Dynamic Volume Perfusion CT of the Foot in Critical Limb Ischemia: Response to Percutaneous Revascularization.

OBJECTIVE. The purpose of this study was to assess the reproducibility and validity of quantitative perfusion parameters derived from dynamic volume perfusion CT in patients with critical limb ischemia (CLI) and to evaluate perfusion parameter changes before and after endovascular revascularization. SUBJECTS AND METHODS. Patients with CLI referred for unilateral extremity endovascular arterial recanalization were enrolled in this study. CT examinations obtained 1-3 days before the procedure and then within 1 week after the treatment were evaluated at two reading sessions. Blood flow (BF), blood volume (BV), and time to peak (TTP) were measured on color-coded maps and compared statistically. Intraobserver agreement was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS. Endovascular treatment was technically successful for all 16 patients. The posttreatment BF and BV showed a statistically significant increase in both dermal and muscle areas (p < 0.05). The posttreatment TTP shortened at a statistically significant level (p < 0.05). In the 3-month clinical follow-up period, the limb salvage rate was 81% and the percentage change in BF and BV of patients with poor response to treatment had no statistically significant increase after treatment, consistent with the clinical assessment. The percentage change in BF and BV correlated well with the improvement of the clinical condition (r = 0.673-0.901). ICC values showed excellent agreement in the range of 0.95-0.98. CONCLUSION. As a reproducible method, dynamic volume perfusion CT of the foot may enable quantitative evaluation of the perfusion of soft tissues and also provide a novel approach to assessing response to endovascular recanalization in CLI.

Treatment-related alterations of imaging findings in osteoid osteoma after percutaneous radiofrequency ablation.

OBJECTIVES: We aimed to report the long-term outcomes of osteoid osteoma patients and to determine CT and dynamic contrast-enhanced MR imaging characteristics of radiofrequency ablation (RFA) treatment related changes of osteoid osteoma between follow-up periods. MATERIALS AND METHODS: Thirty patients (seven female, 23 male) who underwent CT-guided RFA of osteoid osteoma were included. Follow-up imaging examinations were divided into two subgroups; first (1-3 months) and second (> 6 months) periods. Nidus size, calcification, cortical thickening, maximum signal intensity (SImax), time of SImax (Tmax), slope of signal intensity-time (SIT) curves were noted. CT and dynamic MR imaging findings were compared between follow-up periods. RESULTS: Clinical success rate was 100%. The mean of OO nidi size was 5.85 ± 1.98 mm before treatment. There was a significant difference for OO nidi sizes between pretreatment and second follow-up period examinations (p = 0.002). SImax and slope of SIT curves of all patients (100%) showed decrease on follow-up MRIs. There was a significant decrease for SImax values between pretreatment and second follow-up period. There was a significant decrease for slope of SIT curves between pretreatment and both follow-up periods. CONCLUSIONS: RFA is an effective and safe treatment choice for osteoid osteomas. On follow-up imaging, slope of SIT curve and Tmax have the most important positive predictive value for long-term outcomes and single dynamic contrast-enhanced MRI within first 3 months after treatment may be sufficient for symptom-free patients.

Endovascular recanalization of infra-popliteal TASC C and TASC D lesions in patients with critical limb-threatening ischemia: a single-center experience.

PURPOSE: The present study aims to (1) assess the technical success and limb salvage rates of endovascular therapy in patients with critical limb-threatening ischemia (CLTI) and infra-popliteal Trans-Atlantic Inter-Society Consensus (TASC) C/D lesions according to the updated 2015 TASC II classification and (2) to present our institutional experience. METHODS: A single-center retrospective study was conducted on patients with TASC C/D CLTI who underwent endovascular treatment between 2012 and 2017. The follow-up protocol consisted of Doppler ultrasound conduction every 3 months for the first year unless patients showed symptoms of CLTI. Patients with at least 1 year of follow-up data were included in the study, and if applicable their 3-year results were evaluated in terms of primary patency, absence of amputation, amputation-free survival, and overall survival. RESULTS: A total of 248 patients and 287 limbs (238 TASC D lesions and 49 TASC C lesions) were treated via infra-popliteal percutaneous transluminal angioplasty. The overall technical success was 87%, the primary patency rate was 41.5% in the first year, and the freedom from amputation rates were 80.8% in 1 year and 67.7% in 3 years. CONCLUSION: In patients with infra-popliteal arterial occlusive diseases, endovascular treatment methods demonstrate a high rate of technical success and favorable outcomes in limb preservation.

