delayed ischemic neurologic deficits secondary to vasospasm are a major cause of morbility and mortality after subarachnoid hemorrhage ( sah ) . treatment of vasospasm after sah is associated with complications , and reliable techniques for evaluating effects of treatment of vasospasm in such patients are warranted . we present the use of perfusion computed tomography ( ptc ) to evaluate the effect of transluminal percutaneous angioplasty in a with sah and vasospasm - induced ischemiia . dynamic pct with deconvolution produced maps of time - to - peak , mean transit time , regional cerebral blood flow , and regional cerebral blood volume , with a computerized automated map of the infarct and penumbra . before angioplasty and intraarterial papaverine , pct showed normal to decreased cerebral blood flow and increased cerebral blood volume and mean transit time in the middle cerebral artery territory of the left hemisphere . pct can be a useful technique in monitoring angioplasty treatment effects in patients with vasospasm after sah . delayed ischemic neurologic deficits secondary to vasospasm are a major cause of morbidity and mortality after subarachnoid hemorrhage ( sah ) ( 1 ) . the development of vasospasm can be recognized by neurologic deterioration in combination with radiological techniques , such as conventional digital subtraction angiography ( dsa ) , transcranial doppler ( tcd ) ultrasound , positron emission tomography ( pet ) , single - photon emission computer tomography ( spect ) , and single - slice perfusion computed tomographic technique ( xe - ct ) ( 16 ) . two recent studies showed that perfusion ct ( pct ) also represents an accurate screening test in patients with suspected vasospasm , although further refinements are needed before routine recommendation ( 6,7 ) . once symptomatic vasospasm is evident ( with focal neurologic signs ) , hemodynamic augmentation is widely employed , although definitive evidence for this therapy is still lacking ( 1,8,9 ) . patients whose condition does not improve with medical therapy undergo cerebral angiography and transluminal angioplasty ( 1,1012 ) . hemodynamic augmentation has a complication rate of 1020% and balloon angioplasty may be complicated by vessel rupture , branch occlusion , and hemorrhagic infarction ( 1,811 ) . therefore , accurate monitoring of treatment effects in patients with vasospasm after sah is needed . we report the results of the use of pct to evaluate the effect of transluminal percutaneous angioplasty and intraarterial papaverine in a patient with sah and vasospasm - induced ischemia . a 37-year - old woman was admitted with severe sudden headache , nausea , vomiting , and neck stiffness ( hunt & hess grade ii ) . unenhanced ct showed sah predominantly in the left sylvian fissure and over the left lateral convexity ( fisher grade 3 ) . dsa showed a left internal carotid artery tip aneurysm , which was treated with endovascular coil placement ( guglielmi detachable coils , boston scientific , cork , ireland ) . after the procedure she had mild headache and no neurological deficits . on the fourth day after coil placement , however , she de veloped aphasia . pct was performed 6 days after coil placement to determine if there was brain tissue at risk for cerebral infarction . ct scanners with quadruple detector array were used before and after angioplasty . for pct , we used a technique described previously ( 3,4,7 ) . in summary , after unenhanced ct of the brain , pct was performed twice at two different levels , at the roof of the third ventricle and at the roof of the lateral ventricles . for each examination 40 ml of a nonionic contrast agent ( iodixanol , visipaque 320 mg of iodine per ml , ge health , cork , ireland ) were injected with a power injector into a cubital vein at a rate of 4 ml / second . at 7 seconds after initiation of the injection , a continuous scan was started with the following parameters : 80 kv , 100 ma ( sensation 4 ) or 90 kv , 120 ma ( mx8000 ) , 4  5-mm collimation , 1 second per rotation for 46 seconds . . image - postprocessing involved placement of the region of interest ( roi ) in an input artery ( anterior cerebral artery ) and an input vein ( torcular herophili or superior sagittal sinus ) and subsequent generation of contrast - enhancement curves . the software generated color - coded cerebral blood flow ( cbf ) , cerebral blood volume ( cbv ) and mean transit time ( mtt ) maps based on the ct time attenuation curves for each pixel . after large vessel removal , four circular rois of 1.5 cm in diameter were placed along the cortical mantle of each hemisphere in the middle cerebral artery ( mca ) territory on the perfusion maps to generate quantitative data . cbf , cbv , and mtt values in the normal right hemisphere were compared with those of the affected left hemisphere . pct showed areas of normal or decreased cbf and a large area of increased cbv and mtt in the mca territory of the left hemisphere ( figure 1a - c ) , consistent with ischemia - related activation of autoregulation . the mean value of cortical cbf measured in the mca territory of the right ( normal ) hemisphere was 77 ml per 100 g and per minute ( range : 40174 ) . the mean value of cortical cbf in the left ( affected ) hemisphere was 31 ml per 100 g and per min ( range : 1338 ) . the mean value of cortical cbv measured in the right ( normal ) hemisphere was 1.4 ml/100 g ( range : 1.11.8 ) . the mean value of cortical cbv in the left ( affected ) hemisphere was 4.7 ml/100 g ( range 3.96.0 ) . the mean value of cortical mtt measured in the right ( normal ) hemisphere was 1.2 seconds ( range 0.61.9 ) . the mean value of cortical mtt in the left ( affected ) hemisphere was 9.6 seconds ( range 6.719.0 ) . 