Biomedical subjects

Shinichi Hori

Publications and source records attributed to Shinichi Hori.

17 recordsLinked to original sources

PubMed2006

Improvement of low-contrast detectability in low-dose hepatic multidetector computed tomography using a novel adaptive filter: evaluation with a computer-simulated liver including tumors.

PURPOSE: The purpose of this study was to investigate how much radiation dose can be reduced without loss of low-contrast detectability with a newly developed adaptive noise reduction filter in hepatic multidetector computed tomography (MDCT) scans by using a computer-simulated liver phantom. MATERIALS AND METHODS: Simulated CT images, including liver and intrahepatic tumors, were mathematically constructed using a computer workstation to evaluate low-contrast detectability by the observer performance test. Milliampere second for construction of simulated images were 60, 80, 100, and 120 mAs (low dose) and 160 mAs (standard dose) at 120 kVp. Images with 60, 80, 100, and 120 mAs were postprocessed with the adaptive noise reduction filter. A total of 432 images were prepared and receiver operating characteristic (ROC) analysis was performed by 5 radiologists. The detectability of simulated tumor by radiologists was estimated with the area under the ROC curves (Az values). In addition, we visually evaluated CT images of 15 patients with chronic liver damage for graininess of the liver parenchyma, sharpness of the liver contour, conspicuity and marginal sharpness of the liver tumors, and overall image quality. RESULTS: The mean Az value at 0.777 (60 mAs), 0.828 (80 mAs), and 0.844 (100 mAs) without filter was significantly lower than that of 160 mAs without filter (P < 0.001, 60 mAs; P = 0.010, 80 mAs; P = 0.040, 100 mAs). There was no statistical difference between the mean Az value at 80 mAs with and 160 mAs without the adaptive noise reduction filter (P = 0.220) and 100 mAs with and 160 mAs without the adaptive noise reduction filter (P = 0.979). In the visual evaluation of patient livers, there was no statistical difference in the graininess and sharpness of the liver, the conspicuity and marginal sharpness of the tumor, and the overall image quality between standard-dose and filtered low-dose images (Wilcoxon signed rank test, P > 0.05). CONCLUSION: The radiation dose can be reduced by 50% without loss of nodule detectability by applying the adaptive noise reduction filter to simulated and patient liver images obtained at MDCT.

Aged↗

PubMed2006

[A case of postoperative liver metastasis from bile duct carcinoma responding to transarterial chemoembolization].

A 77-year-old man underwent pylorus-preserving pancreatoduodenectomy for bile duct carcinoma in October 2000. Histological diagnosis was moderately-differentiated tubular adenocarcinoma, pT 2 (ss, pHinf 0, pPanc 1, pPV 0, pA 0), pN 0, and final Stage II. The patient was periodically observed after operation. In September 2003, follow-up abdominal CT examinations revealed a liver tumor, 89 x 62 x 60 mm in size, at the anterior segment. Transarterial chemoembolization with 5-FU, epirubicin, mitomycin C and superabsorbent polymer microsphere was initiated under the diagnosis of liver metastasis. After completion of 4 chemoembolizations, the tumor responded partially and diminished to 50 x 16 x 14 mm in CT and superparamagnetic iron oxide-enhanced MRI. Currently, the patient is free from any signs of relapse.

Adenocarcinoma↗

PubMed2005

A computer-simulated liver phantom (virtual liver phantom) for multidetector computed tomography evaluation.

OBJECTIVE: The purpose of study was to develop a computer-simulated liver phantom for hepatic CT studies. A computer-simulated liver phantom was mathematically constructed on a computer workstation. MATERIALS AND METHODS: The computer-simulated phantom was calibrated using real CT images acquired by an actual four-detector CT. We added an inhomogeneous texture to the simulated liver by referring to CT images of chronically damaged human livers. The mean CT number of the simulated liver was 60 HU and we added numerous 5-to 10-mm structures with 60+/-10 HU/mm. To mimic liver tumors we added nodules measuring 8, 10, and 12 mm in diameter with CT numbers of 60+/-10, 60+/-15, and 60+/-20 HU. Five radiologists visually evaluated similarity of the texture of the computer-simulated liver phantom and a real human liver to confirm the appropriateness of the virtual liver images using a five-point scale. RESULTS: The total score was 44 in two radiologists, and 42, 41, and 39 in one radiologist each. They evaluated that the textures of virtual liver were comparable to those of human liver. CONCLUSIONS: Our computer-simulated liver phantom is a promising tool for the evaluation of the image quality and diagnostic performance of hepatic CT imaging.

