Felix Güttler

Human birth observed in real-time open magnetic resonance imaging

OBJECTIVE Knowledge about the mechanism of labor is based on assumptions and radiographic studies performed decades ago. The goal of this study was to describe the relationship between the fetus and the pelvis as the fetus travels through the birth canal, using an open magnetic resonance imaging (MRI) scanner. STUDY DESIGN The design of the study used a real-time MRI series during delivery of the fetal head. RESULTS Delivery occurred by progressive head extension. However, extension was a very late movement that was observed when the occiput was in close contact with the inferior margin of the symphysis pubis, occurring simultaneously with gliding downward of the fetal head. CONCLUSION This observational study shows, for the first time, that birth can be analyzed with real-time MRI. MRI technology allows assessment of maternal and fetal anatomy during labor and delivery.

Comparison of four radiofrequency ablation systems at two target volumes in an ex vivo bovine liver model.

PURPOSE We aimed to validate actually achieved macroscopic ablation volumes in relation to calculated target volumes using four different radiofrequency ablation (RFA) systems operated with default settings and protocols for 3 cm and 5 cm target volumes in ex vivo bovine liver. MATERIALS AND METHODS Sixty-four cuboid liver specimens were ablated with four commercially available RFA systems (Radionics Cool-tip, AngioDynamic 1500X, Boston Scientific RF 3000, Celon CelonPower LAB): 16 specimens for each system; eight for 3 cm, and eight for 5 cm. Ablation diameters were measured, volumes were calculated, and RFA times were recorded. RESULTS For the 3 cm target ablation volume, all tested RFA systems exceeded the mathematically calculated volume of 14.14 cm3. For the 3 cm target ablation volume, mean ablation volume and mean ablation time for each RFA system were as follows: 28.5 ± 6.5 cm3, 12.0 ± 0.0 min for Radionics Cool-tip; 17.1 ± 4.9 cm3, 9.36 ± 0.63 min for AngioDynamic 1500X; 29.7 ± 11.7 cm3, 4.60 ± 0.50 min for Boston Scientific RF 3000; and 28.8 ± 7.0 cm3, 20.85 ± 0.86 min for Celon CelonPower LAB. For the 5 cm target ablation volume, Radionics Cool-tip (48.3 ± 9.9 cm3, 12.0 ± 0.0 min) and AngioDynamic 1500X (39.4 ± 16.2 cm3, 19.59 ± 1.13 min) did not reach the mathematically calculated target ablation volume (65.45 cm3), whereas Boston Scientific RF 3000 (71.8 ± 14.5 cm3, 9.15 ± 2.93 min) and Celon CelonPower LAB (93.9 ± 28.1 cm3, 40.21 ± 1.78 min) exceeded it. CONCLUSION While all systems reached the 3 cm target ablation volume, results were variable for the 5 cm target ablation volume. Only Boston Scientific RF 3000 and Celon CelonPower LAB created volumes above the target, whereas Radionics Cool-tip and AngioDynamic 1500X remained below the target volume. For the 3 cm target ablation volume, AngioDynamic 1500X with 21% deviation was closest to the target volume. For the 5 cm target volume Boston Scientific RF 3000 with 10% deviation was closest.

Process mapping of PTA and stent placement in a university hospital interventional radiology department

ObjectiveTo apply the process mapping technique in an interdisciplinary approach in order to visualize, better understand, and efficiently organize percutaneous transluminal angioplasty (PTA) and stent placement procedures in a university hospital’s interventional radiology department.MethodsAfter providing an overview of seven established mapping techniques for medical professionals, the process mapping technique was chosen and applied in an interdisciplinary approach including referrers (physicians, nurses, and other staff in referring departments, e.g., vascular surgery), providers (interventional radiologists, nurses, technicians, and staff of the angiography suite), and specialists of the hospital’s controlling department.ResultsA generally binding and standardized process map was created, describing the entire procedure for a patient in whom the radiological intervention of PTA or stent treatment is contemplated from admission to the department of vascular surgery until discharge after successful treatment. This visualization tool assists in better understanding (especially given natural staff fluctuation over time) and efficiently organizing PTA and stent procedures.ConclusionProcess mapping can be applied for streamlining workflow in healthcare, especially in interdisciplinary settings. By defining exactly what a business entity does, who is responsible, to what standard a process should be completed, and how the success can be assessed, this technique can be used to eliminate waste and inefficiencies from the workplace while providing high-quality goods and services easily, quickly, and inexpensively.Main Messages• Process mapping can be used in a university hospital’s interventional radiology department.• Process mapping can describe the patient’s entire process from admission to PTA/stent placement until discharge.• Process mapping can be used in interdisciplinary teams (e.g., referrers, providers, and controlling specialists).• Process mapping can be used in order to more efficiently organize PTA and stent placement procedures.• Process mapping can assist in better understanding and efficiently organizing procedures in standardized fashion.

