Seiji Yamamoto

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.

Combination therapy of in vitro‐expanded natural killer T cells and α‐galactosylceramide‐pulsed antigen‐presenting cells in patients with recurrent head and neck carcinoma

The aim of this clinical trial was to investigate the feasibility of intra‐arterial infusion of in vitro‐expanded Vα24 natural killer T (NKT) cells combined with submucosal injection of α‐galactosylceramide (KRN7000; αGalCer)‐pulsed antigen‐presenting cells (APC). A phase I clinical study was carried out in patients with head and neck squamous cell carcinoma (HNSCC). Patients with locally recurrent HNSCC refractory to standard therapy were eligible. Eight patients received super‐selective transcatheter intra‐arterial infusion of activated Vα24 NKT cells into tumor‐feeding arteries and nasal submucosal injections of αGalCer‐pulsed APC twice with a 1‐week interval. Vα24 NKT cell‐specific immune responses, safety, and antitumor effects were evaluated. The number of Vα24 NKT cells and interferon‐γ‐producing cells in peripheral blood mononuclear cells increased in seven out of eight patients enrolled. Grade 3 toxicity with a pharyngocutaneous fistula related to local tumor reduction was observed in one patient and mild adverse events with grade 1–2 symptoms occurred in seven patients. Regarding the clinical responses, three cases exhibited a partial but significant response, four were classified as stable disease, and one patient continued to develop progressive disease. The use of the intra‐arterial infusion of activated Vα24 NKT cells and the submucosal injection of αGalCer‐pulsed APC has been shown to induce significant antitumor immunity and had beneficial clinical effects in the management of advanced HNSCC. The use of such therapeutic modalities may be helpful in the management of tumors and therefore needs to be explored in further detail. The clinical trial registration number was UMIN000000722. (Cancer Sci 2009; 100: 1092–1098)

Induction of NKT cell-specific immune responses in cancer tissues after NKT cell-targeted adoptive immunotherapy

Vα24 natural killer T (NKT) cells have potent anti-tumor activity. We performed a phase II clinical study in patients with head and neck squamous cell carcinoma (HNSCC) using ex vivo expanded Vα24 NKT cells and α-galactosylceramide (αGalCer; KRN7000)-pulsed antigen-presenting cells (APCs) to investigate the efficacy and induction of NKT cell-specific immune responses. The subjects were 10 patients with locally recurrent and operable HNSCC. One course of nasal submucosal administration of αGalCer-pulsed APCs and intra-arterial infusion of activated NKT cells via tumor-feeding arteries was given before salvage surgery. Anti-tumor effects, NKT cell-specific immune responses in extirpated cancer tissue and peripheral blood, safety, and pathological effects were evaluated. Five cases achieved objective tumor regression. The number of NKT cells increased in cancer tissues in 7 cases and was associated with tumor regression. The combination therapy induced NKT cell-specific immune responses in cancer tissues that were associated with beneficial clinical effects.

Does imaging technology overcome problems of conventional postmortem examination? A trial of computed tomography imaging for postmortem examination.

We used a mobile computed tomography (CT) unit for postmortem examinations of deceased subjects to see how many mistakes on cause-of-death diagnoses were made in Japan. In 5 of 20 cases, the cause of death determined by CT was different from the diagnosis made by superficial postmortem examination. In one case, the superficial examination suggested no trauma, whereas a subdural hematoma was found on cranial CT images. We concluded that postmortem examinations in Japan were not effective when screening for crimes or accidents. Using a mobile CT scanner in postmortem examination may be a viable method of screening for causes of deaths, although it cannot be used as a substitute for autopsy.

Inter- and intratumoral variability in magnetic resonance imaging of pleomorphic adenoma: an attempt to interpret the variable magnetic resonance findings.

Objectives: The purpose of our study was to describe the various magnetic resonance (MR) findings of pleomorphic adenoma and to interpret these findings. Methods: MR studies of 33 pleomorphic adenomas and 13 malignant tumors in the major salivary glands were reviewed. Results: High signal intensity on short-inversion-time inversion recovery (STIR) and T2-weighted (T2W) images, progressive enhancement on dynamic MR images, and high apparent diffusion coefficient (ADC) values on diffusion-weighted (DW) images reflected myxoid-dominant components in pleomorphic adenomas. Hypercellularity with less-myxoid stroma showed reduced signal intensity on STIR and T2W images and also reduced ADC values on DW images, and the peak of time versus signal intensity curves (TICs) was reached earlier on dynamic MR images. Conclusions: The MR images of hypercellularity components in pleomorphic adenoma overlap with those of malignant parotid tumors. Detecting myxoid components by STIR, T2W, DW, and dynamic MR images is useful for predicting whether salivary gland tumors are pleomorphic adenoma or not.

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.

Evaluation of Computed Tomography as a Screening Test for Death Inquest

Abstract:  The Japanese method of inquest, which depends mostly on external examinations, may misdiagnose a considerable number of accidental deaths and suicides as death by disease. We conducted computed tomography (CT) scans of 80 cases for which police concluded death by disease or natural causes based on police investigations into the circumstances and results from external examinations. The cause of death was clearly determined by CT scan in 17 of 80 cases. Ten cases underwent autopsy after the police suspected criminality based on results of the CT examinations. The results suggest CT scan may be a tool for preventing a number of overlooked crimes and accidents in Japan. However, it cannot be a perfect tool for discerning between death by disease and other causes of death without cooperation from the investigative agencies and subsequent forensic examinations such as autopsy and toxicological tests.

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.

Can cervical spine injury be correctly diagnosed by postmortem computed tomography

We discuss the usefulness of postmortem computed tomography (PMCT) by reviewing cases of cervical spine injury. A merit of PMCT is that it can identify injury that cannot be found on autopsy; however, peculiar defects of it may exist. While PMCT can identify bone fractures, it cannot indicate whether the injury was inflicted while the deceased was still alive or not because of its inability to clearly image bleeding around the fracture. Furthermore, CT often misses some types of cervical spine injuries, such as laceration of an intervertebral disk and incomplete fracture of the cervical spine. On the other hand, cervical spine injury on CT images occasionally has an appearance similar to subarachnoid hemorrhage due to rupture of the cerebral artery, indicating that cervical spine injury can be misdiagnosed as a disease by PMCT. When PMCT is used for screening trauma, caution must be observed regarding its limitations. If the possibility of trauma of the neck or head is not completely ruled out from the personal history of the victim, autopsy is strongly recommended, even when PMCT findings indicate that the cause of death may be due to disease, such as subarachnoid hemorrhage.

Chondrosarcoma of the nasal septum

Abstract. The nasal septum is a particularly rare site of origin of chondrosarcoma. Cranial base invasion may be at hand, with such lesions making complete tumor removal difficult. MRI techniques allow precise definition of tumor extent. In the described case, CT and Dynamic MR imaging were performed in a case of chondrosarcoma of the nasal septum. Imaging clearly illustrated size and extent of the mass with central regions of internal calcification. Dynamic MRI was additionally performed, which helped to define the presumed origin of the lesion from the nasal septum.