Computer Simulation↗

PubMed2005

[A case of advanced hepatocellular carcinoma with tumor thrombus treated by transarterial chemoembolization therapy using cisplatin (CDDP) with DSM and SAP-MS].

A 78-year-old woman with advanced HCC had been treated by transarterial chemoembolization with epirubicin, however, tumor progression was not controlled and a tumor thrombus was found in the portal vein trunk. A new treatment method for transarterial chemoembolization using CDDP with DSM and SAP-MS was introduced. Marked regression of hepatic lesions and portal vein tumor thrombus was observed after two sessions. No adverse effect was found. The patient has been controlled without tumor recurrence and elevation of tumor marker for 14 months. A new treatment protocol will be useful for patients with far advanced hepatocellular carcinoma with portal vein tumor thrombus.

Aged↗

PubMed2004

Effect of contrast material injection duration and rate on aortic peak time and peak enhancement at dynamic CT involving injection protocol with dose tailored to patient weight.

PURPOSE: To investigate the effect of duration and rate of contrast material injection on aortic peak time and peak enhancement in an injection protocol in which the contrast material dose is adjusted according to patient weight. MATERIALS AND METHODS: One hundred ninety-nine patients were randomly divided into three groups in which the fixed duration of contrast material injection was 25 seconds (group A) or 35 seconds (group B) or the fixed injection rate was 4.0 mL/sec (group C). Computed tomography (CT) at the L3 vertebral level was performed before and after contrast material injection. Aortic peak time, aortic peak enhancement, and period when aortic enhancement is 200 HU or greater (T200) were calculated. The Pearson product-moment correlation coefficient (r) was used to investigate relationships between patient weight and aortic peak time, aortic peak enhancement, and T200 in each group. RESULTS: A significant correlation between aortic peak time and patient weight (r = 0.91, P <.001) was observed in group C. No significant correlations between patient weight and aortic peak time were observed in group A (r = 0.16, P =.21) or B (r = -0.05, P =.69). A significant inverse correlation between aortic peak enhancement and patient weight (r = -0.70, P <.001) was observed in group C. No significant correlations between patient weight and aortic peak enhancement were observed in group A (r = 0.09, P =.48) or B (r = 0.10, P =.41). A significant correlation between T200 and patient weight (r = 0.72, P <.001) was observed in group C. No significant correlations between patient weight and T200 were observed in group A (r = 0.12, P =.34) or B (r = 0.001, P =.99). CONCLUSION: Aortic peak time, aortic peak enhancement, and T200 were closely related to injection duration in the protocol with contrast material dose determined according to patient weight.

Adult↗

PubMed2004

Pulmonary nodules at chest CT: effect of computer-aided diagnosis on radiologists' detection performance.

PURPOSE: To evaluate the effect of computer-aided diagnosis (CAD) on radiologists' detection of pulmonary nodules. MATERIALS AND METHODS: Fifty chest computed tomographic (CT) examination cases were used. The mean nodule size was 0.81 cm +/- 0.60 (SD) (range, 0.3-2.9 cm). Alternative free-response receiver operating characteristic (ROC) analysis with a continuous rating scale was used to compare the observers' performance in detecting nodules with and without use of CAD. Five board-certified radiologists and five radiology residents participated in an observer performance study. First they were asked to rate the probability of nodule presence without using CAD; then they were asked to rate the probability of nodule presence by using CAD. RESULTS: For all radiologists, the mean areas under the best-fit alternative free-response ROC curves (Az) without and with CAD were 0.64 +/- 0.08 and 0.67 +/- 0.09, respectively, indicating a significant difference (P <.01). For the five board-certified radiologists, the mean Az values without and with CAD were 0.63 +/- 0.08 and 0.66 +/- 0.09, respectively, indicating a significant difference (P <.01). For the five resident radiologists, the mean Az values without and with CAD were 0.66 +/- 0.04 and 0.68 +/- 0.04, respectively, indicating a significant difference (P =.02). At observer performance analyses, there were no significant differences in Az values obtained either without (P =.61) or with (P =.88) CAD between the board-certified radiologists and the residents. For all radiologists, in the detection of pulmonary nodules 1.0 cm in diameter or smaller, the mean Az values without and with CAD were 0.60 +/- 0.11 and 0.64 +/- 0.11, respectively, indicating a significant difference (P <.01). CONCLUSION: Use of the CAD system improved the board-certified radiologists' and residents' detection of pulmonary nodules at chest CT.

