Search

This paper presents a novel methodology for short-term load forecasting in the context of significant shifts in the daily load curve due to the rapid and extensive adoption of Distributed Energy Resources (DERs). The proposed solution, built upon the Similar Days Method (SDM) and Artificial Neural Network (ANN), introduces several novelties: (1) selection of similar days based on hidden representations of day data using Autoencoder (AE); (2) enhancement of model generalization by utilizing a broader set of training examples; (3) incorporating the relative importance of training examples derived from the similarity measure during training; and (4) mitigation of the influence of outliers by applying an ensemble of ANN models trained with different data splits. The presented AE configuration and procedure for selecting similar days generated a higher-quality training dataset, which led to more robust predictions by the ANN model for days with unexpected deviations. Experiments were conducted on actual load data from a Serbian electrical power system, and the results were compared to predictions obtained by the field-proven STLF tool. The experiments demonstrated an improved performance of the presented solution on test days when the existing STLF tool had poor predictions over the past year. [ABSTRACT FROM AUTHOR]

Background/Aim. The most frequent therapeutic method for achalasia is balloon dilatation (BD). Esophageal scintigraphy is potentially the most convenient method for the evaluation of achalasia by quantifying esophageal transit. The aim of this study was to present the results of esophageal scintigraphy (ES) in achalasia treated by BD for a long period of time, from 1997 to 2016, and to set parameters suitable for predicting treatment outcomes. Methods. Two-phase ES in anterior projection was performed. The first phase involved swallowing 10 mL of water with 18.5 MBq 99mTc in a supine position. The second phase was performed in a standing position after swallowing 100 mL of water. The retention index (RI) of esophageal radioactivity was calculated after the imaging using registered esophageal and gastric counts. ES was performed in 52 patients (34 males and 18 females, aged 22–75 years, the median age 44 years) before and after BD. In 31 patients, only two scintigraphies were performed. In the remaining 21 patients, follow-up and repeated scintigraphies were continued including the patients with therapeutic failure and repeated BD. BD was repeated in 8 patients, and those were followed up and evaluated over time. Modified BD was performed with Rigiflex balloon dilators. Results. A typical scintigraphic finding in the supine position was passive esophageal filling without the evidence of motility, and in most patients, 43 of them (83%), radionuclide elimination in the stomach was absent. Evaluating values before and long after the first BD, it was shown that certain values of RI indicated remission or relapse of the disease. The RI difference higher than 50% after BD was a reliable indicator of a longer remission. The age and gender of patients had no impact on the outcome of dilatation, but younger patients were with a higher risk of early failure (6 patients during the first year after BD). ES showed that the first BD was initially successful in 50 patients and after the follow-up in 41 (79%) patients. Conclusion. A two-phase supine/standing ES is most suitable for diagnosing and the follow-up of achalasia. RI represents an important parameter for the evaluation and prediction of therapeutic response. The RI difference of more than 50% after BD is a reliable predictor of a longer remission. Age and gender have no impact on dilatation outcome, but patients younger than 40 years have a higher risk of early therapeutic failure.

Background/Aim. There is a constant and dramatic in-crease in hip and knee prosthetic implantations worldwide. However, a decrease in the percentage of failed (infected) prosthetic implantations is not significant (0.5% up to 2%). The real challenge is whether prosthetic joint loosening was caused by aseptic inflammation or by infection. The aim of the present study was to attempt to distinguish sterile inflammation from infection in patients with a painful hip or knee prosthetic joint. Another objective was to determine the accuracy of cumulative bone scintigraphy with methylenediphosphonate (MDP) and ciprofloxacin in diagnosis of periprosthetic joint infection (PJI). Methods. Three-phase bone scintigraphy with 99mTc-MDP and 99mTc-ciprofloxacin was used. The patient selection criterion for this study was a suspicion of PJI followed by painful and limited movement of the prosthetic joint, accompanied by elevated unspecific inflammatory factors. Forty five patients with 39 implanted hips and 24 knee prostheses were included and evaluated. All prosthetic joints were examined (although some of them were asymptomatic) and underwent plain radiography. An average time span between the two nuclear medicine imaging procedures was 3–5 days. Three-phase 99mTc-MDP bone scintigraphy was performed first. Scintigraphy with 99mTc-ciprofloxacin was necessarily involved calculation of the accumulation index. The obtained results were confirmed by microbiological findings as a gold standard. Statistical analysis of the results was performed using SPSS version 20 software (descriptive statistics, χ2-test). Sensitivity, specificity, and predictive values were also calculated. Results. Microbiologically confirmed PJI was found in 16 out of 39 hip prostheses. Positive scintigraphy was obtained in 15 out of 39 prosthetic hip joints. PJI was found using scintigraphy of the knee, and microbiologically con-firmed in all 13 out of 24 suspected joints. Estimated sensitivity/specificity of 99mTc-MDP bone scintigraphy alone (for both joints) was 90%/69%, for 99mTc-ciprofloxacin scintigraphy it was 93%/97%, and for cumulative results it was 96.5%/97%. Conclusion. Cumulative 99mTc-MDP scintigraphy with 99mTc-ciprofloxacin scintigraphy increases the ability of differentiation between aseptic loosening and PJI, with high accuracy of 97%.

