The importance of the location of fluorodeoxyglucose uptake in periprosthetic infection in painful hip prostheses

Ten per cent of patients with hip replacement will eventually complain of significant pain after surgery, often requiring a revision arthroplasty. The majority of these patients experience aseptic loosening rather than infection. Despite significant advances made in diagnostic imaging, distinguishing infection from aseptic loosening remains a significant challenge. Imaging using fluorodeoxyglucose (FDG) positron emission tomography (PET) has been reported to have excellent sensitivity in detecting infections associated with hip prostheses. However, in some studies, a high rate of false positive results has been reported, especially when increased tracer uptake adjacent to the prosthesis (which is not surrounded by bone) is used as the sole criterion for diagnosing infection. The objective of this investigation was to determine the optimal criteria for diagnosing periprosthetic infection, thereby avoiding false positive results in this setting. A total of 41 total hip arthroplasties from 32 patients and for whom complete clinical follow-up was available were included in this analysis. The location and intensity of FDG uptake were determined for each scan. Final diagnosis was made by microbiology, histopathology, surgical findings and clinical follow-up. Patients who did not undergo surgery were followed up to at least 9 months. Twelve patients were proven eventually to have periprosthetic infection. Images from 11 of these patients displayed increased tracer uptake along the interface between bone and prosthesis. The intensity of the increased tracer uptake varied from mild to moderate, with standardized uptake values less than 2. In contrast, images from uninfected, loose hip prostheses revealed very intense uptake around the head or neck of the prosthesis with standardized uptake values as high as 7. It is concluded that the intensity of increased FDG uptake is less important than the location of increased FDG uptake when FDG PET is used to diagnose periprosthetic infection in patients with hip arthroplasty. Using increased uptake as the sole criterion for diagnosing infection will result in false positive results in this setting.

[Clinical significance of Q-Tc dispersion after exercise in aged patients with old myocardial infarction]

OBJECTIVE

This study was aimed to evaluate clinical significance of Q-Tc dispersion after exercise in aged patients with old myocardial infarction.

METHOD

Sixty-four aged patients with old myocardial infarction(infarction group) were examined by treadmill exercise, dynamic electrocardiography, echocardiography, and were followed up for average of 24.12 +/- 7.7 months. 30 healthy aged persons were served as control group.

RESULTS

Compared with that (40.21 +/- 15.21 ms) before exercise, Q-Tc dispersion (59.37 +/- 20.17 ms) was increased significantly after exercise in infarction group(P < 0.01). But no significant difference was found in Q-Tc dispersion of control group before and after exercise(34.70 +/- 12.29 ms vs 38.91 +/- 13.62 ms P > 0.05). In infarction group, occurrence of abnormal contraction of left ventricular wall, aneurysms, NYHA III class and > III class of Lown's ventricular arrhythmia classification was significantly higher in Q-Tcd > 50 ms patients than that in Q-Tcd < 50 ms ones(P < 0.05). It was found that 5 patients died of cardiac sudden death in Q-Tcd > 50 ms patients and no one died of cardiac sudden death in Q-Tcd < 50 ms ones.

CONCLUSION

The Q-Tc dispersion after exercise is an important index to predict ventricular arrhythmia and cardiac death in the patients with old myocardial infarction.

[Does semi-quantitative analysis of FDG-PET have any additional value in the diagnosis of mesial temporal sclerosis?]

The aim of this study was to compare qualitative visual analysis with semi-quantitative analysis in the diagnosis of mesial temporal sclerosis (MTS) using FDG-PET.

METHODS

This study included 21 patients with histopathological confirmation of MTS. FDG-PET visual analysis data were based on clinical reports generated soon after the completion of the scan. FDG-PET images were semi-quantitatively analyzed using regions of interest (ROIs) in 19 slices perpendicular to the longest axis of the temporal lobe. These ROIs divided each temporal lobe into three regions (lateral, inferior and medial). An asymmetry index was calculated for each region.

