Multiple segmental agenesis of the cerebral arteries: case report

A case of multiple segmental agenesis of the cerebral arteries is presented. Cerebral angiography demonstrated bilateral socalled carotid rete mirabile, a similar rete of the right vertebral artery and intradural duplication of the left vertebral artery. These abnormalities are thought to be caused by multiple segmental agenesis of the cerebral arteries as they penetrate the dura mater, the embryological and anatomical significance of these findings is discussed.     

Modification of a previously described arteriovenous malformation model in the swine: endovascular and combined surgical/endovascular construction and hemodynamics

BACKGROUND AND PURPOSE: The rete mirabile in swine has been proposed as an arteriovenous malformation (AVM) model for acute experimental studies through surgical creation of a large carotid-jugular fistula. This report describes two endovascular modifications to simplify the surgical creation and provides hemodynamic parameters for the AVM model. METHODS: An AVM model was created in 29 animals to study n-butyl 2-cyanoacrylate polymerization kinetics. The common carotid artery (CCA) was punctured and a guiding catheter was inserted tightly into the origin of the ascending pharyngeal artery (APA). The CCA was ligated proximal to the catheter to create a pressure drop across the rete, which represented the AVM nidus. The catheter hub was opened whenever needed and served as the venous drainage of the AVM nidus. The contralateral APA served as the arterial feeder. Instead of the surgical ligation of the CCA, a temporary balloon occlusion was performed in three animals. RESULTS: A mean pressure gradient of 14.9 +/- 10.5 mm Hg (range, 4-42 mm Hg) was measured across the rete. The mean flow rate was 30.4 +/- 14.2 mL/min (range, 3.5-46 mL/min), as measured at the venous drainage. CONCLUSION: The endovascular and combined surgical-endovascular rete AVM model in swine is easy to construct and is less time-consuming than are the currently used models for acute experimental studies. Hemodynamic parameters can be monitored during the entire experiment and correspond to values found in human cerebral AVMs.     

A simplified arteriovenous malformation model in sheep: feasibility study.

BACKGROUND AND PURPOSE: Recently, a swine model of a cerebral arteriovenous malformation (AVM) has been developed that closely resembles a human AVM of the brain. The creation of such a model requires sophisticated neurointerventional techniques. The purpose of this study was to develop a simple and cost-effective AVM animal model that does not require additional endovascular techniques. METHODS: A surgical anastomosis was created in seven sheep between the common carotid artery and the ipsilateral jugular vein, followed by ligation of the jugular vein above the anastomosis and of the proximal common carotid artery below the anastomosis. The anastomosis was created on the left side in four animals and on the right side in three. Cerebral angiography from the contralateral carotid artery was performed before and immediately after surgery to delineate the relevant cerebral vascular anatomy and to determine the direction of blood flow. RESULTS: An angiographic appearance simulating an AVM was found in all the animals. The ramus anastomoticus and arteria anastomotica functioned as the feeding vessels to the rete mirabile, which represented the nidus in our model, and to the jugular vein, which represented the draining vein from the malformation. Extensive collateral flow through the rete mirabile into the distal segment of the external carotid artery above the ligature was observed angiographically, with retrograde flow through the surgical anastomosis into the jugular vein. CONCLUSION: A simple surgically created experimental model for cerebral AVMs was developed in sheep without the need for additional complex endovascular catheter manipulations of intracranial branches. Such an animal model can substantially reduce the cost of research and training in the neurointerventional or radiosurgical management of AVMs.     

