Minimal invasive endoscopic treatment for upper urinary tract urothelial carcinoma (UUT-UC) is advocated in patients with low-risk disease and limited tumor volume. Diagnostic ureterorenoscopy combined with biopsy is the diagnostic standard. This study aims to evaluate two alternative diagnostic techniques for UUT-UC: optical coherence tomography (OCT) and endoluminal ultrasound (ELUS). Following nephroureterectomy, OCT, ELUS, and computed tomography (CT) were performed of the complete nephroureterectomy specimen. Visualization software (AMIRA®) was used for reconstruction and coregistration of CT, OCT, and ELUS. Finally, CT was used to obtain exact probe localization. Coregistered OCT and ELUS datasets were compared with histology. Coregistration with three-dimensional CT makes exact data matching possible in this ex-vivo setting to compare histology with OCT and ELUS. In OCT images of normal-appearing renal pelvis and ureter, urothelium, lamina propria, and muscularis were visible. With ELUS, all anatomical layers of the ureter could be distinguished, besides the urothelial layer. ELUS identified suspect lesions, although exact staging and differentiation between noninvasive and invasive lesions were not possible. OCT provides high-resolution imaging of normal ureter and ureter lesions. ELUS, however, is of limited value as it cannot differentiate between noninvasive and invasive tumors.
Rational and Objective: In CT systems, blurring is the main limiting factor for imaging in-stent restenosis. The aim of
this study is to systematically analyze the effect of blurring related biases on the quantitative assessment of in-stent
restenosis and to evaluate potential correction methods. Methods: 3D analytical models of a blurred, stented vessel are
presented to quantify blurring related artifacts in the stent diameter measurement. Two correction methods are presented
for an improved stent diameter measurement. We also examine the suitability of deconvolution techniques for correcting
blurring artifacts. Results: Blurring results in a shift of the maximum of the signal intensity towards the center position
of the stent, resulting in an underestimation of the stent diameter. This shift can be expressed as a function of the stent
radius and width of the point spread function. The correction for this phenomenon reduces the error with 75 percent.
Deconvolution reduces the blurring artifacts but introduces a ringing artifact. Conclusion: The analytical vessel models
are well suited to study the influence of various parameters on blurring-induced artifacts. The blurring-related
underestimation of the stent diameter can significantly be reduced using the presented corrections. Care should be taken
into choosing suitable deconvolution filters since they may introduce new artifacts.