Primary Rectal Syphilis Mimicking Lymphoma: A Case Report and Literature Review.

Primary rectal syphilis is a rare disease that can be misdiagnosed as lymphoma or other rectal cancers on sigmoidoscopy or CT. Here, we report a case of primary rectal syphilis mimicking rectal malignancy in a 23-year-old male who presented with a rectal mass and multiple lymphadenopathies. In this case report and literature review, we focused on the CT findings and endoscopic observations of primary rectal syphilis. Infectious diseases, such as rectal syphilis, should be considered in the differential diagnosis of young patients with unusual rectal lesions and disproportionately extensive lymphadenopathies.

Ilio-Iliac Arteriovenous Fistula with May-Thurner Syndrome: A Case Report.

An ilio-iliac arteriovenous fistula (AVF) is rare. Common factors leading to ilio-iliac AVF include congenital malformations, iatrogeny, and trauma. There is limited documentation in the literature of cases involving ilio-iliac AVF with May-Thurner syndrome. Here, we present a case of an ilio-iliac AVF with May-Thurner syndrome in an 80-year-old male. CT and angiography confirmed extensive ilio-iliac AVF. Successful endovascular procedures for ilio-iliac AVF were performed using several variable-sized coils and 1400-2000 µm gelatin particles. After embolization, follow-up abdominopelvic CT revealed an improvement in edema in the left leg.

Added Value of Structured Reporting for US of the Pediatric Appendix: Additional CT Examinations and Negative Appendectomy.

Purpose: This study aimed to determine the incremental value of using a structured report (SR) for US examinations of the pediatric appendix. Materials and Methods: Between January 2009 and June 2016, 1150 pediatric patients with suspected appendicitis who underwent US examinations of the appendix were included retrospectively. In November 2012, we developed a five-point scale SR for appendix US examinations. The patients were divided into two groups according to the form of the US report: free-text or SR. The primary clinical outcomes were compared between the two groups, including the rate of CT imaging following US examinations, the negative appendectomy rate (NAR), and the appendiceal perforation rate (PR). Results: In total, 550 patients were included in the free-text group and 600 patients in the SR group. The rate of additional CT examinations decreased by 5.3% in the SR group (8.2%, p = 0.003), and the NAR decreased by 8.4% in the SR group (7.8%, p = 0.028). There was no statistical difference in the appendiceal PR (37.6% vs. 48.0%, p = 0.078). Conclusion: The use of an SR to evaluate US examinations for suspected pediatric appendicitis results in lower CT use and fewer negative appendectomies without an increase in appendiceal PR.

Useful Ultrasound Findings of Pediatric Patients with Equivocal Results of Appendicitis: Analysis Based on a Structured Report Form.

Purpose: To identify the features that can be used for differentiating appendicitis from non-appendicitis in pediatric patients with equivocal ultrasound (US) results. Materials and Methods: A total of 53 pediatric patients (≤ 18 years old) with equivocal results on US examination for suspected appendicitis between November 2012 and October 2017 were included. US evaluation was conducted based on information retrieved from a predefined structured report form. Then, the likelihood of appendicitis was prospectively classified into five categories. The equivocal results were considered as grade 3 (indeterminate) and grade 4 (probably appendicitis). Results: Of the 53 patients, 25 (47.2%) and 28 (52.8%) were classified into grade 3 and 4 groups, respectively. Among the individual US findings, increased vascularity of the appendiceal wall and peri-appendiceal fat infiltration were independent findings associated with the diagnosis of appendicitis (p = 0.005, p = 0.045, respectively) in the multivariate logistic regression analysis and showed the highest diagnostic accuracy (69.8% and 62.3%, respectively). Conclusion: Increased vascularity within the appendiceal wall and peri-appendiceal fat infiltration were significant predictors of appendicitis in patients with equivocal US findings.

Transcatheter Removal of Bone Cement Embolism in the Right Atrium after Percutaneous Vertebroplasty: The Embolus Broke in Half and Migrated to the Right Pulmonary Artery Intraoperatively.

