Interpretation, Reporting, and Clinical Applications of Liver MR Elastography.

Chronic liver disease is highly prevalent and often leads to fibrosis or cirrhosis and complications such as liver failure and hepatocellular carcinoma. The diagnosis and staging of liver fibrosis is crucial to determine management and mitigate complications. Liver biopsy for histologic assessment has limitations such as sampling bias and high interreader variability that reduce precision, which is particularly challenging in longitudinal monitoring. MR elastography (MRE) is considered the most accurate noninvasive technique for diagnosing and staging liver fibrosis. In MRE, low-frequency vibrations are applied to the abdomen, and the propagation of shear waves through the liver is analyzed to measure liver stiffness, a biomarker for the detection and staging of liver fibrosis. As MRE has become more widely used in clinical care and research, different contexts of use have emerged. This review focuses on the latest developments in the use of MRE for the assessment of liver fibrosis; provides guidance for image acquisition and interpretation; summarizes diagnostic performance, along with thresholds for diagnosis and staging of liver fibrosis; discusses current and emerging clinical applications; and describes the latest technical developments.

Presacral Neuroendocrine Neoplasms: A Multi-site Review of Surgical Outcomes.

INTRODUCTION: Presacral neuroendocrine neoplasms (PNENs) are rare tumors, with limited data on management and outcomes. METHODS: A retrospective review of institutional medical records was conducted to identify all patients with PNENs between 2008 and 2022. Data collection included demographics, symptoms, imaging, surgical approaches, pathology, complications, and long-term outcomes. RESULTS: Twelve patients were identified; two-thirds were female, averaging 44.8 years of age, and, for the most part, presenting with back pain, constipation, and abdominal discomfort. Preoperative imaging included computed tomography scans and magnetic resonance images, with somatostatin receptor imaging and biopsies being common. Half of the patients had metastatic disease on presentation. Surgical approach varied, with anterior, posterior, and combined techniques used, often involving muscle transection and coccygectomy. Short-term complications affected one-quarter of patients. Pathologically, PNENs were mainly well-differentiated grade 2 tumors with positive synaptophysin and chromogranin A. Associated anomalies were common, with tail-gut cysts prevalent. Mean tumor diameter was 6.3 cm. Four patients received long-term adjuvant therapy. Disease progression necessitated additional interventions, including surgery and various chemotherapy regimens. Skeletal, liver, thyroid, lung, and pancreatic metastases occurred during follow-up, with no mortality reported. Kaplan-Meier analysis showed a 5-year local recurrence rate of 23.8%, disease progression rate of 14.3%, and de novo metastases rate of 30%. CONCLUSION: The study underscores the complex management of PNENs and emphasizes the need for multicenter research to better understand and manage these tumors. It provides valuable insights into surgical outcomes, recurrence rates, and overall survival, guiding future treatment strategies for PNEN patients.

Natural language processing pipeline to extract prostate cancer-related information from clinical notes.

OBJECTIVES: To develop an automated pipeline for extracting prostate cancer-related information from clinical notes. MATERIALS AND METHODS: This retrospective study included 23,225 patients who underwent prostate MRI between 2017 and 2022. Cancer risk factors (family history of cancer and digital rectal exam findings), pre-MRI prostate pathology, and treatment history of prostate cancer were extracted from free-text clinical notes in English as binary or multi-class classification tasks. Any sentence containing pre-defined keywords was extracted from clinical notes within one year before the MRI. After manually creating sentence-level datasets with ground truth, Bidirectional Encoder Representations from Transformers (BERT)-based sentence-level models were fine-tuned using the extracted sentence as input and the category as output. The patient-level output was determined by compilation of multiple sentence-level outputs using tree-based models. Sentence-level classification performance was evaluated using the area under the receiver operating characteristic curve (AUC) on 15% of the sentence-level dataset (sentence-level test set). The patient-level classification performance was evaluated on the patient-level test set created by radiologists by reviewing the clinical notes of 603 patients. Accuracy and sensitivity were compared between the pipeline and radiologists. RESULTS: Sentence-level AUCs were ≥ 0.94. The pipeline showed higher patient-level sensitivity for extracting cancer risk factors (e.g., family history of prostate cancer, 96.5% vs. 77.9%, p < 0.001), but lower accuracy in classifying pre-MRI prostate pathology (92.5% vs. 95.9%, p = 0.002) and treatment history of prostate cancer (95.5% vs. 97.7%, p = 0.03) than radiologists, respectively. CONCLUSION: The proposed pipeline showed promising performance, especially for extracting cancer risk factors from patient's clinical notes. CLINICAL RELEVANCE STATEMENT: The natural language processing pipeline showed a higher sensitivity for extracting prostate cancer risk factors than radiologists and may help efficiently gather relevant text information when interpreting prostate MRI. KEY POINTS: When interpreting prostate MRI, it is necessary to extract prostate cancer-related information from clinical notes. This pipeline extracted the presence of prostate cancer risk factors with higher sensitivity than radiologists. Natural language processing may help radiologists efficiently gather relevant prostate cancer-related text information.

