The Application Of Dual-detector Conjugate View SPECT In Function-Measuring Of Parotid Gland And Head-deflection Correction

Objective:To investigate the difference of the functional parameters of the parotid glands obtained by the anterior and posterior positions in SPECT salivary gland scintigraphy.And to investigate the difference of the conjugate counts obtained by the dual-detector plane acquisition at different head deflection anglesMethods:1.Comparison of parotid function parameters of the anterior and posterior:64patients were undergone Dual-detector ⁹⁹Tc^mO₄^- salivary gland scintigraphy?SGS?which was performed with SPECT.The parotid ROI was delineated,to obtain the net counts of parotid glands(Count_Net).The 15min uptake ratio(UR₁₅)of the parotid gland,and the excretion fraction?EF?after acid stimulation at the anterior and posterior positions were calculated.The Wilcoxon rank-sum test was used to compare the difference in the 15 min net counts(Count_Net15),the maximum net count before acid stimulation((Count_Max))of the parotid glands,the UR₁₅s and EFs of the anterior and posterior positions,respectively.2.Comparison of conjugate counts of parotid gland before and after head deflection:using the ⁹⁹Tc^mO₄^- solution to infuse the parotid gland in the model,the SPECT is applied to the dual detectors,and the parotid region of interest?ROI?is delineated to measure the ROI.The radioactivity count and calculate the geometric mean of the radioactive count of the parotid gland.Data were analyzed using the Wilcoxon rank sum test.Results:1.In the anterior and posterior images,the 15minnet counts of the left parotid gland were 2.46±1.29 and 2.92±1.70?Z=-3.42,P=0.01?,and the right ones were 2.82±1.55and 3.06±1.76 respectively?Z=-2.25,P=0.03?.The maximum net counts before the acid-stimulation of left parotid gland were 2.79±1.50 and 3.23±1.87?Z=-3.09,P=0.00?,and the right side were 3.20±1.69 and 3.48±1.92?Z=-2.17,P=0.03?.The left UR15 at the anterior and posterior images were?1.71±0.76?%and?2.74±1.38?%?Z=-6.34,P=0.00?,and the right were?1.97±1.01?%and?2.86±1.45?%?Z=-6.11,P=0.00?.The left EF were?74.84±14.81?%and?76.61±15.91?%?Z=-3.92,P=0.00?,and the right were:?71.17±15.34?%and?71.48±14.90?%?Z=-4.68,P=0.00?.The 15min net counts and the maximum net count before acid stimulation of both parotid glands in the posterior positions were significantly higher than the anterior ones.The anterior UR₁₅s of both parotid glands were significantly higher than that in the posterior ones.The EFs of both parotids in the posterior positions were significantly lower than that in the anterior.2.When the deflection angle is 0°,2°,4°,6°,8°,-2°,-4°-,6°,-8°,the counts of the parotid glands are:0°:left?I_A=25.96±0.11,I_P=25.10±0.13,I_C=25.53±0.12?,right?I_A=4.05±0.02,I_P=3.27±0.04,I_C=3.64±0.02?,2°:left?I_A=24.29±0.36,I_P=25.05±0.43,I_C=24.66±0.34?,right?I_A=4.45±0.12,I_P=3.26±0.07,I_C=3.81±0.07?,4°:left?I_A=24.09±0.14,I_P=26.47±0.21,I_C=25.25±0.17?,right?I_A=4.51±0.14,I_P=3.10±0.06,I_C=3.74±0.07?,6°:left?I_A=22.66±0.26,I_P=27.43±0.20,I_C=24.93±0.21?,right?I_A=4.78±0.11,I_P=2.85±0.07,I_C=3.69±0.07?,8°:left?I_A=21.83±0.14,I_P=28.76±0.08,I_C=25.06±0.09?,right(I_A=4.83±0.17,I_P=2.55±0.06,I_C=3.50±0.09),-2°:left?I_A=26.52±0.64,I_P=22.15±0.25,I_C=24.24±0.18?,right?I_A=4.13±0.15,I_P=3.44±0.04,I_C=3.77±0.08?,-4°:left?I_A=28.23±0.21,I_P=21.11±0.16,I_C=24.42±0.18?,right?I_A=3.69±0.08,I_P=3.24±0.88,I_C=3.46±0.06?,-6°:left?I_A=29.59±0.20,I_P=19.45±0.19,I_C=23.99±0.18?,right?I_A=3.67±0.04,I_P=3.55±0.04,I_C=3.61±0.03?,-8°:left?I_A=29.75±0.38,I_P=18.07±0.15,I_C=23.18±0.23?,right?I_A=3.49±0.14,I_P=3.52±0.02,I_C=3.50±0.07?.There was no significant difference in I_C of the bilateral parotid glands before and after deflection?P?0.05/10?.Conclusion:1.There are differences in the uptake and excretion of parotid gland dynamic imaging between the anterior and posterior positions.The difference might be caused by the osseous attenuation of the mandibular branch.2.In the range of-8°to 8°,dual-probe SPECT scan can avoid the impact of head deviation on the measurement of parotid radioactivity.