Safety of Catheter Embolization of Pulmonary Arteriovenous Malformations—Evaluation of Possible Cerebrovascular Embolism after Catheter Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia/Osler Disease by Pre- and Post-Interventional DWI

Background. This paper aimed to prospectively evaluate the safety of embolization therapy of pulmonary arteriovenous malformations (PAVMs) for the detection of cerebral infarctions by preand post-interventional MRI. Method One hundred and five patients (male/female = 44/61; mean age 48.6+/−15.8; range 5–86) with pre-diagnosed PAVMs on contrast-enhanced MRA underwent embolization therapy. The number of PAVMs treated in each patient ranged from 1–8 PAVMs. Depending on the size and localization of the feeding arteries, either Nester-Coils or Amplatzer vascular plugs were used for embolization therapy. cMRI was performed immediately before, and at the 4 h and 3-month post-embolization therapy. Detection of peri-interventional cerebral emboli was performed via T2w and DWI sequences using three different b-values, with calculation of ADC maps. Results Embolization did not show any post-/peri-interventional, newly developed ischemic lesions in the brain. Only one patient who underwent re-embolization and was previously treated with tungsten coils that corroded over time showed newly developed, small, diffuse emboli in the post-interventional DWI sequence. This patient already had several episodes of brain emboli before re-treatment due to the corroded coils, and during treatment, when passing the corroded coils, experienced additional small, clinically inconspicuous brain emboli. However, this complication was anticipated but accepted, since the vessel had to be occluded distally. Conclusion Catheter-based embolization of PAVMs is a safe method for treatment and does not result in clinically inconspicuous cerebral ischemia, which was not demonstrated previously

Effectiveness of a Brief Teaching Scenario in a Phantom-Based Learning Model for Students to Achieve Ultrasound-Guided Vascular Access—a Prospective Study

For students, early hands-on experience is very limited and often non-existent during study time. Thus, we aimed to evaluate the progress of inexperienced medical students in successfully establishing an ultrasound-guided vessel access. One brief, condensed single teaching lesson in a prior to post-teaching scenario was performed using an inexpensive, self-made phantom model. In this prospective study, medical students (n = 11) with no experience in ultrasound imaging performed an ultrasound-guided vessel access simulated by a gelatin-based phantom model. Success rates and time of procedures were measured. Afterwards, participants underwent dedicated supervised teaching in a single lesson (duration 30 min) with both theoretical information given and practical training skills shown. Then, every student performed the very same procedure again and results were compared with paired t test. Success rate of guide wire placement rose from 36.4 (4/11) to 100%. Mean number of attempts significantly decreased with 2.5 SD1.3 before and 1.2 SD0.4 after teaching (p < 0.05). Overall time to successful guide wire placement improved from 291 SD8 to 151 SD37 s (p < 0.05). With already limited training time and opportunities available during medical education, short and simple, but highly effective training tools are invaluable. With the help of an inexpensive, self-made gelatin-based phantom model for ultrasound-guided vascular access, medical students demonstrate significantly improved practical puncture skills after only one brief, condensed teaching lesson and thus an important progress with regard to their future clinical routine. The performance of ultrasound-guided vascular access can be highly improved for inexperienced medical students by applying one short teaching session using an inexpensive, self-made phantom model

Diagnostic Performance of a Lower-dose Contrast-Enhanced 4D Dynamic MR Angiography of the Lower Extremities at 3 T Using Multisegmental Time-Resolved Maximum Intensity Projections

Background For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this. Purpose To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent. Study Type Retrospective. Population Forty adult PAD patients yielding 1088 artery segments. Field Strength/Sequence A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images. Assessment DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers. Statistical Tests Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland–Altman-comparison. Results High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3–99.9% (95%-CI)] and specificity 98.5% [95.7–99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2–99.2% (95%-CI)] and specificity 99.1% [96.9–99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71–0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]). Data Conclusion MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature. Evidence Level 3 Technical Efficacy Stage