Biomedical subjects

O Carlsen

Publications and source records attributed to O Carlsen.

At least 19 recordsLinked to original sources

PubMed1992

Root canals in one-rooted maxillary second molars.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.

Classification↗

PubMed1991

Radix paramolaris in permanent mandibular molars: identification and morphology.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth which have been extracted in Denmark. The collection presently includes 203 permanent mandibular molars with a root complex containing a facially-located supernumerary root. This macrostructure is named radix paramolaris (RP). By analyzing the large number of specimens available it was possible to establish uniform and precise criteria for the identification of RP on M1 inf, M2 inf, and M3 inf. The analyses included both separate and non-separate RP. The representation of the RP variants according to tooth type was mapped. Furthermore, the following clinically relevant variables with respect to RP were registered: degree of separation, divergence, apical bend, apical gracility, and fusion. Because of the nature of the material, the study was mostly qualitative and non-metric. The results are aimed primarily at clinical dentists, dental morphologists, and dental anthropologists.

Denmark↗

PubMed1991

Morphometric analysis of occlusal groove-fossa-system in mandibular third molar.

Based on serially cut 200-microns-thick sections from 21 human mandibular third molars, a quantitative characterization was made of the morphology in the mesial and distal interlobal groove. Two parameters were used: depth of interlobal groove and structure angle. The interlobal groove depth varied between 0.13 and 0.55, taken in relation to the maximum crown height. The structure angle varied between 2 degrees and 170 degrees. If the structure angle was less than or equal to 25 degrees, the interlobal groove was classified as a fissure; if the angle was greater than 25 degrees, the interlobal groove was classified as a groove. Only in 18% of the sections did the interlobal groove manifest itself as a fissure. The study demonstrates that it was possible unambiguously to describe the two-dimensional profile of interlobal grooves by groove depth and structure angle.

Classification↗

PubMed1990

A new method for determination of the rate constant for clearance of radioactive indicators in gamma camera hepatography. Clinical examples with 99mTc-diethyl-IDA and 99mTc-diethyl-iodo-IDA.

Application of Stewart-Hamilton's formula to the activity-time curve recorded over a left ventricular region of interest following an intravenous bolus injection of a radioactive indicator in gamma camera hepatography has resulted in a new method for determination of the clearance rate constant of the indicator (i.e. the ratio of the clearance to the plasma volume). In a group of 19 normal subjects the clearance rate constant was 0.116 +/- 0.036 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-IDA (SOLCO HIDA) and 0.184 +/- 0.037 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-iodo-IDA (SOLCO IODIDA) in 15 normal subjects. The clearance rate constant is assumed to represent mainly hepatic clearance of the radioactive indicator and to a much smaller extent renal clearance. The literature shows diverging results as to the clearance of 99mTc-diethyl-IDA and the reasons for this are discussed. The correlations between the clearance rate constant of 99mTc-diethyl-IDA and a number of laboratory variables with relation to liver function were moderate to non-existent in a group of 16 subjects with abnormal values of at least one of these variables. The rate constant for clearance as described in the paper represents a non-invasive method for rapid evaluation of the uptake capacity of the liver and, in particular, with regard to the polygonal cells of the liver parenchyma when IDA derivatives are employed. The clinical usefulness of the clearance rate constant is probably superior to the group of routine laboratory variables which also describe other functions than liver uptake.

Adult↗

PubMed1990

A method for determination of normal or abnormal blood volume in patients subjected to radionuclide cardiography.

The blood volume can be measured after labelling of red blood cells with technetium-99m. In addition, the blood volume and its standard error of estimate can be calculated from the subject's sex, height and deviation from desired weight. By comparing the measured blood volume with the estimated normal blood volume and using a statistical test, it can be decided whether a measured blood volume is normal or not. This method was applied to a group of 36 patients with heart diseases. Four of the patients had abnormal blood volumes. In the remaining 32 patients the measured blood volumes were equally distributed around the estimated mean normal values. The method described for determination of normal/abnormal blood volumes can be considered a by-product of routine radionuclide cardiography.

Adult↗

PubMed1990

Root complex and root canal system: a correlation analysis using one-rooted mandibular second molars.

The principal aim of this investigation was to verify an expected, probable correlation between certain variables, which are initially represented in the macrostructure of the root complex corresponding to the cemento-dentin junction, and certain variables that subsequently manifest themselves in the root canal system. A material consisting of 76 one-rooted, permanent mandibular second molars (M2 inf) was used. The specimens were cut at the mid-root level and all observations were made on the coronal root segment using a stereomicroscope. Relevant variables of the root complex were observed. The total macromorphologic variation of the root complex could be subdivided and classified in well-defined, distinguishable types. In accordance with the single root complex type an expected, logically deduced configuration of the root canal system was established. The relevant variables of the canal system were then recorded. Finally, the root complex morphology, as well as the expected and actually observed canal configuration, were compared type by type. In 76.3% of the teeth a good concordance could be shown between the expected and the actual canal configuration, whereas in 23.7% of the specimens there was a divergence. In 42.1% of the investigated teeth, 1 centrally localized main canal with varying cross section images, among them a C-shaped image, was found. In 30.3%, 2 main canals were found, which were often localized mesially and distally. In 23.7%, 3 main canals were observed: 1 mesiofacial, 1 mesiolingual and 1 distal. In the remaining 3.9%, 1 non-independent supernumerary canal was seen in a distolingual position.