RESULTS

The visual analysis of the FDG-PET studies demonstrated asymmetric hypometabolism in all patients. All but 1 patient underwent standard lobectomy of the same side described as hypometabolic by the PET report. Using an asymmetry index equal or greater than 9% in at least one of the regions as a threshold, the FDG-PET semi-quantitative analysis showed significant asymmetry in 18 patients. These also matched the side of lobectomy and were confirmed as sclerotic in all but one patient (same patient as above).

CONCLUSION

The semi-quantitative analysis did not provide additional information over visual interpretation in this series of patients.

Relationships involving metastable equilibrium solubility, surface complexes, and crystallite disorder with carbonated apatites

Previous studies have shown that the metastable equilibrium solubility (MES) behavior of carbonated apatites (CAPs) may be described by a surface complex with the hydroxyapatite (HAP) stoichiometry in the absence of solution fluoride and by that with the fluorapatite (FAP) stoichiometry when appreciable solution fluoride is present. Studies have also shown that the magnitude of the MES is directly related to the crystallinity of the CAP. The aim of the present investigation was to examine the relationship between the CAP MES determined in the presence of solution fluoride and CAP crystallinity and to examine the effect of the change in the stoichiometry of the surface complex (from that of HAP to that of FAP) upon the relationship of the CAP MES to crystallinity. CAP samples were prepared by methods based on the precipitation of CAP from calcium phosphate solutions and the hydrolysis of dicalcium phosphate dihydrate in bicarbonate solutions. From X-ray diffraction experiments, the crystallite microstrain, and the full width at half maximum (FWHM) of the 002 reflection were determined for the CAPs. From CAP MES experiments conducted in the presence of solu tion fluoride, linear plots of the mean MES (i.e., mean pK(FAP)) values vs the crystallinity parameter (i.e., microstrain and FWHM) were obtained that yielded slopes that were essentially the same as those obtained in the absence of solution fluoride (i.e., mean pK(HAP) values vs crystallinity). This parallel finding suggests that the CAP crystallite disorder affects the energetics of the two surface complexes essentially to the same extent and provides new insight into the nature of CAP surface complexes.

[Development of a diagnostic kit of enzyme-linked immunoassay for detecting serum anti-hepatitis E virus IgG]

OBJECTIVE

To develop a diagnostic kit for detecting serum anti-hepatitis E virus (HEV) IgG with enzyme-linked immunoassay (ELISA).

METHODS

The diagnostic kit of detecting anti-HEV IgG with ELISA was prepared by two synthetic HEV peptides used for coating the solid-phase to capture the antibody against HEV in serum, and then by horseradish peroxidase antihuman IgG (gamma chain) added as the second antibody to bind the anti-HEV IgG in serum. Its sensitivity, specificity, precision and stability were measured and clinically evaluated.

RESULTS

The sensitivity, specificity, and precision of the diagnostic kit detected by the China National Institute for the Control of Pharmaceutical and Biological Products were 90% (1/10), 100% (0/30) and < 15%, respectively, meeting the national standards for detecting serum anti-HEV IgG with ELISA. The ELISA Kit is stable for 1 year at least under 4 degrees C. The total consistency rates were 100% (43/43) and 96.6% (86/89), as compared with Genelabs and Singaporean DBL kits. This diagnostic kit for detecting serum anti-HEV IgG with ELISA was evaluated and approved by the State Drug Administration, China and a certificate was conferred in 1998.

CONCLUSIONS

The diagnostic kit for detecting anti-HEV IgG with ELISA can be used for epidemiological studies and clinical diagnosis of HEV infection.

Dual time point 18F-FDG PET imaging for differentiating malignant from inflammatory processes

The aim of this study was to investigate the difference in the rates of FDG uptake between malignant and inflammatory cells and processes.

METHODS

IN VITRO STUDIES

(18)F-FDG uptake by different tumor cell lines (human mesothelioma [REN]; rat mesothelioma [II45]; mice melanoma [B18F10]; mice mesothelioma [AB12]; human myeloma [GM1500]; and human ovarian cancer [SKOV3]) and peripheral blood mononuclear cells isolated from 8 healthy human volunteers was measured 20 and 60 min after FDG was added into growth medium. Animal studies: II45 cells were implanted into the left flank of rats (n = 5) and a focal inflammatory reaction (mechanical irritation) was generated in the right flank. PET images at 45 and 90 min after injection of FDG were obtained and standardized uptake values (SUVs) were determined. Patient studies: Seventy-six patients who had dual time FDG PET scans were retrospectively analyzed. All results were expressed as the percentage change in SUV of the later time image from that of the earlier time (mean +/- SD).

