Preoperative CT Findings for Predicting Acute Exacerbation of Interstitial Pneumonia After Lung Cancer Surgery: A Multicenter Case-Control Study.

BACKGROUND. Acute exacerbation (AE) is a life-threatening complication of inter-stitial pneumonia (IP). Thoracic surgery may trigger AE. OBJECTIVE. The purpose of this study is to explore the role of preoperative CT findings in predicting postoperative AE in patients with IP and lung cancer. METHODS. This retrospective case-control study included patients from 22 institutions who had IP and underwent thoracic surgery for lung cancer. AE was diagnosed on the basis of symptoms and imaging findings noted within 30 days after surgery and the absence of alternate causes. For each patient with AE, two control patients without AE were identified. After exclusions, the study included 92 patients (78 men and 14 women; 31 with AE [the AE group] and 61 without AE [the no-AE group]; mean age, 72 years). Two radiologists independently reviewed preoperative thin-slice CT examinations for pulmonary findings and resolved differences by consensus. The AE and no-AE groups were compared using the Fisher exact and Mann-Whitney U tests. Multivariable logistic regression was performed. Interreader agreement was assessed by kappa coefficients. RESULTS. A total of 94% of patients in the AE group underwent segmentectomy or other surgery that was more extensive than wedge resection versus 75% in the no-AE group (p = .046). The usual IP pattern was present in 58% of the AE group versus 74% of the no-AE group (p = .16). According to subjective visual scoring, the mean (± SD) ground-glass opacity (GGO) extent was 6.3 ± 5.4 in the AE group versus 3.9 ± 3.8 in the no-AE group (p = .03), and the mean consolidation extent was 0.5 ± 1.2 in the AE group versus 0.1 ± 0.3 in the no-AE group (p = .009). Mean pulmonary trunk diameter was 28 ± 4 mm in the AE group versus 26 ± 3 mm in the no-AE group (p = .02). In a model of CT features only, independent predictors of AE (p < .05) were GGO extent (odds ratio [OR], 2.8), consolidation extent (OR, 9.4), and pulmonary trunk diameter (OR, 4.2); this model achieved an AUC of 0.75, a PPV of 71%, and an NPV of 77% for AE. When CT and clinical variables were combined, undergoing segmentectomy or more extensive surgery also independently predicted AE (OR, 8.2; p = .02). CONCLUSION. The presence of GGO, consolidation, and pulmonary trunk enlargement on preoperative CT predicts AE in patients with IP who are undergoing lung cancer surgery. CLINICAL IMPACT. Patients with IP and lung cancer should be carefully managed when predictive CT features are present. Wedge resection, if possible, may help reduce the risk of AE in these patients. TRIAL REGISTRATION. University Hospital Medical Information Clinical Trial Registry UMIN000029661.

The effect of the virtual monochromatic spectral imaging for the metallic artifact and the pulmonary nodule detection.

OBJECTIVES: This study aimed to evaluate whether dual-energy computed tomography can reduce metal artifacts and improve detection of pulmonary nodules. METHODS: Twelve simulated nodules were randomly placed inside a chest phantom with a pacemaker. Then, dual-energy computed tomography was performed, and 5 virtual monochromatic images at 40, 50, 65, 100, and 140 keV were reconstructed with 5- and 0.625-mm slice thicknesses. Two independent observers assessed the metal artifact (3-point scale from 1, none, to 3, severe) and detection of the nodule (5-point scale from 1, definitely absent, to 5, definitely present). Statistical analysis was performed with a P value of less than 0.01 (0.05/5). RESULTS: With both slice thicknesses, the metallic artifact increased at 40 or 50 keV and decreased at 100 or 140 keV relative to that at 65 keV (P < 0.01). The nodule detection score was not significantly different between each kiloelectron volt level with the 0.625-mm slice thickness; however, the score was significantly worse at 40 keV compared to 65 keV (P < 0.01) with the 5-mm slice thickness. CONCLUSIONS: High monochromatic energy images can reduce metal artifacts without a change in nodule detection score. Low monochromatic energy images increase metal artifacts and worsen nodule detection in thick slices.

Image quality of 320-detector row wide-volume computed tomography with diffuse lung diseases: comparison with 64-detector row helical CT.