Bone cement embolism often occurs during percutaneous vertebroplasty. Bone cement pulmonary arterial embolism generally requires no treatment because of the small size and asymptomatic manifestation. Intracardiac bone cement embolisms are rare but associated with a risk of severe complications. Intracardiac bone cement embolisms are mainly removed through open heart surgery. To the best of our knowledge, only three cases of intracardiac bone cement embolisms removed with interventions have been reported. Here, we report another case of successful transcatheter retrieval of a 6-cm-long cement embolism in the right atrium after percutaneous vertebroplasty. The embolus broke in half and migrated to the right pulmonary artery intraoperatively. Using two snares and a filter retrieval device, we advanced from opposite directions. Further, we gently grasped and pulled the fragments of the right pulmonary artery and aligned them in a linear fashion directly into the sheath for uneventful removal.

Using 2-mSv Appendiceal CT in Usual Practice for Adolescents and Young Adults: Willingness Survey of 579 Radiologists, Emergency Physicians, and Surgeons from 20 Hospitals.

OBJECTIVE: To survey care providers' willingness to use 2-mSv computed tomography (CT) in their usual practice for adolescents and young adults with suspected appendicitis. MATERIALS AND METHODS: An ethical committee approved this prospective study. We introduced 2-mSv CT in 20 hospitals through a pragmatic clinical trial. At the final phase of the trial, we invited 698 potentially-involved care providers in the survey regarding their willingness to use 2-mSv CT. Multivariable logistic regression analyses were performed to identify factors associated with willingness. Nine months after the completion of the trial patient recruitment, we surveyed whether the hospitals were using 2-mSv CT in usual practice. RESULTS: The analyses included responses from 579 participants (203 attendings and 376 trainees; 221 radiologists, 196 emergency physicians, and 162 surgeons). Regarding the willingness to immediately change their standard practice to 2-mSv CT, 158 (27.3%), 375 (64.8%), and 46 (7.9%) participants responded as "yes" (consistently), "partly" (selectively), and "no", respectively. Willingness varied considerably across the hospitals, but only slightly across the participants' departments or job titles. Willingness was significantly associated with attendings (p = 0.004), intention to maintain the dedicated appendiceal CT protocol (p < 0.001), belief in compelling evidence on the carcinogenic risk of conventional-dose CT radiation (p = 0.028), and hospitals having more than 1000 beds (p = 0.031). Fourteen of the 20 hospitals kept using 2-mSv appendiceal CT in usual practice after the trial. CONCLUSION: Despite the extensive efforts over the years of this clinical trial, many care providers were willing to use 2-mSv CT selectively or not willing to use.

Value of Additional Ultrasound Examination in Patients with Equivocal Computed Tomography Findings of Acute Appendicitis: Comparison with Computed Tomography Reassessment.

OBJECTIVES: The objective of this study was to find the diagnostic values of additional ultrasound (US) in patients with equivocal computed tomography (CT) findings of acute appendicitis, compared to CT reassessment. MATERIALS AND METHODS: Patients with equivocal CT findings of acute appendicitis (n = 115), who underwent the US, were included in the study. Two abdominal radiologists reviewed CT scans independently. They analyzed CT findings and made a diagnosis of acute appendicitis. The patients were categorized into positive and negative appendicitis based on the previous US reports. The diagnostic performance, interobserver agreement of CT findings, and appendicitis likelihood were calculated. RESULTS: The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of US (100%, 92.1%, 79.5%, and 100%, respectively) were higher than those of CT reassessment (reviewer 1: 51.9%, 87.5%, 56.1%, and 85.6%; reviewer 2: 66.7%, 85.2%, 58.1%, and 89.3%, respectively). In the coexistent inflammation group, the sensitivity, specificity, PPV, and NPV of US (reviewer 1: 100%, 98%, 91.5%, and 100%; reviewer 2: 100%, 98%, 87.7%, and 100%, respectively) were higher than those of CT reassessment (reviewer 1: 27.3%, 94.1%, 49.9%, and 85.8%; reviewer 2: 14.3%, 98.0%, 50.5%, and 88.9%, respectively). CONCLUSION: In patients with equivocal CT findings of acute appendicitis, US shows better diagnostic performance than CT reassessment, and helps differentiate with periappendicitis.

