論文

症例は30歳代女性で、胃圧迫感を主訴とした。近医CTにて左腎腫瘍が疑われ当院を受診された。淡明細胞型腎細胞癌としては、充実部にT2強調像で低信号域が目立ち、皮髄相での造影効果が弱かった。乳頭状腎細胞癌type 1やXp11.2転座型腎細胞癌としては、腎実質相で造影効果が低下する点が合致しない。嫌色素性腎細胞癌やオンコサイトーマとしては、充実部にT2強調像で低信号域が目立ち、中心性瘢痕様部位においても造影効果を認めないことから中心性瘢痕ではなく広汎な出血や壊死と考えられた。fat-poor AML(hyperattenuating type)としては、腫瘍径が大きく不均一であり、angular interfaceもみられず、偽被膜様構造が目立った。術前診断は腎悪性腫瘍とした。これに対し、開胸開腹根治的左腎摘除術を施行した。肉眼的に、腎上極に灰白色〜黄色調の境界明瞭な充実性腫瘤を認めた。病理組織学的に、腫瘤全体に大小の多稜形細胞(類上皮型平滑筋成分)がシート状に増生しており、淡明ないし顆粒の目立つ好酸性細胞質、明瞭な核小体を伴う類円形核を有していた。50%程度に細胞異型や核異型あり、部分的に紡錘形細胞(紡錘型平滑筋成分)を認めるが、脂肪成分は認めなかった。免疫組織学的に、HMB45陽性、一部にSMA陽性上皮マーカー陰性であり、類上皮型血管筋脂肪腫の診断となった。

症例は70歳代男性で、内腸骨動脈瘤の精査中に左腎動脈瘤を指摘された。ダイナミックCTでは、動脈相にて左腎門部近傍の腹側枝の分枝に洋なし状の26×24×23mm大の嚢状動脈瘤を認めた。壁在血栓を伴い、瘤壁の石灰化を部分的に認めた。末梢分枝の支配領域は狭いことを考慮して、末梢分枝を塞栓した上で瘤内塞栓を行う方針となった。瘤の流入血管の塞栓は行わず、末梢分枝の近位の枝は1本開存している。30ヵ月後のダイナミックCTにて瘤のネック部の急速な増大とコイルの変位を認めたため、再塞栓を施行した。CTでネック部は急速に増大しているため、真性瘤ではあると思われたが、瘤壁が脆弱である可能性が高いと判断した。このため瘤壁に圧をかけないように慎重にpackingを行い、そのコイルを土台に流入血管を密に塞栓する方針とした。DSAで瘤は完全に塞栓され、流入血管内のコイルも腎動脈に突出することなく密に塞栓されたことを確認して手技を終了した。

下部消化管出血は年齢とともに増加し、背景疾患として大腸憩室、angiodysplasia、大腸炎や大腸癌があげられる。中でも大腸憩室出血は頻度がもっとも高く、本邦で増加している。NSAIDsやステロイド、抗血小板薬の使用が憩室出血の増加に拍車をかけている。出血の程度は軽微なものから生命を脅かすほど重篤なものまであるが、多くは保存的治療によって自然に止血し、特別な処置を要さない。重篤な出血に対しては内視鏡的止血術、IVRによる止血術いずれの有用性も報告されているが、どちらの治療法にも長所、短所がある。本稿では当院での大腸からの出血に対するIVRの治療成績を検討し、若干の文献的考察を加えて報告する。(著者抄録)

Objective: The objective of this retrospective study was to determine the frequency of right adrenal vein identification by computed tomography (CT) during right inferior phrenic arteriography (CTRIPA) and to describe the spectrum of anatomic variations of the right adrenal vein.

