Biomedical subjects

M Tiitola

Publications and source records attributed to M Tiitola.

3 recordsLinked to original sources

PubMed2002

Computed tomography of asbestos-related pleural abnormalities.

OBJECTIVES: To study the observer agreement in several asbestos-related pleural abnormalities and to define criteria to discriminate between pleural changes in workers with occupational disease, and those in controls. METHODS: Pleural abnormalities in spiral computed tomography of 602 construction workers with asbestosis or bilateral pleural plaques and 49 controls were reviewed by three radiologists using structured forms. RESULTS: Intra- and inter-observer agreement (weighted kappa) was 0.4 or better with regard to the calcification, extent and thickness of pleural disease. These factors all correlated positively with the duration of asbestos exposure. There were significant differences in these pleural changes between the workers (mean extent per side 83 cm(2)) and controls (mean extent per side 40 cm(2)). Of the controls, 84% showed pleural lesions with an estimated extent of 10 cm(2) or more, bilateral in 64%. The extent of 45 cm(2) in pleural disease was the best value for discriminating between the controls and diseased workers, with a sensitivity of 82% and a specificity of 66%. The degree of pleural calcification, however, was the best discriminator between these groups, but quantitative methods are necessary for its use in the diagnostics of individuals. CONCLUSIONS: The extent, calcification and thickness were well-repeatable indicators of benign pleural pathology and thus their use in future classification systems in computed tomography is recommended. In our material, the extent of 45 cm(2) and the degree of calcification were helpful in discriminating between pleural changes in workers with occupational disease, and those in controls who also presented marked pleural pathology.

Adult↗

PubMed2001

Estimation or quantification of tumour volume? CT study on irregular phantoms.

PURPOSE: To compare radiologists' subjective size estimation to computerised volume quantification of tumour-like phantoms in spiral CT. MATERIAL AND METHODS: Eight tubular phantoms with the inside irregularly covered with silicone (8.7-31.6 ml) were imaged. The phantoms were pairwise compared to analyse the differences in silicone volumes. The observers, 2 radiologists and 2 residents, used both subjective image analysis (2 sessions) and computerised volume quantification (1 session). Accuracy and observer agreement of both methods were calculated. RESULTS: Subjective size estimation was correct in 51% (mean weighted kappa, Kqw=0.73). Using four observers' mean value (Kqw=0.81) or median value (Kqw=0.77) slightly improved the results. Average intra-observer agreement was better than average interobserver agreement. In computerised volume quantification 70% of all classifications were correct (mean Kqw=0.85). The results were moderate even when every second or fourth slice were measured. CONCLUSION: Subjective size estimation of irregular tumours should be repeatedly performed by the same observer, or by using the mean or median estimate of several observers. Computer-based methods are even more reliable and their use is especially recommended for film readers with limited radiological experience. Only every fourth slice may be measured without a major loss of measurement accuracy.

Humans↗

PubMed1997

Optimising imaging parameters in experimental spiral CT.

PURPOSE: This in vitro study was conducted to analyse lesion detection and relative radiation exposure in different CT techniques. MATERIAL AND METHODS: We used a plastic phantom (12 x 8 x 2 cm) containing holes filled with air or fluid of varying densities to simulate lesions. This was imaged with Siemens Somatom Plus S and GE High Speed Advantage units. We varied table feeds (3 and 6 mm/s in Siemens and 3 and 4.5 mm/s in GE) and increments (2 mm and 4 mm) while keeping collimation at 3 mm. The SmartScan program of GE and the reformatting algorithm of Siemens were also analysed. To evaluate the different methods, the phantom lesions were counted by 3 observers. Radiation exposures associated with each technique were also measured. RESULTS: The images reformatted to a coronal direction were significantly inferior (p < 0.01) to those in other techniques. The use of SmartScan did not influence lesion detection, nor did changes in pitch or increment. Spiral and non-spiral techniques proved to be equal. Radiation exposure was lowest when a greater pitch or the SmartScan program was used. CONCLUSION: Radiation exposure in CT can be limited without significantly impairing the image quality by using low-dose techniques. Reformatting to a coronal direction should be used with care as it debases the image quality.

Humans↗