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Biomedical subjects

B Hamm

Publications and source records attributed to B Hamm.

At least 253 records · Page 14Linked to original sources
PubMed1986

[Magnetic resonance tomography of focal hepatic lesions using the para-magnetic contrast medium, gadolinium DTPA. First clinical results].

The use of the para-magnetic contrast medium gadolinium DTPA for magnetic resonance tomography of focal lesions in the liver was investigated in 31 patients. Two dosage schedules of the contrast medium (0.1 and 0.2 mmol/kg body weight were used with field strengths of 0.35 and 0.5 Tesla. Using T1 sequences, gadolinium DTPA showed increased signal intensity in the liver and in tumours, but this was significantly more marked in the tumour. On T1 spin-echo sequences, previously iso-intense lesions became visible after administration of contrast. On the other hand, contrast-enhanced lesions were less well seen on inversion recovery sequences because of a reduction in the contrast between tumour and liver tissue. The contrast between tumour and liver tissue was not improved by gadolinium DTPA in comparison with precontrast inversion recovery sequences and T2 spin-echo sequences. The perfusion of intra-hepatic tumours could be elucidated by magnetic resonance tomography after the administration of gadolinium DTPA.

Adult↗
PubMed1986

Varicoceles: combined sonography and thermography in diagnosis and posttherapeutic evaluation.

One hundred eighteen patients with clinically suspected varicocele were examined with thermography and sonography before phlebography of the internal spermatic vein (ISV). The combination of sonography and thermography led to an exact differentiation among eight patients with normal findings (6.8%), 103 with left-sided varicoceles (87.3%), six with bilateral varicoceles (5.1%), and one with a right-sided varicocele (0.85%). The accuracy of thermography was 98.4% and of sonography, 92.7%. With sonography, venous dilatation was detected when the patients were upright and the Valsalva maneuver was being performed. Thermography was more sensitive than sonography in detecting persistent varicocele in 63 patients reexamined after sclerotherapy. Sclerotherapy within the inguinal segment of the ISV gave better results (82.9%) than that within the proximal segment (77.3%).

Adolescent↗
PubMed1985

[Status of penis sonography in andrology].

Good visualization of the anatomic structures of the penis can be achieved by application of high-resolution real-time sonography and a water path. Penis sonography is painless, free of risk and easy to perform. It is ideal for documentation and assessment of pathological alterations of the penis. 80 patients with penile deviation were examined sonographically. In cases of Peyronie's disease, the most frequent clinical picture, it is possible to achieve good localization and measurement of the fibrotic plaques in the area of the tunica albuginea. Calcifications can be clearly detected. In cases of penile deviation associated with the urethral manipulation syndrome, no fibroses are seen in the corpus spongiosum. In 3 patients with erectile impotence after priapism, sonography permitted precise determination of the extent of fibrosis formation in the corpora cavernosa.

Adult↗
PubMed1982

[Morphological findings in the distal end of the oesophagus after sclerosis of bleeding varices (author's transl)].

The morphological changes in the distal oesophagus occurring after tube treatment, sclerosis and/or shunt operation for acutely bleeding oesophageal varices were investigated in 29 post mortems between March 1979 and April 1980. In addition three oesophagi were investigated after sclerosis several months previously. As was to be expected the oesophagi showed no specific changes after recent porto-caval shunts. In contrast there were definite histological differences after tube treatment as opposed to sclerosis. After compression tubes the oesophagi showed focal pressure necroses and ulcers. In the sclerosed oesophagi there frequent widespread, partially transmural, necroses, suppurative inflammation of the oesophageal wall and mediastinitis. Serious complications occurring after sclerosis were perforation with mediastinal abscess, pleuritis and severe paraoesophageal haemorrhage. In the prevention of complications after sclerosis both the injection technique and the choice of sclerosing agent are important.

Adult↗
PubMed1982

Experimental studies on the functional capacity of the alloplastic spermatocele (Kelâmi-Affeld prosthesis).

An alloplastic spermatocele is implanted to obtain spermatozoa from the epididymis. It is known that, in an alloplastic spermatocele, spermatozoa deteriorate qualitatively and quantitatively as the time interval after implantation increases. 39 Kelâmi-Affeld alloplastic spermatoceles were implanted at the epididymal heads in minipigs. Castration and pathological-anatomical examination of the specimens were performed weeks to months after the operation. It became evident that fibrosis and granulation tissue in the area of the incised epididymal head with occlusion of the opened epididymal tubuli were the causes of aspermia developing in all cases. Apart from normal wound healing, there is additional formation of fibrosis and granulation tissue due to postoperative microbleeding and inflammatory reactions. It may be possible to reduce these complications by microsurgical techniques.

Animals↗
PubMedDate not supplied

Mn-DPDP enhancement patterns of hepatocellular lesions on MR images.

The recently developed paramagnetic hepatobiliary contrast agent manganese dipyridoxyl diphosphate (DPDP) was evaluated in eight patients. Pathologic diagnoses included five hepatocellular carcinomas, two cirrhoses, and one focal nodular hyperplasia. T1-weighted spin-echo and gradient-echo images were obtained after intravenous injection of 5 or 10 mumol/kg Mn-DPDP; these were compared with unenhanced T1-weighted spin-echo and gradient-echo images and T2-weighted spin-echo images. In all patients with lesions of hepatocellular origin, focal areas of increased enhancement were seen in the lesions after administration of Mn-DPDP. In the cirrhotic livers, these areas corresponded to foci of hepatic regeneration. In all patients, the signal-to-noise ratio in normal liver tissue increased significantly after injection of Mn-DPDP. Signal intensity in the six primary liver tumors was further increased, so that they appeared hyperintense relative to surrounding liver tissue on all T1-weighted images. Conspicuity and demarcation of all lesions were improved on Mn-DPDP-enhanced images.

