Naoko Saito

Saitama Medical University, Саитама, Saitama, Japan

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Publications (69)82.42 Total impact

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    ABSTRACT: We report two cases in which the vertebral artery (VA) entered the spinal canal via the intervertebral foramen at the C2-C3 disc level, an extremely rare variation regarded as a C3 segmental type of VA, that we diagnosed by magnetic resonance angiography. The C2 segmental type of VA, in which the VA enters the spinal canal via the C1-C2 intervertebral space, is relatively common. It is important to identify these variations before surgery of the craniovertebral junction or interventional procedures to prevent complications.
    No preview · Article · Jan 2016 · Anatomia Clinica
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    ABSTRACT: Introduction: Fenestration, early bifurcation, and duplication of the posterior cerebral artery (PCA) and the so-called hyperplastic anterior choroidal artery (AChA), considered a variation of the PCA, are rare. We evaluated the prevalence and characteristic features of these PCA variations on magnetic resonance (MR) angiography. Methods: We reviewed intracranial MR angiographic images of 2402 patients examined using a 3-tesla scanner. Images from the skull base to the intracranial region were obtained using the standard time-of-flight technique. We excluded images of 52 patients with insufficient image quality or occlusion of the PCA(s) and retrospectively evaluated the images of 2350 patients using a picture archiving and communication system. Results: We observed PCA fenestration in eight (0.34 %) patients, most at the P1 segment and P1-P2 junction and all small in size, early bifurcation at the P1-P2 junction or proximal P2A segment in eight (0.34 %) patients, complete duplication in one patient, and hyperplastic AChA in 13 (0.55 %) patients. Eleven of the 13 hyperplastic AChAs supplied only the territory of the temporal branch of the PCA, and the remaining two supplied the entire territory of the PCA. Conclusion: We observed PCA variations in 30 (1.28 %) patients. We believe the name "hyperplastic AChA" inaccurately describes variations of the PCA in which the AChA supplies part of or all of the territory of the PCA and propose "accessory PCA" to describe an AChA that supplies part of the territory of the PCA or "replaced PCA" to describe that vessel that supplies the territory all branches of the PCA.
    No preview · Article · Nov 2015 · Neuroradiology
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    ABSTRACT: We present an extremely unusual case of an extratemporal facial nerve malignant peripheral nerve sheath tumor (MPNST) arising from preexistent intratemporal neurofibroma, illustrating a difficulty in discriminating between perineural spread of the MPNST and the preexistent intratemporal neurofibroma on preoperative radiographic images. The most interesting point was that preoperative CT scan and MR images led to misinterpretation that MPNST extended proximally along the facial nerve canal. It is important to recognize that the intratemporal perineural spread of neurofibromas and MPNST share common imaging characteristics. This is the first report (to our knowledge) of these 2 lesions coexisting in the facial nerve, leading to misinterpretation on preoperative images.
    Full-text · Article · Sep 2015
  • Akira Uchino · Naoko Saito · Shoichiro Ishihara
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    ABSTRACT: The posterior inferior cerebellar artery (PICA) frequently arises from the fenestrated segment of the intracranial vertebral artery (VA), and this common variation can be misinterpreted as or confused with a PICA of double origin. Rarely, a PICA of true double origin occurs when two branches of the PICA arise separately from the intracranial VA and fuse to form an arterial ring. We discovered this rare variation incidentally while interpreting images of magnetic resonance (MR) angiography. This is the first report of MR angiographic findings of this rare variation. © The Author(s) 2015 Reprints and permissions:
    No preview · Article · Apr 2015
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    ABSTRACT: We present an extremely rare case of an aberrant course of the petrous internal carotid artery (ICA) associated with the ipsilateral occipital artery arising from the cervical ICA, a combination not previously reported by magnetic resonance (MR) angiography. The patient was a 53-year-old woman with no symptoms related to the anomalous ICA. Source images and partial maximum-intensity-projection images of MR angiography are useful in diagnosing these variations. Source images and curved multiplanar reconstruction images of computed tomography angiography are important for the accurate evaluation of reduced arterial diameter and the relationship between the anomalous artery and petrous bone.
