274 research outputs found
Run-Off Computed Tomography Angiography (CTA) for Discriminating the Underlying Causes of Intermittent Claudication
Aim To evaluate run-off computed tomography angiography (CTA) of abdominal
aorta and lower extremities for detecting musculoskeletal pathologies and
clinically relevant extravascular incidental findings in patients with
intermittent claudication (IC) and suspected peripheral arterial disease
(PAD). Does run-off CTA allow image-based therapeutic decision making by
discriminating the causes of intermittent claudication in patients with
suspected peripheral arterial disease PAD? Material and Methods Retrospective
re-evaluation of CTAs performed in patients with acute or chronic intermittent
claudication (i.e., Fontaine stages I to IIB) between January 2005 and October
2013. Allocation to one of three categories of underlying causes of IC
symptoms: vascular, musculoskeletal (MSK) or both. Clinically relevant
extravascular incidental findings were evaluated. Medical records were
reviewed to verify specific therapies as well as main and incidental findings.
Results While focused on vascular imaging, CTA image quality was sufficient
for evaluation of the MSK system in all cases. The underlying cause of IC was
diagnosed in run-off CTA as vascular, MSK and a combination in n = 138 (65%),
n = 10 (4%), and n = 66 (31%) cases, respectively. Specific vascular or MSK
therapy was recorded in n = 123 and n = 9 cases. In n = 82, no follow-up was
possible. Clinically relevant extravascular incidental findings were detected
in n = 65 patients (30%) with neoplasia, ascites and pleural effusion being
the most common findings. Discussion Run-off CTA allows identification of
vascular, MSK, and combined causes of IC in patients with suspected PAD and
can guide specific therapy. CTA also allowed confident detection of crEVIF
although detection did not necessarily trigger workup or treatment
Radiomics for Everyone: A New Tool Simplifies Creating Parametric Maps for the Visualization and Quantification of Radiomics Features
Aim was to develop a user-friendly method for creating parametric maps that would provide a comprehensible visualization and allow immediate quantification of radiomics features. For this, a self-explanatory graphical user interface was designed, and for the proof of concept, maps were created for CT and MR images and features were compared to those from conventional extractions. Especially first-order features were concordant between maps and conventional extractions, some even across all examples. Potential clinical applications were tested on CT and MR images for the differentiation of pulmonary lesions. In these sample applications, maps of Skewness enhanced the differentiation of non-malignant lesions and non-small lung carcinoma manifestations on CT images and maps of Variance enhanced the differentiation of pulmonary lymphoma manifestations and fungal infiltrates on MR images. This new and simple method for creating parametric maps makes radiomics features visually perceivable, allows direct feature quantification by placing a region of interest, can improve the assessment of radiological images and, furthermore, can increase the use of radiomics in clinical routine
Enhancing the stability of CT radiomics across different volume of interest sizes using parametric feature maps: a phantom study
Background: In radiomics studies, differences in the volume of interest (VOI) are often inevitable and may confound the extracted features. We aimed to correct this confounding effect of VOI variability by applying parametric maps with a fixed voxel size.
Methods: Ten scans of a cup filled with sodium chloride solution were scanned using a multislice computed tomography (CT) unit. Sphere-shaped VOIs with different diameters (4, 8, or 16 mm) were drawn centrally into the phantom. A total of 93 features were extracted conventionally from the original images using PyRadiomics. Using a self-designed and pretested software tool, parametric maps for the same 93 features with a fixed voxel size of 4 mm3 were created. To retrieve the feature values from the maps, VOIs were copied from the original images to preserve the position. Differences in feature quantities between the VOI sizes were tested with the Mann-Whitney U-test and agreement with overall concordance correlation coefficients (OCCC).
Results: Fifty-five conventionally extracted features were significantly different between the VOI sizes, and none of the features showed excellent agreement in terms of OCCCs. When read from the parametric maps, only 8 features showed significant differences, and 3 features showed an excellent OCCC (≥ 0.85). The OCCCs for 89 features substantially increased using the parametric maps.
