Hyperechoic Periappendiceal Fat: Evaluation of Criteria for Improving Specificity in the Sonographic Diagnosis of Appendicitis in Pediatric Patients.

OBJECTIVES: To test the hypothesis that abutting and encasing types of hyperechoic periappendiceal fat are specific sonographic indicators of appendicitis in pediatric patients, including individuals with maximum outer diameters (MODs) of 6 to 8 mm in whom diagnosis by the MOD alone is known to be equivocal. METHODS: Appendiceal sonograms of 271 consecutive pediatric patients were retrospectively evaluated for hyperechoic periappendiceal fat (globular, ≥1.0 cm; categorized as type 0, none; type 1, "abutting," encompassing <180° of the appendiceal circumference; or type 2, "encasing," encompassing 180° or more of the appendiceal circumference) and the MOD. Histopathologic and medical records constituted reference standards. Statistical methods included the binomial distribution, logistic regression, a receiver operating characteristic analysis, and the exact McNemar test. RESULTS: All patients with hyperechoic fat and 105 of 107 patients with appendicitis had MODs of 6 mm or greater. The MOD and fat types 1 and 2 each were significantly associated with appendicitis in the univariable regression. The MOD and fat type 1 were independently associated with appendicitis in multivariable regression (odds ratio, 24.97; P = .034; and odds ratio, 5.35; P < .001, respectively). Specificities of an MOD of 6 to 8 mm and an MOD of 6 mm or greater alone were 89.0% (95% confidence interval, 83.2%-93.4%); these increased to 100.0% each (95% confidence interval, 97.8%-100.0%; P < .001) when combined with fat types 1, 2, and either 1 or 2 as diagnostic criteria, with positive predictive values of 100.0%. CONCLUSIONS: Types 1 and 2 periappendiceal fat are specific indicators of appendicitis, and both improve specificity compared to the MOD. Importantly, they add specificity in diagnosing appendicitis in patients with diagnostically equivocal MODs of 6 to 8 mm.

Luminal obstruction in uncomplicated appendicitis: Detection with sonography and potential clinical implications.

PURPOSE: To determine the frequency of luminal obstruction on appendiceal graded compression sonography (US) in patients with uncomplicated appendicitis and test the hypothesis that this frequency is similar to the failure rates of primary antibiotic therapy for uncomplicated appendicitis when treatment selection is based on CT findings. METHODS: Sonograms of 150 consecutive patients with appendicitis diagnosed on ultrasound (US) and proven histopathologically were retrospectively evaluated; 114 (76.0%) had uncomplicated appendicitis, that is, appendicitis without gangrene or perforation, and were evaluated for appendicolithiasis and lymphoid hyperplasia using previously published sonographic criteria, and for luminal obstruction. RESULTS: Of the 114 patients with uncomplicated appendicitis, US demonstrated no luminal obstruction in 74 (64.9%) and luminal obstruction in 40 (35.1%, P = .018), the latter including 16 (40.0%) with lymphoid hyperplasia and 24 (60.0%, P = .074) with appendicolithiasis. CONCLUSIONS: US demonstrated luminal obstruction in 35.1% of patients with uncomplicated appendicitis, similar to the published failure rates of antibiotic therapy when treatment selection is based on CT. This confirms the hypothesis, supporting the possibility that undiagnosed luminal obstruction may account for treatment failures when patients are selected by CT for primary antibiotic therapy, and suggests a role for US in selecting patients without luminal obstruction for antibiotic therapy.

Spectral Doppler Waveforms for Diagnosis of Appendicitis: Potential Utility of Point Peak Systolic Velocity and Resistive Index Values.

