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268
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J. H. Bortz
nias causing small bowel obstruction [39].
Obstruction of the colon by abdominal wall hernia is uncommon. Obstruction of small bowel is
best diagnosed on multi-detector CT (MDCT)
scans showing dilated bowel proximal to the hernia and normal or reduced calibre or collapsed
bowel distal to the obstruction [39].
• Strangulation may be caused by incarceration
when there is free uid within the hernia sac,
bowel wall thickening is present or bowel is
dilated. If the blood supply is compromised,
then ischaemia or strangulation occurs. This
happens when there is obstruction to the afferent
and efferent loops by the hernia defect [39].
• Incarceration occurs when a hernia cannot be
reduced or pushed back manually and diagnosis
18.8.5 Surgical Repair Procedures
may be suggested if a hernia occurs through a
small defect and the hernial sac has a narrow
neck. Incarceration may predispose to obstruction, inammation or ischaemia. The latter
occurs due to a compromised blood supply [39].
Surgical procedures for abdominal wall hernias
repair vary from open repair to laparoscopic
suture repair with or without the use of mesh.
Figure18.7 g shows repair of an inguinal hernia.
a(i) a(ii)
b(i) b(ii)
Fig. 18.7 (a) (i) 2D supine axial view showing left femo-
ral hernia containing loops of small bowel (Courtesy of
Prof D Kim, Wisconsin University). E4 classication:
high clinical importance. (ii) 2D coronal supine view
showing a loop of small bowel in a left femoral hernia.
Mild proximal dilation of small bowel is present indicat-
ing partial obstruction (Courtesy of Prof D Kim,
Wisconsin University). E4 classication. (b) (i) 2D axial
view showing the presence of small bowel hernias in both
inguinal canals (yellow and red circles). (ii) 2D right
supine sagittal view showing small bowel hernia (yellow
circle).
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening
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b(iii) b(iv)
b(v) b(vi)
269
c(i) c(ii)
Fig. 18.7
small bowel hernia (red circle). (iv) 2D right decubitus
view showing left hernia (red square) and right hernia
(yellow circle). (v) 2D supine coronal view showing bilateral small bowel hernias (yellow and red arrows). (c) (i)
(b)
(iii) 2D left supine sagittal view showing
2D supine axial view showing bowel in left inguinal hernia (white hexagon) and fat in right inguinal hernia (red
hexagon). (ii) 2D supine sagittal view showing bowel in
the scrotum (red arrow) and small area of narrowing as it
exits the inguinal canal (green arrow).
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d e(i)
e(ii) e(iii)
J. H. Bortz
Fig. 18.7
showing collapsed small bowel loops containing barium
in a right direct inguinal hernia (red arrow). Left side
shows a small direct inguinal hernia containing fat (red
circle) with vessels displaced medially (white lines). (e)
(i) Colon-map supine showing small bowel inguinal hernia (white arrow) on the right. (ii) Supine colon-map of
(d) 2D axial scan of an abdominal CT study
large bowel with small bowel removed. (iii) Colon-map
with small bowel removed showing herniation of sigmoid
colon (S). R=rectum; DC=descending colon; TC=transverse colon; AC = ascending colon; C = caecum. Red
arrows indicate direction of ow of CO
sigmoid colon.
from rectum to
2
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening
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f(i) f(ii)
g
271
Fig. 18.7
bowel in right inguinal hernia (red hexagon). E4 classication: high clinical importance. (ii) 2D axial supine view
showing a right inguinal containing fat (red hexagon) and
(f) (i) 2D axial supine image showing small
The most commonly used method is ‘tensionfree’ mesh repair and is regarded as the standard
surgical technique for the majority of cases.
Complications of surgical repair may involve up
to 50% of cases. Hernia recurrence is the most
common one irrespective whether mesh is used
or not. Fluid collection after surgery may occur
as well as infection [39].
