Patients Underwent CT Angiography Research Articles

Incidence of Extrinsic Compression of the Internal Jugular Vein in Unselected Patients Undergoing CT Angiography

Little is known about how commonly the internal jugular vein is compressed by extrinsic structures in the upper neck. The purpose of this paper was to identify the frequency and cause of external compression of the superior segment of the internal jugular vein. Retrospective review of CT angiograms of the neck was performed in 108 consecutive patients. Axial source images were evaluated for moderate (>50%) or severe (>80%) stenosis of the internal jugular vein on the basis of external compression. The cause of extrinsic compression was also recorded. In cases with stenosis, the presence of ipsilateral isoattenuated collateral veins was recorded and considered representative of collateral flow. Moderate stenosis was seen in 33.3% of right and 25.9% of left internal jugular veins. Severe stenosis was seen in 24.1% of right and 18.5% of left internal jugular veins. The most common causes of extrinsic compression included the styloid process and the posterior belly of the digastric muscle. In patients with severe internal jugular vein stenosis, 53.8% of right sides and 55% of left sides had associated condylar collaterals. Extrinsic compression of the superior segment of the internal jugular vein is a common finding in unselected patients, often caused by the styloid process or the posterior belly of the digastric muscle. Presence of severe stenosis is not universally associated with collateral formation.

Pseudostenosis at the Origin of the Vertebral Artery on Contrast-enhanced MRA: Correlation with Aortic Motion on Dynamic 3D Time-Resolved Contrast-Enhanced MRA

Purpose : The origin of the vertebral artery (VA) is a frequent site of pseudostenosis on contrast-enhanced MRA (CEMRA). The purpose of this study is to evaluate the relationship between the motion of the aortic arch and pseudostenosis at the origin of the VA. Materials and Methods: Our study had approval of our institutional review board. 47 patients underwent CT angiography (CTA), CE-MRA, and 3D time-resolved contrast-enhanced MRA (TR-CEMRA) within 6.87±9.89 days (mean±SD). Percent stenosis using the NASCET criteria was measured on CTA and CE-MRA. CTA was used as a reference standard to classify the CE-MRA into pseudostenosis and control group. Pseudostenosis was determined as 50%99% stenosis observed on CE-MRA but normal to less than 50% stenosis on CTA. Aortic motion (distance between the highest position and lowest position of aortic arch) was measured on TR-CEMRA. Age, route of intravenous contrast media, motion of aortic arch, and normal distal diameter of VA were compared between the two groups. Results: There were 17 patients and 23 vertebral arteries of pseudostenosis. Patients with pseudostenosis showed more aortic motion (3.61±1.88 vs. 2.05±1.97 mm) and older age (71.29±8.88 vs. 62.32±13.19 year-old). Route of intravenous contrast media and normal distal diameter of VA were not associated with pseudostenosis. Conclusion: VA origin is a frequent site of pseudostenosis. Older age and more motion of aortic arch are associated with pseudostenosis on CE-MRA.

Spectral CT imaging in the diagnosis of pulmonary embolism using quantitative iodine-based material decomposition images

