Comparison of 3D vs. 2D fast spin echo imaging for evaluation of articular cartilage in the knee on a 3T system scientific research.
ABSTRACT We sought to retrospectively compare the accuracy of a three-dimensional fat-suppressed, fast spin-echo sequences acquired in the sagittal plane, with multiplanar reconstructions to that of two-dimensional fat-suppressed, fast spin echo sequences acquired in three planes on a 3T MR system for the evaluation of articular cartilage in the knee.
Our study group consisted of all patients (N=34) that underwent 3T MR imaging of the knee at our institution with subsequent arthroscopy over an 18-month period. There were 21 males and 13 females with an average age of 36 years. MR images were reviewed by 3 musculoskeletal radiologists, blinded to operative results. 3D and 2D sequences were reviewed at different sittings separated by 4 weeks to prevent bias. Six cartilage surfaces were evaluated both with MR imaging and arthroscopically with a modified Noyes scoring system and arthroscopic results were used as the gold standard. Sensitivity, specificity, and accuracy were calculated for each reader along with Fleiss Kappa assessment agreement between the readers. Accuracies for each articular surface were compared using a difference in proportions test with a 95% confidence interval and statistical significance was calculated using a Fisher's Exact Test.
Two hundred and four articular surfaces were evaluated and 49 articular cartilage lesions were present at arthroscopy. For the patellofemoral surfaces, the sensitivity, specificity, and accuracy were 76.5%, 83%, and 78.2% for the 3D sequences and were 82.3%, 76%, and 82% respectively for the 2D sequences. For the medial compartment surfaces, the sensitivity, specificity, and accuracy were 81.1%, 65.1%, and 78.5% for the 3D sequences and were 82.5%, 48%, and 76.7% respectively for the 2D sequences. For the lateral compartment surfaces, the sensitivity, specificity, and accuracy were 89.3%, 39%, and 79.5% for the 3D sequences and were 94.7%, 18.8%, and 79.5% respectively for the 2D sequences. The accuracies were not significantly different between 3D and 2D sequences. Fleiss Kappa agreement values for the assessment of inter-observer agreement ranged from substantial for the patella and medial femur to moderate for the trochlea and fair for the medial tibia and lateral compartment.
There was no significant difference in accuracy for the evaluation of articular cartilage of a single three-dimensional, fast spin echo sequence with multi-planar reformatted images vs. two-dimensional, fast spin echo sequences acquired in all three imaging planes in the knee.
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ABSTRACT: This paper describes an experimental evaluation of the precision achieved by eye interpolation. It explains the effect on eye interpolation of differences in the position of a pointer. Fiducial lines—a fiducial line is the “0” or leftmost line on a vernier scale and serves as a coarse pointer—were set at different positions between 0 and 1 mm (0.05 mm intervals) using the vernier scales. The vernier scales were then covered with plastic tape. Thi vernier callipers were randomly given to 19 whbjects who were asked to read the position of the fiducial lines on the main scale, and to estimate them to the nearest tenth of a division.As a result of this experiment we found the following: (i) The bias and dispersion of readings just below the scale marks were the smallest. (ii) When the fiducial line were located at less than 0.5, the readings were biased toward 0, and when they were located at greater than 0.5, they were biased toward 1. (iii) Based on an analysis of variance involving the position of the fiducial line, the individual observers, and their interactions, the position of the fiducial line was found to be the most significant. (iv) Thus, personal errors in reading should be categorized together with instrumental errors, and could be reduced with maximum likelihood estimation.Measurement. 01/1994; 13(2):147-151.
Article: CMM verification: a survey[show abstract] [hide abstract]
ABSTRACT: This paper surveys various testing methods, conditions and specifications for checking Co-ordinate Measuring Machines (CMMs). Firstly, it describes and compares test specifications of the most important standards. Secondly, the paper provides a review and a classification of various testing methods based on mechanical artefacts, optical techniques, and opto-mechanical devices. Finally, artefacts used for probing performance verification are outlined and potential research areas are identified.Measurement. 01/1996;