Quantifying Apathy in Late-Life Depression: Unraveling Neurobehavioral Links through Daily Activity Patterns and Brain Connectivity Analysis

BACKGROUND

Better understanding apathy in late-life depression (LLD) would help predicting poor prognosis of the disease such as dementia. Actimetry provides an objective and ecological measure of apathy from patients' daily motor activity. We aimed to determine if patterns of motor activity were associated with apathy and brain connectivity in networks underlying goal-directed behaviors.

METHODS

Resting-state functional MRI and diffusion MRI were collected from 38 non-demented LLD subjects. Apathy was evaluated using the diagnostic criteria for apathy, the apathy evaluation scale (AES) and the apathy motivation index (AMI). Functional principal components (fPC) of motor activity were derived from actimetry recordings of 72 hours. Associations between fPC and apathy were estimated by linear regression. Subnetworks whose connectivity was significantly associated with fPC were identified via the threshold-free network-based statistics. The relationship between apathy and microstructure metrics was estimated along fibers by diffusion tensor imaging and a multicompartment model called neurite orientation dispersion and density imaging via tractometry.

RESULTS

We found two fPC associated with apathy: mean diurnal activity, negatively associated with AES, and an early chronotype, negatively associated with AMI. Mean diurnal activity was associated with increased connectivity in the default-mode, the cingulo-opercular and the frontoparietal networks, while chronotype was associated with a more heterogenous connectivity pattern in the same networks. We did not find significant associations between microstructural metrics and fPCs.

CONCLUSION

Our findings suggest that mean diurnal activity and chronotype could provide indirect ambulatory measures of apathy in LLD, associated with modified functional connectivity of brain networks underlying goal-directed behaviors.

Application of Diffusion Weighted Imaging in Prostate Cancer Bone Metastasis: Detection and Therapy Evaluation

BACKGROUND

Bone metastasis is one of the most common complications of Prostate Cancer (PCa). The detection of distal bone metastasis at the time of initial PCa diagnosis is valuable for the determination of therapeutic methods and for the prognosis of PCa. Many current therapeutic methods target PCa bone metastasis, but no uniform evaluation standard for therapeutic efficacy has been established; in addition, traditional therapeutic evaluation standards that rely on changes in the measured tumor volume are quite controversial. In clinical practice, the volumes of some tumors often change nonsignificantly at the early stage of therapy (especially targeted therapy), while the volumes of other tumors, such as metastatic bone lesions, are difficult to measure. Diffusion-Weighted Imaging (DWI) not only reflects the diffusion characteristics of tissues but can also allow the analysis of microstructural and functional changes in tissues. Therefore, DWI is suitable for evaluations of early responses to tumor therapy.

OBJECTIVE

This study mainly reviews the principle of DWI and its progress in the detection and therapy evaluation of PCa bone metastasis.

METHODS

PubMed was searched to identify eligible articles up to December 26, 2020. The keywords of the analysis included DWI, PCa, bone metastasis, therapeutic response, targeted therapy, Bone Scintigraphy (BS), Positron Emission Tomography/Computed Tomography (PET/CT) and metastatic Castration-Resistant Prostate Cancer (mCRPC).

RESULTS

This review based on collected articles achieved an imaging biomarker for detection and therapy evaluation of PCa bone metastasis.

CONCLUSION

DWI is a promising imaging method for the detection and therapeutic evaluation of PCa bone metastases.

Fused high b-value diffusion weighted and T2-weighted MR images in staging of pediatric Hodgkin's lymphoma: A pilot study

PURPOSE

To evaluate the value of fused high b-value diffusion weighted and T2-weighted MRI compared to T1-weighted imaging, T2-weighted imaging and DWI for staging pediatric Hodgkin's lymphoma.

METHOD

21 consecutive pediatric patients who underwent whole-body MRI at Hodgkin's lymphoma staging were included. Fused, colorized DWI/T2-weighted images were created. Image sets consisting of (a) T1-weighted, T2-weighted and DWI images and (b) T1-weighted, T2-weighted, DWI and DWI/T2-weighted fused images were reviewed by a radiologist using a cross-over design with blinding and randomization. Scoring was performed using a standardized form, based on detection, characterization and reading time, using a FDG-PET/CT based reference standard. Test characteristics, test agreement to a FDG-PET/CT based reference standard and reading times were calculated.

RESULTS

Agreement for whole-body MRI without fused images and FDG-PET/CT was very good for nodal staging (κ = 0.86, 95% CI 0.78-0.93) and extra-nodal staging (κ = 0.90, 95% CI 0.71-1.09). Agreement improved with the addition of the fused DWI/T2-weighted images (κ = 0.92 95% CI 0.87-0.97 (nodal staging), κ = 0.92 95% CI 0.76-1.08 (extra-nodal staging). Sensitivity and specificity for staging nodal disease were 99 % and 95% respectively for whole-body MRI including DWI/T2-weighted fused images (versus 88 % and 97 % without fused images) and 100 % and 99 % for extra-nodal disease (83 % and 100 % without fused images). Disease stage for MRI including fused DWI/T2-weighted images agreed with the reference standard in 18 out of 21 patients.

