[Clinical case of the month. Apropos a case of drowning].
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Adult↗
Biomedical subjects
M Moonen
Publications and source records attributed to M Moonen.
Determination of split renal function from gamma camera renography: a study of three methods.
Three different methods for calculation of the split kidney function from gamma camera renography with 99Tcm-DTPA are surveyed in this study, the integral, the slope and the uptake index methods. The reproducibility in calculating the relative renal function was very good with all three methods (coefficient of variation 2-4%). Single kidney glomerular filtration rate (GFR) was assessed by the three methods and 51Cr-EDTA clearance prior to nephrectomy, giving the accuracy of each method. The slope and uptake index methods showed high accuracy (0.9-2.0 ml min-1), while it is significantly reduced with the integral method (4.6 ml min-1), compared to the postoperative 51Cr-EDTA clearance. The uptake index method enables calculation of a ratio between the kidneys (alpha/UI)SR, which relates each kidney's intrarenal blood volume (alpha) to its renal function (UI). This ratio was compared in a group consisting of 38 patients with kidney tumours and in a control group of 32 patients. It was rather constant in the control group but significantly higher and within a wider range in the group with renal tumours. These discrepancies may indicate an abnormal intrarenal blood volume. Furthermore, the correlation between results assessed by the three calculation methods in the control group was good, while the correlation in the group with renal tumours deteriorated.
Adolescent↗
Gamma camera renography with 99Tcm-DTPA: the impact of variations in input plasma curve on estimated GFR.
In an attempt to improve the reliability in estimating glomerular filtration rate (GFR) from gamma camera renography without blood sampling, we have investigated the impact of plasma input region of interest (ROI) size and location and the effect of the time delay between the circulation peak in the renal curves and in the plasma curve. An uptake index (UI) was calculated using plasma ROIs of five different sizes (8-56 cm2) and compared with measured 51Cr-EDTA clearance. The spread of the estimated GFR was not affected by the variations in plasma ROI size but different relations were obtained between UI and GFR. The plasma ROI markedly affected the estimated GFR (a deviation of 3.5 cm from the maximal region led to an overestimation of the GFR of 36%). Furthermore, the most reliable GFR estimate (S.D. 10.5 ml min-1) was achieved by including the whole circulation peak in the calculation time interval of the time delay-adjusted renogram, except the first frame. The time delay adjustment also enabled the calculation of a factor alpha, which represents the ratio between the blood volume within the renal ROI and that within the plasma input ROI. An abnormal alpha/UI ratio would suggest an unreliable GFR estimation.
Adult↗
Reliability of ACE inhibitor-enhanced 99Tcm-DTPA gamma camera renography in the detection of renovascular hypertension.
Twenty consecutive patients with renovascular hypertension, proven by cure or improvement of hypertension at 1-year follow-up after percutaneous transluminal angioplasty or surgical repair, were studied before intervention by means of gamma camera renography with 99Tcm-diethylenetriaminepentaacetic acid (99Tcm-DTPA) at baseline and after angiotensin-converting enzyme (ACE) inhibition. Sixteen patients underwent bilateral renal vein catheterization for measurement of renal vein renin release and extraction ratios of para-amino-hippurate (PAH) and 51Cr-EDTA before and after acute ACE inhibition. With the limit for a significant change in relative side distribution of 5% or more after ACE inhibition on gamma camera renography 13 patients responded (Group 1), while seven patients (Group 2) had unchanged side distribution. Glomerular filtration rate (GFR), measured with 99Tcm-DTPA, in the affected kidney decreased in Group 1 from 26 +/- 16 ml min-1 to 11 +/- 12 ml min1 (P < 0.0005), while GFR was unchanged in the affected kidney in Group 2, 26 +/- 13 ml min-1 versus 29 +/- 13 ml min-1. Extraction ratios of PAH and 51Cr-EDTA for the affected kidney in Group 1 decreased from 80 +/- 18 to 73 +/- 21% (P < 0.05) and from 16 +/- 5 to 7 +/- 5% (P < 0.005), respectively, while in Group 2 the PAH extraction ratio was not significantly changed, 86 +/- 5 versus 81 +/- 14%, but the 51Cr-EDTA extraction ratio for the affected kidney also decreased from 16 +/- 3 to 8 +/- 4% (P < 0.005). All patients had lateralization of renal vein renin to the affected kidney.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Contraction and evacuation of the gallbladder studied simultaneously by ultrasonography and 99mTc-labeled diethyl-iminodiacetic acid scintigraphy.
