Abstract: PURPOSE: The purpose of our study was to acquire dose profiles at critical organs of lung and breast regions using optically stimulated luminescence (OSL) dosimeters; assess the actual radiation dose delivered at retrospective and prospective computed tomography coronary angiography (CTCA). MATERIALS AND METHODS: Using a chest CT phantom we applied a prospectively-gated step-and-shoot- and a retrospectively-gated helical mode on a 64-detector row CT scanner. Retrospective scan mode was used with and without electrocardiogram (ECG) based tube current modulation. OSL dosimeters were used to measure dose profiles. In the both scan modes we acquired dose profiles and determined the mean and maximum dose in left lung and in left breast regions. RESULTS: In prospective mode, the mean dose was 21.53Â mGy in left lung- and 23.59Â mGy in left breast region. With respect to the retrospective mode, the mean dose with tube current modulation was 38.63Â mGy for left lung- and 46.02Â mGy for left breast region, i.e. 0.56 and 0.55 times lower than the mean dose without modulation. CONCLUSION: The OSL dosimeter is useful for measurement of the actual radiation dose along z-axis at lung and breast regions in the prospective and the retrospective CTCA.
Abstract: To investigate the volume-doubling time (VDT) of histologically proved pulmonary nodules showing ground glass opacity (GGO) at multidetector CT (MDCT) using computer-aided three-dimensional volumetry.
Abstract: The purpose of this study was to evaluate the morphology and composition of atherosclerotic coronary plaques in patients with stable coronary artery disease by 64-row multidetector computed tomography (CT) angiography. A total of 56 patients were divided into an ischemia-related (n = 31) and a nonischemia-related lesion group (n = 25) based on myocardial perfusion scintigraphy, invasive angiography, and 1-year clinical follow-up. The 56 lesions detected by CT imaging were analyzed; the severity of stenosis, the lesion length, CT attenuation value, and calcium deposition of the plaques were evaluated. Clinical characteristics and CT findings were compared using univariate and multivariate logistic regression analyses. Ischemia-related lesions exhibited a greater severity of coronary stenosis, were longer (17.8 ± 8.5 vs 9.1 ± 3.9 mm), and had a higher CT attenuation value (101.7 ± 36.7 vs 81.6 ± 32.6 HU) and larger calcium deposition. By univariate logistic analysis, severity of stenosis, lesion length, CT attenuation value, and calcium deposition were significantly associated with ischemia-related plaques. The odds ratio (OR) of these parameters was 6.874 (P = 0.007), 1.371 (P = 0.001), 1.018 (P = 0.044), and 5.400 (P = 0.004), respectively. By multivariate logistic analysis, the severity of stenosis and lesion length were significantly associated with ischemia-related plaques (OR 7.588, P = 0.036 and OR 1.365, P = 0.003, respectively). In conclusion, coronary CT angiography is useful for the identification of morphological differences between ischemia-related and nonischemia-related plaques in patients with stable coronary artery disease.
Abstract: We evaluated low-contrast injection protocols for coronary computed tomography angiography (CTA) using a 64-detector scanner and the test bolus technique.
Abstract: To investigate the effect of low-tube-voltage technique on a cardiac computed tomography (CT) for coronary arterial and cardiac functional analyses and radiation dose in slim patients.
Abstract: Although pre-existing renal insufficiency (RI) is the most important risk factor for contrast-induced nephropathy (CIN), the background distribution of baseline renal function has not been investigated thoroughly in patients scheduled for contrast-enhanced CT.
