Emergent and unusual presentations of endometriosis: pearls and pitfalls.

The purpose of this pictorial essay is to highlight atypical and unusual presentations of endometriosis that can be missed or misinterpreted in the emergency setting. Although endometriosis is a chronic disease, it can present acutely with symptoms and imaging mimicking more common acute gynecologic, gastrointestinal, or urinary conditions as well as neoplasms. Furthermore, patients may present emergently prior to an established diagnosis of endometriosis. Here, we present a range of cases including endometrioma rupture and infection, urinary tract involvement and obstruction, bowel obstruction, appendicitis, gastrointestinal infiltration, abdominal masses, and thoracic involvement. Pelvic ultrasound and MRI are the most valuable imaging modalities in the assessment of endometriosis. CT findings are non-specific, but given the widespread use of CT in emergency settings, it is important to recognize CT findings suggestive of the diagnosis in the right clinical setting.

Multimodality Imaging after Liver Transplant: Top 10 Important Complications.

Patients who have undergone liver transplant are now regularly seen in day-to-day radiology practice. All surgical techniques for liver transplant require arterial, portal venous, hepatic venous and caval, and biliary anastomoses. This review is focused on the 10 "not to be missed" complications of liver transplant that affect the health and life of the graft and graft recipient. Arterial complications are the most common and devastating. Early hepatic artery thrombosis may be catastrophic because the biliary tree is solely dependent on the hepatic artery after transplant and collateral vessels have not yet formed. In contrast, delayed hepatic artery thrombosis may be more insidious as collateral arteries develop. US findings of delayed hepatic artery thrombosis may be similar to those of hepatic artery stenosis and celiac artery stenosis. Splenic artery steal syndrome is an increasingly recognized cause of graft ischemia. Venous complications are much less common. Hepatic venous and caval complications are notable for their increased incidence in living-donor and pediatric transplants. Biliary complications often result from arterial ischemia. Biliary cast syndrome is a notable example in which ischemic biliary mucosa sloughs into and obstructs the duct lumens. Neoplasms also may occur within the hepatic graft and may be due to recurrent malignancy, posttransplant lymphoproliferative disorder, or metastases. US is the initial imaging modality of choice, particularly in the acute postoperative setting. Further evaluation with contrast-enhanced US, CT, or MRI; catheter angiography; endoscopic retrograde cholangiopancreatography; and/or nuclear medicine studies is performed as needed. An invited commentary by Bhargava is available online. Online supplemental material is available for this article. ©RSNA, 2022.

Evaluation of ACR TI-RADS cytologically indeterminate thyroid nodules and molecular profiles: a single-institutional experience.

INTRODUCTION: The American College of Radiology (ACR) Thyroid Imaging Reporting and Data Systems (TI-RADS) was developed to standardize thyroid ultrasound reports and predict the likelihood of malignancy. In our study, we aimed to correlate indeterminate thyroid fine needle aspiration cytology cases with preceding ultrasound (US) ACR TI-RADS scores and concurrent molecular testing results to examine how well the use of the ACR TI-RADS in our institution predicted which patients with indeterminate cytology might harbor molecular alterations. MATERIALS AND METHODS: We performed a retrospective review of thyroid nodules. Patients with US reports that included TI-RADS scores, fine needle aspiration specimens with indeterminate cytology (Bethesda class III-V), and molecular testing results were included. RESULTS: A total of 46 indeterminate cytology cases had had preceding US reports with TI-RADS scores and molecular testing (Bethesda class III, n = 37; Bethesda class IV, n = 6; Bethesda class V, n = 3). Most of the indeterminate cases had had a TI-RADS score of TR4 (31 of 46; 67.39%) or TR5 (9 of 46; 19.57%). RAS mutations were the most common alteration (n = 12). Of the 46 cases, 22 (47.85%) showed no alterations. Ten cases proceeded to surgery, of which seven displayed malignancies. CONCLUSIONS: Molecular testing in cytologically indeterminate thyroid nodules provided valuable information for TR4 and TR5 lesions; however, the TR2 and TR3 lesions often had no molecular alterations. These findings highlight the potential value of including US imaging features when assessing the significance of indeterminate cytology findings.

Do ACR TI-RADS scores demonstrate unique thyroid molecular profiles?