This manuscript presents experimental studies of composite materials based on poly (L lactic acid) (PLLA) and poly (3-hydroxybutyrate) (PHB) matrices filled with electrolytic copper powder, having a very high dendritic structure. Volume fractions of the copper powder used as filler in all prepared composites were varied in the range 0.5-6.0 vol.%. Samples were prepared by hot moulding injection at 170 °C. Influence of particle size and morphology, as well as the influence of matrix type on conductivity and percolation threshold of the obtained composites were examined. Characterization included: electrical conductivity measurements using AC impedance spectroscopy (IS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform Infrared spectroscopy (FTIR). Presence of three-dimensional conductive pathways was confirmed. The obtained percolation thresholds of 2.83 vol.% for PLLA and 3.13 vol.% for PHB composites were measured, which is about three times lower than the ones stated in the literature for similar composites. This property is ascribed to different morphologies of the filler used in the present investigation. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172046 and Grant no. ON172060]

Background/Aim. Although the number of new primary implantation of hip and knee prostheses every year increases, the rate of failed arthroplasty is nearly the same. The main question is whether it is an aseptic instability or instability caused by infection. The aim of this preliminary study was an attempt with combined 99mTc-ciprofloxacin and 99mTc-methylene diphosphonate (MDP) bone scintigraphy to improve diagnostic accuracy in the differentiation of hip and knee prosthesis aseptic loosening and periprosthetic joint infection. Methods. Inclusion criteria of patients for this study were based on suspected periprosthetic joint infection: painful prosthetic joint, restricted joint movements and increased value of erythrocyte sedimentation rate or levels of C-reactive protein. We examined 20 patients with implanted 14 hip and 6 knee prosthesis. All patients also underwent plain radiography of suspected joint. In all patients, three-phase 99mTc-MDP bone scintigraphy was performed. Three to five days after the bone scan, we performed scintigraphy using 99mTc-ciprofloxacin with the calculation of accumulation index. Periprosthetic joint infection was confirmed on the basis of microbiological findings. Results. Periprosthetic joint infection was confirmed in fourteen of twenty observed joints, in five of them the aseptic loosening was present and in one patient’s symptoms were not related to the prosthesis (poor biomechanics of prosthetic joints caused by weaknesses of muscle). Estimated sensitivity/specificity for 99mTc-MDP bone scintigraphy alone were 100/17%; for 99mTc-ciprofloxacin scintigraphy were 85,7/100%. Sensitivity and specificity were 92,3% and 83,3%, respectively for results obtained with combined assessment by both methods. Our study confirmed the high negative predictive value of 99mTc-MDP bone scan. The negative result of bone scan virtually excludes the possibility of periprosthetic infection. On the other hand, positive findings of 99mTc-MDP scintigraphy cannot with certainty confirm the infection. Conclusion. Combined 99mTc-MDP scintigraphy with 99mTc-ciprofloxacin scintigraphy significantly increases the ability of differentiation of aseptic loosening from periprosthetic joint infection.

