Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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Dosimetric impacts of beam-hardening filter removal for the CyberKnife system Reviewed International journal Open Access

Takeshi Kamomae, Takuma Matsunaga, Junji Suzuki, Kuniyasu Okudaira, Fumitaka Kawabata, Yutaka Kato, Hiroshi Oguchi, Morihito Shimizu, Motoharu Sasaki, Yuki Takase, Mariko Kawamura, Kazuhiro Ohtakara, Yoshiyuki Itoh, Shinji Naganawa

PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS Vol. 86 page： 98 - 105 2021.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

Purpose: Equipment refurbishment was performed to remove the beam-hardening filter (BHF) from the CyberKnife system (CK). This study aimed to confirm the change in the beam characteristics between the conventional CK (present-BHF CK) and CK after the BHF was removed (absent-BHF CK) and evaluate the impact of BHF removal on the beam quality correction factors kQ. Methods: The experimental measurements of the beam characteristics of the present- and absent-BHF CKs were compared. The CKs were modeled using Monte Carlo simulations (MCs). The energy fluence spectra were calculated using MCs. Finally, kQ were estimated by combining the MC results and analytic calculations based on the TRS-398 and TRS-483 approaches. Results: All gamma values for percent depth doses and beam profiles between each CK were less than 0.5 following the 3%/1 mm criteria. The percentage differences for tissue-phantom ratios at depths of 20 and 10 cm and percentage depth doses at 10 cm between each CK were -1.20% and -0.97%, respectively. The MC results demonstrated that the photon energy fluence spectrum of the absent-BHF CK was softer than that of the presentBHF CK. The kQ values for the absent-BHF CK were in agreement within 0.02% with those for the present-BHF CK. Conclusions: The photon energy fluence spectrum was softened by the removal of BHF. However, no remarkable impact was observed for the measured beam characteristics and kQ. Therefore, the previous findings of the kQ values for the present-BHF CK can be directly used for the absent-BHF CK.

DOI： 10.1016/j.ejmp.2021.05.011

Age-related changes in the distribution of intravenously administered gadolinium-based contrast agents leaked into the cerebrospinal fluid in patients with suspected endolymphatic hydrops Reviewed

Toshio Ohashi, Shinji Naganawa, Saeko Iwata, Kayao Kuno

Japanese Journal of Radiology Vol. 39 ( 5 ) page： 433 - 441 2021.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Japan

Purpose: The purpose of this retrospective study was to investigate the relationship between age and leakage of intravenously administered gadolinium-based contrast agents (GBCAs) into the cerebrospinal fluid (CSF) by volumetric segmentation of the whole-cranium CSF. Materials and methods: In 30 patients clinically diagnosed with suspected endolymphatic hydrops, the three-dimensional real inversion recovery (3D-real IR) images were obtained at pre- and 4 h post-intravenous administration of a single dose of GBCA. The volume of interest was set on the whole-cranium CSF in the 3D-real IR image. The signal intensity (SI)-increase of the ventricular CSF and the extra-ventricular CSF at 4 h post-administration of GBCA compared to pre-administration was measured. The relationship between the age of the patient and the SI-increase was evaluated. Results: A correlation between age and the SI-increase was observed in the whole-cranium CSF. The correlation coefficient between age and the SI-increase in the ventricular CSF was higher than that in the extra-ventricular CSF. Conclusion: An age-related leakage of the intravenously administered GBCAs was found in the whole-brain CSF. The age-related change in the distribution of the GBCA leakage was more prominent in the ventricular CSF than in the extra-ventricular CSF.

