Unilateral temporary functional stasis in the upper urinary tract caused by “a filled bladder” on Tc-99m DTPA diuresis renography: A teaching case

A 2-year-old girl with recurrent urinary tract infection having slight left pelvicaliceal dilatation on her renal ultrasound underwent a Tc-99m DTPA diuresis renography. During the excretion phase, a prominent and persisting left pelvicaliceal stasis was noticed even after the diuretic injection. However, it disappeared simultaneously with an uncontrolled micturition. This patient is presented to show the effect of filled bladder on the physiological drainage of urine. Since urine flow in the urinary system is more complicated than simple drainage, a thorough understanding of the physiological basis for diuresis renography and the pitfalls of the technique is required for its appropriate use in the management of patients suspected of urinary tract obstruction.     

Does the accuracy of single reading with CAD (computer-aided detection) compare with that of double reading?: A review of the literature

AIM: To examine current evidence to determine whether the accuracy of single reading with computed-aided detection (CAD) compares with that of double reading. METHODS: We performed a literature review to identify studies where both protocols had been investigated and compared. We identified eight studies that compared single reading with CAD against double reading, of which six reported on comparisons of both sensitivity and specificity. RESULTS: Of the six studies identified, three showed no differences in either sensitivity or specificity. One showed single reading with CAD had a higher sensitivity at the same specificity, another that single reading with CAD had a higher specificity at the same sensitivity. However, one study, in a real-life setting, showed that single reading with CAD had a higher sensitivity but a lower specificity. CONCLUSION: As the majority of the studies were not in a real-life setting, used test sets, lacked sufficient training in the use of CAD and simulated double reading (using a protocol of recall if one suggests), current evidence is therefore limited as to the accuracy, in terms of sensitivity and specificity, of single reading with CAD in comparison with the most common practice in the UK of double reading using a protocol of consensus or arbitration.     

Sensitive GC-MS method for the determination of specific-activity of 16α[18F]fluoro-estra- 1,3,5(10)-triene-3,17β-diol

A rapid and precise method for the measurement of the mass of 16α[¹⁸F]fluoro-estra-1,3,5(10)-triene-3,17β-diol by GC—MS is reported. The advantages of this technique over others more widely used are discussed.     

Quantitative angioscopy: A novel method of measurement of luminal dimensions during angioscopy with the use of a “lightwire”

Purpose To determine the accuracy and reproducibility of luminal dimension measurements of a newly developed method of quantitative angioscopy.Methods A method was developed for quantitation of luminal dimensions during angioscopy, as variation in magnification with lens-object distance and ambiguity associated with identification of corresponding points about the circumference of a given discrete cross-section render subjective estimates unreliable. A transverse ring of fiberoptically transmitted light was emitted from a guidewire or its housing at a known distance from the distal end of an angioscope and discrete cross-sections of interest were observed as the ring of light was reflected from the luminal surface. Caliper measurement of the diameter of the light ring image (< 50 mW at 488/515 nm), obtained on angioscopic video recordings of cylindrical phantom vessels of known dimensions, was performed by three observers on five occasions.Results The mean absolute difference between measured and known luminal diameter (n = 405 observations) was 65 m±35 m and the mean coefficient of variation was 4.2%, and the mean difference between measured and known areas (n = 195 observations) was 0.4 mm², with a mean coefficient of variation of 6.5%.Conclusion By use of this new lightwire method, luminal dimensions can now be measuredin vitro with a high degree of accuracy and reproducibility during angioscopy.Presented in part at the 41st Annual Scientific Session of the American College of Cardiology, Anaheim, California, March 1993.     

A novel electrochemical technique for the production of clinical grade 99mTc using (n, γ)99Mo

IntroductionIn order to meet the growing demand for ^99mTc and to reduce the reliance on fission-produced ⁹⁹Mo, an electrochemical pathway for accessing ^99mTc through the (n, γ)⁹⁹Mo was explored as a back-up measure and to supplement ^99mTc supply for radiopharmaceuticals application.Methods^99mTc from an equilibrium mixture of ⁹⁹Mo/^99mTc was selectively deposited on a platinum cathode in an electrochemical cell by applying optimal voltage and stripped back again into the 0.9% saline solution. The radiochemical and radionuclidic purity of the product were determined using standard techniques. ^99mTc thus obtained was used for labeling standard ligands such as dimercaptosuccinic acid (DMSA) and ethylene dicysteine (EC), to ascertain the usability.ResultsSelective deposition of ^99mTc on the platinum electrode was achieved at a potential of 5 V over a period of 1 h in NaOH electrobath. The overall yield of ^99mTc was >90%, with >99.99% radionuclidic purity and >99% radiochemical purity. The performance of the generator remained consistent over a period of 10 days. The compatibility of the product in the preparation of ^99mTc-labeled formulations such as ^99mTc-DMSA and ^99mTc-EC was found to be satisfactory in terms of high labeling yields (>98%).ConclusionA novel and attractive method has been developed to obtain highly concentrated ^99mTc, without using fission-produced ⁹⁹Mo.     