Adult↗

PubMed2004

Cisplatin enhances the p53-independent apoptosis induced by a topoisomerase I inhibitor (CPT-11) in the lens epithelial tumors in transgenic mice.

We reported that CPT-11 could induce apoptosis in mouse lens epithelial tumors when it was administered to pregnant alphaT3 mice which developed epithelial cell carcinoma in situ in the lens in the perinatal period. p53-deficient alphaT3 mice were generated to analyze the influence of p53 status on tumor cells under combined chemotherapy. On the 16-18th gestational day, alphaT3 received a single i.p. administration of both CPT-11 and Cisplatin, and fetal lens epithelial tumors were examined two days later. Apoptosis in the p53-wild-type alphaT3 tumors was observed in a Cisplatin dose-dependent manner. In addition, it was found that Cisplatin augmented CPT-11-induced p53-independent apoptosis in p53-deficient alphaT3 mice.

Animals↗

PubMed2003

Predominance of Th2-promoting dendritic cells in early human pregnancy decidua.

Dendritic cells (DCs) are specialized antigen-presenting cells required for the priming and activation of T cells and promote the differentiation of naïve CD4+ T cells toward the T helper cell type 1 (Th1) or Th2 phenotype. Here, we describe the characterization of CD45+CD3-CD14-CD16-CD19-CD20-CD56-HLA-DRbright DCs from early human pregnancy decidua by flow cytometry. The percentage of DCs to mononuclear cells (leukocytes) in the decidua was significantly higher than that in the peripheral blood. Moreover, decidual DCs expressed costimulatory molecules such as CD80 and CD86 and a mature marker such as CD83 on their surface. The percentage of CD11c+CD123- myeloid DCs in the decidua was significantly higher than that in the peripheral blood. Conversely, the ratio of CD11c-CD123+ lymphoid DCs in the decidua was significantly lower than that in the peripheral blood. The number of interleukin (IL)-12-producing cells in the total DC population and the myeloid DCs in the decidua was significantly lower than that in the peripheral blood. IL-12 secretion by activated decidual myeloid DCs was significantly lower than that by peripheral DCs. Naïve CD4+ T cells primed with decidual myeloid DCs led to a higher percentage of Th2 cells in comparison with that with peripheral myeloid DCs. This finding was abolished by exogenous IL-12 administration with decidual myeloid DCs. Thus, the DCs in the decidua could regulate the Th1/Th2 balance to maintain a Th2-dominant state, leading to maintenance of pregnancy.

Adult↗

PubMed2003

Effect of contrast injection protocol with dose tailored to patient weight and fixed injection duration on aortic and hepatic enhancement at multidetector-row helical CT.

The aim of this study was to investigate the effect of a contrast material injection protocol with dose and injection rate of contrast material tailored to patient weight (dose tailored to patient weight and fixed injection duration). Hepatic helical CT was performed in 92 patients with chronic liver damage with a dose of 1.4 ml (518 mgI) at a rate of 0.056 ml/s per kilogram body weight of Iopamidol 370. Attenuation values of liver and aorta were measured for calculation of maximum aortic and hepatic enhancement, time to maximum hepatic enhancement, and end of hepatic arterial phase. Correlation coefficients between the injection rate and the four parameters were r=0.008, 0.057, 0.167, and 0.036, and there were no statistically significant correlations between the injection rates and the four parameters. In our injection protocol, uniform temporal scan window may be achieved and the injection rate can be reduced in lighter patients without reducing the degree of enhancement in the aorta and the liver.

