Association between pre-treatment computed tomography findings and post-treatment persistent decrease in lung perfusion blood volume.

The purpose of this study was to evaluate pre-treatment CT findings in patients with acute pulmonary embolism (PE) and determine the imaging findings associated with residual hypoperfused segments in post-treatment lung perfused blood volume (LPBV). We evaluated 91 patients with acute PE who underwent dual-energy CT before and after treatment. The location of thrombi (proximal or distal) and patency of the pulmonary artery (occlusive or non-occlusive) were recorded using pre-treatment computed tomography pulmonary angiography (CTPA). Residual hypoperfusion was defined as a perfusion-decreased area seen in both the pre- and post-treatment LPBVs. The association of the location of the thrombus and vascular patency of pre-treatment CTPA with residual hypoperfusion on a segmental and patient basis was examined. In the segment-based analysis, the proportion of residual hypoperfusion in the proximal group was significantly higher than that in the peripheral group (33/125 [26.4%] vs. 9/87 [10.3%], P = 0.004). Patient-based analysis also showed that the proportion of residual hypoperfusion in patients with pre-treatment proximal thrombus was significantly higher than those without (16/42 [38.1%] vs. 3/25 (12.0%); P = 0.022). Pre-treatment vascular patency was not significantly associated with residual hypoperfusion (P > 0.05). Therefore, careful follow-up is necessary, especially in patients with proximal thrombi.

Brown adipose tissue dysfunction promotes heart failure via a trimethylamine N-oxide-dependent mechanism.

Low body temperature predicts a poor outcome in patients with heart failure, but the underlying pathological mechanisms and implications are largely unknown. Brown adipose tissue (BAT) was initially characterised as a thermogenic organ, and recent studies have suggested it plays a crucial role in maintaining systemic metabolic health. While these reports suggest a potential link between BAT and heart failure, the potential role of BAT dysfunction in heart failure has not been investigated. Here, we demonstrate that alteration of BAT function contributes to development of heart failure through disorientation in choline metabolism. Thoracic aortic constriction (TAC) or myocardial infarction (MI) reduced the thermogenic capacity of BAT in mice, leading to significant reduction of body temperature with cold exposure. BAT became hypoxic with TAC or MI, and hypoxic stress induced apoptosis of brown adipocytes. Enhancement of BAT function improved thermogenesis and cardiac function in TAC mice. Conversely, systolic function was impaired in a mouse model of genetic BAT dysfunction, in association with a low survival rate after TAC. Metabolomic analysis showed that reduced BAT thermogenesis was associated with elevation of plasma trimethylamine N-oxide (TMAO) levels. Administration of TMAO to mice led to significant reduction of phosphocreatine and ATP levels in cardiac tissue via suppression of mitochondrial complex IV activity. Genetic or pharmacological inhibition of flavin-containing monooxygenase reduced the plasma TMAO level in mice, and improved cardiac dysfunction in animals with left ventricular pressure overload. In patients with dilated cardiomyopathy, body temperature was low along with elevation of plasma choline and TMAO levels. These results suggest that maintenance of BAT homeostasis and reducing TMAO production could be potential next-generation therapies for heart failure.

U-Net-based image segmentation of the whole heart and four chambers on pediatric X-ray computed tomography.

This study aimed to determine whether a U-Net-based segmentation method could be used to automatically extract regions of the whole heart and atrioventricular regions from pediatric cardiac computed tomography images with high accuracy. Pediatric cardiac contrast computed tomography images with no abnormalities (n = 20; patient age, 0-13 years; mean 5 years) were used for segmentation of the whole heart and each atrioventricular region using U-Net. Segmentation accuracy was evaluated using the Dice similarity coefficient. The mean Dice similarity coefficient for the whole-heart segmentation was high at 0.95. There were no significant differences between age categories. The median Dice similarity coefficients for segmentation of the atria and ventricles were good (> 0.86). There were significant differences between age categories at some sites. Differences in the Dice similarity coefficient may have occurred because the target diseases and examination procedures differed according to subject age. There was no clear tendency for similar values between subjects of school age, close to adulthood, and newborns; good agreement was obtained in all age categories. These results suggest that U-Net-based segmentation may be useful for automatic extraction of the whole heart and atrioventricular regions from pediatric computed tomography images.

