Severe intracranial bleedings during endovascular procedures: outcome of surgically treated patients

A C-arm photon counting CT prototype with volumetric coverage using multi-sweep step-and-shoot acquisitions

Objective.Existing clinical C-arm interventional systems use scintillator-based energy-integrating flat panel detectors (FPDs) to generate cone-beam CT (CBCT) images. Despite its volumetric coverage, FPD-CBCT does not provide sufficient low-contrast detectability desired for certain interventional procedures. The purpose of this work was to develop a C-arm photon counting detector (PCD) CT system with a step-and-shoot data acquisition method to further improve the tomographic imaging performance of interventional systems.Approach.As a proof-of-concept, a cadmium telluride-based 51 cm × 0.6 cm PCD was mounted in front of a FPD in an Artis Zee biplane system. A total of 10 C-arm sweeps (5 forward and 5 backward) were prescribed. A motorized patient table prototype was synchronized with the C-arm system such that it translates the object by a designated distance during the sub-second rest time in between gantry sweeps. To evaluate whether this multi-sweep step-and-shoot acquisition strategy can generate high-quality and volumetric PCD-CT images without geometric distortion artifacts, experiments were performed using physical phantoms, a human cadaver head, and anin vivoswine subject. Comparison with FPD-CT was made under matched narrow beam collimation and radiation dose conditions.Main results.Compared with FPD-CT images, PCD-CT images had lower noise and improved visualization of low-contrast lesion models, as well as improved visibility of small iodinated blood vessels. Fine structures were visualized more clearly by the PCD-CT than the highest-available resolution provided by FPD-CBCT and MDCT. No perceivable geometric distortion artifacts were observed in the multi-planar PCD-CT images.Significance.This work is the first demonstration of the feasibility of high-quality and multi-planar (volumetric) PCD-CT imaging with a rotating C-arm gantry.

Imaging characteristics and endovascular treatment strategy for cerebellar arteriovenous malformations

Cerebellar arteriovenous malformations (CAVMs) have increased probabilities of rupture and bleeding compared with arteriovenous malformations (AVMs) in other locations of the brain. Endovascular treatment (EVT) for CAVMs is difficult; as the angioarchitecture of CAVMs is complex, EVT may be associated with complications, due to the involvement of crucial structures, such as the brainstem. The present study aimed to determine the efficacy of EVT for CAVMS. For this purpose, 33 cases of CAVMs treated with EVT from January, 2015 to January, 2020 were retrospectively analyzed. The 33 patients were aged 8 to 73 years (mean age, 40.4±17.8 years) and 21 were female (63%, 21/33). Rupture and bleeding occurred in 29 patients (87.9%, 29/33). Among the 33 CAVM cases, 15 (45.5%, 15/33) were fed by a single artery, and 18 (54.5%, 18/33) were fed by multiple arteries. In total, 27 patients (81.8%, 27/33) had superficial vein drainage alone. Among the 33 cases, 15 were complicated by 16 aneurysms, including 14 prenidal aneurysms and 2 intranidal aneurysms. Among the 33 cases, the nidus of the CAVM (87.9%, 29/33) was treated with Onyx^™ casting in 29 patients: 8 cases (27.6%, 8/29) had an embolization volume of <1/3 of the nidus, 11 cases had a volume of 1/3-2/3 of the nidus (37.9%, 11/29) and 10 cases had a volume >2/3 of the nidus (34.5%, 10/29). Among the EVT complications, there were 3 cases (9.1%, 3/33) of intraoperative and post-operative bleeding, which resulted in two deaths (on the 1st and 7th days). The length of hospital stay was 10.7±5.4 days. In total, 27 patients (81.7%, 27/33) had a Glasgow Outcome Scale (GOS) score of 5 at discharge. On the whole, the present study demonstrates that overall, EVT is a feasible treatment for CAVM and may be used to obtain acceptable therapeutic effects.

Clinical Presentation, Imaging, and Management of Complications due to Neurointerventional Procedures

Neurointervention is a rapidly evolving and complex field practiced by clinicians with backgrounds ranging from neurosurgery to radiology, neurology, cardiology, and vascular surgery. New devices, techniques, and clinical applications create exciting opportunities for impacting patient care, but also carry the potential for new iatrogenic injuries. Every step of every neurointerventional procedure carries risk, and a thorough appreciation of potential complications is fundamental to maximizing safety. This article presents the most frequent and dangerous iatrogenic injuries, their presentation, identification, prevention, and management.

Hemorrhagic complications after endovascular treatment of cerebral arteriovenous malformations

BACKGROUND AND PURPOSE

Intracranial hemorrhage is the most severe complication of brain arteriovenous malformation treatment. We report our rate of hemorrhagic complications after endovascular treatment and analyze the clinical significance and potential mechanisms, with emphasis on cases of delayed hemorrhage after uneventful embolization.