Clinical prediction model for primary aldosteronism subtyping and special focus on adrenal volumetric assessment.

PURPOSE: Our aim was to develop a prediction model based on a simple score with clinical, laboratory, and imaging findings for the subtype diagnosis of primary aldosteronism (PA). The contribution of adrenal volumetric assessment to PA subtyping was also investigated. METHODS: Thirty-five patients with adequate cannulation in adrenal venous sampling (AVS) were included. Laboratory data, the saline infusion test (SIT), and the AVS results of patients with PA were retrospectively evaluated. Volumetric assessment was performed using magnetic resonance imaging (MRI) and the ratio of adrenal volumes was calculated after adjusting for gender- and side-specific mean reference values of both adrenal glands. RESULTS: The AVS was consistent with unilateral PA in 49% and bilateral in 51% of the patients. Hypertension as a reason for work-up, the highest aldosterone/lowest potassium value higher than 12, the percentage of plasma aldosterone concentration (PAC) reduction after SIT by equal or less than 43.5%, the use of oral potassium replacement, unilateral disease at pre-AVS imaging, and a ratio of adjusted adrenal volumes equal to or below 1.7 were indicative of unilateral disease in univariate logistic regression analysis concerning the distinction of PA subtyping (p < 0.05). Multivariate logistic regression analysis also revealed that adrenal volumetric assessment has an impact on PA subtyping (p < 0.05). In the prediction model, when each of the six parameters that were significant in the univariate logistic regression analysis was assigned one point, < 4 predicted bilateral PA, whereas ≥ 4 predicted unilateral PA (AUC:0.92, p < 0.001). CONCLUSION: This prediction model before AVS may serve as a convenient and practical approach, while an adjusted adrenal volumetric assessment can make a positive contribution to PA subtyping.

Quantitative and qualitative comparison of standard-dose and low-dose pediatric head computed tomography: a retrospective study assessing the effect of adaptive statistical iterative reconstruction.

OBJECTIVES: Our aim was to assess the effect of adaptive statistical iterative reconstruction (ASIR) on pediatric head computed tomography (CT) examinations. METHODS: We retrospectively reviewed 305 pediatric head CT examinations. The study population consisted of standard dose (STD, n = 152) examinations reconstructed with filtered back projection and low dose (LD, n = 153) examinations reconstructed with 30% (LD30) and 0% (LD0) ASIR. We compared groups by means of radiation dose, noise measures, and visual grading. Student t test, 1-way analysis of variance test, and Mann-Whitney U test were used for statistical analysis. RESULTS: The dose in the LD30 group was significantly lower (29%) than that in the STD group (P < 0.001). The noise in the white matter (P < 0.001), SNR (P < 0.001), and subjective image noise (P = 0.044) was significantly better in the STD group than those in the LD30 group. There was no significant difference between LD30 and STD groups in the sharpness (P = 0.141), diagnostic acceptability (P = 0.079), and artifacts (P = 0.750) and contrast-to-noise ratio (P = 0.718). CONCLUSIONS: In conclusion, we found that a blend of 30% ASIR in a 16-slice multidetector CT produces diagnostically acceptable pediatric head CT examinations with a 29% less dose.

Outcomes of endovascular treatment of thoracic aorta pathologies: 10-year single-center results.

PURPOSE Thoracic endovascular aortic repair (TEVAR) is a safe and effective treatment method for a variety of thoracic aortic pathologies. We aimed to investigate the mortality and complication outcomes and associated factors of TEVAR treatment in Turkey. METHODS In this single-centered retrospective study, patients with thoracic aorta pathologies treated with TEVAR at Gazi University School of Medicine, Department of Radiology, between January 2009 and January 2020 were included. Perioperative, early, and late mortality, complications, and technical success were the outcomes. RESULTS The sample comprised 58 patients with 68 TEVAR interventions. Eleven (16.2%) patients were female, the mean age was 60.1 ± 13.4 years. Emergent TEVAR was required in 20.7% of the patients. The main indications of TEVAR were intact descending aorta aneurysms in 37.9% of the sample, 31.0% Stanford type-B dissection, and 12.1% traumatic transections. The technical success rate of primary and secondary interventions was 98.3% and 100%, respectively. The mortality rate in the first 30 days was 8.6%. Seventeen (29.3%) cases had at least 1 complication related to TEVAR treatment. The most common complication was type-1A endoleak (10.3%). Having acute symptoms, stroke, and acute renal failure were significantly associated with mortality (P=.020, .049, and .009, respectively). CONCLUSION This study reported the outcomes of TEVAR treatment from a tertiary medical center in Turkey over a decade. Patients presenting with acute symptoms and who developed stroke and acute renal failure after the procedure should be carefully followed up as these factors were found to be associated with mortality.

