Opacification Of Arteries Research Articles

Impact of Intra-Arterial Injection Parameters on Arterial, Capillary, and Venous Time-Concentration Curves in a Canine Model

Recent advances in flat panel detector angiographic equipment have provided the opportunity to obtain physiologic and anatomic information from angiographic examinations. To exploit this possibility, one must understand the factors that affect the bolus geometry of an intra-arterial injection of contrast medium. It was our purpose to examine these factors in a canine model. Under an institutionally approved protocol conforming to Guide for the Care and Use of Laboratory Animals of the National Institutes of Health, 7 canines were placed under general anesthesia with isoflurane and propofol. Through a 5F catheter placed into the right common carotid artery, a series of biplane angiographic acquisitions was obtained to examine the effects caused by variation in the volume of injection, the rate of injection, the duration of injection, the concentration of contrast medium, and the catheter position on arterial, capillary, and venous opacification. The results of each injection protocol were determined from analysis of a time-contrast concentration curve derived from locations over an artery, in brain parenchyma, and over a vein. The curve was generated from 2D digital subtraction angiography acquisitions by using prototype software. The area under the curve, the amplitude of the curve, and the time to peak (TTP) were analyzed separately for each injection parameter. Changes in the injection protocols resulted in predictable changes in the time-concentration curves. The injection parameter that contributed most to maximum opacification was the volume of contrast medium injected. When the injection rate was fixed and the volume was varied, there was an increase in opacification (maximal) proportional to the injected volume. The injected volume also had an indirect (secondary) impact on the temporal characteristics of the opacification. The time-concentration curve became wider, and the peak was shifted to the right as the injection duration increased. The impact of injected volume on maximal opacification was significant (P < .0001), regardless of the site of measurement (artery, tissue, and vein); however, the impact on the temporal characteristics of the time-concentration curve reached statistical significance only in measurements made in the artery and the vein (P < .05), but not in the tissue (P > .1). The impact of injected volume on maximal opacification became nonproportional in the tissue and vein when the volume was very large (>12 mL). Increasing the concentration of contrast medium resulted in a nonproportional increase in the height of the time-concentration curves (P < .05). Injection rate had an impact on both maximal opacification and TTP. The impact on TTP occurred only when the injection rate was very slow (1 mL/s). Changes of concentration had a similar impact on the time-concentration curve. Catheter position did not cause significant alterations in the shape of the curves. There were predictable effects from modification of injection parameters on the contrast bolus geometry and on time-concentration curves as measured in an artery, brain parenchyma, or a vein. The amplitude, TTP, and area under the time-concentration curve depend mainly and proportionally on the amount of iodine traversing the vasculature per second. Other injection parameters were of less importance in defining bolus geometry. These findings mimic those observed in studies of parameters affecting bolus geometry following an intravenous injection.

Triple Rule-out and Dedicated Coronary Artery CTA: Comparison of Coronary Artery Image Quality

The aim of this study was to compare image quality on dedicated and triple rule-out coronary computed tomographic (CT) angiography (CTA) with respect to motion artifacts and the quality of coronary artery opacification. Twenty dedicated coronary CT angiographic studies and 20 emergency department triple rule-out CT angiographic studies (ie, to rule out pulmonary embolism, aortic dissection, and acute coronary syndrome) performed on 64-slice CT scanner were selected. Two radiologists, blinded to type of CTA, scored coronary artery image quality. Up to 14 coronary artery segments were scored for motion artifact on a scale ranging from 1 (no motion artifact) to 4 (severe motion artifact). The radiologists also scored the quality of opacification (1 = good opacification, 2 = limited opacification, 3 = vessel not seen). The average of all segments and dedicated larger and smaller coronary artery segments was compared. The average motion-artifact scores per vessel segment for dedicated and triple rule-out studies were 1.64 and 1.72, respectively (P = .6). For larger segments, the average motion-artifact score was 1.41 for dedicated CTA compared to 1.55 for triple rule-out CTA (P = .2). The average coronary artery opacification for dedicated studies was 1.05 for all segments and 1.03 for larger segments, compared to triple rule-out studies, which had scores of 1.09 (P = .5) for all segments and 1.06 (P = .5) for larger segments. No statistically significant differences in favor of dedicated CTA were identified. The image quality of triple rule-out CTA is comparable to that of dedicated coronary CTA, showing no statistically significant difference in motion artifacts or opacification, and therefore may be an alternative and useful diagnostic study in a select group of emergency department patients.