Objective To assess the diagnostic value of CT spectral imaging using quantitative iodine-based material decomposition images in the evaluation of pulmonary embolism. Methods Fifty-three patients underwent CT angiography with spectral imaging mode on a GE Discovery CT750HD scanner. Iodine distribution in the lung parenchyma using the iodine-based material decomposition images was quantitatively measured by post-processing. Monochromatic CT angiographic images were reconstructed from the same data sets and thee images were reviewed for the identification and localization of pulmonary embolism as well as the degree ( partial or complete) of the embolic occlusion. The number and location of perfusion defects were recorded. The iodine content of perfusion defects and normal lung parenchyma on the iodine maps were measured by one reader using an ROI analysis. Comparative analyses were obtained using the Chi-square test for categorical data. Two independent samples rank test and 2 related samples signed-rank test were used to compare iodine densities between different groups. Results CT angiography showed no pulmonary embolism in 33 patients, and iodine distribution was homogeneous. A total of 93 clots with lobar ( n = 26), segmental (n = 54) and sub-segmental (n=13) distribution were detected in 19 patients; Fifty-one clots were occlusive and 42 clots were non-occlusive. The iodine-based material decomposition images of all occlusive clots showed lobar, segmental or sub-segmental iodine distribution defects; whereas eleven of 42 non-occlusive clots had evidence of iodine distribution defects. There was significant difference ( x2 = 39. 94,P＜0. 01 ) in the perfusion defects between occlusive and non-occlusive clots. There was a significant difference in iodine content between normal lung parenchyma [ (1.92 ±0. 54) g/L] and perfusion defects [ (0. 30 ± 0. 20)g/L] (Z= -5.63, P ＜ 0. 01 ). There was a significant difference in the iodine content of peffusion defects before [ (0. 26 ± 0. 23 )g/L] and after anticoagulation [ (0. 94 ± 0. 50 )g/L ] ( Z = -3.93,P ＜ 0. 01 ). Conclusion With the ability of iodine mapping, CT spectral imaging is areliable method in the evaluation of pulmonary embolism both qualitatively and quantitatively, and may be a useful tool in providing information regarding the severity of PE and monitoring therapeutic efficacy. Key words: Tomography, X-ray computed; Pulmonary embolism

Dual-Energy CT for Detection of Endoleaks After Endovascular Abdominal Aneurysm Repair: Usefulness of Colored Iodine Overlay

The purpose of our study was to evaluate the value of dual-source dual-energy CT with colored iodine overlay for detection of endoleaks after endovascular abdominal aortic aneurysm repair. We also calculated the potential dose reduction by using a dual-energy CT single-phase protocol. From November 2007 to November 2009, 74 patients underwent CT angiography 2-7 days after endovascular repair during single-energy unenhanced and dual-energy venous phases. By using dual-energy software, the iodine overlay was superimposed on venous phase images with different percentages ranging between 0 (virtual unenhanced images) and 50-75% to show the iodine in an orange color. Two blinded readers evaluated the data for diagnosis of endoleaks during standard unenhanced and venous phase images (session 1, standard of reference) and virtual unenhanced and venous phase images with colored iodine overlay images (session 2). We compared the effective dose radiation of a single-energy biphasic protocol with that of a single-phase dual-energy protocol. The diagnostic accuracy of session 2 was calculated. The mean dual-energy effective dose was 7.27 mSv. By using a dual-energy single-phase protocol, we obtained a mean dose reduction of 28% with respect to a single-energy biphasic protocol. The diagnostic accuracy of session 2 was: 100% sensitivity, 100% specificity, 100% negative predictive value, and 100% positive predictive value. Statistically significant differences in the level of confidence for endoleak detection between the two sessions were found by reviewers for scores 3-5. Dual-energy CT with colored iodine overlay is a useful diagnostic tool in endoleak detection. The use of a dual-energy single-phase study protocol will lower radiation exposure to patients.

Functional analysis by 64-slice CT scanning: prediction of left ventricular dysfunction together with reduction in radiation exposure?

Functional analysis by 64-slice CT scanning: prediction of left ventricular dysfunction together with reduction in radiation exposure?

Detection and Significance of Incidental Unruptured Cerebral Aneurysms in Patients Undergoing Intravenous Thrombolysis for Acute Ischemic Stroke