Conclusions: This phantom study shows that converting CT images into parametric maps resolves the confounding effect of VOI variability and increases feature reproducibility across VOI sizes
Somatostatin receptor PET/CT in restaging of typical and atypical lung carcinoids
Background To assess the role of somatostatin receptor (SR) PET/CT using Ga-68
DOTATOC or DOTATATE in staging and restaging of typical (TC) and atypical (AC)
lung carcinoids. Methods Clinical and PET/CT data were retrospectively
analyzed in 27 patients referred for staging (N = 5; TC, N = 4; AC, N = 1) or
restaging (N = 22; TC, N = 8; AC, N = 14). Maximum standardized uptake value
(SUVmax) of SR-positive lesions was normalized to the SUVmax of the liver to
generate SUVratio; SR PET was compared to contrast-enhanced (ce) CT. The
classification system proposed by Rindi et al. (Endocr Relat Cancer.
2014;21(1):1-16, 2014) was used for classification of patients in TC and AC
groups. Results Only 18/27 patients were found to have metastases on PET/CT.
Of the 186 lesions, 101 (54.3 %) were depicted on both PET and CT, 53 (28.5 %)
lesions only on CT, and 32 (17.2 %) only on PET. SUVratio of lesions was
significantly higher in AC as compared to TC (p < 0.001). In patients referred
for restaging, additional findings on PET lead to upstaging with change in
management strategy in 5/22 (22.7 %) patients (AC, N = 5; TC, N = 1). In four
patients (all AC) referred for restaging and in one patient (TC) referred for
staging, additional findings on CT missed on PET lead to correct staging.
Conclusions Typical and atypical carcinoid patients have complex patterns of
metastases which make it necessary to combine functional SR PET and contrast-
enhanced CT for appropriate restaging. In patients referred for restaging SR,
PET may have a relevant impact on treatment strategy in up to 22.7 of patients
with typical and atypical lung carcinoids
Enhancing the differentiation of pulmonary lymphoma and fungal pneumonia in hematological patients using texture analysis in 3-T MRI
Objectives: To evaluate texture analysis in nonenhanced 3-T MRI for differentiating pulmonary fungal infiltrates and lymphoma manifestations in hematological patients and to compare the diagnostic performance with that of signal intensity quotients ("nonenhanced imaging characterization quotients," NICQs).
Methods: MR scans were performed using a speed-optimized imaging protocol without an intravenous contrast medium including axial T2-weighted (T2w) single-shot fast spin-echo and T1-weighted (T1w) gradient-echo sequences. ROIs were drawn within the lesions to extract first-order statistics from original images using HeterogeneityCAD and PyRadiomics. NICQs were calculated using signal intensities of the lesions, muscle, and fat. The standard of reference was histology or clinical diagnosis in follow-up. Statistical testing included ROC analysis, clustered ROC analysis, and DeLong test. Intra- and interrater reliability was tested using intraclass correlation coefficients (ICC).
Results: Thirty-three fungal infiltrates in 16 patients and 38 pulmonary lymphoma manifestations in 19 patients were included. Considering the leading lesion in each patient, diagnostic performance was excellent for T1w entropy (AUC 80.2%; p 0.81) for these parameters except for moderate intrarater reliability of T1w energy (ICC = 0.64).
Conclusions: T1w entropy, uniformity, and energy and T2w energy showed the best performances for differentiating pulmonary lymphoma and fungal pneumonia and outperformed NICQs. Results of the texture analysis should be checked for their intrinsic consistency to identify possible incongruities of single parameters.
Key points: • Texture analysis in nonenhanced pulmonary MRI improves the differentiation of pulmonary lymphoma and fungal pneumonia compared with signal intensity quotients. • T1w entropy, uniformity, and energy along with T2w energy show the best performances for differentiating pulmonary lymphoma from fungal pneumonia. • The results of the texture analysis should be checked for their intrinsic consistency to identify possible incongruities of single parameters
Does Hepatic Steatosis Influence the Detection Rate of Metastases in the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI?