Mathematical analysis of 51Cr-labelled red cell survival curves in congenital haemolytic anaemias

The parameters of ⁵¹Cr labelled red cell survival curves were calculated in 33 patients with homozygous -thalassaemia, 8 with sickle-cell anaemia and 3 with s--thalassaemia, using a non-linear weighted least squares analysis computer program. In thalassaemic children the calculated parameters denote that the shortening of the mean cell life is due to early senescence alone, while there is some evidence that in thalassaemic adults additional extracellular destruction mechanisms participate as well. Red cell survival curves from patients with sickle-cell anaemia and s--thalassaemia resemble each other, while their parameters indicate an initial rapid loss of radioactivity, early senescence and the presence of extracellular red cell destruction factors.N.R.C. Democritos     

Immunohistological investigations of autopsied carotid bodies and their application to diagnosing strangulation

Summary Using immunohistochemical staining, the histological changes and the presence of neuropeptides (enkephalin and VIP) in the carotid body have been investigated in medico-legal autopsy cases, especially asphyxia cases. Only in cases of manual and/or ligature strangulation cases that sustained a force near the carotid body, were the chief cells mainly lightly stained, indicating that they had been active cells. Furthermore, these cells and their nuclei were enlarged in comparison to the chief carotid body cells in other autopsy groups. It was thus felt that these changes had resulted from the force that had directly affected the carotid body. Based on these findings, it was concluded that immunohistochemical investigation of the carotid body offers a useful possibility for diagnosing manual asphyxia, especially in autopsy cases involving strangulation.     

Scintimammography with 99mTc-MIBI and magnetic resonance imaging in the evaluation of breast cancer

This study was performed to evaluate the sensitivity and specificity of technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) scintimammography (SMM) and contrast-enhanced magnetic resonance imaging (MRI) in patients with breast masses, using the histological findings as the gold standard. Forty-five consecutive patients with a breast lesion, detected by self-examination, physical examination or screening mammography, underwent SMM and MRI. In 38 cases (84.5%), the histopathology was malignant; the breast cancers ranged from 3 to 100 mm in diameter (mean 22 mm). In the overall patient group, MRI showed a slightly higher sensitivity than SMM (92% vs 84%), but SMM showed a better specificity: 71% vs 42%. The accuracy was 82% and 84% for SMM and MRI respectively. To evaluate the influence of lesion size on the results, patients with lesions 20 mm and 15 mm were examined. In patients with lesions 20 mm, the sensitivity of SMM and MRI decreased to 64% and 82% respectively, while SMM again displayed considerably better specificity: 83% vs 50% for MRI. The accuracy of SMM and MRI was 64% and 82% respectively. In patients with lesions 15 mm, SMM again showed better specificity (75% vs 50%), while MRI displayed better sensitivity and accuracy (sensitivity, 81% vs 62%; accuracy, 75% vs 65%). In this study the specificity of SMM in patients with breast lesions was thus superior to that of MRI. The combination of SMM and MRI may be used in those patients with equivocal findings at mammography and ultrasound to reduce the number of unnecessary surgical biopsies.     

经导管肾动脉节段性栓塞治疗肾动静脉畸形

目的：探讨经导管肾动脉节段性栓塞治疗肾动静脉畸形的栓塞材料及其效果。方法：9例因肾动静脉畸形（先天性者8例，获得性者1例）引起大量血尿患者，施行经导管肾动脉节段性栓塞治疗10次，栓塞材料为无水乙醇、聚乙烯醇颗粒、异丁基-2-氰基丙烯酸酯和弹簧圈。9例患者术后随访观察10-56个月。结果：9例患者栓塞术后肾动脉造影显示畸形血管完全闭塞，3d内血尿消失。随访期间，9例患者中，只有1例单纯应用弹簧圈栓塞患者术后6个月血尿复发，血管造影证实为侧支血管形成导致畸形血管再通，改行无水乙醇及弹簧圈栓塞，术后18个月血尿未再复发。9例患者均无严重并发症发生。结论：经导管肾动脉节段性栓塞是治疗肾动静脉畸形的安全有效的方法，栓塞材料以无水乙醇和弹簧 圈联合栓塞为最佳。     

The two-in-one model: a new variation of the arteriovenous malformation model in swine

