VESCL: an open source 2D vessel contouring library.

PURPOSE: VESCL (pronounced 'vessel') is a novel vessel contouring library for computer-assisted 2D vessel contouring and segmentation. VESCL facilitates manual vessel segmentation in 2D medical images to generate gold-standard datasets for training, testing, and validating automatic vessel segmentation. METHODS: VESCL is an open-source C++ library designed for easy integration into medical image processing systems. VESCL provides an intuitive interface for drawing variable-width parametric curves along vessels in 2D images. It includes highly optimized localized filtering to automatically fit drawn curves to the nearest vessel centerline and automatically determine the varying vessel width along each curve. To support a variety of segmentation paradigms, VESCL can export multiple segmentation representations including binary segmentations, occupancy maps, and distance fields. RESULTS: VESCL provides sub-pixel resolution for vessel centerlines and vessel widths. It is optimized to segment small vessels with single- or sub-pixel widths that are visible to the human eye but hard to segment automatically via conventional filters. When tested on neurovascular digital subtraction angiography (DSA), VESCL's intuitive hand-drawn input with automatic curve fitting increased the speed of fully manual segmentation by 22× over conventional methods and by 3× over the best publicly available computer-assisted manual segmentation method. Accuracy was shown to be within the range of inter-operator variability of gold standard manually segmented data from a publicly available dataset of neurovascular DSA images as measured using Dice scores. Preliminary tests showed similar improvements for segmenting DSA of coronary arteries and RGB images of retinal arteries. CONCLUSION: VESCL is an open-source C++ library for contouring vessels in 2D images which can be used to reduce the tedious, labor-intensive process of manually generating gold-standard segmentations for training, testing, and comparing automatic segmentation methods.

Intravascular contrast media: effect of dose on renal function.

Effect of contrast material dose on clinically evident change in renal function was studied prospectively in 200 examinations requiring intravenous or intraarterial administration of contrast material. All patients were adequately hydrated. Blood urea nitrogen and serum creatinine were measured before and after the procedure. Ionic and nonionic contrast agents were used. Total dose of contrast material ranged from 30 to 530 mL (mean, 237 mL). There was no tendency to give smaller doses to patients with preexisting renal impairment and no relationship between total dose and patient age. No consistent clinical effect on renal function was demonstrated with increasing dose, regardless of whether ionic or nonionic agents were used. In adequately hydrated low-risk patients with predominantly normal initial renal function and within the dose range studied, there does not appear to be any consistent clinical change in renal function with increasing contrast material dose.

The Sidaway case.

KIE: A brief comment is offered on the British House of Lords' decision in Sidaway v. Bethlem Royal Hospital, concerned with the surgeon's duty to warn a patient of the possible risks involved when obtaining informed consent to a proposed operation. A majority of the Lords of Appeal rejected the full doctrine of informed consent as accepted by some states in the U.S. and by the Canadian Supreme Court, but there was disagreement among them on the applicable standard of disclosure. Wells holds that legislation is needed to clarify the issue.^ieng

Warnock report on human fertilisation and embryology.

KIE: Four areas of potential legal difficulty generated by Britain's Warnock report are identified. Supervision of the operations that would be authorized by a licensing authority is problematic because of the lack of qualified individuals and their questionable ability to oversee specific research. Since surrogate arrangements would be considered illegal contracts unenforceable in the courts, a couple would be unable to sue a carrying mother for breach of contract if she refused to hand over the child. The author questions who would be considered the mother if the commissioning woman had supplied the egg. The assumption that all research on embryos is experimental is questioned. Whether mere observation can be classed as research may have some bearing on the 14-day limit applied to such research. The effect on a person of being informed at majority of his or her origin through IVF or AID, as recommended, has yet to be determined.^ieng

The surgeon's duty to warn of risks.

KIE: The British and American approaches to the question of a surgeon's legal duty to warn of risks in surgical procedures are briefly outlined and commented upon, with the decisions in Sidaway v. Bethlem Royal Hospital and Canterbury v. Spence being cited as examples. Most British courts have viewed the issue as one involving the law of negligence, rejecting the American interpretation of informed consent based on the law of trespass to the person. Wells favors the American concept of informed consent over the British concept of a physician's duty to take care, but draws attention to problems with both approaches.^ieng