High dynamic range ultrasound imaging

Abstract

Purpose

High dynamic range (HDR) imaging is a popular computational photography technique that has found its way into every modern smartphone and camera. In HDR imaging, images acquired at different exposures are combined to increase the luminance range of the final image, thereby extending the limited dynamic range of the camera. Ultrasound imaging suffers from limited dynamic range as well; at higher power levels, the hyperechogenic tissue is overexposed, whereas at lower power levels, hypoechogenic tissue details are not visible. In this work, we apply HDR techniques to ultrasound imaging, where we combine ultrasound images acquired at different power levels to improve the level of detail visible in the final image.

Methods

Ultrasound images of ex vivo and in vivo tissue are acquired at different acoustic power levels and then combined to generate HDR ultrasound (HDR-US) images. The performance of five tone mapping operators is quantitatively evaluated using a similarity metric to determine the most suitable mapping for HDR-US imaging.

Results

The ex vivo and in vivo results demonstrated that HDR-US imaging enables visualizing both hyper- and hypoechogenic tissue at once in a single image. The Durand tone mapping operator preserved the most amount of detail across the dynamic range.

Conclusions

Our results strongly suggest that HDR-US imaging can improve the utility of ultrasound in image-based diagnosis and procedure guidance.

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Once-weekly versus every-other-day stereotactic body radiotherapy in patients with prostate cancer (PATRIOT): A phase 2 randomized trial

Publication date: Available online 15 March 2018
Source:Radiotherapy and Oncology
Author(s): Harvey C. Quon, Aldrich Ong, Patrick Cheung, William Chu, Hans T. Chung, Danny Vesprini, Amit Chowdhury, Dilip Panjwani, Geordi Pang, Renee Korol, Melanie Davidson, Ananth Ravi, Boyd McCurdy, Liying Zhang, Alexandre Mamedov, Andrea Deabreu, Andrew Loblaw
Background and purposeProstate stereotactic body radiotherapy (SBRT) regimens differ in time, dose, and fractionation. We completed a multicentre, randomized phase II study to investigate the impact of overall treatment time on quality of life (QOL).Material and methodsMen with low and intermediate-risk prostate cancer were randomly assigned to 40 Gy in 5 fractions delivered once per week (QW) vs. every other day (EOD). QOL was assessed using the Expanded Prostate Cancer Index Composite. The primary endpoint was the proportion with a minimum clinically important change (MCIC) in bowel QOL during the acute (≤12 week) period, and analysis was by intention-to-treat. ClinicalTrials.gov NCT01423474.Results152 men from 3 centres were randomized with median follow-up of 47 months. Patients treated QW had superior acute bowel QOL with 47/69 (68%) reporting a MCIC compared to 63/70 (90%) treated EOD (p = 0.002). Fewer patients treated QW reported moderate–severe problems with bowel QOL during the acute period compared with EOD (14/70 [20%] vs. 40/70 [57%], p < 0.001). Acute urinary QOL was also better in the QW arm, with 52/67 (78%) vs 65/69 (94%) experiencing a MCIC (p = 0.006). There were no significant differences in late urinary or bowel QOL at 2 years or last follow-up.ConclusionProstate SBRT delivered QW improved acute bowel and urinary QOL compared to EOD. Patients should be counselled regarding the potential for reduced short-term toxicity and improved QOL with QW prostate SBRT.



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Interaction Should Guide Management Decisions [LETTERS]

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Reply: [LETTERS]

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Anatomic Malformations of the Middle and Inner Ear in 22q11.2 Deletion Syndrome: Case Series and Literature Review [HEAD & NECK]

BACKGROUND AND PURPOSE:

The 22q11.2 deletion syndrome is characterized by a heterogenic phenotype, including hearing loss. The underlying cause of hearing loss, especially sensorineural hearing loss, is not yet clear. Therefore, our objective was to describe anatomic malformations in the middle and inner ear in patients with 22q11.2 deletion syndrome.

