Beyond fractional anisotropy in amyotrophic lateral sclerosis: the value of mean, axial, and radial diffusivity and its correlation with electrophysiological conductivity changes

Abstract

Purpose

This paper aims to analyze the contribution of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the detection of microstructural abnormalities in amyotrophic lateral sclerosis (ALS) and to evaluate the degree of agreement between structural and functional changes through concomitant diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), and clinical assessment.

Methods

Fourteen patients with ALS and 11 healthy, age- and gender-matched controls were included. All participants underwent magnetic resonance imaging including DTI. TMS was additionally performed in ALS patients. Differences in the distribution of DTI-derived measures were assessed using tract-based spatial statistical (TBSS) and volume of interest (VOI) analyses. Correlations between clinical, imaging, and neurophysiological findings were also assessed through TBSS.

Results

ALS patients showed a significant increase in AD and MD involving the corticospinal tract (CST) and the pre-frontal white matter in the right posterior limb of the internal capsule (p < 0.05) when compared to the control group using TBSS, confirmed by VOI analyses. VOI analyses also showed increased AD in the corpus callosum (p < 0.05) in ALS patients. Fractional anisotropy (FA) in the right CST correlated significantly with upper motor neuron (UMN) score (r = − 0.79, p < 0.05), and right abductor digiti minimi central motor conduction time was highly correlated with RD in the left posterior internal capsule (r = − 0.81, p < 0.05). No other significant correlation was found.

Conclusion

MD, AD, and RD, besides FA, are able to further detect and characterize neurodegeneration in ALS. Furthermore, TMS and DTI appear to have a role as complementary diagnostic biomarkers of UMN dysfunction.

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Beyond fractional anisotropy in amyotrophic lateral sclerosis: the value of mean, axial, and radial diffusivity and its correlation with electrophysiological conductivity changes

Abstract

Purpose

This paper aims to analyze the contribution of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the detection of microstructural abnormalities in amyotrophic lateral sclerosis (ALS) and to evaluate the degree of agreement between structural and functional changes through concomitant diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), and clinical assessment.

Methods

Fourteen patients with ALS and 11 healthy, age- and gender-matched controls were included. All participants underwent magnetic resonance imaging including DTI. TMS was additionally performed in ALS patients. Differences in the distribution of DTI-derived measures were assessed using tract-based spatial statistical (TBSS) and volume of interest (VOI) analyses. Correlations between clinical, imaging, and neurophysiological findings were also assessed through TBSS.

Results

ALS patients showed a significant increase in AD and MD involving the corticospinal tract (CST) and the pre-frontal white matter in the right posterior limb of the internal capsule (p < 0.05) when compared to the control group using TBSS, confirmed by VOI analyses. VOI analyses also showed increased AD in the corpus callosum (p < 0.05) in ALS patients. Fractional anisotropy (FA) in the right CST correlated significantly with upper motor neuron (UMN) score (r = − 0.79, p < 0.05), and right abductor digiti minimi central motor conduction time was highly correlated with RD in the left posterior internal capsule (r = − 0.81, p < 0.05). No other significant correlation was found.

Conclusion

MD, AD, and RD, besides FA, are able to further detect and characterize neurodegeneration in ALS. Furthermore, TMS and DTI appear to have a role as complementary diagnostic biomarkers of UMN dysfunction.

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Determination of the proton RBE in the rat spinal cord: Is there an increase towards the end of the spread-out Bragg peak?

Publication date: Available online 21 March 2018
Source:Radiotherapy and Oncology
Author(s): Maria Saager, Peter Peschke, Stephan Brons, Jürgen Debus, Christian P. Karger
Background and purposeTo determine the relative biological effectiveness (RBE) of protons in the rat spinal cord as a function of linear energy transfer (LET) and dose.Materials and methodsThe rat cervical spinal cord was irradiated with single or two equal fractions (split doses) of protons at four positions (LET 1.4–5.5 keV/µm) along a 6 cm spread-out Bragg peak (SOBP). From dose-response analysis, TD50- (dose at 50% effect probability) and RBE-values were derived using the endpoint of radiation-induced myelopathy.ResultsAlong the SOBP, the TD50-values decreased from 21.7 ± 0.3 Gy to 19.5 ± 0.5 Gy for single and from 32.3 ± 0.3 Gy to 27.9 ± 0.5 Gy for split doses. The corresponding RBE-values increased from 1.13 ± 0.04 to 1.26 ± 0.05 (single doses) and from 1.06 ± 0.02 to 1.23 ± 0.03 (split doses).ConclusionsFor the relative high fractional doses, the experimental RBE at the distal edge of the proton SOBP is moderately increased. The conventionally applied RBE of 1.1 appears to be valid for the mid-SOBP region, but the higher values occurring more distally could be of clinical significance, especially if critical structures are located in this area. Further in vivo studies at lower fractional doses are urgently required.