A new method in criminology: Use of ELISA to detect AFP on different materials with monoclonal anti-α-fetoprotein

Summary A new method has been introduced to distinguish normal adult serum stains from fetal or newborn serum and amniotic fluid stains with ELISA in cases of criminal abortion and infanticide. The method is based on the sensitive detection of -fetoprotein (AFP) by a two-site enzyme immunoassay (EIA) following its elution with high efficiency from different materials (e.g., cotton, paper, synthetic fabric, or glass) by phosphate-buffered 0.5 M NaCl solution     

Functional evaluation of myocardial viability by99mTc tetrofosmin gated SPECT —A quantitative comparison with18F fluorodeoxyglucose positron emission CT (18F FDG PET)—

To validate functional analysis of gated SPECT in detecting myocardial viability, seventeen patients (male 15, female 2, mean age 58) with angiographically proven chronic ischemic heart disease (RCA 6, LAD 10, LCX 1) and eight normal volunteers (all male) were studied. All patients underwent 18F FDG PET and 99mTc tetrofosmin (TF) gated SPECT within a week. After being displayed in a polar map, myocardial perfusion was regionally determined by the mean count in 9 segments at end diastole (ED) and end systole (ES) in gated SPECT. Systolic function was determined by the count increase ratio from ED to ES (WTI: ES - ED/ED). Glucose metabolism was assessed by 18F FDG PET in the segments correspondent to those defined for SPECT. TF %uptake of < 60% was defined as hypoperfusion, and FDG %uptake of < 50% was defined as reduced glucose metabolism. RESULTS: The myocardial segments were classified into 3 categories: "normal" perfusion (n = 85), "mismatch" (reduced perfusion with reserved FDG uptake, n = 25) and "matched" reduced perfusion and metabolic reduction (n = 26). Mean WTI in "mismatch" segment was 0.38 +/- 0.21, and was significantly greater than that in "matched reduced" segments, 0.15 +/- 0.20 (p < 0.001). It was also greater than that in "normal" segments, 0.27 +/- 0.16. Regression analysis showed that association between WTI and FDG %uptake was significant (r = 0.57, p < 0.0005) for the ischemic segments ("mismatch" + "matched", n = 51), but the association was weak for the entire segments although it was statistically significant (r = 0.26, p = 0.02, n = 136). CONCLUSION: For the segments determined as infarct by perfusion image, systolic functional analysis by gated SPECT is helpful in differentiation of a viable myocardial region or artifact from a scar. Nevertheless, further clinical and technical assessment is required for ECG gating to eliminate overestimation of viability and to warrant clinical use.     

A modification of the “total peak area” (TPA) method for gamma ray spectra

A modification of background counting calculations were made in order to increase the precision for the peak area calculation by the use of the TPA method. It was proposed to replace the number of counts on the left and right limit of the peak by other numbers obtained as a result of manifold parabolic interpolation according to Bessel. A ratio of variance of modified and unmodified TPA methods was calculated for various ratios of peak area to background and for various FWHM's. For small values of the peak area to background ratio, the variance ratio is about 0.5.     

Electrochemiluminescence and voltammetry of tris(2,2′-bipyridine)ruthenium (II) with amphetamine-type stimulants as coreactants: an application to the discrimination of methamphetamine

Purpose

We have tried to establish an electrochemical detection method for screening of the stimulants in the forensic samples using electrochemiluminescence (ECL) and voltammetric techniques.

Methods

Amphetamine-type stimulants (ATSs), such as methamphetamine (MA), amphetamine (AM), dimethylamphetamine (DMA), and methoxyphenamine (MP) have been studied as coreactants in the [Ru(bpy)₃]²⁺ (bpy = 2,2′-bipyridine) ECL system.

Results

There were two specific ECL peaks located at + 1.1 and + 1.4 V for MP, whereas there was only one ECL peak at + 1.1 V for MA and DMA, and no ECL response for AM. Different reaction mechanisms were proposed to understand the generation of ECL by the [Ru(bpy)₃]²⁺/ATS system. Because the voltammetric responses of these ATSs at a glassy carbon electrode were also different, it was possible to detect MA without a separation process based on the characteristic ECL and cyclic voltammetric signals. By a combination of ECL and voltammetric measurements, a simple and rapid screening method for MA could be proposed, and was applied in the determination of MA in human urine samples with sufficient sensitivity.

Conclusions

The present electrochemical approach seems to provide a new way for primary screening of MA in forensic application.