CONCLUSIONS

The addition of DWI/T2-weighted fusion images to T1-weighted, T2-weighted and DWI whole-body MRI might shorten reading times and might improve the diagnostic performance of whole-body MRI in staging pediatric Hodgkin's lymphoma.

Optimized Diffusion-Weighting Gradient Waveform Design (ODGD) formulation for motion compensation and concomitant gradient nulling

PURPOSE

To present a novel Optimized Diffusion-weighting Gradient waveform Design (ODGD) method for the design of minimum echo time (TE), bulk motion-compensated, and concomitant gradient (CG)-nulling waveforms for diffusion MRI.

METHODS

ODGD motion-compensated waveforms were designed for various moment-nullings M_n (n = 0, 1, 2), for a range of b-values, and spatial resolutions, both without (ODGD-M_n ) and with CG-nulling (ODGD-M_n -CG). Phantom and in-vivo (brain and liver) experiments were conducted with various ODGD waveforms to compare motion robustness, signal-to-noise ratio (SNR), and apparent diffusion coefficient (ADC) maps with state-of-the-art waveforms.

RESULTS

ODGD-M_n and ODGD-M_n -CG waveforms reduced the TE of state-of-the-art waveforms. This TE reduction resulted in significantly higher SNR (P < 0.05) in both phantom and in-vivo experiments. ODGD-M₁ improved the SNR of BIPOLAR (42.8 ± 5.3 vs. 32.9 ± 3.3) in the brain, and ODGD-M₂ the SNR of motion-compensated (MOCO) and Convex Optimized Diffusion Encoding-M₂ (CODE-M₂ ) (12.3 ± 3.6 vs. 9.7 ± 2.9 and 10.2 ± 3.4, respectively) in the liver. Further, ODGD-M₂ also showed excellent motion robustness in the liver. ODGD-M_n -CG waveforms reduced the CG-related dephasing effects of non CG-nulling waveforms in phantom and in-vivo experiments, resulting in accurate ADC maps.

CONCLUSIONS

ODGD waveforms enable motion-robust diffusion MRI with reduced TEs, increased SNR, and reduced ADC bias compared to state-of-the-art waveforms in theoretical results, simulations, phantoms and in-vivo experiments.

The Value of Diffusion-Weighted Magnetic Resonance Imaging in Predicting the Efficacy of Radiation and Chemotherapy in Cervical Cancer

Background

To analyze the application value of apparent diffusion coefficient (ADC) and exponent apparent diffusion coefficient (EADC) in evaluating the efficacy of radiation and chemotherapy in cervical cancer using pre- and posttreatment diffusion-weighted magnetic resonance imaging (DW-MRI) scans.

Methods

52 patients with cervical cancer were administered radiation and chemotherapy. Both MRI and DW-MRI were obtained at different stages. The ADC and EADC values, as well as the maximum tumor diameter, were measured and analyzed.

Results

We found that the ADC value increased after treatment, and the EADC value decreased. Changes in the calculated ADC occurred earlier than the morphologic changes of the tumors. A negative correlation was detected between reduced rates in the maximum tumor diameter two months after treatment and pretreatment ADC value (r = –0.658, P < 0.05). An ROC curve and nonlinear regression analysis showed that the formula, y = (1525500.122x² – 4689.962x + 3.482) × 100%, can be used to calculate the percentage of complete remission after treatment according to the pretreatment ADC value.

Conclusion

Our data suggest that pretreatment ADC and EADC values are predictive of the efficacy of radiation and chemotherapy. Both ADC and EADC values during treatment were instrumental in early monitoring and dynamic observation.

The Arcuate Fasciculus in auditory-verbal hallucinations: a meta-analysis of diffusion-tensor-imaging studies

Auditory-verbal hallucinations (AVHs) are associated with an impaired connectivity of large-scale networks. To examine the relationship between white-matter integrity and AVHs, we conducted a meta-analysis of diffusion-tensor-imaging studies that compared patients with schizophrenia and AVHs with matched healthy controls (HCs). Five studies were retained gathering 256 DTI data points, divided into AVHs (n=106) and HCs (n=150). The meta-analysis demonstrated a reduced fractional anisotropy in the left Arcuate Fasciculus (AF) of hallucinators (hg= -0.42; CI[-0.69,-0.16]; p<10(-3)). The current meta-analysis confirmed disruptions of white matter integrity in the left AF bundle of schizophrenia patients with AVHs.