Levinas confirms: a reflection about a money as a social and economical reality is not possible without a serious analysis of empirical data. On the other hand, this reflection always involves something else, so a money is never a merely economical category. In that sense, Levinas proposes an intriguing meditation about some “dimensions” of a money in the western tradition. Contrary to the traditional moral condemnation of a money - which however remains unquestionable because of the fact that a man always carries a risk of becoming a merchandise - Levinas suggests that money never simply means a reification, but always implies some positive dimensions. Levinas suggests that a money is not something morally bad or simply neutral covering human relationships, but rather a condition of human community. Furthermore, he claims that a money is a fundament of the justice. A money makes possible a community, he explains, because it opens up the dimension of the future, and implies the existence of human beings who give themselves a credit; a credit understood as a time and a confidence. We shall try to address some problems implied by this thesis, particularly the problem of the relationship between time, money and credit. Finally, we are going to ask whether this cred­it - inseparable from the very essence of the money - is not always already a sort of usury.

Background/Aim. Balloon dilatation is a standard approach to the initial achalasia treatment. Modified dilatation is also applied to rise efficacy and to lower complications. Methods. A total of 57 patients were analysed within a median follow-up of 8.2 years. No premedication was used, dilatation was performed up to the pain treshold, while introduction and positioning of a dilatator was done in combination of endoscopic and radiological control. Dilatation effect was estimated by both Kim Symptom Scoring and objective parameters: body weight rise and radiological scintigraphic findings. Results. Excellent and good results were obtained in 50 (88%) of the patients, while in 7 (12%) of the patients surgery was performed. There was no difference in dilatation efficacy regarding sex of the patients, but the results were better in the patients above 40 years. Duration of symptoms, body weight loss, esophageal lumen width do not indicate the definitive dilatation outcome. Esophageal scintigraphy and body weight increase were in a direct correlation with the effect of dilatation measured with the Kim Symptom Scoring. After the one to two repeated dilatations the efficacy increased from 74% to 88% justifying the repetition of dilatation. In 2 (3.57%) of the patients, that is in 2.65% of the totally dilated patients, perforation was recorded. There was no lethal outcome of dilatation, and the other complications were not clinically significant. Conclusion. Modified balloon dilatation can be recommended for initial method in achalasia treatment due to high efficacy, easy performance in daily hospital while complications are in standard range.

Background/Aim. Parathyroid hyperplasia (PHP) is defined as an absolute increase in the mass of parenchymal cells of the parathyroid gland. PHP is classified as primary, secondary and tertiary. The enlargement of parathyroid glands (PG) is usually asymmetric, resulting in a “dominant“ gland. In order to confirm the diagnosis, at least two glands should be examined histologically. Subtotal parathyroidectomy, i.e. removal of the three PG and leaving a small remnant of the forth, is the treatment of choice. High percent of PHP recurrence imposes the need for preoperative high sensitivity localizing procedures. Parathyroid scintigraphy localizes about 60% of hyperplastic glands. The aim of this study was to correlate findings of subtraction parathyroid scintigraphy (SPS) with weight, pathohistologic finding and oxyphil cell (OC) content of PG in patients with primary, secondary and tertiary parathyroid hyperplasia. Methods. Twenty-seven patients with primary/secondary PHP underwent SPS before surgery. Scintigraphic results were graded from 1-5, in relation to the degree of uptake. SPS graded 3, 4 and 5 were considered positive. The number and weight of operated PG were evaluated macroscopically. Pathohistologic and cellular types were defined on standard stained hematoxylin-eosin slides. OC content was defined as a percent of OC and graded from 1 to 3: grade 1 < 10%, grade 2 ≥ 10% and grade 3 ≥ 20% of OC. Results. SPS localized dominant gland in all patients with sensitivity 100%, and 51 from 73 hyperplastic PG, with sensitivity per gland of 70%. PG weighed 0.1 g to 6.7 g (median 1 g). A significant positive correlation (p < 0.0001) was found between the SPS results and PG weight. A significant positive correlation was found between PG weight and OC content (p = 0.0002). An insignificant correlation was found between SPS and OC content. Thirty-eight PG had < 10% of OC, 32 PG had < 10% and 3 PG had ≥ 20% of OC. Four patients had diffuse PHP and 23 patients nodular PHP. There was no statistically significant difference in SPS results compared to hyperplasia type, and between OC content and hyperplasia type. A significant positive correlation (p = 0.05) was found between PG weight and hyperplasia type. Conclusion. A high positive correlation was found between SPS results and PG weight, PG weight and OC content and PG weight and hyperplasia type. Between SPS results and OC content, and between SPS results and hyperplasia type, an insignificant correlation was found. Our results showed that SPS is a reliable and very sensitive diagnostic tool in detecting abnormal PG in parathyroid hyperplasia, reaching 100% sensitivity in detecting a “dominant gland” and sensitivity per localized gland of 70%. Causes that affect increased uptake of liposolubile Tc99m radiopharmaceuticals (RF) in the hyperfunctional PG tissue and conditions which prevent RF admission into the PG cells still remain to be accurately and precisely determined.

