Pancreatitis associated with pancreatic carcinoma. Preoperative diagnosis: role of CT imaging in detection and evaluation.

The combined occurrence of pancreatic carcinoma with acute or chronic pancreatitis is seldom seen in medical practice, but when present it is a challenging dilemma, plagued by confusing overlapping clinical findings and pitfalls in diagnostic imaging tests. This article reviews the presumptive pathophysiological aspects of this relationship, the perplexing clinical presentations and the advantages and limitations of the noninvasive imaging examinations. The role of state-of-the-art CT imaging in screening patients with acute and chronic pancreatitis is emphasized and the impute of additional more invasive tests in detecting pancreatic tumors in this cohort of patients is reviewed. The habitual use of CT imaging, followed when needed by complementary examinations, can improve on previously reported low detection rates and hopefully decrease the number of exploratory laparatomies and unnecessary major pancreatic surgical resections.

Toxic megacolon: role of CT in evaluation and detection of complications.

The purpose of this study is to determine the role of CT in the evaluation and in detecting complications in patients with toxic megacolon. A retrospective analysis of CT findings of 18 consecutive patients with toxic megacolon was performed. Underlying etiology included 12 patients with pseudomembranous colitis (PC), four patients with ulcerative colitis and two patients with cytomegalovirus colitis. Eleven patients were HIV+. CT features, correlation with severity of disease and development of complications were analyzed. Colonic dilatation with intraluminal air and/or fluid with a distorted colonic contour or an ahaustral pattern was seen in all patients. In four patients (22%), CT depicted complications-two colonic perforations and two septic thrombosis of the portal system. Six patients died (33%), three of whom had the above complications. The presence and degree of submucosal edema (accordion sign, target sign), wall thickening, degree of dilatation, nodular contour and ascites did not correlate with clinical outcome. Two thirds of patients with toxic megacolon had PC as the underlying etiology. CT was helpful in depicting diffuse colitis, and it was instrumental in detecting life-threatening abdominal complications, contributing to the management of these patients. CT abnormalities cannot be used to predict the clinical outcome unless complications develop.

Cystic pancreatic masses: cross-sectional imaging observations and serial follow-up.

BACKGROUND: We retrospectively reviewed the imaging features of a series of patients with cystic pancreatic masses, the majority of whom underwent imaging surveillance. METHODS: Imaging data from 30 patients with known cystic pancreatic masses were reviewed. Nine patients had surgical and/or cytologic classification. Of the 21 who were not operated on, all underwent serial imaging surveillance. Of these, five had corroborative endoscopic retrograde cholangiopancreatography and 16 were followed by only computed tomography and/or magnetic resonance imaging. RESULTS: In the nonoperated group, mean follow-up time was 30 months (3-144 months). Two patients demonstrated growth, and the remainder remain stable. In the patients who underwent surgery, invasive carcinoma was found in those with lesions larger than 4 cm, involvement of the main pancreatic duct, or visible solid components on the imaging study. Smaller lesions were benign. CONCLUSION: In patients with suspected cystic pancreatic neoplasms, surveillance might be possible if lesions are smaller than 2.5 cm, spare the main pancreatic duct, and demonstrate no solid components.

Hemorrhagic complications of pancreatitis: radiologic evaluation with emphasis on CT imaging.

OBJECTIVE: To analyze and describe the incidence, pathophysiology, radiographic diagnosis and the initial management of hemorrhagic complications associated with pancreatitis. MATERIAL AND METHODS: Among 1,910 patients diagnosed of having pancreatitis in the last 10 years, 26 developed hemorrhagic complications (1.3%). These complications were detected from 2 months to 8 years after one or several episodes of pancreatitis with a mean of 2.3 years. Radiographic studies were reviewed and clinical management and outcome were recorded. RESULTS: Ten patients had CT evidence of pancreatic necrosis, 12 patients chronic pancreatitis, and 17 patients pancreatic pseudocysts. The cause of hemorrhage was bleeding pseudoaneurysm in 16 patients (61%), diffuse bleeding with pancreatic necrosis in 5 patients (19.5%) and hemorrhagic pseudocysts in 5 patients (19.5%). Intra-abdominal hemorrhage developed in 21 patients and gastro-intestinal bleeding in 5 patients. Arterial embolization was attempted in 12 patients and was successful in 9 patients (75%). Surgery was used in 16 patients and the overall mortality rate was 11%. CONCLUSIONS: Hemorrhagic complications are rarely seen and are usually late sequelae of pancreatitis. They develop because of leaking or ruptured pseudoaneurysms, diffuse bleeding in pancreatic necrosis, and hemorrhagic pseudocysts. Early detection followed by angiography, embolization and/or surgery has decreased mortality rates.

