FDG-PET, 99mTc-HMPAO white blood cell SPET and bone scintigraphy in the evaluation of painful total knee arthroplasties

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=1) 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.     

Left ventricular thrombus formation after acute myocardial infarction as assessed by cardiovascular magnetic resonance imaging

Introduction

Left ventricular (LV) thrombus formation is a feared complication of myocardial infarction (MI). We assessed the prevalence of LV thrombus in ST-segment elevated MI patients treated with percutaneous coronary intervention (PCI) and compared the diagnostic accuracy of transthoracic echocardiography (TTE) to cardiovascular magnetic resonance imaging (CMR). Also, we evaluated the course of LV thrombi in the modern era of primary PCI.

Methods

200 patients with primary PCI underwent TTE and CMR, at baseline and at 4 months follow-up. Studies were analyzed by two blinded examiners. Patients were seen at 1, 4, 12, and 24 months for assessment of clinical status and adverse events.

Results

On CMR at baseline, a thrombus was found in 17 of 194 (8.8%) patients. LV thrombus resolution occurred in 15 patients. Two patients had persistence of LV thrombus on follow-up CMR. On CMR at four months, a thrombus was found in an additional 12 patients. In multivariate analysis, thrombus formation on baseline CMR was independently associated with, baseline infarct size (g) (B = 0.02, SE = 0.02, p < 0.001). Routine TTE had a sensitivity of 21–24% and a specificity of 95–98% compared to CMR for the detection of LV thrombi. Intra- and interobserver variation for detection of LV thrombus were lower for CMR (κ = 0.91 and κ = 0.96) compared to TTE (κ = 0.74 and κ = 0.53).

Conclusion

LV thrombus still occurs in a substantial amount of patients after PCI-treated MI, especially in larger infarct sizes. Routine TTE had a low sensitivity for the detection of LV thrombi and the interobserver variation of TTE was large.     

The micronucleus test in Xenopus: a new and simple 'in vivo' technique for detection of mutagens in fresh water

The aim of this study was to extend the micronucleus test toXenopus laevis to screen water for potential mutagens. Up tonow, the most commonly used methods for screening fresh waterare the bacterial tests (Ames tests). Ames tests are well validated,but are merely in vitro bacterial assays which can only detectpoint mutations whereas the micronucleus test is an in vivoassay using a vertebrate species, and thus is able to detectboth chromosome and genome mutations. This study was designedto optimize the micronucleus test for Xenopus. Three differentvariables were investigated: (i) the effect of temperature;(ii) the effect of the stage of larval development; and (iii)the effect of varying or continuous exposure concentrations.In addition, a dose—response curve was established foreight concentrations of benzo[a]pyrene. The results indicatethat the micronucleus test with Xenopus can be used to monitorwater pollution.     

Effects of midazolam,DMCM and lindane on potentiated startle in the rat

Forty-eight male Wistar rats were exposed to contingent light-shock combinations and 48 rats received light and shock stimuli in a random order. One day after fear conditioning the animals were tested for startle potentation after injection of midazolam (0, 0.5, 1.0, 2.0 mg/kg, IP) or DMCM (methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate; 0, 0.1, 0.2, 0.4 mg/kg IP) or lindane (0, 7.5, 15.0, 30.0 mg/kg PO). Midazolam attenuated potentiated startle dose dependently and the inverse benzodiazepine agonist DMCM had the opposite effect. The effects of lindane on startle amplitudes were identical to those of DMCM, indicating that lindane has anxiogenic effects on behavior. It is suggested that the anxiogenic effects of lindane are mediated by an effect at the GABA-ionophore complex.     

Development of the tubotympanum in the rat

Objective: To investigate the relationship between the anatomical maturation of the middle ear and that of the eustachian tube and paratubal muscles in the rat. Design: Wistar rats ranging from gestational day 12 to postnatal day 40 were used. Methods: Tissue specimens were examined with routine light microscopy and electron microscopy. Epithelial differentiation was studied immunohistochemically with antibodies to different cytokeratins. Results: The epithelial lining of the tubotympanum showed differentiation-related cytokeratin expression throughout the whole developmental period. The mucociliary epithelium reached mature features around birth. A dorsal extension and its framing cartilage started forming around 5 days after birth. This extension became lined by stratified nonciliated epithelium and attained maturity around 10 days after birth concurrently with the attachment of the dilatory muscles. This process was immediately followed by aeration of the middle ear cavity. Conclusions: The continuous expression of cytokeratins demonstrates that the epithelial lining of the tubotympanum is only derived from the embryonal endoderm. Furthermore, this study demonstrates that the eustachian tube shows a two-stage postnatal development. First, the mucociliary system matures, providing protection/clearance when the animal starts respiration and swallowing. Subsequently, the dorsal part attains maturity. The features of the epithelial lining of the dorsal part of the eustachian tube and the coincidence of the maturation of this part with the attachment of the dilating muscle fibers and the aeration of the middle ear indicates that this part provides ventilation. These findings support the authors' hypothesis that different parts of the eustachian tube serve different purposes: clearance, protection and ventilation.     

