Preoperative radiosurgery for brain metastases (PREOP-1): A feasibility trial.

Purpose: Preoperative radiosurgery (SRS) of brain metastases (BM) aims to achieve cavity local control with a reduction in leptomeningeal relapse (LMD) and without additional radionecrosis compared to postoperative SRS. We present the final results of a prospective feasibility trial of linac-based stereotactic radiosurgery (SRS) prior to neurosurgical resection of a brain metastasis (PREOP-1). Methods: Eligibility criteria included a BM up to 4 cm in diameter for elective resection. The primary endpoint was the feasibility of delivering linac-based preoperative SRS in all patients prior to anticipated gross tumour resection. Secondary endpoints included rates of LMD, local control and overall survival. Exploratory endpoints were the level of expression of immunological and proliferative markers. Results: Thirteen patients of median age 65 years (range 41-77) were recruited. Twelve patients (92 %) received preoperative radiosurgery and metastasectomy and one patient went directly to surgery and received postoperative SRS, thus the primary endpoint was not met. The median time between referral and preoperative SRS was 6.5 working days (1-10) and from SRS to neurosurgery was 1 day (0-5). The median prescribed dose was 16 Gy (14-19) to a median planning target volume of 12.7 cm3 (5.9-26.1). Five patients completed 12-month follow-up after preoperative SRS without local recurrence or leptomeningeal disease. The patient who received postoperative FSRT developed LMD after six months. There was one transient toxicity (grade 2 alopecia) and nine patients have died from extracranial causes. Patients reported significant improvement in motor weakness at 6 months (P = 0.04). No pattern in changes of marker expression was observed. Conclusion: In patients with large brain metastasis without raised intracranial pressure, linac-based preoperative SRS was feasible in 12/13 patients and safe in 12/12 patients without any surgical delay or intracranial complications.

Implementation of the WHO core components of an infection prevention and control programme in two sub-saharan African acute health-care facilities: a mixed methods study.

BACKGROUND: The coronavirus pandemic again highlighted the need for robust health care facility infection prevention and control (IPC) programmes. WHO guidelines on the core components (CCs) of IPC programmes provides guidance for facilities, but their implementation can be difficult to achieve in resource-limited settings. We aimed to gather evidence on an initial WHO IPC implementation experience using a mixed methods approach. METHODS: A five-day training on the WHO IPC CCs was conducted at two reference acute health care facilities in the Democratic Republic of Congo and Burkina Faso. This was accompanied by a three-part mixed-methods evaluation consisting of a: (1) baseline and follow-up survey of participants' knowledge, attitudes and practices (KAP), (2) qualitative assessment of plenary discussion transcripts and (3) deployment of the WHO IPC assessment framework (IPCAF) tool. Results were analysed descriptively and with a qualitative inductive thematic approach. RESULTS: Twenty-two and twenty-four participants were trained at each facility, respectively. Baseline and follow-up KAP results suggested increases in knowledge related to the necessity of a dedicated IPC focal person and annual evaluations of IPC training although lack of recognition on the importance of including hospital leadership in IPC training and hand hygiene monitoring recommendations remained. Most participants reported rarely attending IPC meetings or participating in IPC action planning although attitudes shifted towards stronger agreement with the feeling of IPC responsibility and importance of an IPC team. A reocurring theme in plenary discussions was related to limited resources as a barrier to IPC implementation, namely lack of reliable water access. However, participants recognised the importance of IPC improvement efforts such as practical IPC training methods or the use of data to improve quality of care. The facilities' IPCAF scores reflected a 'basic/intermediate' IPC implementation level. CONCLUSIONS: The training and mixed methods evaluation revealed initial IPC implementation experiences that could be used to inform stepwise approaches to facility IPC improvement in resource-limited settings. Implementation strategies should consider both global standards such as the WHO IPC CCs and specific local contexts. The early involvement of all relevant stakeholders and parallel efforts to advocate for sufficient resources and health system infrastructure are critical.

Long-Term Outcome of Patients with Spinal Dural Arteriovenous Fistula: The Dilemma of Delayed Diagnosis.

