Comparison of Myocardial Blood Flow Quantification Models for Double ECG Gating Arterial Spin Labeling MRI: Reproducibility Assessment.

BACKGROUND: Arterial spin labeling (ASL) allows non-invasive quantification of myocardial blood flow (MBF). Double-ECG gating (DG) ASL is more robust to heart rate variability than single-ECG gating (SG), but its reproducibility requires further investigation. Moreover, the existence of multiple quantification models hinders its application. Frequency-offset-corrected-inversion (FOCI) pulses provide sharper edge profiles than hyperbolic-secant (HS), which could benefit myocardial ASL. PURPOSE: To assess the performance of MBF quantification models for DG compared to SG ASL, to evaluate their reproducibility and to compare the effects of HS and FOCI pulses. STUDY TYPE: Prospective. SUBJECTS: Sixteen subjects (27 ± 8 years). FIELD STRENGTH/SEQUENCE: 1.5 T/DG and SG flow-sensitive alternating inversion recovery ASL. ASSESSMENT: Three models for DG MBF quantification were compared using Monte Carlo simulations and in vivo experiments. Two models used a fitting approach (one using only a single label and control image pair per fit, the other using all available image pairs), while the third model used a T1 correction approach. Slice profile simulations were conducted for HS and FOCI pulses with varying B0 and B1. Temporal signal-to-noise ratio (tSNR) was computed for different acquisition/quantification strategies and inversion pulses. The number of images that minimized MBF error was investigated in the model with highest tSNR. Intra and intersession reproducibility were assessed in 10 subjects. STATISTICAL TESTS: Within-subject coefficient of variation, analysis of variance. P-value <0.05 was considered significant. RESULTS: MBF was not different across acquisition/quantification strategies (P = 0.27) nor pulses (P = 0.9). DG MBF quantification models exhibited significantly higher tSNR and superior reproducibility, particularly for the fitting model using multiple images (tSNR was 3.46 ± 2.18 in vivo and 3.32 ± 1.16 in simulations, respectively; wsCV = 16%). Reducing the number of ASL pairs to 13/15 did not increase MBF error (minimum = 0.22 mL/g/min). DATA CONCLUSION: Reproducibility of MBF was better for DG than SG acquisitions, especially when employing a fitting model. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.

Assessment of Splenic Switch-Off With Arterial Spin Labeling in Adenosine Perfusion Cardiac MRI.

BACKGROUND: In patients with suspected coronary artery disease (CAD), myocardial perfusion is assessed under rest and pharmacological stress to identify ischemia. Splenic switch-off, defined as the stress to rest splenic perfusion attenuation in response to adenosine, has been proposed as an indicator of stress adequacy. Its occurrence has been previously assessed in first-pass perfusion images, but the use of noncontrast techniques would be highly beneficial. PURPOSE: To explore the ability of pseudo-continuous arterial spin labeling (PCASL) to identify splenic switch-off in patients with suspected CAD. STUDY TYPE: Prospective. POPULATION: Five healthy volunteers (age 24.8 ± 3.8 years) and 32 patients (age 66.4 ± 8.2 years) with suspected CAD. FIELD STRENGTH/SEQUENCE: A 1.5-T/PCASL (spin-echo) and first-pass imaging (gradient-echo). ASSESSMENT: In healthy subjects, multi-delay PCASL data (500-2000 msec) were acquired to quantify splenic blood flow (SBF) and determine the adequate postlabeling delay (PLD) for single-delay acquisitions (PLD > arterial transit time). In patients, single-delay PCASL (1200 msec) and first-pass perfusion images were acquired under rest and adenosine conditions. PCASL data were used to compute SBF maps and SBF stress-to-rest ratios. Three observers classified patients into "switch-off" and "failed switch-off" groups by visually comparing rest-stress perfusion data acquired with PCASL and first-pass, independently. First-pass categories were used as reference to evaluate the accuracy of quantitative classification. STATISTICAL TESTS: Wilcoxon signed-rank, Pearson correlation, kappa, percentage agreement, Generalized Linear Mixed Model, Mann-Whitney, Pearson Chi-squared, receiver operating characteristic, area-under-the-curve (AUC) and confusion matrix. SIGNIFICANCE: P value < 0.05. RESULTS: A total of 27 patients (84.4%) experienced splenic switch-off according to first-pass categories. Comparison of PCASL-derived SBF maps during stress and rest allowed assessment of splenic switch-off, reflected in a reduction of SBF values during stress. SBF stress-to-rest ratios showed a 97% accuracy (sensitivity = 80%, specificity = 100%, AUC = 85.2%). DATA CONCLUSION: This study could demonstrate the feasibility of PCASL to identify splenic switch-off during adenosine perfusion MRI, both by qualitative and quantitative assessments. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: 2.