Abstract: Aim: Increased coronary plaque burden, which could be involved in the pathogenesis of atherothrombotic events, is difficult to evaluate in the three major coronary arteries. The purpose of this study was to quantify coronary plaque volume using 64-slice computed tomography (CT).Methods: We measured coronary plaque volume with our new protocol in 23 consecutive patients (48% men; 66 ± 11 years old) who underwent cardiac CT for suspicion of coronary artery disease and had noncalcified plaques. We counted the total pixel volume of noncalcified plaques in the three major coronary arteries.Results: The coronary plaque volume was 1.29 ± 0.56 cm(3) in the right coronary artery, 1.29 ± 0.42cm(3) in the left main coronary artery and left anterior descending artery, and 0.88 ± 0.32 cm(3) in the left circumflex artery. The total coronary plaque burden (TCPB) was 3.45 ± 1.02 cm(3)/patient and had a positive correlation with waist circumference (r =0.44, p < 0.05) and insulin resistance (r = 0.46, p < 0.05). TCPB was significantly greater in men (3.89 ± 1.07 cm(3) vs. 3.06 ± 0.82 cm(3) in women, p < 0.05), patients with diabetes or impaired glucose tolerance (3.77 ± 0.94 cm(3) vs. 2.86 ± 0.92 cm(3) in non-diabetics, p < 0.05), and patients with metabolic syndrome (3.91 ± 0.95 cm(3) vs. 3.03 ± 0.91 cm(3) in patients without metabolic syndrome, p < 0.05).Conclusions: Cardiac CT can provide a noninvasive assessment of TCPB, which was significantly associated with metabolic syndrome and its components. Measuring TCPB by CT could be an important strategy for identifying high-risk patients with suspected coronary artery disease.
Abstract: Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms.
Abstract: We compare the performance of low tube voltage with the hybrid iterative reconstruction (iDose) with standard and low tube voltage with the filtered backprojection (FBP) using phantoms at computed tomographic coronary angiography. In computed tomographic coronary angiography, application of the combined low tube voltage with iDose resulted in significant image quality improvements compared to the low tube voltage with FBP. Image quality was the same or better despite a reduction in the radiation dose by 76% compared with standard tube voltage with FBP.
Abstract: The purpose of this study was to compare the diagnostic capability of hepatic dynamic CT with low-dose contrast material (420 mg I/kg body weight) at 80 kVp with that of the same modality performed with standard-dose contrast material at 120 kVp.
Abstract: The aim of this study was to investigate the detectability of simulated pulmonary nodules with different X-ray attenuation by flat-panel detector (FPD) chest radiography using a dual-exposure dual-energy subtraction (DES) technique.
Abstract: The objective of our study was to investigate the effect on aortic enhancement of contrast material volumes adjusted for a patient's body surface area (BSA) at CT angiography (CTA).
Abstract: We investigated the effect of low-tube-voltage CT angiography with a reduced volume of contrast agent on qualitative and quantitative parameters and the radiation dose in patients with peripheral arterial disease.
Abstract: To investigate the effect of a double-exposure dual-energy subtraction (DES) technique on the diagnostic performance of radiologists detecting small pulmonary nodules on flat-panel detector (FPD) chest radiographs.
Abstract: We sought to assess the association between inflammation in pericardial fat (PF) and coronary artery disease (CAD) by pathological examination and clinical evaluation with cardiac computed tomography (CT).
Abstract: To evaluate the efficacy of variable contrast injection durations and scanning delay determined by test injection analysis of computed tomography angiography (CTA) of peripheral arteries.
Abstract: Primary cardiac lymphoma is a rare, extremely aggressive malignancy. Early diagnosis and treatment is important for patient survival. We present a case of a 76-year-old woman admitted for worsening dyspnea caused by a large tumor in the right atrium. Magnetic resonance imaging and computed tomography clearly depicted the primary cardiac tumor, and histopathological study of the surgical specimen confirmed the diagnosis of diffuse large B-cell lymphoma.
Abstract: Our aim was to prospectively investigate the contrast agent concentration and the infusion rate to obtain optimal images of the Adamkiewicz artery by 64-row MDCT. Eighty patients were divided into four groups based on the following protocol: A, 100 mL of 300 mg I/mL at 5.0 mL/s; B, 100 mL of 350 mg I/mL at 5.0 mL/s; C, 100 mL of 300 mg I/mL at 3.5 mL/s; D, 100 mL of 350 mg I/mL at 3.5 mL/s. Quantitative evaluation was performed by calculating mean aortic attenuation value from T5 to L3 level. Visual evaluation of the Adamkiewicz artery was also performed. In a quantitative evaluation, the rapid injection (A, 473.4 +/- 82.6 HU; B, 506.7 +/- 71.9 HU) was significantly superior to the slow injection (C, 371.3 +/- 65.1 HU; D, 391.5 +/- 60.8 HU). In a visual evaluation, the Adamkiewicz artery was assessable in 15 of 20 (75%), 16 of 20 (80%), 9 of 20 (45%), and 10 of 20 (50%) patients in groups A, B, C, and D, respectively. The injection protocol of 1.75 g iodine/s provides both the adequate aortic attenuation of more than 450 HU to assess the Adamkiewicz artery and the best visualization of the Adamkiewicz artery in 64-row MDCT.