PURPOSE: The present study aimed to examine the molecular profiles of cytologically indeterminate thyroid nodules stratified by American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) categories and to determine whether certain ultrasonographic features display particular molecular alterations. METHODS: A retrospective review was conducted of cases from January 1, 2016 to April 1, 2018. Cases with in-house ultrasonography, fine-needle aspiration Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) diagnoses, molecular testing, and surgery were included. All cases were diagnosed as TBSRTC indeterminate categories. The ultrasound studies were retrospectively reviewed and assigned TI-RADS scores (TR1-TR5) by board-certified radiologists. The final diagnoses were determined based on the surgical resection pathology. Binary logistic regression analysis was used to study whether demographic characteristics, TI-RADS levels, and TBSRTC diagnoses were associated with ThyroSeq molecular results. RESULTS: Eighty-one cases met the inclusion criteria. RAS mutations were the most common alteration across all TI-RADS categories (TR2 2/2; TR3 10/19, TR4 13/44, and TR5 8/16), and did not stratify with any particular TI-RADS category. Only TR4 and TR5 categories displayed more aggressive mutations such as BRAFV600E and TERT. ThyroSeq results were positively correlated with thyroid malignancy when non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was categorized in the malignant category (odds ratio [OR], 6.859; P<0.01), but not when NIFTP was removed from the malignancy category. Echogenicity scores were found to be negatively correlated with ThyroSeq results in thyroid nodules (OR, 0.162; P<0.01). CONCLUSION: Higher-risk molecular alterations tended to stratify with the higher TI-RADS categories.

Ultrasound Studies of COVID-19-Positive Patients and Patient Under Investigation: Pandemic Experience of Body Imaging Division at a Tertiary Medical Center.

ABSTRACT: This retrospective study shares our departmental experience of screening of ultrasound (US) requests, triaging of studies, and abbreviated US protocols implemented during the COVID-19 pandemic. For US studies requested in April and May 2020, the following data were collected: type of study, indication, COVID-19 status (positive or patient under investigation [PUI]), decision to perform study, US findings, and location of patient. A total of 196 US studies in 150 patients were included. The median age of patients was 60 years (female: 46.7% [70/150]). At the time of study request, 83 patients (55.3%) were COVID-19-positive and 67 (44.7%) were PUI, of which 8 (11.9%) tested positive after waiting for test result. The most frequently requested study was venous extremity Doppler (51%), followed by right upper quadrant (20.4%), renal (11.7%), and liver duplex (6.6%). After radiologist screening and triage of US requests, 156 studies were performed (79.6%), 15 were postponed until COVID test result (7.6%), and 40 were not performed after discussion with ordering provider (20.4%). Notably, 40.1% of studies performed on COVID-19-positive patients yielded pathological findings, most frequently deep venous thrombosis (18.1%), medical renal disease (7.6%), and gall bladder sludge (5.7%). Abbreviated US protocols were used in 29.4% of studies. In conclusion, US study screening and triage played an important role to optimize care of COVID-19 patients and PUIs.

Asymptomatic Abdominal Aortic Aneurysm: Standardizing Reporting Recommendations at a Large Multistate Radiology Practice.

OBJECTIVE: Although often asymptomatic at initial diagnosis, abdominal aortic aneurysms (AAAs) require careful surveillance to prevent rupture, with rupture-associated mortality rates as high as 90%. The purpose of this study was to explore if a performance improvement initiative implemented across a large radiology practice successfully increased inclusion of best practice recommendations (BPRs) within the radiology report across the practice. METHODS: After BPRs for asymptomatic AAA surveillance were developed, a structured reporting macro for follow-up recommendation was integrated into dictation software. Following a training period, inclusion of recommendations within the radiology report was monitored across 345 facilities within the practice. Performance was reported on scorecards distributed monthly. To measure practice improvement, inclusion of appropriate recommendation in radiology reports postimplementation was compared with pre-implementation data. RESULTS: During the period before AAA BPRs implementation, from 64,090 consecutive cross-sectional radiology reports reviewed during a 6-month period, 855 incidental AAAs (1.3%) were identified, with 783 aneurysms measuring 2.6 to 5.4 cm requiring imaging surveillance; only 17 (2.1%) included follow-up recommendations within the radiology report. Postimplementation, 2,641 of 148,807 cross-sectional imaging studies were positive for 2.6- to 5.4-cm AAAs requiring further management; 1,533 (58.0%) of these radiology reports included follow-up imaging recommendations (97.0% of which followed our AAA BPRs). DISCUSSION: Quality improvement initiatives to develop BPRs for AAA surveillance and include these recommendations within the radiology report can be successfully implemented across large practices and are imperative to ensure imaging surveillance and avert AAA rupture.

