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BackgroundCoronary computed tomography angiography (CTA)-verified positive remodeling and low attenuation plaques are considered morphological characteristics of high-risk plaque (HRP) and predict short-term risk of acute coronary syndrome (ACS).ObjectivesThis study evaluated whether plaque characteristics by CTA predict mid-term likelihood of ACS.MethodsThe presence of HRP and significant stenosis (SS) of ≥70% were evaluated in 3,158 patients undergoing CTA. Serial CTA was performed in 449 patients, and plaque progression (PP) was evaluated. Outcomes (fatal and nonfatal ACS) were recorded during follow-up (mean 3.9 ± 2.4 years).ResultsACS occurred in 88 (2.8%) patients: 48 (16.3%) of 294 HRP(+) and 40 (1.4%) of 2,864 HRP(−) patients. ACS was also significantly more frequent in SS(+) (36 of 659; 5.5%) than SS(−) patients (52 of 2,499; 2.1%). HRP(+)/SS(+) (19%) and HRP(+)/SS(−) (15%) had higher rates of ACS compared with no-plaque patients (0.6%). Although ACS incidence was relatively low in HRP(−) patients, the cumulative number of patients with ACS developing from HRP(−) lesions (n = 43) was similar to ACS patients with HRP(+) lesions (n = 45). In patients with serial CTA, PP also was an independent predictor of ACS, with HRP (27%; p < 0.0001) and without HRP (10%) compared with HRP(−)/PP(−) patients (0.3%).ConclusionsCTA-verified HRP was an independent predictor of ACS. However, the cumulative number of ACS patients with HRP(−) was similar to patients with HRP(+). Additionally, plaque progression detected by serial CTA was an independent predictor of ACS.

Linear skull fracture, following head trauma, may reach major blood vessels, such as the middle meningeal artery or sinus venosus, and may cause epidural hematoma. However, hematoma is likely to be missed in the initial interpretation because it spreads only gradually. In addition, the fracture lines that run along the scan slice plane are often missed during initial interpretation. In this study, we develop a novel method for automated detection of the linear skull fracture using head computed tomography (CT) images and conduct a basic evaluation using digital phantom and head phantom that enclose genuine human bones. In the proposed method, the bone region is first extracted using morphological processing of the head CT images. Then, the cranial vault is determined from the CT scout view image. The skull has low-density cancellous bone between the hard two-layer high-density compact bones. Because the fracture lines of compact bones are more clearly recognized as compared to cancellous bones, the bone surface is then extracted by performing three-dimensional (3D) Laplacian filtering. Finally, linear structures are extracted by applying the black-hat transform to the bone surface image. In the experiments, we evaluated the proposed method using digital phantom and CT images of the head phantom. From the experiments using digital phantom, we were able to detect a crack line with a width of 0.35 mm. In the experiments using head phantom, we were able to clearly detect the crack lines in the phantom. These results indicate that our proposed method will be useful for the automated detection of skull fracture in CT images.

The purpose of this study was to design and construct a phantom for using motion artifact in the electrocardiogram (ECG)-gated reconstruction image. In addition, the temporal resolution under various conditions was estimated. A stepping motor was used to move the phantom over an arc in a reciprocating manner. The program for controlling the stepping motor permitted the stationary period and the heart rate to be adjusted as desired. Images of the phantom were obtained using a 320-row area-detector computed tomography (ADCT) system under various conditions using the ECG-gated reconstruction method. For estimation, the reconstruction phase was continuously changed and the motion artifacts were quantitatively assessed. The temporal resolution was calculated from the number of motion-free images. Changes in the temporal resolution according to heart rate, rotation time, the number of reconstruction segments and acquisition position in z-axis were also investigated. The measured temporal resolution of ECG-gated half reconstruction is 180 ms, which is in good agreement with the nominal temporal resolution of 175 ms. The measured temporal resolution of ECG-gated segmental reconstruction is in good agreement with the nominal temporal resolution in most cases. The estimated temporal resolution improved to approach the nominal temporal resolution as the number of reconstruction segments was increased. Temporal resolution in changing acquisition position is equal. This study shows that we could design a new phantom for estimating temporal resolution.

Aims Pathological and clinical optical coherence tomography (OCT) studies have indicated that acute coronary syndrome (ACS) lesions have either ruptured fibrous caps (RFC-ACS) or intact fibrous caps (IFC-ACS). Although computed tomographic (CT) angiographic characteristics of RFC-ACS include low-attenuation plaques and positive plaque remodelling, features associated with IFC-ACS have not been previously described. The aim of this study was to assess the CT characteristics of IFC-ACS lesions. Methods and results Seventy-four patients with ACS/stable angina consented to multimodality imaging, of which 66 underwent CT angiography. Of these, 57 culprit lesions in 57 patients were evaluated with sufficient image quality from all four of OCT, angioscopy, intravascular ultrasound, and CT angiography. Intraluminal thrombus was assessed by OCT/angioscopy, and culprit lesions further classified by OCT-based demonstration of fibrous cap integrity. Of 35 culprit lesions with ACS, OCT revealed IFC with thrombus in 10 (29%) and RFC in the remaining 25 (71%); all 22 lesions with stable angina had intact fibrous caps. Fibrous caps were significantly thinner in RFC-ACS than IFC-ACS and stable angina (45 +/- 12, 131 +/- 57, and 321 +/- 146 mu m, respectively; P = 0.001). CT angiography revealed that low-attenuation plaques were more frequently observed in RFC-ACS than IFC-ACS and stable angina (88, 40, and 18%; P = 0.001) lesions. Similarly, positive remodelling was more predominantly seen in RFC-ACS than IFC-ACS and stable angina (96, 20, and 14%; P = 0.001). However, none of the specific CT angiography features clearly distinguished IFC-ACS from stable lesions. Conclusion In contrast to the situation with RFC-ACS, distinct culprit lesion characteristics associated with non-rupture-related mechanisms are not identified by CT angiography. It will therefore not be possible to differentiate plaques likely to develop IFC-ACS from stable plaques.