Structured Reporting versus Free-Text Reporting for Appendiceal Computed Tomography in Adolescents and Young Adults: Preference Survey of 594 Referring Physicians, Surgeons, and Radiologists from 20 Hospitals.

OBJECTIVE: To survey care providers' preference between structured reporting (SR) and free-text reporting (FTR) for appendiceal computed tomography (CT) in adolescents and young adults. MATERIALS AND METHODS: An ethical committee approved this prospective study. The requirement for participant consent was waived. We distributed the Likert scale-based SR form delivering the likelihood of appendicitis across 20 hospitals through a large clinical trial. In the final phase of the trial, we invited 706 potential care providers to participate in an online survey. The survey questions included usefulness in patient management, communicating the likelihood of appendicitis, convenience, style and format, and overall preference. Logistic regression analysis was performed for the overall preference. Three months after the completion of the trial, we checked if the use of the SR was sustained. RESULTS: Responses were analyzed from 594 participants (175 attendings and 419 trainees; 225 radiologists, 207 emergency physicians, and 162 surgeons). For each question, 47.3-64.8% of the participants preferred SR, 13.1-32.7% preferred FTR, and the remaining had no preference. The overall preference varied considerably across the hospitals, but slightly across the departments or job positions. The overall preference for SR over FTR was significantly associated with attendings, SR experience for appendiceal CT, hospitals with small appendectomy volume, and hospitals enrolling more patients in the trial. Five hospitals continued using the SR in usual care after the trial. CONCLUSION: Overall, the care providers preferred SR to FTR. Further investigation into the sustained use of the SR is needed.

CT Scan Findings Can Predict the Safety of Delayed Appendectomy for Acute Appendicitis.

BACKGROUND: The relationship between duration of in-hospital waiting time and outcomes from appendectomy in patients with suspected appendicitis remains equivocal. The aim of this study was to investigate the influence of in-hospital waiting time on perforation rates and clinical outcomes in patients with suspected appendicitis who underwent appendectomy. METHODS: A retrospective review of 5956 patients who underwent appendectomy at a single institution from January 2008 to December 2016 was performed. Patients were separated into two groups based on the duration from hospital arrival to surgery: patients with an in-hospital waiting time ≤ 12 h (no-delay group; n = 5287) and those with an in-hospital waiting time > 12 h (delayed group; n = 669). One-to-one propensity score matching (n = 421 per group) was performed to compare perforation rates and postoperative outcomes between the groups. RESULTS: After propensity score matching, an in-hospital waiting time > 12 h was not associated with increased rates of perforation and significant complications, such as wound infection and abscess. However, in the matched cohorts and in the patients whose initial CT scans suggested perforated appendicitis, the delayed group had a higher risk of developing postoperative ileus (OR 9.18, 95% CI 1.16-72.74, p = 0.021; OR 2.17, 95% CI 1.03-4.59, p = 0.048, respectively) and longer postoperative length of hospital stay (87.38 vs. 79.07 h, p = 0.008; 161.61 vs. 130.87 h, p < 0.001, respectively) than the no-delay group. CONCLUSIONS: Our results indicate that a > 12-h in-hospital waiting time to surgery for appendicitis presents very little risk to the patient. However, the surgeon needs to carefully weigh the "safety" of a delay to surgery for appendicitis in patients whose initial CT scans suggested perforated appendicitis.

Sonographic Findings of Malignant Appendix Tumors in Seven Cases.

