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835
Copyright © 2015 The Korean Society of Radiology
Added Value of Using a CT Coronal Reformation to
Diagnose Adnexal Torsion
Sung Il Jung, MD1, Hee Sun Park, MD1, Younghee Yim, MD1, Hae Jeong Jeon, MD1, Mi Hye Yu, MD1,
Young Jun Kim, MD1, Kyungah Jeong, MD2
1Department of Radiology, Konkuk University School of Medicine, Research Institute of Medical Science, Seoul 143-729, Korea; 2Department of
Obstetrics and Gynecology, School of Medicine, Ewha Womans University, Seoul 158-710, Korea
Objective: To evaluate the increased value of using coronal reformation of a transverse computed tomography (CT) scan for
detecting adnexal torsion.
Materials and Methods: This study included 106 woman suspected of having adnexal torsion who underwent CT with
coronal reformations and subsequent surgical exploration. Two readers independently recorded the CT findings, such as the
thickening of a fallopian tube, twisting of the adnexal pedicle, eccentric smooth wall thickening of the torsed adnexal
mass, eccentric septal thickening of the torsed adnexal mass, eccentric poor enhancement of the torsed adnexal mass,
uterine deviation to the twisted side, ascites or infiltration of pelvic fat, and the overall impression of adnexal torsion with
a transverse scan alone or combined with coronal reformation and a transverse scan. The areas under the receiver operating
characteristic curves (AUCs), sensitivity, specificity, and positive predictive value were used to compare diagnostic
performance.
Results: Fifty-two patients were confirmed to have adnexal torsion. The addition of coronal reformations to the transverse
scan improved AUCs for readers 1 and 2 from 0.74 and 0.75 to 0.92 and 0.87, respectively, for detecting adnexal torsion (p
< 0.001 and p = 0.004, respectively). Sensitivity of CT for detecting twisting of the adnexal pedicle increased significantly
for readers 1 and 2 from 0.27 and 0.29 with a transverse scan alone to 0.79 and 0.77 with a combined coronal reformation
and a transverse scan, respectively (p < 0.001 and p < 0.001, respectively).
Conclusion: Use of a coronal reformation with transverse CT images improves detection of adnexal torsion.
Index terms: CT; Adnexa; Torsion
Korean J Radiol 2015;16(4):835-845
INTRODUCTION
Adnexal torsion is a gynecological emergency caused by
partial or complete twisting of the ovary, fallopian tube,
or both along the vascular pedicle. If the torsion is not
relieved, persistent vascular occlusion results in infarction
and necrosis of adnexal structures (1). Early recognition
is important to preserve the affected ovary and prevent
serious complications, such as peritonitis and infertility, but
the diagnosis of adnexal torsion poses a challenge because
there are no specific clinical signs, manifestations, or
biomarkers (2, 3). Although gray-scale ultrasonography (US)
http://dx.doi.org/10.3348/kjr.2015.16.4.835
pISSN 1229-6929 · eISSN 2005-8330
Original Article | Genitourinary Imaging
Received November 11, 2014; accepted after revision April 8,
2015.
This paper was supported by Konkuk University in 2015.
Corresponding author: Kyungah Jeong, MD, Department of
Obstetrics and Gynecology, School of Medicine, Ewha Womans
University, Mokdong Hospital, 1071 Anyangcheon-ro, Yangcheon-
gu, Seoul 158-710, Korea.
• Tel: (822) 2650-5274 • Fax: (822) 2647-9860
• E-mail: ogjeong@ewha.ac.kr
This is an Open Access article distributed under the terms of
the Creative Commons Attribution Non-Commercial License
(http://creativecommons.org/licenses/by-nc/3.0) which permits
unrestricted non-commercial use, distribution, and reproduction in
any medium, provided the original work is properly cited.
836
Jung et al.
