The rupture of an intracranial aneurysm is a serious incident, causing subarachnoid hemorrhage associated with high fatality and morbidity rates. Because the demand for radiologic examinations is ...steadily growing, physician fatigue due to an increased workload is a real concern and may lead to mistaken diagnoses of potentially relevant findings. Our aim was to develop a sufficient system for automated detection of intracranial aneurysms.
In a retrospective study, we established a system for the detection of intracranial aneurysms from 3D TOF-MRA data. The system is based on an open-source neural network, originally developed for segmentation of anatomic structures in medical images. Eighty-five datasets of patients with a total of 115 intracranial aneurysms were used to train the system and evaluate its performance. Manual annotation of aneurysms based on radiologic reports and critical revision of image data served as the reference standard. Sensitivity, false-positives per case, and positive predictive value were determined for different pipelines with modified pre- and postprocessing.
The highest overall sensitivity of our system for the detection of intracranial aneurysms was 90% with a sensitivity of 96% for aneurysms with a diameter of 3-7 mm and 100% for aneurysms of >7 mm. The best location-dependent performance was in the posterior circulation. Pre- and postprocessing sufficiently reduced the number of false-positives.
Our system, based on a deep learning convolutional network, can detect intracranial aneurysms with a high sensitivity from 3D TOF-MRA data.
Large-bore catheters allow mechanical thrombectomy in ischemic stroke by engaging and retrieving clots without additional devices (direct aspiration first-pass technique ADAPT). The purpose of this ...study was to establish a model for minimal catheter diameters needed for ADAPT.
We established a theoretic model for the calculation of minimal catheter diameters needed for ADAPT. We then verified its validity in 28 ADAPT maneuvers in a porcine in vivo model. To account for different mechanical thrombectomy techniques, we factored in ADAPT with/without a hypothetic 0.021-inch microcatheter or 0.014-inch microwire inside the lumen of the aspiration catheter and aspiration with a 60-mL syringe versus an aspiration pump.
According to our calculations, catheters with an inner diameter of >0.040 inch and >0.064 inch, respectively, are needed to be effective in the middle cerebral artery (2.5-mm diameter) or in the internal carotid artery (4 mm) in an average patient. There was a significant correlation between predicted and actual thrombectomy results (
= .010). Our theoretic model had a positive and negative predictive value of 78% and 79%, respectively. Sensitivity and specificity were 88% and 64%, respectively.
Our theoretic model allows estimating the minimal catheter diameters needed for successful mechanical thrombectomy with ADAPT, as demonstrated by the good agreement with our animal experiments. Our model will be helpful to interventionalists in avoiding selecting catheters that are likely too small to be effective.
Purpose
Carotid artery anatomy is thought to influence internal carotid artery access time (ICA-AT) in patients requiring mechanical thrombectomy for acute ischemic stroke. This study investigates ...the association between ICA-AT and carotid anatomy.
Material and methods
Computed tomography angiography (CTA) data of 76 consecutive patients presenting with acute ischemic stroke requiring mechanical thrombectomy for middle cerebral artery or carotid T occlusion were evaluated. The supraaortic extracranial vasculature was analyzed regarding take-off angles and curvature of the affected side. Digital subtraction angiography data were primarily analyzed regarding ICA-AT and secondarily regarding recanalization time and radiographic result.
Results
ICA-AT was significantly influenced by vessel tortuosity. Take-off angle of the left common carotid artery (p = 0.001) and the brachiocephalic trunk (p = 0.002) as well as the tortuosity of the common carotid artery (p = 0.002) had highest impact on ICA-AT. For recanalization time, however, we found only the take-off angle of the left common carotid artery to be of significance (p = 0.020). There was a tendency for ICA-AT to correlate with successful (mTICI ≥ 2 b) revascularization (average time of successful results was 24.3 minutes, of unsuccessful was 35.6 minutes; p = 0.065). Every evaluated segment with less carotid tortuosity showed a carotid AT below 25 minutes.
Conclusion
Supraaortic vessel tortuosity significantly influences ICA-AT in mechanical thrombectomy for an acute large vessel. There furthermore was a trend for lower successful recanalization rates with increasing ICA-AT.
The
Interface Region Imaging Spectrograph
(IRIS) is a NASA small explorer mission that provides high-resolution spectra and images of the Sun in the 133 – 141 nm and 278 – 283 nm wavelength bands. ...The IRIS data are archived in calibrated form and made available to the public within seven days of observing. The calibrations applied to the data include dark correction, scattered light and background correction, flat fielding, geometric distortion correction, and wavelength calibration. In addition, the IRIS team has calibrated the IRIS absolute throughput as a function of wavelength and has been tracking throughput changes over the course of the mission. As a resource for the IRIS data user, this article describes the details of these calibrations as they have evolved over the first few years of the mission. References to online documentation provide access to additional information and future updates.