Objectives This study sought to assess, by serial computed tomography angiography (CTA), the effect of statin treatment on coronary plaque morphology. Background In addition to the assessment of luminal stenosis, CTA also allows characterization of plaque morphology. Large, positively remodeled plaques with large necrotic cores have been reported as indicators of plaque instability. Methods CTA was performed in 32 patients (26 men, ages 64.3 ± 8.5 years). Of these, 24 received fluvastatin after the baseline study; 8 subjects who refused statin treatment were followed as the control subjects. Serial imaging was performed after a median interval of 12 months. All vessels were examined in every subject, and a 10-mm-long segment was identified for comparison before and after intervention. Total plaque volume, low attenuation plaque (LAP) volume, lumen volume, and remodeling index were calculated. Results In the statin-treated patients, the total plaque volume (92.3 ± 37.7 vs. 76.4 ± 26.5 mm3, p Conclusions This preliminary study suggests that serial CTA evaluation of coronary plaques allows for the assessment of interval change in the plaque morphology. Statin treatment results in decreases in the plaque and necrotic core volume. The features known to be associated with plaque instability.

Objectives In a computed tomographic (CT) angiography study, we identified the characteristics of atherosclerotic lesions that were associated with subsequent development of acute coronary syndrome (ACS). Background The CT characteristics of culprit lesions in ACS include positive vessel remodeling (PR) and low-attenuation plaques (LAP). These 2 features have been observed in the lesions that have already resulted in ACS, but their prospective relation to ACS has not been previously described. Methods In 1,059 patients who underwent CT angiography, atherosclerotic lesions were analyzed for the presence of 2 features: PR and LAP. The remodeling index, and plaque and LAP areas and volumes were calculated. The plaque characteristics of lesions resulting in ACS during the follow-up of 27 10 months were evaluated. Results Of the 45 patients showing plaques with both PR and LAP (2-feature positive plaques), ACS developed in 10 (22.2%), compared with 1 (3.7%) of the 27 patients with plaques displaying either feature (1-feature positive plaques). In only 4 (0.5%) of the 820 patients with neither PR nor LAP (2-feature negative plaques) did ACS develop. None of the 167 patients with normal angiograms had acute coronary events (p 0.001). ACS was independently predicted by PR and/or LAP (hazard ratio: 22.8, 95% confidence interval: 6.9 to 75.2, p 0.001). Among 2- or 1-feature positive segments, those resulting in ACS demonstrated significantly larger remodeling index (126.7 3.9% vs. 113.4 1.6%, p 0.003), plaque volume (134.9 14.1 mm 3 vs. 57.8 5.7 mm 3 ,p 0.001), LAP volume (20.4 3.4 mm 3 vs. 1.1 1.4 mm 3 ,p 0.001), and percent LAP/total plaque area (21.4 3.7 mm 2 vs. 7.7 1.5 mm 2 ,p 0.001) compared with segments not resulting in ACS. Conclusions The patients demonstrating positively remodeled coronary segments with low-attenuation plaques on CT angiography were at a higher risk of ACS developing over time when compared with patients having lesions without these characteristics. (J Am Coll Cardiol 2009;54:49‐57) © 2009 by the American College of Cardiology Foundation

Rationale and Objectives The latest multislice computed tomography (MSCT) scanners permit the chest and abdomen to be scanned continuously. However, conventionally, it has been necessary to perform scanning twice using different pitch factors for the cardiac and abdominal regions. We have developed a new scanning technique known as variable pitch factor scanning, in which the table speed is changed during scanning to obtain continuous images from the heart to the abdomen in a single scan, and have evaluated its physical characteristics. Materials and Methods A bead phantom, a comb phantom, and a gold wire placed at an angle were scanned using a 64-row MSCT scanner. The variation in the spatial resolution and continuity of images in the body axis direction because of changes in the pitch factor were evaluated. Results Because reconstruction taking the cone angle into consideration was employed, the spatial resolution in the body axis direction was unchanged and the continuity of images in the body axis direction was maintained at a certain level even when the pitch factor was changed. Conclusion Variable pitch factor scanning is a useful technique for obtaining continuous images from the heart to the abdomen in a single scan.

