Dural Arteriovenous Fistulas of the Foramen Magnum Region: Clinical Features and Angioarchitectural Phenotypes.

BACKGROUND AND PURPOSE: AVFs of the foramen magnum region, including fistulas of the marginal sinus and condylar veins, have complex arterial supply, venous drainage, symptoms, and risk features that are not well-defined. The purpose of this study was to present the angioarchitectural and clinical phenotypes of a foramen magnum region AVF from a large, single-center experience. MATERIALS AND METHODS: We retrospectively reviewed cases from a 10-year neurointerventional data base. Arterial and venous angioarchitectural features and clinical presentation were extracted from the medical record. Venous drainage patterns were stratified into 4 groups as follows: type 1 = unrestricted sinus drainage, type 2 = sinus reflux (including the inferior petrosal sinus), type 3 = reflux involving sinuses and cortical veins, and type 4 = restricted cortical vein outflow or perimedullary congestion. RESULTS: Twenty-eight patients (mean age, 57.9 years; 57.1% men) had 29 foramen magnum region AVFs. There were 11 (37.9%) type 1, nine (31.0%) type 2, six (20.7%) type 3, and 3 (10.3%) type 4 fistulas. Pulsatile tinnitus was the most frequent symptom (82.1%), followed by orbital symptoms (31.0%), subarachnoid hemorrhage (13.8%), cranial nerve XII palsy (10.3%), and other cranial nerve palsy (6.9%). The most frequent arterial supply was the ipsilateral ascending pharyngeal artery (93.1% ipsilateral, 55.5% contralateral), vertebral artery (89.7%), occipital artery (65.5%), and internal carotid artery branches (48.3%). CONCLUSIONS: We present the largest case series of foramen magnum region AVFs to date and show that clinical features relate to angioarchitecture. Orbital symptoms are frequent when sinus reflux is present. Hemorrhage was only observed in type 3 and 4 fistulas.

Interrater Reliability in the Measurement of Flow Characteristics on Color-Coded Quantitative DSA of Brain AVMs.

BACKGROUND AND PURPOSE: Hemodynamic features of brain AVMs may portend increased hemorrhage risk. Previous studies have suggested that MTT is shorter in ruptured AVMs as assessed on quantitative color-coded parametric DSA. This study assesses the interrater reliability of MTT measurements obtained using quantitative color-coded DSA. MATERIALS AND METHODS: Thirty-five color-coded parametric DSA images of 34 brain AVMs were analyzed by 4 neuroradiologists with experience in interventional neuroradiology. Hemodynamic features assessed included MTT of the AVM and TTP of the dominant feeding artery and draining vein. Agreement among the 4 raters was assessed using the intraclass correlation coefficient. RESULTS: The interrater reliability among the 4 raters was poor (intraclass correlation coefficient = 0.218; 95% CI, 0.062-0.414; P value = .002) as it related to MTT assessment. When the analysis was limited to cases in which the raters selected the same image to analyze and selected the same primary feeding artery and the same primary draining vein, interrater reliability improved to fair (intraclass correlation coefficient = 0.564; 95% CI, 0.367-0.717; P < .001). CONCLUSIONS: Interrater reliability in deriving color-coded parametric DSA measurements such as MTT is poor so minor differences among raters may result in a large variance in MTT and TTP results, partly due to the sensitivity and 2D nature of the technique. Reliability can be improved by defining a standard projection, feeding artery, and draining vein for analysis.

Impact of Aortic Arch Anatomy on Technical Performance and Clinical Outcomes in Patients with Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Arterial access is a technical consideration of mechanical thrombectomy that may affect procedural time, but few studies exist detailing the relationship of anatomy to procedural times and patient outcomes. We sought to investigate the respective impact of aortic arch and carotid artery anatomy on endovascular procedural times in patients with large-vessel occlusion. MATERIALS AND METHODS: We retrospectively reviewed imaging and medical records of 207 patients from 2 academic institutions who underwent mechanical thrombectomy for anterior circulation large-vessel occlusion from January 2015 to July 2018. Preintervention CTAs were assessed to measure features of the aortic arch and ipsilateral great vessel anatomy. These included the cranial-to-caudal distance from the origin of the innominate artery to the top of the aortic arch and the takeoff angle of the respective great vessel from the arch. mRS scores were calculated from rehabilitation and other outpatient documentation. We performed bootstrap, stepwise regressions to model groin puncture to reperfusion time and binary mRS outcomes (good outcome, mRS ≤ 2). RESULTS: From our linear regression for groin puncture to reperfusion time, we found a significant association of the great vessel takeoff angle (P = .002) and caudal distance from the origin of the innominate artery to the top of the aortic arch (P = .05). Regression analysis for the binary mRS revealed a significant association with groin puncture to reperfusion time (P < .001). CONCLUSIONS: These results demonstrate that patients with larger takeoff angles and extreme aortic arches have an association with longer procedural times as approached from transfemoral access routes.

