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Assessing the effect of CT slice interval on unidimensional , bidimensional and volumetric measurements of solid tumours . OBJECTIVES To study the magnitude of differences in tumour unidimensional ( 1D ) , bidimensional ( 2D ) and volumetric ( VOL ) measurements determined from computed tomography ( CT ) images reconstructed at 5 , 2.5 and 1.25 mm slice intervals . MATERIALS AND METHODS A total of 118 lesions in lung , liver and lymph nodes were selected from 30 patients enrolled in early phase clinical trials . Each CT scan was reconstructed at 5 , 2.5 and 1.25 mm slice intervals during the image acquisition . Lesions were semi-automatically segmented on each interval image series and supervised by a radiologist . 1D , 2D and VOL were computed based on the final segmentation results . Average measurement differences across different slice intervals were obtained using linear mixed-effects analysis of variance models . RESULTS Lesion diameters ranged from 6.1 to 80.1 mm ( median 18.4 mm ) . The largest difference was seen between 1.25 and 5 mm ( mean difference of 7.6 % for 1D [ P < 0.0001 ] , 13.1 % for 2D [ P < 0.0001 ] , -5.7 % for VOL [ P = 0.0001 ] ) . Mean differences between 1.25 and 2.5 mm were all within ±3.5 % ( within ±6 % confidence interval ) . For VOL , there was a larger average difference between measurements on different slice intervals for the smaller lesions ( < 10 mm ) compared with the larger lesions . CONCLUSIONS Different slice intervals may give different 1D , 2D and VOL measurements . In clinical practice , it would be prudent to use the same slice interval for consecutive measurements .
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Intervention_Educational
CT slice interval
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Intervention_Educational
Each CT scan was reconstructed at 5 , 2.5 and 1.25 mm slice intervals during the image acquisition .
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Outcome_Other
unidimensional , bidimensional and volumetric measurements
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Outcome_Other
magnitude of differences in tumour unidimensional ( 1D ) , bidimensional ( 2D ) and volumetric ( VOL ) measurements
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Outcome_Other
1D , 2D and VOL
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Outcome_Physical
Lesion diameters