Serial Texture Analyses on ADC Maps for Evaluation of Antiangiogenic Therapy in Rat Breast Cancer.

BACKGROUND/AIM: We investigated the correlation between texture features on apparent diffusion coefficient (ADC) maps and histological vascular parameters of FN13762 rat breast cancers after antiangiogenic therapy. MATERIALS AND METHODS: FN13762 cancer cells were implanted into 30 rats, and bevacizumab was intraperitoneally administered to 15 (treated group). For each rat, magnetic resonance imaging (MRI) was obtained at five time points after baseline examination. Serial texture analyses were performed on ADC maps and extracted texture parameters were correlated with histological vascular parameters. RESULTS: Entropy of the ADC values correlated with microvessel density in the treated group (r=0.493, p=0.06). Hypoxia inducible factor-1 alpha showed the highest correlation coefficient with the 5th percentile ADC value (r=0.844, p<0.001). Vascular endothelial growth factor was significantly correlated with homogeneity on ADC map (r=-0.521, p=0.046). In the control group, no texture features showed significant correlations with histological vascular parameters. CONCLUSION: ADC map texture features may reflect histological vascular changes after antiangiogenic therapy.

Single-Dose Gadoterate Meglumine for 3T Late Gadolinium Enhancement MRI for the Assessment of Chronic Myocardial Infarction: Intra-Individual Comparison with Conventional Double-Dose 1.5T MRI.

Objective: To intra-individually compare 3T magnetic resonance (MR) images obtained with one dose gadoterate meglumine to 1.5T MR using conventional double dose for assessment of chronic myocardial infarction. Materials and Methods: Sixteen patients diagnosed with chronic myocardial infarctions were examined on single-dose 3T MR within two weeks after undergoing double-dose 1.5T MR. Representative short-axis images were acquired at three points after administration of gadoterate meglumine. Contrast-to-noise ratios between infarcted and normal myocardium (CNRinfarct-normal) and between infarct and left ventricular cavity (CNRinfarct-LVC) were calculated and compared intra-individually at each temporal scan. Additionally, two independent readers assessed relative infarct size semi-automatically and inter-observer reproducibility was evaluated using intraclass correlation coefficient. Results: While higher CNRinfarct-normal was revealed at single-dose 3T at only 10 minutes scan (p = 0.047), the CNRinfarct-LVC was higher at single-dose 3T MR at each temporal scan (all, p < 0.05). Measurement of relative infarct size was not significantly different between both examinations for both observers (all, p > 0.05). However, inter-observer reproducibility was higher at single-dose 3T MR (all, p < 0.05). Conclusion: Single-dose 3T MR is as effective as double-dose 1.5T MR for delineation of infarcted myocardium while being superior in detection of infarcted myocardium from the blood cavity, and provides better reproducibility for infarct size quantification.

Incidentally detected atherosclerosis in the abdominal aorta or its major branches on computed tomography is highly associated with coronary heart disease in asymptomatic adults.

BACKGROUND: Atherosclerotic lesions in the abdominal aorta or its major branches are often incidentally detected on abdominal CT. However, clinical implications and optimal subsequent management are mostly left undetermined. METHODS: Consecutive, asymptomatic adults (age≥30) who underwent both abdominal CT and coronary computed tomography angiography as part of a self-referred health check-up were investigated (n = 1494). RESULTS: Adjusted for cardiovascular risk factors, abdominal atherosclerotic lesions with stenosis<25% were associated with significant coronary stenosis, especially in the abdominal aorta (adjusted odds ratio [aOR] 3.37, 95% confidence interval [CI] 0.99-11.45) and any common iliac artery (aOR 2.99, 95% CI 1.43-6.26). The association was higher in atherosclerotic lesions with stenosis≥25%, respectively (aOR 16.39, 95% CI 4.00-67.11; aOR 7.32, 95% CI 2.84-18.86). Furthermore, any major abdominal artery stenosis added predictive value to significant coronary stenosis (area under the receiver operating curve: 0.7598 vs. 0.8019, P < 0.001). The extent of arterial territory involvement was associated with the presence of significant coronary stenoses (P for trend <0.001). CONCLUSION: Stenotic atherosclerotic lesions in the abdominal aorta or its major branches incidentally detected on abdominal CT are relatively prevalent and carry high risk for asymptomatic coronary arterial disease.

