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P O Kotzki

Publications and source records attributed to P O Kotzki.

At least 19 recordsLinked to original sources
PubMed2004

Image resolution and magnification using a cone beam densitometer: optimizing data acquisition for hip morphometric analysis.

Bone mineral density (BMD) is a primary determinant of hip fracture risk. However, other factors, notably the femoral geometry, can influence hip fracture risk. The purpose of this study was to evaluate the potential of a new cone beam densitometer, the DMS Lexxos, in order to visualise femoral morphometry. Resolution, magnification and distortion were assessed in vitro using a line pair test pattern and a matrix test object. Results were given in comparison with currently available systems: the Hologic Discovery A and the Lunar Prodigy densitometers. The DMS Lexxos image resolution was the same in the longitudinal and transversal directions evaluated between 1.4 and 0.5 line pairs/mm (lps/mm) for an attenuation varying from 25 to 325 mm of Perplex. The longitudinal resolution was evaluated between 0.9 and 0.5 lps/mm with the Hologic Discovery densitometer, and inferior to 0.5 with the Lunar Prodigy; as for transversal resolution, it varied from 0.63 to 0.5 lps/mm and from 0.6 to inferior 0.5 lps/mm, respectively. The image was isotropic without magnification with the GE-Lunar Prodigy, whereas there was only a transversal magnification with the Hologic Discovery device. The magnification was about 1.17% cm(-1 )in the two directions, while increasing the distance of the phantom above the examination table with the Lexxos. This magnification was isotropic without distortion. The magnification could be evaluated from two images taken before and after translation of the C-arm, and a magnification correction could be applied. This method was applied to a phantom and to a human cadaver femoral bone.

Absorptiometry, Photon↗
PubMed2003

Total dose incurred by patients and staff from BMD measurement using a new 2D digital bone densitometer.

Dual energy X-ray absorptiometry (DXA) is a widely used and precise technique for non-invasive assessment of bone mineral density. The DXA systems have evolved from pencil X-ray beam (single detector) to fan beam (linear array detector) and recently cone beam densitometers (bi-dimensional detector), allowing for an examination to occur without any scanning and with a short acquisition time. The purpose of this study was to evaluate patient and staff dose from a new cone beam densitometer, the DMS Lexxos. Measurements were performed on a DMS Lexxos bone densitometer prototype. An anthropomorphic phantom and thermoluminescent dosimeters were used to evaluate the effective dose. Ionization chambers and electronic personal dosimeters were used to evaluate the staff dose. The effective dose is 8.4 micro Sv for an anteroposterior spine examination and 4.8 micro Sv for a femoral neck in standard mode. The averaged scattered dose rate (ambient dose equivalent) at 1 m from the beam is evaluated at 226 micro Sv/h. Assuming six patients per hour with two views per patient, the time averaged dose rate is evaluated at 2.9 micro Sv/h. By the personal dosimeter, the staff dose (Hp 10) at 1 m from the beam is evaluated at 0.23 micro Sv per examination. For one examination, patient and staff dose from this new technology remains low: in the same range as the fan-beam densitometer.

Absorptiometry, Photon↗
PubMed2001

Routine measurements of left and right ventricular output by gated blood pool emission tomography in comparison with thermodilution measurements: a preliminary study.

The aim of this preliminary study was to evaluate the accuracy of left and right ventricular output computed from a semi-automatic processing of tomographic radionuclide ventriculography data (TRVG) in comparison with the conventional thermodilution method. Twenty patients with various heart diseases were prospectively included in the study. Thermodilution and TRVG acquisitions were carried out on the same day for all patients. Analysis of gated blood pool slices was performed using a watershed-based segmentation algorithm. Right and left ventricular output measured by TRVG correlated well with the measurements obtained with thermodilution (r = 0.94 and 0.91 with SEE = 0.38 and 0.46 l/min, respectively, P < 0.001). The limits of agreement for TRVG and thermodilution measurements were -0.78-1.20 l/min for the left ventricle and -0.34-1.16 l/min for the right ventricle. No significant difference was found between the results of TRVG and thermodilution with respect to left ventricular output (P = 0.09). A small but significant difference was found between right ventricular output measured by TRVG and both left ventricular output measured by TRVG (mean difference = 0.17 l/min, P = 0.04) and thermodilution-derived cardiac output (mean difference = 0.41 l/min, P = 0.0001). It is concluded that the watershed-based semi-automatic segmentation of TRVG slices provides non-invasive measurements of right and left ventricular output and stroke volumes at equilibrium, in routine clinical settings. Further studies are necessary to check whether the accuracy of these measurements is good enough to permit correct assessment of intracardiac shunts.