It is still controversial whether intravenous (IV) thrombolysis for acute ischemic stroke increases the risk of aneurysmal bleeding. We sought to find the risk for aneurysmal bleeding after IV thrombolysis in ischemic stroke patients with unruptured cerebral aneurysms. We retrospectively analyzed consecutive patients with acute ischemic stroke who had received IVT between August 2006 and November 2009. Immediately after IV-tissue plasminogen activator (tPA) therapy (.9 mg/kg), patients underwent CT angiography, MR angiography. After that, all patients underwent follow-up angiography within 36 hours of the initiation of IV thrombolysis. Aneurysm-related hemorrhage was defined as a hemorrhage that was related to the aneurysm site. A total of 201 patients were analyzed, and 8 (4.1%) had unruptured cerebral aneurysms. Of the 8 patients, 4 had aneurysms over 5 mm of the longest diameter. Three patients had intracerebral hemorrhage that developed at the site of infarction, which was unrelated to the aneurysms. The results of this study suggest that IV thrombolysis might not increase the risk of aneurysmal bleeding in acute stroke patients with unruptured aneurysm < 10 mm in diameter. Further studies with a larger sample size are needed to confirm our result.

320-row CT scanning: reduction in tube current parallels reduction in radiation exposure?

320-row CT scanning: reduction in tube current parallels reduction in radiation exposure?

Dual-energy computed tomographic angiography of head and neck arteries with different contrast material doses in second generation dual-source computed tomography system

To explore the feasibility of a dual-energy computed tomographic angiography (DECTA) protocol using test-bolus injection with reduction of contrast material (CM) dose in second generation dual-source CT system. Totally 57 consecutive patients underwent CT angiography scan covering the cervical and cerebral arteries. CT was performed with second generation dual-source CT system. The time to peak (T) using a test-bolus injection was calculated. The patients were divided into three groups (A, B, and C) with different CM doses (40, 45, and 50 ml) and different delay time points [ (T+1) , (T+1) , and (T+2) s] . All the patients were followed by a 48 ml saline flush. Arterial enhancements were quantified by measuring attenuation values of the aortic arch, bifurcation of common carotid artery, contralateral internal jugular vein of the CM injection, superior vein cava, proximal middle cerebral artery, basilar artery, and straight sinus on source images. Visualizations of intracranial artery and ipsilateral venous effect of the CM injection were rated on a four-point grading scale on CTA images for qualitative assessment. Although the attenuation of internal jugular vein and straight sinus were significantly lower in group A than in groups B and C (P<0.05) , the attenuation of aortic arch, superior vein cava, common carotid artery, middle cerebral artery, and basilar artery vessels showed no significant differences among these three groups. The scores of the visualizations of intracranial artery and ipsilateral venous effect of the CM injection were also not significantly different among these three groups. Based on the delay time calculated by a test-bolus injection, a reduced-dose contrast material may provide an equal degree of arterial attenuation and a lower attenuation of vein for dual-energy CTA covering the craniocervical region in second generation dual-source CT system.

ORIGINAL ARTICLE: Retrospective audit of the investigation of patients with suspected acute subarachnoid haemorrhage

AbstractIntroduction: Recommended investigational care (RIC) of emergency department (ED) patients with suspected subarachnoid haemorrhage comprises lumbar puncture (LP) to detect xanthochromia if the preceding CT scan is negative.Methods: Retrospective audit of the investigational care of 100 consecutive ED patients presenting with possible subarachnoid haemorrhage.Results: Of the 100 patients, 91 had negative CT, and 36 (39.6%) of these patients had an LP performed to detect xanthochromia (i.e. RIC). Fifty‐five of 91 (60.4%) patients did not receive RIC.Of the 55 patients who did not receive RIC, 25 (45.5%) had a documented senior clinical decision not to perform an LP; 15 (27.3%) had no documented reason; five (9.1%) refused consent; two (3.6%) had an LP but no xanthochromia requested, one patient did not have an LP because of technical issues, six patients underwent CT angiography (CTA), and one patient underwent magnetic resonance angiography (MRA), in the absence of a LP, following a negative CT. Two patients underwent CTA following a negative xanthochromia result. Patients admitted to the emergency extended care unit had 6.85 times the odds of receiving RIC (95% CI 2.20–21.4).Conclusions: Fifty‐five (55) of 91 (60%) ED patients did not receive RIC. Fifteen of the 55 did not have any documented justification for not performing an LP with xanthochromia testing. Admission to an emergency extended care unit was a predictor of receiving RIC. Inappropriate use of CTA and MRA was identified. These findings have important implications for patient safety. Multifaceted strategies are required to close this evidence–practice gap.

