320排容积CT冠状动脉血管成像在心律失常患者的应用

目的 评价320排CT容积扫描在心律失常(房颤和室性早搏)患者冠状动脉CT血管成像(CTCA)的可行性及其图像质量.方法 31例持续房颤和8例室性早搏患者.经320排CTCA检查.由2名有经验的放射科医师对CT图像质量(4级评分)进行评价,分析图像质量与患者的辐射剂量.2名评价者之间的一致性采用Kappa检验.结果 31例持续房颤和8例室性早搏患者中可评估的冠状动脉血管510段,其中496段(97.2％)达到诊断要求.患者的平均辐射剂量为(12.7±4.8)mSv.2名评价者对冠状动脉评分的一致性较好(Kappa=0.72).结论 房颤和室性早搏患者的CTCA检查具有可行性,心律失常患者可以不作为检查的禁忌证,但仍须进一步降低辐射剂量.     

低剂量对比剂320排CT冠状动脉成像可行性研究

目的:探讨单次心跳内采集数据320排CT冠状动脉成像时低对比剂用量的可行性。方法:将131例行冠状动脉CTA检查的病例分为3组,A组对比剂剂量为0.8ml/kg,注射流率4.5ml/s;B组对比剂剂量0.7ml/kg,注射流率5.0ml/s;C组对比剂剂量0.6ml/kg,注射流率5.5ml/s。所有病例心率均<70次/分,单心跳采集心脏数据。分别在主肺动脉干、升主动脉、右冠状动脉和左冠状动脉主干内选择相同的兴趣区测量其CT值,采用单因素方差分析比较3组病例动脉强化程度的差异。结果:C组主肺动脉干CT值为(185.40±46.74)HU,强化程度最低,与A组和B组[分别为(225.77±79.69)和(216.79±51.06)HU]间差异有统计学意义(P<0.05);各组之间升主动脉、右冠状动脉和左冠状动脉主干强化程度差异无统计学意义(P>0.05)。结论:320排CT冠状动脉成像能显著降低单心跳扫描患者对比剂用量,并保证冠状动脉足够程度的强化。     

Aortoiliac gadolinium-enhanced CT angiography: improved results with a 16-detector row scanner compared with a four-detector row scanner

PURPOSE: To assess the level of vascular enhancement of gadolinium-enhanced aortoiliac computed tomographic (CT) angiography with a 16-detector row CT scanner and to compare it with the results of previous similar studies that used four-detector row CT units. MATERIALS AND METHODS: Eleven gadolinium-enhanced CT angiograms were obtained in 10 consecutive patients with contraindication to iodinated contrast medium with use of a 16-detector row CT scanner. In the region of interest, attenuation measurements (in HU) were obtained from the proximal abdominal aorta to the common femoral arteries during unenhanced, gadolinium-enhanced, and delayed acquisitions. The results were compared to those in the 15 consecutive patients who most recently had similar examinations performed on a four-detector row CT unit. Phantom studies with diluted gadolinium were conducted to compare attenuation between CT units. RESULTS: On four-detector row CT, throughout the scan length, mean enhancement values were 53.8 HU +/- 5.3 and 15.0 HU +/- 2.6 for gadolinium-enhanced and delayed series, respectively. For the 16-detector row CT unit, they were 76.1 HU +/- 3.4 and 21.3 HU +/- 1.3, respectively. As a result of a shorter scan time and a more optimal start time, the 16-detector row CT unit provided significantly greater and more consistent enhancement throughout the scan length compared with the four-detector row CT unit (P =.0106). Similar structures had significantly greater enhancement when 120 kV was applied instead of 140 kV (P =.0495) CONCLUSION: The 16-detector row CT scanner improved gadolinium-enhanced CT angiography results compared with the four-detector row CT unit.     

