Quantitative CT of lung nodules: Dependence of calibration on patient body size, anatomic region, and calibration nodule size for singleâ and dualâ energy techniques

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134901/1/mp8536.pd

Local Compression in Automated Breast Ultrasound in the Mammographic Geometry

Background, Motivation and Objective: Automated ultrasound scanning (AUS) of the breast has developed more slowly than anticipated. The main limitation, beyond achieving adequate acoustic coupling to the breast, has been excessive shadow artifacts, as reflecting structures at acute angles to the ultrasound beam are not flattened by the transducer as well as in manual scanning. We believe that imaging of the breast in near mammographic compression provides much of the needed flattening. The question under initial study in this effort is, whether in breast AUS under very light mammographic compression, local compression by the transducer might flatten the acutely oriented structures further and reduce the acoustic path length to key structures in the breast. We suspect these improvements will be possible without distorting the breast so dramatically that the lesion registration advantages of scanning the breast in the same system as mammography or digital breast tomosynthesis (DBT) are not realized. Preliminary tests are reported here, as well as design of a system for a more refined human study. Statement of Contribution/Methods: Initial imaging tests were performed in our combined AUS/DBT system. A fiber mesh, loosened slightly in its frame, replaced the standard plastic mammography compression paddle. The transducer, in contact with the mesh and the breast, was translated by motors. The compression force of the linear array transducer on its vertical was manually controlled. Breast phantoms and the breasts of three women were scanned with usual compression by the mesh paddle and then with less global, but added local, compression. Results: Examples of flattened structures were observed more brightly in the locally compressed breasts, and acoustic paths longer than 35 mm were reduced, by _10 mm. In many areas image penetration was 3 cm greater. In one case, image volumes w/wo local compression were spatially aligned by nonlinear image registration software. - - Discussion and Conclusions: Visual indicators of image features expected to provide improved ultrasonic imaging were observed with local compression and lateral movement of tissues appeared acceptable. These results motivated design and construction of an apparatus to make local compression practical and safe. It utilizes joystick control of the vertical compression force during scanning, realized by pneumatic actuators attached to the transducer. The air pressure applied to these actuators is also applied to actuators in the joystick for force feedback to the operator. Two miniature vibrators attached to the joystick provide vibrotactile feedback of the reaction torques computed from the measurements of 6 force sensors on the transducer holder. The fail-safe system design insures no pneumatic compression force application to the breast in case of power loss or emergency shutdown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87269/4/Saitou50.pd

Community‐specific impacts of exotic earthworm invasions on soil carbon dynamics in a sandy temperate forest

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116978/1/ecy201394122827.pd

Evaluation of dual energy quantitative CT for determining the spatial distributions of red marrow and bone for dosimetry in internal emitter radiation therapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135113/1/mp0378.pd

Effect of a Gel Retainment Dam on Automated Ultrasound Coverage in a Dual‐Modality Breast Imaging System

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135299/1/jum20102971075.pd

Breast Mass Characterization Using 3‐Dimensional Automated Ultrasound as an Adjunct to Digital Breast Tomosynthesis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135628/1/jum201332193.pd

Non-contrast thin-section helical CT of urinary tract calculi in children

Background: Non-contrast thin-section helical CT has gained acceptance for the diagnosis of urinary tract calculi in adults, but experience with the technique in children is limited. Purpose: To evaluate the utility of non-contrast thin section helical CT for the diagnosis of urinary tract calculi in children. Materials and methods: Radiology databases at three pediatric institutions were searched to identify all pediatric patients evaluated by "renal stone" protocol CT scans (no oral or intravenous contrast, scans covering the entire urinary tract obtained in helical mode with narrow collimation (< 5 mm)). CT scans were reviewed for the primary finding of urinary tract calculi, for secondary signs of acute urinary tract obstruction and for evidence of alternative diagnoses. Medical records were reviewed to determine clinical presentation and to confirm the eventual diagnosis. Results: One hundred thirty-seven scans of 113 children (mean age: 11.2 years) were studied. Thirty-eight of 94 examinations (40%) performed on 82 children for acute pain and/or hematuria showed ureteral calculi. Alternative diagnoses were suggested by CT on 16 scans (17%). Twenty-eight scans were performed on 10 asymptomatic children with known calculus disease confirming renal stone burden on 21 scans (75%) and persistent ureteral calculi on 6 scans (21%). Upper tract calculi were demonstrated on 10 of 15 scans (67%) performed to evaluate for calculi in patients with known non-calculus genitourinary tract abnormalities. Conclusions: Non-contrast thin section helical CT is a useful method to diagnose urinary tract calculi in children. Radiation dose in this retrospective study may exceed the lowest possible radiation dose for diagnostic accuracy. Further research is needed to optimize CT imaging parameters, while maintaining diagnostic accuracy and minimizing radiation dose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42056/1/247-32-5-326_s00247-001-0655-6.pd