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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.

In Dynamic Contrast Enhanced MRI there are several steps from the initial signal to obtaining the pharmacokinetic parameters for tumor characterization. The aim of this work was to validate the steps in the flow of data focusing on T1-mapping, Contrast Agent (CA)-quantification and the pharmacokinetical (PK) model, using a digital phantom of a head. In the Digital Phantom tissues are assigned necessary values to obtain both a regular and contrast enhanced (using Parker AIF) representation and simulating an SPGR signal. The data analysis was performed in a software called MICE, as well as the Digital Phantom developed at the department of Radiation Sciences at Umeå University. The method of variable flip angles for the T1-mapping was analyzed with respect to SNR and number of flip angles, finding that the median value in each tissue is correct and stable. A "two point" inversion recovery sequence was tested with optimal combination of inversion times for white matter and CSF and obtaining correct T1-values when the inversion times were close to the tissue T1, otherwise with large deviations seen. Three different methods for CA-quantification were analyzed and a large underestimation was found assuming a linearity between signal and CA-concentration mainly for vessels at about 60%, but also for other tissue such as white matter at about 15%, improving when the assumption was removed. Still there was a noticeable underestimation of 30% and 10% and the quantification was improved further, achieving a near perfect agreement with the reference concentration, taking the T2*-effect into account. Applying Kety-model, discarding the vp-term, Ktrans was found to be stable with respect to noise in the tumor rim but ve noticeably underestimated with about 50%. The effect of different bolus arrival time, shifting the AIF required in the PK-model with respect to the CA-concentration, was tested with values up to 5 s, obtaining up to about 5% difference in Ktrans as well as the effect of a vascular transport function obtained by the means of an effective mean transit time up to 5 s and up to about 5% difference in Ktrans.

Effective early detection and monitoring of patient response to cancer therapy is important for improved patient outcomes, avoiding unnecessary procedures and their associated toxicities, as well as the development of new therapies. Dynamic contrast-enhanced magnetic resonance imaging shows promise as a way to evaluate tumour vasculature and assess the efficacy of new anti-angiogenic drugs. However, unavoidable patient motion can decrease the accuracy of subsequent analyses rendering the data unusable. Motion correction algorithms are challenging to develop for contrast-enhanced data since intensity changes due to contrast-enhancement and patient motion must somehow be differentiated from one another. A novel method is presented that employs a motion-informed intensity correction in order to facilitate the registration of contrast enhanced data. The intensity correction simulates the presence or absence of contrast agent in the image volumes to be registered in an attempt to emulate the level of contrast-enhancement present in a single reference image volume.

Effective early detection and monitoring of patient response to cancer therapy is important for improved patient outcomes, avoiding unnecessary procedures and their associated toxicities, as well as the development of new therapies. Dynamic contrast-enhanced magnetic resonance imaging shows promise as a way to evaluate tumour vasculature and assess the efficacy of new anti-angiogenic drugs. However, unavoidable patient motion can decrease the accuracy of subsequent analyses rendering the data unusable. Motion correction algorithms are challenging to develop for contrast-enhanced data since intensity changes due to contrast-enhancement and patient motion must somehow be differentiated from one another. A novel method is presented that employs a motion-informed intensity correction in order to facilitate the registration of contrast enhanced data. The intensity correction simulates the presence or absence of contrast agent in the image volumes to be registered in an attempt to emulate the level of contrast-enhancement present in a single reference image volume.

Thesis (Ph.D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 70-74).

Thesis (M.S.)--Michigan State University. Dept. of Physics, 2008. / Title from PDF t.p. (viewed on Aug. 7, 2009) Includes bibliographical references (p. 55-57). Also issued in print.