Massive hemoptysis treated with embolization of an ectopic bronchial artery arising from the right thyrocervical trunk: a case report.

BACKGROUND: Ectopic bronchial artery and non-bronchial systemic arteries may be the culprit vessels of hemoptysis. The main cause of clinical failure of bronchial artery embolization is incomplete embolization caused by the misidentification of the culprit arteries by conventional angiography. Multidetector computed tomography angiography is useful for visualizing the culprit arteries. CASE PRESENTATION: An 82-year-old man was admitted with hemoptysis. Preprocedural multidetector computed tomography angiography revealed an ectopic bronchial artery branching from the right thyrocervical trunk. Superselective embolization of the ectopic bronchial artery was performed using gelatin sponge particles and metallic coils. Hemoptysis was controlled by this procedure without any associated complications. CONCLUSIONS: Ectopic bronchial arteries originating from the thyrocervical trunk are rare. Preprocedural multidetector computed tomography angiography is useful for visualizing the culprit arteries of hemoptysis, especially if a patient has an ectopic bronchial artery or an ectopic non-bronchial systemic artery.

Low Tube Voltage Computed Tomography Venography for Patients With Deep Vein Thrombosis of the Lower Extremities　- A Comparison With Venous Ultrasonography.

BACKGROUND: Low tube voltage computed tomography venography (CTV) can be expected to increase imaging contrast and decrease radiation exposure by using iterative reconstruction (IR). This study evaluated the diagnostic ability of low tube voltage CTV with IR for deep vein thrombosis (DVT), compared to ultrasonography (US).Methods and Results:Two experienced radiologists retrospectively reevaluated the CTV data of 55 of 318 consecutive patients suspected of having DVT or pulmonary embolism between December 2015 and April 2017. The 55 patients had undergone both low tube voltage CTV and US (within 1 day before or after CTV). The lower extremity veins were divided into 10 segments. The DVT forms were categorized into 3 types: complete, concentric, and eccentric. We analyzed the 534 overall segments (16 segments excluded in US) measured using both CTV and US. The sensitivity-specificity was overall 73.3-90.0%, for femoropopliteal, it was 90.0-93.2%, and for the calf, it was 71.1-87.2%. The diagnostic accuracy between the 'eccentric only' and 'others' groups focusing on DVT forms was compared, and significant differences were revealed, especially in the muscular vein. CONCLUSIONS: The DVT diagnostic ability above the knee was comparable between low tube voltage CTV with IR and conventional CTV, and the radiation dose was reduced. It was suggested that eccentric DVT measured by CTV tend to be a false-positive, especially in the calf muscular vein.

Computed tomography findings of acute gastric peptic ulcer.

PURPOSE: To report the computed tomography (CT) findings of acute peptic ulcer disease (PUD) and to evaluate the usefulness of contrast media for diagnosis. METHODS: This retrospective study included 51 patients diagnosed with acute gastric peptic ulcer by endoscopy. Using a κ analysis, two radiologists independently reviewed contrast-enhanced emergency CTs performed within 24 h of endoscopy. Evaluation findings included low-attenuation wall thickening, focal wall thickening, focal luminal outpouching, perigastric fat stranding, ascites, adjacent lymphadenopathy, and high-density gastric contents. Of the 51 patients, 48 underwent both non-contrast-enhanced and contrast-enhanced CT, and two radiologists also evaluated the presence or absence of these findings on a non-contrast-enhanced CT. McNemar's test was used to evaluate the contrast media's usefulness. RESULTS: Interobserver variability of perigastric fat stranding revealed substantial agreement between evaluators, and other findings had almost perfect agreement. High-density gastric contents were the most recognized findings (60%). Low-attenuation focal wall thickening and focal luminal outpouching were observed in relatively large numbers (~50%) of the cases on contrast-enhanced CT. The CT examinations using contrast media provided significantly higher detectability of low-attenuation wall thickening and focal luminal outpouching than CT examinations without using contrast media. CONCLUSION: Acute PUD can be suspected in patients with nonspecific abdominal symptoms in whom emergency CT shows high-density gastric contents, focal low-attenuation wall thickening, and/or focal luminal outpouching. Our study showed that contrast media are useful for diagnosis.

