Perfusion Territories Research Articles

Relation Between Cerebral Perfusion Territories and Location of Cerebral Infarcts

The perfusion territories of the brain-feeding arteries are difficult to assess in vivo and therefore standard cerebral perfusion territory templates are often used to determine the relation between cerebral infarcts and the feeding vasculature. In the present study, we compared this infarct classification, using standard templates, with the individualized depiction of cerebral perfusion territories on MRI. The ethics committee of our institution approved the study protocol. A total of 159 patients (92 male, 67 female; mean age, 58.9 years) with first-time clinical symptoms of cerebral ischemia were included in the study. Diffusion-weighted imaging was used for depiction of the area of ischemia and the perfusion territories of the left internal carotid artery, right internal carotid artery, and vertebrobasilar arteries were visualized with territorial arterial spin labeling MRI. Infarct locations with respect to cerebral perfusion territories were evaluated with and without territorial arterial spin labeling MRI images. In 92% of the patients, the territorial arterial spin labeling images were of diagnostic quality. One hundred thirty-six patients showed areas of ischemia on diffusion-weighted images. The additional information from the territorial arterial spin labeling images changed the classification in 11% of the cortical or border zone infarcts (6 of 56), whereas no territorial changes were observed in lacunar, periventricular, cerebellar, and brainstem infarcts. The diagnostic information provided by perfusion territory imaging in patients with stroke is valuable for the classification of cortical and border zone infarcts, whereas no change of the textbook-based classification was observed for other infarct types.

Prognostic impact of microembolic signals in arterial sources of embolism

Sir I read with interest the review by Ritter et al. [3] regarding the prevalence and prognostic impact of microembolic signals (MES) in arterial sources of cerebral embolism. I wish to comment on some important issues related to this review. Emboli originating from an atherosclerotic stenotic plaque are considered to play an important etiological role in subsequent cerebral ischemic events [2], and the detection of MES may help in clinical decision-making, especially in patients previously considered to have asymptomatic arterial stenoses. However, this approach is still not widely accepted and appears to be looking at ‘only one side of the picture.’ Cerebral ischemic events secondary to hemodynamic disturbances (hypoperfusion) in patients with significant stenotic lesions constitute an important clinical group, and these patients can be easily evaluated with transcranial Doppler and assessment of cerebral autoregulation (CA). CA is the inherent ability of the cerebral blood vessels to maintain the blood flow over a wide range of systemic blood pressure and various provocative stimuli [6] and can be assessed by testing the vasomotor reactivity (VMR). Flow velocities obtained in real-time by TCD can reflect cerebral blood flow volume (CBFV), and the velocity changes can be proportionate to the changes in CBFV if certain parameters are known and remain constant (e.g., angle of insonation, perfusion territory, and arterial diameter) and the effect of only one stimulus is observed [5]. Evaluation of VMR to various ‘challenges’ and maneuvers may help in the prognostic assessment of patients with significant stenosis in the cervico-cranial cerebral arteries. Silverstrini et al. [4] demonstrated a significantly higher risk of subsequent cerebral ischemic events in patients with asymptomatic carotid stenosis and having impaired VMR, assessed by breath-holding index. VMR can be easily assessed by monitoring the blood flow velocities (by TCD) during voluntary breath-holding in any intracranial artery distal to the stenosis. Elevation of carbon-dioxide levels in blood during breath-holding is a strong vasodilatory stimulus and results in significant augmentation of flow velocities in the intracranial arteries. However, the arteries distal to the segment with significant stenosis tend to maintain maximal vasodilation and may not dilate further in response to hypercapnia, reflected by a blunted response in the blood flow velocities. The response may be further affected, in some cases, due to ‘intracranial steal phenomenon’ known as ‘reversed Robin Hood syndrome’ [1]. I propose that, in addition to the MES monitoring, patients with hemodynamically significant stenosis in the cervical or intracranial cerebral arteries should be evaluated for VMR by TCD. Assessment of VMR in the arterial segments distal to the atherosclerotic segment would reveal, at least to some extent, the ‘other side of the picture’ and help in better understanding of cerebral hemodynamics and the pathogenic mechanisms of cerebral ischemia in these patients. Well-designed prospective studies would, however, be needed to test the feasibility and efficacy of this approach in clinical decision-making.