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No. of bitstreams: 1 maronezi_mc_me_jabo.pdf: 1008361 bytes, checksum: 61c06a0623c77a91cd63571d5a013b0d (MD5) Previous issue date: 2016-02-12 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O baço é um órgão que desenvolve inúmeras funções importantes no organismo e é um dos principais locais para o desenvolvimento de tumores primários, metastáticos e afecções do sistema hematopoiético, por isso realizar uma avaliação apurada neste órgão é de suma importância, em Medicina veterinária, particularmente em cães devido à importância econômica, afetiva e de similaridade cientifica para o homem. Todavia, a maioria dos métodos utilizados para o diagnóstico conclusivo de enfermidades esplênicas são métodos invasivos, sendo que os nãos invasivos perdem em sensibilidade e especificidade, dificultando que se proceda a um correto diagnóstico. Sendo assim, este estudo prospectivo visou avaliar a aplicabilidade das novas técnicas ultrassonográficas para avaliação esplênica de caninos, utilizando a elastografia ARFI (qualitativa e quantitativa), Doppler e ultrassonografia por contraste com microbolhas, com o intuito de determinar valores ainda não descritos na veterinária, as quais forneçam subsídios suficientes para se obter um diagnóstico conclusivo sobre a condição esplênica, nesta espécie. Os resultados obtidos nos cães saudáveis, por meio da ultrassonografia modo B apresentaram-se normais, sendo que na elastografia qualitativa, as porções esplênicas avaliadas apresentaram-se não deformáveis, com parênquima homogêneo de cor cinza escuro (hard). Na elastografia quantitativa os valores médios da velocidade de cisalhamento foram de 2,32 m/s para a cabeça, 2,16 m/s para o corpo e 2,25 m/s para a cauda do baço, não apresentando diferença estatística (P > 0,05). Ao exame contrastado, foram avaliados animais com erliquiose na fase subclínica, e estes apresentaram ao exame modo-B, esplenomegalia com presença de bordas arredondadas, ecotextura heterogênea e ecogenicidade mista do baço. Ao Doppler, verificou-se valores para os índices vasculares da artéria esplênica: velocidade sistólica: 22,59 ± 8,07 cm/s; velocidade diastólica: 5,25 ± 4,66 cm/s; e índice de resistência: 0,71 ± 0,14. Pela ultrassonografia com contraste observaram-se valores para wash-in de 5,31 ± 0,7s, pico de realce de 18,56 ± 2,90s e wash-out: 94,56 ± 35,21s. A elastografia ARFI é um método recente que pode fornecer dados de base para o baço e permitir a utilização futura desta técnica, na avaliação de cães com doença esplênica. A ultrassonografia convencional do baço de cães com erliquiose associado com a utilização do método Doppler e ultrassonografia contrastada são importantes ferramentas na triagem diagnóstica e podem auxiliar a monitoração e evolução de animais na fase subclínica. / The spleen is an organ develops much important functions in the body and the spleen is one of the main organs prone to the development of primary tumors, metastasis and a broad range of diseases of the hematopoietic system perform assessment of spleen is important. In veterinary medicine, principally in dogs because of economic importance, affective and scientific similarity to humans. However, the most of the methods used for conclusive diagnosis of splenic diseases are invasive methods, noninvasive lose in sensitivity and specificity difficulting proceed to a correct diagnosis. Thus, this study aimed to perform the ultrasound scan of dogs spleen using the elastographic (qualitative and quantitative) Doppler and contrast enhanced ultrasonography. Determining values not described in veterinary, which provide sufficient subsidies to get a conclusive diagnosis of the splenic condition in this species. The results in healthy dogs showed, all splenic segments visualized with the B-mode ultrasonography appeared normal. Different splenic segments examined with qualitative elastography were free of any detectable malformations and the images appeared as homogeneous dark areas. The mean shear velocity values were 2.32 m/s for head, 2.16 m/s for body and 2.25 m/s for tail of the spleen, and they did not vary between the different age groups (P>0.05). In dogs with ehrlichiosis in subclinical phase showed, by B-mode examination, observed splenomegaly with presence of rounded borders and heterogeneous echotexture and mixed echogenicity in spleen. For Doppler found values for vascular indices of the splenic artery: systolic velocity: 22.59 ± 8.07 cm/s; diastolic velocity: 5.25 ± 4.66 cm/s; and resistance index: 0.71 ± 0.14. For contrast enhanced ultrasonography observed values for wash-in: 5.31 ± 0.7s, peak enhancement: 18.56 ± 2.90s and wash-out: 94.56 ± 35.21s. The ARFI elastography is a new method and it may aid in the diagnosis and evaluation of splenic abnormalities routinely assessed in veterinary practice. The conventional ultrasonography of the spleen in dogs with ehrlichiosis associated with hemodynamic evaluation by Doppler and contrast enhanced ultrasonography are important tools for diagnosis trial and could help the monitoring clinical evolution in subclinical phase. / FAPESP: 2013/26197-5

