Statistical evaluation of test-retest studies in PET brain imaging

Abstract

Background

Positron emission tomography (PET) is a molecular imaging technology that enables in vivo quantification of metabolic activity or receptor density, among other applications. Examples of applications of PET imaging in neuroscience include studies of neuroreceptor/neurotransmitter levels in neuropsychiatric diseases (e.g., measuring receptor expression in schizophrenia) and of misfolded protein levels in neurodegenerative diseases (e.g., beta amyloid and tau deposits in Alzheimer's disease). Assessment of a PET tracer's test-retest properties is an important component of tracer validation, and it is usually carried out using data from a small number of subjects.

Results

Here, we investigate advantages and limitations of test-retest metrics that are commonly used for PET brain imaging, including percent test-retest difference and intraclass correlation coefficient (ICC). In addition, we show how random effects analysis of variance, which forms the basis for ICC, can be used to derive additional test-retest metrics, which are generally not reported in the PET brain imaging test-retest literature, such as within-subject coefficient of variation and repeatability coefficient. We reevaluate data from five published clinical PET imaging test-retest studies to illustrate the relative merits and utility of the various test-retest metrics. We provide recommendations on evaluation of test-retest in brain PET imaging and show how the random effects ANOVA based metrics can be used to supplement the commonly used metrics such as percent test-retest.

Conclusions

Random effects ANOVA is a useful model for PET brain imaging test-retest studies. The metrics that ensue from this model are recommended to be reported along with the percent test-retest metric as they capture various sources of variability in the PET test-retest experiments in a succinct way.

http://ift.tt/2Ce7nuV

A new SPECT/CT reconstruction algorithm: reliability and accuracy in clinical routine for non-oncologic bone diseases

Abstract

Background

xSPECT Bone® (xB) is a new reconstruction algorithm developed by Siemens® in bone hybrid imaging (SPECT/CT). A CT-based tissue segmentation is incorporated into SPECT reconstruction to provide SPECT images with bone anatomy appearance. The objectives of this study were to assess xB/CT reconstruction diagnostic reliability and accuracy in comparison with Flash 3D® (F3D)/CT in clinical routine. Two hundred thirteen consecutive patients referred to the Brest Nuclear Medicine Department for non-oncological bone diseases were evaluated retrospectively. Two hundred seven SPECT/CT were included. All SPECT/CT were independently interpreted by two nuclear medicine physicians (a junior and a senior expert) with xB/CT then with F3D/CT three months later. Inter-observer agreement (IOA) and diagnostic confidence were determined using McNemar test, and unweighted Kappa coefficient. The study objectives were then re-assessed for validation through > 18 months of clinical and paraclinical follow-up.

Results

No statistically significant differences between IOA _xB and IOA F3D were found (p = 0.532). Agreement for xB after categorical classification of the diagnoses was high (κ _xB = 0.89 [95% CI 0.84 –0.93]) but without statistically significant difference F3D (κ _F3D = 0.90 [95% CI 0.86 – 0.94]). Thirty-one (14.9%) inter-reconstruction diagnostic discrepancies were observed of which 21 (10.1%) were classified as major. The follow-up confirmed the diagnosis of F3D in 10 cases, xB in 6 cases and was non-contributory in 5 cases.

Conclusions

xB reconstruction algorithm was found reliable, providing high interobserver agreement and similar diagnostic confidence to F3D reconstruction in clinical routine.

http://ift.tt/2Elfb3H

Statistical evaluation of test-retest studies in PET brain imaging

Abstract

Background

Positron emission tomography (PET) is a molecular imaging technology that enables in vivo quantification of metabolic activity or receptor density, among other applications. Examples of applications of PET imaging in neuroscience include studies of neuroreceptor/neurotransmitter levels in neuropsychiatric diseases (e.g., measuring receptor expression in schizophrenia) and of misfolded protein levels in neurodegenerative diseases (e.g., beta amyloid and tau deposits in Alzheimer's disease). Assessment of a PET tracer's test-retest properties is an important component of tracer validation, and it is usually carried out using data from a small number of subjects.

Results

Here, we investigate advantages and limitations of test-retest metrics that are commonly used for PET brain imaging, including percent test-retest difference and intraclass correlation coefficient (ICC). In addition, we show how random effects analysis of variance, which forms the basis for ICC, can be used to derive additional test-retest metrics, which are generally not reported in the PET brain imaging test-retest literature, such as within-subject coefficient of variation and repeatability coefficient. We reevaluate data from five published clinical PET imaging test-retest studies to illustrate the relative merits and utility of the various test-retest metrics. We provide recommendations on evaluation of test-retest in brain PET imaging and show how the random effects ANOVA based metrics can be used to supplement the commonly used metrics such as percent test-retest.

Conclusions

Random effects ANOVA is a useful model for PET brain imaging test-retest studies. The metrics that ensue from this model are recommended to be reported along with the percent test-retest metric as they capture various sources of variability in the PET test-retest experiments in a succinct way.

from Cancer via ola Kala on Inoreader http://ift.tt/2Ce7nuV
via IFTTT

A new SPECT/CT reconstruction algorithm: reliability and accuracy in clinical routine for non-oncologic bone diseases

Abstract

Background

xSPECT Bone® (xB) is a new reconstruction algorithm developed by Siemens® in bone hybrid imaging (SPECT/CT). A CT-based tissue segmentation is incorporated into SPECT reconstruction to provide SPECT images with bone anatomy appearance. The objectives of this study were to assess xB/CT reconstruction diagnostic reliability and accuracy in comparison with Flash 3D® (F3D)/CT in clinical routine. Two hundred thirteen consecutive patients referred to the Brest Nuclear Medicine Department for non-oncological bone diseases were evaluated retrospectively. Two hundred seven SPECT/CT were included. All SPECT/CT were independently interpreted by two nuclear medicine physicians (a junior and a senior expert) with xB/CT then with F3D/CT three months later. Inter-observer agreement (IOA) and diagnostic confidence were determined using McNemar test, and unweighted Kappa coefficient. The study objectives were then re-assessed for validation through > 18 months of clinical and paraclinical follow-up.

