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Norio Nakao

Publications and source records attributed to Norio Nakao.

At least 19 recordsLinked to original sources
PubMed2006

Clinicoradiological factors influencing the reversibility of posterior reversible encephalopathy syndrome: a multicenter study.

PURPOSE: The aim of this retrospective study was to clarify the relation between the reversibility of posterior reversible encephalopathy syndrome (PRES) with three factors: the anatomical region of the brain involved, the background clinical cause, and the diffusion weighted image (DWI) intensity of PRES lesions. MATERIAL AND METHODS: This multicenter study, conducted by the PRES Study Group of the Neuroradiology Workshop, involved 52 cases from 28 institutions. Initial and follow-up magnetic resonance imaging were compared regarding the reversibility of PRES lesions according to anatomical location and clinical background. Initial DWI and apparent diffusion coefficient (ADC) maps were reviewed in 20 cases. RESULTS: Reversibility was significantly lower (P < 0.01) in the brain stem (44%) and deep white matter (47%) compared to the other cortical and subcortical areas (76%-91%). The reversibility was greater in the eclampsia subgroup followed by the hypertension and chemotherapy subgroups. DWI, even with ADC maps, had limitations in predicting the outcome of PRES lesions. CONCLUSION: The typical cortical and subcortical PRES lesions showed reversibility, whereas the brain stem and deep white matter lesions showed less reversibility. PRES due to eclampsia showed maximum reversibility compared to hypertension- and drug-related PRES. DWI, even with ADC maps, had limitations in predicting the course of PRES.

Adolescent↗
PubMed2006

[Evaluation of low contrast resolution in cone beam CT using FPD].

We examined the low contrast resolution of cone beam CT (CBCT) equipped with an indirect-type flat panel detector and compared it with a commercial CT unit (Robusto) . In CBCT, the X-ray tube voltage of 110 kV was used, and in the Robusto, the usual 120 kV was used for examinations. The computed tomography dose index (CTDI) of the two systems was measured, and images scanned at about the same exposure to radiation were compared. The modulation transfer factors of the two systems were measured, and the convolution kernel that was the nearest to the characteristic of CBCT was chosen among kernels of the Robusto. A water phantom with a diameter of 200 mm was scanned, Wiener spectra were calculated, and signal-to-noise ratios were compared. The low contrast resolution phantom was scanned, and detectability and contrast-to-noise ratio (CNR) were measured. In addition, we placed diluted contrast medium into a phantom, scanned the phantom, and measured the detectability and CNR. When the X-ray irradiation condition of CBCT was 75 mAs at 110 kV, the equal dose of radioactivity in the Robusto was 50 mAs at 120 kV. In the low contrast resolution phantom, detectability was 8.7%mm in CBCT, and 9.4%mm in the Robusto. In the low contrast resolution evaluation phantom, CNR was 1.39 in CBCT, and 2.69 in the Robusto. With diluted contrast medium, CNR was 1.28 in CBCT, and 0.60 in the Robusto. CBCT was inferior to the Robusto in a low contrast resolution phantom, but CBCT was superior to the Robusto using diluted contrast medium. We found that CBCT was useful in examinations using contrast media.

Contrast Media↗
PubMed2006

Evaluation of vascular supply with cone-beam computed tomography during intraarterial chemotherapy for a skull base tumor.

A cone-beam lowers the X-ray exposure level and the contrast material dose used compared to those for the conventional angiography-computed tomography (angio-CT) technique. Herein we present a patient with a metastatic skull base bone tumor in which the subtraction image of cone-beam CT with a flat panel detector was useful for evaluating the vascular supply during superselective intraarterial chemotherapy. Although the image quality of cone-beam CT is poorer than that of conventional angio-CT, the cone-beam CT system is sufficient for clinical use.

Aged↗
PubMed2006

Disseminated necrotizing leukoencephalopathy following chemoradiation therapy for acute lymphoblastic leukemia.

Disseminated necrotizing leukoencephalopathy (DNL) is a potentially fatal complication of treatment involving intrathecal administration of chemotherapeutic agents such as methotrexate (MTX) alone or in combination with cranial radiotherapy (RT). We describe a case of acute lymphoblastic leukemia (ALL) treated with high-dose intravenous and intrathecal methotrexate combined with craniospinal RT resulting in DNL. Typical MR imaging features of progressive deep white matter lesions showing a characteristic pattern of enhancement after contrast was seen in this case. Deep white matter lesions with ring-like enhancement and calcifications were seen on CT; it showed a mass effect at one stage, which is not typical for DNL. Long-term clinical and imaging follow-up were helpful for the diagnosis in this case.

