Biomedical subjects

B Hamm

Publications and source records attributed to B Hamm.

At least 127 records · Page 7Linked to original sources

PubMed1999

Clinical utility and safety of MultiHance in magnetic resonance imaging of liver cancer: results of multicenter studies in Europe and the USA.

MultiHance (gadobenate dimeglumine; Gd-BOPTA, Bracco SpA, Milano, Italy) is a novel gadolinium-based contrast agent which has recently been made commercially available in Europe for magnetic resonance imaging of the liver. It combines the properties of a conventional extracellular fluid contrast agent with those of a liver-specific agent and has been shown in numerous clinical trials to improve the impact of magnetic resonance imaging for both the detection and characterization of focal liver masses. The present article briefly summarizes the safety and efficacy results of Phase I, II and III clinical studies carried out in almost 800 patient and non-patient volunteers in both Europe and the USA.

Carcinoma, Hepatocellular↗

PubMed1999

Ferric ammonium citrate as a positive bowel contrast agent for MR imaging of the upper abdomen. Safety and diagnostic efficacy.

PURPOSE: To evaluate the safety and diagnostic efficacy of two different doses of ferric ammonium citrate as a paramagnetic oral contrast agent for MR imaging of the upper abdomen. MATERIAL AND METHODS: Ninety-nine adult patients referred for MR imaging for a known or suspected upper abdominal pathology were included in this randomized multicenter double-blind clinical trial. Imaging was performed with spin-echo (T1- and T2-weighted) and gradient-echo (T1-weighted) techniques before and after administration of either 1200 mg or 2400 mg of ferric ammonium citrate dissolved in 600 ml of water. Safety analysis included monitoring of vital signs, assessment of adverse events, and laboratory testing. Efficacy with regard to organ distension, contrast distribution, bowel enhancement and delineation of adjacent structures was graded qualitatively. RESULTS: No serious adverse events were reported for either of the two concentrations. A total of 31 minor side effects were noted, of which significantly more occurred in the higher dose group (p<0.01). The diagnostic confidence in defining or excluding disease was graded as better after contrast administration for 48% of all images. Marked or moderate enhancement of the upper gastrointestinal tract was achieved at both doses in 69.5% of cases with no evident difference between the two doses. The higher dose tended to show better results in terms of the contrast assessment parameters. CONCLUSION: Ferric ammonium citrate is a safe and effective oral contrast agent for MR imaging of the upper abdomen at two different dose levels. The higher dose showed a tendency toward better imaging results while the lower dose caused significantly fewer side effects. Therefore the 1200 mg dose can be recommended in view of the risk-to-benefit ratio.

Abdomen↗

PubMed1999

Safety of implantable coronary stents during 1H-magnetic resonance imaging at 1.0 and 1.5 T.

The safety of most available implantable intracoronary stents during magnetic resonance imaging (MRI) has not been sufficiently tested. Minor, but possibly clinically significant, increases in temperature have not been excluded. We measured temperature changes of 14 different stents clinically in use or currently tested for release on the world market. Stents were examined in 1.0- and 1.5-T MR scanners with multiple sequences used in routine cardiac and thoracic MRI examinations ("clinical worst case") and after implantation of the stents into the coronary arteries of excised pig hearts (1.5-T scanner only). We used a highly sensitive infrared camera with a thermal resolution of 10 mK and did not see significant heating of any stent during the examinations. We conclude that MRI is safe in patients with the currently available intracoronary stents.

Animals↗

PubMed1998

Static magnetic resonance imaging of the pelvic floor muscle morphology in women with stress urinary incontinence and pelvic prolapse.

