INTRODUCTIONWith the advent of high-resolution real time
ultrasonography, this non-invasive, non-ionizing, low cost and quick imaging modality has become the modality of choice for the rapid evaluation of the child. Ultrasound is ideally suited to paediatrics and examinations can often and safely be repeated, with no requirement of sedation.
The many applications of this portable, reliable and comparatively cost effective imaging modality are briefly discussed below.
USE OF USG FOR THE INFANT BRAIN
- Chiari I: Downward displacement of the cerebellar tonsil without displacement of the 4th ventricle/medulla.
- Chiari II: Commonest anomaly and is almost always associated with spina bifida and meningomyelocele. Here, there is downward displacement of the cerebellar tonsils along with pons and medulla through an enlarged foramen magnum into the upper spinal canal. 4th ventricle is also elongated into the upper spinal canal and posterior fossa in small.
- Chiari III: High cervical or occipital encephalocele.
- Chiari IV: Severe cerebellar hypoplasia
Presents with large posterior fossa cyst, which communicates with the 4th ventricle, hypoplastic cerebellar hemispheres and absent/rudimentary inferior vermis. This must be differentiated from other posterior fossa cystic abnormalities like cisterna magna, trapped 4th ventricle and arachnoid cyst.
Agenesis of the corpus callosum
It may be partial / complete and usually associated with other anomalies.
May be alobar, semilobar, lobar and usually associated with facial & calvarial anomalies.
Could be confused with alobar holoprosencephaly but the presence of 'falx' helps to differentiate this lesion. It is difficult to differentiate it from severe hydrocephalus but a thin rim of cortex should be seen in hydrocephalus.
For diagnosis, grading severity and post-shunt follow up.
Germinal matrix hemorrhage may occur in subependymal, intraventricular or intraparenchymal region and is more commonly seen in premature and low birth weight infants. Subdural, epidural and subarachnoid haemorrhages are other less common sites of intracranial haemorrhage.
Hypoxic ischemic encephalopathy (HIE)
Periventricular leukomalacia and periventricular haemorrhagic infarction are the primary manifestations of HIE in the premature infant. Perinatal asphyxia in the term infant can cause diffuse cerebral edema which may progress to brain atrophy / multi cystic encephalomalacia. Doppler studies would reveal lack of Doppler signal / flow
Inflammation, edema and vasculitis are common to all cerebral infections. Ultrasound plays an important role in identifying and following both antenatal and neonatal complications (echogenic sulci, intra-axial fluid collection, hydrocephalus, ventriculitis, abnormal parenchymal echogenicity, abscess, encephalomalacia and calcifications) from congenital (TORCH) infections.
Most tumours presenting before 2yrs of age are congenital (PNET, low grade astrocytoma, craniopharyngioma, teratoma). Ultrasound has a role in screening infants and helps to differentiate solid, cystic or vascular components of the masses.
Cystic lesions in the brain include arachnoid cysts, Dandy Walker cysts, porencephalic cysts, choroid plexus cysts, subependymal and colloid cysts.
Duplex / colour Doppler ultrasound helps to differentiate arteriovenous malformation such as Vein of Galen aneurysm from other cystic lesions.
USG AND PEDIATRIC ABDOMEN
The spectrum of pathology encountered in the neonate is different from that in older children and is much more likely to be a congenital abnormality rather than a malignancy.
They are the commonest course of abdominal mass in both infants and children, accounting to more than 50%.
Solid renal masses: <6 years - Mesoblastic nephroma, >6 years- Wilm's tumour
Bilateral renal masses:
- Autosomal recessive polycystic renal disease - usually associated with congenital hepatic fibrosis with/without portal hypertension.
- Renal vein thrombosis
Cystic renal masses:
- Hydronephrosis accounts for 50% of the renal masses. Etiological factors could be PUJ obstruction, VUR, megaloureter, VUJ obstruction, duplex system, posterior urethral valves, bladder outlet obstruction.
- Multicystic dysplastic kidney disease
- Autosomal dominant polycystic renal disease
- Autosomal recessive polycystic renal disease
- Tuberous sclerosis
- Neuroblastoma: second commonest abdominal mass found in children after Wilm's tumour
- Adrenal haemorrhage
- Other adrenal masses are pheochromocytomas (extremely rare) and adrenal carcinoma
Hepatic masses: Hepatic masses in childhood are relatively uncommon.