    No preview · Article · Feb 2015 · Surgical and Radiologic Anatomy
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    ABSTRACT: Extremely rarely, the ophthalmic artery (OphA) arises from the A1 segment of the anterior cerebral artery (ACA). Discovery of this anomalous OphA during angiography or surgery has been reported in several patients. We report a case in which an OphA of ACA origin was diagnosed by magnetic resonance (MR) angiography and confirmed by selective cerebral angiography. To our knowledge, this is the first report of this variation with MR angiography. Careful observation of MR angiographic images is important for detecting rare arterial variations. Partial maximum-intensity-projection images are useful in identifying tiny anomalous arteries on MR angiography.
    No preview · Article · Feb 2015 · Surgical and Radiologic Anatomy
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    ABSTRACT: Moyamoya disease is a rare progressive cerebrovascular steno-occlusive disease associated with different variations of the cerebral arteries. We evaluated the types and prevalence of such variations among patients with moyamoya disease. In our institution during the past seven years, we diagnosed 72 patients (24 male, 48 female; aged 6 to 75 years, mean, 42 years) with moyamoya disease by magnetic resonance (MR) angiography using either a 3-Tesla or one of two 1.5-T imagers and a standard time-of-flight technique without contrast media. An experienced neuroradiologist retrospectively reviewed the images. There were 15 cerebral arterial variations in 13 of 72 patients with moyamoya disease (18.1%), including four basilar artery fenestrations, three ophthalmic arteries arising from the middle meningeal artery, two intracranial vertebral artery fenestrations, two persistent first cervical intersegmental arteries, two persistent trigeminal arteries, one extracranial origin of the posterior inferior cerebellar artery, and one persistent stapedial artery. Although our number of patients was small, moyamoya disease was frequently associated with variations of the cerebral arteries, especially fenestrations in the vertebrobasilar system and persistent trigeminal artery.
    No preview · Article · Dec 2014
  • Akira Uchino · Naoko Saito · Shinya Kohyama
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    ABSTRACT: The several types of agenesis of the internal carotid artery (ICA) are classified based on the aplastic segment of the ICA and types of collateral circulation. On magnetic resonance angiography, we incidentally found an extremely rare case in which the patient had 2 types of collateral circulation-anastomosis between the paraclinoid and supraclinoid segments of the contralateral ICA and anastomosis between the tip of the basilar artery and the posterior communicating artery. This is the first report of a case of ICA agenesis with 2 such types of collateral circulation.
    No preview · Article · Oct 2014 · Surgical and Radiologic Anatomy
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    ABSTRACT: Anastomosis of the carotid-anterior cerebral artery (ACA) is a rare anomalous vessel that arises from the internal carotid artery (ICA) at the level of the ophthalmic artery and takes an infraoptic and prechiasmatic path to anastomose with the ACA. It has known right-sided predominance. We report the case of an 83-year-old man with a left carotid-ACA anastomosis that was diagnosed by magnetic resonance (MR) angiography from the neck to the head during investigation of transient left hemiplegia. The right ICA was occluded at its origin. Our literature search revealed only six reported cases of left carotid-ACA anastomoses. We believe ours is the first case diagnosed by MR angiography.
    No preview · Article · Aug 2014 · Surgical and Radiologic Anatomy
  • Naoko Saito · Rania Hito · Peter A Burke · Osamu Sakai
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    ABSTRACT: Penetrating neck injuries are commonly related to stab wounds and gunshot wounds in the United States. The injuries are classified by penetration site in terms of the three anatomical zones of the neck. Based on this zonal classification system, penetrating injuries to the head and neck have traditionally been evaluated by conventional angiography and/or surgical exploration. In recent years, multidetector-row computed tomography (CT) angiography has significantly improved detectability of vascular injuries and extravascular injuries in the setting of penetrating injuries. CT angiography is a fast and minimally invasive imaging modality to evaluate penetrating injuries of the head and neck for stable patients. The spectrum of penetrating neck injuries includes vascular injury (extravasation, pseudoaneurysm, dissection, occlusion, and arteriovenous fistula), aerodigestive injury (esophageal and tracheal injuries), salivary gland injury, neurologic injury (spinal canal and cerebral injuries), and osseous injury, all of which can be evaluated using CT angiography. Familiarity with the complications and imaging characteristics of penetrating injuries of the head and neck is essential for accurate diagnosis and optimal treatment.
