Helical Computed Tomography Angiography Research Articles

Dynamics of Intracranial Pressure and Cerebrovascular Reactivity During Intrahospital Transportation of Traumatic Brain Injury Patients in Coma.

Intrahospital transportation (IHT) of patients with traumatic brain injury (TBI) is common and may have adverse consequences, incurring inherent risks. The data on the frequency and severity of clinical complications linked with IHT are contradictory, and there is no agreement on whether it is safe or potentially challenging for neurocritical care unit patients. Continuous intracranial pressure (ICP) monitoring is essential in neurointensive care. The role of ICP monitoring and management of cerebral autoregulation impairments in IHT of patients with severe TBI is underinvestigated. The purpose of this nonrandomized retrospective single-center study was to assess the dynamics of ICP and an improved pressure reactivity index (iPRx) as a measure of autoregulation during IHT. Seventy-seven men and fourteen women with severe TBI admitted in 2012-2022 with a mean age of 33.2 ± 5.2years were studied. ICP and arterial pressure were invasively monitored, and cerebral perfusion pressure and iPRx were calculated from the measured parameters. All patients were subjected to dynamic helical computed tomography angiography using a 64-slice scanner Philips Ingenuity computed tomography scan 1-2days after TBI. Statistical analysis of all results was done using a paired t-test, and p was preset at < 0.05. The logistic regression analysis was performed for cerebral ischemia development dependent on intracranial hypertension and cerebrovascular reactivity. IHT led to an increase in ICP in all the patients, especially during vertical movement in an elevator (maximum 75.2mm Hg). During the horizontal transportation on the floor, ICP remained increased (p < 0.05). The mean ICP during IHT was significantly higher (26.1 ± 13.5mm Hg, p < 0.001) than that before the IHT (19.9 ± 5.3mm Hg). The mean iPRx after and before IHT was 0.52 ± 0.04 and 0.23 ± 0.14, respectively (p < 0.001). Both horizontal and vertical transportation causes a significant increase in ICP and iPRx in patients with severe TBI, potentially leading to the outcome worsening.

Prevalence and Predictor of Pulmonary Embolism in a Cohort of Chinese Patients with Acute Proximal Deep Vein Thrombosis

The aim of this study is to investigate the incidence of pulmonary embolism (PE) in a cohort of Chinese patients with acute (<14days) proximal (above-knee) deep vein thrombosis (DVT) in the lower limbs, and to evaluate whether the location of thrombosis is associated with the existence of PE. A retrospective review of patients diagnosed with acute proximal DVT from January 2014 to June 2018 at a single center was performed. Helical computed tomography angiography was performed to screen PE within 48hr after admission. Multiple factors associated with PE were compared between the PE group and the non-PE group. A total of 100 patients with acute proximal DVT were screened for PE. The mean age was 56.9±18.1 (range 21-88) years, and 55% were male. The most common risk factors of DVT were immobilization (38%), malignancy (27%), and trauma or surgery (21%). Majority of the patients' thrombosis was located at the left leg (66%) and 8 patients had bilateral lower limb DVT. Femoral vein was involved in 52 patients (52%), while iliofemoral thrombosis was identified in 48 patients (48%). PE was identified in 58 patients (58%), including 3 massive and 55 nonmassive PE. There was no statistical difference between the PE group and the non-PE group in terms of age, sex, and risk factors. The D-dimer level was associated with the existence of PE (P=0.038). Patients with iliofemoral thrombosis had a similar incidence of PE compared with those with femoral thrombosis alone (P=1.000). PE occurred in more than half of patients with acute proximal DVT, despite the fact that most of them were asymptomatic. In this study, existence of PE did not correlate with pelvic thrombosis. Increasing D-dimer level was statistically associated with the presence of PE.

Cerebral Arterial Compliance in Polytraumazed Patients with Cerebral Vasospasm.

