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Biomedical subjects

E V Dubovsky

Publications and source records attributed to E V Dubovsky.

At least 55 records · Page 3Linked to original sources
PubMed1988

Comparison of technetium-99m MAG3 with iodine-131 hippuran by a simultaneous dual channel technique.

Technetium-99m MAG3, a technetium-labeled analog of hippuran, was compared with [131I] hippuran using a simultaneous dual isotope study in 20 patients. The plasma clearance for MAG3 was lower than that of hippuran, but its plasma concentration was higher, resulting in similar rates of excretion and similar renal time-activity curves. Apart from better statistics with the technetium-labeled agent, there were no clinically significant differences in this group of patients.

Adult↗
PubMed1988

Abnormal captopril renogram with a technetium-99m-labeled hippuran analog.

A case of renovascular hypertension is presented in which the [131I]hippuran renogram was initially normal, but became strikingly abnormal upon administration of the angiotensin converting enzyme (ACE) inhibitor captopril. The patient presented with fibromuscular dysplasia of the renal arteries, which was shown by hippuran renography to be functionally significant on the right side. She became normotensive after angioplasty of the right renal artery. Hypertension recurred a year later, at which time the renogram was normal without captopril, but showed functionally significant left renal artery stenosis with captopril challenge. Both the conventional agent, [131I]hippuran, and an experimental new 99mTc-labeled hippuran analog, [99mTc]MAG3, were used. Angiography confirmed progression of disease on the left side, which was successfully treated by angioplasty. Functionally significant unilateral renal artery stenosis was thus demonstrated first on the right side and then, 1 yr later, on the left side, using hippuran and [99mTc]MAG3. Anatomic progression of disease was documented by angiography.

Adult↗
PubMed1988

Quantitation of renal function with technetium-99m MAG3.

The technetium-labeled hippuran analog [99mTc]MAG3 was compared with [131I]hippuran in 50 patients using a quantitative renal function protocol that includes: (a) estimation of effective renal plasma flow by a single-injection, single-sample plasma clearance method, (b) determination of relative function of right and left kidney from the initial count rate over each kidney, and (c) comparison of recovered urine activity with plasma disappearance. This protocol is suitable for routine clinical use, and, in fact, has been used heavily at our clinic for a number of years. By slight modification of the formulas, the results obtained with [99mTc]MAG3 agreed well with those using [131I]hippuran. We conclude that [99mTc]MAG3 can be substituted for [131I]hippuran in the quantitative protocol, with the better image quality and lower radiation dose (in abnormals) of a technetium-labeled agent.

Humans↗
PubMed1988

Estimation of extracellular fluid volume from plasma clearance on technetium-99m DTPA by a single-injection, two-sample method.

A simple method is presented for estimating extracellular fluid volume from the plasma clearance of [99mTc])DTPA or [169Yb]DTPA. Two plasma samples are required, at 1 and 3 hr, following a single intravenous injection. (The same plasma samples can be used for measurement of glomerular filtration rate.) Using the complete plasma clearance curve as a reference (eight samples at 10 to 240 min), the error of the two-sample method in 40 patients was 1.5 I for [99mTc]DTPA, 2.1 I for [169Yb]DTPA (residual standard deviation).

Extracellular Space↗
PubMed1987

Mineral content of bone: measurement by energy subtraction digital chest radiography.

Several methods are presently available for measuring the mineral content of bone. Those in widespread use include dual-photon absorptiometry and quantitative CT. The feasibility of using dual-energy digital chest radiography for determination of the mineral content of posterior ribs on digital chest images was studied by using a prototype unit. The results showed a significant difference in the mineral density of the posterior ribs of control subjects and those of patients who had osteoporosis (251.1 +/- 36 mg Ca2+/cm2 of rib vs 158.8 +/- 48 mg Ca2+/cm2, p less than or equal to .01) and a close correlation with values obtained by dual-photon absorptiometry of the lumbar spine (r = .77). The results suggest that this technique can provide an accurate assessment of the presence or absence of osteoporosis.

Adult↗
PubMed1987

Predictive value of bedside effective renal plasma flow for renal recovery in severe acute renal failure.