The optimal cardiac phases for coronary CT angiography (CTA) are end-systole and mid-diastole, in which cardiac movement is slow. In conventional methods, these cardiac phases are determined by visual selection. We have compared the images in the optimal cardiac phases that were selected by the conventional method and cardiac-phase search software (Phase Navi), and examined the clinical usefulness of Phase Navi in patients with atrial fibrillation. The subjects were 38 patients (regular rhythm: 20, atrial fibrillation: 18). The continuity scores of patients with regular rhythm (Phase Navi, conventional methods) were 2.4+/-0.3-2.5+/-0.3 in end-systole and 2.4+/-0.5-2.4+/-0.4 in mid-diastole. The scores of patients with atrial fibrillation (Phase Navi, conventional methods) were 2.3+/-0.4-2.3+/-0.4 in end-systole, and 2.2+/-0.5-2.1+/-0.6 in mid-diastole. Because the continuity scores of the optimal images from Phase Navi were similar to those from the conventional method, Phase Navi had clinical usefulness in patients with atrial fibrillation.

Background It has been proposed that 0.5-mm-slice multislice computed tomography (MSCT) is a noninvasive tool for the detection of atherosclerotic plaque, but the validity of such an assessinent has not been demonstrated by an invasive investigation. The present study was performed to compare the 0.5-mm-slice NISCT density of plaques with intravascular ultrasound (IVUS) findings. Methods and Results Atherosclerotic plaques were characterized in 37 consecutive patients undergoing percutaneous interventions. Based on the IVUS echogenecity, the plaques were classified as soft (n= 18), fibrous (n= 40) or calcified (n=40). In these 98 plaques, 0.5-mm-slice MSCT plaque density was calculated in 443 regions-of-interest, including 331 lesional foci and 112 luminal cross-sections, and represented as Hounsfield units (HU). MSCT density of the 3 types of plaque was 11 +/- 12 HU, 78 +/- 21 HU, and 516 +/- 198 HU respectively. Computed tomography density of the (contrast-filled) lumen was 258 +/- 43HU. There were statistically highly significant differences in the densitometric characteristics among the 4 groups (soft, fibrous, calcified plaque and lumen) by nonparametric Kruskal-Wallis test (p < 0.0001). Conclusions The IVUS-based coronary plaque configuration can be accurately identified by 0.5-mm slice MSCT. Noninvasive assessment of plaque characterization will ensure emphasis on the vessel wall beyond the vascular lumen.

Linitis plastica (scirrhous gastric carcinoma) has a poor prognosis due to delay in diagnosis. Pathological feature of this tumor is diffuse fibrosis of the gastric wall. Detection of small fibrotic lesion in the gastric wall would contribute to early diagnosis of linitis plastica, since the primary lesion usually lacks remarkable protrusion or ulceration. We performed a multislice CT evaluation of 20 patients with gastric carcinoma with 8 data acquisition system (Aquilion, Toshiba Medical Systems Corporation, Japan). Out of 20 primary lesions, 3 were diagnosed as relatively small size (less than 10 cm in maximum diameter) linitis plastica. We have successfully demonstrated an en face virtual endoscopic image of the primary ulcers of linitis plastica by arterial-phase, and reactive fibrosis (a desmoplastic response) of the gastric wall by delayed-phase multiplanar reformation (MPR) images perpendicular to the en face image. This preoperative information was useful to evaluate extent of tumor invasion. The multislice CT evaluation of linitis plastica using delayed-phase images was potentially useful in the detection of relatively small fibrotic lesion and in determining the optimal mode of resection of the stomach.

The complexity of right ventricular (RV) shape makes it more difficult for measuring its volume. However, the short-axis view of the right ventricle usually is crescent and might be assumed as half of a circle. This hypothesis can be applied to calculate RV volume by using the single-plane Simpson's method, but the final RV volume should be about half of the original calculated value. The aim of this study was to test the accuracy of RV volume measurement based on this new assumption in human RV casts.Fifteen human RV casts were scanned with multislice helical CT and RV sagittal image that corresponds to right anterior oblique view were reconstructed. Single-plane Simpson's method was used to calculate RV volumes. The calculated RV volume was defined as the original calculated value divided by 2. The true RV cast volume was determined by water displacement.The true RV volume was 64.23+/-24.51 ml; the calculated volume was 53.18+/-26.22 ml. The calculated RV correlated closely with true volume with a regression equation of RV actual volume=21.04 0.406 x RV calculated volume (r=0.869, P0.001), but significantly underestimated the actual volume by 11.05+/-13.09 ml (P0.006).Right ventricular volume could be calculated with single-plane Simpson's method based on the new proposed half-circle model.

Coronary artery visualization by multi-slice CT and the evaluation of coronary stenosis were examined. Multi-slice CT could not be used for evaluation after the coronary artery stent custody method. We examined various coronary artery stent custody phantoms and stent visualization of clinical examples by using multi-slice CT with a slice thickness of 0.5 mm. ECG-gated scanning was done by inputting ECG using 4DAS (Data Acquisition System) multi-slice CT with a slice thickness of 0.5 mm. We carried out image reconstruction, measured the CT number, and examined the inside stent. The CT number of the inside stent rose in accordance with stent diameter. The inside stent was visualized clearly at 0.5 mm in comparison with 1.0 mm in slice thickness. Visualization of the lumen was influenced in the Stent Custody Phantom by the quality of the stent material, Strut form, and the size of the diameter. The inside stent could be evaluated with the S670 4 mmphi stent. Form evaluation of the inside stent was possible, although the cavity in the stent was influenced by the difference in distance between peaks.