Background/Aim. 99mTc-ciprofloxacin is a radiopharmaceutical preparation sintetized to improve diagnostic accuracy of bacterial infections in human tissues. It is mostly applied in diagnosis of bone and joint infections. Many papers have confirmed its sensitivity to infection, but newer papers argued its specificity. The aim of this study was to compare the results of visual analysis of scintigrams to semiquantitative calculations of accumulation indexes with the assumption that calculation of indexes would improve the specificity for bone and joint infections. Methods. We examined 40 patients, 25 with confirmed bone and joint bacterial infections and 15 patients with bone and joint diseases without bacterial infection. Scintigraphy was performed 5 minutes, 1, 4 and 24 hours after intravenous (iv) injection of 99mTc-ciprofloxacin. Scintigrams were analyzed visually and by calculation and comparation of accumulation indexes values. Results. Visual sensitivity was 94%, but specificity only 47%. Index calculation achieved much higher specificity (100% after 1, 4 and 24 hours for cut off value of 1.50). All basic index values (5 min) in the patients with infections increased in 24 hours. In 8 patients without infection occurred a slight increase and in 7 patients decrease of basic index values. Conclusion. Calculation of accumulation index values is needed in the use of 99mTc-ciprofloxacin scintigraphy as it is the only way to improve specificity for bacterial bone infections. Visual interpretation of results is sensitive, but not specific due to accumulation of the drug in a high percent of non infected bone and joint lesions.

Background/Aim. Primary hyperparathyroidism (pHPT) is an endocrine disease with the third highest incidence of all endocrine disorders after diabetes mellitus and hyperthyroidism. pHPT is typically caused by a solitary parathyroid adenoma, less frequently by multiple parathyroid gland disease (MGD) and rarely by parathyroid carcinoma. Secondary hyperparatyroidism (sHPT) is a common complication in patients with chronic renal failure. The aim of this study was to estimate sensitivity of dual tracer 99mTctetrofosmin and 99mTc-pertechnetate subtraction scintigraphy in detection of abnormal parathyroid glands in patients with pHPT and sHPT confirmed by histopathology. Methods. In 46 patients, (77 abnormal parathyroid glands), 30 with pHPT and 16 with sHPT parathyroid scintigraphy was done preoperatively. All the patients had histopathological confirmation of diagnosis. Abnormal parathyroid glands weighted from 0.1 to 7 g. After iv injection dynamic scintigraphy during 25 minutes (one frame-one minute) using 555 MBq of 99mTc-tetrofosmin, and three hours latter using 111 MBq of 99mTc /pertechnetate was performed. 99mTc-tetrofosmin dynamic study was followed by static scintigraphy of the neck and chest 30 minutes, 1, 2 and 3 hours after iv injection. Results. An abnormal scintigraphic finding was found in 44 of 46 patients with sensitivity of 96%. In pHPT sensitivity was 93% (28 of 30 patients, and 28 of 30 glands). In sHPT scintigraphy was abnormal in all the patients (sensitivity 100%). In the patients with sHPT scintigraphy detected 30 of 47 abnormal parathyroid glands (sensitivity 64%). An overall sensitivity of scintigraphy per gland, for pHPT and sHPT in detecting 58 of 77 abnormal parathyroid glands was 75%. Conclusion. An abnormal scintigrafic result per patient was found in 44 patients (sensitivity 96%) and 58 of 77 abnormal parathyroid glands were detected (sensitivity 75%). A high sensitivity of dual tracer subtraction 99mTc-tetrofosmin/99mTc-pertechnetate parathyroid scintigraphy in detecting abnormal parathyroid glands in primary and secondary hyperparathyroidism was achieved.