Splenic sequestration in the adult: cross sectional imaging appearance of an uncommon diagnosis.

Acute splenic sequestration crisis, the sudden pooling of red blood cells in the spleen, is an emergent process typically seen in children with homozygous sickle cell disease. Splenic sequestration has rarely been reported in adults with heterozygous sickle cell conditions, including sickle cell beta(+)-thalassemia disease (HbS/ß+-thalassemia). Here we present a case of a 32-year-old man with HbS/ß+-thalassemia who suffered an acute splenic sequestration crisis. We review the CT and ultrasound appearance of splenic sequestration, which include splenic enlargement and an irregular rim of hypoenhancing or hypoechoic tissue at the periphery of the spleen, and discuss imaging differential considerations. To our knowledge, this is only the nineteenth case of acute splenic sequestration to be reported in an adult with HbS/ß+-thalassemia in the English literature, and only the second case in which ultrasound findings are reported.

Guidelines for Ultrasound in the Radiology Department During the COVID-19 Pandemic.

The coronavirus disease 2019 is caused by the severe acute respiratory syndrome coronavirus 2. The virus can be spread by close person-to-person contact primarily by respiratory droplets. Given the close proximity of the sonographer or sonologist with the patient during ultrasound examinations, special precautions should be taken to limit the exposure of radiology personnel to patients with coronavirus disease 2019 while still providing optimal patient care. Methods covered in this article include modified workflow, close scrutiny and prioritization of imaging orders, and design of targeted ultrasound protocols. These guidelines summarize the personal experience and insight of multiple colleagues who lead ultrasound sections or are experts in the field.

The pre-CT checklist: A simple tool to improve workflow and patient safety in an outpatient CT setting.

PURPOSE: We aim to share our experience with implementation of a simple checklist to improve workflow and safety in patients scheduled for outpatient CT. METHODS: After identification of several recurrent problems leading to study delays or cancellation, a pre-CT checklist to be used by designated CT technologist in advance of patients' scheduled appointment was designed with input from CT technologists, radiologists, schedulers and nurses. RESULTS: Implementation of the checklist led to further actions in 25.9% of cases. The most common actions were calls to referring providers to modify or clarify an order (24.3%), followed by verification of proper premedication in patients with allergy to iodinated contrast (12.7%) and contacting the radiologist for protocolling (12.7%). CONCLUSIONS: Implementation of a pre-CT checklist that can be tailored to individual practices has potential to improve patients' safety and experience as well as providing a more efficient clinical operation. SUMMARY SENTENCE: We present an easy-to-implement checklist to maximize CT throughput in an outpatient setting that can be customized to the needs of individual institutions and has the potential to improve patients' safety and experience.

Decreasing Duplicative Imaging: Inpatient and Emergency Medicine Abdominal Ultrasound Within 72 Hours of Abdominal CT.

PURPOSE: The aim of this project was to reduce abdominal ultrasound examinations in patients who had undergone abdominal CT within 72 hours previously. METHODS: A best practice advisory (BPA) was created in the electronic medical record to advise against the use of abdominal ultrasound in adult inpatients and emergency department patients who had undergone abdominal CT within the preceding 72 hours. Acceptable acknowledgment reasons to proceed with the order were made available if providers chose to override. Frequency of BPA firing and subsequent ordering behavior were evaluated 6 months after integration of the BPA into the electronic medical record. Chart review was conducted for 100 patients whose orders were placed through an override of the alert to determine if the ultrasound study added value and for all patients whose ultrasound studies were canceled to confirm that patient care was not compromised by omitting the ultrasound study. RESULTS: In the first 6 months, a total of 614 inpatient and emergency department abdominal ultrasound orders triggered the BPA. A total of 16% of orders (n = 96) were canceled by the provider after the BPA, reflecting 518 overrides. The majority of retained orders were to evaluate the gallbladder (44% [227 of 518]). Chart review confirmed utility for gallbladder imaging and that the canceled ultrasound examinations would not have contributed value to patients' care. CONCLUSIONS: A recently performed abdominal CT scan may obviate the need for inpatient and emergency department abdominal ultrasound, particularly in the setting of hospital-acquired acute kidney injury. A BPA resulted in only 16% of orders' being canceled, whereas chart review revealed a much larger opportunity to avoid duplicative imaging.