MATERIALS AND METHODS:

A retrospective case series was conducted in 2 tertiary referral centers. All patients with 22q11.2 deletion syndrome who had undergone CT or MR imaging of the temporal bones were included. Radiologic images were evaluated on predetermined parameters, including abnormalities of the ossicular chain, cochlea, semicircular canals, and vestibule.

RESULTS:

There were 26 patients (52 ears) with a CT or MR imaging scan available. A dense stapes superstructure was found in 18 ears (36%), an incomplete partition type II was suspected in 12 cochleas (23%), the lateral semicircular canal was malformed with a small bony island in 17 ears (33%), and the lateral semicircular canal and vestibule were fused to a single cavity in 15 ears (29%).

CONCLUSIONS:

Middle and inner ear abnormalities were frequently encountered in our cohort, including malformations of the lateral semicircular canal.

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Brain Diffusion Abnormalities in Children with Tension-Type and Migraine-Type Headaches [PEDIATRICS]

BACKGROUND AND PURPOSE:

Tension-type and migraine-type headaches are the most common chronic paroxysmal disorders of childhood. The goal of this study was to compare regional cerebral volumes and diffusion in tension-type and migraine-type headaches against published controls.

MATERIALS AND METHODS:

Patients evaluated for tension-type or migraine-type headache without aura from May 2014 to July 2016 in a single center were retrospectively reviewed. Thirty-two patients with tension-type headache and 23 with migraine-type headache at an average of 4 months after diagnosis were enrolled. All patients underwent DWI at 3T before the start of pharmacotherapy. Using atlas-based DWI analysis, we determined regional volumetric and diffusion properties in the cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, brain stem, and cerebral white matter. Multivariate analysis of covariance was used to test for differences between controls and patients with tension-type and migraine-type headaches.

RESULTS:

There were no significant differences in regional brain volumes between the groups. Patients with tension-type and migraine-type headaches showed significantly increased ADC in the hippocampus and brain stem compared with controls. Additionally, only patients with migraine-type headache showed significantly increased ADC in the thalamus and a trend toward increased ADC in the amygdala compared with controls.

CONCLUSIONS:

This study identifies early cerebral diffusion changes in patients with tension-type and migraine-type headaches compared with controls. The hypothesized mechanisms of nociception in migraine-type and tension-type headaches may explain the findings as a precursor to structural changes seen in adult patients with chronic headache.

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Randomized Assessment of the Safety and Efficacy of Intra-Arterial Infusion of Autologous Stem Cells in Subacute Ischemic Stroke [INTERVENTIONAL]

BACKGROUND AND PURPOSE:

Stroke is a debilitating illness for which treatment window is limited. Most patients present to the healthcare facility beyond that window. Autologous stem cells have shown some promise for this group of patients. This study was performed to evaluate the safety and the efficacy of intra-arterial infusion of bone marrow–derived mononuclear cells in patients with middle cerebral artery ischemic stroke.

MATERIALS AND METHODS:

A prospective, randomized, open-label, blinded–end point study was performed from July 2015 to June 2016. Of 229 patients with acute stroke who presented to the hospital during this period, 20 patients who satisfied the inclusion/exclusion criteria were included and randomized into the control and intervention groups. Intra-arterial stem cell infusion into the ipsilateral MCA was performed in the patients in the intervention group at 8–15 days post-stroke ictus. Final analysis at 6 months was performed for primary (safety) and secondary outcomes (efficacy).

RESULTS:

When we compared the primary end point of the study, no procedure-related mortality, complication, new infarct, or symptomatic intracranial hemorrhage was seen in the intervention group. When we compared the secondary end point of good clinical outcome, 8 (80%) patients in the intervention group showed good clinical outcome (modified Rankin Scale score < 2) with 4 (40%) patients in the control group achieving this (95% confidence interval for good outcome in patients with stem cell infusion, 49.03–94.3, and without stem cell infusion, 16.82–68.73; P = .068).

CONCLUSIONS:

Intra-arterial infusion of stem cells can be carried out safely in the subacute stage of ischemic stroke. Improved clinical outcomes were observed with intra-arterial stem cell therapy; however, studies with larger cohorts are needed to validate the results.

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