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At least 685 records · Page 38Linked to original sources
PubMed1994

Measurement of the extravascular concentration of renal agents following intravenous bolus injection.

The extravascular concentration (Ce) of some renal agents, in relation to the simultaneous plasma concentration (Ci), was calculated as a function of time after intravenous injection. Four agents were studied: 51Cr-ethylenediamine tetraacetate (EDTA) (n = 11), 125I-hippuran (n = 11), 99Tcm-dimercaptosuccinic acid (DMSA) (n = 11) and 99Tcm-mercaptoacetyl triglycine MAG3 (n = 20). Plasma clearance curves were constructed from data acquired from multiple blood sampling and fitted with two exponentials. The extravascular content of tracer at any time is equal to the injected dose remaining after subtraction of the intravascular tracer content and the total amount of tracer cleared from plasma. Mean Ce/Ci at equilibrium (defined as the time, > 120 min, when Ce/Ci reaches its maximum value) was 1.087 (S.D. 0.019) for EDTA, 1.73 (0.48) for hippuran, 0.37 (0.2) for DMSA and 0.64 (0.3) for MAG3. Corresponding clearance (F) values were 68 (13), 415 (149), 15.6 (9.5) and 214 (52) ml min-1 1.73 m-2. Ce/Ci correlated with F and was also related to protein binding in plasma. Extrapolation of the regressions of Ce/Ci on F to F = 0 at several time points after injection gives a curve of Ce/Ci (at F = 0) against time which represents the rate of equilibration of the tracer throughout its distribution volume that would be seen with zero clearance, and therefore allows measurement of the in vivo protein binding of the tracer in plasma. Protein binding was zero for EDTA, 30% for hippuran, 86% for DMSA and 88% for MAG3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Kidney volume estimation using 99Tcm-DMSA RSPECT: evaluation by phantom study.

Renal parenchymal volume is important for clinical interpretation. The phantom study was carried out to validate the volume calculation. The volume of kidney phantom was determined using reoriented single photon emission computed tomography (RSPECT). The phantom volume range was 20-300 ml. There are two major factors in the determination of volume which are radioactivity concentration and organ/background ratio. Our results showed that the effect of radioactivity concentration on the volume in the kidney phantom is -3.3 to 7.5% whereas the effect of organ/background ration was only 2.2%. Our relative volume deviation, therefore, from the real volume was 1.43%. We concluded that it is feasible to use kidney volume in clinical work.

Evaluation Studies as Topic↗
PubMed1994

Comparison of planar and SPECT 99Tcm-dimercaptosuccinic acid scintigraphy in calculating differential kidney function.

An extensive study to compare planar and single photon emission computed tomographic (SPECT) 99Tcm-dimercaptosuccinic acid (DMSA) determination of differential kidney function (DKF) has been carried out. The study has demonstrated that it is possible to use SPECT differential kidney function in place of that obtained using planar scintigraphy. The SPECT DKF value correlated with the planar DKF value. Gradient shaded three-dimensional surface images, reoriented transaxial, sagittal and coronal slices were produced during the same processing method.

Adolescent↗
PubMed1994

99Tcm-DMSA as a dynamic imaging agent for estimating renal blood flow. A comparison with 99Tcm-DTPA.

A technique for estimating fractional renal blood flow (RBF) from the early part of the 99Tcm-diethylenetriaminepentaacetate (DTPA) renogram has been described previously and its reproducibility validated in the pig model. The technique is assumed to be applicable to any recirculating gamma-emitting tracer compound. The aim of this study was to determine whether the same method could be applied to 99Tcm-dimercaptosuccinic acid (DMSA) which has been largely neglected as a dynamic imaging agent. Paired estimates of fractional RBF were obtained in Large White (n = 16) and Göttingen miniature pigs (n = 6) in three groups: group 1, paired 99Tcm-DTPA studies; group 2, paired 99Tcm-DMSA studies; group 3, alternate 99Tcm-DTPA and 99Tcm-DMSA studies. The results showed good agreement between paired results independent of whether 99Tcm-DTPA or 99Tcm-DMSA was used, supporting the assumption that the technique is applicable to any recirculating gamma-emitting tracer compound. The demonstration that fractional RBF can be reliably estimated from the DMSA renogram means that, if required, it may be combined in a single nuclear medicine procedure with conventional static DMSA renal imaging.