OBJECTIVES: To evaluate image quality of 320-detector row wide-volume (WV) computed tomography (CT) compared to 64-detector row helical CT from axial images and coronal multiplanar reformation (MPR). METHODS: Thirty-five patients with diffuse lung diseases were scanned using both 320-detector row WV CT (coneXact and volumeXact+) and 64-detector row helical protocols. Three blinded observers evaluated dislocation and heterogeneity of normal structures on 3 MPR patterns (WV scan with coneXact, WV scan with volumeXact+, and helical scan) using a 3-point scale from 1 (severe dislocation/heterogeneity) to 3 (no dislocation/heterogeneity). They also evaluated axial images of 2 scan patterns (WV with volumeXact+ and helical) using a 5-point scale from 1 (nondiagnostic) to 5 (excellent). Statistical analyses were performed with a post hoc test, Wilcoxon signed rank test, Mann-Whitney U test, or the Kendall W test. RESULTS: The WV scans with the coneXact algorithm had significantly lower quality scores than the WV scans with the volumeXact+ algorithm and the helical scans (P < 0.01) with MPR. Helical scans had significantly lower quality scores than the WV scans with volumeXact+ for heterogeneity on the mediastinal window setting with MPR (P < 0.01). There were no significant differences concerning total image quality of axial images between the WV scans with the volumeXact+ algorithm and the helical scans. CONCLUSIONS: The overall image quality of WV scans with the volumeXact+ algorithm was almost comparable to that of the helical scans on the lung window setting, but density homogeneity with helical scans was inferior to that of the WV scans with the volumeXact+ algorithm on the mediastinal window setting with MPR.

Multidetector CT of the lung: image quality with garnet-based detectors.

PURPOSE: To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors. MATERIALS AND METHODS: The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed by using the Heitzman method were scanned by using both CT with garnet-based detectors and CT with conventional detectors. Tube current was 400 mA for standard-dose and 10 mA for reduced-dose CT, and voltage was 120 kVp. Either normal scan mode with 984 views (conventional and garnet-based detectors) or high-resolution mode with 2496 views was used. Image quality at conventional-detector CT and garnet-based-detector CT in all modes was graded by two independent observers with a five-point scale. The evaluation items included normal lung structures, subjective visual noise, and abnormal CT findings. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest on each selected image. RESULTS: At standard-dose CT, image quality at CT with garnet-based detectors (high-resolution mode) was significantly improved (P < .001, Tukey-Kramer). However, there was no significant difference between quantitative image noise measurements (P > or = .24). At reduced-dose CT, only noise differed significantly, with both subjective visual noise and quantitative image noise measurements significantly greater at CT with garnet-based detectors (high-resolution mode) (P < or = .01). There was no significant difference in image quality except for noise between conventional-detector CT and garnet-based-detector CT (P > or = .06). CONCLUSION: The image quality of standard-dose garnet-based-detector CT (high-resolution) was significantly improved. Although highly reduced-dose garnet-based-detector CT (high-resolution mode) provided more image noise, overall image quality was not different between conventional-detector CT and garnet-based-detector CT.

Are there any metastases to the chest in non-muscle-invasive bladder cancer patients on follow-up computed tomography?

PURPOSE: The purpose of the study was to retrospectively determine whether there are metastases to the chest in patients with primary non-muscle-invasive urothelial carcinoma in the bladder on the follow-up computed tomography (CT). METHODS: We analyzed 328 patients with follow-up chest CT for urothelial carcinoma of the bladder diagnosed between January 2004 and September 2013. We divided patients into four groups: Ta (n = 74), T1 (n = 78), carcinoma in situ (CIS, n = 25), and ≥ T2 (n = 151). We used the chest CT to determine whether there were positive findings of metastasis. Univariate and multivariate analyses were achieved using categories of T stage, histological grade, multifocal lesions, and recurrence. RESULTS: On univariate analysis, there were significant differences on T stage (p < 0.001) and histological grade (p = 0.001), and there was no significant difference on multifocal lesions (p = 0.11) and recurrence (p = 0.34). Positive findings of metastases were observed in 1.4% (1/74) of the Ta patients, 0% (0/78) of the T1 patients, 8.0% (2/25) of the patients with carcinoma in situ (CIS), and 27.2% (41/151) of the ≥ T2 patients (p < 0.001). On multivariate analysis, T staging was independent variable for positive findings of metastasis (Odds ratio; 2.84, 95% Confidence Interval; 1.65-4.89). In contrast, histological grade, multifocal lesions, and recurrence were not independent variables. CONCLUSIONS: T stage would affect to metastasis to the chest. It might be appropriate to omit chest CT in patients with Ta or T1 without upstaging in the course of follow-up. We may suggest that the follow-up chest CT in patients with CIS.