Performance of CT With Adrenal-Washout Protocol in Heterogeneous Adrenal Nodules: A Multiinstitutional Study.

BACKGROUND. CT with adrenal-washout protocol (hereafter, adrenal-protocol CT) is commonly performed to distinguish adrenal adenomas from other adrenal tumors. However, the technique's utility among heterogeneous nodules is not well established, and the optimal method for placing ROIs in heterogeneous nodules is not clearly defined. OBJECTIVE. The purpose of our study was to determine the diagnostic performance of adrenal-protocol CT to distinguish adenomas from nonadenomas among heterogeneous adrenal nodules and to compare this performance among different methods for ROI placement. METHODS. This retrospective study included 164 patients (mean age, 59.1 years; 61 men, 103 women) with a total of 164 heterogeneous adrenal nodules evaluated using adrenal-protocol CT at seven institutions. All nodules had an available pathologic reference standard. A single investigator at each institution evaluated the CT images. ROIs were placed on portal venous phase images using four ROI methods: standard ROI, which refers to a single large ROI in the nodule's center; high ROI, a single ROI on the nodule's highest-attenuation area; low ROI, a single ROI the on nodule's lowest-attenuation area; and average ROI, the mean of the three ROIs on the nodule's superior, middle, and inferior thirds using the approach for the standard ROI. ROIs were then placed in identical locations on unenhanced and delayed phase images. Absolute washout was determined for all methods. RESULTS. The nodules comprised 82 adenomas and 82 nonadenomas (36 pheochromocytomas, 20 metastases, 12 adrenocortical carcinomas, and 14 nodules with other pathologies). The mean nodule size was 4.5 ± 2.8 (SD) cm (range, 1.6-23.0 cm). Unenhanced CT attenuation of 10 HU or less exhibited sensitivity and specificity for adenoma of 22.0% and 96.3% for standard-ROI, 11.0% and 98.8% for high-ROI, 58.5% and 84.1% for low-ROI, and 30.5% and 97.6% for average-ROI methods. Adrenal-protocol CT overall (unenhanced attenuation ≤ 10 HU or absolute washout of ≥ 60%) exhibited sensitivity and specificity for adenoma of 57.3% and 84.1% for the standard-ROI method, 63.4% and 51.2% for the high-ROI method, 68.3% and 62.2% for the low-ROI method, and 59.8% and 85.4% for the average-ROI method. CONCLUSION. Adrenal-protocol CT has poor diagnostic performance for distinguishing adenomas from nonadenomas among heterogeneous adrenal nodules regardless of the method used for ROI placement. CLINICAL IMPACT. Adrenal-protocol CT has limited utility in the evaluation of heterogeneous adrenal nodules.

Multimodality Imaging in Metabolic Syndrome: State-of-the-Art Review.