Myocardial Microinfarction after Coronary Microembolization in Swine: MR Imaging Characterization

To use first-pass perfusion and delayed-enhanced (DE) magnetic resonance (MR) imaging for the detection of the early effects of coronary microembolization on myocardial perfusion and viability. Approval was obtained from the institutional committee on animal research. A hybrid x-ray and MR imaging system was used to guide the endovascular catheter and quantify the left anterior descending coronary artery (LAD) perfusion territory before microembolization and ischemic myocardium and microinfarction after microembolization. The embolic agent was selectively delivered in the LAD in six pigs. First-pass perfusion MR imaging was performed 1 hour and 1 week after microembolization. Microinfarction was measured on DE MR images in beating and nonbeating hearts (high-spatial-resolution sequence) by using extracellular and blood pool MR contrast media and after death. The Wilcoxon signed rank test and correlation analysis were used. The LAD perfusion territory was 35% of left ventricular (LV) mass +/- 2 (standard error of the mean). Microembolization caused perfusion deficit in 15.7% of LV mass +/- 2.6 compared with that of LAD territory (P = .03). At 1 week, perfusion parameters improved and the extent of hypoperfused territory declined (4.6% of LV mass +/- 1.4, P = .03). Microinfarction size expanded from 1.4% of LV mass +/- 0.2 at 1 hour to 7.5% of LV mass +/- 1.2 at 1 week. In nonbeating hearts and at triphenyltetrazolium chloride staining at 1 week, microinfarction size was 7.6% of LV mass +/- 1.4 and 7.2% of LV mass +/- 1.5, respectively. There was no correlation between the ejection fraction and the extents of microinfarction or hypoperfused territory. Histopathologic findings confirmed the presence of patchy microinfarction. Coronary microembolization caused persistent decline in myocardial perfusion at first-pass perfusion imaging. DE MR imaging has the potential to help reliably quantify subacute microinfarction. The magnitude of LV dysfunction is not related to the extents of microinfarction or hypoperfused territory.

XMR is a useful modality to guide, map and quantify the perfusion territories of coronary arteries

XMR is a useful modality to guide, map and quantify the perfusion territories of coronary arteries

Collateral Circulation Imaging: MR Perfusion Territory Arterial Spin-Labeling at 3T

Collateral Circulation Imaging: MR Perfusion Territory Arterial Spin-Labeling at 3T

Territorial and Microvascular Perfusion Impairment in Brain Arteriovenous Malformations

Both the existence and clinical relevance of a steal phenomenon in brain arteriovenous malformations (AVMs) remains a matter of debate. This study aimed to assess perfusion in the brain adjacent to brain AVMs and to relate these to macrovascular blood flow in a single measurement. Twenty consecutive patients with AVMs with a median age of 37 years were evaluated by 3T MR imaging by using 3D time-resolved MR angiography to determine blood flow and perfusion patterns. Cerebral perfusion was estimated by using an arterial spin-labeling technique in vascular territories around the nidus and in symmetric regions of interest in the ipsilateral and contralateral hemispheres. Mapping of concentric shells around the nidus was used to define the immediate and adjacent brain and relative perfusion reductions >20% of baseline, termed perinidal dip (PND). A significant reduction in perfusion ratios between ipsilateral and contralateral hemispheres remote to the AVMs was demonstrated in the middle and posterior cerebral artery territories. PND was detected in 5 patients, and 17 patients overall showed reduced perfusion in the perinidal region on visual inspection. There was a negative correlation of the hemispheric territorial perfusion with the affected/nonaffected inflow time ratio (R = -0.402, P = .015). The perfusion impairment in vascular territories adjacent to brain AVMs that we identified as PND may reflect the existence of 2 levels of perfusion impairment: a territorial and a microvascular perfusion disturbance. Although the hemispheric asymmetry in territorial perfusion seems the result of arterioarterial redistribution, the PND was inhomogeneously distributed within a single vascular territory and thus might result from low perfusion pressure in small arteries and arterioles.