Comparative evaluation of image quality among different detector configurations using area detector computed tomography

The 320-detector row computed tomography (CT) system, i.e., the area detector CT (ADCT), can perform helical scanning with detector configurations of 4-, 16-, 32-, 64-, 80-, 100-, and 160-detector rows for routine CT examinations. This phantom study aimed to compare the quality of images obtained using helical scan mode with different detector configurations. The image quality was measured using modulation transfer function (MTF) and noise power spectrum (NPS). The system performance function (SP), based on the pre-whitening theorem, was calculated as MTF²/NPS, and compared between configurations. Five detector configurations, i.e., 0.5 × 16 mm (16 row), 0.5 × 64 mm (64 row), 0.5 × 80 mm (80 row), 0.5 × 100 mm (100 row), and 0.5 × 160 mm (160 row), were compared using a constant volume CT dose index (CTDI_vol) of 25 mGy, simulating the scan of an adult abdomen, and with a constant effective mAs value. The MTF was measured using the wire method, and the NPS was measured from images of a 20-cm diameter phantom with uniform content. The SP of 80-row configuration was the best, for the constant CTDI_vol, followed by the 64-, 160-, 16-, and 100-row configurations. The decrease in the rate of the 100- and 160-row configurations from the 80-row configuration was approximately 30%. For the constant effective mAs, the SPs of the 100-row and 160-row configurations were significantly lower, compared with the other three detector configurations. The 80- and 64-row configurations were adequate in cases that required dose efficiency rather than scan speed.     

Coronary angiography by 64-detector row computed tomography using low dose of contrast material with saline chaser: influence of total injection volume on vessel attenuation

OBJECTIVE: To assess the influence of total injection volume on thoracic great vessels and coronary arteries enhancement in 64-detector row computed tomography (CT) coronary angiography using low dose of contrast material. METHODS: Sixty patients underwent cardiac CT (64 x 0.5 mm, 0.4 rot/s) using 40 mL of contrast material (350 mg of Iodine per milliliter) in 30 patients and 50 mL in 30 patients. Computed tomography densities (Hounsfield units) in ascending aorta, descending aorta, and main pulmonary artery were measured at every second with the time of CT data acquisition recorded in each reconstructed image. Computed tomography densities of proximal and distal coronary arteries were also measured. Differences in CT densities between 40 and 50 mL contrast material were assessed with the Student t test. In addition, the relation between the injection volume (mL) of contrast material per kilogram body weight and contrast enhancement in coronary arteries was studied. RESULTS: The average attenuations in the ascending and descending aorta and coronary arteries were significantly lower in 40-mL group than in 50-mL group (<0.05). In addition, the average attenuations in the pulmonary artery were significantly lower in 40-mL group than 50-mL group (<0.01). Every patient with the total injection volume of more than 0.9 mL/kg body weight showed a contrast enhancement more than 250 Hounsfield units. CONCLUSIONS: The reduction of total injection volume lowered the enhancement of thoracic great vessels and coronary arteries in 64-detector row cardiac CT. The injection volume of at least 0.9 mL/kg body weight was necessary for a steady contrast enhancement in coronary arteries.     

Intravenous contrast material administration at 16-detector row helical CT coronary angiography: test bolus versus bolus-tracking technique

