Search PubMed⌕ Search

Biomedical subjects

B Hamm

Publications and source records attributed to B Hamm.

265 records · Page 15Linked to original sources
PubMedDate not supplied

The value of hyoscine butylbromide in abdominal MR imaging with and without oral magnetic particles.

PURPOSE: The purpose of this article was to assess the impact of intravenous (IV) anticholinergic hyoscine butylbromide in abdominal magnetic resonance (MR) imaging with oral magnetic particles (OMP) [ABDOS-CAN, Ferristene (USAN), Nycomed Imaging AS, Oslo, Norway]. MATERIALS AND METHODS: In 31 patients with abdominal tumors, T1-weighted spin-echo (SE) images (SE 600/ 15; 1.5 T) were obtained without and with IV hyoscine butylbromide (20 mg) before and after administration of 800 ml of OMP. Two blinded readers assessed motion artifacts, bowel-wall visualization, and lesion delineation on the four sets of T1-weighted images. The two-tailed Wilcoxon paired sample test was used for statistical analysis (p < .05). RESULTS: Hyoscine butylbromide reduced motion artifacts and improved bowel-wall visualization on precontrast and OMP-enhanced images at a statistically significant level (p = 0.0006-0.037). The lowest degree of artifacts was recorded on OMP images with hyoscine butylbromide. OMP with hyoscine butylbromide significantly improved lesion delineation compared to studies without antiperistaltic drug before (p = 0.019) and after OMP administration (p = 0.01). CONCLUSIONS: The authors conclude that the use of IV hyoscine butylbromide is recommended for OMP-enhanced abdominal MR imaging with T1-weighted SE pulse sequences at 1.5 T.

Abdominal Neoplasms↗
PubMedDate not supplied

Comparison of in-phase and out-of-phase gradient recalled echo T1-weighted pulse sequence for MR imaging of malignant liver masses following administration of paramagnetic gadolinium-chelate.

BACKGROUND: The purpose of this study was to compare the performance of in-phase and out-of-phase gradient recalled echo (GRE) pulse sequences on paramagnetic contrast-enhanced magnetic resonance (MR) imaging of malignant liver lesions. METHODS: Fifty patients (27 women, 23 men; mean age = 50 +/- 27 years) with known or suspected focal liver lesions, nine of whom had a fatty liver, were examined at 1.5 T before and 60 min after injection of gadobenate dimeglumine at a dose of 0.05 or 0.1 mmol/kg using two GRE techniques: echo time of 2.3 ms (out-of-phase) or 4.6 ms (in-phase). Liver signal-to-noise ratio (SNR) and lesion-liver contrast-to-noise ratio (CNR) were calculated. RESULTS: In patients with a nonfatty liver, liver SNR increased from 26 +/- 9 to 41 +/- 17 on in-phase images and from 28 +/- 8 to 45 +/- 14 on out-of-phase images. In patients with a fatty liver, in-phase images provided significantly higher (p < 0.01) liver SNR than did out-of-phase images predose (34 +/- 8 on in-phase vs. 21 +/- 8 on out-of-phase) and postdose (44 +/- 13 on in-phase vs. 33 +/- 14 on out-of-phase). In patients with a nonfatty liver, lesion-liver CNR was similar on in-phase and out-of-phase images, predose and postdose. In patients with fatty liver, lesion-liver CNR was significantly (p < 0.01) lower on out-of-phase images on predose and postdose images. CONCLUSION: In-phase GRE imaging is recommended for imaging focal liver lesions on paramagnetic contrast-enhanced MR imaging in patients with fatty infiltration of the liver.

Adult↗
PubMedDate not supplied

Low-field MRI for assessing synovitis in patients with rheumatoid arthritis. Impact of Gd-DTPA dose on synovitis scoring.

OBJECTIVE: To investigate the impact of a double dose compared to a single dose of contrast material in low-field magnetic resonance imaging (MRI) on semi-quantitative scoring of synovitis in patients with rheumatoid arthritis (RA). METHODS: This prospective study included 38 RA patients (23 women and 15 men, mean age 51 years). All patients underwent low-field MRI of the hand before administration of contrast medium, after intravenous injection of 0.1 mmol/kg gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA), and after another dose of 0.1 mmol/kg Gd-DTPA. Two readers (A and B) blinded to dosage independently scored the single dose and double dose image sets for synovitis according to outcome measures in rheumatology (OMERACT) recommendations. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were also calculated for each set. RESULTS: 149 metacarpophalangeal (MCP) joints were evaluated. There was good inter-reader agreement for each of the two sets (intra-class correlation coefficient of 0.75 for the single dose set and 0.83 for the double dose). Median CNR and SNR values were 5.4 and 15.9, respectively, for the single dose set and 8.5 and 16.6, respectively, for the double dose set (p<0.0001). Single dose set mean synovitis scores were 1.7 and 1.6 for readers A and B, respectively. Double dose set scores were 1.9 and 2.0, respectively. Thus, higher synovitis scores were recorded for the double dose sets than the single dose sets (p<0.005). CONCLUSION: In low-field MRI, when evaluating RA, the dose of the contrast material influences synovitis scoring. Therefore, dosage of contrast material should be taken into consideration when using extremity dedicated low-field MRI.