Septic thrombophlebitis of the mesenteric and portal veins: CT imaging.

Pylephlebitis or septic thrombophlebitis of the portal vein and its tributaries is an acute ascending infection arising often from a primary gastrointestinal inflammatory lesion. Common primary sources of infection are diverticulitis, appendicitis, and infected pancreatic necrosis. CT imaging can diagnose this complication at an early stage and can significantly improve the previously reported high mortality and morbidity rates associated with this condition.

Significance of minimal or no intraperitoneal fluid visible on CT scan associated with blunt liver and splenic injuries: a multicenter analysis.

BACKGROUND: The use of ultrasound (U/S) for the evaluation of patients with blunt abdominal trauma is gaining increasing acceptance. Patients who would have undergone computed tomographic (CT) scan may now be evaluated solely with U/S. Solid organ injuries with minimal or no free fluid may be missed by surgeon sonographers. OBJECTIVE: The purpose of this study was to describe the incidence and clinical importance of liver and splenic injuries with minimal or no free intraperitoneal fluid visible on CT scan. We hypothesized that these solid organ injuries occur infrequently and are of minor clinical significance. METHODS: Patient records and CT scans were reviewed for the presence of and outcome associated with blunt liver and splenic injuries with minimal (<250 mL) or no free fluid detected by an attending radiologist. Data were collected from six major trauma centers during a 4-year period before the introduction of U/S and included demographics, grade of injury (American Association for the Surgery of Trauma scale), need for operative intervention, and outcome. RESULTS: A total of 938 patients with liver and splenic injuries were identified. In this group, 11% of liver injuries and 12% of splenic injuries had no free fluid visible on CT scan and could be missed by diagnostic peritoneal lavage or U/S. Of the 938 patients, 267 (28%) met the inclusion criteria; 161 had injury to the spleen and 125 had injury to the liver. In the 267 patients studied, 97% of the injuries were managed nonoperatively. However, 8 patients (3%) required operative intervention for bleeding. Compared with the liver, the spleen was significantly more likely to bleed (p = 0.01), but the grade of splenic injury was not related to the risk for hemorrhage (p = 0.051). CONCLUSION: Data from this study suggest that injuries to the liver or spleen with minimal or no intraperitoneal fluid visible on CT scan occur more frequently than predicted but usually are of minimal clinical significance. However, patients with splenic injuries may be missed by abdominal U/S. We found a 5% associated risk of bleeding. Therefore, abdominal U/S should not be used as the sole diagnostic modality in all stable patients at risk for blunt abdominal injury.

The accordion sign at CT: a nonspecific finding in patients with colonic edema.

PURPOSE: To determine whether the "accordion sign" is a specific computed tomographic (CT) sign of Clostridium difficile colitis. MATERIALS AND METHODS: Fifty-seven patients with CT evidence of severe colitis, as judged by colonic wall thickening, an abnormal haustral pattern, the target sign, and stranding of the pericolic fat, were identified from a computerized CT database for 25 months. CT images were retrospectively evaluated for the presence of oral contrast material in the colon and for the accordion sign. The medical and laboratory records of all patients were reviewed and correlated with CT findings to establish the cause of colitis. RESULTS: Oral contrast material had reached the colon in 35 of 57 patients at the time of the CT examination. The images in 15 of these patients demonstrated the accordion sign, and those in 20 patients did not. C difficile colitis was documented in four of the 15 cases displaying the accordion sign. In the remaining 11 patients, a different cause was documented. Oral contrast material had not reached the colon in the remaining 22 patients. Within this group with findings similar to the accordion sign, five patients had documented C difficile colitis, and four had colitis from other causes. CONCLUSION: The accordion sign is indicative of severe colonic edema or inflammation, but it is not specific for C difficile colitis.

Ischemic colitis: CT evaluation of 54 cases.

