定量的脳核医学検査における注意点

核医学画像は，適切な補正を加えることで定量性に優れた情報を得ることができ る。脳核医学領域では，特に脳循環代謝状態の評価や神経受容体密度の計測等に 有用である。PET による脳循環計測は30 年以上の歴史があり，現在行われている SPECT による簡便な血流定量，統計画像解析法の基礎となっている。また，各種 受容体密度の定量や，最近広まりつつあるアミロイドイメージングなどは，治療法 の選択や病態解析に役立つ情報が得られるため，今後の臨床応用が期待されている。 脳核医学の定量計測に関するこれまでの歴史を振り返り，各種脳血流SPECT 製剤 の特徴と，それらを用いて検査を行う際に気を付けるべき点に関して概説し，慢性 期虚血性脳疾患の血行動態解析の方法や意義を再確認する。第73回～74回北陸核医学カンファレン

アルツハイマーガタ ニンチショウ カンジャ 二 オケル ニンチ キノウ 二 タイスル キヒトウ ノ コウカ

This is the author's version of a work that was accepted for publication in Geriatrics & Gerontology International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Geriatrics & Gerontology International, VOLUME 7, ISSUE 3, 2007-09-06, DOI: 10.1111/j.1447-0594.2007.00407.

Brain perfusion asymmetry in patients with oral somatic delusions

Oral cenesthopathy is a somatic delusion or hallucination involving the oral area and is categorized as a delusional disorder, somatic type. The pathophysiology of this intractable condition remains obscure. In this study, we clarified the pathophysiology of oral cenesthopathy by evaluating regional brain perfusion. We performed single photon emission computed tomography (SPECT) using (99m)Tc-ethylcysteinate dimer in 16 subjects (cenesthopathy:control = 8:8). The SPECT images were visually assessed qualitatively, and quantitative analyses were also performed using a three-dimensional stereotactic region-of-interest template. The visual assessment revealed a right > left perfusion asymmetry in broad areas of the brain among the patients. The quantitative analysis confirmed that the regional cerebral blood flow values on the right side were significantly larger than those on the left side for most areas of the brain in the patients. A comparison of the R/(R + L) ratios in both groups confirmed the significant brain perfusion asymmetry between the two sides in the callosomarginal, precentral, and temporal regions in the patients. Qualitative evaluation of the SPECT images revealed right > left brain perfusion asymmetry in broad regions of the brain. Moreover, the quantitative analyses confirmed the perfusion asymmetry between the two sides in the frontal and temporal areas. Those may provide the key for elucidation of the pathophysiology of oral cenesthopathy

Functional brain imaging in the dog : Single Photon Emission Tomography as a research and clinical tool for the investigation of canine brain physiology and pathophysiology

summary of doctoral dissertatio

Vascular Investigation and Management of Ischaemic Stroke

A variety of aetiological factors serve as targets for both treatment and prevention in ischaemic stroke. Research has shifted towards acute therapy and improving the risk / benefit ratio in secondary prevention. Current evidence based practice in ischaemic stroke is discussed in chapter one, and the background to subsequent chapters is introduced. The thesis is then divided into two broad areas that examine mechanisms by which vascular disease may cause ischaemic stroke, and the manner in which vascular risk may be modulated. Chapters two to four highlight controversies in investigation and management. Chapter two addresses a clinical dilemma - essentially whether a carotid lesion ipsilateral to a lacunar stroke should be considered symptomatic. Observational data comparing incidence of lacunar disease contralateral (group 1) or ipsilateral (group 2) to carotid artery disease, and stroke recurrence in patients in whom co-existent lacunar and carotid disease had been identified, were analysed. 32 patients had carotid disease contralateral to their lacunar stroke, compared to 61 patients with ipsilateral lacunar disease. Chi-squared testing indicated a positive association between unilateral lacunar stroke and ipsilateral carotid disease (p=0.003), and a just significant trend towards more severe carotid disease in group 2 (p=0.049). Recurrent ischaemic stroke occurred more commonly in group 2 than group 1, although this difference just failed to reach statistical significance (p=0.059). A positive association therefore exists between lacunar stroke and ipsilateral carotid disease that confers a poor prognosis. Cryptogenic stroke accounts for approximately 30% of ischaemic stroke. Inter-atrial septal abnormalities (patent foramen ovale (PFO) and atrial septal aneurysm) have been proposed as a cause of stroke. Chapter three details a meta-analysis of data examining the relationship between inter-atrial septal abnormalities and stroke. Comparing ischaemic stroke to controls, the odds ratio (OR) associated with PFO for all ages was 1.83 (95% C.I.=1.25-2.66). For atrial septal aneurysm it was 2.35 (1.46-3.77), and for both lesions in conjunction it was 4.96 (2.37-10.39). Homogeneous results were found within the group 55 years (1.27 (0.80-2.01), 3.43 (1.89-6.22) and 5.09 (1.25-20.74) respectively). Comparing cryptogenic stroke patients to patients with known stroke cause, heterogeneous results derived from total group examination (PFO 3.16 (2.30-4.35), atrial septal aneurysm 3.65 (1.34- 9.97), PFO and atrial septal aneurysm 23.26 (5.24-103.20)). In those 55, 3 studies produced heterogeneous results for PFO (2.26 (0.96-5.31)), while no data were available on atrial septal aneurysm prevalence. Meta-analysis therefore demonstrates significant association between both PFO and atrial septal aneurysm and ischaemic stroke in patients 55 years. The climate of uncertainty that surrounds the subject of 'PFO-associated stroke' has led to a wide spectrum of practice amongst specialists, which is examined in chapter four, using a questionnaire. 17% of respondents would investigate for PFO in all cryptogenic stroke patients, while 60% investigate only in those 55 years, and by 33% of respondents for those <55 years (p<0.01 for comparison of proportions). In a patient of any age with recurrent events, less than 5% of respondents would continue to use antiplatelet therapy alone. 45% would use warfarin, and 42% would refer the patient for a corrective procedure. For a patient with a large PFO, 57% (55 years) would refer (p=0.01), and for a patient with concomitant atrial septal aneurysm, 62% (55 years) would refer (p<0.01). A large PFO was felt to be the most important factor in decisions regarding lesion correction. Investigation practice varied considerably amongst specialists. Randomised trial design should reflect management practice in this area. The second part of the thesis reports clinical trials designed to examine the manner in which agents aimed at the modification of vascular risk may act in the acute and subacute phase of ischaemic stroke. The cholesterol- independent effects of statins may explain their efficacy in patients at high vascular risk. (Abstract shortened by ProQuest.)