Aged↗

PubMed2002

Transarterial embolization for large hepatocellular carcinoma with use of superabsorbent polymer microspheres: initial experience.

The authors report the initial experience with transarterial embolization of large hepatocellular carcinoma (HCC) with use of superabsorbent polymer microsphere (SAP-MS) particles. Six patients with nine HCCs (mean diameter, 8.2 cm) underwent 10 embolization procedures. Two patients underwent surgery later. In follow-up, tumor necrosis, postembolization syndrome, and laboratory data were assessed. Complete necrosis in three nodules, nearly complete necrosis in three nodules, and partial necrosis in three nodules were observed. Histologically, SAP-MS occluded intratumoral vessels tightly without ischemic damage of normal hepatic tissue. Postprocedural pain was minimal. No deterioration of liver function occurred. Our initial experience suggests that embolization with use of SAP-MS leads to extensive tumor necrosis of large nodular HCC, sparing use of chemotherapeutic agents.

Aged↗

PubMed2002

Embolization of high flow arteriovenous malformations: experience with use of superabsorbent polymer microspheres.

PURPOSE: To determine efficacy, safety, and requirements for adjunctive embolization or surgery in the treatment of symptomatic arteriovenous malformations (AVMs) with superabsorbent polymer microsphere (SAP-MS) particles. MATERIALS AND METHODS: SAP-MS particles (sodium acrylate and vinyl alcohol copolymer) are nonbiodegradable spheres with a precisely calibrated diameter. SAP-MS particles swell by absorbing fluids and become soft and deformable. Twenty-five patients (16 men, nine women; mean age, 32 y; range 12-66 y) with symptomatic facial (n = 5), upper- (n = 8) and lower- (n = 12) extremity AVMs were treated primarily (n = 23) or preoperatively (n = 2) by transarterial embolization (TAE) treatment with use of SAP-MS particles. Direct puncture embolization (DPE; n = 4) and/or surgical intervention (n = 5; ie, skin graft, resection, or amputation) were required. Surgical specimens from the resected (n = 2) and the amputated (n = 2) patients were evaluated histologically. Follow-up study, including clinical findings and imaging studies, was performed at intervals ranging from 3 months to 1 year. Clinical outcome was evaluated retrospectively, depending on the subjective improvement of symptoms and signs, according to the medical records. RESULTS: Seventy-two TAEs (range, 1-11; mean, 2.8) and 12 DPEs (range, 1-3; mean, 2.4) were performed during the mean follow-up period of 38 months (range, 7-110 mo). Twenty patients (80%) experienced symptom improvement by embolotherapy alone (n = 17) or in combination with surgery (n = 3). One lip and two finger AVMs were totally removed by surgical excision or amputation after TAE treatment. In diffuse upper- (n = 1) and lower- (n = 1) extremity AVMs, the symptoms were uncontrolled. No nerve injury or skin necrosis was observed after TAE treatment with SAP-MS particles. Mucosal necrosis was induced by DPE with ethanol in one patient. Histologically, SAP-MS particles penetrated intralesional vessels and conformed to the vessel lumen, resulting in tight vessel occlusion. Minimal perivascular reaction was observed. CONCLUSION: SAP-MS particles were used safely in TAE treatment of AVM. TAE treatment with use of SAP-MS particles was suitable for certain symptomatic AVMs, but diffuse AVMs remain a challenge and a combination of alternative methods will be necessary for further strategy.

Acrylic Resins↗

PubMed2002

Splenic artery embolization using contour emboli before laparoscopic or laparoscopically assisted splenectomy.

The present study assessed preoperative splenic artery embolization using spherical embolic material, super absorbent polymer microspheres (SAP-MS), before laparoscopic or laparoscopically assisted splenectomy. Distal splenic artery embolization using 250 to 400 microm SAP-MS was performed in nine cases with ITP and in seven cases with the other diseases with splenomegaly. Laparoscopic or laparoscopically assisted splenectomies, including a hand-assisted procedure and the procedure involving left upper minilaparotomy, were done 2 to 4 hours after embolization. Conversion to traditional laparotomy was not required in any of the 16 cases, while conversion to 12-cm laparotomy was required in one case with massive splenomegaly. Mean operating time was 161 minutes, and mean intraoperative blood loss was 290 mL. No major postoperative complications were identified, and only one patient reported postembolic pain before surgery. Preoperative splenic artery embolization using painless embolic material, SAP-MS, would be effective for easy and safe laparoscopic or laparoscopically assisted splenectomy.