Late stent thrombosis

Late stent thrombosis is a serious complication after stent implantation and it can lead to the development of acute myocardial infarction or death. A 43-year-old patient was admitted to our clinic to coronary care unit. He was diagnosed with acute ST elevation myocardial reinfarction of inferoposterior localization and with right ventricular myocardial infarction. Eighteen months ago, he had acute myocardial infarction of the same localization, and at the same time, PCI (Percutaneous Coronary Intervention) was performed in acute phase, and two bare metal stents were implanted. Now, the patient had chest discomfort two hours before admittance, and PCI was performed once again in acute phase. The diagnostic coronarography resulted in occlusion of the right coronary artery, on the spot of the previously implanted stents. After the passage of guidewire, the artery was recanalized, and defects of artery opacification, which might have been thrombs, were noticed. The thrombs were seen on the spots of earlier implanted stents and in the posterior inteventricular and posterolateral branches of the right coronary artery. PTCA was performed and the patient received the GP IIb/IIIa antagonist therapy after which the control coronarography showed minimal defects of artery opacification, with good anterograde flow. After complete treatment the patient was in good condition. Late stent thrombosis, although not very often, is a very serious complication and can lead to death or acute myocardial infarction. To prevent it, it is necessary that the patient receives dual antiplatelet therapy, and that PCI procedure is performed technically correctly (suitable stent dimensions and proper stent expansion).

Non-occlusive colonic ischemia induced by verapamil ER overdose

Sir: Verapamil overdose can cause conduction disturbances and hypotension with cardiogenic shock [1], both of which can lead to ischemia. The colon is susceptible to ischemia because of the variable amount of collateral blood flow present, especially in arteriosclerotic patients [2, 3]. We report a case of colonic ischemia after verapamil overdose. A 60-year-old man with a history of hypertension, arteriosclerosis, aortofemoral bypass (with clamping of inferior mesenteric artery) 2 years ago and tobacco addiction was being treated with clopidogrel 75 mg/day and verapamil ER 240 mg/day. He came to the emergency department intoxicated after taking approximately 30 verapamil extended-release tablets and three clopidogrel tablets as a suicide attempt. His blood pressure was 72/38 mmHg, and his pulse rate was 52 beats/min. He was drowsy and had thready peripheral pulses. An electrocardiogram showed an atrioventricular block. A bottle of activated charcoal (50 g) was given and could be ingested by the patient. Despite the administration of intravenous fluids, calcium gluconate, and vasopressors, the patient’s blood pressure only marginally improved. He subsequently developed lower abdominal pain. Repeated examination showed abdominal distension with lower-quadrant guarding and absent bowel sounds. His leukocyte count was 22,000 cells/mm, and tomodensitometry of the abdomen showed a peritoneal effusion, a defect of opacification of the left colon with respect to opacification of celiac and superior mesenteric arteries (Fig. 1a, b). An exploratory laparotomy showed a gangrenous segment of the left colon; the rest of the colon and ileum was normal. He had a left hemicolectomy with a colostomy. Histolopathological evaluation showed a pronounced edema of the submucosa with the dilation of the submucosal vessels and several areas with necrotic ulcerations and intramural bleeding (Fig. 1c, d). There was no evidence of thromboembolic obstruction. He was hemodynamically stable during the remainder of his hospitalization and developed immediately acute respiratory distress syndrome. Finally, he left the ICU at day 30. Long-term verapamil use has also been reported as a cause of stercoral perforation of the sigmoid colon [4]. A previous case of caecal and

Poor Left Internal Mammary Artery Opacification on Coronary CT Angiography: An Indirect Sign of Subclavian Steal

We report a case of a case of a 68-year-old man who presented for evaluation of significant aortic valve stenosis, a suspected sequela of radiation therapy for Hodgkin disease 27 years earlier. He had concomitant cardiac risk factors of hypercholesterolemia, congestive heart failure, and coronary artery disease; the latter was thought to be secondary to postradiation changes as well.