We report a new variation of the well-established experimental arteriovenous malformation (AVM) model in swine. To provide high flow through the rete mirabile (nidus, RM) and thereby to reduce the rate of spontaneous thrombosis of the AVM, we performed an end-to-end anastomosis of the left common carotid artery (CCA) and the external jugular vein (EJV) microsurgically in three micropigs. After 1 and 4 months the animals underwent angiograms of the CCA and vertebral artery (VA). In all cases the diversion of the blood through the RM was patent, up to the 4 months follow-up. We observed an arteriovenous fistula (arteriovenous pseudomalformation, pAVF) between the VA and the EJV in each case at both 1 and 4 months. This modification of the well-known AVM model in the micropig could be used to monitor long-term changes after embolisation, avoiding the naturally high rate of spontaneous thrombosis. This two-in-one model is thus well suited for preclinical testing of embolic materials. Received: 2 December 1999 Accepted: 31 August 2000     

The myth of the rete mirabile in man

Summary A case is reported with narrowing of both of the carotid arteries in the neck extending to involve the vessels intracranially. A hypervascularized area surrounds the markedly attenuated carotid siphons. This condition was at first considered to be an example of the rete mirabile in man, but careful study disproved this view. The investigation and subsequent clarification of this fascinating mythological organ, as far as man is concerned, is reported. We have hoped by this report to make it clear why the use of the term rete mirabile, as has been practiced by many contemporary clinical workers, should be discontinued if only for the sake of accuracy. The collaterals between the external and internal carotid systems which have been observed in humans by angiography have no similarity either in gross anatomical characteristics, and certainly not in histological features, with the carotid rete which has been demonstrated so beautifully by Davis and Story, Daniel, Dawes and Pritchard and by Gillilan and Markesbery in sheep, cats, goats, oxen and pigs. The rete mirabile has never been dissected out in man, much less examined under the microscope, since it does not exist in the human. So, we would plead for the elimination of the term rete mirabile from use in clinical medicine until this structure of such fascinating personality and discreet structure in animals, has been demonstrated in man, not radiographically, but by gross anatomical and histological methods.

---

Der Mythos des Rete mirabile beim Menschen

Zusammenfassung Die Verfasser besprechen ausführlich das Problem des Rete mirabile, das beim Menschen weder anatomisch noch histologisch nachgewiesen werden kann. Sie fordern, daß dieser Ausdruck in der klinischen Medizin nicht mehr verwandt wird.

---

Le mythe du rete mirabile chez l'homme

Résumé Les auteurs rapportent un cas de rétrécissement des deux artères carotides au niveau du cou, rétrécissement tendant á s'étendre aux vaisseaux intracrâniens. Une zone hypervascularisée entoure les siphons carotidiens qui sont fortement rétrécis. Cette condition était initialement considérée comme exemple du rete mirabile chez l'homme, mais une étude attentive refuta ce point de vue. Les auteurs rapportent l'exploration et la clarification consécutive de cet organe mythologique fascinant en ce qui concerne l'homme. Ils espèrent par ce travail, expliquer l'emploi du terme rete mirabile par beaucoup de cliniciens contemporains et pourquoi il convient de l'abandonner ne serait-ce que pour des raisons d'exactitude. Les collatérales entre les systèmes carotidiens externe et interne observés chez l'homme par angiographie ne présentent aucune analogie ni du point de vue anatomique, ni certainement du point de vue histologique avec le rete carotidien si bien démontré par Davis et Story, Damil, Dawes et Pritchard et par Gillilan et Markesbery chez les moutons, les chats, les oies, les boeufs et les cochons. Le rete mirabile n'a jamais été disséqué chez l'homme, encore moins examiné au microscope, puisqu'il n'existe pas chez l'homme. Les auteurs désirent donc voir abandonner le terme de rete mirabile dans la médecine clinique jusqu'á ce qu'on ait réussi á démontrer chez l'homme l'existence de cette structure si currieuse et sie discrète chez l'animal et ceci, non par la radiologie, mais par des méthodes anatomiques et histologiques.