Adult↗
PubMed1999

Comparison of ultrasound and dimercaptosuccinic acid scintigraphy changes in acute pyelonephritis.

The strategy for morphological investigations in children with acute pyelonephritis (APN) remains debatable. We studied 70 children (median age 2.0 years) admitted with a first episode of pyelonephritis using a high-resolution ultrasound technique (RUS) and compared the results with 99m technetium-dimercaptosuccinic acid (DMSA) renal scintigraphy. The DMSA scan was abnormal in 62 children (89%). However, using a high-frequency transducer we found abnormal sonogram changes in 61 children (87%), consisting of an increased kidney volume in 42, and/or a thickening of the wall of the renal pelvis in 42, and/or a focal hyper- or hypoechogenicity in 36, and/or a diffuse hyperechogenicity in 31 children. Micturating cystourethrography was performed in all children, revealing vesicoureteral reflux (VUR) in 22 (31%). Among those children with VUR, 4 had a normal DMSA scan, 2 an abnormal RUS, and 2 a normal DMSA scan and RUS. Our data suggest that B-mode RUS performed with a high-frequency transducer by a trained radiologist is nearly as sensitive as the DMSA scan in diagnosing renal involvement in children with unobstructed APN and in predicting VUR.

Acute Disease↗
PubMed1999

Depressive illness, depressive symptomatology and regional cerebral blood flow in elderly people with sub-clinical cognitive impairment.

BACKGROUND: Depressive illness in dementia is often assumed to be a unitary clinical phenomenon. AIM: To describe changes in patterns of depressive symptomatology with time, and associated changes in cerebral blood flow to the frontal and temporal regions. METHOD AND RESULTS: 397 elderly people with sub-clinical cognitive dysfunction were observed over 3 years. Sixteen percent of them developed dementia during the study The prevalence of depressive symptomatology was higher in this group than in the general population, especially in women, who also had higher recovery rates. A changing profile of depressive symptoms was found in depressed elderly people progressing to dementia, with fewer affective symptoms and increases in agitation and motor slowing. These changes were paralleled by greater reductions in left temporal regional cerebral blood flow than in non-depressed subjects with Alzheimer's disease. CONCLUSION: In dementia, there may be two separate and interacting depressive syndromes whose differentiation may be clinically important.

Aged↗
PubMed1999

[Mid-term prognostic value of plasma heavy-chain myosin in thrombolysed myocardial infarction].

Plasma myosin heavy chain assay, which can be easily performed during the acute phase of myocardial infarction, is a recent method allowing quantitative assessment of the extent of infarction. However, to our knowledge, its prognostic value has not been studied in contrast with serum myosin light chain assay. We monitored the state of health of 40 patients (including 37 men with a mean age of 56 years) for two years after a first myocardial infarction, thrombolized during the acute phase. Their survival (mortality) and the development of "cardiac events" (MI, angina, sudden death, etc.) were evaluated at 2 years. The results observed at 2 years were correlated with the initial plasma myosin assay results and other direct and indirect methods of assessment of the extent of infarction, performed during the acute phase of myocardial infarction (cardiac enzymes, contrast angiography). The main result of this study is the demonstration that an unusual plasma myosin release kinetic (complex appearance) is predictive for the medium-term development of heart failure (p = 0.04) and/or destabilization of coronary insufficiency (p = 0.02). These results need to be emphasized, as with only 5 serum myosin assays performed over a 10-day period, it seems possible to identify a group of patients at high risk of medium-term complications, who possess a complex release kinetic during the acute phase of myocardial infarction and a value for area under the curve greater than 10.470 microliters U/L (cut-off value, p = 0.043).

Acute Disease↗
PubMed1998

Semi-automatic segmentation of gated blood pool emission tomographic images by watersheds:application to the determination of right and left ejection fractions.