Metabolic syndrome comprises a set of risk factors that include abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, low high-density lipoprotein levels, and high blood pressure, at least three of which must be fulfilled for diagnosis. Metabolic syndrome has been linked to an increased risk of cardiovascular disease and type 2 diabetes mellitus. Multimodality imaging plays an important role in metabolic syndrome, including diagnosis, risk stratification, and assessment of complications. CT and MRI are the primary tools for quantification of excess fat, including subcutaneous and visceral adipose tissue, as well as fat around organs, which are associated with increased cardiovascular risk. PET has been shown to detect signs of insulin resistance and may detect ectopic sites of brown fat. Cardiovascular disease is an important complication of metabolic syndrome, resulting in subclinical or symptomatic coronary artery disease, alterations in cardiac structure and function with potential progression to heart failure, and systemic vascular disease. CT angiography provides comprehensive evaluation of the coronary and systemic arteries, while cardiac MRI assesses cardiac structure, function, myocardial ischemia, and infarction. Liver damage results from a spectrum of nonalcoholic fatty liver disease ranging from steatosis to fibrosis and possible cirrhosis. US, CT, and MRI are useful in assessing steatosis and can be performed to detect and grade hepatic fibrosis, particularly using elastography techniques. Metabolic syndrome also has deleterious effects on the pancreas, kidney, gastrointestinal tract, and ovaries, including increased risk for several malignancies. Metabolic syndrome is associated with cerebral infarcts, best evaluated with MRI, and has been linked with cognitive decline. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Pickhardt in this issue.

Deciphering ovarian torsion: insights from CT imaging analysis.

PURPOSE: In the milieu of emergency medicine, pelvic and lower abdominal pain present recurrently, with ovarian torsion posing a formidable diagnostic quandary amid multifarious etiologies. Given the burgeoning reliance on CT in acute care settings, it invariably assumes primacy as the principal imaging modality. This study endeavors to elucidate the CT imaging manifestations encountered by surgically confirmed ovarian torsion patients and utilizing CT to differentiate necrosis. METHODS: A retrospective analysis (January, 2015- April, 2019) utilizing hospital archives was conducted on patients diagnosed with ovarian torsion, post-surgery. Inclusion criteria encompassed patients who underwent CT examinations within one week of diagnosis. A large array of CT findings encompassing midline orientation, uterine deviation, intraovarian hematoma/mass, and multiple others were systematically documented. RESULTS: 90 patients were diagnosed with ovarian torsion- 53 (59%) had CT within one week of diagnosis, 41(77%) underwent a CT with IV contrast and 12 (23%) without IV contrast. Mean age was 43 years (range 19-77 years), with near equal distribution of involvement of each ovary. Mean maximum ovarian diameter was 11.7 ± 6.3 cm (4.2-34.8 cm). Most common imaging features include the presence of thickened pedicle (43/53, 81%), midline ovary (41/53, 77%), presence of thickened fallopian tube (31/49, 63%), and ipsilateral uterine deviation (33/53, 62%). Based on contemporaneous imaging report, torsion was diagnosed in 25/ 53 studies giving a sensitivity of 47%. CONCLUSION: Enlarged ovarian dimensions (> 3.0 cm), thickened vascular pedicle or fallopian tube, midline ovarian disposition with ipsilateral uterine deviation, and the presence of a whirlpool sign emerged as predominant CT imaging features in surgically confirmed ovarian torsion cases, serving as pivotal diagnostic aides for radiologists. Concomitant pelvic free fluid and intraovarian hematoma signify necrotic changes, indicative of ischemic severity and disease progression.

Clinical, imaging and biochemical presentation of cystic pheochromocytomas.