MATERIALS AND METHODS

During a 10-year period, 846 embolization procedures were performed in 408 patients with brain AVMs. Any cases of hemorrhagic complications were identified and divided into those related or unrelated to a periprocedural arterial tear (during catheter navigation or catheter retrieval). We analyzed the following variables: sex, age, hemorrhagic presentation, Spetzler-Martin grade, size of the AVM, number of embolized pedicles, microcatheter used, type and volume of liquid embolic agent injected, and the presence of a premature venous occlusion. Univariate and multivariate multiple regression analyses were performed to identify risk factors for hemorrhagic complications.

RESULTS

A hemorrhagic complication occurred in 92 (11%) procedures. Forty-four (48%) complications were related to a periprocedural arterial perforation, and 48 (52%) were not. Hemorrhagic complications unrelated to an arterial perforation were located more commonly in the cerebral parenchyma, caused more neurologic deficits, and were associated with worse prognosis than those in the arterial perforation group. Only premature venous occlusion was identified as an independent predictor of hemorrhagic complication in the nonperforation group. Premature venous occlusion was significantly related to the ratio of Onyx volume to nidus diameter.

CONCLUSIONS

Higher injected volume of embolic agent and deposition on the venous outflow before complete occlusion of the AVM may account for severe hemorrhagic complications.

Perioperative stroke

It is increasingly recognized that one can identify a higher risk patient for perioperative stroke. The risk of stroke around the time of operative procedures is fairly substantial and it is recognized that patients initially at risk for vascular events are those most likely to have this risk heightened by invasive procedures. Higher risk patients include those of advanced age and there is a cumulative risk, over time, of coexistent hypertension, atherosclerosis, diabetes mellitus, cardiac disease and clotting disorders. There are a number of possible mechanisms associated with the procedure (e.g., preoperative hypercoagulability, holding of antithrombic therapy at the time of the procedure and cardiac arrhythmia) that can promote a thrombo-embolic event. Examples of these include: direct mechanical trauma to extracranial vessels related to operations on the head and neck; and vascular injury as a consequence of vascular and innovative endovascular procedures affecting the cerebral circulation (e.g., carotid endarterectomy, extracranial or intracranial angioplasty with stenting, and use of the MERCI clot retrieval device), as well as various endovascular methods that have been developed to obliterate cerebral aneurysms and arteriovenous malformations as an alternative to surgical clipping and surgical resection, respectively.

Subarachnoid hyperattenuation on flat panel detector-based conebeam CT immediately after uneventful coil embolization of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

Flat panel detector-based CBCT can provide CT-like images of the brain without transferring patients from the angiography suite to a conventional CT facility. Conventional brain CT after uneventful endovascular treatment sometimes shows focal subarachnoid hyperattenuation with contrast leakage, mimicking SAH. Differentiating this finding from SAH is important for immediate postprocedural medical management. We investigated CBCT for detecting subarachnoid hyperattenuation immediately after coil embolization of unruptured cerebral aneurysms.

MATERIALS AND METHODS

Thirty-six patients with unruptured cerebral aneurysms undergoing CBCT immediately after uncomplicated coil embolization were included. The relationship between the presence of subarachnoid hyperattenuation and total volume of contrast medium injected, aneurysm size and location, and balloon and stent assistance during embolization was investigated. Statistical analyses were performed with the χ(2) test (P < .05).

RESULTS

Nine of the 36 patients (25.0%) showed focal subarachnoid hyperattenuation within the relevant parent artery territory harboring the aneurysm. Subarachnoid hyperattenuation locations included the ipsilateral superior frontal sulcus (n = 5), the bilateral superior frontal sulcus (n = 1), and the ipsilateral superior frontal and precentral sulci (n = 3). Statistically significant differences were observed between the presence of a subarachnoid hyperattenuation and the total volume of contrast medium injected (P < .001) and aneurysm size (P < .05).

CONCLUSIONS

Subarachnoid hyperattenuation can be detected by CBCT immediately after coil embolization for unruptured aneurysms. The increased amounts of contrast medium to be given before CBCT and the specific location of the hyperattenuation may help differentiate benign subarachnoid contrast leakage from SAH.

Clinical evaluation of flat-panel detector compared with multislice computed tomography in 65 patients with acute intracranial hemorrhage: initial results

Object

The goal in this study was to compare flat-panel detector (FD) CT with multislice (MS) CT in the visualization of intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), intraventricular hemorrhage, and external ventricular drains (EVDs) to evaluate the diagnostic quality and limitations of the new FD CT imaging modality.