Background/Aim. The most frequent method for the assessment of glomerular filtration rate GFR) in clinical practice is clearance of creatinine, clearance of chromium-51 radiolabelled ethylene diamine tetraacetic acid (51Cr-EDTA) and clearance of technetium-99m radiolabelled diethylene triamine pentaacetic acid (99mTc-DTPA). The Gates method for glomerular filtration rate assessment is based on distribution of 99mTc-DTPA in the kidney 2-3 minute after its applying. Calculation of GFR is corrected for the background and depth of the kidney and finally expressed as a percentage of the net injected counts. This value of GFR highly correlates with biexponential model as the most accurate method for the assessment of GFR. The aim of this study was to determine the influence of different background sites on GFR rate assessment using the Gates method. Methods. We analysed 50 patients who were divided into two groups: the group of healthy subjects (21 subjects, mean age 47.38 yrs) and the group of subjects with unilateral kidney damage (29 subjects, mean age 39.79 yrs). Three different background activity regions were chosen: a region drawn below the lower pole of each kidney, region drawn by the lateral side of each kidney and region drawn around the whole kidney. Results. Gromerular filtration rate calculated by the use of a region under the lower pole is statistically significantly higher than GFR calculated using a region by the lateral side and around the whole kidney (p < 0.0001). Glomerular filtration rate calculated using the region by the lateral side and region around the whole kidney did not show statistically significant difference (p > 0.05). Conclusion. The selection of background activity region has a significant influence on GFR rate measured by the Gates method. It is recommended to use only one method for choosing the region of background activity.

Background/Aim. The coronary angiography provides information on the anatomical state of the coronary tree, while myocardial perfusion scintigraphy (MPI) facilitates the evaluation of the grade of ischaemia that a particular stenosis produces. The purpose of MPI is to detect the coronary stenosis that provokes the ischaemia and is termed the "culprit lesion". The aim of this study was to evaluate the accuracy of 1-day DypEX 99mTc-tetrofosmin tomography in the identification and localization of culprit lesion in the patients with known coronary artery disease (CAD). Methods. Ninety-one (91) patients with known CAD were studied. In all of them significant coronary narowing (≥ 75% luminal stenosis) was angiographically detected. All the patients were submitted to 2 iv. injections of 99mTc-tetrofosmin, one in a peak of pharmacologic dipyridamole stress protocol with concomitant low level bicycle exercise 50W (DypEX) and the other 3 h after exercise. Quantification of regional tetrofosmin uptake was performed using short-axis myocardial tomogram that was divided on 17-segments for each study. Reversibility scor (RS) ≥ 3 determinated culprit lesion. Two of segments with scor 5 (index of reversibility scor - IRS) in the territory of coronary artery stenoses determinated culprit lesion. Results. A total of 273 vascular territories (4641 segments) were analyzed before percutaneous coronary intervention (PCI). Overall sensivity, specificity, and accuracy using RS ≥ 3 and IRS were 90.1%, 87.1%, 89.4%, with positive predictive value 95.8%, and 94.1%, 93.3%, 94%, with positive predictive value 98%, respectively. Conclusion. RS and IRS significantly improve sensitivity, specificity, and accuracy for determination of culprit lesion in patients undergoing PCI.

Background/Aim. Detection of metastatic bone disease by skeletal scintigraphy is a classical application of nuclear medicine in cancer patients. Detection of bone metastases in patients with lung cancer is necessary for an appropriate treatment modality. The aim of this study was to report the frequency and imaging characteristics of bone metastases detected by bone scintigraphy (BS) using technetium-99m phosphonates in patients with lung cancer. Methods. We retrospectively analyzed a total of one hundred patients (78 males and 22 females), mean age of 63.3 years, with the diagnosis of lung cancer, who underwent BS during a three-year period (2003−2005). Scintiscans were classified as positive, negative and suspicious with regard to the presence of bone metastases. Results. The incidence of positive, negative and suspicious findings were 57%. 32% and 11%, respectively. Out of 57 patients with bone metastases, 51 had multiple asymmetric foci of increased tracer activity localized in the ribs, spine, extremities, pelvis, sternum, scapula and skull in 72%, 54%, 49%, 37%, 12%, 9% and 5% of scans, respectively. BS revealed solitary metastases in 6 of the patients. The lesions were located in the lower limbs in three patients and in the upper limbs, pelvis and sternum in the remaining three patients. Conclusion. Bone scintigraphy plays a significant role in staging and selecting of patients for curative lung surgery. Due to the fact that metastatic involvment of the extremities was frequently shown, our study suggests that systematic inclusion of the limbs in BS acquisition should be obligatory.