Recent Administration of Iodinated Contrast Renders Core Infarct Estimation Inaccurate Using RAPID Software.

BACKGROUND AND PURPOSE: Automated CTP software is increasingly used for extended window emergent large-vessel occlusion to quantify core infarct. We aimed to assess whether RAPID software underestimates core infarct in patients with an extended window recently receiving IV iodinated contrast. MATERIALS AND METHODS: We reviewed a prospective, single-center data base of 271 consecutive patients who underwent CTA ± CTP for acute ischemic stroke from May 2018 through January 2019. Patients with emergent large-vessel occlusion confirmed by CTA in the extended window (>6 hours since last known well) and CTP with RAPID postprocessing were included. Two blinded raters independently assessed CT ASPECTS on NCCT performed at the time of CTP. RAPID software used relative cerebral blood flow of <30% as a surrogate for irreversible core infarct. Patients were dichotomized on the basis of receiving recent IV iodinated contrast (<8 hours before CTP) for a separate imaging study. RESULTS: The recent IV contrast and contrast-naïve cohorts comprised 23 and 15 patients, respectively. Multivariate linear regression analysis demonstrated that recent IV contrast administration was independently associated with a decrease in the RAPID core infarct estimate (proportional increase = 0.34; 95% CI, 0.12-0.96; P = .04). CONCLUSIONS: Patients who received IV iodinated contrast in proximity (<8 hours) to CTA/CTP as part of a separate imaging study had a much higher likelihood of core infarct underestimation with RAPID compared with contrast-naïve patients. Over-reliance on RAPID postprocessing for treatment disposition of patients with extended window emergent large-vessel occlusion should be avoided, particularly with recent IV contrast administration.

Revisiting classic MRI findings of venous malformations: Changes in protocols may lead to potential misdiagnosis.

Introduction Magnetic resonance imaging (MRI) is most sensitive and specific for characterizing venous malformations (VMs). VMs typically demonstrate central enhancement on delayed-contrast imaging. Fluid-fluid levels (FFLs) are uncommon in VMs and common in lymphatic malformations (LMs). Technology has advanced since the initial description of these findings. Rates of detection of these MRI findings in VMs may have changed as MRI technology and techniques have evolved. Methods and methods A prospectively maintained database from a multidisciplinary vascular anomalies clinic was reviewed to identify patients with final diagnosis of VM or LM. Patients with reviewable contrast-enhanced MRIs were selected, reviewing the oldest MRI studies in the database against the newest MRI studies to identify equal numbers of patients from the temporal extremes. Imaging was reviewed to assess for presence of FFLs. Enhancement was quantified by measuring signal in the same location of the lesion both on pre- and postcontrast sequences Results Forty patients were identified for analysis. Twenty studies with sufficient archived imaging for review were performed between 1995 and 2006; 20 such studies were performed between 2011 and 2012. The new imaging cohort had higher rates of FFL visualization ( p = 0.001). Correlation was found between time to imaging following contrast and degree of enhancement ( p < 0.001). Inverse correlation was found between scan date and time to contrast ( p = 0.001) and scan date and enhancement ( p = 0.021). Conclusion FFLs should no longer be considered exclusionary for the diagnosis of VMs. Timing following contrast administration should be maximized to increase degree of enhancement to confirm the diagnosis of VMs.

Association between lumbar epidural injection and development of acute paraparesis in patients with spinal dural arteriovenous fistulas.