We report the sonographic features of confirmed malignant appendiceal tumors in seven cases. The histologic diagnoses of these tumors were mucinous cystadenocarcinoma (n = 2), colonic type adenocarcinoma (n = 4), and signet-ring cell carcinoma (n = 1). The 2 mucinous cystadenocarcinomas showed mucocele type, which had markedly enlarged inner luminal diameters (mean, 23 mm; range, 15-31 mm) and thick, irregular walls (mean wall thickness, 5.5 mm; range, 5-6 mm). In contrast, the 5 nonmucinous carcinomas (4 adenocarcinomas and 1 signet-ring cell carcinoma) showed nonmucocele type, which had relatively small inner luminal diameters (mean ± standard deviation [SD], 6.6 ± 4.5 mm; range, 2-15 mm) and prominent wall thickening (mean wall thickness ± SD, 6.2 ± 2.3 mm; range, 3-10 mm). Of the 5 nonmucinous tumors, only one had a discernible mass, three had thick irregular walls, two had loss of the wall layer pattern, and four had submucosal hypoechogenicity. Regardless of the histologic type, five of the seven malignant appendiceal tumors showed a severe periappendiceal fat infiltration or periappendiceal abscess, suggestive of perforation. Although the sonographic findings of the malignant appendiceal tumors were nonspecific, some of the sonographic features seen in these seven cases may help radiologists consider the possibility of underlying malignant appendiceal tumors.

CT Predictors of Unfavorable Clinical Outcomes of Acute Right Colonic Diverticulitis.

OBJECTIVE: The purpose of this study was to retrospectively assess CT predictors of unfavorable outcomes of medical treatment in patients with right colonic diverticulitis. MATERIALS AND METHODS: Of 394 patients with right colonic diverticulitis diagnosed on the basis of CT findings from January 2010 through August 2013, we included 328 (190 men, 138 women; mean age, 41.3 ± 12.6 years) who had undergone medical treatment as inpatients. Two radiologists retrospectively reviewed the following CT findings associated with diverticulitis: number of diverticula per 10 cm of colon; length and thickness of affected colonic wall; diameter of inflamed diverticulum and abscess; presence of pericolic fluid collection, spilled feces, and contained air; and extent of fatty infiltration. Logistic regression analysis and the Cox proportional hazards regression model were used to determine significant variables predictive of unfavorable outcomes, including surgery after failed medical treatment, recurrence, and prolonged hospital stay. RESULTS: Of the 328 patients, nine underwent surgery after failed medical treatment. Of the other 319 patients, 35 had recurrence and 49 had a prolonged hospital stay. The spilled feces sign (adjusted odds ratio [OR], 111; p < 0.001) and serum WBC count (adjusted OR, 1.3; p = 0.047) were independent predictors of the need for surgery. More than five multiple diverticula per 10 cm of colon was significantly associated with recurrence (adjusted hazard ratio, 4.1; p < 0.001). Abscess larger than 4 cm (adjusted OR, 18.2; p = 0.01) and inflamed diverticulum larger than 2 cm (adjusted OR, 3.7; p = 0.001) were independent predictors of prolonged hospital stay. CONCLUSION: Some specific CT findings can be useful predictors of unfavorable clinical outcomes of right colonic diverticulitis.

Meaningful standard of reference for appendiceal perforation: pathology, surgery, or both?

PURPOSE: This retrospective study was aimed to determine if appendiceal perforation identified pathologically but not surgically is clinically meaningful. METHODS: The study consists of 2 parts. First, we reviewed 74 studies addressing appendiceal perforation published in 2012 and 2013. Second, in a cross-sectional study, we classified 1,438 adolescents and adults (mean age, 29.3 ± 8.4 years; 785 men) with confirmed appendicitis as "nonperforation" (n = 1,083, group 1), "pathologically-identified perforation" (n = 55, group 2), "surgically-identified perforation" (n = 202, group 3), or "pathologically- and surgically-identified perforation" (n = 98, group 4). The 4 groups were compared for the frequency of laparoscopic appendectomy and the length of hospital stay using multivariable logistic regression analyses. RESULTS: The reference standard for appendiceal perforation was frequently missing or inconsistent in the previous studies. Laparoscopic appendectomies were less frequent in groups 3 (52.5%, P = 0.001) and 4 (65%, P = 0.040) than in group 1 (70.7%), while group 2 (73%, P = 0.125) did not significantly differ from group 1. Median hospital stays were 2.9, 3.0, 5.1, and 6.0 days for groups 1-4, respectively. Prolonged hospital stay (≥3.7 days) was more frequent in groups 3 (77.7%, P < 0.001) and 4 (89%, P < 0.001) than in group 1 (23.4%), while group 2 (35%, P = 0.070) did not significantly differ from group 1. CONCLUSION: We recommend using surgical rather than pathologic findings as the reference standard for the presence of appendiceal perforation in future investigations.