PURPOSE: To compare test bolus and bolus-tracking techniques for intravenous contrast material administration at 16-detector row computed tomographic (CT) coronary angiography. MATERIALS AND METHODS: This study had institutional review board approval, and patients gave informed consent. Thirty-eight patients (mean age, 60 years; three women) were randomized into two groups according to bolus timing technique: group 1 (20-mL test bolus with 100-mL main bolus) and group 2 (bolus tracking with 100-mL main bolus). All patients underwent electrocardiography-gated 16-detector row CT coronary angiography with 12 detectors (collimation, 0.75 mm; rotation time, 420 msec). In group 1, test bolus peak attenuation was used as a delay, while in group 2, a +100-HU threshold in ascending aorta triggered angiographic acquisition, with an additional 4-second delay for patient instruction. Attenuation was measured in the longitudinal direction throughout the examination in three main vessels: ascending aorta (region of interest [ROI] 1), descending aorta (ROI 2), and main pulmonary artery (ROI 3). Mean attenuation and slope of bolus geometry curve were calculated in each patient and ROI. Attenuation at origin of coronary arteries was measured. Student t test was used to compare results. RESULTS: Mean scan delay was 6 seconds longer in group 2 (P < .05). Average attenuation values were 306.6 HU +/- 44.0 (standard deviation) and 328.2 HU +/- 58.6 (P > .05) in ROI 1, 291.6 HU +/- 45.1 and 326.4 HU +/- 62.6 (P > .05) in ROI 2, and 354.7 HU +/- 78.0 and 305.3 HU +/- 71.4 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average slope values were 5.8 and -0.8 (P < .05) in ROI 1, 7.7 and 0.7 (P < .05) in ROI 2, and -1.0 and -13.3 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average attenuation values in left main, left anterior descending, and left circumflex arteries were higher in group 2 (P < .05); there were no differences (P > .05) between groups in right coronary artery. CONCLUSION: Bolus-tracking yields more homogeneous enhancement than does the test bolus technique.     

Influence of hemodynamic parameters on coronary artery attenuation with 320-detector coronary CT angiography

Objectives

To investigate the relationship between cardiac output, end diastolic volume and the contrast enhancement in coronary CT angiography using 320-detector CT.

Materials and methods

A total of 38 patients underwent coronary CT angiography by using a 320-detector CT scanner (detector configuration, 320 × 0.5 mm). The attenuation value of the ascending aorta at the level of the orifice of the left main trunk was measured. The cardiac output (CO), end diastolic volume (EDV) and stroke volume (SV) were measured by echocardiography. The EDV was normalized to the body surface area (BSA). The total blood volume injected from the left ventricle from the beginning of the contrast agent injection to the time of image acquisition was determined to be the total injected blood volume (TIV), which is a product of SV and the number of heart beats from the initiation of contrast agent injection to the scan.

Results

There was a negative correlation between the attenuation of the ascending aorta and CO (r = −0.44, P = 0.0053). However, the negative correlation between the attenuation of the ascending aorta and TIV was stronger (r = −0.52, P = 0.0007). There was a negative correlation between the attenuation of the ascending aorta and EDV/BSA (r = −0.45, P = 0.0039).

Conclusion

In 320-detector CT, contrast enhancement in CCTA with a lesser amount of contrast medium decreases when cardiac output is high. Patients with larger EDV/BSA may also show decreased attenuation.     

Atypical chest pain: coronary, aortic, and pulmonary vasculature enhancement at biphasic single-injection 64-section CT angiography

PURPOSE: To prospectively evaluate the enhancement of coronary, pulmonary, and thoracic aortic vasculature by using biphasic single-acquisition 64-section computed tomographic (CT) angiography and to prospectively evaluate if differences in right side of the heart and coronary venous enhancement interfere with interpretation of coronary arteries. MATERIALS AND METHODS: With internal review board approval and HIPAA compliance, 50 patients (16 men, 34 women; mean age, 51.5 years; range, 30-75 years) with atypical chest pain were referred from the emergency department and were imaged with a 64-section CT scanner after premedication with oral atenolol and/or intravenous metoprolol. Thoracic CT angiography with retrospective gating was subsequently performed with a single biphasic injection of 130 mL of iso-osmolar contrast material (100 mL at 5 mL/sec and 30 mL at 3 mL/sec) in caudal-to-cranial acquisition. Coronary, aortic, and pulmonary arterial attenuation values were obtained. Coronary venous and right atrial enhancement were evaluated to assess whether there was interference with coronary artery evaluation. A two-tailed Friedman test was used to evaluate differences among segments within each artery. RESULTS: Mean coronary arterial, pulmonary arterial, and aortic attenuation values were significantly higher than the 250-HU threshold (P < .05). Mean pooled coronary arterial (288.9 HU +/- 64.8), pulmonary arterial (316.4 HU +/- 79.9), and aortic (329.9 HU +/- 63.3) attenuation values were significantly higher than the 250-HU threshold (P < .0001). Coronary venous enhancement did not affect depiction or interpretation of coronary arteries. Right atrial streak artifact focally traversed the right coronary artery in only one study. CONCLUSION: The aforementioned thoracic CT angiographic protocol provides enhancement of coronary, aortic, and pulmonary vasculature in a single breath hold without interference from right side of the heart streak artifact or coronary venous enhancement.     

