The repeatability of T2 relaxation time measurement of human knee articular cartilage.

OBJECTIVES: To assess short- and long-term repeatability of T2 relaxation time measurements of the knee articular cartilage. MATERIALS AND METHODS: The right knees of nine asymptomatic volunteers (age 30-38 years, five male, four female) were imaged at 1.5 T in three sessions 1 and 2 weeks apart. To observe short-term repeatability, the measurements were repeated three times within one of the three imaging sessions for each volunteer. T2 relaxation time was mapped using a multi-slice multi-echo spin echo sequence in axial and sagittal planes. Cartilage was manually segmented and repeatability, as measured by root-mean-square coefficient of variation (CVRMS) was evaluated both for the entire bulk cartilage of each joint surface in the slice and separately for each region of interest (ROI) at different topographical locations and separately for the superficial and deep half of each ROI. RESULTS: For bulk T2, the long-term repeatability was 3.2, 5.4, and 3.7%, and the short-term reproducibility was 3.9, 3.9, and 3.4% for bulk femoral, tibial, and patellar cartilage, respectively. There were no significant differences between long-term and short-term repeatability in superficial or deep cartilage when comparing CVRMS values (p = 0.338 and 0.700, respectively). For individual ROIs, the repeatability varied between 2.5 and 22.2% depending on the topographical location. CONCLUSION: The current results show mostly good repeatability. However, there were remarkable variations of T2 between bulk cartilage and different ROIs, bulk cartilage showing better repeatability. With careful patient positioning T2 can be accurately determined for different cartilage surfaces.

[Imaging of inflammatory back pain]. / Tulehduksellisen selkäkivun kuvantamis- diagnostiikka.

We recommend magnetic resonance imaging of the sacroiliac joints as the first line imaging method in suspected inflammatory back disorder. Plain X-ray can be taken from those over 35 years of age. A nonconclusive finding in plain X-ray should be verified by MR imaging. For the present, diagnostic criteria for spondylarthritis do not take into account spinal changes. Typical spinal findings can, however, be helpful in making treatment decisions. In case the spinal region MR imaging should be utilized if possible, because radiography is particularly insensitive for thoracic spine. After a confirmed diagnosis, the inflammatory nature of the condition can usually be assessed clinically.