Synthetic interpolated DSA for radiation exposure reduction via gamma variate contrast flow modeling: a retrospective cohort study.

BACKGROUND: Digital subtraction angiography (DSA) yields high cumulative radiation dosages (RD) delivered to patients. We present a temporal interpolation of low frame rate angiograms as a method to reduce cumulative RDs. METHODS: Patients undergoing interventional evaluation and treatment of cerebrovascular vasospasm following subarachnoid hemorrhage were retrospectively identified. DSAs containing pre- and post-intervention runs capturing the full arterial, capillary, and venous phases with at least 16 frames each were selected. Frame rate reduction (FRR) of the original DSAs was performed to 50%, 66%, and 75% of the original frame rate. Missing frames were regenerated by sampling a gamma variate model (GVM) fit to the contrast response curves to the reduced data. A formal reader study was performed to assess the diagnostic accuracy of the "synthetic" studies (sDSA) compared to the original DSA. RESULTS: Thirty-eight studies met inclusion criteria (average RD 1,361.9 mGy). Seven were excluded for differing views, magnifications, or motion. GVMs fit to 50%, 66%, and 75% FRR studies demonstrated average voxel errors of 2.0 ± 2.5% (mean ± standard deviation), 6.5 ± 1.5%, and 27 ± 2%, respectively for anteroposterior projections, 2.0 ± 2.2%, 15.0 ± 3.1%, and 14.8 ± 13.0% for lateral projections, respectively. Reconstructions took 0.51 s/study. Reader studies demonstrated an average rating of 12.8 (95% CI 12.3-13.3) for 75% FRR, 12.7 (12.2-13.2) for 66% FRR and 12.0 (11.5-12.5) for 50% FRR using Subjective Image Grading Scale. Kendall's coefficient of concordance resulted in W = 0.506. CONCLUSION: FRR by 75% combined with GVM reconstruction does not compromise diagnostic quality for the assessment of cerebral vasculature. RELEVANCE STATEMENT: Using this novel algorithm, it is possible to reduce the frame rate of DSA by as much as 75%, with a proportional reduction in radiation exposure, without degrading imaging quality. KEY POINTS: • DSA delivers some of the highest doses of radiation to patients. • Frame rate reduction (FRR) was combined with bolus tracking to interpolate intermediate frames. • This technique provided a 75% FRR with preservation of diagnostic utility as graded by a formal reader study for cerebral angiography performed for the evaluation of cerebral vasospasm. • This approach can be applied to other types of angiography studies.

Case report: Transvenous coil embolization of a high-grade Galenic dural arteriovenous fistula.

Introduction: Galenic dural arteriovenous fistulas (dAVFs) are a rare form of dAVF and rarely described in the literature. Their distinct location requires different surgical approaches than dAVFs occurring at the nearby sites of the straight sinus and torcular Herophili, and their high risk of hemorrhage makes these dAVFs very challenging to approach surgically. In this report, we present a unique case of Galenic dAVF. Case description: The patient is a 54-year-old female who presented with a 2-year history of progressive headaches, cognitive decline, and papilledema. A cerebral angiogram demonstrated a complex dAVF to the vein of Galen (VoG). She underwent transarterial embolization with Onyx-18 which resulted in minimal reduction in arterial venous shunting. She subsequently underwent a successful transvenous coil embolization resulting in complete occlusion of dAVF. The patient's postoperative course was complicated by interventricular hemorrhage; however, she had a remarkable clinical recovery with resolution of headaches and improvement in cognitive function. A follow-up angiogram completed 6 months post-embolization demonstrated very mild residual shunting. Conclusion: In the unique case presented here, we demonstrate the efficacy of transvenous embolization via an occluded straight sinus as an alternative therapeutic option to eliminate cortical venous reflux.

Pseudo-Occlusion of the Internal Carotid Artery in Acute Ischemic Stroke: Clinical Outcome after Mechanical Thrombectomy.

