Nicholas J. Hangiandreou

Magnetic resonance-guided focused ultrasound of uterine leiomyomas: review of a 12-month outcome of 130 clinical patients.

PURPOSE To assess 12-month outcomes and safety of clinical magnetic resonance (MR)-guided focused ultrasound (US) treatments of uterine leiomyomas. MATERIALS AND METHODS Between March 2005 and December 2009, 150 women with symptomatic uterine leiomyomas were clinically treated with MR-guided focused US at a single institution; 130 patients completed treatment and agreed to have their data used for research purposes. Patients were followed through retrospective review of medical records and phone interviews conducted at 3-, 6-, and 12-month intervals after treatment to assess additional procedures and symptom relief. Outcome measures and treatment complications were analyzed for possible correlations with the appearance of the tumors on T2-weighted imaging. RESULTS The cumulative incidence of additional tumor-related treatments 12 months after MR-guided focused US was 7.4% by the Kaplan-Meier method. At 3-, 6-, and 12-month follow-up, 86% (90 of 105), 93% (92 of 99), and 88% (78 of 89) of patients reported relief of symptoms, respectively. No statistically significant correlation between tumor appearance on T2-weighted imaging and 12-month outcome was found. Treatment-related complications were observed in 17 patients (13.1%): 16 patients had minor complications and one had a major complication (deep vein thrombosis). All complications were resolved within the 12-month follow-up period. CONCLUSIONS MR-guided focused US is a noninvasive treatment option that can be used to effectively and safely treat uterine leiomyomas and delivers significant and lasting symptom relief for at least 12 months. The incidence of additional treatment during this time period is comparable with those in previous reports of uterine artery embolization.

Image quality evaluation of a desktop computed radiography system.

The modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) of the Lumisys ACR-2000 desktop computed radiography (CR) reader were measured and compared to equivalent measurements acquired from a Fuji AC-3 CR system. The one-dimensional (1D) MTF was measured from an image of a sharp edge and the 1D NPS was derived from a 2D NPS measured from a uniform field exposure. The energy dependent ideal input signal to noise ratio of the incident x-ray beams was estimated using published x-ray spectra and attenuation coefficients. Measurements were acquired using Agfa, Fuji, and Kodak storage phosphor plates and it was concluded that use of the Fuji plates resulted in the highest system DQE for the ACR-2000. The DQE was measured using exposures of 0.10, 1.0, and 10.0 mR from 70 and 120 kVp x-ray beams filtered with aluminum. The DQE of the Lumisys ACR-2000 was lower than that of the Fuji AC-3.

FOUR-YEAR EXPERIENCE WITH A CLINICAL ULTRASOUND QUALITY CONTROL PROGRAM

Ultrasound (US) quality control (QC) program data over a 4-year period from more than 45 scanners and more than 265 transducers were reviewed to optimize the program in terms of efficiency and effectiveness. Our program included evaluations of mechanical integrity, image uniformity, distance measurement accuracy and maximum depth of penetration (DOP). We computed failure rates and fraction of failures detected by each test. A total of 187 equipment problems were identified. Average annual scanner component and transducer failure rates were 10.5% and 13.9%, respectively. The mechanical integrity and uniformity evaluations detected 25.1% and 66.3% of all failures, respectively. Those evaluations plus defects detected by sonographers accounted for 98.4% of all detected failures. DOP and distance measurement accuracy were not effective at detecting equipment failures. For routine US QC, we recommend quarterly mechanical integrity and uniformity assessments of all transducers. A scanner with five transducers could be tested in an estimated 30 min or less.

