Imaging of peripheral vascular malformations - current concepts and future perspectives

Vascular Malformations belong to the spectrum of orphan diseases and can involve all segments of the vascular tree: arteries, capillaries, and veins, and similarly the lymphatic vasculature. The classification according to the International Society for the Study of Vascular Anomalies (ISSVA) is of major importance to guide proper treatment. Imaging plays a crucial role to classify vascular malformations according to their dominant vessel type, anatomical extension, and flow pattern. Several imaging concepts including color-coded Duplex ultrasound/contrast-enhanced ultrasound (CDUS/CEUS), 4D computed tomography angiography (CTA), magnetic resonance imaging (MRI) including dynamic contrast-enhanced MR-angiography (DCE-MRA), and conventional arterial and venous angiography are established in the current clinical routine. Besides the very heterogenous phenotypes of vascular malformations, molecular and genetic profiling has recently offered an advanced understanding of the pathogenesis and progression of these lesions. As distinct molecular subtypes may be suitable for targeted therapies, capturing certain patterns by means of molecular imaging could enhance non-invasive diagnostics of vascular malformations. This review provides an overview of subtype-specific imaging and established imaging modalities, as well as future perspectives of novel functional and molecular imaging approaches. We highlight recent pioneering imaging studies including thermography, positron emission tomography (PET), and multispectral optoacoustic tomography (MSOT), which have successfully targeted specific biomarkers of vascular malformations

Percutaneous Sclerotherapy of Venous Malformations of the Hand: A Multicenter Analysis

PURPOSE To evaluate the safety and outcome of percutaneous sclerotherapy for treating venous malformations (VMs) of the hand. MATERIALS AND METHODS A retrospective multicenter trial of 29 patients with VMs primarily affecting the hand, including wrist, carpus, and/or fingers, treated by 81 percutaneous image-guided sclerotherapies using ethanol gel and/or polidocanol was performed. Clinical and imaging findings were assessed to evaluate clinical response, lesion size reduction, and complication rates. Substratification analysis was performed with respect to the Puig's classification, the sclerosing agent, the injected volume of the sclerosant, and to previously performed treatments. RESULTS The mean number of procedures per patient was 2.8 (± 2.2). Last follow-up (mean = 9.2~months) revealed a partial relief of symptoms in 78.9% (15/19), while three patients (15.8%) presented symptom-free and one patient (5.3%) with no improvement. Post-treatment imaging revealed an overall objective response rate of 88.9%. Early post-procedural complications occurred after 5/81 sclerotherapies (6.2%) and were entirely resolved by conservative means. Type of VM (Puig's classification) as well as sclerosing agent had no impact on clinical response (p = 0.85, p = 0.11) or complication rates (p = 0.66, p = 0.69). The complication rates were not associated with the sclerosant volume injected (p = 0.76). In addition, no significant differences in clinical success (p = 0.11) or complication rates (p = 0.89) were detected when comparing patients with history of previous treatments compared to therapy-naive patients. CONCLUSION Percutaneous sclerotherapy is both safe and effective for treating VMs of the hand. Even patients with history of previous treatments benefit from further sclerotherapy showing similar low complication rates to therapy-naive patients. LEVEL OF EVIDENCE Level 4, Retrospective study

Multicentered analysis of percutaneous sclerotherapies in venous malformations of the face

ObjectivesTo evaluate the safety and outcome of image-guided sclerotherapy for treating venous malformations (VMs) of the face.Materials and methodsA multicenter cohort of 68 patients with VMs primarily affecting the face was retrospectively investigated. In total, 142 image-guided sclerotherapies were performed using gelified ethanol and/or polidocanol. Clinical and imaging findings were assessed to evaluate clinical response, lesion size reduction, and complication rates. Sub-analyses of complication rates depending on type and injected volume of the sclerosant as well as of pediatric versus adult patient groups were conducted.ResultsMean number of procedures per patient was 2.1 (±1.7) and mean follow-up consisted of 8.7 months (±6.8 months). Clinical response (n = 58) revealed a partial relief of symptoms in 70.7% (41/58), 13/58 patients (22.4%) presented symptom-free while only 4/58 patients (6.9%) reported no improvement. Post-treatment imaging (n = 52) revealed an overall objective response rate of 86.5% (45/52). The total complication rate was 10.6% (15/142) including 4.2% (7/142) major complications, mostly (14/15, 93.3%) resolved by conservative means. In one case, a mild facial palsy persisted over time. The complication rate in the gelified ethanol subgroup was significantly higher compared to polidocanol and to the combination of both sclerosants (23.5 vs. 6.0 vs. 8.3%, p = 0.01). No significant differences in complications between the pediatric and the adult subgroup were observed (12.1 vs. 9.2%, p = 0.57). Clinical response did not correlate with lesion size reduction on magnetic resonance imaging (MRI).ConclusionImage-guided sclerotherapy is effective for treating VMs of the face. Clinical response is not necessarily associated with size reduction on imaging. Despite the complex anatomy of this location, the procedures are safe for both adults and children

Intraosseous contrast administration for emergency computed tomography: A case-control study.

