Spontaneous intracranial artery dissection is an uncommon and probably underdiagnosed cause of stroke that is defined by the occurrence of a haematoma in the wall of an intracranial artery. Patients can present with headache, ischaemic stroke, subarachnoid haemorrhage, or symptoms associated with mass effect, mostly on the brainstem. Although intracranial artery dissection is less common than cervical artery dissection in adults of European ethnic origin, intracranial artery dissection is reportedly more common in children and in Asian populations. Risk factors and mechanisms are poorly understood, and diagnosis is challenging because characteristic imaging features can be difficult to detect in view of the small size of intracranial arteries. Therefore, multimodal follow-up imaging is often needed to confirm the diagnosis. Treatment of intracranial artery dissections is empirical in the absence of data from randomised controlled trials. Most patients with subarachnoid haemorrhage undergo surgical or endovascular treatment to prevent rebleeding, whereas patients with intracranial artery dissection and cerebral ischaemia are treated with antithrombotics. Prognosis seems worse in patients with subarachnoid haemorrhage than in those without.

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Epidemiology, pathophysiology, diagnosis, and management of intracranial artery dissection

Diseases of the salivary glands

Vessel wall imaging can depict the morphologies of atherosclerotic plaques, arterial walls, and surrounding structures in the intracranial and cervical carotid arteries beyond the simple luminal changes that can be observed with traditional luminal evaluation. Differentiating vulnerable from stable plaques and characterizing atherosclerotic plaques are vital parts of the early diagnosis, prevention, and treatment of stroke and the neurological adverse effects of atherosclerosis. Various techniques for vessel wall imaging have been developed and introduced to differentiate and analyze atherosclerotic plaques in the cervical carotid artery. High-resolution magnetic resonance imaging (HR-MRI) is the most important and popular vessel wall imaging technique for directly evaluating the vascular wall and intracranial artery disease. Intracranial artery atherosclerosis, dissection, moyamoya disease, vasculitis, and reversible cerebral vasoconstriction syndrome can also be diagnosed and differentiated by using HR-MRI. Here, we review the radiologic features of intracranial artery disease and cervical carotid artery atherosclerosis on HR-MRI and various other vessel wall imaging techniques (e.g., ultrasound, computed tomography, magnetic resonance, and positron emission tomography-computed tomography).

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Vessel Wall Imaging of the Intracranial and Cervical Carotid Arteries

In a meta-analysis of individual patient data from 5 randomized controlled trials, endovascular treatment (EVT) mainly using a stent retriever achieved successful recanalization in 711% of patients suffering from acute stroke due to anterior circulation large artery occlusion (LAO) However, EVT still failed in 289% of LAO cases in those 5 successful trials Stent retriever failure may occur due to anatomical challenges (eg, a tortuous arterial tree from the aortic arch to a target occlusion site), a large quantity of clots, tandem occlusion, clot characteristics (fresh versus organized clots), different pathomechanisms (embolic versus non-embolic occlusion), etc Given that recanalization success is the most important factor in the neurological outcome of acute stroke patients, it is important to seek solutions for such difficult cases In this review, the basic technique of EVT is briefly summarized and then various difficult cases with diverse conditions are discussed along with suggested solutions

/pdf/causes-and-solutions-of-endovascular-treatment-failure-1rtzfco49x.pdf

Causes and Solutions of Endovascular Treatment Failure.

