Pitfalls and mimickers at 64-section helical CT that cause negative appendectomy: an analysis from 1057 appendectomies.

PURPOSE: To determine the rate of negative appendectomy and clarify the causes of negative appendectomy in patients with clinically suspected acute appendicitis who had surgery after 64-section helical computed tomography (CT). MATERIAL AND METHODS: A retrospective analysis of 1057 patients who had appendectomy after 64-section helical CT was performed to determine the rate of negative appendectomy. The 64-section helical CT examinations obtained with submillimeter and isotropic voxels in the patients with negative appendectomy were analyzed by two readers and compared to clinical, operative and histopathological reports, discharge summaries and original radiology reports. RESULTS: The negative appendectomy rate was 1.7% (18/1057). Appendix enlargement (>6 mm) and fat stranding were present in 17 (17/18; 94%) and 6 patients (6/18; 33%), respectively. In 13 patients (13/18; 72%) 64-section helical CT findings were consistent with acute appendicitis. Interpretive errors in original imaging reports were identified in five patients (5/18; 28%). CONCLUSION: The preoperative use of 64-section helical CT results in a very low rate of negative appendectomy. Patients with negative appendectomy have 64-section helical CT findings consistent with a diagnosis of acute appendicitis in the majority of cases. Interpretive errors are less frequent.

Which Factors Influence the Detection of an Inflamed Appendix: Comparative Assessment of Ultrasonography and CT

PURPOSE: To compare and assess factors influencing the detection of an inflamed appendix by both ultrasonography (US) and CT. MATERIALS AND METHODS: We retrospectively analyzed US and CT findings of 58 patients with confirmed acute appendicitis (42 patients with perforation and 16 patients without perforation), in which both preoperative US and CT scans were performed. We compared the use of US and CT for the diagnostic accuracy of acute appendicitis, and determined the detection rate for an inflamed appendix. According to the location of the appendix, the amount of mesenteric fat content in lower abdominal cavity, the presence of cecal wall thickening, and the presence of pericecal fluid or an abscess, the use of US and CT were compared for the determination of the detection rate of an inflamed appendix. RESULTS: The diagnostic accuracies for US and CT for acute appendicitis in our study group were both 93.1%, and there was no difference between the use of the two modalities. Although the detection rate of an inflamed appendix was slightly higher for US (93.1%) than for CT (84.5%), the difference between the use of the two modalities was not significant (p > 0.05). There was no significant difference in the detection rate of an inflamed appendix between the use of US and CT according to location of appendix, the amount of mesenteric fat content and the presence of cecal wall thickening. A pelvic location of the inflamed appendix and the presence of pericecal fluid or an abscess, were factors that significantly increased the detection rate for US than for CT (p < 0.05). CONCLUSION: The use of US for diagnosis of acute appendicitis is as useful as the use of CT. US is especially useful to detect an inflamed appendix more effectively than CT in cases where the appendix is in a pelvic location and presents with pericecal fluid or an abscess.

Schwannoma of the Appendix: A Case Report

Schwannoma is a benign neurogenic tumor arising from the nerve sheath, and it presents as a well defined mass. Isolated gastrointestinal schwannoma is a relatively rare finding and schwannoma of the appendix is extremely rare. We report here on a case of schwannoma that arose from the appendix, and this lesion was pathologically confirmed.

CT Findings of Acute Appendicitis in Children

Acute appendicitis is the most common cause of surgical abdomen in children. Because of the various locations where you can find the appendix and the different presentation for the symptoms of appendicitis, the clinical diagnosis of appendicitis is often difficult in children, and radiologic diagnosis is becoming increasingly important. Being familiar with the findings of acute appendicitis on the MDCT axial image and the multiplanar reformation images may aid the physician in reaching an early diagnosis and so prevent complications and reduce negative appendectomy rates.

Acute Appendicitis: Sensitivity, Specificity and Diagnostic Accuracy of Thin-Section Contrast-Enhanced CT Findings

PURPOSE: To assess the sensitivity, specificity, and diagnostic accuracy of individual contrast-enhanced helical CT findings of acute appendicitis. MATERIALS AND METHODS: We retrospectively reviewed the appendiceal helical CT scans, obtained after intravenous contrast administration (abdomen; 7-mm collimation, abdominopelvic junction; 5-mm collimation), of 50 patients with surgically proven acute appendicitis and 112 with alternative diagnoses. The following parameters were analysed by three radiologists: enlarged appendix (> 6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), (appendiceal) intraluminal air, (appendiceal) intraluminal air extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. RESULTS: The CT findings of acute appendicitis that statistically distinguished it from alternative diagnoses were an enlarged appendix (sensitivity; 92%, specificity; 93%, diagnostic accuracy; 93%), appendiceal wall thickening (for these three parameters: 68%, 96% and 88%, respectively), periappendiceal fat stranding (90%, 79%, 82%), appendiceal wall enhancement (72%, 86%, 82%), appendicolith (16%, 100%, 74%), and focal cecal apical thickening (14%, 100%, 74%) (for each, p < 0.05). CONCLUSION: On thin-section contrast-enhanced helical CT, an enlarged appendix and periappendiceal fat stranding were found in 90% or more patients with acute appendicitis. Appendiceal wall thickening and enhancement were clearly demonstrated and significant findings for diagnosis. Less common but specific findings include appendicolith, focal cecal apical thickening and intramural air, can also help us establish a diagnosis of acute appendicitis.