BACKGROUND AND PURPOSE: The impact of various radiologic and clinical features on the long-term outcome in spinal dural arteriovenous fistulas is still unclear; thus, they are the purpose of this study. MATERIALS AND METHODS: We retrospectively analyzed our medical data base for all patients treated for spinal dural arteriovenous fistula in our institution between 2006 and 2016. Patient age, neurologic status at the time of diagnosis, the duration of symptoms from onset to diagnosis, and follow-up information were evaluated. The extent of medullary T2WI hyperintensity, intramedullary contrast enhancement, and elongation of perimedullary veins on MR imaging at the time of diagnosis were additionally analyzed. RESULTS: Data for long-term outcome analysis were available in 40 patients with a mean follow-up of 52 months (median, 50.5 months; range, 3-159 months). The mean age at the time of diagnosis was 69.27 ± 9 years (median, 71 years; range, 53-84 years) with a male predominance (n = 32; 80%). The mean duration of symptoms was 20.2 months (median, 10 months; range, 1-120 months). Shorter duration of symptoms at the time of diagnosis was significantly correlated with better outcome of symptoms (P < .05). CONCLUSIONS: Spinal dural arteriovenous fistulas are characterized by interindividually variable clinical presentations, which make a determination of specific predictors for long-term outcome more difficult. Fast and sufficient diagnosis might result in a better outcome after treatment. The diagnosis of spinal dural arteriovenous fistula remains markedly delayed, reflecting an ongoing lack of knowledge and awareness among treating physicians of this rare-but-serious disease.

Treatment strategy and long-term outcome in patients with deep lumbosacral arteriovenous fistulas. A single center analysis in nineteen patients.

OBJECTIVE: Deep lumbosacral dural arteriovenous fistulas (lsDAVF) are rare and present serious diagnostic and treatment difficulties. In our current analysis we present our treatment strategy and the long-term clinical outcome of nineteen patients with lsDAVF. PATIENTS AND METHODS: We retrospectively analyzed our radiological and medical records for patients presenting with SDAVF between 1990 and 2018 at the University Hospital Aachen. We identified twenty patients with a lsDAVF. All patients were treated surgically. One patient died of pulmonary embolism three months after treatment and was excluded from our outcome analysis. Clinical data at time of admission, discharge, one year after discharge and at the last follow-up were evaluated according to modified Aminoff-Logue disability score (AL-score) for this analysis. RESULTS: Mean age was 65 ±â€¯7 years (median, 67; range, 53-78), sixteen patients (84 %) were male. After surgery, four patients developed a recurrent fistula in the same shunt zone and were re-treated microsurgically. Follow-up data one year after treatment was available in 15 patients. No relevant changes in AL-score were observed within this period. For the long-term follow-up analysis, data of 13 patients were available; 38.5 % of patients developed late functional deterioration. CONCLUSION: In our cohort, patients with deep lumbosacral dural arteriovenous fistula had a higher risk of early recurrence compared to patients with thoracolumbar SDAVF, with a considerable percentage of late functional deterioration. Thus strict clinical and radiologic long-term follow-up examinations are recommended in those patients.

Spinal Epidural Arteriovenous Fistula with Perimedullary Venous Reflux: Clinical and Neuroradiologic Features of an Underestimated Vascular Disorder.