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The predictive value for excellent response to initial therapy in differentiated thyroid cancer: preablation-stimulated thyroglobulin better than the TNM stage.

The predictive value for excellent response to initial therapy in differentiated thyroid cancer: preablation-stimulated thyroglobulin better than the TNM stage.

Nucl Med Commun. 2018 Mar 19;:

Authors: Zhang Y, Hua W, Zhang X, Peng J, Liang J, Gao Z

Abstract
PURPOSE: This study aimed to identify the predictive value of the low preablation-stimulated thyroglobulin (ps-Tg, <2 ng/ml) for excellent response to radioiodine remnant ablation in differentiated thyroid carcinoma.
PATIENTS AND METHODS: A total of 398 consecutive patients who underwent total thyroidectomy and radioactive iodine remnant ablation therapy were reviewed retrospectively. Each patient was risk-stratified using the American Joint Cancer Committee and risk staging systems and using response to the initial therapy reclassification system. ps-Tg was defined as less than 2 ng/ml with negative thyroglobulin antibody under thyroid-stimulating hormone stimulation. A multivariate analysis was carried out for ps-Tg, TNM stage, and other potential clinical and pathologic factors.
RESULTS: We followed the patients for a median of 32.7 months. Overall, an excellent rate of response was achieved in 367 (92.2%) of the 398 patients. The only variable found to be associated with excellent response was ps-Tg (odds ratio=2.530, P=0.009) by multivariate analysis. The subgroups with 0<ps-Tg<1 ng/ml had a higher success ablation rate than the patients with 1≤ps-Tg<2 ng/ml. Overall, 31 patients were not achieving an excellent response, and most of them showed an indeterminate response. Only two patients who achieved an excellent response were confirmed to have developed recurrence in the follow-up, both in the local regional lymph nodes.
CONCLUSION: There is a good probability that most low ps-Tg (<2 ng/ml) patients can achieve an excellent response. ps-Tg is the essential and independent predictor for an excellent response in the patients with ps-Tg less than 2 ng/ml, which is better than TNM stage.

PMID: 29557849 [PubMed - as supplied by publisher]

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Regression models with asymmetric data for estimating thyroglobulin levels one year after the ablation of thyroid cancer.

Regression models with asymmetric data for estimating thyroglobulin levels one year after the ablation of thyroid cancer.

Stat Methods Med Res. 2018 Jan 01;:962280218764006

Authors: Alvear Rodriguez CA, Tovar Cuevas JR

Abstract
A key biomarker in the study of differentiated thyroid cancer is thyroglobulin. Measurements of the levels of this protein in the blood are determined using laboratory instruments that cannot detect very small concentrations below a threshold, generating left-censored measurements. In the presence of censoring, ordinary least-squares regression models generate biased parameter estimates; therefore, it is necessary to resort to more complex models that consider the censored observations and the behavior of the distribution of the response variable, such as censored and mixed regression models. These techniques were used to model the relationship between thyroglobulin levels in individuals with differentiated thyroid cancer before and after treatment with radioactive iodine (I-131). Log-normal, log-skew-normal, log-power-normal, and log-generalized-gamma probability distributions were used to model the behavior of errors in the adjusted models. Log-generalized-gamma distribution yielded the best results according to the established model selection criteria.

PMID: 29557257 [PubMed - as supplied by publisher]

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A practical guide for planning pelvic bone percutaneous interventions (biopsy, tumour ablation and cementoplasty)

Abstract

Percutaneous approaches for pelvic bone procedures (bone biopsies, tumour ablation and cementoplasty) are multiple and less well systematised than for the spine or extremities. Among the different imaging techniques that can be used for guidance, computed tomography (CT) scan is the modality of choice because of the complex pelvic anatomy. In specific cases, such as cementoplasty where real-time evaluation is a determinant, a combination of CT and fluoroscopy is highly recommended. The objective of this article is to propose a systematic approach for image-guided pelvic bone procedures, as well as to provide some technical tips. We illustrate the article with multiple examples, and diagrams of the approaches and important structures to avoid to perform these procedures safely.

Teaching Points

• Pelvic bone procedures are safe to perform if anatomical landmarks are recognised.

• The safest approach varies depending on the pelvic level.

• CT is the modality of choice for guiding pelvic percutaneous procedures.

