Statistical Shape Analysis of Cerebellum in Patients With Chiari Malformation I

Characterizing prostate zonal shape changes associated with 5α-reductase inhibitors using MRI

Benign prostatic hyperplasia (BPH) is a prevalent medical disorder that primarily affects elderly males. It is distinguished by enhanced angiogenesis of the prostate, aggravating lower urinary tract symptoms (LUTS) and diminishing overall quality of life. Dutasteride, a 5α-reductase inhibitor, has emerged as a significant therapeutic choice for BPH owing to its efficacy in reducing prostate volume. The objective of this study is to analyze alterations in the shapes of prostate zones resulting from dutasteride treatment of BPH, using MRI. We examined 19 drug-administered patients and 33 non-drug-administered patients. MRI sections of all participants before and after drug treatment were collected retrospectively. The transition zone and peripheral zone of the prostate were marked with selected landmarks using TPSDIG v2.04. Generalized Procrustes Analysis was used to analyze shapes statistically. Our results showed that the 5α-reductase inhibitor significantly altered the shape of the transition zone by narrowing its posterior part. There were significant statistical differences between the drug-administered and non-drug-administered groups in the initial and final shapes of the transition zone. These findings indicate that the use of 5α-reductase inhibitors yielded favorable outcomes in terms of prostate size reduction and amelioration of symptoms associated with BPH.

Geometric morphometric analysis of the brainstem and cerebellum in Chiari I malformation

Background

Chiari I malformation (CMI) is characterized by inferior descent of the cerebellar tonsils through the foramen magnum and is associated with headache and neck pain. Many morphometric research efforts have aimed to describe CMI anatomy in the midsagittal plane using classical measurement techniques such as linear dimensions and angles. These methods are less frequently applied to parasagittal features and may fall short in quantifying more intricate anatomy with fewer distinct homologous landmarks.

Methods

Landmark-based geometric morphometric techniques were used to asses CMI morphology in five anatomical planes of interest.

Results

Significant shape differences between CMI and age/sex-matched controls were found in the midsagittal (Pseudo-F = 5.4841, p = 0.001) and axial planes through the rostral medulla (Pseudo-F = 7.6319, p = 0.001). In addition to tonsillar descent, CMI principal component 1 (PC1) scores in the midsagittal protocol were associated with marked anterior concavity of the brainstem and generalized verticality of the cerebellum with anterior rotation of its anterior lobe. In the axial medulla/cerebellum protocol, CMI PC1 scores were associated with greater anterior-posterior (A-P) dimension with loss of medial-lateral (M-L) dimension.

Discussion

These results suggest that CMI is associated with greater curvature of the brainstem and spinal cord, which may perturb normal neural activities and disrupt cerebrospinal fluid movements. Previous reports on the A-P diameter of the posterior fossa in CMI have conflicted; our findings of greater A-P cerebellar dimensionality with concomitant loss of width alludes to the possibility that more caudal aspects of the posterior cranial fossa are more bowl-like (homogenous in axial dimensions) and less trough-like or elongated in the M-L direction.

Statistical shape analysis of the lentiform nucleus of children of different age groups: a retrospective study

The basal nuclei are important during infancy because of the significant development of motor skills. The main aim of this study was to evaluate the shape differences of the lentiform nucleus between different age and gender groups. A total of 126 children's axial magnetic resonance image series were included in the presented study. These images were grouped between 1 and 5 yr old. Right and left lentiform nuclei are marked with selected landmarks using TPSDIG v2.04. Statistical shape analyses were examined by a Generalized Procrustes Analysis. Our results showed that there was no statistically significant difference in lentiform nucleus shape between genders. However, there was a difference between the shapes of the right and left lentiform nuclei between the 1-yr and 5-yr age groups. These results demonstrated the shape changes in the lentiform nucleus during the first 5 yr of life. Further clinical studies based on our results may be used to gather more detailed information about movement disorders and neuronal development.

Is there a morphometric cause of Chiari malformation type I? Analysis of existing literature

Although many etiologies have been proposed for Chiari malformation type I (CM-I), there currently is no singular known cause of CM-I pathogenesis. Advances in imaging have greatly progressed the study of CM-I. This study reviews the literature to determine if an anatomical cause for CM-I could be proposed from morphometric studies in adult CM-I patients. After conducting a literature search using relevant search terms, two authors screened abstracts for relevance. Full-length articles of primary morphometric studies published in peer-reviewed journals were included. Detailed information regarding methodology and symptomatology, craniocervical instability, syringomyelia, operative effects, and genetics were extracted. Forty-six studies met inclusion criteria, averaging 93.2 CM-I patients and 41.4 healthy controls in size. To obtain measurements, 40 studies utilized MRI and 10 utilized CT imaging, whereas 41 analyzed parameters within the posterior fossa and 20 analyzed parameters of the craniovertebral junction. The most commonly measured parameters included clivus length (n = 30), tonsillar position or descent (n = 28), McRae line length (n = 26), and supraocciput length (n = 26). While certain structural anomalies including reduced clivus length have been implicated in CM-I, there is a lack of consensus on how several other morphometric parameters may or may not contribute to its development. Heterogeneity in presentation with respect to the extent of tonsillar descent suggests alternate methods utilizing morphometric measurements that may help to identify CM-I patients and may benefit future research to better understand underlying pathophysiology and sequelae such as syringomyelia.