• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.84-87
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• 2017

Cerebral hyperperfusion syndrome (CHS) is a rare complication that can occur when conducting stent insertion or endarterectomy in patients with carotid artery stenosis and is known to be caused by various mechanisms when the blood volume abruptly increases. The main clinical symptoms are unilateral headache, hypertension, seizure, and focal neurologic deficit. Subarachnoid hemorrhage and parenchymal hemorrhage may lead to permanent impairment or death in severe cases. CHS can be predicted by using transcranial Doppler, perfusion magnetic resonance imaging, and single photon emission computed tomography. In our case report, a patient developed CHS subsequent to significant venous congestion caused by carotid artery stent insertion. The patient had preexisting, symptomatic bilateral carotid artery stenosis. Venous congestion occurs when the direction of blood flow changes because of increased blood volume in patients with well-developed collateral vessels. We believe that CHS can be predicted from this finding. This study reports the possibility that CHS could be confirmed by cerebral angiography after insertion of the internal carotid stent.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.26 no.1
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• pp.1-10
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• 2024

Objective: Endovascular coil embolization is the primary treatment modality for intracranial aneurysms. However, its long-term durability remains of concern, with a considerable proportion of cases requiring aneurysm reopening and retreatment. Therefore, establishing optimal follow-up imaging protocols is necessary to ensure a durable occlusion. This study aimed to develop guidelines for follow-up imaging strategies after endovascular treatment of intracranial aneurysms. Methods: A committee comprising members of the Korean Neuroendovascular Society and other relevant societies was formed. A literature review and analyses of the major published guidelines were conducted to gather evidence. A panel of 40 experts convened to achieve a consensus on the recommendations using the modified Delphi method. Results: The panel members reached the following consensus: 1. Schedule the initial follow-up imaging within 3-6 months of treatment. 2. Noninvasive imaging modalities, such as three-dimensional time-of-flight magnetic resonance angiography (MRA) or contrast-enhanced MRA, are alternatives to digital subtraction angiography (DSA) during the first follow-up. 3. Schedule mid-term follow-up imaging at 1, 2, 4, and 6 years after the initial treatment. 4. If noninvasive imaging reveals unstable changes in the treated aneurysms, DSA should be considered. 5. Consider late-term follow-up imaging every 3-5 years for lifelong monitoring of patients with unstable changes or at high risk of recurrence. Conclusions: The guidelines aim to provide physicians with the information to make informed decisions and provide patients with high-quality care. However, owing to a lack of specific recommendations and scientific data, these guidelines are based on expert consensus and should be considered in conjunction with individual patient characteristics and circumstances.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.949-958
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• 2022

Objective: To investigate the feasibility of using a deep learning-based analysis of auscultation data to predict significant stenosis of arteriovenous fistulas (AVF) in patients undergoing hemodialysis requiring percutaneous transluminal angioplasty (PTA). Materials and Methods: Forty patients (24 male and 16 female; median age, 62.5 years) with dysfunctional native AVF were prospectively recruited. Digital sounds from the AVF shunt were recorded using a wireless electronic stethoscope before (pre-PTA) and after PTA (post-PTA), and the audio files were subsequently converted to mel spectrograms, which were used to construct various deep convolutional neural network (DCNN) models (DenseNet201, EfficientNetB5, and ResNet50). The performance of these models for diagnosing ≥ 50% AVF stenosis was assessed and compared. The ground truth for the presence of ≥ 50% AVF stenosis was obtained using digital subtraction angiography. Gradient-weighted class activation mapping (Grad-CAM) was used to produce visual explanations for DCNN model decisions. Results: Eighty audio files were obtained from the 40 recruited patients and pooled for the study. Mel spectrograms of "pre-PTA" shunt sounds showed patterns corresponding to abnormal high-pitched bruits with systolic accentuation observed in patients with stenotic AVF. The ResNet50 and EfficientNetB5 models yielded an area under the receiver operating characteristic curve of 0.99 and 0.98, respectively, at optimized epochs for predicting ≥ 50% AVF stenosis. However, Grad-CAM heatmaps revealed that only ResNet50 highlighted areas relevant to AVF stenosis in the mel spectrogram. Conclusion: Mel spectrogram-based DCNN models, particularly ResNet50, successfully predicted the presence of significant AVF stenosis requiring PTA in this feasibility study and may potentially be used in AVF surveillance.

• Journal of Korean Neurosurgical Society
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• v.65 no.6
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• pp.816-824
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• 2022

