Objective: CT perfusion (CTP) provides various hemodynamic parameters. However, it is unclear which CTP parameters are useful in predicting clinical outcome in patients with acute ischemic stroke (AIS).

Methods: Between February 2019 and June 2021, patients with anterior circulation large-vessel occlusion who achieved successful recanalization within 8 hours after stroke onset were included. The relative CTP parameter values analyzed by the reformulated singular value decomposition (SVD) method in the affected middle cerebral artery territories compared to those in the unaffected side were calculated. In addition, the ischemic core volume (ICV) was evaluated using a Bayesian Vitrea. The final infarct volume (FIV) was assessed by 24-hour MRI. The correlation between these CTP-derived values and clinical outcome was assessed.

Results: Forty-two patients were analyzed. Among the CTP-related parameters, the ICV, relative cerebral blood volume (rCBV), and relative mean transit time (rMTT) showed a strong correlation with the FIV (ρ = 0.74, p <0.0001; ρ = −0.67, p <0.0001; and ρ = −0.66, p <0.0001, respectively). In multivariate analysis, rCBV, rMTT, and ICV were significantly associated with good functional outcome, which was defined as a modified Rankin Scale score ≤2 (OR, 6.87 [95% CI, 1.20–39.30], p = 0.0303; OR, 11.27 [95% CI, 0.97–130.94], p = 0.0269; and OR, 36.22 [95% CI, 2.78–471.18], p = 0.0061, respectively).

Conclusions: Among the CTP parameters analyzed by the SVD deconvolution algorithms, rCBV and rMTT could be useful imaging predictors of response to recanalization in patients with AIS, and the performances of these variables were similar to that of the ICV calculated by the Bayesian Vitrea.

Objective: Neuroendovascular treatments are less invasive than surgical clipping. However, the number of fluoroscopy runs may be greater when a contrast medium is used than when routine angiography is performed. Several recent studies have suggested that an iodinated contrast medium causes an increase in the radiation dose. Therefore, it is clinically important to identify physical factors causing amplification of the radiation dose. The purpose of this study was to investigate how dilution of a contrast medium with water influences the amplification effect of the radiation dose using simulation analysis.

Methods: Three different types of commercially available contrast media, namely, iopamidol, iohexol, and iodixanol, were diluted 1.7–3.3 times with water and placed in the left brain parenchyma of a numerical brain phantom. Using the Monte Carlo simulation method, the phantom was exposed to X-ray beams under constant exposure conditions, and the energy absorbed in the entire region of the left brain parenchyma was estimated. At the same time, the content and volume of a contrast medium in the cerebral vessels were predicted on the basis of pharmacokinetic and fractal analyses.

Results: The increase in absorbed energy was attributed to secondary electrons emitted from the contrast medium and varied depending on its content and volume. Interestingly, the amount of energy absorbed increased with increasing dilution of the contrast medium. Furthermore, the amplification effect of the radiation dose varied according to the type of contrast medium used.

Conclusion: These results suggest that the amplification effect of the radiation dose is closely related to an increase in the cross-sectional area in which the X-rays interact with the contrast medium, which is caused by increased distribution of contrast medium in the cerebral vessels. When the contrast medium is diluted with water, its spread in the cerebral vessels plays a more important role than its content in the amplification effect of the radiation dose.

Objective: Mechanical thrombectomy (MT) for middle cerebral artery M2 occlusion (M2O) is challenging because the procedure is performed in a narrow and tortuous artery. In this study, we compared MT using an aspiration catheter (AC) versus a stent retriever (SR) used alone, and retrospectively evaluated the efficacy and safety of MT using an AC for M2O.

Methods: Seventy-four consecutive patients who underwent MT for M2O at our institution between April 2016 and April 2020 were evaluated. The subjects were classified into those treated by AC (AC group) or SR alone (SR group). The AC group included patients treated by both contact aspiration and a combination technique of AC and SR. Background factors and outcomes, including modified treatment in cerebral infarction (mTICI) 2c-3 recanalization, were compared between the groups.

