Diagnostic ultrasound ( PDFDrive )

1792 PART V Pediatric Sonography
A
B
FIG. 52.23 Urachal Remnant. (A) and (B) Transverse and longitudinal images depict the hypoechoic, elliptical urachal remnant (*) in the
anterosuperior bladder wall. B, Bladder.
sensitivity of scar detection. 64,65 Because mild scars do not alter
the course of therapy, the radiation dose of a renal cortical scan
is not required 66-69 and the increased time and expense of Doppler
sonography may also be avoided.
FIG. 52.24 Vesicourachal Diverticulum. Longitudinal image reveals
a diverticulum (arrows) arising from the bladder dome and extending
superiorly. B, Bladder; U, umbilicus.
and to detect the presence of VUR. Nuclear cystography can
also be used for diagnosis of VUR and is associated with a lower
radiation dose to the gonads in boys. In some centers nuclear
cystography is used as the initial study for girls with normal
renal and bladder sonograms, because girls rarely have urethral
abnormalities. Some centers also use it to follow relux in all
children. At Boston Children’s Hospital, we recently introduced
contrast-enhanced VCUG and plan to eventually pilot its use in
the follow-up of patients with prior VCUG documentation of
VUR, as an initial imaging study in selected patients with normal
ultrasound imaging of the kidneys and bladder, and in patients
whose parents have serious concerns about radiation exposure
(see Fig. 52.20, Video 52.2, Video 52.3, Video 52.4).
Diuretic renography with MAG3 can be performed to differentiate
between obstructive and nonobstructive causes of renal
or ureteral dilation, and to assess renal function. 30,63 Renal nuclear
scintigraphy with 99m Tc dimercaptosuccinic acid (DMSA) is
extremely sensitive for demonstrating focal areas of inlammation
and parenchymal scarring. Although mild scarring may be missed
with sonography, power Doppler sonography increases the
Acute Pyelonephritis
Acute pyelonephritis is one of the most serious bacterial illnesses
of childhood. It may be diagnosed clinically in patients with a
sudden onset of fever, lank pain, costovertebral angle tenderness,
and microscopic evidence of urinary infection. VUR is clearly
a risk factor for the development of acute pyelonephritis, which
oten starts as an ascending infection from the bladder. It can
also occur by hematogenous spread. In infants, symptoms are
oten ambiguous, and fever is not always helpful in identifying
patients at risk for complications of acute pyelonephritis such
as sepsis and meningitis. 70,71
In general, there are few indings of acute pyelonephritis on
conventional gray-scale sonography. here may be swelling of
the infected kidney and altered renal parenchymal echogenicity
from edema causing triangular areas of increased echogenicity
or rounded hypoechoic zones. Focal pyelonephritis can appear
sonographically as a localized mass with abnormal echogenicity
compared with the remainder of the kidney and loss of corticomedullary
diferentiation (Fig. 52.26). here may be thickening
of the wall of the renal pelvis and ureter, also caused by edema
and inlammation 72 (Fig. 52.27). Sequential examinations of these
focal infected areas will typically demonstrate a rapid change,
with resolution of the mass in response to antibiotic therapy.
Power Doppler sonography, DMSA scintigraphy, computed
tomography (CT), and magnetic resonance imaging (MRI) may
all show absent or decreased perfusion in a difuse or lobar
distribution, especially in the upper or lower poles. 73 CEUS has
also been used to identify adults with acute pyelonephritis, 74 but
there have been no reports yet regarding its use in children.
When patients with UTIs do not respond rapidly to antibiotic
therapy, repeat sonographic and/or CT examinations are indicated
to search for complications that require drainage.
Acute lobar nephronia is a localized, nonliquefactive, severe
interstitial bacterial infection of the renal parenchyma. Sonography