High-resolution three‑dimensional contrast‑enhanced 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.

Teaching Self-Assessment of Doppler Ultrasound for Bubble Grading in Divers: Learning Curve, Reliability, and Surveying Precision.

BackgroundObserving modern decompression protocols alone cannot fully prevent Diving Accidents especially in repetitive diving. Audio Doppler bubble measurements to estimate supersaturation are done in special professional settings only, being not available for the broad community of sports SCUBA divers. In case SCUBA divers without medical and ultrasound training could learn audio Doppler self-assessment for reliable bubble grading on a stable skill level and with an efficient single teaching intervention, this skill could add significantly to diving safety. MethodsWe taught audio Doppler self-assessment of the subclavian vein and cardiac precordial probe position to 41 divers in a 45-minute standardized training session. Assessment was made of 684 audio Doppler measurements by both the trained divers and a medical professional plus additional 2D-echocardiography as reference. ResultsAll air dives were within normal sports diving limits and decompression bubbles were observable via echocardiography in 32.3% of all measurements. The specificity of audio bubble detection was 96.1% but the sensitivity was low for lower bubble grades, increasing to 25%, 35% and 67% for higher echo-detected bubble grades 3, 4 and 5. The number of attempts to achieve a reliable venous signal within 30 seconds was 13 at the subclavian position and 18 at the precordial position. More bubble positive measurements could be detected at the precordial position for both self and medical professional assessment. The performance level of the taught skill remained stable over six months without further practice.ConclusionAudio Doppler self-assessment can be learned by people without medical and ultrasound training and a reliable venous signal can be achieved after a comparably steep learning curve. However, accurate bubble grading is not possible using audio Doppler as only higher bubble grades can be detected. Nevertheless, this qualitative finding can be important in self-evaluating decompression stress and potentially help the diver to judge on measures for avoiding decompression accidents.

Teaching Self-Assessment of Doppler Ultrasound for Bubble Grading in Divers: Learning Curve, Reliability, and Surveying Precision.

BackgroundAudio Doppler bubble measurements of SCUBA divers are done in special professional settings to estimate supersaturation and avoid decompression accidents. However, it is unknown whether sports SCUBA divers without medical and ultrasound training can learn audio Doppler self-assessment for reliable bubble grading with a single teaching intervention. Further, it is unknown whether they are able to establish a stable practical skill level after that teaching intervention in order to allow appropriate judgment on decompression stress.MethodsWe taught audio Doppler self-assessment of the subclavian vein and cardiac precordial probe position to 41 divers in a 45-minute standardized training session. Assessment was made of 684 audio Doppler measurements by both the trained divers and a medical professional plus additional 2D-echocardiography as reference. ResultsAll air dives were within normal sports diving limits and decompression bubbles were observable via echocardiography in 32.3% of all measurements. The specificity of audio bubble detection was 96.1% but the sensitivity was low for lower bubble grades, increasing to 25%, 35% and 67% for higher echo-detected bubble grades 3, 4 and 5. The number of attempts to achieve a reliable venous signal within 30 seconds was 13 at the subclavian position and 18 at the precordial position. More bubble positive measurements could be detected at the precordial position for both self and medical professional assessment. The performance level of the taught skill remained stable over six months without further practice.ConclusionAudio Doppler self-assessment can be learned by people without medical and ultrasound training and a reliable venous signal can be achieved after a comparably steep learning curve. However, accurate bubble grading is not possible using audio Doppler as only higher bubble grades can be detected. However, this qualitative finding can be important in self-evaluating decompression stress and potentially help the diver to judge on measures for avoiding decompression accidents.

Changes to Venous Flow Coupler Signal during DIEP Flap Inset Can Be Predictive of Poor Clinical Outcomes in Autologous Breast Reconstruction

Background Venous flow couplers are typically used to monitor free flaps during the postoperative period, with a continuous venous signal available immediately after completion of the anastomosis. Intraoperative loss of the coupler signal is not uncommon and may require adjustments in free flap inset and even flap thickness to get the venous signal to return. The effects of intraoperative coupler signal loss and the role of this technology on flap outcomes have not been evaluated. We hypothesized that the use of intraoperative coupler can be protective of both early and late flap complications by preventing unfavorable flap insets. Patients and Methods All patients who underwent free flap breast reconstruction between January 2018 and June 2019 by single microsurgery team were included. Flap inset and inset changes based on flow coupler signal problems were reviewed in the procedure notes. Patient demographics data and clinical outcomes were analyzed with comprehensive chart review. Results Forty-four consecutive patients with 69 free flaps were identified. There were no significant differences in patient characteristics or venous coupler size used in venous anastomosis. Although the number of operating room take backs for venous insufficiency was not significantly different between two groups, the free flaps with inset change had significantly higher complications that required later surgical intervention (p = 0.0464). Conclusion Surgeons should be aware that intraoperative coupler signal loss can be associated with poor clinical outcomes postoperatively and these flaps may require more perfusion imaging, flap debulking, or even additional venous anastomosis.

Preliminary evidence for cerebral capillary shunting in adults with sickle cell anemia

Elevated flow velocities in adults with sickle cell anemia (SCA) may cause rapid erythrocyte transit through capillaries. This phenomenon could present as dural venous sinus hyperintensity on arterial spin labeling (ASL)-MRI and could be indicative of capillary shunting. Here, the prevalence of ASL venous hyperintensities and association with relevant physiology in adults with SCA was investigated. SCA ( n = 46) and age-matched control ( n = 16) volunteers were recruited for 3.0 T MRI. Pseudo-continuous ASL-MRI was acquired for cerebral blood flow (CBF) calculation and venous hyperintensity determination; venous signal intensity and a categorical venous score (three raters; 0 = no hyperintensity, 1 = focal hyperintensity, and 2 = diffuse hyperintensity) were recorded. Flow velocity in cervical internal carotid artery segments was determined from phase contrast data (venc = 40 cm/s) and whole-brain oxygen extraction fraction (OEF) was determined from T2-relaxation-under-spin-tagging MRI. Cerebral metabolic rate of oxygen was calculated as the product of OEF, CBF, and blood oxygen content. ASL venous hyperintensities were significantly ( p < 0.001) more prevalent in SCA (65%) relative to control (6%) participants and were associated with elevated flow velocities ( p = 0.03). CBF ( p < 0.001), but not OEF, increased with increasing hyperintensity score. Prospective trials that evaluate this construct as a possible marker of impaired oxygen delivery and stroke risk may be warranted.