Biomedical subjects

O Carlsen

Publications and source records attributed to O Carlsen.

At least 37 records · Page 2Linked to original sources

PubMed1988

Absorbed radiation dose in adults from iodine-131 and iodine-123 orthoiodohippurate and technetium-99m DTPA renography.

A mathematic model for evaluation of absorbed dose in radionuclide renography has been developed and programmed for automatic calculation in the computer. Input data to the model are readily available from the results of the renography and, hence, the method described is suitable for individual dose determinations in adults. Apart from the situation with very considerable outflow obstructions [131I]OIH single probe renography involves a 15-20 times smaller dose to radiation sensitive organs than [123I]OIH gamma camera renography. Further, the latter examination results in a 2-10 times smaller dose than [99mTc]DTPA gamma camera renography under normal outflow conditions. Absorbed renal dose is large, approximately 70 mGy, in the three renographies in the borderline case with total outflow obstructions. For comparison, i.v. pyelography, which is the x-ray examination often used instead of radionuclide renography, involves an absorbed dose to ovaries 10-1000 times larger than in radionuclide renography.

Adult↗

PubMed1987

Evaluation of end-diastolic left ventricular volume in equilibrium gated radionuclide cardiography.

The image of the left ventricle in the end-diastole during an equilibrium gated radionuclide cardiography (EGRC) was used for evaluation of the left ventricular end-diastolic volume (EDV). The method consists of a summation of the small volumes represented by each pixel in the activity image stored in the computer. The method was adapted to a normal material of 61 women 40-80 years. EDV was 69 +/- 17 ml/m2 (means +/- 1 SEE) and did not correlate with age. The relative experimental accuracy of the single determination of EDV was 7%-16% depending on the size of EDV. The method was verified in a control group of 25 subjects without valve malfunctions of the left ventricle according to echocardiography. The results from an abnormal material of 38 subjects with verified or suspected valve malfunctions of the left ventricle demonstrated the application of EGRC and the preceding first-pass radionuclide cardiography (FPRC) for determination of left ventricular regurgitation. Intra-observer variability of EDV was unbiased with a standard error of estimate of 12% for normal EDV and 5% for enlarged EDV.

Adult↗

PubMed1987

Evaluation of regional cerebral circulation based on absolute mean transit times in radionuclide cerebral angiography.

In radionuclide cerebral angiography (RCA) the analysis of the activity-time curves recorded over the hemispheres following an intravenous bolus injection of a radioactive indicator permits the evaluation of absolute cerebral mean transit times (MTTcb). The inverse of MTTcb is an index of cerebral blood flow. The bolus parts of the cerebral activity curves were fitted with gamma-variate functions. The duration of the injection bolus and its subsequent dispersion through the cardiopulmonary circulation were corrected for using the activity curve over the aortic arch. In a control material of 52 subjects MTTcb was uncorrelated with age and equal to 3.2 +/- 0.67 s (means +/- 1 SEE) for the 37 subjects younger than 60. For the fifteen subjects older than 60, mean MTTcb showed a steep increase with age. The results were in close agreement with those obtained by other researchers using either correction of cerebral curves based on a physical flow model or direct injections into the internal carotid artery. Comparison of RCA with x-ray carotid angiography in 12 subjects was satisfactory. Repeated RCA examinations in nine subjects a few days apart yielded a reproducibility of 0.7 s for MTTcb. The RCA is non-invasive, rapid, easy to perform and without risk for the patient. The RCA is recommended for quantitative evaluation of major alterations in cerebral perfusion.

Adult↗

PubMed1987

Renal fraction of cardiac output cleared of radioactive indicator in 99Tcm-DTPA gamma camera renography.

The renal images recorded during 1 to 2 1/2 min postinjection in 99Tcm-DTPA gamma camera renography were used for determination of the total cleared renal fraction (TCRF) of cardiac output with respect to the radioactive indicator. The left and right cleared renal fractions of cardiac output were determined directly, i.e., assessment of single-kidney uptake function within a few minutes postinjection was also possible. TCRF was proportional to the glomerular filtration rate (GFR) determined by the 51Cr-EDTA plasma clearance in a group of 23 subjects with GFR in the interval 15 to 130 ml/min/1.73 m2. The slope of the regression line of TCRF against GFR was in agreement with the theoretical estimate for it. GFR could be predicted from TCRF with a standard error of estimate from 4 to 15 ml/min/1.73 m2 for values of GFR in the above interval. Intra-observer variability of TCRF was unbiased and varied between 4% (normal GFR) and 9% (decreased GFR). TCRF is proposed to represent an alternative to renal clearance for evaluation of renal uptake function.