Objective : Emergency superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis in patients with large vessel occlusion who fails mechanical thrombectomy or does not become an indication due to over the time window can be done as an alternative for blood flow restoration. The authors planned this study to quantitatively measure the degree of improvement in cerebral perfusion flow using perfusion magnetic resonance imaging (MRI) after bypass surgery and to find out what factors are related to the outcome of the bypass surgery. Methods : For a total of 107 patients who underwent emergent STA-MCA bypass surgery with large vessel occlusion, the National Institute of Health stroke scale (NIHSS), modified Rankin score (mRS), infarction volume, and hypoperfusion area volume was calculated, the duration between symptom onset and reperfusion time, occlusion site and infarction type were analyzed. After emergency STA-MCA bypass, hypoperfusion area volume at post-operative 7 days was calculated and analyzed compared with pre-operative hypoperfusion area volume. The factors affecting the improvement of mRS were analyzed. The clinical status of patients who underwent emergency bypass was investigated by mRS and NIHSS before and after surgery, and changes in infarct volume, extent, degree of collateral circulation, and hypoperfusion area volume were measured using MRI and digital subtraction angiography (DSA). Results : The preoperative infarction volume was median 10 mL and the hypoperfusion area volume was median 101 mL. NIHSS was a median of 8 points, and the last normal to operation time was a median of 60.7 hours. STA patency was fair in 97.1% of patients at 6 months follow-up DSA and recanalization of the occluded vessel was confirmed at 26.5% of patients. Infarction volume significantly influenced the improvement of mRS (p=0.010) but preoperative hypoperfusion volume was not significantly influenced (p=0.192), and the infarction type showed marginal significance (p=0.0508). Preoperative NIHSS, initial mRS, occlusion vessel type, and last normal to operation time did not influence the improvement of mRS (p=0.272, 0.941, 0.354, and 0.391). Conclusion : In a patient who had an acute cerebral infarction due to large vessel occlusion with large ischemic penumbra but was unable to perform mechanical thrombectomy, STA-MCA bypass could be performed. By using time-to-peak images of perfusion MRI, it is possible to quickly and easily confirm that the brain tissue at risk is preserved and that the ischemic penumbra is recovered to a normal blood flow state.

• Journal of Korean Neurosurgical Society
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• v.67 no.4
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• pp.442-450
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• 2024

Objective : Cerebral hyperperfusion syndrome (CHS) manifests as a collection of symptoms brought on by heightened focal cerebral blood flow (CBF), afflicting nearly 30% of patients who have undergone superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The aim of this study was to investigate whether the amalgamation of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) and apparent diffusion coefficient (ADC) imaging via MRI can discern cerebral hyperemia after STA-MCA anastomosis surgery. Methods : A retrospective study was performed of patients who underwent STA-MCA anastomosis due to Moyamoya disease or atherosclerotic steno-occlusive disease. A protocol aimed at preventing CHS was instituted, leveraging the use of MRI FLAIR. Patients underwent MRI diffusion with FLAIR imaging 24 hours after STA-MCA anastomosis. A high signal on FLAIR images signified the presence of hyperemia at the bypass site, triggering a protocol of hyperemia care. All patients underwent hemodynamic evaluations, including perfusion MRI, single-photon emission computed tomography (SPECT), and digital subtraction angiography, both before and after the surgery. If a high signal intensity is observed on MRI FLAIR within 24 hours of the surgery, a repeat MRI is performed to confirm the presence of hyperemia. Patients with confirmed hyperemia are managed according to a protocol aimed at preventing further progression. Results : Out of a total of 162 patients, 24 individuals (comprising 16 women and 8 men) exhibited hyperemia on their MRI FLAIR scans following the procedure. SPECT was conducted on 23 patients, and 11 of them yielded positive results. All 24 patients underwent perfusion MRI, but nine of them showed no significant findings. Among the patients, 10 displayed elevations in both CBF and cerebral blood volume (CBV), three only showed elevation in CBF, and two only showed elevation in CBV. Follow-up MRI FLAIR scans conducted 6 months later on these patients revealed complete normalization of the previously observed high signal intensity, with no evidence of ischemic injury. Conclusion : The study determined that the use of MRI FLAIR and ADC mapping is a competent means of early detection of hyperemia after STA-MCA anastomosis surgery. The protocol established can be adopted by other neurosurgical institutions to enhance patient outcomes and mitigate the hazard of permanent cerebral injury caused by cerebral hyperemia.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.613-621
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• 2019

The purpose of this study is to evaluate the effectiveness of supportive devices which are for minimizing the patient's movement during lower extremity angiography and to verify image quality of phantom by analyzing of Mask image, DSA image and Roadmap image into SNR and CNR. As a result of comparing SNR with CNR of mask image obtained by DSA technique using the phantom alone and phantom placed on the supportive devices, there was no significant difference between about 0~0.06 for SNR and about 0~0.003 for CNR. The study showed about 0.11~0.35 for SNR and 0.016~0.031 for CNR of DSA imaging by DSA technique about only water phantom of the blood vessel model and the water phantom placed on the device. Analyzing SNR and CNR of Roadmap technique about water phantom on the auxiliary device (hardboard paper, pomax, polycarbonate, acrylic) and water phantom alone, there was no significant difference between 0.02~0.05 for SNR and 0.002~0.004 for CNR. In conclusion, there was no significant difference on image quality by using supportive devices made by hardboard paper, pomax, polycarbonate or acryl regardless of whether using supportive devices or not. Supportive devices to minimize of the patient's movement may reduce the total amount of contrast, exam-time, radiation exposure and eliminate risk factors during angiogram. Supportive devices made by hardboard paper can be applied easily during angiogram due to advantages of reasonable price and simple processing. It is considered that will be useful to consider cost efficiency and types of materials and their properties in accordance with purpose and method of the study when the operator makes and uses supportive devices.