The purpose was to determine the status of the cerebral arterial compliance (cAC) in a concomitant head injury and cerebral vasospasm (CVS) with and without the development of intracranial hematomas (ICH). In Materials and Methods, we examined 80 polytrauma patients with severe TBI and CVS. During or immediately after dynamic helical computed tomography angiography (DHCTA), the monitoring of the transcranial Doppler of the MCA was recorded bilaterally with 2-MHz probes. The cerebral blood volumes were calculated from the DHCTA data with complex mathematical procedures using the "direct flow model" algorithm. In Results, CAC was significantly decreased (p<0.001) in both the first and second group TBI and CVS (with or without ICH) in comparison with normal data (p<0.001) and TBI without CVS. The cAC was significantly decreased on the side of the former hematoma with CVS than on the contralateral side with CVS (р=0.003). In Conclusion, the cAC in TBI and CVS gets significantly lower as compared to the normal condition (p<0.001). After removal of the ICH and development of CVS, the compliance in the perifocal zone remains much lower (р=0.003) as compared to compliance of the other brain hemisphere.

Planning endovascular aortic repair with standard and fenestrated-branched endografts.

Endovascular aortic repair (EVAR) has been accepted as the first treatment option in most patients with infrarenal and thoracic aortic aneurysms. Advantages include its minimal invasive approach and lower risk of mortality and morbidity compared to open surgical repair. In patients with complex aneurysms involving side branches, novel techniques of parallel, fenestrated and branched endografts have expanded the indications of EVAR. Preoperative planning is of paramount importance to achieve technical success and to minimize risks of these procedures. In most centers, anatomical measurements are based on helical computed tomography angiography and/or magnetic resonance angiography. This article summarizes the most important aspects on planning standard and complex EVAR to treat aortic aneurysms and dissections.

How to perform 3D reconstruction of skull base tumours

The surgical management of skull base lesions is difficult due to the complex anatomy of the region and the intimate relations between the lesion and adjacent nerves and vessels. Minimally invasive approaches are increasingly used in skull base surgery to ensure an optimal functional prognosis. Three-dimensional (3D) computed tomography (CT) reconstruction facilitates surgical planning by visualizing the anatomical relations of the lesions in all planes (arteries, veins, nerves, inner ear) and simulation of the surgical approach in the operating position. Helical CT angiography is performed with optimal timing of the injection in terms of tumour and vessel contrast enhancement. 3D definition of each structure is based on colour coding by automatic thresholding (bone, vessels) or manual segmentation on each slice (tumour, nerves, inner ear). Imaging is generally presented in 3 dimensions (superior, coronal, sagittal) with simulation of the surgical procedure (5 to 6 reconstructions in the operating position at different depths).

Helical Computed Tomography - Anatomy of the Cat Abdomen

Computed tomography (CT) is a most valuable technique for the diagnosis of abdominal disorders. In veterinary medicine, x-ray and ultrasound are the imaging modalitys of choice for the abdomen, but CT can provide information that cannot be obtained by other means. One mature, female, domestic cat, 4 kg weight was used for this study. The cat was clinically healthy, with no abnormal findings at haematological and biochemical analysis. It was premedicated with 20 µg/kg medetomidine and 0.3mg/kg butorphanol IM. For induction of anaesthesia, 3 to 5 mg/kg propofol was administered IV. Anaesthesia was maintained with a mixture of isoflurane and oxygen. The patient was positioned in sternal recumbency. CT scans were performed with a helical CT scanner Hi Speed CT/e Dual; General Electric. Technical factors were 120 kVp and 50 mA settings, with 1 rotation/s. All sections were imaged with soft-tissue window. CT scans were performed after IV injection of iodinated contrast medium, iopamidol, 2 mL/kg. The images are presented cranialy to caudal progression from the 8th thoracic vertebra to the level of the pelvic inlet. Identifiable anatomical structures are labelled on the CT images. The stomach is left-sided with the gastric folds less numerous and thinner than those in the dogs. The normal small intestine contains less gas in cats. The feline cecum is very short. The liver showed a low attenuation with the mediastinum-vascular window settings, allowing better visualisation of the hepatic lobes and interlobular fissures. The gallbladder and bile ducts were also better visualised. CT imaging studies can provide additional information in patients with radiographic and ultrasonographic patterns of abdominal disorders, as a specialised imaging method, a useful preoperative technique and a precise staging tool. CT improves the image quality further and allows better timing of vascular phases. Helical CT angiography enables visualization of contrast-enhanced abdominal vessels using only a peripheral venous injection of iodinated contrast medium.

Colonic Angiodysplasia with a Huge Submucosal Hematoma in the Sigmoid Colon.