CT assessment-based direct surgical resection of part-solid nodules with solid component larger than 5 mm without preoperative biopsy: experience at a single tertiary hospital.

OBJECTIVES: To retrospectively evaluate the feasibility of CT assessment-based direct surgical resection of part-solid nodules (PSNs) with solid components > 5 mm without preoperative percutaneous transthoracic needle biopsies (PTNBs). METHODS: From January 2009-December 2014, 85 PSNs with solid components > 5 mm on CT were included. Preoperative PTNBs were performed for 41 PSNs (biopsy group) and CT assessment-based direct resections were performed for 44 PSNs (direct surgery group). Diagnostic accuracy and complication rates of the groups were compared. RESULTS: Pathological results of 83 PSNs excluding two indeterminate nodules included 76 adenocarcinomas (91.6%), two adenocarcinomas in situ (2.4%) and five benign lesions (6.0%). In the biopsy group, the overall sensitivity, specificity and accuracy for the diagnosis of adenocarcinoma were 78.9% (30/38), 100% (1/1) and 79.5% (31/39), respectively. Pneumothorax and haemoptysis occurred in 11 procedures (26.8%). In the direct surgery group, the respective values for the diagnosis of adenocarcinoma were 100% (38/38), 0% (0/6) and 86.4% (38/44), respectively. Seven pneumothoraces (15.9%); no haemoptysis occurred during localization procedures. There were no significant differences in diagnostic accuracy (P = 0.559) between the two groups. CONCLUSIONS: CT assessment-based direct resection can be reasonable for PSNs with solid part > 5 mm. KEY POINTS: • 91.6% of PSNs with solid component > 5 mm were adenocarcinomas. • PTNBs for PSNs with solid component > 5 mm had 79.5% accuracy. • CT-based resection for PSNs with solid component > 5 mm had 86.4% accuracy. • CT-based resection without biopsy can be a reasonable option in routine practice.

Impact of Reconstruction Algorithms on CT Radiomic Features of Pulmonary Tumors: Analysis of Intra- and Inter-Reader Variability and Inter-Reconstruction Algorithm Variability.

PURPOSE: To identify the impact of reconstruction algorithms on CT radiomic features of pulmonary tumors and to reveal and compare the intra- and inter-reader and inter-reconstruction algorithm variability of each feature. METHODS: Forty-two patients (M:F = 19:23; mean age, 60.43±10.56 years) with 42 pulmonary tumors (22.56±8.51mm) underwent contrast-enhanced CT scans, which were reconstructed with filtered back projection and commercial iterative reconstruction algorithm (level 3 and 5). Two readers independently segmented the whole tumor volume. Fifteen radiomic features were extracted and compared among reconstruction algorithms. Intra- and inter-reader variability and inter-reconstruction algorithm variability were calculated using coefficients of variation (CVs) and then compared. RESULTS: Among the 15 features, 5 first-order tumor intensity features and 4 gray level co-occurrence matrix (GLCM)-based features showed significant differences (p<0.05) among reconstruction algorithms. As for the variability, effective diameter, sphericity, entropy, and GLCM entropy were the most robust features (CV≤5%). Inter-reader variability was larger than intra-reader or inter-reconstruction algorithm variability in 9 features. However, for entropy, homogeneity, and 4 GLCM-based features, inter-reconstruction algorithm variability was significantly greater than inter-reader variability (p<0.013). CONCLUSIONS: Most of the radiomic features were significantly affected by the reconstruction algorithms. Inter-reconstruction algorithm variability was greater than inter-reader variability for entropy, homogeneity, and GLCM-based features.

Temporal Changes of Texture Features Extracted From Pulmonary Nodules on Dynamic Contrast-Enhanced Chest Computed Tomography: How Influential Is the Scan Delay?