BACKGROUND AND PURPOSE: The purpose of this study was to discuss the clinical and radiologic characteristics of spinal epidural arteriovenous fistulas (SEAVF) and demonstrate their specific angiomorphology in a single-center series. MATERIALS AND METHODS: Thirteen consecutive patients were diagnosed with SEAVF at RWTH Aachen University Hospital between 2006 and 2018 and were included in this study. All patients had MR imaging and DSA before treatment; 10 of these 13 patients received contrast-enhanced MRA (CE-MRA). RESULTS: The mean patient age was 72 ± 8 years. Paraparesis was present in 12 (92%) patients. Sphincter dysfunction and sensory symptoms were observed in 7 (54%) and 6 (46%) patients, respectively. The mean duration of symptoms was 6 ± 8 months. Congestive myelopathy on MR imaging was present in all patients. Prominent arterialized perimedullary veins were demonstrated in only 3 cases. CE-MRA revealed arterialized perimedullary veins and an arterialized epidural pouch in 9/10 (90%) patients, mostly located ventrolaterally. DSA demonstrated a multisegmental extension of the arterialized ventrolateral epidural pouch in 6 (46%) cases. An intradural radicular drainage vein was localized distant from the original fistula point in 3 (23%) patients. CONCLUSIONS: Congestive myelopathy with an acute/subacute clinical course was the dominant finding in spinal epidural arteriovenous fistulas. CE-MRA is a powerful diagnostic tool for identifying arterialized perimedullary veins as well as an arterialized epidural pouch. While arterialized perimedullary veins frequently present with only mild enlargement and elongation in spinal epidural arteriovenous fistulas, the arterialized epidural pouch is frequently located ventrolaterally and may extend over several vertebral levels. DSA remains the criterion standard to precisely visualize a spinal epidural arteriovenous fistula and its intradural radicular drainage vein, which may be located distant from the fistulous point.

Spontaneous Elevation of Blood Pressure After SAH: An Epiphenomenon of Disease Severity and Demand, But Not a Surrogate for Outcome?

BACKGROUND: Spontaneous blood pressure increase is frequently observed after aneurysmal subarachnoid hemorrhage (aSAH). These episodes of spontaneous blood pressure alterations are usually tolerated under the assumption of an endogenous response to maintain cerebral perfusion. The relevance of blood pressure variability and its relationship to disease severity and outcome, however, remain obscure. METHODS: A total of 115 consecutive patients with aSAH were included for this retrospective analysis of a continuously collected data pool. Demographics, initial clinical severity of aSAH (HH°, mFS), treatment modality, clinical course, and outcome (development of DCI, cerebral infarction, and GOS after 3 months) were recorded. Hemodynamic information-recorded automatically with a frequency of 1/15 min-was analyzed for spontaneous blood pressure increase (SBI) and endogenous persistent hypertension (EPH) after exclusion of iatrogenic factors and relevant co-medication. Subgroup analysis included stratification for day 0-3, 4-14, and 14-21. RESULTS: SBI and EPH incidence varied from 17 to 84% depending on detection threshold (15-35 mmHg) and time period under scrutiny. Incidence of blood pressure increase correlated with disease severity upon admission (p < 0.05), but the anticipated association with outcome was not observed. SBI and EPH were more likely to occur between day 4 and 14 (p < 0.001), but only early occurrence (day 0-3) was associated with higher incidence of DCI (p < 0.05). Persistent blood pressure elevation between day 4 and 21 was associated with fewer DCI. However, no influence of spontaneous upregulation on clinical outcome after three months was observed. CONCLUSIONS: Spontaneous hemodynamic upregulation is a frequent phenomenon after aSAH. Our data support the hypothesis that spontaneous blood pressure alterations reflect an endogenous, demand-driven response correlating with disease severity. Early alterations may indicate an aggravated clinical course, while later upregulation in particular-if permitted-does not translate into a higher risk of unfavorable outcome.

Implant-specific follow-up imaging of treated intracranial aneurysms: TOF-MRA vs. metal artifact reduced intravenous flat panel computed tomography angiography (FPCTA).

