of 24 h imaging was (6.33±2.02), (6.01±1.56) and (3.32±0.86) mm3, respectively. The VOI of 48 h imaging was (3.31±1.33), (2.61±1.01) and (1.32±0.58) mm3. The 72 h imaging medium and high dose group recovered, while the low dose group still saw sparseness with (1.26±0.68) mm3 VOI. The ischemic (SUVmean) gradually increased with time. Metabolism gradually recovered (F=121.82, 450.82, 435.75, P<0.05). The three doses of TFFC can eliminate free radicals and reduce the damage of myocardial injury. Amongst them, the high-dose group had a better effect on SOD, and the middle-dose group had a better effect on MDA and LDH. The low-dose group affected CK, and a significant difference was observed compared with the control group (P<0.05). After administration, the morphology of myocardial cells in each dose group was improved to some extent. Nuclear pyknosis, rupture, the apoptosis rate, etc. were significantly reduced, the number of cells increased. The high dose group showed the most obvious improvement. CONCLUSIONS: The PET/CT imaging method can detect non-invasive, in vivo and dynamic MIRI, and can accurately evaluate the protective effect of traditional Mongolian medicine TFFC on MIRI. The Anti-MIRI of TFFC can scavenge free radicals, reduce oxidative stress damage, inhibit apoptosis, affect the activity of related enzymes.

18F-fluorodeoxyglucose positron emission tomography/computed tomography-based radiomic features for prediction of epidermal growth factor receptor mutation status and prognosis in patients with lung adenocarcinoma.

BACKGROUND: To investigate whether radiomic features from (18F)-fluorodeoxyglucose positron emission tomography/computed tomography [(18F)-FDG PET/CT] can predict epidermal growth factor receptor (EGFR) mutation status and prognosis in patients with lung adenocarcinoma. METHODS: One hundred and seventy-four consecutive patients with lung adenocarcinoma underwent (18F)-FDG PET/CT and EGFR gene testing were retrospectively analyzed. Radiomic features combined with clinicopathological factors to construct a random forest (RF) model to identify EGFR mutation status. The mutant/wild-type model was trained on a training group (n=139) and validated in an independent validation group (n=35). The second RF classifier predicting the 19/21 mutation site was also built and evaluated in an EGFR mutation subset (training group, n=80; validation group, n=25). Radiomic score and 5 clinicopathological factors were integrated into a multivariate Cox proportional hazard (CPH) model for predicting overall survival (OS). AUC (the area under the receiver characteristic curve) and C-index were calculated to evaluate the model's performance. RESULTS: Of 174 patients, 109 (62.6%) harbored EGFR mutations, 21L858R was the most common mutation type [55.9% (61/109)]. The mutant/wild-type model was identified in the training (AUC, 0.77) and validation (AUC, 0.71) groups. The 19/21 mutation site model had an AUC of 0.82 and 0.73 in the training and validation groups, respectively. The C-index of the CPH model was 0.757. The survival time between targeted therapy and chemotherapy for patients with EGFR mutations was significantly different (P=0.03). CONCLUSIONS: Radiomic features based on (18F)-FDG PET/CT combined with clinicopathological factors could reflect genetic differences and predict EGFR mutation type and prognosis.

Comparing PET/MRI with PET/CT for Pretreatment Staging of Gastric Cancer.

18F-FDG PET/MRI has been applied to the diagnosis and preoperative staging in various tumor types; however, reports using PET/MRI in gastric cancer are rare because of motion artifacts. We investigated the value of PET/MRI for preoperative staging compared with PET/CT in gastric cancer (GC). Thirty patients with confirmed GC underwent PET/CT and PET/MRI. TNM staging for each patient was determined from the PET/MRI and PET/CT images. The diagnostic performance of PET/MRI and PET/CT was calculated compared with the pathologic TNM stage. The two methods were compared using statistical analyses. The accuracy for T staging between PET/MRI and PET/CT was 76.9% vs. 57.7%, respectively. In T1 and T4a staging, the sensitivity and specificity for PET/MRI vs. PET/CT was 1.0 vs. 0.6 and 1.0 vs. 0.8, respectively. The area under the curve (AUC) for PET/MRI vs. PET/CT was 1.00 vs. 0.78 in the T1 stage, 0.73 vs. 0.66 in the T2 stage, 0.72 vs. 0.57 in the T3 stage, and 0.86 vs. 0.83 in the T4 stage. The accuracy for N staging of PET/MRI vs. PET/CT was 53.9% vs. 34.0%, and that for N0 vs. N+ was 85.0% vs. 77.0%. The sensitivity for PET/MRI in N3 staging was 0.67 and 0 for PET/CT. There was a statistically significant difference in the AUC for N1 staging (PET/MRI vs. PET/CT, 0.63 vs. 0.53, p = 0.03). SUVmax/ADC positively correlated with tumor volume and Ki-67. PET/MRI performs more accurately in TNM staging compared with PET/CT and is optimal for accurate N staging. SUVmax/ADC has positive correlations with tumor volume and Ki-67.