The aim of this study was to evaluate the accuracy of myocardial perfusion scintigraphy with technetium-99m tetrofosmin by single-photon emission computed tomography (SPECT), using one-day protocol in the identification and localization of individual stenosed coronary vessels. Sixty-eight patients with suspected coronary artery disease (CAD) were studied. In thirty of them coronary angiography showed significant stenosis (³50%). Nine patients were with one-vessel disease, 11 were with two-vessel disease, and 10 were with three-vessel disease. All the patients were administered two i.v. injections of 99mTc tetrofosmin, one at peak pharmacologic exercise (1-3 min after i.v. administration of dipiridamol 0.56 mg per kg during 4 min) 370 MBq, and the other 740 MBq at rest 3 hrs after the exercise test (acquisition was obtained 15-30 min after injections for both studies). Overall sensitivity, specificity, and diagnostic accuracy in the identification of individual stenosed coronary vessels were 90%, 86%, and 88%, respectively. Sensitivity, specificity, and accuracy in each of the individual vascular territories were not significantly different: LAD (96% 64%, and 75%), ACx (73%, 100%, and 94%), RCA (95%, 93%, and 94%). The results of this study demonstrated one-day 99mTc-tetrofosmin SPECT scintigraphy to be suitable and accurate technique for the identification and localization of individual stenosed coronary vessels, as well as a highly sensitive method in the recognition of one- and multiple-vessel diseases of coronary arteries.

Background/Aim. There is a constant and dramatic increase in hip and knee prosthetic implantations worldwide. However, a decrease in the percentage of failed (infected) prosthetic implantations is not significant (0.5% up to 2%). The real challenge is whether prosthetic joint loosening was caused by aseptic inflammation or by infection. The aim of the present study was to attempt to distinguish sterile inflammation from infection in patients with a painful hip or knee prosthetic joint. Another objective was to determine the accuracy of cumulative bone scintigraphy with methylenediphosphonate (MDP) and ciprofloxacin in diagnosis of periprosthetic joint infection (PJI). Methods. Threephase bone scintigraphy with 99mTc-MDP and 99mTcciprofloxacin was used. The patient selection criterion for this study was a suspicion of PJI followed by painful and limited movement of the prosthetic joint, accompanied by elevated unspecific inflammatory factors. Forty five patients with 39 implanted hips and 24 knee prostheses were included and evaluated. All prosthetic joints were examined (although some of them were asymptomatic) and underwent plain radiography. An average time span between the two nuclear medicine imaging procedures was 3-5 days. Threephase 99mTc-MDP bone scintigraphy was performed first. Scintigraphy with 99mTc-ciprofloxacin was necessarily involved calculation of the accumulation index. The obtained results were confirmed by microbiological findings as a gold standard. Statistical analysis of the results was performed using SPSS version 20 software (descriptive statistics, X2-test). Sensitivity, specificity, and predictive values were also calculated. Results. Microbiologically confirmed PJI was found in 16 out of 39 hip prostheses. Positive scintigraphy was obtained in 15 out of 39 prosthetic hip joints. PJI was found using scintigraphy of the knee, and microbiologically confirmed in all 13 out of 24 suspected joints. Estimated sensitivity/specificity of 99mTc-MDP bone scintigraphy alone (for both joints) was 90%/69%, for 99mTc-ciprofloxacin scintigraphy it was 93%/97%, and for cumulative results it was 96.5%/97%. Conclusion. Cumulative 99mTc-MDP scintigraphy with 99mTc-ciprofloxacin scintigraphy increases the ability of differentiation between aseptic loosening and PJI, with high accuracy of 97%. [ABSTRACT FROM AUTHOR]

