European Journal of Radiology 81 (2012) 1479–1482
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European Journal of Radiology
jo ur n al hom epage: www.elsevier.com/locate/ejrad
Shape and volume of internal anal sphincter showed by three-dimensional
anorectal ultrasonography
A. Sboarina
a,∗
, A. Minicozzi
a,1
, C. Segattini
a,2
, F. Leopardi
a,2
, F. Lombardo
b,2
, V. Passeri
a,2
,
G. Scudo
a,2
, M. Bencivenga
a,2
, A. Fenzi
a,3
, C. Cordiano
a,4
a
Department of Surgery University Hospital of Verona, Italy
b
Department of Surgery University Hospital of Verona, Endoscopic surgery Unit, 1st General Surgery, Italy
a r t i c l e i n f o
Article history:
Received 21 February 2011
Accepted 6 April 2011
Keywords:
Three-dimensional anorectal
ultrasonography
Internal anal sphincter
Morphology
a b s t r a c t
Purpose: The aim of this work is to characterize the shape and the volume of the internal anal sphincter
(IAS) in normal subjects by three-dimensional anorectal ultrasonography.
Methods: Thirty-nine normal volunteer males (mean age 58.5 ± 18.7) and 25 females (mean age
59.4 ± 14.1) were submitted to anorectal ultrasonography.
The tissue is defined by a semiautomatic procedure. Measurements of thickness, length and volume
were assessed automatically.
The software provides an average number of 57,600 thickness measurements, 360 length measure-
ments for each zone (90 for each quadrant) and seven volume measurements (one for each anatomical
area).The mean values of magnitudes were calculated for the entire volume in each quadrant and zone.
Age and gender-related variations were analyzed.
Results: In assessments of the whole tissue, only thickness was gender-related, with greater thickness
for females (male thickness: 1.81 ± 0.47 mm, female thickness 2.16 ± 0.57 mm, P-value < 0.01).In the dis-
tal zone: thickness, length and volume were all larger in females (for male and female respectively:
1.83 ± 0.49 mm vs 2.34 ± 0.58 mm, P-value < 0.01, for the thickness; 10.87 ± 2.10 mm vs 12.18 ± 2.21 mm,
P-value < 0.02 for the length and 1501 ± 605 mm
3
vs 2169 ± 871 mm
3
, P-value < 0.01 for the volume).
In the medial zone, only thickness was gender-related, with greater thickness in females (male thick-
ness: 2.04 ± 0.60 mm, female thickness:2.44 ± 0.74 mm, P-value < 0.02).The only variation observed in
the proximal zone concerned length, larger in males (respectively: 11.27 ± 2.84 mm vs 9.55 ± 2.43 mm,
P-value < 0.02).
The male population was significantly positively correlated with ageing for volume in the whole tissue
( = 0.32, P-value < 0.05), and for both thickness and volume in the medial zone ( = 0.33, P-value < 0.05
for thickness; = 0.39, P-value < 0.02 for the volume).
Conclusion: This new method is useful to understand both functional anal disorders and local damage
which may affect only part of the muscle tissue.
© 2011 Elsevier Ireland Ltd. All rights reserved.
∗
Corresponding author at: Via Lucania 8, 37138 Verona Italy. Tel.: +39 3331387964; fax: +39 0458027639.
E-mail addresses: andrea.sboarina@univr.it (A. Sboarina), annaminicozzi@hotmail.com (A. Minicozzi), chris 74@alice.it (C. Segattini),
fulvioleopardi@ospedaleuniverona.it (F. Leopardi), fralom@hotmail.it (F. Lombardo), valentinapasseri83@gmail.com (V. Passeri), giovanniscudo@hotmail.com (G. Scudo),
mariabenci@hotmail.it (M. Bencivenga), albertofenzi@univr.it (A. Fenzi), chirurgiaurgenza@univr.it (C. Cordiano).
1
Address: Via Cesiolo 8, 37126 Verona, Italy. Tel.: +39 0458123789; fax: +39 0458122484.
2
Address: Piazzale Stefani 1, 37131 Verona, Italy. Tel.: +39 0458123789; fax: +39 0458122484.
3
Address: Servizio di Fisica Medica, Strada Le Grazie 8, 37134 Verona, Italy. Tel.: +39 0458027137; fax: +39 0458027639.
4
Address: Piazzale Stefani 1, 37131 Verona, Italy. Tel.: +39 0458004981; fax: +39 0458122484.
0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.ejrad.2011.04.024