Three-dimensional isotropic wavelets for post-acquisitional extraction of latent images of atherosclerotic plaque components from micro-computed tomography of human coronary arteries

RATIONALE AND OBJECTIVES: The capability of wavelet transforms to separate signals into frequency bands is the basis for its use in image compression and storage, data management and transmission, and, recently, extraction of latent images of tissue components from noisy medical images. Analysis of temporal variations of radiofrequency backscatter of intravascular ultrasound with one-dimensional wavelets can detect lipid-laden plaque in coronary arteries with a sensitivity and specificity of >80%. In this study we evaluate the capability of a novel, 3-dimensional isotropic wavelet analysis to perform high resolution, non-directionally biased, statistically reliable, non-invasive discrimination between components of human coronary atherosclerotic plaques in micro-CT. MATERIALS AND METHODS: Coronary artery segments (5-15 mm) were excised at necropsy from 18 individuals with advanced coronary atherosclerosis. Specimens were imaged using a GE Locus SP ex vivo micro-CT scanner and processed for histological correlation (833 sections). The isotropic wavelet constructs were applied to the entire volume of CT data of each arterial segment to distinguish tissue textures of varying scales and intensities. Voxels were classified and plaque characterization achieved by comparing the relative magnitudes of these wavelet constituents to that of several reference plaque tissue components. RESULTS: Processing of micro-CT images via these isotropic wavelet algorithms permitted 3-D, color-coded, high resolution, digital discrimination between lumen, calcific deposits, lipid-rich deposits, and fibromuscular tissue providing detail not possible with conventional thresholding based on Hounsfield intensity units. Using the isotropic wavelets (with histology as the gold standard), lipid-rich pools approaching the size of the filter for the isotropic wavelet algorithm (0.25 mm [250 microns] in length) were identified with 81% sensitivity and 86% specificity. Calcific deposits, fibromuscular tissue, and lumen equal to or larger than the wavelet filter size were detected without error (100% sensitivity and specificity). CONCLUSION: Isotropic wavelet analysis permits high resolution, multi-dimensional identification of coronary atherosclerotic plaque components in micro-CT with sensitivity and specificity similar to that achieved with data obtained invasively (from IVUS in vivo) using one-dimensional wavelets. Further studies are necessary to test the applicability of this technology to clinical, multi-detector scanners.     

The impact of acute urinary morbidity on late urinary function after permanent prostate brachytherapy

PURPOSE: Acute prostate brachytherapy-related morbidity is dominated by urinary symptomatology. In this study, we evaluated the effect of severe early brachytherapy-related urinary morbidity on late urinary function. METHODS AND MATERIALS: From January 1998 to September 2003, 1029 patients were implanted for clinical stage T1b-T3a (2002 American Joint Committee on Cancer [AJCC] criteria) prostate cancer. Five hundred sixteen (50.1%) received supplemental external beam radiation therapy and 440 (42.8%) received androgen deprivation therapy. Severe acute urinary morbidity (SAUM) was defined as a dysuria frequency score of at least 4 (of 5), a dysuria severity score of at least 8 (of 10), an internation prostate symptom score (IPSS) elevated to at least 30 or 15 above preimplant value for 4 weeks, and/or requirement of a urinary catheter for at least 5 days. Dysuria severity and frequency resolution were defined as a return to within one point of baseline. IPSS resolution was defined as a return to within two points of baseline. RESULTS: Of the 1029 patients, 175 met at least one of the criteria for inclusion. Dysuria frequency resolved in 5.0 vs. 1.3 weeks and dysuria severity in 5.7 vs. 1.4 weeks, for patients with and without SAUM. The mean time for IPSS resolution was 13.8 vs. 6.6 weeks, for patients with and without SAUM. The incidence of transurethral resection (2.3% [4/173] vs. 1.5% [13/841]) and bulbomembranous urethral strictures (2.2% [4/175] vs. 1.8% [15/854]) were comparable among patients with and without SAUM. CONCLUSIONS: Patients experiencing brachytherapy-related SAUM have long-term urinary function and complications comparable to patients who did not develop SAUM.     

Recombinant activated factor VII increases survival time in a model of incompressible arterial hemorrhage in the anesthetized pig

BACKGROUND: Hemorrhage is the leading cause of death in battlefield casualties and the second leading cause of death after civilian trauma. Evacuation time for military casualties to surgical care can be prolonged and improved hemostasis could greatly reduce mortality. There are several anecdotal reports that recombinant activated factor VII (rFVIIa) may arrest uncontrolled bleeding after trauma. However, the majority of prospective randomized controlled trials show little benefit in survival. The aim of this study was to determine whether rFVIIa could increase survival time within a clinically relevant time scale for military practice and reduce the volume of blood loss in a model of incompressible arterial hemorrhage. A secondary aim was to determine the effects of hypotensive versus normotensive resuscitation on the effectiveness of rFVIIa. METHODS: Terminally anaesthetized Large White pigs were randomly allocated to one of four treatment groups. All animals received a controlled hemorrhage of 40% of the total estimated blood volume. They were given either rFVIIa (180 microg/kg) or placebo (saline 0.3 mL/kg) intravenously and a 4 to 5 mm longitudinal aortotomy created in the infra renal aorta before resuscitation commenced with 0.9% saline to one of two target systolic arterial blood pressures (SBPs): 110 mm Hg (normotensive) or 80 mm Hg (hypotensive). Group sizes were as follows: placebo/normotensive (6), placebo/hypotensive (7), rFVIIa/normotensive (7), and rFVIIa/hypotensive (7). Survival was monitored for a maximum of 6 hours after the onset of resuscitation. RESULTS: rFVIIa was associated with a significantly prolonged survival time in animals managed hypotensively (214 [79-349] vs. 35 [19-52] minutes mean [95% confidence interval] rFVIIa vs. placebo, p = 0.03 Peto log rank test). There was no significant difference in survival time between those given rFVIIa and placebo in groups managed normotensively (128 [6-249] vs. 40 [15-66] minutes respectively, p = 0.27). Both rFVIIa and hypotensive management were associated with reduced uncontrolled hemorrhage volumes. There was no evidence of inappropriate intravascular thrombi or microthrombi associated with the use of rFVIIa. CONCLUSIONS: rFVIIa, combined with hypotensive resuscitation, can increase survival time and reduce hemorrhage in a model of arterial hemorrhage. The increase in survival time is clinically relevant for military evacuation of battlefield casualties to surgical care.