PURPOSE: To review the computed tomographic (CT) scans and medical records of 54 patients with proved ischemic colitis, define the spectrum of CT findings, and assess the effect of CT imaging on treatment. MATERIALS AND METHODS: The mean age of the patients was 72 years. CT scans were analyzed for the presence of colonic abnormalities and associated findings. Ischemia was clinically unsuspected in 16 patients (30%). RESULTS: Segmental involvement was seen in 48 patients (89%), with a mean length of involvement of 19 cm (range, 5-38 cm). Wall thickness varied between 2 and 20 mm (mean, 8 mm). All parts of the colon were involved. The CT appearance of the colonic wall varied: (a) A wet appearance with heterogeneous areas of edema was seen in 33 patients (61%). (b) A dry appearance with mild homogeneous thickening was seen in 18 patients (33%). (c) Intramural air was present in three patients (6%). Ischemia resolved in 41 patients (76%), and complications occurred in 13 patients (24%). CONCLUSION: CT can be used to confirm the clinical suspicion of ischemic colitis, to suggest ischemia when it is unsuspected, and to diagnose complications. Intrinsic colonic abnormalities cannot be used to diagnose or predict the development of infarction.

CT diagnosis of ileal diverticulitis.

The preoperative diagnosis of ileal diverticulitis has been reported during small-bowel series when inflammatory changes are associated with ileal diverticula. Previous CT reports of this entity have failed to establish the specific diagnosis preoperatively. We report the CT findings in a patient with right lower quadrant pain that enabled the specific diagnosis of ileal diverticulitis to be made.

Appendicitis: the impact of computed tomography imaging on negative appendectomy and perforation rates.

OBJECTIVES: The purposes of this study were to investigate the use of computed tomography (CT) imaging in patients with suspected acute appendicitis and to evaluate the impact of CT on negative appendectomy and perforation rates. In patients clinically diagnosed of acute appendicitis the reported overall negative appendectomy rate is about 15-20%; 10% in men and 25-45% in women of childbearing age. This is associated with a perforation rate of 21-23%. METHODS: This is a retrospective analysis of 146 consecutive patients presenting with clinical symptoms suspicious of appendicitis over a 2-yr period in whom CT examinations were performed before therapy was instituted. The overall negative appendectomy and perforation rates were calculated for the entire group, as well as for the 54 women aged 15-50 yr in the childbearing cohort. RESULTS: The negative appendectomy rate was 4% in 122 patients operated on and the perforation rate was 22%. Among 36 women 15-50 yr of age operated on, the negative appendectomy rate was 8.3% and the perforation rate was 19%. Surgery was avoided in 24 patients, 18 of whom were women of childbearing age. CONCLUSIONS: The judicious use of CT imaging in patients with equivocal clinical presentation suspected of having appendicitis led to a significant improvement in the preoperative diagnosis. It resulted in a substantial decrease in the negative appendectomy rate compared to previously published reports, without incurring an increase in the perforation rate.

Intestinal ischemia in patients in whom small bowel obstruction is suspected: evaluation of accuracy, limitations, and clinical implications of CT in diagnosis.

PURPOSE: To determine the accuracy of computed tomography (CT) in diagnosis of intestinal ischemia in patients with possible intestinal obstruction and the limitations and clinical implications of use of CT. MATERIALS AND METHODS: In 100 patients in whom intestinal obstruction was suspected clinically, CT findings were correlated with surgical findings in 77 patients and with follow-up clinical findings after nasogastric suction in 23 patients. The interval between CT and surgical exploration in patients with ischemic bowel was 1-98 hours (mean, 13 hours). RESULTS: Correlation of CT findings of strangulation obstruction with surgical findings revealed 72 true-negative, 19 true-positive, five false-positive, and four false-negative CT results. Sensitivity was 83%, specificity was 93%, accuracy was 91%, positive predictive value was 79%, and negative predictive value was 95%. CONCLUSION: CT enables accurate detection of bowel ischemia, particularly when small bowel obstruction is present. Exploratory laparotomy should be performed when unexplained disparities exist between equivocal CT findings and a deteriorating clinical condition in patients with possible small bowel obstruction or mesenteric infarction.

CT of small-bowel lymphoma in immunocompetent patients and patients with AIDS: comparison of findings.