Complete Invagination of Vermiform Appendix with Adenocarcinoma

Appendiceal intussusception is a very rare pathological condition, an incidence, as revealed by appendectomy specimens, of only 0.01 percent. There are various types among which complete invagination of the appendix is very rare. We encountered a case of intussusception of the appendix with complete invagination induced by appendiceal adenocarcinoma. A preoperative diagnosis of appendiceal adenocarcinoma and intussusception was not possible, but a final pathological report confirmed these conditions and retrospective analysis of a barium enema showed a finger-like filling defect of the cecum, a relatively specific finding in such cases. We describe a case involving a 39-year old man who one month earlier had noted the onset of pain in the right lower abdomen.

Primary Appendiceal Lymphoma Presenting as Acute Appendicitis: A Case Report

Because primary lymphoma of the appendix is a very rare disorder and commonly presented as acute appendicitis,it is seldom diagnosed by preoperative imaging study. We encountered a patient with pathologically proved primaryappendiceal lymphoma associated with acute and chronic appendicitis. Ultrasonogram revealed a non-compressiblesausage-shaped hypoechoic mass with a linear hyperechoic center caused by mucosa-lumen interface in right lowerquadrant. Post-contrast CT examination showed a markedly enlarged target-like appendix with obliteration of thelumen; the outer layer showed higher attenuation than the central portion. There were also multiple strands in theperiappendiceal fat and thickening of adjacent lateroconal fascia and colonic wall, and this suggested acuteappendicitis associated with appendiceal lymphoma.

Value of Noncontrast Spiral CT for Suspected Acute Appendicitis

PURPOSE: To assess the diagnostic accuracy and clinical efficacy of noncontrast spiral CT in patients withsuspected acute appendicitis. MATERIALS AND METHODS: Over a six-month period, 100 patients with suspected acuteappendicitis were prospectively evaluated with noncontrast spiral CT. All scans were obtained from the lower bodyof L3 to the symphysis pubis, with 5mm or 10mm collimation and pitich of 1 or 1.5, and without intravenous or oralcontrast material. Diagnosis was established by means of surgical or clinical follow-up. Prospective diagnosisbased on CT findings was compared with surgical results and clinical follow-up. RESULTS: Acute appendicitis wasconfirmed in 47 of 100 patients. On the basis of the basis of the CT findings, SI patients were prospectivelyinterpreted as positive for appendicitis, but in six the diagnosis was false-positive. Two of the 47 with acuteappendicitis were prospectively interpreted as normal. The preoperative diagnosis of acute appendicitis was, thus,45 true-positive, 47 true-negative, six falsepositive and two false-negative, yielding a sensitivity of 96%, aspecificity of 89%, an accurace of 92%, a positive predictive value of 88%, and a negative predictive value of96%. Using CT, an alternative diagnosis was established in 14 patients. CONCLUSION: Noncontrast spiral CT is auseful technique for diagnosing acute appendicitis.

CT Findings of Perforated Appendicitis: Comparison of Child and Adult Patient

PURPOSE: To evaluate the CT findings of patients with surgically confirmed perforated appendicitis and to compare the characteristics between children and adults. METHOD AND MATERIALS: Patients in whom complicated appendicitis was clinically suspected underwent contrast enhanced CT scanning. The scans of 50 patients (19children and 31 adults) with surgically confirmed perforated appendicitis were analysed. Without knowledge of operative findings, we retrospectively analyzed the CT findings with regard to : 1) the detection of the appendiceal wall thickening; 2) the presence of appendicolith; 3) the size, features, and location of periappendical abscess; 4) mesenteric fat infiltration and lymphadenopathy; 5) wall thickening of the cecum and terminal ileum; and 6) ascites and free air. RESULTS: Appendiceal wall thickening was detected in seven children(37%) and 13 adults (42%) (p>0.05). Appendicolith was detected in 21 patients (42%) and was more frequent in children (13 cases, 68%) than in adults (8 cases, 26%). There were statistically significant differences between the two groups (p0.05). Periappendiceal abscess with well-defined cyst was more frequent in children (17/19, 89%) than in adults (13/31,42%) (p<0.05). The most commonly involved site was the midabdomen and pelvis in children (9/19, 47%), and the right lower quadrant in adults (18/31, 58%), (p <.05). Mesenteric lymph nodes were commonly detected in children, and cecal wall thickening in adults. CONCLUSION: The CT findings of perforated appendicitis included appendiceal wall thickening, appendicolith, periappendiceal abscess, mesenteric fat infiltration and enlargement of mesentericlymph nodes, and thickening of the cecum wall Periappendiceal abscess with well-defined cyst in the midabdomen or pelvis was more frequent in children, as were appendicolith and enlargement of mesenteric lymph nodes.

CT Appearances of Appendiceal Diseases

Cross-sectional imaging plays an increasing role in the diagnosis of appendiceal diseases due to known highnegative appendectomy rate. It is important for radiologists to be aware of the computed tomographic (CT)appearances of various pathologies and common associated findings which can mimic other diagnostic entities. Inthis article, the author illustrates the CT appearances of a spectrum of appendiceal disaeses and outlinespotential diagnostic pitfalls.

Malignant Tumors of the Appendix: Imaging Findings

Malignant tumors of the appendix are rare and are histologically similar to those arising elsewhere in theintestines. The frequency of specific tumor types and the clinical presentation of symptomatic tumors are,however, significantly different. Before surgery, correct diagnosis of a malignant appendiceal tumor is rare; mosttumors are diagnosed by a pathologist while examining an appendectomy specimen. With the advent of high resolutionimaging modalities (ultrasound and helical CT), malignant tumors of the appendix may be more accurately diagnosed;this report describes the imaging findings of malignant appendiceal tumors.