Incidence of Highly Important Extravascular Findings Detected on CT Angiography of the Abdominal Aorta and the Lower Extremities

The purpose of this study was to determine the frequency and significance of extravascular findings on CT angiography of the abdominal aorta and lower extremities. Reports of CT angiograms of the abdominal aorta and lower extremities for 275 patients (164 men and 111 women; mean age, 72 years) were retrospectively reviewed. Patients were scanned from the level of diaphragm to toes. Extravascular findings were classified into three groups-low, moderate, and high importance-on the basis of clinical significance. Low-importance findings were defined as those with little, if any, clinical significance. Moderate-importance findings were those that may not be clinically apparent but recognition of which could be beneficial at a later time. Highly important findings were defined as previously unknown results requiring further imaging or investigation. For highly important findings, electronic chart review determined the subsequent clinical course. Highly important extravascular findings were found in 40 (15%) patients. Of 462 findings overall, 43 (9%) were of high importance, 77 (17%) were of moderate importance, and 342 (74%) were of low importance. The most common highly important findings were indeterminate lesions of kidney (n = 9), lung (n = 7), and liver (n = 6). Overall, eight (3%) of the 275 patients had findings of high clinical significance that resulted in medical therapy or surgical intervention, including lung carcinoma, renal cell carcinoma, colon carcinoma, cholangiocarcinoma, and pulmonary coccidioidomycosis. Of patients undergoing CT angiography of the abdominal aorta and lower extremities, 15% had previously undiagnosed, highly important findings. Radiologists and referring clinicians should be aware of the frequency of these clinically significant extravascular findings at CT angiography.

Evaluation of Virtual CT Sonography for Enhanced Detection of Small Hepatic Nodules: A Prospective Pilot Study

Virtual CT sonography is a system for synchronizing multiplanar reconstructed CT scans with corresponding conventional ultrasound images in real time. The aim of this study was to prospectively evaluate the feasibility of virtual CT sonography for detection of nodules difficult to detect with conventional sonography alone. Fifty-nine patients with 140 nodules were included in the study. All patients underwent CT angiography then conventional sonography and finally virtual CT sonography. The number, location, and echogenicity of nodules and parenchyma were assessed. Among 140 nodules detected with CT angiography, 71 were detected with conventional sonography and another 46 were detected with virtual CT sonography, increasing the overall sensitivity from 50.7% to 83.57%. The average diameter of nodules detected only with virtual CT sonography (9.7 +/- 3.3 mm) was significantly smaller than that of nodules detected with conventional sonography (16.6 +/- 6.2 mm). The results of multivariate analysis suggested that nodule size (p < 0.001), echo pattern (p = 0.004), and location (p = 0.028) are associated with the difference in detection. Interestingly, 87% of the nodules 10 mm in diameter or smaller were already dysplastic or malignant. Nodules 10 mm in diameter or smaller have significant malignant potential and therefore are clinically important. Even though we do not consider virtual CT sonography a screening tool, we conclude it superior to conventional sonography for detection of small hepatic nodules, allowing bedside percutaneous ultrasound-guided biopsy and treatment that would not be possible with conventional sonography alone.

Intraoperative computed tomography angiography with computed tomography perfusion imaging in vascular neurosurgery: feasibility of a new concept