Tomographic multi-gated blood pool scintigraphy (TMUGA) is a widely available method which permits simultaneous assessment of right and left ventricular ejection fractions. However, the widespread clinical use of this technique is impeded by the lack of segmentation methods dedicated to an automatic analysis of ventricular activities. In this study we evaluated how a watershed algorithm succeeds in providing semi-automatic segmentation of ventricular activities in order to measure right and left ejection fractions by TMUGA. The left ejection fractions of 30 patients were evaluated both with TMUGA and with planar multi-gated blood pool scintigraphy (PMUGA). Likewise, the right ejection fractions of 25 patients were evaluated with first-pass scintigraphy (FP) and with TMUGA. The watershed algorithm was applied to the reconstructed slices in order to group together the voxels whose activity came from one specific cardiac cavity. First, the results of the watershed algorithm were compared with manual drawing around left and right ventricles. Left ejection fractions evaluated by TMUGA with the watershed procedure were not significantly different (p=0. 30) from manual outlines whereas a small but significant difference was found for right ejection fractions (p=0.004). Then right and left ejection fractions evaluated by TMUGA (with the semi-automatic segmentation procedure) were compared with the results obtained by FP or PMUGA. Left ventricular ejection fractions evaluated by TMUGA showed an excellent correlation with those evaluated by PMUGA (r=0. 93; SEE=5.93%; slope=0.99; intercept = 4.17%). The measurements of these ejection fractions were significantly higher with TMUGA than with PMUGA (P<0.01). The interoperator variability for the measurement of left ejection fractions by TMUGA was 4.6%. Right ventricular ejection fractions evaluated by TMUGA showed a good correlation with those evaluated by FP (r = 0.81; SEE = 6.68%; slope = 1.00; intercept = 0.85%) and were not significantly different (P = 0.42). The interoperator variability with TMUGA was 6.7% for the right ventricle. Thus, the watershed algorithm proposed is an efficient segmentation tool for the semi-automatic analysis of right and left ventricular ejection fractions by TMUGA. Further studies are necessary to check whether this procedure can be used to evaluate ventricular volumes and cardiac outflow.

Algorithms↗
PubMed1997

Different morphometric and densitometric parameters predict cervical and trochanteric hip fracture: the EPIDOS Study.

We used an experimental software measuring the hip axis length (HAL) and bone mineral density (BMD) in specific regions of the lower and upper part of the femoral neck on dual-energy X-ray absorptiometry scans. To determine whether these parameters were significant predictors of the type of hip fracture, we measured 167 healthy women (controls), 24 women with trochanteric, and 42 women with cervical hip fractures within the EPIDOS prospective cohort. EPIDOS is a multicenter prospective study on risk factors for hip fracture performed in 7575 elderly women living at home, aged 75-95 and conducted in five French centers (Amiens, Lyon, Montpellier, Paris, Toulouse). Measurements were performed on data acquired at baseline before the occurrence of fracture. In the cervical fracture group, HAL was significantly longer than in controls (94.2 vs. 92.3, p = 0.03), and the associated odds ratio (OR) adjusted for age, weight, and total femoral neck BMD was significant (OR = 1.64, 95% confidence interval [CI] 1.06-2.55). In contrast, HAL was not significantly different from controls in the trochanteric fracture group. Femoral neck diameter was not a predictor of fracture. The upper and lower femoral neck BMD was lower in the trochanteric fracture group than in controls, and both measurements predicted trochanteric femoral neck fracture. In contrast, the prediction of cervical femoral neck fracture was enhanced by measuring only the upper part of the femoral neck (OR = 2.79 vs. 1.97 for the total femoral neck) while BMD of the lower part was not different from controls. Hip axis length is a predictor of femoral neck fracture. Femoral neck BMD distribution is different between cervical and trochanteric fractures. These results support the hypothesis of a different pathophysiological mechanism between the two types of hip fractures.

Absorptiometry, Photon↗
PubMed1996

Ultrasonographic heel measurements to predict hip fracture in elderly women: the EPIDOS prospective study.

