The acute right lower quadrant

Rapid MRI Abdomen for Assessment of Clinically Suspected Acute Appendicitis in the General Adult Population: a Systematic Review

OBJECTIVES

To perform a systematic review on the use of magnetic resonance imaging (MRI) of the abdomen to evaluate clinically suspected appendicitis in the general adult population. We examined the diagnostic accuracy, the reported trends of MRI use, and the factors that affect the utility of MRI abdomen, including study duration and cost-benefits.

METHODS

We conducted a systematic literature search on PubMed, MEDLINE, Embase, Web of Science, and Cochrane Library databases. We enrolled primary studies investigating the use of MRI in diagnosing appendicitis in the general adult population, excluding studies that predominantly reported on populations not representative of typical adult appendicitis presentations, such as those focusing on paediatric or pregnant populations.

RESULTS

Twenty-seven eligible primary studies and 6 secondary studies were included, totaling 2,044 patients from eight countries. The sensitivity and specificity of MRI for diagnosing appendicitis were 96% (95% CI: 93-97%) and 93% (95% CI: 80-98%), respectively. MRI can identify complicated appendicitis and accurately propose alternative diagnoses. The duration of MRI protocols in each primary study ranged between 2.26 and 30 minutes, and only one study used intravenous contrast agents in addition to the non-contrast sequences. Decision analysis suggests significant benefits for replacing computed tomography (CT) with MRI and a potential for cost reduction. Reported trends in MRI usage showed minimal utilisation in diagnostic settings even when MRI was available.

CONCLUSIONS

MRI accurately diagnoses appendicitis in the general adult population and improves the identification of complicated appendicitis or alternative diagnoses compared to other modalities using a single, rapid investigation.

Does Orally-Administered Radiocontrast Impair Ultrasound Image Quality in Pediatric Patients?

Introduction

It is commonly assumed that orally-administered radiocontrast material (ORC) preceding abdominal ultrasound (US) performance can obscure image quality and potentially impair diagnostic accuracy when assessing patients with abdominal pain. Due to this concern, ORC administration per protocol for computed tomography (CT) is often delayed until after US performance, potentially contributing to prolonged length of stay in the emergency department (ED) in patients with concern for abdominal pathology. The objective of this study was to evaluate whether early administration of ORC in children with abdominal pain receiving abdominal CT for possible appendicitis obscures subsequent abdominal US image quality.

Methods

We designed a prospective observational study of children <18 years of age presenting to a pediatric ED with abdominal pain who were set to receive ORC prior to obtaining an abdominal CT. These patients received a point-of-care ultrasound (POCUS) of the abdomen to assess the abdominal aorta and right lower quadrant (RLQ) structures (psoas muscle and iliac vessels) pre- and post-ORC administration. Images were compared independently by two blinded emergency US-certified physician-assessors for quality, specifically to determine whether ORC obscured the anatomical structures in question.

Results

A total of 17 subjects were enrolled, and each subject had two POCUS studies of the abdomen, one pre- and one post-ORC administration looking to visualize the anatomy of the RLQ and abdominal aorta in both studies. Statistical analysis showed no significant differences in mean values of POCUS image quality scoring by two blinded US-trained physician-assessors for either RLQ structures or abdominal aorta when performed pre- and post-administration of ORC.

Conclusion

Early ORC administration in children with abdominal pain does not adversely affect image quality of a subsequently performed abdominal US. Patients who may require abdominal CT to determine the etiology of abdominal pain can receive early administration of ORC prior to US performance to help minimize ED length of stay without impairing US diagnostic accuracy.

Acute non-traumatic abdominal pain by quadrant: relative yield of CT and clinical evaluation for diagnosis in 1000 patients

OBJECTIVE

To determine the relative diagnostic yield of contrast-enhanced CT in adults presenting with symptoms referable to a specific abdominal quadrant.