DOI： 10.1007/s11604-020-01079-0

Early glottic cancer treatment with concurrent chemoradiotherapy with once-daily orally administered S-1 Reviewed

Yuuki Takase, Yoshiyuki Itoh, Kazuhiro Ohtakara, Mariko Kawamura, Junji Ito, Yumi Oie, Tamami Ono, Yutaro Sasaki, Ayumi Nishida, Shinji Naganawa

Nagoya Journal of Medical Science Vol. 83 ( 2 ) page： 251 - 258 2021.5

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Nagoya University

Glottic carcinoma is the most common laryngeal cancer. The outcomes for T1 bulky Glottic carcinoma and T2N0 Glottic carcinoma after radiation therapy alone are unsatisfactory. This study was conducted to evaluate the efficacy and safety of unique concurrent chemoradiotherapy regimen using S-1 for early glottic cancer. Concurrent chemoradiotherapy consisted of 60 Gy in 30 fractions with once-daily, orally administered S-1 exclusively within three to six hours prior to each irradiation. Twenty-one consecutive patients treated with this regimen were retrospectively reviewed. Initial complete remission was achieved in all patients without any subsequent local and/or regional recurrences to the last follow-up. The 4-year local control, overall survival, and disease-free survival rates were all 100%. No significant toxicities were observed, except for three cases with Grade 3 acute dermatitis. This regimen is highly effective and well-tolerated, and these results encourage further research to long-term efficacy and functional preservation.

DOI： 10.18999/nagjms.83.2.251

Diffusion analysis of fluid dynamics with incremental strength of motion proving gradient (DANDYISM) to evaluate cerebrospinal fluid dynamics Reviewed

Toshiaki Taoka, Hisashi Kawai, Toshiki Nakane, Takashi Abe, Rei Nakamichi, Rintaro Ito, Yuki Sato, Mayuko Sakai, Shinji Naganawa

Japanese Journal of Radiology Vol. 39 ( 4 ) page： 315 - 323 2021.4

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

<title>Abstract</title><sec>
<title>Purpose</title>
To visualize and analyze the dynamics of cerebrospinal fluid (CSF) motion in the cranium, we evaluated the distribution of motion-related signal dephasing by CSF on Diffusion ANalysis of fluid DYnamics with Incremental Strength of Motion proving gradient (DANDYISM) method, a composite imaging method using various low <italic>b</italic> values.

</sec><sec>
<title>Materials and methods</title>
This study examined ten subjects aged 25–58. We acquired DWIs on a 3T clinical scanner with <italic>b</italic> values 0, 50, 100, 200, 300, 500, 700, and 1000 s/mm<sup>2</sup> in total imaging time of 4 min. We constructed DANDYISM images and evaluated the CSF area distribution with decreased motion-dephasing signal using a scoring method.

</sec><sec>
<title>Results</title>
The DANDYISM images showed statistically significant higher CSF scores in the ventral posterior fossa, suprasellar cistern, and Sylvian vallecula compared to the lateral ventricle and frontal and parietal CSF spaces, indicating greater CSF movement in the former areas.

</sec><sec>
<title>Conclusion</title>
The results indicated prominent CSF motions in the ventral portion of the posterior fossa, suprasellar cistern, and Sylvian fissure but smaller motions in the lateral ventricles and parietal subarachnoid space. This method may provide information of CSF dynamics in the clinical settings within short imaging time.

</sec>

DOI： 10.1007/s11604-020-01075-4

Other Link： http://link.springer.com/article/10.1007/s11604-020-01075-4/fulltext.html

Variation in thyroid volumes due to differences in the measured length or area of the cross-sectional plane: A validation study of the ellipsoid approximation method using CT images Reviewed