Intracoronary Injection of Contrast Media Maps the Territory of the Coronary Artery: An MRI Technique for Assessing the Effects of Locally Delivered Angiogenic Therapies

The effects of locally delivered angiogenic factors or stem cells on the coronary artery perfusion territory are not well defined. Therefore, the aim of this study was to determine the ability of the selective injection of magnetic resonance contrast media (MR-CM) to map and quantify the territories of the major coronary arteries. Selective coronary catheterization (n = 16 pigs) was performed under x-ray and magnetic resonance imaging (MRI) fluoroscopy in an x-ray and magnetic resonance suite. Catheters were placed in the left anterior descending (LAD), circumflex, or right coronary artery. The coronary perfusion territories were mapped by the intracoronary injection of MR-CM using first-pass perfusion (FPP) and early contrast-enhanced (CE) MRI. Cine MRI was used to quantify left ventricular (LV) mass. In 12 animals, the LAD coronary artery was occluded by microspheres to create infarctions. Infarct size was measured on delayed enhanced (DE) MRI after the intravenous injection of MR-CM. X-ray and magnetic resonance fluoroscopy were successfully used to catheterize the coronary arteries. The perfusion territories of the coronary arteries were defined as hyperenhanced regions on FPP and CE MRI. The LAD coronary artery territory was 33.7 +/- 2.2% of LV mass on FPP MRI and 33.0 +/- 2.3% on CE MRI (P = .63). Bland-Altman analysis showed close agreement between the two methods (0.7 +/- 5.0%). DE MRI demonstrated the infarcted myocardium as hyperenhanced subregions of the perfusion territory (7.5 +/- 1.2% of LV mass). Interventional cardiac x-ray and magnetic resonance fluoroscopy can be used to map and quantify the perfusion territory of each coronary artery. This experimental method can be used before and after the local delivery of angiogenic factors and stem cell therapy to determine their efficacy.

Abstract 552: Posterior Involvement Attenuates Predictive Value of ST-Segment Elevation in Lead V4R for Right Ventricular Involvement in Inferior Acute Myocardial Infarction

ST-segment elevation (ST ↑) ≥1.0 mm in lead V4R is considered a reliable marker of right ventricular involvement (RVI) in inferior acute myocardial infarction (IMI). However, the impact of posterior involvement (PI) on the relation between RVI and ST ↑ in lead V4R is unknown. We studied 267 patients with a first IMI who had total occlusion and TIMI 3 flow of the right coronary artery within 6 h after the onset. A 12-lead ECG, lead V4R, and leads V7–9 were recorded on admission. RVI was defined as occlusion proximal to the first right ventricular branch. The perfusion territory was assessed by angiographic distribution score, and PI was defined as a score of ≥0.7. Myocardial blush grade was assessed immediately after reperfusion. Patients were stratified according to the presense or absense of PI and RVI. Times to admission and reperfusion were similar in the 4 groups. RVI was associated with higher peak creatine kinase and higher rates of impaired myocardial reperfusion (blush grade 0/1) and congestive heart failure during hospitalization in the presense or absense of PI, especially the former. RVI was associated with a higher rate of ST ↑ in lead V4R in the absence, but not in the presence, of PI. ST ↑ in lead V4R identified RVI with sensitivities of 34% and 96% (p<0.001) and specificities of 83% and 82% (NS) in the presence and absence of PI, respectively. In patients with reperfused IMI, RVI is associated with a larger infarct size and impaired myocardial reperfusion. However, the incidence of RVI diagnosed by ST ↑ in lead V4R was underestimated in the presence of posterior involvement. ST ↑ in lead V4R caused by RVI might be attenuated due to a reciprocal change in posterior ST ↑.

