Are T2WI PI-RADS sub-scores of transition zone prostate lesions biased by DWI information? A multi-reader, single-center study.

PURPOSE: According to PI-RADS v2.1, T2-weighted imaging (T2WI) is the dominant sequence for transition zone (TZ) lesions. This study aimed to assess, whether diffusion-weighted imaging (DWI) information influences the assignment of T2WI scores. METHOD: Out of 283 prostate MRI examinations with correlated biopsy results, fourty-four patients were selected retrospectively: first, 22 patients with a TZ lesion with T2WI and DWI scores ≥ 4, to represent lesions with unequivocal suspicion on T2WI and DWI. Second, 22 additional patients with TZ lesions of similar T2WI appearance but with corresponding DWI score ≤ 3 were added as control. Four residents and one board-certified radiologist each performed two assessments of the included patients: First, only T2WI was available (T2-only read); second, both T2WI and DWI sequences were available (biparametric read). Lesion scores were assessed using Wilcoxon signed-rank test, inter-reader agreement using weighted kappa and Kendall's W statistics, and sensitivity/specificity using McNemar test. RESULTS: The T2WI scores were significantly different between the T2-only and biparametric read for 3 out of 4 residents (p ≤ 0.049) but not for the radiologist. The overall PI-RADS scores derived from the two reading sessions differed considerably for 35/220 cases (all readers pooled). Inter-reader agreement was fair for the T2WI and overall PI-RADS scores (mean kappa 0.27-0.30) and moderate for the DWI scores (mean kappa 0.43). CONCLUSIONS: For inexperienced readers, assessment of T2WI is variable and potentially biased by availability of DWI information, which can lead to changes of overall PI-RADS score and consequently clinical management. Assessment of T2WI should be performed before reviewing DWI to ensure non-biased interpretation of TZ lesions in the dominant sequence.

Pseudoprospective Paraclinical Interaction of Radiology Residents With a Deep Learning System for Prostate Cancer Detection: Experience, Performance, and Identification of the Need for Intermittent Recalibration.

OBJECTIVES: The aim of this study was to estimate the prospective utility of a previously retrospectively validated convolutional neural network (CNN) for prostate cancer (PC) detection on prostate magnetic resonance imaging (MRI). MATERIALS AND METHODS: The biparametric (T2-weighted and diffusion-weighted) portion of clinical multiparametric prostate MRI from consecutive men included between November 2019 and September 2020 was fully automatically and individually analyzed by a CNN briefly after image acquisition (pseudoprospective design). Radiology residents performed 2 research Prostate Imaging Reporting and Data System (PI-RADS) assessments of the multiparametric dataset independent from clinical reporting (paraclinical design) before and after review of the CNN results and completed a survey. Presence of clinically significant PC was determined by the presence of an International Society of Urological Pathology grade 2 or higher PC on combined targeted and extended systematic transperineal MRI/transrectal ultrasound fusion biopsy. Sensitivities and specificities on a patient and prostate sextant basis were compared using the McNemar test and compared with the receiver operating characteristic (ROC) curve of CNN. Survey results were summarized as absolute counts and percentages. RESULTS: A total of 201 men were included. The CNN achieved an ROC area under the curve of 0.77 on a patient basis. Using PI-RADS ≥3-emulating probability threshold (c3), CNN had a patient-based sensitivity of 81.8% and specificity of 54.8%, not statistically different from the current clinical routine PI-RADS ≥4 assessment at 90.9% and 54.8%, respectively ( P = 0.30/ P = 1.0). In general, residents achieved similar sensitivity and specificity before and after CNN review. On a prostate sextant basis, clinical assessment possessed the highest ROC area under the curve of 0.82, higher than CNN (AUC = 0.76, P = 0.21) and significantly higher than resident performance before and after CNN review (AUC = 0.76 / 0.76, P ≤ 0.03). The resident survey indicated CNN to be helpful and clinically useful. CONCLUSIONS: Pseudoprospective paraclinical integration of fully automated CNN-based detection of suspicious lesions on prostate multiparametric MRI was demonstrated and showed good acceptance among residents, whereas no significant improvement in resident performance was found. General CNN performance was preserved despite an observed shift in CNN calibration, identifying the requirement for continuous quality control and recalibration.

A New Approach for Photorealistic Visualization of Rendered Computed Tomography Images.