Naotoshi Fujita, Katsuhiko Kato, Shinji Abe, Shinji Naganawa

Journal of Applied Clinical Medical Physics Vol. 22 ( 4 ) page： 15 - 25 2021.4

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：John Wiley and Sons Ltd

Purpose: This study examined the variation in the thyroid volume determined by the ellipsoid approximation method due to differences in the measured length or area of the cross-sectional plane of CT images. Methods: Forty-five patients with Graves' disease were included in this retrospective study. We designated the three-dimensional thyroid volumes extracted manually (VCT) as the reference data and calculated five approximate volumes for comparison: (a) the mean volume of 8100 different thyroid volumes depending on the diameter of the cross-sectional plane at the midpoint of the major axis, (Vellipsoid,mean)
(b) the volume using the maximum diameter and its orthogonal diameter, (Vellipsoid,maxlength)
(c) the maximum (Vellipsoid,maxvolume)
(d) minimum (Vellipsoid,minvolume) of the 8100 thyroid volumes
and (e) the volume determined with an equivalent circle diameter, (Vellipsoid,Heywood). Results: Thyroid volumes obtained via the ellipsoid approximation method varied depending on the diameter of the cross-sectional plane and included a mean error of approximately 20%, while the concordance correlation coefficient (CCC) differed for each approximate volume. Among these volumes, Vellipsoid,mean and Vellipsoid,Heywood were in good agreement with VCT, according to single regression analyses and the resultant CCC values, with mean errors of 0.1% and 10.4%, respectively. Conclusion: While Vellipsoid,Heywood approximated thyroid volumes with vastly reduced errors, we recommend utilizing three-dimensional thyroid volumetry if measurement accuracy is required.

DOI： 10.1002/acm2.13125

【Precision Medicine時代のCardiac Imaging 2021 後編】MRI:循環器領域における臨床の最前線と技術の到達点 MRIの技術革新が広げる循環器画像診断の可能性大血管の4D flow MRI Reviewed

櫻井康雄, 竹原康雄, 水野崇, 阿部真治, 長縄慎二

INNERVISION Vol. 36 ( 5 ) page： 7 - 9 2021.4

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：(株)インナービジョン

MRIは、周辺技術の進歩により高画質、高速化が進められ、画像診断において重要な位置を占めている。MRによる生体内情報として、各組織のプロトンの密度、T1緩和、T2緩和、磁化率、拡散、血流、体液の流れ、灌流情報などの画像化、代謝情報が得られるが、その中で、血流や体液の流速を計測する試みは、位相コントラスト法を用いて古くから行われてきた。本稿では、血管領域に関する機能画像として、研究段階ではあるが、三次元の空間に時間軸情報を加えた三次元シネ位相コントラスト(phase contrast:PC)法である「4D flow MRI」について、主として大血管における現状を紹介する。(著者抄録)

Time-resolved 3D cine phase-contrast magnetic resonance imaging (4D-flow MRI) can quantitatively assess portosystemic shunt severity and confirm normalization of portal flow after embolization of large portosystemic shunts. International journal

Ryota Hyodo, Yasuo Takehara, Takashi Mizuno, Kazushige Ichikawa, Yoji Ishizu, Masataka Sugiyama, Shinji Naganawa

Hepatology research : the official journal of the Japan Society of Hepatology Vol. 51 ( 3 ) page： 343 - 349 2021.3

Language：English Publishing type：Research paper (scientific journal)

Diagnosis and severity assessments of portosystemic shunts (PSSs) are important because the pathology sometimes results in severe hepatic encephalopathy, which can be treated almost completely by shunt embolization. At present, morphological assessment of PSS is performed mainly by computed tomography, and ultrasound is used for blood flow assessment. In two cases of PSS-related hepatic encephalopathy, we used time-resolved 3D cine phase-contrast (4D-flow) magnetic resonance imaging (MRI) to assess blood flow before and after shunt embolization. Before the intervention, blood flow in the main trunk of the superior mesenteric vein was mostly hepatofugal. However, post-interventional 4D-flow MRI revealed hepatopetal superior mesenteric vein flow with significantly increased portal vein blood flow. 4D-flow MRI is an ideal adjunct to Doppler ultrasonography, allowing for objective and visual assessment of morphology and blood flow of the portal venous system, including PSSs, and is useful in determining the indications for, and outcome of, PSS embolization.