Purpose: We aimed to determine which of the following magnetic resonance (MR) imaging sequences is most effective for detecting prostate cancer: T2-weighted (T2W), dynamic contrast-enhanced (DCE) T1-weighted (T1W), or diffusion-weighted (DWI) imaging or apparent diffusion coefficient (ADC) mapping. Materials and Methods: We included 37 male patients with prostate cancer who underwent MR imaging before radical prostatectomy in this retrospective study. Sixty-four foci (>5 mm in size; 35 in the peripheral zone [PZ], 29 in the transitional zone [TZ]) were histopathologically determined to be prostate cancer. We determined the capacity of T2W, DCE-T1W, DWI, ADC mapping alone, and the combination of ADC mapping with DWI, and conventional MR sequences to detect prostate cancer, including their sensitivity and positive predictive value (PPV), with reference to the results obtained in histopathological examinations of whole-mount sections. Results: In the PZ, sensitivities were 31.4% (T2W), 37.1% (DCE-T1W), 51.4% (DWI), and 71.4% (ADC mapping); PPVs were 78.6% (T2W), 92.9% (DCE-T1W), 94.7% (DWI), and 96.0% (ADC mapping). Sensitivity was significantly higher of ADC mapping than other sequences. In the TZ, sensitivities were 55.1% (T2W), 44.8% (DCE-T1W), 82.8% (DWI), and 89.7% (ADC mapping); PPVs were 64.0% (T2W), 46.4% (DCE-T1W), 70.6% (DWI), and 72.2% (ADC mapping). Sensitivity was significantly higher of ADC mapping and DWI than conventional MR imaging, but there was no significant correlation between DWI/ADC mapping and T2W/DCE-T1W with respect to PPVs. Combining sequences did not improve sensitivity; only the PPV in the TZ improved when ADC mapping was combined with DCE-T1W. Conclusion: ADC mapping is the most effective standard MR imaging tool for detecting prostate cancer. The addition of DCE-T1W may improve the PPV of ADC mapping for diagnosing cancer in the TZ. © 2013 Japanese Society for Magnetic Resonance in Medicine.

Objective To investigate the effect of visceral fat on operative time and discuss whether the measurement of adipose accumulation could be used as a sensitive predictor of technical difficulty in performing laparoendoscopic single-site adrenalectomy (LESS-A) and laparoscopic adrenalectomy (LA). Methods We reviewed the medical records of 106 patients undergoing LA or LESS-A at our institution. Total fat area (TFA) and visceral fat area (VFA) were measured at the level of the L4 vertebra by computed tomography. To categorize the type of obesity, the VFA/TFA ratio was calculated. Multiple logistic regression analyses were performed to identify independent predictors of prolonged operative time. Results The VFA/TFA ratio does not always coincide with body mass index (BMI, r = 0.415), and a higher correlation coefficient was observed between operative time and the VFA/TFA ratio (r = 0.359) than with that of BMI (r = 0.189). Multivariate analysis revealed that pheochromocytoma, tumor size ≥5 cm, and the VFA/TFA ratio ≥0.35, defined as the visceral type of adipose accumulation, were independent predictive factors for prolonged operative time in LA and LESS-A. We were able to stratify patients into short, intermediate, and long operative times using these preoperative variables. Conclusion This study revealed that the visceral type of adipose accumulation increases operative complexity in LA and LESS-A as measured by operative time. The VFA/TFA ratio might be a more sensitive indicator of technical difficulty than that of BMI. © 2013 Elsevier Inc. All Rights Reserved.

OBJECTIVE • To examine the impact of visceral fat on surgical complexity in patients undergoing laparoscopic nephrectomy. PATIENTS AND METHODS • We reviewed the medical records of 121 patients who underwent laparoscopic nephrectomy from 2006 to 2010 at our institution. • The total fat area, visceral fat area (VFA) and subcutaneous fat area were measured at the level of the umbilicus using computed tomography (CT). • To identify the type of obesity, we divided VFA into ≥ 100 cm 2 and < 100 cm 2 . A VFA ≥ 100 cm 2 was used as the definition of visceral obesity. • We evaluated the impact of the VFA on technical difficulties encountered during laparoscopic nephrectomy by measuring operating time. RESULTS • A significant correlation was observed between body mass index (BMI) and operating time ( P < 0.001, r =0.316) in the patients undergoing laparoscopic nephrectomy. • VFA was also significantly correlated with operating time ( P < 0.001, r =0.348), and the correlation coefficient of VFA was higher than that of BMI. • Multivariate analysis showed that a high VFA was an independent risk factor for prolonged operating time ( P =0.009, odds ratio; 3.70), whereas BMI was not found to be a risk factor. CONCLUSIONS • The present data indicate that measurement of VFA by CT is of benefit for predicting the technical difficulty associated with laparoscopic radical nephrectomy. • Visceral obesity, which is one factor involved in metabolic syndrome, has a greater impact than BMI on the complexity of laparoscopic radical nephrectomy. © 2012 THE AUTHORS.

