Endovenous Glue-Induced Thrombosis in Nonthermal Glue Closure Therapy for Greater Saphenous Vein Insufficiency: A Single-Center Experience.

A retrospective analysis of endovenous glue-closure therapy (EVGC) performed in 76 greater saphenous veins (GSVs) from February 2016 to December 2017 was conducted to assess the incidence and characteristics of endovenous glue-induced thrombosis (EGIT), a phenomenon unique to nonthermal EVGC for GSV insufficiency. Kabnick and Lawrence classifications for endovenous heat-induced thrombosis were adopted. Seven instances of EGIT were detected among 54 patients (13%), with median/mode Kabnick and Lawrence classifications of 2/2 and 4/5, respectively. EGIT resolved with observation within an average of 5.2 wk after detection (range, 2-8 wk) without deep vein thrombosis or pulmonary embolism. EGIT was associated with significantly greater mean age (+7.75 y; P = .0308).

Scintillation Yield Estimates of Colloidal Cerium-Doped LaF3 Nanoparticles and Potential for "Deep PDT".

A hybrid of radiotherapy and photodynamic therapy (PDT) has been proposed in previously reported studies. This approach utilizes scintillating nanoparticles to transfer energy to attached photosensitizers, thus generating singlet oxygen for local killing of malignant cells. Its effectiveness strongly depends upon the scintillation yield of the nanoparticles. Using a liquid scintillator as a reference standard, we estimated the scintillation yield of Ce0.1La0.9F3/LaF3 core/shell nanoparticles at 28.9 mg/ml in water to be 350 photons/MeV under orthovoltage X-ray irradiation. The subsequent singlet oxygen production for a 60 Gy cumulative dose to cells was estimated to be four orders of magnitude lower than the "Niedre killing dose," used as a target value for effective cell killing. Without significant improvements in the radioluminescence properties of the nanoparticles, this approach to "deep PDT" is likely to be ineffective. Additional considerations and alternatives to singlet oxygen are discussed.

Adjunctive anticoagulation during peripheral vascular intervention.

Endovascular techniques for the treatment of peripheral arterial disease are becoming an increasingly common alternative to open surgery, yet the degree of anticoagulation and choice of anticoagulant to optimize outcomes in these procedures remain uncertain. To date, few randomized trials have directly compared different anticoagulants for use during peripheral vascular interventions. It is also unclear if the approach to anticoagulation should be individualized to each vascular bed or if common principles are shared among them. This has led practitioners across different specialties to use a variety of different methods for anticoagulation, with most extrapolated from techniques used in percutaneous coronary interventions. In this review, we analyze the current literature for anticoagulation used during peripheral vascular intervention of the lower extremity, renal, carotid, and aortic arteries, with special consideration to the choice of anticoagulant used to maximize safe and effective procedural outcomes.

High-dose spatially fractionated GRID radiation therapy (SFGRT): a comparison of treatment outcomes with Cerrobend vs. MLC SFGRT.

PURPOSE: Spatially fractionated GRID radiotherapy (SFGRT) using a customized Cerrobend block has been used to improve response rates in patients with bulky tumors. The clinical efficacy of our own multileaf collimator (MLC) technique is unknown. We undertook a retrospective analysis to compare clinical response rates attained using these two techniques. METHODS AND MATERIALS: Seventy-nine patients with bulky tumors (median diameter, 7.6 cm; range, 4-30 cm) treated with SFGRT were reviewed. Between 2003 and late 2005, the Cerrobend block technique (n = 39) was used. Between late 2005 and 2008, SFGRT was delivered using MLC-shaped fields (n = 40). Dose was prescribed to dmax (depth of maximum dose) and was typically 15 Gy. Eighty percent of patients in both groups received external beam radiotherapy in addition to SFGRT. The two-sided Fisher-Freeman-Halton test was used to compare pain and mass effect response rates between the two groups. RESULTS: Sixty-one patients (77%) were treated for palliative intent and 18 (23%) for curative intent. The majority of patients had either lung or head-and-neck primaries in both groups; the most frequent site of SFGRT application was the neck. The majority of patients complained of either pain (65%) or mass effect (58%) at intake. Overall response rates for pain and mass response were no different between the Cerrobend and MLC groups: pain, 75% and 74%, respectively (p = 0.50), and mass effect, 67% and 73%, respectively (p = 0.85). The majority of toxicities were Grade 1 or 2, and only 3 patients had late Grade 3-4 toxicities. CONCLUSIONS: MLC-based and Cerrobend-based SFGRT have comparable and encouraging response rates when used either in the palliative or curative setting. MLC-based SGFRT should allow clinics to more easily adopt this novel treatment approach for the treatment of bulky tumors.

