Daisuke Komoto

Ultra-High-Resolution Computed Tomography of the Lung: Image Quality of a Prototype Scanner

Purpose The image noise and image quality of a prototype ultra-high-resolution computed tomography (U-HRCT) scanner was evaluated and compared with those of conventional high-resolution CT (C-HRCT) scanners. Materials and Methods This study was approved by the institutional review board. A U-HRCT scanner prototype with 0.25 mm x 4 rows and operating at 120 mAs was used. The C-HRCT images were obtained using a 0.5 mm x 16 or 0.5 mm x 64 detector-row CT scanner operating at 150 mAs. Images from both scanners were reconstructed at 0.1-mm intervals; the slice thickness was 0.25 mm for the U-HRCT scanner and 0.5 mm for the C-HRCT scanners. For both scanners, the display field of view was 80 mm. The image noise of each scanner was evaluated using a phantom. U-HRCT and C-HRCT images of 53 images selected from 37 lung nodules were then observed and graded using a 5-point score by 10 board-certified thoracic radiologists. The images were presented to the observers randomly and in a blinded manner. Results The image noise for U-HRCT (100.87 ± 0.51 Hounsfield units [HU]) was greater than that for C-HRCT (40.41 ± 0.52 HU; P < .0001). The image quality of U-HRCT was graded as superior to that of C-HRCT (P < .0001) for all of the following parameters that were examined: margins of subsolid and solid nodules, edges of solid components and pulmonary vessels in subsolid nodules, air bronchograms, pleural indentations, margins of pulmonary vessels, edges of bronchi, and interlobar fissures. Conclusion Despite a larger image noise, the prototype U-HRCT scanner had a significantly better image quality than the C-HRCT scanners.

Effect of lapatinib on hepatic parenchymal enhancement on gadoxetate disodium (EOB)-enhanced MRI scans.

We present changes seen on hepatobiliary phase (HBP)-gadoxetate disodium (EOB)-enhanced magnetic resonance image of a woman with liver metastases who was treated with lapatinib. After treatment, the HBP images appeared like portal venous phase images. This suggests that lapatinib, an inhibitor of organic anion transporting polypeptide 1B1, one of the substrates of EOB, inhibits EOB uptake by hepatocytes. In patients treated with lapatinib, the ability to diagnose liver tumors on HBP images may be compromised.

Radiation dose reduction at MDCT with iterative reconstruction for prenatal diagnosis of skeletal dysplasia: preliminary study using normal fetal specimens.

OBJECTIVE The purpose of this study was to investigate to what degree the radiation dose can be reduced without affecting the ability to evaluate normal fetal bones at MDCT with iterative reconstruction. MATERIALS AND METHODS Fifteen normal fetal specimens immersed in containers (30- and 35-cm diameter) were scanned with a 64-MDCT scanner, with tube voltage of 100 kVp and tube current of 600, 300, 150, 100, and 50 mA. Images were subjected to adaptive statistical iterative reconstruction (ASIR). The fetal dose was measured using glass dosimeters. We calculated the relative ratio of the dose at 600 mA. Image quality was evaluated on maximum-intensity-projection and volume-rendering images. Two radiologists recorded the visualization scores of five regions. Images at 600 mA were considered to be standard. RESULTS With the 30-cm-diameter container, the fetal dose was 10.15 mGy (relative ratio, 100%) at a tube current of 600, 51% at 300, 25% at 150, 17% at 100, and 9% at 50 mA. With the 35-cm-diameter container the fetal dose was 10.01 mGy (relative ratio, 100%) at 600, 47% at 300, 24% at 150, 17% at 100, and 8% at 50 mA. Visual evaluation showed that in both containers, with ASIR 90%, there was a statistically significant difference between 50-and 600-mA images (p<0.01) but not between 600-mA images and those acquired at 100, 150, and 300 mA (p=0.08-1.00). CONCLUSION The fetal radiation dose for the evaluation of normal fetal bones can be reduced by 83% with ASIR 90%.

Multidetector Computed Tomography-Based Microstructural Analysis Reveals Reduced Bone Mineral Content and Trabecular Bone Changes in the Lumbar Spine after Transarterial Chemoembolization Therapy for Hepatocellular Carcinoma

Purpose It is well recognized that therapeutic irradiation can result in bone damage. However, long-term bone toxicity associated with computed tomography (CT) performed during interventional angiography has received little attention. The purpose of this study was to determine the prevalence of osteoporosis and trabecular microstructural changes in patients after transarterial chemoembolization (TACE) for hepatocellular carcinoma therapy using an interventional-CT system. Materials and Methods Spinal microarchitecture was examined by 64-detector CT in 81 patients who underwent TACE, 35 patients with chronic hepatitis, and 79 controls. For each patient, the volumetric CT dose index (CTDIv) during TACE (CTDIv (TACE)), the dose-length product (DLP) during TACE (DLP (TACE)), and CTDIv and DLP of routine dynamic CT scans (CTDIv (CT) and DLP (CT), respectively), were calculated as the sum since 2008. Using a three dimensional (3D) image analysis system, the tissue bone mineral density (tBMD) and trabecular parameters of the 12th thoracic vertebra were calculated. Using tBMD at a reported cutoff value of 68 mg/cm3, the prevalence of osteoporosis was assessed. Results The prevalence of osteoporosis was significantly greater in the TACE vs. the control group (39.6% vs. 18.2% for males, P<0.05 and 60.6% vs. 34.8% for females, P<0.01). Multivariate regression analysis demonstrated that sex, age, and CTDIv (CT) significantly affected the risk of osteoporosis. Of these indices, CTDIv (CT) had the highest area under the curve (AUC) (0.735). Correlation analyses of tBMD with cumulative radiation dose revealed weak correlations between tBMD and CTDIv (CT) (r 2 = 0.194, P<0.001). Conclusion The prevalence of osteoporosis was significantly higher in post TACE patients than in control subjects. The cumulative radiation dose related to routine dynamic CT studies was a significant contributor to the prevalence of osteoporosis.