Korean J Radiol 16(4), Jul/Aug 2015 kjronline.org
CT Imaging
CT scans were obtained on a MDCT (LightSpeed VCT XT;
GE Healthcare, Milwaukee, WI, USA; or LightSpeed Pro 16;
GE Healthcare). The scanners were set to the following
parameters: detector collimation, 64 x 0.625 mm and 16 x
1.25 mm; helical pitch, 0.984 and 0.938; section thickness/
interval, 3.75/3.75 mm and 3.75/3.75 mm; rotation time,
0.5 seconds; 120 kVp/300–500 mA and 120 Kvp/200–400
mA, respectively. Intravenous contrast (iopromide, Ultravist
370; Bayer Healthcare, Berlin, Germany) was injected at a
rate of 3 mL/sec in a total volume of 130 mL through the
antecubital vein using a mechanical injector. Bolus tracking
was not applied, and scanning started 90 seconds after
beginning the contrast injection. No oral contrast agent was
used. Scanning regularly covered the region from the dome
of the liver to the lower vagina. Coronal reformatted images
of 3.0 mm section thickness and 3.0 mm reconstruction
intervals were generated using the source CT data set and
commercially available console software (Volume Viewer;
GE Medical Systems, Waukesha, WI, USA). Radiation dose
to the patients was monitored for each examination using
the volume CT dose index (CTDIvol) and dose length product
(DLP), which were calculated by the CT scanner and were
automatically saved to a dose report. The mean CTDIvol value
was 10.7 ± 2.1 mGy, and the mean DLP value was 530.3 ±
109.1 mGy·cm.
Image Analysis
The CT images were reviewed retrospectively and
independently on a picture archiving and communication
system workstation (Centricity; GE Healthcare) by two
radiologists (with 7 and 5 years experience, respectively,
in genitourinary and abdominal imaging). The readers
were blinded to all surgical and pathological data. Both
readers independently reviewed 1) the transverse CT scan
alone and 2) the coronal reformation in combination
with the transverse CT scan. The two CT data sets for
each patient were randomly interpreted during different
sessions at 4-week intervals to minimize recall bias. The
CT images were specifically evaluated for the presence or
absence of findings related to adnexal torsion, including
thickening of a fallopian tube, twisting of the adnexal
pedicle, eccentric smooth wall thickening of the torsed
adnexal mass, eccentric septal thickening of the torsed
adnexal mass, eccentric poor enhancement of the torsed
adnexal mass, uterine deviation to the twisted side, ascites,
and infiltration of pelvic fat (2, 7, 15, 16). In addition,
and Doppler US are the initial imaging modalities of choice
when adnexal torsion is suspected (4-6), the US findings
of adnexal torsion are nonspecific and have not been fully
established in a large series (1, 7, 8).
Use of computed tomography (CT) for evaluating woman
presenting with acute pelvic pain in the emergency
department has increased to exclude bowel or urologic
diseases, such as appendicitis, diverticulitis, or ureter
stones. In addition, the innovation of multidetector row
CT (MDCT) has led to remarkable improvements in scanning
speed, scan volume, and spatial resolution along the z-axis
(9). Such technical changes have enabled acquisition of
isotropic CT data, and reformations in any desired planes are
similar in spatial resolution to those in the transverse plane
(10). Several studies have reported that adding a coronal
reformation is advantageous to evaluate acute appendicitis,
small bowel obstruction, and urinary tract disease (11-
14). Despite promising results obtained with coronal
reformations on MDCT in this clinical setting, it remains
uncertain whether adding a coronal reformation improves
the detection of adnexal torsion. Thus, the purpose of our
study was to evaluate the increased value of using a coronal
reformation with a transverse CT scan to detect adnexal
torsion.