Purpose To test the hypothesis that appendiceal spectral Doppler waveforms can distinguish patients with and patients without appendicitis. Materials and Methods In this retrospective study, Doppler waveforms were obtained from intramural appendiceal arteries identified with color Doppler imaging in 60% (93 of 155) of consecutive patients whose appendices were visualized at graded compression ultrasonography (US) performed for suspected appendicitis (53 male and 40 female; age, 1-56 years; mean, 14.5 years) over the 5-month period from November 2015 through March 2016. Point, non-angle-corrected peak systolic velocity (PSV) and resistive index (RI) values were compared between patients with and patients without appendicitis by utilizing histopathologically proven appendicitis and 6-week clinical follow-up as diagnostic reference standards. Data were assessed by using the Student t test, exact binomial distribution, two-sample test of proportions, and receiver operating characteristic analysis. Results Among the 93 patients, 36 (38.7%) had proven appendicitis (mean PSV, 19.7 cm/sec; mean RI, 0.69) and 57 patients (61.2%) did not (mean PSV, 7.1 cm/sec, P < .0001; mean RI, 0.50, P < .0001). The area under the receiver operating characteristic curve for the diagnosis of appendicitis was 0.97 (95% confidence interval [CI]: 0.95, 1.00) for PSV and 0.86 (95% CI: 0.78, 0.95; P = .011) for RI. Chosen discriminatory criteria of PSV greater than 10 cm/sec and RI greater than 0.65 yielded specificity for appendicitis of 94.7% and 96.5% with sensitivity of 88.9% and 63.9% (P = .013) and negative predictive value of 93.1% and 80.9% (P = .045), respectively. Original clinical graded compression US interpretations based on established US findings demonstrated specificity of 96.2% and sensitivity of 100.0%. Considering the subset of 20 patients whose maximum outer diameter measured 6-8 mm, the discriminatory criteria of PSV greater than 10 cm/sec and RI greater than 0.65 yielded specificity for appendicitis of 88.9% each, with sensitivity of 100.0% and 63.6% and negative predictive value of 100.0% and 66.6%, respectively. Conclusion In patients with visualized appendices at US, those with appendicitis exhibit significantly higher point PSV and point RI values than do patients without appendicitis and are distinguishable with high specificity by using a PSV greater than 10 cm/sec and an RI greater than 0.65 as diagnostic criteria. © RSNA, 2017.

Anatomic Reasons for Failure to Visualize the Appendix With Graded Compression Sonography: Insights From Contemporaneous CT.

OBJECTIVE: The purpose of this study is to identify the anatomic locations of appendixes on CT when graded compression sonography fails to visualize the appendix. MATERIALS AND METHODS: The study included 197 patients with suspected appendicitis whose appendixes were not visualized on graded compression sonography performed with typically used transducers of at least 10 MHz, who underwent CT within 48 hours following graded compression sonography, and who had available either pathologic examination following surgery or 6-week follow-up if surgery was not performed. Appendixes were retrospectively localized using four transverse quadrants (including the posteromedial quadrant) centered on the ileocecal valve and projected vertically, the craniocaudal level relative to the iliac crests, and the depth of the appendix as measured from the surface of the skin. Data were assessed using the Fisher exact test, t test, multinomial test, binomial distribution, ANOVA, and linear regression. RESULTS: Appendixes were most frequently located in the posteromedial quadrant (123 of 197 patients [62.4%]; 95% CI, 55.3-69.2%) at a statistically significantly greater frequency than that expected by chance (p < 0.00001). Appendixes were located above the iliac crests in 19.8% of patients (39/197; 95% CI, 14.5-26.1%) and at depths exceeding the penetration of typical transducers of at least 10 MHz in 19.3% of patients (38/197; 95% CI, 14.0-25.5%). All appendixes (95% CI, 98.1-100.0%) were located within the range of 6-MHz transducers. CONCLUSION: Appendixes that are not visualized on graded compression sonography are most frequently located in the posteromedial quadrant and are often located above the iliac crests or at depths too great for visualization with typically used transducers of at least 10 MHz. Accordingly, when the appendix is not visualized on graded compression sonography, targeted scanning of the posteromedial quadrant and the region above the iliac crests, and scanning with 6-MHz transducers, may enable visualization of the appendix and are recommended additions to scanning protocols.

Sonographic Differentiation of Complicated From Uncomplicated Appendicitis: Implications for Antibiotics-First Therapy.