DOI： 10.1111/hepr.13616

MRによる頭蓋内間質液・脳脊髄液動態の解明 Invited Reviewed

長縄慎二、田岡俊昭、川井　恒

脳とこころの研究センター　脳疾患克服に向けた次世代創薬開発のためのコホート・コンソーシアム型研究拠点形成 Vol. - ( - ) page： 23 - 23 2021.3

TGSE-Radial Sampling型DWIにおける自作ファントムを用いたADC値と磁化率歪みの評価 Reviewed

加藤裕, 熊谷始紀, 奥平訓康, 丸山克也, 田岡俊昭, 長縄慎二

日本放射線技術学会総会学術大会予稿集 Vol. 77回 page： 200 - 200 2021.3

Imaging of endolymphatic hydrops on a vertigo attack of Meniere's disease. Reviewed

Takafumi Nakada, Masaaki Teranishi, Saiko Sugiura, Yasue Uchida, Shinji Naganawa, Michihiko Sone

Nagoya journal of medical science Vol. 83 ( 1 ) page： 209 - 216 2021.2

Language：English Publishing type：Research paper (scientific journal)

Meniere's disease (MD) characteristically presents with endolymphatic hydrops (EH), which can be visualized with gadolinium-enhanced inner ear magnetic resonance imaging (MRI). Inner ear membrane rupture has been suspected to cause MD attacks, but this remains controversial. We report a case of MD coincidentally evaluated the EH using 3-Tesla MRI during a vertigo attack. A 78-year-old man with bilateral definite MD visited the hospital outpatient department due to a vertigo attack. To evaluate of endolymphatic hydrops on the attack, inner ear MRI was obtained 4 hours after intravenous injection of gadolinium agent. Vestibular EH in each ear occupied almost all vestibular endolymphatic space in contact with the oval window and herniated into the horizontal semi-circular canal. The endolymphatic space was enlarged, without collapse or mixture of contrast agent. No difference was found between ears. EH on a vertigo attack was associated with significant swelling, without obvious evidence of membranous ruptures on magnetic resonance images.

DOI： 10.18999/nagjms.83.1.209

コロナウイルス肺炎のAi診断 Invited Reviewed

伊藤倫太郎、岩野信吾、長縄慎二

臨床免疫・アレルギー科 Vol. 75 ( 2 ) page： 189 - 193 2021.2

Iodine-related attenuation in contrast-enhanced dual-energy computed tomography in small-sized solid-type lung cancers is associated with the postoperative prognosis. Reviewed International journal

Shingo Iwano, Shinichiro Kamiya, Rintaro Ito, Shota Nakamura, Shinji Naganawa

Cancer imaging : the official publication of the International Cancer Imaging Society Vol. 21 ( 1 ) page： 7 - 7 2021.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: To investigate the correlation between iodine-related attenuation in contrast-enhanced dual-energy computed tomography (DE-CT) and the postoperative prognosis of surgically resected solid-type small-sized lung cancers. METHODS: We retrospectively reviewed the DE-CT findings and postoperative course of solid-type lung cancers ≤3 cm in diameter. After injection of iodinated contrast media, arterial phases were scanned using 140-kVp and 80-kVp tube voltages. Three-dimensional iodine-related attenuation (3D-IRA) of primary tumors at the arterial phase was computed using the "lung nodule" application software. The corrected 3D-IRA normalized to the patient's body weight and contrast medium concentration was then calculated. RESULTS: A total of 120 resected solid-type lung cancers ≤3 cm in diameter were selected for analysis (82 males and 38 females; mean age, 67 years). During the observation period (median, 47 months), 32 patients showed postoperative recurrence. Recurrent tumors had significantly lower 3D-IRA and corrected 3D-IRA at early phase compared to non-recurrent tumors (p = 0.046 and p = 0.027, respectively). The area under the receiver operating characteristic curve for postoperative recurrence was 0.624 for the corrected 3D-IRA at early phase (p = 0.025), and the cutoff value was 5.88. Kaplan-Meier curves for disease-free survival indicated that patients showing tumors with 3D-IRA > 5.88 had a significantly better prognosis than those with tumors showing 3D-IRA < 5.88 (p = 0.017). CONCLUSIONS: The 3D-IRA of small-sized solid-type lung cancers on contrast-enhanced DE-CT was significantly associated with postoperative prognosis, and low 3D-IRA tumors showed a higher TNM stage and a significantly poorer prognosis.

