Bowel opacification

Two other cases of neonatal bowel opacification secondary to oral and rectal sodium polystyrene sulfonate have been reported (29). Abdominal radiography showed a faint homogeneous increase in density within the bowel lumen. 

Sherman S, Friedman AP, Berdon WE, Haller JO. Kayexalate a new cause of neonatal bowel opacification. Radiology 1981 138(1) 63. ... 

Fig. 8.8. Postmenopausal ovaries on CT. The ovaries (arrows) appear as bandlike soft tissue structures and are located between the iliac vessels and bowel loops. Without bowel opacification identification of normal postmenopausal ovaries is usually not possible. Uterus (U) with a calcified fibroid of the fundus...

T2WI varies in accordance with the contents, which ranges from water-like fluid to proteinaceous or hemorrhagic components. Multiplanar imaging and bowel opacification facilitates depiction of the tubal origin and differentiation from dilated bowel loops. 

Planning CT adequate bowel opacification necessary for clear differentiation of enteric abscesses and bowel loops... 

The use of pure tap water without the addition of radiopaque substances is a fundamentally different approach to oral and rectal opacification. It is almost impossible to achieve complete filling of the small intestine and certainly not of the large intestine with water,since normal enteral absorption prevents retention of water in the bowel lumen. Water absorption is effectively inhibited by the addition of mannitol. The best effect is achieved with 250 ml mannitol (5%) in 750 ml of water or juice. Administration of negative oral and rectal contrast medium is required only for differentiation of the mucosa and intestinal lumen if adequate intravenous contrast enhancement can be achieved. 

Despite the short examination and the absence of artifacts caused by bowel motion, CT has little use in differentiating posttherapeutic changes and recurrent tumor in the true pelvis. However, CT of the chest, abdomen, and pelvis after oral opacification and IV contrast medium administration can be used in the follow-up of cervical cancer to exclude distant metastases and nodal involvement. The benefit of whole body FDG PET in detecting recurrent cervical cancer and distant metastasis is currently being investigated [ 113,114]. As with MRI, at least 6 months should elapse after primary therapy to correctly interpret increased focal accumulation. 

Ovaries can be identified on CT and MRI due to their location and soft tissue characteristics. The landmark of the ovaries are follicular structures which can be best identified on T2-weighted MRI [8]. On CT, normal ovaries can be best identified after bowel contrast opacification. They are ovoid soft tissue structures with low attenuation areas which represent normal follicles (Fig. 8.2). Presence of a dominant folhde ranging more than 1 cm in size assists in ovarian identification. Hemorrhagic corpus luteum cysts may he identified by high attenuation values or a fluid-fluid level [9]. 

In women of childbearing age, ovaries in atypical positions can be identified on CT and MRI in the majority of patients due to the typical morphology of follicles. MRI is superior to CT for diagnosing mal-descended or ectopic ovaries due to their excellent visualization on T2-weighted images. Bowel contrast opacification will facilitate identification of ovaries in atypical positions. An ovary not visualized in the ovarian fossa should be sought in other locations in proximity to the uterus and above the pelvic brim, rarely may it be located near the inguinal canal. 

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