Animals↗
PubMed1995

Absolute 99Tcm-DMSA renal uptake in children: a study of 321 kidneys.

Absolute 99Tcm-dimercaptosuccinic acid (DMSA) uptake was measured in 160 children ranging in age from 3 months to 15 years. In total, 108 pairs of kidneys were normal and the mean uptake for the left and right kidneys was 24.0 and 23.4%, respectively. The mean summed uptake for the left and right kidneys was 47.3%. A method of calculation based on the geometric mean of the anterior and posterior views was used to allow for radiation attenuation. DMSA uptake did not vary significantly with the age of the child. The value of the method in the assessment of abnormal kidneys is presented. The effect of using a supine or prone position for the anterior view was also investigated.

Adolescent↗
PubMed1995

Absolute 99Tcm-DMSA renal uptake in children: optimum time to scan.

Absolute renal uptake was measured at 2, 4 and 6 h in 27 patients in order to determine a more convenient time for uptake compared with the 6-h measurement proposed by other authors. Measurements made at 2 and 4 h would need to be increased by 20 and 6%, respectively, to convert to the value at 6 h. Measurements at 4 h are a reasonable compromise to achieve a high-count/low-background image in a reasonable time and to obtain a good estimate of the predicted 6 h uptake at a single scanning session. The percent renal uptake at 6 h, U(6), can be derived from the percent uptake measured at t hours after injection, U(t), using the following formula: U(6) = U(t) x CF(t), where CF(t) = 1.0 + 0.03 (6 - t) for 4 < or = t < or = 6.

Adolescent↗
PubMed1995

Positive thyroid cancer scintigraphy using 99Tcm-tetrofosmin (Myoview): a preliminary report.

99Tcm-tetrofosmin imaging was performed in 23 thyroid cancer patients and compared with whole-body 131I scans, neck ultrasonography and plasma thyroglobulin levels. Of 22 patients with differentiated thyroid cancer, 8 showed identical images on 131I scan and tetrofosmin; 1 patient with medullary cancer had identical images with 99Tcm-DMSA and 99Tcm-tetrofosmin, the findings being confirmed by sonography. The potential usefulness of 99Tcm-tetrofosmin imaging in the follow-up of thyroid cancers is discussed.

Biomarkers, Tumor↗
PubMed1995

An evaluation of 99Tcm-DMSA SPET with three-dimensional reconstruction in 68 patients with varied renal pathology.

Sixty-eight patients (135 kidneys) with varied renal pathology were evaluated with 99Tcm-dimercaptosuccinic acid (DMSA) single photon emission tomography (SPET) to determine whether it is possible to detect more renal abnormalities and to reduce the number of false-positives due to anatomical variants when compared with planar imaging. The patients ranged in age from 1 to 78 years and their pathologies included urinary tract infection (n = 50), space occupying lesions (n = 5), calculi (n = 4), hypertension (n = 4) and others (n = 5). Planar scans were performed 3 h after the injection of 80 MBq of 99Tcm-DMSA and a 64 x 20 s acquisition over 360 degrees was used for SPET. High-resolution collimation was used for both. Slices were displayed as transaxial, coronal and sagittal and/or oblique sagittal in the plane of the kidney. Three-dimensional (3D) images were formed by volume rendering. Each kidney was divided into three regions and each region scored separately for the presence of an abnormality. Planar scans were reviewed alone and then in conjunction with SPET and 3D images. Planar imaging detected 95 abnormal regions compared with 103 using SPET. SPET reduced the number of equivocal regions in 8 (12%) patients. The diagnosis was altered by SPET in 17 (4%) regions in 14 (21%) patients. SPET and 3D 99Tcm-DMSA allow more abnormalities to be detected but also allow more specific definition of apparent abnormalities on planar imaging.