MATERIALS AND METHODS
Study Population
This study was approved by the Institutional Review
Board of our medical center. A retrospective analysis of the
medical records of patients in our institution from January
1, 2008 to September 30, 2013 was conducted to identify
patients who were suspected of having adnexal torsion and
who underwent an abdomino-pelvic CT examination and
subsequent surgical exploration of the adnexa. Among 110
consecutive patients from our search, four were excluded
due to a lack of coronal reformation CT images. Ultimately,
106 patients (age range, 10–80 years; mean age, 34.1
± 12.3 years) were included in this study. All patients
presented with acute pelvic pain for up to 7 days and
underwent transabdominal or transvaginal US as first-line
imaging. The indications for CT imaging after US included
an undetermined ovarian mass, limited US study due to
poor sonic window, large ascites volume, or exclusion of
bowel disease.
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Coronal Reformatted CT of Adnexal Torsion
Korean J Radiol 16(4), Jul/Aug 2015
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each reader gave an overall impression of the likelihood
of adnexal torsion based on all of the CT findings, using
a rating scale of 1 to 5 (1, definitely absent; 2, probably
absent; 3, indeterminate; 4, probably present; and 5,
definitely present). In patients with bilateral adnexal
masses, only the side more likely to be torsed was evaluated
because synchronous bilateral adnexal torsion is very rare
(17).
Statistical Analysis
Clinical and demographic data are reported with
descriptive statistics. Mean, median, and standard deviation
are used to summarize continuous variables; frequencies
and percentages were used for categorical variables. The
Wilcoxon rank-sum test was used to assess the difference
between patients with and without adnexal torsion.
Receiver operating characteristic curves and the areas under
the receiver operating characteristic curves (AUCs) with
95% confidence intervals (CIs) were estimated for overall
diagnostic performance of each image set and each reader
using nonparametric methods for the 5-point ordinal score
assessments. The AUCs for the transverse CT scan alone
and the coronal reformation with the transverse CT scan
were compared using a nonparametric method (18, 19).
Sensitivity, specificity, and positive predictive value (PPV)
were estimated with an imaging score > 3 as positive for
adnexal torsion. Sensitivity and specificity comparisons for
the transverse CT scan alone vs. a coronal reformation and
the transverse CT scan were calculated using the McNemar
test. p-values ≤ 0.05 or less were considered significant.
Inter-reader agreement was assessed using the weighted
κ statistic with quadratic weights and was interpreted
using the following scale: slight agreement, ≤ 0.20; fair
agreement, 0.21–0.40; moderate agreement, 0.41–0.60;
substantial agreement, 0.61–0.80; and almost perfect
agreement, 0.81–1.0 (20, 21). The 95% CIs are reported for
the estimated κ statistics.
All statistical analyses were performed with the MedCalc
Software 14.10.2 software package (MedCalc, Mariakerke,
Belgium).
RESULTS
A total 111 adnexal masses in 106 patients were
demonstrated at surgery and during the pathological
examinations. An adnexal mass was detected in all patients,
and bilateral adnexal masses were demonstrated in five
(5/106, 4.7%). Of the five patients with bilateral adnexal
masses, three had bilateral endometrioma, one had bilateral
corpus luteal cysts, and one had a mucinous cystadenoma
and corpus luteal cyst in each adnexa. Of the 106 patients,
52 (52/106, 49.1%) were confirmed to have adnexal
torsion, and 54 (54/106, 51.9%) were confirmed not to
have adnexal torsion. Table 1 shows the characteristics of
Table 1. Charateristics of Patients with or without Adnexal Torsion
Patients with Adnexal Torsion
(n = 52)
Patients without Adnexal Torsion
(n = 54) P
Age (years) 31.0 (22.5–41.5)* 32.5 (27.0–42.0)* 0.301
The largest diameter of adnexal mass (cm) 8.6 (7.0–10.8)* 6.5 (5.6–8.5)* 0.002
Hemorrhagic infarction 20 (38.4) NA
Histopathologic diagnosis
Teratoma 22 (42.3) 10 (18.5)
Endometrioma 1 (1.9) 15 (27.8)
Corpus luteal cyst 5 (9.6) 12 (22.2)
Follicular cyst 10 (19.2) 7 (13.0)
Mucinous cystadenoma 3 (5.8) 4 (7.4)
Serous cystadenoma 6 (11.5) 0
Borderline tumor 2 (3.8) 2 (3.7)
Paratubal cyst 2 (3.8) 2 (3.7)
Hydrosalpinx 1 (1.9) 0
Tuboovarian abscess 01 (1.9)
Fibroma 01 (1.9)
Paraovarian cyst 01 (1.9)
Unless otherwise indicated, data are number of patients, with percentages in parentheses. *Data are medians, with ranges in parentheses.
