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Biomedical subjects

B Hamm

Publications and source records attributed to B Hamm.

At least 163 records · Page 9Linked to original sources
PubMed1996

Testicular microlithiasis: case report and discussion of management under special consideration of testicular germ cell tumours.

We report a case of testicular microlithiasis in a 24-year-old man who was referred to us for evaluation of unclear ultrasonographic appearance of his testes while being examined for bilateral varicocele and epididymal cysts. Since testicular microlithiasis has been found to be associated with testicular germ cell tumours we suggest a diagnostic work-up with testis biopsy to rule out testicular intraepithelial neoplasia (so-called carcinoma in situ) in otherwise normal appearing testis.

Adult↗
PubMed1996

[Ultrasound diagnosis of the transplanted kidney].

Ultrasound is the primary imaging modality after kidney transplantation. Its general availability and the absence of radiation exposure and discomfort for the patient also make it a suitable procedure for follow-up. Simple B-mode sonography provides comprehensive information on the morphology of the renal transplant and surrounding structures, while color-coded duplex sonography (CCDS) additionally allows assessment of the anastomoses and organ perfusion. More recent technical advances such as power Doppler ultrasound appear to improve in particular the assessment of peripheral circulation. The possibilities and limitations of the various sonographic techniques in the evaluation of kidney transplants are discussed with special reference to the most important clinical aspects and some basic technical concepts.

Blood Flow Velocity↗
PubMed1996

[Contrast media for magnetic resonance tomographic lymph node diagnosis (MR lymphography)].

In MR-imaging, similar to computed tomography, diagnosis of metastatic lymph-node disease is based on lymph-node sizes, and thereby it is non-specific. Super-paramagnetic iron oxide as a potential contrast medium for MR-lymphography accumulate in normal lymph node tissue after endolymphatic, interstitial and, in case of very small particles, after intravenous injection. No accumulation occures in lymph node metastases. Lymph-node metastases can be detected by all three injection techniques. It has been shown experimentally, that in particular small metastases can be detected in normal sized lymph nodes. However, MR-lymphography also has inherent methodologic problems, as there may occure an uneven distribution of the contrast medium between different lymph-node groups. The experimental results with endolymphatic, interstitial, and intravenous MR-lymphography as well as first clinical results with intravenous contrast medium injection are presented and discussed.

Contrast Media↗
PubMed1996

[Cost benefit considerations in modern diagnostic sectional imaging exemplified by upper abdominal organs].

Demands for increased productivity despite cuts in financial resources have renewed the discussion of cost effectiveness in medical care. Unfortunately, there is a lack of reliable data for evaluating the cost effectiveness of diagnostic procedures. The present article discusses various aspects of this topic and presents examples from the diagnostic evaluation of the upper abdomen. It is argued that modern imaging procedures have in the past helped to reduce costs and that they can become cost effective when they replace established combinations of diagnostic procedures. The present discussion is severely hampered by the fact that there are no generally accepted standards for evaluating diagnostic strategies and that there are no well-founded studies of the cost effectiveness of the strategies used in abdominal diagnosis. Cost effectiveness will in the future become an additional criterion for assessing the quality of medical care.

Cost-Benefit Analysis↗
PubMed1996

Magnetic resonance lymphography in rats: effects of muscular activity and hyperthermia on the lymph node uptake of intravenously injected superparamagnetic iron oxide particles.