    No preview · Article · Jun 2014 · The Keio Journal of Medicine
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    ABSTRACT: Objectives: Clinical manifestations of sickle cell disease (SCD) can affect the orbit with prior reports describing changes in the lacrimal gland potentially related to chronic vaso-occlusion. The purpose of this study was to evaluate lacrimal gland volumes and quantifiable shifts in MR-relaxation times in patients with SCD. Methods: Thirteen patients with SCD and 12 age-matched control subjects underwent magnetic resonance imaging (MRI) of the orbits with 1.5-T MRI. Lacrimal glands were segmented manually; and gland volumes, peak, and mean T1- and T2-relaxation times were obtained from histogram analysis. Results: In patients with SCD, significant peak and mean T2 shortening (P < 0.001 and P < 0.001) and increased gland volume (P = 0.008) were observed. Significant correlations were seen between gland volumes in the patients SCD and peak T1 and T2 values (r = 0.6, P = 0.017; r = 0.56; P = 0.031) as well as between gland volumes and mean T1 and T2 values (r = 0.54, P = 0.039; r = 0.57, P = 0.026). Conclusion: Significant differences in MR relaxometry and lacrimal gland enlargement provide evidence of subclinical lacrimal gland pathology and chronic lacrimal gland changes patients with SCD.
    No preview · Article · May 2014 · Journal of Computer Assisted Tomography
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    ABSTRACT: PURPOSE/AIM To review the current CT and MR perfusion imaging methods in head and neck cancer. Also to describe various clinical applications of CT and MR perfusion imaging in head and neck cancer. CONTENT ORGANIZATION 1. Review of the current CT and MR perfusion imaging techniques being used to evaluate head and neck cancers including pros and cons for each technique: A)dynamic contrast enhanced CT perfusion, B)MR perfusion, i)With intravenous contrast: a)dynamic susceptibility contrast enhanced (DSC), b)dynamic contrast enhanced (DCE), ii)Without intravenous contrast: a)arterial spin labeling (ASL), b)intravoxel incoherent motion (IVIM). 2. Review of the clinical applications of CT and MR perfusion imaging in head and neck cancer. A)differentiation of tumor histology, B)monitoring tumor perfusion, C)prediction of tumor response to the treatment, D)evaluation of post-treatment tumor change, E)prediction and evaluation of treatment effect in the normal tissues. SUMMARY The major teaching points are: 1. Understanding of various techniques of CT and MR perfusion for head and neck cancers. 2. Understanding microvascular blood supply to the tumor as well as normal tissue that affects treatment response and side-effects. 3. Perfusion information may predict tumor response to various treatments, locoregional control, and treatment-related normal tissue injuries.
    No preview · Conference Paper · Dec 2013
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    ABSTRACT: PURPOSE/AIM High-grade glioma is the most common brain malignancy in adults. Concurrent temozolomide and radiotherapy is the new standard of care for patients with glioblastoma multiforme (GBM). Assessment of treatment response using conventional MRI is complicated by pseudoprogression and pseudoresponse. The purpose of this exhibit is: 1. To review treatments for GBM. 2. To summarize concepts and illustrate pseudoprogression and pseudoresponse on conventional MR imaging. 3. To discuss and illustrate the use of advanced MRI and PET in differentiating true progression from pseudoprogression CONTENT ORGANIZATION 1. Review of GBM treatments. 2. Definition and pathophysiology of pseudoprogression and psueodrtesponse. 3. Review of post-treatment conventional MRI: A. Recurrence B. Pseudoprogression C. Radionecrosis D. Pseudoresponse 4. Review criteria for tumor response after treatment and revised time-to-chemotherapy dependent criteria. 5. Discussion of imaging modalities to differentiate pseudoprogression from recurrence: A. Conventional MRI B. MR spectroscopy C. MR perfusion D. FDG-PET/CT SUMMARY Radiologists should be aware of the imaging features on post-treatment of GBM on conventional MRI. Having an understanding of the concepts and the utilization of advanced MRI and PET imaging techniques can help differentiate pseudopregression from true progression.
    No preview · Conference Paper · Dec 2013
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    ABSTRACT: Although identification of human papilloma virus (HPV) status in oropharyngeal squamous cell carcinoma (OPSCC) is essential in predicting treatment response, no imaging modality can currently determine whether a tumor is HPV-related. In this retrospective study, 26 patients with OPSCC confined to the lateral wall or the base of tongue underwent neck magnetic resonance imaging, using T1-, T2- and diffusion-weighted imaging (DWI). Apparent diffusion coefficients (ADCs) in a region of interest covering the largest available primary tumor area of OPSCC on a single slice of the ADC map were calculated using two b values (0 and 1,000 s/mm(2)). Mean and minimum ADCs were compared with HPV status, using p16 immunohistochemistry as a surrogate marker for HPV infection. Mean and minimum ADCs for HPV(+) OPSCC were significantly lower than those for HPV(-) OPSCC. A cut-off value of mean ADC for HPV(+) OPSCC of 1.027 × 10(-3) mm(2)/s yielded sensitivity and specificity of 83.33 and 78.57 %, respectively. In conclusion, the present study indicates that ADC could be used to predict HPV status in patients with OPSCC.