• Fluoroscopy is recommended when real-time monitoring is mandatory.

• MRI can also be used for guiding pelvic percutaneous procedures.

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Innovative Clinical Investigations: featured papers in IJCARS

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Variability of CT Airways Measurements in COPD Patients Between Morning and Afternoon

Publication date: Available online 20 March 2018
Source:Academic Radiology
Author(s): Maxime Hackx, Elodie Gyssels, Tiago Severo Garcia, Isabelle De Meulder, Marie Bruyneel, Alain Van Muylem, Vincent Ninane, Pierre Alain Gevenois
Rationale and ObjectivesComputed tomography (CT) airways measurements can be used as surrogates to spirometric measurements for assessing bronchodilation in a particular patient with chronic obstructive pulmonary disease. Although spirometric measurements show variations within the opening hours of a hospital department, we aimed to compare the variability of CT airways measurements between morning and afternoon in patients with chronic obstructive pulmonary disease to that of spirometric measurements.Materials and MethodsTwenty patients had pulmonary function tests and CT around 8 am and 4 pm. Luminal area (LA) and wall thickness (WT) of third and fourth generation airways were measured twice by three readers. The percentage of airway area occupied by the wall (WA%) and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. The effects of examination time, reader, and measurement session on CT airways measurements were assessed, and the variability of these measurements was compared to that of spirometric measurements.ResultsVariability of LA^3rd and LA^4th was greater than that of spirometric measurements (P values ranging from <.001 to .033). There was no examination time effect on √WAPi10, WT^3rd, LA^4th, or WA%^4th (P values ranging from .102 to .712). There was a reader effect on all CT airways measurements (P values ranging from <.001 to .028), except in WT^3rd (P > .999). There was no effect of measurement session on any CT airway measurement (P values ranging from .535 to >.999).ConclusionAs the variability of LA^3rd and LA^4th is greater than that of spirometric measurements, clinical studies should include cohorts with larger numbers of patients when considering LA than when considering spirometric measurements as end points.



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Quality and Efficiency Improvement Tools for Every Radiologist

Publication date: Available online 20 March 2018
Source:Academic Radiology
Author(s): Alexei U. Kudla, Olga R. Brook
In an era of value-based medicine, data-driven quality improvement is more important than ever to ensure safe and efficient imaging services. Familiarity with high-value tools enables all radiologists to successfully engage in quality and efficiency improvement. In this article, we review the model for improvement, strategies for measurement, and common practical tools with real-life examples that include Run chart, Control chart (Shewhart chart), Fishbone (Cause-and-Effect or Ishikawa) diagram, Pareto chart, 5 Whys, and Root Cause Analysis.



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A Radiomics Signature in Preoperative Predicting Degree of Tumor Differentiation in Patients with Non–small Cell Lung Cancer

Publication date: Available online 21 March 2018
Source:Academic Radiology
Author(s): Xin Chen, Mengjie Fang, Di Dong, Xinhua Wei, Lingling Liu, Xiangdong Xu, Xinqing Jiang, Jie Tian, Zaiyi Liu
Rationale and ObjectivesPoorly differentiated non–small cell lung cancer (NSCLC) indicated a poor prognosis and well-differentiated NSCLC indicates a noninvasive nature and good prognosis. The purpose of this study was to build and validate a radiomics signature to predict the degree of tumor differentiation (DTD) for patients with NSCLC.Materials and MethodsA total of 487 patients with pathologically diagnosed NSCLC were retrospectively included in our study. Five hundred ninety-one radiomics features were extracted from each tumor from the contrast-enhanced computed tomography images. A minimum redundancy maximum relevance algorithm and a logistic regression model were used for dimension reduction, feature selection, and radiomics signature building. The performance of the radiomics signature was assessed using receiver operating characteristic analysis, and the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy were calculated to quantify the association between a signature and DTD. An independent validation set contained 184 consecutive patients with NSCLC.ResultsA nine-radiomics-feature-based signature was built and it could differentiate low and high DTDs in the training set (AUC = 0.763, sensitivity = 0.750, specificity = 0.665, and accuracy = 0.687), and the radiomics signature had good discrimination performance in the validation set (AUC = 0.782, sensitivity = 0.608, specificity = 0.752, and accuracy = 0.712).ConclusionsA radiomics signature based on contrast-enhanced computed tomography imaging is a potentially useful imaging biomarker for differentiating low from high DTD in patients with NSCLC.



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A chronic oral ulcerative eruption.

A chronic oral ulcerative eruption.