Frequency and importance of small amount of isolated pelvic free fluid detected with multidetector CT in male patients with blunt trauma.

PURPOSE: To retrospectively determine the frequency and importance of a small amount of isolated pelvic free fluid seen at multidetector computed tomography (CT) in male patients who have blunt trauma without an identifiable cause. MATERIALS AND METHODS: Institutional review board approval was obtained, and the requirement for informed consent was waived for this HIPAA-compliant study. One thousand male patients with blunt trauma who underwent abdominopelvic CT at a level 1 trauma center between January 2004 and June 2006 were entered into this study. The CT images of the 1000 patients were reviewed independently by two abdominal radiologists. CT scan assessment included evaluation for presence or absence of pelvic free fluid, any traumatic or nontraumatic cause of the free fluid, pelvic free fluid attenuation and volume measurements, and determination of the location of pelvic free fluid. Interobserver agreement was determined with kappa statistics, and the Student t test was used to assess differences in the mean volume and mean attenuation of the pelvic free fluid in the patients with and those without injury. RESULTS: Pelvic free fluid was identified in 10.2% (102 of 1000) of patients. A small amount of isolated pelvic free fluid without any identifiable cause was identified in 4.8% (48 of 1000) of patients by reader 1 and in 5.0% (50 of 1000) of patients by reader 2 (kappa value, 0.76) and was located at or below the level of the third sacral vertebral body in all 49 patients with isolated pelvic free fluid. The mean volume and mean attenuation of the small amount of isolated pelvic free fluid were 2.3 mL +/- 1.5 (standard deviation) and 8.1 HU +/- 3.9, respectively. None of the patients in this group had an undiagnosed bowel and/or mesenteric injury. CONCLUSION: In male patients with blunt trauma, a small amount of isolated pelvic free fluid with attenuation equal to that of simple fluid and located in the deep region of the pelvis likely is not a sign of bowel and/or mesenteric injury.

Unified wavelet and Gaussian filtering for segmentation of CT images; application in segmentation of bone in pelvic CT images.

BACKGROUND: The analysis of pelvic CT scans is a crucial step for detecting and assessing the severity of Traumatic Pelvic Injuries. Automating the processing of pelvic CT scans could impact decision accuracy, decrease the time for decision making, and reduce health care cost. This paper discusses a method to automate the segmentation of bone from pelvic CT images. Accurate segmentation of bone is very important for developing an automated assisted-decision support system for Traumatic Pelvic Injury diagnosis and treatment. METHODS: The automated method for pelvic CT bone segmentation is a hierarchical approach that combines filtering and histogram equalization, for image enhancement, wavelet analysis and automated seeded region growing. Initial results of segmentation are used to identify the region where bone is present and to target histogram equalization towards the specific area. Speckle Reducing Anisotropic Didffusion (SRAD) filter is applied to accentuate the desired features in the region. Automated seeded region growing is performed to refine the initial bone segmentation results. RESULTS: The proposed method automatically processes pelvic CT images and produces accurate segmentation. Bone connectivity is achieved and the contours and sizes of bones are true to the actual contour and size displayed in the original image. Results are promising and show great potential for fracture detection and assessing hemorrhage presence and severity. CONCLUSION: Preliminary experimental results of the automated method show accurate bone segmentation. The novelty of the method lies in the unique hierarchical combination of image enhancement and segmentation methods that aims at maximizing the advantages of the combined algorithms. The proposed method has the following advantages: it produces accurate bone segmentation with maintaining bone contour and size true to the original image and is suitable for automated bone segmentation from pelvic CT images.

