This manuscript presents an investigation and application of the medical radiographic technique of Dynamic Contrast-enhanced Computed Tomography with an emphasis on its application to the measurement of tissue perfusion using the techniques of CT Perfusion. CT Perfusion was used in association with Fluoro- Deoxy Glucose Positron Emission Tomography (FDG PET) to investigate altered blood flow due to the angiogenic effects of tumour in the clinical setting of medical imaging for cancer diagnosis and staging. CT perfusion, CT enhancement and Doppler ultrasound studies were compared in a series of patient studies performed for the assessment of metastatic liver disease. There was good correlation between all techniques for the arterial phase but not between Doppler measurements of the portal phase and any CT measurement. A new method was developed for quantifying CT perfusion and enhancement values, the Standardised Perfusion Value (SPV) and the Standardised Enhancement Value (SEV). The SPV was shown to correlate with FDG uptake in a series of 16 patient studies of lung nodules, an unexpected and potentially important finding that if confirmed in a larger study may provide an additional diagnostic role for CT in the assessment of lung nodules. Investigation of a commercially available package for the determination of CT Perfusion, CT Perfusion GE Medical Systems, was undertaken in a small series of brain studies for assessment of acute stroke. This data set showed the technique to positively identify patients with non-hemorrhagic stroke in the presence of a normal conventional CT, to select those cases where thrombolysis is appropriate, and to provide an indication for prognosis. An investigation of the accuracy and cost-effectiveness of FDG PET in solitary pulmonary nodules using Australian data was carried out. FDG PET was found to be accurate, cost saving and cost effective for the characterisation of indeterminate solitary pulmonary nodules in Australia. This work was expanded to include the impact of quantitative contrast enhancement CT (QECT) on the cost-effectiveness of FDG PET. The addition of QECT is a cost effective approach, however whether QECT is used alone or in combination with FDG PET will depend on local availability of PET, the cost of PET with respect to surgery and the prior probability of malignancy. A published review of CT perfusion, clinical applications and techniques, is included in the body of the work. Dynamic contrast-enhanced CT and FDG PET were used to investigate blood flow, expressed as SPV, and metabolic relationships in non-small cell lung cancers (NSCLC) of varying size and stage. A significant correlation between SPV and FDG uptake was only found for tumours smaller than 4.5 cm2. Blood flow-metabolic relationships are not consistent in NSCLC but depend on tumour size and stage. Dynamic contrast-enhanced CT as an adjunct to an FDG study undertaken using integrated PET-CT offers an efficient way to augment the assessment of tumour biology with possible future application as part of clinical care. In summary the work has developed a method for standardizing the results of dynamic contrast-enhanced CT and investigated its potential when applied with FDG PET to improve the diagnosis and staging of cancers.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23074号 / 医博第4701号 / 新制||医||1049(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 妹尾 浩, 教授 増永 慎一郎, 教授 川口 義弥 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

Yes / The purpose of this paper is to identify current UK screening practices prior to contrast-enhanced CT. To determine the patient management strategies to minimize the risk of contrast-induced acute kidney injury (CI-AKI) risk in outpatients. An invitation to complete an electronic survey was distributed to the CT managers of 174 UK adult National Health Service hospital trusts. The survey included questions related to local protocols and national guidance on which these are based. Details of the assessment of renal function prior to imaging and thresholds for contrast contraindication and patient management were also sought. A response rate of 47.1% was received. Almost all sites had a policy in place for contrast administration (n = 80/82; 97.6%). The majority of sites require a blood test on outpatients undergoing a contrast-enhanced CT scan (n = 75/82; 91.5%); however, some (15/75; 20.0%) sites only check the result in patients at high risk and a small number (7/82; 8.5%) of sites indicated that it was a referrer responsibility. The estimated glomerular filtration rate (eGFR) or serum creatinine (SCr) result threshold at which i.v. contrast was contraindicated varied and 19 different threshold levels of eGFR or SCr were identified, each leading to different prophylactic strategies. Inconsistency was noted in the provision of follow-up blood tests after contrast administration. The wide variation in practice reflects inconsistencies in published guidance. Evidence-based consensuses of which patients to test and subsequent risk thresholds will aid clinicians identify those patients in which the risk of CI-AKI is clinically significant but manageable. There is also a need to determine the value of the various prophylactic strategies, follow-up regimen and efficient service delivery pathways. This survey has identified that further work is required to define which patients are high risk, confirm those which require renal function testing prior to contrast administration and how best to manage patients at risk of CI-AKI. The role of new technologies within this service delivery pathway requires further investigation.