In a study, the magnetic resonance imaging (MRI) findings of 69 women were analyzed to define the typical MRI appearance of the pelvic floor musculature in healthy subjects (n = 20) and women with urinary incontinence (UI) and/or genitourinary prolapse (GP) (n = 49). The following parameters were determined: thickness and signal intensity of the levator muscles on each side, distance between the urethra and symphysis, diameter of the proximal urethra, and thickness and configuration of the anterior vaginal wall. These parameters were correlated with the patients' age and parity, urodynamic parameters, and the clinical assessment of the pelvic floor. In contrast to healthy subjects, the frequent findings in women with UI and/or GP are higher signal intensity of the levator muscles (p < 0.05) and loss of the hammock-like configuration of the vagina (p < 0.01). On static MRI, the morphometry of the levator musculature identified no findings typical of either UI or GP. Analysis of MRI combined with patients' parity suggests that the severity of damage to the pelvic floor at delivery is determined by the traumatic event as such and not by the number of deliveries. Urethral diameter, distance of the symphysis to the urethra, and vaginal wall thickness cannot distinguish between controls and women with UI and/or GP. Urodynamic and functional clinical parameters do not correlate with the changes in the pelvic floor musculature demonstrated by static MRI. Although morphological changes in UI and/or GP can be demonstrated by MRI, they can be assigned a pathogenic role only if clinical symptoms are present.

Adolescent↗

PubMed1998

[Thoracic diagnosis with electron-beam computed tomography].

The electron beam computed tomography (EBCT) is characterised by an up to 10-fold increased speed in comparison to a spiral CT scanner. Although originally designed for diagnosing the heart, some indications in the chest and for the vessels have also become well established. In the forefront exists the possibility to exam a large volume with a small slice thickness in a short time period without having to sacrifice on important features of spiral CT scanning. During one breathhold, the thorax can be continually examined with 1.5 mm slice thickness, which means that indications for high-resolution (HR-) CT, spiral-CT and for virtual bronchoscopy can be combined into one examination. Beyond the artefact-reduced images, the EBCT presents image data which, following image processing (sliding MIPs, coronal reconstructions), allow recognition of a new horizon in thoracic diagnostics.

Aged↗

PubMed1998

Use of contrast-enhanced MR imaging to detect sacroiliitis in children.

PURPOSE: To verify the diagnostic value of contrast-enhanced MR imaging compared with conventional radiography in the diagnosis of sacroiliitis in children. DESIGN AND PATIENTS: Radiography and MR imaging of the sacroiliac joints were performed in 185 children subdivided into the following groups according to the modified European Spondyloarthropathy (SpA) Study Group (ESSG) criteria: group 1, undifferentiated spondyloarthropathy (uSpA) (n=53, 94.5% HLA-B27+); group 2, differentiated SpA (n=45, 93.3% HLA-B27+); group 3, patients with no signs of SpA other than oligoarthritis (n=39, 92.3% HLA-B27+); group 4, HLA-B27+ controls with various other non-SpA diagnoses (n=22); and group 5, HLA-B27-controls with various other non-SpA diagnoses (n=26). Radiographs were evaluated on the basis of the modified New York criteria independently by three experienced radiologists masked to the clinical data. In a second step, the same radiologists independently evaluated the MR images without knowledge of the clinical data and radiographic findings using the recently published criteria developed by our group. These criteria allow differentiation of acute and chronic inflammatory changes. RESULTS: Radiography demonstrated sacroiliitis in 18 patients: 4 of 53 in group 1 (7.5%), 14 of 45 in group 2 (31%), but none in groups 3, 4 and 5. In contrast, MR imaging demonstrated acute and/or chronic sacroiliitis in 44 patients: 18 of 53 in group 1 (34%), 21 of 45 in group 2 (46.7%) and 5 of 39 in group 3 (12.8%), but none in groups 4 and 5. The percentage of sacroiliitis detected by MR imaging was significantly higher than that detected by radiography (P<0.001). CONCLUSION: Contrast-enhanced MR imaging is a useful method for detecting sacroiliitis in children. Advantages of contrast-enhanced MR imaging compared with conventional radiography are a higher sensitivity due to the ability to document early and acute changes and the absence of radiation exposure.

Adolescent↗

PubMed1998

Virtual endoscopy of the small bowel: phantom study and preliminary clinical results.