Abstract 2808: Combination of Adenosine Stress Perfusion and Late Enhancement Cardiac Magnetic Resonance Imaging in Patients with Suspected Coronary Artery Disease, Percutaneous Coronary Intervention and Coronary Bypass Graft -A Multi-Center Study

The combination of stress perfusion and late Gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) has been established for diagnosis of myocardial ischemia. However, little is known about this helpful clinical examination tool in patients who were treated by percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). Aim of our study was to compare the diagnostic accuracy of stress perfusion and LGE in patients with suspected coronary artery disease (CAD), with PCI and with CABG in a multi-center trial. 477 patients with suspected CAD, 209 with PCI and 110 with CABG were included to the study and underwent adenosine stress perfusion and LGE 10 min. after a second bolus of contrast agent. CMR images were assessed visually using the 16-segments model. Myocardial ischemia was defined as resgional hypoenhancement in stress perfusion with absent LGE. All patients underwent coronary angiography. A significant stenosis was defined by QCA in case of ≥70% of coronary artery or bypass graft narrowing in vessels ≥2 mm diameter. A relevant vessel stenosis or occlusion was present in 173 (36%) patients with susptectd CAD, 69 (29%) PCI and 71 (65%) CABG patients. PCI was performed 314±231 and CABG 423±275 days before CMR examination. Sensitivity, specificity and overall accuracy per patient are given in table 1 CMR is feasible and suitable for detecting relevant vessel stenosis in patients who previously were treated by PCI or CABG. Diagnostic accuracy is reduced in patients with CABG. This could be due to different flow and perfusion kinetic. Furthermore, presented evaluation method may be inadequate, since collaterals and different perfusion territories are not taken into consideration. CMR yields similar diagnostic accuracy in patients with suspected CAD and those who previously were treated by PCI.

2132 Assessment of myocardial oxygenation in the canine heart using blood oxygen level-dependent magnetic resonance imaging

Methods A T2-prepared SSFP sequence with T2and T2*-sensitivity was developed. Three anesthetized dogs were instrumented with a coronary infusion catheter in the circumflex coronary artery (LCX), an MR compatible epivascular flow probe around the LCX and a catheter in the coronary sinus. Using a clinical 1.5 T MRI system (Avanto, Siemens Medical Solutions, Germany), BOLD-sensitive imaging with the new sequence and additional T2* mapping were performed during LCX intracoronary infusion of adenosine and acetylcholine (ACh). The perfusion territory of the LCX was identified by intracoronary injection of a small Gd-DTPA bolus. Images were analyzed using validated software. Paired T-tests were used to compare results before and after intracoronary infusion. Correlations of BOLD signal intensity and T2* values in the LCX territory with coronary venous oxygen saturation (SaO2) were calculated by linear regression analysis (SPSS13).

Vascular adaptation of the internal thoracic artery graft early and late after bypass surgery

Flow mismatch between the supplying artery and the myocardial perfusion region has been observed in patients with internal thoracic artery grafts. Thus coronary flow changes of arterial (internal thoracic artery grafts) and saphenous (saphenous vein grafts) bypass grafts were studied early and late after coronary artery bypass grafting. Thirty patients undergoing elective bypass surgery (internal thoracic artery and saphenous vein grafts) were studied intraoperatively and (17 patients) 3 to 10 months postoperatively. Coronary flow was measured intraoperatively with the transit-time Doppler scanning technique. Postoperatively, flow velocity and coronary flow reserve were determined with the Doppler flow wire technique. Quantitative angiographic analysis was used to determine vessel size for calculation of absolute flow. Intraoperatively, internal thoracic artery graft flow was significantly lower than saphenous vein graft flow (31 +/- 8 vs 58 +/- 29 mL/min, P < .01). Postoperatively, internal thoracic artery graft flow increased significantly to 42 +/- 24 mL/min at 3 months and to 56 +/- 30 mL/min (P < .02 vs intraoperative value) at 10 months, respectively. However, saphenous vein graft flow remained unchanged over time (58 +/- 29 to 50 +/- 27 mL/min at 3 months and 46 +/- 27 mL/min at 10 months). Coronary flow reserve was abnormally low intraoperatively in the internal thoracic artery (1.3 +/- 0.3) and saphenous vein (1.6 +/- 0.5) grafts but increased significantly to normal values in both types of graft at follow-up. Bypass flow of the internal thoracic artery graft is significantly reduced intraoperatively when compared with that of the saphenous vein graft. However, 3 and 10 months after the operation, flow of the internal thoracic artery graft increases significantly and is similar to saphenous vein graft flow. This finding can be explained by an early flow mismatch of the native internal thoracic artery in the presence of a large perfusion territory. During follow-up, there is vascular remodeling of the internal thoracic artery, probably because of endothelium-mediated mechanisms.

