VMAT Planning With Xe-CT Functional Images Enables Radiotherapy Planning With Consideration of Lung Function.

Background/Aim: The most severe adverse event of radiotherapy in lung cancer is radiation pneumonitis (RP). Some indices commonly used to prevent RP are evaluated based on the anatomical lung volume. The irradiation dose may be more accurately assessed by using functional lung volume. We evaluated the usefulness of computed tomography (CT) incorporating functional ventilation images acquired by the inhalation of xenon (Xe) gas (Xe-CT functional images). Patients and Methods: Two plans were created for twelve patients: volumetric modulated arc therapy (VMAT) planning using conventional chest CT images (anatomical plans) and VMAT planning using Xe-CT functional images (functional plans), and the dosimetric parameters were compared. Results: Compared to the anatomical plans, the functional plans had significantly reduced V 20Gy in the high-functional lungs (p=0.005), but significant differences were not seen in the moderate-functional and low-functional lungs. Conclusion: The incorporation of Xe-CT functional images into VMAT plans enables radiotherapy planning with consideration of lung function.

Computed tomography pulmonary angiography and venography with a low dose of contrast medium.

The authors developed a method to ensure sufficient opacification of pulmonary vasculature for separate depiction of arteries and veins in three-dimensional form with a small dose of contrast medium utilizing a test injection to determine optimal timing of computed tomography (CT) scanning. The dose was determined by a simulation based on a pharmacokinetic model. The contrast medium was administered at a rate of 5.0 mL/s for 3 s, followed by helical scanning at the timing determined by a dynamic CT scanning following the test injection. Images of 20 consecutive patients acquired with a 64-row CT scanner were evaluated. Quality of vessel depiction was assessed on the basis of the following: HU values at the main pulmonary artery (MPA) and left atrium (LA), distance between the pleural surface and the distal end of the pulmonary vessels on three-dimensional CT pulmonary arteriography and venography (3D-CTPAV), and subjective visual assessment of quality of the 3D-CTPAV images. Time to generate the 3D-CTPAV images was recorded. The mean ± standard deviation (SD) of the HU values at MPA/LA and the distances to the pleural surface for pulmonary arteries/veins were 448.0 ± 123.1/277.3 ± 60.85 HU and 9.21 ± 3.60/10.7 ± 5.45 mm, respectively. The image quality was visually rated as excellent for all of the patients. The mean time ± SD to generate 3D-CTPAV images was 13.6 ± 6.7 min. In conclusion, three-dimensional images of the pulmonary vasculature can be created using 21 mL (including 6 mL for the test injection) of contrast medium.

Generation of ventilation/perfusion ratio map in surgical patients by dual-energy CT after xenon inhalation and intravenous contrast media.

BACKGROUND: While many studies have evaluated the change in lung volume before and after lung resection and correlated this with pulmonary function test results, there is very little evidence on the changes in ventilation perfusion ratio (V/Q) before versus after lung resection. In the present pilot study, we evaluated if V/Q mapping can be constructed using dual energy CT images. METHODS: Thirty-one lung cancer patients planned for pulmonary resection were included in this study. To evaluate ventilation, Xenon-enhanced CT was performed. This was immediately followed by perfusion CT. The two images were registered manually as well as using dedicated softwares, and division between ventilation pixels and perfusion pixels were done to produce the V/Q map. Also, in order to characterize the distribution of the V/Q, the following numerical indices were calculated; mean, median, mode, standard deviation (SD), coefficient of variation (CV), skewness, kurtosis, and fractal dimension (FD). Pulmonary function tests and blood gas parameters were measured using standard institutional procedures. RESULTS: In the whole group, VC, %VC, and FEV1 decreased significantly after resection. FEV1.0% was increased significantly after resection. No significant changes were seen in PaO2, PaCO2, and DLCO/VA before and after resection. The mean, median, mode, SD, skewness, kurtosis and FD of the V/Q did not change significantly before and after resection. A marginal but significant decrease in CV was seen before versus after resection. CONCLUSIONS: Overall, it was considered that the V/Q maps could be adequately generated in this study. With further accumulation of data, V/Q map generated by dual energy CT may become one of the potentially useful tools for functional lung imaging. TRIAL REGISTRATION: This trial was registered in University Medical Information Network in Japan ( UMIN000010023 ) on 13Feb2013.