SUMMARY: We report 3 patients with previously undiagnosed spinal dural arteriovenous fistulas (SDAVFs), who developed acute paraparesis following lumbar epidural steroid injection. MR imaging demonstrated spinal cord T2 hyperintensity, edema and/or enhancement of the conus, and intradural enlarged vascular flow voids. Spinal angiography confirmed SDAVFs arising from pedicles remote from the sites of the epidural steroid injection. Fistulas were eliminated with either endovascular or combination endovascular and open surgical approaches, with subsequent partial resolution of paraparesis.

Assessment of vasculature of meningiomas and the effects of embolization with intra-arterial MR perfusion imaging: a feasibility study.

BACKGROUND AND PURPOSE: Embolization of meningiomas has emerged as a preoperative adjuvant therapy that has proved effective in mitigating blood loss during surgical resection. Arterial supply to these tumors is typically identified by diffuse areas of parenchymal staining after selective x-ray angiograms. We investigate the benefits that selective injection of MR contrast may have in identifying vascular territories and determining the effects of embolization therapy. MATERIALS AND METHODS: Selective intra-arterial (IA) injection of dilute MR contrast media was used to assess the vascular distribution territories of meningeal tumors before and after embolization therapy. Regions of the tumor that experienced loss of signal intensity after localized contrast injections into the external and common carotid as well as vertebral arteries were used to quantify the specific vessel's volume of distribution. Assessments were made before and after embolization to reveal changes in the vascular supply of the tumor. MR findings were compared with radiographic evaluation of tumor vascular supply on the basis of conventional x-ray angiography. RESULTS: MR proved to be an excellent means to assess tissue fed by selected arteries and clearly demonstrated the treated and untreated portions of the neoplasm after therapy. In some instances, MR revealed postembolization residual enhancement of the tumor that was difficult to appreciate on x-ray angiograms. Very low contrast dose was necessary, which made repeated assessment during therapy practical. CONCLUSION: MR perfusion imaging with selective IA injection of dilute contrast can reveal the distribution territory of vessels. Changes in tumor vasculature could be detected after embolization, which reveal the volumetric fraction of the tumor affected by the therapy.

Pial Artery Supply as an Anatomic Risk Factor for Ischemic Stroke in the Treatment of Intracranial Dural Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: Although intracranial dural arteriovenous fistulas are principally supplied by dural branches of the external carotid, internal carotid, and vertebral arteries, they can also be fed by pial arteries that supply the brain. We sought to determine the frequency of neurologic deficits following treatment of intracranial dural arteriovenous fistulas with and without pial artery supply. MATERIALS AND METHODS: One hundred twenty-two consecutive patients who underwent treatment for intracranial dural arteriovenous fistulas at our hospital from 2008 to 2015 were retrospectively reviewed. Patient data were examined for posttreatment neurologic deficits; patients with such deficits were evaluated for imaging evidence of cerebral infarction. Data were analyzed with multivariable logistic regression. RESULTS: Of 122 treated patients, 29 (23.8%) had dural arteriovenous fistulas with pial artery supply and 93 (76.2%) had dural arteriovenous fistulas without pial arterial supply. Of patients with pial artery supply, 4 (13.8%) had posttreatment neurologic deficits, compared with 2 patients (2.2%) without pial artery supply (P = .04). Imaging confirmed that 3 patients with pial artery supply (10.3%) had cerebral infarcts, compared with only 1 patient without pial artery supply (1.1%, P = .03). Increasing patient age was also positively associated with pial supply and treatment-related complications. CONCLUSIONS: Patients with dural arteriovenous fistulas supplied by the pial arteries were more likely to experience posttreatment complications, including ischemic strokes, than patients with no pial artery supply. The approach to dural arteriovenous fistula treatment should be made on a case-by-case basis so that the risk of complications can be minimized.

Effects on vessel measurement accuracy and subsequent occlusion after calcium channel blocker infusion during treatment of cerebral aneurysms with the Pipeline embolization device.

