Satoshi Kawanami

Detection of non-palpable breast cancer in asymptomatic women by using unenhanced diffusion-weighted and T2-weighted MR imaging: comparison with mammography and dynamic contrast-enhanced MR imaging

ObjectiveTo compare the detectability of non-palpable breast cancer in asymptomatic women by using mammography (MMG), dynamic contrast-enhanced MR imaging (DCE-MRI) and unenhanced MR imaging with combined diffusion-weighted and T2-weighted images (DWI + T2WI).MethodsForty-two lesions in 42 patients with non-palpable breast cancer in asymptomatic women were enrolled. For the reading test, we prepared a control including 13 normal and 8 benign cases. Each imaging set included biplane MMG, DCE-MRI and DWI + T2WI. Five readers were asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of cancer and the BI-RADS category. Confidence level results were used to construct receiver operating characteristic analysis. Sensitivity and specificity were calculated for each technique.ResultsDWI + T2WI showed higher observer performances (area under the curve, AUC, 0.73) and sensitivity (50%) for the detection of non-palpable breast cancer than MMG alone (AUC 0.64; sensitivity 40%) but lower than those of DCE-MRI (AUC 0.93; sensitivity 86%). A combination of MMG and DWI + T2WI exhibited higher sensitivity (69%) compared with that of MMG alone (40%).ConclusionDWI + T2WI could be useful in screening breast cancer for patients who cannot receive contrast medium and could be used as a new screening technique for breast cancer.

Frequency and significance of pulmonary nodules on thin-section CT in patients with extrapulmonary malignant neoplasms

PURPOSE To determine the frequency and significance of pulmonary nodules detected on thin-section CT in patients with extrapulmonary malignant neoplasms. MATERIALS AND METHODS The institutional review board approved this study. This study retrospectively evaluated 308 patients with extrapulmonary carcinomas or sarcomas and had undergone thin-section chest CT (2mm slice thickness) for staging. Three radiologists identified non-calcified nodules and evaluated the size, the growth and the distance from the nearest pleural surface. The characteristics of the nodules were defined based on the results of either a diagnostic biopsy or nodule growth. RESULTS One or more non-calcified pulmonary nodules were detected in 75% of the patients (233/308). One hundred and thirty-seven of these patients had nodules that met the criteria of either benign or malignant nodules. Nodules smaller than 10mm were more likely to be benign, whereas those 10mm or greater were more likely to be malignant (22/26, 85%; P<.0001). Most nodules less than 10mm from the pleura were benign (91%), whereas approximately half of the nodules 10mm or more away from the pleura were malignant (20/43, 47%; P<.0001). Patients with melanoma, sarcoma, or testicular carcinoma were more likely to have malignant nodules. A multivariable analysis demonstrated the nodule size (P<.0001) and distance from the pleura were predictive of malignancy. CONCLUSION The nodule detection rate on thin-section CT in patients with extrapulmonary malignancy is high. Most of the nodules smaller than 10mm or less than 10mm from the pleura are benign.

Differentiation between benign phyllodes tumors and fibroadenomas of the breast on MR imaging.

PURPOSE The purpose of this study was to determine the factors that contribute to the differentiation between phyllodes tumors (PTs) and fibroadenomas (FAs) on MR imaging. MATERIALS AND METHODS This retrospective study included 19 PTs and 18 FAs with ≥ 2 cm diameter. The presence or absence of a capsule and internal septum, the extent of lobulation, and the apparent diffusion coefficient (ADC) values were determined. The presence or absence of a cystic component, the time-intensity curve, and the signal intensity on delayed-phase contrast-enhanced T1WI were also evaluated in 31 patients (16 PTs and 17 FAs) who underwent a contrast-enhanced study. RESULTS Cystic components were seen in 10 of the 16 PTs (63%) and in 4 of the 17 FAs (24%; P=0.03). The PTs showed strong lobulation more frequently compared to the FAs (14/19 [74%] vs. 7/18 [39%], respectively; P=0.04). Though there was no significant difference, PT tended to be heterogeneous more frequently on the delayed phase of the contrast-enhanced T1WI compared to the FA (11/16 [69%] vs. 7/17 [41%], respectively). No significant difference was found in the other findings. CONCLUSIONS Although PTs and FAs show similar MR findings, the presence of a cystic component, strong lobulation, and heterogeneity on delayed-phase contrast-enhanced T1WI suggests a PT.