In vascular neurosurgery, there is a demand for intraoperative imaging of blood vessels as well as for rapid information about critical impairment of brain perfusion. This study was conducted to analyze the feasibility of intraoperative CT angiography and brain perfusion mapping using an up-to-date multislice CT scanner in a prospective pilot series. Ten patients with unruptured aneurysms underwent intraoperative scanning with a 40-slice sliding-gantry CT scanner. Multimodal CT acquisition was obtained in 8 patients consisting of dynamic perfusion CT (PCT) scanning followed by intracranial CT angiography. Two of these patients underwent CT angiography and PCT 2 times in 1 session as a control after repositioning cerebral aneurysm clips. In another 2 patients, CT angiography was performed alone. The quality of all imaging obtained was assessed in a blinded consensus reading performed by an experienced neurosurgeon and an experienced neuroradiologist. A 6-point scoring system ranging from excellent to insufficient was used for quality evaluation of PCT and CT angiography. In 9 of 10 PCT data sets, the quality was rated excellent or good. In the remaining case, the quality was rated insufficient for diagnostic evaluation due to major streak artifacts induced by the titanium pins of the head clamp. In this particular case, the quality of the related CT angiography was rated good and sufficient for intraoperative decision making. The quality of all 12 CT angiography data sets was rated excellent or good. In 1 patient with an anterior communicating artery aneurysm, PCT scanning led to a repositioning of the clip because of an ischemic pattern of the perfusion parameter maps due to clip stenosis of an artery. The subsequent PCT scan obtained in this patient revealed an improved perfusion of the related vascular territory, and follow-up MR imaging showed only minor ischemia of the anterior cerebral artery territory. Intraoperative CT angiography and PCT scanning were shown to be feasible with short acquisition time, little interference with the surgical workflow, and very good diagnostic imaging quality. Thus, these modalities might be very helpful in vascular neurosurgery. Having demonstrated their feasibility, the impact of these methods on patients' outcomes has now to be analyzed prospectively in a larger series.

FP06-MO-02 Economy class stroke in Hong Kong

interest artery include intracranial segment of internal carotid, intracranial segment of vertebral artery, basilar artery, middle cerebral artery. The technical success rate, average stenosis before and after treatment, major complications and clinical outcome were recorded. Conventional angiography was performed at 6 months after stenting to evaluate the patency of stent. Results: The average pretreatment stenosis was 80.6±12.1%. After Wingspan stent deployment, the average stenosis was 14.3±10.2%. The technical success rate was 100%. The rate of ipsilater stroke within 30 days and 6 months was 6.3% and 12.5%, respectively. The symptoms were significantly improved in 68.8% patients. Five patients underwent CT angiography, and in-stent stenosis was detected in one patient with 80% restenosis. Conclusion: Symptomatic intracranial artery stenosis can be treated with Wingspan stent with a high rate of technical success, acceptable safety and favorable clinic outcome.

Pulmonary imaging using dual-energy CT, a role of the assessment of iodine and air distribution

Aim The aim of the study is to present the feasibility of using dual-energy CT and the evaluation of iodine and air distribution in differentiation of pathological conditions. Material and method We used the data of 50 CT examinations performed due to suspected pulmonary embolism with any pathological finding except consolidation of the parenchyma. The patients underwent CT angiography of the pulmonary arteries on a dual-source CT (DSCT), with the two tubes independently operated at 140 and 80 kV. By exploiting the dual-energy information, iodine distribution maps were obtained in addition to the conventional CT images which served as a marker of pulmonary perfusion. Minimum intensity projections (MinIP) were used as a marker of air content. Results By comparing the iodine distribution maps and MinIP images, it was possible to differentiate between the following templates of lung parenchyma: A – normal iodine and air distribution; B – iodine content deficit with minimal or with no redistribution of air; C – reduced iodine content and increased content of air; D – deficit of iodine content and increased content of air; E – increased iodine content and normal content of air; F – increased iodine content and reduced content of air; G – reduced perfusion and reduced content of air. The type A (five cases) was typical for the pulmonary embolism with preserved normal conditions of perfusion and ventilation. Type B (18 cases) occurred in pulmonary embolism; type C was found in case of inflammation of small respiratory airways (five cases); emphysema was typical for type D (nine cases); increased perfusion was observed in the parenchyma preserved from emphysema or preserved from embolism in cases of emphysema or pulmonary embolism; type F occurred in pulmonary interstitial edema (four cases) both with pulmonary infection; finally type G was found in interstitial lung diseases (five cases). Conclusion Imaging of the pulmonary circulation by means of dual-energy CT opens the potential to study pathological changes of circulatory and pulmonary perfusion impairments, our presented work signs the important relations between iodine and air distribution which have to be thought in the interpretation of dual-energy perfusion imaging of the lungs.

