Pitfalls in the CT diagnosis of appendicitis.

CT evaluation of appendicitis represents an increasingly common emergency room request. While the overall accuracy of CT is high, numerous pitfalls exist which may deceive radiologists, resulting in a missed diagnosis of appendicitis. The inflamed appendix may be unusual in its location, or may appear normal if only a small portion of the distal appendix is involved (tip appendicitis). In a patient with a history of appendectomy, inflammation of the appendiceal stump may be easily missed. Appendicitis may closely mimic small bowel obstruction, or gynaecological disease, especially after perforation has occurred. Even a misleading clinical history may lead the radiologist's eye astray. This pictorial review demonstrates these and other potential radiological pitfalls, and includes important points for the accurate diagnosis of appendicitis.

Toxic megacolon: diagnosis and treatment challenges.

In adults, toxic megacolon is a relatively uncommon but potentially lethal complication of inflammatory bowel disease (IBD), infectious colitis, or ischemic colitis caused by cancer chemotherapeutic agents. Patients have distension of the colon and signs of toxicity such as elevated temperature, hypotension, decreased level of consciousness and electrolyte imbalances. Factors thought to increase the risk include premature discontinuation of IBD medications; procedures that increase colon trauma, such as barium enema and colonoscopy; medications that decrease gastrointestinal motility; and electrolyte imbalances, especially hypokalemia. Differential diagnosis is made based on the patient's history and results of stool cultures and assay for Clostridium difficile toxin. Medical management in the intensive care unit includes careful monitoring, fluid volume and electrolyte replacement, bowel rest and decompression, antibiotic therapy, and cessation of medications that slow gastric motility. Surgical management may be necessary if there are signs of deterioration, perforation, hemorrhage, or sepsis.

Echogenic peritoneal fluid as an isolated sonographic finding: significance in patients at risk of ectopic pregnancy.

Echogenic intraperitoneal fluid in any quantity noted on sonography is thought to indicate a very high likelihood of ectopic pregnancy (EP) in patients at risk. We retrospectively reviewed 12 consecutive symptomatic patients with a positive pregnancy test in whom sonography revealed echogenic fluid as an isolated finding without evidence of intrauterine pregnancy and in whom follow-up was available. Final diagnoses were EP in seven patients (58%) and spontaneous abortion in five (42%). EP was diagnosed in all four patients with a large amount of echogenic fluid, but in only three (38%) of eight patients with a small-to-moderate amount of echogenic fluid. We conclude that a small-to-moderate amount of echogenic fluid noted as an isolated finding may not be highly predictive of EP.

Narrowing of the upper abdominal inferior vena cava in patients with elevated intraabdominal pressure.

BACKGROUND: Previous investigators have suggested that narrowing of the suprahepatic inferior vena cava (IVC) occurs in patients with increased intraabdominal pressure (IAP). SUBJECTS AND METHODS: We retrospectively reviewed 59 contrast-enhanced computed tomographic (CT) scans performed over a 2-year period in patients with evidence of increased IAP. We also reviewed CT scans performed in a control group of 30 normal patients. The intrahepatic and suprahepatic IVC segments were assessed for narrowing. RESULTS: Narrowing of the suprahepatic IVC was never observed in the patients with elevated IAP. Slit-like narrowing of the upper intrahepatic IVC was noted in 11 (44%) of 25 patients; the intrahepatic IVC was not evaluated in 34 other patients with liver abnormalities or unsatisfactory opacification of the intrahepatic IVC. In control subjects, narrowing was not observed in either the intrahepatic or suprahepatic IVC. CONCLUSION: Narrowing of the upper intrahepatic IVC can be seen in some patients with increased IAP. The cause and significance of this phenomenon remain to be determined.

Dilatation of the inferior vena cava in patients with cirrhotic portal hypertension. Causes and imaging findings.

Dilatation of the inferior vena cava is a frequent finding in patients with cirrhosis and portal hypertension, and may be produced by various mechanisms. In this article we illustrate the spectrum of causes and appearances of inferior vena caval dilatation in patients with cirrhosis and portal hypertension.

CT evaluation of pararectal varices.