Pre- and Post-stenting Cerebral Blood Flow Velocities in Patients with Carotid Artery Stenosis.

PURPOSE: This study evaluated the hemodynamic effects of carotid artery stenting (CAS) on cerebral blood flow velocity (CBFV) in patients with carotid artery stenosis, before, 3 d, and 3 months after the procedure using transcranial Doppler ultrasound (TCD). METHODS: The study included 36 patients with atheromatous carotid artery stenosis. Cerebral computed tomography (CT) or magnetic resonance imaging (MRI) was performed in every patient, and carotid stenosis was evaluated using duplex sonography, CT, and MRI angiography before the procedure. To obtain baseline values, the CBFV was evaluated 1 d before CAS. Follow-up TCD evaluations were performed 3 d and 3 months postoperatively. RESULTS: The median degree of internal carotid artery (ICA) stenosis in the participants was 90% (range 50%-99%). The median CBFV at the anterior cerebral artery (ACA) was significantly lower on the ipsilateral side than on the contralateral side before stenting; however, there were no significant differences in CBFV in the ipsi and contralateral middle cerebral artery (MCA). The median CBFV in the ipsilateral MCA increased significantly 3 d after the procedure and remained higher than the basal values after 3 months. CONCLUSIONS: We observed significant increases in the median CBFV and pulsatility index (PI) in the MCA bilaterally, especially on the stented side, measured 3 d and 3 months after stenting in patients with severe ICA stenosis.

The position of transarterial chemoembolization with drug-eluting beads and yttrium-90 transarterial radioembolization in patients with hepatocellular carcinoma: Consensus statements from a Delphi-method expert panel in Turkey.

PURPOSE: Clinical studies conducted in different geographic regions using different methods to compare transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) have demonstrated discordant results. Meta-analyses in this field indicate comparable overall survival (OS) with TACE and TARE, while reporting a longer time to progression and a higher downstaging effect with TARE treatment. In terms of isolated procedure costs, treatment with TARE is 2 to 3 times more, and in some countries even more, expensive than TACE. However, relevant literature indicates that TARE is more advantageous compared to TACE regarding the need for repeat procedures, costs of complication management, total hospital stay and quality of life. Heterogeneity of hepatocellular carcinoma (HCC) patients as well as the shortcomings of clinical classifications, randomized clinical trials and cost-effectiveness studies make it difficult to choose between treatment alternatives in this field. As in other countries, these challenges lead to differences in treatment choice across different centers in Turkey. METHODS: The present expert panel used two round modified Delphi method to investigate the resources and clinical parameters referenced while selecting patients for drug-eluting beads (DEB)-TACE and TARE treatment modalities in Turkish clinical practice. The cost-effectiveness parameters and comparisons of these treatments have also been evaluated at a prediction level. RESULTS: The panelists stated that they most commonly use the BCLC staging system for the management of HCC patients in Turkey. However, they did not find any of the staging systems or treatment guidelines sufficient enough for their clinical practice in terms of covering the down-staging intent of treatments. Since living donor transplant preference is higher in Turkey than the rest of the Western countries, down-staging treatments are thought to be more prioritized in Turkey than that in other Western countries. The panelists reached a consensus that TARE may provide improved OS and reduce the number of repeat procedures compared to DEB-TACE in intermediate-stage patients with a single tumor spanning a diameter above 5 cm who experience recurrence after previous treatment with TACE and most TACE-naïve patient groups in intermediate stage. CONCLUSION: Based on the consensus on OS and the number of procedures, the panelists assumed that TARE would be more cost-effective than DEB-TACE in most groups of TACE-naïve patients in intermediate stage and in those with a single tumor spanning a diameter above 5 cm. It was also stated that the predicted cost-effectiveness advantage of TARE could be more pronounced in patients with a tumor diameter greater than 7 cm.

Effect of a chloride channel inhibitor, 5-nitro-2- (3-phenylpropylamino)-benzoate, on endothelin-1 induced vasoconstriction in rabbit basilar artery.

