Choi Insik, Na Dong Gyu, Paik Wooyul
Department of Radiology, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.
Ultrasonography. 2021 Jul;40(3):342-348. doi: 10.14366/usg.20070. Epub 2020 Aug 21.
The normal submandibular gland (SMG) and parotid gland (PG) are thought to have similar homogeneous ultrasound (US) hyperechogenicity; however, this has not been extensively investigated. The aim of this study was to determine whether the normal SMG and PG have similar US echogenicity.
We included 969 consecutive adult patients with normal salivary glands. The patients were categorized into three age groups: group 1 (19 to 29 years, n=27), group 2 (30 to 49 years, n=273), and group 3 (≥50 years, n=669). The echogenicities of the SMG and PG were prospectively evaluated by an experienced radiologist. Computed tomography (CT) attenuation in Hounsfield units (HUs) was quantitatively measured for the SMG, PG, and sternocleidomastoid muscle in 140 patients.
Relative to the PG, the echogenicity of the SMG was similar in 706 (73.0%) and homogeneously hypoechoic in 263 patients (27.0%). The frequency of SMG hypoechogenicity decreased with increasing age (group 1, 59.3%; group 2, 36.3%; group 3, 22.1%; P<0.001). The CT attenuation levels (in HUs) of the SMG and PG were significantly higher in patients with hypoechoic SMGs than in patients with SMG echogenicity similar to that of the PG (P<0.001).
Hypoechogenicity of the SMG was observed in more than a quarter of this sample of adults with normal salivary glands. The SMG may be inadequate as a reference standard for evaluating thyroid nodule echogenicity in patients with diffuse thyroid disease with decreased echogenicity.
正常下颌下腺（SMG）和腮腺（PG）被认为具有相似的均匀超声（US）高回声性；然而，这尚未得到广泛研究。本研究的目的是确定正常SMG和PG是否具有相似的US回声性。
我们纳入了969例连续的唾液腺正常的成年患者。患者被分为三个年龄组：第1组（19至29岁，n = 27），第2组（30至49岁，n = 273），和第3组（≥50岁，n = 669）。由一位经验丰富的放射科医生对SMG和PG的回声性进行前瞻性评估。对140例患者的SMG、PG和胸锁乳突肌进行了Hounsfield单位（HU）的计算机断层扫描（CT）衰减定量测量。
相对于PG，706例（73.0%）患者的SMG回声性相似，263例（27.0%）患者的SMG呈均匀低回声。SMG低回声的频率随年龄增加而降低（第1组，59.3%；第2组，36.3%；第3组，22.1%；P<0.001）。与PG回声性相似的患者相比，SMG呈低回声的患者的SMG和PG的CT衰减水平（以HU计）显著更高（P<0.001）。
在该唾液腺正常的成年样本中，超过四分之一的患者观察到SMG低回声。对于评估回声性降低的弥漫性甲状腺疾病患者的甲状腺结节回声性，SMG可能不足以作为参考标准。