The Value of SPECT/CT in Monitoring Prefabricated Tissue-Engineered Bone and Orthotopic rhBMP-2 Implants for Mandibular Reconstruction.

Bone tissue engineering shows good prospects for mandibular reconstruction. In recent studies, prefabricated tissue-engineered bone (PTEB) by recombinant human bone morphogenetic proteins (rhBMPs) applied in vivo has found to be an effective alternative for autologous bone grafts. However, the optimal time to transfer PTEB for mandibular reconstruction is still not elucidated. Thus, here in an animal experiment of rhesus monkey, the suitable transferring time for PTEB to reconstruct mandibular defects was evaluated by 99mTc-MDP SPECT/CT, and its value in monitoring orthotopic rhBMP-2 implants for mandibular reconstruction was also evaluated. The result of SPECT/CT showed higher 99mTc-MDP uptake, indicating osteoinductivity, in rhBMP-2 incorporated demineralized freeze-dried bone allograft (DFDBA) and coralline hydroxyapatite (CHA) implants than those without BMP stimulation. 99mTc-MDP uptake of rhBMP-2 implant peaked at 8 weeks following implantation while CT showed the density of these implants increased after 13 weeks' prefabrication. Histology confirmed that mandibular defects were repaired successfully with PTEB or orthotopically rhBMP-2 incorporated CHA implants, in accordance with SPECT/CT findings. Collectively, data shows 99mTc-MDP SPECT/CT is a sensitive and noninvasive tool to monitor osteoinductivity and bone regeneration of PTEB and orthotopic implants. The PTEB achieved peak osteoinductivity and bone density at 8 to 13 weeks following ectopic implantation, which would serve as a recommendable time frame for its transfer to mandibular reconstruction.

Can Carrier-Mediated Delivery System Promote the Development of Antisense Imaging?

PURPOSE: We aimed to explore the feasibility of transfection methods for antisense imaging. PROCEDURES: Antisense oligonucleotides (ASON) targeted to the mRNA of hTERT gene were synthesized and labeled with Technetium-99m and fluorescein isothiocyanate (FITC), respectively. Then, ASON was combined with transfection reagent Lipofectamine 2000 and Xfect(TM), named Lipo-ASON and Xfect-ASON, respectively. After transfection, the labeled ASON was characterized in hNPCs-G3 and hRPE cells. Reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were performed to assay the hTERT mRNA and protein levels after hNPCs-G3 cells were incubated with Lipo-ASON, Xfect-ASON, and naked ASON. In addition, Lipo-ASON, Xfect-ASON, and naked ASON were injected into tumor-bearing mice, and the biodistribution in vivo was performed. RESULTS: The presence of two transfection reagents significantly increased intracellular uptake of radiolabeled ASON in both cell lines compared with naked ASON (p < 0.05). However, there was no significant difference in cellular uptake rates of Lipo-ASON and Xfect-ASON between hNPCs-G3 and hRPE cells. In comparison with naked ASON, the fluorescence intensity was strongly enhanced after binding to transfection reagents. Furthermore, the levels of hTERT mRNA and protein were significantly reduced in cells treated with Lipo-ASON and Xfect-ASON (p < 0.05), but naked ASON had no significant effect on hTERT expression level. The biodistribution study indicated that tumor radioactivity uptake of radiolabeled ASON for naked ASON, Lipo-ASON, and Xfect-ASON group was low and shown no significant difference in vivo. CONCLUSIONS: Lipofectamine transfection and Xfect(TM) transfection were not effective delivery methods of ASON for antisense imaging.

Low- and high-frequency transcutaneous electrical acupoint stimulation induces different effects on cerebral µ-opioid receptor availability in rhesus monkeys.