Lean manufacturing and Toyota Production System terminology applied to the procurement of vascular stents in interventional radiology

ObjectivesTo apply the economic terminology of lean manufacturing and the Toyota Production System to the procurement of vascular stents in interventional radiology.MethodsThe economic- and process-driven terminology of lean manufacturing and the Toyota Production System is first presented, including information and product flow as well as value stream mapping (VSM), and then applied to an interdisciplinary setting of physicians, nurses and technicians from different medical departments to identify wastes in the process of endovascular stent procurement in interventional radiology.ResultsUsing the so-called seven wastes approach of the Toyota Production System (waste of overproducing, waiting, transport, processing, inventory, motion and waste of defects and spoilage) as well as further waste characteristics (gross waste, process and method waste, and micro waste), wastes in the process of endovascular stent procurement in interventional radiology were identified and eliminated to create an overall smoother process from the procurement as well as from the medical perspective.ConclusionEconomic terminology of lean manufacturing and the Toyota Production System, especially VSM, can be used to visualise and better understand processes in the procurement of vascular stents in interventional radiology from an economic point of view.

Non-invasive ECG-triggered 2D TOF MR angiography of the pelvic and leg arteries in an open 1.0-tesla high-field MRI system in comparison to conventional DSA

Abstract Objectives: A non-contrast-enhanced 2D time-of-flight magnetic resonance angiography (TOF-MRA) protocol was compared with the gold standard of planar digital subtraction angiography (DSA) by calculating correlations of vessel diameters. Methods: A total of 1134 vascular diameters in 81 corresponding sites were prospectively measured by TOF-MRA and DSA in seven patients (four women, three men; mean age, 68 years). For a total of 162 vascular segments per patient, 81 Spearman’s ρ correlation coefficients were calculated, consolidated to 41 due to consideration of symmetry (right/left), and assessed by correlation quality. Results: In the 41 consolidated segments, correlations were good, very good, and excellent in 25 segments (n=10>0.5, n=4>0.7, and n=11>0.8), moderate to poor in seven segments (n=4>0.3 and 0<n=3≤0.3), without in two, inverse in three, and nonmeasurable in four segments. Correlations were best for the main arteries above the knee, and these arteries were most consistently visualized. Conclusion: The TOF-MRA protocol presented here can be performed in an open 1.0-T MRI system in 60–90 min. Visualization is degraded when the target artery leaves the plane orthogonal to the imaging plane (1) or signal yield is poor due to small caliber (2).

Magnetic resonance imaging of the active second stage of labour: Proof of principle

AbstractObjectiveTo prove that magnetic resonance imaging of foetal anatomy during the active second stage of vaginal delivery is feasible.Materials and methodsInitially, five pregnant volunteers around the 30th week of gestation were examined in an open MRI. Based on the findings, one vaginal delivery was acquired under real-time imaging. To monitor the birth status during image acquisition, an MR-compatible wireless cardiotocography (CTG) system was built. Single-shot sequence parameters were optimised to compensate motion artefacts during labour.ResultsSafety requirements to monitor the birth process under real-time MR imaging were met. High-resolution MR images were acquired immediately before and after delivery. In one patient, TSE single-shot cinematic sequences of the active second stage of labour were obtained. All sequences were adapted to tolerate movement of the mother and infant, as well as residual noise from the CTG. Furthermore, the MR imaging during labour showed only minor image artefacts.ConclusionCTG-monitored acquisition of MRI series during the active second stage of delivery is feasible. Image quality should allow various further studies to improve models for birth simulation as well as potential investigation of obstructed labour and obstetric complications.Key Points• The active second stage of obstetric delivery can be followed by MRI. • Wireless cardiotocography allows monitoring of the foetus during MRI. • It has potential applications in evaluation of late obstetric problems.

Evaluation of a MR-quadrupole imaging coil for spinal interventions in a vertical 1.0 T MRI

The in vivo pain treatment was successfully performed with the patient in a prone position. The PD‐weighted TSE with echo time = 10 ms rendered contrast‐to‐noise‐ratio values of 27 ± 10 for needle/fat, 1.6 ± 5 for needle/muscle, and 4 ± 4.7 for needle/nerve tissue. The mean diameter of the needle artifact was 1.2 ± 0.2 mm. In the T1‐weighted gradient echo, the needles artifact diameter was 6 ± 2 mm; the needles contrast‐to‐noise ratio relative to muscle tissue was 4 ± 2, 7.6 ± 1.5 for needle/fat, and 5 ± 1 for needle/nerve tissue. With the PD‐weighted TSE (echo time = 10 ms) and the T1‐weighted gradient echo, the needle was imaged reliably throughout the intervention. The butterfly surface coil is feasible for the guidance of spinal interventions in a prone patient. Magn Reson Med, 2012.

