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2014年5月28日

5476 18F-FDG PETはf-MRI以上に意識回復を予測するそうです。

 18F-FDG PET、意識回復を予測と言う記事が2014年04月25日のm3海外情報ジャーナルに出ており、そこをたどってLancetのページを見ると確かに脳糖代謝を測定する18F標識のFDG をトレーサーとするPETが、意識のない植物状態の患者の意識水準とその回復を予見する能力において、機能性MRIに勝っていたというベルギーのリージュ大学から投稿記事が確認できました。
 組織の糖代謝を測定する18F-FDG PETにはこのような脳の活動を評価する(歴史的に最初のReivich文献)という利用法と、癌組織の診断と言う2つの利用法がその開発当時からありましたが、最近は癌の診断の方が多くの注目を集めてきています。18F-FDG PETは空間分解能はともかく、時間分解能が劣るため、なにがしかの刺激を与えて、それに対する脳の反応を測定するといった利用面では機能的MRI(や脳磁図)に押され気味でした。意識のない患者の回復を予測するという時間分解能を問わない様な命題において、この18F-FDG PETの機能的MRIに対する優位性が確認できたというのはありうべき結果であろうと思われました。

文献:Johan S,et al.Diagnostic precision of PET imaging and functional MRI in disorders of consciousness: a clinical validation study.Lancet, Early Online Publication, 16 April 2014.

M3記事の抄訳によれば、「無反応覚醒症候群患者41人、閉じ込め症候群患者4人、最小意識状態患者81人を対象に、18F-フルオロ(デオキシ)グルコースを用いたポジトロン断層撮影(18F-FDG PET)と機能的MRI(fMRI)の意識障害診断精度を比較。最小意識状態患者の意識検出感度は、PETで93%、fMRIで45%。12カ月後の正確な転帰予測は74%、56%だった。」そうです。

ーーランセットの要旨ーーー
Diagnostic precision of PET imaging and functional MRI in disorders of consciousness: a clinical validation study

Johan Stender MD a c †, Olivia Gosseries PhD a †, Marie-Aurélie Bruno PhD a, Vanessa Charland-Verville MSc a, Audrey Vanhaudenhuyse PhD a, Athena Demertzi PhD a, Camille Chatelle PhD a, Marie Thonnard MSc a, Aurore Thibaut MSc a, Lizette Heine MSc a, Andrea Soddu PhD b, Mélanie Boly PhD a, Caroline Schnakers PhD a, Prof Albert Gjedde PhD c, Prof Steven Laureys PhD a Corresponding AuthorEmail Address

Summary

Background
Bedside clinical examinations can have high rates of misdiagnosis of unresponsive wakefulness syndrome (vegetative state) or minimally conscious state. The diagnostic and prognostic usefulness of neuroimaging-based approaches has not been established in a clinical setting. We did a validation study of two neuroimaging-based diagnostic methods: PET imaging and functional MRI (fMRI).

Methods
For this clinical validation study, we included patients referred to the University Hospital of Liège, Belgium, between January, 2008, and June, 2012, who were diagnosed by our unit with unresponsive wakefulness syndrome, locked-in syndrome, or minimally conscious state with traumatic or non-traumatic causes. We did repeated standardised clinical assessments with the Coma Recovery Scale—Revised (CRS—R), cerebral 18F-fluorodeoxyglucose (FDG) PET, and fMRI during mental activation tasks. We calculated the diagnostic accuracy of both imaging methods with CRS—R diagnosis as reference. We assessed outcome after 12 months with the Glasgow Outcome Scale—Extended.

Findings
We included 41 patients with unresponsive wakefulness syndrome, four with locked-in syndrome, and 81 in a minimally conscious state (48=traumatic, 78=non-traumatic; 110=chronic, 16=subacute). 18F-FDG PET had high sensitivity for identification of patients in a minimally conscious state (93%, 95% CI 85—98) and high congruence (85%, 77—90) with behavioural CRS—R scores. The active fMRI method was less sensitive at diagnosis of a minimally conscious state (45%, 30—61) and had lower overall congruence with behavioural scores (63%, 51—73) than PET imaging. 18F-FDG PET correctly predicted outcome in 75 of 102 patients (74%, 64—81), and fMRI in 36 of 65 patients (56%, 43—67). 13 of 42 (32%) of the behaviourally unresponsive patients (ie, diagnosed as unresponsive with CRS—R) showed brain activity compatible with (minimal) consciousness (ie, activity associated with consciousness, but diminished compared with fully conscious individuals) on at least one neuroimaging test; 69% of these (9 of 13) patients subsequently recovered consciousness.

Interpretation
Cerebral 18F-FDG PET could be used to complement bedside examinations and predict long-term recovery of patients with unresponsive wakefulness syndrome. Active fMRI might also be useful for differential diagnosis, but seems to be less accurate.

Funding
The Belgian National Funds for Scientific Research (FNRS), Fonds Léon Fredericq, the European Commission, the James McDonnell Foundation, the Mind Science Foundation, the French Speaking Community Concerted Research Action, the University of Copenhagen, and the University of Liège.
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