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M. Riccabona
6.3 US inOther Common Paediatric Abdominal Conditions
andQueries
There are numerous other conditions where US is used as the rst and often only
imaging method, sometimes supplemented by radiographs (or even uoroscopy); in
particularly early childhood the need for MRI and CT is far less than in adults, in
part because of better US applicability and potential (better access, higher resolution transducers applicable, less fat) and in part because of different common queries (less tumours, diverticulitis or perforation or vascular problems such as superior
mesenteric artery emboli rarer).
6.3.1 Necrotizing Enterocolitis (NEC)
In neonates NEC poses an indication for US: meticulous assessment of the bowel,
the bowel wall and the portal vein for potential gas emboli.
Note Remember that pneumatosis or portal venous gas in itself is not a proof for
NEC as there may be other causes—only in connection with clinical information
may this nding supports the diagnosis of NEC.
• US done also for follow-up to depict potentially gangrenous parts or to asses for
perforation and free air (provided proper scanning technique without too much
pressure—“curtain phenomenon”).
Supplementing imaging consists of radiographs, and in follow-up/after surgery
sometimes uoroscopy (e.g., for bowel stenosis) may be necessary (although often
also addressable by US enema—“hydrocolon”, see respective chapter)
6.3.2 Vomiting Infants andChildren
Another common query. Depending on age and history as well as clinical nding
US is indicated:
• Strong suspicion for hypertrophic pyloric stenosis.
• Persistent gastroesophageal reux (GER) in a child with reux disease, to look
for other causes such as malrotation or an intermittently posing hiatal hernia.
Note Normal GER without GER disease or other clinical symptoms/persisting
does not need to be imaged. If performed, gastric lling is needed—as a full
stomach with provocation maoevers is necessary to depict GER or hiatal hernia
(see respective chapter).
Additional complementing imaging if US unclear: Fluoroscopy (pH-metry)
6 Imaging andImaging Algorithms forCommon Queries inChildhood
97
6.3.3 Acute Abdomen
In neonates a sudden onset acute abdomen always raises the suspicion of a volvulus.
This can be addressed by US and is an emergency examination; US should focus
on mesenteric vessels and the course of the duodenum and jejunum.
• Sometimes lling of stomach and duodenum is necessary to see its path and the
typical whirlpool sign nding on US—this then is diagnostic and does not need
any further study before emergency operation.
The same applies in slightly older infants and toddlers for ileocoecal
intussusception
• US = the only diagnostic imaging tool (supplemented by plain rm) can also be
used for image-guided (hydrostatic) reduction.
• US also used for follow-up after successful reduction.
• US furthermore valuable for differential diagnoses such as polyps or infantile colitis.
Acute abdomen in older children: usual queries are ileus, perforation/perforated
appendicitis, renal or biliary colic (see respective entry), ovarian torsion (see respective entry); some rarer entities exist too.
• US = initial imaging, supplemented by radiographs.
• Depending on ndings and availability/emergency, uoroscopy, CT or MRI may
become necessary in the individual case with unclear US results.
6.3.4 Acute Appendicitis
Very common query.
US commonly used as rst imaging—provided there is not already a clinically
clear picture with the decision to go for surgery.
• Particularly in girls (where the DDx of potential ovarian conditions is clinically
difcult) US (preferably with full urinary bladder) is rst and usually only necessary imaging.
• US also used for follow-up, particularly in a complicated course postoperatively.
• US used for DDx such as Meckel’s diverticula, other inammatory bowel diseases and similar conditions.
Rarely CT (or MRI) necessary (e.g., obese children with restricted US access).
6.3.5 Splenomegaly
A very common query—but due to the poor reproducibility of measurements, value
of US questionable, particularly if enlarged spleen already obvious on palpation; the
same applies to liver, too.
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Note US not very specic in terms of diagnosing a specic cause (commonly sys-
temic or viral/reactive).