PURPOSE: This study was undertaken to determine the prevalence of pararectal varices on CT scan in patients with portal hypertension and to see if dilatation of the inferior mesenteric vein (IMV) or the presence of pararectal varices on CT correlates with rectal varices noted on colonoscopy. METHOD: We reviewed 83 consecutive CT scans of the abdomen and pelvis performed in patients with portal hypertension. The size and prevalence of pararectal varices were determined. Correlation with colonoscopic and endoscopic reports was performed. The diameter of the IMV was compared in those patients with pararectal varices with that in those patients without, as was the presence of esophageal varices. RESULTS: Twenty patients (24%) had CT evidence of pararectal varices, ranging from 5 to 11 mm in diameter (mean 7.8 mm). Colonoscopic correlation was available in 30 patients. Of these, 6 of 30 (20%) had pararectal varices on CT and no rectal varices on colonoscopy, 3 of 30 (10%) had pararectal varices on CT and rectal varices on colonoscopy, and 3 of 30 (10%) had no pararectal varices on CT but did have rectal varices on colonoscopy. Endoscopic correlation (available in 48 patients) demonstrated esophageal varices in 88% of patients with rectal or pararectal varices and in 66% of patients without rectal or pararectal varices (p = 0.170). The IMV was significantly larger in patients with pararectal varices (mean diameter 7.5 mm, SD 2.3) as compared with those without (mean diameter 5.8 mm, SD 2.0) (p = 0.014). However, in patients with colonoscopically proven rectal varices, only two of six (33%) had an IMV diameter of > or = 7 mm. CONCLUSION: Inclusion of the pelvis on CT scans of patients with portal hypertension can yield further information about the presence and extent of pararectal venous collaterals, which may be of particular importance in those patients requiring pelvic surgery. The presence of pararectal varices on CT and the diameter of the IMV do not correlate with the presence of rectal varices on colonoscopy. Decompression of portal hypertension by rectal and pararectal varices does not result in a decreased incidence of esophageal varices.

CT findings of bowel and mesenteric injury.

Bowel and mesenteric injuries are common sequelae of blunt abdominal trauma. CT represents a valuable modality in the diagnosis of bowel and mesenteric injuries. While certain findings on CT are highly specific, such as free air and extravasation of oral contrast agent, they are insensitive and seen only in the minority of patients. Therefore, radiologists must focus their attention on the bowel wall and mesentery to improve their diagnostic accuracy in these injuries. Bowel wall thickening and/or abnormal bowel wall enhancement must be noted. Mesenteric abnormalities, which can consist of mesenteric infiltration, interloop fluid, or fluid trapped in the leaves of the small bowel mesentery, may be crucial yet subtle clues. Knowledge of their typical appearance may aid in their diagnosis. This pictorial essay illustrates the range of findings in bowel and mesenteric injuries as well as possible pitfalls to help in their prompt recognition and diagnosis.

Sarcoid myopathy: imaging findings.

Sarcoidosis is a granulomatous multisystem disorder that may uncommonly involve muscle. Muscular sarcoid may be nodular, atrophic myopathic, or acute myositic. We illustrate a case of the myopathic type of muscular sarcoid that is unusual because the abdominal wall muscles, rather than the extremity muscles, were involved. Muscular involvement by sarcoid should be considered in the differential diagnosis of focal muscle disease, especially in a patient with a known history of sarcoid. The presence of typical bilateral hilar adenopathy on a chest radiograph as well as the presence of abdominal findings (hepatosplenomegaly and retroperitoneal adenopathy) may help establish the diagnosis. Otherwise, sonographically guided biopsy may be necessary for definitive diagnosis.

Benign extraovarian mimics of ovarian cancer. Distinction with imaging studies.

Imaging of the pelvis via computed tomography (CT), ultrasound, or magnetic resonance (MR) provides excellent anatomical detail and superb resolution. Despite this, radiologists often have difficulty reaching a specific diagnosis in evaluating adnexal masses. A wide spectrum of benign extraovarian pathology may closely resemble ovarian cancer. Fallopian tube disease such as hydrosalpinx, tuboovarian abscess, and chronic ectopic pregnancy may mimic cystic or solid ovarian neoplasm. Pedunculated uterine leiomyomas may imitate ovarian lesions. Gastrointestinal causes of adnexal masses include mucocele, abscess, and hematoma. These entities may appear similar to ovarian lesions, thus requiring close attention to specific anatomical detail in order to help differentiate them. Similarly, peritoneal disease including tuberculous peritonitis and peritoneal pseudocyst may simulate ovarian tumor. While ultrasound represents the initial imaging modality in the evaluation of most pelvic disease, MR's multiplanar capability and improved tissue characterization make it a valuable modality in many circumstances.