AIM: Endothelin-1 (ET-1) has been implicated in the pathophysiology of cerebral vasospasm. Chloride (Cl-) channels exist in vascular smooth muscle and activation of these channels leads to depolarization and contraction. The aim of the present study was to test the effect of 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), a Cl- channel antagonist, on the ET-1-induced cerebral vasospasm in rabbit basilar artery and thus investigate the contribution of Cl- channels. MATERIAL AND METHODS: Thirty rabbits were divided into five groups and received intra-arterial injection of isotonic saline (Group I, n=6), ET-1 (group II, n=6), ET-1 plus NPPB (Group III, n=6), dimethylsulfate (DMSO4) (Group IV, n = 6) and NPPB (Group V, n=6). Pre and post injection basilar artery diameters were measured in each group and transmission electron microscopic investigations on basilar arteries were performed. RESULTS: The mean pre-injection and post-injection vessel diameters were 0.8833 mm and 0.7000 mm in ET-1 group, 0.6833 mm and 0.8500 mm in ET-1 + NPPB group. NPPB administered prior to ET-1 injection, prevented the ET-1-induced vasoconstriction. Additionally, NPPB prevents the ET-1 induced changes in vessel wall and neurons in the brain stem. CONCLUSION: The results of this study add further insights to our armamentarium against cerebral vasospasm.

Endovascular Treatment for Near Occlusion of the Internal Carotid Artery : 30-Day Outcome and Long-Term Follow-Up.

BACKGROUND: The treatment strategy and the correct incidence of near occlusion (NO) of the internal carotid artery (ICA) is still controversial. In routine radiological imaging NO can easily be misdiagnosed as complete occlusion and there is no consensus on the standard treatment strategy. PURPOSE: To present our perioperative and long-term follow-up results of ICA NO patients treated with carotid artery stenting (CAS). MATERIAL AND METHODS: Between 2004-2014 a total of 182 patients with ICA NO were evaluated for CAS. The study included 132 male (72.5 %) and 50 female (27.5 %) patients with a mean age of 70.2 years. Patients underwent a clinical neurological evaluation and radiological imaging of the carotid arteries before the CAS procedure. Of the patients 80 (44 %) were asymptomatic. The median clinical and carotid Doppler ultrasound (DUS) follow-up period was 64 months (range 18-124 months). RESULTS: In 182 patients CAS were performed, 4 patients (2.2 %) developed minor stroke, 2 patients (1.1 %) developed myocardial infarction but no major stroke or death occurred in the following 30-day period. Asymptomatic restenosis was detected in seven patients (3.8 %) in the follow-up period. CONCLUSION: With sufficient neurological evaluation during pretreatment and posttreatment periods and when the procedure is performed with technologically developed products by an experienced interventional team, CAS is beneficial in patients with ICA NO.

The New Double-Layer Micromesh Stent (Roadsaver®): Use in Endovascular Treatment of Supraaortic and Visceral Artery Aneurysms and Pseudoaneurysms.

PURPOSE: This study was designed to present our preliminary experience with the Roadsaver® double-layer micromesh (DLM) stent in the endovascular treatment of supra-aortic and visceral aneurysms and to utilize the flow-diverting effect of this new design in the treatment of these aneurysms. METHODS: DLM stent (Roadsaver®, Terumo, Tokyo, Japan) was used in five patients (median age 61.8 years; three men) for treating arterial aneurysms (one common carotid artery, one vertebral artery V1 segment, one superior mesenteric artery, and two renal artery aneurysms). RESULTS: All stents were successfully deployed. Follow-up imaging with conventional catheter angiography or computed tomography showed successful treatment of all aneurysms. CONCLUSIONS: The new DLM stent appears to be promising for the treatment of supra-aortic and visceral aneurysms.

Endovascular Treatment of Intracranial Anterior Circulation Aneurysms with Flow Diverters: A Single Centre Experience with mid and long-term results.