Collateral Circulation Imaging: MR Perfusion Territory Arterial Spin-Labeling at 3T

Current knowledge of the collateral circulation remains sparse, and a noninvasive method to better characterize the role of collaterals is desirable. The aim of our study was to investigate the presence and distal flow of collaterals by using a new MR perfusion territory imaging, vessel-encoded arterial spin-labeling (VE-ASL). Fifty-six patients with internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis were identified by sonography. VE-ASL was performed to assess the presence and function of collateral flow. The perfusion information was combined with VE maps into high signal-intensity-to-noise-ratio 3-colored maps of the left carotid, right carotid, and posterior circulation territories. The presence of the anterior and posterior collateral flow was demonstrated by the color of the standard anterior cerebral artery/MCA flow territory. The distal function of collateral flow was categorized as adequate (cerebral blood flow [CBF] >/=10 mL/min/100 g) or deficient (CBF <10 mL/min/100 g). The results were compared with those of MR angiography (MRA) and intra-arterial digital subtraction angiography (DSA) in cross table, and kappa coefficients were calculated to determine the agreement among different methods. The kappa coefficients of the presence of anterior and posterior collaterals by using VE-ASL and MRA were 0.785 and 0.700, respectively. The kappa coefficient of the function of collaterals by using VE-ASL and DSA was 0.726. Apart from collaterals through the circle of Willis, VE-ASL showed collateral flow via leptomeningeal anastomoses. In patients with ICA or MCA stenosis, VE-ASL could show the presence, the origin, and distal function of collateral flow noninvasively.

Improved regional function after autologous bone marrow-derived stem cell transfer in patients with acute myocardial infarction: a randomized, double-blind strain rate imaging study

To investigate whether intracoronary transfer of bone marrow progenitor cells (BMPCs) early after reperfusion of an acute myocardial infarction improves regional myocardial function in a randomized double-blind, placebo-controlled strain rate imaging study. Regional myocardial deformation was measured using velocity-derived strain rate imaging in 67 STEMI patients randomized 1:1 to intracoronary infusion of BMPC (n = 33) or placebo (n = 34). Myocardial segments were grouped into infarct (n = 232), border (n = 250), and remote (n = 526) based on MRI-delayed enhancement and the perfusion territory of the infarct-related vessel. Four months after revascularization and progenitor cell/placebo transfer, regional myocardial deformation (rate) improved significantly more in the infarct segments of BMPC patients (treatment effect on end-systolic strain: -3.7 +/- 1.0%, P = 0.0003; peak-systolic strain rate: -0.20 +/- 0.07 s(-1), P = 0.0035). These findings were confirmed by a significantly greater improvement of longitudinal mitral valve ring displacement in the infarct walls of BMPC patients (treatment effect: 0.93 mm, P = 0.034). Intracoronary infusion of BMPC early after reperfusion of a STEMI improves recuperation of regional myocardial function at 4 months' follow-up. Quantitative assessment of regional systolic function might be more sensitive than global LV ejection fraction for the evaluation of BMPC therapy after STEMI.

Assessment of the Contribution of the External Carotid Artery to Brain Perfusion in Patients With Internal Carotid Artery Occlusion