Does a higher American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) score forecast an increased risk of malignancy? A correlation study of ACR TI-RADS with FNA cytology in the evaluation of thyroid nodules.

BACKGROUND: Ultrasound has become the initial approach to evaluating thyroid nodules, facilitating the distinction between benign and malignant nodules based on composition, echogenicity, nodule border or margin, shape, the presence of calcifications, and nodule dimensions. The American College of Radiology (ACR) recommended the Thyroid Imaging Reporting and Data System (TI-RADS) as a classification system to standardize thyroid ultrasound reports and to predict the probability of malignancy in thyroid nodules using a scoring system (TR1-TR5) based on multiple ultrasound characteristics and nodule size. Fine-needle aspiration (FNA) is recommended as the next step for nodules that warrant further workup. The authors assessed the accuracy of the ACR TI-RADS based on the corresponding FNA cytology results (Bethesda system diagnoses I-VI). METHODS: ACR TI-RADS ultrasound reports and corresponding FNA cytology diagnoses from January 1, 2018 to August 30, 2018 were evaluated. RESULTS: From January 1, 2018 to August 30, 2018, 2306 thyroid ultrasound-guided FNAs were performed at our institution. Of 2306 cases, 361 had ACR TI-RADS reports available. The majority of FNAs were TR4 (180; 49.9%) or TR3 (108; 29.9%). No TR2 or TR3 nodules were associated with Bethesda category V or VI diagnoses. The majority of TR4 nodules (142 of 180; 78.9%) and TR5 nodules (42 of 65; 64.6%) exhibited benign (Bethesda category II) cytology. Fourteen TR5 cases (21.5%) had malignant (Bethesda category VI) cytology. CONCLUSIONS: Although there were no TR2 or TR3 malignant (Bethesda category VI) diagnoses, and there were only a few malignancies in the TR4 and TR5 categories, the current results reassert the notion that the ACR TI-RADS scoring system shows at least some correlation between benign or malignant cytology diagnoses, as illustrated by the greater number of malignant cases in the higher ACR TI-RADS categories.

Interreader Concordance of the TI-RADS: Impact of Radiologist Experience.

OBJECTIVE. The objective of this article is to assess radiologist concordance in characterizing thyroid nodules using the American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS), focusing on the effect of radiologist experience on reader concordance. MATERIALS AND METHODS. Three experienced and three less experienced radiologists assessed 150 thyroid nodules using the TI-RADS lexicon. Percent concordance was determined for various endpoints. RESULTS. Interreader concordance for the five TI-RADS categories was 87.2% for shape, 81.2% for composition, 76.1% for echogenicity, 72.9% for margins, and 69.8% for echogenic foci. Concordance for individual features was 96.3% for rim calcifications, 90.8% for macrocalcifications, 90.1% for spongiform, 83.5% for comet tail artifact, and 77.7% for punctate echogenic foci. Concordance for the TI-RADS level and recommendation for fine-needle aspiration (FNA) were 50.4% and 78.9%, respectively. Concordance was significantly (p < 0.05) higher for less experienced readers in identifying margins (84.3% vs 67.4%), echogenic foci (76.9% vs 69.3%), comet tail artifact (89.6% vs 79.2%), and punctate echogenic foci (85.3% vs 75.5%), and lower for peripheral rim calcifications (95.0% vs 97.8 %), but was not different (p > 0.05) for the remaining categories and features. CONCLUSION. A range of TI-RADS categories, features, and recommendations for FNA had generally moderate interreader agreement among six radiologists. Our results show that concordance for numerous characteristics was significantly higher for the less experienced versus the more experienced readers. These results suggest that less experienced readers relied more on the explicit TI-RADS criteria, whereas the experienced radiologists partially relied on their accumulated experience when forming impressions. However, the overall TI-RADS level and recommendation for FNA were unaffected, supporting the robustness of the TI-RADS lexicon and its continued use in practice.

Additional Surgery for Occult Risk Factors After Lobectomy in Solitary Thyroid Nodules is Predicted by Cytopathology Classification and Tumor Size.

