Nevin Manimala

Invest Radiol. 2021 May 27. doi: 10.1097/RLI.0000000000000796. Online ahead of print.

ABSTRACT

OBJECTIVES: The objectives of this exploratory study were to investigate the feasibility of multidimensional diffusion magnetic resonance imaging (MddMRI) in assessing diffusion heterogeneity at both a macroscopic and microscopic level in prostate cancer (PCa).

MATERIALS AND METHODS: Informed consent was obtained from 46 subjects who underwent 3.0-T prostate multiparametric MRI, complemented with a prototype spin echo-based MddMRI sequence in this institutional review board-approved study. Prostate cancer tumors and comparative normal tissue from each patient were contoured on both apparent diffusion coefficient and MddMRI-derived mean diffusivity (MD) maps (from which microscopic diffusion heterogeneity [MKi] and microscopic diffusion anisotropy were derived) using 3D Slicer. The discriminative ability of MddMRI-derived parameters to differentiate PCa from normal tissue was determined using the Friedman test. To determine if tumor diffusion heterogeneity is similar on macroscopic and microscopic scales, the linear association between SD of MD and mean MKi was estimated using robust regression (bisquare weighting). Hypothesis testing was 2 tailed; P values less than 0.05 were considered statistically significant.

RESULTS: All MddMRI-derived parameters could distinguish tumor from normal tissue in the fixed-effects analysis (P < 0.0001). Tumor MKi was higher (P < 0.05) compared with normal tissue (median, 0.40; interquartile range, 0.29-0.52 vs 0.20-0.18; 0.25), as was tumor microscopic diffusion anisotropy (0.55; 0.36-0.81 vs 0.20-0.15; 0.28). The MKi could not be predicted (no significant association) by SD of MD. There was a significant correlation between tumor volume and SD of MD (R2 = 0.50, slope = 0.008 μm2/ms per millimeter, P < 0.001) but not between tumor volume and MKi.

CONCLUSIONS: This explorative study demonstrates that MddMRI provides novel information on MKi and microscopic anisotropy, which differ from measures at the macroscopic level. MddMRI has the potential to characterize tumor tissue heterogeneity at different spatial scales.

PMID:34049334 | DOI:10.1097/RLI.0000000000000796

Otol Neurotol. 2021 May 26. doi: 10.1097/MAO.0000000000003200. Online ahead of print.

ABSTRACT

OBJECTIVE: Characterize the speech recognition and sound source localization of patients with unilateral Meniere’s disease who undergo labyrinthectomy for vertigo control with simultaneous or sequential cochlear implantation.

DATABASES REVIEWED: PubMed, Embase, and Cochrane databases.

METHODS: The search was performed on May 6, 2020. The keywords utilized included: “Meniere’s disease AND cochlear implant”; “cochlear implant AND single sided deafness”; “cochlear implant AND vestibular”; and “labyrinthectomy AND cochlear implant”. Manuscripts published in English with a publication date after 1995 that assessed adult subjects (≥18 years of age) were included for review. Subjects must have been diagnosed with Meniere’s disease unilaterally and underwent labyrinthectomy with simultaneous or sequential cochlear implantation. Reported outcomes with cochlear implant (CI) use included speech recognition as measured with the Consonant-Nucleus-Consonant (CNC) word test and/or sound source localization reported in root-mean squared (RMS) error. The method of data collection and study type were recorded to assess level of evidence. Statistical analysis was performed with Wilcoxon signed ranks test.

RESULTS: Data from 14 CI recipients met the criteria for inclusion. Word recognition comparisons between the pre-operative interval and a post-activation interval demonstrated a significant improvement with the CI (p = 0.014), with an average improvement of 23% (range -16-50%). Sound source localization post-operatively with the CI demonstrated an average RMS error of 26° (SD 6.8, range 18.7-43.1°) compared to the 42° (SD 19.1, range 18-85°) in the pre-operative or CI off condition, these two conditions were not statistically different (p = 0.148).

CONCLUSION: Cochlear implantation and labyrinthectomy in adult patients with Meniere’s disease can support improvements in speech recognition and sound source localization for some CI users, though observed performance may be poorer than traditional CI candidates.

PMID:34049331 | DOI:10.1097/MAO.0000000000003200

Otol Neurotol. 2021 May 26. doi: 10.1097/MAO.0000000000003204. Online ahead of print.