OBJECTIVE: Cystic adrenal mass is a rare imaging presentation of pheochromocytoma. We aimed to describe the clinical, biochemical and imaging characteristics of patients with cystic pheochromocytoma. DESIGN: Single-centre, retrospective study, 2000-2020. PATIENTS: Consecutive patients with cystic pheochromocytoma were identified from our institutional pathology and adrenal tumour database. RESULTS: Of the 638 patients with pheochromocytomas, 21 (3.2%) had cystic pheochromocytomas (median age: 57 years, 57% women). Most pheochromocytomas were discovered incidentally (57%) or due to symptoms of catecholamine excess (24%). The median tumour size was 6.4 cm. On imaging, cystic pheochromocytomas were round or oval (90%), heterogeneous lesions (86%) with a thick solid rim (median rim thickness 13.9 mm, unenhanced computed tomography (CT) attenuation 40 Hounsfield units (HU), venous-phase CT attenuation 83 HU), and a median cystic component of 40% (unenhanced CT attenuation 17.6 HU, venous-phase CT attenuation 20.4 HU), and rarely with calcifications (15%). All 20 patients with biochemical testing had functioning tumours (adrenergic in 80%, noradrenergic in 20%). Total urinary metanephrine excretion correlated with the volume of the solid component (R2 = .75, p < .0001) but not the cystic component (R2 = .04, p = .4386). All patients underwent adrenalectomy (48% laparoscopic, 52% open), and the median duration of hospital stay was 4 days. CONCLUSIONS: Cystic pheochromocytomas are rare, large tumours with a phenotypic appearance that can masquerade as other adrenal cystic lesions. The degree of biochemical abnormality in cystic pheochromocytomas is associated with the volume of the solid component. All patients with adrenal cysts that have a solid component or an unenhanced attenuation >10 HU should undergo biochemical testing for pheochromocytoma.

Accuracy of DOTATATE PET imaging in the preoperative planning of small bowel neuroendocrine tumor resection.

BACKGROUND AND OBJECTIVES: We assessed the accuracy of preoperative gallium-68 DOTA-Tyr3-octreotate (DOTATATE) positron emission tomography (PET) imaging in estimating multifocality and nodal metastases of small bowel neuroendocrine tumors (sbNETs). METHODS: A multicenter analysis was performed on patients with sbNETs who underwent preoperative DOTATATE PET imaging and surgical resection, with manual palpation of the entire length of the small bowel, between January 2016 and August 2022. Preoperative imaging reports and blinded secondary imaging reviews were compared to the final postoperative pathology reports. Descriptive statistics were applied. RESULTS: One-hundred and four patients met inclusion criteria. Pathology showed 53 (51%) patients had multifocal sbNETs and 96 (92%) had nodal metastases. The original preoperative DOTATATE PET imaging identified multifocal sbNET in 28 (27%) patients and lymph node (LN) metastases in 80 (77%) patients. Based on original radiology reports, sensitivity for multifocal sbNET identification was 45%, specificity was 92%, positive predictive value (PPV) was 86%, and negative predictive value (NPV) was 62%. For the identification of LN metastases, sensitivity was 82%, specificity was 88%, PPV was 99%, and NPV was 29%. CONCLUSIONS: Although DOTATATE PET imaging is specific and relatively accurate, sensitivity and NPV are insufficient to guide surgical planning. Preoperative use should not replace open palpation to identify additional synchronous lesions or to omit regional lymphadenectomy.

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review.

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Imaging of Castleman Disease.

Castleman disease (CD) is a group of rare and complex lymphoproliferative disorders that can manifest in two general forms: unicentric CD (UCD) and multicentric CD (MCD). These two forms differ in clinical manifestation, imaging appearances, treatment options, and prognosis. UCD typically manifests as a solitary enlarging mass that is discovered incidentally or after development of compression-type symptoms. MCD usually manifests acutely with systemic symptoms including fever and weight loss. As a whole, CD involves lymph nodes throughout the chest, neck, abdomen, pelvis, and axilla and can have a wide variety of imaging appearances. Most commonly, lymph nodes or masses in UCD occur in the chest, classically with well-defined borders, hyperenhancement, and possible characteristic patterns of calcification and/or feeding vessels. Lymph nodes affected by MCD, while also hyperenhancing, tend to involve multiple nodal chains and manifest alongside anasarca or hepatosplenomegaly. The polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) subtype of MCD may demonstrate lytic or sclerotic osseous lesions in addition to features typical of MCD. Since a diagnosis of CD based solely on imaging findings is often not possible, pathologic confirmation with core needle biopsy and/or surgical excision is necessary. Nevertheless, imaging plays a crucial role in supporting the diagnosis of CD, guiding appropriate regions for biopsy, and excluding other potential causes or mimics of disease. CT is frequently the initial imaging technique used in evaluating potential CD. MRI and PET play important roles in thoroughly evaluating the disease and determining its extent, especially the MCD form. Complete surgical excision is typically curative for UCD. MCD usually requires systemic therapy. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards.