OBJECTIVE: Classical single-colored or multicolored 3-dimensional (3D) visualization of sectional images lacked in being realistic and revealed limited anatomical discrimination. Recently, a new technique called cinematic volume rendering for 3D reconstruction of computed tomography has been developed. The aim of this study was to analyze this new visualization algorithm from a technical perspective and to investigate potential benefits for neurosurgical applications. METHODS: A standard test in computer graphics called Cornell Box was adapted and applied for reproducibility of light effects in cinematic rendering opposed to classic rendering methods. Simulation of distinct camera effects such as variable apertures, exposition time, optics, and surface refinements are presented in a human skull, respectively. Postprocessing capabilities allow for immediate clinical use. RESULTS: This volume-rendering technique generates cadaver-like 3D reconstructions. By considering complex interactions between a scanned object and dynamic light patterns, a cinematic illumination of a 3D surface reconstruction can be achieved. A spinal tumor case and a complex intracranial carotid artery aneurysm are presented, comparing all available rendering techniques. Cinematic rendering results in greater spatial discrimination of neighboring anatomical structures. CONCLUSIONS: This technical and clinical description focuses on the neurosurgical relevance of a new rendering technique. Considering the improved image impression of cinematic rendering and viewers' perception, it seems likely that the technique will gain wide acceptance in the clinical routine.

23Na MRI and myometry to compare eplerenone vs. glucocorticoid treatment in Duchenne dystrophy.

In this pilot study we tested whether a low dose application of a mild diuretic substance such as eplerenone is beneficial in early stages of Duchenne muscular dystrophy using 23Na und 1H imaging, myometry, and clinical testing versus the glucocorticoid gold standard. Two 7-years old patients with DMD were examined on a 3T MRI system. 1H MRI and 23Na density-adapted 3-dimensional radial MRI sequences were performed both before and 1, 3 and 6 months after therapy with eplerenone respectively cortisone. We quantified fatty infiltration on T1-weighted images using subcutaneous fat as reference and fat fraction with a two-point DIXON sequence. Muscle oedema was quantified on STIR images and DIXON water maps with background noise as reference. We quantified Na+ by a muscular tissue concentration sequence with a 51.3mM Na+ with 5% agarose reference tube. A Na+ IR-sequence was used for determination of mainly myoplasmic Na+. Correspondingly myometry of muscles and tendons were assessed. Clinical tests (i.e. 4-steps-test) and blood counts (i.e. K+) were done by a pediatrician. Under eplerenone therapy we detected a reduction of muscular oedema, intracellular-weighted sodium IR signal and muscular sodium concentration. The oedema reduction in the DMD patient receiving eplerenone was more pronounced to the patient with cortisone. Myometric-measured tissue parameters such as muscle stiffness had a more pronounced effect in the child treated with eplerenone after a first increase in muscle stiffness both after eplerenone and cortisone treatment. Clinical abilities during both therapies were mostly constant. Eplerenone might be a possible new therapy option in DMD patients.

New bone post-processing tools in forensic imaging: a multi-reader feasibility study to evaluate detection time and diagnostic accuracy in rib fracture assessment.

PURPOSE: The aim of this multi-reader feasibility study was to evaluate new post-processing CT imaging tools in rib fracture assessment of forensic cases by analyzing detection time and diagnostic accuracy. MATERIALS AND METHODS: Thirty autopsy cases (20 with and 10 without rib fractures in autopsy) were randomly selected and included in this study. All cases received a native whole body CT scan prior to the autopsy procedure, which included dissection and careful evaluation of each rib. In addition to standard transverse sections (modality A), CT images were subjected to a reconstruction algorithm to compute axial labelling of the ribs (modality B) as well as "unfolding" visualizations of the rib cage (modality C, "eagle tool"). Three radiologists with different clinical and forensic experience who were blinded to autopsy results evaluated all cases in a random manner of modality and case. RESULTS: Rib fracture assessment of each reader was evaluated compared to autopsy and a CT consensus read as radiologic reference. A detailed evaluation of relevant test parameters revealed a better accordance to the CT consensus read as to the autopsy. Modality C was the significantly quickest rib fracture detection modality despite slightly reduced statistic test parameters compared to modalities A and B. CONCLUSION: Modern CT post-processing software is able to shorten reading time and to increase sensitivity and specificity compared to standard autopsy alone. The eagle tool as an easy to use tool is suited for an initial rib fracture screening prior to autopsy and can therefore be beneficial for forensic pathologists.