Interventricular Dyssynchrony Using Tagging Magnetic Resonance Imaging Predicts Right Ventricular Dysfunction in Adult Congenital Heart Disease

PURPOSE Right ventricular (RV) failure and ventricular dyssynchrony are strong determinants of prognosis in patients with adult congenital heart disease (ACHD). The aim of this study was to investigate the relationship between interventricular dyssynchrony (IVD) using cine-tagged magnetic resonance imaging (MRI) and RV dysfunction in ACHD patients. MATERIALS AND METHODS Sixty-seven patients with ACHD (38 with repaired tetralogy of Fallot; 22 with atrial septal defect; seven with ventricular septal defect) underwent tagging MRI. Time curves of myocardial circumferential strains for RV and left ventricular (LV) free walls were delivered from short-axis cine-tagging images. Contraction delay between RV and LV free walls was computed by cross-correlation analysis of the two strain time curves and was defined as the IVD time (msec). RESULTS IVD was significantly greater for patients with RV ejection fraction (RVEF) <40% (116 ± 58 msec) than for patients with RVEF ≥ 40% (65 ± 54 msec) and was significantly greater for patients with RV systolic pressure ≥ 40 mm Hg (112 ± 59 msec) than for patients with RV systolic pressure <40 mm Hg (49 ± 28 msec). Receiver operating characteristic analysis revealed optimal IVD thresholds for detecting patients with RVEF <40% with C-statistics of 0.76 and patients with RV systolic pressure ≥ 40 mm Hg with C-statistics of 0.81. CONCLUSION Quantification of IVD was possible using RV and LV strains derived from tagging MRI. IVD, represented as the time difference between LV and RV contractions, correlates with RV dysfunction. IVD may thus offer an indicator for RV failure in ACHD.

Anterior mediastinal solid tumours in adults: characterisation using dynamic contrast-enhanced MRI, diffusion-weighted MRI, and FDG-PET/CT.

AIM To find significant parameters to characterise anterior mediastinal solid tumours in adults using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), diffusion-weighted MRI (DWI), and combined 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (FDG-PET/CT). MATERIALS AND METHODS Forty-eight histologically confirmed anterior mediastinal solid tumours in 48 patients (24 men, 24 women; age range 21-83 years, mean 50.7 years) were examined. The parameters analysed were maximal diameter, presence of capsule/septa on T2-weighted images, time-signal intensity curves (TICs), apparent diffusion coefficient (ADC), and maximum standardised uptake value (SUVmax). Also examined was whether any differences between histological types could be seen in these parameters. In a validation study, 42 anterior mediastinal solid tumours in 42 patients were examined consecutively. RESULTS The washout pattern on TIC was seen only in thymic epithelial tumours (20/32). SUVmax of lymphoma (mean, 17.9), malignant germ cell tumours (14.2), and thymic carcinomas (15.6) were significantly higher than that of thymomas (6.1). The mean maximal diameter of thymic epithelial tumours was significantly smaller than that of lymphomas (p<0.01) and malignant germ cell tumours (p<0.05). The validation study also yielded high accuracy (38/42, 91%) in differentiation among the anterior mediastinal solid tumours. CONCLUSION The SUVmax, TIC pattern on DCE-MRI, and maximal diameter might be useful to differentiate anterior mediastinal solid tumours in adults.

Volumetric measurement of artificial pure ground-glass nodules at low-dose CT: Comparisons between hybrid iterative reconstruction and filtered back projection