Although systematic studies have demonstrated that acupuncture or electroacupuncture (EA) analgesia is based on their accelerating endogenous opioid release to activate opioid receptors and that EA of different frequencies is mediated by different opioid receptors in specific areas of the central nervous system, there is little direct, real-time evidence to confirm this in vivo. The present study was designed to investigate the effects of transcutaneous electrical acupoint stimulation (TEAS), an analogue of EA, at low and high frequencies on µ-opioid receptor (MOR) availability in the brain of rhesus monkeys. Monkeys underwent 95-min positron emission tomography (PET) with (11) C-carfentanil three times randomly while receiving 0, 2, or 100 Hz TEAS, respectively. Each TEAS was administered in the middle 30 min during the 95-min PET scan, and each session of PET and TEAS was separated by at least 2 weeks. The results revealed that 2 Hz but not 100 Hz TEAS evoked a significant increase in MOR binding potential in the anterior cingulate cortex, the caudate nucleus, the putamen, the temporal lobe, the somatosensory cortex, and the amygdala compared with 0 Hz TEAS. The effect remained after the end of TEAS in the anterior cingulate cortex and the temporal lobe. The selective increase in MOR availability in multiple brain regions related to pain and sensory processes may play a role in mediating low-frequency TEAS efficacy.

[Assessment of hepatic reserve function of cirrhosis liver using dynamic SPECT (99m)Tc-galactosyl human serum albumin scintigraphy].

OBJECTIVE: To evaluate the effectiveness of dynamic SPECT (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy on the assessment of reserve function of cirrhosis liver. METHODS: From January 2010 to December 2011, 55 patients with cirrhosis liver were enrolled in this study. The case numbers of male and female were 43 and 12 respectively and the age was (51 ± 9) years (ranging from 35 to 69 years). After routine biochemistry test, CT scan and (99m)Tc-GSA dynamic SPECT scan were performed in turn using a juxtaposed SPECT/CT system. Then the morphologic volume of liver parenchyma (MLV), functional liver volume (FLV) and the hepatic cell absorption rate constant (GSA-K) were calculated. The correlations between GSA-K and routine biochemistry test, Child-Pugh score, indocyanine green clearance rate (ICG-K) were analyzed. The patients were further divided into 3 groups according to whether there was occlusion or stenosis in the main branch of left portal vein (group 1, n = 5), right portal vein (group 2, n = 13) or not (group 3, n = 37) and the regional hepatic functions index of the 3 groups were compared. RESULTS: The value of FLV of the whole, left and right liver was (594 ± 152) ml, (244 ± 119) ml and (356 ± 171) ml, respectively. There were correlations between GSA-K and total bilirubin, prothrombintime, Child-Pugh score and ICG-K (r = -0.730--0.298, P < 0.05). The FLV and MLV ratios of involved hemiliver to uninvolved hemiliver were 0.09 ± 0.06 and 0.30 ± 0.14 in group 1, 0.57 ± 0.43 and 1.08 ± 0.63 in group 2, 0.71 ± 0.30 and 0.71 ± 0.48 in group 3. The difference in MLV-FLV ratio was signifcant between group 1 and group 3, between group 2 and group 3 (P = 0.000). CONCLUSIONS: The dynamic SPCECT (99m)Tc-GSA scintigraphy can not only assess the whole liver function of cirrhosis liver effectively, but also evaluate the variation of regional liver function accurately.

Hyperaccumulation of (18)F-FDG in order to differentiate solid pseudopapillary tumors from adenocarcinomas and from neuroendocrine pancreatic tumors and review of the literature.

