High-resolution three­dimensional contrast­enhanced magnetic resonance venography in children: comparison of gadofosveset trisodium with ferumoxytol.

BACKGROUND: Gadofosveset is a gadolinium-based blood pool contrast agent that was approved by the United States Food and Drug Administration in 2008. Its unanticipated withdrawal from production in 2016 created a void in the blood pool agent inventory and highlighted the need for an alternative agent with comparable imaging properties. OBJECTIVE: The purpose of our study is to compare the diagnostic image quality, vascular contrast-to-noise ratio (CNR) and temporal signal characteristics of gadofosveset trisodium and ferumoxytol at similar molar doses for high-resolution, three-dimensional (3-D) magnetic resonance (MR) venography in children. MATERIALS AND METHODS: The medical records and imaging data sets of patients who underwent high-resolution 3-D gadofosveset-enhanced MR venography (GE-MRV) or ferumoxytol-enhanced MR venography (FE-MRV) were retrospectively reviewed. Two groups of 20 pediatric patients (age- and weight-matched with one patient common to both groups; age range: 2 days-15 years) who underwent high-resolution 3-D GE-MRV or FE-MRV at similar molar doses were identified and analyzed. Qualitative analysis of image quality and vessel definition was performed by two blinded pediatric radiologists. Interobserver agreement was assessed with the AC1 (first-order agreement coefficient) statistic. Signal-to-noise ratio (SNR) and CNR of the inferior vena cava and aorta were measured in the steady-state venous phase. Medical records were retrospectively reviewed for any adverse reactions associated with either contrast agent. RESULTS: Measured SNR and CNR of the inferior vena cava were higher for FE-MRV than GE-MRV (P = 0.034 and P < 0.001, respectively). The overall image quality score and individual vessel scores of FE-MRV were equal to or greater than GE-MRV (P = 0.084), with good interobserver agreement (AC1 = 0.657). The venous signal on FE-MRV was stable over the longest interval measured (1 h, 13 min and 46 s), whereas venous signal on GE-MRV showed more variability and earlier loss of signal. No adverse reactions were noted in any patient with either contrast agent. CONCLUSION: Ferumoxytol produces more uniform and stable enhancement throughout the entire venous circulation in children than gadofosveset, offering a wider time window for optimal image acquisition. FE-MRV offers a near-ideal approach to high-resolution venography in children at all levels of anatomical complexity.

High resolution, 3-dimensional Ferumoxytol-enhanced cardiovascular magnetic resonance venography in central venous occlusion.

BACKGROUND: Although cardiovascular magnetic resonance venography (CMRV) is generally regarded as the technique of choice for imaging the central veins, conventional CMRV is not ideal. Gadolinium-based contrast agents (GBCA) are less suited to steady state venous imaging than to first pass arterial imaging and they may be contraindicated in patients with renal impairment where evaluation of venous anatomy is frequently required. We aim to evaluate the diagnostic performance of 3-dimensional (3D) ferumoxytol-enhanced CMRV (FE-CMRV) for suspected central venous occlusion in patients with renal failure and to assess its clinical impact on patient management. METHODS: In this IRB-approved and HIPAA-compliant study, 52 consecutive adult patients (47 years, IQR 32-61; 29 male) with renal impairment and suspected venous occlusion underwent FE-CMRV, following infusion of ferumoxytol. Breath-held, high resolution, 3D steady state FE-CMRV was performed through the chest, abdomen and pelvis. Two blinded reviewers independently scored twenty-one named venous segments for quality and patency. Correlative catheter venography in 14 patients was used as the reference standard for diagnostic accuracy. Retrospective chart review was conducted to determine clinical impact of FE-CMRV. Interobserver agreement was determined using Gwet's AC1 statistic. RESULTS: All patients underwent technically successful FE-CMRV without any adverse events. 99.5% (1033/1038) of venous segments were of diagnostic quality (score ≥ 2/4) with very good interobserver agreement (AC1 = 0.91). Interobserver agreement for venous occlusion was also very good (AC1 = 0.93). The overall accuracy of FE-CMRV compared to catheter venography was perfect (100.0%). No additional imaging was required prior to a clinical management decision in any of the 52 patients. Twenty-four successful and uncomplicated venous interventions were carried out following pre-procedural vascular mapping with FE-CMRV. CONCLUSIONS: 3D FE-CMRV is a practical, accurate and robust technique for high-resolution mapping of central thoracic, abdominal and pelvic veins and can be used to inform image-guided therapy. It may play a pivotal role in the care of patients in whom conventional contrast agents may be contraindicated or ineffective.