Background and Purpose- Intracranial atherosclerosis (ICAS) is an important cause of large vessel occlusion and poses unique challenges for emergent endovascular thrombectomy. The risk factor profile and therapeutic outcomes of patients with ICAS-related occlusions (ICAS-O) are unclear. We performed a systematic review and meta-analysis of studies reporting the clinical features and thrombectomy outcomes of large vessel occlusion stroke secondary to underlying ICAS (ICAS-O) versus those of other causes (non-ICAS-O). Methods- A literature search on thrombectomy for ICAS-O was performed. Random-effect meta-analysis was used to analyze the prevalence of stroke risk factors and outcomes of thrombectomy between ICAS-O and non-ICAS-O groups. Results- A total of 1967 patients (496 ICAS-O and 1471 non-ICAS-O) were included. The ICAS-O group had significantly higher prevalence of hypertension (odds ratio [OR] 1.46; 95% CI, 1.10-1.93), diabetes mellitus (OR, 1.68; 95% CI, 1.29-2.20), dyslipidemia (OR, 1.94; 95% CI, 1.04-3.62), smoking history (OR, 2.11; 95% CI, 1.40-3.17) but less atrial fibrillation (OR, 0.20; 95% CI, 0.13-0.31) than the non-ICAS-O group. About thrombectomy outcomes, ICAS-O had higher intraprocedural reocclusion rate (OR, 23.7; 95% CI, 6.96-80.7), need for rescue balloon angioplasty (OR, 9.49; 95% CI, 4.11-21.9), rescue intracranial stenting (OR, 14.9; 95% CI, 7.64-29.2), and longer puncture-to-reperfusion time (80.8 versus 55.5 minutes, mean difference 21.3; 95% CI, 11.3-31.3). There was no statistical difference in the rate of final recanalization (modified Thrombolysis in Cerebral Infarction score of 2b/3; OR, 0.67; 95% CI, 0.36-1.27), symptomatic intracerebral hemorrhage (OR, 0.79; 95% CI, 0.50-1.24), good functional outcome (modified Rankin Scale score of 0-2; OR, 1.16; 95% CI, 0.85-1.58), and mortality (OR, 0.94; 95% CI, 0.64-1.39) between ICAS-O and non-ICAS-O. Conclusions- Patients with ICAS-O display a unique risk factor profile and technical challenges for endovascular reperfusion therapy. Intraprocedural reocclusion occurs in one-third of patients with ICAS-O. Intraarterial glycoprotein IIb/IIIa inhibitors infusion, balloon angioplasty, and intracranial stenting may be viable rescue treatment to achieve revascularization, resulting in comparable outcomes to non-ICAS-O.

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Thrombectomy Outcomes of Intracranial Atherosclerosis-Related Occlusions.

To evaluate the diagnostic performance and reproducibility of a computer-aided diagnosis (CAD) system for thyroid cancer diagnosis using ultrasonography (US) based on the operator’s experience. Between July 2016 and October 2016, 76 consecutive patients with 100 thyroid nodules (≥ 1.0 cm) were prospectively included. An experienced radiologist performed the US examinations with a real-time CAD system integrated into the US machine, and three operators with different levels of US experience (0–5 years) independently applied the CAD system. We compared the diagnostic performance of the CAD system based on the operators’ experience and calculated the interobserver agreement for cancer diagnosis and in terms of each US descriptor. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the CAD system were 88.6, 83.9, 81.3, 90.4, and 86.0%, respectively. The sensitivity and accuracy of the CAD system were not significantly different from those of the radiologist (p > 0.05), while the specificity was higher for the experienced radiologist (p = 0.016). For the less-experienced operators, the sensitivity was 68.8–73.8%, specificity 74.1–88.5%, PPV 68.9–73.3%, NPV 72.7–80.0%, and accuracy 71.0–75.0%. The less-experienced operators showed lower sensitivity and accuracy than those for the experienced radiologist. The interobserver agreement was substantial for the final diagnosis and each US descriptor, and moderate for the margin and composition. The CAD system may have a potential role in the thyroid cancer diagnosis. However, operator dependency still remains and needs improvement. • The sensitivity and accuracy of the CAD system did not differ significantly from those of the experienced radiologist (88.6% vs. 84.1%, p = 0.687; 86.0% vs. 91.0%, p = 0.267) while the specificity was significantly higher for the experienced radiologist (83.9% vs. 96.4%, p = 0.016).
 • However, the diagnostic performance varied according to the operator’s experience (sensitivity 70.5–88.6%, accuracy 72.0–86.0%) and they were lower for the less-experienced operators than for the experienced radiologist.
 • The interobserver agreement was substantial for the final diagnosis and each US descriptor and moderate for the margin and composition.

