Utility of manual venous compression during transvenous Onyx injection for a scalp arteriovenous fistula: illustrative case.

BACKGROUND: When performing transvenous liquid embolization for scalp arteriovenous fistulas, multiple networks of venous drainage could limit effective retrograde penetration of embolic agents into feeding arteries, resulting in incomplete obliteration. A salvage technique to achieve effective Onyx penetration with manual venous compression during transvenous embolization is demonstrated. OBSERVATIONS: A 43-year-old man presented with a progressively enlarging mass on his left temporal scalp that was first noticed approximately 20 years earlier. External carotid artery injection showed two scalp arteriovenous fistulas (AVFs). The patient received endovascular embolization. After successful transarterial obliteration of one AVF, transvenous Onyx embolization was performed for another AVF located in the subcutaneous layer. To avoid unnecessary Onyx migration into multiple venous networks, several coils were put in a venous pouch as a scaffold for the Onyx, and feeding arteries were temporarily occluded. Despite these adjunctive techniques, the Onyx migrated into multiple veins and even toward the orbit without complete fistula obliteration. Thereafter, Onyx was injected under manual compression of venous outlets from the pouch, resulting in complete obliteration. LESSONS: Manual compression of venous outlets can be used as a salvage procedure during transvenous Onyx embolization for a scalp AVF. A surgeon's radiation exposure can be reduced by step-by-step adjunctive procedures.

Superb Microvascular Imaging Ultrasound for Cervical Carotid Artery Stenosis for Prediction of the Development of Microembolic Signals on Transcranial Doppler during Carotid Exposure in Endarterectomy.

INTRODUCTION: During exposure of the carotid arteries, embolism from the surgical site is recognized as a primary cause of neurological deficits or new cerebral ischemic lesions following carotid endarterectomy (CEA), and associations have been reported between histological neovascularization in the carotid plaque and both plaque vulnerability and the development of artery-to-artery embolism. Superb microvascular imaging (SMI) enables accurate visualization of neovessels in the carotid plaque without the use of intravenous contrast. This study aimed to determine whether preoperative SMI ultrasound for cervical carotid artery stenosis predicts the development of microembolic signals (MES) on transcranial Doppler (TCD) during exposure of the carotid arteries in CEA. METHODS: Preoperative cervical carotid artery SMI ultrasound followed by CEA under TCD monitoring of MES in the ipsilateral middle cerebral artery was conducted in 70 patients previously diagnosed with internal carotid artery stenosis (defined as ≥70%). First, observers visually identified intraplaque microvascular flow (IMVF) signals as moving enhancements located near the surface of the carotid plaque within the plaque on SMI ultrasonograms. Next, regions of interest (ROI) were manually placed at the identified IMVF signals (or at arbitrary places within the plaque when no IMVF signals were identified within the carotid plaque) and the carotid lumen, and time-intensity curves of the IMVF signal and lumen ROI were generated. Ten heartbeat cycles of both time-intensity curves were segmented into each heartbeat cycle based on gated electrocardiogram findings and averaged with respect to the IMVF signal and lumen ROI. The difference between the maximum and minimum intensities (ID) was calculated based on the averaged IMVF signal (IDIMVF) and lumen (IDl) curves. Finally, the ratio of IDIMVF to IDl was calculated. RESULTS: MES during exposure of the carotid arteries were detected in 17 patients (24%). The incidence of identification of IMVF signals was significantly greater in patients with MES (94%) than in those without (57%; p = 0.0067). The IDIMVF/IDl ratio was significantly greater in patients with MES (0.108 ± 0.120) than in those without (0.017 ± 0.042; p < 0.0001). The specificity and positive predictive value for the IDIMVF/IDl ratio for prediction of the development of MES were significantly higher than those for the identification of IMVF signals. Logistic regression analysis revealed that only the IDIMVF/IDl ratio was significantly associated with the development of MES (95% CI 101.1-3,628.9; p = 0.0048). CONCLUSION: Preoperative cervical carotid artery SMI ultrasound predicts the development of MES on TCD during exposure of the carotid arteries in CEA.

Resolution of Hypoxic Tissue in Cerebellar Hemispheres After Arterial Bypass Surgery in a Patient With Symptomatic Bilateral Vertebral Artery Occlusion: A 18F-FRP170 PET Study.

A 48-year-old man experienced recurrent vertigo refractory to antiplatelet medications. Cerebral angiography showed occlusion of bilateral vertebral arteries with poor collateral circulation. PET using O2 gas showed reduced blood flow and metabolic rate of oxygen and elevated oxygen extraction fraction in bilateral cerebellar hemispheres. Subsequent F-FRP170 (1-(2-F-fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole) PET, which depicts hypoxic but viable tissue, revealed elevated tracer uptake in the same regions. After superficial temporal artery-posterior cerebral artery anastomosis, O-gas PET showed normalization of blood flow, metabolic rate of oxygen, and oxygen extraction fraction in bilateral cerebellar hemispheres. Abnormally elevated F-FRP-170 uptake was also resolved in those regions.