M. Riccabona
6.3.6 Cholestasis
In signs of cholestasis or upper abdominal colic US is the rst imaging modality
used to asses for bile duct dilatation or to depict a choledochal cyst.
Note Gall bladder pathology and cholecystolithiasis/cholecystitis much rarer in
children than in adults.
• US depicts gall stones (then search for the cause!) and helps DDx to other entities such as cholangitis, gall bladder involvement in systemic disease (e.g., in
Kawasaki disease), or a renal colic.
6.3.7 Pancreatitis
The normal childhood pancreatitis usually does not benet from an US examination, particularly as morphological changes will manifest delayed and persist long
after laboratory values have normalized.
• US indicated as rst line imaging in: recurrent pancreatitis, the history of a
potential malformation, an association with a choledochal cyst, severe complicated clinical course, with suspected haemorrhagic or necrotic components
(eventually leading to pancreatic cysts).
• US useful and often sufcient diagnosing and monitoring these conditions.
Complementing imaging: mostly MRI/MRCP and not-as commonly used in
adults—CT (for radiation protection—ALARA Principle).
6.3.8 Biliary Atresia
Relatively rare condition and query, early diagnosis essential for treatment and
prognosis.
• US: rst imaging modality should focus on assessment for direct or indirect
signs (see respective chapter) and be performed early to avoid treatment delay.
Note A normal gall bladder and US study cannot rule out moderate form of bili-
ary atresia
6 Imaging andImaging Algorithms forCommon Queries inChildhood
• Diagnosis eventually made by cholangiography; even histology can be misleading.
• There is no role for MRI in these queries in the initial work-up.
• US and MRI (CT) have role in follow-up, also before/after transplantation.
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6.3.9 Abdominal Trauma
In moderate blunt abdominal trauma US is the rst study.
• US should always include a meticulous Doppler and Power Doppler study of
the kidney.
– CEUS may be helpful in early settings where grey scale is less reliable—par-
ticularly for liver and spleen injuries.
• US is also used for follow-up, complimented by MRI (e.g., for suspected urinoma) (Ammerstorfer et al. 2015).
– Only in hyper-acute situations (unexpected decompensation, no MRI avail-
able or contraindicated) CT indicated.
In severe or multiple trauma contrast-enhanced trauma CT (after the eFAST
assessment in emergency room) indicated
• May also become necessary in cases where US suggests additional injuries or
cannot answer all relevant questions in acute setting.
• US often sufcient for follow-up, potentially complemented by CEUS and/or MRI.
6.3.10 Abdominal Tumours
US usually used as initial assessment tool. May incidentally pick-up a tumour
or mass.
Although US may quite correctly diagnose condition and describe extent, further
work-up and staging according to respective oncology protocols then mandatory.
• US important in follow-up during treatment (regression? response?) and with
complications.
6.4 Miscellaneous Other Common Queries andAssessment
forSystemic Conditions
6.4.1 Pneumonia, Pleural Effusion
The query pneumonia and effusion has become an accepted indication for US—
reducing need for radiographs, both in initial diagnosis and particularly on follow up. However, even if without radiation and easily accessible, same indications as for
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M. Riccabona
plain lm apply (e.g., persisting, no response to therapy or worsening, complicated
course, unclear clinical ndings).
Note Not every consolidation seen on US is pneumonia; additionally (due to intrin-
sic restrictions on acoustic windows) US cannot “rule out”, for example, central
pneumonia.
• US helpful in differentiating, for example, a sequestration from pneumonia or
other mass.
• US allows depiction of necrotizing pneumonia, abscess formation, or empyema
(septae are better seen than on CT!).
• US can guide puncture and treatment.
• Observation of diaphragmatic movement may aide treatment decisions.
Besides plain lm, MRI is becoming more and more fashionable for chest condi-
tions, too, for radiation protection issues; however, CT is still gold standard for most
chest queries, if therapeutically necessary information cannot be retrieved by US or
radiographs.