Cardiac Output↗

PubMed1987

Renal fraction of cardiac output cleared of radioactive indicator in 123iodine-hippuran gamma camera renography.

The renal images recorded during 1-2 min post-injection in 123I-hippuran gamma camera renography were used for determination of the total cleared renal fraction (TCRF) of cardiac output with respect to the radioactive indicator. In a study of sixty-seven normal children over two years old TCRF was 0.178 +/- 0.026 (mean +/- 1 SEE). This was in agreement with the estimation of TCRF from values of renal fraction of cardiac output and renal extraction ratio of hippuran in the literature. The left and right cleared renal fractions of cardiac output were determined directly, i.e., assessment of single kidney uptake function within a few minutes post-injection was also possible. TCRF was closely related to the glomerular filtration rate (GFR) in a group of twenty-two subjects with GFR in the interval 20-130 ml/min/1.73 m2. Intraobserver variability of TCRF was unbiased and equal to 4%. TCRF is proposed to represent an alternative to renal clearance for evaluation of renal uptake function.

Adolescent↗

PubMed1986

Indirect radionuclide renocystography for determination of vesico-ureteral reflux in children.

Indirect radionuclide renocystography (IRRCG) is a method for the detection of vesico-ureteral reflux by analysis of the activity-time curves over the kidneys and bladder during voiding of urine about 30 min after intravenous administration of a radioactive indicator. This paper presents a new method for detection of reflux by a statistical test, the magnitude of the reflux is evaluated by the reflux volume per 1.73 m2 body surface area. Residual urine volume and urine voiding efficiency are also calculated. In a retrospective study of 154 children examined for renal and urological diseases consisting mainly of urinary tract infections, vesico-ureteral reflux was found by IRRCG in 16% of the kidneys (23% of the children). Reflux volumes were below 10 ml/1.73 m2 in 90% of the children with reflux. The mode value of the reflux volume was 2 ml/1.73 m2. For a subgroup of 97 children, the results were compared with micturating cysto-urethrography (MCU). This showed that a negative IRRCG in conjunction with the renal mean transit time of the radioactive indicator determined by gamma camera renography could be used as a screening test for vesico-ureteral reflux when MCU was considered a true reference method. Hence, about 75% of the invasive and high radiation dose MCU can be replaced by the non-invasive and low radiation dose IRRCG. The discrepancies between the two methods and the reasons for them are discussed.

Child↗

PubMed1986

Quantitative evaluation of functional renal volume in normal children based on [123I]hippuran gamma camera renography.

Images of the kidneys at 1-2 min after injection in [123I]hippuran gamma camera renography were used to find the functional renal volume. The method consists of a summation of the small volumes represented by each pixel in the activity images of the kidneys stored in the computer. In principle, the functional renal volume can therefore be calculated for any renal shape but the paper deals predominantly with normal kidneys. The method described is a by-product of gamma camera renography and is considered valuable for monitoring kidney growth in the normal child. It is believed that the method is also useful for determination of normal/pathological renal volume in patients with renal diseases who have normal/quasi-normal renal shapes.

Adolescent↗

PubMed1986

Quantitative evaluation of iodine-123 hippuran gamma camera renography in normal children.

In a retrospective study of 39 normal children submitted to [123I]hippuran gamma camera renography, a quantitative evaluation of the recorded data showed that: (a) the rate constant for renal plasma clearance of [123I]hippuran was -0.166 +/- 0.043 min-1 corresponding to a hippuran plasma clearance of 518 +/- 142 ml/min per 1.73 m2; (b) the fractional renal clearance of [123I]hippuran was 0.51 +/- 0.03 and 0.49 +/- 0.03 for the left and the right kidney, respectively; and (c) the mean values for the mean transit times of [123I]hippuran through the whole kidney, the renal parenchyma, and the renal pelvis, respectively, were 4.2, 1.9, and 2.5 min. Five kidneys (in four patients) showed prolonged renal mean transit times of [123I]hippuran. Follow-up renographies were performed in three of the four children and gave normal results. Patients with renal mean transit times above the present 5% significance limit of 8.2 min should not necessarily be considered having an abnormal renal function.

Adolescent↗

PubMed1985