Whole-tumor histogram analysis of DWI and QSI for differentiating between meningioma and schwannoma: a pilot study Abstract Purpose To investigate whether whole-tumor histogram analyses of diffusivity measurements derived from q-space imaging (QSI) improves the differentiation between meningioma and schwannoma. Materials and methods Fifteen extra-axial tumors (11 meningiomas and 4 schwannomas) with MR examinations from April 2011 to May 2013 were included. Three-dimensional regions of interest (ROI) encompassed the whole tumor, including cystic areas. Histogram analyses of mean displacement (MD) derived from QSI and apparent diffusion coefficient (ADC) for the ROI were performed at mean, the five percentiles of MDn and ADCn (n = 5, 25, 50, 75, 95th), kurtosis, and skewness. To determine the diagnostic ability of MDn and ADCn, we also compared the area under the curve (AUC) on receiver operating characteristic (ROC) analysis. Results Histogram analyses revealed significant differences between meningioma and schwannoma in MD75, ADC25, ADC50, ADC75, and kurtosis of ADC. The ROC analysis of kurtosis of ADC and MD75 resulted in an AUC of 1.0 and 0.96, respectively. There were no significant differences between the AUC of MD75 and that of kurtosis of ADC (p = 0.41). Conclusion The histogram analyses of MD and ADC derived from QSI were both equally useful in differentiating between intracranial meningioma and schwannoma.

Early detection of intrahepatic cholangiocarcinoma Abstract Cholangiocarcinoma (CC) is a malignant tumor which arises from the biliary epithelium and most cases represent adenocarcinoma. CC can be classified into intrahepatic CC (ICC), perihilar CC, and distal CC, based on the site of anatomic origin. The incidence of ICC is increasing in both Western and Eastern countries, while that of extrahepatic cholangiocarcinoma remains fairly stable. ICC infiltrates into adjacent nerves and lymphatic vessels, resulting in progressive disease with a poor prognosis; thus, early detection of ICC is critical for achieving better outcomes and providing better patient care. However, it is difficult for clinicians to detect an ICC, especially in its early stage. Different from hepatocellular carcinoma, the lack of surveillance system for the high-risk group of CC does not allow for a reliable screening examination. In this context, for early detection and diagnosis of ICC, radiologists need to know predisposing conditions that can lead to the development of ICC, such as chronic biliary or hepatic inflammation, primary sclerosing cholangitis, congenital biliary diseases, and other conditions. In this article, we discuss and illustrate the radiologic features of ICC with special attention to early disease stages and of predisposing conditions of ICC.

Management of acute cholecystitis after biliary stenting for malignant obstruction: comparison of percutaneous gallbladder drainage and aspiration Abstract Purpose To evaluate and compare the clinical outcomes between percutaneous gallbladder drainage (PGBD) and percutaneous gallbladder aspiration (PGBA) for acute cholecystitis after biliary stenting for malignant biliary obstruction. Materials and methods Twenty-six and 14 patients underwent PGBD and PGBA, respectively, for acute cholecystitis after biliary stenting for malignant obstruction. The technical success rate, clinical effectiveness, and safety were compared between the 2 groups. Results Technical success was achieved in all patients. Clinical effectiveness rate was significantly higher in the PGBD group than in the PGBA group [100% (26/26) vs. 57% (8/14), p < 0.01]. In the PGBA group, clinical effectiveness rate was significantly lower in patients with tumor involvement of the cystic duct [13% (1/8) with involvement vs. 83% (5/6) without involvement, p = 0.03]. There were no deaths related to the procedure or acute cholecystitis aggravation. Pleural effusion and biliary peritonitis occurred in 1 patient each after PGBD and intra-abdominal bleeding occurred in 1 patient after PGBA as complications requiring treatment. Conclusion Although PGBD was a more effective treatment for acute cholecystitis after biliary stenting for malignant obstruction, PGBA may be a less invasive option for high-risk patients without tumor involvement of the cystic duct.