    No preview · Article · Jul 2013 · Archives of Oto-Rhino-Laryngology
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    ABSTRACT: The objective of this study was to correlate changes in computed tomography perfusion (CTP) parameters in the oropharyngeal mucosa following start of radiotherapy (RT) with acute mucositis in head and neck cancer patients. Fifteen patients were prospectively evaluated with serial CTP imaging. Computed tomography perfusion studies were obtained before RT; at weeks 2, 4, and 6 during RT; and 6 weeks after completion of RT. At week 2 during RT, mean transition time increased to 13.9% and 261.8% in patients with and without mucositis, respectively (P = 0.024). At week 6 of RT, patients with grade 3 mucositis had a 325.4% increase in blood flow compared with a 58.3% increase in patients with grade 0-2 mucositis (P = 0.039). Mean transition time decreased by 29.9% and increased by 187.4% in patients with grade 3 and grade 0-2 mucositis, respectively (P = 0.025). Mean transition time and blood flow changes in the oropharyngeal mucosa correlated with the incidence and severity of RT-related mucositis.
    No preview · Article · Jul 2013 · Journal of computer assisted tomography
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    ABSTRACT: Purpose: We evaluated the prevalence and imaging characteristics of ring-shaped lateral ventricular nodules (RSLVNs) detected by postcontrast brain magnetic resonance (MR) imaging. Materials and methods: We retrospectively reviewed cranial MR images of 1,241 patients who underwent contrast-enhanced brain imaging between January 1, 2008 and March 31, 2011, excluded images of inadequate quality of 130 patients, and ultimately analyzed images of 1,111 patients (544 male, 567 female). We assessed location, shape, and signal intensity of RSLVNs on T₁-weighted (T₁WIs), T₂-weighted (T₂WIs), fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted (DWIs) images and characteristics of contrast enhancement. Results: In 5 patients, we found 6 RSLVNs (0.45%), four in the frontal horn and two in the roof of the body. Three RSLVNs were round, two were oval, and one was lobular on axial images. All 6 RSLVNs were isointense with adjacent brain parenchyma on T₁WI, T₂WI, and DWI but slightly hyperintense on FLAIR images; none showed enhancement on postcontrast MR imaging. Five nodules serially examined (range, 8 to 24 months) showed no interval changes. Conclusions: Our MR imaging findings of a 0.45% prevalence of RSLVNs shows they are not so rare as previously reported. Except for configuration, all nodules had similar intensity, and none showed contrast enhancement. Absence of changes during the follow-up period seemed to indicate that the nodules have no clinical significance. However, their clear differentiation avoids unnecessary surgery.
    No preview · Article · May 2013 · Magnetic Resonance in Medical Sciences
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    ABSTRACT: Purpose: To identify and characterize sickle cell disease (SCD)-related changes in the composition of mandibular bone marrow using qMRI relaxometry histograms. Materials and methods: Thirteen SCD patients and 17 controls underwent brain MR imaging with the mixed turbo spin-echo (TSE) pulse sequence at 1.5T. The mandible was manually segmented and divided into body, angle, ramus, and condyle. T1 and T2 histograms of each mandible were modeled with Gaussian functions. The relaxation time histogram peaks were calculated, and the number of monomodal versus bimodal curves was compared. Results: SCD patients exhibited monomodal distributions on both T1 and T2 histograms, consistent with a composition of predominantly red hematopoietic marrow. Eighty-eight percent of mandibles in control subjects exhibited a bimodal distribution in T1 and all showed a bimodal distribution in T2, indicating mixed but predominantly yellow marrow composition. The second peak in control subjects was shorter in T1 and longer in T2, consistent with yellow marrow composition. Conclusion: Instead of physiological fatty replacement, SCD patients exhibit red marrow persistence in the mandible, likely due to the increased demand for hematopoiesis. This phenomenon can be manifested by a monomodal curve in both T1 and T2 relaxometric histograms.