METHODS

Electronic health records review systematically identified patients meeting the following inclusion criteria: adults (≥ 18 years) undergoing IV contrast-enhanced abdominopelvic CT for acute non-traumatic symptoms referable to a specific abdominal quadrant (RLQ/LLQ/LUQ/RUQ). The CT-based diagnosis and any clinical diagnosis in the absence of CT diagnosis were recorded. The final cohort of 1000 subjects (mean age, 48.1 years; 647F/353M) consisted of consecutive sub-cohorts of 250 patients for each abdominal quadrant. Positive oral contrast was utilized in 91.6% (916/1000) of cases.

RESULTS

A positive CT diagnosis was provided in 47.3% (473/1000) of all patients, and was highest for LLQ (58.8%) and RLQ (58.0%) symptoms, including diverticulitis and appendicitis in 23.6% and 24.8% cases, respectively. CT positivity was lower for the LUQ (34.4%) and RUQ (38.0%) (p < 0.0001), with no single diagnosis representing > 5% of cases. However, all quadrants provided valuable triage of 218 hospital admissions (21.8%), 83.0% were CT positive, whereas 62.7% of 782 discharged patients were CT negative. Only 7.0% of CT-negative patients were admitted. A clinical-only diagnosis was provided in 9.3% of the total cohort (93/1000), representing 17.6% of the CT-negative cohort (93/527).

CONCLUSION

The rate of positive CT diagnosis is considerably higher for the lower abdominal quadrants, predominately due to appendicitis and diverticulitis. However, CT results (positive vs. negative) for all four quadrants strongly correlated with hospital admission versus discharge. Clinical-only diagnosis represented < 10% of all cases.

Acute appendicitis: Factors associated with inconclusive ultrasound study and the need for additional computed tomography

PURPOSE

To identify variables associated with inconclusive ultrasound examination and the need for further abdominopelvic computed tomography (CT) examination for the diagnosis of acute appendicitis.

MATERIALS AND METHODS

A total of 105 adult patients with acute appendicitis were included. There were 55 patients (38 men, 17 women; mean age, 23±9 [SD] years; range: 15-58 years) with a diagnosis of acute appendicitis using ultrasound alone and 50 patients (30 men, 20 women; mean age, 31±14 [SD] years; range: 16-83 years) who required further CT. Demographic, clinical, and biological criteria and appendix location were compared between the two groups to search for variables associated with the need of further CT.

RESULTS

Patients who required further CT were older (31.1±14 [SD] years) and had a greater body mass index (BMI) (26.7±4.3 [SD]kg/m²) than those who did not require CT (23±9 [SD] years and 22.9±3.4 [SD]kg/m²), respectively (P<0.01). A greater proportion of patients with complicated acute appendicitis was observed in patients who required further CT (9/50; 18%) than in those who had only ultrasound (1/55; 2%) (P=0.012). Atypical appendix location was more frequent in patients who required CT (19/50; 36%) than in those who had only ultrasound (6/55; 11%) (P<0.001). There were no significant differences regarding gender, inflammatory syndrome and hours of imaging (on call vs. working hours) between the two groups.

CONCLUSION

Advanced age, high BMI, atypical appendix location, and complicated appendicitis are associated with inconclusive ultrasound and the need for further CT to diagnose acute appendicitis.

Accuracy of 64-row multidetector CT in the diagnosis of surgically treated acute abdomen

OBJECTIVE

To assess the accuracy of 64-row computed tomography (CT) in the differential diagnosis of acute abdomen in the emergency department.

MATERIALS AND METHODS

Prospective analysis of 181 patients with surgically treated acute abdomen.

RESULTS

In 158/181 cases, CT was totally concordant with surgical repertoire. Partial concordance was found in 15 cases. Overall sensitivity was 87.3% when only cases of complete concordance were considered, 95.6% if also partial concordance cases were included.

CONCLUSION

CT showed high reliability in the differential diagnosis of acute abdomen surgically treated, although associated conditions can sometimes be missed.

Computed tomographic scan diagnosis of appendicitis in children by pediatric and adult radiologists

OBJECTIVES

Computed tomographic (CT) scans are an accepted radiographic mode to the diagnosis of appendicitis. Radiologists play a critical role in its diagnostic accuracy. The purpose of this study was to determine whether there is a difference in the diagnostic accuracy between pediatric and general radiologists interpreting pediatric abdominal/pelvic CT scans for appendicitis.