Colonic angiodysplasia (AD) with bleeding as a comorbidity in the aging population is being increasingly reported. However, to our knowledge, there is no report on colonic AD accompanied by a huge hematoma. Herein, we report a case of colonic AD with a huge submucosal hematoma. A 75-year-old man with sudden melena was referred to our hospital. Helical computed tomographic angiography (CTA) revealed bleeding from the sigmoid colon. Additionally, colonoscopy showed a huge submucosal hematoma with bleeding in the sigmoid colon. As endoscopic hemostasis was difficult, sigmoidectomy was performed. The pathological diagnosis was colonic AD. The present case indicates that colonic AD should be considered in the differential diagnosis for melena. In addition, the case shows that helical CTA, which is a noninvasive imaging modality, is useful for the diagnosis of colonic AD and is as effective as colonoscopy and angiography for diagnosis.

256 Slice Multi-detector Computed Tomography Thoracic Aorta Computed Tomography Angiography: Improved Luminal Opacification Using a Patient-Specific Contrast Protocol and Caudocranial Scan Acquisition.

Caudocranial scan direction and contrast injection timing based on measured patient vessel dynamics can significantly improve arterial and aneurysmal opacification and reduce both contrast and radiation dose in the assessment of thoracic aortic aneurysms (TAA) using helical thoracic computed tomography angiography (CTA). To investigate opacification of the thoracic aorta and TAA using a caudocranial scan direction and a patient-specific contrast protocol. Thoracic aortic CTA was performed in 160 consecutive patients with suspected TAA using a 256-slice computed tomography scanner and a dual barrel contrast injector. Patients were subjected in equal numbers to one of two contrast protocols. Patient age and sex were equally distributed across both groups. Protocol A, the department's standard protocol, consisted of a craniocaudal scan direction with 100 mL of contrast, intravenously injected at a flow rate of 4.5 mL/s. Protocol B involved a caudocranial scan direction and a novel contrast formula based on patient cardiovascular dynamics, followed by 100 mL of saline at 4.5 mL/s. Each scan acquisition comprised of 120 kVp, 200 mA with modulation, temporal resolution 0.27 seconds, and pitch 0.889:1. The dose length product was measured between each protocol and data generated were compared using Mann-Whitney U nonparametric statistics. Receiver operating characteristic analysis, visual grading characteristic (VGC), and κ analyses were performed. Mean opacification in the thoracic aorta and aneurysm measured was 24 % and 55%, respectively. The mean contrast volume was significantly lower in protocol B (73 ± 10 mL) compared with A (100 ± 1 mL) (P<0.001). The contrast-to-noise ratio demonstrated significant differences between the protocols (protocol A, 18.2 ± 12.9; protocol B, 29.7 ± 0.61; P < 0.003). Mean effective dose in protocol B (2.6 ± 0.4 mSv) was reduced by 19% compared with A (3.2 ± 0.8 mSv) (P < 0.004). Aneurysmal detectability demonstrated significant increases by receiver operating characteristic and visual grading characteristic analysis for protocol B compared with A (P < 0.02), and reader agreement increased from poor to excellent. Significant increase in the visualization of TAAs following a caudocranial scan direction during helical thoracic CTA can be achieved using low-contrast volume based on patient-specific contrast formula.

Application of 64-slice spiral computed tomography angiography in extremity vascular injuries.

The objective of the current study was to assess the utility of 64-row helical computed tomography angiography (CTA) in the evaluation of extremity vascular traumas. The extremities from 17 clinical cases of suspected traumatic vascular damage were evaluated using 64-row helical CTA. To evaluate extremity vascular traumas using CTA, volume rendering, multiple planar reconstruction, and curved planar reconstruction technology were applied to accurately and rapidly indicate the type and extent of blood vessel damage, as well as any relationship with injuries to adjacent bones, joints, soft tissue swelling, or hematomas. The types of extremity vascular traumas evaluated included damaged arteries, artery spasms or block, blood vessels shifted because of pressure, pseudo aneurysms, arteriovenous fistula, and vein occlusion. The results of the study indicated that 64-row helical CTA could be highly efficient and accurate in the evaluation of extremity vascular traumas, and could aid in making clinical assessments.

Comparison between helical computed tomography angiography and intraoperative findings.