Coronary artery stent patency assessed with in-stent contrast enhancement measured at multi-detector row CT angiography: initial experience

The authors investigated the contrast enhancement characteristics of the coronary artery stent lumen to assess patency and then evaluated the accuracy of computed tomographic (CT) measurement of the in-stent luminal diameter. Nineteen patients (16 men and three women; mean age, 58.7 years) with 26 stents underwent cardiac-gated CT angiography with a 16-detector row scanner 1-3 weeks after stent placement. CT images depicted the lumina of 20 stents in 14 patients. CT attenuation measured in the treated lumen was higher than, and correlated highly (r >/= 0.87) with, attenuation in the proximal and distal untreated lumen. Estimated values for in-stent luminal diameter were lower with CT than with conventional angiography (P <.001), and the mean error (16.1%) that resulted from estimation based on sharp-kernel CT images was significantly smaller than that (27.3%) from estimation based on medium-smooth-kernel CT images (P <.001). Visualization of the in-stent lumen at CT angiography with a 16-detector row scanner allows assessment of coronary artery stent patency on the basis of measured contrast enhancement.     

Effect of saline flush on enhancement of proximal and distal segments using 320-row coronary CT angiography

Objective

To investigate the effect of saline flush on coronary CT angiography of proximal, middle, and distal coronary artery segments, using 320-row CT, and to compare two injection duration protocols as to amount of contrast in the right heart chambers.

Methods

This retrospective study was approved by the local ethics committee, and the requirement for informed consent to participate in this study was waived. The final study group included 108 patients who underwent coronary CT angiography. The first 36 patients received contrast medium without saline flush (group 1); the next 36 patients received contrast medium for 14 s and saline flush (group 2); the last 36 patients received contrast medium for 12 s and saline flush (group 3). The CT number, noise, contrast-to-noise ratio (CNR), and number of segments with a CT number greater than 325 Hounsfield units (HU) were recorded for proximal, middle, and distal segments.

Results

The CT numbers and the CNR in groups 2 and 3 were significantly higher than that in group 1 (p < 0.005); the difference between groups 2 and 3 was not significant. The proportion of segments greater than 325 HU improved with saline flush (p < 0.05), with a larger improvement in the distal segments.

Conclusions

Saline flush improves enhancement and CNR of coronary arteries, particularly of distal segments, in coronary CT angiography using 320-row CT. An average contrast medium injection of 44 mL was feasible using a saline flush.     

Computed tomography angiography of carotid and coronary artery via a single-bolus injection protocol: a feasibility study using 320-row multidetector CT

Objectives

To investigate the feasibility of using a single-dose injection protocol in CT angiography (CTA) of the carotid and coronary artery with 320-row multidetector CT.

Methods

A total of 82 consecutive patients with suspected carotid artery disease underwent an original CTA protocol aiming at capturing the extra-cranial carotid arteries and coronary arteries simultaneously using 320-row MDCT. The image quality, attenuation, and CNRs of the carotid and coronary arteries were assessed. The lag time (between two separated volumetric acquisitions) was compared between patients with and without cardiac venous opacification (CVO). The contrast medium volume and radiation dose were recorded.

