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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5802_Библиотеки_им_академика_М_И_Перельмана.pdf
Supercial structures
126
Parathyroid glands
PREPARATION
None.
POSITION
Supine.
TRANSDUCER
7.0–14.0 MHz linear transducer.
METHOD
Images are obtained in the longitudinal and transverse planes.
APPEARANCE
The four normal parathyroid glands are generally located at the poles
of the thyroid lobes, although the inferior parathyroid glands may be
ectopic, found in the upper mediastinum. Occasionally, the normal
parathyroid gland can be identied separate from thyroid tissue, especially in a longitudinal view. A linear high-reective band representing
an aponeurosis or a brous sheath may surround the gland. The normal parathyroid gland may either be seen as a slightly low-reective
or slightly high-reective oval area adjacent to the normal thyroid. A
parathyroid adenoma is identied as an oval-shaped, low-reective
area, with increased color Doppler ow, in the expected location of a
parathyroid gland.
MEASUREMENTS
The average normal parathyroid measures 5 × 3 × 1 mm but is difcult
to image. The enlarged parathyroid adenoma is normally visible as an
oval-shaped, low-reective area adjacent to the thyroid gland, most
often located at the inferior aspect of the left thyroid lobe.
FURTHER READING
Reeder SB, Desser TS, Weigel RJ, Jeffrey RB. Sonography in primary
hyperparathyroidism. Review with emphasis on scanning
technique. J Ultrasound Med. 2002; 21:539–552.
Simeone JF, Mueller PR, Ferrucci JT Jr., van Sonnenberg E,
Wang CA, Hall DA, Wittenberg J. High-resolution real-time
sonography of the parathyroid. Radiology. 1981; 141:745–751.
Parathyroid glands
Longitudinal view demonstrating the oval hyporeective parathyroid adenoma (between
cursors), surrounded by the hyperreective aponeurosis.
127
The same parathyroid adenoma (between cursors) in the transverse view.
Supercial structures
128
Submandibular salivary glands
PREPARATION
None.
POSITION
Supine.
TRANSDUCER
7.0–14.0 MHz linear array transducer.
METHOD
The gland is imaged in two planes: paramandibular and frontal.
APPEARANCE
Homogenous high-reective parenchyma, well demarcated from the
surrounding tissues.
MEASUREMENTS
Three measurements are obtained: anteroposterior and lateral-medial
direction, and then depth.
Volume is calculated as if the gland is a spherical body with the formula:
Volume =
π × height × (diameter)
4
2
Normal values
Anteroposterior length 35 ± 5.7 mm
Paramandibular length (depth) 14.3 ± 2.9 mm
Lateral-medial length 33.7 ± 5.4 mm
FURTHER READING
Dost P, Kaiser S. Ultrasonographic biometry in salivary glands.
Ultrasound Med Biol. 1997; 23:1299–1303.
Submandibular salivary glands
The submandibular gland in a paramandibular view, to measure the lateral-medial length.
129
The submandibular gland in a longitudinal view, to measure the anteroposterior and depth
measurements.
Supercial structures
130
Parotid salivary glands
PREPARATION
None.
POSITION
Supine.
TRANSDUCER
7.0–14.0 MHz linear array transducer.
METHOD
The gland is imaged in a transverse plane and in an axis parallel to the
ramus of the mandible (parallel direction to the normal dental occlusion).
APPEARANCE
The gland is homogeneous and of high reectivity, more so than that
of the submandibular gland.
MEASUREMENTS
Axis parallel to ramus of mandible 46.3 ± 7.7 mm
Dimension in transverse axis 37.4 ± 5.6 mm
Parotid parenchyma:
Lateral to mandible 7.4 ± 1.7 mm
Dorsal to mandible 22.8 ± 3.6 mm
FURTHER READING
Dost P, Kaiser S. Ultrasonographic biometry in salivary glands.
Ultrasound Med Biol. 1997; 23:1299–1303.
Parotid salivary glands
The homogenous parotid gland is imaged in an axis parallel to the ramus of the mandible,
in the direction of the dental occlusion.
131
The parotid gland is imaged in the transverse axis, and the measurement obtained.
Supercial structures
132
Thyroid gland
PREPARATION
None.
POSITION
Supine with the neck extended.
TRANSDUCER
7.0–14.0 MHz linear transducer.
METHOD
Longitudinal and transverse images obtained in the lower half of the
neck from the midline.
APPEARANCE
Below the subcutaneous tissues is a 1–2 mm thin, low-reective line
corresponding to the platysma muscle. Anterior to this is a thin, highreective line representing the supercial cervical aponeurosis. The
thyroid gland is made up of two lobes connected medially by the isthmus, which has a transverse course. Approximately 10%–40% of normal people have a third lobe (pyramidal) arising from the isthmus that
runs upward along the same longitudinal axis as the thyroid lobes but
lies in front of the thyroid cartilage. The thyroid parenchyma has a
ne homogeneous echo pattern, which is of higher reectivity than the
contiguous muscular structures and is interrupted at the periphery by
the arterial and venous vessels.
MEASUREMENTS
Age Length Anteroposterior
diameter
Newborn 18–20 mm 8–9 mm
1 year 25 mm 12–15 mm
Adult 40–60 mm 13–18 mm
The mean thickness of the isthmus is 4–6 mm.
Thyroid volume may be calculated using the right and left anteropos-
terior lobe measurements and the following formula:
Volume = [6.91 × RAP] + [3.05 × LAP] – 3.48
Thyroid gland
Transverse image at the level of the thyroid isthmus, with a depth measurement of the
isthmus, and a depth measurement of the right lobe.
133
A longitudinal image through a thyroid lobe, with a length measurement.
The difference in thyroid volume between males and females is
explained solely by a difference in body weight.
Male thyroid volume is 19.6 ± 4.7 ml; female is 17.5 ± 3.2 ml.
Supercial structures
134
Doppler studies of the thyroid arteries: There are two thyroid arteries
on each side, superior and inferior. Rarely, a third artery is present in
the midline and is named the arteria ima.
• Mean diameter of these vessels is 1–2 mm.
• Peak systolic velocity is 20–40 cm/second.
• End diastolic velocity is 10–15 cm/second.
The thyroid veins originate from the perithyroid venous plexus and
join to form three main groups, which drain into the ipsilateral jugular
vein. The largest vessel is a lower vein and can measure up to 7–8 mm.
FURTHER READING
Hegedus L, Perrild H, Poulsen LR, Andersen JR, Holm B, Schnohr
P, Jensen G, Hansen JM. The determination of thyroid volume
by ultrasound and its relationship to body weight, age and sex in
normal subjects. J Clin Endocrinol Metabol. 1983; 56:260–263.
Udea D. Normal volume of the thyroid gland in children. J Clin
Ultrasound. 1990; 18:455–462.
Vade A, Gottschalk ME, Yetter EM, Subbaiah P. Sonographic
measurements of the neonatal thyroid gland. J Ultrasound Med.
1997; 16:395–399.
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