Ryota Shimofusa

Diffusion-weighted imaging of prostate cancer.

Objective: The purpose of this study was to assess whether T2-weighted (T2W) imaging with diffusion-weighted (DW) imaging could improve prostate cancer detection as compared with T2W imaging alone. Methods: The subjects consisted of 37 patients with prostate cancer and 23 without cancer undergoing magnetic resonance (MR) imaging. Using a 1.5-T superconducting magnet, all patients underwent T2W and DW imaging with parallel imaging. Images were independently reviewed by 3 readers to determine the detectability of prostate cancer. The detectability of T2W imaging without and with DW imaging was assessed by means of receiver operating characteristic analysis. Results: Mean areas under the receiver operating characteristic curve for T2W imaging alone and for T2W imaging with DW imaging were 0.87 and 0.93, respectively. The receiver operating characteristic analysis showed that the addition of DW imaging to conventional T2W imaging significantly improved tumor detection (P = 0.0468) compared with T2W imaging alone. Conclusions: The addition of DW imaging to conventional T2W imaging provides better detection of prostate cancer.

Gadoxetic acid-enhanced MRI compared with CT during angiography in the diagnosis of hepatocellular carcinoma

PURPOSE To assess the value of gadoxetic acid-enhanced magnetic resonance imaging (MRI) for the pre-therapeutic detection of hepatocellular carcinoma (HCC) using receiver operating characteristic (ROC) analysis with the combination of computed tomography (CT) arterial portography and CT hepatic arteriography (CTAP/CTHA). MATERIALS AND METHODS A total of 54 consecutive patients with 87 nodular HCCs were retrospectively analyzed. All HCC nodules were confirmed pathologically. Three blinded readers independently reviewed 432 hepatic segments, including 78 segments with 87 HCCs. Each reader read two sets of images: Set 1, CTAP/CTHA; Set 2, gadoxetic acid-enhanced MRI including a gradient dual-echo sequence and diffusion-weighted imaging (DWI). The ROC method was used to analyze the results. The sensitivity, specificity, positive predictive value, negative predictive value and sensitivity according to tumor size were evaluated. RESULTS For each reader, the area under the curve was significantly higher for Set 2 than for Set 1. The mean area under the curve was also significantly greater for Set 2 than for Set 1 (area under the curve, 0.98 vs. 0.93; P=.0009). The sensitivity was significantly higher for Set 2 than for Set 1 for all three readers (P=.012, .013 and .039, respectively). The difference in the specificity, positive predictive values and negative predictive values of the two modalities for each reader was not significant (P>.05). CONCLUSION Gadoxetic acid-enhanced MRI including a gradient dual-echo sequence and DWI is recommended for the pre-therapeutic evaluation of patients with HCC.

Application of postmortem 3D-CT facial reconstruction for personal identification.

Abstract:  Postmortem computed tomography (CT) images can show internal findings related to the cause of death, and it can be a useful method for forensic diagnosis. In this study, we scanned a ready‐made box by helical CT on 2‐mm slices in a mobile CT scanner and measured each side of the box to assess whether reconstructed images are useful for superimposition. The mean difference between the actual measurements and the measurements on the three‐dimensional (3D) reconstructed images (3D‐CT images) is 0.9 mm; we regarded it as having no effect on reconstruction for the superimposition method. Furthermore, we could get 3D‐CT images of the skull, which were consistent with the actual skull, indicating that CT images can be applied to superimposition for identification. This study suggested that postmortem CT images can be applied as superimpositions for unidentified cases, and thinner slices or cone beam CT can be a more precise tool.

What is the origin of intravascular gas on postmortem computed tomography

PURPOSE Intravascular gas is frequently demonstrated on postmortem computed tomography (PMCT). The purpose of this study is to classify the distribution patterns of intravascular gas and to determine its developmental mechanism. METHOD AND MATERIALS The series included 43 cases (mean age, 62 years). All causes of death were non-traumatic (14 cases, sudden death; 29 cases, death caused by known disease). Using a 16-row multi-detector CT, whole body images were obtained with 1.25-mm collimation. Gas in veins, right heart was classified as venous gas. Gas in arteries, left heart was classified as arterial gas. RESULTS PMCT showed intravascular gas in 20 cases. Distribution of gas was divided into 2 patterns; pattern 1 (11 cases): a small volume of venous gas (superior and inferior vena cava, right heart, subclavian veins and brachiocephalic veins) and no arterial gas; pattern 2 (9 cases): both venous (same positions of pattern 1 plus hepatic veins) and arterial gas (left heart, ascending aorta, vertebral arteries and cerebral arteries). CONCLUSION Since imaging findings of pattern 1 are similar to those frequently demonstrated after intravenous contrast-enhanced CT, this gas is presumed to be of exogenous origin from intravenous catheters. In contrast, the gas in pattern 2 may be of endogenous origin, such as decompression disease. Bubbles should move through the ventral side of vessels in the supine position, and subsequently must be trapped by extruded anatomical structures to the ventral side, for example, right ventricle, vertebral and cerebral arteries, hepatic veins and renal veins.