6.4.2 Enlarged Mediastinum
Common query in the chest of infants (after a plain lm) is an enlarged mediastinum.
• US = quick and easy tool to proof a normal thymus or depict another not another
mediastinal mass.
6.4.3 Painful Hip/Limping Child: Osteomyelitis
Query hip effusion quite common; the second query “Osteomyelitis” = emergency.
US done for hip (knee) effusion.
Note US cannot reveal the nature of the effusion = no DDx bacterial versus
viral by US!
Osteomyelitis: in early childhood often subperiosteal abscess and septic arthritis
present—US valuable in initial assessment, may show ndings earlier than
radiographs.
• In older children US less useful.
Additional imaging: radiographs, MRI (scintigraphy?).
6 Imaging andImaging Algorithms forCommon Queries inChildhood
101
6.4.4 US inSystemic andSyndromatous Disease
Many syndromes and systemic conditions with involvement of various organs and
organ systems
• US used to monitor these diseases/its manifestations (e.g., tuberous sclerosis,
angiomyolipoma).
Note US can be done in many of these conditions (e.g., genetic tumour predisposi-
tion syndrome or neurobromatosis) to potentially detect a tumour, but never can
“rule out” (e.g., neurobroma commonly develop in retroperitoneal space and may
easily be missed by US). That means not everything that can be scanned must be
scanned.
In all these conditions one needs to remember that although US is non- irradiating,
it is medical diagnostic imaging and needs a justifying indication that has an impact
on therapy; according to the authors opinion “parents wish” or “pacifying relatives”
(or potential referring doctors) is not a strong indication for performing a study.
Measurements andVolume Calculations:
Basic Considerations, Graphs
andIllustrations forStandardisation
MichaelRiccabona
7.1 General Considerations
Basically, every organ or structure can and often should be measured, particularly
important in paediatric US—as sizes vary with age, also correlated with patient
weight/size.
Note Measurements are for orientation and not always reliable and may vary sig-
nicantly even within one investigator during same examination. Thus diagnosis
cannot be based on only a single measurement—the overall picture and function
must be considered.
For example, particularly preterm/very young babies who develop hypertrophic
pyloric stenosis may not really reach given cut-off values for pyloric diameter and
length (see respective chapter). However, when observing gastric emptying signicant stenosis with insufcient passage through the pyloric canal constituting the
respective diagnosis may be obvious—in spite of smaller measurement numbers.
7
7.2 How toMeasure
Measurements are always performed in longitudinal and axial sections and documented—either as 2-D distance or planimetric denition of (manually) dened
outline. Depending on the organ these orientations are dened by body or by organ
axes (e.g., liver=sagittal sections, kidney=organo-axial measurements …).
M. Riccabona (*)
Department of Radiology, Division of Pediatric Radiology, Medical University Graz
and University Hospital Graz, Graz, Austria
e-mail: michael.riccabona@klinikum-graz.at
© Springer Nature Switzerland AG 2020
M. Riccabona (ed.), Pediatric Ultrasound,
https://doi.org/10.1007/978-3-030-47910-7_7
103
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M. Riccabona
All measurements are performed in standardised, representatively oriented and
reproducible sections that grant optimal depiction of maximal length and diameters.
Lead structures should be documented with respective image (e.g., upper pole of
right kidney for liver length in anterior axial line, abdominal aorta with liver length
in sternal line …).
Volume calculations can/should be performed and may be more reliable in some
organs; calculations use mathematic equations based on a geometric shape that
resembles the shape of respective organ (e.g., kidney = rotational ellipsoid)
(Fig.7.1).
Organ sizes are assessed according to age-matched normal values:
• Partially (e.g., liver, spleen, and pancreas) distance measurements at standardised
sections are sufcient (see Fig.7.1).