ABSTRACT

OBJECTIVE: To examine if performing stapedotomy as the first case of the day provides improved outcomes compared with those performed later in the day.

STUDY DESIGN: Retrospective chart review.

SETTING: Tertiary referral center.

PATIENTS: Adult patients undergoing stapedotomy for otosclerosis.

MAIN OUTCOME MEASURES: Patients were separated into either a first case group or a later case group based on surgical start time. Audiologic outcomes and complications were compared between the two groups.

RESULTS: The first case group had a smaller postoperative air-bone gap (ABG) compared with the later case group of 9.81 dB HL compared with 11.73dB HL and 3.79 dB HL compared with 6.29 dB HL at 1000 and 2000 Hz, respectively (p = 0.03, p < 0.01). The mean postoperative ABG was 10.63 dB HL for the first start group compared with 12.12 dB HL for the later start group, which was statistically significant (p = 0.05).

CONCLUSIONS: First start stapedotomy is associated with slightly improved audiologic outcomes compared with those starting later in the day, although both groups had significantly improved postoperative outcomes overall. There was no significant difference in complications when comparing stapedotomy by case start time.

PMID:34049326 | DOI:10.1097/MAO.0000000000003204

J Nurs Res. 2021 May 27. doi: 10.1097/JNR.0000000000000437. Online ahead of print.

ABSTRACT

BACKGROUND: Urinary catheters (UCs) with a closed urinary drainage system have been widely used in patients for many years. However, the frequency of replacing and operating these devices may be associated with catheter-associated urinary tract infection (CAUTI).

PURPOSE: This study was designed to compare the incidence of CAUTI by replacement time (every 14 or ≥ 15 days) of the urinary drainage system.

METHODS: This 1-year prospective, nonrandomized controlled study was conducted in a major teaching hospital. The Transparent Reporting of Evaluations with Nonrandomized Designs Statement checklist was used. All of the patients with UCs were divided into two groups based on each patient’s preference with regard to replacement time of the urinary drainage system.

RESULTS: Five hundred sixty-two patients were evaluated, and 341 patients with UCs were enrolled as participants in the study. In the per-protocol analysis, 16 patients (22.2%; 9.3 episodes/1,000 catheter-days) in the 14-day group and 15 patients (17.9%; relative risk = 1.24, 95% confidence interval [0.66, 2.34]) in the ≥ 15-day group (7.7 episodes/1,000 catheter-days; incidence density ratio 1.20, 95% confidence interval [0.60, 2.43]) had CAUTIs. A comparison of cleanliness within urinary bags showed no significant intergroup difference (p > .05). In the intention-to-treat analysis, the incidence of CAUTI between the two groups was also not significantly different (p > .05).

CONCLUSIONS: No statistically significant difference in the incidence of CAUTI was identified between patients who used the 14-day replacement interval and those who used the ≥ 15-day replacement interval for their urinary drainage system.

PMID:34049325 | DOI:10.1097/JNR.0000000000000437

J Nurs Res. 2021 May 27. doi: 10.1097/JNR.0000000000000435. Online ahead of print.

ABSTRACT

BACKGROUND: The World Health Organization encourages countries to improve birth outcomes to reduce rates of neonatal mortality and morbidity.

PURPOSE: This study was designed to examine the effect of environmental crude oil pollution on newborn birth outcomes in Rivers State, Nigeria.

METHODS: A retrospective cohort design was used to examine the effects of exposure to oil pollution on birth outcomes using facility-based records. K-Dere (an oil-polluted community) served as the exposure group, whereas birth records from Iriebe served as the comparison group. A sample size of 338 systematically selected birth records was examined (169 records for each arm of the study). A data extraction sheet was used for data collection. Data were analyzed using descriptive and inferential statistics at p < .05.

RESULTS: The risk of preterm birth was significantly higher in the exposed group (16% vs. 7.7%, relative risk = 2.08, 95% CI [1.11, 3.89], p = .018). At 6 weeks after birth, newborns in the exposed group weighed significantly less (4.64 ± 0.82 vs. 4.85 ± 0.92 kg, p = .032) and reported significantly higher incidence of morbidity compared with the newborns in the comparison group (relative risk = 3.03, 95% CI [2.20, 4.19], p < .001).