OBJECTIVES: The aim of this study was to describe the temporal changes of various texture features extracted from pulmonary nodules on dynamic contrast-enhanced computed tomography (DCE-CT) and to compare the feature values among multiple scanning time points. We also aimed to analyze the variability of texture features across multiple scan delay times. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board of Seoul National University Hospital with waiver of patients' informed consent. Twenty patients (M:F, 6:14; mean age, 60.25 ± 11.97 years) with 20 lung nodules (mean size, 24.1 ± 12.3 mm) underwent DCE-CT with multiple scan delays (30, 60, 90, 120, 150, 180, 210, 240, 300, and 480 seconds) after precontrast scans. Lung nodule segmentation and texture feature extraction were performed at each time point using in-house software. Texture feature values were compared among the multiple time points using the Friedman test with post hoc pairwise Wilcoxon signed rank test. In addition, the dynamic range (DR) reflecting the variability between 2 time points to the interpatient range was calculated. Thereafter, we determined the stable time range that met both "DR greater than 0.90" and "no statistically significant difference" between all time point pairs for each feature. The degree of variability across all scan delay times was obtained using coefficients of variation. RESULTS: Standard deviation, variance, entropy, sphericity, discrete compactness, gray-level cooccurrence matrix (GLCM) inverse difference moment (IDM), GLCM contrast, and GLCM entropy did not show significant differences between scan delays of 30 and 180 seconds with DR greater than 0.90 between all time point pairs. When the range was narrowed down to 60 to 150 seconds, an additional 2 values (mean and homogeneity) showed stability. Among the 13 texture features, entropy, sphericity, discrete compactness, and GLCM entropy exhibited the lowest variability (coefficient of variation ≤5%). CONCLUSIONS: Most texture features exhibited stability with low variation between 60 and 150 seconds on DCE-CT. Thus, texture features extracted from contrast-enhanced CT with a scan delay range of 60 to 150 seconds can be used for tumor characterization despite the heterogeneity in delay time.

Ultrasonographic Differentiation Between Nodular Hyperplasia and Neoplastic Follicular-Patterned Lesions of the Thyroid Gland.

We evaluate the gray-scale ultrasonographic characteristics that differentiate between nodular hyperplasia (NH) and neoplastic follicular-patterned lesions (NFPLs) of the thyroid gland. Ultrasonographic features of 750 patients with 832 thyroid nodules (NH, n = 361; or NFPLs, follicular adenoma, n = 123; follicular carcinoma, n = 159; and follicular variant papillary carcinoma, n = 189) were analyzed. Except for echogenicity, over two-thirds of the cases of NH and NFPLs share the ultrasonographic characteristics of solid internal content, a well-defined smooth margin and round-to-ovoid shape. Independent predictors for NH were non-solid internal content (sensitivity 27.1%, specificity 90.2%), isoechogenicity (sensitivity 69.5%, specificity 63.5%) and an ill-defined margin (sensitivity 18.8%, specificity 94.5%). Independent predictors for NFPLs were hypoechogenicity (sensitivity 60.5%, specificity 70.4%), marked hypoechogenicity (sensitivity 2.8%, specificity 99.4%) and taller-than-wide shape (sensitivity 6.6%, specificity 98.1%). Although NH and NFPLs commonly share ultrasonographic characteristics, non-solid internal content and ill-defined margin are specific to NH and marked hypoechogenicity and taller-than-wide shape are specific to NFPLs.

Measurement Variability of Persistent Pulmonary Subsolid Nodules on Same-Day Repeat CT: What Is the Threshold to Determine True Nodule Growth during Follow-Up?

