Contrast Media in Pregnant and Lactating Patients, From the AJR Special Series on Contrast Media.

IV contrast media improve the diagnostic power of radiology examinations. These media include gadolinium-based contrast media and iron-oxide nanoparticles for MRI, iodinated contrast material for CT, microbubbles for ultrasound, and radiopharmaceuticals for nuclear medicine. As for all medications, contrast media carry risks, which may be heightened in the conditions of pregnancy and lactation. Radiologists must understand the potential risks from contrast media exposure to the pregnant patient, fetus, and nursing infant, as well as understand these administrations' impact on examinations' clinical utility. This article reviews the available literature on these media, along with key regulatory bodies' and professional societies' current recommendations for their use, in the settings of pregnancy and lactation. This knowledge should help radiologists make well-reasoned risk-benefit analyses regarding contrast media administration and provide informed consent discussions with pregnant and nursing patients in whom contrast media administration is being considered. This information and analysis can also assist facilities in designing policies and standard operating procedures of possible clinical benefit to the pregnant patient, fetus, or nursing infant, balancing contrast media exposure considerations versus augmented diagnostic capabilities.

Artificial intelligence model for enhancing the accuracy of transvaginal ultrasound in detecting endometrial cancer and endometrial atypical hyperplasia.

OBJECTIVES: Transvaginal ultrasound is typically the initial diagnostic approach in patients with postmenopausal bleeding for detecting endometrial atypical hyperplasia/cancer. Although transvaginal ultrasound demonstrates notable sensitivity, its specificity remains limited. The objective of this study was to enhance the diagnostic accuracy of transvaginal ultrasound through the integration of artificial intelligence. By using transvaginal ultrasound images, we aimed to develop an artificial intelligence based automated segmentation model and an artificial intelligence based classifier model. METHODS: Patients with postmenopausal bleeding undergoing transvaginal ultrasound and endometrial sampling at Mayo Clinic between 2016 and 2021 were retrospectively included. Manual segmentation of images was performed by four physicians (readers). Patients were classified into cohort A (atypical hyperplasia/cancer) and cohort B (benign) based on the pathologic report of endometrial sampling. A fully automated segmentation model was developed, and the performance of the model in correctly identifying the endometrium was compared with physician made segmentation using similarity metrics. To develop the classifier model, radiomic features were calculated from the manually segmented regions-of-interest. These features were used to train a wide range of machine learning based classifiers. The top performing machine learning classifier was evaluated using a threefold approach, and diagnostic accuracy was assessed through the F1 score and area under the receiver operating characteristic curve (AUC-ROC). RESULTS: 302 patients were included. Automated segmentation-reader agreement was 0.79±0.21 using the Dice coefficient. For the classification task, 92 radiomic features related to pixel texture/shape/intensity were found to be significantly different between cohort A and B. The threefold evaluation of the top performing classifier model showed an AUC-ROC of 0.90 (range 0.88-0.92) on the validation set and 0.88 (range 0.86-0.91) on the hold-out test set. Sensitivity and specificity were 0.87 (range 0.77-0.94) and 0.86 (range 0.81-0.94), respectively. CONCLUSIONS: We trained an artificial intelligence based algorithm to differentiate endometrial atypical hyperplasia/cancer from benign conditions on transvaginal ultrasound images in a population of patients with postmenopausal bleeding.

Safety and Efficacy of CT-Guided Percutaneous Biopsy of Suspicious Subcentimeter Pelvic and Retroperitoneal Lymph Nodes Detected by 11C-Choline PET in Patients With Prostate Cancer.