The additive value of plaque characteristics determined by computed tomography angiography (CTA) in patients undergoing invasive coronary angiography (ICA) has not been established. METHODS AND RESULTS: We studied 676 patients undergoing ICA and CTA within 3 months. The luminal diameter narrowing based on ICA and the presence of high risk plaque (HRP) based on CTA were assessed in all coronary artery segments except for those after or before scheduled treatment. We followed their cardiac events including cardiac death, acute coronary syndrome (ACS), and revascularization for de novo lesions ≥3 months after ICA. The incidence of coronary events was higher in the segments including25% luminal narrowing than in those without (2.94% vs. 0.31%, P0.0001), and higher in the segments containing HRP than in those without (12.6 vs. 0.46%, P0.0001). Greater than 25% residual luminal narrowing and the presence of HRP were identified as independent predictors of cardiac events after risk adjustment for age, gender, and history of ACS (hazard ratio [HR], 3.22; 95% confidence interval [CI]: 1.29-10.76; P=0.0092, HR, 2.64; 95% CI: 1.59-4.35; P=0.0002, respectively). Adding the presence of HRP to a model including age, gender, ACS history, and25% residual stenosis improved the prediction of cardiac events.Assessment of coronary plaque characteristics on CTA improves the prediction of cardiac events in patients undergoing ICA.

To study whether thrombolytic therapy affects Gd-DTPA-enhanced pattern and whether its pattern indicates myocardial viability, Gd-DTPA-enhanced magnetic resonance imaging (MRI) was performed in 43 patients with reperfused acute myocardial infarction 14.8+/-5.0 days after onset with breathhold scanning on a 1.5-T whole body system. The hypoenhanced area at 90 sec after contrast injection was defined as a perfusion defect (PD). Patients were divided into PD(+) and PD(-) groups. The PD was detected in 77.8% of patients treated with direct percutaneous transluminal coronary angioplasty (PTCA) and in 28.6% of patients treated by thrombolytic therapy with or without PTCA in the thrombolysis in myocardial infarction grade 3 group (p0.05). The myocardial wall was divided into seven segments based on the American Heart Association committee report. Wall motion of each segment was classified by one of six patterns (wall motion score [WMS]: dyskinesis, -1; akinesis, 0; severe hypokinesis, 1; hypokinesis, 2; slight hypokinesis, 3; normal, 4). By echocardiography, the average WMS and ejection fraction were similar between the PD(+) group and the PD(-) group on admission. Those parameters were significantly worse in the PD(+) group than in PD(-) group 1 month after onset. The change in WMS was significantly lower in the PD(+) group than in the PD(-) group. The number of patients and segments with more than two grades of improvement of WMS in the PD(+) group was significantly lower than that in the PD(-) group. Angiographically, left ventricular ejection fraction and WMS of the PD(+) group were significantly lower than those of the PD(-) group 3 months later. PDs were detected significantly less frequently in patients treated with thrombolytic therapy, suggesting that microvascular embolization related to formation of the no-reflow phenomenon.

Multislice helical computed tomography (CT) substantially reduces scanning time. However, the temporal resolution of individual images is still insufficient for imaging rapidly moving organs such as the heart and adjacent pulmonary vessels. It may, in some cases, be worse than with current single-slice helical CT. The purpose of this study is to describe a novel image reconstruction algorithm to improve temporal resolution in multislice helical CT, and to evaluate its performance against existing algorithms. The proposed image reconstruction algorithm uses helical interpolation followed by data weighting based on the acquisition time. The temporal resolution, the longitudinal (z-axis) spatial resolution, the image noise, and the in-plane image artifacts created by a moving phantom were compared with those from the basic multislice helical reconstruction (helical filter interpolation, HFI) algorithm and the basic single-slice helical reconstruction algorithm (180 degrees linear interpolation, 180LI) using computer simulations. Computer simulation results were verified with CT examinations of the heart and lung vasculature using a 0.5 second multislice scanner. The temporal resolution of HFI algorithm varies from 0.28 and 0.86 s, depending on helical pitch. The proposed method improves the resolution to a constant value of 0.29 s, independent of pitch, allowing moving objects to be imaged with reduced blurring or motion artifacts. The spatial (z) resolution was slightly worse than with the HFI algorithm; the image noise was worse than with the HFI algorithm but was comparable to axial (step-and-shoot) CT. The proposed method provided sharp images of the moving objects, portraying the anatomy accurately. The proposed algorithm for multislice helical CT allowed us to obtain CT images with high temporal resolution. It may improve the image quality of clinical cardiac, lung, and vascular CT imaging.