Classification↗

PubMed1990

Radix entomolaris: identification and morphology.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth, extracted in Denmark. At present, the collection includes 398 permanent mandibular molars with a root complex containing a lingually-located supernumerary root. This macrostructure is called radix entomolaris (RE). By analyzing the large number of available specimens it was possible to establish uniform and precise criteria for the identification of RE on M1 inf, M2 inf, and M3 inf. The analyses included separate as well as non-separate RE. The representation of the RE variants according to tooth types was mapped. Furthermore, the following relevant clinical variables with respect to RE were registered: degree of separation, divergence, apical bend, apical gracility, and fusion. Because of the nature of the material, the investigation was mostly qualitative and non-metric. The results should be of interest to clinical dentists, dental morphologists, and dental anthropologists.

Classification↗

PubMed1989

A new, simple and precise method for the determination of right ventricule forward ejection fraction in first-pass radionuclide cardiography.

A new method is presented for the determination of right ventricular ejection fraction (RVEF) in first-pass radionuclide cardiography. The method is simple to apply and it provides RVEF values with an experimental standard deviation of 3.4% over the whole range of right ventricular ejection fractions. The method determines RVEF from analysis of time-activity curves from regions of interest (ROIs) over representative portions of the right atrium and the pulmonary artery (RVEFRAPA). Hence, the problem of demarcation of the right ventricle from adjacent structures is avoided. RVEFRAPA was 0.658 +/- 0.067 (mean +/- 1 S.D.) in a normal group of 36 adult women. This value was not significantly different from the RVEF of 0.641 +/- 0.072 (mean +/- 1 S.D.) determined by separate areas over the right ventricle in the end-diastole and end-systole (RVEFRVSA). In a repeatability study comprising 25 subjects covering a wide range of RVEF values, the standard deviation of RVEFRAPA was 4.4 times smaller than that of RVEFRVSA. The left ventricular ejection fraction (LVEF) determined in the equilibrium gated radionuclide cardiography following the first-pass study was 0.692 +/- 0.065 (mean +/- 1 S.D.) for the normal group. Hence, LVEF is slightly higher than RVEF in normals.

Adult↗

PubMed1988

Evaluation of forward stroke volume in first-pass radionuclide cardiography.

First-pass radionuclide cardiography and Zierler's area-over-height formula have been applied for determination of stroke volume. The method has three new features: (a) the region of interest comprises the entire cardiopulmonary circulation; (b) a prediction of (normal) blood volume based on deviation from desired weight; and (c) a correction of stroke volume in case of incomplete bolus injection. The method was verified in a pathological situation by an independent geometric method in equilibrium gated radionuclide cardiography. The variation of stroke volume was investigated in a normal group of 61 women, 40-80 years old. The result was in excellent agreement with values for normal variation of stroke volume in the literature.

Adult↗

PubMed1988

Glomerular filtration rate in adults estimated from 123iodine-hippuran and 99mtechnetium-diethylenetriaminepenta-acetic acid gamma camera renography.

In a retrospective study a close relationship was found between the rate constant for renal clearance of the radioactive indicator (lambda pk) and the glomerular filtration rate (GFR) measured by 51Cr-EDTA plasma clearance. The material comprised eighteen adult subjects submitted to 123I-hippuran gamma camera renography (IHGR) and twenty-two adult subjects to 99mTc-DTPA gamma camera renography (TDGR). The rate constant was calculated from a bi-exponential decomposition of the activity-time curve recorded within a small region of interest over the left ventricle. The total cleared renal fraction (TCRF) of the cardiac output with respect to the radioactive indicator has previously been shown to be closely related to GFR. A pooled estimate of GFR (GFRp) was calculated from the stochastically independent estimates of GFR based on lambda pk and TCRF. The comparison of GFRp with measured GFR was satisfactory and yielded substantially smaller standard deviations (SD) of GFRp than estimates based on lambda pk and TCRF separately. The standard deviations of GFRp were about 7 and 12 ml/min/1.73 m2 in IHGR for GFR equal to 50 and 100 ml/min/1.73 m2, respectively. The corresponding SD in TDGR were about 7 and 11 ml/min/1.73 m2. These standard deviations are sufficiently small for many clinical purposes and the method requires no blood samples or urine collections.

Adult↗

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↗