Screening and follow-up of chronic liver diseases with understanding their etiology in clinics and hospitals.

BACKGROUND AND AIM: Considering the increasing prevalence of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis (NASH), the development of an effective screening and follow-up system that enables the recognition of etiological changes by primary physicians in clinics and specialists in hospitals is required. METHODS: Chronic hepatitis B (HBV) and C (HCV), NASH, and alcoholic steatohepatitis (ASH) patients who were assayed for Mac-2-binding protein glycosylation isomer (M2BPGi) (n = 272) and underwent magnetic resonance elastography (MRE) (n = 119) were enrolled. Patients who underwent MRE were also tested by ultrasound elastography (USE) (n = 80) and for M2BPGi (n = 97), autotaxin (ATX) (n = 62), and platelet count (n = 119), and their fibrosis-4 (FIB-4) index was calculated (n = 119). RESULTS: FIB-4 index >2, excluding HBV-infected patients, M2BPGi >0.5, ATX >0.5, and platelet count <20 × 104/µL were the benchmark indices, and we took into consideration other risk factors, such as diabetes mellitus and age, to recommend further examinations, such as USE, based on the local situation to avoid overlooking hepatocellular carcinoma (HCC) in the clinic. During specialty care in the hospital, MRE exhibited high diagnostic ability for fibrosis stages >F3 or F4; it could efficiently predict collateral circulation with high sensitivity, which can replace USE. We also identified etiological features and found that collateral circulation in NASH/ASH patients tended to exceed high-risk levels; moreover, these patients exhibited more variation in HCC-associated liver stiffness than the HBV and HCV patients. CONCLUSIONS: Using appropriate markers and tools, we can establish a stepwise, practical, noninvasive, and etiology-based screening and follow-up system in primary and specialty care.

Japanese Survey of Radiation Dose Associated With Coronary Computed Tomography Angiography　- 2013 Data From a Multicenter Registry in Daily Practice.

BACKGROUND: Although coronary computed tomography angiography (CTA) is frequently used for identifying coronary artery disease, no studies have investigated the radiation dose in detail in Japan. The aim of this study was to estimate the radiation dose of coronary CTA in Japanese clinical practice and to identify the independent predictors associated with radiation dose.Methods and Results:A multicenter, retrospective, observational study (54 institutions) was conducted for estimating the radiation dose of coronary CTA in 2,469 patients between January and December 2013. Independent predictors associated with radiation dose were investigated on linear regression analysis. Median dose-length product (DLP) was 809.0 mGy·cm (IQR, 350.0-1,368.8 mGy·cm), corresponding to an estimated radiation dose of 11 mSv. The DLP per site significantly differed between institutions (median DLP per site, 92-2,131 mGy·cm; P<0.05). Independent predictors associated with radiation dose on multivariable linear regression were body weight, heart rate, non-stable sinus rhythm, scan length, tube voltage setting, electrocardiogram (ECG)-gated scanning protocol, and the image reconstruction technique (P<0.05 each). CONCLUSIONS: The coronary CTA radiation dose was relatively high in 2013, and it varied significantly between institutions. Effective strategies for radiation dose reduction were low tube voltage ≤100 kVp, retrospective ECG-gated scanning with dose modulation technique, prospective ECG-gated scanning, and the iterative reconstruction technique.

