Biomedical subjects

Mathias Cohnen

Publications and source records attributed to Mathias Cohnen.

3 recordsLinked to original sources

PubMed2003

A rapid and reliable semiautomated method for measurement of total abdominal fat volumes using magnetic resonance imaging.

The aim of this study was the development of a reliable and fast method to estimate total abdominal fat volumes (TAF) in diabetic subjects on the basis of T1-weighted MR images. Thirty-seven patients with diabetes were examined (age 48 +/- 13 y mean +/- SD). A semiautomated computer assisted software program was developed to quantify intraabdominal (IAF), subcutaneous (SCF), and total abdominal fat volumes (TAF). The variability of image analysis for fat measurements between two observers and within observers was assessed. Mean volumes (+/- SD) for IAF, SCF and TAF were 10.5 1 (+/- 5.0 1), 15.1 1 (+/-7.3 1) and 25.7 1 (+/-11.5 1), respectively. Inter- and intraobserver reliability was excellent (r = 0.999 to r = 1.0). Per patient, the analysis required nine minutes in addition to a scan duration of seven minutes. As this analytic method using T1-weighted MR images allows a fast and reliable quantification of TAF, IAF and SCF, it may serve as a valuable tool for respective studies in diabetic subjects.

Abdomen↗

PubMed2003

Improvement of sonographic needle visibility in cirrhotic livers during transjugular intrahepatic portosystemic stent-shunt procedures with use of real-time compound imaging.

The visibility of a transjugular intrahepatic portosystemic stent-shunt (TIPS) puncture needle was assessed with use of real-time compound imaging and single-line ultrasonography (US). In vitro and in vivo, needle-tissue contrast was calculated. With an increasing angle of incidence, the decrease in needle visibility was more pronounced for single-line US than for compound imaging. At angles of incidence of more than 30 degrees, the needle was barely visible with either technique. Subjective evaluation during TIPS procedures in 10 patients proved that the needle tip was significantly better seen with compound imaging. Therefore, real-time compound imaging significantly improved contrast and subjective visibility of the needle.

Adult↗

PubMed2002

Effective doses in standard protocols for multi-slice CT scanning.

The purpose of this study was to assess the radiation exposure of patients in several standard protocols in multi-slice CT (MSCT). Scanning protocols for neck, chest, abdomen, and spine were examined on a Somatom Plus 4 Volume Zoom MSCT (Siemens, Erlangen, Germany) with changing slice collimation (4x1, 4x2.5, and 4x5 mm), and pitch factors (1, 1.5, and 2). Effective doses were calculated from LiF-TLD measurements at several organ sites using an Alderson-Rando phantom and compared with calculations using the weighted CTDI. Effective dose for MSCT of the neck was 2.8 mSv. For different protocols for MSCT of the chest, 7.5-12.9 mSv were found. In abdominal MSCT protocols, effective dose varied between 12.4 and 16.1 mSv. The MSCT of the spine may lead to 12 mSv. An excellent correlation between the effective dose as determined by LiF-TLD and the calculated effective dose using the weighted CTDI could be demonstrated; however, a difference of up to 30% (mean 14.3%) was noted. Standard protocols for MSCT as measured in this study showed effective doses of up to16 mSv. Phantom measurement data show a good correlation to estimations using the weighted CTDI.

Abdomen↗