The purpose of this study was to prospectively investigate the contribution of the ipsilateral external carotid artery (ECA) to cerebral perfusion in patients with internal carotid artery occlusion. Institutional Review Board approval and informed consent were obtained. Thirty functionally independent patients (24 men, 6 women; mean age, 63 years) with an angiographically proven unilateral internal carotid artery occlusion and transient or minor disabling ischemic attacks ipsilateral to the side of the internal carotid artery occlusion were included. Grading of ECA collateral flow was performed with intraarterial digital subtraction angiography. The contribution of the ECA to regional cerebral blood flow was assessed with selective arterial spin labeling MRI. Differences in regional cerebral blood flow were analyzed with Student t test. Twenty percent of the patients had ECA Grade 0 collateral flow (no filling of ophthalmic artery), 20% Grade 1 (filling of carotid siphon), and 60% Grade 2 (filling of anterior and/or middle cerebral artery) as demonstrated on digital subtraction angiography. Although in the Grade 1 group, the ECA supplied a smaller region of the brain compared with the Grade 2 group, the mean regional cerebral blood flow of the perfusion territory supplied by the ECA is similar (P=0.70) in the Grade 1 group (mean+/-SD 57+/-16 mL/min/100 g) and the Grade 2 group (60+/-12 mL/min/100g). In patients with symptomatic internal carotid artery occlusion, focal brain regions may strongly depend on the contribution to cerebral perfusion of the ECA ipsilateral to the side of the internal carotid artery occlusion, even in patients with limited ECA collateral supply as demonstrated on digital subtraction angiography.

Real‐time catheter‐directed MRA with effective background suppression and persistent rendering

To develop an imaging and visualization technique for real-time magnetic resonance angiography (rtMRA) fully integrated with a real-time interactive imaging environment on a clinical MR scanner. Intraarterial injections of contrast agent and imaging processing techniques were employed for rapid catheter-directed assessment of vessel patency and regional tissue perfusion. Operators can image multiple thin slices to maximize anatomic detail or use thick slice or projection imaging to maximize vessel coverage. Techniques in both pulse sequence and image processing were employed to ensure background suppression. Accumulation of maximum pixel values allows persistent display of bolus signal as it passes through the vessels and into tissues. Automatic brightness adjustment was used to ensure visibility at all stages of bolus passage. Experimental intraarterial rtMRA of coronary, renal, and carotid arteries show that vessel trajectories and perfusion territories are well visualized in swine. Switching between standard real-time imaging and rtMRA imaging after contrast injection was easy to perform during a procedure without stopping the scanner. The proposed technique facilitates visualization of intraarterial contrast injections using real-time MRI. Although designed for rapid deployment during rtMRI-guided interventional procedures, the technique may also be useful to supplement the study of vessel anatomy, flow, or perfusion.

Drug-eluting stenting of saphenous vein graft vs. native coronary artery of the same myocardial perfusion territory: a retrospective 12-month follow-up

Drug-eluting stenting of saphenous vein graft vs. native coronary artery of the same myocardial perfusion territory: a retrospective 12-month follow-up

Global and focal cerebral perfusion after aneurysmal subarachnoid hemorrhage in relation with delayed cerebral ischemia

The pathogenesis of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is unclear. We assessed whether DCI relates to focal or global cerebral perfusion on admission and on follow-up imaging. Twenty-seven SAH patients underwent computed tomography (CT) perfusion (CTP) on admission and at clinical deterioration or 1 week after admission in clinically stable patients. We compared global and focal (least perfused territory) perfusion in patients with DCI (n = 12), clinically stable patients (n = 7), and patients with non-DCI-related deterioration (n = 8). Global cerebral blood flow (CBF) increased on follow-up: 29% (95% confidence interval (CI) 15% to 43%) in patients with DCI, 12% (95%CI -1% to 25%) in stable patients, and 20% (95%CI 4% to 36%) in patients with non-DCI-related deterioration. Focal CBF decreased in patients with DCI, (-23%; 95%CI -58% to 12%) but increased in patients with non-DCI-related deterioration (23%; 95%CI -26% to 55%) and stable patients (7%; 95%CI -30% to 45%).On follow-up, global CBF was lower in patients with DCI (70.0 ml per 100 g/min) than in clinically stable patients (81.6; difference 11.6; 95%CI 0.8 to 22.5 ml per 100 g/min) but comparable to patients with non-DCI-related deterioration (67.6; difference -2.4; 95%CI -11.9 to 7.2 ml per 100 g/min). Focal CBF was lower in patients with DCI (30.7) than in clinically stable patients (53.6; difference 22.9; 95%CI 5.1 to 40.6 ml per 100 g/min) and patients with non-DCI-related deterioration (46.6; difference 15.9; 95%CI -2.6 to 28.4 ml per 100 g/min) Our results suggest that DCI is more likely a focal than a global process.