OBJECTIVES: To evaluate sonographic findings as indicators of complicated versus uncomplicated appendicitis in the setting of known appendicitis, a necessary distinction in deciding whether to proceed with antibiotic therapy or with appendectomy. METHODS: With Institutional Review Board approval and Health Insurance Portability and Accountability Act compliance, appendiceal sonograms of 119 patients with histopathologically proven appendicitis were retrospectively blindly reviewed to determine the presence or absence of the normally echogenic submucosal layer, the presence of mural hyperemia, periappendiceal fluid, appendicoliths, and hyperechoic periappendiceal fat and to determine the maximum outside diameter. Results were compared with the presence of complicated versus uncomplicated appendicitis on histopathologic examination and assessed by both univariate and mulitvariate logistic regression; confidence intervals (CIs) of proportions were assessed by the exact binomial test. RESULTS: Thirty-two (26.9%) of the 119 patients had complicated appendicitis, including 11 with gangrenous appendicitis without perforation and 21 with gangrenous appendicitis and perforation. Loss of the submucosal layer was the only independent significant indicator of complicated appendicitis in multivariate regression (P < .001) and provided sensitivity and specificity values of 100.0% (95% CI, 89.1%-100.0%) and 92.0% (95% CI, 84.1%-96.7%), respectively. CONCLUSIONS: Loss of the normally echogenic submucosal layer was the most useful sonographic finding for discriminating complicated from uncomplicated appendicitis, being the only finding independently and significantly associated with complicated appendicitis and, additionally, providing both high sensitivity and high specificity. This information may help a physician decide whether to proceed with antibiotic therapy or with appendectomy when treating a patient with appendicitis.

Preoperative Multidetector CT Diagnosis of Extrapancreatic Perineural or Duodenal Invasion Is Associated with Reduced Postoperative Survival after Pancreaticoduodenectomy for Pancreatic Adenocarcinoma: Preliminary Experience and Implications for Patient Care.

Purpose To test the hypothesis that patients with pancreatic adenocarcinoma who otherwise are viewed to have resectable disease but have preoperative findings of extrapancreatic perineural invasion (EPNI) and/or duodenal invasion at multidetector computed tomography (CT) have reduced postoperative survival after pancreaticoduodenectomy for pancreatic ductal adenocarcinoma (PDAC). Materials and Methods This study was approved by the institutional review board and complied with HIPAA. The authors retrospectively evaluated 76 consecutive patients with PDAC who underwent preoperative multidetector CT and subsequent pancreaticoduodenectomy. Two radiologists blinded to surgical pathology results and clinical outcome evaluated multidetector CT images for evidence of EPNI and duodenal invasion; discrepancies were resolved by consensus. Also determined for each patient were resected lymph node status, tumor size, surgical margin status, time to progression, and time to death. Data were assessed with the Goodman-Kruskal gamma for correlations among indicators and the log-rank test, Kaplan-Meier estimates, and multivariate Cox proportional hazards regression for survival analysis. Results In univariate analysis, duodenal invasion and/or EPNI on preoperativemultidetector CT images was associated with significantly decreased progression-free survival (P < .0001) and overall survival (P = .0013), and the clinical indicators (lymph node status, tumor size, and surgical margin status) as well as duodenal invasion and/or EPNI showed correlation with each other. In multivariate regression that included multidetector CT findings as well as the three traditional clinical indicators, only duodenal invasion and/or EPNI showed significant independent association with reduction in both modes of survival (P < .0001 and P = .014, respectively). Interobserver agreement was substantial with respect to EPNI and duodenal invasion (κ = 0.691 and 0.682, respectively). Conclusion Patients with evidence of EPNI and/or duodenal invasion on preoperative multidetector CT images have significantly reduced survival after pancreaticoduodenectomy for PDAC. © RSNA, 2016.

Lymphoid Hyperplasia of the Appendix: A Potential Pitfall in the Sonographic Diagnosis of Appendicitis.

OBJECTIVE: The objective of this study was to test the hypothesis that thickening of the lamina propria, a finding produced by lymphoid hyperplasia, is significantly associated with false-positive sonographic diagnoses of appendicitis in 6- to 8-mm noncompressible appendixes. MATERIALS AND METHODS: Sonograms of 119 consecutive patients with suspected appendicitis and 6- to 8-mm noncompressible appendixes were retrospectively blindly evaluated for thickening of the lamina propria (short axis thickness ≥ 1 mm). The reference standard for appendicitis was pathologic analysis of resected specimens. Results were compared with the two-tailed Fisher exact test. RESULTS: Thirty-one patients (26.1%) had a thickened lamina propria and 88 (73.9%) did not. Of the 27 pediatric patients with a thickened lamina propria, five (18.5%) had true-positive and 22 (81.5%) had false-positive sonograms for appendicitis; among the 55 pediatric patients without a thickened lamina propria, 27 (49.1%) had true-positive and 28 (50.9%) had false-positive sonograms for appendicitis (p = 0.009). Similar differences in adult patients were not statistically significant. All five pediatric patients with appendicitis and thickened lamina propria also showed two or more findings of periappendiceal fluid, hyperechoic periappendiceal fat, or mural hyperemia on color Doppler examination, compared with two of 22 similar pediatric patients without appendicitis (p < 0.001). CONCLUSION: Lymphoid hyperplasia may result in a noncompressible appendix 6-8 mm in diameter and may be misdiagnosed as appendicitis in pediatric patients. True-positive diagnoses of appendicitis can be accurately identified by the presence of at least two additional findings from the group of periappendiceal fluid, hyperechoic periappendiceal fat, and mural hyperemia. Identifying the characteristic sonographic appearance of lymphoid hyperplasia may help prevent false-positive misdiagnoses of appendicitis.