Midlife obesity affects cognition and increases risk of developing dementia. Recent data suggest that intake of the short chain fatty acid butyrate could improve memory function, and may protect ...against diet-induced obesity by reducing body weight and adiposity.
We examined the impact of a high-fat diet (HFD) followed by intervention with 5% (w/w) dietary butyrate, on metabolism, microbiota, brain function and structure in the low-density-lipoprotein receptor knockout (LDLr-/-) mouse model in mid and late life.
In mid-adult mice, 15 weeks of HFD-induced adiposity, liver fibrosis and neuroinflammation, increased systolic blood pressure and decreased cerebral blood flow, functional connectivity assessed with neuroimaging. The subsequent 2 months butyrate intervention restored these detrimental effects to chow-fed control levels. Both HFD and butyrate intervention decreased variance in fecal microbiota composition. In late-adult mice, HFD showed similar detrimental effects and decreased cerebral white and gray matter integrity, whereas butyrate intervention attenuated only metabolic parameters.
HFD induces detrimental effects in mid- and late-adult mice, which can be attenuated by butyrate intervention. These findings are consistent with reported associations between midlife obesity and cognitive impairment and dementia in humans. We suggest that butyrate may have potential in prevention and treatment of midlife obesity.
Because stroke therapy has changed with the introduction of endovascular stroke treatment as a standard approach, studies on intrahospital causes of death from stroke are no longer up-to-date. The ...purpose of this observational study was to present the causes of death during hospitalization of patients with ischemic stroke who received endovascular stroke treatment, with the focus on a differentiation of curative and secondary palliative treatment.
We studied a total cohort of 1342 patients who received endovascular stroke treatment in a tertiary stroke center (Aachen, Germany) between 2010 and 2020 and analyzed the causes of death in all 326 consecutive deceased patients. We distinguished between curative treatment and a secondary palliative approach and analyzed causes of death and treatment numbers across the years.
In the entire cohort of 326 deceased patients, the most common cause of death was of a cerebrovascular nature (51.5%), followed by pneumonia and sepsis (25.8%) and cardiovascular causes (8.3%). Neurovascular causes constituted 75.8% of reasons for palliation. In the group with a secondary palliative approach, causes of death were neurovascular in 54.0% of patients and pneumonia and sepsis in 26.0% of patients.
Cerebrovascular causes in patients with stroke play a major role in the intrahospital causes of death and reasons for palliation. Considering the large proportion of secondarily palliative-treated patients, reasons for palliation should be considered instead of causes of death to avoid concealment by, for example, life-terminating measures.
Transient cortical blindness (TCB) has been reported as a complication after diagnostic cerebral angiography in 0.3–1% of cases. Our aim was to observe the frequency of TCB after diagnostic cerebral ...angiography over a period of 11 years using only hypo-osmolar, nonionic contrast agents and following a protocol to reduce both the total volume of injected contrast agent and the number of angiography series obtained.
We retrospectively included all 2431 patients who received diagnostic cerebral angiographies at our institution. Primary outcome measure was the occurrence of TCB after diagnostic cerebral angiography, hypothesizing that the occurrence of TBC depends on the volume of contrast agent and angiography of the vertebrobasilary arteries.
Over the analyzed time period of 11 years, we did not observe a single case of TCB following diagnostic cerebral angiography. The median contrast volume used was 100 ml (IQR, 100–200), ranging from 15 ml to 500 ml. In our cohort, 61.5% of patients received a selective catheterization of the vertebrobasilary territory. In 99.8% of angiographies iopamidol was used a contrast agent.
Our results indicate that following to certain aspects of the angiography protocol (using the hypoosmolar, non-ionic contrast agent iopamidol and reducing the number of catheterized vessels and angiography series to a diagnostic minimum) the frequency of transient cortical blindness as a complication of diagnostic cerebral angiography considerably can be very low.
Blood flow should be interrupted during mechanical thrombectomy to prevent embolization of clot fragments. The purpose of our study was to provide a handy overview of the most common aspiration ...devices and to quantify their flow characteristics.
We assessed volumetric flow rates generated by a 60-mL VacLok vacuum pressure syringe, a Pump MAX aspiration pump, and a Dominant Flex suction pump connected to the following: 1) an 8F long sheath, 2) an 8F balloon-guide catheter, 3) an ACE 64 distal aspiration catheter, and 4) an AXS Catalyst 6 Distal Access Catheter. We used a water/glycerol solution, which was kept at a constant temperature of 20°C (viscosity, 3.7 mPa · s).