Adult↗
PubMedDate not supplied

Contrast-enhanced MR imaging of liver and spleen: first experience in humans with a new superparamagnetic iron oxide.

The aim of this prospective study was to obtain the first human safety and magnetic resonance (MR) imaging results with a new formulation of superparamagnetic iron oxide (SPIO) (SHU 555 A). The SPIO was tested at four iron doses, from 5 to 40 mumol/kg. Laboratory tests and clinical measurements were done in 32 healthy volunteers for up to 3 weeks after administration. MR imaging at 1.5 T was performed before and 8 hours to 14 days after fast intravenous injection (500 mumol Fe/min) of the SPIO (six subjects per dose). Results of this phase I study demonstrate that SHU 555 A at a concentration of 0.5 mol Fe/L was well tolerated. A dose-dependent minor increase in activated partial thromboplastin time, which remained within the normal range, was seen. All doses of SPIO caused a signal loss in both liver and spleen (P < .05) with a spin-echo sequence (TR = 2,300 msec, TE = 45 msec). The signal losses in the liver 8 hours after contrast agent injection were 58%, 79%, 82%, and 87% for the 5, 10, 20, and 40 mumol Fe/kg doses, respectively. The corresponding signal losses in the spleen were 23%, 45%, 65%, and 78%, respectively. The doses that reduced signal intensity by half were 3.1 mumol Fe/kg for the liver and 12.8 mumol Fe/kg for the spleen. The results suggest that the new SPIO formulation is a safe and efficient MR contrast agent.

Adult↗
PubMedDate not supplied

Initial experience with dynamic MR imaging in evaluation of normal bone marrow versus malignant bone marrow infiltrations in humans.

The purpose of this study was (a) evaluation of dynamic contrast-enhanced MR imaging of normal bone marrow versus malignant bone marrow infiltrations in patients with proven B-cell-type chronic lymphocytic leukemia (B-CLL) and (b) correlation with the clinical stage according to Binet (stages A, B, C) and response to therapy. Bone marrow imaging of the lumbar spine, pelvis, and proximal femurs was performed at 1.5 T in 45 patients without known malignancy and in 30 patients with B-CLL. The differences between opposed-phase and in-phase dynamic gradient-echo sequences before and up to 10 minutes after intravenous application of .1 mmol/kg body weight of gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) were evaluated in normal bone marrow. The contrast-enhancement patterns of normal and malignant bone marrow were compared using the opposed-phase dynamic gradient-echo sequence. Ten of the patients with bone marrow infiltrations (Binet stage C) additionally underwent MR imaging follow-up during therapy. Opposed-phase gradient echo sequences demonstrated a signal decrease of normal bone marrow, and in-phase gradient echo sequences demonstrated a signal increase of normal bone marrow after administration of Gd-DTPA. The dynamic signal intensity time courses differed significantly (P < .05) between Binet stages B and C and controls as well as among the three Binet stages of B-CLL. In the 10 patients followed during therapy, MR imaging sensitively demonstrated response (n = 6), nonresponse (n = 2), or relapse after initial response (n = 2). In out-of-phase imaging, both normal bone marrow and initial bone marrow infiltration in CLL stage Binet A show signal decrease after administration of contrast agent, whereas there is increase in signal intensity in higher-grade bone marrow infiltration in Binet stage B or C disease. The signal loss of normal bone marrow in out-of-phase imaging is a phase effect rather than a T2* effect. The differentiation of initial from higher-grade bone marrow infiltration on out-of-phase images relies solely on a shift in the fat/water ratio.

Adult↗
PubMedDate not supplied

Carpal tunnel syndrome: staging of median nerve compression by MR imaging.

The purpose of this prospective study was to determine the potential of MR imaging to depict morphologic alterations of the median nerve correlating with the stage of carpal tunnel syndrome (CTS). Eighteen wrists of normal subjects and 81 wrists of patients with CTS were examined. MR imaging was performed with proton-density- and T2-weighted spin-echo sequences. Staging of CTS was done on the basis of clinical and electrophysiological testing, including evaluation of the number of previous steroid infiltrations in conservative treatment. Median nerve flattening, cross-sectional area, and signal intensity were measured from the distal radius to the end of the carpal tunnel. Delineation and structure of the median nerve were recorded qualitatively by two experienced radiologists in consensus. Three major MR imaging criteria of early CTS were (a) isolated prestenotic and intracarpal swelling of the median nerve (P < .01), (b) the absence of significant flattening, and (c) a generalized increase in signal intensity retrograde to the distal radius (P < .01). The nerve showed sharply delineated contours and a homogeneous signal pattern. Advanced CTS was characterized by retrograde swelling of the median nerve to the distal radius (P < .01) and decreased signal intensity (P < .05). Demarcation of the nerve became poorer, and its signal pattern appeared fasciculated. After steroid infiltration, the median nerve was difficult to delineate, showed an inhomogeneous structure, and swelling was less pronounced than without steroid infiltration (P < .05). MR imaging yields typical morphologic findings that correlate with the duration and severity of median nerve compression. Hence, MR imaging allows staging of median nerve compression in CTS and thus may contribute to therapeutic decision-making.

Carpal Tunnel Syndrome↗