Orientador: Andrigo Barboza De Nardi / Resumo: Os anti-inflamatórios não esteroidais (AINEs) COX-2 seletivos possuem efeito antitumoral mais potente que os AINEs tradicionais e desencadeiam menos efeitos colaterais. Dentre estes efeitos indesejáveis cabe citar alterações gastrintestinais e da perfusão renal, quando administrados por longos períodos para o tratamento auxiliar da dor ou do próprio câncer. Com estes preceitos hipotetizou-se que o carprofeno como AINEs seletivo usado por um período de três meses tem um efeito benéfico em pacientes afetados por carcinoma mamário e que os efeitos sobre o sistema renal vão ser moderados e apenas ligados à alteração da perfusão renal e não à alteração de sua função, assim, objetivou-se avaliar a hemodinâmica renal por meio das técnicas ultrassonográficas Doppler e ultrassonografia contrastada por microbolhas (CEUS), os parâmetros clínicos e laboratoriais rotineiros de função renal e a evolução clínica de cadelas com carcinomas mamário, submetidas à mastectomia, e tratadas ou não com carprofeno. Foi realizado um estudo clínico prospetivo, aleatorizado em 26 cadelas, distribuídas equitativamente em um grupo tratado que recebeu carprofeno 4,4 mg/kg/dia por 90 dias e um grupo controle que não recebia medicação anti-inflamatória. Foram obtidos os parâmetros Dopplerfluxométricos da artéria renal, caraterísticas da perfusão renal pela CEUS, análises celulares e bioquímicas hematológicas e analise clínicas uma vez por mês durante seis meses. Estes dados foram submetidos a comparação entr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Selective COX-2 nonsteroidal anti-inflammatory drugs (NSAIDs) have a more potent antitumoral effect than traditional NSAIDs and trigger fewer side effects. Among these undesirable effects, it is important mentioning gastrointestinal and renal perfusion changes, when administered for long periods in the auxiliary treatment of pain or cancer. With these precepts, it was hypothesized that carprofen as selective NSAIDs used for a period of three months has a beneficial effect on patients affected by breast carcinoma and that the effects on the renal system will be moderate, linked only to renal perfusion alteration and not to function alteration, consequently, the objective was to evaluate renal hemodynamics by Doppler ultrasound and microbubbles contrast enhancement ultrasound (CEUS) techniques, routine clinical and laboratorial parameters of renal function and clinical evolution of bitches with breast carcinomas, submitted to mastectomy, and treated or not with carprofen. A prospective, randomized clinical study was carried out on 26 bitches, equally distributed in a treated group that received carprofen 4.4 mg/kg/day for 90 days and a control group that did not receive NSAIDs medication. Dopplerfluxometric parameters of the renal artery, CEUS renal perfusion characteristics, cell and biochemical hematological analysis and clinical analysis were obtained once a month for six months. These data were subjected to comparison between groups and moments by analysis of variance (ANOV... (Complete abstract click electronic access below) / Mestre

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.