Emptying of the gallbladder was studied by the simultaneous use of 99mTc-labeled diethyl-iminodiacetic acid [HIDA] scanning and real-time ultrasonography. In response to a liquid test meal the gallbladder volume was reduced for 80 min and then increased again, but the radionuclide evacuation continued and was more complete than could be explained by the reduction of gallbladder volume. In response to intravenous infusion of cholecystokinin, a maximal contraction of the gallbladder to 35% of the basal volume was obtained at 40 min, and 36% of the HIDA then remained in the gallbladder. In a separate series repeated intravenous injections of 99mTc-HIDA were given after the test meal, and the isotope was found to enter the gallbladder even when the gallbladder contracted. The results support the view that the gallbladder acts like a 'bellows' when contracting and that postprandial fluid secretion by the gallbladder mucosa may help to evacuate its contents.
Adult↗
Subtraction of extra-renal background in 99mTc-DTPA renography: comparison of various regions of interest.
Quantitative evaluation of renal function in 99mTc-DTPA isotope renography is hampered by high background activity. This study compares various background regions of interest (ROIs) to obtain the most accurate estimate of the extra-renal background, taking both total counts (integral value) and change by time (slope) into account. Gamma camera renography was performed in 21 patients with a single kidney. Time-activity histograms obtained from 8 different background ROIs were compared in the time interval corresponding to the uptake phase of the renogram with the histogram obtained from a ROI over the empty kidney area. A significant difference could be demonstrated between the slope values of the histograms of the right and left empty kidney ROIs, but not for the integral values. Backgrounds taken over the heart, liver, between the kidneys, and under the kidneys had significantly different characteristics than the one in the empty kidney area. Only background ROIs surrounding each kidney area gave integral and slope values with close resemblance to those recorded over the empty kidney area. The results emphasize the necessity for an individual background ROI for each kidney and the need to separate extra- and intra-renal background activities before subtraction.
Adult↗
Effects of extra-renal background subtraction and kidney depth correction in the measurement of GFR by gamma camera renography.
99Tcm-DTPA gamma camera renography was performed in 83 patients with a wide range of renal function. An uptake index (UI) proportional to the single kidney glomerular filtration rate (GFR) was calculated from the renograms according to two different algorithms, one based on a blood background taken from a region of interest (ROI) over the heart (method I), and the other a modification of that procedure including an extra-renal background subtraction (method II). The extra-renal background was defined by a ROI closely surrounding the kidney, making the separation between the extra-renal background and intra-renal blood background possible. Method II was further evaluated by comparing the results without and with correction for kidney depth (method III), the skin-kidney distance being measured by sonography. Calculated UI from the renograms was compared with measured 51Cr-EDTA plasma clearance as the reference method. Method I overestimated GFR at low kidney function. Addition of the extra-renal background subtraction (method II) eliminated that error and correction for kidney depth improved the accuracy (the standard error of the estimate was reduced from 18.2 min-1 to 12.3 min-1). It is concluded that the measurement of GFR by gamma camera renography is improved by these additional operations.
Adult↗
Predictive value of quantitative cisternography in normal pressure hydrocephalus.
Twenty-five patients with normal pressure hydrocephalus (NPH) and 16 patients with cerebral atrophy were investigated by quantitative cisternography using anterior images of the head 3, 6 and 24 h after a lumbar injection of 200 MBq 99mTc DTPA (diethylene-triamine-penta-acetic acid). The activity in the lateral ventricles, basal cisterns, hemispheric convexities and total intracranial region was measured. Ratios between these regions/quantities were calculated. Fifteen of the NPH patients improved while 10 were unchanged after ventriculo-peritoneal shunt surgery. The ratio between ventricular and total intracranial activity (V/T) correlated positively with the degree of improvement after shunt surgery. All NPH patients with a V/T ratio higher than 32% improved after the operation but a V/T ratio less than 32% did not exclude the possibility of improvement. With regard to quantitative measurements, the radionuclide cisternography procedure can be reduced to imaging at 24 h.
Aged↗
Influence of percutaneous renal stone extraction on renal function.
The total and separate renal function was studied in 10 patients by means of 51Cr-EDTA-clearance and gamma camera renography with 99mTc-DTPA before and 2 weeks to 5 months after percutaneous renal stone extraction. There was no major complication related to the operations. There was no significant change of function as measured as the glomerular filtration rate. The stone extraction procedure was well tolerated by the kidneys.
Chromium Radioisotopes↗