Quantitative parameters to compare image quality of non-invasive coronary angiography with 16-slice, 64-slice and dual-source computed tomography

Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing. A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n = 90; Siemens Sensation 64: n = 91; Siemens Definition: n = 75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients. Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347 +/- 13 vs. 254 +/- 14 (64-MSCT) vs. 233 +/- 11 (16-MSCT) HU], LM (362 +/- 11/275 +/- 12/262 +/- 9), LAD (332 +/- 17/248 +/- 19/219 +/- 14) and LCX (310 +/- 12/210 +/- 13/221 +/- 10, all p < 0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p < 0.05). BMI had no impact on the CA ratio in DSCT only (p < 0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a positive impact on the diagnostic accuracy.

Emergency Cardiac CT for Suspected Acute Coronary Syndrome: Qualitative and Quantitative Assessment of Coronary, Pulmonary, and Aortic Image Quality

The purpose of this study was to determine whether a dedicated coronary CT protocol provides adequate contrast enhancement and artifact-free depiction of coronary, pulmonary, and aortic circulation. Dedicated coronary 64-MDCT data sets of 50 patients (27 men; mean age, 54 +/- 12.4 years) consecutively admitted from the emergency department with suspected acute coronary syndrome were analyzed. Two independent observers graded overall coronary arterial image quality and qualitative and quantitative contrast opacification, motion, and streak artifacts within the pulmonary arteries and aorta. Coronary image quality was excellent in 48 patients (96%) and moderate in two patients (4%). Eleven left main and 22 left upper lobar pulmonary arteries were not visualized. Qualitative evaluation showed pulmonary arterial tree opacification to be excellent except for the right and left lower lateral and posterior segmental branches (52-54% rate of poor opacification). Quantitative evaluation showed four central (8%), six lobar (8%), and 206 segmental (29%) branches had poor contrast opacification (< 200 HU). Nineteen right upper lobar arteries (38%) were slightly and one was severely affected by streak artifact. At the segmental pulmonary artery level, marked differences in contrast enhancement were detected between the upper (292 +/- 72 HU) and both the middle (249 +/- 85 HU) and the lower lobes (248 +/- 76 HU) (p < 0.01). Mean aortic opacification was 300 +/- 34 HU with excellent contrast homogeneity without severe motion or streak artifacts. In the evaluation of patients presenting to the emergency department with suspected acute coronary syndrome, a dedicated coronary CT protocol enables excellent assessment of the coronary arteries and proximal ascending aorta but does not depict the pulmonary vasculature well enough for exclusion of pulmonary embolism.

Longitudinal left ventricular systolic function is impaired in patients with coronary slow flow

Slow coronary flow (SCF) is a well recognized clinical entity, characterized by delayed opacification of coronary arteries in the presence of normal coronary angiogram. There is currently no data evaluating myocardial systolic function in SCF phenomenon. This study was performed to evaluate regional and global systolic function using tissue Doppler imaging (TDI), strain (S) and strain rate imaging (SRI) in patients with slow coronary flow. A total of 35 patients with slow coronary flow and otherwise normal coronary arteries (mean age 48 +/- 7 years) (SCF group) and 21 patients with normal coronary angiograms (mean age 50 +/- 12 years) (control group) were included in the study. These patients were prospectively assessed for evaluation of regional and global left ventricular function by conventional echocardiography, systolic TDI, peak S, and peak systolic strain rates (SRs) There was a significant difference in peak SRs (-1.1 +/- 0.2 vs. -1.8 +/- 0.2 1/s, P < or = 0.0001) but similar in systolic TDI (42 +/- 20 vs. 44 +/- 21 mm/s, P = 0.77) and S (20.7 +/- 7.7 vs. 23.7 +/- 8.8, P = 0.14) between groups. SRs showed a good correlation with mean TIMI frame count (r = -0.80, P < or = 0.0001). As the number of coronary artery with SCF increased global strain rate decreased further. In case of one or two or three coronary artery with SCF global strain rates were 1.4 +/- 0.2; 1.1 +/- 0.3; 0.9 +/- 0.2 1/s, respectively, P < or = 0.0001. Although ejection fraction was preserved, global and regional strain rate were decreased in SCF. In brief, there is an impairment in longitudinal left ventricular systolic function in patients with SCF.