High-field MR imaging in pediatric congenital heart disease: initial results.

BACKGROUND: Comprehensive assessment of pediatric congenital heart disease (CHD) at any field strength mandates evaluation of both vascular and dynamic cardiac anatomy for which diagnostic quality contrast-enhanced magnetic resonance angiography (CEMRA) and cardiac cine are crucial. OBJECTIVE: To determine whether high-resolution (HR) CEMRA and steady-state free precession (SSFP) cine can be performed reliably at 3.0 T in children with CHD and to compare the image quality to similar techniques performed at 1.5 T. MATERIALS AND METHODS: Twenty-eight patients with a median age of 5 months and average weight 9.0 ± 7.8 kg with suspected or known CHD were evaluated at 3.0 T. SSFP cine (n = 86 series) and HR-CEMRA (n = 414 named vascular segments) were performed and images were scored for image quality and artifacts. The findings were compared to those of 28 patients with CHD of similar weight who were evaluated at 1.5 T. RESULTS: Overall image quality on HR-CEMRA was rated as excellent or good in 96% (397/414) of vascular segments at 3.0 T (k = 0.49) and in 94% (349/371) of vascular segments at 1.5 T (k = 0.36). Overall image quality of SSFP was rated excellent or good in 91% (78/86) of cine series at 3.0 T (k = 0.55) and in 81% (87/108) at 1.5 T (k = 0.47). Off-resonance artifact was common at both field strengths, varied over the cardiac cycle and was more prevalent at 3.0 T. At 3.0 T, off-resonance dark band artifact on SSFP cine was absent in 3% (3/86), mild in 69% (59/86), moderate in 27% (23/86) and severe in 1% (1/86) of images; at 1.5 T, dark band artifact was absent in 16% (17/108), mild in 69% (75/108), moderate in 12% (13/108) and severe in 3% (3/108) of cine images. The signal-to-noise ratio and contrast-to-noise ratio of both SSFP cine and HR-CEMRA images were significantly higher at 3.0 T than at 1.5 T (P < 0.001). CONCLUSION: Signal-to-noise ratio and contrast-to-noise ratio of high-resolution contrast-enhanced magnetic resonance angiography and SSFP cine were higher at 3.0 T than at 1.5 T. Artifacts on SSFP cine were cardiac phase specific and more prevalent at 3.0 T such that frequency-tuning was required in one-third of exams. In neonates, high spatial resolution CEMRA was highly reliable in defining extracardiac vascular anatomy.

Pediatric cardiovascular interventional devices: effect on CMR images at 1.5 and 3 Tesla.

BACKGROUND: To predict the type and extent of CMR artifacts caused by commonly used pediatric trans-catheter devices at 1.5 T and 3 T as an aid to clinical planning and patient screening. METHODS: Eleven commonly used interventional, catheter-based devices including stents, septal occluders, vascular plugs and embolization coils made from either stainless steel or nitinol were evaluated ex-vivo at both 1.5T and 3T. Pulse sequences and protocols commonly used for cardiovascular magnetic resonance (CMR) were evaluated, including 3D high-resolution MR angiography (MRA), time-resolved MRA, 2D balanced-SSFP cine and 2D phase-contrast gradient echo imaging (GRE). We defined the signal void amplification factor (F) as the ratio of signal void dimension to true device dimension. F1 and F2 were measured in the long axis and short axes respectively of the device. We defined F3 as the maximum extent of the off-resonance dark band artifact on SSFP measured in the B0direction. The effects of field strength, sequence type, orientation, flip angle and phase encode direction were tested. Clinical CMR images in 3 patients with various indwelling devices were reviewed for correlation with the in-vitro findings. RESULTS: F1 and F2 were higher (p<0.05) at 3T than at 1.5T for all sequences except 3D-MRA. Stainless steel devices produced greater off-resonance artifact on SSFP compared to nitinol devices (p<0.05). Artifacts were most severe with the stainless steel Flipper detachable embolization coil (Cook Medical, Bloomington, IN), with F1 and F2 10 times greater than with stainless steel stents. The orientation of stents changed the size of off-resonance artifacts by up to two fold. Sequence type did influence the size of signal void or off-resonance artifact (p<0.05). Varying the flip angle and phase encode direction did not affect image artifact. CONCLUSION: Stainless steel embolization coils render large zones of anatomy uninterpretable, consistent with predictions based on ex-vivo testing. Most other commonly used devices produce only mild artifact ex-vivo and are compatible with diagnostic quality in-vivo studies. Knowledge of ex-vivo device behavior can help predict the technical success or failure of CMR scans and may preempt the performance of costly, futile studies.