DOI： 10.1186/s40644-020-00368-1

Lesion-specific prognosis by magnetic resonance imaging in sudden sensorineural hearing loss. Reviewed International journal

Cheng-Jui Yang, Tadao Yoshida, Satofumi Sugimoto, Masaaki Teranishi, Masumi Kobayashi, Naoki Nishio, Shinji Naganawa, Michihiko Sone

Acta oto-laryngologica Vol. 141 ( 1 ) page： 5 - 9 2021.1

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: High signals in the inner ear of idiopathic sudden sensorineural hearing loss (ISSNHL) on magnetic resonance imaging (MRI) have been reported, but no quantitative evaluation has yet been done. OBJECTIVES: To evaluate hearing outcomes and cochlear signal intensities on 3-T heavily T2-weighted three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (hT2W-3D-FLAIR) in patients with ISSNHL. MATERIALS AND METHODS: Twenty-nine patients with ISSNHL were included. Patients underwent hT2W-3D-FLAIR with intravenous gadolinium injection and pure tone audiometry (PTA) at initial visits and 3 months later. Signal intensity ratios (SIRs) were measured in the basal or apical-middle turns of the affected cochlea. A statistical analysis of relationships between SIRs and the average hearing levels (HLs) at low (125, 250, and 500 Hz) and high (2, 4, and 8 kHz) tone frequencies was performed. RESULTS: Hearing improvements at high-tone frequencies in ears with HLs ≥60 dB were significantly worse in those with high SIRs at the basal turns on pre-contrast images. Similarly, hearing improvements at low-tone frequencies in ears with HLs ≥60 dB were significantly worse in those with high SIRs at the apical-middle turns on post-contrast images. CONCLUSIONS AND SIGNIFICANCE: High SIRs on hT2W-3D-FLAIR indicate cochlear disturbances with severe ISSNHL and could provide lesion-specific prognostic information.

DOI： 10.1080/00016489.2020.1827159

Imaging for central nervous system (CNS) interstitial fluidopathy: disorders with impaired interstitial fluid dynamics. Reviewed

Toshiaki Taoka, Shinji Naganawa

Japanese journal of radiology Vol. 39 ( 1 ) page： 1 - 14 2021.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

After the introduction of the glymphatic system hypothesis, an increasing number of studies on cerebrospinal fluid and interstitial fluid dynamics within the brain have been investigated and reported. A series of diseases are known which develop due to abnormality of the glymphatic system including Alzheimer's disease, traumatic brain injury, stroke, or other disorders. These diseases or disorders share the characteristics of the glymphatic system dysfunction or other mechanisms related to the interstitial fluid dynamics. In this review article, we propose "Central Nervous System (CNS) Interstitial Fluidopathy" as a new concept encompassing diseases whose pathologies are majorly associated with abnormal interstitial fluid dynamics. Categorizing these diseases or disorders as "CNS interstitial fluidopathies," will promote the understanding of their mechanisms and the development of potential imaging methods for the evaluation of the disease as well as clinical methods for disease treatment or prevention. In other words, having a viewpoint of the dynamics of interstitial fluid appears relevant for understanding CNS diseases or disorders, and it would be possible to develop novel common treatment methods or medications for "CNS interstitial fluidopathies."