Introduction/Purpose To achieve aneurysm occlusion, flow diverters (FDs) must be accurately sized to maximize coverage over the neck and induce thrombosis. Catheterization for diagnostic angiography can cause vasospasm that may affect vessel measurements. This study evaluates impacts of intra-arterial infusion of a calcium channel blocker (CCB) on angiographic measurements in patients treated with FDs to determine effects on final diameter of the FD and subsequent occlusion. Materials and methods Pre-treatment measurements were recorded for diameter of the distal and proximal landing zones and maximum and minimum diameters between these segments. Post-treatment measurements of the stent following deployment were recorded at these locations. When CCB was infused, post-infusion pre-treatment measurements were recorded. Rates of occlusion were noted for all patients. T-tests were performed to assess for differences in pre- and post-treatment measurements and rates of occlusion between groups with and without CCB infusion. Results Twenty-eight FDs were deployed to treat 25 aneurysms in 24 patients. CCB infusion was performed prior to deployment of 12 (42.9%) devices. No significant difference was noted between groups for pre- and post-treatment measurement changes. Confirmed aneurysm occlusion was more likely to occur in the CCB infusion group (88.9% vs. 36.4%, p = 0.009). Conclusion Optimization of device sizing is important to increase FD density over the aneurysm neck and promote thrombosis. To improve measurement accuracy, CCB infusion can reduce effects of mild vasospasm. Subsequent aneurysm occlusion was more likely to occur following FD treatment when device size selection was based on measurements performed following CCB infusion.

Superselective Intra-Arterial Ethanol Sclerotherapy of Feeding Artery and Nidal Aneurysms in Ruptured Cerebral Arteriovenous Malformations.

In the endovascular treatment of cerebral arteriovenous malformations, ethanol sclerotherapy is seldom used due to safety concerns. However, when limited reflux of an embolic agent is permissible or when there is a long distance to the target, ethanol may be preferable. We reviewed 10 patients with 14 cerebral AVM feeding artery aneurysms or intranidal aneurysms treated with intra-arterial ethanol sclerotherapy at our institution between 2005 and 2014. All patients presented with acute intracranial hemorrhage. Thirteen of 14 aneurysms were treated primarily with 60%-80% ethanol into the feeding artery. Complete target feeding artery and aneurysm occlusion was seen in all cases; 8/13 (62%) were occluded by using ethanol alone. No retreatments or recurrences were seen. One permanent neurologic deficit (1/13, 7.7%) and no deaths occurred. In a subset of ruptured cerebral AVMs, ethanol sclerotherapy of feeding artery aneurysms and intranidal aneurysms can be performed with a high degree of technical success and a low rate of complication.

Lesion stability characteristics outperform degree of stenosis in predicting outcomes following stenting for symptomatic intracranial atherosclerosis.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) causes substantial morbidity and mortality. Treatment decisions have most commonly been driven by the degree of luminal stenosis. This study compares ICAD lesion stability features with percentage stenosis for associations with adverse outcomes following treatment with stents. MATERIALS AND METHODS: Retrospective analysis was performed of prospectively maintained procedure logs. Lesions were classified by symptom type as hypoperfusion, non-hypoperfusion, or indeterminate, and pretreatment asymptomatic intervals were noted. Hypoperfusion lesions and indeterminate or non-hypoperfusion lesions with ≥14 days of asymptomatic interval were classified as stable. Percentage stenosis was calculated and compared against these other symptom features for value in predicting technical complication, ischemic stroke, disability, or death at 90 days and 2 years using univariate and multivariate analysis. RESULTS: 130 lesions were treated in 124 patients. The only statistically significant percent stenosis finding was lesions with 60-99% stenosis were less likely to have technical complications. In univariate analysis, stroke at 2 years was less common with hypoperfusion and stable lesions. In multivariate analysis, only hypoperfusion status was associated with lower stroke rates at 2 years. CONCLUSIONS: Lesion stability features, particularly non-hypoperfusion symptomatology, outperform percentage stenosis in predicting outcomes following treatment of ICAD with stents. Further examination is needed to better classify the natural history of ICAD and more precisely classify lesion stability.

Progressive versus Nonprogressive Intracranial Dural Arteriovenous Fistulas: Characteristics and Outcomes.