Adult↗

PubMed2002

Aortic and hepatic enhancement and tumor-to-liver contrast: analysis of the effect of different concentrations of contrast material at multi-detector row helical CT.

PURPOSE: To investigate the effect of different iodine concentrations of contrast material on aortic and hepatic enhancement and the detectability of hypervascular hepatocellular carcinoma (HCC) with multi-detector row computed tomography (CT) and a uniphasic contrast material injection technique. MATERIALS AND METHODS: Two hundred one patients with known or who were suspected of having HCC underwent multi-detector row CT; 58 patients with hypervascular HCC were identified. First-, second-, and third-phase scanning was started with the aortic arrival times plus 15 seconds, plus 30 seconds, and plus 105 seconds, respectively. All patients were assigned randomly into two groups. Patients in groups A and B received iopamidol with an iodine concentration of 300 mg/mL and 370 mg/mL, respectively, with the same total iodine load per patient per body weight. The liver and aorta enhancement and tumor-to-liver contrast (TLC) were measured. Depiction of hepatic arteries was evaluated visually by two radiologists. RESULTS: During the first phase, aortic enhancement was significantly (P <.01) higher in group B, with no significant difference in hepatic enhancement between the two groups. During the second phase, aortic enhancement was significantly (P <.01) higher in group A, with no significant difference in hepatic enhancement. The TLC was significantly (P <.01) higher in group B during the first phase, but there was no significant difference between the two groups during the second phase. There was no significant difference in any parameters between the two groups during the third phase. Depiction of the hepatic arteries in group B was significantly (P <.05) superior to that in group A. CONCLUSION: In the arterial phase, administration of a higher concentration of contrast material is effective for a significantly higher TLC.

Adult↗

PubMed2002

Manganese deposition in basal ganglia due to perioperative parenteral nutrition following gastrointestinal surgeries.

BACKGROUND/AIMS: Serial changes in blood manganese (Mn) levels and brain MRI examinations following perioperative parenteral nutrition (PN) were investigated. METHODS: Six cases undergoing pancreatoduodenectomy (PD), 4 cases undergoing thoracic esophagectomy (TE), 18 cases undergoing total gastrectomy (TG) and 20 cases undergoing colorectal surgeries (CR) with daily administration of 20 micromol of Mn per day were studied. Cases undergoing PD, TE, TG or CR without Mn administration served as controls. RESULTS: Hyperintense lesions in the basal ganglia on T1-weighted MRI and elevated blood Mn levels were recognized after PN in 4 of 6 cases in the PD group, in 3 of 4 cases in the TE group, in 1 of 18 cases in the TG group and in 2 of 20 cases in the CR group. No abnormalities were recognized in the control groups. CONCLUSION: The possible Mn deposition in the basal ganglia caused by perioperative PN should be especially noted in cases undergoing PD or TE.

Adult↗

PubMed2002

The role of PGE(2) in the differentiation of dendritic cells: how do dendritic cells influence T-cell polarization and chemokine receptor expression?

The role of prostaglandin E(2) (PGE(2)) in the function of dendritic cells (DCs), T-cell polarization, and expression of chemokine receptors was evaluated in human cells. Immature DCs were generated from peripheral blood CD14(+) cells using a combination of GM-CSF and interleukin-4 (IL-4) with or without PGE(2). On day 6, maturation of DCs was induced by the addition of tumor necrosis factor alpha with or without PGE(2). DCs harvested on day 6 (immature DCs) or day 9 (mature DCs) were examined using functional assays. In the presence of PGE(2), immature and mature DCs showed, phenotypically, a lower expression of CD1a and, functionally, a higher allostimulatory capacity at a high DC/T-cell ratio than control cells cultured in the absence of PGE(2). DCs cultured in the presence of PGE(2) induced the differentiation of naïve T cells toward a helper T-cell type 1 (Th1) response, which was independent of IL-12 secretion in the basal state despite a slightly lower interferon gamma secretion compared with control cells. However, the function of cytotoxicity-stimulating autologous T cells was not augmented by the addition of PGE(2). Immature DCs expressed the inflammatory chemokine receptors, CCR1 and CXCR4, but not CCR6, regardless of the presence or absence of PGE(2). Mature DCs expressed CCR7 equally, measured using a migration test and the measurement of calcium flux with macrophage inflammatory protein-3beta and reverse transcription-polymerase chain reaction assay in all of the groups. All of these findings suggest that PGE(2) affects the DC-promoted differentiation of naïve T cells to a Th1 response in the basal state, without affecting chemokine receptor expression on DCs.