ObjectiveThe aim of the study was to evaluate the feasibility of intraosseous (i.o.) contrast media injection (CMI) for emergency computed tomography (CT) of severe trauma and the associated image quality compared to intravenous (i.v.) CMI.Materials and methodsThe authors retrospectively analysed objective (contrast-to-noise ratio (CNR)) and subjective (4-point Likert scale) image quality of CTs after i.o. (n = 4, mean age (y) 57.0±11.0) versus i.v. (n = 20, mean age (y) 58.8±4.4) CMI. All patients underwent a native head CT scan, a cerebral CT angiography (CTA) and CTA of the supra-aortic vasculature as well as a chest and abdominal CT scan in the venous phase; one patient with an i.o. access additionally received a CTA of the lower limbs. Electronic patient records have been reviewed to determine i.o. access related complications.ResultsBoth groups were consistent in age, heart rate, scan parameters including the flow rate of the contrast agent, resulting in comparable radiation dose levels. The image noise and CNR had no significant difference between the two groups. Scoring the delineation of the main vessels after i.o. CMI showed no significant difference to the i.v. group. There were no CT or i.o. access related complications observed.ConclusionThe i.o. access is a safe and suitable alternative for emergency CMI in CT. Using established protocols good to very good image quality can be achieved, comparable to i.v. CMI. We show for the first time, that i.o. CMI is also feasible for CTA imaging of the head and neck region as well as of pelvic and leg vessels

Multispectral Optoacoustic Tomography: Intra- and Interobserver Variability Using a Clinical Hybrid Approach

Multispectral optoacoustic tomography (MSOT) represents a new imaging approach revealing functional tissue information without extrinsic contrast agents. Using a clinical combined ultrasound (US)/MSOT device, we investigated the interindividual robustness and impact of intra- and interobserver variability of MSOT values in soft tissue (muscle and subcutaneous fat) of healthy volunteers. Semiquantitative MSOT values for deoxygenated (Hb), oxygenated (HbO2) and total hemoglobin (HbT), as well as oxygen saturation (sO2), were calculated for both forearms in transversal and longitudinal probe orientation (n = 3, 8 measurements per subject). For intraobserver reproducibility, the same examiner investigated three subjects twice. Mean values of left vs. right forearm and transversal vs. longitudinal probe orientation were compared using an unpaired Student’s t test. Bland Altmann plots with 95% limits of agreement for absolute averages and differences were calculated. Intraclass correlation coefficients (ICC 2,k) were computed for three different examiners. We obtained reproducible and consistent MSOT values with small-to-moderate deviation for muscle and subcutaneous fat tissue. Probe orientation and body side had no impact on calculated MSOT values (p > 0.05 each). Intraobserver reproducibility revealed equable mean values with small-to-moderate deviation. For muscular tissue, good ICC was obtained for sO2. Measurements of subcutaneous tissue revealed good-to-excellent ICCs for all calculated values. Thus, in this preliminary study on healthy individuals, clinical MSOT provided consistent and reproducible functional soft tissue characterization, independent on the investigating personnel

Medical imaging training with eye movement modeling examples: A randomized controlled study

To determine whether ultrasound training in which the expert’s eye movements are superimposed to the underlying ultrasound video (eye movement modeling examples; EMMEs) leads to better learner outcomes than traditional eye movement-free instructions. 106 undergraduate medical students were randomized in two groups; 51 students in the EMME group watched 5-min ultrasound examination videos combined with the eye movements of an expert performing the task. The identical videos without the eye movements were shown to 55 students in the control group. Performance and behavioral parameters were compared prepost interventional using ANOVAs. Additionally, cognitive load, and prior knowledge in anatomy were surveyed. After training, the EMME group identified more sonoanatomical structures correctly, and completed the tasks faster than the control group. This effect was partly mediated by a reduction of extraneous cognitive load. Participants with greater prior anatomical knowledge benefited the most from the EMME training. Displaying experts’ eye movements in medical imaging training appears to be an effective way to foster medical interpretation skills of undergraduate medical students. One underlying mechanism might be that practicing with eye movements reduces cognitive load and helps learners activate their prior knowledge.</p