Combined lipiodol marking and video-assisted thoracoscopic surgery in a hybrid operating room.

BACKGROUND: The development of diagnostic technology has led to detection of an increasing number of small pulmonary nodules (SPNs), which can be difficult to locate intraoperatively. Here, we report our experience performing single-stage lipiodol localization and surgical resection in a hybrid operating room (OR). METHODS: Between June 2016 and August 2017, 30 patients with 32 SPNs underwent sliding gantry-based multidetector computed tomography (MDCT)-guided lipiodol marking followed by video-assisted thoracoscopic surgery (VATS) in a hybrid OR. After induction of general anesthesia, all nodules were marked with 0.2 mL lipiodol under MDCT fluoroscopic guidance, followed by immediate VATS. RESULTS: The mean SPN diameter and distance from the pleural surface were 10.7±4.5 mm (range, 5.0-21.0 mm) and 18.0±9.0 mm (range, 2.8-32.0 mm) respectively. The MDCT-guided localization procedure required 15.8±6.0 min (range, 8.0-32.0 min). All the nodules were marked with lipiodol and detected during fluoroscopy as a clear spot. The median deviation between the radio-opaque nodule and the target nodule was 7.8±3.6 mm (range, 3.0-20.0 mm). In two cases, MDCT scans performed after completion of marking revealed mild pneumothorax, which did not need further intervention. VATS resection was converted to thoracotomy in two patients because of strong pleural adhesions and intraoperative bleeding from the pulmonary vein. No other complications occurred during the combined approach, and there was no intra- or post-operative mortality or morbidity. CONCLUSIONS: These results suggest that a combined approach using MDCT-guided lipiodol marking followed by VATS is feasible and has acceptable accuracy in resection of SPNs.

Association of Focal Radiation Dose Adjusted on Cross Sections with Subsolid Nodule Visibility and Quantification on Computed Tomography Images Using AIDR 3D: Comparison Among Scanning at 84, 42, and 7 mAs.

RATIONALE AND OBJECTIVES: The objectives of this study were to compare the visibility and quantification of subsolid nodules (SSNs) on computed tomography (CT) using adaptive iterative dose reduction using three-dimensional processing between 7 and 42 mAs and to assess the association of size-specific dose estimate (SSDE) with relative measured value change between 7 and 84 mAs (RMVC7-84) and relative measured value change between 42 and 84 mAs (RMVC42-84). MATERIALS AND METHODS: As a Japanese multicenter research project (Area-detector Computed Tomography for the Investigation of Thoracic Diseases [ACTIve] study), 50 subjects underwent chest CT with 120 kV, 0.35 second per location and three tube currents: 240 mA (84 mAs), 120 mA (42 mAs), and 20 mA (7 mAs). Axial CT images were reconstructed using adaptive iterative dose reduction using three-dimensional processing. SSN visibility was assessed with three grades (1, obscure, to 3, definitely visible) using CT at 84 mAs as reference standard and compared between 7 and 42 mAs using t test. Dimension, mean CT density, and particular SSDE to the nodular center of 71 SSNs and volume of 58 SSNs (diameter >5 mm) were measured. Measured values (MVs) were compared using Wilcoxon signed-rank tests among CTs at three doses. Pearson correlation analyses were performed to assess the association of SSDE with RMVC7-84: 100 × (MV at 7 mAs - MV at 84 mAs)/MV at 84 mAs and RMVC42-84. RESULTS: SSN visibilities were similar between 7 and 42 mAs (2.76 ± 0.45 vs 2.78 ± 0.40) (P = .67). For larger SSNs (>8 mm), MVs were similar among CTs at three doses (P > .05). For smaller SSNs (<8 mm), dimensions and volumes on CT at 7 mAs were larger and the mean CT density was smaller than 42 and 84 mAs, and SSDE had mild negative correlations with RMVC7-84 (P < .05). CONCLUSIONS: Comparable quantification was demonstrated irrespective of doses for larger SSNs. For smaller SSNs, nodular exaggerating effect associated with decreased SSDE on CT at 7 mAs compared to 84 mAs could result in comparable visibilities to CT at 42 mAs.