PURPOSE To compare hybrid iterative reconstruction (HIR) with filtered back projection (FBP) in the volumetry of artificial pure ground-glass nodules (GGNs) with low-dose computed tomography (CT). MATERIALS AND METHODS Artificial GGNs (10 mm-diameter, 523.6 mm(3), -660 HU) in an anthropomorphic chest phantom were scanned by a 256-row multi-slice CT with three dose levels (10, 30, 100 mAs). Each scan was repeated six times. Each set was reconstructed by FBP and HIR at 0.625-mm thickness. The volumes of artificial GGNs placed at the lung apex and middle lung field of the chest phantom were measured by two observers. Semi-automated measurements were performed by clicking the cursor in the center of GGNs, and manual measurements were performed by tracing GGNs on axial section. Modification of the trace was added on a sagittal or coronal section if necessary. Measurement errors were calculated for both the FBP and HIR at each dose level. We used the Wilcoxon signed rank test to identify any significant difference between the measurement errors of the FBP and HIR. Inter-observer, intra-observer, and inter-scan variabilities were evaluated by Bland Altman analysis with limits of agreements given by 95% confidence intervals. RESULTS There were significant differences in measurement errors only at the lung apex between FBP and HIR with 10 mAs in both the semi-automated (observer 1, -37% vs. 7.2%; observer 2, -39% vs. 1.9%) and manual methods (observer 1, -29% vs. 7.5%; observer 2, -30% vs. 1.1%), respectively (P<0.05). HIR provided each variability equal to or less than one half of that of FBP at 10 mAs in both methods. In the semi-automated method, the inter-observer and intra-observer variabilities obtained by HIR at 10 mAs were -11% to 17% and -6.7% to 6.7%, whereas those for FBP at 10 mAs were -29% to 30% and -38% to 20%, respectively. The inter-scan variability for FBP at 100 mAs vs. HIR at 10 mAs was -9.5% to 11%, and that for FBP at 100 mAs vs. FBP at 10 mAs was -73% to 32%. In the manual method, the inter-observer and intra-observer variabilities for HIR at 10 mAs were -14% to 22% and -9.8% to 22%, and those for FBP at 10 mAs were -45% to 36% and -31% to 28%, respectively. The inter-scan variability for FBP at 100 mAs vs. HIR at 10 mAs was -7.4% to 23%, and that for FBP at 100 mAs vs. FBP at 10 mAs was -52% to 26%. CONCLUSION HIR is superior to FBP in the volumetry of artificial pure GGNs at lung apex with low-dose CT.

Description of early gastric cancer with wall-carving technique on multidetector computed tomography

PurposeWe introduce a new volume-rendering method, named the “wall-carving (WC) technique,” for luminal organs on contrast-enhanced multidetector row computed tomography (MDCT) using a gas-extension protocol. This study aimed to investigate the enhancement profile of the normal gastric wall, particularly focused on the relation between depth and gray value in the normal gastric wall, as a background to distinguish early gastric cancer (EGC) on MDCT.Materials and methodsWe retrospectively evaluated 32 data sets of abdominal CT with EGC. All data sets were obtained with a 64-detector-row CT after administration of an effervescent agent, anticholinergic drug, and intravenous contrast material. The enhancement profile was analyzed in the normal gastric body and antrum (n = 32) by the depth from the air-mucosa interface. We also examined the visual accessibility of the WC image. Institutional review board approval was obtained for this study.ResultsThe profile curve showed that the thickness of the normal gastric wall was 3.75–6.25 mm (mean 4.8 mm), and the maximum enhancement was observed at the layer of 1.875 mm in each case. The enhancement pattern of the EGC was visually accessible, especially at a depth of 1.875–3.75 mm.ConclusionThe enhancement profile showed a peak at the depth within the inner half-thickness of the estimated normal gastric wall. The WC image seems to be a good alternative for detecting tumor enhancement and its relation with the surrounding vascular structures in the gastric wall.

One-stop shop assessment for atrial septal defect closure using 256-slice coronary CT angiography.

ObjectivesTo investigate the feasibility and accuracy of measurement of the pulmonary to systemic blood flow ratio (Qp/Qs) and defect and rim sizes in secundum atrial septal defects (ASDs) using 256-slice CT, compared to the reference transoesophageal echocardiography (TEE) and right heart catheterization (RHC) measurements.MethodsTwenty-three consecutive adult patients with secundum ASDs who underwent retrospective ECG-gated coronary CT angiography (CCTA), TEE and RHC were enrolled in this study. Right ventricular (RV) and left ventricular (LV) stroke volumes (SV) were calculated by biventricular volumetry of CCTA. Qp/Qs-CT was defined as RVSV/LVSV. The sizes of the defect and rim were measured by multi-planar reconstruction CT images. Correlations between Qp/Qs-CT and Qp/Qs–RHC and between the defect diameter obtained by CT and TEE were analyzed by Pearson’s coefficient analysis. Rim sizes by CT and TEE were compared by paired t-test.ResultsQp/Qs-CT was significantly correlated with Qp/Qs-RHC (r = 0.83, p < 0.0001), and the defect diameter by CT was significantly correlated with that by TEE (r = 0.95, p < 0.0001). There was no significant difference between CT and TEE in measurements of rim size.Conclusions256-slice CCTA allows measuring Qp/Qs and size of defects and rims in patients with secundum ASDs, accomplishing pretreatment evaluation non-invasively and comprehensively.Key Points• Quantification of left-to-right shunting can be performed reliably and accurately by CT.• The sizes of defects and rims can be measured accurately using 256-slice CT.• 256-slice CT permits pretreatment evaluation of ASD non-invasively and comprehensively.