In vitro evaluation of radiopacity of contrast-loaded superabsorbent polymer microspheres (SAP-MS) with static imaging and flow model Abstract Purpose To evaluate the radiopacity of contrast-loaded superabsorbent polymer microspheres (SAP-MS) under X-ray imaging. Materials and methods SAP-MS were suspended in contrast material (iodixanol) and the diameter change was assessed. The diameter of contrast-loaded SAP-MS in saline was measured sequentially. Radiography of the contrast-loaded SAP-MS was evaluated as radiopacity by contrast-to-noise ratio and visibility by multiple reader scoring. Under digital subtraction angiography, contrast-loaded SAP-MS were injected into a flow model. The flow speed was 1–10 cm/s, and images were acquired at 1–7.5 frames per second using a pulse width of 10–85 ms. Images were assessed by multiple reader scoring. Results The diameter of SAP-MS increased to 4.0–5.0 times its original size for approximately 15 min. The diameter of contrast-loaded SAP-MS in saline further increased by 10–30% within several minutes and returned to the previous size. Radiopacity and visibility of contrast-loaded SAP-MS decreased in 30 min after mixing with saline. Visibility was better with slow flow speed and narrow pulse width. Conclusion For effective observation, contrast-loaded SAP-MS should be kept in non-diluted contrast material until use. The conditions of slower flow and use of a narrow pulse width are recommended.

Factors affecting the accuracy of respiratory tracking of the image-guided robotic radiosurgery system Abstract Purpose To analyze the factors affecting the tracking accuracy of the CyberKnife Synchrony Respiratory Tracking System (SRTS). Materials and methods A dynamic motion phantom (motion phantom) reproduced the respiratory motions of each patient treated with the SRTS using a ball as the target. CyberKnife tracked the ball using the SRTS, and this process was recorded by a video camera mounted on the linear accelerator head. The tracking error was evaluated from the images captured by the video camera. Multiple regression analysis was used to identify factors affecting tracking accuracy from 91 cases. Results The median tracking error was 1.9 mm (range 0.9–5.3 mm). Four factors affected the tracking accuracy: the average absolute amplitude of the tumor motion in the cranio-caudal (CC) direction (p = 0.007), average position gap due to the phase shift between the internal tumor and external marker positions in the CC direction (p < 0.001), and average velocity of the tumor in the CC (p < 0.001) and anterior–posterior directions (p = 0.033). Conclusion We identified factors that affected tracking accuracy. This information may assist the identification of suitable margins that should be added to each patient’s clinical target volume.

Assessment of angiogenesis in rabbit orthotropic liver tumors using three-dimensional dynamic contrast-enhanced ultrasound compared with two-dimensional DCE-US Abstract Objectives To evaluate quantitative three-dimensional (3D) dynamic contrast-enhanced ultrasound (DCE-US) in the assessment of tumor angiogenesis using an orthotropic liver tumor model. Methods Nine New Zealand white rabbits with liver orthotropic VX2 tumors were established and imaged by two-dimensional (2D) and 3D DCE-US after SonoVue® bolus injections. The intraclass correlation coefficients of perfusion parameters, including peak intensity (PI), mean transit time, time to peak, and area under the curve, were calculated based on time-intensity curve. The percentage area of microvascular (PAMV) and the expression of vascular endothelial growth factor (VEGF) were both evaluated by immunohistochemical analysis and weighted by the tumor activity area ratio. Correlations between quantitative and histologic parameters were analyzed. Results The reproducibility of 3D DCE-US quantitative parameters was excellent (ICC 0.91–0.99); but only PI showed high reproducibility (ICC 0.97) in 2D. None of the parameters of quantitative 2D DCE-US were significantly correlated with weighted PAMV or VEGF. For 3D DCE-US, there was a positive correlation between PI and weighted PAMV (r = 0.74, P = 0.04) as well as VEGF (r = 0.79, P = 0.02). Conclusion Quantitative parameters of 3D DCE-US show feasibility, higher reproducibility and accuracy for the assessment of tumor angiogenesis using an orthotropic liver tumor model compared with 2D DCE-US.