64-MDCT imaging of the coronary arteries and systemic arterial vascular tree in a single examination: optimisation of the scan protocol and contrast-agent administration

The aim of this study was to validate a 64-row multidetector computed tomography (64-MDCT) acquisition protocol with biphasic administration of contrast medium for comprehensive assessment of the coronary and systemic arterial tree in a single examination. The scanning protocol comprised two acquisitions: an electrocardiograph (ECG)-gated scan at the level of the heart, followed by a total-body, low-dose scan of the systemic arterial circulation. Twenty patients were evaluated using two different strategies for contrast administration. In ten patients, the delay between the two acquisitions was set at 40 s, whereas in the remaining patients, it varied between 45 s and 65 s. For both strategies, the degree of systemic arterial opacification and the attenuation gradient between arterial and venous structures were quantitatively assessed at six extracoronary locations. Two observers evaluated in consensus the presence or absence of atherosclerosis and the degree of stenosis of arterial segments. Three hundred coronary segments were analysed. Arterial-wall changes were depicted in 155 (51%) segments, and in 35 (23%), the degree of stenosis was > 50%. Of the 640 extracoronary arterial segments, 250 (39%) presented atherosclerotic wall alterations, in 50 (20%), the degree of stenosis was > 50% and five were affected by aneurysmal dilatation. The magnitude of arterial opacification values and attenuation gradients between arterial and venous structures were significantly higher in patients scanned with the 40-s fixed-delay strategy. Whole-body CT angiography with biphasic administration of contrast agent and fixed scan delay has been shown to be a feasible and reproducible technique. Comprehensive data on the global atherosclerotic burden potentially offer important therapeutic options for subclinical, high-risk segments.

The relation between coronary flow rate, plasma endothelin-1 concentrations, and clinical characteristics in patients with normal coronary arteries

Coronary slow flow (CSF) is characterized by delayed opacification of epicardial arteries in the absence of occlusive disease. In the present study, we aimed to investigate the relation between coronary flow rate, plasma endothelin-1 (ET-1) concentrations, and clinical characteristics in patients with normal coronary arteries. The study population included 77 patients with angiographically normal coronary arteries who underwent coronary angiography on suspicion of ischemic heart disease due to typical chest pain or ischemic findings on treadmill exercise test or myocardial scintigraphy. Based on the Thrombolysis In Myocardial Infarction frame count (TFC), patients were grouped into those with normal coronary flow and those with slow coronary flow. Forty-eight (61.5%) patients were found to have CSF. Plasma ET-1 concentrations were significantly higher with the presence of CSF (P=.03). There were significant differences between plasma ET-1 concentrations, and mean TFC, TFC for left anterior descending coronary artery (LAD), TFC for left circumflex coronary artery (CX), and TFC for right coronary artery separately in patients with and without CSF (P=.033, P<.001, P<.001, P<.001, and P<.001, respectively). Mean TFC, TFC for LAD, and TFC for CX, and ET-1 concentrations were significantly higher in smokers than in nonsmokers (P<.001, P<.001, P=.004, and P=.033, respectively). However, logistic regression analysis suggested that ET-1 concentration was not an independent determinant of CSF. Although there is a significant relation between ET-1 concentrations and coronary flow rate, ET-1 concentrations are not sufficient to determine the presence of CSF. Smoking is strongly associated with CSF, TFC, and increased ET-1 concentrations.