Background:Live donor nephrectomy has gained popularity on account of the laparoscopic technique, to overcome a small donor pool. Laparoscopic donor nephrectomy requires a precise study of the vascular and morphological renal anatomy, as laparoscopy is technically challenging due to the limited field of vision. In-depth knowledge of the renal anatomy before a laparoscopic procedure is essential for a successful transplant. The left kidney is preferred over the right even in cases of multiple vessels because of the long renal vein, which requires precise preoperative vascular mapping. Helical computerized tomography (CT) angiography, with its axial, coronal, and 3D reconstruction, gives a better understanding of renal anatomy. There are instances where the helical CT findings are misleading and less informative in a small number of cases. This study highlights a case study of the helical CT findings compared with the intraoperative findings of 200 live donors, who underwent laparoscopic donor nephrectomy, and the renal anatomy has been understood at the same time.Aims:1. To compare the helical CT findings on the operated side with the intraoperative findings. 2. To analyze the CT findingsMaterials and Methods:Two hundred cases of laparoscopic transperitoneal donor nephrectomy were included in this study.Statistical Method Used:Chi square test was the statistical test used to compare the findings between CT and the intraoperative data.Results:The axial, coronal, and 3D images of the CT findings were on par with the intraoperative findings in most of the cases. Incidental findings help in the better planning of surgery. Multiple vessels on the left side are preferred over the right sided normal anatomy; with not much technical difficulty with the aid of a helical CT. Male donors had more incidences of multiple vessels, gonadal vein, Retroaortic Renal Vein (RARV), lumbar vein, and duplication of ureter, compared to females. Furthermore, these variations are more in the left side donors. Ninety-two percent of the cases in this study are left-sided donors. The helical CT finding shows that renal vein variations are more on the right side.Conclusions:Helical CT is important in delineating the arterial, venous, and ureteral anatomy and can show the important incidental findings. Left renal donors and males have more variations in their renal anatomy. Technically challenging laparoscopic nephrectomy on the multiple-vessel-side donor is possible with the aid of helical CT. The importance of the CT in evaluating donor renal anatomy for a technically challenging laparoscopic donor nephrectomy is commendable.

Evidence of Incremental Diagnostic Quality Gain in The Assessment of Pulmonary Embolism With Computed Tomography Angiography versus Ventilation Perfusion Scan Using Wells Score and Bayesian Statistical Modeling

To assess the diagnostic value of contrast enhanced helical computed tomography angiography (CTA) in comparison to ventilation perfusion (V/Q) scan, in the diagnostic assessment of pulmonary embolism (PE) in low, moderate, and high risk wells-score criteria stratified patients using Bayesian statistical modeling.

Timing-Invariant Reconstruction for Deriving High-Quality CT Angiographic Data from Cerebral CT Perfusion Data

To suggest a simple and robust technique used to reconstruct high-quality computed tomographic (CT) angiographic images from CT perfusion data and to compare it with currently used CT angiography techniques. Institutional review board approval was waived for this retrospective study, which included 25 consecutive patients who had had a stroke. Temporal maximum intensity projection (tMIP) CT angiographic images were created by using prior temporal filtering as a timing-insensitive technique to produce CT angiographic images from CT perfusion data. The temporal filter strength was optimized to gain maximal contrast-to-noise ratios (CNRs) in the circle of Willis. The resulting timing-invariant (TI) CT angiography was compared with standard helical CT angiography, the arterial phase of dynamic CT angiography, and nonfiltered tMIP CT angiography. Vascular contrast, image noise, and CNR were measured. Four experienced observers scored all images for vascular noise, vascular contour, detail of small and medium arteries, venous superimposition, and overall image quality in a blinded side-by-side comparison. Measurements were compared with a paired t test; P ≤ .05 indicated a significant difference. On average, optimized temporal filtering in TI CT angiography increased CNR by 18% and decreased image noise by 18% at the expense of a decrease in vascular contrast of 3% when compared with nonfiltered tMIP CT angiography. CNR, image noise, vascular noise, vascular contour, detail visibility of small and medium arteries, and overall image quality of TI CT angiograms were superior to those of standard CT angiography, tMIP CT angiography, and the arterial phase of dynamic CT angiography at a vascular contrast that was similar to that of standard CT angiography. Venous superimposition was similar for all techniques. Image quality of the arterial phase of dynamic CT angiography was rated inferior to that of standard CT angiography. TI CT angiographic images constructed by using temporally filtered tMIP CT angiographic data have excellent image quality that is superior to that achieved with currently used techniques, but they suffer from modest venous superimposition.