METHODS

Computed tomographic scans of 10 patients (5 with appendicitis and 5 without appendicitis) were presented on a password-protected Web site. Radiologists rated the CT scans for the likelihood of appendicitis on a grading scale from 1 to 5.

RESULTS

This is a report of data from 6 pediatric radiologists and 13 general radiologists. For appendicitis cases, the pediatric radiologists gave a "positive" interpretation in 26 (87%) of the cases, whereas the general radiologists gave a "positive" interpretation in 57 (89%) of the cases. Of the true positives, pediatric radiologists rated 25 (96%) of 26 as a high likelihood of appendicitis with a score of 1, whereas general radiologists rated 44 (77%) of 57 as high likelihood. In cases without appendicitis, the pediatric radiologists had a true negative interpretation rate of 83%, and the general radiologists had a true negative interpretation rate of 73%. Of the true negatives, pediatric radiologists rated 22 (88%) of 25 with a rating of 4, being "no appendicitis," whereas the general radiologists rated 39 (85%) of 46 with a rating of 4.

CONCLUSIONS

There is a similar accuracy rate in the interpretation of CT scans positive for appendicitis between general and pediatric radiologists, but pediatric radiologists were more definitive.

[Usefulness of ultrasonography in children with right iliac fossa pain]

Acute pain in the right iliac fossa is common in children. It can arise from a wide variety of gastrointestinal and genitourinary processes that make up the differential diagnosis with acute appendicitis. In this article, we describe the most representative findings of these processes on ultrasonography. We emphasize the characteristics that enable these processes to be differentiated from acute appendicitis.

Beyond appendicitis: common and uncommon gastrointestinal causes of right lower quadrant abdominal pain at multidetector CT

Right lower quadrant abdominal pain is one of the most common causes of a patient visit to the emergency department. Although appendicitis is the most common condition requiring surgery in patients with abdominal pain, right lower quadrant pain can be indicative of a vast list of differential diagnoses and is thus a challenge for clinicians. Other causes of right lower quadrant pain beyond appendicitis include inflammatory and infectious conditions involving the ileocecal region; diverticulitis; malignancies; conditions affecting the epiploic appendages, omentum, and mesentery; and miscellaneous conditions. Multidetector computed tomography (CT) has emerged as the modality of choice for evaluation of patients with several acute traumatic and nontraumatic conditions causing right lower quadrant pain. Multidetector CT is an extremely useful noninvasive method for diagnosis and management of not only the most common causes such as appendicitis but also less common conditions.

Acute appendicitis in young adults: low- versus standard-radiation-dose contrast-enhanced abdominal CT for diagnosis

PURPOSE

To compare low and standard radiation doses in intravenous contrast material-enhanced abdominal computed tomography (CT) for the diagnosis of acute appendicitis in young adults.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived informed consent. The study included 257 patients (age range, 15-40 years) who underwent CT for suspected appendicitis performed by using a low radiation dose (n = 125) or a standard radiation dose (n = 132). Receiver operating characteristic (ROC) analysis, Fisher exact tests, and Mann-Whitney U tests were used to compare the diagnosis of appendicitis and diagnostic confidence as recorded in prospective CT reports between the two groups.

RESULTS

For 55 low-radiation-dose (median dose-length product, 122 mGy · cm) and 44 standard-dose (median dose-length product, 544 mGy · cm) examinations, one of two abdominal radiologists made primary reports that served as final reports. For the remaining examinations, on-call radiologists with differing levels of experience issued preliminary reports and the two abdominal radiologists then provided final reports. In the primary reports, the low- and standard-dose CT groups did not significantly differ in area under the ROC curve (0.96 vs 0.97, P = .76), sensitivity (90% [38 of 42] vs 89% [47 of 53], P > .99), or specificity (92% [76 of 83] vs 94% [74 of 79], P = .74) in the diagnosis of appendicitis. There was also no significant difference between the two groups in the confidence level when diagnosing (P = .71) or excluding (P = .20) appendicitis in the primary reports. Similar results were observed for the final reports. The two dose groups also did not significantly differ in terms of appendiceal visualization, diagnosis of appendiceal perforation, or sensitivity for alternative diagnoses.