The radiologic diagnosis of adrenal disease can be challenging in settings of atypical presentations, mimics of benign and malignant adrenal masses, and rare adrenal anomalies. Misdiagnosis may lead to suboptimal management and adverse outcomes. Adrenal adenoma is the most common benign adrenal tumor that arises from the cortex, whereas adrenocortical carcinoma (ACC) is a rare malignant tumor of the cortex. Adrenal cyst and myelolipoma are other benign adrenal lesions and are characterized by their fluid and fat content, respectively. Pheochromocytoma is a rare neuroendocrine tumor of the adrenal medulla. Metastases to the adrenal glands are the most common malignant adrenal tumors. While many of these masses have classic imaging appearances, considerable overlap exists between benign and malignant lesions and can pose a diagnostic challenge. Atypical adrenal adenomas include those that are lipid poor; contain macroscopic fat, hemorrhage, and/or iron; are heterogeneous and/or large; and demonstrate growth. Heterogeneous adrenal adenomas may mimic ACC, metastasis, or pheochromocytoma, particularly when they are 4 cm or larger, whereas smaller versions of ACC, metastasis, and pheochromocytoma and those with washout greater than 60% may mimic adenoma. Because of its nonenhanced CT attenuation of less than or equal to 10 HU, a lipid-rich adrenal adenoma may be mimicked by a benign adrenal cyst, or it may be mimicked by a tumor with central cystic and/or necrotic change such as ACC, pheochromocytoma, or metastasis. Rare adrenal tumors such as hemangioma, ganglioneuroma, and oncocytoma also may mimic adrenal adenoma, ACC, metastasis, and pheochromocytoma. The authors describe cases of adrenal neoplasms that they have encountered in clinical practice and presented to adrenal multidisciplinary tumor boards. Key lessons to aid in diagnosis and further guide appropriate management are provided. © RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Imaging Features in the Liver after Stereotactic Body Radiation Therapy.

Historically, radiation therapy was not considered in treatment of liver tumors owing to the risk of radiation-induced liver disease. However, development of highly conformed radiation treatments such as stereotactic body radiation therapy (SBRT) has increased use of radiation therapy in the liver. SBRT is indicated in treatment of primary and metastatic liver tumors with outcomes comparable to those of other local therapies, especially in treatment of hepatocellular carcinoma. After SBRT, imaging features of the tumor and surrounding background hepatic parenchyma demonstrate a predictable pattern immediately after treatment and during follow-up. The goals of SBRT are to deliver a lethal radiation dose to the targeted liver tumor and to minimize radiation dose to normal liver parenchyma and other adjacent organs. Evaluation of tumor response after SBRT centers on changes in size and enhancement; however, these changes are often delayed secondary to the underlying physiologic effects of radiation. Knowledge of the underlying pathophysiologic mechanisms of SBRT should allow better understanding of the typical imaging features in detection of tumor response and avoid misinterpretation from common pitfalls and atypical imaging findings. Imaging features of radiation-induced change in the surrounding liver parenchyma are characterized by a focal liver reaction that can potentially be mistaken for no response or recurrence of tumor. Knowledge of the pattern and chronology of this phenomenon may allay any uncertainty in assessment of tumor response. Other pitfalls related to fiducial marker placement or combination therapies are important to recognize. The authors review the basic principles of SBRT and illustrate post-SBRT imaging features of treated liver tumors and adjacent liver parenchyma with a focus on avoiding pitfalls in imaging evaluation of response. Online supplemental material is available for this article. ©RSNA, 2022.

Radiofrequency Ablation of Benign and Malignant Thyroid Nodules.