AIM: We report our experience with flow diverter devices in the treatment of intracranial aneurysms arising from anterior circulation with mid and long-term follow-up. MATERIAL AND METHODS: 78 aneurysms in 61 patients (range 25-81 years, 13 male, 48 female) were treated with flow diverter devices. 40 (51,3%) aneurysms were treated with pipeline embolization device (PED), 24 (30,8%) aneurysms were treated with SILK stent, 12(15,4%) aneurysms were treated with flow redirection endoluminal device (FRED) and two aneurysms were treated with P64 Flow Modulation Device (P64). Angiographic follow-up data at six month and one yea were recorded and the occlusion degrees of aneurysms were evaluated according to the scale which was formed by Kamran et al. RESULTS: At six month follow-up, complete occlusion (grade 4) rate was 60,8% and at one year increased to 74,3%. Statistical analysis revealed significant difference (p=0,002) between six month and one year follow-up results but there was no significant association (p=0,531, p=1,000) between aneurysm occlusion rate and aneurysm diameter. Two patient (3,2%) died due to hemorrhagic complication. CONCLUSION: Endovascular treatment of intracranial anterior circulation aneurysms with flow diverters is a safe and effective treatment option. A high rate of stable occlusion is achieved at long term follow-up.

Interventional radiology in the lacrimal drainage system.

This article presents a review of the interventional radiological procedures in the lacrimal drainage system. Balloon dacryocystoplasty and nasolacrimal polyurethane stent placement are the main fluoroscopically guided interventions for the treatment of epiphora by recanalizing the obstructed LDS. These procedures can also be used for dacryolith removal and lacrimal sac abscess treatment.

Radiation dose in balloon dacryocystoplasty: a study using Rando phantoms and thermoluminescent dosimetry.

PURPOSE: The radiation dose to the lens of the eye, skin, thyroid and brain of patients who underwent diagnostic and interventional radiological procedures of the lacrimal drainage system have been measured with thermoluminescent dosimeters (TLD-100 and TLD-700) by using an adult male and female Rando phantom. All dose values for one second of fluoroscopic exposure and one frame of digital subtraction dacryocystography (DS-DCG) exposure have been obtained individually in the pastero-anterior (PA) and lateral (LAT) projections. MATERIALS AND METHODS: An adult male and female Rando phantom was used instead of the patients. The procedures were performed by using an Advantx AFM C-arm unit coupled with a DX Hiline digital image acquisition and processing system. The 6-inch mode of a triplefield image intensifier (II) was used, with a circular collimation of the same or a slightly smaller size. Two different lithium floride (LiF) thermoluminescent chips were used for absorbed dose measurements: TLD700, approximately 4.5 mm in diameter and 0.9 mm in thickness; TLD100, 3.7 mm square and 0.9 mm in thickness. RESULTS: The average values of absorbed doses (lens of the eye, skin, thyroid and brain) measured separately with TLD100 and TLD700 dosimeters after irradiation of the male and female Rando phantom are presented for LAT and PA projections. CONCLUSION: This study suggests that useful information for dose determination can be obtained by use of the radiation dose to the lens of the eye, thyroid and brain received during radiological procedure of the LDS for one frame of DS-DCG and one second of fluoroscopy.

Endovascular treatment of peripheral vascular lesions with stent-grafts.

PURPOSE: To evaluate our results of stent-graft implantation for the endovascular treatment of peripheral vascular lesions. MATERIALS AND METHODS: Seventeen patients underwent repair of iatrogenic, traumatic, or spontaneous vascular lesions by means of endovascular stent-grafts. The study cases consisted of 10 cardiac catheterization-induced femoral arteriovenous fistulas (AVFs) located between the deep femoral artery and the femoral vein, one iatrogenic AVF between the common iliac artery and vein, one penetrating trauma-induced AVF between the superficial femoral artery and vein, two penetrating trauma-induced pseudoaneurysms in the axillary and popliteal arteries, and three spontaneous or atherosclerosis- related iliac artery aneurysms. Balloon-expandable or self-expandable stent-grafts were used in all 17 cases. RESULTS: All the stent-grafts were deployed successfully. In catheterization-induced femoral AVFs, complete closure of the fistulas was immediately accomplished in 9 of the 10 cases. Blood flow within the pseudoaneurysms of the axillary artery and the popliteal artery, and aneurysms of the iliac arteries were stopped. Partial closure was achieved in two patients with traumatic iliac and femoral AVFs. For the patients who reported subsided complaints, mean follow-up for 24 months with clinical examination and color Doppler ultrasound revealed patency of the stented segments. CONCLUSION: Our results suggest that endovascular treatment of various types of peripheral vascular lesions with stent-grafts is a low-risk procedure, which appears to be less invasive than surgery.

Unfused or twig-like middle cerebral artery.