NA = not applicable
838
Jung et al.
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the patients with or without adnexal torsion. All cases of
adnexal torsion were unilateral, with a slightly right-sided
predominance (28:24).
Adding the coronal reformation to the transverse CT scan
improved overall diagnostic performance for detecting
adnexal torsion (Table 2, Fig. 1). The AUC for reader 1
increased from 0.74 (95% CI, 0.64–0.82) with a transverse
CT scan alone to 0.92 (95% CI, 0.85–0.96) with a coronal
reformation and a transverse CT scan (p < 0.001). The AUC
for reader 2 increased from 0.75 (95% CI, 0.66–0.83) with a
transverse CT scan alone to 0.87 (95% CI, 0.79–0.92) with
a coronal reformation and a transverse CT scan (p = 0.004).
Interreader agreement for detecting adnexal torsion was
moderate (κ = 0.46 for a transverse CT scan alone and κ =
0.57 for a coronal reformation and a transverse CT scan).
Sensitivity, specificity, PPV, and accuracy values of each CT
finding for diagnosing adnexal torsion using a transverse CT
scan alone and a coronal reformation and a transverse CT
scan are presented for both readers in Tables 3 and 4 and
Figures 2-7. Sensitivity of reader 1 for the CT finding of a
twisted adnexal pedicle increased significantly from 0.27
(95% CI, 0.17–0.40) with a transverse CT scan alone to
0.79 (95% CI, 0.66–0.88) with a coronal reformation and a
transverse CT scan (p < 0.001), while sensitivity of reader 2
increased significantly from 0.29 (95% CI, 0.18–0.42) with
a transverse CT scan alone to 0.77 (95% CI, 0.64–0.86)
Fig. 1. Receiver operating characteristic curves for reader 1 (A) and reader 2 (B) for detecting adnexal torsion. AUC = areas under
receiver operating characteristic curve
1.00
0.75
0.50
0.25
0.00
1.00
0.75
0.50
0.25
0.00
0.00 0.000.25 0.250.50 0.50
False positive rate False positive rate
0.75 0.751.00 1.00
Transverse scan: AUC = 0.74
Coronal and transverse scan: AUC = 0.92
Transverse scan: AUC = 0.75
Coronal and transverse scan: AUC = 0.87
True positive rate
True positive rate
A B
Table 2. Diagnostic Parameters for Detecting Adnexal Torsion
Parameter
Reader 1 Reader 2
Transverse Scan Coronal and
Transverse Scans PTransverse Scan Coronal and
Transverse Scans P
AUC 0.74
(0.64–0.82)
0.92
(0.85–0.96) < 0.001 0.75
(0.66–0.83)
0.87
(0.79–0.92) 0.004
Sensitivity
0.35
(0.23–0.48)
[18/52]
0.87
(0.74–0.94)
[45/52]
< 0.001
0.42
(0.30–0.56)
[22/52]
0.87
(0.74–0.94)
[45/52]
< 0.001
Specificity
0.87
(0.75–0.94)
[47/54]
0.83
(0.71–0.91)
[45/54]
0.691
0.85
(0.73–0.93)
[46/54]
0.76
(0.63–0.85)
[41/54]
0.181
Positive predictive value
0.72
(0.52–0.86)
[18/25]
0.83
(0.71–0.91)
[45/54]
0.73
(0.55–0.86)
[22/30]
0.78
(0.65–0.87)