Solid pseudopapillary tumors (SPT) are rare, unique pancreatic tumors with benign entity and low malignant potential. Limited information is available in the literature reporting their accumulation of fluorine-18 fluoro deoxyglucose ((18)F-FDG) using positron emission tomography/computed tomography (PET/CT). The aim of this retrospective study was to define t he uptake-accumulation of (18)F-FDG PET/CT in a comparatively large cohort of SPT, and to compare their uptake with the uptake of (18)F-FDG in pancreatic ductal adenocarcinomas (PAC) and neuroendocrine tumors (PNET). Between June 2007 and January 2013, 18 pathologically proven SPT were identified from the total of patients studied by PET/CT in our Center, including 13 women and 5 men, aging from 23 to 56 years old (mean age, 38.5 years). Malignant SPT was histologically classified using the WHO criteria. Eighty-six PAC patients and 28 PNET patients were also identified and included in this study for comparison. Positron emission tomography results were considered as positive if focal accumulation of (18)F-FDG exceeded the surrounding normal pancreatic tissue. Regions of interest were drawn on the pancreatic lesions, and the maximal standardized uptake values (SUVmax values) were calculated. The mean values of SUVmax were compared with independent-samples t test or with the nonparametric Mann-Whitney U method. Correlation of SUVmax values and tumor size were analyzed in cases of SPT. Receiver operating characteristics (ROC curve) were used to study the efficiency of SUV values for the differential diagnosis between SPT versus (vs) PAC and SPT vs PNET. A value of P<0.05 was considered statistically significant. All SPT cases were (18)F-FDG-PET positive, with SUVmax values ranging from 3.5-18.3. The SUVmax values of SPT had poor correlation with tumor size, and no significant difference by gender and age. Areas under the curve ROC were 0.619 and 0.526, respectively for the differentiation of SPT from PNET and PAC tumors. Five SPT tumors were malignant, and exhibited relatively low (18)F-FDG uptake (SUVmax range, 3.0-4.5) except a tumor after recurrence (SUVmax 17.7). Images of CT were of low dose and thus were not evaluated. In conclusion, our results suggest that SPT benign or malignant are consistently hyperaccumulating (18)F-FDG above SUVmax 3. Differentiation from PAC and PNET if only based on the higher SUVmax values was not possible but if based on lower SUVmax, of ≤2.6 (in 14%) and ≤2.5 (in 21,4%) of PAC and PNET, respectively, these pancreatic tumors could be differentiated from SPT.

The influence of interpreters' professional background and experience on the interpretation of multimodality imaging of pulmonary lesions using 18F-3'-deoxy-fluorothymidine and 18F-fluorodeoxyglucose PET/CT.

OBJECTIVE: Based on the results of a recently accomplished multicenter clinical trial for the incremental value of a dual-tracer (18F-FDG and 18F-FLT), dual-modality (PET and CT) imaging in the differential diagnosis of pulmonary lesions, we investigate some issues that might affect the image interpretation and result reporting. METHODS: The images were read in two separate sessions. Firstly the images were read and reported by physician(s) of the imaging center on completion of each PET/CT scanning. By the end of MCCT, all images collected during the trial were re-read by a collective of readers in an isolated, blinded, and independent way. RESULTS: One hundred sixty two patients successfully passed the data verification and entered into the final analysis. The primary reporting result showed adding 18F-FDG image information did not change the clinical performance much in sensitivity, specifity and accuracy, but the ratio between SUVFLT and SUVFDG did help the differentiation efficacy among the three subgroups of patients. The collective reviewing result showed the diagnostic achievement varied with reading strategies. ANOVA indicated significant differences among (18)F-FDG, (18)F-FLT in SUV (F = 14.239, p = 0.004). CT had almost the same diagnostic performance as 18F-FLT. When the 18F-FDG, 18F-FLT and CT images read in pair, both diagnostic sensitivity and specificity improved. The best diagnostic figures were obtained in full-modality strategy, when dual-tracer PET worked in combination with CT. CONCLUSIONS: With certain experience and training both radiologists and nuclear physicians are qualified to read and to achieve the similar diagnostic accuracy in PET/CT study. Making full use of modality combination and selecting right criteria seems more practical than professional back ground and personal experience in the new hybrid imaging technology, at least when novel tracer or application is concerned.

A pilot study on diagnosis of coronary artery disease using computed tomography first-pass myocardial perfusion imaging at rest.

BACKGROUND: Although computed tomography coronary angiography (CTCA) can identify coronary stenosis, little data exists on the ability of multislice computed tomography (MSCT) to detect myocardial perfusion defects at rest. METHODS: In 33 patients with diagnosed or suspected coronary artery disease (CAD), CTCA using retrospective electrocardiography (ECG) gating at rest and invasive coronary angiography (ICA) was performed. The 2D myocardial images were reconstructed in diastolic and systolic phases using the same raw data for CTCA. CT values of the myocardium were used as an estimate of myocardial enhancement, which were shown by color mapping. Myocardial ischemia was defined as a pattern of transient endocardial hypo-enhancement at systole and normal enhancement at diastole. The results of ICA were taken as the reference standard. RESULTS: When a diameter reduction of more than 50% in ICA was used as diagnostic criteria of CAD, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT first-pass myocardial perfusion imaging (MPI) at rest were 0.85, 0.67, 0.92, and 0.50 per patient, respectively, and 0.58, 0.93, 0.85, and 0.76 per vessel, respectively. CONCLUSIONS: CT first-pass MPI at rest could detect CAD patients, which could become a practical and convenient way to detect ischemia, consequently offering the ability for MSCT to act as a "one stop shop" for the diagnosis of CAD.