Color Doppler Imaging of the Appendix: Criteria to Improve Specificity for Appendicitis in the Borderline-Size Appendix.

OBJECTIVES: To test the hypothesis that continuous intramural vascular signal measuring at least 3 mm on color Doppler imaging is highly specific for appendicitis in patients with diagnostically borderline-size appendices. METHODS: Two blinded observers independently reviewed color Doppler images of the appendix in 94 consecutive patients who had undergone sonography for suspected appendicitis and whose appendices were of diagnostically borderline size (6-8 mm maximum outer diameter). Intramural vascular flow on color Doppler images was classified as absent, type 1 (only punctate and dispersed signal), or type 2 (continuous linear or curvilinear signal measuring at least 3.0 mm in long- or short-axis views). Histopathologic examination and clinical follow-up served as reference standards. Proportions were assessed by the exact binomial test. RESULTS: Of the 94 patients, 33 (35.1%) had type 1 flow (of whom 5 [15.2%] had appendicitis); 23 (24.5%) had type 2 flow (of whom 20 [87.0%] had appendicitis); and 38 (40.4%) had absent flow (of whom 10 [26.3%] had appendicitis). The sensitivity, specificity, and odds ratio of type 2 flow as an indicator of appendicitis were 57.1%, 94.9%, and 24.9 (P< .001), respectively; the corresponding values for type 1 flow as an indicator of normal appendices were and 47.5%, 85.7%, and 5.4 (P = .002). CONCLUSIONS: Continuous intramural linear or curvilinear signal measuring at least 3 mm on color Doppler imaging is a highly specific, although relatively insensitive, sign of acute appendicitis in noncompressible appendices of diagnostically borderline size (6-8 mm).

MDCT Diagnosis of Perineural Invasion Involving the Celiac Plexus in Intrahepatic Cholangiocarcinoma: Preliminary Observations and Clinical Implications.

OBJECTIVE: The purpose of this study was to test the hypothesis that soft-tissue infiltration along the celiac plexus and delayed enhancement exceeding two-thirds of the tumor area on preoperative MDCT correlate with histologic evidence of perineural invasion in resected intrahepatic cholangiocarcinomas. MATERIALS AND METHODS: Two experienced abdominal radiologists retrospectively reviewed preoperative multiphasic MDCT scans of 20 patients who underwent resection of intrahepatic cholangiocarcinoma, identifying soft-tissue infiltration along the celiac plexus, delayed enhancement exceeding two-thirds of the tumor area, and maximum tumor diameter. Consensus findings were compared with intratumoral perineural invasion in resected intrahepatic cholangiocarcinomas using the Fisher exact test. RESULTS: Six patients had histologic intratumoral perineural invasion, five of whom had soft-tissue infiltration along the celiac plexus on preoperative MDCT, with corresponding 83.3% sensitivity and 92.9% specificity for perineural invasion and significant association between these MDCT and histologic findings (p = 0.002). No patients with histologic perineural invasion had enhancement exceeding two-thirds of the tumor area on MDCT; sensitivity was 0.0% for this finding. Tumor diameter on MDCT was not significantly associated with perineural invasion at histopathology (p = 0.530). CONCLUSION: Soft-tissue infiltration along the celiac plexus on MDCT is an indicator of perineural invasion in patients with intrahepatic cholangiocarcinoma. The data did not confirm an association between delayed enhancement exceeding two-thirds of the tumor area and perineural invasion. Because perineural invasion from intrahepatic cholangiocarcinoma is associated with a very poor prognosis and is generally a contraindication to surgery, the MDCT diagnosis of celiac plexus perineural invasion in patients with intrahepatic cholangiocarcinoma may have important implications for prognosis and treatment planning.