PURPOSE: To assess the measurement variability of subsolid nodules (SSNs) in follow-up situations and to compare the degree of variability between measurement metrics. METHODS: Two same-day repeat-CT scans of 69 patients (24 men and 45 women) with 69 SSNs were randomly assigned as initial or follow-up scans and were read by the same (situation 1) or different readers (situation 2). SSN size and solid portion size were measured in both situations. Measurement variability was calculated and coefficients of variation were used for comparisons. RESULTS: Measurement variability for the longest and average diameter of SSNs was ±1.3 mm (±13.0%) and ±1.3 mm (±14.4%) in situation 1, and ±2.2 mm (±21.0%) and ±2.1 mm (±21.3%) in situation 2, respectively. For solid portion, measurement variability on lung and mediastinal windows was ±1.2 mm (±27.1%) and ±0.8 mm (±24.0%) in situation 1, and ±3.7 mm (±61.0%) and ±1.5 mm (±47.3%) in situation 2, respectively. There were no significant differences in the degree of variability between the longest and average diameters and between the lung and mediastinal window settings (p>0.05). However, measurement variability significantly increased when the follow-up and initial CT readers were different (p<0.001). CONCLUSIONS: A cutoff of ±2.2 mm can be reliably used to determine true nodule growth on follow-up CT. Solid portion measurements were not reliable in evaluating SSNs' change when readers of initial and follow-up CT were different.

Added Value of Integrated Whole-Body PET/MRI for Evaluation of Colorectal Cancer: Comparison With Contrast-Enhanced MDCT.

OBJECTIVE: The purpose of this study was to evaluate the added clinical value of PET/MRI compared with conventional contrast-enhanced MDCT (CECT) alone in the evaluation of patients with colorectal cancer. MATERIALS AND METHODS: The study population comprised 51 patients with colorectal cancer who underwent (18)F-FDG PET/MRI and CECT within a 90-day interval between October 2012 and August 2013. Two reviewers in consensus evaluated whether PET/MRI added value to CECT for lesion detection and characterization and assessed whether changes in treatment strategies were made. The malignancy probability of each lesion was assessed on a 5-point scale. ROC analyses were performed with histopathologic findings, imaging, and clinical follow-up as the reference standards. Two reviewers evaluated the presence or absence of pulmonary metastatic nodules on PET/MR images that had been detected on chest CT scans. RESULTS: PET/MRI added value to CECT for 14 of 51 patients (27.5%) in terms of better characterization (12/51 [23.5%]) and additional detection (2/51 [3.9%]) of extracolonic lesions. The additional information from PET/MRI led to a change in treatment strategy for 11 of 51 (21.6%) patients. ROC analyses showed that PET/MRI was significantly superior to CT in depicting colorectal cancer (p < 0.05). The rate of detection of pulmonary metastatic nodules with PET/MRI was 52.9% (9/17). CONCLUSION: Integrated whole-body PET/MRI added value to CECT in the detection of metastatic lesions and characterization of indeterminate lesions, albeit with limited performance for small pulmonary metastatic nodules. The results suggest that PET/MRI may aid in the selection of more appropriate treatment strategies for patients with colorectal cancer.

Digital tomosynthesis for evaluating metastatic lung nodules: nodule visibility, learning curves, and reading times.

OBJECTIVE: To evaluate nodule visibility, learning curves, and reading times for digital tomosynthesis (DT). MATERIALS AND METHODS: We included 80 patients who underwent computed tomography (CT) and DT before pulmonary metastasectomy. One experienced chest radiologist annotated all visible nodules on thin-section CT scans using computer-aided detection software. Two radiologists used CT as the reference standard and retrospectively graded the visibility of nodules on DT. Nodule detection performance was evaluated in four sessions of 20 cases each by six readers. After each session, readers were unblinded to the DT images by revealing the true-positive markings and were instructed to self-analyze their own misreads. Receiver-operating-characteristic curves were determined. RESULTS: Among 414 nodules on CT, 53.3% (221/414) were visible on DT. The main reason for not seeing a nodule on DT was small size (93.3%, ≤ 5 mm). DT revealed a substantial number of malignant nodules (84.1%, 143/170). The proportion of malignant nodules among visible nodules on DT was significantly higher (64.7%, 143/221) than that on CT (41.1%, 170/414) (p < 0.001). Area under the curve (AUC) values at the initial session were > 0.8, and the average detection rate for malignant nodules was 85% (210/246). The inter-session analysis of the AUC showed no significant differences among the readers, and the detection rate for malignant nodules did not differ across sessions. A slight improvement in reading times was observed. CONCLUSION: Most malignant nodules > 5 mm were visible on DT. As nodule detection performance was high from the initial session, DT may be readily applicable for radiology residents and board-certified radiologists.