CONCLUSION

Low-dose CT may have comparable diagnostic performance to standard-dose CT for the diagnosis of appendicitis in young adults.

Epiploic appendagitis: an entity frequently unknown to clinicians--diagnostic imaging, pitfalls, and look-alikes

OBJECTIVE

Epiploic appendagitis is an ischemic infarction of an epiploic appendage caused by torsion or spontaneous thrombosis of the epiploic appendage central draining vein. When it occurs on the right side of the abdomen, it can mimic appendicitis and right-sided diverticulitis; whereas when it occurs on the left side of the abdomen, it is often mistaken for sigmoid diverticulitis. The purpose of this article is to review the diagnostic imaging of this entity.

CONCLUSION

Epiploic appendagitis is self-limited and spontaneously resolves without surgery within 5-7 days. Therefore, it is imperative for radiologists to be familiar with this entity.

[Imaging tests in acute abdominal pain]

Acute abdominal pain constitutes a diagnostic challenge for the physician. The list of diseases that can cause abdominal pain is very extensive. Some of these conditions may be serious and life-threatening. The medical history is fundamental for the judicious choice of the most suitable diagnostic tests. Plain abdominal x-ray has little diagnostic efficiency although it comprises the initial diagnostic test when perforation of a hollow viscus, intestinal obstruction or ingestion of a foreign body is suspected. Abdominal ultrasound is the test of choice in suspected biliary tract pathology, complicated renal colic and gynaecological disease. Abdominal computed axial tomography (CT) may be the most sensitive and specific imaging test for diagnosing most causes of abdominal pain but should be reserved for selected cases.

Independent predictors of acute appendicitis on CT with pathologic correlation

RATIONALE AND OBJECTIVES

To assess computed tomographic (CT) signs that have been described in published studies for the diagnosis of appendicitis to identify independent findings that predict appendicitis.

METHODS AND MATERIALS

A retrospective database search identified 67 patients with a CT scan of the abdomen/pelvis and pathologic evaluation of the appendix, including 41 with appendicitis and 26 with a normal appendix on pathologic examination. Each computed tomogram was re-evaluated by three independent, blinded observers who evaluated appendix diameter, enhancement of the appendix, thickening of the appendix, presence of an appendicolith, infiltration of peri-appendiceal fat, focal cecal thickening, local lymphadenopathy, fluid collections, non-appendiceal bowel thickening, non-periappendiceal infiltration of fat, and comparison of peri-appendiceal fat infiltration to thickening of adjacent bowel loops.

RESULTS

Mean diameter of the normal appendix (6.7 +/- 2.2 mm) was significantly lower than that of the inflamed appendix (12.1 +/- 4.3 mm; P < .001). Significant univariate predictors of appendicitis included appendix diameter >8 mm (odds ratio [OR] 34.8), enhancement of the appendix (OR 4.4), thickening of the appendix (OR 4.3), infiltration of peri-appendiceal fat (OR 5.5), focal cecal thickening (OR 5.1), non-appendiceal bowel thickening (OR 0.4), and non-periappendiceal infiltration of fat (OR = 0.3). Of these variables, only appendix diameter and enhancement of the appendix were significant independent predictors of appendicitis on multivariate analysis. An overall diagnostic impression based on all secondary signs was less accurate than a diagnosis based on appendix diameter alone (receiver-operating characteristic analysis: Az = 0.80 vs. Az = 0.91, P = .02). Sensitivity/specificity of appendix diameter was 84%/87% using a cutoff between 8 and 9 mm and 97%/48% using a cutoff between 6 and 7 mm.

CONCLUSION

Appendix diameter is the best single diagnostic criterion for appendicitis on CT scan. A cutoff between 8 and 9 mm provided the best balance of sensitivity/specificity in our study population, whereas a cutoff between 6 and 7 mm improved sensitivity at the expense of specificity. The presence of appendiceal enhancement provided additional diagnostic information, but other secondary signs of appendicitis did not improve diagnostic accuracy.