Background/Aim. In the last five decades primary hip and knee arthroplasty is the most common and effective surgical intervention worldwide. Infection, although unfrequented, is the most serious complication. Nuclear medicine imaging, not affected by metallic hardware, is the current imaging modality of choice for the evaluation of suspected joint replacement infection. The aim of this study was to estimate the diagnostic accuracy of three phase 99m technetium methylene diphosphonate (99mTc-MDP) bone scintigraphy in periprosthetic hip and knee joint infection. Methods. Inclusion criteria of patients in the study were suspected knee or hip periprosthetic joint infections. In this study, we examined 45 patients (14 men and 31 women) with 39 hip and 24 knee prosthesis (total 63). In all patients, three-phase bone scintigraphy was performed after intravenous application of 555 MBq of 99mTc-MDP. The final confirmation of infection was microbiological or pathohistology finding. Results. Infection was confirmed in 29 prosthetic joints, in 13 (44.8%) knee and 16 (55.2%) hip joints while there was no infection in 34 prosthetic joints. The connection of different modalities of negative and positive findings 99mTc-MDP three-phase bone scintigraphy with the final confirmation of infection showed a high statistical significance (p < 0.001). Three phase bone scintigraphy showed a high sensitivity of 90% but a modest specificity of 69.7% in the detection of periprosthetic infection with the diagnostic accuracy of 79%. The calculated positive predictive value was 73% but the negative predictive value was high 89%. Our results of three-phase bone scintigraphy with calculated sensitivity, specificity and diagnostic accuracy of 79% are in consent with the majority of published studies, or even slightly better. Conclusion. Bone scintigraphy is sensitive in the diagnosis of periprosthetic infection but insufficiently specific. In the detection of periprosthetic infections three-phase bone scan can be used as a diagnostic method of the first line only aimed at its exclusion. The only reasonable use of bone scintigraphy is in combination with other radionuclide methods with high specificity. [ABSTRACT FROM AUTHOR]

Background/Aim. Although the number of new primary implantation of hip and knee prostheses every year increases, the rate of failed arthroplasty is nearly the same. The main question is whether it is an aseptic instability or instability caused by infection. The aim of this preliminary study was an attempt with combined 99mTc-ciprofloxacin and 99mTc-methylene diphosphonate (MDP) bone scintigraphy to improve diagnostic accuracy in the differentiation of hip and knee prosthesis aseptic loosening and periprosthetic joint infection. Methods. Inclusion criteria of patients for this study were based on suspected periprosthetic joint infection: painful prosthetic joint, restricted joint movements and increased value of erythrocyte sedimentation rate or levels of C-reactive protein. We examined 20 patients with implanted 14 hip and 6 knee prosthesis. All patients also underwent plain radiography of suspected joint. In all patients, three-phase 99mTc-MDP bone scintigraphy was performed. Three to five days after the bone scan, we performed scintigraphy using 99mTc-ciprofloxacin with the calculation of accumulation index. Periprosthetic joint infection was confirmed on the basis of microbiological findings. Results. Periprosthetic joint infection was confirmed in fourteen of twenty observed joints, in five of them the aseptic loosening was present and in one patient’s symptoms were not related to the prosthesis (poor biomechanics of prosthetic joints caused by weaknesses of muscle). Estimated sensitivity/specificity for 99mTc-MDP bone scintigraphy alone were 100/17%; for 99mTc-ciprofloxacin scintigraphy were 85,7/100%. Sensitivity and specificity were 92,3% and 83,3%, respectively for results obtained with combined assessment by both methods. Our study confirmed the high negative predictive value of 99mTc-MDP bone scan. The negative result of bone scan virtually excludes the possibility of periprosthetic infection. On the other hand, positive findings of 99mTc-MDP scintigraphy cannot with certainty confirm the infection. Conclusion. Combined 99mTc-MDP scintigraphy with 99mTc-ciprofloxacin scintigraphy significantly increases the ability of differentiation of aseptic loosening from periprosthetic joint infection. [ABSTRACT FROM AUTHOR]

