Diagnostic ultrasound ( PDFDrive )

CHAPTER 5 The Spleen 145
of assessment requires considerably more experience than is
necessary for other imaging techniques and is relatively inaccurate.
Various clinicians have used diferent methods to measure splenic
size. he length of the spleen measured on a coronal or coronal
oblique view that includes the hilum is the most common
technique 11,12 (Fig. 5.8). his view can be obtained during deep
inspiration or quiet breathing. Importantly, this method correlates
well with the splenic volume, particularly when performed with
the patient in the right lateral decubitus position. 12
Multiple studies have tried to establish nomograms of spleen
size. In a study of 703 normal adults, the length of the spleen
was less than 11 cm, the width (breadth) less than 7 cm, and
the thickness less than 5 cm in 95% of patients. 13 Rosenberg
et al. 11 established an upper limit of normal splenic length of
12 cm for girls and 13 cm for boys (≥15 years). Hosey et al. 14
demonstrated a mean splenic length of 10.65 cm. In this study,
men also had larger spleens than women. Spielmann et al. 15
showed that the length of the spleen correlates with height and
established nomograms for tall, healthy athletes. In women taller
than 5 feet (t), 6 inches (168 cm), the mean splenic length of
10 cm increased by 0.1 cm for each 1-inch incremental increase
in height. In men taller than 6 t (180 cm), the mean splenic
length of 11 cm increased by 0.2 cm for each 1-inch incremental
increase in height. Upper limits of normal in splenic length were
14 cm in women 6 t, 6 inches (198 cm) tall and 16.3 cm in men
Length
Width
Longitundinal section
Diaphragm
FIG. 5.8 Splenic Measurement. Diagram shows sonographic approach
to measuring splenic length and width. Splenic size is best measured
by obtaining a coronal view that includes the hilum.
7 t (213 cm) tall. Chow et al. assessed 1230 healthy volunteers
and found that spleen length and volume were signiicantly and
independently associated with sex, body height, and weight, with
men and taller and heavier individuals having longer and
larger spleens. he spleen length of 20 of 324 women (6%) and
234 of 906 men (26%) exceeded a strict upper limit of normal
of 12 cm. 16
PATHOLOGIC CONDITIONS
Splenomegaly
he diferential diagnosis of splenomegaly is exceedingly long.
It includes infection (e.g., mononucleosis, tuberculosis, malaria),
hematologic disorders (myeloibrosis, lymphoma, leukemia), 17
congestion (portal hypertension, portal/splenic vein thrombosis,
congestive heart failure), inlammation (sarcoidosis), neoplasia
(hemangioma, metastases), and iniltration (e.g., Gaucher
disease) 18 (Table 5.1).
Frequency and causes of splenomegaly vary between developing
and developed countries and even between hospitals in the
same region. 19 Sonography is very helpful in determining the
degree of enlargement. In “borderline” splenomegaly, however,
diagnosis can be diicult.
he spleen is capable of growing to an enormous size. It can
extend inferiorly into the let iliac fossa, and it can cross the
midline and appear as a mass inferior to the let lobe of the liver
on longitudinal section. he degree of splenomegaly is generally
not a reliable tool in providing a more concise diferential
diagnosis. he diferential diagnosis of massive splenomegaly,
deined as a spleen size greater than 18 cm, is less extensive and
includes hematologic disorders and infections 18 (see Table 5.1).
Sonographic assessment of the splenic architecture is used to
diferentiate between focal lesions (single or multiple) causing
splenomegaly and difuse splenomegaly.
he most common inding is difuse enlargement; in these
patients, imaging is typically not helpful in providing a speciic
diagnosis. When the spleen enlarges, it can become more
echogenic, but the clinician cannot diferentiate between the
diferent types of splenomegaly on the basis of its echogenicity
(see Fig. 5.7B). In experimental studies researchers have tried
to quantify the degree of ibrosis in liver and spleen using the
echotexture characteristics, but no clinical applications have yet
been established. 20 More promising is the use of splenic elastography
in patients with portal hypertension. Studies have shown
that use of elastography in patients at risk for cirrhosis can lead
to improved triage of patients with respect to degree of liver
ibrosis 21,22 as well as esophageal varices and bleeding. 23
Associated clinical and radiologic features can be helpful in
establishing a diferential diagnosis. Liver disease and evidence
of portal venous collaterals can establish portal hypertension
as the cause of splenomegaly (Fig. 5.9). Focal lesions, multiorgan
involvement, and lymphadenopathy may indicate lymphoma.
However, in many patients, extensive radiologic and laboratory
investigations will fail to yield a diagnosis. In these cases of
“isolated” splenomegaly, the risks of serious underlying disease
must be balanced against the risks of further invasive