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Biomedical subjects

B Hamm

Publications and source records attributed to B Hamm.

At least 181 records · Page 10Linked to original sources
PubMed1994

Localisation of neuroendocrine tumours of the upper gastrointestinal tract.

In order to localise neuroendocrine tumours of the foregut type (that is, of the stomach, duodenum, and pancreas), 18 patients were studied prospectively by endoscopic ultrasonography, computed tomography, transabdominal ultrasonography, magnetic resonance imaging, and somatostatin receptor scintigraphy. These 18 patients had a total of 25 primary tumour lesions which were verified histologically in tissue obtained by surgery or by ultrasound or endoscopy guided biopsy. Tumours were found in the stomach (n = 1), duodenum (n = 6), pancreas (n = 17), and liver (n = 1). Endoscopic ultrasonography had the highest sensitivity for tumour detection, followed by somatostatin receptor scintigraphy, computed tomography, transabdominal ultrasonography, and magnetic resonance imaging (88%, 52%, 36%, 32%, and 24% respectively). Endoscopic ultrasonography was especially sensitive in tumours smaller than 2 cm in diameter (88% v somatostatin receptor scintigraphy 35%; computed tomography 12%; transabdominal ultrasonography 6%; and magnetic resonance imaging 0%). Of 17 tumours located in the pancreas, endoscopic ultrasonography showed a sensitivity of 94% (somatostatin receptor scintigraphy 47%; computed tomography 47%; transabdominal ultrasonography 41%; and magnetic resonance imaging 29%). Of eight extrapancreatic tumours, six were identified by endoscopic ultrasonography, five by somatostatin receptor scintigraphy, and only one by computed tomography, transabdominal ultrasonography, and magnetic resonance imaging. One neuroendocrine tumour that was not detected by endoscopic ultrasonography was correctly identified by somatostatin receptor scintigraphy. Endoscopic ultrasound allowed correct determination of the tumour size and tumour spread into parapancreatic structures, especially the large vessels (T stage), in all 14 patients operated upon. The lymph node stage (N stage) was correctly determined in 10 of these 14 patients. In summary, endoscopic ultrasonography and somatostatin receptor scintigraphy were the most sensitive imaging methods for the localisation of these tumours and should be used as early diagnostic procedures to accurately stage neuroendocrine tumours of the foregut type.

Adolescent↗
PubMed1994

Peripheral washout: a sign of malignancy on dynamic gadolinium-enhanced MR images of focal liver lesions.

PURPOSE: To assess the value of peripheral washout of contrast medium in differentiating benign from malignant focal liver lesions. MATERIALS AND METHODS: One hundred two patients, 49 with malignant liver tumors and 53 with benign lesions, underwent unenhanced T1- and T2-weighted and dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Dynamic contrast material-enhanced MR imaging was performed before and up to 10 minutes after intravenous administration of a bolus of gadopentetate dimeglumine (0.1 mmol/kg). RESULTS: On the dynamic contrast-enhanced images, 12 of the 49 malignant tumors had a rim that was hypo-intense to the center of the lesion ("peripheral washout" sign); this rim was best seen 10 minutes after administration of contrast material. This sign was absent in the remaining 37 malignant tumors as well as in all 53 benign lesions (P < .001). The peripheral washout sign had a sensitivity of 24.5% and a specificity of 100% in the diagnosis of malignancies of the liver. The malignant tumors with peripheral washout showed no difference in signal intensity between the periphery and the center on the unenhanced T1- and T2-weighted images. CONCLUSION: Peripheral washout is a specific sign of malignancy in dynamic gadolinium-enhanced MR imaging of liver lesions.

Contrast Media↗
PubMed1994

Focal liver lesions: characterization with nonenhanced and dynamic contrast material-enhanced MR imaging.