Background/Aim. 99mTc-ciprofloxacin is a radiopharmaceutical preparation sintetized to improve diagnostic accuracy of bacterial infections in human tissues. It is mostly applied in diagnosis of bone and joint infections. Many papers have confirmed its sensitivity to infection, but newer papers argued its specificity. The aim of this study was to compare the results of visual analysis of scintigrams to semiquantitative calculations of accumulation indexes with the assumption that calculation of indexes would improve the specificity for bone and joint infections. Methods. We examined 40 patients, 25 with confirmed bone and joint bacterial infections and 15 patients with bone and joint diseases without bacterial infection. Scintigraphy was performed 5 minutes, 1, 4 and 24 hours after intravenous (iv) injection of 99mTc-ciprofloxacin. Scintigrams were analysed visually and by calculation and comparation of accumulation indexes values. Results. Visual sensitivity was 94%, but specificity only 47%. Index calculation achieved much higher specificity (100% after 1, 4 and 24 hours for cut off value of 1.50). All basic index values (5 min) in the patients with infections increased in 24 hours. In 8 patients without infection occurred a slight increase and in 7 patients decrease of basic index values. Conclusion. Calculation of accumulation index values is needed in the use of 99mTc-ciprofloxacin scintigraphy as it is the only way to improve specificity for bacterial bone infections. Visual interpretation of results is sensitive, but not specific due to accumulation of the drug in a high percent of non infected bone and joint lesions. [ABSTRACT FROM AUTHOR]

This research analyzed the degree of utilization of the agricultural biomass for energy purposes (combustion), in order to indicate the reasons that limit its use. The biomass potential was studied by means of the methodology of the biomass potential, whereas the factors suggesting a low degree of biomass utilization were identified by means of factor analysis. The research results reveal that there is an enormous potential of the unused agricultural biomass. This dissertation research significantly contributes to the establishment of a genuine mathematical model based on multiple linear regression. The solution obtained by this analysis, in both a mathematical and a scientific manner, conveys the primary reasons for an insufficient utilization of the biomass for energy purposes. Moreover, the paper suggests the measures to be applied for a more substantial use of this renewable source of energy and presents the expected benefits to be gained. [ABSTRACT FROM AUTHOR]

Background/Aim. Primary hyperparathyroidism (pHPT) is an endocrine disease with the third highest incidence of all endocrine disorders after diabetes mellitus and hyperthyroidism. pHPT is typically caused by a solitary parathyroid adenoma, less frequently by multiple parathyroid gland disease (MGD) and rarely by parathyroid carcinoma. Secondary hyperparatyroidism (sHPT) is a common complication in patients with chronic renal failure. The aim of this study was to estimate sensitivity of dual tracer 99mTctetrofosmin and 99mTc-pertechnetate subtraction scintigraphy in detection of abnormal parathyroid glands in patients with pHPT and sHPT confirmed by histopathology. Methods. In 46 patients, (77 abnormal parathyroid glands), 30 with pHPT and 16 with sHPT parathyroid scintigraphy was done preoperatively. All the patients had histopathological confirmation of diagnosis. Abnormal parathyroid glands weighted from 0.1 to 7 g. After iv injection dynamic scintigraphy during 25 minutes (one frame-one minute) using 555 MBq of 99mTc-tetrofosmin, and three hours latter using 111 MBq of 99mTc /pertechnetate was performed. 99mTc-tetrofosmin dynamic study was followed by static scintigraphy of the neck and chest 30 minutes, 1, 2 and 3 hours after iv injection. Results. An abnormal scintigraphic finding was found in 44 of 46 patients with sensitivity of 96%. In pHPT sensitivity was 93% (28 of 30 patients, and 28 of 30 glands). In sHPT scintigraphy was abnormal in all the patients (sensitivity 100%). In the patients with sHPT scintigraphy detected 30 of 47 abnormal parathyroid glands (sensitivity 64%). An overall sensitivity of scintigraphy per gland, for pHPT and sHPT in detecting 58 of 77 abnormal parathyroid glands was 75%. Conclusion. An abnormal scintigrafic result per patient was found in 44 patients (sensitivity 96%) and 58 of 77 abnormal parathyroid glands were detected (sensitivity 75%). A high sensitivity of dual tracer subtraction 99mTc-tetrofosmin/99mTc-pertechnetate parathyroid scintigraphy in detecting abnormal parathyroid glands in primary and secondary hyperparathyroidism was achieved. [ABSTRACT FROM AUTHOR]