Pinhole Versus Parallel-Hole Collimators for Parathyroid Imaging: An Intraindividual Comparison

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FIGURE 1.
A 1,100-mg left inferior parathyroid lesion. Lesion is seen on both parallel-hole and pinhole imaging (arrows). (Early images are on left; late images are on right.)
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FIGURE 2.
An 870-mg right inferior parathyroid lesion. Parallel-hole imaging (top) has negative findings. There is focally increased sestamibi accumulation, just below lower pole of right thyroid lobe (arrow) on pinhole imaging (bottom). (Early images are on left; late images are on right.)
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FIGURE 3.
A 680-mg solitary right inferior parathyroid lesion. Lesion is not identified on parallel-hole imaging (top) but is clearly seen on pinhole imaging (arrow) (bottom). (Early images are on left; late images are on right.)
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FIGURE 4.
Multigland disease. Parallel-hole imaging (top) has negative findings. A 170-mg left superior lesion and 170-mg right inferior parathyroid lesion (arrows) are identified on pinhole imaging, but 90-mg left inferior parathyroid lesion is not. (Early images are on left; late images are on right.)

TABLE 1

Parathyroid Lesion Localization: Pinhole Versus Parallel-Hole Imaging

Index	Pinhole	Parallel-hole	Difference (%)	χ² (df = 1)	Confidence interval (%)	P
Sensitivity	48/54 (89%)	30/54 (56%)^*	33	13.1	17 to 49	0.0003
Specificity	43/46 (93%)	44/46 (96%)	2	0.001	−7 to +11	0.29
Accuracy	91/100 (91%)	74/100 (74%)^*	17	8.9	7 to 27	0.003
PPV	48/51 (94%)	30/32 (94%)	0	0.23	−11 to +11	0.78
NPV	43/49 (88%)	44/68 (65%)^*	23	6.8	9 to 38	0.01

↵* P < 0.05 for parallel-hole vs. pinhole imaging values.
df = degrees of freedom; PPV = positive predictive value; NPV = negative predictive value.

TABLE 2

Parathyroid Lesion Localization: Effect of Lesion Weight

Index	Pinhole	Parallel-hole	Difference (%)	χ² (df = 1)	Confidence interval (%)	P
Group 1 (lesions > 840 mg)
Sensitivity	28/28 (100%)	19/28 (68%)^*	32	8.4	15 to 49	0.003
Specificity	30/32 (94%)	31/32 (97%)	3	0.001	−7 to +13	0.98
Accuracy	58/60 (97%)	50/60 (83%)^*	14	5.1	4 to 24	0.04
PPV	28/30 (93%)	19/20 (95%)	2	0.09	−11 to +15	0.76
NPV	30/30 (100%)	31/40 (78%)^*	22	5.7	9 to 35	0.01
Group 2 (lesions < 840 mg)
Sensitivity	20/26 (77%)^†	11/26 (42%)^*	35	5.2	10 to 60	0.03
Specificity	23/24 (96%)	23/24 (96%)	0	0.54	−11 to +11	0.51
Accuracy	43/50 (86%)	34/50 (68%)	18	3.6	2 to 34	0.06
PPV	20/21 (95%)	11/12 (92%)	3	0.17	−15 to +21	0.78
NPV	23/29 (79%)^†	23/38 (61%)	18	1.7	−34 to +39	0.17

↵* P < 0.05 for parallel-hole collimator vs. pinhole collimator.
↵† P < 0.05 for lesions > 840 mg vs. lesions < 840 mg.
df = degrees of freedom; PPV = positive predictive value; NPV = negative predictive value.