Results

The image quality was 99.4 % diagnostic in carotid and 86.9 % in coronary artery segments. The mean attenuation of carotid and coronary arteries ranged from 462.2 Hu to 533.7 Hu, 415.9 Hu to 454.7 Hu respectively. The mean CNR of the carotid and coronary artery ranged from 15.8 to 18.9 and 17.7 to 20.4 respectively. The lag time in patients with and without CVO was 5.75?±?1.64 s vs. 4.21?±?1.14 s (p?<?0.05). The mean radiation dose was 6.6?±?4.1 mSv.The mean contrast media volume was 71.9?±?9.1 ml.

Conclusions

The carotid and coronary artery can be imaged simultaneously via our original single-dose injection CTA protocol using 320-row CT with adequate image quality.

Key Points

? Carotid and coronary 320-row CTA can be achieved in a single-dose injection. ? Longer coverage was achieved with two or more volumes using 320-row CT. ? The single-dose protocol allows a reduced contrast agent dose of about 72 ml.     

Diagnostic performance of multidetector CT angiography for assessment of coronary artery disease: meta-analysis

PURPOSE: To review the literature on the diagnostic performance of multidetector computed tomographic (CT) angiography for assessment of symptomatic coronary artery disease, with conventional coronary angiography as the reference standard. MATERIALS AND METHODS: A PubMed and manual search of the literature published between January 1998 and May 2006 on use of multidetector CT angiography compared with coronary angiography in patients with symptomatic coronary artery disease was performed. Summary estimates of diagnostic odds ratio, sensitivity, and specificity were calculated. Random-effects models were used to compare the diagnostic performance of four-, 16-, and 64-detector CT angiographic units, and the proportion of nonassessable coronary arterial segments was evaluated. RESULTS: Fifty-four studies were included in the meta-analysis: 22 studies with four-detector CT angiography, 26 with 16-detector CT angiography, and six with 64-detector CT angiography. The pooled sensitivity and specificity for detecting a greater than 50% stenosis per segment were 0.93 (95% confidence interval [CI]: 0.88, 0.97) and 0.96 (95% CI: 0.96, 0.97) for 64-detector CT angiography, 0.83 (95% CI: 0.76, 0.90) and 0.96 (95% CI: 0.95, 0.97) for 16-detector CT angiography, and 0.84 (95% CI: 0.81, 0.88) and 0.93 (95% CI: 0.91, 0.95) for four-detector CT angiography, respectively. Results of regression analysis indicated that the diagnostic performance significantly improved with the newer generations of multidetector CT scanners (64- and 16-detector vs four-detector units), adjusted for exclusion of nonassessable segments, and contrast agent concentration used (P < .05). Simultaneously, the nonassessable proportion of segments significantly decreased with the newer generations of multidetector CT scanners, adjusted for heart rate, prevalence of significant disease, and mean age. CONCLUSION: With the newer generations of multidetector CT scanners, the diagnostic performance for the assessment of coronary artery disease has significantly improved, and the proportion of nonassessable segments has decreased.     

320层容积CT冠状动脉血管造影的护理

目的:探讨320层容积CT冠状动脉造影检查中相关的护理因素。方法:对620例(男380例,女240例,平均年龄58.4±9.2岁)临床怀疑冠心病行320层CT冠状动脉造影检查的患者在检查前、检查过程中及检查后采用有效的护理流程进行严格的护理,并对相关图像资料进行回顾性分析。结果:620例患者中605例(97.5%)的图像能满足影像学评价。在2480支冠状动脉分支中1级血管分支共1709支(68.9%),满足诊断要求的血管分支共2390支(96.4%)。结论:严格和有效的护理流程是320层容积CT冠脉造影检查成功和提高图像质量的重要保证。     

Plaque imaging with CT coronary angiography: Effect of intra-vascular attenuation on plaque type classification