1pct was performed to determine if the patient was at risk for cerebral infarction and whether transluminal angioplasty should be performed or not ( a  c ) and was repeated after angioplasty to monitor treatment effects on cerebral perfusion ( d  f ) . ( a ) preangioplasty pct cbv map demonstrates increased cbv values in the left hemisphere , consistent with ischemia - related activation of cerebral autoregulation ( blue to red : cbv = 0 to 20 ml/100 g ) . ( b ) preangioplasty pct mtt map demonstrates increased mtt values in the left hemisphere , consistent with ischemia - related activation of cerebral autoregulation ( red to blue : mtt = 0 to 15 seconds ) . ( c ) preangioplasty pct cbf map demonstrates normal to decreased cbf values in the left hemisphere ( blue to red : cbf = 0 to 100 ml per 100 g and per minute ) . ( d ) postangioplasty pct cbv map demonstrates normalized cbv values in the left hemisphere , symmetric to the normal right side . ( e ) postangioplasty perfusion ct mtt map demonstrates normalized mtt values in the left hemisphere , symmetric to the normal right side . ( f ) postangioplasty pct cbf map demonstrates normalized cbf values in the left hemisphere , symmetric to the normal right side . pct was performed to determine if the patient was at risk for cerebral infarction and whether transluminal angioplasty should be performed or not ( a  c ) and was repeated after angioplasty to monitor treatment effects on cerebral perfusion ( d  f ) . ( a ) preangioplasty pct cbv map demonstrates increased cbv values in the left hemisphere , consistent with ischemia - related activation of cerebral autoregulation ( blue to red : cbv = 0 to 20 ml/100 g ) . ( b ) preangioplasty pct mtt map demonstrates increased mtt values in the left hemisphere , consistent with ischemia - related activation of cerebral autoregulation ( red to blue : mtt = 0 to 15 seconds ) . ( c ) preangioplasty pct cbf map demonstrates normal to decreased cbf values in the left hemisphere ( blue to red : cbf = 0 to 100 ml per 100 g and per minute ) . ( d ) postangioplasty pct cbv map demonstrates normalized cbv values in the left hemisphere , symmetric to the normal right side . ( e ) postangioplasty perfusion ct mtt map demonstrates normalized mtt values in the left hemisphere , symmetric to the normal right side . ( f ) postangioplasty pct cbf map demonstrates normalized cbf values in the left hemisphere , symmetric to the normal right side . on the same day as the pct , angioplasty was performed under general anesthesia with full heparinization via a transfemoral approach using an over the wire ( transend 0.010 in , target therapeutics / boston scientific , boston , ma ) silicone balloon microcatheter ( sentry , target therapeutics / boston scientific , fremont , ca ) , according to a technique described previously ( 11,15 ) . before angioplasty , dsa showed severe vasospasm of the m1 segment of the left mca and of the proximal left m2 segments ( figure 2a ) . after angioplasty of the m1 segment of the left mca a good angiographic result was obtained ( figure 2b ) . in addition , 150 mg of papaverine ( papaverine hydrochloride , eli lilly and co. , indianapolis , in ) was infused via a microcatheter in the left mca to treat spasm of the proximal m2 segments . within 2 days , pct was repeated and showed symmetric , normalized cbv , cbf , and mtt values ( figure 1d - f ) . dsa images in a 37-year - old woman who developed progressive aphasia 1 day after coiling of a ruptured left internal carotid arterytip aneurysm , despite optimal medical treatment . a ) preangioplasty dsa demonstrates severe vasospasm in the m1 and m2 segments of left mca . ( b ) postangioplasty dsa shows return to normal caliber of the m1-segment of the left mca . this case illustrates the value of pct in demonstrating the effect of transluminal balloon angioplasty on cerebral perfusion in a patient with vasospasm after sah . before angioplasty , decreased to normal cbf and increased cbv and mtt were identified in the left mca territory , indicating tissue at risk for cerebral infarction with intact autoregulation . cerebral vasospasm is a frequent complication in patients with aneurysmal sah ( 1 ) . in 50% of cases it is manifested by delayed neurologic deficits related to ischemia , with progression to infarction in approximately one - half of the symptomatic