Židininiai kepenų pakitimai (ŽKP) – vieni dažnesnių patologinių radinių tiriant pacientus dėl įvairių virškinimo ar kitų organizmo sistemų ligų. Įvairių spindulinės diagnostikos metodų dėka nustačius patologinius židinius kepenyse ypač svarbi jų klinikinė diferencinės diagnostikos reikšmė. ŽKP diferencinės diagnostikos esmė yra kiek įmanoma tikslesnis židinio kepenyse kraujotakos nustatymas ir aprašymas. Šios problemos sprendime naujų galimybių įgyja santykinai nauja ir Lietuvoje niekur kitur dar neatliekama UG tyrimo su i/v kontrastavimu metodika, kurios metu gaunami rezultatai lyginami su dominuojančių įprastų KT ir MRT kontrastinių tyrimų rezultatais. Tikslas: nustatyti radiologinių tyrimų vertę diagnozuojant židininius kepenų pakitimus (ŽKP) Uždaviniai: 1. Nustatyti įprastinio UG, UG su i/v kontrastavimu ir KT su i/v kontrastavimu diagnostikos metodų tikslumo rodiklius nepiktybiniams ir piktybiniams ŽKP. 2. Nustatyti UG ir KT su i/v kontrastavimu vertingiausius diagnostikos kriterijus vertinant židininių kepenų pokyčių prigimtį. 3. Palyginti tarpusavyje UG ir KT su i/v kontrastavimu nustatytų židininių kepenų pakitimų diagnostikos metodų tikslumo rodiklius nepiktybiniams ir piktybiniams ŽKP. 4. Įvertinti kepenų hemangiomų radiologinių diagnostikos metodų tikslumo vertę. / Focal hepatic lesions (FHL) are one of the most common pathological findings in patients who are examined for gastrointestinal or other diseases. The rigorous description of blood circulation in the hepatic focus is essential in differential diagnosis of FHL. US with i/v contrast enhancement is a new imaging method enabling definition of nature of FHL, follow-up, treatment efficacy and monitoring for possible relapse of the process. This study is conducted solely in the Radiology Department of Kaunas University of Medicine Hospital. Aim of the study To evaluate and compare the value of ‘bolus’ contrast-enhanced CT and contrast-enhanced US in diagnostics of focal hepatic lesions. Tasks of the study 1. To determine rates of diagnostic accuracy of conventional US, US with i/v contrast enhancement and ‘bolus’ contrast-enhanced CT in diagnosis of benign and malingnant FHL. 2. To establish the main and most effective diagnostic criteria of US and CT with i/v contrast enhancement for the assessment of nature of focal hepatic lesions. 3. To compare rates of diagnostic accuracy of US with i/v contrast enhancement and ‘bolus’ contrast-enhanced CT in diagnosis of benign and malingnant FHL. 4. To assess the reliability of radiological diagnostics of hemangioma, comparing the results of US, CT, and MRI.

This work is focused on the description of the dynamic contrast-enhanced CT examination and its contribution in the pneumooncology. It includes a program for creating a two-dimensional model of the scan from the thorax and for the perfuse examination simulation using the time-density curve. Real CT data are simulated more authentic using rigid geometric transformations and noise. The model will be used for the validation of registration algorithms that is used to suppress the spatial deformation generated by patient motions during the long time examination.