Objectives: The purpose of this study was to select the optimal monochromatic level for virtual monochromatic spectral (VMS) imaging to minimize the image noise of the liver parenchyma and to acquire a high contrast-to-noise ratio (CNR) of hypovascular hepatic metastases in the portal-dominant phase. Materials and Methods: This study was conducted with the approval of our institutional review board, and written informed consent was obtained from all the participating patients. Ninety patients with hepatic metastases were scanned by fast kilovoltage switching dual-energy computed tomography in the portal-dominant phase. One hundred one sets of VMS images in the range of 40 to 140 keV at 1-keV intervals were reconstructed. The image noise of the liver parenchyma in each patient and the CNR of each metastasis (n = 303) were measured on all the 101 VMS image sets. Data were analyzed by the paired t test and mixed-effects model. Bonferroni's method was used for multiple comparisons. Results: The lowest noise of the liver parenchyma was obtained in 6, 15, 31, 29, 7, 1, and 1 patient at 67, 68, 69, 70, 71, 72, and 73 keV, respectively. The mean noise of the liver parenchyma on the 69-keV VMS images in all 90 patients was significantly lower than that on the 67-, 68-, 71-, 72-, and 73-keV VMS images (P < 0.001); however, there was no significant difference in the mean noise of the liver parenchyma between the 69-keV and 70-keV VMS images (P = 0.279). For 95% of the hepatic metastases (288/303 metastases), the highest metastasis-to-liver CNR was obtained in the 66-to 71-keV VMS images. The mean metastasis-to-liver CNR for the 303 metastases was numerically highest at 68 keV; however, there was no significant difference in the mean metastasis-to-liver CNR between the 68-keV and 69-keV images (P = 0.737) or between the 68-keV and 70-keV images (P = 0.103). Conclusions: VMS imaging at approximately 70 keV (69-70 keV) yielded the lowest image noise of the liver parenchyma and a high CNR for hypovascular hepatic metastases in the portal-dominant phase. © 2012 by Lippincott Williams & Wilkins.

Purpose: To compare image quality obtained in phantoms with virtual monochromatic spectral (VMS) imaging with that obtained with conventional 120-kVp computed tomography (CT) for a given radiation dose. Materials and Methods: Three syringes were filled with a diluted contrast medium (each syringe contained a contrast medium with a different iodine concentration [5, 10, or 15 mg of iodine per milliliter]), and a fourth syringe was filled with water. These syringes were placed in a torso phantom meant to simulate the standard human physique. The phantom was examined with a CT system and use of the fast kilovoltage switching (80 and 140 kVp) and conventional (120 kVp) modes. Image noise and contrast-to-noise (CNR) ratio were analyzed on VMS images and 120-kVp CT images. Results: Image noise on VMS images in the range of 67-72 keV was significantly lower than that on the 120-kVp CT images (P < .014). Image noise was lowest at 69 keV and was 12% lower when compared with that on 120-kVp CT images. CNR on the VMS images was highest at 68 keV. CNR on the VMS images obtained at 68 keV in the syringes filled with diluted contrast material (5, 10, and 15 mg of iodine per milliliter) was 28%, 31%, and 30% higher, respectively, compared with that on the 120-kVp CT images (P < .001). Conclusion: VMS imaging at approximately 70 keV yielded lower image noise and higher CNR than did 120-kVp CT for a given radiation dose. VMS imaging has the potential to replace 120-kVp CT as the standard CT imaging modality, since optimal VMS imaging may be expected to yield improved image quality in a patient with standard body habitus. © RSNA, 2011.