18.9 Air inVagina
Vaginal air may be seen on 2D images; thus, it is
important to carefully examine these images to
exclude pathology causes as an ECF [45]. Table18.4
lists normal causes of air in the vagina. Figure18.8a
(i, ii) shows no air in the vagina. Figure18.8a (iii)
shows air between vulva folds. Figure18.8a (iv, v)
shows air in the vagina due to yoga stretching.
a small left inguinal hernia containing fat (yellow hexagon). E3 = moderate clinical importance. (g) 2D axial
supine view showing repair of right inguinal hernia (red
hexagon). Red arrow=left inguinal hernia
Table 18.4 Normal causes of air in vagina
Sexual intercourse
Insertion of objects into the vagina (e.g., pessaries or
speculum)
Tampon insertion
Exercise or stretching (e.g., stretching in yoga)
a
Adapted from Bortz [45]
a
It is important not to not mistake air between
vulva folds as air in the vagina. If air is present it
may be one or two bubbles that are rounded, horizontal, vertical, or curvilinear (Fig. 18.8b (i)–
(v)). A cluster of bubbles may indicate an
underlying infection or malignancy. Pathological
conditions that show air in the vagina are presented in Table18.5. Figure18.8c (i)–(iii) shows
a rectovaginal stula at a CTC study.
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J. H. Bortz
a(i) a(ii)
a(iii) a(iv)
a(v)
Fig. 18.8 (a) (i) 2D axial viewing showing normal
vagina without air (open black arrows) and rectal catheter.
(ii) Sagittal view showing no air in the vagina (V). Rectal
catheter (C). Rectum (R). (iii) Axial supine view showing
air between vulval folds. White circle= rectal catheter.
(iv) 2D axial view showing a large amount of air in the
vagina (white arrow). R=rectum; circle=catheter. This
air was caused by yoga exercises. (v) Sagittal view showing a large amount of air in the vagina (white arrow) post
yoga exercises
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening
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273
b(i)
b(iii)
b(v)
b(ii)
b(iv)
Fig. 18.8
the vagina (open white arrow). Circle=rectal catheter. (ii)
2D axial view showing two small air bubbles in the
vagina. Circle=rectal catheter. (iii) 2D axial view showing curvilinear air in vagina (open white arrow).
(b) (i) 2D Axial showing solitary air bubble in
Circle=rectal catheter. (iv) 2D axial showing a triangular
shape air bubble air (open white arrow). Circle= rectal
catheter. (v) 2D view showing air in the vagina (open
white arrow)
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J. H. Bortz
c(i) c(ii)
c(iii)
Fig. 18.8
(c) (i) Sagittal view showing air in the vagina
(A). Rectovaginal stula = bottom white line. Rectum
(R); Uterus (U). (ii) 2D prone axial demonstrates a stulous tract (open black arrow) between the rectum (C=rec-
Table 18.5
Inammatory bowel disease, especially Crohn’s
disease
inammatory bowel disease
Pelvic malignancies arising from the cervix or uterus;
vaginal secondaries from breast cancer or melanoma
Radiotherapy to the pelvis
Recto or colo-vaginal stula
Pelvic oor dysfunction or prolapse following
childbirth, enterocoele, rectocoele, or vaginal prolapse
a
Das and Snyder [46]
b
Bortz [47]
c
Bortz [45]
d
Krissi etal. [48]
Air in the vagina due to pathology
a
. CTC is not performed on patients with
b
a
a
c
d
18.10 Comparison ofECFs
andClinical Outcomes at
Screening andDiagnosticCTC
A recent comparative study was done to determine
the distribution of ECFs and clinical outcomes in
388 patients who underwent screening and diag-
tal catheter) and the vagina (open white arrow).(iii) 2D
close-up view showing the rectovaginal stula. Open
black arrow=stulous tract; open white arrow=air in the
vagina; C=rectal catheter
Table 18.6
Total ECFs
a
E classication Percentage of n=388
E1 and E2 88.4% (n=347)
E3 4.4% (n=17)
E4 7.2% (n=28)
a
Adapted from the text of Taya etal. [49]
nostic CTC studies [49]. The majority (262/68%)
had screening CTC studies compared to the diagnostic CTC cohort (126/32%). The majority (84.%)
had E1 and E2 ECFs as shown in Table18.6. The
distribution of ECFs distribution and clinical outcomes showed there was no statistically signicant
difference between the screening and diagnostic
CTC population (4.4%/4.0%) [49].
Key Messages
• Extracolonic ndings are an integral part of a
CTC examination and must be reported on even
if the examination is considered non-diagnostic.