RESULTS

IN VITRO STUDIES

Except for the SKOV3 cell line, which had only minimally increased FDG uptake (+10% +/- 26%; P > 0.3), all other tumor cell lines tested showed significantly increased FDG uptake over time (GM1500, +59% +/- 19%; B18F10, +81% +/- 15%; AB12, 93% +/- 21%; II45, +161% +/- 21%; REN, +198% +/- 48%; P < 0.01 for all). By contrast, FDG uptake in mononuclear cells was decreased in 7 of 8 donors. Animal studies: SUVs of tumors from 90-min images were significantly higher than those from 45-min images (+18% +/- 8%; P < 0.01), whereas the SUVs of inflammatory lesions decreased over time (-17% +/- 13% of the early images; P < 0.05).

CLINICAL STUDIES

The SUVs of delayed images from the known malignant lesions compared with those of earlier scans increased over time (+19.18% +/- 9.58%; n = 31; P < 0.001; 95% confidence interval, 15.8%-22.6%). By contrast, the SUVs of benign lung nodules decreased slightly over time (-6.3% +/- 8.1%; n = 12; P < 0.05; 95% confidence interval, -10.9% to -1.7%). The SUV of inflammatory lesions caused by radiation therapy (+1.16% +/- 7.23%; n = 8; P > 0.05; 95% confidence interval, -3.9%-6.2%) and the lesions of painful lower limb prostheses (+4.03% +/- 11.32%; n = 25; P > 0.05; 95% confidence interval, -0.4%-8.5%) remained stable over time.

CONCLUSION

These preliminary data show that dual time imaging appears to be useful in distinguishing malignant from benign lesions. Further research is necessary to confirm these results.

An extended self-organizing map network for modeling and control of pulse jet fabric filters

Pulse jet fabric filters (PJFFs) have become an attractive option of particulate collection utilities, because they can meet stringent particulate emission limits regardless of variation in operating conditions. Despite their wide applications, the present control algorithm for PJFFs can best be described as rudimentary. In this paper, a modeling and control strategy based on the local model network (LMN) is proposed. An extended self-organizing map (ESOM) network is developed to construct the LMN model of the filtration process using the filter's input-output data. Subsequently, these ESOM local models are incorporated into the design of local generalized predictive controllers (GPC), and the proposed controller design is obtained as the weighted sum of these local controllers. Simulation results show that the proposed controller design yields a better performance than both conventional GPC and proportional plus integral (PI) controllers yield.

A bacterially expressed peptide prevents experimental infection of primates by the hepatitis E virus

A 23 kDa peptide of the major structural protein of the hepatitis E virus (HEV) expressed in E. coli was found to naturally interact with one another to form homodimers and the peptide was recognized strongly in its dimeric form by HEV reactive human sera. To determine if the peptide may confer protection against HEV infection, three monkeys were immunized with the purified peptide and three were given placebo. Both groups of animals were challenged with 10(5) genome equivalent dose of the homologous strain of HEV. All control animals excreted the virus for 10-12 days beginning 5 days after the infection. The viral genome was also present in the peripheral blood monocyte (PBMC) samples from two animals, but it was not detected in the plasma samples from any of the animals. The infection in two control animals was accompanied by HEV seroconversion. Immunization was found to abrogate HEV stool excretion in two animals and reduced the viral excretion to one day in the third. None of the immunized animals showed detectable HEV in plasma or PBMC samples nor did the animals showed evidence of HEV seroconversion. These results suggested that immunization with the bacterially expressed peptide may prevent experimental infection of primates with the homologous strain of HEV.