Structural neuroimaging changes associated with subjective cognitive decline from a clinical sample.

BACKGROUND: Alzheimer's disease (AD) is characterized by progressive deterioration of cognitive functions. Some individuals with subjective cognitive decline (SCD) are in the early phase of the disease and subsequently progress through the AD continuum. Although neuroimaging biomarkers could be used for the accurate and early diagnosis of preclinical AD, the findings in SCD samples have been heterogeneous. This study established the morphological differences in brain magnetic resonance imaging (MRI) findings between individuals with SCD and those without cognitive impairment based on a clinical sample of patients defined according to SCD-Initiative recommendations. Moreover, we investigated baseline structural changes in the brains of participants who remained stable or progressed to mild cognitive impairment or dementia. METHODS: This study included 309 participants with SCD and 43 healthy controls (HCs) with high-quality brain MRI at baseline. Among the 99 subjects in the SCD group who were followed clinically, 32 progressed (SCDp) and 67 remained stable (SCDnp). A voxel-wise statistical comparison of gray and white matter (WM) volume was performed between the HC and SCD groups and between the HC, SCDp, and SCDnp groups. XTRACT ATLAS was used to define the anatomical location of WM tract damage. Region-of-interest (ROI) analyses were performed to determine brain volumetric differences. White matter lesion (WML) burden was established in each group. RESULTS: Voxel-based morphometry (VBM) analysis revealed that the SCD group exhibited gray matter atrophy in the middle frontal gyri, superior orbital gyri, superior frontal gyri, right rectal gyrus, whole occipital lobule, and both thalami and precunei. Meanwhile, ROI analysis revealed decreased volume in the left rectal gyrus, bilateral medial orbital gyri, middle frontal gyri, superior frontal gyri, calcarine fissure, and left thalamus. The SCDp group exhibited greater hippocampal atrophy (p < 0.001) than the SCDnp and HC groups on ROI analyses. On VBM analysis, however, the SCDp group exhibited increased hippocampal atrophy only when compared to the SCDnp group (p < 0.001). The SCD group demonstrated lower WM volume in the uncinate fasciculus, cingulum, inferior fronto-occipital fasciculus, anterior thalamic radiation, and callosum forceps than the HC group. However, no significant differences in WML number (p = 0.345) or volume (p = 0.156) were observed between the SCD and HC groups. CONCLUSIONS: The SCD group showed brain atrophy mainly in the frontal and occipital lobes. However, only the SCDp group demonstrated atrophy in the medial temporal lobe at baseline. Structural damage in the brain regions was anatomically connected, which may contribute to early memory decline.

Breath-Hold Induced Cerebrovascular Reactivity Measurements Using Optimized Pseudocontinuous Arterial Spin Labeling.

A pseudocontinuous arterial spin labeling (PCASL) sequence combined with background suppression and single-shot accelerated 3D RARE stack-of-spirals was used to evaluate cerebrovascular reactivity (CVR) induced by breath-holding (BH) in ten healthy volunteers. Four different models designed using the measured change in PETCO2 induced by BH were compared, for CVR quantification. The objective of this comparison was to understand which regressor offered a better physiological model to characterize the cerebral blood flow response under BH. The BH task started with free breathing of 42 s, followed by interleaved end-expiration BHs of 21 s, for ten cycles. The total scan time was 12 min and 20 s. The accelerated readout allowed the acquisition of PCASL data with better temporal resolution than previously used, without compromising the post-labeling delay. Elevated CBF was observed in most cerebral regions under hypercapnia, which was delayed with respect to the BH challenge. Significant statistical differences in CVR were obtained between the different models in GM (p < 0.0001), with ramp models yielding higher values than boxcar models and between the two tissues, GM and WM, with higher values in GM, in all the models (p < 0.0001). The adjustment of the ramp amplitude during each BH cycle did not improve the results compared with a ramp model with a constant amplitude equal to the mean PETCO2 change during the experiment.