• For other organs, volume calculations are preferred due to inaccuracies or inadequate meaning of 2D distance measurements (e.g., kidney, bladder)—volumes
are estimated using equations based on geometrical pre-assumptions (e.g., ellipsoid equation=L×W×D×correction factor, usually 0.523). These mathematic
estimations sometimes are inaccurate, as organs may exhibit irregular or a different shape as usual; planimetric approaches or 3DUS-based volumetry may
improve results (Fig7.2a, b). Correction factors should be adapted if underlying
geometric shape does not reect shape of measured organ; e.g. in a rather rectangular/cubical shape of the urinary bladder the correction factor is around 1 (as
equation for volume of a cuboid=L×H×D) (Fig7.2c). The applicable correction factor varies with organ—e.g. in the thyroid gland it differs from the kidney
(Table7.1).
• Some structures cannot be properly assessed by volume calculations, then standardized distance or area/circumference measurements are used (e.g., neurosonography, Fig. 7.3). Try to measure relevant structures—e.g. assess not just
ventricular size, but also brain itself, too (Fig.7.3c).
• Ratios can help to follow-up changes of these structures with growth (e.g.,
increase in ventricular size but also in brain parenchyma width), an aspect not
present in adult sonography. Ratios also useful to describe and dene shape (e.g.,
lymph nodes dened by ratio of length and depth, with ratios approaching 1
indicating a higher probability of pathologic nodes).
Always compare measurements/volumes with age/size matched normal val-
Note
ues and check internally preset correction factors of device if using the device’s
calculation program.
• Measurements must be obtained in proper section and—particularly for volume
estimations—respective sections must be acquired in orthogonal views to avoid
signicant errors, and respective borders must be clearly seen on the screen
(Fig. 7.4). Wrong measurements and volume calculations may have serious
implications on patient management!
bc
7 Measurements and Volume Calculations: Basic Considerations, Graphs…
a
105
d e
Fig. 7.1 Schematic drawing of some organs where US measurements are commonly applied.
Organ shape and relevant measurement axes are given. The equation for calculating the volume
and age-adapted normal value charts can be found in the respective organ chapters, the chapter on
normal values, and textbooks. Additionally, typical images with correct measurements (arrows) are
displayed for liver sagittal length in VAL (b) and STL (c), as well as for the kidney in a hilar
organo-axial section with 2 orthogonal diameters (d) and renal length measurement (e). 1 sternal
line (STL), 2 right anterior axillar line (MCL), 3 ventral axillar line (VAL), 4 spleen length, 5
spleen depth/width, l renal length, w renal width, d renal depth
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acb
Fig. 7.2 (a–c)Volume calculations based on diameter measurements: (a) 3DUS of the kidney for
volume calculation (gray structure in lower right case) after segmenting and delineating the renal
outer contour in three orthogonal planes. (b) In this kidney with a dilated collecting system, 3DUS
allows to segment the pelvicalyceal structures (white, lower right case) to then be subtracted from
the overall renal volume—enabling a more accurate assessment of the pure renal parenchymal
volume. (c) This urinary bladder (cross section in lower abdomen) exhibits a rather rectangular and
not an ellipsoid shape—therefore the correction factor usually used for bladder volume calculations of 0.523 is incorrect and should be changed to 1
Table 7.1 Volume calculation of thyroid
Schematic drawing: How and where to take measurements for volume
assessment; correction factor usually=0.48, but only applies in
regular thyroid shape.
M. Riccabona
Each lobe is calculated separately and then both lobes are added, neglecting the isthmus.
Additionally, and age/weight correlated growth chart is displayed
Abbreviations: w width, d depth, and l length
• For measurements of large vessels, the variation between systole and diastole
needs to be considered.
• Some structures are assessed by angle measurements, e.g. neonatal hip for
evaluating developmental hip dysplasia using the Graf method (see respective
chapter). Angle measurements are also important for quantitative Doppler
velocity measurements. As all these are 3-dimensional structures that may also
curve in an out-of-plane direction these measurements are again only the best
achievable compromise and may differ from reality. Nevertheless, try to avoid
tilting transducer and thus obtaining unrepresentative projections that worsen
these effects.