Akira Fujikawa

University Hospital Medical Information Network, Edo, Tōkyō, Japan

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Publications (31)71.08 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Between September 2009 and January 2010, 6 members of the Japanese Eastern Army, who had completed the same training program, were diagnosed with active tuberculosis (TB) on different occasions. The Ministry of Defense conducted a contact investigation of all members who had come into contact with the infected members. The purpose of this study was to verify the efficacy of the TB screening protocol used in this investigation. A total of 884 subjects underwent interferon-gamma release assay (IGRA) and chest X-ray. The 132 subjects who were IGRA positive or with X-ray findings suggestive of TB subsequently underwent chest computer tomography (CT). Chest CT was performed for 132 subjects. Based on CT findings, 24 (2.7%) subjects were classified into the active TB group, 107 (12.1%) into the latent tuberculosis infection (LTBI) group, and 753 (85.2%) into the non-TB group. The first 2 groups underwent anti-TB therapy, and all 3 groups were followed for 2 years after treatment. Although one subject in the active TB group experienced relapse during the follow-up period, no patient in the LTBI or non-TB groups developed TB. IGRA and chest X-ray, followed by chest CT for those IGRA positive or with suspicious X-ray findings, appears to be an effective means of TB contact screening and infection prevention.
    PLoS ONE 01/2014; 9(1):e85612. · 3.53 Impact Factor
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    ABSTRACT: The authors report two cases of pseudomesotheliomatous lung cancer (PLC) detected by (18)F-FDG PET/CT scan. (18)F-FDG PET/CT clearly revealed the extent of the disease in both cases, a case of adenocarcinoma of the lung and a case of squamous cell carcinoma of the lung. Intense (18)F-FDG uptake by the diffusely thickened pleurae and primary lesion was observed in both cases, and increased (18)F-FDG uptake by a pelvic bone metastasis was observed in the case of squamous cell carcinoma. Although PLC is indistinguishable from malignant pleural mesothelioma on (18)F-FDG PET/CT scans, (18)F-FDG PET/CT was helpful in identifying the primary focus of the PLCs and in staging the disease. Diagnostic image interpreters should be familiar with the (18)F-FDG PET/CT findings in PLC.
    Japanese journal of radiology 04/2013; · 0.73 Impact Factor
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    ABSTRACT: When the Great East Japan Earthquake occurred on March 11, 2011, the Ground Self-Defense Force (GSDF) was dispatched nationally to Northeast area in Japan. The highly trained GSDF members were simultaneously assigned to various missions for the Fukushima Nuclear Power Plants disaster. The missions of GSDF terminated on August 31, 2011. Special medical examinations were conducted for the members as they returned to each military unit. GSDF members who were assigned to the nuclear power plant were at risk of radiation exposure; therefore, pocket dosimeters were used to assess external radiation exposure. A few months after the mission was terminated, measurements of internal radiation exposure were performed. This is the first report of the internal exposure of GSDF members who worked in the restricted radiation contamination area. Here, we report the amounts of internal and external exposure of and the equipment used by the GSDF members.
    American journal of disaster medicine 01/2013; 8(2):87-90.
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    ABSTRACT: A 59-year-old asymptomatic man was incidentally found to have a periaortic mass and an elevated serum amylase level during his medical check-up. Additional findings, such as infiltration of immunoglobulin G4 (IgG4)-producing plasma cells in the mass lesion, elevation of serum IgG4 (1000 mg/dl), and pancreatic duct narrowing as evidenced on a magnetic resonance cholangiopancreatography scan, confirmed the diagnosis as retroperitoneal fibrosis complicated with autoimmune pancreatitis. The patient responded favorably to steroid treatment before the appearance of symptoms.
    Modern Rheumatology 02/2010; 20(3):306-10. · 1.72 Impact Factor
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    ABSTRACT: Our aim was to examine the feasibility of a computed tomographic angiography (CTA) protocol using a reduced dose of high-concentration contrast material on a 16 multidetector-row system to visualize both cervical and cerebral arteries in one session. In 31 consecutive patients, we performed CTA covering the cervical and cerebral arteries. The patients were assigned to one of three groups: group A, 100 mL of 300 mgI/mL; group B, 80 mL of 370 mgI/mL; and group C, 60 mL of 370 mgI/mL followed by a 30-mL saline flush. Arterial enhancements were quantified by measuring attenuation values of the common carotid artery, internal jugular vein, proximal middle cerebral artery (MCA), basilar artery, and straight sinus on source images. Visualizations of the carotid bifurcation and arteries continuing to the circle of Willis were rated on a three-point grading scale on CTA images for qualitative assessment. There were no statistically significant differences in attenuation of all the target vessels among the three groups, with the one exception being a lower attenuation of the MCA in group C than in groups A and B (P < 0.01). Neither were there any significant differences noted among the three groups on the visual assessment. Use of a reduced dose of high iodine concentration contrast material may provide an equal degree of image quality for CTA covering the craniocervical region on a 16 multidetector-row system.