CONCLUSIONS: The oil-polluted area examined in this study was found to have a higher risk of preterm birth, a slower rate of newborn growth, and a higher rate of newborn morbidity than the non-oil-polluted area at 6 weeks after birth. Stakeholders should sustain efforts to remediate the environment in polluted regions and prevent oil pollution. Future research should investigate the mechanisms of the observed toxicological effects and the targeted protection of vulnerable groups in oil-polluted communities.

PMID:34049324 | DOI:10.1097/JNR.0000000000000435

ASAIO J. 2021 May 28. doi: 10.1097/MAT.0000000000001490. Online ahead of print.

ABSTRACT

Maintaining dialysis vascular access is a source of considerable morbidity in patients with end-stage renal disease (ESRD). High-resolution radiofrequency (RF) ultrasound vascular strain imaging has been applied experimentally in the vascular access setting to assist in diagnosis and management. Unfortunately, high-resolution RF data are not routinely accessible to clinicians. In contrast, the standard DICOM formatted B-mode ultrasound data are widely accessible. However, B-mode, representing the envelope of the RF signal, is of much lower resolution. If strain imaging could use open-source B-mode data, these imaging techniques could be more broadly investigated. We conducted experiments to detect wall strain signals with submillimeter tracking resolutions ranging from 0.2 mm (3 pixels) to 0.65 mm (10 pixels) using DICOM B-mode data. We compared this submillimeter tracking to the overall vascular distensibility as the reference measurements to see if high-strain resolution strain could be detected using open-source B-Mode data. We measured the best-fit coefficient of determination between signals, expressed as the percentage of strain waveforms that exhibited a correlation with a p value of 0.05 or less. The lowest percentage was 86.7%, and most were 90% and higher. This indicates high-resolution strain signals can be detected within the vessel wall using B-mode DICOM data.

PMID:34049311 | DOI:10.1097/MAT.0000000000001490

Phys Med Biol. 2021 May 28. doi: 10.1088/1361-6560/ac0681. Online ahead of print.

ABSTRACT

For decades, dose-volume information for segmented anatomy has provided the essential data for correlating radiotherapy dosimetry with treatment-induced complications. Dose-volume information has formed the basis for modelling those associations via normal tissue complication (NTCP) models and for driving treatment planning. Limitations to this approach have been identified. Many studies have emerged demonstrating that the incorporation of information describing the spatial nature of the dose distribution, and potentially its correlation with anatomy, can provide more robust associations with toxicity and seed more general NTCP models. Such approaches are culminating in the application of computationally intensive processes such as machine learning and the application of neural networks. The opportunities these approaches have for individualising treatment, predicting toxicity and expanding the solution space for radiation therapy are substantial and have clearly widespread and disruptive potential. Impediments to reaching that potential include issues associated with data collection, model generalisation and validation. This review examines the role of spatial models of complication and summarises relevant published studies. Sources of data for these studies, appropriate statistical methodology, frameworks for processing spatial dose information and extracting relevant features are described. Spatial complication modelling is consolidated as a pathway to guiding future developments towards effective, complication-free radiotherapy treatment.

PMID:34049304 | DOI:10.1088/1361-6560/ac0681

Phys Med Biol. 2021 May 28. doi: 10.1088/1361-6560/ac0684. Online ahead of print.

ABSTRACT

CT images for radiotherapy planning are usually acquired in thick slice to reduce imaging dose, especially for pediatric patients, and to lessen the need for contouring and treatment planning on more slices. However, low through-plane resolution may degrade the accuracy of dose calculations. In this paper, a self-supervised deep learning workflow is proposed to synthesize high through-plane resolution CT images by learning from their high in-plane resolution features. The proposed workflow was designed to facilitate the neural networks to learn the mapping from low resolution (LR) to high resolution (HR) images in the axial plane. During the inference step, the HR sagittal and coronal images were generated by feeding two parallelly trained neural networks with the respective LR sagittal and coronal images to the trained neural networks. The CT simulation images of a cohort of 75 head and neck (HN) cancer patients (1 mm slice thickness) and 200 CT images of a cohort of 20 lung cancer patients (3 mm slice thickness) were retrospectively investigated with a cross validation manner. The generated HR images with the proposed method were qualitatively (visual quality, image intensity profiles and preliminary observer study) and quantitatively (Mean Absolute Error (MAE), Edge Keeping Index (EKI), Structural Similarity Index Measurement (SSIM), Information Fidelity Criterion (IFC) and Visual Information Fidelity in Pixel domain (VIFP)) inspected, while taking the original HN and lung cancer patients’ CT images as the reference. The qualitative results have shown the capability of the proposed method for generating high through-plane resolution CT images with data of the HN and lung cancer patients. All the improvements of the measure metrics are confirmed to be statistically significant with paired two-sample t-test analysis. The innovative point of the work is that the proposed deep learning workflow for CT image generation with high through-plane resolution in radiotherapy is self-supervised, which means it does not rely on ground truth CT images to train the network. In addition, the assumption that the in-plane HR information can supervise the through-plane HR generation is confirmed and anticipated to potentially inspire more researches on this topic to further improve the through-plane resolution of medical images.

