村山 和宏

A 77-year-old woman presented with worsening cognitive impairment, nausea and vomiting. Computed tomography (CT) of the head revealed a high-density mass that symmetrically filled both lateral ventricles. Magnetic resonance imaging (MRI) showed an enhanced mass with T1 and T2 prolongation and restricted diffusion on diffusion weighted imaging (DWI). Diagnosis was delayed until a post-mortem examination, which revealed the mass as a primary central nervous system lymphoma (PCNSL). A high-intensity tumor on DWI with lateral ventricle involvement should raise the possibility of PCNSL. © Oie et al.

BACKGROUND: In ruptured cerebral aneurysms (RCAs), identification of the rupture point of a cerebral aneurysm is useful for treatment planning. In unruptured cerebral aneurysms (URCAs), detection of the risk of aneurysmal rupture is also useful for patient management. OBJECTIVE: Electrocardiographic (ECG)-gated 3D-CT angiography was performed for patients with RCAs and URCAs using 320-row area detector CT (ADCT) to detect pulsation of the cerebral aneurysms. The clinical usefulness of this method was then evaluated. METHODS: Twelve patients had 12 RCAs, and 39 patients had 53 URCAs. A 320-row ADCT system was used to scan. ECG-gated reconstruction was then performed with the R-R interval divided into 20 phases. RESULTS: Pulsation was observed in 10 of the 12 RCAs. The bleeding site was considered to correspond to the area of pulsation. Pulsation was observed in 14 of 53 URCAs. Thirteen patients with 18 URCAs were followed. Of the 11 URCAs in which pulsation was not observed, 1 showed a change in shape. Of the 7 URCAs in which pulsation was observed, 3 showed a change in shape. URCAs in which pulsation was observed were more likely to show a change in shape (P = .082). CONCLUSION: The area of pulsation was found to correspond to the bleeding site in many RCAs. This information would be extremely useful for treatment planning. The detection of pulsation in an URCA is therefore considered to provide useful information for patient management.

Area Detector CT(AD-CT)は単に検出器が増えただけでなく,頭部を1回転で撮影できるほどに広くなった.通常の3D-CTAでは1秒程度で撮影が終了するため,造影剤の減量が可能となる.また,シーケンシャルスキャンにより動脈相〜静脈相までのvolume dataを連続的に取得できる.連続ボリュームスキャンでは心電同期下で撮影を行うことにより,頭部から,頚動脈,心臓(冠動脈)まで一度に検査が可能である.また160列ヘリカルスキャンも可能となり,頭部から恥骨部まで6秒程度で撮影が可能である.AD-CTではさまざまな検査ができるため,検査目的に適した撮影方法の選択,適切な照射線量,適切な再構成や解析も重要である.

The objectives of the study were to quantitatively assess whole-brain CT Perfusion (CTP) data using an automatic region of interest (ROI) analysis program in order to distinguish between the degree of ischemia in the ischemic core and that in the penumbra and to assess the relationship between expansion of the area of infarction. The subjects were 20 patients with acute cerebral infarction. Whole-brain CTP was performed for all subjects using a 320-row area detector CT scanner. The penumbra* is defined as the region in which the CBV value is 2 mL/100 g or more and the ischemic core* is defined as the region in which the CBV value is less than 2 mL/100 g. The quantitative values of CTP parameters were automatically measured using the automatic ROIs analysis program. The Mann-Whitney U test was applied to differentiate between the ischemic core* and the penumbra*. The reduction in perfusion pressure in the penumbra* was smaller in the group with expansion of the area of infarction than in the group without expansion of the area of infarction. The difference in the median values between the penumbra* and the ischemic core* was larger in the group with expansion of the area of infarction than the group without expansion of the area of infarction. It is considered that the quantitative analysis method using whole-brain CTP may be useful for more accurately distinguishing between the ischemic core and the penumbra and for evaluating the risk of expansion of the ischemic core into the penumbra.

100列以上の検出器をもった面検出器CTはもはや単なるCTではなくなった。ワンショットスキャンは単純レントゲン写真を撮影するかのごとくCTが撮影できる。また、撮影のプログラムを組んだシーケンシャルスキャンでは検査目的に応じた最適な撮影が可能となった。CT Perfusionでは脳血流だけでなく同じデータより3D-CTAの再構成が可能であり、動脈相だけでなく、あらゆる時相の再構成が可能である。AVMでは連続撮影により時間分解の良好は4D imageの取得が可能である。また心電同期再構成はヘリカルCTより画質が向上している。しかしながら、診療目的にあった適切な検査方法と画像処理をおこなわなければ、適切な結果がでないことを忘れてはならない。(著者抄録)

面検出器CT area detector CT(ADCT)は現在のスタンダードとなっているmulti-detector CT(MDCT)の一つの行き着く先である.しかし,ADCTは単にMDCTがさらに多列化したのではなく,それ以上に多くの優れた点を有している.検査時間の短縮,画質の向上,被曝の低減,サブトラクション機能の向上,dynamic 3D DATA(4D DATA)の取得などがあげられる.特に,脳神経領域では1回の検査で単純CT,造影CT,dynamic 3D-CTA,全脳のperfusion imageなどすべての種類の画像DATAの取得が可能となった.一方,CTの1回転あたりのCTDIは低減しているが,連続回転による検査が多く行われるため1検査あたりのCTDIは検査目的に合わせて最適化が必要である.また,大量に発生する画像データの処理や転送,保管などは,通常の画像ネットワーク,ワークステーションや画像サーバーの能力を超えており,専用のシステムが必要である.(著者抄録)

Purpose: To preliminarily evaluate the feasibility and potential diagnostic utility of whole-brain perfusion computed tomography (CT) performed with a prototype 256-detector row CT system over an extended range covering the entire brain to assess ischemic cerebrovascular disease. Materials and Methods: Institutional review board approval and informed consent were obtained. Eleven cases in 10 subjects (six men, four women; mean age, 64.3 years) with intra- or extracranial stenosis were retrospectively evaluated with whole-brain perfusion CT. Three readers independently evaluated perfusion CT data. The diagnostic performance of perfusion CT was visually evaluated with a three-point scale used to assess three factors. Differences between four axial perfusion CT images obtained at the basal ganglia level (hereafter, four-section images) and whole-brain perfusion CT images were assessed with the paired t test. In four subjects, the interval between perfusion CT and single photon emission computed tomography (SPECT) was 1-17 days (mean, 10.3 days). Correlation between perfusion CT findings and SPECT findings was assessed with the Spearman correlation coefficient. Results: Three-dimensional perfusion CT images and axial, coronal, and sagittal whole-brain perfusion CT images were displayed, and the extent of ischemia was assessed. Mean visual evaluation scores were significantly higher for whole-brain images than for four-section images (4.27 +/- 0.76 [standard deviation] vs 2.55 +/- 0.87). The cerebral blood flow ratios of the ischemic lesions relative to normal regions scanned with perfusion CT (x) and SPECT (y) showed a significant positive correlation (R(2) = 0.76, y = 0.44x + 0.37, P <.001). Conclusion: Perfusion CT performed with a 256-detector row CT system can be used to assess the entire brain with administration of one contrast medium bolus. Thus, ischemic regions can be identified with one examination, which has the potential to improve diagnostic utility. (C) RSNA, 2009