The aim of this exploratory study was to evaluate the influence of hepatic steatosis on the detection rate of metastases in gadoxetic acid-enhanced liver magnetic resonance imaging (MRI). A total of 50 patients who underwent gadoxetic acid-enhanced MRI (unenhanced T1w in- and opposed-phase, T2w fat sat, unenhanced 3D-T1w fat sat and 3-phase dynamic contrast-enhanced (uDP), 3D-T1w fat sat hepatobiliary phase (HP)) were retrospectively included. Two blinded observers (O1/O2) independently assessed the images to determine the detection rate in uDP and HP. The hepatic signal fat fraction (HSFF) was determined as the relative signal intensity reduction in liver parenchyma from in- to opposed-phase images. A total of 451 liver metastases were detected (O1/O2, n = 447/411). O1/O2 detected 10.9%/9.3% of lesions exclusively in uDP and 20.2%/15.5% exclusively in HP. Lesions detected exclusively in uDP were significantly associated with a larger HSFF (area under curve (AUC) of receiver operating characteristic (ROC) analysis, 0.93; p 30%) is a potential pitfall for the detection of metastases in HP
Mild therapeutic hypothermia alters neuron specific enolase as an outcome predictor after resuscitation: 97 prospective hypothermia patients compared to 133 historical non-hypothermia patients
Quantitative assessment of the asphericity of pretherapeutic FDG uptake as an independent predictor of outcome in NSCLC
Background The aim of the present study was to evaluate the predictive value
of a novel quantitative measure for the spatial heterogeneity of FDG uptake,
the asphericity (ASP) in patients with non-small cell lung cancer (NSCLC).
Methods FDG-PET/CT had been performed in 60 patients (15 women, 45 men; median
age, 65.5 years) with newly diagnosed NSCLC prior to therapy. The FDG-PET
image of the primary tumor was segmented using the ROVER 3D segmentation tool
based on thresholding at the volume-reproducing intensity threshold after
subtraction of local background. ASP was defined as the relative deviation of
the tumor’s shape from a sphere. Univariate and multivariate Cox regression as
well as Kaplan-Meier (KM) analysis and log-rank test with respect to overall
(OAS) and progression-free survival (PFS) were performed for clinical
variables, SUVmax/mean, metabolically active tumor volume (MTV), total lesion
glycolysis (TLG), ASP and “solidity”, another measure of shape irregularity.
Results ASP, solidity and “primary surgical treatment” were significant
independent predictors of PFS in multivariate Cox regression with binarized
parameters (HR, 3.66; p < 0.001, HR, 2.11; p = 0.05 and HR, 2.09; p = 0.05),
ASP and “primary surgical treatment” of OAS (HR, 3.19; p = 0.02 and HR, 3.78;
p = 0.01, respectively). None of the other semi-quantitative PET parameters
showed significant predictive value with respect to OAS or PFS. Kaplan-Meier
analysis revealed a probability of 2-year PFS of 52% in patients with low ASP
compared to 12% in patients with high ASP (p < 0.001). Furthermore, it showed
a higher OAS rate in the case of low versus high ASP (1-year-OAS, 91% vs. 67%:
p = 0.02). Conclusions The novel parameter asphericity of pretherapeutic FDG
uptake seems to provide better prognostic value for PFS and OAS in NCSLC
compared to SUV, metabolic tumor volume, total lesion glycolysis and solidity
Diffusion-weighted magnetic resonance imaging using a preclinical 1 T PET/MRI in healthy and tumor-bearing rats
Background: Hybrid positron emission tomography and magnetic resonance imaging (PET/MRI) scanners are increasingly used for both clinical and preclinical imaging. Especially functional MRI sequences such as diffusionweighted imaging (DWI) are of great interest as they provide information on a molecular level, thus, can be used as surrogate biomarkers. Due to technical restrictions, MR sequences need to be adapted for each system to perform reliable imaging. There is, to our knowledge, no suitable DWI protocol for 1 Tesla PET/MRI scanners. We aimed to establish such DWI protocol with focus on the choice of b values, suitable for longitudinal monitoring of tumor characteristics in a rat liver tumor model.