Application of positron emission tomography molecular probes in hepatocellular carcinoma biological imaging.

Biological behavior is a hot issue in hepatocellular carcinoma (HCC) study. Positron emission tomography (PET), a biological imaging technique, has been widely applied in many types of tumors. It is capable of noninvasive detection of biological behavior. Different radiotracers provide different information of HCC, including glucose/lipid metabolism, DNA synthesis, and apoptosis. In addition, radiotracer uptake relates to biological and clinical prognostic markers. In this article we review the application of several existing and novel radiotracers in PET in HCC study.

[CT coronary angiography combined with adenosine stress myocardial perfusion scintigraphy for detecting flow-limiting coronary stenoses].

OBJECTIVE: To assess the feasibility and accuracy of CT coronary angiography (CTCA) combined with adenosine stress myocardial perfusion scintigraphy (MPS) for diagnosis of flow-limiting coronary stenosis. METHODS: A total of 105 patients with suspected or established coronary artery disease (CAD) underwent CTCA and MPS within 4 weeks before invasive coronary angiography. The accuracy of CTCA/MPS in the diagnosis of flow-limiting coronary stenosis was evaluated in comparison with the results of quantitative coronary angiography and MPS. RESULTS: The sensitivity, specificity, positive predictive value and negative predictive value of CTCA/MPS as a combined approach for detection of flow-limiting coronary stenosis were all 100%. In 16% (9/55) of the patients, revascularization procedures were performed and no flow-limiting stenosis was found. CONCLUSION: Combination of CTCA and MPS has an excellent accuracy for detecting flow-limiting coronary stenosis as compared with quantitative coronary angiography/MPI, and can be a useful gatekeeper for revascularization procedures.

Monitoring early responses to irradiation with dual-tracer micro-PET in dual-tumor bearing mice.

AIM: To monitor the early responses to irradiation in primary and metastatic colorectal cancer (CRC) with (18)F-fluorothymidine ((18)F-FLT) and (18)F-fluorodeoxyglucose ((18)F-FDG) small-animal position emission tomography (micro-PET). METHODS: The primary and metastatic CRC cell lines, SW480 and SW620, were irradiated with 5, 10 and 20 Gy. After 24 h, the cell cycle phases were analyzed. A dual-tumor-bearing mouse model of primary and metastatic cancer was established by injecting SW480 and SW620 cells into mice. micro-PET with (18)F-FLT and (18)F-FDG was performed before and 24 h after irradiation with 5, 10 and 20 Gy. The region of interest (ROI) was drawn over the tumor and background to calculate the ratio of tumor to non-tumor (T/NT) in tissues. Immunohistochemical assay and Western blotting were used to examine the levels of integrin ß(3,) Ki-67, vascular endothelial growth factor receptor 2 (VEGFR2) and heat shock protein 27 (HSP27). RESULTS: The proportion of SW480 and SW620 cells in the G(2)-M phase was decreased with an increasing radiation dose. The proportion of SW480 cells in the G(0)-G(1) phase was increased from 48.33% ± 4.55% to 87.09% ± 7.43% (P < 0.001) and that of SW620 cells in the S-phase was elevated from 43.57% ± 2.65% to 66.59% ± 7.37% (P = 0.021). In micro-PET study, with increasing dose of radiation, (18)F-FLT uptake was significantly reduced from 3.65 ± 0.51 to 2.87 ± 0.47 (P = 0.008) in SW480 tumors and from 2.22 ± 0.42 to 1.76 ± 0.45 (P = 0.026) in SW620 tumors. (18)F-FDG uptake in SW480 and SW620 tumors was reduced but not significantly (F = 0.582, P = 0.633 vs F = 0.273, P = 0.845). Dose of radiation was negatively correlated with (18)F-FLT uptake in both SW480 and SW620 tumors (r = -0.727, P = 0.004; and r = -0.664, P = 0.009). No significant correlation was found between (18)F-FDG uptake and radiation dose in SW480 or SW620 tumors. HSP27 and integrin ß(3) expression was higher in SW480 than in SW620 tumors. The T/NT ratio for (18)F-FLT uptake was positively correlated with HSP27 and integrin ß(3) expression (r = 0.924, P = 0.004; and r = 0.813, P = 0.025). CONCLUSION: (18)F-FLT is more suitable than (18)F-FDG in monitoring early responses to irradiation in both primary and metastatic lesions of colorectal cancer.