Real-time CT fluoroscopy (CTF), which permits real-time monitoring of CT images at a rate of 8 images per second with a 0.5 s delay time, has recently entered clinical use. The purpose of this paper is to evaluate the usefulness of CTF as a tool for guiding intracranial interventions. Twenty-six interventional procedures were undertaken in 16 patients under CTF guidance. These included puncture of intracranial hematoma (n=8), hematoma drainage (n=9), cerebrospinal fluid (CSF) drainage (n=3), biopsy of intracranial tumors (n=4), and marking of intracerebral tumors (n?2). Needle puncture and placement were clearly monitored by CTF in all the cases. Hematoma puncture and drainage, CSF drainage, and tumor marking were performed successfully under CTF guidance. Biopsy failed in one patient with suspected brain tumor. Intra- and extra-tumor bleeding was observed in two patients who underwent tumor biopsy and was detected by CTF immediately after the occurrence. Our preliminary study indicates that real-time CTF is a potentially valuable tool for guiding neurosurgical interventions.

We previously reported that serial coronary computed tomography angiography (CTA) had a potential to evaluate the interval change of plaque morphology of coronary arteries. The aim of this study was to evaluate variables associated with the plaque progression by serial CTA. We included 148 patients (age 66.3 ± 9.8 years, male 81.1 %, median scan interval 12 months) with coronary artery disease undergoing serial CTA. Each coronary artery was compared visually between baseline and follow-up CTA to detect plaque progression. Baseline characteristics between progression and nonprogression patients did not demonstrate any significant differences. Logistic analysis revealed that only low-density lipoprotein cholesterol (LDL-C) ≥100 mg/dl at follow-up was associated with plaque progression (odds ratio 2.59, 95 % confidence interval 1.12–6.34, P = 0.0263). Cutoff value of LDL-C for plaque progression at follow-up was 103.0 mg/dl based on receiver-operator characteristic curves analyses. Of the 36 progressive lesions in 32 patients, plaque composition at baseline included 13 lesions (36.1 %) of noncalcified plaque, 1 lesion (2.8 %) of calcified plaque, 12 lesions (33.3 %) of partially calcified plaque, and the remaining 10 lesions (27.8 %) had no plaque at baseline and revealed de novo plaques at follow-up. There were 9 lesions (25 %) with high-risk plaque (HRP) characteristics at baseline and 18 lesions (50 %) with HRP at follow-up. Plaque progression of coronary arteries by serial CTA was associated with LDL-C ≥100 mg/dl at follow-up regardless of baseline LDL-C level. There was no specific finding to predict plaque progression on the baseline plaque characteristics.

Using helical computed tomography (CT), we evaluated cystic pancreatic lesions in 11 patients and compared the imaging and the histopathologic findings. Helical CT allowed us to assess the tumor vasculature. Contrastenhanced images showed satisfactory details of the cysts, cyst walls, and intracystic structures. Helical CT is extremely useful for the evaluation of cystic pancreatic lesions.

A recently developed real-time computed tomography (CT) fluoroscopy system, which provides effective real-time reconstruction and display of CT images, was used to monitor nonvascular interventional procedures performed in 57 patients. Biopsy of thoracic lesions (n = 38), biopsy or drainage of pelvic lesions (n = 6), drainage or aspiration of intracranial hematomas (n = 9), and other procedures (n = 4) were performed. CT fluoroscopy successfully depicted the entire procedure in all patients. In thoracic lesions, a mean 1.3 passes was necessary to gain access to the lesion. Sufficient cytologic samples were obtained in 32 of 33 pulmonary lesions with a mean diameter of 26 mm.

Background: The role of combined evaluation of myocardial perfusion imaging (MPI; by single-photon emission computed tomography) and computed tomography angiography (CTA) for risk stratification of coronary artery disease was evaluated. For CTA, the extent of luminal stenosis, and also the features of high-risk plaques (HRP, including positive remodeling and low attenuation) were evaluated. Methods and Results: A total of 304 patients (65±11 years, male 72%, median follow-up: 24 months) who underwent CTA and MPI were enrolled in the study. Summed stress scores and summed difference scores (SDS) for MPI, stenosis, and HRP were evaluated, and event rates were compared. Cardiac events were defined as acute coronary event including cardiac death or non-fatal acute myocardial infarction, and unstable angina requiring revascularization. Of 304 patients, 51 (16.8%) underwent early revascularization. In the remaining 253 patients, an event occurred in 11 (4.3%). HRP (hazard ratio [HR], 4.75, P=0.00171) and stenosis (+) with SDS >0 (HR, 4.58, P=0.0461) were significant independent predictors of cardiac event. The event rate for stenosis (+) with SDS >0 was significantly higher than others (log-rank P=0.0490). The event rates were significantly different between HRP(+) and HRP(–) (16.1% vs. 2.7%, log-rank P=0.0013). Conclusions: HRP on CTA was an independent predictor of acute coronary events, as was stenosis (+) with SDS >0, and HRP had increased prognostic value over stenosis and abnormal MPI findings. (Circ J 2013; 77: 411–417)

Background: The differences in the coronary plaque characteristics between patients with mild chronic kidney disease (CKD) (estimated glomerular filtration rate [eGFR] 30-59ml⋅min-1⋅1.73m-2) and those without CKD (eGFR ≥60) by 320-row area detector computed tomography (CT) have not been studied. Methods and Results: We enrolled 487 patients undergoing coronary CT angiography with suspected stable coronary artery disease (mean age: 66.6±10.8 years, 131 with mild CKD) and analyzed 6,352 segments. All coronary plaques were characterized for the presence of vessel remodeling, plaque consistency and the disposition of coronary calcification, and a plaque with positive vessel remodeling and/or low-attenuation was defined as high risk. The number of diseased segments per patient was higher in mild CKD patients than in those without CKD (4.61±3.83 vs. 2.95±3.11, P