Revisión de los factores de riesgo y factores protectores para el cáncer de mama

Objetivo: Revisar los aspectos clínicos necesarios a tomar en cuenta por el médico tratante al interpretar los reportes de los hallazgos radiológicos en la mamografía y de otras pruebas diagnósticas para un diagnóstico integral del cáncer de mama. Métodos: Se realizó una revisión sistemática de manuscritos publicados entre el 2010 y el 2020 sobre factores de riesgo y factores protectores que pueden verse involucrados en la incidencia del cáncer de mama. Se revisaron publicaciones de investigaciones realizadas en mujeres con diagnóstico de cáncer de mama de tipo ensayos clínicos aleatorizados, casos y controles, revisiones sistemáticas, metaanálisis y guías internacionales. Se buscó en las bases de datos bibliográficas PubMed, EBSCO y Scopus, publicaciones en inglés o español, utilizando términos provenientes de los Descriptores en Ciencias de la Salud (DeCS). Resultados: Se identificaron un total de 735 artículos en las búsquedas, de los cuáles se excluyeron 508 por su poca relevancia de acuerdo con el título. De los 227 restantes se excluyeron 22 por estar repetidos en las distintas bases, 12 porque no cumplían con los criterios de inclusión, 83 durante la revisión del resumen, y 28 al revisar el texto completo. En total se incluyeron 82 artículos para elaborar esta revisión. Los factores identificados en la revisión de la literatura se clasificaron en tres áreas: fisiopatológicos, gíneco-obstétricos y ambientales. Los factores de riesgo fisiopatológicos son la historia familiar, hiperplasia epitelial atípica, etnia, mayor edad, diabetes tipo II, síndrome metabólico, mayor peso y talla y mutaciones genéticas; los gíneco-obstétricos son la menarquía temprana, la menopausia tardía y la nuliparidad; y los ambientales incluyen fármacos, hábitos de vida, procedimientos médicos y alimentación. Mientras que, entre los factores protectores, los factores fisiopatológicos son el hipotiroidismo, el asma y la rinitis alérgica; los gínecoobstétricos son la multiparidad, el primer embarazo a una edad temprana y dar lactancia; y los ambientales incluyen fármacos, procedimientos médicos y alimentación.

Aim: To review relevant clinical aspects for the attending physician to consider when interpreting the reports of radiological findings in the mammogram and other diagnostic tests for a comprehensive breast cancer diagnosis. 2 ISSN 0001-6012 • eISSN 2215-5856 / Acta méd. costarric. 2022 / octubre-diciembre; 64 (4): 1-11 Cáncer mama factores de riesgo y de protección Methods: A systematic literature review was carried out focusing on risk and protective factors associated with breast cancer incidence, within peer-reviewed scientific articles published between 2010 and 2020. Published research on women with a breast cancer diagnoses who participated in randomized clinical trials, case control studies, systematic reviews, meta-analysis, and international guides were used. Research terms were searched on PubMed, EBSCO and Scopus databases, published in Spanish and English, using terms from the Medical Subject Headings (MeSH). Results: A total of 735 publications were found of which 508 were excluded due to title content being irrelevant to the review. Of the remainder 227, 22 were excluded due to been repeated across the different databases used, 12 because they did not meet the inclusion criteria, 83 after abstract review, and 28 after reading the whole text. A total of 82 papers were used for this review. The identified factors were categorized in three areas: pathophysiological, gynecological and obstetrics, and environmental factors. The pathophysiological risk factors are, family history, atypical hyperplasia, ethnicity, age, diabetes type II, metabolic syndrome, greater weight and height and genetic mutations; the gynecological and obstetric factors are early menarche, late menopause and nulliparity; and the environmental factors include prescription drugs, lifestyle habits, medical procedures and eating habits. Regarding the protector factors, the pathophysiological factors include hypothyroidism, asthma and allergic rhinitis; in the gynecological and obstetrics category are multiparity, the first pregnancy at early age and breast feeding; lastly, the environmental factors include prescription drugs, medical procedures and eating habits. Conclusions: Considering the risk and protector factors for breast cancer would allow a more comprehensive approach in the diagnosis and treatment of breast cancer.