Transient subsolid nodules in patients with extrapulmonary malignancies: their frequency and differential features.

BACKGROUND: For pulmonary subsolid nodules (SSNs) in patients with extrapulmonary malignancies, it is still unclear what proportion of SSNs is transient and how we can more accurately diagnose these transient SSNs. PURPOSE: To investigate the frequency of transient SSNs and their differentiating clinical and thin-section computed tomography (CT) features in patients with extrapulmonary malignancies. MATERIAL AND METHODS: From January 2005 to February 2012, 78 SSNs in 63 individuals (30 men and 33 women; mean age, 55.1 years ± 15.5) with extrapulmonary malignancies were identified. Their clinical and thin-section CT characteristics were reviewed and compared between transient and persistent SSNs. Differentiating factors and their performance were also measured. RESULTS: Thirty-six of the 78 SSNs (46.2%) were transient. Between transient and persistent SSNs, there were significant differences in patients' age, sex, detection mode, and the presence of eosinophilia, lesion multiplicity, lesion margin, and pleural retraction (P < 0.05). Multivariate analysis revealed that follow-up detected SSNs (adjusted odds ratio [OR], 38.88), multiple lesions (OR, 7.64), and an ill-defined nodular margin (OR, 11.93) were significant discriminators of transient SSNs (P < 0.05). Discrimination of transient SSNs was significantly better upon incorporating both clinical and thin-section CT features than using clinical features alone (P < 0.05). CONCLUSION: Approximately half of the SSNs detected in patients with extrapulmonary malignancies were transient. Transient SSNs in these patients can be very accurately differentiated using their thin-section CT and clinical features.

Volume and mass doubling times of persistent pulmonary subsolid nodules detected in patients without known malignancy.

PURPOSE: To evaluate volume doubling time (VDT) and mass doubling time (MDT) of persistent pulmonary subsolid nodules (SSNs) followed-up with low-dose (LD) computed tomography (CT) in patients without a history of malignancy. MATERIALS AND METHODS: This retrospective institutional review board-approved study, with waiver of patient informed consent, included 97 SSNs in 97 patients (45 men, 52 women; median age, 58 years; range, 37-87 years) in whom at least two LD CT scans were obtained, with 3-month or longer follow-up interval and median follow-up of 633 days. SSNs were categorized into pure ground-glass nodules (GGNs) (group A), part-solid GGNs with solid components of 5 mm or smaller (group B), and part-solid GGNs with solid components larger than 5 mm (group C). Three-dimensional manual segmentation for all SSNs was performed on initial and latest follow-up LD CT scans; subsequently, VDTs and MDTs were calculated and were compared among groups by using Kruskal-Wallis test, followed by the Dunn procedure with Bonferroni correction for volume-growing SSNs and mass-growing SSNs. RESULTS: Volume growth was thus: 12 of 63 SSNs (19%), group A; nine of 23 SSNs (39%), group B; and eight of 11 SSNs (73%), group C. Median VDT was thus: 1832.3 days (range, 1230.7-4537.3 days), group A; 1228.5 days (range, 934.7-4617.7 days), group B; and 759.0 days (range, 376.4-941.5 days), group C. Mass growth was thus: 17 of 63 SSNs (27%), group A; 11 of 23 SSNs (48%), group B; and nine of 11 SSNs (82%), group C. Median MDT was 1556.1 days (range, 642.5-3564.5 days) for group A, 1199.9 days (range, 838.6-2578.7 days) for group B, and 627.7 days (range, 340.0-921.2 days) for group C. Median VDTs and MDTs of groups A and B were significantly longer than those of group C (P < .01). CONCLUSION: Pure GGNs and part-solid GGNs with solid components of 5 mm or smaller show significantly longer VDTs and MDTs than do part-solid GGNs with solid components larger than 5 mm. Online supplemental material is available for this article.

