ACR Appropriateness Criteria® Hydronephrosis on Prior Imaging-Unknown Cause.

Initial imaging evaluation of hydronephrosis of unknown etiology is a complex subject and is dependent on clinical context. In asymptomatic patients, it is often best conducted via CT urography (CTU) without and with contrast, MR urography (MRU) without and with contrast, or scintigraphic evaluation with mercaptoacetyltriglycine (MAG3) imaging. For symptomatic patients, CTU without and with contrast, MRU without and with contrast, MAG3 scintigraphy, or ultrasound of the kidneys and bladder with Doppler imaging are all viable initial imaging studies. In asymptomatic pregnant patients, nonionizing imaging with US of the kidneys and bladder with Doppler imaging is preferred. Similarly, in symptomatic pregnant patients, US of the kidneys and bladder with Doppler imaging or MRU without contrast is the imaging study of choice, as both ionizing radiation and gadolinium contrast are avoided in pregnancy. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Multicenter Evaluation of Frequency and Impact of Activity Infiltration in PET Imaging, Including Microscale Modeling of Skin-Absorbed Dose.

There has been significant recent interest in understanding both the frequency of nuclear medicine injection infiltration and the potential for negative impact, including skin injury. However, no large-scale study has yet correlated visualized injection site activity with actual activity measurement of an infiltrate. Additionally, current skin dosimetry approaches lack sufficient detail to account for critical factors that impact the dose to the radiosensitive epidermis. Methods: From 10 imaging sites, 1,000 PET/CT patient studies were retrospectively collected. At each site, consecutive patients with the injection site in the field of view were used. The radiopharmaceutical, injected activity, time of injection and imaging, injection site, and injection method were recorded. Net injection site activity was calculated from volumes of interest. Monte Carlo image-based absorbed dose calculations were performed using the actual geometry from a patient with a minor infiltration. The simulation model used an activity distribution in the skin microanatomy based on known properties of subcutaneous fat, dermis, and epidermis. Simulations using several subcutaneous fat-to-dermis concentration ratios were performed. Absorbed dose to the epidermis, dermis, and fat were calculated along with relative γ- and ß-contributions, and these findings were extrapolated to a hypothetical worst-case (470 MBq) full-injection infiltration. Results: Only 6 of 1,000 patients had activity at the injection site in excess of 370 kBq (10 µCi), with no activities greater than 1.7 MBq (45 µCi). In 460 of 1,000 patients, activity at the injection site was clearly visualized. However, quantitative assessment of activities averaged only 34 kBq (0.9 µCi), representing 0.008% of the injected activity. Calculations for the extrapolated 470-MBq infiltration resulted in a hypothetical absorbed dose to the epidermis of below 1 Gy, a factor of 2 lower than what is required for deterministic skin reactions. Analysis of the dose distribution demonstrates that the dermis acts as a ß-shield for the radiation-sensitive epidermis. Dermal shielding is highly effective for low-energy 18F positrons but less so with the higher-energy positrons of 68Ga. Conclusion: When quantitative activity measurement criteria are used rather than visual, the frequency of PET infiltration appears substantially below frequencies previously published. Shallow doses to the epidermis from infiltration events are also likely substantially lower than previously reported because of absorption of ß-particles in the dermis.

68 Ga-DOTATATE Uptake in COVID-19 Pneumonia: A Non-Neoplastic False Positive.

In the detection and characterization of neuroendocrine tumors (NETs), the NETSPOT 68 Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) utilizes a somatostatin analog to capture whole body imaging of somatostatin receptors. Here, we report a rare case of incidental coronavirus disease 2019 (COVID-19) detection using 68 Ga-DOTATATE PET/CT for a 48-year-old patient with COVID-19 who presented to our nuclear medicine department for oncologic and neuroendocrine indications. Current maximal intensity project image from 68Ga-DOTATATE PET/CT demonstrated numerous hypermetabolic foci in the upper abdominal lymph nodes, consistent with somatostatin-avid pancreatic islet cell neoplasm. Radiotracer uptake corresponding to the anatomic infiltrates was also seen in the bilateral pneumonia. With the rise of worldwide COVID-19 cases, and the continued use of NETSPOT for somatostatin avid neoplasms, it is imperative that diagnostic measures of this disease are clearly understood. This case highlights the importance of including COVID-19 on the differential diagnosis when radiotracer uptake appears in 68 Ga-DOTATATE PET/CT.

18F-FDG PET/CT Staging of Head and Neck Cancer: Interobserver Agreement and Accuracy-Results from Multicenter ACRIN 6685 Clinical Trial.