INTRODUCTION: The knowledge of anatomic variations of the cerebral arterial circulation may be important to decide on the safest surgical or endovascular treatment method. Variations in the middle cerebral artery (MCA) territory seems to be less frequent than the other intracranial arteries. During the embryonic stage the primitive MCA is hypothesized to be made up of arterial twigs and these twigs will generate the definitive MCA at the end of the development stage. As in our cases, an early interruption in this period will prevent the evolution of MCA normally and a plexiform arterial network will create the M1 segment of MCA which is the so-called extremely rare unfused or twig-like (Uf/Tw) MCA variation. Our aim is to define and evaluate the angiographical features of Uf/Tw MCA. METHODS: The diagnosis of Uf/Tw MCA was evaluated in a total of 4855 diagnostic cerebral catheter angiograms, retrospectively. The coexisting intracranial pathologies were also interpreted with former radiological examinations. A review of the literature is provided. RESULTS: A total of six cases of Uf/Tw MCA was identified on angiograms accompanying ipsilateral internal carotid artery (ICA) occlusion and contralateral ICA supraclinoid segment aneurysm in one case, and cingulate gyrus AVM in the other. In two different cases, CT or MRI examinations revealed coexisting subarachnoid hemorrhage and misdiagnosis of forniceal AVM in one case, and temporal arachnoid cyst and parenchymal hematoma in the other. CONCLUSION: Lack of data and knowledge about the Uf/Tw MCA variation may cause misdiagnosis and unnecessary treatment attempts.

Bilateral persistence of type 1 proatlantal arteries: report of a case and review of the literature.

Persistent proatlantal artery type 1 is one of the four anastomotic vessels between the carotid and vertebrobasilar arterial systems. Persistence of this embryonic anastomosis is extremely rare. We present such a case with bilateral persistent proatlantal arteries that arose from internal carotid arteries, entered the skull via the foramen magnum and united with the horizontal portions of vertebral arteries. We also mention its embryology, potential clinical implications, and differentiating features between two types of proatlantal arteries.

Percutaneous management of bile duct stones.

This article presents a review of the interventional radiological procedures in the percutaneous management of the bile duct stones through T-tube or transhepatic tracts. Interventional stone removal techniques mainly include extraction through the T-tube tract with baskets or forceps and expulsion into the duodenum by means of baskets or balloon catheters with the dilatation of the sphincter of Oddi. Fragmentation or size reduction of the stone, dilatation of the strictures and cholangioscopic assistance can facilitate the procedures.

Endovascular stent-graft placement for the management of a traumatic axillary artery pseudoaneurysm-a case report.

A 24-year-old woman with a right infraclavicular gunshot wound developed an axillary artery pseudoaneurysm. She was successfully treated by using a 5 cm Hemobahn stent-graft with a diameter of 6 mm. Postimplantation arteriography revealed normal flow through the axillary artery without evidence of leakage of contrast medium. Five months after the procedure, stenoses developed within the stent-graft owing to intimal hyperplasia and were treated by balloon angioplasty. The patient has been followed up symptom-free for 6 months after the second procedure.

Intravenous and local intraarterial tissue-plasminogen activator in a rabbit model of acute thromboembolic stroke: angiographic comparison.

The aim of early thrombolytic therapy in acute stroke is to obtain early recanalization of occluded cerebral arteries and prevent or reduce irreversible ischemic brain damage. In this study, Seldinger technique and digital subtraction angiography were used to verify thromboembolic occlusion of the common carotid artery by an autologous 12-hour-old thrombus in 28 rabbits. Thirty minutes after embolization, 2 mg/kg of recombinant tissue-plasminogen activator (rt-PA) was delivered intravenously by way of the femoral vein in group A (n = 8) and through a local intraarterial infusion in group B (n = 8). Twelve control animals received an equivalent volume of saline intravenously (group C, n = 6) or by local intra-arterial infusion (group D, n = 6). A comparison of posttreatment angiographs of the treatment groups and the control groups was used to demonstrate reperfusion induced by thrombolytic therapy. None of the control animals showed any evidence of recanalization. Both intravenously (group A) and intra-arterially (group B) treated animals achieved 100% recanalization, although the average time to recanalization was significantly longer in group A (P = .01; 123.7 vs 82.5 min). These results suggest that local intra-arterial administration of rt-PA within 30 minutes produces more rapid reperfusion compared with the intravenous route. Further studies and additional treatments are needed to widen the therapeutic window and decrease hemorrhagic side effects.