Antimetabolites, Antineoplastic↗
PubMed2006

Sertoli-stromal cell tumor of the right ovary: radiological-pathological correlation.

A case of Sertoli-stromal cell tumor of the right ovary is reported. The patient was a 50-year-old perimenopausal woman with abdominal distention due to a large pelvic tumor. She had no signs of androgen excess. A large solid sponge-like tumor with multicystic areas throughout, in which there were some small hemorrhagic spots, was shown on magnetic resonance (MR) imaging. No endometrial thickening of the uterus was seen. Pathology examination revealed a Sertoli-stromal cell tumor with intermediate-to-poor differentiation. The edematous, watery, sponge-like appearance on the MR images correlated with the pathological findings.

Contrast Media↗
PubMed2006

[Intra-arterial chemotherapy for invasive bladder cancer (T2-3N0M0)].

We assessed the effectiveness of intra-arterial MVAC chemotherapy or a combination of intra-arterial chemotherapy and external beam radiotherapy based on diagnostic images and histological (transurethral) examination in 15 cases with T2-3NOM0 between January 2003 and September 2005. When the clinical response was assessed one month after the treatments, a complete response (CR) was achieved in 20% (1/5) and 50% (5/10) by intra-arterial MVAC chemotherapy and a combination of intra-arterial chemotherapy and external beam radiotherapy, respectively. Total radical cystectomy was required on one patient during the follow-up period of 4-26 months. Although our result showed that the combination of external beam radiation therapy and intraarterial cisplatin effectively contributed to the preservation of the bladder with localized invasive bladder cancer, radical cystectomy is required when CR is not achieved after this treatment.

Aged↗
PubMed2005

A novel 3D hepatectomy simulation based on liver circulation: application to liver resection and transplantation.

Hepatectomy is a complicated operative procedure because of its anatomical complexity, vascular variability, and impaired hepatic function due to associated hepatitis or cirrhosis. Thus preoperative detailed topography and precise liver resection volume measurements should be obtained for a curative hepatectomy. The aim of this study was to assess the feasibility and accuracy of a novel three-dimensional (3D) virtual hepatectomy simulation software in patients who underwent liver resection or living donor liver transplantation. We developed the hepatectomy simulation software, which was programmed to analyze detailed 3D vascular structure and to predict liver resection volume and margins. In 72 patients receiving hepatectomy, the predicted liver resection volumes and margins revealed a significant correlation with the actual value with a mean difference of 9.3 mL (P < .0001) and 1.6 mm (P < .01), respectively. The drainage area by hepatic veins was quantified to achieve reconstruction of the corresponding venous branch. In conclusion, this hepatectomy simulation software reliably predicted an accurate liver resection volume, the cancer-free margin, and the drainage volume of hepatic vein branches. This software may promote curative hepatectomy and may be used for other interventional therapies in the treatment of liver disease.

Adult↗
PubMed2005

Kidney displacement simulator for retroperitoneal laparoscopic nephrectomy.

PURPOSE: We evaluated the efficacy of a renal displacement simulator originally developed at our department for retroperitoneal laparoscopic nephrectomy. MATERIALS AND METHODS: A total of 12 patients with a malignant localized renal (7) or ureteral (5) neoplasm underwent multidetector row computerized tomography. Imaging data were sent to a dedicated work station to create volume rendering and virtual laparoscopic images of the kidney, which was displaced ventral using a retroperitoneal balloon. These findings were compared with video images obtained during laparoscopy surgery. RESULTS: The kidney displacement simulator depicted all renal arteries (100% sensitivity) and 13 of 14 renal veins (93% sensitivity). Hilar anatomy, including the tumor, as well as major vessels and their relationships were visualized by the simulator in the laparoscopic views. The major vessel portions completely corresponded to those seen during surgery, and the left adrenal and gonadal veins were also synchronized quite well. CONCLUSIONS: Our kidney displacement simulator was able to visualize the major vessel portions and branched small vessels, such as the adrenal and gonadal veins, prior to surgery. It is considered useful for providing guidance to surgeons and decreasing operative risks and possible complications.

Aged↗
PubMed2005

Potential of superparamagnetic iron oxide in the differential diagnosis of metastasis and inflammation in bone marrow: experimental study.

