Woong Yoon

Contrast Enhancement and Contrast Extravasation on Computed Tomography After Intra-Arterial Thrombolysis in Patients With Acute Ischemic Stroke

Background and Purpose— The goal of this study was to determine the CT findings and clinical consequences of contrast enhancement and contrast extravasation on CT scans obtained after intra-arterial thrombolytic therapy for treatment of acute ischemic stroke. Methods— Sixty-two patients were treated with intra-arterial thrombolysis. All patients underwent nonenhanced CT scans immediately and 24 hours after thrombolytic therapy. Contrast enhancement was defined as a hyperdense lesion that disappeared on a 24-hour follow-up CT scan. Contrast extravasation was defined as a hyperdense lesion with maximum Hounsfield unit >90 that persisted on a follow-up CT scan. We evaluated the differences in the clinical and radiological data between 3 groups: contrast enhancement, contrast extravasation, and control groups. Results— Contrast enhancement was found in 14 of 62 patients (22.6%); contrast extravasation was seen in 7 (11.3%). Compared with the control group, the contrast enhancement group had a lower recanalization grade (64.3% versus 34.1%, P =0.048) and a lower incidence of hemorrhagic transformation (14.3% versus 43.9%, P =0.047). The contrast extravasation group had a higher incidence of both hemorrhage (100% versus 43.9%, P =0.006) and symptomatic hemorrhage (100% versus 14.6%, P <0.001) than the control group. Poor outcomes were more frequent in the contrast extravasation group (100% versus 38.9%, P =0.003) than the control group. Conclusions— Contrast enhancement on CT scans obtained after intra-arterial thrombolysis is usually not associated with hemorrhagic complications. However, contrast extravasation is highly associated with parenchymatous hematoma and should be considered a negative prognostic sign.

FDG PET/CT for the Detection and Evaluation of Breast Diseases: Usefulness and Limitations

Positron emission tomography (PET) with fluorine 18 fluorodeoxyglucose (FDG) is used to diagnose, stage, and monitor breast cancer. FDG PET has the capability to depict abnormal metabolic activity before any anatomic change occurs; however, in the absence of identifiable anatomic structures on PET images, it may be impossible to identify the location of areas of increased radionuclide uptake. In such cases, the coregistration of PET images with images from computed tomography (CT) may help improve diagnostic accuracy and lead to better clinical management of patients with breast cancer. Although FDG PET/CT may have limited diagnostic value for detecting small primary breast tumors, well-differentiated breast cancer, or regional lymph node involvement, it is superior to conventional imaging modalities for detecting distant metastases and recurrences and for monitoring the response to therapy.

Histologic Analysis of Retrieved Clots in Acute Ischemic Stroke: Correlation with Stroke Etiology and Gradient-Echo MRI

BACKGROUND AND PURPOSE: It is unclear whether clot composition analysis is helpful to predict a stroke mechanism in acute large vessel occlusion. In addition, the relationship between early vessel signs on imaging studies and clot compositions has been poorly understood. The purpose of this study was to elucidate the relationship between clot composition and stroke etiology following mechanical thrombectomy and to investigate the effect of varied clot compositions on gradient-echo MR imaging of clots. MATERIALS AND METHODS: Histopathologic analysis of retrieved clots from 37 patients with acute MCA occlusion was performed. Patients underwent gradient-echo imaging before endovascular therapy. Retrieved clots underwent semiquantitative proportion analysis to quantify red blood cells, fibrin, platelets, and white blood cells by area. Correlations between clot compositions and stroke subtypes and susceptibility vessel signs on gradient-echo imaging were assessed. RESULTS: Stroke etiology was classified as cardioembolism in 22 patients (59.4%), large-artery atherosclerosis in 8 (21.6%), and undetermined in 7 (18.9%). The clots from cardioembolism had a significantly higher proportion of red blood cells (37.8% versus 16.9%, P = .031) and a lower proportion of fibrin (32.3% versus 48.5%, P = .044) compared with those from large-artery atherosclerosis. The proportion of red blood cells was significantly higher in clots with a susceptibility vessel sign than in those without it (48.0% versus 1.9%, P < .001), whereas the proportions of fibrin (26.4% versus 57.0%, P < .001) and platelets (22.6% versus 36.9%, P = .011) were significantly higher in clots without a susceptibility vessel sign than those with it. CONCLUSIONS: The histologic composition of clots retrieved from cerebral arteries in patients with acute stroke differs between those with cardioembolism and large-artery atherosclerosis. In addition, a susceptibility vessel sign on gradient-echo imaging is strongly associated with a high proportion of red blood cells and a low proportion of fibrin and platelets in retrieved clots.

Subarachnoid hemorrhage in a multimodal approach heavily weighted toward mechanical thrombectomy with solitaire stent in acute stroke.