The purpose of this study was to determine the optimal scanning technique for lesion detection in a small bowel phantom and to evaluate the virtual endoscopy (VE) technique in patients. A small bowel phantom with a fold thickness of 7 mm and length of 115 cm was prepared with nine round lesions (3 x 1 mm, 2 x 2 mm, 2 x 3 mm, 2 x 4 mm). Spiral CT parameters were 7/7/4, 3/5/2, 3/5/1, 1.5/3/1 (slice thickness/table feed/reconstruction interval). VE was done using volume rendering technique with 1 cm distance between images and 120 degrees viewing angle. Two masked readers were asked to determine the number and location of the lesions. Seven patients underwent an abdominal CT during one breathhold after placement of a duodenal tube and filling of the small bowel with methyl cellulose contrast solution. VE images were compared with the axial slices with respect to detectability of pathology. With the 7/7/4 protocol only the 4-mm lesions were visualised with fuzzy contours. The 3/5/2 protocol showed both 4-mm lesions, one 3-mm lesion and one false positive lesion. The 3/5/1 protocol showed both 4-mm and both 3-mm (one uncertain) lesions with improved sharpness, and no false positive lesions. One 2-mm and one 1-mm lesion were additionally seen with the 1.5/3/1 protocol. Path definition was difficult in sharp turns or kinks in the lumen. In all patients, no difference was found between VE and axial slices for bowel pathology; however, axial slices showed 'outside' information that was not included in VE. We conclude that the 3/5/2 protocol may be regarded as an optimal compromise between lesion detection, coverage during one breathhold, and number of reconstructed images in patients; round lesions of 4 mm in diameter can be detected with high certainty.

Adult↗

PubMed1998

Virtual endoscopy of the nose and paranasal sinuses.

The purpose of this study was to evaluate the applicability of virtual endoscopy (VE) in the region of the nose and paranasal sinuses on the basis of volume-rendered spiral CT data. Forty-five patients underwent a low-dose spiral CT of the sinuses. The data were transferred to a workstation running software for volume rendering (EasyVision, Philips Medical Systems, Eindhoven, The Netherlands). Six orthogonal views of the maxillary sinuses and the nasopharynx and a fly-through movie of the nose were calculated. Two radiologists evaluated the coronal reconstructions and virtual endoscopy with respect to detectability of pathology using a checklist comprising 10 points. In 30 patients who underwent subsequent endoscopic surgery, surgeons were asked to rank the degree of assistance of the preoperative virtual endoscopy. In general, virtual endoscopy was possible in all 45 patients. The mean time required for path definition and movie calculation for virtual endoscopy were 8 (+/- 2) min and 3 (+/- 1) min, respectively. Overall, more anatomical details were depicted on coronal reconstructions; however, a high degree of similarity between virtual endoscopy and the intraoperative impression was reported by the surgeons. We conclude that virtual endoscopy of the nose and paranasal sinuses may develop into a standard means to guide surgeons during endoscopic interventions.

Adolescent↗

PubMed1998

Low-dose spiral computed tomography for measuring abdominal fat volume and distribution in a clinical setting.

OBJECTIVES: Computed tomography (CT) has been used to measure body composition, however, a technique with reduced radiation exposure has not yet been introduced. This study tested a low-dose spiral CT technique on a phantom to determine its validity and reproducibility. The method was then applied for volume and distribution measurements in patients. DESIGN: Construction and measurement of a phantom followed by measurement of patients referred to CT for clinical indications. SETTING: Radiology Department, University Hospital. SUBJECTS: Twenty-four post-gastrectomy patients. INTERVENTION: A 22 cm phantom with a known amount of water and fat was scanned using high- and low-dose technique, standard and double table speed during a volumetric scan. The low-dose technique was implemented in the patient group. Total volume, total fat and four defined compartmental fat volumes in the truncal area were measured. RESULTS: The mean fat volume measured using the low-dose CT technique in the phantom was 0.2% above the actual fat content. The coefficient of variation for this method was 5%. By using low-dose, double speed instead of standard-dose technique, radiation exposure to the skin was decreased by more than 90% (equivalent to 4 mGy) of what is used in diagnostic imaging. The patient scans showed that no significant differences in BMI and total measured volume existed between female and male patients, but percent fat and percent subcutaneous fat were significantly larger in women (P = 0.006 and 0.002, respectively), as were percent intraabdominal and mediastinal fat in men (P = 0.002 and 0.003 respectively). CONCLUSIONS: Low-dose spiral CT accurately measures fat volume in vitro, and can be used in vivo for compartmental fat measurements.

Abdomen↗

PubMed1998

[Automated mammary sonography and mammography: the differentiation of benign and malignant breast lesions].