Added diagnostic value of multiplanar reformation of multidetector CT data in patients with suspected appendicitis

Computed tomography (CT) is an accurate and effective modality for the diagnosis and staging of appendicitis. CT provides rapid and complete evaluation of patients with suspected appendicitis and clearly demonstrates the typical findings of appendicitis, including a distended appendix, periappendiceal fat stranding, an appendicolith, and focal thickening of the cecum. Identification of an inflamed appendix at CT may be difficult in certain patients (eg, patients with scanty intraabdominal fat, an unusual location of the cecum and appendix, prominent cecal wall thickening and pericecal fat stranding, small bowel dilatation, or abscess formation adjacent to the right adnexa). In such cases, multiplanar reformation (MPR) of multidetector CT data may provide improved appendiceal visualization and increase the physician's confidence in diagnosing appendicitis. Moreover, the use of MPR in addition to conventional CT may provide improved visualization of the normal appendix and thereby enhance confidence in excluding appendicitis and diagnosing diseases that mimic appendicitis. Consequently, the radiologist should obtain MPR images in the evaluation of patients with suspected appendicitis to help ensure the correct diagnosis.

CT scan in patients with suspected appendicitis: clinical implications for the acute care surgeon

OBJECTIVE

To determine the influence of computed tomography (CT) scans on diagnosis and management of patients with suspected appendicitis.

METHODS

Retrospective 2-year review of 1,630 patients with suspected appendicitis, categorized into three groups based on the likelihood (Alvarado scores) of having appendicitis. Group 1: low likelihood (Alvarado score < or =4); group 2: intermediate likelihood (Alvarado scores 5-7), and group 3: high likelihood (Alvarado score > or = 8). CT scan utilization, hospital course, and final pathology were retrospectively reviewed.

RESULTS

More patients received a CT scan in 2006 as compared with 2005 (60 vs. 52%; p = 0.001). The overall appendectomy rate was similar between the 2 years (57% in 2005 vs. 57% in 2006; p = 0.995). The overall appendectomy rate in patients with a CT was significantly higher as compared with those without (60 vs. 53%; p = 0.002). The appendectomy rate in patients with Alvarado scores < or =4 and no CT scan was significantly lower than in those with a CT scan (12 vs. 48%; p < 0.0001). The overall negative appendectomy rate in patients with a CT scan was similar to that in those without: 31/546 (6%) vs. 23/383 (6%).

CONCLUSIONS

CT scan utilization increased the appendectomy rate only in patients with a low clinical suspicion for appendicitis. Preoperative CT scans did not decrease the negative appendectomy rate.

Abdominal Computed Tomography in the Evaluation of Acute and Perforated Appendicitis in the Community Setting

Several studies report sensitivity and specificity of abdominal computed tomography scans (CT) for the evaluation of acute appendicitis as high as 98 per cent. Despite increased utilization of CT, the rate of negative appendectomy has remained constant at 10 to 20 per cent. The objective of this study was to assess the effectiveness of CT in the evaluation of acute and perforated appendicitis in an academic community-based setting. A retrospective review of 550 patient charts with International Classification of Diseases-9 (ICD-9) codes for acute and perforated appendicitis from January 2002 to October 2005 was performed. Sensitivity of CT was 87 per cent with a positive predictive value of 92 per cent. Specificity was 42 per cent with a negative predictive value of 29 per cent. Negative appendectomy rates were similar with or without CT (11% vs 13%, respectively). Our data suggests that CT used liberally in everyday practice in a community-based setting to evaluate acute appendicitis may not have as strong of a diagnostic value as those used in protocol-driven research studies. Further prospective studies are needed to formulate criteria to better delineate the role of CT in the evaluation of acute appendicitis.