PURPOSE: To evaluate prospectively the diagnostic accuracy of non-enhanced and gadolinium-enhanced magnetic resonance (MR) imaging in characterization of hepatic lesions. MATERIALS AND METHODS: Fifty-five patients with benign and 52 patients with malignant focal liver lesions underwent examination at 1.5 T that comprised nonenhanced and dynamic contrast material-enhanced images. Four experienced radiologists independently read the different sets of images without and with knowledge of clinical history. RESULTS: Receiver operating characteristic analysis showed that dynamic contrast-enhanced MR imaging added information to nonenhanced MR studies and thereby improved distinction between benign and malignant lesions (P < .05). Knowledge of clinical data further improved lesion characterization with nonenhanced and combined nonenhanced and contrast-enhanced MR imaging (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is a useful adjunct for characterization of hepatic lesions. Knowledge of clinical history still has a decisive effect on interpretation of MR images of the liver.

Adult↗
PubMed1994

[Computerized tomography and MR tomography in diagnosis of ovarian tumors].

Transvaginal ultrasound is the method of first choice in patients with a suspected ovarian tumor. Computed tomography (CT) and magnetic resonance (MR) imaging are supplementary imaging procedures for the diagnostic evaluation of ovarian tumors. The major indications for a CT or MR examination are unclear ultrasound findings, the differential diagnosis of lesions and tumor staging. Dermoid cysts can be reliably diagnosed by both CT and MR imaging. The latter is superior in the demonstration of hemorrhagic lesions and in the evaluation of endometrial cysts. CT and MR imaging use identical morphological criteria for the differentiation of benign and malignant ovarian tumors; MR imaging is not superior to CT. For the staging of ovarian carcinomas, CT is the preferred imaging procedure. Contrast-enhanced MR imaging might be better for the evaluation of peritoneal carcinosis than other modalities.

Diagnosis, Differential↗
PubMed1994

[Case report of extra-intestinal manifestation of salmonella infection].

The case history of a 75 year old man is demonstrated, who developed an abscess in the scar after B-II-resection 30 years ago. In this abscess S. typhi murium was detected. Diabetes mellitus was an additional risk factor. A review of the literature is given concerning extraintestinal manifestations of salmonellosis with emphasis to the predisposing conditions.

Abdominal Abscess↗
PubMed1994

[Progress in magnetic resonance tomography of the liver: value of ultra-rapid imaging and liver-specific contrast media].

Ongoing technical improvements in magnetic resonance imaging (MRI) and the development of liver-specific contrast agents are likely to have an impact on the clinical assessment of liver disease. Technical progress towards methods of motion-free MRI and concepts of liver-specific contrast agents are presented. The potential impact of these developments on clinical medicine is discussed.

Animals↗
PubMed1993

Somatostatin-receptor imaging of neuroendocrine gastroenteropancreatic tumors.

BACKGROUND: Gastroenteropancreatic neuroendocrine tumors are often difficult to localize. This study was conducted to examine the value of somatostatin-receptor scintigraphy for visualization of gastroenteropancreatic neuroendocrine tumors. METHODS: Applying the recently developed indium-labeled somatostatin analogue 111In-pentetreotide to 40 patients with gastroenteropancreatic neuroendocrine tumors, the diagnostic power of pentreotide-receptor scintigraphy was evaluated in comparison with conventional imaging techniques. RESULTS: Expression of somatostatin receptors was observed in the majority of patients (11 of 17 in the foregut, 14 of 16 in the midgut, and 7 of 7 in metastatic neuroendocrine tumors with unknown primary). Comparative imaging by computerized tomography, magnetic resonance imaging, and transabdominal ultrasonography yielded false-negative results for somatostatin-receptor scintigraphy in 8 of 40 patients; however, in 16 patients, tumor tissue that had escaped conventional imaging techniques was detected by 111In-pentetreotide scintigraphy. CONCLUSIONS: 111In-pentetreotide scintigraphy is a practical, safe, and sensitive procedure for in vivo imaging of gastroenteropancreatic neuroendocrine tumors.