Abstract: The association between a gadolinium-based contrast material and nephrogenic systemic fibrosis has been discussed. The purpose of our study was to evaluate whether non-contrast enhanced magnetic resonance angiography (MRA) might provide sufficient information of renal artery stenosis.
Abstract: A single coronary artery is a rare and potentially serious anomaly. We present the case of a 54-year-old woman with chest pain predominantly at rest. A single coronary artery was demonstrated by 64-row multidetector computed tomography (CT) imaging, which is useful for the diagnosis and classification of coronary anomaly. In our case, no coronary artery stenosis was demonstrated on CT angiographic images, and totally occlusive coronary spasm was confirmed by intracoronary infusion of acetylcholine.
Abstract: Malignant fibrous histiocytoma of the thoracic aorta associated with ulcer-like projection has not been reported previously. The hypovascular tumor of the thoracic aorta involved the mural layer, which showed intra- and extra-mural growth patterns and no significant filling defect within the aortic lumen, and mimicked ulcer-like projection with secondary pseudoaneurysm formation. Aortic tumor, although rare, should be included among the causes of an ulcer-like projection.
Abstract: The aim of this experimental study was to investigate visualization of various coronary artery stents with sub-millimeter multi-slice spiral computed tomography (MSCT) using a cardiac physical phantom. Four 3-mm stents of various designs were implanted in tubes with an inner diameter of 3 mm to simulate coronary artery. Stents were placed on a cardiac phantom and scanned at different heart rates. Retrospective ECG-gated adaptive segmental reconstruction technique was employed. Profile curves across longitudinal curved planar reconstruction images of the stents were generated. From the profile curve, the full width at half maximum was defined as the stent lumen index. The effect of heart rate and stent type on the stent lumen index was evaluated. Visual evaluation for each stent at various heart rates was also performed. The heart rate had no significant effect on in-stent visualization. However, in-stent visualization differed significantly for the various stent types for both profile curve analysis and visual evaluation (the Tukey-Kramer multiple comparisons test). Multiple regression analysis indicated that strut thickness, especially minimal strut thickness, was the significant influencing factor for the in-stent visualization. On the basis of four stent models examined it would appear that visualization of the coronary stent lumen varies depending on the stent type, but not on the heart rate. Stents with slim struts are preferable for in-stent evaluation with multi-slice spiral computed tomography.
Abstract: We present a case of a 19-year-old male patient complaining of right leg pain, which appeared after exercise and abated with rest. Computed tomography (CT) and magnetic resonance angiography (MRA) showed occlusion of right popliteal artery. Volume rendering CT image showed not only occlusion of right popliteal artery but also abnormal course of the medial head of the gastrocnemius muscle (MHG). CT and MR images of right popliteal fossa showed the abnormal anatomy that MHG coursed between popliteal artery with thrombus and popliteal vein. Popliteal artery entrapment syndrome was diagnosed non-invasively by multidetector CT and MRI. Sectional radiological and three-dimensional images are useful for not only depiction of the arterial changes but also identification of the abnormal anatomic structures responsible for the entrapment.
Abstract: Coronary computed tomography (CT) angiography (CTA) and myocardial perfusion single photon emission CT (SPECT, or MPS) provide complementary information on vascular structure and myocardial perfusion. In patients with coronary artery disease (CAD), the combination of both methods is helpful for disease detection and therapeutic strategy planning. This article addresses the utility of coronary CTA with current 64-row multidetector CT instruments, MPS, and the combination of these methods in the evaluation of CAD.
Abstract: The objective of our study was to evaluate whether a low-dose contrast material (CM) protocol with a saline flush might provide sufficient contrast enhancement in aortoiliac 16-MDCT angiography.
Abstract: To evaluate retrospectively if there is additional diagnostic value of fused single photon emission computed tomographic (SPECT) and computed tomographic (CT) images in assessing possible bone metastases.
