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Isamu Narabayashi

Publications and source records attributed to Isamu Narabayashi.

At least 19 recordsLinked to original sources
PubMed2006

Diffusion-weighted MR imaging for urinary bladder carcinoma: initial results.

The aim of this study was to demonstrate the feasibility of using diffusion-weighted (DW) magnetic resonance (MR) imaging under free breathing for the detection of a urinary bladder carcinoma. In 15 patients with 17 urinary bladder carcinomas, DW images were obtained in the axial plane under free breathing scanning with a multisection spin-echo type single-shot echo planar sequence with a body coil. DW images were evaluated based on cystoscopic findings. Moreover, the apparent diffusion coefficient (ADC) value was measured in a circular region of interest (ROI) within the carcinoma, urine, normal bladder wall, prostate and seminal vesicle. In the results, on the DW images, all 17 carcinomas were clearly shown as high signal intensity relative to the surrounding structure. The ADC value (x10(-3) mm(2)/s) in the carcinoma was 1.18+/-0.19, which was significantly lower compared with that of urine (3.28+/-0.20), the normal bladder wall (2.27+/-0.24), prostate (transition zone: 1.57+/-0.09, peripheral zone:1.85+/-0.22) and seminal vesicle (2.01+/-0.22). In conclusion, DW images under free breathing enabled the clear detection of the urinary bladder carcinoma, whose ADC values were lower compared with those of the surrounding structure. The DW images may be useful in evaluating tumors invading to the surrounding structures.

Aged↗
PubMed2006

Preoperative esophageal cancer staging: magnetic resonance imaging of lymph node with ferumoxtran-10, an ultrasmall superparamagnetic iron oxide.

BACKGROUND: Accurate detection of metastasis to lymph nodes is an essential component of the approach to treatment. The purpose of this study was to evaluate the utility of magnetic resonance imaging with ferumoxtran-10 in diagnosing lymph node metastasis in esophageal cancer. STUDY DESIGN: Sixteen patients with esophageal cancer who were scheduled for surgical lymph node dissection were enrolled. All patients underwent MRI scanning before and 24 hours after intravenous administration of ferumoxtran-10, an ultrasmall, superparamagnetic iron oxide. The presence or absence of metastasis was identified in lymph nodes by their enhancement patterns. Nonmalignant nodes contained macrophages that phagocytosed ferumoxtran-10. Metastatic nodes exhibited a decrease in phagocytic activity, and consequently showed little or no uptake of ferumoxtran-10. So we subdivided the enhancement patterns into the following three patterns: (A) node having an overall low signal intensity, (B) node having an area of high signal intensity, and (C) node having an overall high signal intensity. We identified that patterns (B) and (C) were metastatic patterns. The imaging results were compared with histopathologic findings. RESULTS: Of the 408 resected lymph nodes, imaging results of 133 nodes could be compared with histopathologic findings. Twenty-four lymph nodes had histopathologic metastases. Using our enhancement criteria, sensitivity was 100%, specificity was 95.4%, and accuracy was 96.2% for diagnosis of metastatic nodes. CONCLUSIONS: Ferumoxtran-10 is useful for characterizing benign or malignant lymph nodes in esophageal cancer patients based on the defined enhancement criteria.

Adult↗
PubMed2006

Preoperative diagnosis of lymph node metastases in gastric cancer by magnetic resonance imaging with ferumoxtran-10.