Dual-Energy CT for the Assessment of Contrast Material Distribution in the Pulmonary Parenchyma

The purpose of this study was to assess the feasibility and diagnostic value of dual-energy CT iodine mapping at pulmonary CT angiography. Ninety-three patients underwent CT angiography with the dual-energy technique on a dual-source CT scanner. Postprocessing was used to map iodine in the lung parenchyma on the basis of its spectral behavior, and image quality was assessed by two readers. Iodine distribution patterns were rated as homogeneous, patchy, or circumscribed defects. Conventional CT angiographic images reconstructed from the same data sets were reviewed for the presence and localization of pulmonary embolism, whether embolic occlusion was partial or complete, and the presence of changes in the lung parenchyma. Dual-energy perfusion findings were correlated with the CT angiographic and lung-window CT findings in per-patient and per-segment analyses. Iodine distribution was homogeneous in 49 patients, of whom CT angiography showed no pulmonary embolism in 46 patients and nonocclusive pulmonary emboli in three patients. Images of 29 patients showed a patchy pattern; 24 of these patients had no pulmonary embolism, and five had nonocclusive pulmonary emboli with solely nonocclusive intravascular clots. Images of 15 patients showed segmental or subsegmental defects; four of these patients had evidence of pulmonary embolism, and 11 had occlusive pulmonary emboli with at least one occlusive clot in the pulmonary vasculature. Dual-energy CT is reliable in the detection of defects in pulmonary parenchymal iodine distribution that correspond to embolic vessel occlusion.

Low-dose CT angiography: sufficient contrast for vessel imaging?

At present, noninvasive CT angiography has been shown to be as accurate as conventional angiography, and it had been presaged that CT angiography will soon be able to replace conventional coronary angiography [1–21]. The ACCURACY trial showed in 230 patients a 99% negative predictive value for CT angiography, establishing this method as an effective noninvasive alternative to conventional angiography to rule out obstructive coronary artery disease [22]. Despite the tremendous achievements by CT angiography, most investigators have called for restricted use of this imaging method until adequate clinical evidence becomes available showing the cost-effectiveness and safety of this approach. In particular, there are inherent questions about safety of cardiac CT scans in terms of radiation exposure [23, 24]. The median exposure of CT angiography is roughly equivalent to 600 chest X-rays (12 mSv). Traditional angiography exposes patients to roughly half the dose of CT angiography. However, the radiation exposure of almost 2,000 people having 64-slice cardiac CT images at 50 medical centers in different countries may vary more than six-fold [25]. Effective strategies to reduce radiation dose are available but these strategies are not frequently used. The following strategies and new scanning techniques have been proposed for dose reduction in cardiac CT and include the following [26]: (1) coronary CT angiography should not be performed in patients with extensive coronary calcifications because the probability to rule out obstructive coronary artery disease diminishes with increasing coronary artery calcium scores; (2) the scan length in CT angiography should be individually adjusted to the minimum needed length; (3) electrocardiogram-correlated modulation of the tube current should be applied in all patients with stable sinus rhythm; (4) the tube voltage should be reduced to 100 kV in non-obese patients (patient weight 90% of patients. Heart rate control proved to be an important component of 320-detector row prospectively gated CT dose reduction. In the present study in the International Journal of Cardiovascular Imaging, Herzog et al. [30] evaluated 70 patients using prospectively ECG-triggered CT coronary angiography to establish the determinants of vessel contrast. All patients underwent low-dose CT angiography using body mass index (BMI)-adapted tube parameters and a fixed contrast material bolus. Mean radiation dose was 2.13 ± 0.69 mSv. Tube voltage had been adapted to patients’ body mass index in order to minimize the interference of body mass index with image noise and, thus, contrast to noise ratio. With this strategy it was aimed at assessing the impact of cardiac output as an index of contrast bolus dilution on coronary artery attenuation and contrast to noise ratio. It was shown that a BMI adapted protocol widely reduced the impact of BMI on image noise, while vessel contrast remained subject to large variations, depending on bolus dilution by blood volume and cardiac output. The use of a BMI-adapted scanning protocol allowed the reduction of BMI interference on image noise as evidenced by similar noise values over a large range of BMI. Finally, the study identified body surface area as the most promising parameter to be of potential value for adjusting the contrast bolus in future protocols. As such, the present study by Herzog et al. [30] supports the notion that reduction of radiation exposure through low-dose CT angiography with prospective gating allows for proper vessel contrast using contrast dosages based on body surface area. These findings are in line with the recent findings of the same group guided by Kaufmann et al. [31, 32]), who showed that prospective ECG-triggering for CT angiography reduces radiation dose by almost 90% without affecting diagnostic performance. Consequently, striving for effective strategies to reduce radiation exposure—as well as implementing these strategies—are of paramount importance when evaluating patients undergoing CT angiography.

