Biomedical subjects

G Leinsinger

Publications and source records attributed to G Leinsinger.

11 recordsLinked to original sources

PubMed1992

Immunoimaging of choroidal melanoma: assessment of its diagnostic accuracy and limitations in 101 cases.

Immunoscintigraphy (IS) was performed on 101 patients with space occupying intraocular lesions including choroidal melanomas (85), choroidal naevi (11), non-melanoma metastases (three), and other melanoma simulating lesions (two). Scintigraphic images with conventional and emission computer tomography techniques were obtained after the intravenous injection of 99mTc-labelled F(ab')2 fragments of monoclonal antibody (MoAb) 225.28S directed against the high molecular weight-melanoma associated antigen (HMW-MAA). Immunohistochemistry was performed on sections of four out of 10 melanoma-containing eyes to confirm MoAb binding. IS demonstrated positive scans in 66 out of 85 choroidal melanomas, offering a sensitivity of 78%. Sensitivity was dependent on the lesion size. True negative results were obtained in 15 out of 16 non-melanoma lesions (specificity 94%). False positive antibody accumulation was found in one patient with a post-traumatic subretinal haemorrhage. Immunohistochemistry demonstrated positive MoAb 225.28S binding in all melanoma sections. In summary IS offered substantial sensitivity and specificity in the differentiation of intraocular lesions, particularly choroidal melanomas, naevi, and metastases. In combination with other diagnostic procedures such as ultrasound echography and fluorescein angiography IS proved to be a valuable method in the diagnosis of choroidal melanoma.

Choroid↗

PubMed1992

Granulocytes and three-phase bone scintigraphy for differentiation of diabetic gangrene with and without osteomyelitis.

OBJECTIVE: In diabetic gangrene, concomitant osteopathy and soft-tissue infection often render laboratory and roentgenographic signs unreliable as indicators of osteomyelitis. In this situation, scintigraphic methods can be helpful. RESEARCH DESIGN AND METHODS: Relying on the long-term clinical course as the final indicator of presence or absence of osteomyelitis, we prospectively compared in 31 patients three-phase bone scintigraphy with either indium-labeled autologous granulocytes (n = 20) or 123I-labeled antibodies against granulocytes (n = 11). RESULTS: Three-phase bone scintigraphy and imaging with indium-labeled autologous granulocytes yielded sensitivities and specificities of 95 and 70% for bone scintigraphy and 77 and 100% for granulocyte scintigraphy, respectively. One patient with severe angiopathy and proved osteomyelitis had a negative bone scintigraphy but a positive scintigraphy with labeled antibodies against granulocytes. One patient with aseptic bone necrosis presented with a formally false positive result with both methods. CONCLUSIONS: In contrast to former retrospective studies, three-phase bone scintigraphy compares very well with granulocyte scintigraphy. The care of most patients can be managed with clinical data and this widely available scintigraphic method.

Bone and Bones↗

PubMed1990

Reduced cerebral blood flow in early stages of human immunodeficiency virus infection.

In order to determine if brain perfusion abnormalities, which are known in patients with acquiredimmunodeficiency syndrome dementia, occur in early stages of human immunodeficiency virus infection, technetium 99m hexamethyl-propyleneamine oxime-single-photon emission computed tomography studies were performed in 20 patients infected with human immunodeficiency virus who belonged to Walter Reed stages I through IV. None of these patients demonstrated signs of dementia or severe neurological dysfunction. Pathological patterns of hexamethyl-propyleneamine oxime uptake were seen in 14 patients, seven of whom had normal results during neurological examination. Only four patients had signs of cerebral atrophy on cranial computed tomographic scan. These data suggest that subtle changes in cerebral perfusion seem to arise early in the course of human immunodeficiency virus infection and may indicate human immunodeficiency virus encephalopathy before neurological symptoms or noticeable structural damage occurs.

Acquired Immunodeficiency Syndrome↗

PubMed1990

A simple test to assess cerebrovascular reserve capacity using transcranial Doppler sonography and acetazolamide.