Usefulness of Tomographic Versus Planar Lung Scintigraphy in Suspected Pulmonary Embolism in a Daily Practice

Objectives: Lung scintigraphy is non-diagnostic in most patients suspected of pulmonary embolism when performed in planar mode. Tomographic mode could improve lung scan performance but has not been rigorously assessed. In this study we assessed the usefulness of tomographic mode in patients with a non-diagnostic lung scan scintigraphy. Methods: pulmonary embolism was diagnosed or ruled out in consecutive patients with a non-diagnostic lung scan by the combination of a 4-slices computerized tomography and a lower-limb ultrasonography. Results given by reading the tomographic mode in ventilation/perfusion lung scan were compared to final diagnosis. Results: 142 out of 392 consecutive patients with a non-diagnostic planar lung scintigraphy were included while 47 were excluded, 45 because of contra-indication to contrast medium and 2 because of non-optimal opacification of pulmonary arteries. Ninety-five patients were evaluated. Pulmonary embolism was diagnosed in 20 (21%) patients and ruled out in 75 (79%). Concordance with final diagnosis was found in 77/94 (82%) patients. Tomographic mode was non-diagnostic in 1 (1%) patient. Tomographic mode sensitivity/specificity/accuracy were 0.79/0.83/0.80 respectively. Negative predictive value was 0.94. Discordances were related to single sub segmental or non-occluding segmental thrombus. Conclusion: Tomographic mode is diagnostic in nearly all patients and agreement with final diagnosis is found in the majority. Its excellent negative predictive value enables to rule out pulmonary embolism. Discordances were related to single sub segmental or non-occluding segmental thrombus which prognosis value remains to be established.

Renal Frame Count and Renal Blush Grade: Quantitative Measures That Predict the Success of Renal Stenting in Hypertensive Patients With Renal Artery Stenosis

This study sought to identify angiographic parameters of favorable clinical response to renal artery stenting. Stenting improves blood pressure (BP) control in patients with renal artery stenosis (RAS), but markers predicting a favorable clinical response are limited. Renal perfusion was quantified in hypertensive patients (BP >or=140/90 mm Hg) without RAS by determining renal frame count (RFC) (angiographic frames [30 frames/s] for contrast to reach distal renal parenchyma after initial renal artery opacification) and renal blush grade (RBG) (0: none, 1: minimal, 2: normal, 3: hyperemic parenchymal blush). It was hypothesized that stenting unilateral RAS in hypertensive patients would result in decreased RFC and increased RBG, which might predict BP reduction. The RFC in 17 consecutive hypertensive patients without RAS (control group) (64.4 +/- 14.2 years, 12 male, 22 kidneys) was 20.1 +/- 5.4, whereas RBG was 2.33 +/- 0.66. In 24 consecutive hypertensive patients with unilateral RAS (study group) (72.7 +/- 11.3 years, 8 male), reduced RFC (26.6 +/- 9.1 to 21.4 +/- 6.7, p < 0.001) and increased RBG (1.63 +/- 0.71 to 2.13 +/- 0.85, p = 0.03) were observed after renal stenting. At 6 months, reduced BP (systolic BP 150.6 +/- 15.6 mm Hg to 128.6 +/- 15.5 mm Hg, p < 0.001; diastolic BP 77.2 +/- 15.6 mm Hg to 68.3 +/- 10.4 mm Hg, p = 0.022) without change in number of hypertensive medications was observed. Clinical responders (systolic BP reduction >15 mm Hg) had a greater decrease in RFC (7.7 +/- 4.6 vs. 1.7 +/- 5.1, p = 0.009) and 78.6% of patients with >4 RFC decrease were responders (p = 0.024). This study shows that quantitative indices of renal perfusion (RFC and RBG) are impaired in patients with RAS and improve after stenting, and that RFC reduction is associated with BP reduction.

Impaired left ventricular function has a detrimental effect on image quality in multi-detector row CT coronary angiography

To determine whether there is a relationship between left ventricular (LV) haemodynamic parameters, circulation times, and arterial contrast opacification that might affect the image quality of computed tomography (CT) coronary angiography. Thirty-six patients were included in the study: 18 with cardiomyopathy (CM) and LV dilatation of suspected ischaemic aetiology [age 57.9+/-13.7 years, range 30-77 years; 14 male, four female; body mass index (BMI)=27.7+/-4.5, range 25.5-31.8] and 18 controls (age 62.3+/-9.4 years, range 47-89 years; 10 male, eight female; BMI 27.8+/-6.6; range 19.2-33.6). Coronary artery image quality was assessed using a three-point visual scale; contrast medium circulation times, aortic root contrast attenuation, and LV functional parameters were studied. Visually reduced contrast opacification impaired image quality more often in the CM group than the control group (27.4 versus 5.1%). A total of 55.6% CM patients had a contrast transit time ranging from 30-75 s; the number of "unassessable" segments increased with increasing transit time conforming to a fitted quadratic model (R2=0.74). The relationship between LV ejection fraction and contrast attenuation may also conform to a quadratic model (R2=0.71). LV haemodynamics influence coronary artery opacification using cardiac CT, and users imaging this subgroup must do so with the knowledge of this potential pitfall. The results indicate the need for further studies examining CT protocols in this clinical subgroup.

