Antioxidants Taken Orally prior to Diagnostic Radiation Exposure Can Prevent DNA Injury.

PURPOSE: To evaluate efficacy of oral antioxidant treatment given to patients before radiologic procedures in reducing x-ray-induced DNA damage. MATERIALS AND METHODS: In a single-center prospective controlled trial, antioxidant treatment with 2 g ascorbate, 1.2 g N-acetylcysteine, 600 mg lipoic acid, and 30 mg beta carotene was given to 5 consecutive participants before undergoing clinically indicated technetium-99m methylene diphosphonate (99mTc MDP) bone scans for cancer staging. These participants were compared with 5 participants without antioxidant treatment. DNA damage was visualized in peripheral blood mononuclear cells (PBMCs) before and after bone scans using three-dimensional microscopy and fluorescently labeled gamma-H2AX protein. Wilcoxon rank sum test was used to determine whether there was a statistically significant difference in the radiation received between the control and antioxidant groups, the number of foci/cell before and after bone scan within groups, and foci/cell after bone scan between groups. RESULTS: There was a significantly higher number of gamma-H2AX foci/cell after ionization radiation in the control group compared with the antioxidant group (P = .009). There was no statistically significant difference in number of gamma-H2AX foci/cell before or after exposure in the antioxidant group; the number of gamma-H2AX foci/cell was statistically significantly higher (P = .009) in the control group after exposure to 99mTc MDP. CONCLUSIONS: In patients undergoing 99mTc MDP bone scans, treatment with oral antioxidants before scanning significantly prevented DNA damage in PBMCs. Antioxidants may provide an effective means to protect patients and health care professionals from radiation-induced DNA damage during imaging studies.

Perfusion in peripheral musculoskeletal structures from dynamic volumetric computed tomography using an en bloc approach.

Volumetric computed tomography offers improved potential to perform perfusion analysis in peripheral musculoskeletal structures. Despite poor baseline tissue enhancement and artifacts from adjacent bone, reproducible perfusion estimates were attained using a volumetric en bloc technique in the plantar muscle compartment, Achilles tendon, and subcalcaneal adipose tissue of 16 feet in healthy male subjects. Inadequate enhancement prevented perfusion estimates in the second metatarsal head of all cases. Perfusion calculations succeeded in the calcaneus in 6 of the 16 examined feet.

Intra-vascular blood velocity and volumetric flow rate calculated from dynamic 4D CT angiography using a time of flight technique.

We examine a time of flight (TOF) approach for the analysis of contrast enhanced 4D volumetric CT angiography scans to derive and display blood velocity in arteries. Software was written to divide blood vessels into a series of cross sections and to track contrast bolus TOF along the central vessel axis, which was defined by a user, from 4D CT source data. Time density curves at each vessel cross section were fit with quadratic, Gaussian, and gamma variate functions to determine bolus time to peak (TTP). A straight line was used to plot TTP versus vessel path length for all three functions and the slope used to calculate intraluminal velocity. Software was validated in a simulated square channel and non-pulsatile flow phantom prior to the calculation of blood velocity in the major cerebral arteries of 8 normal patients. The TOF algorithm correctly calculates intra-luminal fluid velocity in eight flow conditions of the CT flow phantom where quadratic functions were used. Across all conditions, in phantoms and in vivo, the success of calculations depended strongly on having a sufficiently long path length to make measurements and avoiding venous contamination. Total blood flow into the brain was approximately 17 % of a normal 5 L cardiac output. The technique was explored in vivo in a patient with subclavian steal syndrome, in the pulmonary arteries and in the iliac artery from clinical 4D CT source data. Intravascular blood velocity and flow may be calculated from 4D CT angiography using a TOF approach.

An en bloc approach to CT perfusion for the evaluation of limb ischemia.

We examine volumetric CT perfusion in soft tissues of the entire foot with an en bloc technique to provide a meaningful measure of differentiation between mild and major vascular impairment. With Institutional Review Board approval, 22 healthy male subjects between the ages of 21 and 50 (mean 37) were enrolled. Volumetric computed tomography using an en bloc technique was conducted on 14 subjects for validation while unilateral vascular obstruction was simulated in the calves of the remaining 8 subjects. Perfusion estimates were made using in-house software and differences in perfusion estimates between feet were evaluated with Student's t-test at 95% confidence. Subjects with simulated major vascular obstruction (calf blood pressure cuff inflated to 200 mmHg) showed significantly higher ratios of perfusion estimates between the unobstructed and obstructed foot compared to subjects with simulated mild vascular obstruction (cuff inflated to 120 mmHg), mean 4.6, SD 2.6 vs. mean 1.3, SD 0.2; P = 0.05. CT perfusion using an en bloc technique shows promise for the future evaluation of patients with critical limb ischemia and particularly for re-characterization post medical, surgical or endovascular intervention.