Electrocardiography-triggered high-resolution CT for reducing cardiac motion artifact: evaluation of the extent of ground-glass attenuation in patients with idiopathic pulmonary fibrosis.

PURPOSE: The aim of this study was to evaluate the decreasing of cardiac motion artifact and whether the extent of ground-glass attenuation of idiopathic pulmonary fibrosis (IPF) was accurately assessed by electrocardiography (ECG)-triggered high-resolution computed tomography (HRCT) by 0.5-s/rotation multidetector-row CT (MDCT). MATERIALS AND METHODS: ECG-triggered HRCT were scanned at the end-diastolic phase by a MDCT scanner with the following scan parameters; axial four-slice mode, 0.5 mm collimation, 0.5-s/rotation, 120 kVp, 200 mA/rotation, high-frequency algorithm, and half reconstruction. In 42 patients with IPF, both conventional HRCT (ECG gating(-), full reconstruction) and ECG-triggered HRCT were performed at the same levels (10-mm intervals) with the above scan parameters. The correlation between percent diffusion of carbon monoxide of the lung (%DLCO) and the mean extent of ground-glass attenuation on both conventional HRCT and ECG-triggered HRCT was evaluated with the Spearman rank correlation coefficient test. RESULTS: The correlation between %DLCO and the mean extent of ground-glass attenuation on ECG-triggered HRCT (observer A: r = -0.790, P < 0.0001; observer B: r = -0.710, P < 0.0001) was superior to that on conventional HRCT (observer A: r = -0.395, P < 0.05; observer B: r = -0.577, P = 0.002) for both observers. CONCLUSION: ECG-triggered HRCT by 0.5 s/rotation MDCT can reduce the cardiac motion artifact and is useful for evaluating the extent of ground-glass attenuation of IPF.

Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system.

OBJECTIVE: To prospectively evaluate the ability of CT urography with a low-dose multi-phasic excretory phase for opacification of the urinary system. MATERIALS AND METHODS: Thirty-two patients underwent CT urography with low-dose multi-phasic s using adaptive iterative dose reduction 3D acquired at 5-, 10-, and 15-minute delays. Opacification scores of the upper urinary tracts and the urinary bladder were assigned for each excretory phase by two radiologists, who recorded whether adequate (>75%) or complete (100%) opacification of the upper urinary tract and urinary bladder was achieved in each patient. Adequate and complete opacification rates of the upper urinary tracts and the urinary bladder were compared among three excretory phases and among combined multi-phasic excretory phases using Cochran's Q test. RESULTS: There was no significant difference among three excretory phases with 5-, 10-, and 15-minute delays in adequate (56.3, 43.8, and 63.5%, respectively; P = 0.174) and complete opacification rates (9.3, 15.6, and 18.7%, respectively; P = 0.417) of the upper urinary tracts. Combined tri-phasic excretory phases significantly improved adequate and complete opacification rates to 84.4% and 43.8%, respectively (P = 0.002). In contrast, there were significant differences among three excretory phases for the rate of adequate (31.3, 84.4, and 93.8%, respectively; P<0.001) and complete opacification (21.9, 53.1, and 81.3%, respectively; P<0.001) of the urinary bladder. Multi-phasic excretory phases did not improve these rates because opacification was always better with a longer delay. CONCLUSION: Although multi-phasic acquisition of excretory phases is effective at improving opacification of the upper urinary tracts, complete opacification is difficult even with tri-phasic acquisition.

Sub-solid Nodule Detection Performance on Reduced-dose Computed Tomography with Iterative Reduction: Comparison Between 20 mA (7 mAs) and 120 mA (42 mAs) Regarding Nodular Size and Characteristics and Association with Size-specific Dose Estimate.