[123I-Iomazenil Single-Photon Emission Computed Tomography Imaging in a Patient with Mild Traumatic Subdural Hematoma Accompanied by Delayed Transient Aphasia].

Early and late images of 123I-iomazenil(IMZ)single-photon emission computed tomography(SPECT)reflect distributions of cerebral blood flow and those of cortical benzodiazepine receptor binding potential, respectively. Crossed cerebellar diaschisis reflects left-to-right asymmetry of metabolism in the cerebral hemispheres. We present a case of a 67-year-old woman who developed transient aphasia 3 days after the onset of a mild acute subdural hematoma. Computed tomography scan and magnetic resonance imaging during aphasia did not show enlargement of the hematoma or any new lesions. Electroencephalography did not show any abnormalities. Early images of 123I-IMZ SPECT 3 days after the onset of aphasia revealed a decrease in radioactivity in the right cerebellar hemisphere relative to that in the left cerebellar hemisphere. Late images of the same 123I-IMZ SPECT displayed a decrease in radioactivity in the left cerebral hemisphere relative to that in the right cerebral hemisphere. Twenty-four days later, the aphasia disappeared and the left-to-right asymmetries of radioactivity in the cerebellar and cerebral hemispheres on the early and late 123I-IMZ SPECT images also resolved.

Crossed Cerebellar Tracer Uptake on Acute-Stage 123I-Iomazenil SPECT Imaging Predicts 3-Month Functional Outcome in Patients With Nonfatal Hypertensive Putaminal or Thalamic Hemorrhage.

PURPOSE: Whereas SPECT images obtained 180 minutes after administration of I-iomazenil (IMZ) (late images) are proportional to the distribution of central benzodiazepine receptor-binding potential, SPECT images obtained within 30 minutes after I-IMZ administration (early images) correlate with regional brain perfusion. The aim of the present study was to determine whether crossed cerebellar tracer uptake on acute-stage I-IMZ SPECT imaging predicts 3-month functional outcome in patients with nonfatal hypertensive putaminal or thalamic hemorrhage. METHODS: Forty-six patients underwent early and late SPECT imaging with I-IMZ within 7 days after the onset of hemorrhage. A region of interest was automatically placed in the bilateral cerebellar hemispheres using a 3-dimensional stereotaxic region-of-interest template, and the ratio of the value in the cerebellar hemisphere contralateral to the affected side to that in the ipsilateral cerebellar hemisphere (ARcbl) was calculated in each patient. Each patient's physical function was measured using the modified Rankin scale (mRS) score 3 months after onset. RESULTS: The ARcbl on early (ρ = -0.511, P = 0.0003) and late (ρ = -0.714, P < 0.0001) images correlated with the mRS 3 months after the onset of hemorrhage. Multivariate analysis showed that only a low ARcbl in late images was significantly associated with a poor functional outcome (mRS score ≥3 at 3 months after onset) (95% confidence interval, 0.001-0.003; P = 0.0212). CONCLUSIONS: Crossed cerebellar tracer uptake on acute-stage I-IMZ SPECT imaging predicts 3-month functional outcome in patients with nonfatal hypertensive putaminal or thalamic hemorrhage.

Comparison of Three-Dimensional T1-Weighted Magnetic Resonance and Contrast-Enhanced Ultrasound Plaque Images for Severe Stenosis of the Cervical Carotid Artery.

BACKGROUND AND PURPOSE: Magnetic resonance (MR) and contrast-enhanced ultrasound assess characteristics and neovascularization, respectively, of the carotid plaque. The purpose of the present study was to clarify how findings of contrast-enhanced ultrasound plaque imaging are related to those of 3-dimensional (3D) fast spin echo (FSE) T1-weighted MR plaque imaging (WI) in severe stenosis (≥70%) of the cervical carotid artery. METHODS: Fifty-three patients underwent 3D FSE T1-WI and contrast-enhanced ultrasound. For each patient, the averaged contrast ratio on MR (CRMR) was calculated by dividing the averaged internal carotid artery plaque signal intensity by the sternocleidomastoid muscle signal intensity; maximally enhanced intensities on the intraplaque and lumen time-intensity curves were obtained from contrast-enhanced ultrasound data, and the ratio of the maximal intensity of the intraplaque curve to that of the lumen curve was calculated and defined as contrast effect (CEUS). RESULTS: A linear correlation (r = .702; P <.0001) was observed between CRMR and CEUS. Receiver operating characteristic curve analyses to evaluate the ability of the CEUS to differentiate each category of CRMR from the other 2 categories showed that the sensitivity was significantly lower for category II (1.30 ≤ CRMR ≤ 1.60) than for category I (CRMR < 1.30) or III (1.60 < CRMR). The CEUS was lower in plaques with higher CRMR than in those with lower CRMR in a subgroup of category III (P = .0196). CONCLUSION: Findings of contrast-enhanced ultrasound plaque imaging are related to those of 3D FSE T1-WI MR plaque imaging according to the life history of arterial plaque and its neovascularization.