Background: Although quantitative analysis using standardized uptake value (SUV) becomes realistic in clinical single-photon emission computed tomography/computed tomography (SPECT/CT) imaging, reconstruction parameter settings can deliver different quantitative results among different SPECT/CT systems. This study aims to propose a use of the digital reference object (DRO), which is a National Electrical Manufacturers Association (NEMA) phantom-like object developed by the Quantitative Imaging Biomarker Alliance (QIBA) fluorodeoxyglucose-positron emission tomography technical committee, for the purpose of harmonizing SUVs in Tc-99m SPECT/CT imaging. Methods: The NEMA body phantom with determined Tc-99m concentration was scanned with the four state-of-the-art SPECT/CT systems. SPECT data were reconstructed using different numbers of the product of subset and iteration numbers (SI) and the width of 3D Gaussian filter (3DGF). The mean (SUVmean), maximal (SUVmax), and peak (SUVpeak) SUVs for six hot spheres (10, 13, 17, 22, 28, and 37 mm) were measured after converting SPECT count into SUV using Becquerel calibration factor. DRO smoothed by 3DGF with a FWHM of 17 mm (DRO17 mm) was generated, and the corresponding SUVs were measured. The reconstruction condition to yield the lowest root mean square error (RMSE) of SUVmeans for all the spheres between DRO17 mm and actual phantom images was determined as the harmonized condition for each SPECT/CT scanner. Then, inter-scanner variability in all quantitative metrics was measured before (i.e., according to the manufacturers’ recommendation or the policies of their own departments) and after harmonization. Results: RMSE was lowest in the following reconstruction conditions: SI of 100 and 3DGF of 13 mm for Brightview XCT, SI of 160 and 3DGF of 3 pixels for Discovery NM/CT, SI of 60 and 3DGF of 2 pixels for Infinia, and SI of 140 and 3DGF of 15 mm for Symbia. In pre-harmonized conditions, coefficient of variations (COVs) among the SPECT/CT systems were greater than 10% for all quantitative metrics in three of the spheres, SUVmax and SUVmean, in one of the spheres. In contrast, all metrics except SUVmax in the 17-mm sphere yielded less than 10% of COVs after harmonization. Conclusions: Our proposed method clearly reduced inter-scanner variability in SUVs. A digital phantom developed by QIBA would be useful for harmonizing SUVs in multicenter trials using SPECT/CT.

Background: Our aim was to evaluate the effect of visceral obesity and impact of severe hydronephrosis on surgical complexity in patients undergoing laparoscopic radical nephroureterectomy (LRNU). Methods: From January 2000 to December 2013, 169 patients underwent radical nephroureterectomy at our institution. We retrospectively reviewed the medical records of 70 patients who underwent LRNU. We measured total fat area (TFA) and visceral fat area (VFA) at the level of the umbilicus using computed tomography. We defined accumulated visceral fat distribution as a VFA/TFA ratio ≥0.45. Ipsilateral hydronephrosis was graded from 0 to 4 by two uro-radiologists blinded to the clinical outcomes. Results: Among the 70 patients, VFA/TFA ratio was ≥0.45 in 40 patients (57.1%) and 28 (40.0%) had severe hydronephrosis (grade 3 or greater). Patients with a VFA/TFA ratio ≥0.45 had significantly longer pneumoperitoneum and total operation times compared to their counterparts (p = 0.047 and p = 0.002, respectively). Patients with severe hydronephrosis had significantly longer pneumoperitoneum and total operative times compared to their counterparts (p = 0.006 and p = 0.002, respectively). Multivariate logistic regression analysis showed that a high VFA/TFA and severe hydronephrosis were independent predictive factors for prolonged pneumoperitoneum (p = 0.048, HR = 2.90; p = 0.015, HR = 3.82, respectively) and total operative times (p < 0.001, HR = 18.7; p = 0.003, HR = 10.7; respectively). Other pre-clinical factors such as age, gender, BMI, clinical stage, tumor size, location, laterality, degree of perinephric stranding, and surgical procedure did not affect the operation times. Conclusion: The present data indicated that the visceral type of adipose accumulation and presence of severe hydronephrosis could provide preoperative information on the degree of technical difficulty associated with LRNU.

Objective: To investigate the prognostic significance of visceral obesity to predict recurrence after curative surgery for Japanese patients with localized renal cell carcinoma. Methods: The data of 285 patients who underwent curative surgery for localized renal cell carcinoma were retrospectively reviewed. Median follow-up was 36.7 months. The association between visceral obesity and recurrence-free survival rate was evaluated using the Kaplan-Meier method and Cox regression models. Visceral fat area at the level of the umbilicus measured using pre-operative computed tomography was used as an index of visceral obesity. Results: Twenty-nine patients (10.2%) experienced recurrence. Five-year recurrence-free survival rates were 91.3% in high visceral fat area group (≥120 cm2) and 76.9% in low visceral fat area group (<120 cm2) (P = 0.037); however, visceral fat area was not an independent predictor of recurrence- free survival in multivariate analysis. In the patients with clear cell renal cell carcinoma, 28 patients (11.6%) experienced recurrence. Five-year recurrence-free survival rates were 88.7% in high visceral fat area group and 71.0% in low visceral fat area group (P = 0.043), and visceral fat area was an independent predictor of recurrence-free survival (hazard ratio: 1.974, P = 0.042) as well as C-reactive protein, Fuhrman nuclear grade, tumor size and microvascular invasion. In patients with organ confined clear cell renal cell carcinoma in particular, visceral fat area was also a useful and independent predictor of recurrence-free survival (hazard ratio: 2.807, P = 0.038). Body mass index was not useful in either cohort. Conclusions: High visceral fat area was a positive predictive biomarker for better recurrence-free survival after curative surgeries for localized clear cell renal cell carcinomas; however, body mass index was not a predictor.