Adolescent↗
PubMed1996

A review of renal scarring in children.

It is now widely accepted that children with a proven urinary tract infection should undergo some form of diagnostic imaging to assess the presence of, or the potential to develop, renal scarring. The type of investigation which should be performed is controversial. Some centres still perform intravenous urography, others rely on ultrasound alone, while others believe that a 99Tc(m)-dimercaptosuccinic acid (99Tc(m)-DMSA) scan is essential. This review discusses the advantages and disadvantages of these techniques by drawing from the extensive literature currently available. The consensus view is that a DMSA scan is the most sensitive method of detecting renal scarring and of highlighting the kidney at risk of developing scarring. It is hoped that wider early use of DMSA scintigraphy will lead to a fall in the number of children who develop end-stage renal disease.

Adolescent↗
PubMed1996

Inter-observer agreement in the reporting of 99Tcm-DMSA renal studies.

The early identification of renal cortical scarring secondary to urinary reflux and/or renal infection is important in the management of patients with recurrent disease. Scintigraphic imaging of the renal cortex using 99Tcm-dimercaptosuccinic acid (DMSA) is often considered the standard method for the diagnosis of renal scars in both adults and children. Consistent reporting of 99Tcm-DMSA is nevertheless essential in ensuring that the clinician can act on the data reported. In this study, seven experienced observers were asked to report, independently, 99Tcm-DMSA data sets from 32 patients. The observers were asked to note the presence of a space occupying lesion or of a renal cortical scar(s) and to conclude if the kidney was normal or abnormal. There was marked variation in the number of renal cortical scars reported, the total number of scars seen and whether or not the kidney was normal or abnormal. After peer review of all data, consensus and referenced criteria were arrived at for a reanalysis of data. All scans were reread by the observers. There was some improvement in the concordant reporting of kidneys with renal scars (51 vs 61%) and whether or not the kidney was normal or abnormal (53 vs 63%). However, this was not statistically significant (at a level of P < 0.05). This study demonstrated significant inter-observer variation regarding the reporting of 99Tcm-DMSA studies. A consensus with agreed guidelines for data interpretation did not significantly affect this apparent lack of consistency of reporting.

Adolescent↗
PubMed1997

Incidence and clinical significance of linear defects ascribed to interrenuncular septa on 99Tcm-DMSA SPET.

99Tcm-dimercaptosuccinic acid (99Tcm-DMSA) planar and single photon emission tomographic images from 100 children were reviewed to analyse whether linear defects corresponding to anatomical characteristics of interrenuncular septum (IRS) could be seen. Thirty sites in 30 kidneys (20 right, 10 left) from 27 patients were determined as showing IRS. They were seen less frequently in patients less than 7 years of age. The prevalence of IRS in the patients with vesico-ureteric reflux (VUR) was not significantly different from that in the patients without VUR. The interrenuncular septum was never seen on planar images and was most clearly demonstrated on conventional coronal tomographic images. The linear defects ascribed to IRS on 99Tcm-DMSA scintigrams were of a similar incidence to that reported previously. However, IRS is still an unestablished structure, and there is no evidence that these linear defects actually correspond to the structure described as the interrenuncular septum.

Child↗
PubMed1997

Renal 99Tc(m)-DMSA SPET and planar imaging: are they really the same?

Previous studies have suggested that more defects are detected on SPET than on planar DMSA images. The aim of this study was to evaluate differences between planar and SPET imaging. Sixty-four kidneys from pyelonephritic patients were studied using both techniques. An automated algorithm for reorientation and centring of the SPET images was used to minimize inter-observer variability. Reduced uptake and contour defects showed different localization on planar and SPET imaging. Coincidence of defects on both types of image was low. We also noted a dependence on defect frequency content for detectability. Image contrast played a noticeable role in the detection of defects. Differences in contrast between SPET and planar images may be responsible for the variable success in the detection of defects. Contour defects are seen more frequently on tomographic slices, whereas reduced uptake defects are seen more frequently on planar images. A difference is also noted between the cortical and calyceal zones for differently contrasted lesions. SPET and planar DMSA images can potentially provide a different diagnosis of renal lesions.