BACKGROUND: The ability of ultrasonographic measurements to discriminate between patients with hip fracture and age-matched controls has until now been tested mainly through cross-sectional studies. We report the results of a prospective study to assess the value of measurements with ultrasound in predicting the risk of hip fracture. METHODS: 5662 elderly women (mean age 80.4 years) had both baseline calcaneal ultrasonography measurements and femoral radiography (dual-photon X-ray absorptiometry, DPXA) to assess their bone quality. Follow-up every 4 months enabled us to identify incident fractures. 115 hip fractures were recorded during a mean follow-up duration of 2 years. FINDINGS: Low calcaneal ultrasonographic variables (obtained from measurements of broadband ultrasound attenuation by, and speed of sound through the bone) were able to predict an increased risk of hip fracture, with similar accuracy to low femoral bone mineral density (BMD) obtained by DPXA. The relative risk of hip fracture for 1 SD reduction was 2.0 (95% CI 1.6-2.4) for ultrasound attenuation and 1.7 (1.4-2.1) for speed of sound, compared with 1.9 (1.6-2.4) for BMD. After control for the femoral neck BMD, ultrasonographic variables remained predictive of hip fracture. The incidence of hip fracture among women with values above the median for both calcaneal ultrasound attenuation and femoral neck BMD was 2.7 per 1000 woman-years, compared with 19.6 per 1000 woman-years for those with values below the median for both measures. INTERPRETATION: Ultrasonographic measurements of the os calcis predict the risk of hip fracture in elderly women living at home as well as DPXA of the hip does, and the combination of both methods makes possible the identification of women at very high or very low risk of fracture.

Absorptiometry, Photon↗
PubMed1996

In corticosteroid-treated respiratory diseases, monofluorophosphate increases lumbar bone density: a double-masked randomized study.

The efficacy of a monofluorophosphate-calcium combination (MFP-Ca) in increasing lumbar bone mineral density (BMD) was assessed in a prospective double-masked study. Patients (n = 35), who had been treated for 1 year or more with prednisone-equivalent doses > or = 7 mg/day for asthma or other respiratory diseases, were randomly assigned to receive twice a day, for 2 years, either one MFP-Ca tablet [100 mg sodium monofluorophosphate (13.2 mg F-) + 500.5 mg Ca2+] or one Ca tablet (500.5 mg Ca2+). BMD was measured from L2 to L4 using a dual photon absorptiometer. The eligible patients (7 premenopausal women, 21 men), who had no previous vertebral fractures and were aged 46.5 (21-65) years, had received 18 (7.5-60) mg prednisone-equivalent/day and had a mean lumbar BMD of 0.917 +/- 0.141 g/cm2 at baseline (MO); in these 28 patients, the mean increase in lumbar BMD at final assessment was significantly greater in the MFP-Ca group (p = 0.05; Mann-Whitney). There was also a significant difference after 2 years between the two groups (p = 0.05, ANOVA) in favour of MFP-Ca, with an increase in lumbar BMD of 11% (MFP-Ca) compared with 1% (Ca); thus, with MFP-Ca, lumbar BMD increased by an average of approximately 5.5%/year. There was no statistically significant difference between the two groups in doses of corticosteroids used during the 2 study years, rate of vertebral fractures, or frequency of side-effects (which were all minor). No bone fissure was observed. Thus, the daily dose of 200 mg monofluorophosphate (26.4 mg F-) combined with 1 g Ca2+ in patients with long-term corticosteroid-treated respiratory diseases appears to be a safe and efficient way of increasing lumbar BMD, suggesting that its use should be further studied in corticosteroid-induced osteoporosis.

Absorptiometry, Photon↗
PubMed1995

The use of technetium-99m hexamethylpropylene amine oxime labelled granulocytes with single-photon emission tomography imaging in the detection and follow-up of recurrence of infective endocarditis complicating transvenous endocardial pacemaker.

In this case report we present a patient with a recurrence of subacute bacterial infectious endocarditis (IE) complicating a transvenous endocardial pacemaker. Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) labelled granulocytes were used for diagnosis and follow-up under medical treatment only, since surgical removal of the pacemaker lead was ruled out because of the general condition of the patient. Single-photon emission tomography (SPET) imaging displayed the active lesion previously suspected on echography. At the end of antibiotic therapy, SPET indicated a favourable disease outcome whereas echocardiographic abnormalities remained nearly unchanged. The medical treatment had eradicated the IE, and the patient did well for more than 1 year thereafter.