PURPOSE: A prospective study on the differentiation of breast lesions was carried out using experimental combination schemes of mammography and automatic sonography. MATERIALS AND METHODS: X-ray mammograms and a B image from automatic sonography of 39 malignant and 41 benign lesions as well as 40 cases without lesions were separately examined by four experienced diagnosticians. The observers differentiated the findings mammographically and by measurement in the B images. RESULTS: For two examiners the combination of mammography and automatic sonography gave with regard to the differentiation of breast lesions an improvement in sensitivity of 3 or 5% and in specificity of 31 and 18%, respectively, as compared to mammography alone while for the other two examiners an improved specificity of 21 and 36%, respectively, was accompanied by an 8 and 10% decrease in sensitivity as compared to mammography alone. CONCLUSIONS: The differentiating criteria from automatic sonography and mammography can, in principle, be used to evaluate the dignity of breast lesions. However, an optimization is necessary since the improvement in specificity does not compensate the loss in sensitivity.

Adult↗

PubMed1998

[Pneumocysts juxta-articular to the ilial bone and the sacral bone].

PURPOSE: The purpose of the study was to detect and safely diagnose pneumatocysts by means of computed tomography. METHODS: From September 1995 to May 1996 computed tomography of the pelvis was performed in six patients for various indications. A slice thickness of 8 mm was employed for all studies. One patient had undergone surgery for hyperparathyroidism nine years previously. Attenuation values within the coincidentally diagnosed pneumatocysts were obtained. RESULTS: We found a total of 14 pneumatocysts juxtaarticular to the sacroiliac joint. Three patients demonstrated a bilateral intraarticular vacuum phenomenon, yet a joint communication was not found. The lesions did not coincide with inflammation, tumour or trauma. CONCLUSION: Pneumatocysts are benign bone lesions associated with arthrotic changes of the sacroiliac joint. Computed tomography is the modality of choice for the diagnosis of pneumatocysts.

Aged↗

PubMed1998

[Combination of mammography with automated ultrasound (Sono-X) in routine diagnosis?].

A new technique for breast imaging is presented. This technique combines radiographic mammography directly with automated ultrasound. The combined examination, which is performed without decompression of the breast, yields the conventional mammography films as well as a complete set of B-mode scans and ultrasound projections. These can be geometrically matched with each other in a definitive manner. A prototype of the device was first used in a pilot study of 50 patients followed by a study of an additional 450 patients with a total of 492 breast lesions, of which 269 were confirmed by histology or cytology. The results show that X-ray and ultrasound are complementary in the detection of cancer. The use of an experimental mode of image interpretation for combined mammography and automated ultrasound reduced the number of mammographically suspicious findings that ultimately turned out to be benign. These results were also confirmed in two blind studies including a total of 160 histologically or cytologically confirmed lesions and 40 cases without lesions. With further technical advancement of the technique aimed at rapid and easy application and confirmation of the results obtained so far, the combination of mammography and automated ultrasound might be introduced into a routine clinical setting.

Breast↗

PubMed1998

[The ABBI system as a possibility for evaluating non-palpable lesions].

For non-palpable lesions detected radiographically alone, lumpectomy after needle-localization is currently performed. Specimen radiography provides an indirect proof of complete excision of the mammographic abnormality. Up to now, intraoperative mammography of the operated breast has not been possible. Digital intraoperative mammography is now possible with the ABBI-system, which will be introduced in this article. In a pilot study, we have investigated, whether it is possible to excise small carcinomas with the ABBI stereotactic biopsy device (maximum diameter 20 mm) without compromising breast conserving therapy. In a prospective study, 69 patients were diagnosed or treated using the ABBI-system. In all 60 patients with a primary lesion, a cylindrical excision was performed. Of these, 11 invasive and 5 intraductal carcinomas were diagnosed. 7 of the invasive and 2 of the intraductal cancers were treated with breast conserving surgery. In 9 cases, an in-breast recurrence was suspected. In 7 of these a cylindrical excision was performed. One invasive and 3 intraductal carcinomas were found and mastectomy was performed in these four patients. In two patients with the suspicion of an in-breast recurrence, the ABBI-system was used to perform a core-needle biopsy. In one patient, the biopsy finding was positive and mastectomy was performed. Patients with lesions close to the chest wall are not suited for the ABBI-system. The postoperative course was uneventful in all cases, the cosmetic result after breast-conserving therapy was very good. The advantages of this new method consist in the reliable stereotactic localization of suspicious lesions and in the fast intraoperative imaging.