Pseudo-occlusion (PO) of the cervical internal carotid artery (cICA) can be caused by distal ICA occlusion. We explored the clinical impact of PO after mechanical thrombectomy (MT). Patients who underwent MT to treat distal ICA occlusions between July 2012 and March 2018 were reviewed. A cICA-PO was defined as when single phase computed tomography angiography (CTA) revealed a gradual decline in contrast above the level of the carotid bulb. We investigated the relationship between a cICA-PO and outcome; we also explored the association between successful recanalization and outcome. Among 71 patients, 40 (56.3%) exhibited cICA-PO and more likely to experience poor outcomes (80.0% vs. 25.8%, P < 0.001), hemorrhagic transformation (32.5% vs. 9.6%, P = 0.01), and a lower rate of successful recanalization (65.0% vs. 90.3%, P = 0.014) than the non-PO group. In binary logistic regression, a cICA-PO was independently associated with a poor outcome (odds ratio, 4.278; 95% CI, 1.080-33.006; P = 0.045). In the cICA-PO group, all patients who failed recanalization (n = 15) experienced poor outcomes, as did 69.2% of patients in whom recanalization was successful (P = 0.018). cICA-POs are common and have worse outcomes than non-PO patients. Patients with cICA-POs are more likely to exhibit poor outcomes after MT, particularly when recanalization fails.

Endovascular intervention of acute ischemic stroke due to occlusion of fetal posterior cerebral artery.

A fetal posterior cerebral artery (FPCA) is an anatomic variant in which the posterior cerebral artery is an embryological derivative of the internal carotid artery. Although most cases of ischemic strokes in patients with FPCAs involve embolic infarcts, emergent large vessel occlusion of a FPCA is extremely rare. We present two cases of successful endovascular intervention for emergent occlusion of a FPCA, one of which is only the second reported case of a mechanical thrombectomy of a FPCA. We review the embryology of FPCA, the controversy regarding its association with cerebral infarcts, and various approaches used in the treatment of such occlusive lesions.

Factors Affecting the Obliteration Rate of Intracranial Aneurysms Treated with a Single Pipeline Embolization Device.

OBJECTIVE: To evaluate the clinical and angiographic outcomes of intracranial aneurysm treatment using a single Pipeline embolization device (PED), and to evaluate the factors affecting aneurysm obliteration rate. METHODS: The demographic characteristics and anatomic features of 58 aneurysms in 47 patients treated with a single PED were reviewed retrospectively. All aneurysms treated with a PED at a single center and with follow-up angiograms for at least 6 months were included in this study. RESULTS: The overall rate of complete and near-complete occlusion was 84% (49 of 58) after a mean follow-up period of 18.3 months. The rate of complete aneurysm obliteration was lower in aneurysms with an arterial branch arising from the aneurysm neck compared with aneurysms without an arterial branch (13% [1 of 8] vs. 68% [34 of 50]; P = 0.0075). The overall rate of complete and near-complete aneurysm occlusion was 90% (45 of 50) in aneurysms without an arterial branch arising from its neck. There were no statistically significant associations between obliteration rate and aneurysm neck width, size, or type, or history of previous coil embolization. CONCLUSIONS: Our data suggest that a single PED is sufficient to induce complete or near-complete obliteration of most aneurysms. The presence of a branching artery arising from the aneurysm neck is highly predictive of incomplete occlusion after treatment with a single PED.

Ruptured Arteriovenous Malformation Presenting with Kernohan's Notch.

AVMs are congenital lesions that predispose patients to intracranial hemorrhage and resultant neurological deficits. These deficits are often focal and due to the presence of local neurologic disruption from hemorrhage in the contralateral cerebral hemisphere. We present a rare case of a patient with ipsilateral neurological deficits due to Kernohan's Notch phenomenon resulting from hemorrhage from an AVM. A 31-year-old woman with seizures underwent MR and angiographic imaging which confirmed an unruptured left parietal AVM. The patient declined treatment and presented with obtundation 4 years later. Imaging revealed an acute left parietal ICH and SDH with significant mass effect. The patient underwent emergent hemicraniectomy and hematoma evacuation. Postoperatively, she made significant improvement and was following commands contralaterally with ipsilateral hemiplegia. MR imaging revealed right Kernohan's Notch. The patient had significant rehabilitation with neurological improvement. She eventually underwent elective embolization followed by subsequent surgical resection and bone replacement. Three years from the initial hemorrhage, the patient had only mild left-sided weakness and ambulates without assistance. A false localizing sign, Kernohan's Notch phenomenon, should be considered in the setting of AVM hemorrhage with paradoxical motor impairment and can be identified through MRI.

Retrograde stent placement for coil embolization of a wide-necked posterior inferior cerebellar artery aneurysm.