Hand vascular involvement assessed by magnetic resonance angiography in systemic sclerosis

Impairment of the microcirculation is a cardinal feature of systemic sclerosis (SSc). Magnetic resonance angiography (MRA) has improved the assessment of vascular lesions of the hand. The aim of this study was to evaluate vascular abnormalities in the hands of patients with SSc, using MRA. Thirty-eight patients with SSc were compared with 7 healthy subjects and 7 patients with rheumatoid arthritis. Among patients with SSc, the mean +/- SD age was 52 +/- 14 years, the mean +/- SD Health Assessment Questionnaire (HAQ) score was 0.9 +/- 0.8, and the mean +/- SD systolic pulmonary artery pressure (PAP) was 32.2 +/- 8.4 mm Hg. Ten patients had a history of digital ulcers. The MRA protocol consisted of 4 successive acquisitions, each lasting 52 seconds, of 3-dimensional coronal cross-sectional images after gadolinium injection. The primary criteria were distality and quality of arterial opacification, avascular areas, and venous return. Thirty-five of the patients with SSc (92%) had at least 1 true digital artery that did not reach the first phalanx at the initial arterial analysis, and 23 patients (61%) had > or =4 damaged arteries. Twenty-eight patients (74%) had thin arteries, and 20 patients (53%) had >1 avascular area. Nearly all patients (35 of 38 [92%]) had abnormal venous return, and a lack of visible venous return was observed in 16 patients (42%). Results for all of the control subjects were considered normal. Digital ulcers were more frequently observed in patients with SSc who had > or =4 damaged proper digital arteries compared with other patients (P = 0.003), the HAQ score was associated with thin-caliber arteries (P = 0.04), and systolic PAP was associated with tissue enhancement secondary to ischemia (P = 0.04). These results show the substantial vascular involvement in SSc. Lesions were diffuse and involved both arterial and venous vessels of small caliber as well as the microcirculation.

Limitations of computed tomographic angiography in the diagnosis of brain death

To evaluate the accuracy of cerebral computed tomographic angiography (CT-a) for the diagnosis of brain death (BD). Prospective observational study in intensive care units. Twenty-one clinically BD patients enrolled over 12 months. All clinically BD patients were evaluated by electroencephalography (EEG) and CT-a after exclusion of hypothermia and drug intoxication. Data collected included: demographic characteristics, cause of BD, delay between in-hospital admission and BD diagnosis and between EEG and CT-a, occurrence of cardiac arrest, administration of vasoactive agents, results of EEG and CT-a. We evaluated the sensitivity of EEG and CT-a and their agreement. Groups were compared according to BD diagnosis by EEG and CT-a (E+C+), or only by EEG (E+C(-)). Statistical analysis were performed by Mann-Whitney test and Fisher's exact test. BD was confirmed by EEG in all cases (sensitivity 100%) whereas only 11 patients of 21 had no cerebral perfusion during CT-a (sensitivity 52.4%). No agreement was documented between EEG and CT-a for the diagnosis of BD (kappa = 0). Patients' characteristics did not differ between E+C+ and E+C(-) groups. In the E+C(-) group arterial opacification was observed in 100% of patients, but opacification of the internal cerebral veins was achieved in only 30%. In clinically BD patients with no electroencephalographic activity CT-a documents opacification of the intracerebral vessels in a significant percentage of the cases. Therefore CT-a cannot be recommended as a means of BD diagnosis.