    Neuroradiology 10/2009; 52(4):291-5. · 2.70 Impact Factor
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    ABSTRACT: We report an interesting case of a patient with renal cell carcinoma who developed a refractory cough, which immediately resolved after tumor embolization. Patient's symptoms including low-grade fever, weight loss, and abnormal laboratory results also improved shortly after subsequent nephrectomy. The clinical manifestations of the patient are most likely representing paraneoplastic syndrome secondary to renal cell carcinoma.
    Scandinavian Journal of Urology. 07/2009; 36(5).
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    ABSTRACT: We employed a diffusion-tensor (DT) imaging technique involving a single-shot echo-planar sequence in combination with parallel imaging for tractography of the lower spinal cord and assessed the feasibility of this technique. Images were obtained at 1.5 T using a five-channel receiver coil. We used a single-shot echo-planar sequence with parallel imaging to acquire diffusion-weighted (DW) images in the axial plane with phase encoding in the right-left direction. A motion-probing gradient was applied in six directions with a b-value of 1,000 s/mm(2). The scan time was 5 min 15 s. On a reconstructed DW image in the sagittal plane, the spinal cord was included in a single region-of-interest to generate a tractogram of the entire cord in seven volunteers and nine patients with spinal canal stenosis or vertebral metastasis. In each subject, although the conus medullaris and cauda equina were continuously visualized, the cord was demonstrated as a bundle of tracts color-coded in the z-axis. Nerve roots were depicted showing color-coding in the x- and y-axes. In the patient group, displacement of the cord was depicted showing changes in the color of the cord. Displacement of the proximal nerve roots was also depicted in the two patients with vertebral metastasis. DT imaging using parallel imaging shows potential as a method for routine tractography of the lower spinal cord.
    Neuroradiology 04/2008; 50(3):221-5. · 2.70 Impact Factor
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    ABSTRACT: The purpose of this study was to prospectively explore the MRI features of normal healing of the expected residual tendon gap in the Achilles tendon after percutaneous surgical repair. MR images of the Achilles tendon were obtained approximately 4, 8, and 12 weeks after surgery. Assessment of MR images was focused on the presence of residual tendon gap and gap length, Achilles tendon contour, and contrast enhancement in the ruptured area. Cases of open surgical repair were used for comparison. We attempted to statistically compare the timing of tendon gap disappearance within the percutaneous surgical repair group and between the percutaneous and open surgical repair groups. A total of 30 tendons repaired with percutaneous surgical technique and 10 repaired with open surgical technique were evaluated. At the first, second, and third MRI sessions of the percutaneous surgical repair group, a residual gap was found in 100%, 80%, and none of the tendons on T1-weighted images and in 87%, 63%, and none of the tendons on T2-weighted images. Achilles tendon contour was visualized in 30%, 90%, and 100% of the tendons on T1-weighted images and 90%, 100%, and 100% of the tendons on T2-weighted images. Intratendinous enhancement was present in 100%, 73%, and 7% of the tendons in the percutaneous surgical repair group. Ring-shaped peritendinous enhancement was recognized at the third session in all subjects. A significantly longer time was required for tendon gap disappearance after percutaneous than after open surgical repair. The time course of the MR findings in the ruptured Achilles tendon after percutaneous surgical repair appears to reflect regular healing.