BACKGROUND: Knowledge regarding the presence and location of lymph node metastasis in gastric cancer is essential in deciding on the operative approach. Lymph node metastases have been diagnosed with imaging tests such as computed tomography (CT) and ultrasonography (US); however, the accuracy of such diagnoses, based on size and shape criteria, has not been adequate. Ferumoxtran-10 (Combidex; Advanced Magnetics) is a lymphotropic contrast agent for magnetic resonance imaging (MRI) whose efficacy for the detection of metastatic lymph nodes in various cancers has been reported by several investigators; however, its efficacy for this purpose has not been reported for gastric cancer. We investigated the efficacy of ferumoxtran-10-enhanced MRI for the diagnosis of metastases to lymph nodes in gastric cancer. METHODS: Seventeen consecutive patients who were diagnosed with a nonearly stage of gastric cancer were enrolled in the study. All the patients were examined by MRI (Signa Horizon 1.5 T; GE Medical; T2*-weighted images) before and 24 h after the intravenous administration of ultrasmall particles of superparamagnetic iron oxide--ferumoxtran-10 (2.6 mg Fe/kg of body weight)--and the presence or absence of metastasis was determined from the enhancement patterns. The imaging results were compared with the corresponding histopathological findings following surgery. RESULTS: Of 781 lymph nodes dissected during surgery, the imaging results of 194 nodes could be correlated with their histopathological findings. Fifty-nine lymph nodes from 11 patients had histopathological metastases. In nonaffected normal lymph nodes, we observed dark signal intensity on MRI caused by the diffuse uptake of the contrast medium by macrophages resident in the lymph nodes, which phagocytose the iron oxide particles of ferumoxtran-10. The number of phagocytic macrophages was decreased in metastatic lymph nodes, and they showed various patterns of decreased uptake of ferumoxtran-10. Three enhancement patterns were observed in lymph nodes: (A) lymph nodes with overall dark signal intensity due to the diffuse uptake of ferumoxtran-10; (B) lymph nodes with partial high signal intensity due to partial uptake; and (C) no blackening of lymph nodes due to no uptake of ferumoxtran-10. Patterns (B) and (C) were defined as metastatic. The sensitivity, specificity, positive predictive value, negative predictive value, and overall predictive accuracy of postcontrast MRI were 100% (59/59), 92.6% (125/135), 85.5% (59/69), 100% (125/125), and 94.8% (184/194), respectively. These parameters for predictive accuracy were much superior to these parameters previously evaluated by CT or US. Nodes in the retroperitoneal and paraaortic regions were more readily identified and diagnosed on the MR images than those in the perigastric region. CONCLUSION: The present study confirmed that ferumoxtran-10-enhanced MRI is useful in the diagnosis of metastatic lymph nodes and that the use of this modality will be helpful in treatment decision-making for gastric cancer patients.

Adult↗
PubMed2006

CT and MR features of sclerosing mesenteritis mimicking a mesenteric metastasis from the carcinoid tumor.

Sclerosing mesenteritis is a rare and benign inflammatory entity characterized by fibrofatty thickening of the mesentery. To our knowledge, there are only a few reports on the features of sclerosing mesenteritis on magnetic resonance (MR) imaging and computed tomography (CT). In this present case, MR imaging demonstrated tissue characterization of fibrosis, and partial maximum intensity projection (MIP) and three-dimensional angiography images obtained using multislice CT clearly revealed the extent of the tumor and the vascular appearance affected by the mass. However, a mesenteric metastasis from the carcinoid tumor may show such imaging features. Therefore, when encountering such a case, we suggest that a tentative diagnosis of sclerosing mesenteritis be made, followed by a biopsy for intraoperative histopathologic analysis to avoid aggressive surgery.

Aged↗
PubMed2006

Comparative study of cerebral blood flow in patients with normal-tension glaucoma and control subjects.

PURPOSE: To evaluate regional cerebral blood flow (rCBF) in normal-tension glaucoma patients (NTGs) compared with normal volunteers (controls) in a pilot study. DESIGN: Observational cohort study. METHODS: The Iodine-123-IMP single photon emission computed tomography (SPECT) scans were acquired in 31 NTGs and 18 age-matched controls. The SPECT images in NTGs were classified and the quantitative rCBF data were compared with controls. RESULTS: Seven of 31 NTGs (22.6%) exhibited an Alzheimer's disease (AD)-like perfusion pattern although none of them were clinically diagnosed with AD. The visual field defect of NTGs with an AD-like pattern progressed more rapidly than NTGs with a normal pattern (P=.132). The rCBF in left parietal regions of NTGs with senile sclerotic or focal ischemic disk was significantly lower than controls (P<.05). CONCLUSIONS: A number of NTGs exhibited an AD-like perfusion pattern, suggesting that some of NTGs and AD patients might have a common pathologic mechanism.