© 2020 The Authors. Cancer Medicine published by John Wiley & Sons Ltd. Background: The Response Evaluation Criteria in Solid Tumors (RECIST) for computed tomography (CT) is preoperatively used to evaluate therapeutic effects. However, it does not reflect the pathological treatment response (PTR) of pancreatic ductal adenocarcinoma (PDAC). The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) for positron emission tomography (PET)/CT is effective in other cancers. This study aimed to confirm the usefulness of PERCIST and the prognostic utility of PET/CT for PDAC. Methods: Forty-two consecutive patients with PDAC who underwent neoadjuvant therapy (NAT) and pancreatectomy at our institution between 2014 and 2018 were retrospectively analyzed. We evaluated the treatment response and prognostic significance of PET/CT parameters and other clinicopathological factors. Results: Twenty-two patients who underwent PET/CT both before and after NAT with the same protocol were included. RECIST revealed stable disease and partial response in 20 and 2 cases, respectively. PERCIST revealed stable metabolic disease, partial metabolic response, and complete metabolic response in 8, 9, and 5 cases, respectively. The PTR was G3, G2, and G1 in 8, 12, and 2 cases, respectively. For comparing the concordance rates between PTR and each parameter, PERCIST (72.7% [16/22]) was significantly superior to RECIST (36.4% [8/22]) (P =.017). The area under the curve survival values of PET/CT parameters were 0.777 for metabolic tumor volume (MTV), 0.500 for maximum standardized uptake value, 0.554 for peak standardized uptake value corrected for lean body mass, and 0.634 for total lesion glycolysis. A 50% cut-off value for the MTV reduction rate yielded the largest difference in survival between responders and nonresponders. On multivariate analysis, MTV reduction rates < 50% were independent predictors for relapse-free survival (hazard ratio [HR], 3.92; P =.044) and overall survival (HR, 14.08; P =.023). Conclusions: PERCIST was more accurate in determining NAT’s therapeutic effects for PDAC than RECIST. MTV reduction rates were independent prognostic factors for PDAC.

© 2019 the Author(s). Published by Wolters Kluwer Health, Inc. Aims:To investigate the usefulness of contrast-enhanced ultrasonography for diagnosing renal cell carcinoma (RCC) in dialysis patients.Material and methods:Of 1301 dialysis patients who underwent abdominal computed tomography (CT) between January 2012 and March 2017, 19 were suspected to have solid renal lesions; of these patients, 18 gave consent for and underwent contrast-enhanced ultrasonography with perflubutane in addition to CT; 13 underwent dynamic contrast-enhanced CT, and 5, who could not be administered iodinated contrast media, underwent unenhanced CT. The final diagnoses were based on histopathological findings or the presence/absence of enlargement of the lesion during follow-up.Results:Of the 19 lesions in 18 patients, 14 were diagnosed as RCC and 5 as benign cysts. CT facilitated accurate diagnosis in 10/19 lesions (52.6%) with obvious enhancement (≥20 Hounsfield units [HU]), while definitive diagnosis by CT was difficult in 9 lesions: 2 lesions showed ambiguous enhancement (10-20 HU), 1 lesion was an inflammatory cyst with obvious enhancement, and 6 lesions were assessed by unenhanced CT. Compared with CT, contrast-enhanced ultrasonography allowed more accurate diagnosis (McNemar test, P = .02) in 17/19 lesions (89.5%, 14 RCC and 3 cysts; including all lesions assessed by unenhanced CT and 2 with ambiguous enhancement on CT), with 1 false-positive (inflammatory cyst with hyper-enhancement) and 1 false-negative result due to deep location of the lesion.Conclusions:Contrast-enhanced ultrasonography was useful for the diagnosis of RCC in dialysis patients with suspected solid renal lesions especially when contrast enhancement was not obvious on CT or contrast-enhanced CT could not be performed.