Quantitative 3D Shape Analysis of CT Images of Thymoma: A Comparison With Histological Types.

OBJECTIVE. The purpose of this study is to differentiate between low- and high-risk types of thymoma using quantitative 3D shape analysis of CT images. MATERIALS AND METHODS. This retrospective study included 44 patients with a pathologic diagnosis of thymoma. Two radiologists semiautomatically contoured CT images of the tumors and evaluated 3D shape parameters-namely, quantitative indicators of surface smoothness, including sphericity, ellipsoidality, and discrete compactness. The visual CT findings that were analyzed included longest diameter, shape (round-oval, lobulated, or irregular), calcification, cystic or necrotic changes, and enhancement pattern (homogeneous or heterogeneous). The difference and discriminating performance between low-risk (types A, AB, and B1) and high-risk (types B2 and B3) thymomas were statistically assessed. Interobserver agreement was determined using the concordance correlation coefficient. RESULTS. Twenty-three low-risk and 21 high-risk thymomas were identified on the basis of pathologic findings. The median values of sphericity and ellipsoidality were significantly higher for low-risk thymomas than for high-risk thymomas (for sphericity, 0.566 vs 0.517; for ellipsoidality, 0.941 vs 0.875; p < 0.05 for both). The AUC values of sphericity and ellipsoidality were 0.704 and 0.712, respectively. The best cutoff values were 0.528 and 0.919 for sphericity and ellipsoidality, respectively. Risk assessment combining these cutoff values and the mode of tumor detection (incidental detection or detection based on the presence of symptoms) improved the AUC value to 0.856 (sensitivity, 81.0% [17 of 21 patients]; specificity, 82.6% [19 of 23 patients]). All 3D shape parameters showed almost perfect interobserver agreement (concordance correlation coefficient, > 0.90). The visual CT findings were not significantly different between low- and high-risk thymomas (p > 0.05 for all). CONCLUSION. Quantitative 3D shape analysis has excellent reproducibility, and combining this technique with information on the detection mode helps differentiate low- from high-risk thymomas.

Detectability of the choroid plexus of the third ventricle with magnetic resonance ventriculography.

PURPOSE: To clarify the detectability of the choroid plexus of the third ventricle (ChPl3V) with magnetic resonance ventriculography (MRVn) employing a steady-state free precession (SSFP) sequence in comparison to surgical endoscopic movies as a golden standard, as we encountered some clinical cases of total agenesis of corpus callosum (ACC) where we could not recognize the choroid plexus of the third ventricle and found no previous article addressing this problem. MATERIALS AND METHODS: This retrospective study included consecutive patients from 2010 to 2016 for whom endoscopic evaluation of the third ventricle was conducted. The anterior portion of the right and left streaks of ChPl3V was evaluated in 8 patients on 16 sites, while the posterior portion of both streaks of ChPl3V was evaluated in 13 patients on 26 sites. Sensitivity of MRVn to visualize ChPl3V with endoscopic movies as the golden standard was calculated. RESULTS: Sensitivity of MRVn in visualizing the anterior portion of ChPl3V was 0.813, and that for the posterior portion 0.692. The anterior portion of ChPl3V was visualized in all cases where no tumor contacted the foramen of Monro. CONCLUSION: MRVn visualizes the anterior portion of ChPl3V with significant sensitivity and the posterior portion with lower one.

Assessment of a simple method of heart weight estimation by postmortem computed tomography.