The goal of this study was the development of a simple bedside test to assess cerebrovascular reserve capacity using transcranial Doppler sonography. We studied 33 normal persons at rest and after stimulation of cerebral blood flow with 1 g acetazolamide. Their mean +/- SD increase in blood flow velocity in 54 middle cerebral arteries 10 minutes after stimulation was 24.4 +/- 9.2 cm/sec. We tried to validate the increase in blood flow velocity as cerebrovascular reserve capacity in 21 patients with obstructive carotid artery disease and symptoms of cerebral ischemia. The patients were studied using transcranial Doppler sonography and xenon-133 dynamic single-photon emission computed tomography after acetazolamide stimulation. Their increases in blood flow velocity (delta FV) and increases in cerebral blood flow (delta CBF) correlated significantly in both hemispheres (asymptomatic: Y = 0.32X + 10.65, r = 0.45, p = 0.04; symptomatic: Y = 0.36X + 2.28, r = 0.59, p = 0.004). There was no significant difference between the slopes of the regression lines. Blood flow velocity and cerebral blood flow at rest were not correlated. The increase in blood flow velocity after acetazolamide stimulation offers a simple and reliable method for assessing cerebrovascular reserve capacity.

Acetazolamide↗

PubMed1989

Brain morphology and regional cerebral blood flow in anorexia nervosa.

Cranial computed tomography (CT) was performed in 12 patients with anorexia nervosa, revealing that the majority of the patients displayed ventricular dilatation and/or sulcal widening. In addition, regional cerebral blood flow (rCBF) was measured at admission and once again after weight gain, using xenon-133 dynamic single-photon emission tomography (dSPECT). The mean flow rates assessed at the first examination did not significantly differ from those assessed at the second examination and from those of a control group. There was a significant inverse relationship between the size of the cerebrospinal fluid spaces and the cerebral blood flow in the anorectics; a decrease in ventricular size after weight gain was associated with an increase in cerebral blood flow in this area. This finding, however, has to be interpreted with caution, as partial volume effects render the flow rates ambiguous in brain areas, which, in addition to neuronal tissue, also include ventricular and sulcal structures.

Adolescent↗

PubMed1989

[Brain structure and brain function in anorexia nervosa: a computerized tomography study].

Cranial computed tomography (CT) was performed in 12 patients with anorexia nervosa revealing that the majority of the patients displayed ventricular dilatation and/or sulcal widening. In six patients re-examined these structural brain alterations showed a strong trendency towards normalization after weight gain. With the intention of finding a functional correlate of the CT abnormalities, the regional cerebral blood flow (rCBF) was measured at admission and once again after weight gain and compared with the flow rates of a healthy control group. The mean flow rates assessed at the first examination did not significantly differ from those assessed at the second examination and from those of a control group. Thus, despite the CT findings of structural brain abnormalities, the measurement of the regional cerebral blood flow gave no hint of a reduced functioning of certain brain areas in anorexia nervosa.

Adolescent↗

PubMed1988

Immunoscintigraphy in intraocular malignant melanoma.

Immunoscintigraphy of malignant tumours has become an encouraging tool in nuclear medicine. Early diagnosis of small lesions is mandatory for successful cancer therapy. The scintigraphic detectability of small lesions (less than 1 cm in diameter) by immunoscintigraphy is shown in 39 patients suffering from ocular tumours (37 malignant choroidal melanoma, two benign choroidal naevi) using 99Tcm-labelled F(ab')2 fragments of the anti-melanoma monoclonal antibody 225.28S; this antibody recognizes the high molecular weight melanoma-associated antigen. No adverse effects were observed. In terms of true-positive results, single photon emission computed tomography (SPECT) proved to be superior to planar scans (73% versus 41% true-positive results).

Aged↗

PubMed1988

[133Xe-DSPECT: significance of the cerebrovascular reserve capacity for the diagnosis and therapy of chronic cerebral ischemia].

