Biomedical subjects

Shigeru Nawano

Publications and source records attributed to Shigeru Nawano.

14 recordsLinked to original sources

PubMed2006

Hepatic metastases: diffusion-weighted sensitivity-encoding versus SPIO-enhanced MR imaging.

PURPOSE: To retrospectively compare accuracy of diffusion-weighted (DW) single-shot echo-planar imaging with sensitivity encoding (SENSE) with that of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the evaluation of hepatic metastases due to extrahepatic malignancies. MATERIALS AND METHODS: Patients provided informed consent; ethics committee approval was not required. The data of 24 patients (16 men, eight women; age range, 41-68 years; mean age, 61.9 years) with 40 resected hepatic metastases were retrospectively reviewed. Before SPIO administration, DW SENSE imaging and T2-weighted fast spin-echo (SE) and T1-weighted dual-echo fast field-echo (FFE) MR imaging were performed. After SPIO administration, T2-weighted fast SE, T1-weighted dual-echo, and T2*-weighted FFE MR examinations were performed. Images were divided into two sets: The SPIO-enhanced MR image set consisted of pre- and postcontrast T2-weighted fast SE and dual-echo T1-weighted FFE images and postcontrast T2*-weighted FFE images. The DW SENSE image set included DW SENSE images and precontrast T2-weighted fast SE and dual-echo T1-weighted FFE images. Three radiologists individually interpreted these images and sorted the confidence levels for presence of hepatic metastasis in each section into five grades. Area under the receiver operating characteristic (ROC) curve (A(z)) was calculated for each image set. RESULTS: Hepatic metastases showed higher signal intensity on DW SENSE images than on T2-weighted fast SE images. Conversely, signals from vessels and cysts were suppressed with DW SENSE imaging. ROC analysis showed higher A(z) values when the DW SENSE image set was interpreted (0.90) than when the SPIO-enhanced MR image set was interpreted (0.81). The sensitivity and specificity, respectively, of total cases were 0.66 and 0.90, for the SPIO-enhanced MR image set and 0.82 and 0.94 for the DW SENSE image set. During SPIO-enhanced MR image interpretation, lesions 1 cm in diameter or smaller showed significantly lower sensitivity than lesions larger than 1 cm in diameter. During both interpretation sessions, left lobe lesions showed significantly lower sensitivity than right lobe lesions. CONCLUSION: Combined reading of DW SENSE images and T2-weighted fast SE and dual-echo T1-weighted FFE MR images showed higher accuracy in the detection of hepatic metastases than did reading of SPIO-enhanced MR images.

Adult↗

PubMed2006

The effect of simultaneous use of respiratory triggering in diffusion-weighted imaging of the liver.

OBJECTIVE: To determine the effect of simultaneous use of respiratory triggering in hepatic diffusion-weighted imaging (DWI), we compared DWI with respiratory triggering (RT-DWI) and DWI under free breathing (FB-DWI) in terms of relative contrast between hepatic tumor and surrounding liver parenchyma, apparent diffusion coefficient (ADC) measurement, and frequency of respiratory misregistration. MATERIALS AND METHODS: Thirty patients (21 men, 9 women, aged 25 to 80 years) with liver metastasis or hepatocellular carcinoma in the right hepatic lobe were examined with RT- and FB-DWI. In patients having multiple tumors, up to 3 lesions were selected by mutual agreement of 2 diagnostic radiologists. Finally, 59 nodules were selected for evaluation. Relative contrast ratio (RCR) between the lesions and surrounding parenchyma and ADC were measured in each hepatic lesion in each sequence. The differences in RCR and ADC between RT- and FB-DWI were statistically analyzed using Wilcoxon's signed rank test. The frequency of respiratory misregistration advents in each sequence was visually evaluated by the 2 diagnostic radiologists and assessed using McNemar's test. RESULTS: RCRs were significantly higher in RT- than in FB-DWI (P<0.001). The difference in ADC between the 2 sequences was not significant. However, ADCs tended to be more scattered in FB- than in RT-DWI. The frequency of respiratory misregistration advents was significantly higher in FB- than in RT-DWI. CONCLUSION: FB- was inferior to RT-DWI in both contrast between tumors and surrounding liver parenchyma and in accuracy of ADC measurement as far as the numbers of excitation in each sequence were the same. For preoperative examination of hepatic resection, RT- is more suitable than FB-DWI.