[Application of positron emission tomography in evaluation of Alzheimer's disease rat model].

OBJECTIVE: To discuss the value of 11C-PIB PET and 18F-FDG micro PET imaging in Alzheimer's disease (AD) rat model. METHODS: The AD rat model was established by injection of Abeta1-40 into rat's hippocampus. Learning and memory function were estimated by the Morris water maze. Amyloid deposit and neuron loss were observed by Congo red staining and HE staining respectively. 11C-PIB PET and 18F-FDG micro PET scan were performed. Meanwhile the findings of PET imaging were compared with the results of behavior test and histology. RESULTS: The uptake of 18F-FDG in hippocampus of AD rat model group was lower than that of control group (P < 0.01). The Morris water maze showed that the escape latent period of rat model group was longer than that of control group (P < 0.01). Neuron loss was found in rat model brain. Thus the result of micro-PET imaging was matched with those of the Morris water maze and HE staining. 11C-PIB was specifically bound to beta-amyloid in rat model brain, the uptake of 11C-PIB in AD rat model was higher than that of control (P < 0.05). Abeta deposit was observed in Congo red staining so that the result of 11C-PIB Micro-PET imaging was matched with that of beta-amyloid deposition. CONCLUSION: 11C-PIB Micro-PET imaging shows the plaque deposition while 18F-FDG PET imaging reflects the change of glucose metabolism in hippocampus in AD rat model. And PET scan can be used to verify the successful establishment of AD model rat model.

[Positron emission tomography imaging of cell transplantation in a rat model of Alzheimer's disease].

OBJECTIVE: To explore the value of positron emission tomography (PET) in the Alzheimer's disease (AD) rat model verification and in monitoring the therapeutic effectiveness of cell transplantation. METHODS: A beta(1-40) hippocampus injected rat model was successfully established and neural stem cells were injected into hippocampus. Results of behavior tests and histological examinations were compared between model group and graft group, and then the N-methyl-[(11)C]2-(4 methylaminophenyl)-6-hydroxybenzothiazole ((11)C-PIB) and (18)F-fluorodeoxyglucose ((18)F-FDG) imaging were performed to observe whether the result of imaging was matched with behavior test and histological examination. RESULTS: The Morris water maze showed that the latent period of the escape was significantly longer in model group than in control group (P<0.01). In histological examinations, the neuron loss and A beta deposition were found in hippocampus CA1 and dentate gyrus of rat model. (11)C-PIB imaging showed increased uptake in model rat hippocampus district (P<0.05), while (18)F-FDG imaging showed that the uptake in the injected side of hippocampus in model group was significantly lower than that in the same side in control group (P<0.001). After cell transplantation, the latent period of the escape was significantly shorter in graft group than in model group (P<0.01). Histological examinations showed that there was no obvious changes in A beta deposition; in addition, the neural stem cells differentiated and expressed neuronal nuclei-positive cells, and continuously expressed 5-bromodeoxyuridine-positive cells for six weeks. (11)C-PIB imaging and (18)F-FDG imaging showed the uptakes were not significantly different between between model group and transplantation group(P>0.05). CONCLUSION: (11)C-PIB imaging is useful in diagnosing AD and monitoring the pathological change of AD model in vivo, while (18)F-FDG imaging provides useful visual information for monitoring short-term therapeutic effectiveness of stem cell transplantation.

[Positron emission tomography with special tracers in pulmonary abnormalities].

