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Biomedical subjects

G Friedmann

Publications and source records attributed to G Friedmann.

At least 19 recordsLinked to original sources
PubMed1992

In vivo imaging of glucose consumption and lactate concentration in human gliomas.

Twenty patients with histologically confirmed gliomas were studied with positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H-MRS). PET with 18F-2-fluoro-2-deoxy-D-glucose (FDG) provided tomograms of the metabolic rate of glucose. MRS images were obtained by combining volume-selective excitation with phase-encoded acquisition. With 32 x 32 gradient phase-encoding steps, an in-plane resolution of 7 x 7 mm was achieved. From this set of spectra, lactate maps were created and compared with PET maps of glucose metabolism. Maximum glucose metabolic rates within tumors (relative to metabolic rates of glucose in contralateral regions of the brain) were correlated significantly with maximum lactate concentrations (relative to N-acetyl aspartate peaks in the contralateral part of the brain). In 8 tumors, no lactate was detected, and in 7 of these the maximum glucose metabolic rate was below the median value. The tumor with the highest lactate concentration also had the highest glucose metabolic rate. The topographic relation between glucose metabolic rate and lactate concentration could be analyzed in 9 patients by three-dimensional alignment of the PET and MRS images. In that analysis, maximum lactate concentrations were often not found in the same location as maximum glucose metabolism, but lactate tended to accumulate in tumor cysts, necrotic areas, and the vicinity of the lateral ventricles. The combination of FDG PET and 1H-MRS imaging demonstrates details of the spatial relation between the two poles of nonoxidative glycolysis, glucose uptake and lactate deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Experimental studies on magnetic resonance tomographic and magnetic resonance angiographic imaging of poststenotic flow patterns].

A phantom has been developed, which permits the perfusion of defined stenosis with variable flow rates. The post-stenotic flow patterns were imaged by means of conventional MRI sequences and special angiographic sequences using a 1.5 total body scanner (Gyroscan S15, Philips). For conventional MRI images, spin-echo-sequences (TR 500 ms, TE 27 ms with reconstruction of the magnitude and phase images) and gradient-echo-sequences (TR 60 ms, TE 27 ms, flip angle 15 degrees with reconstruction of the magnitude images) were used. For MR angiography 2D inflow (multiple-single-slice-technique, TR 40 ms, TE 14 ms, flip angle 60 degrees) and flow-adjusted-gradient-sequences (TR 24 ms, TE 10 ms, flip angle 60 degrees) were performed. In addition to an analysis of the appearances, the length of the changed signal intensity beyond the stenosis was evaluated. For constant flow rates it increases with the severity of the stenosis. For a constant stenosis the length of the post-stenotic signal change alters with flow rate. The changes also depend on the direction of flow and the gradients of the chosen sequences. The comparison of magnitude and phase images allows the discrimination between turbulent and non-turbulent flow. It therefore appears possible to estimate the severity of arteriosclerotic occlusive disease by means of MRI in the future.

Blood Flow Velocity↗
PubMed1992

Human brain tumors: spectral patterns detected with localized H-1 MR spectroscopy.

Image-guided localized proton magnetic resonance (MR) spectroscopy of intracranial tumors was performed to correlate spectral patterns and histologic findings. Thirty-six patients were examined prior to any specific treatment. Evaluation based on signal intensity ratios showed that all tumor spectra differed from spectra of healthy brain tissue. Ratios of creatine to choline-containing compounds (Cr/Cho) and nitrogen acetyl-aspartate to Cho (NAA/Cho) were reduced significantly in all tumor spectra compared with spectra of normal tissue in contralateral brain hemispheres (P less than .005). Noncerebral tumors typically showed a vanishing or missing NAA signal, strongly reduced Cr signal, and additional signals, assigned to alanine in meningiomas and lipids in metastases. In contrast, 11 gliomas of grades 2 and 3 exhibited NAA/Cho ratios and Cr/Cho ratios that were less than normal but that were significantly larger (P less than .01) than corresponding values in eight meningiomas. Ten glioblastomas displayed spectra with various signal ratios, so no significant differences between them and other tumor types could be established. In nine gliomas a clearly detectable lactate signal was present. However, no direct correlation between lactate level and histologic tumor grading was found.

Adult↗
PubMed1979

[Computer tomography on the pancreas. A diagnostic extension from the surgical aspect (author's transl)].

125 patients were subjected to computer tomography on account of suspected pancreatic disease. 48 patients were operated on--the computer tomography (CT) diagnosis was confirmed in 85.5% of the cases. Acute pancreatitis can be detected by CT if it is accompanied by an appropriate enlargement of the organ. Chronic pancreatitis can be recognized by deformations of the organ, calcifications or formation of pseudocysts. Pancreatic carcinoma is recognizable when it is larger than 3 cm accompanied by a change in the shape of the organ or if infiltration of neighboring structures has occurred. Computer tomography offers patients a safe, non-invasive method of performing follow-up examinations at short intervals.

Acute Disease↗
PubMed1979

[Computed axial tomography (cat) in the diagnosis of diseases of the heart and aorta (author's transl)].

Computed axial tomography (CAT) was used in 70 patients with diagnostic problems centering on the heart (47 patients) or the aorta (23). The method proved suitable for the diagnosis, differential diagnosis and serial control of pericardial effusions and also well demonstrated intracardiac tumours. Aortic aneurysms are also easily demonstrated and their extent can be exactly defined. But aortic wall dissection and stenosis of arteries arising from the aorta are not visualized and therefore require angiography.