Material and methods: DWI was first performed in 18 healthy rat livers using the scanner-dependent maximum of 4 b values (0, 100, 200, 300 s/mm2). Apparent diffusion coefficients (ADC) were calculated from different b value combinations and compared to the reference measurement with four b values. T2-weighted MRI and optimized DWI with best agreement between accuracy, scanning time, and system performance stability were used to monitor orthotopic hepatocellular carcinomas (HCC) in five rats of which three underwent additional 2-deoxy-2-(18F)fluoro-D-glucose(FDG)-PET imaging. ADCs were calculated for the tumor and the surrounding liver parenchyma and verified by histopathological analysis.
Results: Compared to the reference measurements, the combination b = 0, 200, 300 s/mm2 showed the highest correlation coefficient (rs = 0.92) and agreement while reducing the acquisition time. However, measurements with less than four b values yielded significantly higher ADCs (p < 0.001). When monitoring the HCC, an expected drop of the ADC was observed over time. These findings were paralleled by FDG-PET showing both an increase in tumor size and uptake heterogeneity. Interestingly, surrounding liver parenchyma also showed a change in ADC values revealing varying levels of inflammation by immunohistochemistry.
Conclusion: We established a respiratory-gated DWI protocol for a preclinical 1 T PET/MRI scanner allowing to monitor growth-related changes in ADC values of orthotopic HCC liver tumors. By monitoring the changes in tumor ADCs over time, different cellular stages were described. However, each study needs to adapt the protocol further according to their question to generate best possible results
a randomized, open, multicenter phase III trial of lenalidomide/dexamethasone versus lenalidomide/dexamethasone plus subsequent autologous stem cell transplantation and lenalidomide maintenance in patients with relapsed multiple myeloma
Background Despite novel therapeutic agents, most multiple myeloma (MM)
patients eventually relapse. Two large phase III trials have shown
significantly improved response rates (RR) of lenalidomide/dexamethasone
compared with placebo/dexamethasone in relapsed MM (RMM) patients. These
results have led to the approval of lenalidomide for RMM patients and
lenalidomide/dexamethasone has since become a widely accepted second-line
treatment. Furthermore, in RMM patients consolidation with high-dose
chemotherapy plus autologous stem cell transplantation has been shown to
significantly increase progression free survival (PFS) as compared to
cyclophosphamide in a phase III trial. The randomized prospective ReLApsE
trial is designed to evaluate PFS after lenalidomide/dexamethasone induction,
high-dose chemotherapy consolidation plus autologous stem cell transplantation
and lenalidomide maintenance compared with the well-established
lenalidomide/dexamethasone regimen in RMM patients. Methods/Design ReLApsE is
a randomized, open, multicenter phase III trial in a planned study population
of 282 RMM patients. All patients receive three lenalidomide/dexamethasone
cycles and - in absence of available stem cells from earlier harvesting -
undergo peripheral blood stem cell mobilization and harvesting. Subsequently,
patients in arm A continue on consecutive lenalidomide/dexamethasone cycles,
patients in arm B undergo high dose chemotherapy plus autologous stem cell
transplantation followed by lenalidomide maintenance until discontinuation
criteria are met. Therapeutic response is evaluated after the 3rd (arm A + B)
and the 5th lenalidomide/dexamethasone cycle (arm A) or 2 months after
autologous stem cell transplantation (arm B) and every 3 months thereafter
(arm A + B). After finishing the study treatment, patients are followed up for
survival and subsequent myeloma therapies. The expected trial duration is 6.25
years from first patient in to last patient out. The primary endpoint is PFS,
secondary endpoints include overall survival (OS), RR, time to best response
and the influence of early versus late salvage high dose chemotherapy plus
autologous stem cell transplantation on OS. Discussion This phase III trial is
designed to evaluate whether high dose chemotherapy plus autologous stem cell
transplantation and lenalidomide maintenance after lenalidomide/dexamethasone
induction improves PFS compared with the well-established continued
lenalidomide/dexamethasone regimen in RMM patients. Trial registration:
ISRCTN16345835 (date of registration 2010-08-24)
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