[45/58]
Accuracy
0.61
(0.52–0.70)
[65/106]
0.85
(0.77–0.91)
[90/106]
0.64
(0.55–0.73)
[68/106]
0.81
(0.73–0.88)
[86/106]
Data with 95% confidence intervals in parentheses and numerators and denominators in brackets. AUC = area under receiver operating
characteristic curve
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Coronal Reformatted CT of Adnexal Torsion
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Table 3. Diagnostic Performance of CT Findings for Detecting Adnexal Torsion by Reader 1
CT Finding
Sensitivity Specificity Positive Predictive Value Accuracy
Transverse
Scan
Coronal and
Transverse Scans PTransverse
Scan
Coronal and
Transverse Scans PTransverse
Scan
Coronal and
Transverse Scans
Transverse
Scan
Coronal and
Transverse Scans
Tubal thickening
0.73
(0.60–0.83)
[38/52]
0.63
(0.50–0.75)
[33/52]
0.326
0.67
(0.53–0.78)
[36/54]
0.81
(0.69–0.90)
[44/54]
0.021
0.68
(0.55–0.79)
[38/56]
0.77
(0.62–0.87)
[33/43]
0.70
(0.60–0.78)
[74/106]
0.73
(0.63–0.80)
[77/106]
Twisting of adnexal
pedicle
0.27
(0.17–0.40)
[14/52]
0.79
(0.66–0.88)
[41/52]
< 0.001
0.91
(0.80–0.96)
[49/54]
0.81
(0.69–0.90)
[44/54]
0.221
0.74
(0.50–0.89)
[14/19]
0.80
(0.67–0.89)
[41/51]
0.59
(0.50–0.68)
[63/106]
0.80
(0.72–0.87)
[85/106]
Eccentric smooth wall
thickening of
adnexal mass
0.52
(0.39–0.65)
[27/52]
0.58
(0.44–0.70)
[30/52]
0.452
0.52
(0.39–0.65)
[28/54]
0.50
(0.37–0.63)
[27/54]
1.000
0.51
(0.38–0.64)
[27/53]
0.53
(0.40–0.65)
[30/57]
0.52
(0.42–0.61)
[55/106]
0.54
(0.44–0.63)
[57/106]
Eccentric septal
thickening of
adnexal mass
0.15
(0.08–0.28)
[8/52]
0.15
(0.08–0.28)
[8/52]
NA
0.87
(0.75–0.94)
[47/54]
0.87
(0.75–0.94)
[47/54]
1.000
0.53
(0.30–0.75)
[8/15]
0.53
(0.30–0.75)
[8/15]
0.52
(0.42–0.61)
[55/106]
0.52
(0.42–0.61)
[55/106]
Eccentric poor
enhancement of
adnexal mass
0.12
(0.05–0.23)
[6/52]
0.12
(0.05–0.23)
[6/52]
1.000
0.94
(0.84–0.99)
[51/54]
0.94
(0.84–0.99)
[51/54]
NA
0.67
(0.35–0.88)
[6/9]
0.67
(0.35–0.88)
[6/9]
0.54
(0.44–0.63)
[57/106]
0.54
(0.44–0.63)
[57/106]
Uterine deviation to
side of involved
adnexa
0.08
(0.03–0.19)
[4/52]
0.12
(0.05–0.23)
[6/52]
0.634
0.87
(0.75–0.94)
[47/54]
0.89
(0.77–0.95)
[48/54]
1.000
0.36
(0.15–0.65)
[4/11]
0.50
(0.25–0.75)
[6/12]
0.48
(0.39–0.58)
[51/106]
0.51
(0.42–0.60)
[54/106]
Ascites
0.69
(0.57–0.80)
[36/52]
0.77
(0.64–0.86)
[40/52]
0.132
0.31
(0.21–0.45)
[17/54]
0.35
(0.24–0.49)
[19/54]
0.632
0.49
(0.38–0.61)
[36/73]
0.53
(0.42–0.64)
[40/75]
0.50
(0.41–0.59)
[53/106]
0.56
(0.46–0.65)
[59/106]
Infiltration of
periadnexal fat
0.29
(0.18–0.42)
[15/52]
0.37
(0.25–0.50)
[19/52]
0.133
0.52
(0.39–0.65)
[28/54]
0.56
(0.42–0.68)
[30/54]
0.501
0.37
(0.24–0.52)
[15/41]
0.44
(0.30–0.59)
[19/43]
0.41
(0.32–0.50)