Results

No statistically significant differences between IOA _xB and IOA F3D were found (p = 0.532). Agreement for xB after categorical classification of the diagnoses was high (κ _xB = 0.89 [95% CI 0.84 –0.93]) but without statistically significant difference F3D (κ _F3D = 0.90 [95% CI 0.86 – 0.94]). Thirty-one (14.9%) inter-reconstruction diagnostic discrepancies were observed of which 21 (10.1%) were classified as major. The follow-up confirmed the diagnosis of F3D in 10 cases, xB in 6 cases and was non-contributory in 5 cases.

Conclusions

xB reconstruction algorithm was found reliable, providing high interobserver agreement and similar diagnostic confidence to F3D reconstruction in clinical routine.

from Cancer via ola Kala on Inoreader http://ift.tt/2Elfb3H
via IFTTT

Chest wall recurrence in pT1-2N0-1 breast cancer patients after mastectomy without radiotherapy

Abstract

Purpose

In correlation with the nodal status in the era of modern radiotherapy, the chest wall recurrence (CWR) rate was investigated in pT1-2N0-1 breast cancer patients after a mastectomy without post-mastectomy radiotherapy (PMRT).

Methods

The data from the patients participating in two South Korean multi-institutional studies (KROG 14–22; N = 1842 and KROG 14–23; N = 1382) were analyzed. In total, 3224 pT1-2N0-1 breast cancer patients who underwent mastectomy without PMRT were analyzed.

Results

The median follow-up time was 72.2 months (range 0.8–125.2 months). The overall CWRs during the follow-up period were 1.68% in N0 patients and 2.82% in N1 patients. There was no statistically significant difference in 5-year and 10-year CWR-free survival (CWRFS) between the N0 and N1 patients. Of the 70 patients with CWR, 33 (1% of all the patients) had isolated CWR, and the 10-year overall survival rate in this group was 96.9%. After the propensity score matching of the N0 and N1 groups, there was still no difference in CWRFS by nodal status.

Conclusions

The incidence of CWR in pT1-2N0-1 breast cancer patients is very low, especially with isolated recurrence. Also, the obtained data showed that the nodal status had no impact on CWRFS.

http://ift.tt/2Enlioq

Do patients whose tumor achieved a pathological response relapse at specific sites? A substudy of the EORTC 10994/BIG-1-00 trial

Abstract

Purpose

To determine the sites of first distant relapse in patients with or without pCR following neoadjuvant chemotherapy in breast cancer patients enrolled in the EORTC 10994/BIG-1-00 trial.

Methods

We included patients enrolled in the EORTC 10994/BIG-1-00 trial who received at least one chemotherapy cycle before surgery and who had been diagnosed with a distant relapse. pCR was defined as no evidence of residual invasive cancer in the primary tumor and axillary lymph nodes with or without residual ductal carcinoma in situ. Site of first distant relapse was categorized as 'soft tissue,' 'visceral,' 'skeletal,' 'central nervous system (CNS),' and 'other.' The association between relapse site and achievement of pCR was assessed using multivariate logistic regression models for molecular subtypes classification and preceding locoregional recurrence.

Results

The study included 383 (21%) eligible patients out of the 1856 randomized, of whom 28 (7%) had achieved pCR. Median follow-up was 5.4 years. Achievement of pCR was associated with a trend towards a decreased presentation of skeletal metastases [21% (pCR) vs. 50% (non-pCR), OR 0.32, adjusted p value = 0.071] and an increase in the proportion of patients with CNS metastases as first distant relapse site (21% vs. 9%, OR 2.39, adjusted p value = 0.183). Patients with pCR were more likely to present with only one relapse location category when compared to non-pCR (86% vs. 69%).

Conclusion

Patients that achieved a pCR appeared less likely to present with skeletal metastases and more frequently presented with CNS metastases as first site of distant relapse, even after adjustment for molecular subtypes.

http://ift.tt/2CgFQci

Cancer and aging in Ibero-America

Abstract

Population aging represents a worldwide challenge. In Ibero-America (Spain, Portugal, and the American countries in which the Spanish or Portuguese language are spoken), the number of older adults is growing, leading to an increase in aging-related diseases such as cancer. Older adults already account for half of all cancer cases in Ibero-America, and this proportion will continue to increase. Furthermore, Ibero-American healthcare systems are not adequately prepared to provide care for older adults with cancer, mainly due to a lack of resources and generalized paucity of geriatric training for healthcare providers. Across the region, several clinical initiatives, educational activities and research collaborations have been established to set the foundations of Ibero-American geriatric oncology and to increase the geriatric knowledge among healthcare providers. This article provides an overview of the current landscape of geriatric oncology in Ibero-America, highlighting its critical challenges, opportunities for improvement and collaboration, and future directions.

http://ift.tt/2EnB0vq