PMID:34049297 | DOI:10.1088/1361-6560/ac0684

Phys Med Biol. 2021 May 28. doi: 10.1088/1361-6560/ac0683. Online ahead of print.

ABSTRACT

Multiple injection dynamic positron emission tomography (PET) scanning is used in the clinical management of certain groups of patients and in medical research. The analysis of these studies can be approached in two ways: (i) separate analysis of data from individual tracer injections, or (ii), concatenate/pool data from separate injections and carry out a combined analysis. The simplicity of separate analysis has some practical appeal but may not be statistically efficient. We use a linear model framework associated with a kinetic mapping scheme to develop a simplified theoretical understanding of separate and combined analysis. The theoretical framework is explored numerically using both 1-D and 2-D simulation models. These studies are motivated by the breast cancer flow-metabolism mismatch studies involving 15O-Water (H2O) and 18F-Fluorodeoxyglucose (FDG) and repeat 15O-H2O injections used in brain activation investigations. Numerical results are found to be substantially in line with the simple theoretical analysis: mean square error (MSE) characteristics of alternative methods are well described by factors involving the local voxel-level resolution of the imaging data, the relative activities of the individual scans and the number of separate injections involved. While voxel-level resolution has dependence on scan dose, after adjustment for this effect, the impact of a combined analysis is understood in simple terms associated with the linear model used for kinetic mapping. This is true for both data reconstructed by direct filtered backprojection (FBP) or iterative maximum likelihood (ML). The proposed analysis has potential to be applied to the emerging long axial field-of-view PET scanners.

PMID:34049293 | DOI:10.1088/1361-6560/ac0683

Phys Med Biol. 2021 May 28. doi: 10.1088/1361-6560/ac0682. Online ahead of print.

ABSTRACT

The use of multi-pinhole collimation has enabled ultra-high-resolution imaging of SPECT and PET tracers in small animals. Key for obtaining high-quality images is the use of statistical iterative image reconstruction with accurate energy-dependent photon transport modelling through collimator and detector. This can be incorporated in a system matrix that contains the probabilities that a photon emitted from a certain voxel is detected at a specific detector pixel. Here we introduce a Fast Monte-Carlo based (FMC-based) matrix generation method for pinhole imaging that is easy to apply to various radionuclides. The method is based on accelerated point-source simulations combined with model-based interpolation to straightforwardly change or combine photon energies of the isotope of interest. The proposed method was evaluated for a VECTor PET-SPECT system with (i) a HE-UHR-M collimator and (ii) an EXIRAD-3D 3D autoradiography collimator. Both experimental scans with^99mTc,¹¹¹In, and¹²³I, and simulated scans with⁶⁷Ga and⁹⁰Y were performed for evaluation. FMC was compared with two currently used approaches, one based on a set of point-source measurements with^99mTc (dubbed traditional method), and the other based on an energy-dependent ray-tracing simulation (ray-tracing method). The reconstruction results show better image quality when using FMC-based matrices than when applying the traditional or ray-tracing matrices in various cases. FMC-based matrices generalise better than the traditional matrices when imaging isotopes with energies deviating too much from the energy used in the calibration and are computationally more efficient for very-high-resolution imaging than the ray-tracing matrices. In addition, FMC has the advantage of easily combining energies in a single matrix which is relevant when imaging isotopes with multiple photopeak energies (e.g.⁶⁷Ga and¹¹¹In) or with a continuous energy spectrum (e.g.⁹⁰Y). To conclude, FMC is an efficient, accurate, and versatile tool for creating system matrices for ultra-high-resolution pinhole SPECT.

PMID:34049291 | DOI:10.1088/1361-6560/ac0682