Full wave 3D inverse scattering transmission ultrasound tomography in the presence of high contrast.

We present here a quantitative ultrasound tomographic method yielding a sub-mm resolution, quantitative 3D representation of tissue characteristics in the presence of high contrast media. This result is a generalization of previous work where high impedance contrast was not present and may provide a clinically and laboratory relevant, relatively inexpensive, high resolution imaging method for imaging in the presence of bone. This allows tumor, muscle, tendon, ligament or cartilage disease monitoring for therapy and general laboratory or clinical settings. The method has proven useful in breast imaging and is generalized here to high-resolution quantitative imaging in the presence of bone. The laboratory data are acquired in ~ 12 min and the reconstruction in ~ 24 min-approximately 200 times faster than previously reported simulations in the literature. Such fast reconstructions with real data require careful calibration, adequate data redundancy from a 2D array of 2048 elements and a paraxial approximation. The imaging results show that tissue surrounding the high impedance region is artifact free and has correct speed of sound at sub-mm resolution.

High-speed, low-cost, pulsed-laser-diode-based second-generation desktop photoacoustic tomography system.

Bulky, expensive Nd:YAG lasers are used in conventional photoacoustic tomography (PAT) systems, making them difficult to translate into clinics. Moreover, real-time imaging is not feasible when a single-element ultrasound transducer is used with these low-pulse-repetition-rate lasers (10-100 Hz). Low-cost pulsed laser diodes (PLDs) can be used instead for photoacoustic imaging due to their high-pulse-repetition rates and compact size. Together with acoustic-reflector-based multiple single-element ultrasound transducers, a portable desktop PAT system was developed. This second-generation PLD-based PAT achieved 0.5 s cross-sectional imaging time with high spatial resolution of ∼165 µm and an imaging depth of 3 cm. The performance of this system was characterized using phantom and in vivo studies. Dynamic in vivo imaging was also demonstrated by monitoring the fast uptake and clearance of indocyanine green in small animal (rat) brain vasculature.

Using Medical Claims for Policy Effectiveness Surveillance: Reimbursement and Utilization of Abdomen/Pelvis Computed Tomography Scans.

OBJECTIVE: To quantify changes in private insurance payments for and utilization of abdominal/pelvic computed tomography scans (CTs) after 2011 changes in CPT coding and Medicare reimbursement rates, which were designed to reduce costs stemming from misvalued procedures. DATA SOURCES: TruvenHealth Analytics MarketScan Commercial Claims and Encounters database. STUDY DESIGN: We used difference-in-differences models to compare combined CTs of the abdomen/pelvis to CTs of the abdomen or pelvis only. Our main outcomes were inflation-adjusted log payments per procedure, daily utilization rates, and total annual payments. DATA EXTRACTION METHODS: Claims data were extracted for all abdominal/pelvic CTs performed in 2009-2011 within noncapitated, employer-sponsored private plans. PRINCIPAL FINDINGS: Adjusted payments per combined CTs of the abdomen/pelvis dropped by 23.8 percent (p < .0001), and their adjusted daily utilization rate accelerated by 0.36 percent (p = .034) per month after January 2011. Utilization rate of abdominal-only or pelvic-only CTs dropped by 5.0 percent (p < .0001). Total annual payments for combined CTs of the abdomen/pelvis decreased in 2011 despite the increased utilization. CONCLUSIONS: Private insurance payments for combined CTs of the abdomen/pelvis declined and utilization accelerated significantly after 2011 policy changes. While growth in total annual payments was contained in 2011, it may not be sustained if 2011 utilization trends persist.

Inherent limitations of hydraulic tomography.

We offer a cautionary note in response to an increasing level of enthusiasm regarding high-resolution aquifer characterization with hydraulic tomography. We use synthetic examples based on two recent field experiments to demonstrate that a high degree of nonuniqueness remains in estimates of hydraulic parameter fields even when those estimates are based on simultaneous analysis of a number of carefully controlled hydraulic tests. We must, therefore, be careful not to oversell the technique to the community of practicing hydrogeologists, promising a degree of accuracy and resolution that, in many settings, will remain unattainable, regardless of the amount of effort invested in the field investigation. No practically feasible amount of hydraulic tomography data will ever remove the need to regularize or bias the inverse problem in some fashion in order to obtain a unique solution. Thus, along with improving the resolution of hydraulic tomography techniques, we must also strive to couple those techniques with procedures for experimental design and uncertainty assessment and with other more cost-effective field methods, such as geophysical surveying and, in unconsolidated formations, direct-push profiling, in order to develop methods for subsurface characterization with the resolution and accuracy needed for practical field applications.

Cost effectiveness of alternative imaging strategies for the diagnosis of small-bowel Crohn's disease.

BACKGROUND & AIMS: The cost effectiveness of alternative approaches to the diagnosis of small-bowel Crohn's disease is unknown. This study evaluates whether computed tomographic enterography (CTE) is a cost-effective alternative to small-bowel follow-through (SBFT) and whether capsule endoscopy is a cost-effective third test in patients in whom a high suspicion of disease remains after 2 previous negative tests. METHODS: A decision-analytic model was developed to compare the lifetime costs and benefits of each diagnostic strategy. Patients were considered with low (20%) and high (75%) pretest probability of small-bowel Crohn's disease. Effectiveness was measured in quality-adjusted life-years (QALYs) gained. Parameter assumptions were tested with sensitivity analyses. RESULTS: With a moderate to high pretest probability of small-bowel Crohn's disease, and a higher likelihood of isolated jejunal disease, follow-up evaluation with CTE has an incremental cost-effectiveness ratio of less than $54,000/QALY-gained compared with SBFT. The addition of capsule endoscopy after ileocolonoscopy and negative CTE or SBFT costs greater than $500,000 per QALY-gained in all scenarios. Results were not sensitive to costs of tests or complications but were sensitive to test accuracies. CONCLUSIONS: The cost effectiveness of strategies depends critically on the pretest probability of Crohn's disease and if the terminal ileum is examined at ileocolonoscopy. CTE is a cost-effective alternative to SBFT in patients with moderate to high suspicion of small-bowel Crohn's disease. The addition of capsule endoscopy as a third test is not a cost-effective third test, even in patients with high pretest probability of disease.

Imaging of cerebral metastases.

MR imaging with intravenous gadolinium has greatly enhanced our ability to detect and delineate intracranial metastases as well as to differentiate them from other disease processes. Techniques such as magnetization transfer and triple dose gadolinium imaging have further improved lesion detection. Consideration of these radiologic techniques, including the issues and controversies of screening and cost effectiveness, suggests a reasonable approach to imaging patients with possible intracranial metastases. Newer modalities such as echo planar imaging, spectroscopy, PET, and SPECT, may in the future, prove to be very useful in the evaluation of patients with intracranial metastases. Proper imaging is also critical to appropriate diagnosis and management of meningeal metastases, calvarial metastases, and paraneoplastic disease.