Mehrschicht-Spiral-CT des Abdomens bei onkologischen Patienten: Einfluss von Tischvorschub und Detektorkonfiguration auf Bildqualität und Strahlenexposition

PURPOSE

To evaluate the image quality and radiation exposure of different spiral CT scanning parameters for routine staging examination of the abdomen in oncologic patients using a multi-slice CT scanner.

METHODS/MATERIALS

Examination of 40 patients in 4 groups on a multi-slice CT scanner (Somatom VolumeZoom, Siemens AG, Forchheim). Functional detector width (4 x 2.5, 4 x 5 mm) and pitch (table feed in relation to collimated slice width) were varied (3 and 5). Tube voltage (120 kV), effective tube current (160 mAs), slice-thickness (6 mm), increment (4 mm), kernel (B 30), and contrast injection parameters were kept constant. Axial images were assessed by three radiologists regarding delineation of anatomic structures, artifacts, and overall image quality.

RESULTS

Significantly reduced image quality especially due to artifacts was observed using a 5 mm detector configuration with a pitch of 5 (scan time 9 sec). Image quality was rated best for a 2.5 mm detector configuration with a pitch of 3 and a scan time of 28 sec. The effective dose was independent of the pitch. However, the mean effective dose was 9% higher using the smaller detector configuration (9.9 mSv vs 10.9 mSv).

CONCLUSIONS

For routine staging CT of the abdomen use of a 4 x 2.5 mm detector configuration with a pitch between 3 and 5 is recommended. A 4 x 5 mm detector configuration using overlapping data acquisition can also be recommended, but additional thin slice reformations are not possible.

Multislice cardiac spiral CT evaluation of atypical hypertrophic cardiomyopathy with a calcified left ventricular thrombus

We report a case of a 43-year-old male patient with an atypical nonobstructive hypertrophic cardiomyopathy and a calcified left ventricular thrombus, and present results of multislice computed tomography (MSCT) using retrospective electrocardiograph gating, which is a new modality in cardiac imaging. Obtaining virtually motion-free images with a temporal resolution of 250 ms in an optimized heart scan MSCT allows functional imaging with evaluation of impaired systolic and diastolic left ventricular wall motion.