Background and Purpose— Subarachnoid hemorrhage (SAH) may appear on computerized tomography scans after mechanical thrombectomy for acute ischemic stroke. The incidence and prognosis of this observation remain unknown. We investigated the frequency and clinical consequences of SAH after treating acute ischemic stroke with a multimodal approach heavily weighted toward mechanical thrombectomy with Solitaire stent. Methods— Seventy-four consecutive patients with acute ischemic stroke underwent mechanical thrombectomy with a Solitaire stent as a first-line treatment. Nonenhanced computerized tomography scans were performed before, immediately after, and 24 hours after treatment to detect SAH. Clinical outcome was assessed after treatment, on day 1, at discharge, and at 3 months. Clinical and radiological data were compared between patients with and without SAH. Results— Twelve patients (16.2%) exhibited SAH associated with pure SAH (n=4) or mixed SAH and contrast extravasation (n=8). The SAH was located in the ipsilateral Sylvian fissure (n=11) or bilateral parietooccipital sulci (n=1). Patients with SAH had no periprocedural vessel perforations or arterial dissections and no postprocedural neurological deteriorations. Rescue angioplasty was performed more frequently in SAH group than in control group (33.3% vs 9.7%; P=0.05). Patients with SAH and those without had similar recanalization rates and clinical outcomes. Conclusions— SAH on post-therapeutic computerized tomography scans were not uncommon after primary mechanical thrombectomy with a Solitaire stent, but they seemed to be benign. Rescue angioplasty and unidentified, small vessel ruptures due to mechanical stretch during stent retrieval might give rise to these lesions.

Acute gastrointestinal bleeding: contrast-enhanced MDCT

With the introduction of multidetector row computed tomography (MDCT), CT is being considered a potential diagnostic method for patients with acute gastrointestinal (GI) bleeding. On arterial phase MDCT images, active GI bleeding is typically identified as a focal area of high attenuation within the bowel lumen, which represents a collection of contrast material that has been extravasated in association with arterial bleeding. Additional CT findings suggestive of acute GI bleeding are focal dilatation of fluid-filled bowel segment noted on contrast-enhanced CT and acute hematoma on unenhanced CT. In addition to detection of active bleeding, an advantage of contrast-enhanced MDCT is the ability to demonstrate morphologic changes in the GI tract, which could suggest specific conditions that cause acute GI bleeding such as intestinal tumors. Arterial phase contrast-enhanced MDCT is rapid, noninvasive, and accurate in detecting and localizing sites of bleeding in patients with acute GI bleeding. Contrast-enhanced MDCT may be a promising diagnostic option in patients with acute GI bleeding.

Acute Basilar Artery Occlusion: Outcome of Mechanical Thrombectomy with Solitaire Stent within 8 Hours of Stroke Onset

BACKGROUND AND PURPOSE: Mechanical thrombectomy with a stent retriever applied shortly after symptom onset could increase good functional outcomes and improve survival in patients with acute basilar artery occlusion, but this has not yet been studied. This study evaluated the efficacy and safety of mechanical thrombectomy with a Solitaire stent within 8 hours of stroke onset in patients with acute basilar artery occlusion. MATERIALS AND METHODS: We analyzed 25 consecutive patients with acute basilar artery occlusion who were treated with mechanical thrombectomy by use of the Solitaire stent within 8 hours of stroke symptom onset. Successful recanalization was defined as TICI grade 2b or 3. Good outcome was defined as mRS score of 0–2 at 3 months. Clinical and radiologic data in patients with good outcomes were compared with those with poor outcomes. RESULTS: Successful recanalization was achieved in 96% (24/25) of patients, and 48% (12/25) of patients had good outcomes. Eighty-eight percent (22/25) of patients survived to 3 months. The median NIHSS score on admission was significantly lower in patients with good outcomes than in those with poor outcomes (9.5 versus 14, P = .005). Procedure-related complications occurred in 2 patients (8%). No symptomatic intracerebral hemorrhages occurred. CONCLUSIONS: The current study suggests that mechanical thrombectomy by use of a Solitaire stent within 8 hours of stroke onset increases good outcomes and improves survival in patients with acute basilar artery occlusion.

Dissection of the V4 segment of the vertebral artery: clinicoradiologic manifestations and endovascular treatment

Intracranial vertebral artery (VA) dissection has three clinical presentations: ischemia, hemorrhage, and mass effect. Imaging findings of intracranial VA dissections vary according to clinical presentation. Irregular stenosis or occlusion of the VA is the most common finding in patients with posterior fossa infarction, whereas a dissecting aneurysm is the main feature in those with acute subarachnoid hemorrhage. A chronic, giant, dissecting aneurysm can cause mass effect on the brain stem or cranial nerves, as well as distal embolism. Magnetic resonance imaging is useful for detection of intramural hematomas and intimal flaps, both of which are diagnostic of VA dissection. Multidetector computed tomography angiography is increasingly used for diagnosis of VA dissection. Catheter angiography is still beneficial for evaluation of precise endoluminal morphology of the dissection before surgical or endovascular intervention. Endovascular treatment is now considered a major therapeutic option for patients with a ruptured dissecting aneurysm or a chronic dissecting aneurysm. Anticoagulation therapy is currently considered the initial treatment of choice in patients with posterior circulation ischemic symptoms. Endovascular treatment, such as stent-assisted angioplasty or coil occlusion at the dissection site, can be performed in selected patients with posterior fossa ischemic symptoms.