Hyperdense appendix on unenhanced CT: a sign of acute appendicitis

The purpose of this study was to evaluate the presence of the hyperdense appendix in acute appendicitis. The CT scans of 183 patients with pathologically proven acute appendicitis were reviewed to determine the prevalence of a hyperdense appendix, defined as a high-attenuated appendix when compared with the adjacent cecal wall on precontrast CT. A control group consisted of 100 patients with CT examinations performed in the emergency department were also randomly allocated to search for any hyperdense appendix in other disease conditions. The images were reviewed by two radiologists who reached a decision by consensus. A hyperdense appendix sign was found in 61 of 183 (33%) patients, including 92 men and 91 women ranging in age from 17 to 85 years (mean 37 years). On the other hand, the sign was seen in only two (2%) of the 88 patients in whom appendicitis was not diagnosed. The hyperdense appendix sign on unenhanced CT is seen in about 33% of patients with acute appendicitis. The false-positive rate is very low, rendering it a very useful sign for diagnosis of acute appendicitis.

Current Concepts in Imaging of Appendicitis

Appendicitis is the most common cause of acute abdominal pain requiring surgery. Early diagnosis is crucial to the success of therapy. CT and ultrasound are widely recognized as very useful in the timely diagnosis of appendicitis. MR imaging is emerging as an alternative to CT in pregnant patients and in patients who have an allergy to iodinated contrast material. This article reviews the current imaging methods and diagnostic features of appendicitis.

Right Lower Quadrant Pain: Value of the Nonvisualized Appendix in Patients at Multidetector CT

PURPOSE

To retrospectively determine the value of the nonvisualized appendix at multidetector computed tomography (CT) in patients with acute right lower quadrant pain in whom appendicitis was a consideration.

MATERIALS AND METHODS

Institutional review board approval was obtained for this HIPAA-compliant study, with waiver of informed consent. Records were retrospectively reviewed in patients who presented to the emergency department between April 29 and October 31, 2003, with right lower quadrant pain. Scanning was performed with the same eight-detector row CT scanner by using oral and (unless contraindicated) intravenous contrast agents, and transverse and coronal reformations were obtained. Two radiologists prospectively evaluated all scans at the time of the examination and rendered a consensus opinion. Clinical follow-up of at least 3 months' duration was performed retrospectively for patients whose appendix was not visualized to determine whether appendicitis had developed. Statistical analysis and calculation of percentages with confidence intervals (CIs) were performed.

RESULTS

Of the 400 consecutive patients who underwent multidetector CT, 132 (33.0%) were male and 268 (67.0%) were female. Eighty patients (20.0%) had acute appendicitis and 79 (19.8%) had another cause for abdominal pain. A normal appendix with no other cause for pain was seen in 182 patients (45.5%). In 59 patients (14.8%), the appendix was not visualized. Of these 59 patients, 50 had adequate follow-up. Clinical follow-up was uneventful in 49 of these 50 patients. Thus, on otherwise normal multidetector CT scans in patients suspected of having acute appendicitis, nonvisualization of the appendix was negative for appendicitis in 98% (95% CI: 71%, 100%) of cases. Conversely, when the appendix was seen at multidetector CT and was abnormal, appendicitis was present in 95% (95% CI: 72%, 100%) of cases.

CONCLUSION

In patients with right lower quadrant pain, a nonvisualized appendix at multidetector CT reliably excludes acute appendicitis.

Increased Use of Computed Tomography Does Not Harm Patients with Acute Appendicitis

The increased use of computed tomography (CT) in patients with appendicitis may cause a delay in surgery and, therefore, higher perforation rates. We examined the use of CT, delay in time to surgery, and perforation rates in appendicitis patients operated on in two periods: Phase 1, 1996 through 1998 and Phase 2, 2001 through 2002. CT was performed in 18 per cent of the Phase 1 group compared with 62 per cent in the Phase 2 group. In the Phase 1 group, patients undergoing CT had a delay to surgery compared with those without CT (18.6 hours vs 7 hours; P < 0.0001). In the Phase 2 group, time to surgery was reduced (median time = 12 hours with CT vs 6 hours without CT; P < 0.001). CT was more accurate in the later group; there were less false-negative and equivocal studies. There was no difference in perforation rates between the Phase 1 and 2 groups. Over time, the increased use, efficiency, and accuracy of CT in patients with acute appendicitis were associated with reduced delays to surgery. The use of CT did not harm patients, but did not translate to better overall outcomes in this group of patients.

