CT findings of sigmoid volvulus.
OBJECTIVE
The purpose of this study was to evaluate the features of sigmoid volvulus on CT scanograms and cross-sectional images.


METHODS
We retrospectively reviewed 21 cases of sigmoid volvulus in 15 men and six women. Three radiologists evaluated scanograms and cross-sectional images for several classic and two novel imaging signs of volvulus: crossing sigmoid transitions (called the X-marks-the-spot sign) and folding of the sigmoid wall by partial twisting (called the split-wall sign). A general impression was assigned to scanograms and cross-sectional images. CT findings suggesting bowel compromise were compared with pathologic and endoscopic findings.


RESULTS
The most sensitive scanogram findings were absence of rectal gas (19 of 21 cases, 90%) and an inverted-U-shaped distended sigmoid (18 of 21 cases, 86%) followed by the coffee bean sign and disproportionate sigmoid enlargement (both 16 of 21 cases, 76%). The most sensitive cross-sectional findings were one sigmoid colon transition point (20 of 21 cases, 95%) and disproportionate enlargement of the sigmoid (18 of 21 cases, 86%). The X-marks-the-spot and split-wall signs were present in nine of 21 (43%) and 11 of 21 (52%) patients, but one of the two signs was present in 18 of 21 patients (86%). Classic radiographic and definitive cross-sectional findings were seen in 11 of 21 (52%) and 16 of 21 (76%) patients. CT findings were definitive in five of seven patients (71%) with indeterminate scanogram findings. Imaging signs suggesting bowel compromise correlated poorly with clinical ischemia, but CT features were present in all three patients with frank necrosis.


CONCLUSIONS
Sigmoid volvulus has a spectrum of imaging findings. A classic appearance is absent on approximately one half of scanograms and one fourth of CT scans. Use of new signs that model the pathophysiologic characteristics of volvulus (X-marks-the-spot sign for more complete twisting and split-wall sign for less severe twisting) may improve diagnostic confidence.
Levsky
Jeffrey M
JM
Department of Radiology, Montefiore Medical Center, Albert Einstein College of Medicine, 111 E 210th St., Bronx, NY 10467-2490, USA. jlevsky@montefiore.org
Den
Elana I
EI
DuBrow
Ronelle A
RA
Wolf
Ellen L
EL
Rozenblit
Alla M
AM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003974:Diatrizoate Meglumine; D005260:Female; D006801:Humans; D045822:Intestinal Volvulus / Q000000981:diagnostic imaging*; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012810:Sigmoid Diseases / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids
D003287:Contrast Media; D014283:Triiodobenzoic Acids; D003974:Diatrizoate Meglumine; D007472:Iohexol; C038192:iopromide; C044834:iodixanol