Evaluation of pulmonary function using single-breath-hold dual-energy computed tomography with xenon: Results of a preliminary study.

Xenon-enhanced dual-energy computed tomography (xenon-enhanced CT) can provide lung ventilation maps that may be useful for assessing structural and functional abnormalities of the lung. Xenon-enhanced CT has been performed using a multiple-breath-hold technique during xenon washout. We recently developed xenon-enhanced CT using a single-breath-hold technique to assess ventilation. We sought to evaluate whether xenon-enhanced CT using a single-breath-hold technique correlates with pulmonary function testing (PFT) results.Twenty-six patients, including 11 chronic obstructive pulmonary disease (COPD) patients, underwent xenon-enhanced CT and PFT. Three of the COPD patients underwent xenon-enhanced CT before and after bronchodilator treatment. Images from xenon-CT were obtained by dual-source CT during a breath-hold after a single vital-capacity inspiration of a xenon-oxygen gas mixture. Image postprocessing by 3-material decomposition generated conventional CT and xenon-enhanced images.Low-attenuation areas on xenon images matched low-attenuation areas on conventional CT in 21 cases but matched normal-attenuation areas in 5 cases. Volumes of Hounsfield unit (HU) histograms of xenon images correlated moderately and highly with vital capacity (VC) and total lung capacity (TLC), respectively (r = 0.68 and 0.85). Means and modes of histograms weakly correlated with VC (r = 0.39 and 0.38), moderately with forced expiratory volume in 1 second (FEV1) (r = 0.59 and 0.56), weakly with the ratio of FEV1 to FVC (r = 0.46 and 0.42), and moderately with the ratio of FEV1 to its predicted value (r = 0.64 and 0.60). Mode and volume of histograms increased in 2 COPD patients after the improvement of FEV1 with bronchodilators. Inhalation of xenon gas caused no adverse effects.Xenon-enhanced CT using a single-breath-hold technique depicted functional abnormalities not detectable on thin-slice CT. Mode, mean, and volume of HU histograms of xenon images reflected pulmonary function. Xenon images obtained with xenon-enhanced CT using a single-breath-hold technique can qualitatively depict pulmonary ventilation. A larger study comprising only COPD patients should be conducted, as xenon-enhanced CT is expected to be a promising technique for the management of COPD.

Prediction of postoperative pulmonary function: preliminary comparison of single-breath dual-energy xenon CT with three conventional methods.

PURPOSE: To assess the use of xenon ventilation maps (Xe-images) for predicting postoperative pulmonary function. MATERIALS AND METHODS: After study approval by the institutional review board, written informed consent was obtained from 30 patients with lung tumors who underwent pre- and postoperative spirometry, pulmonary perfusion SPECT and dual-energy CT (80 kV and 140 kV/Sn) after single-breath inspiration of 35 % xenon. Xe-images were calculated by three-material decomposition. Sum of pixel values of the part to be resected (A) and of the whole lung (B) on Xe-images or lung perfusion SPECT, and volumes or the number of segments of the part to be resected (A) and of the whole lung (B) on Xe-images were enumerated, respectively. We multiplied (1 - A/B) by each preoperative value from spirometry for prediction. Predictions by each of the four methods were compared with postoperative values. RESULTS: Predicted values for vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) by the four methods regressed significantly with measured values (R (2) = 0.56-0.77, p < 0.001 for all). CONCLUSION: Analysis of Xe-images can predict postoperative VC, FVC and FEV1 with accuracy comparable to that of CT volumetry.