Similar Pelvic Abnormalities on FDG Positron Emission Tomography of Different Origins

Fluorodeoxyglucose positron emission tomography (FDG PET) has been used extensively to detect and stage various cancers. However, normal variation and inflammatory lesions may lead to false-positive interpretations of PET findings. The authors report three cases of increased pelvic FDG uptake with differing origins. Although the findings are similar, a postpartum uterus, lymphoma, and a bleeding uterus caused pelvic FDG uptake in these patients. Interestingly, of these three patients, the patient with lymphoma had the lowest level of FDG uptake. Clinical correlation is needed for the accurate interpretation of FDG-PET findings.

Detection of cranial metastases by F-18 FDG positron emission tomography

Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning has been useful in the management of various cancers. The normal glucose use of gray matter often limits the detection of metastatic lesions to the brain and skull with FDG PET. The authors report two cases of calvarial metastases: one with pheochromocytoma and the other with non-small-cell lung carcinoma. These cases illustrate the crucial role that FDG PET can play when patients are examined for metastases. The important concept of contrast resolution that is achieved with PET imaging is discussed as an advantage that significantly overcomes its limited spatial resolution in detecting small lesions that may not be detected by anatomic imaging techniques with high spatial resolution.

[Study on hepatitis C virus genotyping in some parts of China]

OBJECTIVE

To study the genotypes of hepatitis C virus in some parts of China.

METHODS

Twenty-seven sera of plasma donors from Guan county of Hebei province, Zhoukou district of Henan province, and 36 patients with chronic hepatitis C from Beijing and Qingdao cities were tested for HCV RNA by Amplicor PCR kit. Thirty-six of 38 HCV RNA positive sera were further genotyped, using INNO-LiP A HCV II kit.

RESULTS

The HCV RNA positive rates of plasma donors and patients with chronic hepatitis C were 48.15% (13/27) and 69.44% (25/36) respectively. Genotyping data from 13 plasma donors and 23 patients with chronic hepatitis C showed that 29 (80.55%) were 1b, 5 (13.89%) were genotype 2, and 2 (5.56%) remained untyped.

CONCLUSION

1b seemed to be the prevalent HCV genotype in some parts of China.

Evaluation of recurrent squamous cell carcinoma of the head and neck with FDG positron emission tomography

PURPOSE

This study compared the effectiveness of fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT), magnetic resonance imaging (MRI), or both for the assessment of recurrent squamous cell carcinoma of the head and neck. The value of quantifying the standardized uptake values (SUV) to distinguish recurrent neoplasm from inflammatory lesions and normal structures was also evaluated.

METHODS

Forty-three patients with head and neck cancer were examined with F-18 FDG PET at least 4 months after their last course of radiation therapy (mean, 11 months). The SUVs were measured in visually identified regions of abnormally increased activity and were compared with the values in normal mucosa, the base of the tongue, and the hard palate to determine if an optimal cutoff value exists for diagnosing recurrence of malignant lesions. The final diagnosis of recurrence was made based on biopsy or at least 6 months' clinical follow-up.

RESULTS

FDG PET correctly detected recurrence in 20 of 22 patients who had 45 discrete lesions located in the field of the upper aerodigestive tract. Two false-negative and three false-positive results were identified. The accuracy of FDG PET was 88% (38 of 43 patients), compared with 66% (25 of 38 patients) for CT, MRI, or both. Although there was a significant difference of SUVs (P = 0.0036) between the recurrent lesions and normal structures, the optimal cutoff values were difficult to define.

CONCLUSIONS

Visual analysis of FDG PET is significantly more accurate in the diagnosis of recurrent squamous cell cancer of the head and neck than are CT or MRI. However, single SUV quantification does not significantly enhance efficacy.

The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants

The purpose of this study was to evaluate the feasibility of using 18F-FDG and PET for the detection of infection associated with lower limb arthroplasty.

METHODS

Seventy-four prostheses in 62 patients in whom infection was suspected after artificial hip or knee placement were studied with this technique. Images were obtained 60 min after an intravenous injection of FDG. The images were interpreted as positive for infection if tracer uptake was increased at the bone-prosthesis interface. A final diagnosis was made by surgical exploration or clinical follow-up for 1 y. PET results were compared with the follow-up outcome in all patients.