Oral Surg Oral Med Oral Pathol Oral Radiol. 2018 Feb 13;:

Authors: Faustino ISP, Fernandes DT, Santos-Silva AR, Vargas PA, Lopes MA

PMID: 29555364 [PubMed - as supplied by publisher]

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Chronic painful oral ulcers in a heart transplant recipient.

Chronic painful oral ulcers in a heart transplant recipient.

Oral Surg Oral Med Oral Pathol Oral Radiol. 2018 Feb 21;:

Authors: Pereira MS, Wagner VP, Munerato MC, Clausell NO, Goldraich LA, Martins MAT, Martins MD, Carrard VC

PMID: 29555363 [PubMed - as supplied by publisher]

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Factors Affecting Interpretative Accuracy: How Can We Reduce Errors?

Factors Affecting Interpretative Accuracy: How Can We Reduce Errors?

Radiology. 2018 Apr;287(1):213-214

Authors: Arenson RL

PMID: 29558311 [PubMed - in process]

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Prostate Cancer: Improving the Flow of Research.

Prostate Cancer: Improving the Flow of Research.

Radiology. 2018 Apr;287(1):5-9

Authors: Lawton CAF

Abstract
Prostate cancer is the most common nonskin cancer diagnosed in U.S. men and kills over 27 000 men annually. Thus, improving the outcomes for patients diagnosed with this disease is imperative. There has been a considerable amount of research done over the past several decades resulting in more cures than ever, but the death rate is still unacceptable. This oration addresses the progress that we have made over the past several decades and outlines the work yet to be done, as well as some processes to make that work happen. © RSNA, 2018.

PMID: 29558314 [PubMed - in process]

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Case 256.

Case 256.

Radiology. 2018 Apr;287(1):349-352

Authors: Eisenberg AM, Eppelheimer CN, Fulop TA, Abramson LL

PMID: 29558313 [PubMed - in process]

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CT Fractional Flow Reserve for Stable Coronary Artery Disease: The Ongoing Journey.

CT Fractional Flow Reserve for Stable Coronary Artery Disease: The Ongoing Journey.

Radiology. 2018 Apr;287(1):85-86

Authors: Leipsic JA, Hurwitz Koweek L

PMID: 29558312 [PubMed - in process]

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Deep Learning Lends a Hand to Pediatric Radiology.

Deep Learning Lends a Hand to Pediatric Radiology.

Radiology. 2018 Apr;287(1):323-325

Authors: Summers RM

PMID: 29558310 [PubMed - in process]

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Use of MR Imaging-defined Connectome to Predict the Recovery of Patients after Cardiac Arrest.

Use of MR Imaging-defined Connectome to Predict the Recovery of Patients after Cardiac Arrest.

Radiology. 2018 Apr;287(1):256-257

Authors: Haller S

PMID: 29558302 [PubMed - in process]

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Is Tomosynthesis the Future of Breast Cancer Screening?

Is Tomosynthesis the Future of Breast Cancer Screening?

Radiology. 2018 Apr;287(1):47-48

Authors: Pisano ED

PMID: 29558309 [PubMed - in process]

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Ferumoxtyol-enhanced MR Angiography for Transcatheter Aortic Valve Replacement Planning in Patients with Renal Failure.

Ferumoxtyol-enhanced MR Angiography for Transcatheter Aortic Valve Replacement Planning in Patients with Renal Failure.

Radiology. 2018 Apr;287(1):362-363

Authors: Zhu C, Kallianos K, Henry T, Hope MD

PMID: 29558308 [PubMed - in process]

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Cerebral Microbleeds: Imaging and Clinical Significance.

Cerebral Microbleeds: Imaging and Clinical Significance.

