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Biomedical subjects

P Heidenreich

Publications and source records attributed to P Heidenreich.

At least 19 recordsLinked to original sources
PubMed1995

Three-dimensional transabdominal ultrasound identification of aortic plaque.

Tree-dimensional (3-D) reconstruction of acquired tomographic images in adults has recently been described. With an adaptation of this technique, we performed 3-D reconstruction of transabdominal images of the abdominal aorta to test the hypotheses that 3-D reconstruction of the abdominal aorta is feasible and that 3-D images have incremental value over 2-D in the detection of atheromatous plaque. Twenty-one patients undergoing contrast aortography (Aogram) for clinical indications (1 abdominal aorta (AA) aneurysm, 5 peripheral vascular disease, 1 renal artery stenosis, 14 renal donors) were studied using a 5-MHz annular array probe fitted to a mechanical registration device. In 13 of 21 patients, adequate 2-D ultrasound slices were acquired around a 180 degrees rotation and stored as a volumetric data set using a dedicated computer and 3-D images were reconstructed off-line. Three-dimensional and planar images were blindly compared with Aograms using the following scale: grade 1, normal; grade 2, increased echodensity of the intimal surface; grade 3, local intimal thickening and/or luminal irregularity; and grade 4, protruding mass. Analogous 3-D images were produced in all 13 patients with branching vessels visible in 3 of 13. In 10 patients, the Aogram was interpreted as normal. Compared with Aogram, blindly interpreted 3-D images were compared and correctly identified normal AA in 8 of 10 and atherosclerotic plaque (grade 3 or 4) in 2 of 3. Discordant results were present in 2 of 10 normal aortas and 1 of 3 disease aortas. When 2-D (planar) images were compared with Aograms, 8 of 10 identified normal AA and 3 of 3 aortas with grade 3 or 4 plaque. Thus, in 2 patients, 3-D and planar images suggested atherosclerotic changes not seen by Aogram. Transabdominal 3-D imaging of the abdominal aorta is a feasible technique. Early data suggest that 3-D imaging may distinguish normal from moderate to severe disease, but currently has no demonstrable incremental value over conventional 2-D images. These early results in a small number of patients suggest that this promising technique warrants further evaluation.

Adult↗
PubMed1994

Quantification of mitral regurgitation by velocity-encoded cine nuclear magnetic resonance imaging.

OBJECTIVES: The feasibility of velocity-encoded cine nuclear magnetic resonance (NMR) imaging to measure regurgitant volume and regurgitant fraction in patients with mitral regurgitation was evaluated. BACKGROUND: Velocity-encoded cine NMR imaging has been reported to provide accurate measurement of the volume of blood flow in the ascending aorta and through the mitral annulus. Therefore, we hypothesized that the difference between mitral inflow and aortic systolic flow provides the regurgitant volume in the setting of mitral regurgitation. METHODS: Using velocity-encoded cine NMR imaging at a magnet field strength of 1.5 T and color Doppler echocardiography, 19 patients with isolated mitral regurgitation and 10 normal subjects were studied. Velocity-encoded cine NMR images were acquired in the short-axis plane of the ascending aorta and from the short-axis plane of the left ventricle at the level of the mitral annulus. Two independent observers measured the ascending aortic flow volume and left ventricular inflow volume to calculate the regurgitant volume as the difference between left ventricular inflow volume and aortic flow volume, and the regurgitant fraction was calculated. Using accepted criteria of color flow Doppler imaging and spectral analysis, the severity of mitral regurgitation was qualitatively graded as mild, moderate or severe and compared with regurgitant volume and regurgitant fraction, as determined by velocity-encoded cine NMR imaging. RESULTS: In normal subjects the regurgitant volume was -6 +/- 345 ml/min (mean +/- SD). In patients with mild, moderate and severe mitral regurgitation, the regurgitant volume was 156 +/- 203, 1,384 +/- 437 and 4,763 +/- 2,449 ml/min, respectively. In normal subjects the regurgitant fraction was 0.7 +/- 6.1%. In patients with mild, moderate and severe mitral regurgitation, the regurgitant fraction was 3.1 +/- 3.4%, 24.5 +/- 8.9% and 48.6 +/- 7.6%, respectively. The regurgitant fraction correlated well with the echocardiographic severity of mitral regurgitation (r = 0.87). Interobserver reproducibilities for regurgitant volume and regurgitant fraction were excellent (r = 0.99, SEE = 238 ml; r = 0.98, SEE = 4.1%, respectively). CONCLUSIONS: These findings suggest that velocity-encoded NMR imaging can be used to estimate regurgitant volume and regurgitant fraction in patients with mitral regurgitation and can discriminate patients with moderate or severe mitral regurgitation from normal subjects and patients with mild regurgitation. It may be useful for monitoring the effect of therapy intended to reduce the severity of mitral regurgitation.