Thyroid nodule treatment has significantly evolved over recent years with attempts to individualize treatment on the basis of the cause of the nodule and patient performance status. The risks and complications associated with surgery and radioactive iodine have promoted interest in additional therapies such as radiofrequency ablation (RFA). RFA creates an electrical current through a target tissue (thyroid nodule) with resultant tissue heating causing coagulative necrosis. National and international groups are beginning to recognize the role of RFA as a viable therapeutic option in the treatment of thyroid nodules. Based on numerous guidelines, RFA is indicated in the treatment of symptomatic benign nodules and autonomously functioning nodules when surgery is refused or when the patient would not tolerate surgery. The treatment of thyroid malignancy with RFA is controversial, with some groups advocating for its use in the treatment of small papillary thyroid cancers in specific scenarios. The most important aspect of RFA is the preprocedural workup and adequate patient selection. Procedural technique varies among centers. However, RFA is typically performed as a single-day-admission outpatient procedure. Methods such as hydrodissection and a moving shot technique are employed to ensure adequate coverage of the nodule without overtreating the peripheries and damaging sensitive structures. As a result, the procedure is well tolerated, and major complications such as recurrent laryngeal nerve injury and nodule rupture are very rare. In the proper patient cohort, thyroid RFA offers an efficacious and safe option in the management of thyroid nodules. An invited commentary by Filippiadis and Vrachliotis is available online. ©RSNA, 2022.

Small bowel radiology.

PURPOSE OF REVIEW: Recent advances in computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), and nuclear radiology have improved the diagnosis and characterization of small bowel pathology. Our purpose is to highlight the current status and recent advances in multimodality noninvasive imaging of the small bowel. RECENT FINDINGS: CT and MR enterography are established techniques for small bowel evaluation. Dual-energy CT is a novel technique that has shown promise for the mesenteric ischemia and small bowel bleeding. Advanced US techniques and MRI sequences are being investigated to improve assessment of bowel inflammation, treatment response assessment, motility, and mural fibrosis. Novel radiotracers and scanner technologies have made molecular imaging the new reference standard for small bowel neuroendocrine tumors. Computational image analysis and artificial intelligence (AI) have the potential to augment physician expertise, reduce errors and variability in assessment of the small bowel on imaging. SUMMARY: Advances in translational imaging research coupled with progress in imaging technology have led to a wider adoption of cross-sectional imaging for the evaluation and management of small bowel entities. Ongoing developments in image acquisition and postprocessing techniques, molecular imaging and AI have the strongest potential to transform the care and outcomes of patients with small bowel diseases.

Frequency and Characteristics of Nodal and Deltoid FDG and 11C-Choline Uptake on PET Performed After COVID-19 Vaccination.