Reproducibility of histogram and texture parameters derived from intravoxel incoherent motion diffusion-weighted MRI of FN13762 rat breast Carcinomas.

AIM: To determine the reproducibility of histogram and texture parameters derived from intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (MRI) of FN13762 rat breast carcinomas. MATERIALS AND METHODS: IVIM diffusion-weighted MRI was performed twice, nine days after tumor implantation in 11 rats. At each session, histogram and texture parameters of entire tumors were extracted from apparent diffusion coefficient (ADC), true-diffusion coefficient (Dt), pseudo-diffusion coefficient (Dp), and perfusion fraction (Pf) maps. Intraobserver and interscan measurement reproducibilities were evaluated using intraclass correlation coefficients (ICC). RESULTS: Mean, entropy, 5th, 10th, 25th percentiles from ADC and Dt maps revealed good intra-observer and interscan agreements [lower limits of 95% confidence interval (CI) for ICC≥0.75]. However, all parameters from Dp and Pf maps gave relatively poor intra-observer and interscan agreements (lower limits of 95% CI for ICC<0.75). CONCLUSION: Histogram and texture parameters derived from ADC and Dt maps were more reproducible than those from Dp and Pf maps.

Influence of radiation dose and iterative reconstruction algorithms for measurement accuracy and reproducibility of pulmonary nodule volumetry: A phantom study.

PURPOSE: To evaluate the influence of radiation dose settings and reconstruction algorithms on the measurement accuracy and reproducibility of semi-automated pulmonary nodule volumetry. MATERIALS AND METHODS: CT scans were performed on a chest phantom containing various nodules (10 and 12mm; +100, -630 and -800HU) at 120kVp with tube current-time settings of 10, 20, 50, and 100mAs. Each CT was reconstructed using filtered back projection (FBP), iDose(4) and iterative model reconstruction (IMR). Semi-automated volumetry was performed by two radiologists using commercial volumetry software for nodules at each CT dataset. Noise, contrast-to-noise ratio and signal-to-noise ratio of CT images were also obtained. The absolute percentage measurement errors and differences were then calculated for volume and mass. The influence of radiation dose and reconstruction algorithm on measurement accuracy, reproducibility and objective image quality metrics was analyzed using generalized estimating equations. RESULTS: Measurement accuracy and reproducibility of nodule volume and mass were not significantly associated with CT radiation dose settings or reconstruction algorithms (p>0.05). Objective image quality metrics of CT images were superior in IMR than in FBP or iDose(4) at all radiation dose settings (p<0.05). CONCLUSION: Semi-automated nodule volumetry can be applied to low- or ultralow-dose chest CT with usage of a novel iterative reconstruction algorithm without losing measurement accuracy and reproducibility.

Computed tomography guided percutaneous injection of a mixture of lipiodol and methylene blue in rabbit lungs: evaluation of localization ability for video-assisted thoracoscopic surgery.

Preoperative localization is necessary prior to video assisted thoracoscopic surgery for the detection of small or deeply located lung nodules. We compared the localization ability of a mixture of lipiodol and methylene blue (MLM) (0.6 mL, 1:5) to methylene blue (0.5 mL) in rabbit lungs. CT-guided percutaneous injections were performed in 21 subjects with MLM and methylene blue. We measured the extent of staining on freshly excised lung and evaluated the subjective localization ability with 4 point scales at 6 and 24 hr after injections. For MLM, radio-opacity was evaluated on the fluoroscopy. We considered score 2 (acceptable) or 3 (excellent) as appropriate for localization. The staining extent of MLM was significantly smaller than methylene blue (0.6 vs 1.0 cm, P<0.001). MLM showed superior staining ability over methylene blue (2.8 vs 2.2, P=0.010). Excellent staining was achieved in 17 subjects (81%) with MLM and 8 (38%) with methylene blue (P=0.011). An acceptable or excellent radio-opacity of MLM was found in 13 subjects (62%). An appropriate localization rate of MLM was 100% with the use of the directly visible ability and radio-opacity of MLM. MLM provides a superior pulmonary localization ability over methylene blue.