Journal Club: the Alvarado score as a method for reducing the number of CT studies when appendiceal ultrasound fails to visualize the appendix in adults.

OBJECTIVE. The purpose of this article is to evaluate the hypothesis that Alvarado scores of 3 or lower identify adult patients who are unlikely to benefit from CT after appendiceal ultrasound fails to show the appendix and is otherwise normal. MATERIALS AND METHODS. We identified 119 consecutive adults for whom the appendix was not seen on otherwise normal appendiceal sonography performed as the first imaging study for suspected appendicitis, who subsequently underwent CT within 48 hours, and whose data permitted retrospective calculation of admission Alvarado scores. Specific benefits of CT were defined as diagnoses of appendicitis or significant alternative findings, and specific benefits were compared between patients with Alvarado scores of 3 or less and 4 or higher. Significant alternative findings on CT were findings other than appendicitis that were treated with medical or surgical therapy during the admission or that were to be addressed during follow-up care. Diagnostic reference standards were discharge diagnoses, pathologic examinations, and clinical follow-up. RESULTS. No patients (0.0%, 0/49) with Alvarado scores 3 or lower had appendicitis, compared with 17.1% (12/70) of patients with Alvarado scores 4 or higher (p = 0.001), and CT showed neither appendicitis nor significant alternative findings in 85.7% (42/49) versus 58.6% (41/70) of these patients, respectively (p = 0.002). The rates of perforated appendicitis, as well as significant alternative CT findings, did not differ significantly. CONCLUSION. Adults with Alvarado scores 3 or lower who have nonvisualized appendixes and otherwise normal appendiceal sonography are at very low risk for appendicitis or significant alternative findings and therefore are not likely to benefit from CT.

Predictors of appendicitis on computed tomography among cases with borderline appendix size.

Confident diagnosis of appendicitis when the appendix is borderline (6 to 7 mm) in size can be challenging. This retrospective study assessed computed tomography (CT) findings that are most predictive of appendicitis when the appendix is borderline in diameter. Three radiologists conducted separate, blind retrospective reviews of 105 contrast-enhanced CTs with borderline appendices. Presence or absence of appendicitis was confirmed by chart review of clinical or surgical outcomes. Logistic regression was used to determine the odds ratio (OR) and the receiver operating characteristic for CT features predictive of appendicitis. Absence of intraluminal air (OR = 5.11, p < 0.001), wall hyperemia (OR = 3.92, p = 0.002), wall thickening (OR = 29.7, p < 0.001), and fat stranding (OR = 3.85, p = 0.003) were significant findings in univariate logistic regression. Using a multivariate model, we found that the absence of intraluminal air (OR = 6.04, p = 0.002) and wall thickening (OR = 24.6, p < 0.001) remained statistically significant and were unaffected by adjustment for gender and pediatric age. The area under the curve was significantly greater for the multivariate model than the initial, clinical CT impressions (p = 0.024). The combination of wall thickening and absence of intraluminal air was 92.6 % (95 % CI 75.7-99.1) sensitive and 82.4 % (95 % CI 65.5-93.2) specific for appendicitis. Wall thickening and the absence of intraluminal air are prominent predictors of appendicitis and, if present together, these features may aid in identifying appendicitis on CT when the appendix is borderline in size.

Three-step sequential positioning algorithm during sonographic evaluation for appendicitis increases appendiceal visualization rate and reduces CT use.

OBJECTIVE: The purpose of this article is to examine the rates of appendiceal visualization by sonography, imaging-based diagnoses of appendicitis, and CT use after appendiceal sonography, before and after the introduction of a sonographic algorithm involving sequential changes in patient positioning. MATERIALS AND METHODS: We used a search engine to retrospectively identify patients who underwent graded-compression sonography for suspected appendicitis during 6-month periods before (period 1; 419 patients) and after (period 2; 486 patients) implementation of a new three-step positional sonographic algorithm. The new algorithm included initial conventional supine scanning and, as long as the appendix remained nonvisualized, left posterior oblique scanning and then "second-look" supine scanning. Abdominal CT within 7 days after sonography was recorded. RESULTS: Between periods 1 and 2, appendiceal visualization on sonography increased from 31.0% to 52.5% (p < 0.001), postsonography CT use decreased from 31.3% to 17.7% (p < 0.001), and the proportion of imaging-based diagnoses of appendicitis made by sonography increased from 63.8% to 85.7% (p = 0.002). The incidence of appendicitis diagnosed by imaging (either sonography or CT) remained similar at 16.5% and 17.3%, respectively (p = 0.790). Sensitivity and overall accuracy were 57.8% (95% CI, 44.8-70.1%) and 93.0% (95% CI, 90.1-95.3%), respectively, in period 1 and 76.5% (95% CI, 65.8-85.2%) and 95.4% (95% CI, 93.1-97.1%), respectively, in period 2. Similar findings were observed for adults and children. CONCLUSION: Implementation of an ultrasound algorithm with sequential positioning significantly improved the appendiceal visualization rate and the proportion of imaging-based diagnoses of appendicitis made by ultrasound, enabling a concomitant decrease in abdominal CT use in both children and adults.