W1002 Usefulness of Real Time Virtual Sonography for Detection of Small Hepatic Nodules: A Prospective Study

Purpose:Ultrasonography(US) has excellent spatial resolution, uses neither X-rays nor magnetic fields, is a portable machine that can be conveniently used at the bedside, and displays lesions in real time. The latter feature is convenient for curative percutaneous procedures such as radiofrequency ablation and percutaneous ethanol injection. However, US is not sensitive for the detection of small nodules in patients with advanced liver disease, and the ability to detect nodules varies depending on the experience and technical skill of the examiner. Real time virtual sonography(RVS) is the first system capable of demonstrating virtual multiplanar reconstructed images corresponding to ultrasonographic images in real time. The purpose of this study was to prospectively evaluate the diagnostic efficacy of RVS for detection of liver malignancy often overlooked by conventional US. Materials and Methods:Sixty-six patients with a presumptive diagnosis of hepatocellular carcinoma were assessed between January 2005 and December 2006 at Shimane University Hospital. All of the patients underwent CT angiography, either during arterial portography or hepatic arteriography. Patients with diffuse invasive hepatoma, 6 or more nodules, and nodules for which US-guided percutaneous therapy (>3 cm lesions) was not indicated were excluded. A final total of 59 patients with 140 nodules were included. After CT angiography, conventional US and RVS were performed. The number of nodules detected by these two methods as well as their characteristics (nodule diameter, location and echo pattern of the nodule, and the echo pattern of the liver parenchyma) were compared to determine which method was more sensitive and which characteristics had a stronger influence on sensitivity. Results:From a total of 140 nodules detected by CT angiography, 71 (50.7%) were detected by both conventional US and RVS, and 46 (32.9%) were detected by RVS but not by conventional US. Twenty-three nodules (16.4%) were not detected by either conventional US or RVS. Univariate analysis demonstrated that nodule size, location, and echo pattern of the nodule and the liver parenchyma, influenced the difference in detection ability between the two methods. Multivariate analysis suggested that the most important factor affecting the difference in detection ability was nodule size. Conclusion:The RVS system is useful for detection of non-hyperechoic nodules with 10 mm or smaller diameter located in the periphery of the liver.

Value of multi-slice computed tomography in diagnosis of coronary plaque characterization