BACKGROUND: Measurement of heart weight is important when investigating cause of death, but there is presently no satisfactory method of heart weight estimation by postmortem computed tomography (PMCT). METHOD: We investigated 33 consecutive cases that underwent both PMCT and autopsy between February 2008 and June 2014. Heart and left ventricular (LV) weights were calculated by PMCT morphometry. We used a simple method to estimate LV weight: We assumed that LV was an ellipsoid and multiplied its volume on PMCT with myocardial specific gravity. We then compared the various heart and LV weights using linear regression. The calculated and estimated LV weights on PMCT were also compared. RESULTS: It was not possible to predict heart weight at autopsy from PMCT (R2 = 0.53). However, heart weight at autopsy could be accurately predicted from LV weight calculated by PMCT (R2 = 0.77). In addition, there was a strong correlation between the estimated and calculated LV weights by PMCT (R2 = 0.92). Heart weight at autopsy could also be accurately predicted using the PMCT-estimated LV weight (R2 = 0.72). CONCLUSION: Heart weight at autopsy could be accurately predicted using a simple method in which LV volume was assumed to be an ellipsoid on PMCT.

Correction to: The sternalis muscle: radiologic findings on MDCT.

In the original publication of the article, the seventh author name was incorrectly published as Hidehumi Aoyama. The correct author name should read as Hidefumi Aoyama.

HRCT texture analysis for pure or part-solid ground-glass nodules: distinguishability of adenocarcinoma in situ or minimally invasive adenocarcinoma from invasive adenocarcinoma.

PURPOSE: To distinguish between adenocarcinoma in situ (AIS)-minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IAC) showing pure or part-solid ground-glass nodules (GGNs) by high-resolution computed tomography (HRCT) texture analysis. MATERIALS AND METHODS: This retrospective study included 101 consecutive patients with 115 pure or part-solid GGNs ≤ 3 cm diameter, which were surgically resected and pathologically diagnosed with AIS, MIA, or IAC (48 AIS-MIA and 67 IAC) between April 2011 and March 2015. Each tumor was manually segmented on axial CT images, and the following texture features were calculated: volume, mass, mean CT value, variance, skewness, kurtosis, entropy, uniformity, and percentile CT numbers (10th, 25th, 50th, 75th, 90th, 95th percentiles). The differences between AIS-MIA and IAC were statistically evaluated using univariate, multivariate, and receiver operating characteristic analysis. RESULTS: Compared with IAC, AIS-MIA had significantly greater skewness, kurtosis, and uniformity, whereas in the other parameters, AIS-MIA demonstrated significantly lower values than those of IAC. Multivariate analysis revealed that independent differentiators were the 90th percentile CT numbers (P < 0.001) and entropy (P = 0.005) with an excellent accuracy (area under the curve, 0.90). CONCLUSIONS: The 90th percentile CT numbers and entropy can accurately distinguish AIS-MIA from IAC.

Coronary computed tomography angiography using 128-slice dual-source computed tomography in patients with severe calcification.

PURPOSE: To compare coronary computed tomography angiography (CTA) and coronary angiography (CAG) with regard to luminal graphic definition of calcified segments using 128-slice dual-source computed tomography (DSCT), specifically for patients with an Agatston score >400. MATERIALS AND METHODS: Of 1148 consecutive patients who underwent coronary CTA using a 128-slice DSCT, 132 subjects had severe calcification with an Agatston score >400. Thirty-nine of the 132 patients who had undergone CAG within 3 months before or after coronary CTA were included. We investigated the distribution of calcification, and we visually evaluated significant stenosis in the calcified and all segments. Results were compared with CAG. RESULTS: The target group in this study had a very high mean Agatston score of 1771 ± 1724. Results for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 247 calcified vs all 325 segments were as follows: sensitivity 93.2 vs 92.2%, specificity 83.9 vs 87.5%, PPV 70.8 vs 69.6%, and NPV 96.7 vs 97.3%, respectively. CONCLUSION: 128-slice DSCT has potential for evaluation of calcified segments in the lumen, even in patients whose Agatston score exceeds 400.

Acute coronary syndrome: evaluation of detection capability using non-electrocardiogram-gated parenchymal phase CT imaging.

