Table 2. Intra- and interobserver variability for the MR phantom.

Diameter (cm)
		1.0	1.5	3.0	6.0	20.0
Geometric volume		82.7	3.50	56.6	113	4189
Cavalieri volume
Observer 1	1	83.5	3.3	57.4	109	3898
	2	88.7	3	53.3	112	3642
CE (intra)		1.90	2.23	2.75	2.36	1.13
CV (intra)		4.27	6.73	5.24	1.92	4.80
Average deviation		3.95	−11.11	−2.26	−2.26	−11.11
Observer 2		83.8	3.19	57.2	120	4014
CE (inter)		0.90	2.31	1.03	1.81	2.36
CV (inter)		0.25	2.40	0.25	6.79	2.13
ROI volume
Observer 1	1	97.9	3.80	58.7	103	4168
	2	95.4	3.55	60.9	104	4249
CV (intra)		1.85	4.98	2.55	0.68	1.35
Average deviation		14.4	4.76	5.35	−9.18	0.46
Observer 2		94	3.64	65.3	116	4948
CV (inter)		2.87	3.04	7.53	8.39	12.1
Geometric surface area		496	14.1	113	113	1257
Surface
Observer 1	1	512	14.7	105	101	1221
	2	567	15.2	111	108	1116
CE (intra)		1.58	3.84	2.03	2.03	1.84
CV (intra)		7.21	2.36	3.93	4.74	6.35
Average deviation		8.06	5.69	−4.63	−8.13	−7.57
Observer 2		547	15.1	96.8	98.1	1258
CE (inter)		2.36	2.80	1.75	1.43	2.80
CV (inter)		4.49	1.87	5.98	2.13	2.08

Volume is in measured in cm³ and was found using Equation 1; surface area is measured in cm² and found using Equation 2. CE is calculated using Equation 7. CV is calculated using Equation 9. Average deviation is calculated using Equation 10.

CE, coefficient of error; CV, coefficient of variation; CE (intra), mean CE for Observer 1; CE (inter), mean CE for both observers; CV (intra), intraobserver variability, the variance for the two estimates made by Observer 1; CV (inter), interobserver variability (Observer 1 against Observer 2) using the first estimate from Observer 1 and the estimate from Observer 2.