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Biomedical subjects

D Hahn

Publications and source records attributed to D Hahn.

At least 235 records · Page 13Linked to original sources
PubMed1987

MRI of the breast--histopathologic correlation.

132 solid breast masses have been examined at our institution by MR and have consequently been histopathologically correlated. T1- and T2-weighted SE and multi-echo sequences have been evaluated visually. It was found that signal intensities of tissues on T2-weighted images correlated with the contents of fibrosis, cells or water. Thus in some lesions (which consisted of different tissue components), a characteristic internal structure was visible on T2-weighted images, reflecting their histopathologic structure. Corresponding to their different composition, differences of signal intensity have also been noted between those fibroadenomas with a high contents of fibrosis and all other well-circumscribed breast lesions (fibroadenomas, carcinomas). However, for the majority of lesions with irregular contours a discrimination based on signal intensities or calculated T1- and T2-values did not seem possible. This overlap can also be explained by the macroscopically similar composition (amount of fibrosis, water or cells) of benign and malignant irregular lesions.

Breast↗
PubMed1987

[Value of nuclear magnetic resonance tomography in the staging of tumors of the urinary bladder].

The accuracy of magnetic resonance imaging (MRI) and computed tomography (CT) in the staging of bladder tumors was evaluated in 46 patients. In the T-staging MRI was superior to CT. With MRI 38 out of the 46 tumors were correctly staged into the four groups T0, T1-T3a, T3b and T4. With CT this classification was only possible in 28 cases. The main advantages of MRI were the capability for multiplanar imaging, which improved evaluation of the bladder base and the bladder dome, as well as a better differentiation between tumor recurrency and fibrosis. In the evaluation of adenopathy MRI and CT proved to be equal and demonstrated a sensitivity of 50%.

Carcinoma, Transitional Cell↗
PubMed1986

[Value of noninvasive and intraoperative diagnosis of malignant mediastinal tumors].

Among malignant tumors of the mediastinum lymphomas are no indication for operation. In our experience, however, fine needle puncture, computed tomography (CT), nuclear magnetic resonance, mediastinoscopic biopsy of lymph nodes and intraoperative freeze section histology can only rarely differentiate between lymphomas and other tumors of the mediastinum. Only CT-guided or direct parasternal biopsy including immunhistochemistry can yield a reliable preoperative diagnosis and prevent unnecessary operation of lymphomas.

Biopsy↗
PubMed1986

[Results of a comparative study of MR, CT and sonography of patients with primary hyperparathyroidism].

Twenty-three patients with primary hyperparathyroidism were examined by MR, CT and sonography in order to localise the parathyroid adenoma. In twenty patients, surgery was performed and the findings confirmed histologically. Fifteen patients had an adenoma in a parathyroid and in three, the adenoma was in the mediastinum. In one patient there was hyperplasia of all parathyroids. Accuracy of MR was 98%, of CT 98% and sonography 94% in previously unoperated patients and is therefore similar for these methods. This is also true for previously operated patients (four) where MR was 88% accurate, CT 83% and sonography 91%. In sixteen patients without previous operation, MR had the highest sensitivity with 79%. In previously operated patients, the sensitivity of MR and sonography was equal, with 67%, and CT was similar with 66%, MR was able to differentiate adenomas by the specific measurements of T1 and T2.

Adenoma↗
PubMed1986

[Use of Gd-DTPA in the nuclear magnetic resonance study of the breast].

55 patients with altogether 60 breast masses have been examined postoperatively by plain MR, MR with Gd-DTPA and mammography at our institution. All breast carcinomas and fibroadenomas did enhance significantly. Non-proliferative dysplasia, normal breast tissue and scar tissue did not enhance significantly. Borderline enhancement has been found in cases of proliferative dysplasia. The diagnostic accuracy has been improved by MR with Gd-DTPA. Advantages have been an improved visualization of tumors in dense breasts, an improved differentiation between irregular dysplasia and carcinoma and an improved differentiation between post-therapeutic changes (after radiation, surgery or silicon implants) and carcinoma. Nevertheless both technical improvements and further clinical experience is necessary.

Breast↗
PubMed1986

[Magnetic resonance tomography in suspected acoustic neurinoma: technic and differential diagnosis].