Aged↗
PubMed1995

Optimum tomographic reconstruction parameters for HMPAO brain SPET imaging: a practical approach based on subjective and objective indexes.

The purpose of this study was to define an optimal strategy for the tomographic reconstruction procedure in routine brain single-photon emission tomography (SPET) studies, including the number of projections, filter function and matrix size. A set of projection data with different count densities was obtained from a technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) brain SPET acquisition from one volunteer. The projections were reconstructed with different filters and the quality of the reconstructed images was determined using both a subjective observer rating score and the Gilbert index. For each count density, the observers' choice corresponded to images with the lowest Gilbert index. The noise level in brain SPET sections was estimated and correlated with the fractal dimension. The results of this study indicate that although noise represents a fundamental component of brain SPET imaging, image quality also depends on the reconstructed spatial resolution. Image quality is satisfactorily described by fractal dimension. In addition the optimal filter function depends on the available count density. For high count levels, optimal reconstruction may be obtained by using a high-resolution matrix and a slightly smoother reconstruction filter. When count densities are low, best results are obtained by using a low-resolution matrix and a sharper filter. Finally, this study suggests that image quality is not influenced by the number of projections for equivalent count densities. These results were confirmed by 30 HMPAO brain SPET studies acquired in a routine clinical setting.

Brain↗
PubMed1995

The relationship between osteoarthritis of the hands, bone mineral density, and osteoporotic fractures in elderly women.

To study the relationship between osteoarthritis (OA) and osteoporosis (OP), radiographic osteoarthritis lesions of the hands (HOA) were quantified in 300 healthy women, aged 75 years or more, as a subgroup of a cohort originally recruited for a multi-centre study of risk factors for femoral neck fracture. The HOA combined score (i.e. the sum of the grades of joint-space narrowing, osteophytes, erosions and joint misalignment), the osteophytosis score and the joint-space narrowing score were calculated on a radiograph of both hands. Bone mineral density (BMD) was measured using dual-energy X-ray absortiometry (Lunar DPX) at the femoral neck, Ward's triangle and the total body. BMDs of the total spine, lumbar spine, and the upper and lower limbs were derived from the regional analyses of the total body measurement. Correlations between bone mass, HOA scores and other variables were explored by multiple linear regression and stepwise logistic regression analysis. The HOA combined score was positively correlated with increasing age but not with body mass index. In the multiple regression analyses the HOA combined score positively correlated with BMD and the joint-space narrowing score. According to stepwise logistic regression and after off adjustment of BMD for age, women with an HOA combined score higher than 20 had significantly higher BMD values at all skeletal sites. Sixty-nine women (23%) reported a history of osteoporotic fracture; among them, 20 (6.6%) reported a history of vertebral fracture. The OA score of both subgroups was significantly lower than that of women with no history of fracture. These data suggest that in elderly women the severity of HOA is positively correlated with bone mass and that women with a higher score of HOA more rarely report a history of osteoporotic fracture.

Aged↗
PubMed1995

Do ultrasound measurements on the os calcis reflect more the bone microarchitecture than the bone mass?: a two-dimensional histomorphometric study.

Few studies have analyzed the relationship between ultrasound measurements (US) and corresponding histomorphometric parameters of the calcaneus. To address this question we have compared US and histomorphometric parameters in 17 whole human os calcis from amputation or necropsy. Speed of sound (SOS), broadband ultrasound attenuation (BUA), and bone mineral density (BMD) were measured on the whole foot at the calcaneal site using an Achilles device and a DPX-L densitometer (Lunar). The os calcis was dissected and a 1-cm-wide transcortical parallelepiped extracted with a biopsy needle, focused on the center of the measured area. Histomorphometry was performed on undecalcified biopsies. Structural and connectivity parameters were measured on 7-microns-thick sections with both automatic (Biocom) and semiautomatic analyzers (Ibas 1, Kontron). We found that all ultrasonic and densitometric parameters reflected the true amount of bone and were correlated with only some of the parameters reflecting bone microarchitecture. From stepwise regression analysis, we found that 68%, 67%, 72%, and 74% of the variance of SOS, BUA stiffness, and BMD, respectively, were explained significantly by trabeculae thickness only. Ultrasonic measurements appear to reflect bone quantity rather than bone microarchitecture. The current conclusion is fairly negative with respect to the ability of ultrasound to assess structural parameters, but our limited sample size did not give enough power to our study to reach statistically significant correlations. In addition, the calcaneus is anisotropic and the ultrasound interaction in bone is a three-dimensional phenomenon. So, a three-dimensional study rather than a two-dimensional one should be performed.