To our knowledge, no prior multicenter clinical trial has reported interobserver agreement of 18F-FDG PET/CT scans for staging of clinical N0 neck in head and neck cancer. Methods: A total of 287 participants were recruited. For visual analysis, positive nodal uptake of 18F-FDG was defined as uptake visually greater than activity seen in the blood pool. Results: The negative predictive value of the 18F-FDG PET/CT for N0 clinical neck was 86% or above for visual assessment (95% CI, 86%-88%) for the 2 central readers and above 90% (95% CI, 90%-95%) for SUVmax for central reads and site reads dichotomized at the optimal cutoff value of 1.8 and the prespecified cutoff value of 3.5, respectively. The κ coefficients between the 2 expert readers and between central reads and site reads varied between 0.53 and 0.78. Conclusion: The NPV of the 18F-FDG PET/CT for N0 clinical neck was 86% or above for visual assessment and above 90% for SUVmax cut points of 1.8 and 3.5 with moderate to substantial agreements.

ACR Appropriateness Criteria® Radiologic Management of Lower Gastrointestinal Tract Bleeding: 2021 Update.

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

COVID-19 messenger ribonucleic acid vaccination and abnormal radiopharmaceutical uptake in the axilla visualized on 68Ga-DOTATATE positron-emission tomography/computed tomography.

As COVID-19 vaccination rates continue to rise, it is becoming increasingly important to understand diagnostic imaging associations' resultant from the vaccines. Here, we report a case of a 59-year-old female who was in remission for gastrointestinal neuroendocrine carcinoma and presented for standard follow-up imaging evaluation. Positron-emission tomography (PET) images from a 68Ga-DOTATATE PET (NETSPOT) demonstrated moderate focal radiotracer uptake in the right axilla. Interestingly, this uptake localized to several normal-sized lymph nodes on the corresponding computed tomography (CT). A medical history revealed the patient received both doses of an ipsilateral COVID-19 messenger ribonucleic acid vaccine injection at 17 and 38 days before the PET/CT study. Subsequent scans 2 months later revealed no radiotracer uptake.

FDG-PET/CT and Pathology in Newly Diagnosed Head and Neck Cancer: ACRIN 6685 Trial, FDG-PET/CT cN0.

OBJECTIVE: FDG-PET/CT (fluorodeoxyglucose-positron emission tomography/computed tomography) is effective to assess for occult neck nodal disease. We report risks and patterns of nodal disease based on primary site and nodal level from data on the dissected cN0 per the results from ACRIN 6685. STUDY DESIGN: Prospective nonrandomized enrollment included participants with first-time head and neck squamous cell carcinoma and at least 1 cN0 neck side to be dissected. SETTING: Twenty-four ACRIN-certified centers internationally (American College of Radiology Imaging Network). METHODS: A total of 287 participants were enrolled. Preoperative FDG-PET/CT findings were centrally reviewed and compared with pathology. Incidence, relative risk, pattern of lymph node involvement, and impact upon neck dissection were reported. RESULTS: An overall 983 nodal levels were dissected (n = 261 necks, n = 203 participants). The highest percentages of ipsilateral positive nodes by primary location and nodal level were oral cavity (level I, 17/110, 15.5%), pharynx (level II, 6/30, 20.0%), and larynx (level VI, 1/3, 33.3%). CONCLUSION: Levels at greatest risk for nodal disease in cN0 in terms of ipsilateral neck dissection are level I (oral cavity), II (pharynx), and VI (larynx). These data should be considered when treating patients presenting with cN0. This is the first study to comprehensively report the incidence, location, and risk of metastases in cN0 in the FDG-PET/CT era.

ACR Appropriateness Criteria® Cerebrovascular Disease-Child.

Stroke is an uncommon but an important and under-recognized cause of morbidity and mortality in children. Strokes may be due to either brain ischemia or intracranial hemorrhage. Common symptoms of pediatric acute stroke include headache, vomiting, focal weakness, numbness, visual disturbance, seizures, and altered consciousness. Most children presenting with an acute neurologic deficit do not have an acute stroke, but have symptoms due to stroke mimics which include complicated migraine, seizures with postictal paralysis, and Bell palsy. Because of frequency of stroke mimics, in children and the common lack of specificity in symptoms, the diagnosis of a true stroke may be delayed. There are a relatively large number of potential causes of stroke mimic and true stroke. Consequently, imaging plays a critical role in the assessment of children with possible stroke and especially in children who present with acute onset of stroke symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Acute Pancreatitis.