Optimal Brain 99mTc-Ethyl Cysteinate Dimer SPECT Imaging and Analysis to Detect Misery Perfusion on 15O PET Imaging in Patients With Chronic Occlusive Disease of Unilateral Major Cerebral Artery.

PURPOSE: Misery perfusion is defined as marginally sufficient cerebral blood supply relative to cerebral metabolic demand. The aim of the present study was to determine the optimal brain Tc-ethyl cysteinate dimer (ECD) SPECT imaging and analysis to detect misery perfusion on O PET imaging in patients with chronic occlusive disease of unilateral internal carotid or middle cerebral artery (MCA). METHODS: For 97 patients, cerebral blood flow, cerebral metabolic rate of oxygen, and oxygen extraction fraction were measured using O PET; Tc-ECD SPECT was performed using dynamic scanning with a scan duration of 10 minutes each for 50 minutes after tracer administration. A region of interest was placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres in all standardized images using a 3-dimensional stereotaxic region-of-interest template and affected-to-contralateral asymmetry ratio in the MCA territory (ARMCA) and contralateral-to-affected asymmetry ratio in the cerebellar hemisphere (ARcbl) were calculated. RESULTS: The ARMCA or ARcbl on Tc-ECD SPECT with a scan time of 20 to 30 minutes after tracer administration (ARMCA20-30 or ARcbl20-30) was correlated with ARMCA on PET cerebral blood flow (r = 0.654) or ARMCA on PET cerebral metabolic rate of oxygen (r = 0.576), respectively, more strongly than with other scan times. The area under the receiver operating characteristic curve for detecting abnormally elevated ARMCA on PET oxygen extraction fraction was significantly greater for ARcbl20-30/ARMCA20-30 (0.947) than for ARMCA20-30 alone (0.780) (difference between areas, 0.167; P = 0.0001) on Tc-ECD SPECT. CONCLUSIONS: Combination of asymmetries in the cerebellar and cerebral hemispheres on Tc-ECD SPECT in a scan time of 20 to 30 minutes after tracer administration optimally detects misery perfusion in unilateral internal carotid artery or MCA occlusive disease.

Preoperative cervical carotid artery contrast-enhanced ultrasound findings are associated with development of microembolic signals on transcranial Doppler during carotid exposure in endarterectomy.

BACKGROUND AND AIMS: Emboli from the surgical site during exposure of the carotid arteries cause new cerebral ischemic lesions or neurological deficits after carotid endarterectomy (CEA). The purpose of the present study was to determine whether preoperative contrast-enhanced ultrasound findings of the cervical carotid arteries are associated with the development of microembolic signals (MES) on transcranial Doppler, during exposure of the arteries in CEA, and to compare the predictive accuracy of contrast-enhanced ultrasound findings with that of gray-scale median (GSM). METHODS: Seventy patients with internal carotid artery stenosis (≥70%) underwent preoperative cervical carotid artery ultrasound and CEA under transcranial Doppler monitoring of MES in the ipsilateral middle cerebral artery. Maximally enhanced intensities on the intraplaque and lumen time-intensity curves, respectively, were obtained from contrast-enhanced ultrasonography data, and the ratio of the maximal intensity (EIp) of the intraplaque curve to that (EIl) of the lumen curve was calculated. The GSM value of the plaque was also measured. RESULTS: The area under the receiver operating characteristic curve to discriminate between the presence and absence of MES during exposure of the carotid arteries was significantly greater for EIp/EIl than for GSM (p = 0.0108). Multivariate statistical analysis demonstrated that only EIp/EIl was significantly associated with the development of MES during exposure of the carotid arteries (p = 0.0002). CONCLUSIONS: Preoperative contrast-enhanced ultrasound findings of the cervical carotid arteries are associated with development of MES on transcranial Doppler during exposure of the arteries in CEA, and the predictive accuracy of contrast-enhanced ultrasound is greater than that of GSM.

Cerebral Hyperperfusion after Revascularization Inhibits Development of Cerebral Ischemic Lesions Due to Artery-to-Artery Emboli during Carotid Exposure in Endarterectomy for Patients with Preoperative Cerebral Hemodynamic Insufficiency: Revisiting the "Impaired Clearance of Emboli" Concept.