Adult↗
PubMed1990

[Interstitial radiotherapy with 125I seeds in non-operable and non-radioiodine retaining local recurrences of differentiated and undifferentiated thyroid cancers].

The use of interstitial radiation therapy in the treatment of local recurrence of anaplastic and other carcinomas of the thyroid is discussed on the basis of four cases. 125I seeds were used except in 1 case. All tumours showed no uptake of radioiodine and could not be completely removed by surgery. In three patients local control of the tumour was achieved (longest follow-up 41 months); one patient died 2 months after therapy due to local recurrence.

Aged↗
PubMed1990

The orthopan tomoscintigram--a new application of emission computed tomography for facial bone scanning.

The exact regional correlation of findings of facial bone scans, planar or SPECT, to dental orthopan X-ray films (OPT) is difficult because of the very different projection techniques. To improve correlative imaging in this regard a projection algorithm was developed that uses SPECT data of the skull for reconstructing an orthopan tomoscintigraphic projection. Fourteen conventional SPECT slices of the upper and lower jaws were obtained during bone scanning. All mandibular slices were superimposed resulting in a horseshoe shaped structure, while was marked by an ROI which was divided into segments. All 14 SPECT slices were then masked by this segmental ROI, thereby marking the teeth-carrying bone in all slices. The information from this horseshoe like ROI is then transformed into lines. Line by line arrangement results in an orthopan projection, the orthopan tomoscintigram. This new display allows 1:1 true scale superimposition with the X-ray OPT and markedly facilitates correlative imaging.

Facial Bones↗
PubMed1990

Reconstruction of Fourier coefficients: a fast method to get polar amplitude and phase images of gated SPECT.

Gated SPECT (GASPECT) during radionuclide ventriculography (RNV) is a time-consuming procedure requiring extended hard- and software. Furthermore, the procedure suffers from poor count statistics. Our method tries to overcome these difficulties by exploiting the count summation effect of Fourier analysis. The sine and cosine coefficients of the first harmonic are extracted from the gated views and reconstructed. This, in fact, results in an improvement of the count statistics by a factor of four combined with a tremendous reduction of disc space requirements. Using short-axis slices, bull's-eye plots of the amplitude and phase of the left ventricle are calculated. Cardiac functions and localization and extent of any malfunction are documented three-dimensionally without superposition.

Data Interpretation, Statistical↗
PubMed1989

Quantitation of renal blood flow by contrast ultrasonography: preliminary results.

Contrast ultrasonography, employing tracers behaving like red blood cells, is a promising technique to study regional blood flow distribution. Aim of this note is to quantitate renal blood flow in the dog using contrast ultrasonography. Mathematical formulae derived from the classical dye-dilution theory are applied. Ten different renal blood flow levels (ranging from 16 to 125 ml/min) were obtained by means of mechanical (stenosis and reperfusion) and pharmacological interventions (iv infusion of adrenaline, noradrenaline and fenoldopam). Renal blood flow was measured by electromagnetic flow-meter and contemporary calculated by contrast ultrasonography. The correlation coefficient between measured and calculated flow was 0.92 (p less than 0.01). Contrast ultrasonography is a technique capable of measuring renal blood flow at a wide range of different flow levels.

Albumins↗
PubMed1987

[After care of differentiated thyroid gland carcinoma with special reference to serum thyroglobulin level].

The histories of 358 patients with carcinomas of the thyroid have been evaluated. Differentiated carcinomas of the thyroid (84.6%) were treated by means of thyroidectomy, ablative radio-iodine therapy (tissue dose 1000 Gray), TSH-suppressive thyroid hormone medication and, in special cases, external radiation. Even differentiated carcinomas showed a high recurrence rate. Metastases occurred particularly in the lungs, the skeleton and locally; low iodine uptake, particularly in distant metastases from papillary carcinomas, often made it impossible to reach a diagnosis by using radio-iodine. Some pulmonary metastases could only be demonstrated radiologically and some skeletal metastases could be shown radiologically or scintigraphically. A modified follow-up program for differentiated carcinomas is suggested, based on the highly sensitive and specific thyroglobulin determination under TSH suppression (sensitivity 97.9%, specificity 93.6%).