Aged↗
PubMed2006

Differences in heart rate variability in non-hypertensive diabetic patients correlate with the presence of underlying cerebrovascular disease.

We previously showed that diabetes contributes to the development of sclerotic lesions in cerebral arteries. In this study, we attempted to clarify whether differences in heart rate variability in non-hypertensive diabetic patients were dependent on the presence or absence of underlying cerebrovascular disease. Thirty diabetic subjects between 40 and 59 years of age and who had no prior history of hypertension were used in this study. Lacunar lesions (LA) were detected with magnetic resonance imaging and atherosclerotic lesions (AS) were detected using intra- and extracranial magnetic resonance angiography, and by ultrasonographic scanning of the carotid artery. Patients underwent a full clinical laboratory screening and a power spectrum analysis of their heart rate variability. Subjects were divided into two groups: those with and without LA. The low frequency/high frequency ratio (LF/HF ratio) was found to be significantly increased (P<0.01) in subjects with LA (2.2 +/- 0.3) compared to those without LA (1.3 +/- 0.1). When subjects were divided into groups based on their presence or absence of AS, high-frequency power was found to be significantly reduced (P<0.05) in the subjects with AS (12.8 +/- 3.4 ms) compared to those without AS (19.4 +/- 1.7 ms). The LF/HF ratio was found to be significantly increased (P<0.05) in the subjects with AS (2.2 +/- 0.3) compared to those without AS (1.4 +/- 0.1). Our data suggested that atherosclerotic lesions in cerebrovascular diseased linked to decrease of vagal nerve activity in non-hypertensive diabetic patients.

Albuminuria↗
PubMed2006

Dual-phase 3D CT angiography during a single breath-hold using 16-MDCT: assessment of vascular anatomy before laparoscopic gastrectomy.

OBJECTIVE: In this study, we evaluated the efficacy of dual-phase 3D CT angiography (CTA) during a single breath-hold using 16-MDCT in the assessment of vascular anatomy before laparoscopic gastrectomy. MATERIALS AND METHODS: The study involved 20 consecutive patients (10 men, 10 women; mean age, 59 years) scheduled for laparoscopic gastrectomy for the treatment of early gastric cancer. A dual-phase contrast-enhanced CT scan using 16-MDCT was obtained before laparoscopic gastrectomy. After rapid infusion of a nonionic contrast agent, arterial and venous phase scans were obtained serially with an interval of 15 sec during a single breath-hold of 31 sec. Three-dimensional CTA images in the arterial phase (3D CT arteriography) and venous phase (3D CT venography) were individually reconstructed using the volume-rendering technique, and then the images were fused together. We evaluated the detectability of the celiac trunk, left gastric artery (LGA), right gastric artery (RGA), left gastric coronary vein (LCV), Henle's gastrocolic trunk, right gastroepiploic vein (RGEV), and accessory right colic vein on 3D CTA to compare with surgical findings. RESULTS: In all 20 patients, 3D CT arteriography and venography clearly showed the celiac trunk, LGA, RGA, Henle's gastrocolic trunk, RGEV, and accessory right colic vein, which were correctly identified during surgery. The branching pattern of the celiac trunk was classified as Michels type I in 19 patients and Michels type II in one patient. Imaging showed the RGA originating from the proper hepatic artery (PHA) in nine patients; from the gastroduodenal artery (GDA) in seven patients; and from the left hepatic artery (LHA) in four patients. In 12 patients, the LCV joined the portal vein (PV) and in eight, the splenic vein (SV). In all patients, the accessory right colic vein joined the RGEV, and Henle's gastrocolic trunk proximal to the joining point flowed to the superior mesenteric vein (SMV). In all 20 patients, the fused image simultaneously showed arteries and veins around the stomach, with no mismatch between the arterial and venous phase images. In 10 patients, the LCV joined the PV after running along the dorsal side of the PHA, common hepatic artery (CHA), or splenic artery (SA). In eight patients, the LCV joined the SV after running along the ventral side of the PHA, CHA, or SA. In two patients, the LCV joined the PV after running along the ventral side of the CHA, which correlated with the surgical findings. Both the sensitivity and positive predictive values of 3D CTA revealed 100% correct identification of the celiac trunk, LGA, RGA, LCV, Henle's gastrocolic trunk, RGEV, and accessory right colic vein. CONCLUSION: Dual-phase 3D CTA using 16-MDCT clearly revealed individual arteries and veins around the stomach before laparoscopic gastrectomy. The fused image of 3D CT arteriography and venography during a single breath-hold enabled the simultaneous assessment of arteries and veins before laparoscopic gastrectomy.