OBJECTIVE: To assess the value of positron emission tomography (PET) with (11)C-choline (CH), (11)C-methionine (MET), (18)F-fluorothymidine (FLT), and (11)C-acetate (AC) in diagnosis of pulmonary abnormalities and the features of pulmonary abnormalities in PET. METHODS: From June 2002 to June 2007, 100 patients with pulmonary nodules or masses confirmed by CT scans received PET with special tracers. Fifty-eight patients received CH-PET, 16 patients received MET-PET, 22 patients received FLT-PET, 4 patients received AC-PET. PET data was analyzed by visual method and semiquantitative method with standard uptake value (SUV). Diagnoses were compared with pathology and follow-up survey. RESULTS: For identification of pulmonary neoplasms with CH-PET, the sensitivity, specificity and accuracy were 84.2% (32/38), 57.9% (11/19) and 75.4% (43/57). In cancer cases, SUV had no correlation with tumor size or age. For identification of pulmonary neoplasms with MET-PET, the sensitivity, specificity and accuracy were 6/7, 6/9 and 75.0% (12/16). In cancer cases, SUV had not correlation with tumor size or age. For identification of pulmonary neoplasms with FLT-PET, the sensitivity, specificity and accuracy were 85.7% (12/14), 2/8 and 63.6% (14/22). In cancer cases, SUV had not correlation with tumor size or age. In AC-PET, only 1 case of pulmonary metastasis of kidney clear cell carcinoma showed acetate avid. Two squamous cell carcinoma and 1 adenocarcinoma didn't appear abnormal in AC-PET. CONCLUSION: CH, MET, FLT, AC are valuable in diagnosing but also lead to false positive and false negative.

Pitfalls in positron emission tomography/computed tomography imaging: causes and their classifications.

OBJECTIVE: To describe the pitfalls in positron emission tomography/computed tomography (PET/CT) imaging and classify them according to the principles of their generation. METHODS: We summarized retrospectively the 18F-fluorodeoxyglucose (FDP) PET/CT imaging pitfalls through reviewing the PET/CT images of 872 patients. The pitfalls were divided into artifacts and infrequent physiological uptake, and the artifacts were further classified according to their causes. Meanwhile, we calculated the incidences of various pitfalls. Whether the PET/CT pitfalls influenced the diagnostic decision was analyzed. The appearances of pitfalls in PET were also described. RESULTS: Pitfalls could be found in PET/CT images of 684 (78.4%) patients. Artifacts were found in 664 (76.15%) patients, and could be classified into self-factor artifacts and equipment- or technology-related artifacts. Among self-factor artifacts, respiratory motion (57.5%), postprandial or hyperglycemia artifacts (2.41%), and metal or high density matter artifacts (1.38%) were frequent. As for equipment- or technology-related factors, injection point outleakage or radiotracer contamination (13.88%) and truncation artifacts (1.83%) were most common ones. Infrequent physiological FDG uptakes, including fatty uptake, endometrial uptake, and bilateral breast feeding period uptake, were found in 20 (2.29%) patients. Among all pitfalls, the artifacts in 92 (13.4%) patients and infrequent physiological uptakes in 6 (0.88%) patients affected the diagnostic results. Artifact images in PET could be described as hot or cold area and the images of infrequent physiological uptake were always shown as hot area. CONCLUSIONS: The incidence of pitfall in PET/CT imaging was high and the causes of pitfalls are various. Among all causes that artifacts generated, respiratory motion is the most common. Some pitfalls may disturb clinical physicians' decision, so it is important to recognize artifacts and physiological uptake, and distinguish them from pathological uptakes.

[Relationship between computed tomography coronary angiography and adenosine stress myocardial perfusion imaging for the assessment of coronary artery disease].

OBJECTIVE: To compare the accuracy of computed tomography coronary angiography (CTCA) and adenosine stress myocardial perfusion imaging in the diagnosis of coronary artery disease (CAD) and discuss their relationship. METHODS: Fifty-six patients, suspected or diagnosed as CAD, were performed with CTCA, MPI and coronary angiography (CAG) within 3 weeks. They were divided into 3 groups: no CAD, no obstructive CAD (coronary artery stenosis < 70%) and obstructive CAD (coronary artery stenosis > or = 70%). RESULTS: 5 patients were diagnosed as no CAD. 19 patients were diagnosed as no obstructive CAD and 32 patients were diagnosed as obstructive CAD by CTCA. While adenosine stress MPI suggested 26 patients normal, 18 patients had IPD and 29 patients had RPD. The sensibility, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CTCA were 100%, 55.6%, 92.2% and 100% versus 78.6%, 71.4%, 73.3% and 76.9% respectively for adenosine stress MPI. CONCLUSION: CTCA and adenosine stress MPI provide different and complementary information on CAD, anatomical versus functional. As compared with CAG, CTCA has a high accuracy of detecting CAD.