Low attenuation of acute traumatic hemoperitoneum on CT scans.

OBJECTIVE: This study was undertaken to determine the incidence of low attenuation values in intraperitoneal hemorrhage, which could be confused with ascites. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 42 consecutive patients with hepatic and splenic lacerations and intraperitoneal fluid after blunt abdominal trauma. Patients were excluded if they had prior peritoneal lavage, bladder or bowel injury, or low hematocrit values. Intraperitoneal fluid was categorized by the site of accumulation (perihepatic, perisplenic, Morison's pouch, paracolic gutters, or pelvis). The amount of fluid in each intraperitoneal location was categorized as small, moderate, or large. Attenuation values were obtained from each intraperitoneal site, and overall mean attenuation values were determined for each patient. We correlated the size of each fluid collection with the attenuation value. We also compared attenuation values at locations adjacent to the site of each injury with those at other intraperitoneal sites. We then evaluated technical factors that could have lowered attenuation values, including CT miscalibration, volume averaging, and beam-hardening artifacts. RESULTS: For the 42 patients, we measured 131 separate attenuation values. Attenuation values ranged from 0 to 80 H, with attenuation of 24% of sites (32/131) measuring less than 20 H. Only 16% of sites (21/131) had attenuation values greater than 45 H. Attenuation at the remaining 78 sites (60%) measured from 20 to 45 H. All intraperitoneal locations except the pelvis had mean attenuation values significantly lower then 40 H. Mean attenuation values (determined by averaging measurements from different intraperitoneal sites) were also calculated for each patient. Only 6 (14%) of 42 patients had mean attenuation values greater than 40 H, whereas 4 (10%) of 42 patients had mean attenuation values less than 20 H. The remaining 32 patients (76%) had mean attenuation values between 21 and 40 H. Patients with hepatic lacerations showed no significant difference (p = .3509) in attenuation between perihepatic fluid and the remainder of intraperitoneal fluid. However, in patients with splenic lacerations, perisplenic fluid had a significantly higher (p = .0013) attenuation value (43 H) than did fluid at other intraperitoneal locations. CONCLUSION: Low attenuation measurements for acute hemoperitoneum represented a common finding that was not attributable to technical factors or underlying anemia. Fluid with attenuation values less than 20 H in acute trauma should not be dismissed as ascitic fluid.

Wedge-shaped intrahepatic cholangiocarcinoma: MRI-pathologic correlation.

On magnetic resonance imaging (MRI) studies, wedge-shaped areas of signal abnormality noted in association with liver lesions have been attributed to secondary phenomena and are said to be substantially larger than the actual tumor. We describe the MRI and pathological appearance of a wedge-shaped cholangiocarcinoma. In cases where therapy might be affected, biopsy of wedge-shaped MRI abnormalities associated with hepatic malignancy should be considered for accurate tumor staging.

Ultrasonography of hepatic arteries in the portacaval space: celiac versus superior mesenteric artery origin.

A hepatic artery coursing within the portacaval space was seen in 30 (18.3%) of 164 consecutive patients in whom this region was seen with ultrasonography. In 12 subjects (40%) this vessel represented the right hepatic artery arising from the proximal celiac artery. In the other 18 subjects (60%) this vessel arose from the superior mesenteric artery. It should not be assumed that a hepatic artery traversing the portacaval space arises from the superior mesenteric artery until its origin is clearly documented.

Transient arteriovenous fistulae after transrectal prostate biopsy: diagnosis with color Doppler ultrasonography.

To assess the prevalence and significance of arteriovenous fistulae after prostate biopsy, we performed color Doppler ultrasonography immediately after 136 consecutive transrectal prostate needle biopsies. Pathologic results were correlated with color Doppler ultrasonographic findings. Arteriovenous fistulae developed after 17 biopsies (13%), all closed spontaneously within 18 minutes, and none were associated with unusual bleeding. Carcinoma was noted in 25 biopsy specimens (18%), 10 (40%) of which were followed by arteriovenous fistula. The correlation between malignancy and postbiopsy arteriovenous fistula was statistically significant (P < 0.0004), consistent with hypervascularity known to be present in many prostate cancers.

CT in patients with blunt abdominal trauma: clinical significance of intraperitoneal fluid detected on a scan with otherwise normal findings.

