Orientation-dependent changes in MR signal intensity of articular cartilage: a manifestation of the "magic angle" effect.

OBJECTIVE: To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the "magic angle" effect to the MR signal. DESIGN: Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared. RESULTS: A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images. CONCLUSION: The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis.

[Morphometric analysis of roentgen images of the spine for diagnosis of osteoporosis-induced fracture]. / Morphometrische Analyse von Röntgenbildern der Wirbelsäule zur Diagnose einer osteoporotischen Fraktur.

The European Vertebral Osteoporosis Study (EVOS) is one of the largest studies to investigate the prevalence of osteoporosis related vertebral fractures in a population based cross-sectional study. One of the main tasks was to create standards and logistics to obtain uniform and comparable radiographs in all 36 European centers. Furthermore the central reading of the X-rays and the morphometry of the vertebral bodies were 2 important challenges. This paper describes the standardized patient positioning and making of the radiographs as well as their morphometry, reading, and evaluation.

[Diagnosis of changes in the knee joint of high performance athletes]. / Diagnostik von Veränderungen des Kniegelenkes bei Leistungssportlern.

Sport-associated knee-joint alterations are frequent. A correct and rapid differentiation between traumatic lesions, chronic degenerative changes, and adaptive processes is important with regard to therapy as well as training and competitive planning for athletes. After the case history and physical examination, X-ray images are an absolute necessity for more in-depth diagnostic procedures. Depending on the clinical symptoms, partial aspects of the knee-joint can be visualized by sonography as well as by conventional tomography and computed tomography. If, however, a comprehensive evaluation of all knee-joint structures is needed, magnetic resonance imaging of the knee-joint should be performed. As a rapid, noninvasive procedure with high diagnostic reliability for all essential knee-joint structures only magnetic resonance imaging presently fulfills the specific demands placed on a modern diagnostic procedure by doctors working in sports-medicine.

[Quantitatively evaluated dynamic magnetic resonance tomography in chronic polyarthritis of the knee joint. A therapeutic follow-up after intra-articular cortisone application]. / Quantitativ evaluierte dynamische Magnetresonanztomographie bei chronischer Polyarthritis des Kniegelenkes. Therapiekontrolle nach intraartikulärer Kortisonapplikation.

32 patients with chronic polyarthritis were examined by MRT. Following intra-articular application of 25 mg prednisolone, 18 patients were re-examined after two of three weeks and 7 out of 18 patients were re-examined after 8 to 16 weeks, both by MRT and clinically. After an initial double echo sequence, we carried out a dynamic series of FLASH measurements (TR 30, TE 10 ms, 70 degrees) following an intravenous bolus of 0.1 mmol gadolinium-DTPA. Single intensity-time curves were treated quantitatively in relation to the pannus, muscles and effusions. Two or three weeks after treatment the curve parameters showed a reduction in pannus vascularisation which remained constant for the 8 to 16 weeks of further observation. Contrast diffusion in the pannus is initially reduced but approaches the early measurements at the time of the second examination.