DOI： 10.1007/s11604-020-01017-0

Distribution of gadolinium-based contrast agent after leaking into the cerebrospinal fluid: Comparison between the cerebral cisterns and the lateral ventricles Reviewed

Toshio Ohashi, Shinji Naganawa, Saeko Iwata, Kayao Kuno

Magnetic Resonance in Medical Sciences Vol. 20 ( 2 ) page： 175 - 181 2021

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

Purpose: Leakage of a small amount of intravenously administered gadolinium-based contrast agents (GBCAs) into the cerebrospinal fluid (CSF) space has been reported, even in healthy subjects without blood-brain barrier disruption. Several candidates including the choroid plexus and cortical veins have been proposed as the source of the leakage. The purpose of this study was to evaluate the distribution of intravenously administered GBCA leakage into the CSF by comparing the contrast enhancement of the cerebral cisterns to the lateral ventricles (LVs). Methods: In 26 patients with a suspicion of endolymphatic hydrops (21-80 years old), a three-dimensional real inversion recovery (3D-real IR) image was obtained at pre-, and at 5 min, and 4 h post-intravenous administration of a single dose of GBCA (IV-SD-GBCA). In the 3D-real IR image, the signal intensities (SIs) in the anterior horn of the LV (LVante), the trigone of the LV (LVtri), the Sylvian fissure (SyF), the ambient cistern (Amb), the prepontine cistern (PPC), the cerebellopontine angle cistern (CPA), and the vitreous (Vit) were measured. The differences in the SI at pre-, and at 5 min and 4 h post-IV-SD-GBCA were evaluated for each region. The change in the SI pre- to post-IV-SD-GBCA (SIchange) were calculated for each region. The differences in the SIchange in each region were evaluated at 5 min and 4 h post-IV-SD-GBCA. A Steel-Dwass’s test was applied to correct for multiple comparisons. Results: The SIs of all regions at 4 h post-IV-SD-GBCA were significantly higher compared with pre-IV-SD-GBCA (P &lt
0.05). The SIchange in the SyF, Amb, PPC, and the CPA were significantly higher compared with those of the LVante, LVtri, and the Vit at 4 h post-IV-SD-GBCA (P &lt
0.05). Conclusion: The contrast enhancement in the cerebral cisterns was greater than that in the LVs.

DOI： 10.2463/mrms.mp.2020-0016

Three Dimensional Ultra-short Echo Time MRI Can Depict Cholesterol Components of Gallstones Bright. Reviewed

Mamoru Takahashi, Yasuo Takehara, Kenji Fujisaki, Tomoyuki Okuaki, Yukiko Fukuma, Norihiro Tooyama, Katsutoshi Ichijo, Tomoyasu Amano, Satoshi Goshima, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 4 ) page： 359 - 370 2021

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: Non-calcified cholesterol stones that are small in size are hard to be depicted on CT or magnetic resonance cholangiopancreatography. This institutional review board (IRB)-approved retrospective in vitro study aims to characterize contrast behaviors of 3 main components of the gallstones, i.e., cholesterol component (CC), bilirubin calcium component (BC) and CaCO3 (CO) on 3D radial scan with ultrashort TE (UTE) MRI, and to test the capability of depicting CC of gallstones as bright signals as compared to background saline. METHODS: Fourteen representative gallstones from 14 patients, including 15 CC, 6 BC and 4 CO, were enrolled. The gallstones underwent MRI including fat-saturated T1-weighted image (fs-T1WI) and UTE MRI with dual echoes. The contrast-to-noise ratio (CNR) and the chemical analysis for the 25 portions of the stones were compared. RESULTS: BC was bright on fs-T1WI, which did not change dramatically on UTE MRI and the signal did not remain on UTE subtraction image between dual echoes. Whereas the CC was negative or faintly positive signal on fs-T1WI, bright signal on UTE MRI and the contrast remained even higher on the UTE subtraction, which reflected their short T2 values. Median CNRs and standard errors of the segments on each imaging were as follows: on fs-T1WI, -10.2 ± 4.2 for CC, 149.7 ± 27.6 for BC and 37.9 ± 14.3 for CO; on UTE MRI first echo, 16.7 ± 3.3 for CC, 74.9 ± 21.3 for BC and 17.7 ± 8.4 for CO; on UTE subtraction image, 30.2 ±2.0 for CC, -11.2 ± 5.4 for BC and 17.8 ± 10.7 for CO. Linear correlations between CNRs and cholesterol concentrations were observed on fs-T1WI with r = -0.885, (P < 0.0001), UTE MRI first echo r = -0.524 (P = 0.0072) and UTE subtraction with r = 0.598 (P = 0.0016). CONCLUSION: UTE MRI and UTE subtraction can depict CC bright.