Sixty-five patients with suspected acoustic neuromas were examined by CT and MR; the optimal diagnostic procedures are discussed. Extrameatal acoustic neuromas (11 cases) were all diagnosed by CT and MR, but only 82% of intrameatal tumours could be diagnosed by CT combined with air cisternography. Using special surface coils and the paramagnetic contrast medium Gd-DTPA, the accuracy of MR was 100%. All tumours greater than 4 mm were demonstrated. Following clinical and neurological examination, MR is the primary diagnostic method in the investigation of acoustic neuromas.

Diagnosis, Differential↗
PubMed1986

[Gd-DTPA in magnetic resonance diagnosis of chronic myocardial infarct].

30 patients with myocardial infarction older than three weeks were examined by MRI prior and following intravenous injection of 0.1-0.2 mmol/kg Gd-DTPA, 201TL-SPECT and cineventriculography. Gd-DTPA did not cause any significant change (p less than 0.05) of T2-values for infarcted or non-infarcted myocardium. Compared with this, signal intensity for T1-weighted images increased after the application of the contrast agent both for normal (26 +/- 14%) and infarcted myocardium (33 +/- 16%). The intraindividual signal intensity ratio for infarcted and normal myocardium increased from 1.06 +/- 0.07 to 1.12 +/- 0.09 after the injection of Gd-DTPA. The diagnosis of myocardial infarction by visual analysis of signal intensity was not possible in individual cases. Myocardial infarction could only be visualized indirectly by morphological changes such as wall thinning and aneurysm.

Adult↗
PubMed1985

The community residential treatment service: developing a continuum of prosthetic environments for the chronically disabled.

Among the many issues regarding the care of chronic mental patients, none is more pressing than the need for administrative and clinical models designed to organize and systematize the efforts of diverse community service providers. This paper describes the functioning of the Community Residential Treatment Service of the South Beach Psychiatric Center, a large-scale project of a state facility created to respond to this tissue. By blending sophisticated clinical and administrative technology, programs operated by the state, voluntary, and proprietary health care sectors have been integrated to form a balanced service delivery system. This system provides a broad continuum of inpatient and outpatient residential settings developed in accordance with social learning principles. The components of the system, with the Community Residential Treatment Service as the major integrative force, are linked together by detailed contracts as well as common behavioral clinical and behavioral administrative language. The treatment successes f this system have been significant enough to suggest that a positive synergistic effect is generated by this programming combination.

Community Mental Health Services↗
PubMed1985

Evaluation of transport kinetics in lymphoscintigraphy: follow-up study in patients with transplanted lymphatic vessels.

To quantitate visual findings in lymphoscintigraphy with 99mTc-labeled stannous sulfur colloids, a numeric index of transport kinetics was designed by combining visual assessment of five criteria: temporal and spatial distribution of the radionuclide, appearance time of lymph nodes, and graded visualization of lymph nodes and vessels. For assessment, scores were used ranging from 0 to 9. Thus, the resulting transport index (TI) ranged from 0 (normal) to 45 (pathological). TI in healthy extremities was less than 10. Lymphoscintigraphy was performed routinely in healthy lower extremities to ensure normal drainage before transplantation. In 122 investigations of upper and lower extremities, TI was found to be very sensitive (97.4%). Specificity was 90.3%. An interobserver study in 179 investigations revealed a high correlation (r = 0.96). A total of 23 patients underwent autologous lymphatic transplantation. The average decrease of TI was 5.9: 31.1 before and 25.2 after transplantation. This decrease of TI was correlated with a marked decrease of the volumes of the extremities (from 3423 ml to 2580 ml). Changes in TI and volume were significant (p less than 0.05). This method of evaluation has proved to be very sensitive, reproducible, and able to measure the transport capacity of only two or three transplanted lymph collectors.

Adult↗
PubMed1985

Synthesis and antifertility activity of zoapatanol analogues.

The synthesis of and guinea pig contragestational screening data for several oxepane and 3,8-dioxabicyclo[3.2.1]octane analogues of zoapatanol (1) are described and their structure-activity relationships discussed. Conversion of the 5-keto group on the nonenyl side chain of 1 into a hydroxyl function enhanced the potency. Further significant enhancement in the potency was realized with the transformation of several oxepanes into the 3,8-dioxabicyclo-[3.2.1]octane-1-acetic acid derivatives. Detailed, comparative contragestational evaluation of the three most potent compounds 9, 33, and 37 is presented, which led to the selection of 33 (ORF 13811) for further biological evaluation.

Abortifacient Agents↗
PubMed1985

[Digital radiography--methods and clinical application].