MRI-detected breast lesions: clinical implications and evaluation based on MRI/ultrasonography fusion technology Abstract Magnetic resonance imaging (MRI) is a highly sensitive imaging modality that frequently reveals additional breast lesions that are occult on mammography and ultrasonography (US) and are thus difficult to diagnose. It is important to investigate these MRI-detected suspicious lesions, which are associated with a fairly high rate of malignancy. In this review, we have discussed MRI/US fusion technology, a magnetic position tracking system that synchronizes real-time US and MRI to improve lesion detection and enables comparisons of MRI and US findings of the detected lesions. This combination increases the precision of second-look US. We hope that our review underscores the importance of understanding the US findings and histopathology of MRI-detected breast lesions, as this will enable radiologists to perform appropriate assessments.

Tc-99m PMT scintigraphy in the diagnosis of pediatric biliary atresia Abstract Purpose Hepatobiliary scintigraphy plays an important role in the differentiation of biliary atresia (BA) and non-BA. The usefulness of 99mTc-iminodiacetic acid (IDA) derivatives in BA diagnosis is reported in several papers. In contrast, there are no comprehensive data on differentiating BA from non-BA using 99mTc-N-pyridoxyl-5-methyl-tryptophan (PMT). Our objective was to evaluate the usefulness of 99mTc-PMT scintigraphy in the diagnosis of BA. Materials and methods 52 infants who received 99mTc-PMT scintigraphy for suspected BA were retrospectively evaluated. Preoperative cholangiograms or follow-ups were used as the gold standard for diagnosis of BA. We analyzed the utility of 99mTc-PMT scintigraphy, various clinical and investigational parameters in the diagnosis of BA. Results The final diagnoses in this group were BA (67.3%) and non-BA (32.7%). 99mTc-PMT scintigraphy, stool color change, total bilirubin, direct bilirubin, aspartate aminotransferase (AST) and γ-glutamyl transferase (γ-GTP) led to distinguishing between BA and non-BA in univariate analysis. Subsequent multivariate logistic regression analysis indicated that 99mTc-PMT scintigraphy and γ-GTP were independent predictors of BA. The diagnostic accuracy of 99mTc-PMT scintigraphy was 94.2%. Conclusions 99mTc-PMT scintigraphy is more accurate in the diagnosis of BA than other conventional examinations. In addition, false positives of 99mTc-PMT scintigraphy could be reduced by combining γ-GTP level monitoring.

Diagnostic imaging of dementia with Lewy bodies, frontotemporal lobar degeneration, and normal pressure hydrocephalus Abstract Neuroimaging can provide important biomarkers and is very useful for supporting dementia diagnosis. This review summarizes the neuroimaging findings of dementia with Lewy bodies (DLB), frontotemporal lobar degeneration (FTLD), and normal pressure hydrocephalus (NPH). In DLB, medial temporal atrophy is milder than that of Alzheimer’s disease. 2-fluoro-2-deoxy-d-glucose-positron emission tomography and brain perfusion single-photon emission computed tomography demonstrate hypometabolism and hypoperfusion in the occipital lobe, in addition to decreased metabolism and perfusion in the parietotemporal, posterior cingulate, precuneus, and frontal association cortices. The cingulate island sign, which shows relatively spared middle-to-posterior cingulate cortex metabolism compared with precuneus hypometabolism, is proposed to detect DLB in 2-fluoro-2-deoxy-d-glucose-positron emission tomography imaging. Reduced uptake in dopamine transporter imaging and reduced myocardial uptake in iodine-123 metaiodobenzylguanidine cardiac scintigraphy are indicative biomarkers for DLB diagnosis. Characteristic findings of FTLD include dominant frontotemporal atrophy, hypometabolism, and hypoperfusion. Most idiopathic NPH cases demonstrate disproportionally enlarged subarachnoid space hydrocephalus findings, including dilated ventricular systems, enlarged Sylvian fissures, tight sulci in the midline, and a high convexity.

Computed tomography diagnosis of transomental hernia