Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled white blood cell (WBC) scintigraphy and bone scintigraphy were used in the evaluation of total knee arthroplasties (TKAs). We prospectively included 21 patients who had a three-phase bone scan for exclusion of infection of TKAs. Four hours after injection of 185 MBq 99mTc-HMPAO-labelled WBCs, planar and single-photon emission tomographic (SPET) imaging was performed. Planar imaging was repeated at 24 h p.i. Consecutively images of the knees were obtained with a dedicated PET system 60 min following the injection of 370 MBq of FDG. Focal tracer uptake was scored on SPET and PET visually (0=no uptake, 4=intense uptake). In addition, SUV (standardised uptake value) per voxel was calculated from attenuation-corrected PET images using the MLAA algorithm. Focal uptake at the bone-prosthesis interface was used as the criterion for infection before and after correlation with the third phase of the bone scan. Final diagnosis was based on operative findings, culture and clinical outcome. In the infected TKAs, the WBC scan showed focal activity of grade 2 (n=2), 3 (n=l) or 4 (n=2). PET scan revealed focal activity of grade 4 (n=5) or 3 (n=1). WBC scan alone had a specificity for infection of 53% [positive predictive value (PPV) 42%, sensitivity 100%], compared with 73% for PET scan (PPV 60%, sensitivity 100%). Considering only lesions at the bone-prosthesis interface that were also present on the third phase of the bone scan, we found a specificity of 93% (PPV 83%) for WBC scan. Using these criteria, a specificity of 80% (PPV 67%) was obtained for PET scan. Two out of three false-positive PET scans were due to loosening of the TKA. It is concluded that WBC scintigraphy in combination with bone scintigraphy has a high specificity in the detection of infected TKAs. FDG-PET seems to offer no additional benefit.

We compared the accuracy of fluorine-18 labelled 2-fluoro-2-deoxy- d-glucose positron emission tomography ((18)FDG PET) with that of technetium-99m hexamethylpropylene amine oxime leucocyte scintigraphy (LS) in the detection of infected hip prosthesis. Seventeen patients with a hip prosthesis suspected for infection were prospectively included and underwent (99m)Tc-methylene diphosphonate bone scintigraphy (BS), LS and an (18)FDG-PET scan within a 2-week period. Seven volunteers with ten asymptomatic hip prostheses were used as a control group and underwent BS and an (18)FDG-PET scan. Bacteriology of samples obtained by surgery or by needle aspiration and/or clinical follow-up for up to 6 months were used as the gold standard. Planar images of BS and LS (4 and 24 h p.i.) were acquired, followed by single-photon emission tomography (SPET) LS images (after 4 h). These images were scored as positive or negative by two experienced readers. The (18)FDG-PET scans of the patients were compared with the tracer distribution pattern in the asymptomatic control group and with BS. A phantom study was performed in order to identify artefacts. For this purpose, three different attenuation correction methods were tested. The combined analysis of the planar BS and LS resulted in a 75% sensitivity and a 78% specificity. The SPET LS images showed a better lesion contrast, resulting in an 88% sensitivity and a 100% specificity, while 24-h planar images were of no additional value. The analysis of PET images alone resulted in an 88% sensitivity and a 78% specificity. The combination of (18)FDG-PET and BS images resulted in an 88% sensitivity and a 67% specificity. Given the presence of small errors near the edge of the metal, which can induce significant artefacts in the corrected emission image, we decided to use the data without attenuation correction. In this preliminary study, (18)FDG-PET scans alone showed the same sensitivity as combined BS and LS, although the specificity was slightly lower.

No abstract

Kivu's traditional patrimonial system revolved around the distribution of access rights to communally held land in return for rents that were redistributed through the system. The social capital embedded in this institutional framework was a public good. The introduction of a ‘modern’ land law in 1973 destroyed the social cohesion of that patrimonial system; it sanctioned efforts to capitalise and appropriate the full value of these rents. At the time of the law's introduction, market mechanisms for factor markets including land, were not developed, so they had to be simulated. The core of this simulation consisted of exchanging social capital, built up in networks that involved political power-holders and state administrators, for assets. The social capital embedded in these networks was a ‘club good’ rather than a public good; both are non-rival in nature, but with a club good, unlike public goods, exclusion is workable. Its effect was therefore marginalisation and dispossession of those not belonging to the ‘club’, and the erosion of the existing social capital tied up in the traditional institutional framework by breaking the patterns of reciprocity and assurance featured in it. This evolution has contributed to a change of social structure and a crisis of legitimacy that increased social tensions and the potential for conflict. The customary leadership was able to cling to their positions by mobilising their clientele on an ethnic platform, conveniently using the issue of nationality: ‘foreigners’, especially the Banyarwanda and Banyamulenge, were accused of having unrightfully appropriated customary land and of having subverted the customary order.

Salivary gland scintigraphy (SGS) is used to depict salivary gland dysfunction after radiotherapy (RT). The aim of this study was to investigate the utility of SGS combined with single photon emission computed tomography (SPECT). Twenty-one patients with a carcinoma of head and neck underwent SGS before and 1 month after RT. After injection of 370 MBq 99Tcm-pertechnetate, a biplanar dynamic acquisition (12 x 1 min) was started, followed by a SPECT acquisition during 4 min. Carbachol was then injected and a second dynamic study (16 x 1 min) was performed, again followed by a SPECT acquisition. The salivary excretion fraction (SEF) was calculated both from the geometric mean planar image for each parotid and from the SPECT data for each transverse plane through the parotids. The RT-induced changes in the SEF (dSEF) were correlated with the mean radiation dose calculated using tomography-based dosimetry. The mean radiation dose to the parotids was 44 Gy (range 4.4-68.1 Gy). The mean range of the variation in radiation dose to the transverse slices within the parotids of a patient was 24 Gy (range 6.2-51.9 Gy). Considering all transverse planes through the parotids in all patients, a linear correlation was found between the dSEF calculated using SGS-SPECT and the radiation dose (r=0.45, P=0.0001). Thirteen patients had a variation in radiation dose within the parotids of more than 20 Gy. In nine of these a significant intra-individual correlation between radiation dose and the dSEF of the transverse parotid slices was found (r range 0.55-0.97; P value range 0.037-0.0001). In conclusion, SGS-SPECT can be used for monitoring radiation-induced parotid gland dysfunction. It offers the unique possibility for the assessment of intra-individual dose-dysfunction curves in patients with large variations in the radiation dose within the parotids.