Fl'711'I. Type IIICholedochocysts: choledochocele. A,.ERCP shows saccular dilatation <strong>of</strong> the dist<strong>al</strong> common bile duct (C) <strong>and</strong> choledocholiathias 'II I II. I "ron<strong>al</strong> MRCP image demonstrates bulbous dilatation <strong>of</strong> the intramur<strong>al</strong> segment <strong>of</strong> the dist<strong>al</strong> common bile duct (arrows), which protrudes II) III
tumors.73 Occasion<strong>al</strong>ly, endom<strong>et</strong>riomas can occur in the anterior abdomin<strong>al</strong> w<strong>al</strong>l, incorporated in a surgic<strong>al</strong> scar, typic<strong>al</strong>ly in the s<strong>et</strong>ting <strong>of</strong> prior cesarean section. These hormon<strong>al</strong>ly responsive lesions can be painful at the time <strong>of</strong> menses <strong>and</strong> can be easily missed with pelvic ultrasound if the near field is not carefully examined. 113 Miscellaneous Conditions Vascular Lesions Sm<strong>al</strong>l, subcutaneous blood vessels are frequently evident on abdomin<strong>al</strong> CT scans; however, an increase in the size or number <strong>of</strong> these vessels (usu<strong>al</strong>ly veins) should raise suspicion <strong>of</strong> an intra-abdomin<strong>al</strong> venous abnorm<strong>al</strong>ity. Veins are recognized by their intense enhancement <strong>and</strong> tubular or serpiginous configuration on multiple, contiguous images. Abdomin<strong>al</strong> w<strong>al</strong>l venous collater<strong>al</strong> vessels may occur in the s<strong>et</strong>ting <strong>of</strong> systemic venous occlusion or port<strong>al</strong> hypertension, <strong>and</strong> the appearance <strong>of</strong> the collater<strong>al</strong> vessels <strong>al</strong>one <strong>of</strong>ten does not lead to a definitive diagnosis. Patients with port<strong>al</strong> hypertension usu<strong>al</strong>ly have a large number <strong>of</strong> associated findings that lead to the correct diagnosis, including r<strong>et</strong>roperitone<strong>al</strong>, mesenteric, perisplenic, or paraesophage<strong>al</strong> varices, <strong>and</strong> cirrhotic hepatic changes.113'llS One specific collater<strong>al</strong> vessel, the recan<strong>al</strong>ized umbilic<strong>al</strong> or paraumbilic<strong>al</strong> vein, is highly specific for port<strong>al</strong> hypertension.113-115 This vessel drains the port<strong>al</strong> venous system from the left port<strong>al</strong> vein <strong>al</strong>ong the f<strong>al</strong>ciform ligament into the anterior abdomin<strong>al</strong> w<strong>al</strong>l, terminating in many paraumbilic<strong>al</strong> systemic veins, causing caput medusae. Vascular Grafts Surgic<strong>al</strong>ly placed arteri<strong>al</strong> grafts are easily identified in the subcutaneous tissues by CT, ultrasound, or MRU3 Axillaryfemor<strong>al</strong> bypass grafts are oriented par<strong>al</strong>lel to the long axis <strong>of</strong> the body <strong>al</strong>ong the later<strong>al</strong> abdomin<strong>al</strong> w<strong>al</strong>l, whereas femor<strong>al</strong>femor<strong>al</strong> grafts cross the lower abdomen just above the symphysis pubis. Patency <strong>of</strong> these grafts is usu<strong>al</strong>ly apparent by p<strong>al</strong>pation but can be confirmed by Doppler ultrasound.73 Figure 114-29. CSFoma: CT features. There is a fluid coli," in the subcutaneous fat <strong>of</strong> the anterior pelvic w<strong>al</strong>l due to "' ventriculoperitone<strong>al</strong> shunt tube. Other Implanted Devices Chronic ambulatory peritone<strong>al</strong> di<strong>al</strong>ysis is pcrl", IIII'd patients. in ren<strong>al</strong> ~ailure by sequ~nti~lly infusing IIII 1.1 litu: the pentone<strong>al</strong> cavity <strong>and</strong> removmg It to <strong>al</strong>low 11"11r " "" toxins <strong>and</strong> regulation <strong>of</strong> electrolytes. This techniqll' 1"'lliltit" the placement <strong>of</strong> a cath<strong>et</strong>er that crosses the anteri." ,iI'.\11111.1< n<strong>al</strong> w<strong>al</strong>l. Leaks, hernias, or fluid collections at tl" 'oIliI\1ttt': entry site are optim<strong>al</strong>ly demonstrated by CT (Fig. II I ",). IItl: benefici<strong>al</strong> to infuse di<strong>al</strong>ysate mixed with iodin<strong>al</strong>l'd ,tllIll'dJ-r to enhance visu<strong>al</strong>ization <strong>of</strong> the configuration <strong>of</strong> thl' I" Iltlll\~1 lining at the cath<strong>et</strong>er site.ll5 Other devices, such .1'. ,"lu_llfiL ports, chemotherapy reservoirs, <strong>and</strong> cardiac pacl'lIl.d"'I~, IIr.!' commonly s,een with cross-section<strong>al</strong> imaging. Unb, II II" I"vll'¥ was placed recently, the presence <strong>of</strong> gas or fluid ;1I'IIIIHltlrf implant should raise suspicion <strong>of</strong> infection. ' Figure 114-30. Trocar deformity. A. Acute changes at the post-trocar insertion site (arrows) are present in the anterior abdomin<strong>al</strong> w<strong>al</strong>l. 8. II" "," 1'"1\ sites may serve as a chronic source <strong>of</strong> ventr<strong>al</strong> herniation (arrows). 1 "'
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