MDCT enteroclysis with split bolus technique provides additional information on the urinary tract in patients with suspected bowel endometriosis

Introduction: Multidetector computerized tomography enteroclysis (MDCTe) has been demonstrated to be accurate in the diagnosis of bowel endometriosis. In this study we present a modified protocol of MDCTe which allows to study the urinary tract without increasing the radiation dose imparted to the patients. Materials and methods: This prospective study included 103 women who underwent laparoscopy because of pain and gastrointestinal symptomssuggestive of pelvic and colorectal endometriosis. Women with a previous diagnosis of urolithiasis were excluded from the study. Colonic distension was achieved by introducing 2000–2300ml of water (378C). The same iodine load per patient body weight (7.4 mg/kg) was administered. The intra- venous contrast material (c.m.) was administered by using a split bolus technique. 20% of the c.m. was administered at a rate of 1 ml/s during colon distension (8 minutes before starting the volumetric acquisition). After injec- tion of the remaining quantity of the c.m, the volumetric acquisition was per- formed during the portal phase of the c.m. (40 s after the arterial peak). One volumetric acquisition was performed from the dome of the diaphragm to the pubic symphysis. Examinations were performed on a 16-row MDCT scanner (LightSpeed, GE Medical Systems, Waukesha, Wisconsin, USA). In addition to axial images, coronally and sagittally reformatted multiplanar reconstructions, maximum-intensity- projections, average-intensity-projections images were generated on an Advantage workstation (AW 4.2, GE Healthcare). Images were evaluated on a PACS workstation (Centricity, GE Healthcare) by two radiologists. The presence of bowel endometriotic nodules and the depth of infiltration of the nodules in the bowel wall were determined. The radiologists classified ureteral opacification as poor, sufficient, and good. When the ureter was opa- cified between the crossing of the iliac vessels and the bladder, the radiol- ogists determined whether ureteral compression was present. Radiological findings were compared with surgical and histological results. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, positive likelihood ratio (LRþ), and negative likelihood ratio (LR2) were calculated by using the CATmaker software (CEBM, Oxford, UK). Results: Surgery revealed that 67 women (65.0%) had bowel endometriotic nodules. The sensitivity of MDCTe in identifying bowel nodules was 95.5%, the specificity 97.2%, the PPV 98.5%, the NPV 92.1%, the accuracy 96.1%, the LRþ 34.39, and the LR- 0.05. Three bowel nodules were not detected by MDCTe; they were all located on the rectum. The effectiveness of MDCTe was also determined for the diagnosis of bowel nodules infiltrating at least the muscular layer. In this analysis the sensibility of MDCTe was 93.3%, the specificity 96.6%, the PPV 95.5%, the NPV 94.9%, the accuracy 95.1%, the LRþ 27.07, and the LR- 0.07. One patient had a double ureter. Ureteral opacification was judged to be poor in 17 cases (8.2%), suf- ficient in 36 cases (17.4%), and good in 154 cases (74.4%). The renal cav- ities were well detected in all cases; no hydronephrosis was observed. Compression of the distal ureter was observed at MDCTe in 36 cases (17.4%); surgery confirmed the presence of ureteral compression in 34 cases (16.4%); therefore, there were two false positive at MDCTe. In 137 cases laparoscopic examination of the ureters revealed the presence of super- ficial endometriotic lesions involving the peritoneum overlying the ureters; however, no ureteral compression was observed. The sensitivity of MDCTe in identifying ureteral compression was 97.1%, the specificity 98.8%, the PPV 94.4%, the NPV 99.4%, the accuracy 99.0%, the LRþ 83.54, and the LR20.03. Conclusions: Applying the split bolus technique to MDCTe allows diagnosing ureteral endometriosis and does not compromise the accuracy in the detection of bowel endometriosis.