Grading of cerebral glioma with multiparametric MR imaging and 18F-FDG-PET: concordance and accuracy.

OBJECTIVES: To retrospectively evaluate concordance rates and predictive values in concordant cases among multiparametric MR techniques and FDG-PET to grade cerebral gliomas. METHODS: Multiparametric MR imaging and FDG-PET were performed in 60 consecutive patients with cerebral gliomas (12 low-grade and 48 high-grade gliomas). As the dichotomic variables, conventional MRI, minimum apparent diffusion coefficient in diffusion-weighted imaging, maximum relative cerebral blood volume ratio in perfusion-weighted imaging, choline/creatine ratio and (lipid and lactate)/creatine ratio in MR spectroscopy, and maximum standardised uptake value ratio in FDG-PET in low- and high-grade gliomas were compared. Their concordance rates and positive/negative predictive values (PPV/NPV) in concordant cases were obtained for the various combinations of multiparametric MR techniques and FDG-PET. RESULTS: There were significant differences between low- and high-grade gliomas in all techniques. Combinations of two, three, four, and five out of the five techniques showed concordance rates of 77.0 ± 4.8%, 65.5 ± 4.0%, 58.3 ± 2.6% and 53.3%, PPV in high-grade concordant cases of 97.3 ± 1.7%, 99.1 ± 1.4%, 100.0 ± 0% and 100.0% and NPV in low-grade concordant cases of 70.2 ± 7.5%, 78.0 ± 6.0%, 80.3 ± 3.4% and 80.0%, respectively. CONCLUSION: Multiparametric MR techniques and FDG-PET have a concordant tendency in a two-tiered classification for the grading of cerebral glioma. If at least two examinations concordantly indicated high-grade gliomas, the PPV was about 95%. KEY POINTS: • Modern imaging techniques can help predict the aggressiveness of cerebral gliomas. • Multiparametric MRI and FDG-PET have a concordant tendency to grade cerebral gliomas. • Their high-grade concordant cases revealed at least 95 % positive predictive values. • Their low-grade concordant cases revealed about 70­80% negative predictive values.

Rat model of hindlimb ischemia induced via embolization with polyvinyl alcohol and N-butyl cyanoacrylate.

OBJECTIVE: To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). MATERIALS AND METHODS: Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. RESULTS: There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). CONCLUSION: The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model.

True progression versus pseudoprogression in the treatment of glioblastomas: a comparison study of normalized cerebral blood volume and apparent diffusion coefficient by histogram analysis.

OBJECTIVE: The purpose of this study was to differentiate true progression from pseudoprogression of glioblastomas treated with concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ) by using histogram analysis of apparent diffusion coefficient (ADC) and normalized cerebral blood volume (nCBV) maps. MATERIALS AND METHODS: Twenty patients with histopathologically proven glioblastoma who had received CCRT with TMZ underwent perfusion-weighted imaging and diffusion-weighted imaging (b = 0, 1000 sec/mm(2)). The corresponding nCBV and ADC maps for the newly visible, entirely enhancing lesions were calculated after the completion of CCRT with TMZ. Two observers independently measured the histogram parameters of the nCBV and ADC maps. The histogram parameters between the true progression group (n = 10) and the pseudoprogression group (n = 10) were compared by use of an unpaired Student's t test and subsequent multivariable stepwise logistic regression analysis to determine the best predictors for the differential diagnosis between the two groups. Receiver operating characteristic analysis was employed to determine the best cutoff values for the histogram parameters that proved to be significant predictors for differentiating true progression from pseudoprogression. Intraclass correlation coefficient was used to determine the level of inter-observer reliability for the histogram parameters. RESULTS: The 5th percentile value (C5) of the cumulative ADC histograms was a significant predictor for the differential diagnosis between true progression and pseudoprogression (p = 0.044 for observer 1; p = 0.011 for observer 2). Optimal cutoff values of 892 × 10(-6) mm(2)/sec for observer 1 and 907 × 10(-6) mm(2)/sec for observer 2 could help differentiate between the two groups with a sensitivity of 90% and 80%, respectively, a specificity of 90% and 80%, respectively, and an area under the curve of 0.880 and 0.840, respectively. There was no other significant differentiating parameter on the nCBV histograms. Inter-observer reliability was excellent or good for all histogram parameters (intraclass correlation coefficient range: 0.70-0.99). CONCLUSION: The C5 of the cumulative ADC histogram can be a promising parameter for the differentiation of true progression from pseudoprogression of newly visible, entirely enhancing lesions after CCRT with TMZ for glioblastomas.