OBJECTIVE: Clinical practice for differentiated thyroid cancer is moving towards lobectomy rather than total thyroidectomy in patients at low risk of recurrence. However, recurrence risk assessment depends on post-operative findings, while the surgical decision is based on preoperative factors. We determined the preoperative predictors of occult higher-risk pathology and rates of completion thyroidectomy among surgical candidates with nonbenign thyroid nodules 10 to 40 mm and no evidence of extrathyroidal extension or metastasis on preoperative evaluation. METHODS: Thyroid surgery cases at a single institution from 2005-2015 were reviewed to identify those meeting American Thyroid Association (ATA) criteria for lobectomy. ATA-based risk stratification from postoperative surgical pathology was compared to preoperative cytopathology, ultrasound, and clinical findings. RESULTS: Of 1,995 thyroid surgeries performed for nonbenign thyroid nodules 10 to 40 mm, 349 met ATA criteria for lobectomy. Occult high-risk features such as tall cell variant, gross extrathyroidal invasion, or vascular invasion were found in 36 cases (10.7%), while intraoperative lymphadenopathy led to surgical upstaging in 13 (3.7%). Intermediate risk features such as moderate lymphadenopathy or minimal extrathyroidal extension were present in an additional 44 cases. Occult risk features were present twice as often in Bethesda class 6 cases (35%) as in lower categories (12 to 17%). In multivariable analysis, Bethesda class and nodule size, but not age, race, sex, or ultrasound features, were significant predictors of occult higher-risk pathology. CONCLUSION: Most solitary thyroid nodules less than 4 cm and with cytology findings including atypia of undetermined significance through suspicious for papillary thyroid cancer would be sufficiently treated by lobectomy. ABBREVIATIONS: ATA = American Thyroid Association; CND = central neck dissection; DTC = differentiated thyroid cancer; ETE = extrathyroidal extension; FNA = fine needle aspiration; FTC/HCC = follicular thyroid carcinoma/Hurthle cell carcinoma; NIFTP = noninvasive follicular thyroid neoplasm with papillary-like nuclear features; OR = odds ratio; PTC = papillary thyroid cancer; US = ultrasound.

Upper urinary tract urothelial carcinoma on multidetector CT: spectrum of disease.

Urothelial carcinoma of the upper urinary tract (UUT) is a relatively uncommon genitourinary malignancy, accounting for about 5-7% of urothelial tumors. The significant features of this tumor are multifocality and high rate of recurrence. Computed tomography urography (CTU) has replaced excretory urography (EU) and retrograde pyelography (RP) for imaging of upper tract urothelial carcinoma. While many studies have confirmed high sensitivity (88-100%) and specificity (93-100%) of CTU, an optimized CT protocol is of critical importance in screening, staging, and post-operative follow-up of patients (Chlapoutakis, Eur J Radiol 73(2):334-338, 2010; Caoli and Cohan, Abdom Radiol (NY) 41(6):1100-1107, 2016). The key element of the CT protocol is to have adequate distension of the collecting system with excreted contrast, to detect subtle lesions at an early stage. In this article, we discuss the background of upper urinary tract TTC, pathogenesis, CT protocol and the role of imaging in evaluation of this malignancy, staging, as well as different imaging appearances.

TIRADS Interobserver Variability Among Indeterminate Thyroid Nodules: A Single-Institution Study.

OBJECTIVES: A high proportion of cytologically indeterminate, Afirma Gene Expression Classifier "suspicious" thyroid nodules are benign. The Thyroid Imaging Reporting and Data System (TIRADS), was proposed by the American College of Radiology in 2017 to help classify thyroid nodules based on ultrasound characteristics in a standardized fashion to guide management. We aim to determine the interobserver variability of TIRADS classification among cytologically indeterminate and Afirma suspicious nodules. METHODS: We retrospectively queried cytopathology archives for thyroid fine-needle aspiration specimens obtained between February 2012 and September 2016 with associated (1) indeterminate diagnosis, (2) ultrasound imaging at our institution, (3) Afirma suspicious result, and (4) surgery at our institution. We compared the TIRADS variability of the 3 blinded radiologists using intraclass correlation coefficients. RESULTS: Our cohort consisted of 127 nodules. Intraclass correlation coefficients can be interpreted as follows: less than 0.4, poor; 0.4 to 0.59, fair; 0.6 to 0.74, good; 0.75 to 1.00, excellent. The intraclass correlation coefficients of the raw TIRADS score and category variability was 0.561 (95% confidence interval [CI]: 0.464-0.651) or fair and 0.547 (95% CI, 0.449-0.640) or fair, respectively. When analyzing composition, echogenicity, shape, margin, and echogenic foci, the ICCs were 0.552 (95% CI, 0.454-0.643), fair; 0.533 (95% CI, 0.432-0.627), fair; 0.359 (95% CI, 0.248-0.469), poor; 0.192 (95% CI, 0.084-0.308), poor; and 0.549 (95% CI, 0.451- 0.641), fair, respectively. CONCLUSIONS: Our results show that among the subset of cytologically indeterminate and Afirma suspicious nodules, TIRADS interobserver variability was fair. Shape and margin criteria were the biggest sources of disagreement. Large prospective studies are needed to evaluate the interobserver variability of TIRADS in this subset of thyroid nodules.