BACKGROUND AND PURPOSE: A minority of intracranial dural arteriovenous fistulas progress with time. We sought to determine features that predict progression and define outcomes of patients with progressive dural arteriovenous fistulas. MATERIALS AND METHODS: We performed a retrospective imaging and clinical record review of patients with intracranial dural arteriovenous fistula evaluated at our hospital. RESULTS: Of 579 patients with intracranial dural arteriovenous fistulas, 545 had 1 fistula (mean age, 45 ± 23 years) and 34 (5.9%) had enlarging, de novo, multiple, or recurrent fistulas (mean age, 53 ± 20 years; P = .11). Among these 34 patients, 19 had progressive dural arteriovenous fistulas with de novo fistulas or fistula enlargement with time (mean age, 36 ± 25 years; progressive group) and 15 had multiple or recurrent but nonprogressive fistulas (mean age, 57 ± 13 years; P = .0059, nonprogressive group). Whereas all 6 children had fistula progression, only 13/28 adults (P = .020) progressed. Angioarchitectural correlates to chronically elevated intracranial venous pressures, including venous sinus dilation (41% versus 7%, P = .045) and pseudophlebitic cortical venous pattern (P = .048), were more common in patients with progressive disease than in those without progression. Patients with progressive disease received more treatments than those without progression (median, 5 versus 3; P = .0068), but as a group, they did not demonstrate worse clinical outcomes (median mRS, 1 and 1; P = .39). However, 3 young patients died from intracranial venous hypertension and intracranial hemorrhage related to progression of their fistulas despite extensive endovascular, surgical, and radiosurgical treatments. CONCLUSIONS: Few patients with dural arteriovenous fistulas follow an aggressive, progressive clinical course despite treatment. Younger age at initial presentation and angioarchitectural correlates to venous hypertension may help identify these patients prospectively.

Association between Venous Angioarchitectural Features of Sporadic Brain Arteriovenous Malformations and Intracranial Hemorrhage.

BACKGROUND AND PURPOSE: Intracranial hemorrhage is the most serious outcome for brain arteriovenous malformations. This study examines associations between venous characteristics of these lesions and intracranial hemorrhage. MATERIALS AND METHODS: Statistical analysis was performed on a prospectively maintained data base of brain AVMs evaluated at an academic medical center. DSA, CT, and MR imaging studies were evaluated to classify lesion side, drainage pattern, venous stenosis, number of draining veins, venous ectasia, and venous reflux. Logistic regression analyses were performed to identify the association of these angiographic features with intracranial hemorrhage of any age at initial presentation. RESULTS: Exclusively deep drainage (OR, 3.42; 95% CI, 1.87-6.26; P < .001) and a single draining vein (OR, 1.98; 95% CI, 1.26-3.08; P = .002) were associated with hemorrhage, whereas venous ectasia (OR, 0.52; 95% CI, 0.34-0.78; P = .002) was inversely associated with hemorrhage. CONCLUSIONS: Analysis of venous characteristics of brain AVMs may help determine their prognosis and thereby identify lesions most appropriate for treatment.

Stent angioplasty for cervical carotid artery stenosis in high-risk symptomatic NASCET-ineligible patients.

BACKGROUND AND PURPOSE: Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) has shown carotid endarterectomy (CEA) to be protective compared with medical therapy alone, its stringent eligibility criteria excluded patients with severe medical, angiographic, and neurological risk factors. We sought to determine the safety and efficacy of stent angioplasty in this high-risk subset for whom the perioperative morbidity and mortality of surgery are elevated. METHODS: Twenty-eight consecutive symptomatic NASCET-ineligible patients (10 female; median age, 72.2 years) underwent microcatheter-based carotid stent angioplasty. Half of the patients had sustained a previous stroke. Classification of surgical risk by Sundt criteria yielded no patients in grade 1, 3 patients in grade 2 (10.7%), 8 in grade 3 (28.6%), and 17 (60.7%) in grade 4. Stratification of stroke risk for medical therapy according to the European Carotid Surgery Trial (ECST) 5-point score showed 8 patients with a score of 3 (28.6%), 12 with 4 (42.8%), and 8 with 5 (28.6%). Follow-up was obtained in all patients at a median of 14 months. RESULTS: The procedure was technically successful in all cases (100%), with immediate stenosis reduction from a mean of 80.3% to 2.7%. There were no periprocedural deaths, 1 major stroke (3.6%), no minor strokes, and 3 transient ischemic attacks (10.7%). In-hospital complications included 2 nonfatal myocardial infarctions, 1 case of acute renal failure, and 1 groin hematoma requiring transfusion. There were 5 deaths during the follow-up period, all beyond 30 days after the procedure: 3 from cardiac causes, 1 from lung cancer, and 1 following unrelated surgery. The patient with major stroke died at 7.8 months during rehabilitation. No surviving patients had further strokes, and all except 1 (95.5%) remained asymptomatic. Anatomic follow-up in 20 patients showed occlusion in 2 (10%) (1 symptomatic, 1 asymptomatic) and intimal hyperplasia in 3 asymptomatic patients (15%). CONCLUSIONS: The clinical results and sustained freedom from symptoms and stroke during the short available follow-up period suggest that stent angioplasty may be useful in the treatment of symptomatic cervical carotid stenosis in high-risk patients despite a notable incidence of restenosis.