Focal hepatic masses
- Hepatoblastoma: Third commonest malignancy seen in childhood after Wilm's tumour and neuroblastoma.
- Hepatocellular carcinoma
- Hemangioma and hemangioendothelioma
- Metastasis - Wilm's, neuroblastoma, lymphoma, leukemia, rhabdomyosarcoma
- Mesenchymal hamartomas
- Adenomas, teratomas
- Infection- amoebic/pyogenic abscess, hydatid cyst
Diffuse hepatic lesion
- Hepatomegaly: Glycogen storage disease, fatty liver, infections (malaria, typhoid)
Other abdominal masses
- Mesenchymal & omental cyst
- Cystic teratoma
- Duplication cyst
- Ovarian cyst
- Pancreatic pseudocyst
Infections - Tuberculosis, HIV
Neoplastic - Lymphoma, Leukemia
- Appendicular abscess
- Undescended testis
- Splenic lesions: lymphoma, Gaucher's disease, abscess, cyst, hydatid, infection (malaria, typhoid).
Urinary tract infection:
It is the 1st line of investigation in any child with a proven urinary tract infection. Vesico-ureteric reflux may be demonstrated by non-invasive means with the aid of colour Doppler examination. Acute pyelonephritis, acute lobar nephronia, renal abscess, pyonephrosis, chronic pyelonephritis and neonatal candidiasis can also be detected.
The acute abdomen:
Appendicitis: commonest cause
Intussusception: diagnosis & treatment (hydrostatic reduction)
Mesenteric adenitis very limited role
The vomiting infant:
Hypertrophic pyloric stenosis
Duodenal obstruction - Malrotation & volvulus - Colour Doppler studies aid in the diagnosis by demonstrating SMV anterior or to the left of SMA
Ultrasound forms the first line of investigation to look for free fluid in the abdomen and injury (contusions/lacerations/hematoma) to the liver, kidney, spleen, pancreas & bladder.
Jaundice in the neonate:
Ultrasound helps to differentiate between neonatal hepatitis, biliary atresia and choledochal cyst- the three common cause of neonatal jaundice.
Medical renal disease:
- Acute and chronic glomerulonephritis
- Grading severity of parenchymal disease
- Nephrocalcinosis: cortical/medullary
- Medullary (common causes): Medullary sponge kidney, renal tubular acidosis, hyperparathyroidism, hypervitaminosis D, hypercalcemia, hypercalciuria, milk alkali syndrome, hyperoxaluria
- Cortical - Glomerular nephritis
USG AND PEDIATRIC CHEST- Identification of pleural effusion and to provide guidance for tapping
- Evaluation of diaphragmatic motion to assess diaphragmatic paralysis
- Differentiate between cystic/solid intrathoracic mass.
- Evaluation of diaphragmatic hernia
- Diagnosis of pericardial effusion
- Differentiate chest wall mass from pleural effusion
- Guidance of needle aspiration biopsy of masses or fluid collection
- Characterisation of mediastinal masses
- Detection of extension of neck masses into the chest
USG AND PEDIATRIC HEAD AND NECK MASSESInformation of the salivary glands: Acute/chronic parotitis
Lymphadenopathy: inflammatory, infective, sarcoidosis, lymphoma
- Lymphangiomas/cystic hygromas
- Salivary gland tumours - pleomorphic adenomas of parotid gland
- Mucoepidermoid carcinomas
- Undifferentiated sarcoma
Brachial cleft cysts/sinuses
Encephalocele/ cervical meningocele
Doppler imaging useful in identifying erratic carotid artery, pseudoaneurysm
Pathologies of the thyroid gland
- Inflammatory: Acute suppurative thyroiditis, Hashimoto's thyroiditis, Turner's, Noonan's syndrome, Down's syndrome, treated Hodgkin's lymphoma, dilantin therapy
- Neoplasms: Adenoma, Papillary carcinoma, Follicular carcinoma - rare, Medullary carcinoma - rare
Multinodular goitre, Multiple thyroid cyst - McCune Albright syndrome
- Congenital lesions: Thyroglossal cyst, Congenital goitre, Congenital cyst - very rare, Thymic cyst
USG AND PEDIATRIC SPINAL CANALSonographic study of the intact spinal canal is unique to paediatric age group because of the incomplete ossification of the posterior elements.