Multidetector CT appearance of adhesion-induced small bowel obstructions: matted adhesions versus single adhesive bands.

Adhesive small bowel obstruction (SBO) is a common cause of abdominal pain after surgery or peritonitis. The role of computed tomography (CT) in the evaluation of SBO has expanded. Diagnosis of adhesive SBO, however, remains challenging. Adhesions causing SBO are classified as either matted adhesions or single adhesive bands, and both types have different mechanisms that lead to SBO. In patients with matted adhesions, SBO results from angulation and kinking or from torsion of the intestines. In patients with adhesive bands, SBO results from compression of the intestine caused by the band itself. Recent advances in spatial resolution using multidetector CT (MDCT) have enabled detailed assessment of the configuration of the SBO site. Presented in this pictorial essay are characteristic MDCT findings regarding the mechanism of the obstruction process of adhesive SBO.

Appendiceal diverticulitis: multidetector CT features.

PURPOSE: Appendiceal diverticulitis has been difficult to distinguish from acute appendicitis clinically and radiologically. The purpose of this study was to describe multidetector computed tomography (MDCT) features of cases of pathologically proved appendiceal diverticulitis at our institution over a 36-month period. MATERIALS AND METHODS: Seven of 156 patients who underwent appendectomy with the preoperative diagnosis of acute appendicitis were pathologically diagnosed with appendiceal diverticulitis. Two radiologists reviewed the MDCT images for these 7 patients. RESULTS: On MDCT, a total of 8 inflamed diverticula were visualized as small fluid-filled luminal structures with thick enhanced walls or as solid enhanced masses protruding from the appendix for 6 of 7 patients. For 2 of these 6 patients, MDCT revealed a total of 5 normal diverticula visualized as small air-filled luminal structures with thin walls. For 1 of the 7 patients, neither inflamed or normal diverticula could be identified on MDCT. MDCT revealed appendiceal wall thickening with a tiny or no luminal fluid collection for 5 patients and with a moderate fluid collection for 1 patient, and a normal appendiceal wall for 1 patient. CONCLUSION: Our results suggest that MDCT can reveal appendiceal diverticula and has potential in the preoperative diagnosis of appendiceal diverticulitis.

Imaging of ventilation with dual-energy CT during breath hold after single vital-capacity inspiration of stable xenon.

PURPOSE: To assess single-breath-hold technique for ventilation mapping by using dual-energy computed tomography (CT) in phantom experiments and volunteers. MATERIALS AND METHODS: Institutional review board approved this study, and written informed consent was obtained from all volunteers. A rubber bag filled with a mixture of xenon (0%-35.4%) and oxygen was scanned with dual-source dual-energy CT (80 kV and 140 kV with tin [Sn] filter [Sn/140 kV] and 100 kV and Sn/140 kV). A cylinder containing six tubes of identical sizes with different apertures was ventilated once with a mixture of 35% xenon and 65% oxygen and was scanned in dual-energy mode (80 kV and Sn/140 kV). Xenon-enhanced images were derived by using three-material decomposition technique. Four volunteers were scanned twice in dual-energy mode (80 kV and Sn/140 kV) during breath hold after a single vital-capacity inspiration of air (nonenhanced) and of 35% xenon. Xenon-enhanced images were obtained by using two methods: three-material decomposition and subtraction of nonenhanced from xenon-enhanced images. Regression analysis with t and F tests was applied to the data of the rubber bag scans, with the significance level set at .05. RESULTS: Mean pixel values of gas in the bag were linearly related to xenon concentration for all x-ray tube voltages (r(2) = 1.00, P < .00001). Pixel values of the xenon-enhanced images of the tubes were related to their aperture size. Nearly homogeneous (coefficient of variation: 0.22, 0.23, and 0.34) pixel values were found in the lungs of healthy volunteers, with higher pixel values in the trachea and lower pixel values in the bullae. Xenon-enhanced images calculated by using three-material decomposition had better image quality on visual comparison than those calculated by using subtraction. CONCLUSION: Xenon-enhanced dual-energy CT with the single-breath-hold technique could depict ventilation in phantoms and in four volunteers.