Radiologic-Pathologic Correlation of Solid Portions on Thin-section CT Images in Lung Adenocarcinoma: A Multicenter Study

Micro‐Abstract Although the invasiveness size on computed tomography (CT) is important for the T descriptor, the solid portion size on CT will be larger than the pathologic invasiveness size. We analyzed whether the maximal dimensions of the solid portions on CT correlated with the pathologic invasiveness size (> 0.5 cm) in 378 lung adenocarcinoma patients. A solid portion > 0.8 cm on the lung window setting or > 0.6 cm on the mediastinal window setting predicted for pathologic invasiveness > 0.5 cm. Background Measuring the size of invasiveness on computed tomography (CT) for the T descriptor size was deemed important in the 8th edition of the TNM lung cancer classification. We aimed to correlate the maximal dimensions of the solid portions using both lung and mediastinal window settings on CT imaging with the pathologic invasiveness (> 0.5 cm) in lung adenocarcinoma patients. Materials and Methods The study population consisted of 378 patients with a histologic diagnosis of adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), invasive adenocarcinoma (IVA)‐lepidic, IVA‐acinar and/or IVA‐papillary, and IVA‐micropapillary and/or solid adenocarcinoma. A panel of 15 radiologists was divided into 2 groups (group A, 9 radiologists; and group B, 6 radiologists). The 2 groups independently measured the maximal and perpendicular dimensions of the solid components and entire tumors on the lung and mediastinal window settings. The solid proportion of nodule was calculated by dividing the solid portion size (lung and mediastinal window settings) by the nodule size (lung window setting). The maximal dimensions of the invasive focus were measured on the corresponding pathologic specimens by 2 pathologists. Results The solid proportion was larger in the following descending order: IVA‐micropapillary and/or solid, IVA‐acinar and/or papillary, IVA‐lepidic, MIA, and AIS. For both groups A and B, a solid portion > 0.8 cm in the lung window setting or > 0.6 cm in the mediastinal window setting on CT was a significant indicator of pathologic invasiveness > 0.5 cm (P < .001; receiver operating characteristic analysis using Youdens index). Conclusion A solid portion > 0.8 cm on the lung window setting or solid portion > 0.6 cm on the mediastinal window setting on CT predicts for histopathologic invasiveness to differentiate IVA from MIA and AIS.

Diffusion-weighted MR imaging of non-complicated hepatic cysts: Value of 3T computed diffusion-weighted imaging

Purpose To investigate the utility of computed 3T diffusion-weighted imaging (c-DWI) for the diagnosis of non-complicated hepatic cysts with a focus on the T2 shine-through effect. Materials and methods In 50 patients with non-complicated hepatic cysts we acquired one set of DWIs (b-value 0 and 1000 s/mm2) at 1.5T, and two sets at 3T (b-value 0 and 1000 s/mm2, TE 70 ms; b-value 0 and 600 s/mm2, TE 60 ms). We defined the original DWIs acquired with b = 1000 s/mm2 at 1.5T and 3T as “o-1.5T-1000” and “o-3T-1000”. c-DWIs were calculated with 3T DWI at b-values of 0 and 600 s/mm2. c-DWI with b = 1000 and 1500 s/mm2 were defined as “c-1000” and “c-1500”. Radiologists evaluated the signal intensity (SI) of the cysts using a 3-point score where 1 = not visible, 2 = discernible, and 3 = clearly visible. They calculated the contrast ratio (CR) between the cysts and the surrounding liver parenchyma on each DWIs and recorded the apparent diffusion coefficient (ADC) with a b-value = 0 and 1000 s/mm2 on 1.5T- and 3T DWIs. Results Compared with o-1.5T-1000 DWI, the visual scores of all but the c-1500 DWIs were higher (p = 0.07 for c-1500- and p < 0.01 for the other DWIs). The CR at b = 1000 s/mm2 was higher on o-3T-1000- than on o-1.5T-1000- (p < 0.01) but not higher than on c-1500 DWIs (p = 0.96). The CR at b = 0 s/mm2 on 3T images with TE 70 ms was higher than on 1.5T images (p < 0.01). The ADC value was higher for 3T- than 1.5T images (p < 0.01). Conclusions Non-complicated hepatic cysts showed higher SI on o-3T-1000- than o-1.5T-1000 DWIs due to the T2-shine through effect. This high SI was suppressed on c-1500 DWIs.

Correction: Ultra-High-Resolution Computed Tomography of the Lung: Image Quality of a Prototype Scanner

Fig 5F and 5G are improperly labelled. Please see the correct Fig 5 here. Fig 5 CT-pathologic correlation of an adenocarcinoma in situ.