Using 133Xe-DSPECT, measurements of regional cerebral blood flow (rCBF) were performed before and after stimulation with 1 g of Diamox in 55 patients with symptomatic occlusion of the internal carotid artery (ICA) and 26 patients without evidence of brain disease (normals). In normals, a negative correlation (r = -0.74) of the Diamox-induced increase of hemispheric blood flow (reserve capacity) and rCBF at rest was observed. In 48 of the 55 patients (87%) with ICA-occlusion a reduced reserve capacity was found. The extent of reduction, however, did not correlate with the findings of transmission CT, because 15 of 21 patients (71%) with normal CT-scans presented a moderate to severe reduction of reserve capacity. In contrast, reserve capacity corresponded to the extent of arterial collateralisation as documented by cerebral panangiography. In 31 patients EC/IC-bypass surgery was performed. In follow-up studies reserve capacity increased, especially in patients who had a severe reduction preoperatively. Therefore, the combined measurement of rCBF at rest and of reserve capacity is a sensitive, non-invasive method for the diagnosis of (even bilateral) cerebrovascular disease and can be helpful to identify patients with hemodynamic ischemia, who may benefit from EC/IC-bypass surgery.

Adult↗

PubMed1987

[Radioimmunoscintigraphy with monoclonal antibodies].

Radioimmunoscintigraphy is presented as a new imaging modality in nuclear medicine, using specific antigen-antibody interactions. Monoclonal antibodies to tumor-associated antigens facilitate the characterization of molecular differences between tumors and normal cells. Labelled with gamma-emitting radioisotopes like I-131, I-123, In-111, and Tc99M, these antibodies can be used for in-vivo imaging. Radioimmunoscintigraphy does not compete with morphological modalities like CT and ultrasound, but provides additional information based on its functional principle. Hidden lesions may be detected. Target-to-background ratios, however, are still rather low hampering scintigraphic imaging. The use of Single Photon Emissions Computed Tomography (SPECT) in addition to planar scintigraphy resolves background activities thus providing better visualization and localization of tumors, and increasing sensitivity. The high cost of these time-consuming studies is still a limiting factor to its wider use. Its preliminary indication is founded on the suspicion of tumor progression, based on clinical findings and/or increasing serum tumor markers (CEA, CA 19-9, CA 12-5). This paper provides an overview over possible applications of radioimmunoscintigraphy. Its clinical use is demonstrated by studies of malignant melanoma, colorectal cancer and ovarian cancer.

Antibodies, Monoclonal↗

PubMed1987

[133Xe-DSPECT: normal values of resting cerebral blood flow and reserve capacity].

Using the 133Xe-DSPECT technique, quantitative measurements of regional cerebral blood flow (rCBF) were performed before and after provocation with acetazolamide (Diamox) i.v. in 32 patients without evidence of brain disease (normals). In 6 cases, additional studies were carried out to establish the time of maximal rCBF increase which was found to be approximately 15 min p.i. 1 g of Diamox increases the rCBF from 58 +/- 8 at rest to 73 +/- 5 ml/100 g/min. A Diamox dose of 2 g (9 cases) causes no further rCBF increase. After plotting the rCBF before provocation (rCBFR) and the Diamox-induced rCBF increase (reserve capacity, delta rCBF) the regression line was delta rCBF = -0,6XrCBFR + 50 (correlation coefficient: r = -0,77). In normals with relatively low rCBF values at rest, Diamox increases the reserve capacity much more than in normals with high rCBF values before provocation. It can be expected that this concept of measuring rCBF at rest and the reserve capacity will increase the sensitivity of distinguishing patients with reversible cerebrovascular disease (even bilateral) from normals.

Acetazolamide↗

PubMed1984

Dynamic SPECT with Xe-133: regional cerebral blood flow in patients with unilateral cerebrovascular disease: concise communication.

To validate xenon-133 dynamic single photon emission tomography (SPECT) clinically, 74 patients were examined. Strictly unilateral cerebrovascular disease was confirmed in 47 patients by clinical history and by transmission computerized tomography (TCT) and contrast angiography. Twenty-seven were excluded, considered normal. SPECT flow maps were evaluated visually (against TCT) or by automated region of interest (ROI) techniques (12 areas per slice) to measure area flow (AF) (ml/100 g-min) and interhemispherical area flow ratios (AR). These were compared with normal values. Minimum AF in affected hemisphere decreased, and AR-to-normal difference increased, with the severity of the disease. Visually, low-flow areas were detected twice as frequently in SPECT as areas of low density of TCT. In reversible episodes, sensitivity of AF alone ws significantly below the sensitivity of combined evaluation of flow and ratio.

Adult↗