RATIONALE AND OBJECTIVES: This study aimed to compare sub-solid nodule detection performances (SSNDP) on chest computed tomography (CT) with Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR 3D) between 7 mAs (0.21 mSv) and 42 mAs (1.28 mSv) in total and in subgroups classified by nodular size, characteristics, and location, and analyze the association of SSNDP with size-specific dose estimate (SSDE). MATERIALS AND METHODS: As part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases Study, a Japanese multicenter research project, 68 subjects underwent chest CT with 120 kV, 0.35 seconds per rotation, and three tube currents: 240 mA (84 mAs), 120 mA (42 mAs), and 20 mA (7 mAs). The research committee of the study project outlined and approved our study protocols. The institutional review board of each institution approved this study. Axial 2-mm-thick CT images were reconstructed using AIDR 3D. Standard reference was determined by CT images at 84 mAs. Four radiologists recorded SSN presence by continuously distributed rating on CT at 7 mAs and 42 mAs. Receiver operating characteristic analysis was used to evaluate SSNDP at both doses in total and in subgroups classified by nodular longest diameter (LD) (≥5 mm), characteristics (pure and part-solid), and locations (ventral, intermediate, or dorsal; central or peripheral; and upper, middle, or lower). Detection sensitivity was compared among five groups of SSNs classified based on particular SSDE to nodule on CT with AIDR 3D at 7 mAs. RESULTS: Twenty-two part-solid and 86 pure SSNs were identified. For larger SSNs (LD ≥ 5 mm) as well as subgroups classified by nodular locations and part-solid nodules, SSNDP was similar in both methods (area under the receiver operating characteristics curve: 0.96 ± 0.02 in CT at 7 mAs and 0.97 ± 0.01 in CT at 42 mAs), with acceptable interobserver agreements in five locations. For larger SSNs (LD ≥ 5 mm), on CT at 42 mAs, no significant differences in detection sensitivity were found among the five groups classified by SSDE, whereas on CT with 7 mAs, four groups with SSDE of 0.65 or higher were superior in detection sensitivity to the other group, with SSDE less than 0.65 mGy. CONCLUSIONS: For SSNs with 5 mm or more in cases with normal range of body habitus, CT at 7 mAs was demonstrated to have comparable SSNDP to CT at 42 mAs regardless of nodular location and characteristics, and SSDE higher than 0.65 mGy is desirable to obtain sufficient SSNDP.

Solitary pulmonary metastases from renal cell carcinoma: comparison of high-resolution CT with pathological findings.

PURPOSE: The aim of this study was to examine the radiographic features of solitary pulmonary metastases from renal cell carcinoma by comparing high-resolution CT (HRCT) findings with histopathological observations. MATERIALS AND METHODS: Three thoracic radiologists retrospectively reviewed HRCT findings from eight patients who underwent surgery on the basis of the diagnosis of solitary pulmonary metastatic renal cell carcinoma. The histopathological diagnoses for six of these eight lesions were metastases from clear cell carcinoma of the kidney, one case was a metastasis from papillary renal cell carcinoma, and the remaining case was a metastasis from a poorly differentiated carcinoma including predominantly spindle cells, papillary cells, and clear cells. RESULTS: The HRCT findings of all cases of clear cell carcinoma showed solid nodular lesions without ground-glass attenuation (GGA). The HRCT findings for one case of papillary renal cell carcinoma showed a lobulated nodule with a small amount of GGA in an area in the periphery and an air bronchogram. The HRCT findings of the remaining case of poorly differentiated carcinoma showed an ill-defined nodule with a GGA area and pleural indentations. CONCLUSION: In brief, solitary pulmonary metastases from renal cell carcinoma may present as a smoothly marginated nodule, lobulated nodule, or a nodule with peripheral GGA.

Evaluation of the usefulness of color digital summation radiography in temporally sequential digital radiographs: a phantom study.

PURPOSE: The purpose of this study was to assess the usefulness of color digital summation radiography (CDSR) for detection of nodules on chest radiographs by observers with different levels of experience. MATERIALS AND METHODS: A total of 30 radiographs of chest phantoms with abnormalities and 30 normal ones were arranged at random. Set A was conventional radiographs only. Set B consisted of both conventional radiographs and CDSR images, which were colored with magenta. Five chest radiologists and five residents evaluated both image sets on a TFT monitor. The observers were asked to rate each image set using a continuous rating scale. The reading time for each set was also recorded. RESULTS: In set A, the performance of chest radiologists was significantly superior to that of the residents (P < 0.05). However, in set B, there was no significant difference in the performance of the chest radiologists and the residents. In both observer groups, the mean reading time per case in set B was significantly shorter than that in set A (P < 0.01). CONCLUSION: By using CDSR, the detection capability of observers with little experience improves and is comparable to that of experienced observers. Moreover, the reading time becomes much shorter using CDSR.