Carcinoma↗
PubMed1984

[Value of bone scintigraphy in secondary (intestinal) hyperparathyroidism].

We report on 4 patients with secondary hyperparathyroidism of intestinal origin presenting a characteristical pattern of distribution, namely focal accumulations of 99mTc-methylene diphosphonate on locations typical of Looser's zones. In accordance with other authors we demonstrate the higher sensitivity of skeletal scintigraphy as compared to radiography which is well known from other disorders of bone. We also refer to the problems of differential diagnosis arising when multiple foci are visible on bone scan.

Aged↗
PubMed1983

[Simplified methods for the measurement of renal clearance. Comparison of the results of Cr51-EDTA slope clearance, iodohippurate clearance and endogenous creatinine clearance].

Endogenous creatinine clearance proved to be unreliable in comparison to the 51Cr-EDTA-slope clearance with compartment analysis (examination time 4 hours). Tauxe's method of estimation of GFR can be recommended because of nearly perfect correlation with the 51Cr-EDTA-slope clearance (r = 0.959, n = 169, p less than 0.001). Estimation of ERPF according to Tauxe showed a moderate good correlation (r = 0.843, n = 140, p less than 0.001) with Oberhausen's method of clearance calculation (shoulder detector technique).

Chromium Radioisotopes↗
PubMed1981

Determination of total and individual kidney function in children by means of 123-I-hippuran whole body clearance and scintillation camera.

In 153 children suffering from various renal or urological disease a total of 179 individual and regional renal clearance studies were performed using 123-I-hippuran and a scintillation camera. The clinical diagnoses and questions before and the therapeutic consequences after clearance determinations are analyzed. The dynamic information fo sequential scintigraphy combined with renal clearance determination allow a quantitative estimation of the individual and regional kidney function. The method is considerably helpful in cases of unilateral small kidneys, obstructive uropathies, duplication of the urinary tract, and segmental renal disease.

Adolescent↗
PubMed1979

[The oblique projection in lung perfusion scintigraphy (author's transl)].

In perfusion lung imaging by scintillation camera routine use of posterior oblique views is recommended in addition to anterior and posterior views. Avoiding overlap activity ("shine through") from the contralateral lung they improve the detection rate as well as the characterisation and localisation of perfusion defects especially in the lower lobes. Artifacts due to increased absorption in the scapular region or to compression by mediastinal structures should be recognized.

Humans↗
PubMed1979

[Radio-nuclide phlebography: methods, indications and clinical value (author's transl)].

Radionuclide venography (RNV) is an easily performed, rapid and non-invasive diagnostic examination for the detection of deep-vein thrombosis. Provided the procedure is followed out in a standardized order, the results are highly reliable and accurate, especially in the iliac and femoral veins. Therefore, because of this advantage and the possibility of simultaneous lung perfusion scanning and the lack of serious complications this method fills a gap between contrast phlebography and fibrinogen test. 122 limbs of 69 patients were investigated by RNS. 65% showed pathologic results. In 48% thrombotic venous occlusions could be demonstrated. Pulmonary embolic perfusion defects were found in 46% of patients presenting deep vein thrombosis but only in 15% of patients without pathologic findings in RNV. In correlation with contrast phlebography in 11 patients there was no discrepancy neither in recognition nor in localization of the thrombotic occlusion. The essential findings in RNV and the resulting diagnostic conclusions are demonstrated.

Humans↗
PubMed1979

[Reliability and limitations of total and divided renal clearances as determined with a partially shielded whole-body counter (author's transl)].

Error and reproducibility of the total and divided renal clearance determination was investigated, using a partially shielded whole-body counter. The error of the total renal clearance determination using ortho-131I-hippuran (OIH) depends primarily on the downslope of the whole-body curve, i.e. on renal function. The error is as low as +/- 6% for clearance values of more than 100 ml/min and increases slowly with clearance values decreasing about 35 ml/min. The error of clearance values below 25 ml/min is higher than 50%. The error of the divided renal clearance using OIH is the same as the error of the total renal clearance. The reproducibility of the total OIH-clearance in single clearance periods was found to be +/- 6% and in repeated determinations +/- 12% (r = 0.97). The reproducibility of the divided renal OIH-clearance with scintillation probes showed an average deviation from the mean of +/- 10% (r = 0.87). The substitution of the scintillation probes by a scintillation camera and the use of regions of interest should diminish this error considerably. The results were compared with literature data on standard PAH- and inulin clearances.

Humans↗