Rapid CT diagnosis of acute appendicitis with IV contrast material

The purpose of this study was to determine the sensitivity and specificity of computed tomography (CT) without administration of oral contrast in confirming suspected acute appendicitis. One hundred seventy-three patient studies were retrieved by a computer-generated search for the word "appendicitis" in radiology reports. Patients presenting to the emergency department over an 8-month period were examined for acute abdominal pain or suspected acute appendicitis. IV-contrast-enhanced CT scans of the abdomen and pelvis were obtained without oral or rectal contrast. Criteria for diagnosis of acute appendicitis included a dilated appendix (>6 mm), periappendiceal inflammation, or abscess. Final diagnoses were established with surgical/clinical follow-up, histopathological analysis or both. The standard time (1 h) for the administration of oral contrast prior to the CT scan was eliminated. Fifty-nine CT diagnoses were made of acute appendicitis, 56 of which were histologically verified and three of which resulted in another diagnosis. One hundred fourteen CT diagnoses were negative for appendicitis. This corresponds to a sensitivity of 100% and specificity of 97%, a positive predictive value of 95%, and a negative predictive value of 100%. CT with IV contrast is sensitive and specific for the confirmation or exclusion of acute appendicitis. By eliminating the time required to administer oral contrast, the diagnosis might be made more rapidly.

CT Evaluation of Appendicitis and Its Complications: Imaging Techniques and Key Diagnostic Findings

OBJECTIVE

This article reviews various CT protocols for appendicitis, identifies key CT findings for diagnosing appendicitis, discusses unusual manifestations such as chronic and recurrent appendicitis, and profiles imaging features that differentiate appendicitis from other inflammatory and neoplastic ileocecal conditions. Patients were studied with helical CT.

CONCLUSION

CT is a highly accurate, noninvasive test for appendicitis, but the optimal CT technique is controversial. Major complications of appendicitis (perforation, abscess formation, peritonitis, bowel obstruction, septic seeding of mesenteric vessels, gangrenous appendicitis) and their management are discussed. Abdominal CT is a well-established technique in the study of acute abdominal pain and has shown high sensitivity and specificity for diagnosing and differentiating appendicitis, providing an accurate diagnosis in the early stages of disease.

Helical CT Evaluation of Acute Right Lower Quadrant Pain: Part II, Uncommon Mimics of Appendicitis

OBJECTIVE

The purpose of our pictorial essay is to highlight the helical CT features of uncommon mimics of appendicitis and to provide clues to differentiate them from appendicitis.

CONCLUSION

Uncommon mimics of appendicitis create a diagnostic challenge in patients with right lower quadrant pain. Recognition of the helical CT features of uncommon mimics of appendicitis is important in clinical management and avoiding unnecessary laparotomy.

Mimics of Renal Colic: Alternative Diagnoses at Unenhanced Helical CT

During the past decade, unenhanced computed tomography (CT) has become the standard of reference in the detection of urinary calculi owing to its high sensitivity (>95%) and specificity (>98%) in this setting. Numerous diseases may manifest as acute flank pain and mimic urolithiasis. Up to one-third of unenhanced CT examinations performed because of flank pain may reveal unsuspected findings unrelated to stone disease, many of which can help explain the patient's condition. Alternative diagnoses are most commonly related to gynecologic conditions (especially adnexal masses) and nonstone genitourinary disease (eg, pyelonephritis, renal neoplasm), closely followed by gastrointestinal disease (especially appendicitis and diverticulitis). Hepatobiliary, vascular, and musculoskeletal conditions may also be encountered. Vascular causes of acute flank pain must always be considered, since these constitute life-threatening emergencies that may require the intravenous administration of contrast material for diagnosis. Radiologists must be familiar with the typical findings of urinary stone disease at unenhanced CT, as well as the spectrum of alternative diagnoses that may be detected with this modality, to accurately diagnose the source of flank pain.