AIM:To assess the attenuation of non-calcified atherosclerotic coronary artery plaques with computed tomography coronary angiography(CTCA).METHODS:Four hundred consecutive patients underwent CTCA(Group 1:200 patients,Sensation 64 Cardiac,Siemens;Group 2:200 patients,VCT GE Healthcare,with either Iomeprol 400 or Iodixanol 320,respectively) for suspected coronary artery disease(CAD).CTCA was performed using standard protocols.Image quality(score 0-3),plaque(within the accessible non-calcified component of each non-calcified/mixed plaque) and coronary lumen attenuation were measured.Data were compared on a per-segment/perplaque basis.Plaques were classified as fibrous vs lipid rich based on different attenuation thresholds.A P < 0.05 was considered significant.RESULTS:In 468 atherosclerotic plaques in Group 1 and 644 in Group 2,average image quality was 2.96 ± 0.19 in Group 1 and 2.93 ± 0.25 in Group 2(P ≥ 0.05).Coronary lumen attenuation was 367 ± 85 Hounsfield units(HU) in Group 1 and 327 ± 73 HU in Group 2(P < 0.05);non-calcified plaque attenuation was 48 ± 23 HU in Group 1 and 39 ± 21 HU in Group 2(P < 0.05).Overall signal to noise ratio was 15.6 ± 4.7 in Group 1 and 21.2 ± 7.7 in Group 2(P < 0.01).CONCLUSION:Higher intra-vascular attenuation modifies significantly the attenuation of non-calcified coronary plaques.This results in a more difficult characterization between lipid rich vs fibrous type.     

320排动态容积CT冠状动脉成像诊断冠心病的初步应用

目的探讨320排动态容积CT冠状动脉成像(CTA)诊断冠心病的准确性。方法 2010年3月至2010年9月对临床拟诊为冠心病的82例患者先后行冠状动脉CTA及冠状动脉造影(ICA)检查,并以ICA为金标准,评估320排CTA诊断冠状动脉狭窄≥50%及≥70%的敏感度、特异度、阳性预测值及阴性预测值。结果 CTA成像质量4分71例(86.6%),平均心率为67次/min;3分10例(12.2%),平均心率为74次/min;2分1例(1.2%),心率为83次/min;1分0例,全部病例均无阶梯伪影。CTA发现174个狭窄≥50%的节段,ICA发现144个以ICA为金标准,320排CTA诊断狭窄≥50%的敏感度、特异度、阳性预测值及阴性预测值分别为93.1%、96.0%、77.0%和99.0%。CTA发现40个狭窄≥70%的节段,ICA发现40个。以ICA为金标准,320排CTA诊断狭窄≥70%的敏感度、特异度、阳性预测值及阴性预测值分别为100%、95.6%、45.5%和100%。结论 320排CTA图像质量好,诊断冠心病准确可靠。     

Assessment of coronary stents using 40-detector row CT: comparison with 16-detector row CT in vitro

OBJECTIVE: To evaluate the performance of 40-detector row computed tomography (CT) in the assessment of coronary stents in comparison with 16-detector row CT. METHODS: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 types of stent (Bx-Velocity, Express2, and Driver) with an approximately 3.5-mm inner diameter filled with contrast material (450 Hounsfield units) were scanned with 2 computed tomographic scanners (collimation, 16 x 0.75 and 40 x 0.625 mm). We evaluated the in-stent stenosis visually for the 6 vascular models in 4 orientations (0, 30, 60, and 90 degrees) to the z-axis of the scanner. We evaluated attenuation values of the stent lumen of the 3 patent models in the 4 orientations. The average and standard deviation of the luminal attenuation values were assessed to evaluate the degree of blooming and streak artifacts. RESULTS: The visualization of the stent lumen of the vascular models at 90 degrees was improved using 40-detector row CT. For all the 3 stents, the average luminal attenuations values using 40-detector row CT were significantly lower than those using 16-detector row CT in all orientations. For all the 3 stents, the standard deviations of the luminal computed tomographic attenuation using 40-detector row CT were significantly smaller than those using 16-detector row CT in the 4 orientations to the z-axis except for Express 2 at 0 degrees. CONCLUSIONS: The visualization of coronary stents is improved by the use of 40-detector row CT with reduced blooming and streak artifacts.     