Adult↗

PubMed2005

Phase II study of oral fludarabine phosphate in relapsed indolent B-Cell non-Hodgkin's lymphoma.

PURPOSE: Although intravenous (IV) fludarabine phosphate is effective against indolent B-cell non-Hodgkin's lymphoma (B-NHL), IV administration for 3 to 5 consecutive days is inconvenient in an outpatient setting. To assess the efficacy and toxicity of oral fludarabine phosphate in patients with indolent B-NHL, we conducted a multicenter phase II study. PATIENTS AND METHODS: Patients with relapsed indolent B-NHL received fludarabine phosphate tablets orally once daily on days 1 through 5 every 28 days for three to six cycles. The efficacy was separately analyzed in a mantle-cell lymphoma (MCL) cohort and indolent B-NHL except for MCL (IL) cohort. The primary end point was the overall response rate (ORR). RESULTS: Fifty-two patients, including 46 in the IL cohort (41 with follicular lymphoma) and six in the MCL cohort, were registered, and all patients were eligible. Forty-one patients (79%) had received rituximab as prior therapy. In the IL cohort, the ORR and complete response rate were 65% (30 of 46 patients; 95% CI, 50% to 79%) and 30% (14 of 46 patients; 95% CI, 18% to 46%), respectively. One of six patients with MCL achieved a partial response. The median times to treatment failure for the 46 patients in the IL cohort and for the six patients in the MCL cohort were 8.6 and 6.1 months, respectively. Hematologic toxicities, including grade 4 neutropenia (37%), were the most frequent toxicities, and nonhematologic toxicities were mild. CONCLUSION: Oral fludarabine phosphate is highly effective in patients with relapsed indolent B-NHL who have mostly been pretreated with rituximab and is more convenient than the IV formulation.

Administration, Oral↗

PubMed2005

Phase I study of radioimmunotherapy with an anti-CD20 murine radioimmunoconjugate ((90)Y-ibritumomab tiuxetan) in relapsed or refractory indolent B-cell lymphoma.

We conducted a phase I study to evaluate the safety and efficacy of radioimmunotherapy with yttrium-90-ibritumomab tiuxetan (Y2B8) in Japanese patients with relapsed or refractory indolent B-cell lymphoma. Indium-111-labeled ibritumomab tiuxetan (In2B8; 3.5 or 5 mCi [129.5 or 185 MBq]) was administered on day 1, followed by serial gamma-camera imaging to investigate the distribution of In2B8 in the whole body of patients and to judge the feasibility of Y2B8 administration. Y2B8 with a dose of 0.3 mCi/kg (11.1 MBq/kg) or 0.4 mCi/kg (14.8 MBq/kg) was administered on day 8. Grade 4 neutropenia and grade 3 thrombocytopenia were observed in three of nine of the patients evaluated for safety. Critical toxicities (prolonged thrombocytopenia or severe non-hematological toxicities) were observed in two of six patients in the 0.4 mCi/kg (14.8 MBq/kg) dose group but were not seen in any of the three patients in the 0.3 mCi/kg (11.1 MBq/kg) dose group. The non-hematological toxicities of the nine patients were of grade 2 or less, except in two patients who had been heavily treated previously. They experienced critical toxicities such as infection, diarrhea, hyponatremia and prolonged thrombocytopenia, as well as other frequent grade 2 non-hematological toxicities. Although the pharmacokinetic profiles were similar to those in the US study, one of the two patients was clarified retrospectively as showing abnormal biodistribution of In2B8 in the bone marrow, as judged by an independent third party panel of radiologists. Five of the 10 participants achieved complete responses or unconfirmed complete responses and two partial responses. In conclusion, the recommended dose of Y2B8 for the subsequent phase II study for Japanese patients is 0.4 mCi/kg (14.8 MBq/kg). This dose of radioimmunotherapy was feasible when patients with altered biodistribution of In2B8 were excluded, and it was highly effective. (Cancer Sci 2005; 96: 903-910).

Adult↗

PubMed2004

Optimization of Gd-DTPA-enhanced balanced turbo field echo sequence in abdominal imaging: a basic study.