The association between the ultrasonography TIRADS classification system and surgical pathology among indeterminate thyroid nodules.

BACKGROUND: A high proportion of cytologically indeterminate, Afirma-suspicious thyroid nodules are benign. The Thyroid Imaging Reporting and Data System was proposed by the American College of Radiology in 2015 to determine appropriate management of thyroid nodules in a standardized fashion. Our aim was to determine the diagnostic value of the Thyroid Imaging Reporting and Data System in cytologically indeterminate and Afirma-suspicious nodules. METHODS: We retrospectively queried cytopathology archives for retrospectively for thyroid fine-needle aspiration specimens obtained between February 2012 and September 2016 that were associated with the following: (1) indeterminate diagnosis, (2) ultrasonographic imaging at our institution, (3) an Afirma Gene Expression Classifier-suspicious result, and (4) surgery at our institution. We then calculated the diagnostic value of the Thyroid Imaging Reporting and Data System in predicting surgical pathology. RESULTS: Our cohort consisted of 133 nodules among 131 patients who underwent thyroid surgery for cytologically indeterminate, Afirma-suspicious nodules. A total of 9 nodules (6.8%) were assigned TR2 "not suspicious," 25 (18.8%) TR3 "mildly suspicious," 81 (60.9%) TR4 "moderately suspicious," and 18 (13.5%) TR5 "highly suspicious." Among our cohort, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the Thyroid Imaging Reporting and Data System was 71.4%, 38.1%, 40.2%, 69.6%, and 50.4%, respectively. CONCLUSION: Among cytologically indeterminate and Afirma-suspicious nodules, the Thyroid Imaging and Reporting and Data System was a poor predictor of final surgical pathology. Additional prospective studies are needed to validate these findings.

Reader performance in the ultrasonographic evaluation of oropharyngeal carcinoma.

OBJECTIVE: To examine reader performance in evaluating oropharyngeal anatomy on ultrasonography. MATERIALS AND METHODS: Ultrasound images of the oropharynx comprising normal and malignant anatomic variants were organized into slideshows. Slideshows were administered to 6 readers blinded to participant tumor status and with varying experience reading oropharyngeal sonograms. A training slideshow oriented readers to images of the oropharynx with and without malignant lesions. Readers then evaluated images in a test slideshow for tumor presence and marked orthogonal long and short dimensions of the tumor. Results were analyzed for accuracy, sensitivity, specificity, inter-reader agreement, and measurement error relative to prospectively-identified reference measurements. RESULTS: Eighty-seven percent of base of tongue (BOT) sonograms were identified correctly by a majority of readers. In identifying BOT tumors, median accuracy, sensitivity, specificity, and Fleiss's kappa were 79%, 73%, 85%, and 0.51, respectively. Median measurement error in the long and short axes for BOT tumors was -2.6% (range: -40% to 29%) and -2.6% (range: -56% to 156%), respectively. Eighty-four percent of palatine tonsil sonograms were identified correctly by a majority of readers. In identifying tonsil tumors, median accuracy, sensitivity, specificity, and Fleiss's kappa were 77%, 74%, 78%, and 0.41, respectively. Median measurement error in the long and short axes for tonsil tumors was 3.8% (range: -45% to 32%) and -6.5% (range: -83% to 42%), respectively. CONCLUSIONS: Overall, US has clinically useful sensitivity for identification of oropharyngeal carcinoma among readers of diverse clinical backgrounds and experience. US may be useful for the evaluation of features such as tumor dimensions.