Adolescent↗
PubMed1979

[Computer tomography of the facial skeleton and pharyngeal space (author's transl)].

Seventy-five patients with histologically confirmed abnormalities of the facial skeleton and pharynx, including the mouth and base of the tongue, were examined by computer tomography. The advantages of simultaneous demonstration of the soft tissues and bones in localised space-occupying lesions are pointed out. Accurate comparison between pre-operative descriptions and findings at operation in 30 cases showed high diagnostic accuracy. Conventional, multi-dimensional film tomography is being increasingly replaced by computer tomography.

Diagnosis, Differential↗
PubMed1979

[Computer tomography in the diagnosis of local recurrences after resection for carcinoma of the rectum (author's transl)].

Presacral or pelvic floor tumour recurrence after abdomino-perineal resection for rectal or anal carcinomas has not been amenable to early radiological diagnosis. Computer tomography is a procedure which can demonstrate recurrences of two to three cm. Within the pelvis with certainty. The reliability of the method has been demonstrated in 27 patients suspected of having recurrences. The effect of demonstrating or excluding a recurrence on subsequent treatment is discussed. The value of computer tomographic examination of the pelvis for demonstrating the position and extent of a recurrence, the displacement of neighbouring organs, destruction of the pelvis and involvement of iliac lymph nodes is shown.

Adult↗
PubMed1979

[Radiological diagnosis of colorectal polypi and carcinomas which have not progressed].

Provided examination conditions are optimal, we are now able to detect changes of the wall of the colon from about 5 mm diameter upwards and thus to further clarify the diagnosis and to initiate appropriate treatment. Hence, the demand for early or timely diagnosis can be met by means of x-ray diagnosis in respect of processes of the colon.

Adenocarcinoma↗
PubMed1979

[CT scanning of the orbita (author's transl)].

Basing on selected cases, the efficiency spectrum of modern CT apparatus in the diagnosis of orbital disease is described. Besides exact localisation of retrobulbar space-occupying growths, CT scanning enables good identification of pathological processes at the bulbus and those of parabulbar location, at the lacrimal gland, the optic nerve and the ocular muscles. Extraorbital changes are clearly identifiable.

Eye Diseases↗
PubMed1978

[Angiographic findings in 86 confirmed tumours of the posterior cranial fossa (author's transl)].

The accuracy of vertebral angiography in the diagnosis of tumours was reviewed on the basis 368 selective angiograms. The greatest accuracy was achieved with space-occupying lesions situated centrally in the cerebellum in the region of the fourth ventricle or in the vermis. However, tumours growing eccentrically, but arising in this region, were occasionally missed. Least reliable is the angiographic diagnosis of tumours is the cerebellar hemispheres. Of these, only about two-thirds could be demonstrated. Only 60% of cerebello-pontine tumours were diagnosed from displacement of various structures, another 10% by the presence of pathological vessels or tumour staining. The classic angiographic picture of pontine tumours is rare. Brain stem tumours are frequently eccentric and may simulate cerebello-pontine angle tumours. The demonstration or exclusion of brain stem involvement can be difficult. In view of the implications for treatment, this should, however, always be attempted.

Adolescent↗
PubMed1978

[Computer cardio-tomography for tumours of the left atrium (author's transl)].

The role of computer tomography in the diagnosis of cardiac tumours was demonstrated by three patients with myxomas of the left atrium. After intravenous contrast administration these tumours appeared as relatively translucent space-occupying lesions on the computer tomograph. The invasive method of angio-cardiography is unlikely to provide any additional information concerning tumour size or localisation when compared with non-invasive computer tomography or echo cardiography.

Female↗
PubMed1978

[Diagnostic relevance of computer tomography (CT) in pancreatic disease (author's transl)].

CT-x-ray examination of 98 patients yielded pathologic results in 42 patients; in 33 patients results of CT could be controlled by surgery or at autopsy. In 14 cases necrotizing pancreatitis or pancreatic pseudocysts were suspected and these cases were operated upon; only 1 case turned out to be a falsely positive diagnosis. In 15 cases pancreatic carcinoma were found at surgery; 13 of these cases had been diagnosed preoperatively by CT; the diameters of the 2 tumors not diagnosed were below 3-4 cm. Differentiation between cysts, pancreatitis and tumors was possible in 2/3 of all cases; in 1/3 of the cases differentiation was neither possible by applying morphological criteria nor by evaluating absorption spectra. It turned out to be advantageous to examine the parenchymatous organs surrounding the pancreas by CT as well; in about 12% of cases with pathological findings the processes were found to be localized extrapancreatically.

False Positive Reactions↗
PubMed1978

[Extension of thoracal diagnostics through computer tomography (author's transl)].

The utilization of transverse layers in computer tomography opens up a new level of examination for localization of pathologic processes in the thorax and their spread. The good resolution of roentgen absorption differences in the soft parts enables the use of computer tomography in the diagnosis of pericardial effusions and for further differentiation of known mediastinal growing and displacing processes. This method is also suitable for the identification of aneurysms, since it is not invasive and places hardly any strain on the patient. Finally, computer tomography can also be used for radiotherapy and operation planning, as well as in target biopsy on account of the true-to-scale and reproducible image of the body cross-sections.

Aortic Diseases↗