Diagnostic Accuracy of Early Computed Tomographic Angiography for Visualizing Medium Sized Inferior and Posterior Projecting Carotid System Aneurysms

Conventional angiography, generally referred to as intra-arterial digital subtraction angiography, still remains the gold standard reference method for the diagnosis of intracranial aneurysms, helical computed tomography angiography (CTA) is a new non-invasive volumetric imaging method. This study was conducted to screen patients presenting with subarachnoidhemorrhage by CTA before conventional digital subtraction angiography (DSA) and subsequently comparing the results for various aneurysm projections. In a prospective study, 99 consecutive patients with an initial diagnosis of subarachnoid hemorrhage were screened for aneurysms with CTA followed by conventional DSA. There were 17 cases with negative angiograms in whom repeat angiograms, three months later were negative for 15 cases, while two cases were found to bear aneurysm on the repeat examination. Eighty two patients had at least one proven aneurysm on initial DSA and two on the repeat angiogram. Out of 84 patients, five underwent endovascular treatment and 79 patients who underwent surgical clipping were considered for projection evaluation. Sensitivity of CTA was 98.78% (95% confidence interval [CI], 93.4-99.7%), while the specificity was 100% (95% CI, 81.57-100%) and the kappa coefficient of agreement between CTA and DSA was 96.5%. The most significant discrepancies with DSA findings were for visualizing the projection of inferior and posterior projecting proximal anterior circulation aneurysms. Helical CTA was in good concordance with DSA for screening of cerebral aneurysms; however, for exact visualization of the aneurysm neck and its projection, especially if it is inferior or posterior, DSA remains the gold standard.

Right aortic arch with aberrant left subclavian artery—prenatal diagnosis and evaluation of postnatal outcomes: Report of three cases

Objective To present prenatal diagnosis of a right aortic arch (RAA) with an aberrant left subclavian artery (LSCA) by the three vessels and trachea (3VT) view using routine ultrasound and the newer technique of three-dimensional power Doppler ultrasound (3D-PDU) together with a discussion of the postnatal outcome. Case Reports Three fetuses having an RAA with an aberrant LSCA were diagnosed prenatally between January 2004 and June 2009. They were all detected at between 20 and 24 weeks by routine ultrasound examination at our hospital. All of them were diagnosed via the 3VT view of the fetal upper mediastinum using ultrasound, which revealed an abnormal U-shaped pattern instead of a normal V-shaped confluence; furthermore, 3D-PDU showed an abnormal RAA and an aberrant LSCA with a vascular ring. These abnormalities were not combined with any other congenital cardiac defects in our three cases. A normal chromosome complement was present without microdeletion of chromosome 22q11.2 in all three cases. Two of the cases were genetically assessed prenatally and the other was assessed postnatally. After delivery, diagnosis was confirmed by echocardiography and three-dimensional 64-slices helical computed tomography angiography. Two of the three fetuses were asymptomatic postnatally, whereas one fetus presented with symptoms of tracheoesophageal compression caused by the vascular ring, but this had improved by 8 months of age. Conclusion The 3VT view in routine prenatal ultrasound examination is important and essential for the prenatal diagnosis of an RAA with an aberrant LSCA. Moreover, 3D-PDU is able to provide a more clear-cut cardiovascular structure, which helps with the diagnosis.

Evaluation and Management of Peripheral Vascular Injury. Part 1. Western Trauma Association/Critical Decisions in Trauma

This is a position article from members of the Western Trauma Association (WTA). Because there are no prospective randomized trials on the evaluation and management of peripheral vascular trauma, the algorithm (Fig. 1) is based on the expert opinion of WTA members and published observational studies. It may not be applicable at all hospitals caring for injured patients. The algorithm contains letters that correspond to lettered text that is intentionally concise. This Part I algorithm emphasizes evaluation, diagnosis, and need for operation versus a therapeutic procedure performed in interventional radiology, while a Part II algorithm (2011) will focus on operative techniques. Peripheral vascular injures defined as axillobrachial and branches in the upper extremity and femoropopliteal and branches in the lower extremity account for 40% to 75% of all vascular injuries treated in civilian trauma centers.1–4 With the exception of the axillary artery, the long tracks of named arteries and veins in the extremities make them particularly susceptible to either penetrating or blunt trauma. This fact coupled with the smaller diameter of many of these vessels (as compared with those in the thorax or abdomen) and the ability of the patient and others to control external hemorrhage with compression contribute to a low incidence of death in the field.