Radiology. 2018 Apr;287(1):11-28

Authors: Haller S, Vernooij MW, Kuijer JPA, Larsson EM, Jäger HR, Barkhof F

Abstract
Cerebral microbleeds (CMBs), also referred to as microhemorrhages, appear on magnetic resonance (MR) images as hypointense foci notably at T2*-weighted or susceptibility-weighted (SW) imaging. CMBs are detected with increasing frequency because of the more widespread use of high magnetic field strength and of newer dedicated MR imaging techniques such as three-dimensional gradient-echo T2*-weighted and SW imaging. The imaging appearance of CMBs is mainly because of changes in local magnetic susceptibility and reflects the pathologic iron accumulation, most often in perivascular macrophages, because of vasculopathy. CMBs are depicted with a true-positive rate of 48%-89% at 1.5 T or 3.0 T and T2*-weighted or SW imaging across a wide range of diseases. False-positive "mimics" of CMBs occur at a rate of 11%-24% and include microdissections, microaneurysms, and microcalcifications; the latter can be differentiated by using phase images. Compared with postmortem histopathologic analysis, at least half of CMBs are missed with premortem clinical MR imaging. In general, CMB detection rate increases with field strength, with the use of three-dimensional sequences, and with postprocessing methods that use local perturbations of the MR phase to enhance T2* contrast. Because of the more widespread availability of high-field-strength MR imaging systems and growing use of SW imaging, CMBs are increasingly recognized in normal aging, and are even more common in various disorders such as Alzheimer dementia, cerebral amyloid angiopathy, stroke, and trauma. Rare causes include endocarditis, cerebral autosomal dominant arteriopathy with subcortical infarcts, leukoencephalopathy, and radiation therapy. The presence of CMBs in patients with stroke is increasingly recognized as a marker of worse outcome. Finally, guidelines for adjustment of anticoagulant therapy in patients with CMBs are under development. © RSNA, 2018.

PMID: 29558307 [PubMed - in process]

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Richard Wier Katzberg, MD.

Richard Wier Katzberg, MD.

Radiology. 2018 Apr;287(1):364

Authors: McGahan J, McDonald RJ

PMID: 29558306 [PubMed - in process]

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Trainee Research Prizes from the 2017 RSNA Scientific Assembly and Annual Meeting.

Trainee Research Prizes from the 2017 RSNA Scientific Assembly and Annual Meeting.

Radiology. 2018 Apr;287(1):1-4

Authors:

PMID: 29558305 [PubMed - in process]

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Case 252: Acute Hyperammonemic Encephalopathy Resulting from Late-Onset Ornithine Transcarbamylase Deficiency.

Case 252: Acute Hyperammonemic Encephalopathy Resulting from Late-Onset Ornithine Transcarbamylase Deficiency.

Radiology. 2018 Apr;287(1):353-359

Authors: Hershman M, Carmody R, Udayasankar UK

Abstract
History A 19-year-old woman with no pertinent medical history was brought to the emergency department after being found unconscious on her bathroom floor by her roommate. In the preceding weeks, she had reported intractable nausea and vomiting, for which she had been taking ondansetron. No other medications had been prescribed. The day prior to presentation, she had contacted her mother and described increasing confusion. Glasgow coma scale score on arrival in the emergency department was 4. Intravenous naloxone was administered, without immediate response. Initial blood glucose level was 232 mg/dL (12.8 mmol/L) (normal range, 79-140 mg/dL [4.4- 7.7 mmol/L]), and other routine laboratory test results were normal. Urine toxicology results were negative. Cerebrospinal fluid evaluation revealed levels were within normal limits. Neurologic examination revealed dilated pupils, which showed a sluggish response to light, and left lower extremity rigidity with intermittent tremors. Initial unenhanced cranial computed tomographic (CT) findings were negative. Magnetic resonance (MR) imaging of the brain was performed. The patient's condition deteriorated, with increasing cerebral edema over the next week, and she was declared brain dead. Her liver was transplanted into an adult recipient, who subsequently developed cerebral edema and elevated plasma ammonia levels, resulting in death in the immediate postoperative period.

PMID: 29558304 [PubMed - in process]

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CT Features for Complicated versus Uncomplicated Appendicitis: What Is the Evidence?

CT Features for Complicated versus Uncomplicated Appendicitis: What Is the Evidence?

Radiology. 2018 Apr;287(1):116-118

Authors: Foley WD

PMID: 29558303 [PubMed - in process]

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Region of Interest Selection in Nonclinical Studies of Accumulated Gadolinium-based Contrast Agent-induced T1 Hyperintensity in Deep Cerebellar Nuclei.

Region of Interest Selection in Nonclinical Studies of Accumulated Gadolinium-based Contrast Agent-induced T1 Hyperintensity in Deep Cerebellar Nuclei.

Radiology. 2018 Apr;287(1):360-362

Authors: Idée JM, Robert P, Raynaud JS, Rasschaert M, Fretellier N, Factor C, Corot C

PMID: 29558301 [PubMed - in process]

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Thyroid Imaging Reporting and Data System (TI-RADS): A User's Guide.

Thyroid Imaging Reporting and Data System (TI-RADS): A User's Guide.

Radiology. 2018 Apr;287(1):29-36

Authors: Tessler FN, Middleton WD, Grant EG

Abstract
In 2017, the Thyroid Imaging Reporting and Data System (TI-RADS) Committee of the American College of Radiology (ACR) published a white paper that presented a new risk-stratification system for classifying thyroid nodules on the basis of their appearance at ultrasonography (US). In ACR TI-RADS, points in five feature categories are summed to determine a risk level from TR1 to TR5. Recommendations for biopsy or US follow-up are based on the nodule's ACR TI-RADS level and its maximum diameter. The purpose of this article is to offer practical guidance on how to implement and apply ACR TI-RADS based on the authors' experience with the system. © RSNA, 2018.