Three-phase parathyroid 4-dimensional computed tomography initial experience: inexperienced readers have high accuracy and high interobserver agreement.

OBJECTIVE: Multiphase multidetector contrast-enhanced parathyroid CT (4-dimensional computed tomography [4D-CT]) is an emerging tool for evaluating patients with primary hyperparathyroidism. Our goal was to describe the initial performance of 2 inexperienced readers in interpretation of 4D-CT. METHODS: Twenty-three subjects who received 4D-CT and successful surgical exploration were studied (14 initial and 9 repeat explorations; 15 single-gland disease and 8 multigland disease) A staff neuroradiologist prospectively interpreted all studies, and a neuroradiology fellow retrospectively interpreted all studies; their results were compared with the surgical findings for each side of the neck separately. RESULTS: The prospective readings were 78% accurate overall, 97% accurate in the subset of single-gland disease cases, and 89% accurate in re-exploration cases. There was 91% concordance in interpretation between observers, with κ of 0.83. CONCLUSIONS: Initial results after implementation of 4D-CT show high accuracy of interpretation for inexperienced observers, comparable to published data, and high interobserver agreement.

Technical Feasibility and Safety of Repeated Computed Tomography-Guided Transthoracic Intratumoral Injection of Gene-Modified Cellular Immunotherapy in Metastatic NSCLC.

INTRODUCTION: To assess the technical feasibility and safety of repeated percutaneous computed tomography (CT)-guided transthoracic biopsies and intratumoral injections of gene-modified dendritic cells in metastatic NSCLC. METHODS: A total of 15 patients with 15 NSCLC lesions measuring greater than 1.0 cm underwent two cycles of intratumoral biopsies and CCL21 dendritic cell injections separated by 7 days. All needle placements and injections were done under CT guidance. Clinical and imaging follow-up was done approximately 4 weeks after the first procedure. Safety and feasibility were determined as: (1) safety and feasibility similar to that of single-needle biopsy, and (2) an absence of serious adverse events defined as grade greater than or equal to three according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. RESULTS: A total of 30 percutaneous, transthoracic intratumoral biopsies and injections into the lung cancer were performed, two cycles (at d 0 and 7) received by each patient (311 biopsies and 96 intratumoral injections). All percutaneous cases achieved technical success with respect to needle placement for both biopsy and injection of CCL21 dendritic cells. Only minor complications were observed (grade <3), including pneumothorax (n = 10, 33%) and small postbiopsy hemorrhage (n = 2, 7%). Pneumothorax was moderate (n = 1) or trace (n = 9), with resolution of the moderate pneumothorax after manual aspiration without chest tube placement. No patient required chest tube placement. No other complications or serious adverse effects related to the biopsy or dendritic cell injection were noted. All patients were in stable condition after up to 4 hours in the recovery unit and were discharged home on the same day. No procedure-related complications were observed on imaging or clinical follow-up at 4 weeks. CONCLUSIONS: Repeated percutaneous, transthoracic CT-guided biopsies and intratumoral gene-modified cell-based immunotherapy injections into lung cancers are technically feasible, safe, and reproducible. There were no procedure-related serious (defined as grade ≥3) adverse events.

Comparison of Ferumoxytol-enhanced MR Angiography and CT Angiography for the Detection of Pulmonary Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia: Initial Results.