Multiparametric voxel-based analyses of standardized uptake values and apparent diffusion coefficients of soft-tissue tumours with a positron emission tomography/magnetic resonance system: Preliminary results

AbstractObjectivesTo investigate the usefulness of voxel-based analysis of standardized uptake values (SUVs) and apparent diffusion coefficients (ADCs) for evaluating soft-tissue tumour malignancy with a PET/MR system.MethodsThirty-five subjects with either ten low/intermediate-grade tumours or 25 high-grade tumours were prospectively enrolled. Zoomed diffusion-weighted and fluorodeoxyglucose (18FDG)-PET images were acquired along with fat-suppressed T2-weighted images (FST2WIs). Regions of interest (ROIs) were drawn on FST2WIs including the tumour in all slices. ROIs were pasted onto PET and ADC-maps to measure SUVs and ADCs within tumour ROIs. Tumour volume, SUVmax, ADCminimum, the heterogeneity and the correlation coefficients of SUV and ADC were recorded. The parameters of high- and low/intermediate-grade groups were compared, and receiver operating characteristic (ROC) analysis was also performed.ResultsThe mean correlation coefficient for SUV and ADC in high-grade sarcomas was lower than that of low/intermediate-grade tumours (−0.41 ± 0.25 vs. −0.08 ± 0.34, P < 0.01). Other parameters did not differ significantly. ROC analysis demonstrated that correlation coefficient showed the best diagnostic performance for differentiating the two groups (AUC 0.79, sensitivity 96.0%, specificity 60%, accuracy 85.7%).ConclusionsSUV and ADC determined via PET/MR may be useful for differentiating between high-grade and low/intermediate-grade soft tissue tumours.Key Points• PET/MR allows voxel-based comparison of SUVs and ADCs in soft-tissue tumours. • A comprehensive assessment of internal heterogeneity was performed with scatter plots. • SUVmax or ADCminimum could not differentiate high-grade sarcoma from low/intermediate-grade tumours. • Only the correlation coefficient between SUV and ADC differentiated the two groups. • The correlation coefficient showed the best diagnostic performance by ROC analysis.

Detectability of T1a lung cancer on digital chest radiographs: an observer-performance comparison among 2-megapixel general-purpose, 2-megapixel medical-purpose, and 3-megapixel medical-purpose liquid-crystal display (LCD) monitors.

Background There has been no comparison of detectability of small lung cancer between general and medical LCD monitors or no comparison of detectability of small lung cancer between solid and part-solid nodules. Purpose To compare the detectabilities of T1a lung cancer on chest radiographs on three LCD monitor types: 2-megapixel (MP) for general purpose (General), 2-MP for medical purpose (Medical), and 3-MP-Medical. Material and Methods Radiographs from forty patients with T1aN0M0 primary lung cancer (27 solid nodules, 13 part-solid nodules) and 60 patients with no abnormalities on both chest X-ray and computed tomography (CT) were consecutively collected. Five readers assessed 100 cases for each monitor. The observations were analyzed using receiver operating characteristic (ROC) analysis. A jackknife method was used for statistical analysis. A P value of <0.05 was considered significant. Results The average AUC for all T1a lung cancer nodule detection using the 2-MP-General, 2-MP-Medical, and 3-MP-Medical LCD monitors were 0.86, 0.89, and 0.89, respectively; there were no significant differences among them. The average AUC for part-solid nodule detection using a 2-MP-General, 2-MP-Medical, and 3-MP-Medical LCD monitors were 0.77, 0.86, and 0.89, respectively. There were significant differences between the 2-MP-General and 2-MP-Medical LCD monitors (P = 0.043) and between the 2-MP-General and 3-MP-Medical LCD monitors (P = 0.027). There was no significant difference between the 2-MP-Medical and 3-MP-Medical LCD monitors. The average AUC for solid nodule detection using a 2-MP-General, 2-MP-Medical, and 3-MP-Medical LCD monitors were 0.90, 0.90, and 0.88, respectively; there were no significant differences among them. The mean AUC values for all and part-solid nodules of the low-experienced readers were significantly lower than those of the high-experienced readers with the 2 M-GP color LCD monitor (P < 0.05). Conclusion Detectability of part-solid nodules using a general-purpose LCD monitor was significantly lower than those using medical-purpose LCD monitors.