ACR–AAPM–SIIM Practice Guideline for Digital Radiography

This guideline was developed collaboratively by the American College of Radiology (ACR), the American Association of Physicists in Medicine (AAPM), and the Society for Imaging Informatics in Medicine (SIIM). Increasingly, medical imaging and patient information are being managed using digital data during acquisition, transmission, storage, display, interpretation, and consultation. The management of these data during each of these operations may have an impact on the quality of patient care. “CR” and “DR” are the commonly used terms for digital radiography detectors. CR is the acronym for computed radiography, and DR is an acronym for digital radiography. CR uses a photostimulable storage phosphor that stores the latent image, which is subsequently read out using a stimulating laser beam. It can be easily adapted to a cassette-based system analogous to that used in screen-film (SF) radiography. Historically, the acronym DR has been used to describe a flat-panel digital X-ray imaging system that reads the transmitted X-ray signal immediately after exposure with the detector in place. Generically, the term CR is applied to passive detector systems, while the term DR is applied to active detectors. This guideline is applicable to the practice of digital radiography. It defines motivations, qualifications of personnel, equipment guidelines, data manipulation and management, and quality control (QC) and quality improvement procedures for the use of digital radiography that should result in high-quality radiological patient care. In all cases for which an ACR practice guideline or technical standard exists for the modality being used or the specific examination being performed, that guideline or standard will continue to apply when digital image data management systems are used.

The effect of magnification on sonographically measured nerve cross‐sectional area

Introduction: The primary aim of this investigation was to determine whether use of write‐zoom magnification affects sonographically determined cross‐sectional area (CSA) of peripheral nerves. Methods: CSAs of the median (MN) and posterior interosseous (PIN) nerves were measured in 22 limbs from 11 asymptomatic volunteers using both standard imaging and write‐zoom magnification. CSA measurements were repeated on the same images 1 week later. Results: The average CSA of write‐zoomed images for the MN was significantly larger at both measurement sessions (week 1: 11.1 mm2 write‐zoom vs. 10.0 mm2 standard, P = 0.019; week 2: 11.8 mm2 vs. 10.4 mm2, P = 0.023). Similar differences were noted for the PIN (week 1: 2.3 mm2 vs. 1.9 mm2, P = 0.002; week 2: 2.5 mm2 vs. 1.9 mm2, P = 0.001). Conclusions: Write‐zoom magnification may significantly increase the measured CSA of peripheral nerves. These changes appear to be more substantial when smaller nerves are measured. Muscle Nerve 51: 30–34, 2015

Evaluation of a low-cost liquid ultrasound test object for detection of transducer artefacts

Routine quality control of ultrasound scanners and transducers is important for maintaining image quality. Our experience suggests that artefact and uniformity evaluation is the most effective single phantom test for detecting equipment problems. Current methods for assessing ultrasound images for artefacts have important limitations. To overcome these limitations, we have developed a novel, low-cost, liquid phantom with a flexible surface for assessing artefacts. A range of materials were evaluated and the optimal liquid phantom was found to be a water/cornstarch solution contained within a flexible latex balloon. When compared to a rigid tissue-mimicking phantom no deficiencies in overall image appearance or artefact detection for any transducer model was observed for the liquid phantom. With minimal training, reproducible clips were obtained by clinical sonographers with low inter- and intra-operator dependence, for a range of transducers models. The flexible scanning surface of the liquid phantom allows complete rapid coupling of all transducers. Due to its ease of use and low cost this liquid phantom appears superior to rigid phantoms for assessment of non-uniformity artefacts, and should allow clinical practices to perform routine artefact assessments of all ultrasound scanners and transducers.

Quantitative evaluation of overall electronic display quality

ConclusionsThis study indicates that contrast-detail data should be very helpful in providing quantitative measurements of overall electronic display quality. The method would be suitable for new equipment selection, acceptance testing, and quality control. The recommended protocol would only involve observer data obtained using test images with mid-range background pixed values. Improvements to the current linear curve fit may also provide increased levels of measurement precision and sensitivity. To put the measurements in proper context, MTC measurements of a group of displays currently in use and deemed acceptable for the clinical display) should be obtained by a group of observers, if possible.When making quantitative recommendations regarding equipment selection, or display configuration (eg, maximum display luminance or ambient room lighting levels), a group of observers should be used, since the decisions made will presumably affect a large number of radiologists, technologists or clinical physicians using the display workstations. With a group of five observers, and using the group paired difference analysis technique, measurement precision will be 9.0%, and sensitivity to MTC changes will be 11.1%. Each set of raw data for a measurement of MTC can be collected and analyzed for each observer in approximately 30 minutes, so data sufficient for a comparison of two devices could be collected and analyzed within an hour.When making measurements for equipment acceptance testing or routine QC measurements (eg, on a quarterly or twice-yearly basis), measurements from a single observer should suffice since the goal is an assessment of the relative performance of an individual device. Precision of the single observer MTC measurements will be 6.8%, and sensitivity will be 15.2%. Measurements made over a period of time should have a reproducibility of about 5%.