RATIONALE AND OBJECTIVES: We investigated the influence of muscular activity and regional body temperature changes on the accumulation of intravenously (i.v.) administered, dextran-coated superparamagnetic iron oxide (SPIO) particles in the lymph nodes of rats. METHODS: Four groups of rats (N = 21) were used. Five rats were allowed to move freely after i.v. contrast administration (group 1). In another five rats, muscular inactivity (group 2) was induced during i.v. injection of SPIO particles and for up to 2 hr thereafter by anesthesia. In seven rats (likewise anesthetized), the contrast agent was administered while the extremities of one side of the body were warmed in a water bath for 2 hr (group 3). The rats in groups 1-3 received 100 mumol Fe/kg of the contrast agent. Four rats not given SPIO particles served as the control group (group 4). The lymph nodes of all animals were removed 24 hr after SPIO administration and were embedded in an agar matrix for magnetic resonance imaging at 1.5 T using a proton-density-weighted spin-echo (PD-SE) sequence and a T2*-weighted gradient-recalled echo (T2* GRE) sequence. RESULTS: Signal loss varied widely among the different lymph nodes in group 1. A pronounced signal reduction was observed in the mesenteric (PD-SE = 20 +/- 6%, T2* GRE = 55 +/- 19%), iliac (PD-SE = 13 +/- 13%, T2* GRE = 44 +/- 24%), and popliteal (PD-SE = 24 +/- 7%, T2* GRE = 70 +/- 11%) lymph nodes and only a moderate reduction in the mandibular (PD-SE = 4 +/- 7%, T2* GRE = 42 +/- 15%), axillary (PD-SE = 0 +/- 4%, T2* GRE = 8 +/- 7%), and inguinal (PD-SE = 5 +/- 5%, T2* GRE = 34 +/- 18%) lymph nodes. The least pronounced signal loss occurred in the peripheral lymph nodes of group 2, ranging from 0 +/- 3% for PD-SE sequences and 10 +/- 11% for T2* GRE sequences to 13 +/- 15% for PD-SE sequences and 41 +/- 19% for T2* GRE sequences. In group 3, the uptake of contrast material in the peripheral lymph nodes of the hyperthermal side was significantly more pronounced than on the contralateral side (p < .01), and the contrast agent was distributed more evenly to the different lymph node groups than in group 1. CONCLUSION: Muscular activity and regional hyperthermia markedly influence the accumulation of SPIO particles in different lymph node groups in rats. These findings must be considered in preclinical studies and in the clinical administration of MR lymphography.

Anesthesia↗
PubMed1996

Endoscopic ultrasonography and somatostatin receptor scintigraphy in the preoperative localisation of insulinomas and gastrinomas.

BACKGROUND: Endoscopic ultrasonography (EUS) and somatostatin receptor scintigraphy (SRS) can detect a high percentage of gastroenteropancreatic neuroendocrine tumours especially in the upper gastrointestinal tract. The ability of these procedures to localise primary tumour lesions and metastases of gastrinomas and insulinomas was evaluated in comparison with transabdominal ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). PATIENTS AND METHODS: In a prospective trial, patients with gastrinomas (n = 10) and insulinomas (n = 10) diagnosed by clinical signs and laboratory tests were assessed by EUS, SRS, US, CT and MRI. RESULTS: In 10 patients with gastrinoma and 10 patients with insulinoma, a total of 14 separate primary tumour lesions were histologically confirmed for each of the tumour entities. The mean diameter was 2.1 cm for gastrinomas and 1.5 cm for insulinomas. All insulinomas and nine gastrinoma lesions were located in the pancreas. Three gastrinomas were found in the duodenal wall, one in a periduodenal lymph node, and one in the liver, For gastrinomas, sensitivities were 79% with EUS, 86% with SRS and 29% with CT, US, and MRI. For insulinomas, sensitivities were 93% with EUS, 14% with SRS, 21% with CT and 7% with US and MRI. CONCLUSIONS: EUS is of high value for localising primary lesions of both tumour entities. SRS is a very sensitive procedure for diagnosing of gastrinomas but not insulinomas. CT, US and MRI are primarily useful for visualising metastases.

Adolescent↗
PubMed1995

[Somatostatin receptor scintigraphy and endoscopic ultrasound for the diagnosis of insulinoma and gastrinoma].

In a prospective study of 13 patients (three males and 10 females; mean age 53 [8-82] years) the value of somatostatin receptor scintigraphy (SRS) and endoscopic ultrasonography (EUS) was compared with transabdominal ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of insulinoma (six patients) or gastrinoma (seven patients). There were ten separate primary lesions of each tumour type, proven histologically. For insulinoma the sensitivity of EUS was 90%, SRS 10% and CT, US and MRI together 20%. For gastrinoma the sensitivity of EUS was 90%, SRS 100%, and 30% for the other three methods together. Thus EUS had a high diagnostic localizing sensitivity for both tumours, while SRS was highly sensitive only in the diagnosis of gastrinoma, not insulinoma. The value of CT, MRI and conventional ultrasonography lies in their ability to visualize distant metastases.

Adolescent↗
PubMed1995

Maturation of the testis: ultrasound evaluation.