AIM: To compare the diagnostic quality of time-of-flight magnetic resonance angiography (TOF-MRA) and metal-artefact-reduction (MAR) flat-panel-detector computed tomography angiography (FPCTA) and to determine the imaging technique best suited for evaluation endovascular and surgically treated aneurysms. METHODS: The image quality of TOF-MRA and MAR-FPCTA of 44 intracranial implants (coiling: n=20; clipping: n=15; coiling + stenting: n=9) in a patient cohort of 25 was evaluated by two independent readers. Images obtained using MAR-FPCTA (20 second scan time, 496 projections, intravenous contrast medium administration; Artis Zee, Siemens Healthcare, Forchheim) were compared with TOF-MRA-images (1.5 or 3 T). Nominal data were analysed using McNemar's chi-square test and ordinal variables using the Wilcoxon rank test. RESULTS: Compared to TOF-MRA, MAR-FPCTA was significantly better suited to detect aneurysm remnants and to evaluate parent vessels after clipping (p<0.01). For coil packages >160 mm3, TOF-MRA provided significantly better assessment than MAR-FPCTA (p<0.01). For small coil packages (<160 mm3), no significant difference between TOF-MRA and MAR-FPCTA (p=0.232) was observed. For different clip sizes (cut-off 492 mm3) likewise no significant differences were found. The interobserver comparison showed high interrater agreement. CONCLUSION: MAR-FPCTA is significantly better suited for follow-up examinations of clipped aneurysms, whereas for larger coil packages TOF-MRA is preferable. Smaller coil packages can be analysed using MAR-FPCTA or TOF-MRA.

Clinical and Radiologic Characteristics of Deep Lumbosacral Dural Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: Spinal dural arteriovenous fistulas located in the deep lumbosacral region are rare and the most difficult to diagnose among spinal dural arteriovenous fistulas located elsewhere in the spinal dura. Specific clinical and radiologic features of these fistulas are still inadequately reported and are the subject of this study. MATERIALS AND METHODS: We retrospectively evaluated all data of patients with spinal dural arteriovenous fistulas treated and/or diagnosed in our institution between 1990 and 2017. Twenty patients with deep lumbosacral spinal dural arteriovenous fistulas were included in this study. RESULTS: The most common neurologic findings at the time of admission were paraparesis (85%), sphincter dysfunction (70%), and sensory disturbances (20%). Medullary T2 hyperintensity and contrast enhancement were present in most cases. The filum vein and/or lumbar veins were dilated in 19/20 (95%) patients. Time-resolved contrast-enhanced dynamic MRA indicated a spinal dural arteriovenous fistula at or below the L5 vertebral level in 7/8 (88%) patients who received time-resolved contrast-enhanced dynamic MRA before DSA. A bilateral arterial supply of the fistula was detected via DSA in 5 (25%) patients. CONCLUSIONS: Clinical symptoms caused by deep lumbosacral spinal dural arteriovenous fistulas are comparable with those of spinal dural arteriovenous fistulas at other locations. Medullary congestion in association with an enlargement of the filum vein or other lumbar radicular veins is a characteristic finding in these patients. Spinal time-resolved contrast-enhanced dynamic MRA facilitates the detection of the drainage vein and helps to localize deep lumbosacral-located fistulas with a high sensitivity before DSA. Definite detection of these fistulas remains challenging and requires sufficient visualization of the fistula-supplying arteries and draining veins by conventional spinal angiography.

Temporary Stent-Assisted Coil Embolization as a Treatment Option for Wide-Neck Aneurysms.

BACKGROUND AND PURPOSE: Simple coil embolization is often not a feasible treatment option in wide-neck aneurysms. Stent-assisted coil embolization helps stabilize the coils within the aneurysm. Permanent placement of a stent in an intracranial vessel, however, requires long-term platelet inhibition. Temporary stent-assisted coiling is an alternative technique for the treatment of wide-neck aneurysms. To date, only case reports and small case series have been published. Our purpose was to retrospectively analyze the effectiveness and safety of temporary stent-assisted coiling in a larger cohort. MATERIALS AND METHODS: Research was performed for all patients who had undergone endovascular aneurysm treatment in our institution (University Hospital Aachen) between January 2010 and December 2015. During this period, 355 consecutive patients had undergone endovascular aneurysm treatment. We intended to treat 33 (9.2%) of them with temporary stent-assisted coiling, and they were included in this study. Incidental and acutely ruptured aneurysms were included. RESULTS: Sufficient occlusion was achieved in 97.1% of the cases. In 94%, the stent could be fully recovered. Complications occurred in 5 patients (14.7%), whereas in only 1 case was the complication seen as specific to stent-assisted coiling. CONCLUSIONS: Temporary stent-assisted coiling is an effective technique for the treatment of wide-neck aneurysms. Safety is comparable with that of stent-assisted coiling and coiling with balloon remodeling.