BACKGROUND. In patients with prostate cancer, PET using targeted radiotracers can identify increased activity in small morphologically normal lymph nodes, facilitating earlier detection of metastatic disease. OBJECTIVE. The purpose of this article was to assess the efficacy and safety of CT-guided biopsy of suspicious pelvic and retroperitoneal lymph nodes measuring smaller than 1 cm detected by 11C-choline PET in patients with prostate cancer, with comparison with nodes measuring 1 cm or larger. METHODS. This retrospective study included patients with prostate cancer who underwent CT-guided percutaneous biopsy of suspicious pelvic or retroperitoneal lymph nodes detected by 11C-choline PET/CT or PET/MRI (performed because of a rising or elevated PSA level or known recurrent or metastatic disease) between June 1, 2012, and March 20, 2020. Patient, lymph node, and procedural characteristics, as well as biopsy outcomes and complications, were recorded. Biopsies of lymph nodes measuring smaller than 1 cm and of lymph nodes measuring 1 cm and larger were compared. RESULTS. A total of 269 patients (mean age, 68.7 ± 6.8 [SD] years) were included. A total of 156 patients underwent biopsy of lymph nodes measuring smaller than 1 cm (range, 3-9 mm); 113 patients underwent biopsy of lymph nodes measuring 1 cm or larger (range, 10-35 mm). Lymph nodes smaller than 1 cm and lymph nodes 1 cm and larger showed no significant difference in diagnostic yield (89.7% vs 92.9%; p = .40). Diagnostic yield was not significantly different between nodes smaller than 1 cm and nodes 1 cm and larger for any individual anatomic location within the pelvis or retroperitoneum (all p > .05). Malignant yield was lower for nodes smaller than 1 cm than for nodes 1 cm and larger (44.9% vs 63.7%; p = .003). The single biopsied 3-mm node had a nondiagnostic specimen. Diagnostic yield and malignant yield were 100.0% and 40.0%, respectively, for 4-mm nodes, and 95.5% and 45.5%, respectively, for 5-mm nodes. Patients with nodes smaller than 1 cm and nodes 1 cm and larger showed no significant difference in minor (12.8% vs 7.1%; p = .16) or major (0.6% vs 2.7%; p = .31) complication rate. CONCLUSION. The findings support the safety and efficacy of CT-guided biopsy of suspicious subcentimeter pelvic and retroperitoneal lymph nodes detected on 11C-choline PET in patients with prostate cancer. CLINICAL IMPACT. Earlier diagnosis of metastatic lymphadenopathy will impact prognostic assessment and management decisions in patients with recurrent prostate cancer.

Atypical Metastases in the Abdomen and Pelvis From Biochemically Recurrent Prostate Cancer: 11C-Choline PET/CT With Multimodality Correlation.

PET with targeted radiotracers has become integral to mapping the location and burden of recurrent disease in patients with biochemical recurrence (BCR) of prostate cancer (PCa). PET with 11C-choline is part of the National Comprehensive Cancer Network and European Association of Urology guidelines for evaluation of BCR. With advances in PET technology, increasing use of targeted radiotracers, and improved survival of patients with BCR because of novel therapeutics, atypical sites of metastases are being increasingly encountered, challenging the conventional view that prostate cancer rarely metastasizes beyond bones or lymph nodes. The purpose of this article is to describe such atypical metastases in the abdomen and pelvis on 11C-choline PET (including metastases to the liver, pancreas, genital tract, urinary tract, peritoneum, abdominal wall, and perineural spread) and to present multimodality imaging features and relevant imaging pitfalls. Given atypical metastases' inconsistent relationship with the serum PSA level and the nonspecific presenting symptoms, atypical metastases are often first detected on imaging. Awareness of their imaging features is important because their detection affects clinical management, patient counseling, prognosis, and clinical trial eligibility. Such awareness is particularly critical because the role of radiologists in the imaging and management of BCR will continue to increase given the expanding regulatory approvals of other targeted and theranostic radiotracers.

How We Do It: A Multidisciplinary Approach to 177Lu DOTATATE Peptide Receptor Radionuclide Therapy.

Lutetium 177 (177Lu) DOTA-0-Tyr3-Octreotate (DOTATATE) peptide receptor radionuclide therapy (PRRT) is an effective treatment for advanced gastroenteropancreatic neuroendocrine tumors. This review presents a clinical practice workflow that has been successful since 177Lu DOTATATE PRRT was approved by the U.S. Food and Drug Administration. The workflow relies heavily on the input of a multidisciplinary team and involves a nuclear medicine consultation service, tumor board, and specific preparations in advance of therapy and day-of-therapy procedures. A systematic checklist designed to ensure appropriate selection of treatment candidates and identification of any concerns to address to safely administer PRRT is provided. All patients were evaluated with gallium 68 DOTATATE PET/CT, and in cases of high-grade tumors, they were also evaluated with fluorine 18 fluorodeoxyglucose PET/CT, with imaging findings reviewed as part of the systematic checklist before PRRT. Adverse effects are discussed and imaging follow-up regimens are reviewed, including alternative diagnostic contrast materials. Approaches to multiple challenging patient scenarios are illustrated through case examples. Finally, alternative theranostic radionuclides and treatment strategies are discussed.

Safety and accuracy of aortic and periaortic CT-guided percutaneous core needle biopsy.