Computed tomography angiography in children with cardiovascular disease: low dose techniques and image quality

Dose reduction techniques for computed tomography angiography (CTA) in children with cardiovascular diseases have the potential of reducing risks of radiation-induced cancer. To evaluate effectiveness of these techniques, both radiation dose and image quality must be compared. While clinically practical methods of estimating effective dose are available, there are no generally accepted metrics for the assessment of image quality in CTA. We introduce a measurable and reproducible image quality index, CTA QI. Using this index, along with calculated effective dose, we test the hypothesis that volume scan CTA delivers comparable image quality at substantially reduced radiation dose when compared to helical CTA. CTA QI is a measure of intraluminal contrast variation in three-dimensions, and it is calculated from standardized measurements of means and standard deviations of Hounsfield units in the thoracic descending aorta. From institutional database, 83 studies of CTA for thoracic cardiovascular diseases were retrospectively identified. CTA QI values were independently measured by two radiologists and compared using correlation. CTA QI and DLP-derived effective dose were compared for the following groups: non-cardiac gated wide-detector and helical CTA, ECG-synchronized retrospective wide-detector and helical CTA, ECG-synchronized wide detector retrospective and target technique CTA. Statistical significance was evaluated with the Student-t test. The correlations of CTA QI values between the radiologists were 0.83 and 0.92 for non-gated studies and ECG-synchronized studies respectively. Comparing non-gated volume scan CTA to helical CTA, there was a radiation dose reduction of 69% (P < 0.0001) without a significant change in CTA QI (1.4 ± 1.0 vs. 1.9 ± 1.4, P = 0.13). Comparing retrospective ECG-synchronized wide-detector CTA to helical CTA, there was a radiation dose reduction of 46% (P < 0.0001) with and improvement in CTA QI (1.0 ± 0.8 vs. 3.7 ± 3.4, P < 0.01). Comparing ECG-synchronized wide-detector target CTA to retrospective CTA, there was a radiation dose reduction of 68% (P < 0.0001, but at the cost of a significant reduction in CTA QI (2.0 ± 1.0 vs. 0.8 ± 0.4, P < 0.0044). CTA QI is a simple, reproducible metric of image quality suited for comparing CTA studies. Using this quality index, we establish that CTA performed with wide-detector scan techniques can yield substantially lower radiation dose without compromising diagnostic imaging quality. A wide-detector target technique can further reduce effective dose compared to wide-detector retrospective ECG-synchronization, but with a reduction in image quality.

Diagnosing a large slowly enhanced cerebral aneurysm using four-dimensional multiphase dynamic contrast-enhanced computed tomography angiography

Our patient was diagnosed with acute subarachnoid hemorrhage on plain head computed tomography (CT). Multiphase dynamic contrast-enhanced CT angiography on a 64-row multidetector scanner revealed a large aneurysm in the left middle cerebral artery that was not detected on conventional helical CT angiography. We believed that increased intracranial pressure and rough thrombus within the aneurysm delayed its peak enhancement. Our case demonstrates the diagnostic utility of four-dimensional CT with multiphase volume data in cases of lesions with delayed enhancement.

A Method for Reconstructing the Arterial Input Function during Helical CT: Implications for Myocardial Perfusion Distribution Imaging

To determine if a multidetector computed tomographic (CT) image acquisition and analysis method can enable accurate measurement of the arterial input function (AIF) during first-pass adenosine stress helical multidetector CT angiography and to test the effect of using this method on the semiquantitative assessment of myocardial perfusion distribution. The animal care and use committee of Johns Hopkins University approved the use of all procedures. The AIF was reconstructed by using a combination of bolus-tracking and time-registered helical multidetector CT data. After the AIF reconstruction method was validated in healthy animals, coronary stenosis was induced in seven dogs and contrast material-enhanced multidetector CT was performed during adenosine infusion (0.14-0.21 mg per kilogram of body weight per minute). Myocardial attenuation density (AD) parameters normalized to portions of the AIF were compared with microsphere myocardial blood flow (MBF) measurements at linear regression analysis. There was no significant difference between the area under the curve (AUC) for dynamic multidetector CT-derived AIF (3108 + or - 1250 [standard deviation]) and that for combined bolus-tracking and time-registered multidetector helical CT-derived AIF (3086 + or - 941) (P = .90). When AIF analysis was applied to helical multidetector CT myocardial perfusion measurements, the correlation between MBF and mean myocardial AD normalized to the AUC for the entire AIF was significant (R(2) = 0.82, P <.001). Myocardial AD normalized to the AUC for the AIF measured during helical multidetector CT correlated best with MBF (R(2) = 0.86, P <.001). The combination of bolus tracking and time-registered helical imaging enables reconstruction of the AIF during multidetector CT perfusion imaging. The helical CT AIF can be used to improve the semiquantitative assessment of myocardial perfusion distribution.