Impact of high-grade obstruction on outcomes in patients with appendiceal inflammatory masses managed by nonoperative treatment.

PURPOSE: To retrospectively assess the impact of high-grade obstructions identified on initial CT on outcomes of patients with appendiceal inflammatory masses managed by nonoperative treatment. METHODS: Institutional Review Boards approved this retrospective study and informed consent was waived. Included were 52 consecutive patients diagnosed with appendiceal inflammatory masses by CT scan and managed by nonoperative treatment. The main outcome measure was treatment failure and secondary outcomes were complications and initial and total hospital stay. Patient demographics, inflammatory markers, and CT findings for presence of an appendiceal inflammatory mass and high-grade obstruction were assessed. Patients with and without high-grade obstruction were compared for patient characteristics and outcomes using Fisher exact test and Student t-test. RESULTS: Among 52 patients, 14 (27%) had high-grade obstruction on CT examination at presentation. No significant differences were observed in patient characteristics (P > 0.05), treatment failure (P = 0.33), complications (P = 0.29), or initial (P = 0.73) or total (P = 0.72) hospitalization between patients with and without high-grade obstruction. CONCLUSION: For patients who were managed by nonoperative treatment for appendiceal inflammatory masses, the presence of high-grade obstruction identified on initial CT scan did not significantly affect outcomes of treatment failure, complications, and initial and total hospitalization.

Prolonged operative time in laparoscopic appendectomy: Predictive factors and outcomes.

INTRODUCTION: To our knowledge, this study is the first to identify the predictive factors and outcomes of prolonged operative time associated with laparoscopic appendectomy. We aimed to identify preoperative factors that influence operation time and to determine how operative time affects laparoscopic appendectomy outcomes. METHODS: The medical records of 3049 patients who had undergone laparoscopic appendectomy between January 2008 and December 2014 were retrospectively reviewed. Prolonged operative time was defined in the top 10% according to distribution (>90 min). A multivariate regression model was generated to assess potential predictive factors and outcomes of prolonged operative time. RESULTS: In laparoscopic appendectomy for non-perforated appendicitis, independent factors that predict a prolonged operative time as identified through multivariate analysis were elevated C-reactive protein levels, symptom duration of more than 3 days, and computed tomography findings indicating an appendiceal diameter of more than 10 mm. In laparoscopic appendectomy for perforated appendicitis, overweight, elevated C-reactive protein, symptom duration of more than 3 days, and computed tomography findings of abscess were independent predictive factors for prolonged operative time. Prolonged surgery increases the risk of complications, prolonged hospital stay, and readmission. CONCLUSIONS: Overweight, elevated C-reactive protein, symptom duration of more than 3 days, appendiceal diameter of more than 10 mm, and abscess were independent predictive factors of prolonged operative time. Furthermore, prolonged operative time was associated with adverse postoperative outcomes after laparoscopic appendectomy.

Comparison of filtered back projection and iterative reconstruction in diagnosing appendicitis at 2-mSv CT.