Biopsy, Needle↗

PubMed1998

Use of dynamic magnetic resonance imaging to detect sacroiliitis in HLA-B27 positive and negative children with juvenile arthritides.

OBJECTIVE: Involvement of the sacroiliac (SI) joints is a hallmark of the spondyloarthropathies (SpA), especially, in early and later stages of ankylosing spondylitis in adults. The significance of sacroiliitis in juvenile SpA is less clear and the diagnosis of juvenile SpA is difficult due to the mostly nonspecific or absent history of back pain in children and the time delay associated with the diagnosis of sacroiliitis by conventional radiographs. Our aim was to evaluate dynamic magnetic resonance imaging (MRI) of the SI joints in children and to assess the frequency and the determinants of SI joint involvement in juvenile SpA and other juvenile arthritides. METHODS: Clinical examinations and dynamic MRI were performed in 130 children < 16 years of age with joint complaints, 100 with probable SpA, and 30 controls. The degree of back pain was assessed by a visual analog scale (VAS) (0 = no pain, 10 = very severe pain). The following groups were defined before MRI investigation according to modified European Spondylarthropathy Study Group (ESSG) criteria for SpA: Group 1: undifferentiated SpA (uSpA, n = 41, 88% B27+); Group 2: differentiated SpA (n = 29, 97% B27+), comprising reactive arthritis (n = 16), ankylosing spondylitis (n = 9), psoriatic arthritis (n = 3), and arthritis in inflammatory bowel disease (n = 1); Group 3: patients with no signs of SpA other than oligoarthritis, here named juvenile chronic arthritis (JCA) II (n = 30, 93% B27+); Group 4: HLA-B27+ controls without arthritis (n = 12); and Group 5: HLA-B27-controls with various other non-SpA diagnoses (n = 18). MRI was evaluated according to published criteria allowing for differentiation between acute and chronic changes in SI joints. RESULTS: Acute sacroiliitis without chronic changes could only be detected by dynamic MRI: in 17 patients (11 in Group 1, 3 in Group 2, 3 in Group 3) together in 14/70 (20%) patients with SpA. All these 17 patients had normal pelvic radiographs. Using MRI acute and/or chronic sacroiliitis were found in 35 patients: 17/41 in Group 1 (41%), 15/29 in Group 2 (52%), and 3/30 (10%) patients in Group 3, but in no patients in Groups 4 and 5. Chronic SI joint changes > grade 1 were detected by MRI in 18/70 patients with SpA (25.7%). In comparison, radiographic changes > grade 1 were less often detected in 14/70 patients with SpA (20%) or 23/210 SI joints examined (11 %), compared to 29/210 SI joints found in the MRI examinations (14%) (p = 0.05). Among the 70 patients with SpA, those with MRI diagnosis of acute sacroiliitis had a significantly longer disease duration (62+/-34 vs 28+/-16 months; p = 0.01) and higher C-reactive protein (12+/-12 vs 9+/-14; p = 0.01), and also reported more back pain on VAS (4.3+/-3.6 vs 1.2+/-2.2; p = 0.001) than those without sacroiliitis. CONCLUSION: Dynamic MRI and MRI are useful to detect acute and chronic sacroiliitis in children. The main advantages in comparison with conventional radiographs are the ability to detect acute changes in the SI joints, the higher sensitivity to detect chronic changes, and clearly, the lack of radiation exposure; while the disadvantages are the high costs and the duration of the procedure. Sacroiliitis is fairly common in juvenile SpA and seems to be associated with disease intensity and duration.

Adolescent↗

PubMed1998

[Stereotactic tumor biopsy and tumor excision].