The overall effect of lifestyle habits, such as alcohol consumption, on general health remains controversial and it is important to clarify how such habits affect aging-related health impairments. To discover novel impacts of lifestyle on general health, we employed a mathematical approach to perform a comprehensive, unbiased, cross-sectional analysis of data from 6036 subjects who participated in a Japanese health checkup. Notably, we found that moderate alcohol consumption was positively correlated with lung function, muscle mass, and strength. Health checkup data were collected periodically from the same subjects. These people were light to moderate drinkers who had high health awareness and were basically free of major underlying diseases. We next analyzed 5 years of data from 1765 of these subjects. We found that higher baseline alcohol consumption, as well as increased alcohol intake over 5 years attenuated time-related deterioration of forced vital capacity without affecting total lung volume. This effect was independent of smoking. Our study suggests a possible protective effect of moderate amounts of alcohol on lung function, due to increased muscle mass/strength and forced vital capacity.

Lymphedema occurs when interstitial fluid and fibroadipose tissues accumulate abnormally because of decreased drainage of lymphatic fluid as a result of injury, infection, or congenital abnormalities of the lymphatic system drainage pathway. An accurate anatomical map of the lymphatic vasculature is needed not only for understanding the pathophysiology of lymphedema but also for surgical planning. However, because of their limited spatial resolution, no imaging modalities are currently able to non-invasively provide a clear visualization of the lymphatic vessels. Photoacoustic imaging is an emerging medical imaging technique that provides unique scalability of optical resolution and acoustic depth of penetration. Moreover, light-absorbing biomolecules, including oxy-and deoxyhemoglobin, lipids, water, and melanin, can be imaged. Using exogenous contrast agents that are taken up by lymphatic vessels, e.g., indocyanine green, photoacoustic lymphangiography, which has a higher spatial resolution than previous imaging modalities, is possible. Using a new prototype of a photoacoustic imaging system with a wide field of view developed by a Japanese research group, high-resolution three-dimensional structural information of the vasculatures was successfully obtained over a large area in both healthy and lymphedematous extremities. Anatomical information on the lymphatic vessels and adjacent veins provided by photoacoustic lymphangiography is helpful for the management of lymphedema. In par-ticular, such knowledge will facilitate the planning of microsurgical lymphaticovenular anastomoses to bypass the excess fluid component by joining with the circulatory system peripherally. Although challenges remain to establish its implementation in clinical practice, photoacoustic lymphangiography may contribute to improved treatments for lymphedema patients in the near future.

Evaluating pulmonary regional function using pulmonary perfusion scintigraphy is so easy that it is used in daily clinical practice. However, this may not seem suitable for prediction of post-lobectomy lung function because it is difficult to divide lobar radioactive counts from pulmonary radioactivity on planar scintigraphic images. On the other hand, pulmonary perfusion SPECT with attenuation and scatter correction may help calculate lobar perfusion of the lung. We developed a new method for assessing pulmonary lobe function using three-dimensional (3D) image fusion of volume rendering SPECT/CT images. Our study showed that lobe-to-entire lung perfusion ratio with this 3D method (%lobe3D) was reproducible between 2 observers (rs = 0.97, ICC = 0.98). In addition, there was a high correlation between %lobe3D and lobe-to-entire lung perfusion ratio with 2D method (rs=0.98-0.99). In conclusion, our proposed method provides an accurate assessment for pulmonary lobar perfusion.

Background: Despite the improvement of cardiac CT, right heart visualization remains challenging. Objective: We herein describe a new method, called the time-adjusted gradual replacement injection protocol. The aim of this study was to compare this protocol with the split-bolus injection protocol. Methods: Fifty-two patients who had undergone dual-source cardiac CT were retrospectively recruited. Twenty-six patients were injected by using the split-bolus injection protocol, and 26 patients were injected by using the time-adjusted gradual replacement injection protocol. For this method, we injected contrast medium for 10seconds at a flow rate of 0.07× body weight mL/s, then gradually replaced the contrast material with saline until 2 seconds before finishing the scans. The CT attenuation was measured in 4 chambers, the aorta, and the coronary arteries. The visualization of the anatomic structures and the occurrence and severity of streak artifacts were scored for the cardiac structures in the heart. For the analyses, either Welch t-test or Student t-test was performed. Results: In the right heart, the CT values and visualization scores were significantly higher in the time-adjusted replacement injection group than in the split-bolus injection group, whereas the artifact scores were comparable between the 2 groups. The CT values, visualization scores, and artifact scores of the left heart were not significantly different between the 2 groups. Conclusions: In this study, the time-adjusted gradual replacement injection protocol provided excellent attenuation for visualization of the right heart. This method may help toaccurately evaluate the right cardiac anatomy and thereby identify any potential diseases. © 2014 Society of Cardiovascular Computed Tomography.