Thermal ablation of a confluent lesion in the porcine kidney with a clinically available MR-HIFU system.

The incidence of small renal masses (SRMs) sized <4 cm has increased over the decades (as co-findings/or due to introduction of cross sectional imaging). Currently, partial nephrectomy (PN) or watchful waiting is advised in these patients. Ultimately, 80-90% of these SRMs require surgical treatment and PN is associated with a 15% complication rate. In this aging population, with possible comorbidities and poor health condition, both PN and watchful waiting are non-ideal treatment options. This resulted in an increased need for early, non-invasive treatment strategies such as MR-guided high intensity focused ultrasound (MR-HIFU). (i) To investigate the feasibility of creating a confluent lesion in the kidney using respiratory-gated MR-HIFU under clinical conditions in a pre-clinical study and (ii) to evaluate the reproducibility of the MR-HIFU ablation strategy. Healthy pigs (n = 10) under general anesthesia were positioned on a clinical MR-HIFU system with integrated cooling. A honeycomb pattern of seven overlapping ablation cells (4 × 4 × 10 mm3, 450 W, <30 s) was ablated successively in the cortex of the porcine kidney. Both MR thermometry and acoustic energy delivery were respiratory gated using a pencil beam navigator on the contralateral kidney. The non-perfused volume (NPV) was visualized after the last sonication by contrast-enhanced (CE) T 1-weighted MR (T 1 w) imaging. Cell viability staining was performed to visualize the extent of necrosis. RESULTS: a median NPV of 0.62 ml was observed on CE-T 1 w images (IQR 0.58-1.57 ml, range 0.33-2.75 ml). Cell viability staining showed a median damaged volume of 0.59 ml (IQR 0.24-1.35 ml, range 0-4.1 ml). Overlooking of the false rib, shivering of the pig, and too large depth combined with a large heat-sink effect resulted in insufficient heating in 4 cases. The NPV and necrosed volume were confluent in all cases in which an ablated volume could be observed. Our results demonstrated the feasibility of creating a confluent volume of ablated kidney cortical tissue in vivo with MR-HIFU on a clinically available system using respiratory gating and near-field cooling and showed its reproducibility.

Interventional Radiology Clinical Practice Guideline Recommendations for Neurovascular Disorders Are Not Based on High-Quality Systematic Reviews.

BACKGROUND: In recent years, clinical practice guidelines have been criticized for biased interpretations of research evidence, and interventional radiology is no exception. PURPOSE: Our aim was to evaluate the methodologic quality and transparency of reporting in systematic reviews used as evidence in interventional radiology clinical practice guidelines for neurovascular disorders from the Society of Interventional Radiology. DATA SOURCES: Our sources were 9 neurovascular disorder clinical practice guidelines from the Society of Interventional Radiology. STUDY SELECTION: We selected 65 systematic reviews and meta-analyses. DATA ANALYSIS: A Measurement Tool to Assess Systematic Reviews (AMSTAR) and Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) tools were used to assess the methodologic quality and reporting transparency of systematic reviews. Radial plots were created on the basis of average scores for PRISMA and AMSTAR items. DATA SYNTHESIS: On the basis of AMSTAR scores, 3 (4.62%) reviews were high-quality, 28 reviews (43.08%) were moderate-quality, and 34 reviews (52.31%) were low-quality, with an average quality score of 3.66 (34.32%; minimum, 0%; maximum, 81.82%). The average PRISMA score was 18.18 (69.41%). LIMITATIONS: We were unable to obtain previous versions for 8 reviews, 7 of which were from the Cochrane Database of Systematic Reviews. CONCLUSIONS: The methodologic quality of systematic reviews needs to be improved. Although reporting clarity was much better than the methodologic quality, it still has room for improvement. The methodologic quality and transparency of reporting did not vary much among clinical practice guidelines. This study can also be applied to other medical specialties to examine the quality of studies used as evidence in their own clinical practice guidelines.

Grading of moyamoya disease allows stratification for postoperative ischemia in bilateral revascularization surgery.

