Cartilage and soft tissue imaging using X-rays: propagation-based phase-contrast computed tomography of the human knee in comparison with clinical imaging techniques and histology.
OBJECTIVE
This study evaluates high-resolution tomographic x-ray phase-contrast imaging in whole human knee joints for the depiction of soft tissue with emphasis on hyaline cartilage. The method is compared with conventional computed tomography (CT), synchrotron radiation absorption-based CT, and magnetic resonance imaging (MRI).


METHODS
After approval of the institutional review board, 2 cadaveric human knees were examined at an synchrotron institution using a monochromatic x-ray beam of 60 keV, a detector with a 90-mm field of view, and a pixel size of 46 × 46 μm. Images of phase-contrast imaging CT were reconstructed with the filtered back projection algorithm and the equally sloped tomography method. Image quality and tissue contrast were evaluated and compared in all modalities and with histology.


RESULTS
Phase-contrast imaging provides visualization of altered cartilage regions invisible in absorption CT with simultaneous high detail of the underlying bony abnormalities. The delineation of surface changes is similar to 3-T MRI using cartilage-dedicated sequences. Phase-contrast imaging CT presents soft tissue contrast surpassing that of conventional CT with a clear discrimination of ligamentous, muscular, neural, and vascular structures. In addition, phase-contrast imaging images show cartilage and meniscal calcifications that are not perceptible on conventional CT or on MRI.


CONCLUSIONS
Phase-contrast imaging CT may facilitate a more complete evaluation of the human knee joint by providing concurrent comprehensive information about cartilage, the underlying subchondral bone, and their changes in osteoarthritic conditions.
From the *Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Germany; †European Synchrotron Radiation Facility, Grenoble, France; ‡Department of Physics, Ludwig-Maximilians University, Garching, Germany; §Phelma, Institut National Polytechnique de Grenoble, Grenoble, France; and ∥Institute of Anatomy, Ludwig-Maximilians University, Munich, Germany.
Annie
A
Horng
Emmanuel
E
Brun
Alberto
A
Mittone
Sergei
S
Gasilov
Loriane
L
Weber
Tobias
T
Geith
Silvia
S
Adam-Neumair
Sigrid D
SD
Auweter
Alberto
A
Bravin
Maximilian F
MF
Reiser
Paola
P
Coan
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D003287:Contrast Media; D003952:Diagnostic Imaging; D005260:Female; D006801:Humans; D007717:Knee / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D007719:Knee Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D017356:Synchrotrons; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media