RATIONALE AND OBJECTIVES: The utility of ferucarbotran for the diagnosis of bone metastases was investigated using tumor-implanted rabbits. The potential of ferucarbotran in the differential diagnosis of metastasis and inflammation was also investigated. METHODS: Twelve rabbits were divided into 2 groups (tumor and inflammation groups). Six rabbits of tumor group were inoculated with VX2 tumor cell suspension, and the 6 rabbits of the inflammation group were inoculated with 10% croton oil in the bone marrow of the right femur. All rabbits were imaged using a clinical MRI system. Signal intensity in the bone marrow of the right femur was measured in each rabbit before and after the intravenous injection of 8 micromol Fe/kg of ferucarbotran. As a control, the signal intensity in the bone marrow of the left femur (the normal, intact femur) was measured in each rabbit. The change in signal intensity of each group was compared statistically. After MRI imaging, the femora were removed, and sections were prepared for microscopic examination. RESULTS: Signal intensity in the right femur of the tumor group did not change after injection, although that of the inflammation group and the control group decreased. In the histologic findings, tumors were widely spread in the right femur of the tumor group. The infiltration of pseudoeosinocytes was induced in the right femur of the inflammation group. CONCLUSIONS: This animal study showed that ferucarbotran was useful to detect bone marrow tumors. In addition, ferucarbotran may have potential in the differential diagnosis of bone metastasis and some kinds of inflammation.

Animals↗
PubMed2005

[Clinical study of porous gelatin sphere (YM 670) in transcatheter arterial embolization].

A clinical study on the use of porous gelatin particles(sterile gelatin embolization material, YM 670, Gelpart) in transcatheter arterial embolization (TAE) was performed in patients with hepatocellular carcinoma, and the efficacy (embolization,anti-tumor effect, recanalization and operationality) and safety (tolerability) were studied. An additive agent comprising porous gelatin particles and low osmolarity contrast media was administered peripherally through a catheter into the hepatic artery proper of 63 patients with hepatocellular carcinoma. Good hepatic arterial embolization was confirmed in all cases (embolization: 100%), and a tumor necrosis effect was obtained in most cases (35/62 patients, 56.5%). Moreover, operationality was assessed as "highly easy to use" or "easy to use" in all cases. Frequencies of adverse events in which a relationship to TAE was not excluded and abnormalities of clinical laboratory data were high at 71.4% and 9 8.4%, respectively. The most common adverse reactions were pyrexia, abdominal pain, queasiness and blood pressure increase;abnormalities in clinical laboratory data included hepatic function with increased AST (GOT), increased ALT (GPT), decreased cholinesterase, increased LDH and increased total bilirubin. These adverse reactions and abnormalities in clinical laboratory data, however, were transient and attributed to the TAE procedure itself, and no adverse reactions related to YM 670 as an embolic material were observed. In addition, with regard to tolerability (safety), the treatment was assessed as suitable for use in all the present cases.

Adult↗
PubMed2004

[Usefulness of Cho/Cr ratio in proton MR spectroscopy for differentiating residual/recurrent glioma from non-neoplastic lesions].

PURPOSE: We evaluated the clinical usefulness of the Cho/Cr ratio of proton MR spectroscopy(1H-MRS) to differentiate residual/recurrent glioma from non-neoplastic lesions. PATIENTS AND METHODS: 20 cases of glioma were involved in this study(astrocytoma grade I-II: 7, oligodendroglioma: 1, astrocytoma grade III: 2, glioblastoma: 10). Seven of the patients underwent surgical resection only, 4 underwent surgical resection and radiotherapy(40-60 Gy), and 9 underwent surgical resection and radiotherapy with concurrent chemotherapy(14-60 Gy). 1H-MRS was performed on a 1.5 Tesla clinical MR unit using a 3D-chemical shift imaging sequence(1500 msec/270 msec/1 (TR/TE/excitations), and the Cho/Cr ratio was calculated in the voxel where neoplastic lesion was most suspected on MRI. The presence of lactate + lipid peak was also evaluated. All spectra were obtained after the contrast enhanced study. RESULTS: Cho/Cr ratios were significantly higher in cases of residual/recurrent tumors(mean +/- SD = 1.70 +/- 0.96) than in non-neoplastic lesions(mean +/- SD = 1.04 +/- 1.16) (Mann-Whitney U-test p = 0.047). If a Cho/Cr ratio of more than 1.5 was used as a marker of tumor presence, its sensitivity was 64%, specificity 83%, and accuracy 70%. One false-positive case that of radiation necrosis whose spectrum showed a high Cho/Cr ratio with markedly elevated lactate + lipid peak. CONCLUSION: The Cho/Cr ratio of 1H-MRS provides additional information to MRI in differentiating residual/recurrent gliomas from non-neoplastic lesions.