     

Bilateral segmental regression of the carotid and vertebral arteries with rete compensation in a Western patient

We report a case of symptomatic symmetrical, bilateral absence of the cavernous internal carotid (ICA) and transdural vertebral artery (VA) segments with formation of a rete mirabile. There have been similar reports in Asian patients; ours is the first in the Western population. A 29- year-old woman presented with recurrent temporary blindness and an episode of minor subarachnoid haemorrhage. Angiography demonstrated absence of the C5 and C6 segments of the ICA and the C1/2 segments of the VA bilaterally, with typical carotid rete mirabile formation to reconstitute the distal flow. Comparative anatomy and embryology show retia in several species and point to their secondary origin. The anomalies of the ICA cannot be called agenesis but rather absence since they are likely to result from perinatal disappearance of the artery rather its failure to develop.     

Progressive cerebral arterial occlusive disease: Analysis of 27 cases

Summary Neuroradiologic findings of 27 cases of multiple progressive intracranial arterial occlusion (Taveras) are reported. The cause of stenotic process remains uncertain, but the disease in all probability is an acquired one and not a congenital dysplasia. Narrowing of the cervical internal carotid artery is secondary to a decreased blood flow. Deep central vascular network represents extraordinarily developed collateral channels.

---

Progressive cerebrale arterielle Verschlußkrankheit: Analyse von 27 Fällen

Zusammenfassung Es werden die Untersuchungsbefunde von 27 Patienten geschildert, bei denen eine arterielle cerebrale Verschlußkrankheit vorlag. Die pneumoencephalographischen Befunde, die angiographischen Befunde und die Veränderungen an den verschiedenen Gefäßabschnitten werden im einzelnen wiedergegeben. Die Verfasser kommen dabei zu der Ansicht, daß es sich bei dieser Erkrankung nicht um ein angeborenes, sondern um ein erworbenes Leiden handelt.

---

Maladie de l'occlusion progressive des artères cérébrales: Analyse de 27 cas

Résumé Les auteurs rapportent les caractéristiques neuro-radiologique dans 27 cas d'occlusions multiples et progressives des artères intra-crâniennes (Taveras). L'origine du processus sténosant reste incertaine, mais la maladie est vraisemblablement acquise et non une dysplasie congénitale. Le rétrécissement de l'artère carotide interne cervicale est secondaire à und diminution du flux sanguin. Les artères profondes représentent un extraordinaire réseau de circulation collatérale.

     

利用猪颅底奇网制作动静脉畸形模型的实验研究

目的 利用猪颅底奇网制作一种简单、经济的动静脉畸形模型.方法 通过显微外科手术,将猪一侧颈总动脉与颈内静脉或颈外静脉吻合,建成动静脉畸形模型.吻合术后行血管造影及组织学检查.结果 8头家猪手术后全部成活.血流自右侧咽升动脉流经奇网和对侧咽升动脉,进入颈内/外静脉.术后3周1头家猪死亡.另1头家猪1个月时吻合口闭塞.结论...     

Carotid bifurcation calcium and correlation with percent stenosis of the internal carotid artery on CT angiography

The aim of this paper was to determine the correlation between calcium burden (expressed as a volume) and extent of stenosis of the origin of the internal carotid artery (ICA) by CT angiography (CTA). Previous studies have shown that calcification in the coronary arteries correlates with significant vessel stenosis, and severe calcification (measured by CT) in the carotid siphon correlates with significant (greater than 50% stenosis) as determined angiographically. Sixty-one patients (age range 50–85 years) underwent CT of the neck with intravenous administration of iodinated contrast for a variety of conditions. Images were obtained with a helical multidetector array CT scanner and reviewed on a three-dimensional workstation. A single observer manipulated window and level to segment calcified plaque from vascular enhancement in order to quantify vascular calcium volume (cc) in the region of the bifurcation of the common carotid artery/ICA origin, and to measure the extent of ICA stenosis near the origin. A total of 117 common carotid artery bifurcations were reviewed. A significant stenosis was defined arbitrarily as >40% (to detect lesions before they become hemodynamically significant) of luminal diameter on CTA using NASCET-like criteria. All significant stenoses (21 out of 117 carotid bifurcations) had measurable calcium. We found a relatively strong correlation between percent stenosis and the calcium volume (Pearsons r = 0.65, P<0.0001). We also found that there was an even stronger correlation between the square root of the calcium volume and the percent stenosis as measured by CTA (r= 0.77, P<0.0001). Calcium volumes of 0.01, 0.03, 0.06, 0.09 and 0.12 cc were used as thresholds to evaluate for a significant stenosis. A receiver operating characteristic (ROC) curve demonstrated that thresholds of 0.06 cc (sensitivity 88%, specificity 87%) and 0.03 cc (sensitivity 94%, specificity 76%) generated the best combinations of sensitivity and specificity. Hence, this preliminary study demonstrates a relatively strong relationship between volume of calcium at the carotid bifurcation in the neck (measured by CT) and percent stenosis of the ICA below the skull base (as measured by CTA). Use of calcium volume measurements as a threshold may be both sensitive and specific for the detection of significant ICA stenosis. The significance of the correlation between calcium volume and ICA stenosis is that potentially a score can be obtained that will identify those at risk for high grade carotid stenosis.Presented at the 41st Annual Meeting of the American Society of Neuroradiology, Washington D.C., 2003. Sean Casey, MD and Charles Truwit, MD are members of the Medical Advisory Board of Vital Images (Plymouth, Minnesota), the company that developed the Vitrea 2 software.     