DOI： 10.2463/mrms.mp.2020-0009

Relationship between Time-dependent Signal Changes in Parasagittal Perivenous Cysts and Leakage of Gadolinium-based Contrast Agents into the Subarachnoid Space. Reviewed

Shinji Naganawa, Rintaro Ito, Rei Nakamichi, Mariko Kawamura, Toshiaki Taoka, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 4 ) page： 378 - 384 2021

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: To investigate the association between signal changes over time in perivenous cystic structures near the superior sagittal sinus and leakage of a gadolinium-based contrast agent (GBCA) into the subarachnoid space in patients with suspected endolymphatic hydrops. METHODS: Fifty-one cystic structures in 27 cases were evaluated. The signal intensity of the cystic structures was measured on 3D real inversion recovery (3D-real IR) images obtained at pre-, and at 10 min, 4 hrs and 24 hrs post-intravenous administration (IV) of GBCA. Signal enhancement of the cystic structures from the pre-contrast images at each time point was compared in subjects with leakage (positive) versus those without leakage (negative) using an ANOVA. Fisher's exact probability test was used to compare the maximum contrast-enhanced time point between positive and negative groups. We used 5% as a threshold to determine statistical significance. RESULTS: In leakage positive subjects, mean signal enhancement of the cysts was significantly greater at 4 and 24 hrs compared to 10 min. However, although there was a trend of an increase from 4 to 24 hrs, the difference was not significant. In the leakage negative group, mean signal enhancement of the cysts was significantly higher at 4 hrs compared to 10 min and 24 hrs. There was no significant difference between 10 min and 24 hrs. In the positive group, the maximum signal increase was found in 10/38 and 28/38 cysts at 4 and 24 hrs after IV-GBCA, respectively. In the leakage negative group, the maximum signal increase was found in 10/13 and 3/13 cysts at 4 and 24 hrs, respectively (P = 0.0019). CONCLUSION: There was an association between signal changes over time after IV-GBCA in perivenous cystic structures and leakage of GBCA. Further research to clarify the impact of cystic structures on the function of the waste clearance system of the brain is warranted.

DOI： 10.2463/mrms.mp.2020-0138

Relationship between Parasagittal Perivenous Cysts and Leakage of Gadolinium-based Contrast Agents into the Subarachnoid Space around the Cortical Veins after Intravenous Administration. Reviewed

Shinji Naganawa, Rintaro Ito, Rei Nakamichi, Mariko Kawamura, Hisashi Kawai, Toshiaki Taoka, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 3 ) page： 245 - 252 2021

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: The purpose of this retrospective study was to investigate the relationship between the number and size of cystic structures around the cortical veins near the superior sagittal sinus and the leakage of gadolinium-based contrast agent (GBCA) around the cortical veins. METHODS: Of 190 patients (91 male and 99 female), that were scanned at 4 h after an intravenous injection of GBCA as a diagnostic examination for endolymphatic hydrops, 6 patients with GBCA leakage were younger than the previously proposed threshold age of 37.3 years for leakage. Six age-matched patients without leakage were also included for reference. In addition, we included 8 cases without leakage that were older than the hypothesized threshold of 37.3 years, as well as 8 age-matched patients with GBCA leakage into the cerebrospinal fluid space. The number of cysts was counted and the sizes were measured in these 28 patients (age: 32-60 years old, 13 men and 15 women). RESULTS: The mean number of cysts surrounding the cortical veins in the parasagittal region was 4.29 ± 1.77 vs. 1.79 ± 1.05 (P = 0.0001) in the subjects with and without GBCA leakage, respectively. The mean size of the largest cysts was at 8.89 ± 3.49 mm vs. 5.69 ± 2.29 (P = 0.009) in the subjects with and without GBCA leakage, respectively. CONCLUSION: The number and size of the perivenous cystic structures near the superior sagittal sinus is greater in subjects with GBCA leakage into the subarachnoid space compared with those without leakage. Future research regarding the histological and functional details of these parasagittal cystic structures is needed.