CD3 Complex↗

PubMedDate not supplied

Contrast enhancement for whole-body screening using multidetector row helical CT: comparison between uniphasic and biphasic injection protocols.

OBJECTIVE: To investigate which is more suitable for whole-body screening with multidetector row CT (MDCT) during one breathhold, a uniphasic or biphasic injection protocol for contrast material. SUBJECTS AND METHODS: Sixty patients received a volume of 1.7 mL x weight (kg) with iopamidol 300 mg iodine/mL. The patients were randomized into two injection protocols: A) a fixed injection rate of 2.0 mL/sec with a 70 sec delay, B) administration of 80% of the contrast material in 40 sec, then administration of the remaining 20% in 20 sec with an 80 sec delay. A helical scan from the apex of the lung to the base of the pelvic cavity was performed during one breathhold. CT attenuation values of the thoracic aorta, pulmonary artery, abdominal aorta, portal vein, superior vena cava (SVC), suprarenal and infrarenal inferior vena cava (IVC), liver, and pancreas were measured. Two radiologists visually assessed the degree enhancement of the IVC. In addition, the two radiologists visually assessed artifacts caused by contrast material in the subclavian vein and SVC using a four-point scale. RESULTS: Enhancement of the SVC in protocol A was significantly better than that in protocol B (p=0.04). Enhancement of the infrarenal IVC and liver in protocol B was significantly better than that in protocol A (p<0.01, p<0.01). Renal enhancement in protocol B was significantly better than that in protocol A (p=0.02). In all patients with both protocols A and B, enhancement of the suprarenal IVC was visually graded as acceptable or good. In all patients with protocol B, enhancement of the infrarenal IVC was graded as acceptable or good. In only 2/3 of patients with protocol A, enhancement of the infrarenal IVC was graded as acceptable or good. There was no significant difference in artifacts in the subclavian vein between the two protocols (p=0.77). Artifacts in the SVC in protocol B were significantly fewer than those in protocol A (p<0.01). CONCLUSION: Protocol B was more suitable for whole-body screening than protocol A, because of better enhancement of the liver and infrarenal IVC and fewer artifacts in the SVC.

Artifacts↗

PubMedDate not supplied

Embolic effects of superabsorbent polymer microspheres in rabbit renal model: comparison with tris-acryl gelatin microspheres and polyvinyl alcohol.

PURPOSE: We have developed a spherical embolic agent, superabsorbent polymer microspheres (SAP-MS). The aim of this study was to examine the embolic effects of SAP-MS in comparison with polyvinyl alcohol (PVA) particles and tris-acryl gelatin microsphere (Embosphere Microsphere; EM) in a rabbit renal model. MATERIALS AND METHODS: The right kidneys of nine rabbits were embolized with the given agents: PVA (180-300 microm) (n=3), EM (100-300 microm) (n=3), and SAP-MS (106-150 microm) (n=3). The embolized kidneys were evaluated by angiography and histology after one week. RESULTS: Renal artery occlusion and prominent coagulative necrosis were confirmed regardless of agent. PVA aggregated in the proximal vessels with tiny fragments migrating into glomeruli. Both EM and SAP-MS traveled distally up to the interlobular artery level, and a single particle achieved cross-sectional vessel occlusion. SAP-MS was markedly swollen, deformed, and conformed to the vessel lumen compared with the constantly spherical EM. Mild perivascular reaction was seen with both microspheres. CONCLUSION: SAP-MS resulted in targeted end-organ infarction in the rabbit renal model and showed different mechanical properties from other agents.

Acrylic Resins↗