Clinical impact of MRI perfusion disturbances and normal diffusion in acute stroke patients

Purpose In acute ischemic stroke MR-imaging typically shows diffusion abnormalities surrounded by reduced perfusion signifying the so-called ischemic penumbra. Mismatch between diffusion and perfusion abnormalities gives indication for thrombolysis. But is there an indication for thrombolytic treatment, if there is no diffusion abnormality but pathologic perfusion combined with acute stroke symptoms?. Material and methods MR-imaging of 1465 patients treated on our Stroke Unit between June 2004 and May 2007 retrospectively are analyzed. 6 patients met the inclusion criteria of severe neurological symptoms, large territorial perfusion disturbances, lack of diffusion abnormalities and complete neurological recovery after treatment. Results In all six patients MTT measurements showed a significantly depressed perfusion in the symptomatic hemisphere ( p < 0.02). Time-to-peak delay correlated with the mean transit time delay (0.949, p < 0.01). Indication for thrombolysis was based on perfusion abnormalities and clinical symptoms. Stroke symptoms could be reversed in all patients without any complication. Conclusion Whereas diffusion imaging could not reveal any abnormality, perfusion analysis legitimated therapy with systemic thrombolysis in heavily affected patients. This work underlines the importance of multimodal MR imaging for guiding treatment decisions in acute stroke patients.

Superselective Intra-arterial Chemotherapy for Advanced Maxillary Sinus Cancer

The purpose of our study was to elucidate the relationship between arterial perfusion in advanced maxillary sinus cancer which was opacified by superselective intra-arterial computed tomographic arteriography (IA-CTA) and the tumor response to intra-arterial chemotherapy. Superselective IA-CTA was performed to identify the feeding arteries and their perfusion in advanced maxillary sinus cancer in 10 patients. Cisplatin was selectively infused into these feeding arteries, except for the internal carotid artery. The results were assessed in 9 of the 10 patients, and a complete response was achieved in 5 patients in whom either the entire tumor, or most of the tumor, was perfused by the branches of the external carotid artery. In 4 patients with a partial response, the residual tumors were seen in the territory of the perfusion defect or in the perfusion territory of the internal carotid artery. Superselective IA-CTA is a useful technique to correctly identify the intratumoral perfusion and to predict tumor response to the intra-arterial chemotherapy of advanced maxillary sinus cancer.

Arterial spin labeling of cerebral perfusion territories using a separate labeling coil

To obtain cerebral perfusion territories of the left, the right, and the posterior circulation in humans with high signal-to-noise ratio (SNR) and robust delineation. Continuous arterial spin labeling (CASL) was implemented using a dedicated radio frequency (RF) coil, positioned over the neck, to label the major cerebral feeding arteries in humans. Selective labeling was achieved by flow-driven adiabatic fast passage and by tilting the longitudinal labeling gradient about the Y-axis by theta = +/- 60 degrees . Mean cerebral blood flow (CBF) values in gray matter (GM) and white matter (WM) were 74 +/- 13 mL . 100 g(-1) . minute(-1) and 14 +/- 13 mL . 100 g(-1) . minute(-1), respectively (N = 14). There were no signal differences between left and right hemispheres when theta = 0 degrees (P > 0.19), indicating efficient labeling of both hemispheres. When theta = +60 degrees , the signal in GM on the left hemisphere, 0.07 +/- 0.06%, was 92% lower than on the right hemisphere, 0.85 +/- 0.30% (P < 1 x 10(-9)), while for theta = -60 degrees , the signal in the right hemisphere, 0.16 +/- 0.13%, was 82% lower than on the contralateral side, 0.89 +/- 0.22% (P < 1 x 10(-10)). Similar attenuations were obtained in WM. Clear delineation of the left and right cerebral perfusion territories was obtained, allowing discrimination of the anterior and posterior circulation in each hemisphere.