7-T (35)Cl and (23)Na MR Imaging for Detection of Mutation-dependent Alterations in Muscular Edema and Fat Fraction with Sodium and Chloride Concentrations in Muscular Periodic Paralyses.

Purpose To determine whether altered sodium (Na(+)) and chloride (Cl(-)) homeostasis can be visualized in periodic paralyses by using 7-T sodium 23 ((23)Na) and chlorine 35 ((35)Cl) magnetic resonance (MR) imaging. Materials and Methods Institutional review board approval and informed consent of all participants were obtained. (23)Na (repetition time msec/echo time msec, 160/0.35) and (35)Cl (40/0.6) MR imaging of both lower legs was performed with a 7-T whole-body system in patients with genetically confirmed hypokalemic periodic paralysis (Cav1.1-R1239H mutation, n = 5; Cav1.1-R528H mutation, n = 8) and Andersen-Tawil syndrome (n = 3) and in 16 healthy volunteers. Additionally, each participant underwent 3-T proton MR imaging on the same day by using T1-weighted, short-tau inversion-recovery, and Dixon-type sequences. Muscle edema was assessed on short-tau inversion-recovery images, fatty degeneration was assessed on T1-weighted images, and muscular fat fraction was quantified with Dixon-type imaging. Na(+) and Cl(-) were quantified in the soleus muscle by using three phantoms that contained 10-, 20-, and 30-mmol/L NaCl solution and 5% agarose gel as a reference. Parametric data for all subpopulations were tested by using one-way analysis of variance with the Dunnett test, and correlations were assessed with the Spearman rank correlation coefficient. Results Median muscular (23)Na concentration was higher in patients with Cav1.1-R1239H (34.7 mmol/L, P < .001), Cav1.1-R528H (32.0 mmol/L, P < .001), and Kir2.1 (24.3 mmol/L, P = .035) mutations than in healthy volunteers (19.9 mmol/L). Median muscular normalized (35)Cl signal intensity was higher in patients with Cav1.1-R1239H (27.6, P < .001) and Cav1.1-R528H (23.6, P < .001) than in healthy volunteers (12.6), but not in patients with the Kir2.1 mutation (14.3, P = .517). When compared with volunteers, patients with Cav1.1-R1239H and Cav1.1-R528H showed increased muscular edema (P < .001 and P = .003, respectively) and muscle fat fraction (P < .001 and P = .017, respectively). Conclusion With 7-T MR imaging, changes of Na(+) and Cl(-) homeostasis can be visualized in periodic paralyses and are most pronounced in the severe phenotype Cav1.1-R1239H, with up to daily paralytic episodes. (©) RSNA, 2016 An earlier incorrect version of this article appeared online. This article was corrected on April 18, 2016.

Bacterial reprogramming of PBMCs impairs monocyte phagocytosis and modulates adaptive T cell responses.

Septic diseases are characterized by an initial systemic, proinflammatory phase, followed by a period of anti-inflammation. In the context of the latter, monocytes have been described to display altered functions, including reduced TNF secretion and T cell-stimulating capacities in response to recall antigens. This hyporesponsiveness is supposed to be detrimental for coping with secondary infections. We here characterize bacterially reprogrammed PBMC-derived monocytes with special focus on their phagocytic activity. Hence, we have implemented a surrogate model of the early, postinflammatory period by exposing PBMCs to Escherichia coli on d0 and rechallenging them with bacteria on d2. This induced the emergence of a distinct monocytic phenotype with profound phagocytic impairments but a preserved ability for naïve T cell stimulation. The compromising effects on phagocytosis required the presence of bacteria and were not mimicked by TLR4 ligation or exposure to isolated cytokines alone. Moreover, the impairments were specific for the engulfment of bacteria and were coupled to a selective down-regulation of FcγR and SR expression. Intriguingly, this monocytic phenotype contributed to the stimulation of a T(H)17-polarized adaptive immune response in the context of secondary infection. Our findings extend the current knowledge of monocytic reprogramming and identify the phagocytic capacity of monocytes as a putative sepsis biomarker.