320排冠状动脉CTA中等渗低浓度对比剂用量的合理选择

目的：探讨在320排冠状动脉 CTA 检查中降低等渗低浓度对比剂用量的可行性。方法选取心率≤70次/min、心律规则、体质量指数(BMI)≤24 kg/m2患者64例行320排冠状动脉 CTA,采用100 kVp 管电压,威视派克270 mg I/mL 对比剂,使用前瞻性心电门控技术,自适应迭代剂量减低算法重建。根据对比剂用量的不同将其分为3组：A 组22例注射50 mL 固定剂量对比剂,注射速率为5.0 mL/s;B 组21例按0.7 mL/kg 计算剂量,注射速率为4.5 mL/s;C 组21例按0.6 mL/kg 计算剂量,注射速率为4.0 mL/s。采用单因素方差分析比较3组间感兴趣区(ROI)的 CT 值、信噪比(SNR)、对比噪声比(CNR)以及冠状动脉节段评分的差异,并对患者碘摄入量进行比较。结果3组间患者的年龄、性别比、BMI、心率等指标差异无统计学意义(P >0.05),对比剂用量及注射时间的差异有统计学意义(P <0.05)。ROI 的 CT 值从 A 组到 B 组再到 C 组呈下降趋势,A 组明显高于 B 组和 C组,差异均有统计学意义(P <0.05),而 B 组与 C 组间差异无统计学意义(P >0.05)。3组间冠状动脉节段评分、SNR 和 CNR 的差异无统计学意义(P >0.05)。C 组的碘总量和碘注入率最低。结论在320排 CT 冠状动脉血管成像中,对于心率≤70次/min、BMI≤24 kg/m2患者,按0.6 mL/kg 剂量注射等渗低浓度对比剂,图像质量能满足诊断要求,明显减少了患者的碘摄入量,降低了发生对比剂肾病的风险。     

Late defect on delayed contrast-enhanced multi-detector row CT scans in the prediction of SPECT infarct size after reperfused acute myocardial infarction: initial experience

PURPOSE: To prospectively assess the accuracy of multi-detector row computed tomography (CT) in the prediction of infarct size after successful reperfusion of acute myocardial infarction (MI) by using single photon emission computed tomography (SPECT) images obtained 6 weeks later as the reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. A total of 34 patients (29 men and five women; mean age, 56 years +/- 13) underwent dual-phase 16-detector row CT within 3 days +/- 3 after successful reperfusion of acute MI. Iodinated contrast medium (1.5 mL per kilogram of body weight) was injected at a flow rate of 3.5 mL/sec. A first arterial phase acquisition was followed 5 minutes later by a late acquisition, without reinjection of contrast medium. A radiologist and a cardiologist used a 17-segment model in a blind analysis of images obtained during late acquisition. For each segment, presence of late defect or late enhancement was recorded. Findings were compared with SPECT studies analyzed by a nuclear medicine physician and a cardiologist 6 weeks after the acute event. CT defects were compared with SPECT defects on a segmental and per-patient basis. Mean number of segments with late defects on multi-detector row CT scans was compared with infarct size on SPECT images by using the t test. RESULTS: All patients had late enhancement in the infarcted myocardium. In 27 of 34 patients, a late defect surrounded by a subepicardial late enhancement was detected. Segments with late defect on CT scans were predictive of residual perfusion defects at 6-week follow-up, with sensitivity of 78%, specificity of 91%, and accuracy of 90%. On a per-patient basis, sensitivity was 93%, specificity was 100%, and accuracy was 94%. Mean number of segments with late defects on multi-detector row CT scans (ie, 3.1 segments) was not significantly different from infarct size on SPECT images (eg, 2.5 segments) (P = .2). CONCLUSION: Late defect on multi-detector row CT scans indicates residual perfusion SPECT defect and infarct size after successfully reperfused MI, with sensitivity of 93%, specificity of 100%, and accuracy of 94%.     