Effects of tumor motion in GRID therapy.

Clinical and biological evidence suggest that the success of GRID therapy in debulking large tumors depends on the high peak-to-valley contrast in the dose distribution. In this study, we show that the peaks and valleys can be significantly blurred out by respiration-induced tumor motion, possibly affecting the clinical outcome. Using a kernel-based Monte Carlo dose engine that incorporates phantom motion, we calculate the dose distributions for a GRID with hexagonally arranged holes. The holes have a diameter of 1.3 cm and a minimum center-to-center separation of 2.1 cm (projected at the isocenter). The phantom moves either in the u parallel direction, which is parallel to a line joining any two nearest neighbors, or in the perpendicular u perpendicular direction. The displacement-time waveform is modeled with a cosn function, with n assigned 1 for symmetric motion, or 6 to simulate a large inhale-exhale asymmetry. Dose calculations are performed on a water phantom for a 6 MV x-ray beam. Near dmax, the static valley dose is 0.12D0, where D0 is the peak static dose. For motion in the u parallel direction, the peak and valley doses vary periodically with the amplitude of motion a and the transverse dose profiles are maximally flat near a=0.8 cm and a=1.9 cm. For the cos waveform, the minimum peak dose (Dpmin) is 0.67D0 and the maximum valley dose (Dvmax) is 0.60D0. Less dose blurring is seen with the cos6 waveform, with Dpmin=0.77D0 and Dvmax=0.45D0. For motion in the u perpendicular direction, the maximum flattening of dose profiles occurs at a=1.5 cm. GRIDs with smaller hole separations produce similar blurring at proportionally smaller amplitudes. The reported clinical response data from GRID therapy seem to indicate that mobile tumors, such as those in the thorax and abdomen, respond worse to GRID treatments than stationary tumors, such as those in the head and neck. To establish a stronger correlation between clinical response and tumor motion, and possibly improve the clinical response rates, it is recommended that prospective GRID therapy trials be conducted with motion compensation strategies, such as respiratory gating.

On the sources of drift in a turbine-based spirometer.

A systematic study on the sources of drift in a turbine-based spirometer (VMM-400) is presented. The study utilized an air-tight cylinder to pump air through the spirometer in a precise and programmable manner. Factors contributing to the drift were isolated and quantified. The drift due to imbalance in the electronics and the mechanical blade increased from 1% per breathing cycle to as much as 10% when the flow rate decreased from 0.24 to 0.08 l s(-1). A temperature difference of 16 degrees between the ambient and the air in the cylinder contributed about 3.5%. Most significantly, a difference in the breathing between inhalation and exhalation could produce a drift of 40% per breathing cycle, or even higher, depending on the extent of the breathing asymmetry. The origin of this drift was found to be rooted in the differential response of the spirometer to the different flow rate. Some ideas and suggestions for a correction strategy are provided for future work. The present work provides an important first step for eventual utilization of a spirometer as a stand-alone breathing surrogate for gating or tracking radiation therapy.

Feasibility of delivering grid therapy using a multileaf collimator.

The feasibility of using a multileaf collimator (MLC) for grid therapy is demonstrated in this study. Grids with the projected field openings of 10 mm x 10 mm and 5 mm x 5 mm were created using multiple MLC-shaped fields. The deposited doses were measured with films at different depths in a solid water phantom and compared to those of Cerrobend grid collimators of similar hole sizes and hole separations. At the depth of maximum dose (dmax), the valley-to-peak dose ratios of the MLC grids were found to be about 11% and 19% for the respective 10 mm x 10 mm and 5 mm X 5 mm grid openings, and those of the corresponding grid blocks were about 15% and 20%. To quantify the dose contributed by transmission in the blocked areas due to the limited leaf thickness, Monte Carlo simulations (based on convolution/superposition method) were performed to calculate the doses in the solid water phantom using an ideal MLC with no leakage and perfect divergence in both the leaf end and side. About 7% reduction in the valley-to-peak dose ratio was found for both grid sizes at dmax. The results clearly showed that MLCs can be used to provide grid treatments with at least as good dosimetric properties as those of the Cerrobend grid blocks, though the former would in general require a longer delivery time.