Absorptiometry, Photon↗
PubMed1994

Influence of fat on ultrasound measurements of the os calcis.

Measurements of the speed-of-sound (SOS) and of the broadband ultrasound attenuation (BUA) on the os calcis were recently proposed to assess osteoporotic fragility. Velocity and attenuation were measured through the heel which can be divided in three phases including hydroxyapatite, soft tissue, and fat. The aim of this study was to evaluate the influence of fat composition and heel width on SOS and BUA. This influence was determined from both in vitro investigations examining fat samples, phantoms, and cadaver heels, and in vivo ones observing adult volunteers as well as a wide sample section of healthy elderly women. Ultrasound velocities on various fat samples were significantly lower than those on distilled water (-65 m/second to -123 m/second). The excision of the surrounding soft tissue from cadaver heels made SOS steadily increase whereas the insertion of a 10 mm piece of lard in the lateral face of cadavers' and volunteers' heels os calcis lowered SOS about 30 m/second. Furthermore, a difference of SOS was estimated at 15 m/second for a 12.5% variation of the marrow fat weight. Among 334 elderly and healthy women aged 75 and over, a significant negative correlation was found between SOS and heel width (r = -0.27; P < 0.0001). On the other hand, fat composition had no significant effect on BUA measurement, and no significant relationship was found between BUA and heel width. This study demonstrates that an increase of heel width and fat thickness provides an underestimation of os calcis SOS, but has no significant effect on BUA.

Adipose Tissue↗
PubMed1993

Measurement of the bone mineral density of the os calcis as an indication of vertebral fracture in women with lumbar osteoarthritis.

In women with lumbar osteoarthritis, measurement of the os calcis bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA) as an indication of vertebral fracture was evaluated. The in vivo precision of the method was 1.28%. Age- and sex-matched control curves were evaluated using a control of 193 females. The correlation between spine BMD and os calcis BMD was significant (r = 0.65, p << 0.001). For the osteoporotic women without osteoarthritis (n = 34), there was no significant difference in the spine and the os calcis Z-scores (-1.99SD and -1.83SD respectively). Whereas for osteoporotic women with osteoarthritis (n = 30) the spine Z-score was -0.49SD the os calcis Z-score was -1.92SD. The difference was significant (p < 0.001). Receiver operating characteristic (ROC) curves demonstrate the superiority of the os calcis as a measurement site over the lumbar spine, in correlation with existing crush fractures in the presence of osteoarthritis. It is concluded that when lumbar osteoarthritis occurs measurement of the os calcis BMD using DEXA is clinically useful for the estimation of bone mass.

Absorptiometry, Photon↗
PubMed1992

Prototype of dual energy x-ray tomodensimeter for lumbar spine bone mineral density measurement: choice of the reconstruction algorithm and first experimental results.

A dual-energy x-ray tomodensimeter adapted for the determination of bone mineral density (BMD) of the lumbar vertebrae has been directly developed from a typical dual-energy x-ray absorptiometer. This apparatus consists of two fundamental parts: a dual energy x-ray tube, and a multidetector made by an array of 24 NaI(T1) crystals. It provides both tomographic and non-tomographic (anteroposterior, lateral etc) measurement. The detection area is limited to 132 mm. In this condition, the choice of the best reconstruction algorithm in order to give a direct BDM is considered. Preliminary studies based on numerical simulated projections and hydroxyapatite phantoms demonstrated the superiority of algebraic reconstruction algorithms, such as conjugated gradient, in order to resolve the problems of (i) the impossibility of defining an internal calibration, and (ii) the potential for reconstruction errors due to the presence of bone structures located out of the detection area. The accuracy of BMD measurement is within 2%, with in vitro precision approximately 1%, and linearity characterized by a standard error of estimation (SEE) of 2 mg cm-3 in the range of lumbar BMD (less than 400 mg cm-3). Experimental data derived from two volunteers are presented.

Algorithms↗