PURPOSE: To compare radiologists' diagnostic performance and confidence, and subjective image quality between filtered back projection (FBP) and iterative reconstruction (IR) at 2-mSv appendiceal CT. METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. We included 107 adolescents and young adults (age, 29.8 ± 8.5 years; 64 females) undergoing 2-mSv CT for suspected appendicitis. Appendicitis was pathologically confirmed in 42 patients. Seven readers with different experience levels independently reviewed the CT images reconstructed using FBP and IR (iDose(4), Philips). They rated both the likelihood of appendicitis and subjective image quality on 5-point Likert scales. Diagnostic confidence was assessed using the likelihood of appendicitis, proportion of indeterminate interpretations, and 3-point normal appendix visualization score. We used receiver operating characteristic analyses, Wilcoxon's signed-rank tests, and McNemar's tests. RESULTS: The pooled area under the receiver operating characteristic curve (AUC) was 0.96 for both FBP and IR (95% CI for the difference, -0.02, 0.02; P = 0.73). The AUC difference was not significant in any of the individual readers (P ≥ 0.21). For the majority of the readers, the diagnostic confidence was not significantly different between the two reconstruction methods. Subjective image quality tended to be higher with IR for all readers (P ≤ 0.70), showing significant differences for four readers (P ≤ 0.040). CONCLUSION: When diagnosing appendicitis at 2-mSv CT in adolescents and young adults, FBP and IR were comparable in radiologists' diagnostic performance and confidence while IR exhibited higher subjective image quality than FBP.

Appendectomy: Should it Be Performed So Quickly?

Controversy surrounds appendectomy timings and their effects on postoperative outcomes. This study evaluated the influence of hospital delays on perforation rates and complications in patients with acute appendicitis. From January 2008 to December 2013, the cases of 4148 consecutive patients who had undergone appendectomies for suspected appendicitis were reviewed. The patients' demographic data, times from symptom onset to hospital arrival (prehospital delay), times from hospital arrival to surgery (hospital delay), histological findings, and postoperative outcomes were documented. Perforation rates and complications were assessed at each time interval between symptom onset and surgery. Perforation rates and complications increased with longer prehospital delays, but no correlations were evident between hospital delays and perforation rates or between hospital delays and complications. Although delaying appendectomies for >18 hours had no statistically significant impact on perforation rates (25.3 vs 19.4%, P = 0.133), it caused more complications (8.7 vs 3.8%, P = 0.023) compared with cases delayed for 12 to 18 hours. Multivariate analyses determined that hospital delays were not associated with increased risks of perforation, complications, wound infections, or intra-abdominal abscesses. However, a >18-hour hospital delay was associated with a significantly increased risk of postoperative ileus (odds ratio = 2.94, 95% confidence interval = 1.17-7.41, P = 0.022). Hospital delays were not associated with significantly increased risks of perforation and complications. However, patients with perforated appendicitis had higher risks of developing postoperative ileus if hospital delays were >18 hours. Therefore, hospital delays of ≤18 hours are safe, but caution is required if delays are >18 hours.

Signet-ring cell carcinoma of the appendix: a case report with an emphasis on sonographic findings.

In this report, we present a rare case of primary signet-ring cell carcinoma of the appendix in a 51-year-old woman with right lower quadrant pain. Since non-specific concentric appendiceal wall thickening was found in a radiologic evaluation, it was misdiagnosed as non-tumorous appendicitis. An in-depth examination of the correlation between sonographic and histopathologic findings demonstrated that a single markedly thickened hypoechoic layer was well correlated with the diffuse infiltration of tumor cells in both the submucosal and muscle layers. If this sonographic finding is observed in certain clinical settings, such as potential ovarian and peritoneal metastasis, submucosal infiltrative tumors, including signet-ring cell carcinoma, should be considered in the differential diagnosis.

Off-site smartphone reading of CT images for patients with inconclusive diagnoses of appendicitis from on-call radiologists.