Aspiration with the syringe and the Dominant Flex suction pump achieved the highest flows, whereas aspiration with the Pump MAX was significantly lower (
< .001). Resistors in the aspiration system (tubing, connectors, and so forth) restricted flows, especially when the resistance of the catheter was small (due to its large diameter) and the connected resistors became the predominant resistance (
< .001). The syringe achieved an average vacuum pressure of -90 kPa, and the resulting flow was constant during almost the entire procedure of filling the syringe.
Sixty-milliliter VacLok vacuum pressure syringes and the Dominant Flex suction pump achieved high and constant flows likely sufficient to reverse blood flow during thrombectomy with an 8F sheath or balloon-guide catheter in the ICA and modern distal aspiration catheters in the MCA. The Pump MAX aspiration pump is dedicated for use with distal aspiration catheters and is unlikely to reverse blood flow in the ICA and MCA without balloon protection.
Radiographic shunt series are still the imaging technique of choice for radiologic evaluation of VP-shunt complications. Radiographic shunt series are associated with high radiation exposure and have ...a low diagnostic performance. Our aim was to investigate the diagnostic performance of whole-body ultra-low-dose CT for detecting mechanical ventriculoperitoneal shunt complications.
This retrospective study included 186 patients (mean age, 54.8 years) who underwent whole-body ultra-low-dose CT (100 kVpeak; reference, 10 mAs). Two radiologists reviewed the images for the presence of ventriculoperitoneal shunt complications, image quality, and diagnostic confidence. On a 5-point Likert scale, readers scored image quality and diagnostic confidence (1 = very low, 5 = very high). Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Radiation dose estimation of whole-body ultra-low-dose CT was calculated and compared with the radiation dose of a radiographic shunt series.
34 patients positive for VP-shunt complications were correctly identified on whole-body ultra-low-dose CT by both readers. No false-positive or -negative cases were recorded by any of the readers, yielding a sensitivity of 100% (95% CI, 87.3%-100%), a specificity of 100% (95% CI, 96.9%-100%), and perfect agreement (κ = 1). Positive and negative predictive values were high at 100%. Shunt-specific image quality and diagnostic confidence were very high (median score, 5; range, 5-5). Interobserver agreement was substantial for image quality (κ = 0.73) and diagnostic confidence (κ = 0.78). The mean radiation dose of whole-body ultra-low-dose CT was significantly lower than the radiation dose of a conventional radiographic shunt series (0.67 SD, 0.4 mSv versus 1.57 SD, 0.6 mSv; 95% CI, 0.79-1.0 mSv;
< .001).
Whole-body ultra-low-dose CT allows detection of ventriculoperitoneal shunt complications with excellent diagnostic accuracy and diagnostic confidence. With concomitant radiation dose reduction on contemporary CT scanners, whole-body ultra-low-dose CT should be considered an alternative to the radiographic shunt series.
Current classifications of cerebral cavernous malformations focus solely on morphologic aspects. Our aim was to provide a morphologic classification that reflects hemorrhage rates.
We retrospectively ...categorized 355 cavernous malformations of 70 children and adolescents according to their morphologic appearance on MR imaging and calculated prospective hemorrhage rates on the basis of survival functions for 255 lesions in 25 patients with a radiologic observation period of >180 days.
Overall, there were 199 MR imaging examinations with 1558 distinct cavernous malformation observations during a cumulative observation period of 1094.2 lesion-years. The mean hemorrhage rate of all 355 cavernous malformations was 4.5% per lesion-year. According to Kaplan-Meier survival models, Zabramski type I and II cavernous malformations had a significantly higher hemorrhage rate than type III and IV lesions. The presence of acute or subacute blood-degradation products was the strongest indicator for an increased hemorrhage risk (P = .036, Cox regression): The mean annual hemorrhage rate and mean hemorrhage-free interval for cavernous malformations with and without signs of acute or subacute blood degradation products were 23.4% and 22.6 months and 3.4% and 27.9 months, respectively. Dot-sized cavernous malformations, visible in T2* and not or barely visible in T1WI and T2WI sequences, had a mean annual hemorrhage rate of 1.3% and a mean hemorrhage-free interval of 37.8 months.
It is possible to predict hemorrhage rates based on the Zabramski classification. Our findings imply a tripartite classification distinguishing lesions with and without acute or subacute blood degradation products and dot-sized cavernous malformations.
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