Quantification of 1.5 T T1 and T2* Relaxation Times of Fetal Tissues in Uncomplicated Pregnancies.

BACKGROUND: Despite its many advantages, experience with fetal magnetic resonance imaging (MRI) is limited, as is knowledge of how fetal tissue relaxation times change with gestational age (GA). Quantification of fetal tissue relaxation times as a function of GA provides insight into tissue changes during fetal development and facilitates comparison of images across time and subjects. This, therefore, can allow the determination of biophysical tissue parameters that may have clinical utility. PURPOSE: To demonstrate the feasibility of quantifying previously unknown T1 and T2* relaxation times of fetal tissues in uncomplicated pregnancies as a function of GA at 1.5 T. STUDY TYPE: Pilot. POPULATION: Nine women with singleton, uncomplicated pregnancies (28-38 weeks GA). FIELD STRENGTH/SEQUENCE: All participants underwent two iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL-IQ) acquisitions at different flip angles (6° and 20°) at 1.5 T. ASSESSMENT: Segmentations of the lungs, liver, spleen, kidneys, muscle, and adipose tissue (AT) were conducted using water-only images and proton density fat fraction maps. Driven equilibrium single pulse observation of T1 (DESPOT1 ) was used to quantify the mean water T1 of the lungs, intraabdominal organs, and muscle, and the mean water and lipid T1 of AT. IDEAL T2* maps were used to quantify the T2* values of the lungs, intraabdominal organs, and muscle. STATISTICAL TESTS: F-tests were performed to assess the T1 and T2* changes of each analyzed tissue as a function of GA. RESULTS: No tissue demonstrated a significant change in T1 as a function of GA (lungs [P = 0.89]; liver [P = 0.14]; spleen [P = 0.59]; kidneys [P = 0.97]; muscle [P = 0.22]; AT: water [P = 0.36] and lipid [P = 0.14]). Only the spleen and muscle T2* showed a significant decrease as a function of GA (lungs [P = 0.67); liver [P = 0.05]; spleen [P < 0.05]; kidneys [P = 0.70]; muscle [P < 0.05]). DATA CONCLUSION: These preliminary data suggest that the T1 of the investigated tissues is relatively stable over 28-38 weeks GA, while the T2* change in spleen and muscle decreases significantly in that period. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

Fetal Response to a Maternal Internal Auditory Stimulus.

BACKGROUND: Functional MRI (fMRI) is a noninvasive method to investigate the neural correlates of brain development. Insight into the rapidly developing brain in utero is limited, and fetal fMRI can be used to gain a greater understanding of the developmental process. Fetal brain fMRI is typically limited to resting-state fMRI due to the difficulty to instruct or provide a stimulus to the fetus. Previous studies have employed auditory task fMRI with an external sound stimulus directly on the abdomen of the mother; however, this practice has since been deemed unsafe for the developing fetus. PURPOSE: To investigate a reliable and safe paradigm to study the development of fetal brain networks, we postulated that an internal task, such as the mother's singing, as the auditory stimulus would result in activation in the fetal primary auditory cortex. STUDY TYPE: Cohort. POPULATION: Pregnant women with singleton pregnancies (n = 9; 33-38 weeks gestational age). FIELD STRENGTH/SEQUENCE: All subjects underwent two task-based block design blood oxygen level-dependent (BOLD) at 1.5T or 3T. ASSESSMENT: Each volume was assessed for fetal motion and manually reoriented and realigned to correct for fetal motion. Once the motion was corrected, a gestational age-matched parcellated atlas with regions of interest overlaid onto the activation map was used to determine which regions in the brain had activation during task phases. STATISTICAL TESTS: First Level Analysis. MRI data were analyzed using SPM 12 as a task fMRI. RESULTS: Eight subjects had activation on the right Heschl's gyrus; six fetuses demonstrated activation on the left when exposed to the internal acoustic stimulus. Additionally, activation was found on the right and left middle cingulate cortex (MCC) and the left putamen. DATA CONCLUSION: Maternal singing can be used as an internal stimulus to activate the auditory network and Heschl's gyrus during fetal fMRI. Level of Evidence 2 Technical Efficacy Stage 2 J. Magn. Reson. Imaging 2020;52:139-145.

Defining a Cohort that May Not Require Repeat Prostate Biopsy Based on PCA3 Score and Magnetic Resonance Imaging: The Dual Negative Effect.

PURPOSE: Prostate cancer over diagnosis and overtreatment are concerns for clinicians and policy makers. Multiparametric magnetic resonance imaging and the PCA3 (prostate cancer antigen 3) urine test select for clinically significant cases. We explored how well the tests performed together with previous biopsies. MATERIALS AND METHODS: In accordance with ethics committee approval we collected clinicopathological data on all patients in whom a PCA3 test was done from January 2011 to June 2016. This included patients on active surveillance for low risk prostate cancer and those without prostate cancer who had previous negative biopsies and suspicion of occult disease. We explored whether age, prostate specific antigen, PCA3 score, multiparametric magnetic resonance imaging, digital rectal examination, family history and prostate size would predict clinically significant prostate cancer on repeat biopsy. The negative predictive value of multiparametric magnetic resonance imaging and PCA3 score was calculated. RESULTS: A total of 470 patients were included in study. The PCA3 score was abnormal at 35 or greater in 32.5% of cases. In the multivariate model including 154 men only age (OR 1.08, 95% CI 1.01-1.16), multiparametric magnetic resonance imaging PI-RADS™ (Prostate Imaging-Reporting and Data System) score 4 (OR 16.6, 95% CI 3.9-70.0) or 5 (OR 28.3, 95% CI 5.7-138) and PCA3 score (OR 2.9, 95% CI 1.0-8.8) predicted clinically significant cancer on biopsy. No patient with negative multiparametric magnetic resonance imaging and a normal PCA3 score had clinically significant prostate cancer on biopsy for a negative predictive value of 100% (p <0.0001). CONCLUSIONS: In patients with dual negative tests (multiparametric magnetic resonance imaging and PCA3 score) clinically significant prostate cancer was never found on biopsy, which may be unnecessary in this group. This study was limited by its retrospective design, selection bias and lack of cost-effectiveness data.

Spinal cord atrophy after spinal cord injury - A systematic review and meta-analysis.

Cervical spinal cord atrophy occurs after spinal cord injury. The atrophy and how level of injury affects atrophy differs between studies. A systematic review and metaanalysis were done after systematic searches of PubMed, CINAHL, APA PsycInfo and Web of Science. English language original studies analyzing MRI cervical spinal cord cross-sectional area in adults with spinal cord injury were included. Atrophy and correlation between injury level and atrophy were estimated with random-effects models, standardized mean differences, and 95% confidence intervals. 24 studies were identified. 13/24 studies had low risk of bias. Cord atrophy meta-analysis of 18 articles corresponded to a standardized mean difference of -1.48 (95% CI -1.78 to -1.19) with moderate to large interstudy heterogeneity. Logarithmic time since injury influenced heterogeneity. Longitudinal atrophy was best described by a logarithmic model, indicating that rate of spinal atrophy decreases over time. Meta-correlation of eight studies indicated more severe atrophy in more rostral injuries (0.41, 95% CI 0.20-0.59). Larger and preferably longitudinal studies, data sharing, and standardized protocols are warranted.