BACKGROUND. COVID-19 vaccination may trigger reactive lymphadenopathy, confounding imaging interpretation. There has been limited systematic analysis of PET findings after COVID-19 vaccination. OBJECTIVE. The purpose of this study was to evaluate the frequency and characteristics of abnormal FDG and 11C-choline uptake on PET performed after COVID-19 vaccination. METHODS. This retrospective study included 67 patients (43 men and 24 women; mean [± SD] age, 75.6 ± 9.2 years) who underwent PET examination between December 14, 2020, and March 10, 2021, after COVID-19 vaccination and who had undergone prevaccination PET examination without visible axillary node uptake. A total of 52 patients received the BNT162b2 mRNA COVID-19 vaccine (Pfizer-BioNTech; hereafter referred to as the Pfizer-BioNTech vaccine), and 15 received the SARS-CoV-2 mRNA-1273 vaccine (Moderna; hereafter referred to as the Moderna vaccine). Sixty-six of the patients underwent PET/CT, and one underwent PET/MRI. Fifty-four PET examinations used FDG, and 13 used 11C-choline. PET was performed a median of 13 and 10 days after vaccination for patients who had received one (n = 44) and two (n = 23) vaccine doses, respectively. Two nuclear medicine physicians independently reviewed images and were blinded to injection laterality and the number of days since vaccination. Lymph node or deltoid SUVmax greater than the blood pool SUVmax was considered positive. Interreader agreement was assessed, and the measurements made by the more experienced physician were used for subsequent analysis. RESULTS. Positive axillary lymph node uptake was observed in 10.4% (7/67) of patients (7.4% [4/54] of FDG examinations and 23.1% [3/13] of 11C-choline examinations); of the patients with positive axillary lymph nodes, four had received the Pfizer vaccine, and three had received the Moderna vaccine. Injection laterality was documented for five of seven patients with positive axillary lymph nodes and was ipsilateral to the positive node in all five patients. PET was performed within 24 days of vaccination for all patients with a positive node. One patient showed extraaxillary lymph node uptake (ipsilateral supraclavicular uptake on FDG PET). Ipsilateral deltoid uptake was present in 14.5% (8/55) of patients with documented injection laterality, including 42.9% (3/7) of patients with positive axillary lymph nodes. Interreader agreement for SUV measurements (expressed as intraclass correlation coefficients) ranged from 0.600 to 0.988. CONCLUSION. Increased axillary lymph node or ipsilateral deltoid uptake is occasionally observed on FDG or 11C-choline PET performed after COVID-19 vaccination with the Pfizer-BioNTech or Moderna vaccine. CLINICAL IMPACT. Interpreting physicians should recognize characteristics of abnormal uptake on PET after COVID-19 vaccination to guide optimal follow-up management and reduce unnecessary biopsies.

The Role of Magnetic Resonance Elastography in the Diagnosis of Noncirrhotic Portal Hypertension.

Portal hypertension (PH) is defined as abnormal elevation of portal venous pressure with cirrhosis accounting for 90% of cases and 10% of cases classified as noncirrhotic PH (NCPH).1,2 The differentiation of cirrhotic PH (CPH) from NCPH is difficult (Supplementary Figure 1), with recent research efforts focusing on noninvasive evidence of increased hepatic stiffness.3,4 Magnetic resonance elastography (MRE) is an established imaging technique in the assessment of hepatic stiffness, and is now the most efficacious, noninvasive method to assess for hepatic fibrosis.5-8 The aim of this study was to assess the ability of magnetic resonance imaging (MRI) and MRE to differentiate between CPH and NCPH.

Periprocedural Major Bleeding Risk of Image-Guided Percutaneous Chest Tube Placement in Patients with an Elevated International Normalized Ratio.

PURPOSE: To evaluate the incidence of major hemorrhage after image-guided percutaneous chest tube placement in patients with an abnormal international normalized ratio (INR) measured before the procedure. MATERIALS AND METHODS: Between January 2013 and September 2017, 49 image-guided percutaneous chest tubes were placed in 45 adult patients who had an elevated INR of greater than 1.6. Data collected included routine serum pre-procedure coagulation studies, indication for chest tube placement, insertion technique, size of chest tube, and presence of complications after drain placement. Major bleeding complications were defined using the Society of Interventional Radiology classification system. RESULTS: Mean patient age was 62 years (range, 22-94 years), with median American Society of Anesthesiologists score of 4. Mean INR was 2.1 (range, 1.7-3), with 21 (43%) procedures with an INR between 1.7 and 1.9, 20 (41%) procedures with an INR between 2.0 and 2.4, and 8 (16%) procedures with an INR between 2.5 and 3.0. Computed tomography guidance was used for 27 (55%) procedures; ultrasound guidance was used for 22 (45%) procedures. Median size of chest tube was 10 Fr (range, 8-14 Fr) used in 27 (55%) procedures. No major bleeding complications were observed. There was a small, significant decrease in mean hemoglobin after the procedure (mean = 0.9g/dL; P < .0001), which correlated to increasing chest tube size (P = .0269). CONCLUSIONS: No major bleeding complications were observed after image-guided percutaneous chest tube placement in patients with an elevated INR. Major bleeding complications in these patients may be safer than initially considered, and this study encourages the conduct of larger trials for further evaluation.