Endovascular treatment and the outcomes of atherosclerotic intracranial stenosis in patients with hyperacute stroke.

BACKGROUND The importance of underlying atherosclerotic intracranial artery stenosis (ICAS) in hyperacute stroke patients who receive endovascular therapy remains unknown. OBJECTIVE To report and compare the outcomes of multimodal endovascular therapy in patients with hyperacute stroke with and without underlying ICAS. METHODS A total of 172 consecutive patients with acute stroke were treated with multimodal endovascular therapy that was heavily weighted toward stent-based thrombectomy. Patients with ICAS underwent emergent intracranial angioplasty or stenting. Data were compared between patients with and without ICAS. Revascularization was defined as Thrombolysis in Cerebral Infarction grade ≥2b. A favorable outcome was defined as a modified Rankin Scale score ≤2 or equal to the premorbid modified Rankin Scale score at 3 months. RESULTS ICAS was responsible for acute ischemic symptoms in 40 patients (22.9%). Revascularization and favorable outcome occurred more frequently in the ICAS group than in the control group (95% vs 81.8%, P = .04; 65% vs 40.2%, P = .01, respectively). The median baseline National Institutes of Health Stroke Scale score was significantly lower in the ICAS group compared with the control group (10 vs 12; P = .002). There were no significant differences between the 2 groups in the rates of symptomatic hemorrhage and mortality. CONCLUSION Emergent intracranial angioplasty with or without stenting is safe and feasible and yields a high rate of revascularization and favorable outcome in patients with hyperacute stroke and underlying ICAS. Patients with underlying ICAS have less severe infarctions at presentation and higher successful revascularization after multimodal endovascular therapy in the setting of hyperacute stroke compared with those with other stroke subtypes.

Early Outcome of Combined Thrombolysis Based on the Mismatch on Perfusion CT

Background: Possible factors associated with early outcome after thrombolysis are the recanalization time and the status of tissue. We assessed whether combined intravenous (IV) and intra-arterial (IA) thrombolysis performed according to the status of tissue based on perfusion computed tomography (PCT) is beneficial for the early outcome in patients with acute ischemic stroke. Methods: To improve the recanalization time, we assumed that combined IA thrombolysis after IV thrombolysis would be beneficial. Eligible patients for combined thrombolysis were selected according to the status of tissue based on PCT. Recanalization was defined as Thrombolysis in Myocardial Infarction (TIMI) grade 2 or 3. ‘Good functional outcome’ was defined as a Modified Rankin Scale (mRS) score of 2 or less at discharge. Results: Eighteen patients (11 men) underwent combined IV/IA thrombolysis. The recanalization rate after combined IV/IA thrombolysis was 88.9% (TIMI 2, 4; TIMI 3, 12). A good functional outcome at discharge was noted in 12 patients (66.7%). The incidence of symptomatic intracranial hemorrhage was 5.6% (1/18). Conclusions: The results of this study suggest that combined IV/IA thrombolysis based on the presence of mismatches on PCT might have a relatively high rate of recanalization and a favorable early outcome. In addition, the incidence of symptomatic intracranial hemorrhage was acceptable.

Endovascular Stenting as a First Choice for the Palliation of Superior Vena Cava Syndrome

To assess the effectiveness of endovascular stenting for the palliation of superior vena cava (SVC) syndrome, endovascular stent insertion was attempted in 10 patients with symptomatic occlusion of the SVC. All the patients had known malignant disease of the thorax. Eight patients had been treated previously with chemotherapy and radiotherapy (n=5), chemotherapy alone (n=2), or pneumonectomy and radiotherapy (n=1). After developing SVC syndrome, all the patients were stented before receiving any other treatment. After single or multiple endovascular stents were inserted, five of eight patients were treated with chemotherapy and radiotherapy (n=2) or chemotherapy alone (n=3). Resolution of symptoms was achieved in nine patients within 72 hr (90%). In one patient, the symptoms did not disappear until a second intervention. At follow up, symptoms had recurred in two of ten patients (20%) after intervals of 15 and 60 days. Five patients have died from their cancers, although they remained free of symptoms of SVC occlusion until death. In conclusion, endovascular stent insertion is an effective treatment for palliation of SVC syndrome. Endovascular stent insertion can be considered the first choice of treatment, due to the immediate relief of symptoms and excellent sustained symptomatic relief.