The sonographic "bright band sign" of splenic infarction.

OBJECTIVES: To evaluate the frequency of the "bright band sign" in patients with splenic infarcts as well as control patients and to thereby assess whether the bright band sign has potential utility as a sonographic sign of splenic infarction. METHODS: Using an electronic search engine and image review, 37 patients were retrospectively identified with noncystic parenchymal splenic infarcts on sonography. Nineteen abnormal control patients with noninfarcted splenic lesions on sonography and 100 normal control patients with sonographically normal spleens were also identified. The sonographic appearance of each splenic lesion was evaluated by 2 reviewers and assessed for the bright band sign, defined as thin specular reflectors perpendicular to the sound beam within hypoechoic parenchymal lesions, and for the presence or absence of the classic sonographic appearance of splenic infarction. Possible histologic counterparts of the bright band sign were assessed in archival infarct specimens. RESULTS: The bright band sign was present in 34 (91.9%; 95% confidence interval [CI], 78.1%-98.3%) of 37 patients with splenic infarcts on sonography, including 12 (85.7%; 95% CI, 57.2%-98.2%) of 14 with classic and 22 (95.7%; 95% CI, 78.1%-99.9%) of 23 with nonclassic infarct appearances. No normal or abnormal control patients had the bright band sign. Histologic sections suggested that preserved splenic trabeculae within infarcts may generate the bright band sign. CONCLUSIONS: The bright band sign is a potentially useful sonographic sign of splenic infarction, which may confer additional sensitivity and specificity and may be particularly helpful with infarcts having nonclassic appearances.

Value of short-interval computed tomography when sonography fails to visualize the appendix and shows otherwise normal findings.

OBJECTIVES: The purpose of this study was to evaluate the type and incidence of disorders revealed by short-interval computed tomography (CT) in patients with suspected appendicitis after graded compression sonography fails to reveal the appendix and shows otherwise normal findings. METHODS: Computed tomographic findings and clinical courses were assessed retrospectively for 318 patients identified consecutively in a searchable database who met inclusion criteria specifying that sonography was the initial imaging examination for suspected appendicitis; sonography revealed nonvisualization of the appendix and otherwise normal results; and abdominopelvic CT was performed within 48 hours after sonography. RESULTS: Of the 318 patients, short-interval CT revealed normal findings in 250 (78.6%). Appendicitis was revealed in 52 (16.4%) others, of whom 7 had perforation and all of whom had pathologic results confirming these CT findings. Important alternative diagnoses other than appendicitis were revealed in 16 (5.0%) others, including 2 (0.6%) who required urgent surgery and 14 (4.4%) who did not. No significant differences were observed between adult patients (>18 years) and pediatric patients. CONCLUSIONS: Most short-interval CT scans in this clinical setting reveal normal findings, and relatively few disclose appendicitis or disorders that require urgent surgery. In view of concerns regarding radiation exposure associated with CT, these observations argue for the development of clinical triage methods that differentiate patients who are likely to benefit from short-interval postsonography CT from those who are not.

Sonography for appendicitis: nonvisualization of the appendix is an indication for active clinical observation rather than direct referral for computed tomography.