Detection of bladder cancer: comparison of low-dose scans with AIDR 3D and routine-dose scans with FBP on the excretory phase in CT urography.

OBJECTIVE: To prospectively compare the detection of bladder cancer between low-dose scans with adaptive iterative dose reduction three dimensional projection (AIDR 3D) and routine-dose scans with filtered back projection (FBP) on the excretory phase (EP) in CT urography. METHODS: 42 patients were included. Routine- and low-dose EP were performed in each patient. Routine-dose images were reconstructed with FBP, and low-dose images were reconstructed with AIDR 3D. Two radiologists scored confidence levels for the presence or absence of bladder cancer using a 5-point scale. The CT dose index of each EP was measured, and the dose reduction was calculated. RESULTS: Sensitivity, specificity and accuracy were 86.4%, 95.0% and 90.5% on routine-dose scans and were 86.4%, 90.0% and 88.1% on low-dose scans, respectively. There was no significant difference (p; not significant, 1.00 and 1.00, respectively). The average CT dose index was 8.07 and 2.63 mGy on routine- and low-dose scans, and the ratio of dose reduction was 67.6%. CONCLUSION: The detection of bladder cancer on low-dose scans with AIDR 3D is almost equal to that on routine-dose scans with FBP on the EP, with nearly 70% dose reduction. ADVANCES IN KNOWLEDGE: Using AIDR 3D, the radiation dose may be reduced on the EP in CT urography for the detection of bladder cancer.

Image quality of high-resolution CT with 16-channel multidetector-row CT: comparison between helical scan and conventional step-shoot scan.

OBJECTIVE: The aim of this study was to evaluate the image quality of high-resolution CT (HRCT) reconstructed from volumetric data with 16-channel multidetector-row CT (MDCT). SUBJECTS AND METHODS: Eleven autopsy lungs that were diagnosed histopathologically were scanned by 16-channel MDCT with the step-and-shoot scan mode and three helical scan modes. Each helical mode had each size of focal spot, pitch, and time of gantry rotation. HRCT images were reconstructed from the volumetric data with each helical mode and axial sequence data. Two observers evaluated the image quality and noted the most appropriate diagnosis for each imaging. RESULTS: Visualization of abnormal structures with one helical mode was equal to those with axial mode, whereas those with the other two helical modes were inferior to those with axial mode (Wilcoxon signed rank test; p<0.0001). There was no significant difference in diagnostic efficacy between modes. CONCLUSION: The image quality of HRCT with appropriate helical mode is equal to that with axial mode and diagnostic efficacy is equal among all modes. These results may indicate that sufficient HRCT images can be obtained by only one helical scan without the addition of conventional axial scans.

Voxel dimensions required for micromorphologic evaluation of ground-glass opacity on lung high-resolution CT.

PURPOSE: To clarify the appropriate voxel dimensions required for pathologic evaluation of areas with ground-glass opacity on lung high-resolution computed tomography (HRCT). MATERIALS AND METHODS: Synchrotron radiation CT (SRCT) images of autopsied lung speci-mens (n=25) that showed ground-glass opacity on HRCT were reconstructed with 12 different voxel dimensions ranging from 0.006 to 0.6 mm. The specimens were micromorphologically categorized into one of three pathologic groups: alveolar, interstitial, and mixed abnormalities. Each SRCT image was independently diagnosed as one of three pathologic groups by six chest radiologists. The diagnostic accuracy required to estimate the appropriate voxel dimensions was compared among different voxel dimensions by means of the Tukey test. RESULTS: Diagnostic accuracy with voxel dimensions less than or equal to 0.06 mm was significantly higher than that with voxel dimensions of 0.18 mm or more (p<0.01). There was, however, no significance of difference in diagnostic accuracy with voxel dimensions of less than or equal to 0.06 mm. In addition, no significant difference in diagnostic accuracy was found with voxel dimensions of 0.18 mm or more. CONCLUSION: The appropriate voxel dimensions are approximately 0.06 mm for pathologic differentiation of areas with ground-glass opacity on HRCT.