Computer-aided diagnosis system for thyroid nodules on ultrasonography: diagnostic performance and reproducibility based on the experience level of operators

To evaluate the feasibility of high-resolution MRI (HR-MRI) for diagnosing intracranial vertebrobasilar artery dissection (VBD) and to identify the most useful imaging findings suggesting dissection. We retrospectively reviewed 50 patients with suspected intracranial VBDs who underwent HR-MRI. Two neuroradiologists independently reviewed the HR-MR images. The diagnosis based on HR-MRI was compared with the final diagnosis by consensus among the neuroradiologists, neurointerventionist, and neurologist. Two neuroradiologists also sought signs of dissection (mural hematoma, dissection flap, outer-diameter enlargement on T2WI of steno-occlusive lesions). Inter- and intraobserver agreements were analysed. HR-MRI corroborated the final diagnosis in 47 (94 %; 31 VBD and 16 non-VBD) patients. A mural haematoma was best detected on T1WI and contrast-enhanced (CE)-T1WI (54.3 %). Dissection flaps were observed in almost all cases on CE-T1WI (91.4 %), and then were detected on T2WI (68.6 %). Outer-diameter enlargement of the steno-occlusive lesions on angiography was detected in more than half of the cases (62.9 %). The two reviewers showed almost perfect agreement for the diagnosis of VBD and detecting dissection signs on every sequence. HR-MRI can be a useful and non-invasive diagnostic tool for intracranial VBD, and dissection flaps on CE-T1WI are the signs with the greatest diagnostic value. • Direct imaging findings of dissection were well visualised by HR-MRI.
 • Detection of a dissection flap on CE-T1WI is the most reliable diagnostic finding.
 • HR-MRI could be a useful diagnostic tool for intracranial VBDs.

Feasibility of high-resolution MR imaging for the diagnosis of intracranial vertebrobasilar artery dissection

This study evaluated the diagnostic performance of a commercially available computer-aided diagnosis (CAD) system (S-Detect 1 and S-Detect 2 for thyroid) for detecting thyroid cancers. Among 218 thyroid nodules in 106 patients, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the CAD systems were 80.2%, 82.6%, 75.0%, 86.3% and 81.7%, respectively, for the S-Detect 1 and 81.4%, 68.2%, 62.5%, 84.9% and 73.4%, respectively, for the S-Detect 2. The inter-observer agreement between the CAD system and radiologist for the description of calcifications was fair (kappa = 0.336), while the final diagnosis and each ultrasonographic descriptor showed moderate to substantial agreement for the S-Detect 2. To conclude, the current CAD systems had limited specificity in the diagnosis of thyroid cancer. One of the main limitations of the S-Detect 2 was its inaccuracy in recognizing calcifications, which meant that differentiation had to be undertaken by the radiologist.

Real-World Performance of Computer-Aided Diagnosis System for Thyroid Nodules Using Ultrasonography

http://repository.ajou.ac.kr/bitstream/201003/14154/1/26632740.pdf

The Correlations Between MRI Perfusion, Diffusion Parameters, and 18F-FDG PET Metabolic Parameters in Primary Head-and-Neck Cancer: A Cross-Sectional Analysis in Single Institute.

http://repository.ajou.ac.kr/bitstream/201003/14796/1/27583902.pdf

Miran Han

Papers

Computer-aided diagnosis system for thyroid nodules on ultrasonography: diagnostic performance and reproducibility based on the experience level of operators

Feasibility of high-resolution MR imaging for the diagnosis of intracranial vertebrobasilar artery dissection

Real-World Performance of Computer-Aided Diagnosis System for Thyroid Nodules Using Ultrasonography

The Correlations Between MRI Perfusion, Diffusion Parameters, and 18F-FDG PET Metabolic Parameters in Primary Head-and-Neck Cancer: A Cross-Sectional Analysis in Single Institute.

Cerebral infarct volume measurements to improve patient selection for endovascular treatment.