PMID: 29558300 [PubMed - in process]

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Predonation Volume of Future Remnant Cortical Kidney Helps Predict Postdonation Renal Function in Live Kidney Donors.

Predonation Volume of Future Remnant Cortical Kidney Helps Predict Postdonation Renal Function in Live Kidney Donors.

Radiology. 2018 Mar 20;:171642

Authors: Fananapazir G, Benzl R, Corwin MT, Chen LX, Sageshima J, Stewart SL, Troppmann C

Abstract
Purpose To determine whether the predonation computed tomography (CT)-based volume of the future remnant kidney is predictive of postdonation renal function in living kidney donors. Materials and Methods This institutional review board-approved, retrospective, HIPAA-compliant study included 126 live kidney donors who had undergone predonation renal CT between January 2007 and December 2014 as well as 2-year postdonation measurement of estimated glomerular filtration rate (eGFR). The whole kidney volume and cortical volume of the future remnant kidney were measured and standardized for body surface area (BSA). Bivariate linear associations between the ratios of whole kidney volume to BSA and cortical volume to BSA were obtained. A linear regression model for 2-year postdonation eGFR that incorporated donor age, sex, and either whole kidney volume-to-BSA ratio or cortical volume-to-BSA ratio was created, and the coefficient of determination (R2) for the model was calculated. Factors not statistically additive in assessing 2-year eGFR were removed by using backward elimination, and the coefficient of determination for this parsimonious model was calculated. Results Correlation was slightly better for cortical volume-to-BSA ratio than for whole kidney volume-to-BSA ratio (r = 0.48 vs r = 0.44, respectively). The linear regression model incorporating all donor factors had an R2 of 0.66. The only factors that were significantly additive to the equation were cortical volume-to-BSA ratio and predonation eGFR (P = .01 and P < .01, respectively), and the final parsimonious linear regression model incorporating these two variables explained almost the same amount of variance (R2 = 0.65) as did the full model. Conclusion The cortical volume of the future remnant kidney helped predict postdonation eGFR at 2 years. The cortical volume-to-BSA ratio should thus be considered for addition as an important variable to living kidney donor evaluation and selection guidelines. © RSNA, 2018.

PMID: 29558297 [PubMed - as supplied by publisher]

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Effects of Tumor Burden on Reference Tissue Standardized Uptake for PET Imaging: Modification of PERCIST Criteria.

Effects of Tumor Burden on Reference Tissue Standardized Uptake for PET Imaging: Modification of PERCIST Criteria.

Radiology. 2018 Mar 20;:171356

Authors: Viglianti BL, Wale DJ, Wong KK, Johnson TD, Ky C, Frey KA, Gross MD

Abstract
Purpose To examine the effect metabolic burden (tumor and/or cardiac myocyte uptake) has on fluorine 18 fluorodeoxyglucose (FDG) distribution in organs and tissues of interest. Materials and Methods Positron emission tomographic (PET)/computed tomographic (CT) scans at the Ann Arbor Veterans Affairs hospital from January to July 2015 were reviewed. A total of 107 scans (50 patients; mean age, 64.3 years ± 13.2 [standard deviation]) had metabolic tissue burden assessed by using total lesion glycolysis (TLG) obtained from autosegmentation of the tumor and/or cardiac tissue. Standardized uptake value (SUV) and subsequent normalized SUV uptake in target organs and tissues were compared with 436 FDG PET/CT scans previously reported in 229 patients as a function of TLG to describe the effect(s) that metabolic burden has on reference tissue (blood pool, liver, and brain) FDG uptake. Subsequent regression by using linear mixed-effects models was used. If the slope of the regression was significantly (P < .05) different than zero, then an effect from TLG was present. Results There was a negative inverse relationship (P < .0001) between FDG uptake within reference tissues (blood pool, liver, and brain) and TLG in comparison to the study population at similar blood glucose levels. This TLG effect was no longer statistically significant (P > .05) when FDG uptake was normalized to a reference tissue (eg, blood pool or liver). Conclusion Metabolic tissue burden can have a significant effect on SUV measurements for PET imaging. This effect can be mitigated by normalizing FDG uptake to a reference tissue. © RSNA, 2018.