Abstract: The aim of this study was to compare results of left ventricular (LV) function obtained by quantitative gated single-photon emission tomography (QGS) and multidetector-row spiral computed tomography (MDCT) with reference parameters using an electrocardiogram-gated cardiac physical phantom. The phantom study was performed using a combined SPECT/CT system. Flexible membranes formed the inner and outer walls of the simulated LV. The stroke volume was adjusted (45 mL or 58 mL) and the fixed 42-mL end-systolic volume (ESV) produced two different volume combinations. The LV function parameters were estimated by means of MDCT and QGS. Differences in true and measured volumes were compared among CT with a reconstructed image thickness of 2.5 mm and 5.0 mm and QGS volumetric values. Each scan was repeated three-times. The estimation of LV volumes using both QGS and MDCT analyses were reproducible very well. QGS overestimated ejection fraction (EF) by approximately 20%; MDCT volumetry overestimated EF by approximately 5% in each volume setting. The differences in true and measured values for EF and ESV obtained with QGS were significantly greater than obtained with MDCT. Conclusion: MDCT provides a reliable estimation of functional LV parameters, whereas QGS tends to significantly overestimate the EF in small hearts.
Abstract: To determine whether quantitative diffusion-weighted imaging (DWI) is useful for characterizing poorly contrast-enhanced and T2-prolonged bone masses.
Abstract: The purpose of this study was to determine the optimal contrast injection protocol for clear delineation of the endocardial and epicardial contours and coronary vessels in anatomic and functional imaging with cardiac 16-MDCT.
Abstract: The purpose of our study was to assess quantitative indexes and the effect of attenuation correction on the evaluation of lymph node metastasis in the staging of non-small cell lung cancer (NSCLC) using fused thallium-201 SPECT/CT images.
Abstract: Aneurysms of the sinus of Valsalva are rare. We report here the case of a 56-year-old man with a ruptured aneurysm of sinus of Valsalva with flow into the right ventricle which was diagnosed non-invasively by 64-row multi-slice computed tomographic (CT) imaging. The right sinus of Valsalva aneurysm rupturing into the right ventricular outflow region might be silent or symptomless in many cases. The patient also had mild symptom. For anatomical demonstration, contrast-enhanced CT was performed. Although the ruptured sinus of Valsalva was initially diagnosed by echocardiography, CT images did give our surgeons a better three-dimensional appreciation when surgical repair was performed. Multi-slice CT imaging should be considered the technique of choice for both diagnosis and follow-up examination of the aneurysm of sinus of Valsalva and its rupture.
Abstract: We present a case of a 57-year-old woman with an unremarkable medical history except for a continuous cardiac murmur at the left second and third interspaces. Transthoracic echocardiography revealed an unusual chamber in front of the heart. To evaluate the precise anatomy of this abnormality, multi-slice computed tomographic (MSCT) imaging was performed. MSCT angiography with retrospective ECG gating showed a coronary arterial malformation with fistulous communications to the coronary artery, pulmonary artery and the root of aorta. Images from MSCT coronary angiography can be helpful in understanding the tortuous configuration of the coronary arterial malformation.
Abstract: Institutional review board approval was obtained for multiple imaging examinations in healthy volunteers and patients and for the analysis of images. The purpose of the study, and the risks associated with radiation exposure with regard to stochastic effects that might result in cancer and/or genetic mutations, were explained to all subjects, and all questions from subjects were answered. Each subject provided written informed consent. The purpose of the study was to prospectively determine the respiratory protocol at computed tomography (CT) that results in the best registration of CT images with images acquired at single photon emission computed tomography (SPECT) in the thorax. Errors of registration between myocardial SPECT images and CT images obtained with different respiratory protocols (postinhalation breath hold, postexhalation breath hold, and free breathing) in 13 healthy subjects were compared. CT scans obtained with free breathing and postexhalation breath hold better matched SPECT images than did those obtained with postinhalation breath hold (one-way analysis of variance, P < .01). Fewer SPECT/CT images showed artifacts with registration performed by using internal landmarks (four, two, and one of 13 images with postinhalation breath-hold, postexhalation breath-hold, and free-breathing protocols, respectively) than with registration performed by using external markers (nine, four, and two of 13 images). CT data acquisition with a free-breathing or postexhalation breath-hold protocol and image registration by using internal landmarks are recommended for attenuation correction.
Abstract: Attenuation artifacts adversely affect the diagnostic accuracy of myocardial perfusion imaging. We assessed the clinical usefulness of X-ray CT based attenuation correction (AC) in patients undergoing myocardial perfusion imaging by comparing their myocardial AC- and non-corrected (NC) SPECT images with the coronary angiography (CAG).