Stereotactic procedures are indicated in nonpalpable breast lesions that are suspicious in mammography. Using the ABBI system all established procedures (stereotactic needle biopsy, fine needle biopsy, core needle biopsy) can be performed. Also the resection of cylindrical tissue specimen with a maximum diameter of 20 mm can be carried out, controlled by digital mammography. For the exact diagnosis of lesions with a diameter up to 15 mm, cylindrical extirpation is recommended. In several cases this can be considered as definitive lumpectomy. Neither lesions localized close to the thoracic wall nor retromamillary lesions can be treated by using the ABBI system. While digital mammography is the method of choice for the detection of microcalcifications, the visualization of opacifications may be difficult. Overall the ABBI system was used in 40.7% of our patients with nonpalpable breast lesions.

Biopsy, Needle↗

PubMed1997

Differential diagnosis of scrotal masses by ultrasound.

Ultrasound is the mainstay for imaging of the scrotum. It is used primarily for determining the location and nature of palpable lesions and to demonstrate nonpalpable lesions. Scrotal US is characterized by high sensitivity in the detection of intrascrotal abnormalities and is a very good mode for differentiating testicular from paratesticular lesions. However, scrotal US is limited in determining whether a focal testicular lesion is benign or malignant. The limitations of gray-scale US in the assessment of an acute scrotum and in particular of testicular torsion have now been overcome by color-coded duplex sonography and power Doppler.

Adolescent↗

PubMed1997

Colour-coded duplex sonography in the diagnostic assessment of vascular complications after kidney transplantation in children.

BACKGROUND: Vascular complications are a major cause of dysfunction or transplant loss in children. Arterial or venous occlusion, transplant renal artery stenosis (TRAS) and some arteriovenous (AV) fistula require rapid detection and prompt intervention. The present study was performed to determine the accuracy of colour Doppler sonography (CDS) in the early and late phase after renal transplantation and to correlate the results with angiographic and intraoperative findings. OBJECTIVE: CDS is the preferred imaging modality with a high diagnostic accuracy for follow-up of renal transplantation in children. The indication for angiography should be established on the basis of the CDS diagnosis. MATERIALS AND METHODS: In 87 children (mean age 10.9 years, range 2-17), 423 CDS examinations were performed after renal transplantation. Angiography was performed in 17 cases; surgery was necessary in 16 patients. RESULTS: CDS correctly identified 8/8 arterial or venous occlusions and 7/7 TRAS. The only false positive diagnosis of TRAS was due to misinterpretation of an iliac artery stenosis. Six AV fistulae were diagnosed by CDS. The overall positive predictive value of CDS was 94 % in this study. CONCLUSION: CDS is a noninvasive, non-radiation producing imaging modality with a high diagnostic accuracy. It is the method of choice in the assessment of vascular complications after renal transplantation in children.

Adolescent↗

PubMed1997

Normal morphology of sacroiliac joints in children: magnetic resonance studies related to age and sex.

OBJECTIVE: To determine in a prospective study the normal MRI morphology of the sacroiliac joints (SIJs) in relation to age and sex during adolescence. DESIGN AND PATIENTS: A total of 98 children (63 boys, mean age 12.7 +/- 2.8 years; 35 girls, mean age 13.7 +/- 2.3 years), ranging in age from 8 to 17 years, with juvenile chronic arthritis (JCA) but without signs of sacroiliitis fulfilled the study prerequisites (no back pain and no pathologic changes of the SIJs on physical examination before MRI in a 1.5-year follow-up). An additional eight HLA-B27-negative boys and eight HLA-B27-negative girls without arthritis served as controls. The MRI protocol comprised a T1-weighted SE sequence, an opposed-phase T2*-weighted GE sequence, and a dynamic contrast-enhanced study in single-section technique. RESULTS: Noncontrast MRI permitted differentiation of "open" from ossified segmental and lateral apophyses of the sacral wings, with a significant difference in age (P < 0.05) between children with open and ossified apophyses. Ossification of the apophyses of the sacral wings was seen significantly earlier (P < 0.05) in girls than in boys. Girls also had a significantly higher incidence of transitional lumbosacral vertebrae, pelvic asymmetries, and accessory joints. In the contrast-enhanced opposed-phase MRI study, normal cartilage of the SIJs showed no contrast enhancement whereas the joint capsule showed a moderate enhancement. CONCLUSION: There are significant age- and sex-related differences in the normal MRI morphology of juvenile SIJs. Our findings might serve as a standard of comparison for the evaluation of pathologic changes--in particular for the early identification of juvenile sacroiliitis.

Adolescent↗