Adolescent↗
PubMedDate not supplied

Differentiation of hepatic hemangiomas from metastases by dynamic contrast-enhanced MR imaging.

Twenty-nine patients with hepatic hemangiomas (n = 14) and hepatic metastases (n = 15) underwent magnetic resonance (MR) imaging prior to and after an intravenous bolus injection of Gd-diethylenetriamine pentaacetic acid (0.2 mmol/kg). Before contrast application, a T2-weighted spin echo sequence (SE 1,600/105) and a T1-weighted gradient echo sequence (GE 315/14/90 degrees pulse angle) were performed. Beginning with injection of the contrast agent, a dynamic study was conducted for 10 min using a moderately T1-weighted gradient echo sequence (GE 40/14/40 degrees) with an acquisition time of 10.2 s per image. Delayed (11 min) and late (60 min) postcontrast images were obtained using a T1-weighted sequence (GE 315/14/90 degrees). In the dynamic study (0-10 min) the hemangiomas were characterized by peripheral contrast enhancement and a subsequent hyperintense fill-in. The metastases showed very mixed patterns of enhancement after contrast administration, and their signal intensity remained low compared with that of the hepatic tissue. In the delayed postcontrast examination (11 min) the hemangiomas had a very high and homogeneous signal intensity and the metastases were characterized by an inhomogeneous, hypointense to isointense signal. The contrast between tumor and liver [signal-difference-to-noise ratio (SD/N)] was higher for all hemangiomas than it was for the metastases. In the T2-weighted precontrast examination, on the other hand, five hemangiomas and seven metastases showed an overlap in the SD/N. The late postcontrast images (60 min) did not yield any further diagnostic information. We conclude that the combination of a dynamic MR study with delayed postcontrast T1-weighted imaging is a useful method of diagnosing hepatic hemangiomas.

Adult↗
PubMedDate not supplied

CT-guided intraarticular corticosteroid injection into the sacroiliac joints in patients with spondyloarthropathy: indication and follow-up with contrast-enhanced MRI.

PURPOSE: Our goal was to prospectively study the therapeutic efficacy of CT-guided intraarticular corticosteroid instillation of inflamed sacroiliac joints (SIJs) in patients with spondyloarthropathies and to evaluate the role of MRI as a procedure for establishing the indication and for therapeutic follow-up. METHOD: A total of 103 CT-guided corticosteroid injections of the SIJs were performed in 66 patients with inflammatory back pain (IBP): 37 bilateral, 29 unilateral. All patients did not respond to an immediately preceding 4 week nonsteroidal antiinflammatory therapy. Forty milligrams of a crystalline long-acting corticoid was instilled in each joint. All 66 patients underwent continuous clinical follow-up at 10 to 12 week intervals after corticosteroid injection to a maximum of 18 months. The degree of subjective complaints before and after the intervention was recorded using a analogue scale (0 = no pain, 10 = unbearable pain). Dynamic contrast-enhanced (Gd-DTPA, 0.1 mmol/kg body wt) MRI with quantitative determination of contrast enhancement was performed in all patients before the therapeutic intervention and in 38 patients at 8 +/- 4 months. RESULTS: Sixty-one of the 66 study patients (92.5%) showed a statistically significant abatement of subjective complaints from 8.8 +/- 1.3 to 3.3 +/- 2.3 (p < 0.01) at 1.7 +/- 1.1 weeks after intervention, and this improvement lasted for 10 +/- 5 months. The percentage contrast enhancement at dynamic MRI likewise showed a significant reduction from 100.3 +/- 48% before to 44.3 +/- 36.1% after intraarticular cortisone administration (p < 0.01). CONCLUSION: CT-guided intraarticular corticosteroid instillation in the SIJs may be regarded as an effective therapy for florid sacroiliitis. The severity of inflammation and the response to therapy can be determined quantitatively by dynamic MRI.

Adult↗
PubMedDate not supplied

Dynamic and quantitative assessment of tracheomalacia by electron beam tomography: correlation with clinical symptoms and bronchoscopy.

PURPOSE: The purpose of this study was to evaluate the performance of electron beam tomography (EBT) in the dynamic and quantitative assessment of tracheal collapse in tracheomalacia. METHOD: Eight patients with suspected tracheomalacia were evaluated by EBT, and the results were correlated with both clinical symptoms and bronchoscopy. To validate this technique, an EBT phantom study preceded the patients' examination. A dynamic imaging sequence consisting of 20 50-ms scans obtained at 0.5 s intervals during a 10 s period was performed while the patient followed an instructed breathing maneuver. RESULTS: Good correlation between EBT data and clinical symptoms was found in all patients. In comparison to bronchoscopic findings, EBT results correlated well in three, showed limited correlation in three patients, and no correlation in one case. CONCLUSION: EBT with its short scanning time may be regarded as an accurate noninvasive method to dynamically evaluate tracheomalacia.

Adult↗
PubMedDate not supplied

Rib artifacts in electron beam tomography: incidence and severity without and with the cone beam reconstruction algorithm.