OBJECTIVE: The purpose of this study was to determine the clinical significance of intraperitoneal fluid seen on CT scans with otherwise normal findings in patients with blunt abdominal trauma. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 60 patients with blunt abdominal trauma who had scans showing normal findings except for the presence of intraperitoneal fluid. The location of the fluid was determined (pouch of Douglas, pelvis, paracolic gutters, mesentery, Morison's pouch, perihepatic or perisplenic spaces). The amount of fluid in each location was categorized as minimal, moderate, or marked. The total volume of fluid in each patient was estimated as small (+1), intermediate (+2), or large (+3) on the basis of the sum of the amount of fluid in the individual peritoneal locations. The amount and location of fluid were compared between patients who required exploratory laparotomy and those who were managed conservatively. RESULTS: In most patients, the total fluid volume was small (44 patients, 73%) as opposed to intermediate (11 patients, 18%) or marked (five patients, 8%). Thirty-seven patients had fluid in one location, 12 patients had fluid in two locations, and 11 patients had fluid in three or more locations. Intraperitoneal fluid tended to accumulate in the pouch of Douglas (67%) and Morison's pouch (33%). Patients requiring laparotomy had a higher total fluid volume score compared with the patients managed conservatively (2.2 versus 1.3, p < .002) and had larger amounts of fluid in the upper abdomen. Laparotomy was required in only one patient (2%) who had a small amount of fluid compared with three patients (27%) with intermediate and two patients (40%) with marked amounts. Mesenteric and/or bowel injuries were noted in all six patients at laparotomy. One patient had a small superficial liver laceration that was not diagnosed with CT. No other injuries to the solid viscera were missed on the scans. Two of the four patients with mesenteric fluid seen on the CT scan had mesenteric lacerations found during surgery, and the remaining two did well with conservative management. CONCLUSION: Patients with blunt abdominal trauma who have small amounts of intraperitoneal fluid as the sole abnormality shown by CT may generally be treated conservatively. However, patients with even a small quantity of mesenteric fluid may benefit from peritoneal lavage to help exclude bowel or mesenteric injury. Intermediate and large amounts of fluid are less common as the sole CT abnormality but have a higher likelihood of being associated with bowel or mesenteric injury.

Cardiophrenic varices in portal hypertension: evaluation with CT.

PURPOSE: To determine the prevalence and appearance of cardiophrenic angle (CPA) varices at computed tomography (CT) in patients with portal hypertension (PHT). MATERIALS AND METHODS: A retrospective review was performed of 148 consecutive contrast material--enhanced abdominal CT scans of patients with PHT. The paracardiac region was assessed for tubular structures suggestive of varices. Variceal diameter and CT attenuation relative to adjacent liver were noted. RESULTS: Tubular structures consistent with CPA varices were noted in 29 cases and were more common on the right side than on the left. Mean CPA variceal diameter was 2.6 mm. In three cases, right CPA varices measured 10-13 mm in diameter, but no variceal enhancement was noted on initial dynamic CT images. Delayed CT demonstrated contrast enhancement that reflected delayed enhancement of the portal venous system. CONCLUSION: CPA varices, particularly on the right side, are not uncommon in patients with PHT. Varices should be considered and excluded as a cause of CPA masses, particularly before percutaneous biopsy. Delayed CT may be necessary to correctly delineate CPA varices.

Imaging of percutaneous tube gastrostomies: spectrum of normal and abnormal findings.

Enteral alimentation is a crucial component of care for the malnourished patient who cannot eat. Until recently, long-term alimentation was delivered through nasogastric tubes or gastrostomy tubes placed at surgery. In the past few years, percutaneous endoscopic gastrostomy (PEG) has almost completely supplanted these traditional methods. PEG is a safer and better-tolerated procedure. The advantages of PEG over nasogastric tubes include greater social acceptance and improved cosmetic appearance, increased ease of feedings, and decreased nasal alar deformities and gastroesophageal reflux. Complications are less common with PEG than with open gastrostomy but still occur in as many as 15% of cases [1-3]. Percutaneous gastrostomies performed using fluoroscopic guidance have complications in approximately 10% of cases [4]. Despite a rapid increase in the use of percutaneous gastrostomies and their placement by radiologists [4], few published reports have described imaging findings after the placement of such tubes. This pictorial essay illustrates a spectrum of normal and abnormal imaging findings observed with the use of PEG tubes, including tube migration and misplacement, infection, tumor seeding along the PEG tube track, and a variety of gastric wall defects and pseudomasses.