[Studies on image quality, high contrast resolution and dose for the axial skeleton and limbs with a new, dedicated CT system (ISO-C-3 D)].
OBJECTIVE
Evaluation of 3D-CT imaging of the axial skeleton and different joints of the lower and upper extremities with a new dedicated CT system (ISO-C-3D) based on a mobile isocentric C-arm image amplifier.


METHODS
27 cadaveric specimes of different joints of the lower and upper extremities and of the spinal column were examined with 3D-CT imaging (ISO-C-3D). All images were evaluated by 3 radiologists for image quality using a semiquantitative score (score value 1: poor quality; score value 4: excellent quality). In addition, dose measurements and measurements of high contrast resolution were performed in comparison to conventional and low-dose spiral CT using a high contrast phantom (Catphan, Phantom Laboratories).


RESULTS
Adequate image quality (mean score values 3 - 4) could be achieved with an applied dose comparable to low-dose CT in smaller joints such as wrist, elbow, ankle and knee. A remarkably inferior image quality resulted in imaging of the hip, lumbar and thoracic spine (mean score values 2 - 3) in spite of almost doubling the dose (dose increased by 85 percent). The image quality of shoulder examinations was insufficient (mean score value 1). Phantom studies showed a high-contrast resolution comparable to helical CT in the xy-axis (9 lp/cm).


CONCLUSIONS
Preliminary results show, that image quality of C-arm-based CT-imaging (ISO-C-3D) seems to be adequate in smaller joints. ISO-C-3D images of the hip and axial skeleton show a decreased image quality, which does not seem to be sufficient for diagnosing subtle fractures.
Rock
C
C
Institut für Klinische Radiologie, Klinikum der Universität München, Innenstadt, Germany. rock@radin.med.uni-muenchen.de
Kotsianos
D
D
Linsenmaier
U
U
Fischer
T
T
Brandl
R
R
Vill
F
F
Wirth
S
S
Kaltschmidt
R
R
Euler
E
E
Pfeifer
K J
KJ
Reiser
M
M
D001132:Arm / Q000000981:diagnostic imaging; D001175:Arthrography; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002102:Cadaver; D006801:Humans; D021621:Imaging, Three-Dimensional; D007866:Leg / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013131:Spine / Q000000981:diagnostic imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*