Electron beam tomography (EBT) may be compromised by rib artifacts. Two hundred forty-seven abdominal studies were performed without (Group A, n = 222) or with (Group B, n = 25) the cone beam algorithm. One hundred eighty-six (83.8%) and nine (36%) studies of Groups A and B, respectively, displayed some level of artifact. In Groups A and B, major, minor, and no artifacts were found in 115 (51.5%) and 0 (0%), 71 (32.3%) and 9 (36%), and 36 (16.2%) and 16 (64%) patients, respectively (p < 0.01). The cone beam algorithm improves EBT studies of the abdomen.

Algorithms↗
PubMedDate not supplied

How to increase the motility of spermatozoa from the epididymis of bulls and alloplastic spermatoceles in minipigs.

The motility of spermatozoa from the head and tail of the epididymis in bulls was studied. Qualitatively and quantitatively, the motility of spermatozoa from the cauda was distinctly better than that from the caput. It was possible to achieve a highly significant increase in the motility of epididymal spermatozoa from the caput as well as the cauda area using caffeine or a caffeine-kallikrein mixture. Above all, motility stimulants improved the local motility of the epididymal spermatozoa as compared to twitching and progressive motility. The motility of caudal spermatozoa was increased by 100%, corresponding to local movement of 59% of the total number of sperm cells. It was possible to demonstrate an increase in the almost totally absent motility of the caput spermatozoa to 27% local motility. Application of kallikrein without addition of kininogens led to no significant change in spermatozoa motility. By the addition of caffeine, it was possible to increase the motility of minipig epididymal spermatozoa taken by puncture from alloplastic spermatoceles significantly. In 23 aspirates, a prompt increase in the percentage of locally motile "spermatocele spermatozoa" from 12% to 23.5% was observed.

Animals↗
PubMedDate not supplied

Sonography of the testis and epididymis.

Sonography (ultrasound) is the mainstay for imaging morphologic abnormalities of the scrotum and testis. It is used primarily for determining the location and nature of palpable lesions and to demonstrate clinically occult, non-palpable lesions. This article describes the state of the art of scrotal sonography. After an initial presentation of the normal sonographic appearance of the testis and epididymis, the diagnostic evaluation of the most common scrotal disorders is described. Scrotal sonography 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 sonography is limited in determining whether a focal testicular lesion is benign or malignant. Unsatisfactory results are obtained by conventional sonography in the evaluation of testicular torsion. This gap in the diagnosis of scrotal pathologies is now being reliably filled by colour-coded duplex sonography.

Adult↗
PubMedDate not supplied

High-resolution dynamic MR imaging of hepatocellular carcinoma with a phased-array body coil.

High spatial resolution dynamic magnetic resonance (MR) imaging performed with a phased-array body coil is a useful tool for evaluating hepatocellular carcinoma. The examination consists of fast spin-echo T1- and T2-weighted images obtained in a single breath hold; multisection, dynamic, fast gradient-echo images obtained in a single breath hold; and contrast material-enhanced images obtained in the arterial-dominant and delayed phases. Hepatocellular carcinoma, with its predominantly arterial blood supply, usually appears hyperintense on arterial-dominant phase images and isointense or hypointense relative to liver parenchyma on delayed-phase images. Hepatocellular carcinomas, especially those larger than 1.5 cm, contain a fibrous capsule or an inner septum, which allows them to be differentiated from other tumors. These characteristics are particularly important in the diagnosis of hypovascular hepatocellular carcinomas, which do not have an arterial blood supply and thus do not enhance. Extracapsular invasion, a relatively common finding in advanced cases, is seen as a nodular enhancing area that projects into the surrounding liver parenchyma adjacent to the main tumor on arterial-dominant phase images and as an iso- or hypointense area on delayed-phase images. Portal vein invasion appears as an obstruction of the vein, and portal vein tumor thrombi appear as intermediate-signal-intensity masses. The technique can also be helpful in the follow-up of treatment.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Use of contrast enhanced magnetic resonance imaging to detect spinal inflammation in patients with spondyloarthritides.

Inflammation of spinal structures is a characteristic feature of the spondyloarthritides (SpA). The term SpA covers patients with inflammatory back pain and/or peripheral arthritis who can be further categorized. Ankylosing spondylitis (AS), the prototype of the SpA, the most frequent inflammatory spinal disease in adults, usually starts in the sacroiliac joints. Pathologic spinal changes occurring in AS are spondylitis, spondylodiscitis and inflammation and ankylosis also at other sites in the axial skeleton. In the later stages of AS such changes can be well recognized by spinal x-rays. In the early disease stages it has been more difficult to analyze the exact anatomic localization of spinal inflammation to date, because conventional imaging systems have only a limited capacity to demonstrate such changes early. There is some evidence that magnetic resonance imaging (MRI) with fat saturation and contrast enhanced MRI are useful to visualize early and late inflammatory changes in the sacroiliac joints. In this paper we report that MRI is also useful to localize the site of inflammation to distinct regions of the spine in AS and other SpA.

Adult↗