BACKGROUND: Moyamoya disease (MMD) may be graded based on DSA, the presence of ischemia in MRI and cerebrovascular reserve capacity allowing the prediction of ischemic symptoms in patients. Cerebral ischemia represents a severe complication in revascularization surgery. Focusing on different clinical features of hemodynamic impairment, MMD grading may allow prediction of ischemic complications. It was the aim to analyze whether MMD grading stratifies for ischemic complications in revascularization surgery for MMD. METHOD: In 37 MMD patients a bilateral, standardized, one-staged revascularization approach consisting of STA-MCA bypass/encephalomyosynangiosis (EMS) and single EMS on the contralateral hemisphere was performed. Clinical data including DSA, MRI and rCBF (Xenon-CT) studies were assessed and used for grading MMD. All patients were observed on the ICU for at least 24 h and received CT imaging on the first postoperative day and in case of neurological deterioration. Ischemic complications were analyzed until the day of discharge and at 6-month follow-up. RESULTS: Grading of MMD revealed 11 hemispheres (15 %) as grade I, 33 hemispheres (44 %) as grade II and 30 hemispheres (41 %) as grade III. Eight ischemic complications were observed (11 %). MMD grading demonstrated a significant correlation with ischemic complications: 0 complications in grade I, 3 in grade II (9 %) and 5 in grade III hemispheres (16 %; p < 0.05, Fisher's exact test). CONCLUSIONS: The proposed grading system allows to stratify for ischemic complications in MMD patients that receive bilateral, one-staged revascularization surgery. Future studies will have to investigate its use for predicting ischemic complications in other revascularization strategies for MMD.

Cervical arthroplasty with ROTAIO® cervical disc prosthesis: first clinical and radiographic outcome analysis in a multicenter prospective trial.

BACKGROUND: Cervical Disc Arthroplasty (CDA) seems to be an alternative to Anterior Cervical Decompression and Fusion (ACDF) and was developed to minimize the risk of Adjacent Segment Disease (ASD). The ROTAIO Cervical Disc Prosthesis represents a new unconstrained implant with a variable centre of rotation which should enable physiological facet-guided movement. The aim of this current study was to evaluate the clinical outcomes after arthroplasty using ROTAIO Cervical Disc Prosthesis. METHOD: Twenty-seven female and 18 male patients (n = 45) with a mean age of 43.7 ± 7.8 years were prospectively followed up for a maximum of 24 month. Clinical outcomes were assessed by Neck Disability Index (NDI), visual analogue scale (VAS) scores for neck and arm pain, patients´ overall satisfaction and the usage of analgesics. Additionally, radiographic information including ROM of the functional spinal unit (FSU) and signs of adjacent segment disease were recorded. RESULTS: NDI and VAS scores showed significant improvement 6 months after surgery and at last follow-up (p < 0.001). Concerning overall satisfaction 95.7% of the patients showed good to excellent results at the last visit and a significant reduction of analgesic usage was observed (p < 0.001). Radiographic measurements showed a mean increase of ROM up to 8.40° in the treated FSU at last follow-up (p < 0.001). No signs of anterior migration or dislocation of the prosthesis and no subsidence was recorded radiographically. There were no major complications and a low rate of secondary procedures (2.2%). CONCLUSION: In the 24-months follow-up the ROTAIO Cervical Disc Prosthesis provided excellent clinical and radiographical results and seems to be safe and effective for the treatment of symptomatic single-level degenerative disc disease.

Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks.

