Functional CT imaging of prostate cancer.
ABSTRACT The purpose of this paper is to investigate the distribution of blood flow (F), mean capillary transit time (Tc), capillary permeability (PS) and blood volume (vb) in prostate cancer using contrast-enhanced CT. Nine stage T2-T3 prostate cancer patients were enrolled in the study. Following bolus injection of a contrast agent, a time series of CT images of the prostate was acquired. Functional maps showing the distribution of F, Tc, PS and vb within the prostate were generated using a distributed parameter tracer kinetic model, the adiabatic approximation to the tissue homogeneity model. The precision of the maps was assessed using covariance matrix analysis. Finally, maps were compared to the findings of standard clinical investigations. Eight of the functional maps demonstrated regions of increased F, PS and vb, the locations of which were consistent with the results of standard clinical investigations. However, model parameters other than F could only be measured precisely within regions of high F. In conclusion functional CT images of cancer-containing prostate glands demonstrate regions of elevated F, PS and Vb. However, caution should be used when applying a complex tracer kinetic model to the study of prostate cancer since not all parameters can be measured precisely in all areas.
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ABSTRACT: Purpose:To assess the effects of acquisition duration on computed tomographic (CT) perfusion parameter values in neuroendocrine liver metastases and normal liver tissue.Materials and Methods:This retrospective study was institutional review board approved, with waiver of informed consent. CT perfusion studies in 16 patients (median age, 57.5 years; range, 42.0-69.7 years), including six men (median, 54.1 years; range, 42.0-69.7), and 10 women (median, 59.3 years; range 43.6-66.3), with neuroendocrine liver metastases were analyzed by means of distributed parametric modeling to determine tissue blood flow, blood volume, mean transit time, permeability, and hepatic arterial fraction for tumors and normal liver tissue. Analyses were undertaken with acquisition time of 12-590 seconds. Nonparameteric regression analyses were used to evaluate the functional relationships between CT perfusion parameters and acquisition duration. Evidence for time invariance was evaluated for each parameter at multiple time points by inferring the fitted derivative to assess its proximity to zero as a function of acquisition time by using equivalence tests with three levels of confidence (20%, 70%, and 90%).Results:CT perfusion parameter values varied, approaching stable values with increasing acquisition duration. Acquisition duration greater than 160 seconds was required to obtain at least low confidence stability in any of the CT perfusion parameters. At 160 seconds of acquisition, all five CT perfusion parameters stabilized with low confidence in tumor and normal tissues, with the exception of hepatic arterial fraction in tumors. After 220 seconds of acquisition, there was stabilization with moderate confidence for blood flow, blood volume, and hepatic arterial fraction in tumors and normal tissue, and for mean transit time in tumors; however, permeability values did not satisfy the moderate stabilization criteria in both tumors and normal tissue until 360 seconds of acquisition. Blood flow, mean transit time, permeability, and hepatic arterial fraction were significantly different between tumor and normal tissue at 360 seconds (P < .001).Conclusion:CT perfusion parameter values are affected by acquisition duration and approach progressively stable values with increasing acquisition times.© RSNA, 2013Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122708/-/DC1.Radiology 07/2013; · 6.34 Impact Factor
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ABSTRACT: Purpose. Dynamic contrast enhanced (DCE) imaging has gained interest as an imaging modality for assessment of tumor characteristics and response to cancer treatment. However, for DCE-magnetic resonance imaging (MRI) tissue contrast enhancement may vary depending on imaging sequence and temporal resolution. The aim of this study is to compare DCE-MRI to DCE-computed tomography (DCE-CT) as the gold standard. Material and methods. Thirteen patients with advanced cervical cancer were scanned once prior to chemo-radiation and during chemo-radiation with DCE-CT and -MRI in immediate succession. A total of 22 paired DCE-CT and -MRI scans were acquired for comparison. Kinetic modeling using the extended Tofts model was applied to both image series. Furthermore the similarity of the spatial distribution was evaluated using a Γ analysis. The correlation between the two imaging techniques was evaluated using Pearson's correlation and the parameter means were compared using a Student's t-test (p < 0.05). Results. A significant positive correlation between DCE-CT and -MRI was found for all kinetic parameters. The results showing the best correlation with the DCE-CT-derived parameters were obtained using a population-based input function for MRI. The median Pearson's correlations were: volume transfer constant K(trans) (r = 0.9), flux rate constant kep (r = 0.77), extracellular volume fraction ve (r = 0.58) and blood plasma volume fraction vp (r = 0.83). All quantitative parameters were found to be significantly different as estimated by DCE-CT and -MRI. The Γ analysis in normalized maps revealed that 45% of the voxels failed to find a voxel with the corresponding value allowing for an uncertainty of 3 mm in position and 3% in value (Γ3,3). By reducing the criteria, the Γ-failure rates were: Γ3,5 (37% failure), Γ3,10 (26% failure) and at Γ3,15 (19% failure). Conclusion. Good to excellent correlations but significant bias was found between DCE-CT and -MRI. Both the Pearson's correlation and the Γ analysis proved that the spatial information was similar when analyzing the two sets of DCE data using the extended Tofts model. Improvement of input function sampling is needed to improve kinetic quantification using DCE-MRI.Acta oncologica (Stockholm, Sweden) 09/2013; · 2.27 Impact Factor
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ABSTRACT: The aim of our study was to correlate perfusion MDCT parameters and immunohistochemical markers of angiogenesis in prostate cancer. Twenty-two patients scheduled for radical surgical prostatectomy because of biopsy-proven prostate cancer underwent perfusion CT on a 64-MDCT scanner. Eight contiguous 5-mm sections were acquired at 1-second intervals for 45 seconds followed by three additional scans every 10 seconds after the administration of 80 mL of iodinated contrast medium (350 mg I/mL). Blood volume, blood flow, mean transit time, and permeability surface-area product were calculated, dividing each slice into nine square regions. Values obtained were correlated with the mean microvessel density (MVD) and mean vascular area of corresponding areas on histologic macrosections. The mean values of the perfusion parameters detected on all square fields of patients with prostate cancer, benign hyperplasia, chronic prostatitis, and healthy tissue were, respectively, 18.36 ± 6.30, 19.49 ± 8.46, 19.67 ± 11.44, and 20.32 ± 4.53 mL/min/100 g for blood flow; 8.45 ± 2.75, 6.21 ± 4.32, 4.94 ± 2.31, and 5.44 ± 2.67 mL/100 mg for blood volume; 19.19 ± 4.45, 18.74 ± 4.91, 16.24 ± 4.12, and 16.37 ± 4.83 seconds for mean transit time; and 26.34 ± 11.88, 18.67 ± 9.15, 18.08 ± 7.72, and 19.93 ± 7.22 mL/min/100 g for permeability surface-area product. Both blood volume and the permeability surface-area product of cancerous squares showed the highest correlation with mean MVD and mean vascular area (0.618 [p < 0.01] and 0.614 [p < 0.01], respectively) and the highest area under the curve (0.769 and 0.708). Our results show that blood volume and permeability surface-area product measurements obtained with perfusion CT have the highest correlation with immunohistochemical markers of angiogenesis in prostate cancer.American Journal of Roentgenology 11/2012; 199(5):1042-8. · 2.90 Impact Factor