    No preview · Article · May 2013 · Journal of Magnetic Resonance Imaging
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    ABSTRACT: Objective: To study age-related characteristics of T1 and T2 relaxation times and volume of the major salivary glands. Methods: Thirty-five subjects (0.5-87 years old) with normal salivary glands were imaged with mixed turbo spin-echo pulse sequences at 1.5-T magnetic resonance units. Bilateral parotid, submandibular, and sublingual glands were segmented manually. Histograms for each salivary gland were generated and modeled with Gaussian functions for every parameter. Results: Seventy parotid glands, 52 submandibular glands, and 50 sublingual glands were segmented and the histograms were analyzed. The parotid gland exhibited shorter-peak T1s and longer-peak T2s relative to the submandibular and sublingual glands. The peak T2s for all glands showed a minimum value between 2 and 4 years of age and increased monotonically thereafter. From birth to early adulthood, all glands increased in size logarithmically. Conclusion: Age-related relaxo-volumetric changes of the major salivary glands show clear T2 and volumetric age-related patterns for all glands.
    No preview · Article · Mar 2013 · Journal of computer assisted tomography
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    ABSTRACT: Introduction: A persistent dorsal ophthalmic artery (OA) is a rare variation that originates from the cavernous segment of the internal carotid artery (ICA) and enters the orbit via the superior orbital fissure (SOF). Occasionally, the OA also arises from the middle meningeal artery (MMA) and enters the orbit via the SOF. These two major variations of the OA have not been well described by magnetic resonance (MR) angiography. We evaluated their prevalence on MR angiography at 3 T. Methods: We retrospectively reviewed our database of MR angiographic images obtained using a 3 T imager. Of images of 846 patients, we evaluated those of 826 patients (1,652 OAs) with special attention to OA origin and its course into the orbit. We excluded images of the 20 because quality was insufficient to assess. Results: We found 7 (0.42%) persistent dorsal OAs among 1,652 OAs (right/left, 6/1; male/female, 3/4). Twenty-four (1.45%) OAs arose from the MMA (right/left/bilateral, 11/5/4; male/female, 10/10), three of which also demonstrated a small normally branching OA. In one patient, we observed both right persistent dorsal OA and left OA arising from the MMA. Conclusions: Per OA, the prevalence of persistent dorsal OA was 0.42% and of OA arising from the MMA, 1.45%, with a tendency toward right-side predominance. OA arising from the MMA can be seen bilaterally; preprocedural knowledge of this variation is important because of the danger associated with endovascular procedures of the external carotid system when the OA arises from the MMA.
    No preview · Article · Feb 2013 · Anatomia Clinica
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    ABSTRACT: Introduction: The origin of the vertebral artery (VA) varies, though most VAs enter the transverse foramen (TF) of the sixth cervical vertebra. On computed tomography (CT) angiographic images, we evaluated the prevalence of variations of both VA origin and its level of entry into the TF. Methods: We retrospectively reviewed CT angiographic images of 2,287 patients obtained using either of two 64-slice multidetector CT scanners. All patients were Japanese and underwent scanning from the aortic arch to the intracranial region; most had or were suspected of having cerebrovascular diseases. Results: The left VA (LVA) arose from the aorta between the left common carotid artery and left subclavian artery in 94 patients (4.1 %) and in other variations in 44 patients (1.9 %). The right VA (RVA) arose from the extreme proximal segment of the right subclavian artery in 72 patients (3.1 %) and in other variations in 14 patients (0.6 %). The LVA entered the sixth TF in 2,127 patients (93.0 %), and the RVA entered the sixth TF in 2,146 patients (93.8 %). Anomalous origin and anomalous entry level into the TF correlated strongly. Conclusions: The total prevalence of variation in the origin of the LVA was 6.0 % and of the RVA, 3.8 %. The total prevalence of variation in entry level into the TF was 7.0 % for the LVA and 6.2 % for the RVA. Recognition and reporting of these variations is important in interpreting CT angiography to prevent complications during surgery of the aortic arch or lower neck.
    No preview · Article · Jan 2013 · Neuroradiology

Publication Stats

267 Citations
82.42 Total Impact Points


  • 2010-2015
    • Saitama Medical University
      • Department of Radiology
      Саитама, Saitama, Japan
  • 2009-2014
    • Boston University
      Boston, Massachusetts, United States
  • 2013
    • Boston Medical Center
      Boston, Massachusetts, United States
  • 2012
    • Jichi Medical University
      Totigi, Tochigi, Japan
  • 2011
    • Beverly Hospital, Boston MA
      Beverly, Massachusetts, United States