Contrast-enhanced ultrasound of the small organs in children

Abstract

In pediatric and adult populations, intravenous contrast-enhanced ultrasound (CEUS) remains off-label for imaging of organs other than the liver and heart. This limited scope inhibits potential benefits of the new modality from a more widespread utilization. Yet, CEUS is potentially useful for imaging small organs such as the thyroid gland, lymph nodes, testes, ovaries and uterus, with all having locations and vasculature favorable for this type of examination. In the adult population, the utility of CEUS has been demonstrated in a growing number of studies for the evaluation of these small organs. The aim of this article is to present a review of pediatric CEUS of the thyroid gland, lymph nodes, testes, ovaries and uterus as well as to draw from the adult literature indications for possible applications in children.

Keywords: Children; Contrast-enhanced ultrasound; Lymph nodes; Ovary; Testis; Thyroid; Ultrasound; Ultrasound contrast agents; Uterus.

Fig. 1

Right thyroid nodule that was incidentally detected on a CT scan of the cervical spine in a 17-year-old boy. The CT was obtained following a motor vehicle collision. a Transverse gray-scale ultrasound (US) of the right thyroid shows a well-circumscribed, solid, iso- to slightly hyperechoic nodule in the lower pole (calipers). b Transverse color Doppler US of the right thyroid nodule demonstrates predominantly peripheral vascularity. c–e Transverse contrast-enhanced ultrasound (CEUS) of the right thyroid lobe. Contrast-only mode. There is homogeneous enhancement of the nodule (arrow), which is slightly hyperenhancing to the overlying thyroid parenchyma (asterisk) in the arterial phase (c) and iso-enhancing in the parenchymal (d) and delayed (e) phases. Overall this is a benign CEUS enhancement pattern. The diagnosis following biopsy was a benign follicular adenoma, oncocytic type (Hurthle cell adenoma)

Fig. 2

Severe right-side lymphadenitis colli in a 5-year-old girl. a Gray-scale US, transverse plane, shows multiple lymph nodes (arrowheads), one of which appears enlarged (arrow) with an anechoic area centrally (asterisk), suggestive of abscess formation. b–d Transverse contrast-enhanced ultrasound (CEUS) image with dual display of contrast (left) and gray-scale (right) modes and in contrast-only mode at 10 s (b), 15 s (c) and 39 s (d) post contrast injection. The central anechoic area of the lymph node (asterisk) demonstrates complete lack of enhancement corresponding to the purulent content. A hyperenhancing rim (arrow) is noted in the periphery corresponding to the adjacent inflamed tissue. An additional enlarged and abnormally enhancing lymph node is noted adjacent to the abscess (arrowhead)

Fig. 3

Atypical cervical mycobacteriosis in a 3-year-old girl. a Transverse gray-scale US demonstrates an enlarged lymph node (arrow) with heterogeneous internal reflectivity and presence of tiny hyperechoic punctate foci. b, c Transverse contrast-enhanced ultrasound (CEUS) with dual display of contrast (left) and gray-scale (right) modes. Ten seconds post contrast injection (b), no enhancement is seen within the lymph node (arrow). Fifteen seconds post contrast injection (c), there are multiple areas (arrowheads) of nonenhancement centrally within the lymph node, corresponding to caseating necrosis suggestive of atypical mycobacteriosis within the lymph node

Fig. 4

Advanced puberty in an 11-year-old boy undergoing high-resolution contrast-enhanced ultrasound (CEUS) of the right testis to assess for tumor. Normal testicular perfusion. a–d Transverse CEUS image with dual display of contrast (right) and gray-scale (left) modes. Two seconds post contrast injection (a), no intratesticular enhancement is visible. Eleven seconds post contrast injection (b), the first microbubbles appear in the scrotum and the testicular tunica (arrows). Twenty-two seconds post-contrast injection (c), there is homogeneous enhancement of the testicular tissue (asterisk). One hundred twenty seconds post-contrast injection (d), there is homogeneous enhancement of the testicular tissue including the mediastinum testis (arrowhead), without pathological changes

Fig. 5

Acute scrotal pain in a 6-year-old boy with intellectual disability. a Longitudinal gray-scale US of the right testicle shows mild diffuse heterogeneity of the testicular parenchyma (asterisk). There is thickening and an edematous appearance of the scrotal wall (arrow). b Transverse color Doppler US image of the right testicle shows absence of color flow signal within the testicular parenchyma (asterisk). There is a rim of peripheral enhancement (arrow) corresponding to hyperemia of the scrotal wall. c Longitudinal dual display of contrast (left) and gray-scale (right) modes of the right testicle 49 s following contrast administration. There is complete absence of enhancement within the testicular parenchyma (asterisk), while contrast agent is seen in the surrounding tissues. See Online Supplementary Material 1 for cinematic images

Fig. 6

US in a 16-year-old-boy with severe pain of the left testicle. a High-resolution longitudinal gray-scale US of the left testicle shows homogeneous echogenicity with slightly coarse echotexture. b Longitudinal contrast-enhanced ultrasound (CEUS) with dual display of contrast (right) and gray-scale (left) modes, 21 s after contrast administration, shows a peripheral wedge-shape area of nonenhancement in the ventral segment of the lower pole of the left testicle, consistent with segmental infarction (arrow). Image reprinted with permission from [3]