The purpose of the present study was to determine whether cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during exposure of the carotid arteries in carotid endarterectomy (CEA). In patients undergoing CEA for internal carotid artery stenosis (≥70%), cerebral blood flow (CBF) was measured using single-photon emission computed tomography (SPECT) before and immediately after CEA. Microembolic signals (MES) were identified using transcranial Doppler during carotid exposure. Diffusion-weighted magnetic resonance imaging (DWI) was performed within 24 h after surgery. Of 32 patients with a combination of reduced cerebrovascular reactivity to acetazolamide on preoperative brain perfusion SPECT and MES during carotid exposure, 14 (44%) showed cerebral hyperperfusion (defined as postoperative CBF increase ≥100% compared with preoperative values), and 16 (50%) developed DWI-characterized postoperative cerebral ischemic lesions. Postoperative cerebral hyperperfusion was significantly associated with the absence of DWI-characterized postoperative cerebral ischemic lesions (95% confidence interval, 0.001-0.179; p = 0.0009). These data suggest that cerebral hyperperfusion after revascularization inhibits development of cerebral ischemic lesions due to artery-to-artery emboli during carotid exposure in CEA, supporting the "impaired clearance of emboli" concept. Blood pressure elevation following carotid declamping would be effective when embolism not accompanied by cerebral hyperperfusion occurs during CEA.

Preoperative prediction of cerebral hyperperfusion after carotid endarterectomy using middle cerebral artery signal intensity in 1.5-tesla magnetic resonance angiography followed by cerebrovascular reactivity to acetazolamide using brain perfusion single-photon emission computed tomography.

OBJECTIVE: The purpose of the present study was to determine whether the signal intensity of the middle cerebral artery (MCA) on preoperative 1.5-T magnetic resonance angiography (MRA) could identify patients at risk for hyperperfusion following carotid endarterectomy (CEA) as a clinical screening test and whether an additional measurement of preoperative cerebrovascular reactivity (CVR) to acetazolamide on brain perfusion single-photon emission computed tomography (SPECT) could increase the predictive accuracy for the development of hyperperfusion. METHODS: In 301 patients, the signal intensity of the MCA ipsilateral to CEA on MRA was preoperatively graded according to the ability to visualize the MCA. For patients with reduced MCA signal intensity on the MRA study, CVR to acetazolamide was subsequently assessed using brain perfusion SPECT. Cerebral hyperperfusion was determined intraoperatively using transcranial regional cerebral oxygen saturation monitoring with near-infrared spectroscopy. RESULTS: Preoperative reduced MCA signal intensity was significantly associated with the development of cerebral hyperperfusion (95% CI, 1.188-3.965; p = 0.0352). While the sensitivity and negative predictive value were 100% both for the preoperative MCA signal intensity alone and in combination with subsequent preoperative CVR to acetazolamide, the specificity and positive predictive value were significantly greater for the latter than for the former (p < 0.05). CONCLUSIONS: Signal intensity of the MCA on preoperative 1.5-T MRA identifies patients at risk for hyperperfusion following CEA as a clinical screening test. An additional measurement of preoperative CVR to acetazolamide increases the predictive accuracy for the development of hyperperfusion.

Combined measurement of cerebral and cerebellar blood flow on preoperative brain perfusion SPECT imaging predicts development of new cerebral ischemic events after endarterectomy for symptomatic unilateral cervical carotid stenosis.

PURPOSE: The aim of this study was to determine whether the ratio of blood flow contralateral-to-affected asymmetry in the cerebellar hemisphere to blood flow affected-to-contralateral asymmetry in the middle cerebral artery (MCA) territory (AR(cbl)/AR(MCA)) on preoperative brain perfusion SPECT could identify patients at risk for new cerebral ischemic events after carotid endarterectomy (CEA) for symptomatic unilateral cervical carotid stenosis. For the purposes of this study, new cerebral ischemic events included neurological deficits and cerebral ischemic lesions on diffusion-weighted MRI. METHODS: Brain blood flow was assessed using 123I-IMP SPECT in 101 patients. A region of interest was automatically placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres using a 3-dimensional stereotaxic region-of-interest template, and the AR(cbl)/AR(MCA) was calculated. Diffusion-weighted MRI was performed within 3 days before and 24 hours after surgery. Patients were neurologically tested before induction of general anesthesia and after recovery from general anesthesia. RESULTS: New cerebral ischemic events after CEA were observed in 12 patients (12%). Multivariate analysis revealed that only high AR(cbl)/AR(MCA) was significantly associated with the development of new postoperative cerebral ischemic events (95% confidence interval, 1.945-8.452; P = 0.0070). The AR(cbl)/AR(MCA) provided 75% sensitivity, 84% specificity, and 39% positive and 96% negative predictive values in predicting development of new postoperative cerebral ischemic events. CONCLUSIONS: The AR(cbl)/AR(MCA) on preoperative brain perfusion SPECT could identify patients at risk for new cerebral ischemic events after CEA for unilateral cervical carotid stenosis.