To investigate the value of multi-slice computed tomography in diagnosis of different types of coronary atherosclerotic plaques. Twenty-eight patients undergoing CT angiography (CTA) with normal coronary arteries were randomly selected to measure the CT values of different sections of the 4 main branches of coronary artery. Twenty-five specimens of human heart from the bodies of the patients who died of non-cardiogenic diseases were scanned by 16-slice CT scanner and 64-slice CT scanner: a mixture of CT contrast media and normal saline was injected into the coronary arteries to achieve in-vivo-like contrast enhancement within the coronary artery lumen to detect atherosclerotic plaques. The CT values of plaques were measured in several regions of interest (ROI) selected in each plaque. The CT images thus obtained were evaluated by 2 experienced radiologists. There are nine specimens with coronary atherosclerotic plaques among them. Then the atherosclerotic lesions in the coronary were made into tissue specimens to undergo pathological examination. 7560 CT values were obtained from the 28 patients. Thirty-eight atherosclerotic plaques were found by CAT in 9 heart specimens and confirmed by pathology. When the CT value of coronary lumen was 370 HU, the predominant lipid-rich plaque showed a mean CT value of 53 +/- 12 HU; the fibrous-rich plaque showed a mean CT value of 106 +/- 17 HU; and the calcified plaque showed a mean CT value of 429 +/- 94 HU measured by 16-slice CT; and the predominant lipid-rich plaque showed a mean CT value of 51 +/- 13 HU; the fibrous-rich plaque showed a mean CT value of 110 +/- 19 HU; and the calcified plaque showed a mean CT value of 435 +/- 87 HU measured by 64-slice CT. The CT value of the fibrous-rich plaque was significantly higher than that of the lipid-rich plaque (P = 0.008), and lower than that of the calcified plaque (P < 0.01). There was no significant difference between the results obtained by the two kinds of CT scanners. CTA can non-invasively assess the atherosclerotic plaques.

Multidetector CT Angiography in Pulmonary Sequestration

To evaluate the role of multidetector CT angiography in the diagnosis and preoperative assessment of pulmonary sequestration with angiographic or surgical correlation. Eight patients (5 males, 3 females) in the age range of 2 days to 35 years suspected of having pulmonary sequestration on the basis of clinical history and chest radiographs were included in the study. All patients underwent CT angiography (4 or 16 slice) and MPVR, MIP and 3D volume rendered images were generated. The axial images were also reviewed at soft tissue and lung window settings to evaluate the parenchymal changes. CT angiography showed five pulmonary sequestrations on the left and three on the right, located in the basal segments (n = 7) or paravertebral region (n = 1). Aberrant systemic arterial supply was demonstrated in all cases: from the descending thoracic aorta (n = 2); abdominal aorta (n = 3) and celiac axis (n = 3). Venous drainage into inferior pulmonary veins was demonstrated in 4 patients. The angioarchitecture depicted on CT angiography was confirmed on surgery in five patients and by DSA in two patients who subsequently underwent embolization using PVA particles and/or coils. The ability of CT angiography to simultaneously image the arterial supply, venous drainage and parenchymal changes in a single examination makes it the imaging modality of choice for the diagnosis and preoperative assessment of pulmonary sequestration.

Extravascular incidental findings at multislice CT angiography of the abdominal aorta and lower extremity arteries: a retrospective review study

To assess the frequency and clinical impact of extravascular incidental findings on routine CT angiography of abdominal aorta or lower extremity arteries. From January 2002 to July 2004, a total of 692 patients underwent CT angiography of abdominal aorta and lower extremity arteries. Two radiologists retrospectively reviewed by consensus cross-sectional images for the presence and clinical impact definition of extravascular findings. The revision of hospital charts, medical records, and all procedures' reports performed before and after CT angiography represented the standard of reference (SOR). Only 373 out of 605 patients in whom extravascular findings were found had a SOR; in these patients CT angiography obtained a true-positive incidental rate of 98.9% (369/373). For the clinical impact definition of CT-angiography incidental findings, a concordance with SOR was obtained in 56.3% of patients, whereas a subsequent investigation was required in 183 patients (183/369, 49.6%). Among clinically relevant incidental findings, a total of 35 malignancies (35/894, 3.9%) were detected in 20 patients (20/423, 4.7%); in 15 patients (15/423, 3.5%) malignancy was unknown before CT-angiography exam. A careful observation of cross-sectional images, even if "time consuming", is mandatory not only to assess vascular findings but also to avoid a misdiagnosis of clinical relevant extravascular findings.