PURPOSE: The purpose of this study was to determine the safety and accuracy of aortic and periaortic computed tomography (CT)-guided percutaneous core needle biopsy performed at a single center over 12 years. MATERIALS AND METHODS: A retrospective review was conducted of cases performed between February 2010 and August 2022 in which the biopsied region was in direct contact with the aorta or great vessels including the pericardium and common iliac arteries. Clinical notes were reviewed for any early or delayed complications following the procedure, which if present were graded using the National Institute of Health's Common Terminology Criteria for Adverse Events, version 5.0. Pathology results were compared to subsequent outside biopsy results or follow-up surgical pathology, if available, as well as subsequent clinical decision making and/or clinical course, to determine concordance. Sensitivity, specificity, predictive value, and accuracy (indicative of diagnostic yield) were calculated. RESULTS: 32 core needle biopsies were reviewed from 30 patients (average lesion longest diameter 3.1 cm, range 0.5-10.9 cm; average needle proximity to the vessel endothelium or deep side of the pericardium 1.0 cm, range 0.3-1.8 cm). Complications occurred in 46.9% of cases (15/32), 93.3% (14/15) of which were minor and included small amounts of bleeding or pain. One patient developed a small nonemergent pneumothorax. Of biopsies obtained, 96.9% provided adequate tissue for diagnosis (31/32). When evaluating concordance between pathological and final diagnosis, sensitivity was 94.7% and specificity was 83.3%; positive and negative predictive value were 90.0% and 90.9%, respectively. Accuracy (diagnostic yield) of biopsy was 90.3%. CONCLUSION: CT-guided percutaneous aortic and periaortic core needle biopsies are safe and efficacious procedures with high diagnostic yield.

PET/MRI for evaluation of patients with pancreatic cancer.

Pancreatic cancers are the third leading cause of cancer-related death in the USA and outcomes remain poor despite improvements in imaging and treatment paradigms. Currently, computed tomography (CT) and magnetic resonance imaging (MRI) are frequently utilized for staging and restaging of these malignancies, but positron emission tomography (PET)/CT can play a role in troubleshooting and improve whole-body staging. PET/MRI is a novel imaging modality that allows for simultaneous acquisition of PET and MRI images, leading to improved image quality and potential increased sensitivity. Early studies suggest that PET/MRI may play a larger role in pancreatic cancer imaging in future. This manuscript will briefly discuss current imaging approaches to pancreatic cancer and outline existing evidence and published data supporting the use of PET/MRI for pancreatic cancers.

Bayesian penalized likelihood PET reconstruction impact on quantitative metrics in diffuse large B-cell lymphoma.

Evaluate the quantitative, subjective (Deauville score [DS]) and reader agreement differences between standard ordered subset expectation maximization (OSEM) and Bayesian penalized likelihood (BPL) positron emission tomography (PET) reconstruction methods. A retrospective review of 104 F-18 fluorodeoxyglucose PET/computed tomography (CT) exams among 52 patients with diffuse large B-cell lymphoma. An unblinded radiologist moderator reviewed both BPL and OSEM PET/CT exams. Four blinded radiologists then reviewed the annotated cases to provide a visual DS for each annotated lesion. Significant (P < .001) differences in BPL and OSEM PET methods were identified with greater standard uptake value (SUV) maximum and SUV mean for BPL. The DS was altered in 25% of cases when BPL and OSEM were reviewed by the same radiologist. Interobserver DS agreement was higher for OSEM (>1 cm lesion = 0.89 and ≤1 cm lesion = 0.84) compared to BPL (>1 cm lesion = 0.85 and ≤1 cm lesion = 0.81). Among the 4 readers, average intraobserver visual DS agreement between OSEM and BPL was 0.67 for lesions >1cm and 0.4 for lesions ≤1 cm. F-18 Fluorodeoxyglucose PET/CT of diffuse large B-cell lymphoma reconstructed with BPL has higher SUV values, altered DSs and reader agreement when compared to OSEM. This report finds volumetric PET measurements such as metabolic tumor volume to be similar between BPL and OSEM PET reconstructions. Efforts such as adoption of European Association Research Ltd accreditation should be made to harmonize PET data with an aim at balancing the need for harmonization and sensitivity for lesion detection.

A Review of Theranostics: Perspectives on Emerging Approaches and Clinical Advancements.

Theranostics is the combination of two approaches-diagnostics and therapeutics-applied for decades in cancer imaging using radiopharmaceuticals or paired radiopharmaceuticals to image and selectively treat various cancers. The clinical use of theranostics has increased in recent years, with U.S. Food and Drug Administration (FDA) approval of lutetium 177 (177Lu) tetraazacyclododecane tetraacetic acid octreotate (DOTATATE) and 177Lu-prostate-specific membrane antigen vector-based radionuclide therapies. The field of theranostics has imminent potential for emerging clinical applications. This article reviews critical areas of active clinical advancement in theranostics, including forthcoming clinical trials advancing FDA-approved and emerging radiopharmaceuticals, approaches to dosimetry calculations, imaging of different radionuclide therapies, expanded indications for currently used theranostic agents to treat a broader array of cancers, and emerging ideas in the field. Keywords: Molecular Imaging, Molecular Imaging-Cancer, Molecular Imaging-Clinical Translation, Molecular Imaging-Target Development, PET/CT, SPECT/CT, Radionuclide Therapy, Dosimetry, Oncology, Radiobiology © RSNA, 2023.