DOI： 10.2463/mrms.mp.2020-0062

Portal Vein Stenosis Following Liver Transplantation Hemodynamically Assessed with 4D-flow MRI before and after Portal Vein Stenting. Reviewed

Ryota Hyodo, Yasuo Takehara, Takashi Mizuno, Kazushige Ichikawa, Yasuhiro Ogura, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 3 ) page： 231 - 235 2021

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

We present a case of a patient who underwent portal vein (PV) stenting for PV stenosis after a living-donor liver transplantation. A pretreatment 3D cine phase-contrast (4D-flow) MRI showed decreased, though hepatopetal, blood flow in the PV. After stenting, 4D-flow MRI confirmed an improvement in PV flow, with a more homogeneous flow distribution to each hepatic segment. 4D-flow MRI are valuable for understanding the hemodynamics of this area, planning for treatments, and evaluating the outcome of the interventions.

DOI： 10.2463/mrms.ici.2020-0057

MR Imaging of Endolymphatic Hydrops: Utility of iHYDROPS-Mi2 Combined with Deep Learning Reconstruction Denoising. Reviewed

Shinji Naganawa, Rei Nakamichi, Kazushige Ichikawa, Mariko Kawamura, Hisashi Kawai, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 3 ) page： 272 - 279 2021

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: MRI of endolymphatic hydrops (EH) 4 h after intravenous administration of a single dose of gadolinium-based contrast agent is used for clinical examination in some institutions; however, further improvement in image quality would be valuable for wider clinical utility. Denoising using deep learning reconstruction (Advanced Intelligent Clear-IQ Engine [AiCE]) has been reported for CT and MR. The purpose of this study was to compare the contrast-to-noise ratio of endolymph to perilymph (CNREP) between the improved hybrid of reversed image of the positive endolymph signal and the native image of the perilymph signal multiplied with the heavily T2-weighted MR cisternography (iHYDROPS-Mi2) images, which used AiCE for the three source images (i.e. positive endolymph image [PEI], positive perilymph image [PPI], MR cisternography [MRC]) to those that did not use AiCE. We also examined if there was a difference between iHYDROPS-Mi2 images with and without AiCE for degree of visual grading of EH and in endolymphatic area [EL] ratios. METHODS: Nine patients with suspicion of EH were imaged on a 3T MR scanner. iHYDROPS images were generated by subtraction of PEI images from PPI images. iHYDROPS-Mi2 images were then generated by multiplying MRC with iHYDROPS images. The CNREP and EL ratio were measured on the iHYDROPS-Mi2 images. Degree of radiologist visual grading for EH was evaluated. RESULTS: Mean CNREP ± standard deviation was 1681.8 ± 845.2 without AiCE and 7738.6 ± 5149.2 with AiCE (P = 0.00002). There was no significant difference in EL ratio for images with and without AiCE. Radiologist grading for EH agreed completely between the 2 image types in both the cochlea and vestibule. CONCLUSION: The CNREP of iHYDROPS-Mi2 images with AiCE had more than a fourfold increase compared with that without AiCE. Use of AiCE did not adversely affect radiologist grading of EH.

DOI： 10.2463/mrms.mp.2020-0082

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