PURPOSE: To determine the optimum imaging conditions for the balanced turbo field echo (bTFE) sequence in abdominal imaging, we performed phantom experiments and scanning of a normal volunteer while noting the correlation among signal intensity, k-space ordering, flow velocity and Gd-DTPA concentration. MATERIALS AND METHODS: Initially, the abdomen of a healthy volunteer and some samples (water, blood and bovine albumin solutions with various Gd-DTPA concentrations, and olive oil) were examined with the bTFE sequence under various conditions to define the correlation among signal intensity, k-space ordering and Gd-DTPA concentration. Another experiment was performed to assess the correlation between the flow velocity and Gd-DTPA concentration. With the centric-bTFE sequence, we measured the signal intensity of water samples having various Gd-DTPA concentrations flowing in a long tube with an internal diameter of 4 mm. RESULTS: The experiments revealed the following issues: (i) The contrast of bTFE images was much influenced by k-space ordering; (ii) Gd-DTPA did not exhibit an overt enhancement effect in water and blood under stable conditions; (iii) The signal intensity of moving water decreased in centric-bTFE images, and this signal drop became more significant as the fluid speed increased; and (iv) Gd-DTPA decreased the range of signal loss in the moving fluid; however, this effect had no correlation with Gd-DTPA concentration. CONCLUSION: When the bTFE sequence was employed for abdominal imaging, centric view ordering, fat suppression and Gd-DTPA contrast enhancement were assumed to be necessary.

Abdomen↗

PubMed2004

Optimization of Gd-DTPA-enhanced balanced turbo field echo sequence in abdominal imaging: clinical application.

PURPOSE: We performed MRI examinations of patients in order to confirm the enhancement effect of the balanced turbo field echo (bTFE) sequence with centric view ordering and SPIR (SPIR-centric-bTFE) as mentioned in the prior paper, and to evaluate the actual image quality of this sequence. MATERIALS AND METHODS: The upper abdomens of 30 patients with various abdominal disorders were examined with the SPIR-centric-bTFE sequence before and after Gd-DTPA administration. To assess the enhancement effect of Gd-DTPA, ROI measurements were taken in the aorta, superior mesenteric artery, portal vein, liver and bile juice in the common bile duct in each patient both in pre- and postcontrast images. Visual evaluations were also carried out in order to depict the peripheral vessels in the peritoneal fat and the apparent brightness of the soft-tissue organs. RESULTS: In all patients, the signal of the arteries after Gd-DTPA administration increased by about 50% compared with precontrast images. On the other hand, the veins and the liver showed a signal gain of less than 20% in postcontrast images. Consequently, only the signal of the arteries appeared enhanced in the postcontrast images. The visual evaluation revealed that postcontrast SPIR-centric-bTFE acquisition can depict the thin vessels clearly and the abdominal soft-tissue organs brightly. CONCLUSION: The balanced turbo field echo sequence with centric view ordering and SPIR after Gd-DTPA injection was considered the most appropriate protocol when this sequence was employed for abdominal imaging.

Blood Flow Velocity↗

PubMed2004

Diffusion-weighted imaging of breast cancer with the sensitivity encoding technique: analysis of the apparent diffusion coefficient value.

PURPOSE: The usefulness of diffusion-weighted imaging (DWI) in the field of neuroradiology has been established. Despite its high contrast resolution, DWI has the disadvantages of susceptibility artifact and chemical shift artifact. We performed DWI of breast cancer with the sensitivity encoding (SENSE) technique. METHODS: The subjects were 60 female patients with breast mass. All patients underwent MRI including SENSE-DWI and were diagnosed histologically. Of these patients, 55 were diagnosed with breast cancer and the remaining five were diagnosed with benign mass. The histological diagnoses of breast cancer were as follows: 39 cases of invasive ductal carcinoma (IDC); 11 cases of IDC with a predominant intraductal component and non IDC (pure or predominant NIDC); and five cases of special types of cancer. The MR system used was a Gyroscan Intera 1.5T (Philips Medical Systems). In addition to routine MRI for breast cancer, including contrast-enhanced dynamic, SENSE-DWI was obtained. The accuracy of the positional information of SENSE-DWI was visually compared with that of conventional images. The apparent diffusion coefficient (ADC) values of breast mass were analyzed with SENSE-DWI. RESULTS: The accuracy of positional information was adequate for diagnosing of all patients. The mean ADC value of breast cancer was 1.021x10(-3) mm2/s and that of benign mass was 1.488x10(-3) mm2/s (p=0.0002). The mean ADC value of IDC was 0.968x10(-3) mm2/s and that of pure or predominant NIDC was 1.218x10(-3) mm2/s (p=0.0011). CONCLUSION: SENSE-DWI was of sufficient quality to support diagnosis of breast mass. SENSE-DWI may permit the acquisition of more detailed information about lesions, including tumor cellularity, that is difficult to obtain with conventional techniques.