Magnetic resonance imaging of hepatocellular carcinoma: a pictorial review of novel insights into pathophysiological features revealed by magnetic resonance imaging

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Magnetic resonance (MR) imaging is one of the most powerful modalities for the assessment of HCC with sufficient sensitivity and specificity. In addition to its capacity for lesion detection, MR imaging delineates some unique in vivo pathophysiological features of tumors, which cannot be assessed by other modalities. Chemical shift imaging may depict steatosis of the tumor. Dynamic contrast-enhanced MR imaging is the most powerful tool to assess the vascularity of the tumor, which is closely related to malignant transformation in hepatocarcinogenesis. Diffusion-weighted imaging illustrates the cellularity of the tumor. Super-paramagnetic iron oxide, a liver-specific MR contrast agent accumulating in Kupffer cells, enables detection of the hepatocellular architecture in the lesion. Recently, a new liver-specific MR contrast agent, gadoxetic acid [gadolinium-ethoxybenzyl (Gd-EOB)-diethylenetriaminopentoacetic acid (DTPA)], has been introduced for clinical imaging. Gd-EOB-DTPA has a significant impact on the imaging of HCC, with potential capacity for the concurrent assessment of vascularity of the tumor and hepatocellular-specific properties within the tumor. Understanding the characteristics of MR imaging methods and contrast agents is essential for the optimal diagnosis and characterization of HCCs.

Prognostic relevance of apparent diffusion coefficient obtained by diffusion‐weighted MRI in pancreatic cancer

Diffusion‐weighted magnetic resonance imaging (DW‐MRI) is utilized as a method of oncologic imaging for predicting treatment outcomes. This study explored the role of DW‐MRI in the treatment of patients with resected pancreatic cancer by comparing apparent diffusion coefficient (ADC) values with clinicopathological findings and survival rates.

Massive gas embolism revealed by two consecutive postmortem computed-tomography examinations

We present a case of unusual gas embolism in a 73-year-old man who was found in a state of cardiopulmonary arrest with an oxygen-supply tube connected to an intravenous catheter inserted into his median cubital vein. Postmortem computed tomography (PMCT) performed 27 h after death showed systemic gas distribution including intravascular gas, pneumothorax, pneumoperitoneum, pneumomediastinum, pneumoretroperitoneum and gastric emphysema. A second PMCT scan performed 116 h after death showed a marked decrease of air inside the body. The current case shows the importance of PMCT for visualization, quantification, and preservation of evidence for establishment of the cause of death in cases with suspected gas embolism. Our findings also indicate that performance of two PMCT examinations may be useful for differentiation of embolized gas from gas produced by putrefaction.

A pictorial review of benign hepatocellular nodular lesions: comprehensive radiological assessment incorporating the concept of anomalous portal tract syndrome

Background/purposeAlthough the pathological categorization system advocated by the International Working Party (IWP) on Terminology has been helpful in categorizing benign hepatocellular lesions, the diverse clinicopathological features of the lesions still cause confusion of diagnosis in clinical settings. Recently, an integrated disease concept termed “anomalous portal tract syndrome” (APTS) has been proposed as a congenital anomaly of the portal tract, being a single unifying etiological factor underlying the disorder. In this article, we discuss the radiological features of benign nodular hepatocellular lesions incorporated in the concept of APTS.MethodsWe systematically reviewed the literature on benign hepatocellular lesions based on the concept of APTS, as well as standard IWP terminology. For this pictorial review, we selected six representative cases and assessed the radiological features of the cases based on the concept of APTS.ResultsThe comprehensive assessment based on APTS enabled the systematic categorization of benign hepatocellular lesions, including nodular regenerative hyperplasia, large regenerative nodules, partial nodular transformation, focal nodular hyperplasia, and hepatocellular adenoma, and was helpful in understanding the overlapping features of these lesions.ConclusionsAlthough the disease concept of APTS is still evolving, it is nonetheless helpful in comprehensively understanding the clinicopathological and radiological features of various benign hepatocellular lesions.

Sarcoidosis presenting as prepatellar bursitis.

A 61-year-old woman complained of a subcutaneous mass in her right knee. MR images revealed a well-defined subcutaneous mass in the prepatellar region, containing some fluid and foci of short T2. The lesion showed some marginal contrast uptake after an administration of meglumine gadopentetate (Gd-DTPA), consistent with prepatellar bursitis. The pathological specimen, however, revealed subcutaneous sarcoidosis involving the bursa.

Applicability of facial soft tissue thickness measurements in 3-dimensionally reconstructed multidetector-row CT images for forensic anthropological examination

PURPOSE The purpose of this study is to assess the applicability of facial soft tissue measurements using 3-dimensional reconstructed MDCT and to compare the results with previously reported Japanese data. METHODS AND MATERIALS This study included 50 Japanese cadavers who underwent postmortem whole body 16-detector CT within 0-3 days after death. Using 3-D workstation, 10 anthropological measuring points were located and the soft tissue thicknesses were measured. The differences between the acquired thickness and the previously reported Japanese average thickness were statistically analyzed. RESULTS All measuring points were readily determined on the 3-dimensional reconstructed images. Previous Japanese cadaveric data was thinner than our data in almost all sites except for 1 measuring point (mid-philtrum). Previous living Japanese data was thicker than ours except for 1 measuring point (end of nasal). CONCLUSION Facial soft tissue thickness was easily assessed using 3-D reconstructed MDCT images. At many measuring points, our results were thicker than previously reported cadaveric data and were thinner than the data from live persons.