OBJECTIVE: The purpose of this study was to describe and analyze the CT features of small-bowel lymphoma, compare those features with the radiographic presentation in immunocompetent patients and patients with AIDS, and discuss the role of CT in the initial detection and evaluation of this disease. MATERIALS AND METHODS: Abdominal CT examinations of 42 consecutive patients with proven small-bowel lymphoma were retrospectively reviewed. In 19 patients, small-bowel examinations were also available for review. The 42-patient study group was divided into two subgroups: 22 patients with AIDS and 20 immunocompetent patients. RESULTS: Primary small-bowel lymphoma was present in 37% of patients and was equally distributed between the two subgroups. The histologic types included non-Hodgkin's lymphoma in 33 patients, Burkitt's lymphoma in seven patients, Hodgkin's lymphoma in one patient, and mucosa-associated lymphoid tissue-type lymphoma in one patient. Solid organ involvement (liver, splee, kidney, or adrenal glands) was detected in 22% of patients with AIDS and in 10% of the immunocompetent patients. We saw two main patterns of CT appearance. In the first pattern, single or multiple segments had circumferential wall thickening, homogeneous in attenuation, that ranged from 1.5 cm to 7 cm (mean, 2.6 cm) in 33 patients. In the second pattern, single or multiple cavitary lesions were revealed as nodular and grossly enlarged intestinal lumen with bowel wall thickening in 13 patients. A polypoid mass that was entirely intraluminal was seen in one patient. Heterogeneous areas of low attenuation were revealed in two intestinal tumors of HIV-positive patients. Mesenteric or retroperitoneal lymphadenopathy was seen in 45% of patients with AIDS and 60% of the immunocompetent patients. The gross morphologic features, distribution. pattern of CT presentation, degree of wall thickening, and length of involvement were all similar in the two subgroups. CONCLUSION: More than half (52%) of the individuals with small-bowel lymphoma diagnosed at our institution in the last 4 years were patients with AIDS. The features revealed by CT scans were characteristic or highly suggestive of small-bowel lymphoma. We saw no significant differences in the radiographic features of patients with AIDS and immunocompetent patients.

CT evaluation of infradiaphragmatic air in patients treated with mechanically assisted ventilation: a potential source of error.

OBJECTIVE: The purpose of this study was to describe the CT features of infradiaphragmatic air that may develop in patients after mechanically assisted ventilation, its location, its pathway of transdiaphragmatic dissection, and its extension into the abdomen. MATERIALS AND METHODS: We retrospectively evaluated six consecutive adult patients with pneumomediastinum associated with positive end-expiratory pressure therapy who developed intraabdominal air and were imaged with CT in our institution-between 1993 and 1995. Abdominal CT examinations were reviewed and correlated with the clinical findings, follow-up examinations, and exploratory laparotomies in four patients. RESULTS: In four patients, air present in the anterior mediastinum (endothoracic fascia) was seen to extend into the anterior abdominal wall within the extraperitoneal space. In a fifth patient, the air was located extraperitoneally and intraperitoneally. In the remaining patient, air was present exclusively in the peritoneal cavity. In only two patients did we detect small amounts of air in the posterior retroperitoneum. In five patients, we also detected subcutaneous emphysema and/or air dissection into the muscle planes of the anterolateral abdominal wall. CONCLUSION: In patients on mechanically assisted ventilation, anterior mediastinal air can dissect through the diaphragm into the anterior abdominal extraperitoneal space. This anterior pathway of infradiaphragmatic extension of air can be erroneously diagnosed as intraperitoneal air, which may lead to unnecessary exploratory laparotomies. Also, anterior mediastinal air can enter the peritoneal cavity, particularly in patients with a history of median sternotomy.

Salmonella- and Shigella-induced ileitis: CT findings in four patients.