[43/106]
0.46
(0.37–0.56)
[49/106]
Data with 95% confidence intervals in parentheses and numerators and denominators in brackets. NA = not applicable
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Table 4. Diagnostic Performance of CT Findings for Detecting Adnexal Torsion by Reader 2
CT Finding
Sensitivity Specificity Positive Predictive Value Accuracy
Transverse Scan Coronal and
Transverse Scans PTransverse Scan Coronal and
Transverse Scans PTransverse Scan Coronal and
Transverse Scans Transverse Scan Coronal and
Transverse Scans
Tubal thickening
0.92
(0.81–0.97)
[48/52]
0.96
(0.86–1.00)
[50/52]
0.502
0.48
(0.35–0.61)
[26/54]
0.37
(0.25–0.50)
[20/54]
0.072
0.63
(0.52–0.73)
[48/76]
0.60
(0.49–0.69)
[50/84]
0.70
(0.60–0.77)
[74/106]
0.66
(0.57–0.74)
[70/106]
Twisting of
adnexal pedicle
0.29
(0.18–0.42)
[15/52]
0.77
(0.64–0.86)
[40/52]
< 0.001
0.91
(0.80–0.96)
[49/54]
0.74
(0.61–0.84)
[40/54]
0.013
0.75
(0.53–0.89)
[15/20]
0.74
(0.61–0.84)
[40/54]
0.60
(0.51–0.69)
[64/106]
0.75
(0.67–0.83)
[80/106]
Eccentric wall
thickening of
adnexal mass
0.71
(0.58–0.82)
[37/52]
0.87
(0.74–0.94)
[45/52]
0.008
0.59
(0.46–0.71)
[32/54]
0.54
(0.41–0.66)
[29/54]
0.382
0.63
(0.50–0.74)
[37/59]
0.64
(0.53–0.75)
[45/70]
0.65
(0.56–0.74)
[69/106]
0.70
(0.60–0.78)
[74/106]
Eccentric septal
thickening of
adnexal mass
0.19
(0.11–0.32)
[10/52]
0.31
(0.20–0.44)
[16/52]
0.032
0.89
(0.77–0.95)
[48/54]
0.87
(0.75–0.94)
[47/54]
1.000
0.63
(0.39–0.82)
[10/16]
0.70
(0.49–0.85)
[16/23]
0.55
(0.45–0.64)
[58/106]
0.59
(0.50–0.68)
[63/106]
Eccentric poor
enhancement of
adnexal mass
0
(0–0.08)
[0/52]
0
(0–0.08)
[0/52]
NA
1.00
(0.92–1.00)
[54/54]
1.00
(0.92–1.00)
[54/54]
NA NA
[0/0]
NA
[0/0]
0.51
(0.42–0.60)
[54/106]
0.51
(0.42–0.60)
[54/106]
Uterine deviation to
side of involved
adnexa
0.60
(0.46–0.72)
[31/52]
0.71
(0.58–0.82)
[37/52]
0.032
0.67
(0.53–0.78)
[36/54]
0.65
(0.51–0.76)
[35/54]
1.000
0.63
(0.49–0.75)
[31/49]
0.66
(0.53–0.77)
[37/56]
0.63
(0.53–0.72)
[67/106]
0.68
(0.59–0.76)
[72/106]
Ascites
0.85
(0.72–0.92)
[44/52]
0.87
(0.74–0.94)
[45/52]
1.000
0.17
(0.09–0.29)
[9/54]
0.15
(0.07–0.27)
[8/54]
1.000
0.49
(0.39–0.60)
[44/89]
0.49
(0.39–0.60)
[45/91]
0.50
(0.41–0.59)
[53/106]
0.50
(0.41–0.59)
[53/106]
Infiltration of
periadnexal fat
0.79
(0.66–0.88)
[41/52]
0.87
(0.74–0.94)
[45/52]
0.214
0.61
(0.48–0.73)
[33/54]
0.43
(0.30–0.59)
[23/54]
0.002
0.66
(0.54–0.77)
[41/62]
0.59
(0.48–0.70)
[45/76]
0.70
(0.60–0.78)
[74/106]
0.64
(0.55–0.73)
[68/106]
Data with 95% confidence intervals in parentheses and numerators and denominators in brackets. NA = not applicable
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with a coronal reformation and a transverse CT scan (p <
0.001).