Adult↗
PubMed1997

Renal imaging with 99Tc(m)-dextran.

Significant uptake and retention of 99Tc(m)-dextran (molecular weight: 81,000) in renal parenchyma was discovered during evaluation of its intravascular use. Renal SPET images confirmed this. This study was designed to evaluate 99Tc(m)-dextran as a renal cortex imaging agent. Stability of parenchymal retention was shown by insignificant outflow at 24 h and by frusemide intervention. Evaluation of the renal parameters of intravenous 99Tc(m)-dextran (n = 71 normal kidneys) and its comparison with 99Tc(m)-DTPA n = 10) and 99Tc(m)-DMSA(III) (n = 23) was undertaken. The early glomerular extraction phase of the renograms of 99Tc(m)-DTPA and 99Tc(m)-dextran appeared identical; parenchymal uptake of 99Tc(m)-dextran continued to increase and reached a near-plateau by 40-60 min. The mean cortex-to-background and cortex-to-liver ratios at 2 h with 99Tc(m)-dextran and 99Tc(m)-DMSA(III) were 14.9 and 9.2, and 16.0 and 8.9, respectively. The target-to-nontarget ratios were similar despite different absolute renal uptake values (12 vs 20% at 2 h) because of faster background clearance of 99Tc(m)-dextran. The mechanism of parenchymal retention of 99Tc(m)-dextran appears to be trapping at the endothelial-epithelial interphase of the glomerulus. Our initial experience suggests 99Tc(m)-dextran is a viable renal parenchyma imaging agent.

Adolescent↗
PubMed1998

UK audit of relative renal function measurement using DMSA scintigraphy.

A variety of software is used to determine quantitative parameters from radionuclide imaging procedures. Knowledge of the variability of parameter values found in different hospitals is an important aspect of clinical audit of these techniques. This study investigated the variation in relative renal function measurement from static DMSA scintigraphy in the UK. Ten studies representing a range of ages and relative function values were distributed in digital form to 100 hospitals with the assistance of the gamma camera computer suppliers and regional audit coordinators. The studies were analysed at each participating hospital and details of the different techniques and computer systems used were documented. The median value of relative percentage function was assessed for each of the studies. Methods varied in terms of the view used for analysis (54% geometric mean, 46% posterior), the type of background subtraction (single region 32%, separate regions 60%, none 8%) and the definition of the renal regions of interest (73% manual, 27% semi-automatic). Eighty-eight percent of results were within two percentage points of the study median and 98% within five percentage points. There were statistically significant differences observed in the results arising from the view used for the analysis and the background subtraction protocol. The results indicate that relative renal function assessment from static DMSA scintigraphy in the UK is essentially a reliable procedure, although improvements could be made by standardizing the technique used.

Adult↗
PubMed1992

Escherichia coli virulence factors and 99mTc-dimercaptosuccinic acid renal scan in children with febrile urinary tract infection.

Correlation of virulence factors of Escherichia coli with renal inflammation documented by 99mTc-dimercaptosuccinic acid renal scan was undertaken in 59 children with febrile urinary tract infections to identify more accurately the role of bacterial virulence factors in the development of pyelonephritis. P fimbriae were present in 63% of isolates from the positive scan group and 83% of those from the negative scan group (P = 0.126). Multivariate regression analysis showed no significant role for established E. coli virulence factors in the development of pyelonephritis. The pap genome was independently associated with negative scan (P less than 0.007) and with the absence of reflux (P = 0.031). E. coli pyelonephritogenic clone O16:K1:H6 was isolated from negative scan patients and did not produce hemolysin. We conclude that P fimbriae are important in the development of febrile urinary tract infection regardless of the level of infection. Virulent E. coli clones described in prior Scandinavian urinary tract infection studies were not common causes of pyelonephritis in our patient population.

Adolescent↗