Measurement of Caval Blood Flow with MRI During Respiratory Maneuvers: Implications for Vascular Contrast Opacification on Pulmonary CT Angiographic Studies

Transient interruption of the contrast bolus has been described as a physiologic artifact that can sometimes result in poor opacification of the pulmonary arteries on pulmonary CT angiographic studies. To better understand the mechanism underlying this artifact, we used velocity-encoded cine MRI to measure flow in the inferior vena cava (IVC) and superior vena cava (SVC) during respiratory maneuvers. Quantitative measurements of SVC and IVC flow per R-R interval were performed on 10 healthy volunteers (six men, four women; median age, 30 years; range, 25-55 years) with a retrospectively ECG-gated velocity-encoded gradient-echo cine sequence on a 1.5-T MRI unit with axial slices at the level of the diaphragm and just below the azygous vein confluence during free breathing, continuous inspiration, breath-hold at end inspiration, Valsalva maneuver, and breath-hold at end expiration. Median flow during free breathing was 38.9 mL in the SVC and 74.3 mL in the IVC, during continuous inspiration was 43.9 mL in the SVC and 113.7 mL in the IVC, during breath-hold at end inspiration was 31.0 mL in the SVC and 56.1 mL in the IVC, during a Valsalva maneuver was 28.9 mL in the SVC and 53.9 mL in the IVC, and during breath-hold at end expiration was 35.3 mL in the SVC and 61.2 mL in the IVC. MRI measurements showed a significant increase in caval flow during inspiration and a greater relative increase in blood flow in the IVC than in the SVC. For thoracic CT performed with IV contrast enhancement, deep inspiration before scanning leads to a large influx of IVC blood that does not contain contrast medium and dilutes the contrast bolus, causing poor vascular opacification. Avoiding initial inspiration before scanning is suggested as a way to limit the transient interruption of the contrast bolus artifact.

Early sign of atherosclerosis in slow coronary flow and relationship with angiotensin-converting enzyme I/D polymorphism

Increase in carotid artery intima-media thickness (IMT) is an early sign of atherosclerosis. Slow coronary flow (SCF) is characterized by delay of opacification of coronary arteries in coronary angiography in the absence of any evident obstructive lesion, but its etiopathogenesis remains unclear. Genes that regulate the renin angiotensin system also play a role in developing cardiovascular system disorders. The presence of deletion (D) allele in angiotensin converting enzyme (ACE) gene polymorphism is associated with coronary artery disease. The aim of this study was to investigate the carotid artery IMT measurement, as an early sign of atherosclerosis, in patients with SCF and without SCF and also to assess the effect of the renin-angiotensin gene system on carotid IMT. Forty-four patients with angiographically proven SCF and 44 cases with normal coronary flow (NCF) pattern with similar risk profile were enrolled in the study. Coronary flow patterns of the cases were determined by thrombolysis in myocardial infarction (TIMI) frame count method. Intima-media thickness was measured by recording ultrasonographic images of both the left and right common carotid artery with a 12-MHz linear array transducer. ACE I/D polymorphism and Angiotensin II tip 1 receptor (AT1R) A/C gene polymorphism were determined by polymerase chain reaction (PCR) amplification. Demographic characteristics and coronary artery disease risk factors of SCF and NCF groups were similar. Mean TIMI frame count and carotid IMT (mm) were significantly higher in the SCF group than controls (45.9 +/- 12 vs 23.3 +/- 3.7, P = 0.0001; 0.75 +/- 0.08 vs 0.69 +/- 0.06, P = 0.0001, respectively). Mean TIMI frame count was positively correlated with IMT of carotid artery in correlation analysis (r = 0.45, P = 0.0001). When analyzed in regard to ACE genotype in all subjects, IMT values were statistically different (0.78 +/- 0.06 for DD genotype, 0.72 +/- 0.05 for ID genotype, and 0.64 +/- 0.06 for II genotype, P = 0.0001). This difference remained significant in subgroup analyses for each genotype. No association could be observed between the AT1R A/C(1166) polymorphism and IMT of carotid artery measurement (P > 0.05). Lack of association was still observed with analysis carried out when genotype effect was assumed to be inherited as additive (CC versus AA versus AC) or dominant (AA versus AC+CC). Increased IMT in patients with SCF shows that subclinical atherosclerosis may play role in this phenomenon. This increase was most marked in the presence of D allele of ACE genotype, which is associated with vascular hypertrophy.