PURPOSE: To determine the prevalence of perforated and nonperforated appendicitis in patients with nonvisualization of the appendix on ultrasound (US) performed for suspected appendicitis, and to evaluate the value of CT in these patients. METHODS: We analyzed 400 consecutive patients undergoing US for suspected appendicitis. Of these patients, 260 had nonvisualization of the appendix, but otherwise normal scans. We analyzed the clinical outcome in these patients to determine the prevalence of appendicitis, referrals for CT, and the contribution of CT in these patients. RESULTS: Of the 400 patients, 140 (35%) had either a normal (80 patients, 25%) or an abnormal appendix (60 patients, 15%); 260 (65%) had nonvisualization of the appendix. Overall 75 patients had appendicitis (18.8%) and 17 (4.3%) had appendicitis with perforation. Of the 260 patients with nonvisualization of the appendix, 14 patients (5.4%) had appendicitis and 2 were perforated (0.8%). The prevalence of perforated and nonperforated appendicitis in this group was significantly lower than the overall group (p < 0.001 and p < 0.01, respectively). Of these 260 patients, 101 patients (38.8%) had CT within 48 hours and 79 (78.2%) had normal scans. CONCLUSIONS: Patients with nonvisualization of the appendix on US, but otherwise normal scans, are at significantly lower risk for appendicitis, either perforated or nonperforated. Active clinical observation should be considered in these patients, rather than direct referral for CT.

The Borderline-Size Appendix: Grayscale, Color Doppler, and Spectral Doppler Findings That Improve Specificity for the Sonographic Diagnosis of Acute Appendicitis.

Diagnostic criteria for acute appendicitis using graded compression sonography have been well established based on the maximum outer diameter (MOD) of the appendix, with MOD values of <6 mm nearly always indicating normal appendices and MOD values of >8 mm nearly always indicating appendicitis. However, the "borderline-size" appendix, meaning one whose MOD lies between these ranges (ie, an appendix with MOD of 6-8 mm), presents a diagnostic dilemma because appendices in this size range are neither clearly normal nor abnormal when diagnosis is based on the MOD alone; accordingly, such borderline MOD values are diagnostically equivocal, and sonographic diagnosis must rely on sonographic findings other than the MOD. The goal of this review was to examine the additional sonographic findings that can add specificity and help enable an accurate diagnosis to be made in patients with borderline-size appendices.

Ileocolic vascular curvature: a new CT finding of cecal volvulus.

PURPOSE: To evaluate the diagnostic performance of a proposed new CT observation in cecal volvulus, marked hook-like curvature of ileocolic vessels termed "ileocolic vascular curvature." METHODS: Contrast-enhanced CT scans of 14 patients with diagnoses of cecal volvulus on original CT reports were compared with scans of 40 control patients with dilated cecum but no cecal volvulus on original CT reports, accrued consecutively from January, 2006 through July, 2017. Two independent blinded readers retrospectively evaluated scans for cecal dilatation, ileocolic vascular curvature and seven previously reported CT features of cecal volvulus. Statistical methods included the exact binomial distribution to define 95% confidence intervals (95% CIs), logistic regression, receiver operating characteristic analysis, and the exact McNemar test. Pathology reports and clinical records served as reference standards. RESULTS: All patients had abdominal pain and cecal distension. All 14 patients with CT diagnoses of cecal volvulus, and no control patients, had cecal volvulus by reference standards. Ileocolic vascular curvature and ectopic cecal location were the only features independently and significantly associated with cecal volvulus in multivariable regression (odds ratio 178, p = 0.014, and 63, p = 0.013, respectively) and also the only features with both sensitivity (12/14 [85.7%, 95% CI 57.2-98.2%] and 13/14 [92.9%, 95% CI 66.1-99.8%], respectively) and specificity (40/40 [100.0%, 95% CI 91.2-100.0%] and 38/40 [95.0%, 95% CI 83.1-99.4%], respectively) that differed significantly from 50.0%. CONCLUSIONS: Ileocolic vascular curvature was independently and significantly associated with cecal volvulus and exhibited both substantial sensitivity and substantial specificity for cecal volvulus, and thus is potentially a valuable new CT finding of cecal volvulus.

Groove pancreatitis: a clinical and imaging overview.

Groove or paraduodenal pancreatitis is an uncommon fibroinflammatory form of pancreatitis involving the anatomic space of the pancreatic groove located between the C-loop of the duodenum and the head of the pancreas. Although in some patients there are distinctive clinical and imaging features of groove pancreatitis (GP), there is often significant overlap with other infiltrative processes involving the pancreatic groove such as pancreatic ductal adenocarcinoma or duodenal carcinoma. In this review, we summarize the most distinctive clinical and imaging aspects of GP and highlight some important distinguishing features that may aid in differentiating malignant lesions involving the pancreatic groove.