18F-fluorodeoxyglucose PET/Computed Tomography: Head and Neck Salivary Gland Tumors.

Salivary gland tumors (SGTs) are a heterogeneous group of neoplasms arising from the 3 pairs of major salivary glands (parotid, submandibular, and sublingual) or numerous minor salivary glands located throughout the oral cavity. This review discusses the role of PET/computed tomography (CT) in evaluation of SGTs, including staging, restaging, prognostication, and response assessment. 18F-fluorodeoxyglucose (FDG) PET/CT is useful for staging and restaging malignant SGTs and offers important prognostic information in these patients. It is less useful for differentiating benign and malignant SGTs. Non-FDG PET radiotracers, perineural spread, parotid incidentalomas, and interpretative pitfalls are discussed as well.

Epithelioid hemangioendothelioma: evaluation by 18F-FDG PET/CT.

PURPOSE: The purpose of this study was to evaluate the imaging characteristics of epithelioid hemangioendothelioma (EHE) on staging 18F-FDG PET/CT. MATERIALS AND METHODS: An IRB-approved retrospective review was conducted for patients with biopsy-proven EHE who underwent FDG PET/CT at our institution between 2005 and 2019. Patients with a history of surgery, chemotherapy, or radiotherapy prior to PET/CT were excluded. PET/CT exams were analyzed, noting metabolic activity, distribution of involvement, and CT morphologic features. PET/CT findings were correlated with comparative CT and MRI performed within three months. RESULTS: There were 35 patients [21 females, 14 males; average age 55.1±16.9 years (range 15-82 years)]. 18/35 patients (52%) had more than one organ affected on PET/CT. The most common sites were liver [21/35 (60%)], lung [(19/35 (54%)], bone [5/35 (14%)], lymph nodes [4/35 (11%)], and vasculature [4/35 (11%)]. Most patients [30/35, (86%)] presented with multiple lesions. The average largest lesion dimension was 4.0±3.6 cm (range 0.6-15.0 cm). The average SUVmax of the most metabolically active lesion at any site was 5.3±3.3 (range 1.2-17.1), and for bone was 7.9±5.4 (range 3.5-17.1), liver was 5.1±2.1 (range 2.6-10.5), and lung was 3.0±1.9 (range 1.2-8.5). Of patients with pulmonary lesions, 9/19 (47%) showed calcification, and 4/19 (21%) had nodules that were either non FDG-avid or too small for accurate SUV assessment. Of patients with hepatic lesions, 11/21 (52%) demonstrated capsular retraction, and 12/21 (57%) were found to have additional hepatic lesions on contrast-enhanced CT or MRI that were occult on PET/CT. CONCLUSION: EHE demonstrates variable, but most commonly moderate FDG activity on PET/CT. The most common sites of disease are the liver, lungs, and bones, and most patients present with multiple lesions and more than one organ involved. Given the intrinsic metabolic activity and multi-organ involvement, FDG PET/CT represents an attractive modality for EHE evaluation. However, it may be best used in combination with CT or MRI given that EHE pulmonary or hepatic lesions may be missed by PET/CT.

Percutaneous ureteral biopsy: safety and diagnostic yield.

PURPOSE: To evaluate safety and diagnostic yield of percutaneous CT-guided biopsy of extrarenal upper urinary tract lesions. MATERIALS AND METHODS: Retrospective review of our institutional database of image-guided biopsies yielded 44 CT-guided percutaneous biopsies in 44 unique patients that targeted ureteral (30, 68%) or other non-renal upper urinary tract lesions (14, 32%) between January 1, 2000 and May 1, 2017. Indications, pre-biopsy imaging, biopsy technique, peri-procedural antithrombotic use, complications including bleeding defined by Society of Interventional Radiology criteria, pathology results, and subsequent imaging were reviewed up to 3 months after the procedure to evaluate safety and diagnostic yield. RESULTS: Mean patient age was 66 (range 27-88) and 23/44 patients were male. The majority (34/44) of lesions were sampled with an 18-gauge biopsy device via a 17-gauge introducer needle, and the remaining 10/44 lesions were sampled with a 19/20 gauge system. The mean number of core samples obtained was 4 (range 2-10). No major complications occurred. Specifically, no patient developed a urine leak or urinary obstruction. Minor complications occurred in 3/44 (7%) biopsies, all retroperitoneal hemorrhages that did not require transfusion or other intervention. Biopsy was adequate for pathologic examination in 41 of 44 (93%) cases. Among patients undergoing surgical resection, biopsy diagnosis was concordant with surgical pathology in 9/10 (90%) cases and discordant in 1/10 (10%). CONCLUSION: CT-guided percutaneous biopsy of upper urinary tract lesions can be performed safely, with high diagnostic yield, and with a high rate of concordance on subsequent surgical pathology.