Venous angiography is needed to interpret inferior petrosal sinus and cavernous sinus sampling data for lateralizing adrenocorticotropin-secreting adenomas.

Bilateral simultaneous venous sampling of ACTH from the inferior petrosal sinus is a reliable test for diagnosing Cushing's disease, but is not reliable for lateralizing ACTH-secreting pituitary adenomas. We reviewed 23 consecutive patients with Cushing's disease who underwent venous angiography of the cavernous and inferior petrosal sinuses followed by bilateral simultaneous venous sampling of ACTH in the inferior petrosal and cavernous sinuses. Venous drainage was bilaterally symmetric in 14 patients (61%) and asymmetric in 9 (39%). The most common asymmetric pattern (6 patients) was for blood from both cavernous sinuses to drain into the right inferior petrosal sinus, with no significant drainage into the left. Cavernous sinus sampling in 21 patients correctly lateralized the tumor in 12 cases of symmetric venous drainage, but in only 3 cases of asymmetric drainage. Inferior petrosal sinus sampling in all 23 patients correctly lateralized the tumor in 12 cases of symmetric drainage, but in only four cases of asymmetric drainage. Overall, venous sampling correctly lateralized 70% of the tumors. Incorrect lateralization in cases of asymmetric venous drainage is probably attributable to shunting of blood toward the side of dominant venous drainage. Our findings illustrate the need for venography in all patients undergoing venous sampling of ACTH because an understanding of the venous drainage patterns is essential to correctly interpret venous sampling data and warn physicians that the lateralization data may be incorrect or unreliable.

Localization procedures in patients with persistent or recurrent hyperparathyroidism.

OBJECTIVE: To determine the accuracy of noninvasive and invasive localization studies in patients with persistent or recurrent hyperparathyroidism (HPT). DESIGN AND SETTING: Reoperations based on patients who were treated surgically for recurrent or persistent HPT at the University of California-San Francisco Hospitals from 1982 to 1993. PATIENTS: This study evaluated 174 localization studies performed in 152 patients before reoperation (110 women and 42 men). MAIN OUTCOME MEASURES: The accuracy of localization studies, including ultrasonography, thallous chloride T1 201-technetium Tc 99m pertechnetate scanning, technetium Tc 99m sestamibi scanning, magnetic resonance imaging, computed tomography, and selective venous catheterization, were evaluated, as were the results of parathyroid reoperations. RESULTS: A total of 174 consecutive reoperations were performed in 152 patients with HPT (persistent, 113; recurrent, 39; mean age, 54 years; range, 21 to 88 years). One hundred thirty-three patients had primary HPT, 15 had secondary HPT, and four had tertiary HPT. Overall, 141 (93%) became normocalcemic, two (1%) became hypocalcemic, and nine (6%) remained hypercalcemic. Abnormal parathyroid glands at reoperation were situated in a normal location in 77 cases (44%), in the mediastinum in 37 cases (22%), in a deep cervical location in 34 cases (19%), or in an intrathyroidal location in 14 cases (8%), or were undescended in four cases (2%); supernumerary glands were found in 26 cases (15%). Some patients had more than one remaining abnormal gland. Selective venous catheterization with a parathyroid hormone assay was done in cases in which the results of noninvasive localization studies were equivocal or negative, and it frequently converted an equivocal result of a localization study to a definitely positive result. There were no complications from the localization studies. At reoperation, permanent hypoparathyroidism that required parathyroid autotransplantation of cryopreserved tissue developed in two patients and two patients had recurrent laryngeal nerve palsies. CONCLUSION: We currently recommend using ultrasonography and technetium Tc99m sestamibi scanning and magnetic resonance imaging for patients with recurrent or persistent HPT. Selective venous catheterization with a parathyroid hormone assay is done selectively. Localization tests decrease morbidity and improve overall results in these patients.