This paper discusses the test for the automatic extraction of lung cancer candidate areas from the high-resolution continuous chest CT image taken with the slice interval of 1 mm, by a three-dimensional image processing technique. The detection of local suspicious regions (SR) is considered. A procedure is developed which discriminates the lung area from other images (mostly vessels) based on the differences of three-dimensional shapes. The actual procedure in the processing is composed largely of two steps: (1) segmentation of lung area; and (2) SR extraction. In this study, the processing is realized by a relatively simple procedure, combining such basic processes as thresholding, fusion of three-dimensional figures (or three-dimensional distance transformation) and the three-dimensional skeletonization. The usefulness of the method is demonstrated using an actual case of lung cancer. The study is significant as the first test that demonstrated the usefulness of the three-dimensional image processing, using the three-dimensional CT image of a practically sufficient accuracy.

The aim of this study was to evaluate 320-row area detector CT (ADCT) for patients with atrial fibrillation (Af) based on simulated exposure using electrocardiogram RR intervals and comparison with the findings of coronary CT angiography (CCTA) using 64-row multi slice CT (MSCT). The probability of including RR intervals of 900 ms or more was calculated when the acquisition time was varied from 1 to 4 beats. Overall, 51 patients with Af who underwent CCTA were examined. The exposure time for CCTA, the total dose length product (DLP) for the examination, and the image quality (scored 0 to 3: poor to excellent) were compared between ADCT and MSCT. The probability of including RR intervals of 900 ms or more was highly significantly increased at 3 beats of acquisition time. The exposure time using ADCT was reduced by 75% compared with MSCT (ADCT/MSCT: 2.8/11.3 s), and the total DLP was reduced by 40% (ADCT/MSCT: 1398/2277 mGy·cm). Moreover, ADCT provided diagnosable images in all cases, and the mean image quality score for ADCT was significantly higher than that for MSCT (ADCT/MSCT: 2.8/2.4). Thus, 320-row ADCT at 3 beats of acquisition time can provide CCTA images of acceptable quality for patients with Af.

This study sought to assess, by serial computed tomography angiography (CTA), the effect of statin treatment on coronary plaque morphology.In addition to the assessment of luminal stenosis, CTA also allows characterization of plaque morphology. Large, positively remodeled plaques with large necrotic cores have been reported as indicators of plaque instability.CTA was performed in 32 patients (26 men, ages 64.3 +/- 8.5 years). Of these, 24 received fluvastatin after the baseline study; 8 subjects who refused statin treatment were followed as the control subjects. Serial imaging was performed after a median interval of 12 months. All vessels were examined in every subject, and a 10-mm-long segment was identified for comparison before and after intervention. Total plaque volume, low attenuation plaque (LAP) volume, lumen volume, and remodeling index were calculated.In the statin-treated patients, the total plaque volume (92.3 +/- 37.7 vs. 76.4 +/- 26.5 mm(3), p0.01) and LAP volume (4.9 +/- 7.8 vs. 1.3 +/- 2.3 mm(3), p = 0.01) were significantly reduced over time; however, there was no change in the lumen volume (63.9 +/- 25.3 vs. 65.2 +/- 26.2 mm(3), p = 0.59). On the other hand, no change was observed in the CTA characteristics in the control subjects, including total plaque volume (94.4 +/- 21.2 vs. 98.4 +/- 28.6 mm(3), p = 0.48), LAP volume (2.1 +/- 3.0 vs. 2.3 +/- 3.6 mm(3), p = 0.91), and lumen volume (80.5 +/- 20.7 vs. 75.0 +/- 16.3 mm(3), p = 0.26). The plaque volume change (-15.9 +/- 22.2 vs. 4.0 +/- 14.0 mm(3), p = 0.01) and LAP volume change (-3.7 +/- 7.0 vs. 0.2 +/- 1.5 mm(3), p0.01) were significantly greater in the statin than the control group. The lumen volume (1.3 +/- 15.6 vs. -5.5 +/- 13.1 mm(3), p = 0.24) and remodeling index (-2.4 +/- 6.8% vs. -0.3 +/- 6.5%, p = 0.53) did not show the significant differences between the 2 groups. The decrease in the plaque volume was due to reduction in the LAP volume (R = 0.83, p0.01), and was not related to any changes in the lumen volume (R = 0.21, p = 0.24).This preliminary study suggests that serial CTA evaluation of coronary plaques allows for the assessment of interval change in the plaque morphology. Statin treatment results in decreases in the plaque and necrotic core volume. The features known to be associated with plaque instability.

