I . . . . Comparative Double-Blind Investigation of Meglumine Metrizoate, Metrizamide, and lohexol in Carotid Angiography

The new non ionic contrast medium iohexol (Omnipaque) was compared with its predecessor metrizamide (Amipaque) and with the conventional ionic medium meglumine metrizoate (Isopaque Cerebral) in carotid angiography using a double-blind crossover technique. The results indicated that iohexol and metrizamide caused less discomfort than the ionic medium. The circulatory effects of the three media were generally mild, and the diagnost ic effectiveness was comparable when the iodine concentration was kept in the range of 280-300 mg I/mi. The research concerned with contrast media for vascular use during recen t years has focused on th e syn thesi s of nonionic monomeri c compo unds . The prototype for these co mpou nd s is metrizamide (Amipaque) , which is now extensively used in many different diagnostic procedures . However, this medium has two definite drawbacks: it has a very hi gh production cost, and it is packaged as a lyophilic powder that has to be dissolved separately for every examination . lohexol (Omnipaq ue), a recently synthetized compound , does not have these disadvantages. The principal aim of this study was to compare the safety, tolerance, and usefuln ess of metrizamide and iohexol in carotid angiography with the co nven ti onal standard med ium meglumine metrizoate (lsopaque Cerebral, referred to in thi s paper as metrizoate). Anoth er objective of th e study was to compare th e two nonionic media in order to find out if iohexol might repl ace metrizamide as safely as animal studi es [1] and phase II noncomparative trials [2] seem to indicate. For these reasons a test model was designed th at allows for high sensitivity and cross-checking of results while at th e same time being easily appli cab le to routine angiography . Subjects and Methods Among patients referred for ce rebral ang iog raphy, 110 fully conscious and cooperative adu lts were selected. All patients except one ag reed to participate after thorough explanation of the test, which was performed as a double-blind crossove r investigation . The patients were split into three groups. The first 52 pati ents (group 1) were given meglumine metrizoate (280 mg I/ ml) and metrizamide (280 mg I/ ml); the next 30 (group 2) meglumine metrizoate (280 mg I/ ml) and iohexo l (3 00 mg I/ ml); and th e last 28 (group 3 ) metri zamide (300 mg I/ ml) and iohexol (300 mg I/ ml) . (Th e iodine co ncentrati on was not th e same in all groups for produ cti on reasons.) Group 1 co nsisted of 26 men (mean age 52 years, range 17-70) and 26 wo men (mean age 42 years, range 17-69); group 2 co nsisted of 13 men (m ean age 42 yea rs, range 26 -64) and 17 women (m ean age 45 years , range 25-74); and group 3 of 12 men (mean age 47 years, range 37-64) and 16 wom en (mean age 47 years, range 26-73). Th e diagnoses are li sted in table 1. In each patient th e two different co ntrast med ia being used were administered at th e beginning of the angiog raphic procedu re. Rapid serial exposures in th e lateral view were added in ord er to assess ci rcul ati on tim e. Th e order of th e injec ti ons was randomi zed acco rding to a code li st and remained unknown to th e examining physic ian and to the pati ent. Premedication was 0 .5 mg atropin e and 10 mg d iazepam . The examinations we re ca rri ed out under local anesthesia. Cath eterizat ion was perform ed via the femoral route in most cases, althoug h a few patients we re examined after direct puncture of th e internal ca rotid artery. With few excepti ons th e co ntrast med ia injecti ons were made with the tip of the cath eter in th e intern al caro tid artery (table 2). In this artery 8 ml of co ntrast medium was injected , whi le for injections of th e common artery 10 ml was used . Th e media were at room temperature at injecti on. Averag e injecti on tim es for the different media and groups were: group 1 : 1 .1 sec for both metrizoate and metri zam id e; group 2: 1.2 sec for metri zoate and 1.3 sec for iohexol; and group 3 : 1 .2 sec for both metrizamide and iohexo l. The electrocardiogram (ECG) was record ed on an ink-writer fro m extremity lead II , and was monitored before, during, and up to 60 sec after every injection. On parall el c hannels of th e ink-writer th e injecti on times and the exposures were record ed. Th e bradycardial effect was defined as th e difference in milli second s between th e longest R-R interval before and after injectio

Interactive use of cerebral angiography and magnetoencephalography in arteriovenous malformations: Technical note

OBJECTIVE: To minimize the risks associated with treating cortical cerebral arteriovenous malformations (AVMs), we developed a technique combining functional imaging and cerebral angiography. The functional loci obtained by performing magnetoencephalography (MEG) are projected onto stereoscopic pairs of a stereotactically derived digital subtraction angiogram. The result is a simultaneous three-dimensional perspective of the angioarchitecture of an AVM and its relationship to the sensorimotor cortex. METHODS: Eight patients underwent multimodality brain imaging, including magnetic resonance imaging, functional mapping via MEG, and stereotactic angiography using a modified Compass fiducial system (Compass International, Rochester, MN). The coordinates derived by performing MEG were superimposed onto stereotactic, stereoscopic, angiographic pairs using custom-made distortion correction and coordinate transfer software. RESULTS: The magnetoencephalographic angiogram allowed simultaneous viewing of the angioarchitecture of the AVM nidus, the feeding vessels, and the draining veins and their relationship to the normal cerebral vasculature and functional cortex. This imaging technique was particularly valuable in identifying en passant vessels that supplied functional cortex and was used during the treatment of these lesions. CONCLUSION: The techniques of MEG and cerebral angiography were combined to provide simultaneous viewing of both modalities in a three-dimensional perspective. This technique can aid in risk stratification in the management of patients with cerebral AVMs. In addition, this technique can facilitate the selective targeting of vessels, thus potentially reducing the risks associated with embolization of these formidable lesions