Acute pancreatitis (AP) is divided into two types: interstitial edematous and necrotizing. AP severity is classified clinically into mild, moderately severe, and severe, depending on the presence and persistence of organ failure and local or systemic complications. The revised Atlanta classification divides the clinical course of AP into an early (first week) and late phase (after first week) and the clinical phase determines the role of imaging. Imaging has a limited role in the early phase. In the early phase with typical presentations of AP, ultrasound is usually the only appropriate modality and is used for the detection of gallstones. CT and MRI are appropriate in the early phase in equivocal presentations. In the late phase (or at least 48-72 hours after presentation), CT and MRI play a primary role in the imaging of patients with AP for evaluation of etiology, complications, extent of disease, intervention, and follow-up; CT is particularly useful in patients with suspected acute hemorrhage. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Gallium-68-Labeled Prostate-Specific Membrane Antigen-11 PET/CT of Prostate and Nonprostate Cancers.

OBJECTIVE. The purpose of this study is to provide a concise summary of the current experience with 68Ga-labeled prostate-specific membrane antigen (PSMA)-11 imaging of prostate and nonprostate malignancies and benign conditions. CONCLUSION. PSMA is overexpressed in prostate cancer and in the neovasculature of many other malignancies. The relevance of PSMA as a biologic target, coupled with advances in the design, synthesis, and evaluation of PSMA-based radionuclides for imaging and therapy, is anticipated to play a major role in patient care.

ACR Appropriateness Criteria® Dysphagia.

This review summarizes the relevant literature for the initial imaging of patients with symptoms of dysphagia. For patients with oropharyngeal dysphagia who have an underlying attributable cause, a modified barium swallow is usually appropriate for initial imaging but for those who have unexplained dysphagia a fluoroscopic biphasic esophagram is usually appropriate. Fluoroscopic biphasic esophagram is usually appropriate for initial imaging in both immunocompetent and immunocompromised patients who have retrosternal dysphagia. For postoperative patients with dysphagia, fluoroscopic single-contrast esophagram and CT neck and chest with intravenous (IV) contrast are usually appropriate for oropharyngeal or retrosternal dysphagia occurring in the early postoperative period where water-soluble contrast is usually preferred rather than barium sulfate. In the later postoperative period (greater than 1 month), CT neck and chest with IV contrast and fluoroscopic single-contrast esophagram are usually appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Jaundice.

Jaundice is the end result of myriad causes, which makes the role of imaging in this setting particularly challenging. In the United States, the most common causes of all types of jaundice fall into four categories including hepatitis, alcoholic liver disease, blockage of the common bile duct by a gallstone or tumor, and toxic reaction to a drug or medicinal herb. Clinically, differentiating between the various potential etiologies of jaundice requires a detailed history, targeted physical examination, and pertinent laboratory studies, the results of which allow the physician to categorize the type of jaundice into mechanical or nonmechanical causes. Imaging modalities used to evaluate the jaundiced patient (all etiologies) include abdominal ultrasound (US), CT, MR cholangiopancreatography, endoscopic retrograde cholangiopancreatography and endoscopic US. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Multicenter Trial of [18F]fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging of Head and Neck Cancer and Negative Predictive Value and Surgical Impact in the N0 Neck: Results From ACRIN 6685.

PURPOSE: The objective of this study was to determine the negative predictive value (NPV) of positron emission tomography (PET)/computed tomography (CT) for the clinically N0 neck on the basis of neck dissection. METHODS: Participants with newly diagnosed, first-time, head and neck squamous cell carcinoma (HNSCC) and at least one clinically N0 neck side for which dissection was planned were included. A total of 287 participants were prospectively enrolled from 23 American College of Radiology Imaging Network-qualified institutions. PET/CT was compared with findings at neck dissection. RESULTS: PET/CT scans and pathology findings were available for 270 N0 neck sides from 212 participants. For visual assessment, the NPV specific to the clinical-N0 sides was 0.868 (95% CI, 0.803 to 0.925). For dichotomized maximum standardized uptake value, the NPVs specific to the nodal basins were 0.940 (95% CI, 0.928 to 0.952) and 0.937 (95% CI, 0.925 to 0.949) at prespecified cutoffs of 2.5 and 3.5, respectively. The optimal cutoff maximum standardized uptake value was determined to be 1.8, with an NPV of 0.942 (95% CI, 0.930 to 0.953). The PET/CT-informed surgical treatment plan was changed in 51 of 237 participants (22%) compared with the PET/CT-blinded surgical plan. In 34 participants (14%), this led to planned dissection of additional nodal levels. In 12 participants (5%), this led to fewer planned dissected nodal levels. Negative PET/CT scans in N0 necks was true negative in 87% and false negative in 13%. CONCLUSION: [18F]fluorodeoxyglucose-PET/CT has high NPV for the N0 neck in T2 to T4 HNSCC. The surgical treatment plans on the basis of PET/CT findings may be changed in approximately 22% of this group. These findings suggest that [18F]fluorodeoxyglucose-PET/CT may assist the clinician in deciding on the best therapy for the clinically N0 neck in HNSCC. Well-designed clinical trials should be performed to test the outcome of omitting neck dissection by using PET/CT.