Artifacts↗

PubMed2004

Volume reduction surgery for advanced hepatocellular carcinoma.

PURPOSE: The aim of this study was to evaluate the prognostic impact of reductive surgery on the survival of patients with advanced hepatocellular carcinoma (HCC). METHODS: Eligible patients had a main tumor greater than 10 cm in diameter with multiple intrahepatic metastases (>5 nodules), and good liver function (Child-Pugh class A), but no tumor thrombus in the main portal vein. The main tumor was surgically removed but the metastases were not removed and were treated with repeated transcatheter hepatic arterial chemo-embolization (TAE). RESULTS: From Jun 1997 to May 2003, 13 patients (median age 61 years, range: 48-74) were prospectively enrolled. The median diameter of the main tumor was 14 cm (range 11.5-18.0). No major surgical complications were observed and the median hospital stay was 12 days (range 7-20). The first TAE was performed 1 month after hepatectomy in all patients and was repeated for median of 5 (range: 1 to 16) times. Complete remission was observed in two patients. One patient had recurrence afterwards but another patient survived 41 months without recurrence. Three patients survived more than 3 years. The overall 1-, 3-, and 4-year survival rates of the 13 patients were 67.7%, 40.6%, and 40.6%, respectively. CONCLUSIONS: Volume reduction surgery followed by TAE might prolong the survival of patients with a large HCC and intrahepatic metastases, especially those with a main tumor on the right side.

Aged↗

PubMed2004

Diffusion-weighted single shot echo planar imaging of colorectal cancer using a sensitivity-encoding technique.

BACKGROUND: We wanted to determine the feasibility of diffusion-weighted single shot echo planar imaging using a sensitivity-encoding technique (SENSE-DWI) in depicting colorectal cancer. METHODS: Forty-two patients with sigmoid colon cancer and rectal cancer, all proven pathologically, were examined on T2-turbo spin echo (TSE) and SENSE-DWI. No bowel preparation was performed before examination. The b-factors used in SENSE-DWI were zero and 1000 s/mm(2). In 10 randomly selected cases, the images whose b-factors were 250 and 500 s/mm(2) were also obtained. The reduction factor of SENSE was 2.0 in all sequences. Two radiologists evaluated the obtained images from the viewpoints of tumor detectability, image distortion and misregistration of the tumors. The apparent diffusion coefficients (ADCs) of the tumors and urine in the urinary bladders in each patient were measured to evaluate the correlation between ADC and pathological classification of each tumor. RESULTS: All tumors were depicted hyperintensely on SENSE-DWI. Even though single shot echo planar imaging (EPI) was used, the image distortion and misregistration was quite pronounced because of simultaneous use of SENSE. On SENSE-DWI whose b-factor was 1000 s/mm(2), the normal colon wall and feces were always hypointense and easily differentiated from the tumors. The mean ADC value of each tumor was 1.02 +/- 0.1 (x 10(-3)) mm(2)/s. No overt correlation can be pointed out between ADC and pathological classification of each tumor. CONCLUSION: SENSE-DWI is a feasible method for depicting colorectal cancer. SENSE-DWI provides strong contrast among colorectal cancers, normal rectal wall and feces.

Adult↗

PubMed2004

[Evaluation of pancreatic cancer extent using balanced turbo field echo (bTFE)].

PURPOSE: Recent advances in MR system technology have allowed for the development of new imaging techniques. Balanced turbo field echo (bTFE) is one such example. The purpose of this study was to evaluate the usefulness of bTFE for evaluating pancreatic cancer extent. MATERIALS AND METHODS: 45 patients with pathologically proven pancreatic cancer were examined with bTFE. The images obtained were evaluated by the consensus of two radiologists, from the following viewpoints: tumor detection and vascular invasion, e.g., celiac axis (CA); superior mesenteric artery (SMA); portal vein (PV); and splenic artery (SA). The results of vascular evaluation were compared with those of dynamic CT. RESULTS: All tumors were demonstrated on bTFE images, however, tumors in the pancreatic head were less clear than those in the pancreatic body. Vascular evaluation on bTFE images was in good agreement with that on dynamic CT scan. CONCLUSION: bTFE is a useful method for evaluating pancreatic cancer extent. Because image quality does not show overt changes in this sequence as time passes, unlike so-called dynamic study, not only are divided scans or respiration-trigered scans available, but repeated scans and multi-directional image acquisition can be performed as well.