Cystic artery bleeding due to blunt gallbladder injury: computed tomography findings and treatment with transcatheter arterial embolization.

Blunt gallbladder injury is rare, and bleeding from the cystic artery due to blunt trauma is even rarer. We report herein a case of extraluminal bleeding of the gallbladder in a patient following blunt abdominal trauma. Contrast-enhanced computed tomography revealed pericholecystic fluid and extravasation of contrast material in the subcapsular liver space adjacent to the gallbladder. Abdominal digital subtraction angiography revealed pseudoaneurysm originating from a branch of the cystic artery. Successful treatment was achieved using selective transcatheter embolization, and cholecystectomy was not required.

Relation between pulmonary embolus volume quantified by multidetector computed tomography and clinical status and outcome for patients with acute pulmonary embolism.

PURPOSE: The aim of this study was to determine whether pulmonary embolus volume (PEV) obtained with multi-detector row computed tomography is related to clinical status and outcomes. MATERIALS AND METHODS: Subjects comprised 48 patients with acute pulmonary embolism (PTE). PEV was measured by tracing the contours manually and compared between sets of two groups divided by clinical status. Correlations of PEV to blood gases and D-dimer levels were investigated. PEV was tested as a predictor of clinical probability of acute PTE using Wells' criteria and as a predictor of survival after PTE by logistic regression analysis. RESULTS: The PEV was greater in groups with respiratory symptoms (P < 0.001), PTE as pretest clinical diagnosis (P = 0.027), and heart rate >100 beats/min (P < 0.001). It was smaller in subjects with concurrent malignancy (P = 0.02). It was correlated with PaCO(2) (P = 0.04, rho = -0.37) and the D-dimer level (P = 0.002, rho = 0.46); it was not a predictor of clinical probability of acute PTE or survival after PTE. The survival rate did not differ between groups with PEV > 10 ml (8/9) or

Correlation of left ventricular dyssynchrony with myocardial stunning using dual single photon emission computed tomography of (123)iodine-beta-methyl iodophenyl pentadecanoic acid and (201)thallium scintigraphy after reperfusion therapy.

OBJECTIVE: Left ventricular (LV) dyssynchrony after reperfusion therapy has been closely examined as a cause of chronic remodeling, but the details have not been clarified. The present study measured LV dyssynchrony appearing immediately after reperfusion therapy using real-time three-dimensional echocardiography (RT-3DE), and assessed the significance of this phenomenon in relation to dual single photon emission computed tomography (SPECT) of (123)iodine beta methyliodophenyl pentadecanoic acid ((123)I-BMIPP) and (201)thallium ((201)Tl). METHODS: Subjects comprised 58 patients with first-time acute myocardial infarction who received reperfusion therapy and underwent RT-3DE and dual SPECT of (123)I-BMIPP and (201)Tl within two weeks of onset. Two dyssynchrony parameters were measured using RT-3DE in the acute phase and six months later. After evaluating the correlation of these dyssynchrony parameters to resting (201)Tl uptake, (201)Tl washout, (123)I-BMIPP uptake, and (201)Tl-(123)I-BMIPP discrepancy (Tl-BMIPP discrepancy), we compared scintigraphic parameters in the chronic phase between groups with improved dyssynchrony and those without. RESULTS: Acute dyssynchrony exhibited a significant positive correlation to Tl-BMIPP discrepancy and it was significantly increased in the group with improved dyssynchrony in the chronic phase, revealing close relationship between dyssynchrony and Tl-BMIPP discrepancy. Then the subjects were divided into positive Tl-BMIPP discrepancy and negative discrepancy groups, and the parameters of cardiac function were compared between them. In the chronic phase, improved cardiac function was observed in the group with positive Tl-BMIPP discrepancy compared to negative discrepancy. CONCLUSION: LV dyssynchrony after reperfusion therapy correlates positively with Tl-BMIPP discrepancy, reflecting acute myocardial stunning, in which ventricular contraction improves during the chronic phase.