    American Journal of Roentgenology 12/2007; 189(5):1169-74. · 2.90 Impact Factor
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    ABSTRACT: Diffusion-weighted (DW) magnetic resonance (MR) imaging of the nerve roots and peripheral nerves has been reported. We applied a sequence similar to brain diffusion tensor (DT) tractography to such a technique and assessed its feasibility. On a 1.5-T MR system, we acquired DW images in the axial plane using a single-shot echo-planar short tau inversion-recovery (STIR)-based sequence. Motion-probing gradients (MPGs) were applied in 6 directions with a b-value of 500 s/mm(2). For postprocessing, we performed maximum-intensity projection to reconstruct the images. We obtained cervical spine images from 3 volunteers and 8 patients and thoracolumbar spine images from 3 volunteers and 6 patients. On the source images of the cervical spine obtained from the volunteers, we compared the signal-to-noise ratios (SNRs) of the neural structures between images obtained applying MPG in 6 directions and in 3 directions. We visually assessed the nerve roots and proximal portions of the contiguous peripheral nerves in the images from volunteers and patients. The SNRs were significantly superior in the images obtained with the application of MPGs in 6 directions to those obtained with the application of MPGs in 3 directions (P<0.01). Visual assessment demonstrated the nerve roots as well as the nerve ganglia and the contiguous peripheral nerves up to 3 cm or more from the respective neural foramina in each subject. Image distortion was minimal. Our technique provides neurographic images of the nerve roots and proximal portions of the contiguous peripheral nerves, and images obtained using our sequence applying MPGs in 6 directions are superior to those obtained in 3 directions.
    Magnetic Resonance in Medical Sciences 02/2007; 6(1):1-5. · 0.75 Impact Factor
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    ABSTRACT: We analyzed the findings of diffusion-weighted (DW) imaging using the single-shot fast spin-echo sequence in acute cervical cord injury and evaluated the usefulness of this method for predicting the prognosis. Our patient group comprised 14 patients examined 2 h to 3 days after injury. First, we visually evaluated the DW imaging findings in all patients. Apparent diffusion coefficient (ADC) maps were also assessed in 13 patients. Second, we assessed follow-up magnetic resonance (MR) examinations obtained in six patients whose DW images showed hyperintensity. Third, we reviewed the functional outcome at discharge. The lesions showed hyperintensity in ten patients, and no abnormal signal was noted in the remaining four patients. The ADC maps showed restricted diffusion in all patients with hyperintensity on DW imaging except in one patient for whom the ADC map was unavailable. Repeated MR examinations obtained in six of the ten patients showed either myelomalacia or exacerbation. Seven of the ten patients (70%) required assistance and the other three were independent. Among the four patients without hyperintensity on DW imaging, three (75%) were independent and only one required assistance. DW imaging in acute cervical cord injury often reveals restricted diffusion. This finding may predict an unfavorable functional prognosis.
    Neuroradiology 12/2006; 48(11):803-8. · 2.70 Impact Factor
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    ABSTRACT: OBJECTIVE: The ability of different MRI sequences to depict characteristic findings suggestive of ventriculitis was compared. CONCLUSION: The study comprised 20 brain MRI studies in 13 patients who had a final diagnosis of ventriculitis. Both diffusion-weighted imaging and FLAIR imaging were equally and highly sensitive for detecting intraventricular debris and pus--the most common MRI finding suggestive of ventriculitis. FLAIR imaging was superior to contrast-enhanced T1-weighted imaging for depicting ventricular wall abnormalities--a less common finding that also is suggestive of ventriculitis.
    American Journal of Roentgenology 11/2006; 187(4):1048-53. · 2.90 Impact Factor
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    ABSTRACT: To report a technique developed for visualizing cervical nerve roots and distal nerve fibers using diffusion-weighted magnetic resonance imaging employing parallel imaging. We performed maximum intensity projection for a stack of isotropic axial diffusion-weighted images obtained with parallel imaging applying a motion-probing gradient in six directions with a b-value of 500 s/mm2 in a preliminary series of 13 subjects. This method worked well for visualizing the spinal cord and most of the nerve roots, the dorsal root ganglia, and proximal peripheral nerves. Although the technique remains limited in depicting the brachial plexus and distal nerves, the ability to visualize the proximal peripheral nervous system at the cervical level is promising.
    Acta Radiologica 08/2006; 47(6):599-602. · 1.33 Impact Factor
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    ABSTRACT: Our goals were to assess image quality of time-resolved contrast-enhanced MR angiography (CE MRA), by using 3D data acquisition along with a parallel imaging technique that can improve temporal resolution and to compare this technique with 3D-time-of-flight (TOF) MRA in the postoperative assessment of extracranial (EC)-intracranial (IC) bypass surgery. On a 1.5T imaging system, we performed CE MRA by using a 3D fast field-echo sequence in combination with a parallel imaging technique, to obtain images in the coronal plane centered at the postoperative site. Our patient group comprised 17 patients, including 13 after superficial temporal artery-middle cerebral artery (MCA) anastomosis, 3 after external carotid artery-MCA anastomosis, and one after extracranial vertebral artery-posterior cerebral artery anastomosis. Visualization of the anastomosis and the distal flow on the CE-MRA images was assessed comparatively with that on 3D-TOF MR angiograms obtained at the same time. In 6 patients, we also compared the efficiency of visualization on CE-MRA images with that on conventional angiograms. A temporal resolution of 0.8 s/frame could be achieved with the technique employed. The bypass was better demonstrated postoperatively on CE-MRA images than on 3D-TOF MR angiograms in 13 patients (76%), whereas the 2 methods were equivalent in 4 patients (24%). Good correspondence of results was observed in the 6 patients for whom CE MRA and conventional digital subtraction angiography (DSA) images were compared. CE MRA by using the parallel imaging technique can increase image acquisition speed with sufficient image quality. This technique is at least equivalent to 3D-TOF MRA to evaluate the postoperative status of EC-IC bypass.