PURPOSE: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib obstruction leaves only part of the aperture available for energy transmission, conserving total emitted acoustic power, the intensity in the near-field tissues inherently increases after beam shaping. Despite of effective rib sparing, those tissues are therefore subjected to increased risk of thermal damage. In this study, for a number of clinically representative intercostal sonication geometries, modeling clinically available hardware, the effect of beam shaping on both the exposure of the ribs and near-field to acoustic energy was evaluated and the implications for the volumetric ablation rate were addressed. METHODS: A relationship between rib temperature rise and acoustic energy density was established by means of in vivo MR thermometry and simulations of the incident acoustic energy for the corresponding anatomies. This relationship was used for interpretation of rib exposure in subsequent numerical simulations in which rib spacing, focal point placement, and the focal point trajectory were varied. The time required to heat a targeted region to 65 °C was determined without and with the application of beam shaping. The required sonication time was used to calculate the acoustic energy density at the fat-muscle interface and at the surface of the ribs. At the fat-muscle interface, exposure was compared to available literature data and rib exposure was interpreted based on the earlier obtained relation between measured temperature rise and simulated acoustic energy density. To estimate the volumetric ablation rate, the cool-down time between periods of energy exposure was estimated using a time-averaged power limit of 100 kJ/h. RESULTS: At the level of the ribs, the temperature rise-energy density proportionality constant was estimated to be 6.0-7.6 °C/(J/mm(2)). Beam shaping by the geometric shadow method typically reduces the acoustic intensity a factor of 2, considering the 1 cm(2) with the highest exposure. For a 4 mm diameter circular sonication trajectory, the near-field energy limit of 2.5 J/mm(2) was exceeded for all considered geometries. The estimated rib temperature was in all but one (sonication 50 mm behind the ribs, with 15 mm rib spacing and a 4 mm diameter circular sonication trajectory) of the considered scenarios within acceptable limits. For those sonication scenarios where a single sonication is considered safe both in terms of near-field as well as rib heating, volumetric ablation rates in the order of 1 ml/h are estimated. CONCLUSIONS: Intercostal sonication is associated with an increased risk of near-field overheating. This risk is strongly dependent on the considered rib spacing, the placement of the focus behind the ribs, and the selected sonication trajectory. For the hardware under simulation, obstruction by the thoracic cage renders ablations of clinically relevant volumes within a practical time-frame unfeasible in a large part of the liver. Improvements maybe expected from transducer designs with a larger active surface and/or nonlinear sonication strategies.

Performance analysis of a dedicated breast MR-HIFU system for tumor ablation in breast cancer patients.

MR-guided HIFU ablation is a promising technique for the non-invasive treatment of breast cancer. A phase I study was performed to assess the safety and treatment accuracy and precision of MR-HIFU ablation in breast cancer patients (n=10) using a newly developed MR-HIFU platform dedicated to applications in the breast. In this paper a technical analysis of the performance of the dedicated breast MR-HIFU system during breast tumors ablation is described. The main points of investigation were the spatial targeting accuracy and precision of the system and the performance of real-time respiration-corrected MR thermometry.The mean targeting accuracy was in the range of 2.4-2.6 mm, whereas the mean targeting precision was in the range of 1.5-1.8 mm. To correct for respiration-induced magnetic field fluctuations during MR temperature mapping a look-up-table (LUT)-based correction method was used. An optimized procedural sedation protocol in combination with the LUT-based correction method allowed for precise MR thermometry during the ablation procedure (temperature standard deviation <3 °C). No unwanted heating in the near field (i.e. skin) nor in the far field (pectoral muscle) was detected.The newly developed dedicated breast MR-HIFU system allows for safe, accurate and precise ablation of breast tumors.

The bigger, the better? About the size of decompressive hemicraniectomies.

INTRODUCTION: Decompressive hemicraniectomy (DHC) is a treatment option in refractory ICP elevation and malignant infarction. A minimum diameter of 12 cm has been widely accepted as mandatory for effective decompression for ICP control. Complete hemispheric exposure is frequently advocated to further reduce the risk of parenchymal shear stress, hemorrhage and swelling. At the same time, superior efficacy and comparable risk profile of a more extensive decompression have yet to be established. MATERIAL AND METHODS: We reviewed 74 patients with comprehensive clinical data sets undergoing DHC from 2008 to 2013 at our institution. With a minimum threshold of 12 cm in AP diameter being observed in all cases, patients were grouped according to the absolute size of maximum AP diameter (<18 cm, ≥ 18 cm) and surface estimate (<180 cm(2), ≥ 180 cm(2)). Surgical technique, efficacy of ICP control, surgical complications and early clinical course were recorded. RESULTS: Baseline demographics were comparable in both groups. Surgery was effective in relieving or preventing intracranial hypertension in all patients, irrespective of craniectomy size. With smaller craniectomies, immediate surgical and secondary complications such as parenchymal herniation, hemorrhage, or swelling did not occur more frequently. CONCLUSION: Due to the heterogeneity of underlying disease, a conclusion as to effect of craniectomy size on long-term outcome cannot be made based on this study. However, if the obligatory lower threshold of 12 cm for DHC size and decompression to the temporal base are observed, a smaller craniectomy is equally effective in relieving intracranial hypertension. While not inadvertently associated with a more favorable surgical risk profile, it does not increase the risk for early secondary complications such as parenchymal shear stress, hemorrhage and swelling.