Evaluating fetal head dimension changes during labor using open magnetic resonance imaging.

Abstract Aim: Fetal skull molding is important for the adaptation of the head to the birth canal during vaginal delivery. Importantly, the fetal head must rotate around the maternal symphysis pubis. The goals of this analysis were to observe a human birth in real-time using an open magnetic resonance imaging (MRI) scanner and describe the fetal head configuration during expulsion. Methods: Real-time cinematic MRI series (TSE single-shot sequence, TR 1600 ms, TE 150 ms) were acquired from the midsagittal plane of the maternal pelvis during the active second stage of labor at 37 weeks of gestation. Frame-by-frame analyses were performed to measure the frontooccipital diameter (FOD) and distance from the vertex to the base of the fetal skull. Results: During vaginal delivery in an occiput anterior position, the initial FOD was 10.3 cm. When expulsion began, the fetal skull was deformed and elongated, with the FOD increasing to 10.8 cm and 11.2 cm at crowning. In contrast, the distance from the vertex to the base of the skull was reduced from 6.4 cm to 5.6 cm at expulsion. Conclusions: Fetal head molding is the change in the fetal head due to the forces of labor. The biomechanics of this process are poorly understood. Our visualization of the normal mechanism of late second-stage labor shows that MRI technology can for the first time help define the changes in the diameters of the fetal head during active labor.

Measurement of susceptibility artifacts with histogram-based reference value on magnetic resonance images according to standard ASTM F2119.

Abstract Objective: The standard ASTM F2119 describes a test method for measuring the size of a susceptibility artifact based on the example of a passive implant. A pixel in an image is considered to be a part of an image artifact if the intensity is changed by at least 30% in the presence of a test object, compared to a reference image in which the test object is absent (reference value). The aim of this paper is to simplify and accelerate the test method using a histogram-based reference value. Materials and methods: Four test objects were scanned parallel and perpendicular to the main magnetic field, and the largest susceptibility artifacts were measured using two methods of reference value determination (reference image-based and histogram-based reference value). The results between both methods were compared using the Mann-Whitney U-test. Results: The difference between both reference values was 42.35±23.66. The difference of artifact size was 0.64±0.69 mm. The artifact sizes of both methods did not show significant differences; the p-value of the Mann-Whitney U-test was between 0.710 and 0.521. Conclusions: A standard-conform method for a rapid, objective, and reproducible evaluation of susceptibility artifacts could be implemented. The result of the histogram-based method does not significantly differ from the ASTM-conform method.

Initial experience with imaging of the lower extremity arteries in an open 1.0 Tesla MRI system using the triggered angiography non-contrast-enhanced sequence (TRANCE) compared to digital subtraction angiography (DSA).

Abstract Purpose: The aim of this study was to evaluate the feasibility and validity of arterial lower limb imaging with triggered angiography non-contrast enhanced (TRANCE) in an open MRI at 1.0 Tesla (T) compared to digital subtraction angiography (DSA). Material and methods: ECG-gated, non-contrast-enhanced magnetic resonance angiography (MRA) was performed in a 1.0-T high-field open magnetic resonance imaging (MRI) system which generates a vertical magnetic field. Three acquisition levels were defined (abdominal and pelvic level, arterial segments above the knee and segments below the knee) and a total of 1782 vessel diameter measurements were taken on a total of 11 patients with suspected peripheral arterial occlusive disease (PAOD) (8 men, 3 women; average age 66 years). In each patient, 162 vessel segments (81 each with TRANCE and DSA) were defined and measured. Pearson correlation coefficients were calculated. Results: At the abdominal/pelvic level, all mean values measured with DSA exceeded the mean values obtained with TRANCE. Above the knee, mean vessel diameters were measured smaller in DSA in six, equal in three, and larger in two vessel segments. Below the knee, all measured averages, except for the tibiofibular tract (TFT) measurements, were larger in TRANCE. In total, two small (≤0.3), two moderate (>0.3), 11 good (>0.5), 10 high (>0.7) and 13 very high (>0.8) correlations were obtained. Conclusions: Non-contrast-enhanced imaging of the lower limb arteries using a TRANCE-sequence in a 1.0 T open MRI system is feasible with the protocol presented; however, TRANCE tends to underestimate larger vessels and overestimate smaller vessels compared to DSA.