We performed a prospective study to investigate whether the sonographic appearance of the testicular parenchyma changes during maturation of the testis. One hundred forty-three boys ranging in age from 6 months to 16 years, and 11 volunteers aged about 30 years, were included in the study. The echogenicity of each of the 308 normal testes were determined by measuring the average brightness of a histogram over a defined testicular area. To avoid divergent results due to different settings of the device in individual cases, the average brightness of a histogram of a standard ultrasound phantom was measured immediately after the examination of each testicle. From these 2 measurements, testicular echogenicity could be calculated independently of individual equipment settings. All testes had a homogeneous echotexture. The echogenicity of the prepubertal testis was markedly reduced compared to the medium-level echogenicity of the mature testis (p < 0.001). Testicular echogenicity increases during puberty. We conclude that testicular echogenicity increases with maturation. Knowledge of this fact may improve the diagnostic performance of scrotal ultrasound especially in children.

Adolescent↗
PubMed1995

T2-weighted breath-hold MR imaging of the liver at 1.5 T: results with a three-dimensional steady-state free precession sequence in 87 patients.

PURPOSE: To evaluate a fast three-dimensional (3D) sequence that permits the acquisition of 16 T2-weighted images within a 29-second breath hold for magnetic resonance (MR) imaging of the liver. MATERIALS AND METHODS: Eighty-seven patients with focal liver lesions were examined at 1.5 T by using a 3D reversed fast imaging with steady-state precession (PSIF) sequence at flip angles of 15 degrees, 30 degrees, and 70 degrees and a T2-weighted spin-echo (SE) sequence. Quantitative and qualitative image analysis was performed. RESULTS: Contrast and signal difference-to-noise ratios were 56% and 33% (liver-spleen) and 76% and 68% (liver-tumor), respectively, with the 3D-PSIF sequence compared with the T2-weighted SE sequence. With 3D-PSIF, overall image quality was poorer than that of the T2-weighted SE sequence at flip angles of 15 degrees but was similar at 30 degrees and 70 degrees. At low flip angles (15 degrees and 30 degrees) all lesion types were hyperintense. At a flip angle of 70 degrees, it was predominantly cysts and hemangiomas that showed high signal intensity. With the 3D-PSIF sequence, intrahepatic vessels are void of signal and can be better distinguished from small liver lesions compared with the flow-compensated T2-weighted SE sequence. CONCLUSION: The fast 3D-PSIF sequence is a valuable addition to MR imaging of the liver.

Adult↗
PubMed1995

Early sacroiliitis in patients with spondyloarthropathy: evaluation with dynamic gadolinium-enhanced MR imaging.

PURPOSE: To investigate the diagnostic value of gadolinium-enhanced magnetic resonance (MR) imaging in the detection of early sacroiliitis. MATERIALS AND METHODS: Of 125 patients with back pain, 72 had inflammatory back pain and had a diagnosis of spondylarthropathy; the other 53 patients had other mostly mechanical causes of back pain and served as the control group. The 72 patients with spondyloarthropathy were further subdivided into two groups according to established radiographic criteria for ankylosing spondylitis. While group 2 patients (n = 36) with a diagnosis of ankylosing spondylitis had definite radiographic changes in the sacroiliac joints, group 1 patients (n = 36) with undifferentiated spondylarthropathy had no such findings. RESULTS: While no contrast enhancement was found in normal sacroiliac joints, significantly different degrees of enhancement (P < .05) related to the patients' degree of pain were clearly detected in both groups of patients with spondyloarthropathy. Contrary to the mostly normal findings with precontrast MR imaging and with radiography, dynamic MR imaging revealed small erosions (< 1 mm) in 47 (72%) of the 65 inflamed joints in group 1 and juxtaarticular osteitis in 53 (82%). CONCLUSION: Contrast-enhanced MR imaging allows detection of sacroiliitis in early stages.

Adolescent↗
PubMed1995

Phase I clinical evaluation of Gd-EOB-DTPA as a hepatobiliary MR contrast agent: safety, pharmacokinetics, and MR imaging.

PURPOSE: To determine the safety, pharmacokinetics, and magnetic resonance (MR) imaging results of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) as a contrast agent for use in hepatobiliary MR imaging. MATERIALS AND METHODS: Gd-EOB-DTPA was tested at doses of 10, 25, 50, and 100 mumol per kilogram of body weight. Results of laboratory tests, clinical measurements, and pharmacokinetic data were obtained in 44 healthy volunteers in a double-blind, randomized, placebo-controlled design. MR images were obtained in another 16 healthy volunteers before and up to 6 hours after fast intravenous administration of Gd-EOB-DTPA. RESULTS: Gd-EOB-DTPA was well tolerated, with no important side effects or changes in laboratory parameters. Homogeneous enhancement of liver parenchyma was observed immediately after injection of the contrast agent. Peak liver signal intensity was noted 20 minutes after injection, followed by plateaulike enhancement over about 2 hours. The common bile duct was hyperintense within 10 minutes after injection in all volunteers. CONCLUSION: Gd-EOB-DTPA is safe and efficient for MR imaging of the liver.