Evaluation of quality of life and psychological response in cancer patients treated with radiotherapy.

PURPOSE: The importance of the quality of life (QOL) and mental condition of patients being treated for cancer is now recognized. In this study, we evaluated QOL and mental condition in patients with cancer before and after radiotherapy. MATERIALS AND METHODS: The subjects were 170 patients who had undergone radiotherapy. The examination of QOL was performed using the quality of life questionnaire for cancer patients treated with anticancer drugs (QOL-ACD), and mental condition (anxiety and depression) was examined using the hospital anxiety and depression scale (HADS). These examinations were performed at the start of radiotherapy and immediately after radiotherapy. RESULTS: The QOL score was slightly higher in all patients after the completion of radiotherapy than before the start of radiotherapy. In the palliative radiotherapy group, QOL score was significantly improved by treatment. Anxiety and depression were improved after radiotherapy. There was a correlation between the degrees of improvement of the HADS and QOL score. CONCLUSION: We could treat cancer patients by radiotherapy without reducing their QOL, and improvement in QOL was significant in the palliative radiotherapy group. Mental condition was also improved after radiotherapy.

Multidetector computed tomography diagnosis of primary and secondary epiploic appendagitis.

PURPOSE: The aim of this study was to evaluate the epiploic appendages in patients with acute abdomen using multidetector computed tomography (MDCT) and to determine the incidence of primary and secondary epiploic appendagitis (EA). MATERIALS AND METHODS: A radiologist reviewed MDCT images from 1338 patients with acute abdomen for visible epiploic appendages. Two radiologists then reviewed the MDCT images showing inflamed epiploic appendages and diagnosed primary EA, secondary EA, or other conditions by consensus. The CT criteria for primary EA are a round or oval pericolonic fatty lesion with a hyperattenuated rim and adjacent fat stranding, without other causes of inflammation. Secondary EA is diagnosed if an epiploic appendage is found to be due to inflammation from other inflammatory entities. RESULTS: Epiploic appendages were identified in 19 patients. Four patients (0.3%) had a retrospective CT diagnosis of primary EA. Twelve patients (0.9%) had a retrospective CT diagnosis of secondary EA (primary condition was diverticulitis in 10 patients and inflammatory bowel disease in 2 patients). The remaining three patients had calcification of an epiploic appendage suggestive of old EA. CONCLUSION: Primary EA should be included in the differential diagnosis of acute abdomen. Occasionally, inflammation of the epiploic appendages is secondary to other inflammatory conditions.

Relationship between (99m)Tc-GSA scintigraphic indices of liver function reserve and portal circulation in patients with chronic liver disease.