DISCUSSION
We demonstrated that a coronal reformation added value
to a transverse CT scan for detecting adnexal torsion. When
the coronal reformation was combined with a transverse CT
scan, accuracy for the overall detection of adnexal torsion
improved significantly for both readers. In particular,
the detection rate of a twisted adnexal pedicle increased
significantly for both readers.
The pathophysiological process of adnexal torsion is a
sequence of several events. A twisted ovarian pedicle and
fallopian tube initially compromise venous and lymphatic
outflow resulting in congestion and diffuse ovarian edema,
which are likely followed by arterial obstruction and
thrombosis. Continued vascular compromise can lead to
hemorrhagic infarction and necrosis of the affected ovary.
Ultrasonography is the primary imaging technique most
often used in woman with acute pelvic pain suspicious for
adnexal torsion. Typical US findings include cystic, solid, or
complex ovarian masses, free fluid collection, thickening of
the wall, cystic hemorrhage, or follicles at the periphery of
an enlarged ovary (3, 6, 8, 22, 23). However, low detection
rates of 46–74% make distinguishing those from other
Fig. 3. Contrast-enhanced computed tomography (CT) scan of 53-year-old woman with torsion of follicular cyst in left ovary.
Transverse CT scan (A) and coronal reformation (B) show heterogeneous cystic mass (*) with swirling soft tissue lesion representing twisting of
adnexal pedicle (arrows).
A B
Fig. 2. Contrast-enhanced computed tomography (CT) scan of 66-year-old woman with torsion of follicular cyst in right ovary.
Transverse CT scan (A) and coronal reformation (B) show multilocular cystic mass with homogeneously elongated soft tissue lesion representing
tubal thickening (arrows).
A B
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diseases, such as hemorrhagic cysts, endometriosis, ovarian
tumors, or pelvic inflammatory disease, difficult (15).
Moreover, given the large variability in Doppler US findings
and characteristic dual vascular supply to the ovary, the
value of Doppler US is limited for detecting adnexal torsion
(8, 24, 25).
The widespread use of CT for assessing gynecological
diseases has led to the view that CT may be useful if the
adnexal torsion is equivocal on US or if the lesion is not
well depicted sonographically (2, 7, 15, 26). Rha et al. (7)
reported that common CT findings of adnexal torsion include
tubal thickening, smooth wall thickening of a twisted
ovarian cystic mass, ascites, and uterine deviation to the
twisted side. A study by Hiller et al. (2) demonstrated
that a well-defined adnexal mass with a smooth border or
infiltration of periadnexal fat is an important CT sign of
adnexal torsion. Chiou et al. (1) also demonstrated that
minimal or absent enhancement of a torsed ovary on CT
indicates the evolution of ovarian torsion from ischemia to
infarction. In the first study that evaluated the diagnostic
performance of CT findings for identifying adnexal torsion,
Lee et al. (16) found that the accuracy of intra-adnexal
or extra-adnexal CT findings, including tubal thickening,
eccentric wall or septal thickening of the adnexal mass,
eccentric poor enhancement of the adnexal mass, uterine
deviation to the side of the involved adnexa, ascites, or
Fig. 5. Contrast-enhanced computed tomography (CT) scan of 52-year-old woman with torsion of follicular cyst in right ovary.