Aged↗
PubMed2005

Evaluation of breath-hold 201Tl SPECT in the differential diagnosis of solitary pulmonary nodules.

UNLABELLED: The aim of this study was to evaluate the usefulness of deep inspiration breath-hold SPECT (BrST, a method for 201Tl SPECT) in the diagnosis of solitary pulmonary nodules (SPN). METHODS: Ten patients with malignant lesions and five with benign lesions were enrolled in this study. Early SPECT acquisition was performed 15 min after injection of 201Tl, while delayed SPECT images were acquired 3 h after injection. The first 15-sec acquisition was done using the BrST technique, and the second with the conventional free breathing (FB) method. We performed this technique alternately, and therefore, the odd data were from BrST and the even data were from FB. We referred to the T/N ratio of the early images as the ER and to the T/N ratio of the delayed images as the DR. To semi-quantitatively evaluate the degree of retention in the lesion, the retention index (RI) was calculated. RESULTS: The RI of BrST indicated greater accuracy than that of FB in the differential diagnosis of SPN. For the benign and malignant lesions, the RI of BrST was -3.07 +/- 31.51 and 29.86 +/- 25.01, respectively (p < 0.05). The sensitivity, specificity, and accuracy of BrST (80%, 80%, and 80%, respectively) were significantly higher than those of FB (p < 0.05). CONCLUSION: The BrST method is more accurate than that of the conventional FB method in the differential diagnosis of SPN.

Aged↗
PubMed2005

[A case of iatrogenic pseudoaneurysm of the pulmonary artery induced by a Swan-Ganz catheter].

We report a case of iatrogenic pseudoaneurysm of the right pulmonary artery induced by a Swan-Ganz (SG) catheter. An SG catheter was inserted to the pulmonary artery before the esophageal surgery. Chest radiograph after the surgery showed a nodule in the right lower lung field. Based on the retrospective review of serial chest radiographies after SG catheter placement, we suspected iatrogenic pseudoaneurysm of the pulmonary artery caused by over-insertion of the catheter tip. Contrast-enhanced CT showed the nodular shadow with eccentric and marked enhancement continuing right A4b. We diagnosed a pseudoaneurysm of the pulmonary artery. The nodular shadow resolved spontaneously over a 2-month period.

Aged↗
PubMed2005

[A case of giant fibrovascular polyp of the esophagus: MR findings].

We report a case of giant fibrovascular polyp of the esophagus. The patient was a 69-year-old man who complained of hematemesis. Barium swallowing revealed a long, expansile lesion within the esophagus. Endoscopy demonstrated a pedunculated lesion covered with normal esophageal epithelium. On MRI, the sagittal image showed the characteristic sausage-like shape of the lesion. On T2-weighted images, the lesion demonstrated predominantly low signal intensity, which reflected a fibrous tumor. Opposed-phase imaging showed the area of decreased intensity within the mass, which reflected adipose tissue. MRI was useful for the differential diagnosis of fibrovascular polyp.

Aged↗
PubMed2005

Comparison of methods of attenuation and scatter correction in brain perfusion SPECT.