PMID: 29558296 [PubMed - as supplied by publisher]

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CT Prediction Model for Major Arterial Injury after Blunt Pelvic Ring Disruption.

CT Prediction Model for Major Arterial Injury after Blunt Pelvic Ring Disruption.

Radiology. 2018 Mar 20;:170997

Authors: Dreizin D, Bodanapally U, Boscak A, Tirada N, Issa G, Nascone JW, Bivona L, Mascarenhas D, O'Toole RV, Nixon E, Chen R, Siegel E

Abstract
Purpose To develop and test a computed tomography (CT)-based predictive model for major arterial injury after blunt pelvic ring disruptions that incorporates semiautomated pelvic hematoma volume quantification. Materials and Methods A multivariable logistic regression model was developed in patients with blunt pelvic ring disruptions who underwent arterial phase abdominopelvic CT before angiography from 2008 to 2013. Arterial injury at angiography requiring transarterial embolization (TAE) served as the outcome. Areas under the receiver operating characteristic (ROC) curve (AUCs) for the model and for two trauma radiologists were compared in a validation cohort of 36 patients from 2013 to 2015 by using the Hanley-McNeil method. Hematoma volume cutoffs for predicting the need for TAE and probability cutoffs for the secondary outcome of mortality not resulting from closed head injuries were determined by using ROC analysis. Correlation between hematoma volume and transfusion was assessed by using the Pearson coefficient. Results Independent predictor variables included hematoma volume, intravenous contrast material extravasation, atherosclerosis, rotational instability, and obturator ring fracture. In the validation cohort, the model (AUC, 0.78) had similar performance to reviewers (AUC, 0.69-0.72; P = .40-.80). A hematoma volume cutoff of 433 mL had a positive predictive value of 87%-100% for predicting major arterial injury requiring TAE. Hematoma volumes correlated with units of packed red blood cells transfused (r = 0.34-0.57; P = .0002-.0003). Predicted probabilities of 0.64 or less had a negative predictive value of 100% for excluding mortality not resulting from closed head injuries. Conclusion A logistic regression model incorporating semiautomated hematoma volume segmentation produced objective probability estimates of major arterial injury. Hematoma volumes correlated with 48-hour transfusion requirement, and low predicted probabilities excluded mortality from causes other than closed head injury. © RSNA, 2018 Online supplemental material is available for this article.

PMID: 29558295 [PubMed - as supplied by publisher]

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MR Imaging with Apparent Diffusion Coefficient Histogram Analysis: Evaluation of Locally Advanced Rectal Cancer after Chemotherapy and Radiation Therapy.

MR Imaging with Apparent Diffusion Coefficient Histogram Analysis: Evaluation of Locally Advanced Rectal Cancer after Chemotherapy and Radiation Therapy.

Radiology. 2018 Mar 20;:171804

Authors: Enkhbaatar NE, Inoue S, Yamamuro H, Kawada S, Miyaoka M, Nakamura N, Sadahiro S, Imai Y

Abstract
Purpose To determine response to neoadjuvant chemotherapy and radiation therapy in patients with locally advanced rectal cancer (LARC) by using magnetic resonance (MR) apparent diffusion coefficient (ADC) histogram analysis. Materials and Methods Ninety-two patients with LARC underwent MR imaging with rectal barium before and after chemotherapy and radiation therapy (CRT). Rectal expansion with barium expanded the lumen, provided similar imaging geometry before and after CRT, and eliminated fecal matter, air, and residual fluid. T2-weighted images, the percentage change in ADC, and ADC histogram skewness and kurtosis were assessed. The histopathologic tumor regression grade (TRG) ranged from 1a (66%-99% residual tumor cells) to 3 (no residual cells). The Wilcoxon signed-rank test, the Spearman correlation test, multivariable linear regression, and one-way analysis of variance were used to determine post- and pretreatment differences and correlations between tumor size and ADC. Results Of the 92 patients, 16 (17.4%) had TRG 3, 27 (29.3%) had TRG 2b, 24 (26.1%) had TRG 2a, 14 (15.2%) had TRG 1b, and 11 (12%) had TRG 1a. Post-CRT skewness (regression coefficient = 10.9, P = .06) and percentage ADC change (regression coefficient = -0.18, P = .03) were associated with the percentage of residual tumor. Post-CRT skewness and percentage ADC change, respectively, showed negative and positive correlation with histopathologic TRG (post-CRT skewness: P = .024; percentage ADC change: P = .001). Conclusion In patients with LARC, post-CRT skewness of the ADC histogram and percentage change in ADC were useful for predicting a favorable response to neoadjuvant CRT. © RSNA, 2018 Online supplemental material is available for this article.