Large vessel disease in Chinese patients with capsular infarcts and prior ipsilateral transient ischaemia

Summary Carotid angiography was carried out in 21 Chinese patients with acute capsular infarcts; all had had a previous ipsilateral transient ischaemic attack (TIA) or reversible ischaemic neurological deficit (RIND) during the preceding 6 months. Sixteen (group 1) showed lacunar capsular infarcts, and 5 (group 2) either giant lacunae or striatocapsular infarcts. Angiography showed that 81% of group 1 and all group 2 patients had ipsilateral severe stenosis or occlusion of either the M1 segment of the middle cerebral artery or the internal carotid artery. Ten group 1 patients and 3 group 2 patients also had contralateral intra- or extracranial carotid artery stenosis. Apart from hypertension, other risk factors such as hyperfibrinogenaemia, polycythaemia, and low HDL-cholesterol level seem to play a role. Haemorheological abnormalities in the presence of atherostenosis at the orifice of lenticulostriate arteries and/or artery-to-artery embolism might be the cause of infarcts in the majority of the patients. A fifth of patients had recurrent large ipsilateral infarcts. Thus capsular lacunar syndromes with prior ipsilateral TIA or RIND are not as benign as previously thought, and they should indicate more intensive studies including cerebral angiography, and more vigorous therapy.     

The MR appearance of endovascular embolic agents in vitro with clinical correlation

A spectrum of embolic agents including PVA, avitene, gelfoam, ethanol, IBCA, silicone microspheres, metal and platinum coils, and balloons containing contrast of HEMA were imaged in vitro at 0,3 Tesla using spin echo, gradient echo, and inversion recovery sequences. Signal intensities associated with these agents and changes created by addition of blood are presented. The in vitro model is also correlated with clinical MR material. Recognition of embolic materials is important to avoid confusion with persistent flow void, hemorrhage, or thrombus.     

Assessment of accuracy of renal artery stenosis grading in helical CT angiography using maximum intensity projections

The purpose of the study was to investigate whether visual inspection of maximum intensity projection (MIP) images is a reliable method for assessment of the severity of renal artery stenoses (RAS). Therefore, 20 RAS were investigated with helical CT. Native axial images and MIP images were analysed separately or in combination (two-step method). A phanton study was performed to investigate the influence of window setting on apparent stenosis severity. Accuracy for diagnosis of 50–69% and 70–99% RAS and the mean inter-observer agreement were 82.5%, 77.5% and 82.5% respectively, using study of MIP images alone, and 100%, 97.5% and 95% using the two-step method. The phantom study showed that the apparent severity of vascular stenoses on MIP images depends on the selected window centre values. It is concluded that combined evaluation of both MIP images and native axial images is more reliable than study of MIP images alone for assessing the severity of RAS. Correspondence to: L. Van Hoe     

Diagnosis of neuroendocrine tumours by retrospective image fusion: is there a benefit?

