1  Answers:

Patient 1: C. Suture needle

Patient 2: E. Hernia repair mesh

Patient 3: D. Brachytherapy radiation seed

Patient 4: B. Laparotomy pad

Patient 5: A. Vascular embolization microcoil

This series of patients demonstrates expected and unexpected radiopaque foreign bodies that can be seen in the abdomen and pelvis. Patients 1 and 4 have unexpected retained foreign bodies (arrows on the following images) after surgery. Patient 1 has a retained suture needle, and patient 4 has a retained surgical laparotomy pad. These items were identified by x-ray and retrieved before the patients left the operating room.

The following image shows the radiographic appearance of radiopaque surgical items, such as surgical sponges and laparotomy pads, which have thin metallic strips that allow them to be identified radiographically. Complications including infection, granulomatous reaction, bowel obstruction, or fistulae may develop immediately or years after surgery. The term “gossypiboma” is reserved for a retained mass of cotton or woven fabric. Gossypibomas classically have a spongiform appearance on CT with foci of gas and wavy layers of fabric internally. An associated radiopaque marker strip may be identified, and chronic gossypibomas may be surrounded by an enhancing fibrous capsule mimicking abscess or neoplasm.

Patient 2 has an abdominal wall hernia repair with mesh. This type of mesh has small round titanium anchors that are visible on radiographs or CT, but other types may not have visible anchors. The anchors are typically arranged in an ovoid configuration (short arrows on the following coronal image) at the margins of the mesh. Among the anchors, a layer representing the mesh (long arrows on the following sagittal image) is visible.

Patient 3 has undergone brachytherapy with multiple radiation seed sources implanted in the prostate gland. These are seen as group of short linear metallic foci near the symphysis pubis.

Patient 5 has two vascular embolization microcoils in the left upper quadrant (arrows on the following images). These are initially seen as metallic wavy lines and later appear to be coiled more tightly. The patient had selective embolization of two branches of the superior mesenteric artery to treat postoperative GI bleeding. A few surgical clips are seen above the coils, and on the first image, a surgical drain is also visible.

References: Hunter TB, Taljanovic MS. Medical devices of the abdomen and pelvis. Radiographics 2005;25(2):503–523.

Manzella A, Filho PB, Albuquerque E, et al. Imaging of gossypibomas: pictorial review. AJR Am J Roentgenol 2009;193(6 Suppl):S94–S101.

Taljanovic MS, Hunter TB, O’Brien MJ, et al. Gallery of medical devices: part 2: devices of the head, neck, spine, chest, and abdomen. Radiographics 2005;25(4):1119–1132.

2  Answer A.Axial and coronal CT images show discontinuity (arrows) of the left hemidiaphragm consistent with diaphragmatic rupture, complicated by herniation of the stomach, transverse colon, spleen, and a small portion of the left hepatic lobe into the left thorax. The left lung is compressed by the herniation and is opacified due to contusion and hemorrhage. The mediastinum is slightly shifted to the right, and no pneumothorax is identified.

Diaphragmatic injuries are almost always associated with other injuries. The left diaphragm is ruptured more often than the right. Evaluation of the integrity of the diaphragm may be challenging, and correlation of the axial images with CT multiplanar reconstructions in the coronal and sagittal planes may be helpful. A number of direct and indirect signs of diaphragmatic rupture have variable sensitivity but excellent specificity > 90%. A few of these signs are listed in the table below. Complications of diaphragmatic rupture include bowel incarceration, obstruction, and strangulation, respiratory insufficiency, pneumonia, pleural effusion/empyema, and tension physiology from mediastinal shift. Diaphragmatic rupture requires surgical repair.

References: Desir A, Ghaye B. CT of blunt diaphragmatic rupture. Radiographics 2012;32(2):477–498.

Iochum S, Ludig T, Walter F, et al. Imaging of diaphragmatic injury: a diagnostic challenge? Radiographics 2002;22(Spec No):S103–S116; discussion S116–S108.

3a  Answer D.

3b  Answer C.This patient has disseminated echinococcal infection. There are multiple complex cystic masses with appearance pathognomonic for echinococcal (hydatid) cysts. The dominant mass replacing the spleen represents an encapsulated “mother cyst” with multiple peripheral “daughter cysts” (short white arrows) arranged in a spoke wheel, or rosette, pattern. The daughter cysts typically demonstrate lower density on CT than the mother cyst. Other similar complex cysts are seen scattered in the liver and peritoneal cavity (long white arrows).

Echinococcal cysts have variable appearance, ranging from simple cysts to complex solid and cystic masses. Lesions may show calcification, and those with extensive calcification such as the one in the right lobe of the liver (short black arrow) are more likely to represent involuted inactive cysts. The “water lily sign” is also highly specific for echinococcal cysts, referring to sloughing and collapse of the internal membrane within a cyst. “Hydatid sand” represents mobile debris that can be seen in the cysts on ultrasound. When imaging features are less specific, the differential diagnosis may include cystic lesions such abscess or biliary cystadenoma/cystadenocarcinoma. Cystic or necrotic metastases may be considered if there are enhancing soft tissue components. Amebic abscesses are usually unilocular and thick walled, with appearance similar to pyogenic (bacterial) abscesses.

Hydatid disease is a parasitic infection caused by tapeworms endemic in underdeveloped parts of the world, particularly where sheep are raised. Humans are infected by ingesting water contaminated with dog feces harboring Echinococcus granulosus (more common) or Echinococcus multilocularis eggs. The liver is the most common site of involvement, seen in 75% to 80% of cases, followed by the lung. Echinococcal cysts may be complicated by peritoneal rupture, portal obstruction, biliary obstruction, and superinfection. Treatment options include surgery, percutaneous aspiration, and antiparasitic agents such as albendazole. The antiparasitic agents also prevent anaphylaxis during the procedure.

The “central dot” sign is unrelated to echinococcal cysts and is an enhancing focus associated with the cystic lesions of Caroli disease.

References: Marrone G, Crino’ F, Caruso S, et al. Multidisciplinary imaging of liver hydatidosis. World J Gastroenterol 2012;18(13):1438–1447.

Nunnari G, Pinzone MR, Gruttadauria S, et al. Hepatic echinococcosis: clinical and therapeutic aspects. World J Gastroenterol 2012;18(13):1448–1458.