OBJECTIVE: The purpose of this study was to simulate a mobile consultation in patients with inconclusive diagnosis of appendicitis made by on-call radiologists, as well as to measure the diagnostic confidence and performance of the mobile consultation. MATERIALS AND METHODS: Two off-site abdominal radiologists interpreted the CT images from 68 patients (including 29 patients with confirmed appendicitis) on a smart-phone for whom the preliminary CT reports by 25 in-house on-call radiologists were inconclusive. The smartphone readings were compared with the preliminary reports by on-call radiologists and with the original final reports by in-house abdominal radiologists. Heat maps, kappa statistics, Wilcoxon signed-rank tests, and ROC curves were used for data analysis. RESULTS: The heat maps and kappa statistics showed that the smartphone readings were more similar to the final reports than to the preliminary reports. In diagnosing or ruling out appendicitis, the smartphone readings were more confident than the preliminary reports (p ≤ 0.01) and did not significantly differ in diagnostic confidence from the final reports (p ≥ 0.19). The AUCs of the smartphone readings (0.91 and 0.92) did not differ significantly from those of the preliminary (0.85) or final (0.97) reports (p ≥ 0.09). CONCLUSION: With the given study sample, the diagnostic performance of the off-site smartphone readings did not differ significantly from that of the in-house preliminary reports. However, the smartphone readings provided higher diagnostic confidence than the preliminary reports.

Added value of ultrasound re-evaluation for patients with equivocal CT findings of acute appendicitis: a preliminary study.

PURPOSE: To prospectively estimate the additional diagnostic value of ultrasound (US) re-evaluation for patients with equivocal computed tomography (CT) findings of acute appendicitis. METHODS: Between April 2011 and October 2011, 869 consecutive patients with suspected appendicitis who were referred for CT were included. The likelihood of appendicitis was prospectively categorized into five categories. US re-evaluation was recommended for patients in the 'equivocal appendix' and 'probably not appendicitis' groups. The overall negative appendectomy rate during the study period was compared with the rate of the previous year, and negative appendectomy rates of the US and non-US evaluation groups were also compared. RESULTS: Among 869 patients, 71 (8.2 %) had equivocal appendicitis findings and 63 (7.2 %) were diagnosed as probably not appendicitis. The sensitivity and specificity of CT combined with US re-evaluation group (100 % and 98.1 %, respectively) exceeded those of the CT alone group (93 % and 99 %; equivocal group considered as negative appendicitis, 100 % and 89.9 %; as positive, respectively, P < 0.0001). After adding US re-evaluation, the overall negative appendectomy rate in our institution decreased from 3.4 to 2.3 %. CONCLUSION: For patients with equivocal CT findings of acute appendicitis, US re-evaluation can improve diagnostic accuracy and decrease the rate of negative appendectomies. KEY POINTS: • Misdiagnosis of appendicitis still occurs, especially in patients with equivocal radiological findings. • The sensitivity and specificity of CT followed by US exceeded those of CT alone. • After US re-evaluation, the negative appendectomy rate decreased from 3.4 to 2.3 %. • US re-evaluation in equivocal cases helps diagnostic confidence and further management.

Color Doppler twinkling artifacts from gallstones: in vitro analysis regarding their compositions and architectures.

The purpose of our study was to investigate the relationship between a twinkling artifact and the biochemical compositions of gallstones in phantom experiments. Fifty-two gallstones surgically extracted from 26 patients (26 cholesterol, 12 brown pigment and 14 black pigment stones) were included in the phantom study. Color Doppler sonography was performed to evaluate the occurrence of a twinkling artifact behind the stones. The artifacts were graded from grade 0 (no artifact) to grade 3 (very strong artifact). Micro computed tomography (CT) images were obtained to analyze the internal architecture and external surface of the stones. A total of 20 of 26 cholesterol stones (77%) produced grade 2 or 3 artifacts, whereas almost all the black pigment stones and more than half of the brown pigment stones produced no artifacts or grade 1 artifacts (p = 0.0010). The sensitivity and specificity of grade 2 or greater artifacts for cholesterol stones were 76.9% and 76.9%, respectively. The composition of the stones was strongly correlated with the internal shape on the micro CT image. Cholesterol stones with rough surfaces did not show stronger intensities of the artifacts than those with smooth surfaces (p > 0.05). In conclusion, most of the prominent artifacts arose from cholesterol stones having radial or radial-concentric internal architectures, whereas the black pigment stones mostly produced little artifact.