Fig. 7

Left scrotal swelling in an 8-week-old boy. US was initially performed for evaluation of the swelling. An intratesticular cystic lesion was incidentally detected. a Transverse color Doppler US image of left testis. The testicular volume is normal for age. There is a large left-side anechoic hydrocele (asterisk). A cystic lesion (arrow) is noted centrally within the left testis, with a thin internal septum noted in the periphery of the lesion (arrowhead). b, c Transverse contrast-enhanced ultrasound (CEUS) of the left testis in contrast-only mode; 27 s post-contrast injection (b), there is absence of enhancement of the cystic lesion (arrow), and 44 s post-contrast injection (c), there is enhancement of the thin septum in the periphery of the lesion (arrowhead) that appears to be to the same extent as the surrounding normally enhancing testicular tissue. No evidence of enhancing nodularity is noted. There is no enhancement of the hydrocele (asterisk). Partial orchiectomy was performed, revealing changes of acute orchitis with hemosiderin deposition suggestive of sequala of previous inflammation

Fig. 8

Palpable lesion adjacent to the right testicle in an 11-year-old boy. a Longitudinal gray-scale US of the right testis shows a round extra-testicular structure (arrow) between the epididymis (E) and the right testis (T), with similar reflectivity as the adjacent testicular tissue. b, c Quantitative contrast-enhanced ultrasound (CEUS) with time-intensity curve analysis, with a region of interest placed within the right testis (yellow circle in b) and the structure of concern (green circle in b). Time-intensity curve analysis of contrast dynamics (c) shows a similar wash-in and curve progression in the first 30 s for both structures. d Transverse CEUS color-coded map shows similar enhancing parameters for the structure of concern and the right testis. This combination of imaging findings favors the diagnosis of supernumerary testis compatible with polyorchidism

Fig. 9

Imaging in an 18-year-old woman with cystic fibrosis status post lung transplant 4 years prior; she had a mediastinal mass concerning for post-transplant lymphoproliferative disease (PTLD). a, b Sagittal (a) and transverse (b) trans-abdominal gray-scale US demonstrates soft-tissue masses (arrows) posterior to the uterus (U) and small volume of free fluid (F) within the pelvis. c Transverse contrast-enhanced ultrasound (CEUS) of the pelvis in contrast-only mode at 2 min 30 s after contrast administration demonstrates heterogeneous enhancement of both ovarian masses (arrows), with no normal ovarian follicles visualized. d Axial positron emission tomography (PET)/CT demonstrates marked [F-18]2-fluoro-2-deoxyglucose (FDG) avidity of both ovarian masses (arrows), compatible with PTLD

Fig. 10

Ovarian cyst in a 16-year-old girl. CT was performed following blunt abdominal trauma. a Sagittal reconstruction from contrast-enhanced CT of the abdomen and pelvis demonstrates hemorrhagic fluid (F) in the pelvis from a splenic laceration (not shown here). A large cystic lesion (arrow) is noted posterior to the uterus. b Sagittal trans-abdominal gray-scale US demonstrates the anechoic lesion (arrow) posterior to the uterus (U) in direct contact with the right ovary (arrowhead). c Sagittal contrast-enhanced ultrasound (CEUS) of the pelvis in contrast mode shows no visible enhancement, nodularity or septations within the ovarian lesion (arrow), compatible with simple cyst

Fig. 11

Imaging of a 16-year-old girl with vaginal bleeding. A fibroid lesion in the anterior wall of the uterus was biopsied hysteroscopically and had a pathological diagnosis of embryonal rhabdomyosarcoma. The girl was now presenting for hysteroscopic tumor debulking. a Intraoperative transvaginal gray-scale pelvic US, sagittal plane, shows that the uterus (U) is anteverted and demonstrates heterogeneous and poorly defined endometrium with multiple echogenic foci in the endometrial canal (arrow), likely reflecting gas loculi from the procedure. A heterogeneous, predominantly hypoechoic mass-like lesion is present within the central portion of the uterus, extending to the myometrium (arrowheads). A small volume of free fluid (F) is present within the pelvis. b Intraoperative transvaginal color Doppler US, sagittal plane, shows no significant color Doppler flow within the hypoechoic central regions (arrowheads). Gas loculi are noted within the endometrial canal (arrow). A small volume of free fluid (F) is present within the pelvis. c–e Intraoperative transvaginal contrast-enhanced ultrasound (CEUS) of the uterus in sagittal plane with simultaneous display of gray-scale (left) and contrast (right) images (c) and in contrast-only mode (d and e). CEUS was performed in the operating room during hysteroscopy, immediately following tumor debulking to evaluate for the extent of residual disease. A bolus dose of 1 mL Lumason was injected. Still images from a cinematic clip obtained during gentle sweeping through the uterus (U) at 20 s (c), 44 s (d) and 155 s (e). Peripheral lobulated enhancement (arrow) of the uterus corresponds to the residual tumor with persistent central nonenhancement (asterisk), likely to represent blood products from tumor debulking. f–i Intraoperative transabdominal CEUS of the uterus was subsequently performed in sagittal plane, following repeat bolus injection of 1 mL Lumason with simultaneous display of gray-scale (left) and contrast (right) images (f) and contrast-only mode (g–i). Still images of a stationary cinematic clip obtained at 20 s (f), 30 s (g), 109 s (h) and 156 s (i) following contrast administration show enhancement in the periphery of the uterus (U) with a lobular configuration and washout of the central tissue (arrowhead). Within the central portion of the uterus, there is persistent nonenhancement (asterisk), in keeping with blood products from tumor debulking. B bladder