OBJECTIVE: The radioactivity count distribution in the brain must be determined accurately to accurately measure cerebral blood flow (CBF). Scatter and attenuation are factors that compromise the accuracy of determining radioactivity counts in the brain. METHODS: We compared regional CBF in patients by an autoradiographic method using N-isopropyl-p-[123I] iodoamphetamine when, first, attenuation correction alone was performed uniformly on SPECT images by using empiric mu-values (Chang method); second, scatter correction was performed and the mu-values of a homogeneous-attenuation body of water were used for attenuation correction (triple-energy window [TEW]+Chang method); and third, scatter correction was performed and the mu-values calculated by CT were used for attenuation correction (TEW+CT method). We also compared regional CBF measured by these methods with the values obtained by the xenon CT/CBF method, which uses CT and stable xenon. RESULTS: Scatter correction reduced overestimation of regional CBF in low-flow regions. The TEW+CT method yielded better regional and overall correlations with the xenon CT/CBF method than did either of the other methods. CONCLUSION: The TEW+CT method of correction gave the most accurate measurements of regional CBF.

Algorithms↗
PubMed2004

Preoperative assessment of vascular anatomy around the stomach by 3D imaging using MDCT before laparoscopy-assisted gastrectomy.

OBJECTIVE: Our aim was to evaluate the efficacy of 3D imaging using MDCT in the preoperative assessment of the vascular anatomy around the stomach before laparoscopy-assisted gastrectomy. SUBJECTS AND METHODS. Thirty-six consecutive patients scheduled for laparoscopy-assisted distal gastrectomy were evaluated on MDCT. CT was performed at the arterial phase after a bolus IV injection of contrast material. Three-dimensional CT angiography (3D CTA) of the arterial and venous systems was reconstructed separately using a volume-rendering algorithm, and the images were fused. Three-dimensional CTA for the left gastric, right gastric, and replaced left hepatic arteries and the left gastric coronary vein was evaluated prospectively by three reviewers, and then a surgical correlation was made. RESULTS: In all 36 cases, the left gastric artery was correctly identified on 3D CTA. In 35 of 36 cases, the right gastric artery was correctly identified, whereas in one case, the right gastric artery could not be visualized on 3D CTA because of its small size. In 35 of 36 cases (i.e., one case with agenesis of the left gastric coronary vein was excluded), the left gastric coronary vein was correctly identified. In six cases, the replaced left hepatic artery was correctly identified on 3D CTA. All 36 cases underwent successful laparoscopy-assisted distal gastrectomy on the basis of the 3D CTA. Both the sensitivity and positive predictive values of 3D CTA revealed 100% correct determination of the left gastric artery, replaced left hepatic artery, and left gastric coronary vein. The sensitivity and positive predictive values for the right gastric artery were 97% and 100%, respectively. CONCLUSION: Three-dimensional CTA using MDCT clearly revealed individual vascular anatomies around the stomach and could play an important role in safely facilitating the laparoscopy-assisted gastrectomy procedure.

Algorithms↗
PubMed2004

[A case of uterine cystic adenomatoid tumor mimicking malignant ovarian tumor on MR imaging].

We report a case of adenomatoid tumor of the uterus. MR images demonstrated a cystic mass with septae attached to the posterior wall of the uterus, making it difficult to distinguish from a malignant ovarian tumor. However, normal bilateral ovaries and beak sign continuing to the uterus were detected on MR images, enabling us to distinguish the cystic mass from a malignant ovarian tumor. Laparotomy demonstrated a subserosal mass of the uterine fundus. The macroscopic specimen showed a multilocular cystic mass, while the microscopic specimen showed cystic spaces lined with flattened and cuboidal cells admixed with smooth muscle, confirming the diagnosis of adenomatoid tumor of the uterus.

Adenomatoid Tumor↗
PubMed2004

[A case of gastric cancer with trial of x-, y- and z-axes positional reformation in multiphase fusion imaging of three-dimensional perigastric arteriography and venography].