Transverse CT scan (A) and coronal reformation (B) show eccentric septal thickening (arrow) of cystic mass.
A B
Fig. 4. Contrast-enhanced computed tomography (CT) scan of 41-year-old woman with torsion of follicular cyst in right ovary.
Transverse CT scan (A) and coronal reformation (B) show unilocular cystic mass with eccentric smooth wall thickening (arrows).
A B
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infiltration of periadnexal fat ranged from 0.85 to 0.97.
However, their data may have been somewhat overestimated
because their study population was enrolled regardless
of the status or duration of pelvic pain (16). Of note, the
aforementioned CT findings may be secondary changes of a
torsed ovary and the adjacent genital tract, which reflect
edema, congestion, infarction, or necrosis, and are not clear
obvious proof of torsion per se (26).
A feature that directly indicates adnexal torsion
is twisting of the adnexal pedicle, which shows a
characteristic swirling target appearance of the adnexa,
and can be a most definitive and pathognomic sign of
adnexal torsion (15, 25). A twisted pedicle corresponds to
the broad ligament, fallopian tube, and ovarian branches of
the uterine artery and vein (24). Detecting of this finding
varies between 13 and 88% of patients with adnexal torsion
on US and in less than one-third of patients with adnexal
torsion on CT or magnetic resonance imaging (2, 4, 24,
25). Our results for detecting a twisted adnexal pedicle on
a transverse CT scan alone were similar to those of previous
Fig. 6. Contrast-enhanced computed tomography (CT) scan of 49-year-old woman with complaint of acute pelvic pain as false-
negative case.
Transverse CT scan (A) and coronal reformation (B) show well-defined cystic mass (*) in pelvic cavity. Both readers provided scores of 2 as level
of suspicion for adnexal torsion using 5-point scale. Adnexal mass was serous cystadenoma with torsion in right ovary.
A B
Fig. 7. Contrast-enhanced computed tomography (CT) scan in 38-year-old woman with complaint of acute pelvic pain as false-
positive case.
Transverse CT scan (A) and coronal reformation (B) show well-defined cystic mass (*) with eccentric soft tissue lesion (arrows). Both readers
provided score of 4 as level of suspicion for adnexal torsion using 5-point scale. Adnexal mass was paratubal cyst without torsion in right ovary.
A B
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studies (2, 27). Interestingly, adding a coronal reformation
to a transverse CT scan significantly improved the detection
rate of this finding from 27–29% to 77–79% and twisting
of the adnexal pedicle had the highest accuracy (75–80%)
among all CT findings. Similarly, the adding a coronal
reformation significantly increased overall accuracy (87–
92%) and sensitivity (87%) for detecting adnexal torsion.
We suggest that these observations are a clue to validate
our hypothesis that additional coronal reformations provide
a more intuitive anatomic perspective and help to evaluate
an unpredictable tortuous structure, such as an adnexal
pedicle, as in previous studies on acute appendicitis (14,
28).
We acknowledge the following limitations. First, our study
was retrospective. Verification or selection bias may have
distorted the true diagnostic performance and limit the
applicability of results because we only included patients
who underwent preoperative CT and surgery. Second, the
relatively high proportion of patients with adnexal torsion
in our sample may have affected pretest probability.
Third, the readers were instructed to search specifically for
adnexal torsion on CT, which may have improved accuracy.
Fourth, our results were based on findings obtained from
nonuniform CT scanners; however, this reflects actual
clinical practice.
In conclusion, adding a coronal reformation to a
transverse CT scan improved overall accuracy for diagnosing
adnexal torsion and was valuable for detecting a twisted
adnexal pedicle.
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