OBJECTIVES: In order to predict the prognosis or complications of portal hypertension in patients with chronic liver disease, it is important to evaluate both hepatic functional reserve and portal circulation. On (99m)Tc-galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy, the index of blood clearance (HH15) and receptor index (LHL15) have been widely used to evaluate the hepatic functional reserve. However, the relationship between these indices and portal circulation is unknown. The purpose of this study was to examine the relationship between HH15 and LHL15 and portosystemic shunts evaluated with arteriographic portography or esophagogastroduodenoscopy. METHODS: A total of 82 patients with chronic liver disease (mean age, 66.7 years) who underwent (99m)Tc-GSA scintigraphy, arteriographic portography, and esophagogastroduodenoscopy were enrolled. HH15 and LHL15 were obtained from dynamic (99m)Tc-GSA scintigraphy. The patients were divided into three groups according to the arteriographic portography findings: group 1, no portal collateral circulation; group 2, mild collateral development; and group 3, moderate to severe collateral development. They were also divided into three groups based on the esophagogastroduodenoscopic findings: group A, no varices; group B, small-caliber varices; and group C, enlarged varices. The Kruskal-Wallis test was used to compare each index among these groups. Receiver operating characteristic (ROC) analysis was used to determine whether each index was an indicator for the presence of portosystemic shunts. RESULTS: Both HH15 and LHL15 differed significantly between groups 1 and 2 and between groups 1 and 3. However, only HH15 differed significantly between groups A and B and between groups A and C. On the basis of the ROC analysis, the HH15 threshold value of 0.62 yielded both excellent sensitivity (83.9%) and specificity (84.6%) for the presence of portosystemic shunts, as evaluated with arteriographic portography. The HH15 threshold value of 0.64 yielded both good sensitivity (66.1%) and specificity (69.2%) for the presence of portosystemic shunts, as evaluated with esophagogastroduodenoscopy, whereas no adequate threshold value of LHL15 was found for the presence of portosystemic shunts. CONCLUSIONS: HH15 is a potent indicator of the presence of portosystemic shunts in chronic liver disease.

Three-dimensional assessment of urinary stone on non-contrast helical computed tomography as the predictor of stonestreet formation after extracorporeal shock wave lithotripsy for stones smaller than 20 mm.

The incidence of stonestreet formation after extracorporeal shock wave lithotripsy (ESWL) rises with increasing stone burden. However, stonestreet after ESWL is often experienced even in stones smaller than 20 mm. To examine whether the non-contrast helical computed tomography (CT) data could predict stonestreet formation in these stones, 53 radiopaque stones of 5-20 mm treated with ESWL were evaluated. Maximal dimension was measured on plain radiograph. From an attenuation value histogram graphed from the CT data, total stone volume and mean attenuation value were calculated. Seven stonestreets longer than 25 mm developed. There was no significant difference in maximal dimension and total stone volume between stones that did and stones that did not develop stonestreet. Mean attenuation value was the sole significant predictive factor. Application of mean attenuation value with cut-off level of 650 HU would anticipate stonestreet formation with a sensitivity of 85.7% and a specificity of 71.7%. The estimated risk of stonestreet formation is high in the treatment of stones with higher mean attenuation value.

Arteriovenous malformation of the gallbladder: CT and angiographic findings.

We encountered a case of arteriovenous malformation (AVM) of the gallbladder in a patient with hepatocellular carcinoma (HCC). Contrast-enhanced computed tomography (CT) showed serpentine vessels around and within the gallbladder wall. Angiography showed dilated and tortuous cystic arteries, a racemose vascular network, and early-filling cystic veins. Transcatheter arterial embolization of two cystic arteries feeding the AVM was performed with platinum microcoils prior to transcatheter arterial chemoembolization for HCC to prevent embolic particles from flowing into these arteries. Follow-up contrast-enhanced CT showed blood flow in the gallbladder AVM, which appeared to be fed by the arterial collaterals.

Discrimination between ureteral stent and stone by non-contrast helical computed tomography in the clinical setting.

OBJECTIVE: In urolithiasis with indwelling ureteral stent, an adequate visualization of retained stone is often obscured by the stent. In functional solitary kidney, it is essential to detect retained fragments before stent removal. We examined the capability of non-contrast helical computed tomography (NCHCT) in discriminating stone from stent. PATIENTS AND METHODS: We assessed the CT of 21 radiopaque stones of 3-5 mm and four stents, and compared their attenuation values. In addition, two other cases with stent, in which only NCHCT by manipulating the setting could detect retained fragments. RESULTS: No overlaps of attenuation value were found between the stones and stents. Although they had the same appearance in NCHCT with abdominal-window setting, in bone-window setting the contrasts of stones were reduced, while stents were still bright white. CONCLUSIONS: We would discriminate the residual stone from the stent by manipulating window and level setting, and bone-window setting is easy to use.