Abstract: OBJECTIVE: The purpose of this study was to develop a method of fused images of coronary CT angiography and myocardial perfusion SPECT. CONCLUSION: Four patients with ischemic heart disease underwent 3D volume-rendering fused images using a conversion program and volume-rendering fusion function of a computer workstation. The fusion images clearly showed the relationship of relevant coronary arteries and the abnormal perfusion territory in all patients and were useful for the evaluation of coronary artery disease.
Abstract: The aim of our study was to compare T2-weighted and contrast-enhanced dynamic T1-weighted images with histologic findings in assessing the depth of myometrial invasion by endometrial carcinoma in adenomyosis.
Abstract: For transmission computed tomography (TCT) systems using a centered transmission source with a fan-beam collimator, the transmission projection data are truncated. To achieve sufficiently large imaging field of view (FOV), we have designed the combination of an asymmetric fan-beam (AsF) collimator and a small uncollimated sheet-source for TCT, and implemented AsF sampling on a two-head SPECT system. The purpose of this study is to evaluate the feasibility of our TCT method for quantitative emission computed tomography (ECT) in clinical application. Sequential Tc-99m transmission and Tl-201 emission data acquisition were performed in a cardiac phantom (30 cm in width) with a myocardial chamber and a patient study. Tc-99m of 185 MBq was used as the transmission source. Both the ECT and TCT images were reconstructed with the filtered back-projection method after scatter correction with the triple energy window (TEW) method. The attenuation corrected transaxial images were iteratively reconstructed with the Chang algorithm utilizing the attenuation coefficient map computed from the TCT data. In this AsF sampling geometry, an imaging FOV of 50 cm was yielded. The attenuated regions appeared normal on the scatter and attenuation corrected (SAC) images in the phantom and patient study. The good quantitative accuracy on the SAC images was also confirmed by the measurement of the Tl-201 radioactivity in the myocardial chamber in the phantom study. The AsF collimation geometry that we have proposed in this study makes it easy to realize TCT data acquisition on the two-head SPECT system and to perform quantification on Tl-201 myocardial SPECT.
Abstract: To investigate which is more suitable for whole-body screening with multidetector row CT (MDCT) during one breathhold, a uniphasic or biphasic injection protocol for contrast material.
Abstract: Attenuation correction is very important for quantitative SPECT imaging. We designed an uncollimated non-uniform line array source (non-uniform LAS) for attenuation correction based on transmission computed tomography (TCT) using Tc-99m and compared its performance with an uncollimated uniform line array source (uniform LAS) in a thorax phantom study. This non-uniform LAS was attached to one camera head of a dual-head gamma camera, and transmission data were acquired with another camera head with a low-energy, general purpose, parallel-hole collimator at 50 cm-distance apart from the source. The modified TEW using a subtraction factor of 1.0 was employed to correct scattered Tc-99m photons for transmission data. In the phantom experiment, eight TCT data were acquired with the scanning time changed from 2 minutes to 20 minutes for each LAS. The Tc-99m attenuation coefficient (mu) maps with the non-uniform LAS and uniform LAS improved the statistical count variation in the mediastinum filled with water as the scanning time got longer. The Tc-99m mu-map with the non-uniform LAS and 6 minutes of scanning time had equal quality at the center of the thorax phantom to that with the uniform LAS and 16 minutes of scanning time. In conclusion, for the TCT imaging with combination of the parallel hole collimator and uncollimated Tc-99m external source the non-uniform LAS can reduce the Tc-99m radioactivity or the TCT scanning time compared with the uniform LAS.
Abstract: The authors describe a case of struma ovarii coexisting with mucinous cystadenoma. Ultrasonography and magnetic resonance imaging showed a multilocular cystic mass with a solid component. The ovarian tumor demonstrated uptake of I-123 sodium iodide, allowing a preoperative diagnosis of struma ovarii. In women with an unexplained increase in thyroid function and low I-123 uptake in the cervical thyroid gland, scintigraphy of the pelvis should be considered.
Abstract: To assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD).
Abstract: We successfully performed embolization therapy for a pelvic arteriovenous malformation by the retrograde transvenous approach using a liquid embolic material. This malformation was unique in that it had a single draining vein, which allowed this technique employing an occlusion balloon.