Optimization of a contrast-detail-based method for electronic image display quality evaluation

The authors previously reported a general technique based on contrast-detail methods to provide an overall quantitative evaluation of electronic image display quality. The figure-of-merit reflecting overall display quality is called maximum threshold contrast or MTC. In this work we have optimized the MTC technique through improvements in both the test images and the figure-of-merit computation. The test images were altered to match the average luminance with that observed for clinical computed radiographic images. The figure-of-merit calculation was altered to allow for contrast-detail data with slopes not equal to −1. Preliminary experiments also were conducted to demonstrate the response of the MTC measurements to increased noise in the displayed image. MTC measurements were obtained from five observers using the improved test images displayed with maximum monitor luminance settings of 30-, 50-, and 70-ft-Lamberts. Similar measurements were obtained from two observers using test images altered by the addition of a low level of image noise. The noise-free MTC and MTC difference measurements exhibited standard deviations of 0.77 and 1.55, respectively. This indicates good measurement precision, comparable or superior to that observed using the earlier MTC technique. No statistically significant image quality differences versus maximum monitor luminance were seen. The noise-added MTC measurements were greater than the noise-free values by an average of 4.08 pixel values, and this difference was statistically significant. This response is qualitatively correct, and is judged to indicate good sensitivity of the MTC measurement to increased noise levels.

Evaluation of Irreversible JPEG Compression for A Clinical Ultrasound Practice

A prior ultrasound study indicated that images with low to moderate levels of JPEG and wavelet compression were acceptable for diagnostic purposes. The purpose of this study is to validate this prior finding using the Joint Photographic Experts Group (JPEG) baseline compression algorithm, at a compression ratio of approximately 10:1, on a sufficiently large number of grayscale and color ultrasound images to attain a statistically significant result. The practical goal of this study is to determine if it is feasible for radiologists to use irreversibly compressed images as an integral part of the day to day ultrasound practice (ie, perform primary diagnosis with, and store irreversibly compressed images in the ultrasound PACS archive). In this study, 5 Radiologists were asked to review 300 grayscale and color static ultrasound images selected from 4 major anatomic groups. Each image was compressed and decompressed using the JPEG baseline compression algorithm at a fixed quality factor resulting in an average compression ratio of approximately 9:1. The images were presented in pairs (original and compressed) in a blinded fashion on a PACS workstation in the ultrasound reading areas, and radiologists were asked to pick which image they preferred in terms of diagnostic utility and their degree of certainty (on a scale from 7 to 4). Of the 1,499 total readings, 50.17% (95% confidence intervals at 47.6%, and 52.7%) indicated a preference for the original image in the pair, and 49.83% (95% confidence intervals at 47.3%, and 52.0%) indicated a preference for the compressed image. These findings led the authors to conclude that static color and gray-scale ultrasound images compressed with JPEG at approximately 9:1 are statistically indistinguishable from the originals for primary diagnostic purposes. Based on the authors laboratory experience with compression and the results of this and other prior studies JPEG compression is now being applied to all ultrasound images in the authors radiology practice before reading. No image quality-related issues have been encountered after 12 months of operation (approximately 48,000 examinations).

Evaluation of the accuracy of a continuous speech recognition software system in radiology

ADIOLOGY REPORTS in most medical settings are generally dictated by the radiologists and then transci by a human transcriptionist, resulting in a text report. The radiologist then finalizes the transcribed report after reviewing it and assuring the accuracy of the text. Time delays between the various stages of this process usually mean that the final reports are available only after several hours or more have passed following interpretation of the examination. The emergence of automatic speech recognition software has suggested that all reading rooms operate in the direct dictation mode without involving the human transci When used in conjunction with electronic systems for managing the text information (radiology information system IRIS]) and image information (picture archiving