PURPOSE: To perform a preliminary comparison of the sensitivity and positive predictive value of ferumoxytol-enhanced MR angiography with those of CT angiography for detection of pulmonary arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT). MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Ten patients with pulmonary AVMs who had undergone CT of the chest within 12 months underwent MRI of the chest and abdomen with ferumoxytol at 3.0 T at a dose of 4 mg per kilogram of body weight. Consensus review of MR and CT images assessed the presence and characteristics of pulmonary AVMs, image quality, vessel visibility, and artifact grade. RESULTS: Forty-three AVMs were detected, 13 native and 30 recanalized. Twenty-one AVMs had a feeding artery diameter of greater than 2 mm, of which detection occurred in 19 (at MRI and CT), in two (at MRI only), and zero (at CT only). Twenty-two AVMs had a feeding artery diameter of less than or equal to 2 mm, of which detection occurred in 16 (at MRI and CT), six (at CT only), and zero (at MRI only). For the entire cohort, the sensitivity of ferumoxytol-enhanced MRI using CT as the reference standard was 85.4% (35 of 41), and the positive predictive value was 100% (35 of 35). No significant difference was found between CT and MRI in AVM size, feeding artery and draining vein diameter, and artifact score (P >.05 for all). CONCLUSION: Initial results suggest that ferumoxytol-enhanced MRI is a feasible alternative to CT for detection of pulmonary AVM in HHT, while avoiding repeated exposure to radiation, nephrotoxic contrast material, or gadolinium-based contrast agent.© RSNA, 2020.

Portal Venous Interventions: How to Recognize, Avoid, or Get Out of Trouble in Transjugular Intrahepatic Portosystemic Shunt (TIPS), Balloon Occlusion Sclerosis (ie, BRTO), and Portal Vein Embolization (PVE).

Portal venous interventions comprise a large portion of many Interventional Radiology practices today, and remain some of the more technically challenging cases in one's repertoire of procedures. The patients upon whom these procedures are performed are often critically ill, have decompensated disease, or are burdened with comorbid conditions such that they are poor surgical candidates. This leaves them with few options outside the care of Interventional Radiology. Some portal venous interventions, such as transjugular intrahepatic portosystemic shunt, have an established history of excellent clinical success with numerous technical advancements over the years helping to improve outcomes. Others, like balloon occlusion sclerotherapy or portal venous recanalization, are less well established but are nonetheless invaluable in the treatment of portal venous diseases. The goal of this article is to help dispel some of the anxiety experienced by individuals performing the three main procedures of the portal venous system, namely transjugular intrahepatic portosystemic shunt, balloon-occlusion retrograde transvenous obliteration, and portal vein embolization.

Magnetic Resonance Imaging of Glioma in the Era of Antiangiogenic Therapy.

Since it supplanted computed tomography in the early 1990s, magnetic resonance (MR) imaging has remained the standard tool to evaluate disease status in patients with brain tumors. With the recent adoption of antiangiogenic therapy for gliomas, it has become increasingly clear that leakiness of the blood-brain barrier, the physiologic correlate of contrast enhancement, is affected by a multitude of pathophysiologic processes, not all of which correlate with tumor burden. To address this issue, physiologic imaging including diffusion and perfusion MR imaging has been investigated as an avenue to acquire predictive and prognostic biomarkers useful in the evaluation of high-grade gliomas.

Orbital masses: CT and MRI of common vascular lesions, benign tumors, and malignancies.

A wide variety of space occupying lesions may be encountered in the orbit. CT and MR imaging frequently help confirm the presence of a mass and define its extent. Characteristic imaging features may help distinguish among lesions that have overlapping clinical presentations. This review focuses on some of the common orbital masses. Common vascular lesions that are reviewed include: capillary (infantile) hemangioma, cavernous hemangioma (solitary encapsulated venous-lymphatic malformation), and lymphangioma (venous-lymphatic malformation). Benign tumors that are reviewed include: optic nerve sheath meningioma, schwannoma, and neurofibroma. Malignancies that are reviewed include: lymphoma, metastasis, rhabdomyosarcoma, and optic glioma. Key imaging features that guide radiological diagnosis are discussed and illustrated.