Adolescent↗
PubMed1993

[A liver tumor model in the rat suitable for experimental MRT].

A malignant tumour was implanted in the livers of 205 rats in the context of an experimental MRT project. The implantation technique of the Novikoff hepatoma is described. Within 10 days of implantation a solitary one-centimetre intrahepatic tumour develops; it is a hypovascular tumour with an invasive periphery and central tumour necrosis. The tumour model is distinguished by a high success rate of 91.1% and is suitable for experimental MRT studies of liver tumours.

Animals↗
PubMed1993

[The diagnostic role of contrast medium-enhanced MR tomography in the diagnosis of the post-diskectomy syndrome. A prospective study of 109 patients].

In a prospective study, 132 previously operated disc levels in 109 patients with failed back surgery syndrome (FBSS) were examined by MR imaging before and after intravenous application of a contrast agent (0.1 mmol Gd-DTPA/kg). The results were compared with current CT findings in 47 cases. The images were randomized and independently assessed by two experienced radiologists. A second intervention of a total of 30 disc levels was performed in 28 patients. Contrast-enhanced-MR imaging (CE-MRI) improved the differentiation of scar from recurrent disc herniation (RDH) compared to plain MRI and CT. Agreement between the two readers was significantly higher for CE-MRI than for the other two procedures (p < or = 0.001). CE-MRI additionally had the highest diagnostic accuracy (p < or = 0.001). The preoperative diagnosis made by CE-MRI was confirmed in 27 (90%) of the reoperated disc levels. Quantitative evaluation showed that there was no contrast enhancement in RDH as opposed to pronounced enhancement of 122% in scars (p < or = 0.001). Evaluation with respect to scar age revealed a significant difference (p < or = 0.01) in contrast enhancement between scars less and more than 2.5 years old.

Adolescent↗
PubMed1993

[Atypically located pancreatic pseudocysts in the liver, spleen, stomach wall and mediastinum: their CT diagnosis].

It was the aim of this computed tomography study to analyse the frequency, morphology, and cause of atypically located pancreatic pseudocysts. Of 236 patients with acute (n = 87) or chronic (n = 149) pancreatitis, 85 (36%) had pancreatic pseudocysts. Pancreatic pseudocysts atypically located in the liver, spleen, stomach wall or mediastinum were diagnosed in 19 (22.4%) of the 85 patients. The mean size of intrapancreatic, parapancreatic, and atypically located pseudocysts was 2.7, 4.4, and 7.5 cm, respectively. The density values of atypically located pseudocysts did not differ significantly from those of intra/parapancreatic pseudocysts. The natural pathways along which atypically located pseudocysts develop primarily are the hepatoduodenal, gastrohepatic, and gastrosplenic ligaments.

Acute Disease↗
PubMed1993

Hypervascular liver lesions: differentiation of focal nodular hyperplasia from malignant tumors with dynamic gadolinium-enhanced MR imaging.

The differentiating points between focal nodular hyperplasia (FNH) and malignant hypervascular liver lesions were studied at dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Thirty-six patients with 50 hypervascular lesions (28 FNH, 12 hepatocellular carcinoma, nine metastases, and one cholangiocarcinoma) underwent unenhanced spin-echo (SE) T1- and T2-weighted imaging and T1-weighted gradient-recalled-echo imaging before and repeatedly for 10 minutes after intravenous bolus injection of gadopentetate dimeglumine. On unenhanced SE images, the signal intensity of 25 FNH lesions (89%) and 10 malignant tumors (45%) was homogeneous. A central scar was detected in 12 FNH lesions (43%) and in none of the malignant tumors. On dynamic gadolinium-enhanced images, all lesions had early vigorous enhancement that was homogeneous in 27 FNH lesions (96%) and in seven malignant tumors (32%) (P < .001). After administration of gadopentetate dimeglumine, central scars were seen in 22 FNH lesions (79%) and in one malignant tumor (4%) (P < .001). All FNH lesions (100%) and six malignant tumors (27%) had well-defined enhancement (P < .001). There was overlap in the enhancement pattern between hypervascular malignant lesions and FNH, but by using the combination of unenhanced and enhanced images, they could be distinguished.