Background Sixty-four-slice multidetector computed tomography (64-MDCT) has been shown to be a feasible modality for diagnosing coronary artery disease. We studied the accuracy of 64-MDCT in the detection of diseased grafts and also evaluated its limitations. Methods This study comprised 19 patients who underwent coronary artery bypass grafting and both invasive coronary angiography (ICA) and 64-MDCT. The 64-MDCT images were analyzed for bypass graft occlusion and significant stenosis (>50%) of the anastomosis, and the results were compared with those of ICA. Results A total of 90 anastomoses, including 25 proximal anastomoses, were evaluated. Of 65 distal anastomoses, including 5 previously occluded grafts in redo cases, 12 distal anastomoses were identified by 64-MDCT as occluded. In comparison, only 10 grafts were identified as occluded by ICA. The sensitivity, specificity, positive predictive value, and negative predictive value for patency were 100% (10 of 10), 96.5% (55 of 57), 83.3% (10 of 12), and 100% (55 of 55), respectively. The ICA patent grafts were evaluated with respect to stenosis. Invasive coronary angiography identified significant stenosis at only 1 site, whereas 64-MDCT showed significant stenosis at 6 sites. The sensitivity, specificity, positive predictive value, and negative predictive value for stenoses were 100% (1 of 1), 93.1% (67 of 72), 16.7% (1 of 6), and 100% (67 of 67), respectively. Conclusions Although 64-MDCT demonstrated diagnostic accuracy in evaluating bypass grafts, limitations of this method include false positive results in cases of competitive flow between the graft and the native coronary artery.

To preliminarily evaluate the feasibility and potential diagnostic utility of whole-brain perfusion computed tomography (CT) performed with a prototype 256-detector row CT system over an extended range covering the entire brain to assess ischemic cerebrovascular disease.Institutional review board approval and informed consent were obtained. Eleven cases in 10 subjects (six men, four women; mean age, 64.3 years) with intra- or extracranial stenosis were retrospectively evaluated with whole-brain perfusion CT. Three readers independently evaluated perfusion CT data. The diagnostic performance of perfusion CT was visually evaluated with a three-point scale used to assess three factors. Differences between four axial perfusion CT images obtained at the basal ganglia level (hereafter, four-section images) and whole-brain perfusion CT images were assessed with the paired t test. In four subjects, the interval between perfusion CT and single photon emission computed tomography (SPECT) was 1-17 days (mean, 10.3 days). Correlation between perfusion CT findings and SPECT findings was assessed with the Spearman correlation coefficient.Three-dimensional perfusion CT images and axial, coronal, and sagittal whole-brain perfusion CT images were displayed, and the extent of ischemia was assessed. Mean visual evaluation scores were significantly higher for whole-brain images than for four-section images (4.27 +/- 0.76 [standard deviation] vs 2.55 +/- 0.87). The cerebral blood flow ratios of the ischemic lesions relative to normal regions scanned with perfusion CT (x) and SPECT (y) showed a significant positive correlation (R(2) = 0.76, y = 0.44 x + 0.37, P.001).Perfusion CT performed with a 256-detector row CT system can be used to assess the entire brain with administration of one contrast medium bolus. Thus, ischemic regions can be identified with one examination, which has the potential to improve diagnostic utility.

With high-speed multislice helical CT, the time needed to select the optimal cardiac phase accounts for a large percentage of the coronary CT angiography examination time because the scan time is short. To reduce the phase selection time, we have developed an automatic cardiac phase selection algorithm and implemented it in the Aquilion 64 scanner. This algorithm calculates the absolute sum of the differences between two raw data sets for subsequent cardiac phases (e.g., 4% and 0%) and generates a velocity curve representing the magnitude of cardiac motion velocity for the entire heart volume. Normally, the velocity curve has two local minimum slow-motion phases corresponding to end-systole and mid-diastole. By applying these local minimum phases in reconstruction, stationary cardiac images can be reconstructed automatically. In this report, the algorithm for generating the velocity curve and the processing time for selecting the optimal cardiac phase are discussed. The accuracy of this method is compared with that of the conventional manual method. In the manual method, a sample plane containing all four cardiac chambers was selected, reconstruction was performed for all phases at 2% intervals, and images were visually evaluated. Optimal phase selection required about 5 min/exam. With automatic phase selection, optimal phase selection required only about 1 min/exam, and the cardiac phases were close to those selected using the manual method. Automatic phase selection substantially reduces the time needed to select the optimal phase and increases patient throughput. Moreover, the influence of operator skill in selecting the optimal phase is minimized.

It has been proposed that 0.5-mm-slice multislice computed tomography (MSCT) is a noninvasive tool for the detection of atherosclerotic plaque, but the validity of such an assessment has not been demonstrated by an invasive investigation. The present study was performed to compare the 0.5-mm-slice MSCT density of plaques with intravascular ultrasound (IVUS) findings.Atherosclerotic plaques were characterized in 37 consecutive patients undergoing percutaneous interventions. Based on the IVUS echogenecity, the plaques were classified as soft (n=18), fibrous (n=40) or calcified (n=40). In these 98 plaques, 0.5-mm-slice MSCT plaque density was calculated in 443 regions-of-interest, including 331 lesional foci and 112 luminal cross-sections, and represented as Hounsfield units (HU). MSCT density of the 3 types of plaque was 11+/-12 HU, 78+/-21 HU, and 516 +/-198 HU respectively. Computed tomography density of the (contrast-filled) lumen was 258+/-43 HU. There were statistically highly significant differences in the densitometric characteristics among the 4 groups (soft, fibrous, calcified plaque and lumen) by nonparametric Kruskal-Wallis test (p0.0001).The IVUS-based coronary plaque configuration can be accurately identified by 0.5-mm slice MSCT. Noninvasive assessment of plaque characterization will ensure emphasis on the vessel wall beyond the vascular lumen.