PURPOSE: The purpose of this study is to describe and illustrate the CT appearance of four cases of acute terminal ileitis induced by nontyphoidal Salmonella and Shigella infection and to review the radiographic and endoscopic findings of these entities. METHOD: The medical records, CT examinations, and small bowel examinations of three patients with Salmonella ileitis and one patient with Shigella ileitis were retrospectively reviewed. CT examinations were done in four patients, colonoscopy in three patients, and small bowel examinations in two patients. Stool cultures established the diagnosis of nontyphoidal Salmonella enteritis in three patients and Shigella enteritis in one patient. The patients' symptoms and clinical findings resolved promptly following supportive therapy and appropriate antibiotic therapy. RESULTS: CT showed slight circumferential and homogeneous thickening of the terminal ileum over a segment of 10-15 cm in patients with Salmonella ileitis. Associated mild thickening of the wall of the colon was present in addition. Small bowel examination performed in one patient revealed a spastic terminal ileum with thickened mucosal folds. Colonoscopy revealed acute colitis involving the colon diffusely in one case, but sparing the distal 50 cm of the colon in one case. CT showed more pronounced thickening of the terminal ileum and a target configuration in the patient with Shigella ileitis. Small bowel examination revealed narrowing, irregular contour, several large nodular defects (thumbprinting), and a severely ulcerated mucosa affecting the terminal ileum. Colonoscopy revealed a normal colon and large ulcerations with fibropurulent exudate in the terminal ileum. CONCLUSION: In patients with severe Salmonella or Shigella infections or persistent and/or confusing clinical presentations, CT can play a complementary but important role in the initial diagnostic evaluation. It avoids clinical mismanagement, circumvents unnecessary invasive procedures, and contributes to the efficient workup and therapy in this group of individuals.

CT in patients with scirrhous carcinoma of the GI tract: imaging findings and value for tumor detection and staging.

OBJECTIVE: The purposes of this study were to analyze the CT features of scirrhous carcinoma of the gastrointestinal (GI) tract and to assess the usefulness of CT in detecting and staging these lesions. MATERIAL AND METHODS: This is a retrospective evaluation of 31 proven cases of scirrhous carcinoma (linitis plastica) of the GI tract imaged in our institution from 1986 to 1994. Twenty-two patients had primary gastric carcinoma, and nine had carcinoma of the colon (rectosigmoid in eight and right colon in one). CT examinations were reviewed and correlated with pathologic and/or surgical findings in all patients and with barium examinations in 19 cases. A modified Dukes classification was used to stage these lesions without knowledge of the pathologic and surgical results. RESULTS: Four gastric lesions were missed during the initial CT examination. Seventeen patients had extensive circumferential lesions, and five had focal plaquelike lesions. The wall thickness ranged from 1 to 3 cm (mean, 1.8 cm). Homogeneous enhancement was seen in 17 patients, slightly heterogeneous enhancement was seen in one, a target configuration was present in two patients, and intramural calcification was present in one patient. All colonic lesions were circumferential, homogeneously enhancing with a wall thickness ranging from 1 to 3 cm (mean, 2 cm). CT scans showed limitations in evaluating local parameters. Compared with surgical and pathologic staging, CT correctly staged 26 patients, understaged four patients, and overstaged one patient. Among the 19 patients with pathologically proven stage D lesions (61%), CT correctly staged 17 patients (89%) and had a 100% positive predictive value. One case of hepatic metastases, 13 cases of malignant ascites, and 11 cases of omental and peritoneal metastases were found. CONCLUSION: CT is an important complimentary imaging technique to detect scirrhous carcinoma. The sensitivity of detection depends on the size of the lesion and the quality of the examination. CT has limitations in staging early lesions but shows a high sensitivity (89%) in detecting Dukes stage D lesions. Accurate CT staging in these individuals (61% in this series) allows a more adequate treatment strategy and avoids unnecessary exploratory laparotomies.

Imaging and intervention in acute pancreatitis.

An International Symposium was held in Atlanta in 1992 to present the state of the art of diagnostic evaluation and management of acute pancreatitis and to agree on an acceptable series of clinical definitions for classifying the disease and its complications. The symposium was composed of 40 internationally recognized experts in pancreatic disease from 15 countries representing six disciplines (anatomy, gastroenterology, internal medicine, pathology, radiology, and surgery). The purpose of this article is to present the radiologically relevant aspects of the symposium; to define the state of the art of imaging and intervention in acute pancreatitis, particularly how and when to use computed tomography and how and when to perform percutaneous therapy versus surgery; and to encourage radiologists to use precise and proper nomenclature when describing the morphologic manifestations of acute pancreatitis as depicted by various imaging modalities.