Adult↗
PubMed1993

Interstitial MR lymphography with iron oxide particles: results in tumor-free and VX2 tumor-bearing rabbits.

OBJECTIVE: MR lymphography with interstitial injection of superparamagnetic iron oxide particles was optimized in normal rabbits by investigating the pattern of signal reduction in lymph nodes as a function of dose and time after administration. The optimized examination procedure was then used in a rabbit tumor model to study the potential of superparamagnetic iron oxide--enhanced MR lymphography in the detection of metastatic lymph node involvement. MATERIALS AND METHODS: The popliteal and iliac lymph nodes of 18 normal rabbits were imaged to study the dose response and time course of the effect of the contrast agent. For the dose response study, six doses of 2-50 mumol of iron per extremity were administered to three animals per dose, and MR images were obtained before and 12 hr after administration. For the time course study, 20 mumol of iron per extremity was administered to four animals, and images were obtained before and 6 hr to 42 days after administration. VX2 tumor-bearing rabbits were examined 12 hr after administration of 20 mumol (10 animals) and 50 mumol (three animals) of iron per extremity. Superparamagnetic iron oxide was injected into the foot pad of the hind limb. T1-, T2-, and proton density-weighted MR images were obtained with a 1.5-T unit. RESULTS: In normal rabbits, a profound and homogeneous loss of signal intensity was found with doses of 2-5 mumol of iron per extremity in popliteal lymph nodes and with doses of 20-30 mumol in the iliac lymph nodes. Superparamagnetic iron oxide caused maximal loss of signal intensity in both popliteal and iliac lymph nodes 12 hr after administration. In tumor-bearing rabbits, different degrees of metastatic displacement of lymph nodes were discernible, and even small metastases (3 mm in diameter) could be visualized when using the optimized examination protocol and the proton density-weighted spin-echo sequence. CONCLUSION: We conclude that interstitial MR lymphography with superparamagnetic iron oxide enables the detection of lymph node metastases and therefore is a promising technique for improved diagnostic imaging of lymph nodes in the staging of tumors.

Animals↗
PubMed1993

If you could feel what I feel. Learning to care for the elderly.

It's a familiar scene for any EMS responder who has transported nursing home residents. The room is filled with people apparently suffering the various afflictions of time: those with problems hearing, seeing, walking, feeding and expressing themselves, and performing the simple, everyday tasks younger people ordinarily do without conscious effort. Some people are in wheelchairs. Others hobble about on canes or crutches.

Aged↗
PubMed1993

MR lymphography using iron oxide particles. Detection of lymph node metastases in the VX2 rabbit tumor model.

MR images of the iliac lymph nodes of 25 VX2 carcinoma-bearing rabbits and of 5 tumor-free rabbits were obtained at 1.5 T before and after endolymphatic administration of superparamagnetic iron oxide particles (SPIO) at a dose of 1 mumol Fe per extremity. Imaging results were correlated with histology. In unenhanced images intranodal metastases were not detectable with any of the pulse sequences used and the signal intensities of tumor-free and metastatic lymph nodes did not differ significantly. After administration of the contrast medium, a significant signal loss (p < or = 0.05) occurred in the healthy lymph node tissue, whereas the signal intensity of lymph node metastases remained unchanged. In SPIO enhanced images, the threshold size for detection of lymph node metastases was 2 mm. Metastatic involvement was detected in 28 of the 30 tumorous lymph nodes with the SE 2000/15 sequence but in a smaller number of lymph nodes with the sequences SE 500/22 (n = 27) and 2000/65 (n = 21).

Animals↗