Methods

Neuroimages obtained in 65 patients, including 24 with EVDs, were reviewed by 2 independent, experienced clinicians. Lesions in all patients were investigated with FD CT and MS CT. The numbers of slices positive for ICH and SAH were counted, and for ICH the diameter and area of the lesion was measured. The positioning of drains was assessed. The presence of ventricular blood was noted. Statistical analysis was performed by calculating the Pearson correlation coefficient (r) to evaluate the level of inter- and intraobserver agreement, and linear regression analysis was done to visualize the results of the numbers of ICH- and SAH-positive slices.

Results

The authors found high interobserver agreement regarding the number of slices with evidence of ICH (r = 0.89 for MS CT, r = 0.78 for FD CT) and SAH (r = 0.88 for MS CT, r = 0.9 for FD CT). Thin layers of blood in the ventricles were not detected on FD CT in 36.4% of cases. Six of 7 perimesencephalic SAHs were not seen on FD CT scans. The EVDs could be assessed with both modalities in 83.3% of cases, but the position of the drain could not be determined with FD CT in 16.7% (4 of 24 cases).

Conclusions

In some respects, FD CT is of limited use for the visualization of intracranial hemorrhage. However, despite limited contrast resolution, ICH and EVDs can be reliably demonstrated. Perimesencephalic SAH and thin layers of blood in the occipital horns may not be detected using FD CT. Further evaluation and improvement of the image quality is necessary before FD CT will provide identical quality in comparison with MS CT.

Metal artifact reduction for clipping and coiling in interventional C-arm CT

BACKGROUND AND PURPOSE

Metallic implants induce massive artifacts in CT images which deteriorate image quality and often superimpose structures of interest. The purpose of this study was to apply and evaluate a dedicated MAR method for neuroradiologic intracranial clips and detachable platinum coiling events. We here report the first clinical results for MAR in FDCT.

MATERIALS AND METHODS

FDCT volume scans of several patients treated with endovascular coiling or intracranial clipping were corrected by using a dedicated FDCT MAR correction algorithm combined with an edge-preserving attenuation-normalization method in the projection space. Corrected and uncorrected images were compared by 2 experienced radiologists and evaluated for several image-quality features.

RESULTS

After application of our algorithm, implant delineation and visibility were highly improved. CT values compared with values in metal artifact-unaffected areas showed good agreement (average correction of 1300 HU). Image noise was reduced overall by 27%. Intracranial hemorrhage in the direct surroundings of the implanted coil or clip material was displayed without worrisome metal artifacts, and our algorithm even allowed diagnosis in areas where extensive information losses were seen. The high spatial resolution provided by FDCT imaging was well preserved.

CONCLUSIONS

Our MAR method provided metal artifact-reduced images in every studied case. It reduced image noise and corrected CT values to levels comparable with images measured without metallic implants. An overall improvement of brain tissue modeling and implant visibility was achieved. MAR in neuroradiologic FDCT imaging is a promising step forward for better image quality and diagnosis in the presence of metallic implants.

Periprocedural bleeding complications of brain AVM embolization with Onyx

The advent of Onyx has provided a new method for neurointerventional therapists to treat brain AVMs. Although some retrospective studies have reported complications for AVM embolization with Onyx, periprocedural bleeding complications with Onyx embolization have not yet been described in detail. The aim of this retrospective study was to analyze the factors of Onyx-related bleeding complications and to find a way to avoid and manage these complications.From January 2003, patients with AVMs recruited in our institution started to be treated by Onyx embolization. From January 2007 to July 2009, 143 consecutive interventions were performed in 126 patients using flow-independent microcatheters and Onyx as embolic agents. Seven patients encountered bleeding complications (5.4% per patients and 4.7% per procedures) during or after the endovascular procedures. Among them, five bleeding episodes occurred during procedures, the other two after procedures. Details of the seven patients' clinical presentations, imaging presentations, speculative reasons and management of these complications were recorded. Follow-up data, including postoperative course, clinical symptoms and duration of follow-up were documented. The five active bleedings discovered in procedures were managed in time, and the patients recovered without any new neurological symptoms compared with preoperation. However, of the two bleeding episodes that occurred after interventional procedures, one was detected half an hour later: the patient was remained comatose two months later after resection of right occipital hematoma; the other who encountered intraventricular and midbrain hemorrhage was treated conservatively and suffered Parinaud syndrome and hemianesthesia.

CONCLUSION

Periprocedural bleeding of AVMs embolization is considered a severe and devastating complication. The clinical course and prognosis of bleeding mostly depends on prompt detection and management. Interventional embolization is an effective method to manage bleeding during procedures, and the detection of risk factors and imaging signs of bleeding is extremely important.