Lung nodule detection performance in five observers on computed tomography (CT) with adaptive iterative dose reduction using three-dimensional processing (AIDR 3D) in a Japanese multicenter study: Comparison between ultra-low-dose CT and low-dose CT by receiver-operating characteristic analysis.

PURPOSE: To compare lung nodule detection performance (LNDP) in computed tomography (CT) with adaptive iterative dose reduction using three dimensional processing (AIDR3D) between ultra-low dose CT (ULDCT) and low dose CT (LDCT). MATERIALS AND METHODS: This was part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIve) Study, a multicenter research project being conducted in Japan. Institutional Review Board approved this study and informed consent was obtained. Eighty-three subjects (body mass index, 23.3 ± 3.2) underwent chest CT at 6 institutions using identical scanners and protocols. In a single visit, each subject was scanned using different tube currents: 240, 120 and 20 mA (3.52, 1.74 and 0.29 mSv, respectively). Axial CT images with 2-mm thickness/increment were reconstructed using AIDR3D. Standard of reference (SOR) was determined based on CT images at 240 mA by consensus reading of 2 board-certificated radiologists as to the presence of lung nodules with the longest diameter (LD) of more than 3mm. Another 5 radiologists independently assessed and recorded presence/absence of lung nodules and their locations by continuously-distributed rating in CT images at 20 mA (ULDCT) and 120 mA (LDCT). Receiver-operating characteristic (ROC) analysis was used to evaluate LNDP of both methods in total and also in subgroups classified by LD (>4, 6 and 8 mm) and nodular characteristics (solid and ground glass nodules). RESULTS: For SOR, 161 solid and 60 ground glass nodules were identified. No significant difference in LNDP for entire solid nodules was demonstrated between both methods, as area under ROC curve (AUC) was 0.844 ± 0.017 in ULDCT and 0.876 ± 0.026 in LDCT (p=0.057). For ground glass nodules with LD 8mm or more, LNDP was similar between both methods, as AUC 0.899 ± 0.038 in ULDCT and 0.941 ± 0.030 in LDCT. (p=0.144). CONCLUSION: ULDCT using AIDR3D with an equivalent radiation dose to chest x-ray could have comparable LNDP to LDCT with AIDR3D except for smaller ground glass nodules in cases with normal range body habitus.

Coronal multiplanar reconstruction view from isotropic voxel data sets obtained with multidetector-row CT: assessment of detection and size of mediastinal and hilar lymph nodes.

OBJECTIVE: To assess the detection and size of mediastinal and hilar lymph nodes by multiplanar reconstruction (MPR) view from isotropic voxel data sets obtained with multidetector-row computed tomography (MDCT). MATERIALS AND METHODS: Thin-section CT of 27 patients with mediastinal or hilar lymph node swelling was obtained with a 25.6-cm FOV, 512 x 512 matrix, and two protocols: A) 0.5-mm collimation, 0.3-mm interval, and B) 2-mm collimation, 1-mm interval. MPR views with a 0.5-mm slice thickness were obtained from these two data sets. Postcontrast axial CT used 5-mm collimation (set C). Two observers evaluated the presence and cranio-caudal length of swollen lymph nodes. Two other board-certified chest radiologists evaluated all three sets and established a gold standard by consensus. RESULTS: The accuracy of detection was 76%, 73%, and 68% for sets A, B, and C, respectively. There was a significant difference between sets A and C (McNemar's test: p<0.05) but not between sets A and B or B and C (p>0.05). The cranio-caudal length of lymph nodes was significantly correlated with the gold standard only in set A (Pearson's correlation coefficient: r=0.53, p<0.05). CONCLUSION: Non-contrast enhanced coronal MPR views constructed from isotropic voxel data sets may be substituted for axial enhanced CT for the evaluation of mediastinal and hilar lymph nodes.

Coronal multiplanar reconstruction view from whole lung thin-section CT by multidetector-row CT: determination of malignant or benign lesions and differential diagnosis in 68 cases of solitary pulmonary nodule.