The term "Digital Radiography" covers all x-ray techniques which produce a projected image with the help of digital imaging techniques, which are very similar to a conventional x-ray film image. The advantage of "Digital Radiography" is the possibility of digital image processing, like the subtraction technique, the selective material filtering technique and the quantitative image plotting technique. With the equipments now in use, the digital projected image is produced by the line or on an even level. One example of the in-line projected image is the so-called "topogram", produced via computed tomography equipment. With the help of an x-ray video chain, it is possible to produce digital images on an even level. This technique is used, for example, for "digital video subtraction angiography" (DVSA). Today, digital radiography is clinically used only in the "DVSA" and the "topogram" systems. A survey of the clinical use and the improved future possibilities of digital radiography is given, and the special features of the method are discussed.

Analog-Digital Conversion↗
PubMed1985

[Nuclear magnetic resonance tomography in breast cancer diagnosis--present status and future outlook].

Due to its high soft tissue contrast MR appears particularly well suited for the examination of the breast. However, it was only after the development of breast coils and the concomitant improvement of the image quality that examinations regarding the potentials of MR in breast cancer diagnosis became interesting. Thus, MR of the breast is still in the initial stage. First results indicate that at present the expected tissue differentiation by MR parameters T1, T2 ...) is not possible MR proved nevertheless advantageous for selected cases. Further research is necessary.

Breast Neoplasms↗
PubMed1985

[Value of nuclear magnetic resonance tomography in the diagnosis and therapy outcome of prolactinomas].

30 MR tomographies were performed in 15 patients suspected of having a prolactinoma on account of clinical examinations and test in the chemical laboratory. The T1 and T2 times of the adenomas were determined quantitatively. In addition, high resolution CT imaging had been performed in all patients. The signal performance of the normal pituitary gland determined in 11 healthy persons on the basis of quantitatively measured T1 and T2 times, was found to largely correspond with that of grey matter of the brain. Of the 14 confirmed prolactinomas, 11 were microadenomas and 3 macroadenoma. Solid adenomas were identified by enhanced T1 values. It was possible to differentiate these from cystic, haemorrhagic and necrotic tumour components by differences in signal performance. 7 patients on drug therapy with dopamine agonists were controlled by means of MR tomography. No measurable size reduction of tumour was seen in 3 patients with cystic or haemorrhagic tumour components. On the other hand, tumour reduction was seen after brief drug therapy in 2 macroprolactinomas and one microprolactinoma. An essential advantage offered by MR is, besides the absence of exposure to radiation, in the first place the better and more precise information on the relative position of the adenoma with reference to the vessels and the optic chiasm, and, secondly, better identification of cystic and haemorrhagic processes within the prolactinoma.

Adenoma↗
PubMed1984

Inhibin activity and steroid hormone levels in ovarian extracts and ovarian vein plasma of female monkeys during postnatal development.

Inhibin activity, follicle-stimulating hormone (FSH)-suppressing substance, estrogen, progesterone, and androstenedione were measured in charcoal-treated ovarian tissue and ovarian venous and peripheral blood of eight rhesus monkeys ranging from 12 to 48 months of age. All of the monkeys demonstrated inhibin activity in ovarian tissue, which, if expressed per milligram protein, was relatively constant throughout development. However, if the activity was expressed per ovary, the amount of ovarian FSH-suppressing substance increased between 26 and 48 months; it was present in detectable amounts in ovarian venous blood only in one 26-month-old monkey. Detectable levels of estrogen were present in ovarian venous blood of the 26-month-old and the 48-month-old monkeys but not in the younger monkeys. It is possible that the secretion of inhibin activity may be in part responsible for low levels of serum FSH observed prior to puberty, because it has been observed by others that bilateral ovariectomy in the prepubertal monkey can result in a rise in FSH and that administration of charcoal-treated ovarian follicular fluid can suppress serum FSH in castrated prepubertal and adult rhesus monkeys.

Androstenedione↗
PubMed1984

[Extravasation of contrast media in the excretory urogram].

Aetiology and diagnostic procedure of calyceal fornix rupture during intravenous urography are discussed. In the literature the fornix rupture is described as a spontaneous event--not so in the four cases presented. In two cases a sudden increase in intrapelvic pressure was due to an ureteric calculus, in the other cases an obstruction of the ureter was secondary to neoplasm. It is recommended to perform a CT as soon as a contrast medium extravasation in intravenous urography is diagnosed.

Adult↗