PURPOSE: To evaluate the capability to detect acute coronary syndrome (ACS) by using non-electrocardiogram-gated parenchymal phase CT imaging. MATERIALS AND METHODS: Of 962 consecutive patients who underwent emergent coronary angiography for suspected ACS, 32 with ACS who underwent CT ≤24 h before angiography and 15 without ACS who underwent CT ≤24 h before or after angiography were included. Parenchymal phase was acquired at 100-s scan delay. The presence of a myocardial perfusion defect (MPD) on the left ventricle (a decrease of >20 HU) and its capability to detect ACS were evaluated. Results were compared with laboratory findings. RESULTS: MPD was detected in 29 of 32 ACSs. The sensitivity, specificity, and positive and negative predictive values were 91 % (29/32), 93 % (14/15), 97 % (29/30), and 82 % (14/17), respectively. The sensitivities of ST- and non-ST-elevation ACSs were 89 % (16/18) and 93 % (13/14), respectively, without significant difference (P > 0.99). Of the CT-detectable ACS, non-ST-elevation on the electrocardiogram and a normal creatine kinase-myocardial band were observed in 41 % (12/29) and 24 % (7/29), respectively. CONCLUSION: ACS is highly detectable even using conventional parenchymal phase CT imaging. Therefore, even when CT is non-gating, radiologists should carefully evaluate the heart to avoid overlooking ACS.

CT measurement of splenic volume changes as a result of hypovolemic shock.

PURPOSE: To evaluate the changes in splenic volume during hypovolemic shock and after recovery by use of multidetector computed tomography (MDCT). MATERIALS AND METHODS: We investigated 22 cases who underwent MDCT during hypovolemic shock up to 3 h after presentation, compared the splenic volume with that after recovery, and evaluated the volume difference. We compared the volume ratio (recovery/shock) for two age groups: under 60 years (n = 10) and 60 years and over (n = 12). For cases (n = 10) undergoing CT examination twice after treatment, we compared the volume ratios by using the initial recovery CT and the second CT images. RESULTS: The average spleen volume in shock was 63 cm(3); under normal conditions it was 132 cm(3) (P < 0.001). The average volume ratio for groups under 60 years old was 2.34; for groups 60 years and over it was 2.05 (P = 0.051). The average volume ratio obtained by use of the initial post-recovery CT was 2.11; the ratio obtained by use of the second post-recovery CT was 2.16 (P = 0.386). CONCLUSIONS: Our results revealed that splenic volume was reduced during hypovolemic shock and rapidly increased after recovery. Splenic contraction is an important CT finding in shock.

A combination of preoperative CT findings and postoperative serum CEA levels improves recurrence prediction for stage I lung adenocarcinoma.

OBJECTIVES: To assess the prognostic value of combined evaluation of preoperative CT findings and pre/postoperative serum carcinoembryonic antigen (CEA) levels for pathological stage I lung adenocarcinoma. METHODS: This retrospective study included 250 consecutive patients who underwent complete resection for ≤ 3-cm pathological stage I (T1-2aN0M0) adenocarcinomas (132 men, 118 women; mean age, 67.8 years). Radiologists evaluated following CT findings: maximum tumor diameter, percentage of solid component (%solid), air bronchogram, spiculation, adjacency of bullae or interstitial pneumonia (IP) around the tumor, notch, and pleural indent. These CT findings, pre/postoperative CEA levels, age, gender, and Brinkman index were assessed by Cox proportional hazards model to determine the best prognostic model. Prognostic accuracy was examined using the area under the receiver operating characteristic curve (AUC). RESULTS: Median follow-up period was 73.2 months. In multivariate analysis, high %solid, adjacency of bullae or IP around the tumor, and high postoperative CEA levels comprised the best combination for predicting recurrence (P<0.05). A combination of these three findings had a greater accuracy in predicting 5-year disease-free survival than did %solid alone (AUC=0.853 versus 0.792; P=0.023), with a sensitivity of 85.7% and a specificity of 74.3% at the optimal threshold. The best cut-off values of %solid and postoperative CEA levels for predicting high-risk patients were ≥ 48% and ≥ 3.7 ng/mL, respectively. CONCLUSION: Compared to %solid alone, combined evaluation of %solid, adjacency of bullae or IP change around the tumor, and postoperative CEA levels improves recurrence prediction for stage I lung adenocarcinoma.