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening
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275
• Although the number of ECFs are high, only a
small percentage are of signicant clinical
importance.
• A low-dose technique without intravenous
contrast is used.
• The most common ndings include abdominal aortic aneurysm, renal carcinoma, lymphadenopathy, and ovarian tumours.
• Opportunistic screening for bone mineral density should be included in a CTC study.
• When a hernia containing bowel is visualised,
it is important to determine whether it is
reducible or whether obstruction,
incarceration, or strangulation has occurred
and which bowel (large or small) is involved.
• A cluster of bubbles in a vagina may indicate
an underlying infection or malignancy.
18.11 Summary
Detection of ECFs is an unavoidable responsibility of the radiologist or radiographer who interprets the CTC images. Most ECFs are determined
to be clinically inconsequential on CTC and most
patients do not have further testing. A disclaimer
should be in CTC reports, namely that the lack of
intravenous contrast material and low-dose technique limit the evaluation of CT ndings outside
the colon. It is essential to report ECFs in poor
quality non-diagnostic CTC studies to ensure that
if the abnormalities are deemed to be clinically
important this will result in further diagnostic
studies or medical/surgical follow-up.
Acknowledgement Professor David Kim from
Wisconsin University is thanked for providing examples
of a femoral hernia.
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Metabolic-Associated Fatty Liver
https://t.me/medicina_free
Disease: Opportunistic Screening
at CT Colonography
JoelH.Bortz
19
19.1 Introduction
In this chapter, the novel term metabolicassociated fatty liver disease (MAFLD) previously termed non-alcoholic fatty liver disease
(NAFDL) [1, 2] is used. According to a group of
experts, the term non-alcoholic fatty liver disease (NAFLD) does not reect current knowledge associated with fatty liver disease in terms
of associated metabolic dysfunction [3]. They
suggest the use of metabolic-associated fatty
liver disease (MAFLD) as an overarching term
to cover specic metabolic conditions in terms
of inclusion criteria compared to the exclusion
criteria of NAFLD.This suggested term is supported by many international patients because
the term NAFLD is not acceptable in terms of
their religious, cultural, and spiritual beliefs [4].
The use of alcoholic in the term to describe their
clinical condition leads to them being stigmatised; they therefore support the suggested use
of MAFLD [4].
The global prevalence of metabolic-associated
fatty liver disease (MAFLD) has increased by
25% [5, 6]. Such a prevalence could lead to a
clinical and economic burden [7]. In radiology,
opportunistic screening is the practice of maximum use of imaging data, unrelated to the clinical indication, for risk proling and prevention of
J. H. Bortz (*)
LSG Imaging, Los Angeles, CA, USA
relevant disease [8]. According to Pickhardt [8],
opportunistic screening allows for early detection
of, for example, liver fat content on unenhanced
scan. AI-based CT tools or manual region of
interest (ROI) assessment can be used in opportunistic screening of the liver [8]. It is therefore
important that the liver should be carefully
assessed during screening CTC as it allows visualisation of the colon as well as extracolonic
structures [9, 10]. The examination includes visualisation of the liver as an extracolonic organ; unenhanced images of the liver and spleen are
obtained. A reader can compare these two organs’
respective CT attenuation values (Hounseld
units/HU) [11]. This allows for differentiation
and quantication of visceral and subcutaneous
fat; liver fat (steatosis) can be accurately quantied [12]. Moderate steatosis is when unenhanced
liver attenuation under 40 HU corresponds to
15% proton fat fraction calculated from MRI [8].
In the absence of multiple blood transfusions, or
amiodarone therapy, if the attenuation of unenhanced liver exceeds 75HU then iron overload
must be considered [8].
Steatosis used to be considered a self-limiting
and relatively benign condition, but is now recognised as a typical feature of MAFLD (formerly
NAFLD), which may lead to non-alcoholic steatohepatitis (NASH/MASH), and even cirrhosis
[13, 14]. Figure 19.1a and b are examples of a
normal liver and hepatic steatosis. MAFLD is an
extracolonic nding (ECF) which needs to be
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
J. H. Bortz et al. (eds.), CT Colonography for Radiographers,
https://doi.org/10.1007/978-3-031-30866-6_19
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