PURPOSE: The purpose of this study was to evaluate the usefulness of the coronal multiplanar reconstruction (MPR) view in comparison with transverse helical thin-section CT for both the determination of malignant or benign lesions and the differential diagnosis of solitary pulmonary nodules. MATERIALS AND METHODS: Sixty-eight cases of pathologically proved solitary pulmonary nodule less than 3 cm in diameter were enrolled in this study. For the routine study, transverse helical thin-section CT (1.25 mm collimation, FOV 20 cm) covering the areas with solitary pulmonary nodules as well as whole lung helical thin-section CT (2.5 mm collimation, 1.25 mm reconstruction interval, FOV 34.5 cm, pitch 6:1, high-spatial frequency algorithm) were scanned with a multidetector-row CT (MDCT) scanner. From the whole lung thin-section CT data, coronal MPR views (2.5 mm slice thickness) were reconstructed on a workstation. ROC analysis was used for an observer performance study, in which three observers indicated their confidence level for the determination of malignant or benign lesion for the nodules by means of transverse thin-section CT and coronal MPR. In addition, the observers recorded appropriate disease entities as the final diagnosis of each case. Accuracies of the final diagnosis based on the two sets of images were compared with McNemer' s test. RESULTS: In terms of the determination of malignant or benign lesion, there was no significant difference between the two sets of images (coronal MPR and transverse thin-section CT; mean Az=0.853 and 0.854, respectively). In addition, accuracy of the final diagnosis based on coronal MPR views (74%) was almost equal to that based on transverse thin-section CT (71%) (p=0.3). CONCLUSIONS: The diagnostic efficacy of the coronal MPR view is comparable to that of transverse thin-section CT for the evaluation of solitary pulmonary nodules.

Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D) improves chest CT image quality and reduces radiation exposure.

OBJECTIVE: To assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) for image quality improvement and dose reduction for chest computed tomography (CT). METHODS: Institutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D). Using a 5-point scale from 1 (non-diagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease), and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts). Differences in these scores were assessed by Scheffe's test. RESULTS: At each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001) and all mediastinal measurements (p<0.01). For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001), and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA. CONCLUSION: For chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%.

Pulmonary nodules: effect of adaptive statistical iterative reconstruction (ASIR) technique on performance of a computer-aided detection (CAD) system-comparison of performance between different-dose CT scans.

PURPOSE: To evaluate the effects of ASIR on CAD system of pulmonary nodules using clinical routine-dose CT and lower-dose CT. MATERIALS AND METHODS: Thirty-five patients (body mass index, 22.17 ± 4.37 kg/m(2)) were scanned by multidetector-row CT with tube currents (clinical routine-dose CT, automatically adjusted mA; lower-dose CT, 10 mA) and X-ray voltage (120 kVp). Each 0.625-mm-thick image was reconstructed at 0%-, 50%-, and 100%-ASIR: 0%-ASIR is reconstructed using only the filtered back-projection algorithm (FBP), while 100%-ASIR is reconstructed using the maximum ASIR and 50%-ASIR implies a blending of 50% FBP and ASIR. CAD output was compared retrospectively with the results of the reference standard which was established using a consensus panel of three radiologists. Data were analyzed using Bonferroni/Dunn's method. Radiation dose was calculated by multiplying dose-length product by conversion coefficient of 0.021. RESULTS: The consensus panel found 265 non-calcified nodules ≤ 30 mm (ground-glass opacity [GGO], 103; part-solid, 34; and solid, 128). CAD sensitivity was significantly higher at 100%-ASIR [clinical routine-dose CT, 71% (overall), 49% (GGO); lower-dose CT, 52% (overall), 67% (solid)] than at 0%-ASIR [clinical routine-dose CT, 54% (overall), 25% (GGO); lower-dose CT, 36% (overall), 50% (solid)] (p<0.001). Mean number of false-positive findings per examination was significantly higher at 100%-ASIR (clinical routine-dose CT, 8.5; lower-dose CT, 6.2) than at 0%-ASIR (clinical routine-dose CT, 4.6; lower-dose CT, 3.5; p<0.001). Effective doses were 10.77 ± 3.41 mSv in clinical routine-dose CT and 2.67 ± 0.17 mSv in lower-dose CT. CONCLUSION: CAD sensitivity at 100%-ASIR on lower-dose CT is almost equal to that at 0%-ASIR on clinical routine-dose CT. ASIR can increase CAD sensitivity despite increased false-positive findings.