Because multiphase fusion imaging demonstrates three-dimensionally and simultaneously the perigastric arteries and veins, it is particularly useful in the simulation of laparoscopic gastric cancer surgery. We constructed a multiphase fusion image of the perigastric arteries and veins, which were divided by a different degree of respiratory rest. We attempted to reform the positional relationship of the left gastric coronary vein to the splenic arteries along the x-, y-, and z-axes, however, the portal vein ran along the ventral side of the gastroduodenal artery, and the gastroepiploic artery was separate from the gastroepiploic vein, differing from the true anatomical relationship.

Coronary Angiography↗
PubMed2004

[Fusion imaging of three-dimensional angiographies of arteries and veins around the stomach by multiphase fusion technique under single breath-hold using 16-detector multislice CT].

Postcontrast CT scan using multislice CT was performed in 10 patients prior to laparoscopic gastric cancer surgery. Using 16-detector multislice CT, images were obtained at both arterial and venous phases under a single breath-hold. Three-dimensional CT angiography at arterial and venous phases was respectively reconstructed using the volume-rendering technique and then fused. Multiphase fusion imaging was able to demonstrate clearly, simultaneously, and three-dimensionally the gastric arteries and veins without a respiratory gap. In conclusion, multiphase fusion images were considered to be very useful for the intraoperative navigation of laparoscopic gastric cancer surgery.

Aged↗
PubMed2004

[A case of giant peritoneal loose body: usefulness of wide window width CT].

We encountered a case of giant peritoneal loose body, which was detected on barium enema by chance. Unenhanced CT showed a round mass with calcified center. On MR examination, the mass moved to the pelvic cavity from the position at CT examination. T1- and T2-weighted images showed a mass with low signal intensity. The contrast-enhanced T1-weighted images showed no enhancement. From these findings, peritoneal loose body, in addition to teratoma, granuloma, and foreign body, was suspected. However, the wide window width CT clearly showed a concentric calcification, a finding that is characteristic of peritoneal loose body.

Aged↗
PubMed2003

Gated blood pool SPECT improves reproducibility of right and left ventricular Fourier phase analysis in radionuclide angiography.

OBJECTIVES: The ventricular phase angle, a parametric method applied to Fourier phase analysis (FPA) in radionuclide ventriculography, allows the quantitative analysis of ventricular contractile synchrony. However, FPA reproducibility using gated blood pool SPECT (GBPS) has not been fully evaluated. The present study evaluates whether by using GBPS, the reproducibility of FPA could be improved over that in planar radionuclide angiography (PRNA). METHODS: Forty-three subjects underwent both GBPS and PRNA, of which 10 subjects were normal controls, 25 had dilated cardiomyopathy, and 8 had various heart diseases. Interventricular contractile synchrony was measured as the absolute difference in RV and LV mean ventricular phase angle as delta(phi) (RV - LV). Intraventricular contractile synchrony was measured as the standard deviation of the mean phase angle for the RV and LV blood pools (RVSD(phi), LVSD(phi)). Two nuclear physicians processed the same phase images of GBPS to evaluate the interobserver reproducibility of the phase angles using data from the 43 study participants. Phase images acquired from PRNA were processed in the same manner. RESULTS: Excellent reproducibility of delta(phi) (RV - LV) was obtained with both GBPS (Y = -3.10 + 0.89 x X; r = 0.901) and PRNA (Y = -4.51 + 0.81 x X; r = 0.834). In regard to RVSD(phi) reproducibility was not adequate with PRNA (Y = 18.56 + 0.35 x X; r = 0.424), while it was acceptable with GBPS (Y = 5.22 + 0.85 x X; r = 0.864). LVSD(phi) reproducibility was superior using both GBPS (Y = 4.15 + 0.97 x X; r = 0.965) and PRNA (Y = -0.55 + 0.98 x X; r = 0.910). CONCLUSION: Our results demonstrate FPA obtained using GBPS to be highly reproducible for evaluating delta(phi) (RV - LV), RVSD(phi) and LVSD(phi), in comparison with the PRNA method. We thus consider GBPS appropriate for evaluating ventricular contractile synchrony.

Adult↗