Adult↗
PubMed1995

[Imaging methods in diagnosis of neuroendocrine tumors of the gastrointestinal tract].

Neuroendocrine tumors of the gastroenteropancreatic system represent a group of tumors with various diagnostic problems. Especially detection of primary tumor lesions is often difficult. Endoscopic ultrasonography is a relatively new imaging procedure localizing insulinomas preoperatively in about 90% of cases. Thus, previously used invasive preoperative imaging methods are usually unnecessary. The combination of endoscopic ultrasonography and somatostatin receptor scintigraphy allows visualization of gastrinomas in 90% of cases. Somatostatin receptor scintigraphy can also visualize metastatic lesions of gastrinomas and carcinoids in the whole body with high accuracy. In surgical management of a gastrinoma, duodenal transillumination and intraoperative ultrasound should be performed in all cases to exclude small duodenal or periduodenal, extrapancreatic tumors. US, CT, and MRI should be mainly used to exclude local and distant metastases. Angiography is helpful in detecting anatomical variations of abdominal vessels preoperatively. Due to the excellent results of endoscopic ultrasonography and somatostatin receptor scintigraphy in localizing insulinomas and gastrinomas, transhepatic portal venous sampling appears to be obsolete.

Carcinoid Tumor↗
PubMed1994

The value of magnetic resonance imaging in carpal tunnel syndrome.

We examined 62 patients (72 hands) with carpal tunnel syndrome (CTS) by magnetic resonance imaging (MRI) of the carpal tunnel and latency measurements of the median nerve. In 32 of 72 hands a probable causative lesion of the CTS was identified by MRI, for example tenosynovitis, a cyst-like structure, or an aberrant muscle. The MRI findings were confirmed by surgery in 16 of 24 hands, slightly corrected in 5, and not substantiated in 3. In 65 of 72 hands, MRI disclosed pathology of the median nerve, most prominently an enlargement of the nerve at the level of the os pisiforme, a finding not seen during surgery. Oedema of the nerve was found in 14 of 72 hands. The distal latencies were prolonged in 62 of 72 hands. The sensory latencies correlated significantly with the MRI-determined cross-sectional area of the nerve at the level of the distal radius. The lack of other correlations suggests that partly independent features of the nerve lesion are demonstrated in each method or that the sensitivity and specificity of both methods are limited. Further experience with MRI in CTS is desirable. At present, the practical use of MRI in CTS should be restricted to special diagnostic problems such as carpal tunnel syndromes which do not respond adequately to conservative or surgical treatment.

Adult↗
PubMed1994

[The value of the liver-specific superparamagnetic contrast medium AMI-25 for the detection and differential diagnosis of primary liver tumors versus metastases].

The value of the superparamagnetic contrast medium AMI-25 and its clinical acceptability was investigated in a phase-III-multicenter study. 18 patients with primary and secondary hepatic tumours were studied using T2- and T1-weighted spin-echo sequences, FATSAT sequences and FLASH-2-D-breathold sequences, both before and after intravenous application of AMI-25 (0.2 mmol GE/ml 15 mmol/kg KG in 100 ml 5% glucose infusion), using a 1.5 Tesla MRT (Magnetom 63 SP, Siemens). In 6 patients the MRT findings could be correlated with in vitro results within 30 minutes following surgical resection. In 8 patients a diagnosis of metastases was made. Amongst patients with primary liver tumours (FNH 6 cases, HCC 3 cases, adenomatosis 1 case) 3 of the 10 patients showed more lesions following the injection of contrast; similarly, in 4 patients of the 8 with secondary tumours contrast increased the number of visible lesions. The absence of contrast enhancement separated primary from secondary lesions. Amongst the patients with secondary liver tumours, in vitro correlation always showed more tumours than had been visualised whereas there was exact in vivo/in vitro correlation amongst patients with primary liver tumours.

Contrast Media↗