Single injection, single blood sample, effective renal plasma flow (ERPF) estimated by 131I-orthoiodohippurate can be performed accurately and conveniently without urine collection at the bedside. The purpose of this study was to determine if ERPF early in the course of severe acute renal failure (ARF) predicts recovery of renal function in hemodynamically stable patients. Over 18 months, ERPF was determined in 33 such patients with ARF in whom an etiologic diagnosis could be established. Eight patients died within 2 months of onset and while on dialysis, did not have an autopsy, and were not considered further. Six patients (Group A) either remained on dialysis after at least 6 months follow-up or had irreversible renal disease at autopsy. In Group B (19 patients, 13 of whom were dialyzed), serum creatinine returned to less than 2.0 mg/dL (n = 16) or was decreasing without dialysis. Peak serum creatinine (Group A 11.2 +/- 1.4; Group B 10.1 +/- 1.3 mg/dL) did not differ between groups. Oliguria was present in 75% of Group A patients and in 25% of Group B patients. Initial ERPFs differed (p less than 0.001) between Group A (90 +/- 11) and Group B (204 +/- 20 mL/min). Initial ERPF was greater than 125 mL/min in 15 Group B patients but in no Group A patients; the false-positive rate was 21% and the false-negative rate was 0%.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1985

Measurement of glomerular filtration rate using 99mTc-DTPA and the gamma camera: a comparison of methods.

A variety of methods have been proposed to estimate the glomerular filtration rate (GFR) from the renal uptake of technetium Tc 99m-DTPA using a gamma camera. To compare alternative methods, we calculated the GFR in several different ways from measurements in 33 patients and compared the results with an independent GFR measurement based on eight-point plasma clearance of ytterbium Yb 169-DTPA. The best agreement was obtained using an algorithm that has not been described previously, in which correction was made for overlap of the kidneys by the liver and spleen. The correlation coefficient was 0.958, and the residual standard deviation was 12.1 ml/min. This method required a single 20-min blood sample as well as the camera data. The best method not requiring a blood sample was significantly less accurate, with a correlation coefficient of 0.837 and a residual standard deviation of 23.1 ml/min. The accuracy of these methods was comparable to that reported for creatinine clearance, the most commonly used estimate of the GFR in current clinical practice.

Glomerular Filtration Rate↗
PubMed1985

Measurement of glomerular filtration rate: single injection plasma clearance method without urine collection.

Glomerular filtration rate (GFR) can be calculated from the plasma clearance of any of several radiopharmaceuticals that are excreted by glomerular filtration. Simplified methods have been proposed that require only one or two plasma samples in lieu of a more complete clearance curve. We examined the error introduced by this simplification. Forty patients were studied using a dual-isotope technique employing [99mTc]DTPA and [169Yb]DTPA, obtaining eight plasma samples for each clearance curve at intervals from 10 to 240 min after injection. Data were fit to several empirical or semiempirical formulae and also to a two-compartment computer model that permitted GFR estimation from only one or two data points. The computer model gave good fit, but so did several simpler methods. The error that results from replacing the complete clearance curve by a single 3-hr sample was about 8 ml/min (residual s.d.). By using two samples (at 1 and 3 hr), the error could be reduced to 4 ml/min. Recommended one- and two-sample methods are presented.

Glomerular Filtration Rate↗
PubMed1984

Comparison of measurement of effective renal plasma flow by single plasma sample and plasma disappearance slope/volume methods.

Numerous simplified methods for the estimation of ERPF have described, including the so-called slope/intercept (SI) methods, based on the analysis of the slope of certain segments of the 131I-OIH plasma disappearance curve and its y-axis intercept, and the single sample (SS) clearance method, based on theoretical volumes of OIH distribution at some fixed time after injection. Using ERPFs estimated from compartment analysis of the entire 60-min plasma disappearance curve, we have compared the errors of data calculated from use of eight SI methods made at various times along the disappearance curve with that from the optimum SS curve. The errors obtained from the SS method were approximately 50% less than those obtained from the SI methods. The errors of the SI methods are greater at both ends of the 60-min plasma curve than when samples are drawn near the mid-time. The SS method appears to be the method of choice for the estimation of ERPF using single injection techniques.

Adolescent↗
PubMed1984

Renal function after acute and chronic spinal cord injury.