PMID: 29558294 [PubMed - as supplied by publisher]

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Diffusion Kurtosis Imaging of Acute Infarction: Comparison with Routine Diffusion and Follow-up MR Imaging.

Diffusion Kurtosis Imaging of Acute Infarction: Comparison with Routine Diffusion and Follow-up MR Imaging.

Radiology. 2018 Mar 20;:170553

Authors: Yin J, Sun H, Wang Z, Ni H, Shen W, Sun PZ

Abstract
Purpose To determine the relationship between diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in patients with acute stroke at admission and the tissue outcome 1 month after onset of stroke. Materials and Methods Patients with stroke underwent DWI (b values = 0, 1000 sec/mm2 along three directions) and DKI (b values = 0, 1000, 2000 sec/mm2 along 20 directions) within 24 hours after symptom onset and 1 month after symptom onset. For large lesions (diameter ≥ 1 cm), acute lesion volumes at DWI and DKI were compared with those at follow-up T2-weighted imaging by using Spearman correlation analysis. For small lesions (diameter < 1 cm), the number of acute lesions at DWI and DKI and follow-up T2-weighted imaging was counted and compared by using the McNemar test. Results Thirty-seven patients (mean age, 58 years; range, 35-82 years) were included. There were 32 large lesions and 138 small lesions. For large lesions, the volumes of acute lesions on kurtosis maps showed no difference from those on 1-month follow-up T2-weighted images (P = .532), with a higher correlation coefficient than those on the apparent diffusion coefficient and mean diffusivity maps (R2 = 0.730 vs 0.479 and 0.429). For small lesions, the number of acute lesions on DKI, but not on DWI, images was consistent with that on the follow-up T2-weighted images (P = .125). Conclusion DKI complements DWI for improved prediction of outcome of acute ischemic stroke. © RSNA, 2018.

PMID: 29558293 [PubMed - as supplied by publisher]

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Implementation of GPU accelerated SPECT reconstruction with Monte Carlo-based scatter correction

Abstract

Objective

Statistical SPECT reconstruction can be very time-consuming especially when compensations for collimator and detector response, attenuation, and scatter are included in the reconstruction. This work proposes an accelerated SPECT reconstruction algorithm based on graphics processing unit (GPU) processing.

Methods

Ordered subset expectation maximization (OSEM) algorithm with CT-based attenuation modelling, depth-dependent Gaussian convolution-based collimator-detector response modelling, and Monte Carlo-based scatter compensation was implemented using OpenCL. The OpenCL implementation was compared against the existing multi-threaded OSEM implementation running on a central processing unit (CPU) in terms of scatter-to-primary ratios, standardized uptake values (SUVs), and processing speed using mathematical phantoms and clinical multi-bed bone SPECT/CT studies.

Results

The difference in scatter-to-primary ratios, visual appearance, and SUVs between GPU and CPU implementations was minor. On the other hand, at its best, the GPU implementation was noticed to be 24 times faster than the multi-threaded CPU version on a normal 128 × 128 matrix size 3 bed bone SPECT/CT data set when compensations for collimator and detector response, attenuation, and scatter were included.

Conclusions

GPU SPECT reconstructions show great promise as an every day clinical reconstruction tool.

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Evaluation of condyle position in patients with Angle Class I, II, and III malocclusion using cone-beam computed tomography panoramic reconstructions

Abstract

Objectives

This study was performed to compare the positions of the right and left condyles between male and female patients with different Angle malocclusions using cone-beam computed tomography (CBCT) panoramic reconstructions.

Methods

The CBCT images of 60 patients (age of 18–37 years) were retrospectively evaluated. The patients were divided according to their Angle malocclusion classifications (Angle Classes I, II, and III). The condyle-to-eminence, condyle-to-fossa, and condyle-to-meatus distances were measured digitally using i-CAT software.

Results

The left and right condyle-to-fossa distances were the most variable parameters among the Angle classes. The right condyle-to-eminence and right condyle-to-fossa distances were significantly different among the classes. Male patients seemed to have a greater condyle-to-fossa distance on the right side in both the Class I and III groups. The mean distance from the condyle to eminence, condyle to fossa, and condyle to meatus on the right side was the greatest in the Angle Class II group.

Conclusions

In all three types of malocclusion (Angle Classes I, II, and III), the condyles on both the right and left sides were not exactly symmetric or centrally located within the glenoid fossa. This work emphasizes the differences in the condyle position between male and female patients. Furthermore, the symmetry and centricity of the condyles are not dependent on the patient's sex or type of malocclusion.

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