The changing pattern of medical activity in a major Belgian university hospital

To evaluate the changes in the pattern of clinical activity in a 1900-bed Belgian teaching hospital in the period 1979-1987, we extracted data from the historical files of the hospital's central invoicing system. The total charge for a day of hospitalization, care and treatment increased by 83%. In this total per diem charge the share of hospital charges in the strict sense declined from 60 to 53%; the shares of charges for services and for pharmaceuticals rose, respectively, from 29 to 32, and from 10 to 15%. Within charges for services the share for diagnostic services declined by 22%; the share for surgery rose by 16%, and that for miscellaneous other services by 89%. For diagnostic services the decline was particularly clear for laboratory medicine (-32%) and for conventional imaging services (-22%), while cardiac and endoscopic investigations show a prominent expansion (+78 and +83%, respectively). In surgery the growth is quite homogeneous with the charges for urology, ophthalmology and orthopedics as the most important growers. In a group of miscellaneous, not diagnostic nor surgical services, which grows faster than all other groups, there is a marked shift from rather simple to technologically more advanced services. The increase in the pharmacy's bill results from increases in charge for both drugs (+49%) and materials (+95%). We conclude that the observed changes in charges reflect an intensification of care and an impact of technological innovation on clinical practice, including a phenomenon of substitution of old technologies for newer ones.     

The bacteriological changes after re-using a vaginal continence guard.

BACKGROUND: Involuntary loss of urine is a major health care problem, especially in women. The Conveen Continence Guard is a non-surgical treatment of stress incontinence. A possible risk of vaginal devices is introduction of changes in bacteriological flora of the vagina, especially after re-use of the guard. Moreover, vaginal devices can induce magnesium ion deficiency and thereby facilitate growth of Staphylococcus Aureus. This can lead to the production of toxin-1, eventually resulting in toxic shock syndrome. METHODS: The first aim of this study was to investigate the capacity to absorp magnesium ions in an in-vitro study. Secondly, 14 patients with stress incontinence were examined for bacteriological changes in the vagina after re-using the continence guard for four days. After completing this study the patients were asked whether re-using the continence guard was as convenient as single use. RESULTS: The continence guard had no absorption capacity for magnesium ions. The vaginal bacteriological changes after re-use showed in 11% changes in bacterial growth and in 20% increased bacterial growth. Only one patient developed a vaginal colonization with Staphylococcus Aureus but had no symptoms of disease. The continence guard showed itself to be less effective in preventing stress incontinence after re-use. CONCLUSIONS: Although re-use of the continence guard is feasable from a bacteriological point of view, re-use renders the device less effective.     

Quality of life after gamma knife radiosurgery treatment in patients with a vestibular schwannoma: the patient’s perspective

This study evaluates the impact of gamma knife radiosurgery (GKRS) on the quality of life (QOL) of patients with a sporadic vestibular schwannoma (VS). This study pertains to 108 VS patients who had GKRS in the years 2003 through 2007. Two different QOL questionnaires were used: medical outcome study short form 36 (SF36) and Glasgow benefit inventory (GBI). Radiosurgery was performed using a Leksell 4C gamma knife. The results of the QOL questionnaires in relation to prospectively and retrospectively gathered data of the VS patients treated by GKRS. Eventually, 97 patients could be included in the study. Their mean tumor size was 17 mm (range 6–39 mm); the mean maximum dose on the tumor was 19.9 Gy (range 16–25.5 Gy) and the mean marginal dose on the tumor was 11.1 (range 9.3–12.5 Gy). SF36 scores showed results comparable to those for a normal Dutch population. GBI showed a marginal decline in QOL. No correlation was found between QOL and gender, age, tumor size, or radiation dose. Increased audiovestibular symptoms after GKRS were correlated with a decreased GBI score, and decreased symptoms were correlated with a higher QOL post-GKRS. In this study shows that GKRS for VS has little impact on the general QOL of the VS patient. However, there is a wide range in individual QOL results. Individual QOL was influenced by the audiovestibular symptoms. No predictive patient, tumor, or treatment factors for QOL outcome after GKRS could be determined. Comparison with microsurgery is difficult because of intra group variability.