Results: AC and SR groups consisted of 47 and 27 patients respectively. Among them, the rate of mTICI 2b-3 was 93.6% vs 92.6%, and that of mTICI 2c-3 was 72.3% vs 48.2% (P = 0.004). The perioperative symptomatic subarachnoid hemorrhage (SAH) rate was 0% vs 7.4%, and modified Rankin scale scores of 0–2 were 78.6% vs 50% (P = 0.03). In the AC group, the mTICI 2c-3 rate was higher in patients in whom the AC was adequately advanced to the thrombus compared to those with inadequate AC advancement (83.3% vs 36.3%, P = 0.002).

Conclusion: The rate of mTICI 2c-3 was higher in the AC than SR group, with no cases of symptomatic SAH. MT using AC for M2O might achieve safe and effective thrombectomy.

Objective: In radiation-induced carotid artery stenosis (RIS), morphological characteristics, such as bilateral and long lesion distances and in-stent stenosis, have been reported as common after carotid artery stenting (CAS). Here, we present 25 cases at our hospital wherein CAS was performed for RIS and compare the morphological characteristics and the safety of the treatment with cases of atherosclerotic carotid artery stenosis (AS).

Methods: Twenty-five lesions from 21 patients underwent CAS for RIS at our hospital between March 2002 and July 2020. The procedure was performed at a mean of 10.0 ± 5.2 years after radiation therapy with 60–72 Gy, with a median follow-up of 45 months. We retrospectively selected consecutive patients with AS with comparable follow-up times from the beginning of the study as controls. We compared the patients’ background, stenosis findings including plaque MRI, perioperative period, and postoperative course.

Results: All patients in both groups completed the procedure, and the median follow-up time for the RIS and AS groups was 45 and 40 months, respectively (p = 0.1479). Patients in the RIS group had a lower mean age (69.9 ± 6.9 vs. 75.3 ± 7.04, p = 0.0075), a higher stenosis rate (79.1 ± 8.7% vs. 68.6 ± 11.7%, p = 0.0032), and longer stenosis greater than one vertebra (long lesions) (10 vs. 1, p = 0.0046) compared with the patients in the AS group. Although there was no significant difference in outcomes between the two groups, restenosis tended to be more common in the RIS group. Plaque MRI was characterized by a significantly higher T2WI signal (p = 0.0381) in the RIS group, which was attributable to the fact that a necrotic core has been reported commonly in the plaque tissue of RIS.

Conclusion: RIS has a high likelihood of restenosis both morphologically and in terms of plaque characteristics. Thus, close follow-up is crucial.

Objective: Central venous disease, defined as ≥50% stenosis or obstruction of central veins, is one of many life-threatening complications faced by patients on hemodialysis. It often presents as upper limb edema to the arteriovenous (AV) shunt for hemodialysis, although neurological symptoms are rare. We report a case of central venous disease with neurological symptoms associated with endovascular therapy.

Case Presentation: A 79-year-old man presented with status epilepticus. His past medical history included rectal carcinoma when he was 69 years old and indication for hemodialysis when he was 79 years old. However, he had no history of neurological disease or epilepsy. On arrival at our facility, CT perfusion revealed venous circulation dysfunction on the left cerebral hemisphere. DSA demonstrated regurgitation from the AV shunt on left upper limb to the cerebral veins and obstruction of the left subclavian vein. Ligation of the causal AV shunt was deemed difficult due to surrounding edema; therefore, endovascular transarterial coil embolization was performed. After completely occluding the AV shunt, patient’s condition improved significantly. The patient was discharged 3 days later without neurologic symptoms, with no recurrence of epilepsy was observed to date.

Conclusion: Coil embolization of causal AV shunt significantly improved the neurological symptoms of central venous disease.