Prosthetic joint replacements in hips and knees: pilot study for the development of a single imaging test in patients with painful prosthetic joint replacements. 18 F-Fluoride PET-CT and conventional radionuclide bone scans

An increasing number of annual joint replacement operations are performed. Prosthetic infection and aseptic loosening is very important and distinguishing between them allows prompt and accurate treatment but there is no consensus on how best to image these patients. I also reviewed the role of CT in prosthetic joint imaging with a spectrum of usual pathologic conditions and CT patterns. This showed that CT plays a significant role in detecting and demonstrating complications of joint prosthesis surgery but it may not be sufficient in itself. CT can be combined, in hybrid imaging, such as SPECT-CT and PET-CT. I assessed the magnitude of the problem with a retrospective study of painful prosthetic joints in UHCW from symptom onset to diagnosis. This demonstrated significant delays in diagnosis and the need for streamlined and reduced imaging tests with some patients undertaking multiple non-imaging and imaging tests. I performed a systematic review of the role of 18 F-NaF showed that sodium fluoride positron emission tomography (18 F-NaF-PET) is a promising tool with high sensitivity and specificity in the assessment of joint replacements after the ninth post-surgical month. A further study confirmed the practicality of performing dynamic 18 F NaF PET-CT in detecting aseptic loosening of lower limb prostheses but future research trials with larger patient populations are required. Beam hardening artefacts occur in CT and hybrid imaging of metallic prosthetic joints. A series of physics experiments to evaluate and correct beam hardening artefacts was performed to alleviate the problem. Beam hardening artefacts from prostheses reduce image quality on 18 F PET-CT. The experiments included pre-filtering with Aluminium; dual-energy CT and mathematical algorithms with MATLAB® filtered back projection. The results showed no significant difference in artefact reduction between the different methods. The artefact-reduction techniques introduce other secondary artefacts with subsequent image quality reduction. Analysis of data from the prospective dynamic 18 F-NaF PET-CT trial showed inconsistent results due to data corruption and dynamic 18 F-NaF data loss but quantitative methods with Time-Activity Curves and trend line assessment of 99m Tc-MDP 3-phase bone scans was more accurate. The trial problems were identified and suggestions were made for a larger study with opt-in methods for patient recruitment and more involved use of allied healthcare staff for patient recruitment. I designed and obtained funding for a study to use a novel radiopharmaceutical agent -99m Tc-Tilmanocept (Lymphoseek® ) to assess periprosthetic membranes in vivo. Lymphoseek® binds to the mannose receptor on the cell surface of macrophages and multinucleated giant cells which are likely to reflect wear particle aseptic loosening. Further in vitro periprosthetic membranes tests will also be performed using immunochemistry. This study has not yet been performed but it is hoped that a negative Tilmanocept scan would reassuringly make a diagnosis of wear particle induced aseptic loosening unlikely