Does antiplatelet therapy increase the risk of hemoptysis during percutaneous transthoracic needle biopsy of a pulmonary lesion?

OBJECTIVE: The purpose of this article is to evaluate whether antiplatelet therapy increases the occurrence and severity of percutaneous transthoracic needle biopsy (PTNB)-related hemoptysis. MATERIALS AND METHODS: Our institutional review board approved this retrospective study, with waiver of informed consent. From May 2007 to December 2009, 1251 patients undergoing 1346 PTNBs constituted our study population. Of these PTNBs, 163 were performed in patients who had suspended antiplatelet therapy for less than 10 days (mean discontinuation time, 2.56 ± 2.35 days), and these patients were classified as antiplatelet agent users: 143 patients with single aspirin (mean discontinuation time, 2.55 ± 2.35 days), 12 patients with single clopidogrel (mean discontinuation time, 2.33 ± 2.10 days), and eight patients with dual-antiplatelet therapy (i.e., aspirin plus clopidogrel; mean discontinuation time, 3.12 ± 2.90 days). The influence of antiplatelet therapy on the occurrence and severity of PTNB-related hemoptysis was retrospectively evaluated. RESULTS: Among 1346 PTNBs, there were 128 cases (9.5%) of hemoptysis, including 21 cases of severe hemoptysis (1.6%). Multivariate analysis revealed that dual-antiplatelet therapy (odds ratio [OR], 10.09), female sex (OR, 1.88), smaller lesions (OR, 0.88), deeply located lesions (OR, 1.17), and the use of cutting needles (OR, 3.22) were independent risk factors for overall hemoptysis. For severe hemoptysis, dual-antiplatelet therapy (OR, 13.02), ground-glass nodules (OR, 8.86), and deeply located lesions (OR, 1.24) were proven to be independent risk factors. Single-antiplatelet therapy suspended for less than 10 days was not a significant risk factor for either overall or severe hemoptysis. CONCLUSION: Single-antiplatelet therapy suspended for less than 10 days is not an independent risk factor for the occurrence of PTNB-related hemoptysis, whereas dual-antiplatelet therapy increases its risk.

Ocular adnexal IgG4-related disease: CT and MRI findings.

BACKGROUND/AIMS: To evaluate CT and MRI findings of histopathologically proven ocular adnexa IgG4-related disease. METHODS: Study subjects included 18 patients with histopathologically proven ocular adnexal IgG4-related disease. CT (n=16) and MR (n=3) images were retrospectively evaluated for location, laterality, shape, margin, attenuation on precontrast CT images, T1 and T2 signal intensity on precontrast MRI , internal architecture, ocular adnexal lesion enhancement patterns, sialadenitis of major salivary glands, cervical lymph node enlargement and perilesional bony change. RESULTS: Lacrimal gland enlargement was observed in 16 cases. Extraglandular lesions were observed in the medial canthus (n=2) and extraconal space (n=2). Bilateral supraorbital and infraorbital nerves, pterygopalatine fossa and cavernous sinus involvement were observed in one case. All ocular adnexal lesions showed well defined margins, isoattenuation on precontrast CT images, isointensity on T1- and hypointensity on T2-weighted images, homogenous internal arcithecture and enhancement patterns and bone remodelling without destruction. CONCLUSIONS: Ocular adnexal IgG4-related disease can involve the lacrimal gland, medial canthus, extraconal space, supraorbital and infraorbital nerves, pterygopalatine fossa and cavernous sinus. A diagnosis of ocular adnexal IgG4-related disease should be considered in lesions with the typical imaging features described herein.