RESULTS

The sensitivity, specificity, and accuracy of PET for detecting infection associated with knee prostheses were 90.9%, 72.0%, and 77.8%, respectively. The sensitivity, specificity, and accuracy of PET for detecting infection associated with hip prostheses were 90%, 89.3%, and 89.5%, respectively. Overall, the sensitivity was 90.5% and the specificity was 81.1% for detection of lower limb infections.

CONCLUSION

FDG PET is a useful imaging modality for detecting infections associated with lower limb arthroplasty and is more accurate for detecting infections associated with hip prostheses than for detecting infections associated with knee prostheses.

Imaging in vivo herpes simplex virus thymidine kinase gene transfer to tumour-bearing rodents using positron emission tomography and

Radiolabelled ganciclovir analogues have shown promise as imaging agents to detect herpes simplex virus thymidine kinase (HSVtk) expression. This study evaluated the use of positron emission tomography (PET) imaging with 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG) to assess gene transfer into tumours. HSVtk-positive and HSVtk-negative cell lines were first treated in vitro with [18F]FHPG. To assess the efficacy of PET in detecting HSVtk expression following in vivo gene transfer, mice were injected intravenously with an adenovirus encoding HSVtk (Ad.HSVtk), a control vector (Ad.Bgl2) or saline. Subcutaneous human glioma xenografts were grown in mice and treated by direct injection of Ad.HSVtk or Ad.Bgl2. Imaging was performed 48 h after transduction. Similar experiments were performed using Fischer rats implanted with syngeneic tumours. The presence of the HSVtk protein was confirmed by immunohistochemistry. Biodistribution studies were also obtained in 14 naive mice. In vitro studies showed high and specific uptake of [18F]FHPG in HSVtk-positive cell lines, with an uptake ratio of up to 27:1. PET imaging and direct counting of major organs demonstrated HSVtk-specific tracer retention. In mice, HSVtk-positive tumours retained 3.4% dose/gram as compared to 0.6% for control tumours (P=0.03). They were clearly seen on the PET images as early as 100 min post injection. Similar results were obtained with syngeneic rat tumours. Biodistribution studies demonstrated the rapid distribution and clearance of the tracer in all major organs. Our results demonstrate that PET imaging of HSVtk gene transfer to tumours is feasible and is highly specific for HSVtk expression.

[Partial nucleotide sequences of hepatitis E viruses isolated from patients in 14 cities of China]

OBJECTIVE

To investigate the genotypes of hepatitis E viruses isolated in China.

METHODS

The partial genome of open reading frame 2 (nt6461-6860, nt5994-6294) of 45 HEV isolated from patients in 14 cities of China was amplified and sequenced using polymerase chain reaction and direct sequencing.

RESULTS

41 of 45 isolates (91%) shared the same genotype with HEV Burma strain (B), with nucleotide identities higher than 98% with the representative HEV Chinese strain. Only 4 HEV isolates were significantly divergent from the 3 prototype strains of HEV, with nucleotide identities of 77%-80% with HEV Burmese/Chinese strain, 74%-76% with Mexico strain and 74%-77% with the newly discovered HEV US/Swine strain, respectively. Phylogenetic analysis suggested that these 4 isolates represented 2 different subtypes belonging to a novel genotype of HEV, which was significantly divergent from the prototype Mexican, Burmese and US/Swine isolates.

CONCLUSION

Among patients with hepatitis E in China, most are infected with the Chinese prototype HEV, and only a small part with the new genotype HEV.

[A new chemiluminescence immunoassay method for the determination of cancer embryo antigen]

A new chemiluminescent probe 10,10'-dimethyl-3,3'-disulfo-9,9'-biacridine DMDSBA) is used to label anti-CEA antibody, the molar incorporation is 1.15-1.32 mole of DMDSBA per mol anti-CEA; the conditions of labeling reaction, sandwich immunoassay and chemiluminescent reaction are studied. Moreover, a new double antibody sandwich chemiluminescence immunoassay is firstly established, the linear calibration ranges is 1.5-150.0 ng.mL-1 and the detection limit is 0.53 ng.mL-1. This method is used to detect cancer embryo antigen (CEA) in human serum, the results are well-matched with that of radio immunoassay.