Whole tumour perfusion of peripheral lung carcinoma: evaluation with first-pass CT perfusion imaging at 64-detector row CT

AIM: To prospectively assess the feasibility of a whole-tumour perfusion technique using 64-detector row computed tomography (CT) and to analyse the variation of CT perfusion parameters in different histological types, sizes, and metastases in patients with peripheral lung carcinoma. METHODS AND MATERIALS: Ninety-seven pathologically proved peripheral lung carcinomas (less than 5 cm in largest diameter) underwent dynamic contrast-enhanced CT using a 64-detector row CT machine. Small amounts of iodinated contrast medium with a sharp bolus profile (50 ml, 6-7 ml/s), and 12 repeated fast acquisitions encompassing the entire tumour lesion were adopted to quantify perfusion of the whole-tumour during first-pass of contrast medium. Four kinetic parameters, including perfusion, peak enhancement intensity (PEI), time to peak (TTP), and blood volume (BV), were measured and statistically compared among different histological types, sizes, and metastases. RESULTS: Mean values for perfusion, PEI, TTP, and BV of the 97 lung carcinomas were 57.5+/-45.4 ml/min/ml (range 5.9-243 ml/min/ml), 53.4+/-40.6 HU (range 10.3-234.4 HU), 34+/-11s (range 11-60s), and 30.1+/-21.7 ml/100g (range 3.9-113.4 ml/100g), respectively. No statistical differences were found between the histological types regarding the perfusion parameters (p>0.05). Perfusion, PEI, and BV of stage T2 tumours were significantly lower than those of stage T1 tumours (all p < 0.05), whereas no statistically significant differences was found between other stages of tumours (all p>0.05). Perfusion of the tumours with distant metastasis was significantly higher than that of the tumours without distant metastasis (p<0.05), but there was no statistically significant difference between nodal metastasis positive and negative groups (p>0.05). CONCLUSION: The present study of first-pass perfusion imaging using 64-detector row CT could provide a feasible method for assessment of whole-tumour perfusion. CT perfusion parameters of peripheral lung carcinoma may be associated with tumour size and distant metastasis.     

Focal tracer uptake: a potential artifact in contrast-enhanced dual-modality PET/CT scans.

This study was performed to evaluate a possible artifact related to the administration of intravascular contrast agent in dual-modality PET/CT imaging. METHODS: Thirty oncology patients underwent whole-body PET/CT. CT images, which were collected in the presence of intravenous and oral iodinated contrast agent, were used for PET attenuation correction. PET images were assessed for the artifact, defined as a region of high count rate on attenuation-corrected images in accurate coregistration with a contrast-enhanced blood vessel. Intravascular enhancement of thoracic veins was quantified by application of regions of interest, and quantities in patients with the artifact (group 1) and without the artifact (group 2) were correlated. Body surface area was calculated for all patients. RESULTS: The contrast-induced PET artifact was present in 4 (13%) of 30 patients. Mean density differences in intravascular enhancement were highly significant (P < 0.001) in a comparison of group 1 (2,262 +/- 304 Hounsfield units [HU]) and group 2 (1,058 +/- 209 HU). Body surface area was significantly lower (P = 0.035) in the patients of group 1 (1.67 +/- 0.11 m(2)) than in the patients of group 2 (2.01 +/- 0.18 m(2)). CONCLUSION: Contrast-enhanced dual-modality PET/CT examinations may result in a PET artifact that is due to the transient bolus passage of undiluted intravenous contrast agent.