AHNS Series: Do you know your guidelines? Optimizing outcomes in reoperative parathyroid surgery: Definitive multidisciplinary joint consensus guidelines of the American Head and Neck Society and the British Association of Endocrine and Thyroid Surgeons.

BACKGROUND: Revision parathyroid is challenging due to possible diagnostic uncertainty as well as the technical challenges it can present. METHODS: A multidisciplinary panel of distinguished experts from the American Head and Neck Society (AHNS) Endocrine Section, the British Association of Endocrine and Thyroid Surgeons (BAETS), and other invited experts have reviewed this topic with the purpose of making recommendations based on current best evidence. The literature was also reviewed on May 12, 2017. PubMed (1946-2017), Cochrane SR (2005-2017), CT databases (1997-2017), and Web of Science (1945-2017) were searched with the following strategy: revision and reoperative parathyroidectomy to ensure completeness. RESULTS: Guideline recommendations were made in 3 domains: preoperative evaluation, surgical management, and alternatives to surgery. Eleven guideline recommendations are proposed. CONCLUSION: Reoperative parathyroid surgery is best avoided if possible. Our literature search and subsequent recommendations found that these cases are best managed by experienced surgeons using precision preoperative localization, intraoperative parathyroid hormone (PTH), and the team approach.

Implementation of a Flipped Classroom for Nuclear Medicine Physician CME.

INTRODUCTION: Increasingly, emerging technologies are expanding instructional possibilities, with new methods being adopted to improve knowledge acquisition and retention. Within medical education, many new techniques have been employed in the undergraduate setting, with less utilization thus far in the continuing medical education (CME) sphere. This paper discusses the use of a new method for CME-the "flipped classroom," widely used in undergraduate medical education. This method engages learners by providing content before the live ("in class") session that aids in preparation and fosters in-class engagement. METHODS: A flipped classroom method was employed using an online image-rich case-based module and quiz prior to a live CME session at a national nuclear medicine meeting. The preparatory material provided a springboard for in-depth discussion at the live session-a case-based activity utilizing audience response technology. Study participants completed a survey regarding their initial experience with this new instructional method. In addition, focus group interviews were conducted with session attendees who had or had not completed the presession material; transcripts were qualitatively analyzed. RESULTS: Quantitative survey data (completed by two-thirds of the session attendees) suggested that the flipped method was highly valuable and met attendee educational objectives. Analysis of focus group data yielded six themes broadly related to two categories-benefits of the flipped method for CME and programmatic considerations for successfully implementing the flipped method in CME. DISCUSSION: Data from this study have proven encouraging and support further investigations around the incorporation of this innovative teaching method into CME for nuclear imaging specialists.

ACR Appropriateness Criteria® Colorectal Cancer Screening.

This review summarizes the relevant literature regarding colorectal screening with imaging. For individuals at average or moderate risk for colorectal cancer, CT colonography is usually appropriate for colorectal cancer screening. After positive results on a fecal occult blood test or immunohistochemical test, CT colonography is usually appropriate for colorectal cancer detection. For individuals at high risk for colorectal cancer (eg, hereditary nonpolyposis colorectal cancer, ulcerative colitis, or Crohn colitis), optical colonoscopy is preferred because of its ability to obtain biopsies to detect dysplasia. After incomplete colonoscopy, CT colonography is usually appropriate for colorectal cancer screening for individuals at average, moderate, or high risk. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Headache-Child.

Headaches in children are not uncommon and have various causes. Proper neuroimaging of these children is very specific to the headache type. Care must be taken to choose and perform the most appropriate initial imaging examination in order to maximize the ability to properly determine the cause with minimum risk to the child. This evidence-based report discusses the different headache types in children and provides appropriate guidelines for imaging these children. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.