Along with the increase of detector rows on the z-axis and a faster gantry rotation speed, the spatial and temporal resolutions of the multislice computed tomography (CT) have been improved for noninvasive coronary artery imaging. We investigated the feasibility of the second specification prototype 256-detector row four-dimensional CT for assessing coronary artery and cardiac function.The subjects were five patients with coronary artery disease. Contrast medium (40-60 ml) was intravenously administered at the rate of 3-4 ml/s. The patient's whole heart was scanned for 1.5 s to cover at least one cardiac cycle during breathholding without electrocardiographic gating. Parameters used were 0.5 mm slice thickness, 0.5 s/rotation, 120 Kv, and 350 mA, with a half-scan reconstruction algorithm (temporal resolution 250 ms). Twenty-six transaxial datasets were reconstructed at intervals of 50 ms.The assessability of the coronary arteries in AHA segments 1, 2, 3, 5, 6, 7, 9, and 11 was visually evaluated, resulting in 29 of 32 (90.9%) segments being assessable. Functional assessment was also performed using animated movies without banding artifacts in all cases.The 256-detector row four-dimensional CT can assess the coronary artery and cardiac function using data during 1.5 s without banding artifacts.

ObjectivesTo evaluate the feasibility of noninvasive assessment of the characteristics of disrupted atherosclerotic plaques, the authors interrogated the culprit lesions in acute coronary syndromes (ACS) by multislice computed tomography (CT).BackgroundDisrupted atherosclerotic plaques responsible for ACS histopathologically demonstrate large lipid cores and positive vascular remodeling. It is expected that plaques vulnerable to rupture should bear similar imaging signatures by CT.MethodsEither 0.5-mm × 16-slice or 64-slice CT was performed in 38 patients with ACS and compared with 33 patients with stable angina pectoris (SAP) before percutaneous coronary intervention. The coronary plaques in ACS and SAP were evaluated for the CT plaque characteristics, including vessel remodeling, consistency of noncalcified plaque (NCP

Summary: Electrocardiographically (ECG) gated multisection helical CT images were obtained in 23 patients with ruptured intracranial aneurysms. 4D-CTA (3D CT angiography plus phase data) images were generated by ECG-gated reconstruction. Four patients showed pulsation of an aneurysmal bleb. Clipping was performed in two of these patients, and the rupture site matched the pulsatile bleb seen in 4D-CTA.

One of the newest CT application technologies is cardiac synchronized image reconstruction. In this technology, evaluation of time-resolution is very important. We developed a method of measuring time-resolution in cardiac synchronized reconstruction, and evaluated various scanning protocols. In our experiment, ECG-gated scanning was done by multi-slice CT (Aquilion16 Super Heart Edition, Toshiba Medical Systems Co., Ltd., Japan). The nominal slice thickness was 0.5 mm, and rotation time was 0.5 sec. Input heart rate was set at 40, 45, 50, 55, 60, 70, 75, 80, and 90 bpm, and helical pitch at 3.2, 4.0, and 4.8 (beam-pitch: 0.200, 0.250 and 0.300). We measured FWTM of the obtained sensitivity distribution and compared at each scanning protocol. Time resolution improved as helical pitch decreased and heart rate increased. However, phase-time resolution deteriorated as heart rate increased. The results of our experiment indicated that a segment center was determined by X-ray tube rotation time and heart rate, and the number of segments was determined by heart rate, helical pitch, and reconstruction position. Time resolution changed with X-ray tube rotation time, heart rate, helical pitch, and reconstruction position. In this report, we provide a reference for an optimal scanning protocol in cardiac synchronized image reconstruction.

Multislice helical computed tomography (MSCT) has been used to depict coronary anatomy noninvasively, and proved useful for evaluating ventricular function. The aim of our study was to assess the accuracy of ventricular volume as measured by MSCT.Fourteen human left ventricular (LV) and 15 right ventricular (RV) casts were scanned by MSCT. A series of LV and RV short-axis images were reconstructed later with slice thickness of 2.0 mm, 3.5 mm, 5.0 mm, 7.0 mm, and 10.0 mm. Ventricular volume was calculated by the multislice tomographic Simpson's method. True LV and RV cast volumes were determined by water displacement.Both calculated LV and RV volumes correlated highly with the corresponding true volumes (all r0.95, P0.01). But with slice thickness from 2.0 mm to 10.0 mm, MSCT scanning overestimated the corresponding true volume by (3.21 +/- 5.95) ml to (12.58 +/- 8.56) ml for LV and (10.22 +/- 8.45) ml to (23.91 +/- 12.24) ml for RV (all P0.01). There was a very high correlation between the overestimation and the selected slice thickness for both LV and RV volume measurements (r=0.998 and 0.996, P0.01, respectively). However, when slice thickness was reduced to 5.0 mm, the overestimation for both LV and RV volume measurements became nonsignificant for slice thickness from 2.0 mm to 5.0 mm.Both LV and RV volumes can be accurately estimated by MSCT. Thinner slice has more accurate calculated volume. However, 5.0 mm slice thickness is thin enough for an accurate measurement of LV or RV volume.