    American Journal of Neuroradiology 11/2005; 26(9):2243-7. · 3.17 Impact Factor
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    K Tsuchiya, A Fujikawa, M Nakajima, K Honya
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    ABSTRACT: We tested our hypothesis that fractional anisotropy (FA) maps of diffusion tensor imaging could be used to differentiate between a solitary brain metastasis and a high-grade glioma. In seven patients with a solitary metastasis and seven patients with a high-grade glioma, FA values of enhancing and non-enhancing parts of the tumour were compared. Additionally, we visually assessed FA maps. No significant difference in the FA values of either the enhancing or non-enhancing part was found between the two groups. In the visual assessment, displacement of subcortical white-matter fibres was found in five of the seven metastasis patients, but in only one glioma patient. Additionally, discrimination between tumour and oedema was possible in three of the seven metastasis patients, but not in any glioma patient. Although FA values are not helpful in differentiating between the two groups, visual differences in FA values can allow the differentiation. Displacement of white-matter fibres is another finding suggestive of metastasis.
    British Journal of Radiology 07/2005; 78(930):533-7. · 1.22 Impact Factor
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    Kazuhiro Tsuchiya, Akira Fujikawa, Yuriko Suzuki
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    ABSTRACT: We applied a single-shot echo-planar axial diffusion tensor sequence with parallel imaging for tractography of the cervical cord. Placing a large region of interest on a reconstructed sagittal image, the cervical cord was depicted as a tract bundle showing color-encoded cephalocaudally. By setting one region of interest in the cerebral peduncle and another in the entire cord on source images, tracts on each side were visualized. This method is promising for tractography of the cervical cord.
    American Journal of Neuroradiology 03/2005; 26(2):398-400. · 3.17 Impact Factor
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    ABSTRACT: We report diffusion-weighted (DW) MR findings for acute spinal cord ischemia in a 56-year-old patient. MR imaging obtained approximately 3 h after symptom onset demonstrated an area of hyperintensity on DW images, but no conspicuous signal abnormality on T2-weighted images in the conus medullaris. DW imaging of the spinal cord can contribute to the early detection of spinal cord vascular compromise.
    European Radiology 12/2004; 14(11):2076-8. · 4.34 Impact Factor
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    American Journal of Roentgenology 12/2004; 183(5):1487-8. · 2.90 Impact Factor
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    ABSTRACT: We assessed the feasibility of MR digital subtraction angiography (DSA) using parallel imaging and keyhole data sampling in the diagnosis of cerebrovascular diseases (CVDs) in 11 patients. Their diseases included arterial trunk stenosis/occlusion ( n=4), aneurysm ( n=3), arteriovenous malformation ( n=2), venous angioma ( n=1), and sinus thrombosis ( n=1). The technique depicted not only anatomical features, comparably to MR angiography ( n=10/11), but also hemodynamics such as collateral flow at a temporal resolution of 1.68 s/frame. When compared with conventional angiograms ( n=7), details were missed in four patients (incomplete demonstration of aneurysmal neck in two and poor separation of AVM components in two). Although inferior to conventional angiography, this technique can provide both anatomical and hemodynamic information of CVDs.
    European Radiology 09/2004; 14(8):1494-7. · 4.34 Impact Factor
  • Clinical Nuclear Medicine 07/2004; 29(6):372-4. · 2.96 Impact Factor
  • Clinical Nuclear Medicine 02/2004; 29(1):53-4. · 2.96 Impact Factor

Publication Stats

250 Citations
71.08 Total Impact Points

Institutions

  • 2004–2009
    • University Hospital Medical Information Network
      Edo, Tōkyō, Japan
  • 2001–2006
    • Kyorin University
      • Department of Radiology
      Edo, Tōkyō, Japan