Thoracic Aorta: Prospective Electrocardiographically Triggered CT Angiography with Dual-Source CT—Feasibility, Image Quality, and Dose Reduction

To prospectively investigate the feasibility, image quality, and radiation dose for prospective electrocardiographically (ECG) triggered sequential dual-source computed tomographic (CT) angiography of the thoracic aorta in comparison to retrospective ECG-gated helical dual-source CT angiography. This study was approved by the institutional review board; informed consent was obtained. One hundred thirty-nine patients referred for ECG-assisted dual-source CT angiography of the thoracic aorta were prospectively enrolled. Inclusion criteria were stable sinus rhythm and heart rate of 80 beats per minute or less. Tube voltage was adjusted to body mass index (< 25.0 kg/m(2), 100 kV, n = 58; > or = 25.0 kg/m(2), 120 kV, n = 81). In both cohorts, patients were randomly assigned to prospective or retrospective ECG-assisted data acquisition. In both groups, tube current (250 mAs per rotation) was centered at 70% of the R-R cycle. The presence of motion or stair-step artifacts of the thoracic aorta was independently assessed by two readers. Effective radiation dose was calculated from the dose-length product. Subjective scoring of motion and stair-step artifacts was equivalent for both techniques. Scan length was not significantly different (23.8 cm +/- 2.4 [standard deviation] vs 23.7 cm +/- 2.5 for prospective and retrospective ECG-triggered CT angiography, respectively; P = .54). Scanning time was significantly longer for prospective ECG-triggered CT angiography (18.8 seconds +/- 3.4 vs 16.4 seconds +/- 3.3, P < .001). Mean estimated effective dose was significantly lower for prospective data acquisition (100 kV, 1.9 mSv +/- 0.5 vs 4.1 mSv +/- 0.7, P < .001; 120 kV, 5.3 mSv +/- 1.1 vs 9.5 mSv +/- 3.0, P < .001). Prospective ECG-gated sequential dual-source CT angiography of the thoracic aorta is feasible, despite the slightly longer acquisition time. Thus, motion-free imaging of the thoracic aorta is possible at significantly lower radiation exposure than retrospective ECG-gated helical dual-source CT angiography in certain patients with a regular heart rate.

Imaging of blood flow in cerebral arteries with dynamic helical computed tomography angiography (dhcta) using a 64-row CT scanner

Cerebral computed tomography angiography (CTA) depicts a structural image of intracranial arteries without providing much time-resolved information on blood flow dynamics. Current CT technology allows obtaining of rapidly repeated helical scans during the arterial contrast filling phase after an intravenous contrast injection. To report our experience on dynamic CT imaging in determining the direction of contrast filling within proximal intracranial arteries of operated cerebral artery aneurysm patients. Such dynamic information can help detect vascular occlusion or severe spasm. The method is here referred to as dynamic helical CT angiography (DHCTA). We retrospectively collected image and related technical data for 23 patients who underwent DHCTA and CTA during their first postoperative day after cerebral artery aneurysm surgery. For DHCTA, we had helically scanned a 4-cm tissue volume three times in succession with a 64-row CT scanner at intervals of 2.6 s during arterial contrast filling after an intravenous contrast injection. We assessed how well DHCTA succeeded in demonstrating the direction of contrast filling in the proximal intracranial arteries, evaluated clinically relevant structural information provided by DHCTA and CTA, and compared radiation doses for the two methods. For 21 patients, DHCTA outlined the direction of contrast filling in proximal intracranial arteries. As to arterial spasm and residual filling of the operated aneurysm, CTA and DHCTA gave similar information. Radiation doses were higher (P<0.000001) for DHCTA than for CTA at 120 kV tube voltage. At 100 kV, the difference was smaller, but doses for DHCTA still exceeded (P<0.05) those for CTA. DHCTA gave dynamic information unobtainable with CTA and could prove useful in selected clinical settings.