Adult↗

PubMed2002

Efficacy of MR mammography (MRM) in providing preoperative locoregional information on breast cancer: correlation between MRM and histological findings.

RATIONALE AND OBJECTIVES: To assess the efficacy of MRM in providing preoperative locoregional information on patients with breast cancer. METHODS: MRI was performed on 62 female breast cancer patients. A 1.5T MR-system was used to acquire fat-suppressed T(1)WI, T(2)WI and dynamic-contrast-enhanced images with an SPGR pulse sequence. The extent of the cancer measured with MRM was confirmed histologically in all patients. RESULTS: The size obtained from MRM correlated well with the size obtained histologically, including intraductal spread of cancer (R: 0.853). As for shape, the round/oval type evident from MRM correlated more accurately (R: 0.934) than the ill-defined type associated with a linear and/or clumped enhanced area (R: 0.744). The difference between the size obtained from MRM and the size obtained histologically, including IDS, was less than 15 mm in the majority of patients (93.5%). CONCLUSIONS: MRM accurately reveals the extent of cancer, including IDS, and is effective at providing preoperative locoregional information for breast-conserving therapy for breast cancer.

Adult↗

PubMed2002

[Current status of nuclear medicine clinical application of FDG-PET for cancer diagnosis. Lung cancer].

Recent advances in small cyclotrons, PET scanners, and image-processing software have made it possible to apply FDG-PET for clinical use, especially for tumor imaging. Although the efficacy of FDG-PET for several tumors remains a problem under discussion, the efficacy of PET for lung cancer has been studied in great detail and has already been established. The roles of FDG-PET for lung cancer management are, roughly speaking, 1) characterization of pulmonary nodules, 2) staging of lung cancer, 3) monitoring therapeutic effect, and 4) early diagnosis of tumor recurrence. We examined the usefulness of FDG-PET for lung cancer by analyzing our own data and reviewing recent reports. Two image-processing techniques, the image fusion technique and the respiratory-gated data-acquisition method, are also introduced in this article. FDG-PET is a promising method of anatomical imaging that is complementary to such techniques as CT and MRI. It may obtain a more important position among imaging modalities in the future.

Diagnosis, Differential↗

PubMedDate not supplied

Thymic MALT lymphoma: MR imaging findings and their correlation with histopathological findings on four cases.

There has been no report on the MRI findings of primary thymic MALT lymphoma. We report the correlation between MRI findings and histopathology in four cases of this entity. While primary thymic MALT lymphomas exhibited diverse characteristics, the cystic components inside, which were clearly depicted on T2-weighted images, were considered to be pathognomonic. Primary thymic MALT lymphoma should be considered as one of the differential diagnoses of anterior mediastinal tumors having multilocular cysts that arise in patients with immunological abnormalities.

Adult↗

PubMedDate not supplied

Positron emission tomography with F-18 fluorodeoxyglucose in evaluating colorectal hepatic metastasis down-staged by chemotherapy.

BACKGROUND: The efficacy of positron emission tomography with 18F fluoro-2-deoxy-D-glucose (FDG-PET) is obscure in evaluating viability or the extent of colorectal hepatic metastasis (CHM), down-staged by chemotherapy. PATIENTS AND METHODS: A retrospective lesion-by-lesion analysis was performed for seven consecutive patients, who had received rescue hepatectomy for initially unresectable CHM, in order to evaluate the correlation between results of imaging modalities and the corresponding pathology. RESULTS: The sensitivity and positive predictive value of the conventional modalities (CT and MRI) were 92% and 42%, respectively, while the sensitivity, specificity, positive predictive value and negative predictive value of FDG-PET were 58%, 100%, 100% and 75% respectively. The sensitivity of FDG-PET was 100% in evaluating the viability of tumors >2 cm, however, this fell to 17% in tumors <2 cm. CONCLUSION: FDG-PET is effective in assessing the viability of tumors >2 cm, but not those <2 cm, in patients with CHM down-staged by chemotherapy.

Adult↗