Aortic Pulse Pressure and Aortic Pulsatility in Patients with Coronary Slow Flow

Objective: Coronary slow flow (CSF) is an angiographic phenomenon characterized by delayed opacification of coronary arteries in the absence of obstructive coronary disease. Recently, increased aortic pulse pressure (PP) and aortic pulsatility were both linked to the presence of angiographic coronary artery disease. In this study aortic PP and aortic pulsatility, derived from the invasively measured ascending aortic pressure waveform, were analyzed in patients with CSF and otherwise normal epicardial coronary arteries and compared with those with completely normal coronary arteries. Methods: Fifty consecutive patients with CSF (35 men, mean age: 51.7 ± 10 years) and fifty age and gender-matched controls (34 men, 51.1 ± 9 years) were included in the study. For determination of coronary flow, the thrombosis in myocardial infarction (TIMI) frame count method was used. Blood pressure waveforms of the ascending aorta were measured during cardiac catheterization with a fluid-filled system. Aortic pulsatility was estimated as the ratio of aortic PP to mean pressure. Results: Study groups were well matched with respect to age, gender and atherosclerotic risk factors. Although systolic, diastolic and mean pressures of the ascending aorta were similar, aortic PP (60.5 ± 19 vs. 51.7 ± 14 mm Hg, p = 0.01) and aortic pulsatility (0.63 ± 0.1 vs. 0.54 ± 0.1, p = 0.006) were significantly higher in patients with CSF compared with the controls. Besides, in all subjects, corrected TIMI frame counts of all three coronary arteries correlated with both ascending aorta PP and aortic pulsatility values. No association was found between corrected TIMI frame counts of coronary arteries and aortic mean blood pressure or brachial blood pressure parameters. Conclusion: Our findings suggest that CSF is, as with obstructive coronary artery disease, associated with more diffuse vascular disease rather than being an isolated finding.

Einfluss des Bodymass-Index auf den Kontrast in den Koronararterien mit der 64-Schicht-CT

To evaluate the influence of the body mass index (BMI) on coronary artery opacification in 64-slice CT. Sixty-two patients retrospectively underwent ECG-gated 64-slice CT coronary angiography (tube potential 120 kV, tube current time product 650 mAs) after intravenous injection of 80 ml of iodinated contrast agent (320 mg/ml, 5 ml/s). Attenuation values (HU) were measured and contrast-to-noise ratios (CNR) were calculated in the right coronary artery (RCA) and left main artery (LMA). The CNR was defined as the difference between the mean attenuation in the vessel and the mean attenuation in the perivascular fat tissue divided by the image noise in the ascending aorta. The height and weight of the patients at the time of the CT scan were recorded and the BMI was calculated. The mean BMI was 26.2 +/- 3.2 kg/m (2) (range 19.7 - 32.2 kg/m (2)), the mean attenuation in the LMA was 330 +/- 64 HU, and the mean attenuation in the RCA was 309 +/- 68 HU. The CNR in the LMA was 16.7 +/- 3.8, and the CNR in the RCA was 15.9 +/- 3.6. The image noise in the ascending aorta significantly correlated with the BMI (r = 0.36, p < 0.01). A weak negative correlation was found between the BMI and LMA attenuation (r = - 0.28, p < 0.05), whereas no significant correlation was found for the RCA (r = - 0.21, p = 0.12). A significant negative correlation was found between the BMI and the CNR in the RCA (r = - 0.41, p < 0.05) and the LMA (r = - 0.47, p < 0.001). With constant scan parameters and a constant contrast medium amount, the CNR in both coronary arteries decreases while the BMI increases. This implies a modification of previously standardized and fixed examinations with respect to individually adapted protocols with variable parameters for CT coronary angiography.

A serious complication of a power injector for coronary angiography

Recently several contrast delivery systems for coronary angiography have been introduced to provide adequate artery opacification through small catheters, which are thought to facilitate patient comfort and reduce hemorrhagic/vascular complications. However, the safety profile of a specific system has not been fully examined. In this case report, we present patients who underwent angiography using a contrast delivery system and suffered from massive air embolism necessitating mechanical support. We discuss the potential mechanism and the prevention of this complication.