Wide-necked aneurysms of the posterior inferior cerebellar artery (PICA) are infrequently encountered in cerebrovascular practice, and endovascular treatment is difficult or impossible even with the use of several neck remodeling techniques. We present the case of a patient with a wide-necked aneurysm of the PICA, which was treated by the retrograde stenting through the contralateral vertebral artery and vertebrobasilar junction with antegrade coil embolization.

IV vs. IA TPA in acute ischemic stroke with CT angiographic evidence of major vessel occlusion: a feasibility study.

BACKGROUND AND AIMS: Studies suggest that stroke patients with thrombus in a major cerebral vessel respond less favorably to intravenous (IV) thrombolysis. The purpose of this study was to test the feasibility of a protocol comparing IV versus intra-arterial (IA) recombinant tissue plasminogen activator (TPA) in an acute ischemic stroke with major vessel occlusion. METHODS: Consecutive ischemic stroke patients presenting <3 h from symptom onset with major vessel occlusion on CT angiogram (CTA) were randomly assigned to IV TPA (per NINDS protocol) or IA TPA (22 mg over 2 h). Demographics, times to presentation and thrombolysis, presenting NIH stroke scale (NIHSS) and 90-day NIHSS, Barthel Index, and modified Rankin Scale were recorded. CT-scans at 24-h were reviewed for presence of hemorrhage. Recanalization was determined by post-procedure MR angiograms, which are obtained the day after thrombolytic therapy. RESULTS: Seven patients (median NIHSS = 16) were randomized to IV (N = 4) or IA (N = 3) TPA. There were no significant differences in the presentation NIHSS, time to presentation, or time to treatment between the two groups. Hemorrhage was noted in one patient in the IA group (asymptomatic) and one patient in the IV group (symptomatic). Recanalization was seen in all patients treated with IA TPA and none treated with IV TPA (P = 0.03, Fisher's Exact test). CONCLUSIONS: We found that it is feasible to conduct a trial comparing IV vs. IA TPA in ischemic stroke patients with major vessel occlusion presenting <3 h from onset. Patients treated with IA TPA showed a trend toward higher rate of recanalization. A larger trial may be designed to test safety and effectiveness of IA TPA in this specific group of stroke patients.

Successful transarterial Guglielmi detachable coil embolization of posttraumatic posterior communicating artery-cavernous sinus fistula: technical note.

OBJECTIVE: Carotid-cavernous fistulae are uncommon but well-documented sequelae of craniofacial trauma. A rare subset may arise from the posterior communicating artery instead of from the carotid artery proper. The presentation is similar to that of carotid-cavernous fistulae, with ocular pain, chemosis, and proptosis being the common symptoms. The first successful transarterial coil embolization of this type of lesion is described. METHODS: A 42-year-old man presented with severe craniocerebral injury, including multiple craniofacial fractures, after an industrial accident. He required emergent craniotomy for an open depressed cranial fracture and epidural hematoma. Six weeks after presentation, the patient began to exhibit progressive chemosis and proptosis. Magnetic resonance imaging revealed findings consistent with a carotid-cavernous fistula. RESULTS: Angiography revealed a fistula between the posterior communicating artery and the cavernous sinus. The origin of the fistula in the posterior communicating artery was successfully obliterated with Guglielmi detachable coiling. Subsequent studies demonstrated no flow through the fistula and good opacification of the ipsilateral posterior cerebral artery by the vertebrobasilar system. CONCLUSION: Posterior communicating artery-cavernous fistulae are a rare sequel of trauma. They may be treated successfully with the use of transarterial coil embolization.

Bilateral congenital absence of the internal carotid artery.

Bilateral congenital absence of the internal carotid artery was incidentally found in an 11-year-old boy. Magnetic resonance imaging showed a normal-appearing brain that was entirely supplied by the vertebrobasilar system, and CT confirmed the absence of the bony carotid canals. Although most reported patients with agenesis of both internal carotid arteries presented with cerebrovascular lesions, this case demonstrates that this rare malformation may be asymptomatic.

Bilateral congenital absence of the internal carotid artery.

Bilateral congenital absence of the internal carotid artery was incidentally found in an 11-year-old boy. Magnetic resonance imaging showed a normal-appearing brain that was entirely supplied by the vertebrobasilar system, and CT confirmed the absence of the bony carotid canals. Although most reported patients with agenesis of both internal carotid arteries presented with cerebrovascular lesions, this case demonstrates that this rare malformation may be asymptomatic.