cases ( 1,8 ) . angioplasty for vasospasm may significantly reduce morbidity and mortality if performed early after medical therapy has failed ( 1,10 ) . it is , albeit rarely , also associated with severe complications , such as vessel rupture , and should therefore only be used in those patients in whom vasospasm causes cerebral ischemia ( 1,8 ) . because delayed neurologic deficits following sah may have different causes , including hydrocephalus , hemorrhage , edema , metabolic factors , and ischemia ( 12 ) , it is important to identify those patients with vasospasm who most likely will benefit from angioplasty . although tcd may aid in the determination of vasospasm , it does not necessarily assist in the identification of ischemia ( 12 ) . spect ( 2 ) , xe - ct ( 3 ) , and pet ( 4,5 ) are reliable methods for the determination of cerebral perfusion , but these techniques are cumbersome and not widely available . pct can be combined with unenhanced ct , which is routinely performed for follow - up of patients with sah ( 7 ) . they found significant differences in cbf and cbv between patients with significant and absent or minor vasospasm and between patients with and without a presumed vasospasm - related infarct . they could not , however , define a pct - threshold for cerebral infarct by using pct , because of the use of relatively large rois , causing volume averaging with normal and ischemic tissue ( 6,16 ) . the findings of the current report are consistent with results described by grubb et al . the system of autoregulation is reflected by pct findings in patients with cerebral ischemia ( 18 ) . a mild reduction in cerebral perfusion pressure is associated with a compensatory dilatation of cerebral blood vessels . under these circumstances , measurements of cbf pressure falls , normal cbf can not be maintained , despite further vasodilatation ( oligemia or misery perfusion ) . when perfusion pressure falls below a threshold of approximately 20 ml per 100 g and per minute , cerebral metabolism is severely impaired ( ischemia ) . the development of subsequent irreversible damage ( infarction ) is not only dependent on the absolute perfusion value but also on the time the tissue has been ischemic . irreversible damage is associated with loss of autoregulatory vasodilatation and therefore reduced cbv ( 18 ) . pct may also be valuable in detecting subclinical ischemia , i.e. , areas of vasospasm which are still asymptomatic owing to intact autoregulation but may become symptomatic over time . further research is warranted to determine if angioplasty of spastic vessels supplying these areas may improve outcome of patients with sah . pct has several limitations , including restricted anatomic coverage and lack of full validation of its accuracy , reliability , and reproducibility of quantitative results ( 7,16,19,20 ) . with our multislice ct scanner , we were able to use a collimation of 4  5 mm and to obtain 2  10 mm reconstructed slices . by performing pct at two different levels with 16- , 32- and 64-slice ct scanners , a larger brain coverage will be possible . quantitation is strongly dependent on the choice of the venous roi location ( 19,20 ) . different roi locations within the same vein may result in significantly different cbv and cbf values ( 19 ) . the venous roi with the greatest peak enhancement value should be chosen , as is done in the software used in this study to limit variability and increase quality of pct images ( 19 ) . with proper roi selections a good correlation between quantitative pct maps and xenon - ct and positron emission tomography ( pet ) studies was found , as described in previous reports ( 3,5 ) . this case illustrates the value of pct for monitoring treatment effects in patients with symptomatic vasospasm .
introductiondelayed ischemic neurologic deficits secondary to vasospasm are a major cause of morbility and mortality after subarachnoid hemorrhage ( sah ) . 
 treatment of vasospasm after sah is associated with complications , and reliable techniques for evaluating effects of treatment of vasospasm in such patients are warranted . 
 we present the use of perfusion computed tomography ( ptc ) to evaluate the effect of transluminal percutaneous angioplasty in a with sah and vasospasm - induced ischemiia.methodsdynamic pct with deconvolution produced maps of time - to - peak , mean transit time , regional cerebral blood flow , and regional cerebral blood volume , with a computerized automated map of the infarct and penumbra . 
 ct scanners with quadruple detector array were used before and after angioplasty.resultsbefore angioplasty and intraarterial papaverine , pct showed normal to decreased cerebral blood flow and increased cerebral blood volume and mean transit time in the middle cerebral artery territory of the left hemisphere . after angioplasty and intraarterial papaverine 
 , pct showed normalization of perfusion parameters.conclusionpct can be a useful technique in monitoring angioplasty treatment effects in patients with vasospasm after sah .