- To determine the level of conus medullaris - look for tethered cord
- Myelomeningocele, meningocele, lipomyelomeningocele, hydromyelia, syringomyelia, syringohydromyelia, diastematomyelia
USG AND PEDIATRIC PELVISCongenital anomalies of the uterus & vagina:
- Bicornuate, unicornuate and T shaped uterus
- Obstruction of the vagina resulting in hydrocolpos or hydrometrocolpos (vaginal atresia, imperforated hymen, vaginal septum)
- Uterine hypoplasia
- Streak ovaries: Turner's syndrome
Neoplasms of uterus:
- Endodermal sinus tumour
- Adenocarcinoma of cervix
- Carcinoma of vagina (h/o in utero exposure to diethylstilbestrol)
- Gartner's duct cyst
- Paramesonephric (Mullerian) duct cyst
Neoplasms of ovary:
- Ovarian cysts
- Primary ovarian tumours:
Germ cell tumours: Benign teratoma, dysgerminoma (common),embryonal cell carcinoma (rare), endodermal sinus tumour (rare)
Epithelial tumours: Serous & mucinous adenocarcinoma are rare before puberty
Stromal tumour: Granulosa theca cell tumour
New born infant with ambiguous genitalia to look for presence / absence of uterus and vagina.
Investigation for primary amenorrhoea - to assess uterine - size, shape & maturity, ovarian development
- Turner's syndrome (ovarian absent or streak)
- Swyer's syndrome (pure gonadal dysgenesis)
- Noonan's syndrome (pseudo-Turner's syndrome)(normal ovarian function & normal ovaries on ultrasound)
- Testicular feminization: Absent uterus & ovaries, blind ending vagina. Testis are ectopic (pelvic).
Precocious puberty: Uterus enlarged and ovarian volume > 1cc before the age of 8 yrs.
- Pseudoprecocious puberty: Usually secondary to ovarian tumours -> granulosa theca cell tumour, dysgerminoma,functional ovarian cyst, teratoma, choriocarcinoma, feminizing adrenal tumours.
USG AND PEDIATRIC SCROTUM -
Undescended testis: Commonest ectopic location being the inguinal canal
- Hydrocele: Due to patent processus vaginalis, infection, inflammation, trauma - hematocele, tumour
- Testicular torsion: Colour Doppler imaging is used to differentiate torsion from acute epididymo-orchitis.
- Scrotal hernia
Primary testicular neoplasms
Germ cell tumours: endodermal sinus tumours, embryonal carcinoma. Rarely: Seminoma, teratocarcinoma and choriocarcinoma.
Non germ cell tumours:
Leydig cell tumours - precocious puberty
Sertoli cell tumour - feminization
Metastasis from neuroblastoma
- Trauma: contusion, hematoma or rupture of testis, hydrocele
- Varicoceles Post-pubertal males
- Spermatoceles Post-pubertal males
DOPPLER EXAMINATION OF THE ABDOMEN- Evaluation of the splanchnic venous system in the child with portal hypertension
- Assessment of the renal circulation in trauma and disease affecting the main renal arteries, veins or small intra renal vessels.
- Determination of patency of vessels (aorta and inferior vena cava), especially following surgery or in the presence of tumours
- Evaluation of acute scrotal disease (torsion v/s epididymo-orchitis)
- Assessment of vascularity and rejection of transplant organs (kidney, liver)
- Identification of unknown structure (tortuous portal vein versus dilated bile duct, dilated vein versus dilated ureter or lymphatic channel)
- Identifying refluxing or obstructed ureter by the abnormal urine jet it emits into the bladder.
- Distinguishing obstructive hydronephrosis from other causes of urinary tract dilatation by assessing intra-renal arterial resistance
- Defining malignant nature of a mass by its abnormal vascularisation
ORBITAL ULTRASOUND- To study the posterior segment in case of congenital cataract, corneal opacity
- Evaluation of Vitreo-retinal disorders
- Identification & localisation of intraocular foreign body
- Diagnosis & follow up of ocular tumours - retinoblastoma, metastasis (neuroblastoma, Ewing's sarcoma, lymphoma), optic nerve glioma, rhabdomyosarcoma, dermoid cyst
- Infections: cellulitis, orbital abscess, cysticercosis, hydatid cyst
Colour Doppler flow imaging
- Evaluation of ocular tumours
- Study of vascular disorders of the orbit-central retinal artery or vein occlusion, carotico-cavernous fistulae
- Orbital trauma