Seizures after decompressive hemicraniectomy for ischaemic stroke.

OBJECTIVE: The risk of seizures after malignant middle cerebral artery (MCA) infarction with decompressive hemicraniectomy (DHC) is uncertain. Also unknown is how this complication influences survivors' recovery and quality of life. METHODS: We retrospectively reviewed medical charts of all patients admitted to Harborview Medical Center between 1 January 2002 and 31 June 2011 for space-occupying MCA ischaemic stroke and who underwent DHC. Survivors and their surrogates were invited to participate in a telephone or in-person interview. RESULTS: Fifty-five patients were followed for a median of 311 days (IQR 134-727). Twenty-seven patients (49%) had seizures, 25 (45%) developed epilepsy and 21 (38%) achieved moderate disability or better (modified Rankin Scale score ≤3) by 1 year after stroke onset. The only factor significantly associated with seizure occurrence was male gender. Median time from stroke to first seizure was 222 days, with a cluster of first seizures within weeks after cranioplasty; only two of the first seizures occurred right around the time of stroke onset. Follow-up time was significantly longer for patients with seizures (605 days, IQR 297-882) than for those without (221 days, IQR 104-335). Of the 20 patients interviewed, 12 achieved moderate disability or better, 15 experienced a seizure with 6 indicating the seizure was a major drawback. Regardless, all 20 would have chosen DHC again. CONCLUSIONS: In this case series, patients were at high risk of developing seizures after malignant MCA stroke with DHC, especially after cranioplasty. Assuming these findings are replicated, means should be sought to reduce the occurrence of this complication.

Characterization of direct and indirect cerebral revascularization for the treatment of European patients with moyamoya disease.

BACKGROUND: The best revascularization strategy for moyamoya disease (MMD) remains unknown. Our aim was to characterize angiographic revascularization effects of a bilateral standardized revascularization approach, consisting of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and encephalomyosynangiosis (EMS) on one hemisphere and single EMS on the contralateral hemisphere of each patient, and to compare the effects of both revascularization strategies on cerebral hemodynamics. METHODS: In 30 patients (18 females/12 males, age 8-63 years), standardized revascularization was performed. Digital subtraction angiography was performed preoperatively and at 7 days, 6 months and 12 months postoperatively. STA-MCA and EMS functions were graded I (poor), II (medium) or III (extensive) according to angiographic aspects. In 20 patients, cerebrovascular reserve capacity (CVRC) was assessed pre- and postoperatively (at 12 months) using xenon CT. RESULTS: After 12 months, STA-MCA/EMS function was grade 1 in 40/40%, grade 2 in 27/26%, and grade 3 in 27/10% of hemispheres, respectively. Twelve months after surgery, single EMS showed grade I in 37%, grade II in 27%, and grade III in 20% of hemispheres. Combined revascularization improved CVRC significantly compared to preoperative measurement (preoperative: 16.5 ± 34.6% vs. postoperative: 60.8 ± 64.22%; p < 0.05). Single EMS did not improve CVRC significantly (preoperative: 21.8 ± 35.9% vs. postoperative: 34.8 ± 63.0%; p < 0.05). CONCLUSIONS: Combined and indirect revascularization may be successfully applied in a bilateral standardized approach. STA-MCA/EMS is superior to single EMS in restoring CVRC in adult MMD patients.