     

Weight of evidence of Y-STR matches computed with the discrete Laplace method: Impact of adding a suspect’s profile to a reference database

The discrete Laplace method is recommended by multiple parties (including the International Society for Forensic Genetics, ISFG) to estimate the weight of evidence in criminal cases when a suspect’s Y-STR profile matches the crime scene Y-STR profile. Unfortunately, modelling the distribution of Y-STR profiles in the population reference database is time-consuming and requires expert knowledge. When the suspect’s Y-STR profile is added to the database, as would be the protocol in many cases, the parameters of the discrete Laplace model must be re-estimated. We found that the likelihood ratios with and without adding the suspect’s Y-STR profile were almost identical with 1,000 or more Y-STR profiles in the database for Y-STR profiles with 8, 12, and 17 loci. Thus, likelihood ratio calculations can be performed in seconds if an established discrete Laplace model based on at least 1,000 Y-STR profiles is used. A match in a population reference database with 17 Y-STR loci from at least 1,000 male individuals results in a likelihood ratio above 10,000 in approximately 94% of the cases, and above 100,000 in approximately 82% of the cases. We offer free software accessible without restrictions to estimate a discrete Laplace model using a Y-STR reference database and subsequently to calculate likelihood ratios.     

99mTc-EDDA/HYNIC-octreotate scintigraphy, an efficient method for the detection and staging of carcinoid tumours: results of 3 years’ experience

Purpose At all stages of the disease, serious difficulties are encountered in the imaging diagnosis of carcinoids. Somatostatin receptor scintigraphy (SRS) holds great promise for detecting primary tumours and metastases. ^99mTc-EDDA/HYNIC-octreotate should significantly improve the diagnosis of carcinoids in comparison with ¹¹¹In-Octreoscan owing to the better affinity for SSR2 and the higher count rate. The aim of this study was to assess the diagnostic efficiency of ^99mTc-EDDA/HYNIC-octreotate scintigraphy in the detection and staging of carcinoid tumours.Methods The study population comprised 75 patients (age 48.5±15.5 years): 46 with histological confirmation of carcinoid and 29 with suspected disease. ^99mTc-EDDA/HYNIC-octreotate (740 MBq) SRS and CT were performed in all patients. Fifteen patients were examined with ¹¹¹In-Octreoscan. Results High-quality ^99mTc-EDDA/HYNIC-octreotate images were obtained in all cases, with maximum tumour tracer accumulation 4 h p.i. The mean target/non-target ratios for whole body (WB) and SPECT scans were, respectively, as follows: primary lesions: 4.5 and 10.2; metastases: liver, 3.1 and 12.3; abdominal focal lesions, 2.7 and 5.8; lung, 2.7 and 8.3; mediastinum, 3.4 and 7.6; bones, 6.8 and 19.0. ^99mTc-EDDA/HYNIC-octreotate WB scans revealed more metastases than ¹¹¹In-Octreoscan, with better individual separation. ^99mTc-EDDA/HYNIC-octreotate SRS revealed new metastatic lesions in seven patients with confirmed carcinoid, and in four with dissemination the primary focus was found. Five patients qualified for radioguided surgery and 11 were referred to ⁹⁰Y-DOTA-TATE therapy. The sensitivity of SRS in comparison with CT was higher for primary lesions and liver and abdominal lymph node metastases. In the subgroup of patients with suspected neuroendocrine tumours, two duodenal carcinoids, one thymic carcinoid and one ileal carcinoid were found.Conclusion ^99mTc-EDDA/HYNIC-octreotate, with high imaging quality, is an excellent alternative to ¹¹¹In-Octreoscan for staging of carcinoids, and it seems to be the method of choice for detection of the primary focus in patients with metastases from an unknown primary tumour.     

Radiolabelling of monoclonal antibodies: Optimization of conjugation of DTPA to F(ab′) 2-fragments and a novel measurement of the degree of conjugation using Eu(III)-labelling

F(ab) ₂ fragments (at concentrations of 5–30 mg/ml) derived from monoclonal antibodies raised against human prostate specific acid phosphatase were derivatized with a bicyclic anhydride of diethylenetriaminepentaacetic acid (cDTPAA) in the molar ratios of cDTPAA/F(ab) ₂ of 1:1, 5:1, 10:1 or 50:1. The most optimal product, aimed at radioimaging of prostatic cancer was obtained when the antibody fragment concentration was at least 10 mg/ml and the molar ratio of cDTPAA to F(ab) ₂ was 5:1 cDTPAA was added dissolved in dimethylsulfoxide (DMSO). Under these conditions, 1.8–2.2 DTPA molecules/F(ab) ₂ molecule were bound, giving a coupling efficiency of 37%–44%, and the labelling efficiency with ¹¹¹In (3 mCi/1 mg protein) was 95%±3% (n=7). The antibody fragment completely retained its immunoreactivity measured by radioimmunoassay and showed no aggregation when studied using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE).For evaluation of the degree of conjugation of DTPA to the antibody fragment, a novel technique was developed relying on the use of EuCl₃, and the measurement of europium fluorescence employing time resolved fluorometry. Results by EuCl₃ labelling were identical to those obtained by the conventional ¹¹¹InCl₃ labelling method.