Adolescent↗
PubMed2004

[Visualization of brain perfusion by contrast-enhanced ultrasonography: preliminary study in rabbits].

PURPOSE: We evaluated the usefulness of an agent for contrast-enhanced ultrasonography (galactose parmitine acid: Levovist) in visualizing brain perfusion in rabbits. MATERIALS AND METHODS: Six rabbits were involved in this study. A hole in the skull bone was made under anesthesia and used as an acoustic window. An ischemic model (3 of 6 rabbits) was made by surgically occluding the M1 portion of the middle cerebral artery. Power Doppler images (PDI) and B-mode Harmonic images (HI) before and after intravenous injections of the contrast medium (150 mg/body) were obtained using the HDI5000 (ATL) equipped with a linear-type 5-12 Mhz probe. RESULTS: Smaller arteries were clearly visualized by contrast-enhanced PDI. However, enhancement of brain parenchyma was not clear on PDI. Enhancement of brain parenchyma was observed clearly on contrast-enhanced HI. Enhancement was strong during the first pass and then diminished quickly. In ischemic models, hypoperfusion in the right cerebral hemisphere (the occluded side) were clearly observed on contrast-enhanced HI. CONCLUSION: Brain perfusion in rabbits can be observed on contrast-enhanced Harmonic ultrasonographic imaging. It is suggested to be useful for human clinical cases, including hypoxic ischemic brain injury in infants.

Animals↗
PubMed2003

[Imaging findings of elongated styloid process syndrome (Eagle's syndrome): report of two cases].

Elongated styloid process syndrome, which is synonymous with Eagle's syndrome, is a rare disease. Although an elongated styloid process is not always symptomatic, if it compresses the cranial nerves and/or carotid artery, a patient can present with sore throat, dysphasia, or dysphoria of the throat. We present two cases of elongated styloid process syndrome, focusing on the imaging findings. The elongated styloid processes were visualized by panoramic photograms. However, CT images, especially 3DCT images, were useful in visualizing the elongated styloid process itself as well as the relationship between the styloid process and surrounding soft tissue.

Adult↗
PubMed2003

[Choroid plexus carcinoma of the foramen Luschka: a case report].

Choroid plexus carcinoma(CPC) is a rare intracranial neoplasm that usually arises in the supra-tentorial region of infants. We report an adult case of CPC that arose in the foramen Luschka. A 61-year-old woman presented with a 10-year history of dysarthria. CT showed an iso- to slightly high density mass in the left foramen Luschka. The tumor appeared as a low- to iso-intensity area in T1-weighted MR images, and as an iso- to high-intensity area in T2-weighted images. The tumor showed homogeneous enhancement with the administration of contrast medium. Imaging findings were non-specific and the differential diagnosis was difficult.

Choroid Plexus Neoplasms↗
PubMed2003

[New three-dimensional compensating filter for TBI using compu-former associated with RT LAN].

To shorten the TBI process, we developed a new device for making the three-dimensional (3D) compensating filter that improves dose distribution. The dose distributions in the phantom and manufacturing time were compared between the new device and the previous one. Clinical evaluations included dose distribution in patients and the clinical rate of interstitial pneumonitis (IP). Our 3D compensating filter is made of polystyrene resin and gypsum. The filter was made after performing two procedures as follows. Patient data were measured by CT, and the 3D dose-distribution data and 3D compensating-filter data were obtained from the CT data by the 3D radiation planning system. We were able to produce the new 3D compensating filter within about 4 hours, including all procedures. The average dose distribution to each site when the 3D compensating filter was used was 92.7% to the head, 102.1% to the thorax, 106.4% to the pelvis, 90.2% to the knee, and 93.8% to the ankle joint, when the scheduled dose was taken as 100%. Dose distribution was improved. IP occurred in 6 of 32 patients (18.8%). There was no significant difference between the TBI and non-TBI groups in the frequency of IP (p = 0.27).

Adolescent↗
PubMed2002

Central neurocytoma with craniospinal dissemination.

We report a case of central neurocytoma that manifested tumor recurrence with craniospinal dissemination. Imaging studies before surgery showed a markedly enhanced tumor with small cysts and calcification, which invaded the adjacent brain parenchyma, located in the posterior horn of the right lateral ventricle. Proton MR spectroscopy showed markedly elevated choline and lactate peaks with a strongly diminished N-acetylaspartate peak. Two years after neurosurgical intervention, the tumor showed multiple craniospinal dissemination in the middle cranial fossa and the intradural extramedullary space of the spine.

Adult↗