This study evaluated the use of image fusion in the preoperative staging of neuroendocrine tumors (NET) of the pancreas and the gastrointestinal tract (GIT). Thirty-eight patients suffering from a metastasized NET with location of the primary in the pancreas (n=15) or the GIT (n=23) were examined by somatostatin receptor scintigraphy (SRS) and computed tomography (CT). Consecutive image registration and fusion were performed using custom-built software integrated in AVS/Express (Advanced Visual Systems, Waltham, MA, USA). Registration was performed by a voxel-based algorithm based on normalized mutual information. Image fusion was feasible in 36/38 patients. A total of 87 foci were assigned to anatomical regions (e.g. gut, pancreas, liver, lymph node or others) by two independent observers in both SRS and SRS/CT fusion images. The assignments used a binary ranking system (1=definite, 0=not definite). These results were then retrospectively compared to the classification of the foci, based on postoperative histology or clinical follow-up. Imaging by SRS allowed a definite anatomical assignment in 57% (50/87) and 61% (53/87) of all lesions in the case of observers A and B, respectively. Image fusion improved the topographic assignment to 91% (79/87) and to 93% (81/87). The number classified as definite by both observers increased from 54% (47/87) to 86% (77/87). The increase in definite assignments was highly significant for both observers (P<0.0001 for each). In the case of foci classified as liver metastases, image fusion allowed improved assignment to the corresponding liver segment from 45% (18/40) to 98% (39/40) and from 58% (23/40) to 100% (40/40) by observers A and B, respectively. Furthermore, the improved assignment of foci classified as lesions by image fusion was relevant for therapy in 7/36 patients (19%). Therefore, the image fusion technique presented herein appears to be a very useful method for clinical routine.     

The “dense artery sign” — major cerebral artery thromboembolism demonstrated by computed tomography

Summary A 4 years review of high resolution thin slice (3–5 mm) computed tomography performed within 24 h after cerebral infarction revealed increased density in a major cerebral artery segment in 28 patients. Arteries affected were the vertebral and basilar artery in 6 and 8 patients, the sphenoid course of the middle cerebral artery in 13 cases and the extracranial internal carotid artery in 1 patient. In 35.7% of cases the so called dense artery sign provided earliest evidence of the ensuing infarction documented by CT controls in most patients. Angiography carried out in 8 patients, density caculations in the course of the affected vessel and resolution of the increased density on subsequent CT examinations suggest thrombembolism as the most likely etiology. In the clinical setting of acute stroke increased artery density encompassing the entire vessel diameter may serve as an early indicator of major cerebral artery occlusion and prompt angiographic investigation of a lesion potentially amenable to lysis.     

Unilateral cervical and petrosal segment agenesis of the internal carotid artery with rete mirabile

The carotid rete mirabile (RM) is a physiological network between the internal and external carotid arterial systems. In this paper, an extremely rare case is presented, in which internal–external carotid artery anastomoses and a dilated ascending pharyngeal artery, due to unilateral agenesis of the cervical and petrous segments of the internal carotid artery (ICA), is presented.     

Early-stage focal nodular hyperplasia: US/CT/MR features correlated with histology

Two cases of local nodular hyperplasia (FNH), in which ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MR) studies detected an atypical hemorrhagic pattern associated with an intrahepatic arterio venous malformation (AVM) around the growths, are presented. In both cases, histology demonstrated a very early regenerative stage — without central scar or fibrosis — and necrotichemorrhagic areas within the lesions. In these cases, the analysis of radiological findings, surgical specimens and histology seemed to confirm the pathogenetic hypothesis suggested by Wanless [1]: in normal liver parenchyma, a blood steal phenomenon due to congenital or acquired intrahepatic AVM — arterio portal or porto systemic shunt — could cause ischemic damaged, appering as a hemorrhagic necrotic area, the extent of which depends on the degree of residual portal supply (maintained in Case 1, and markedly reduced in Case 2 due to arterio portal shunting). The subsequent phase of repair could activate the regenerative-hyperplastic process, evolving into final fibrosis, which represents the mature pattern of FHN. Correspondence to: R. Golfieri