Hemangiomas and vascular malformations of the head and neck: MR characterization.

PURPOSE: To characterize the MR appearance of the common hemangioma of infancy as well as low- and high-flow vascular malformations of the head and neck. PATIENTS AND METHODS: Twenty patients with vascular lesions of the head and neck proved either by pathology, angiography, and/or unequivocal clinical diagnosis were included. Vascular lesions included 15 low-flow lesions (four hemangiomas, 10 venous malformations, one lymphatic malformation), and five high-flow lesions (three arteriovenous malformations (AVMs) and two invasive combined malformations). All patients had MR studies (generally 1.5 T using routine T1- and T2-weighted spin-echo sequences). Nine had postgadolinium, gradient recalled-echo, CT, and/or angiographic studies. FINDINGS: Deep hemangiomas and venous malformations demonstrate intermediate signal in T1-weighted images, heterogeneous high signal on T2-weighted images, and prominent enhancement. Involuting hemangiomas show focal areas of high signal intensity on T1-weighted images due to fatty replacement. Venous malformations may demonstrate venous lakes seen as homogeneous regions of high signal intensity on T2-weighted images and phleboliths seen as low signal foci. The one patient with lymphatic malformation showed a large multicystic submandibular mass with large hemorrhage-fluid levels. Features of high-flow lesions (AVMs) include serpiginous signal voids, absence of a dominant mass, and intraosseous extension with decreased marrow signal on T1-weighted images. Invasive combined vascular malformations showed serpiginous flow voids and infiltrative solid masses. Low-flow lesions (hemangiomas, venous, and lymphatic malformations) demonstrate distinct MR findings allowing their differentiation from high-flow lesions (AVMs). Deep hemangiomas and venous malformations appear as solid masses and may look identical. Venous lakes and phleboliths are features of venous malformations which, when present, may help in diagnosis. Combined vascular malformations share features of both low- and high-flow malformations. CONCLUSION: MR is useful in delineating the extent of disease and differentiating low- and high-flow vascular lesions.

Posterior fossa venous angiomas with drainage through the brain stem.

PURPOSE: To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem. METHODS: Eleven cases of posterior fossa venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the cerebellum and brain stem is made. RESULTS: Six of the 11 venous angiomas were found in the cerebellum, four in the brain stem; one involved both the cerebellum and brain stem. The cerebellar venous angiomas drained to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transpontine vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases. CONCLUSION: Cerebellar and brain stem venous angiomas have several potential routes of drainage, including an enlarged vein traversing the pons, midbrain, or medulla. A knowledge of the normal venous anatomy of this region helps to understand the occurrence of these uncommon routes of venous drainage.

Transarterial platinum coil embolization of carotid-cavernous fistulas.

Of the 227 embolization procedures performed by our neurointerventional section for symptomatic carotid-cavernous fistulas over the past 10 years, five involved placement of platinum coils in the cavernous sinus from a transarterial route. In four patients, prior transarterial balloon procedures had failed to produce fistula closure. In the fifth patient, with Ehlers-Danlos syndrome, a prior transvenous embolization attempt was unsuccessful. In three patients, complete closure of the carotid-cavernous fistula was achieved with preservation of the parent artery. In one patient, the earliest treated, a portion of a platinum coil projected through the fistula into the parent artery. To eliminate the risk of clot formation and distal embolization, internal carotid occlusion was performed and tolerated without deficits. In the last patient, closure of the anterior drainage was achieved, but complicated by distal migration of the platinum coils with transient aggravation of ocular symptoms. Attempts to occlude the remaining cortical drainage were unsuccessful with platinum coils; therefore, a balloon was used to obliterate the small remaining fistula. Transarterial platinum coil embolization is an alternative treatment for symptomatic carotid-cavernous fistulas that cannot be closed successfully by other embolization techniques. The development of shorter, more thrombogenic, detachable or retrievable coils may make this technique more promising in the future.