Neuroangiography with lohexol

lohexol is a new, non ionic water-soluble contrast agent undergoing early clinical trials in the United States. Using a doubleblind , parallel format, iohexol was compared with meglumine iothalamate (60 patients) for selective cerebral angiography, and with sodium meglumine diatrizoate (40 patients) for arch aortography. lohexol produced significantly less pain than meglumine iothalamate or sodium meglumine diatrizoate. There were no significant differences in terms of heart rate, blood pressure, or electrocardiogram (ECG) changes. Both produced a transient tachycardia and hypotension after arch aortography, but significantly less so with iohexol. No significant complications occurred. Film quality was comparable between contrast agents except for diminished motion artifacts with iohexol. lohexol appears to be a superior neuroangiographic contrast agent to current ionic drugs. Neuroang iography, involving th e selective injection of carotid and vertebral arteri es as well as flu sh injections of the aortic arc h, follows myelography as th e most frequent " invasive " neuroradiologic procedure performed. About 250,000 cerebral angiograms are ob tain ed yearly in the United States with the following complicati on rate: minor complications, 5% ; significant morbidity, 0.5%; and mortality, 0 .1 % [1, 2J. Adverse effects resulting from this procedure can be attributed to th e contrast media injected and / or tech nical , mechanical factors such as arterial damage and emboli. Essentially all neuroangiographic procedures are now performed with " modern " ionic contrast agents using a meglumine salt of either diatrizoate or iothalamate . Th e ad verse effects produced by these compounds are due to the ex treme hyperosmolality of the ionic constrast med ia and the inherent neurotoxicity of the drugs The purpose of thi s paper is to present th e results of our clinical evaluation of one of th ese new non ionic agents , iohexol. lohexo l is a neutral , non ionic , water-soluble, hydrostable contrast med ium with a molecular weight of 821 (iodine content 46.4%). lohe xo l has previously been shown to have a low order of neurotoxicity in animal studies and to be clinically acceptable in preliminary European studi es Subjects and Methods Selective Cerebral Angiography Sixty ad ult patients were randomly assigned to receive either iohexol (30 patients) or meglumine iothalamate (30 patients). Each patient received only one contrast medium for his neuroangio graphic workup. The contrast medium was placed in the injector by an assistant, so that the agent used was unknown to the investigator and patient. The patients were premedicated with atropin e (0.4 mg) and nonnarcotic sedatives, usually Valium 2.5-7.5 mg intravEO nously. To be included in the study, a patient required selective carotid and / or vertebral angiography on clinical grounds, was 1 U years of age or older, and was not pregnant. Patients who were incapable of judging pain, allergic to iodine-containing drugs, pre vious recipients of contrast injection w ith in 48 hr, had serum cre atinine levels of greater than 3 mg / dl, or required emergen c l procedure were excluded from the study . Serum creatinines were obtained 24 hr and immediately befor ' cerebral angiography and 24 hr after the procedure . Vital sign; including oral temperature, pulse rate, and supine blood pressur,) were recorded 30 min before the first injection and 15 min, 3 hr and 24 hr after the final contrast injection. A brief neurologh. examination was also performed at these times. Neurologic statu; was also evaluated after each injection with motor function , visior . and speech specifically tested . Clinically appropriate selective injections were made with dose ; of 10-20 ml for common carotid, 10 ml for internal carotid, 5-8 n,1 for external carotid, and 6-1 2 ml for vertebral injections. Anot hf r 50 ml of contrast agent was used for those patients requiring an aortic arch flush injection. While the aortic injections were peformed , they were not specifically evaluated in these results due t·) the limited number of injections. The iohexol had a concentration (,f 300 mg I/ ml while the meglumine iothalamate had a concentration of 290 mg I/ ml. Immediately before and for 1 min after each injection , stri,) recordings of the electrocardiogram (ECG) and arterial blood pre5-sure were made. The blood pressure was obtained through t h ,~ injection catheter. Systolic and diastol ic blood pressure, pulse ratc Q-T intervals, ST segment, and T -wave amplitudes were specifical y evaluated for change. After each injection , the patient was asked to describe the typ of discomfort experienced (heat, pain, etc.) and the degree t f discomfort on a scale of 1-4 (1 = no reaction; 2 = slight discomfor' ; 3 = definite but tolerable discomfort; 4 = severe excruciatirg discomfort). The radiologist performing the injection also evalu ated the patient's response on a scale of 1-4 (1 = no response ; 2 ~ slight discomfort with mild visible and/or audible signs of discor'lfort; 3 = moderate discomfort with definite visible and audib.e signs; 4 = severe with evidence of definite patient distress). TI ~ radiologist performing the procedure also evalu ated the im ag il 9 effectiveness on a scale of 1-4 (1 = no visualization; 2 = po r visualization ; 3 = good visualization; 4 = excellent visu alizati ol )