Computer-assisted renal scintigraphy was performed on 160 acute and 240 chronic spinal cord injury patients, and 287 noninjured controls. Concurrently, measurements of global and individual kidney effective renal plasma flow, time of maximum activity in each kidney, ratio of maximum counts to the counts at 27 minutes after injection over each kidney and number of counts in each kidney at 1 to 2 minutes after injection were made. The time of peak activity over the kidney and differential function at 1 to 2 minutes after injection were not affected significantly by age, sex or spinal cord status. Global and individual effective renal plasma flows were significantly affected by all of these factors. Both plasma flow measures generally were higher for male than for female patients. Effective renal plasma flow decreased steadily after early adulthood and, except for the youngest and oldest patients, values were lower for spinal cord injury patients than for normal controls. The ratio of peak to 27-minute counts was affected significantly by age and spinal cord injury but not by sex. In patients without obvious pathological conditions followup scintigrams 1 to 3 years after injury showed no significant changes owing to interval since injury on any parameter studied. Lower limits of basal scintigraphic parameters are given for evaluation of renal status in neurologically intact or spinal cord injury persons.

Adolescent↗
PubMed1983

Quality control of Tc-99m DTPA for measurement of glomerular filtration: concise communication.

When technetium-99m DTPA is used to measure glomerular filtration rate (GFR), the accuracy depends on the supplier of the radiopharmaceutical. The error in GFR is due to protein binding, as we have shown by direct measurement. In 19 patients, GFR measured with Tc-DTPA and corrected for protein binding agreed with that measured simultaneously using Yb-169 DTPA (correlation coefficient 0.991). Without correction, Tc-DTPA gave falsely low values in patients having good renal function, in whom unbound activity cleared rapidly while bound activity remained in the circulation. When Tc-DTPA is used to measure GFR, the in vivo protein binding should be measured and used to correct the data.

Animals↗
PubMed1982

New formulas for the calculation of effective renal plasma flow.

Estimation of effective renal plasma flow (ERPF) can be made easily, inexpensively, and accurately by means of a single plasma concentration determination, sampled 44 min after injection of 131I-orthoiodohippurate (OIH). We originally established predictive regression equations based on a series of patients with a wide variety of diseases and a few normal potential kidney donors. The equation best fitting that data was parabolic in form and assumed a negative slope when high ERPF rates were encountered. This problem has been corrected by deriving new equations (parabolic and exponential) based on an expanded series which includes a large number of subjects with high ERPF. Errors of estimation are lower than those of the more classic para-aminohippuric acid (PAH) clearances and well within the exigencies of clinical practice.

Adolescent↗
PubMed1982

Prediction of urinary excretion of 131I-orthoiodohippurate.

A new formula is presented for the prediction of urinary excretion at approximately 35 min after injection of 131I-orthoiodohippurate, derived from a large series of normal kidney donors, before and after unilateral nephrectomy, and a few patients with diseases in which there was no evidence of urinary tract obstruction. The best formula was: Expected percent dose excretion at 35 min = 79.3[1-e--(0.004798 X ERPF)] with a standard error of estimate (Sy.x) of 5.2% dose. This value has been particularly useful in clinical practice in the calculation of an excretion index (actual/expected percent dose excretion) which separates various post-transplantation entities and various nephrourologic processes.

Humans↗
PubMed1982

Quantitation of renal function with glomerular and tubular agents.

Quantitative methods to measure the glomerular and tubular function of the kidneys with radionuclides have been available for many years. They have not been widely used because the techniques and the calculations exceeded the scope of routine nuclear medicine practice. Validation of simplified methods and the introduction of computer technology have made measurement of the effective renal plasma flow (ERPF) and the glomerular filtration rate (GFR) simple enough so that they can be performed reproducibly in most nuclear medicine departments. The estimation of ERPF with radioiodinated OIH and GFR with 99mTcDTPA can be achieved in many ways, all of which yield clinically useful results. How to get the best results using the simplest methods is still unclear. The required accuracy depends on the intended clinical use. Our preference at the present time is to use a single or double plasma sample to calculate global ERPF or GFR, and to use the 1-2 min OIH or 1-3 min Tc-DTPA uptake to calculate relative function of the two kidneys (split function ERPF or GFR). The choice of method will be influenced by local factors, such as the nature of the patient population, the case volume, and the resources available. A desirable goal for future studies is to document carefully the capabilities and limitations of each alternative method, so that the choice can be rational.

Computers↗