Differential diagnosis of uterine smooth muscle tumors using diffusion-weighted imaging: correlations with the apparent diffusion coefficient and cell density.

The purpose of this study is to investigate the utility of the apparent diffusion coefficient (ADC) in differentiating benign and malignant uterine smooth muscle tumors classified by signal intensity (SI) on T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), and to determine the correlation between ADC and tumor cell density. This retrospective study reviewed 168 lesions in 134 cases with pathologically confirmed uterine smooth muscle tumors, including 6 leiomyosarcomas and 3 smooth muscle tumors of uncertain malignant potential, and preoperative magnetic resonance imaging examinations performed between October 2009 and November 2012. T2WI and DWI were also performed for each subject. Tumors were then classified according to SI on T2WI and DWI relative to myometrial SI. The correlation between ADC and tumor cell density was also determined. In Group 1 (high on both T2WI/DWI), mean ADC was significantly lower for leiomyosarcoma (0.91 × 10(-3) mm(2)/s) than for leiomyoma (1.30 × 10(-3) mm(2)/s; p < 0.05) and mean cell density significantly higher for leiomyosarcoma (42.9%) than for leiomyoma (22.4%; p < 0.05). A strong negative correlation was seen between ADC and tumor cell density in Group 1 (Spearman, R = -0.72; p < 0.05). ADC may help to differentiate benign from malignant uterine smooth muscle tumors, particularly tumors with high SI on T2WI and DWI.

Analysis of decrease in lung perfusion blood volume with occlusive and non-occlusive pulmonary embolisms.

PURPOSE: The aim of this study was to determine if lung perfusion blood volume (lung PBV) with non-occlusive pulmonary embolism (PE) differs quantitatively and visually from that with occlusive PE and to investigate if lung PBV with non-occlusive PE remains the same as that without PE. MATERIALS AND METHODS: Totally, 108 patients suspected of having acute PE underwent pulmonary dual-energy computed tomography angiography (DECTA) between April 2011 and January 2012. Presence of PE on DECTA was evaluated by one radiologist. Two radiologists visually evaluated the PE distribution (segmental or subsegmental) and its nature (occlusive or non-occlusive) on DECTA and classified perfusion in lung PBV as "decreased," "slightly decreased," and "preserved". Two radiologists used a lung PBV application to set a region of interest (ROI) in the center of the lesion and measured HU values of an iodine map. In the same slice as the ROI of the lesion and close to the lesion, another ROI was set in the normal perfusion area without PE, and HUs were measured. The proportion of lesions was compared between the occlusive and non-occlusive groups. HUs were compared among the occlusive, non-occlusive, and corresponding normal groups. RESULTS: Twenty-five patients had 80 segmental or subsegmental lesions. There were 37 and 43 lesions in the occlusive and non-occlusive groups, respectively. The proportion of decreased lesions was 73.0% (27/37) in the occlusive group, while that of preserved lesions in the non-occlusive group was 76.7% (33/43). There was a significant difference in the proportion of lesions (P<0.001) between the two groups. HUs of the iodine map were significantly higher in the non-occlusive group than in the occlusive group (33.8 ± 8.2 HU vs. 11.9 ± 6.1 HU, P<0.001). There was no significant difference in HUs for the entire lesion between the non-occlusive (33.8 ± 8.2 HU) and corresponding normal group (34.5 ± 6.8 HU; P=0.294). CONCLUSION: Iodine perfusion tended to be visually and quantitatively preserved in lungs with nonocclusive PE. Lung PBV is required to evaluate pulmonary blood flow.