Brain metabolic correlates of Locus Coeruleus degeneration in Alzheimer's disease: a multimodal neuroimaging study

Locus Coeruleus (LC) degeneration occurs early in Alzheimer's disease (AD) and this could affect several brain regions innervated by LC noradrenergic axon terminals, as these bear neuroprotective effects and modulate neurovascular coupling/neuronal activity. We used LC-sensitive Magnetic Resonance imaging (MRI) sequences enabling LC integrity quantification, and [18F]Fluorodeoxyglucose (FDG) PET, to investigate the association of LC-MRI changes with brain glucose metabolism in cognitively impaired patients (30 amnesticMCI and 13 demented ones). Fifteen cognitively intact age-matched controls (HCs) were submitted only to LC-MRI for comparison with patients. Voxel-wise regression analyses of [18F]FDG images were conducted using the LC-MRI parameters signal intensity (LC_CR) and LC-belonging voxels (LC_VOX). Both LC_CR and LC_VOX were significantly lower in patients compared to HCs, and were directly associated with [18F]FDG uptake in fronto-parietal cortical areas, mainly involving the left hemisphere (p < 0.001, kE > 100). These results suggest a possible association between LC degeneration and cortical hypometabolism in degenerative cognitive impairment with a prevalent left-hemispheric vulnerability, and that LC degeneration might be linked to large-scale functional network alteration in AD pathology.

Os Supranaviculare as a Predisposing Factor to Navicular Stress Fractures

Teaching Point: An os supranaviculare is a variant of the anatomy which however may predispose to symptoms.

How embryology knowledge can help radiologists in the differential diagnosis of canal of Nuck pathologies

The Canal of Nuck (CN) is an anatomical structure which is often forgotten. It is the female equivalent of the male processus vaginalis and corresponds to a protrusion of parietal peritoneum that extends from the inguinal canal to labia majora. Radiologists rarely encounter patients with pathology of CN, especially in adult population. It is well known that CN diseases can occur in paediatric patient (especially younger than 5 years of age) and they are associated to high morbidity (for example ovarian hernia with high risk of incarceration and torsion). The aim of our work is to review embryology, anatomy and pathologies of the CN thanks to a multi modal approach-ultrasound (US), Computed Tomography (CT) and Magnetic Resonance imaging (MRI)-to make radiologists more aware of such conditions and guarantee a prompt and correct diagnosis not only in paediatric patients but also in the adult population.

The accuracy of Magnetic Resonance - Cone Beam Computed Tomography soft-tissue matching for prostate radiotherapy

BACKGROUND AND PURPOSE

Magnetic Resonance (MR)-Only radiotherapy requires a method for matching image with on-treatment Cone Beam Computed Tomography (CBCT). This study aimed to investigate the accuracy of MR-CBCT soft-tissue matching for prostate MR-only radiotherapy.

MATERIALS AND METHODS

Three patient cohorts were used, with all patients receiving MR and CT scans. For the first cohort (10 patients) the first fraction CBCT was automatically rigidly registered to the CT and MR scans and the MR-CT registration predicted using the MR-CBCT and CT-CBCT registrations. This was compared to the automatic MR-CT registration. For the second and third cohorts (five patients each) the first fraction CBCT was independently matched to the CT and MR by four radiographers, the MR-CBCT and CT-CBCT matches compared and the inter-observer variability assessed. The second cohort used a CT-based structure set and the third a MR-based structure set with the MR relabelled as a 'CT'.

RESULTS

The mean difference between predicted and actual MR-CT registrations was Δ R All = - 0.1 ± 0.2 mm (s.e.m.). Radiographer MR-CBCT registrations were not significantly different to CT-CBCT, with mean differences in soft-tissue match ⩽ 0.2 mm and all except one difference ⩽ 3.3 mm . This was less than the MR-CBCT inter-observer limits of agreement [ 3.5 , 2.4 , 0.9 ] mm (vertical, longitudinal, lateral), which were similar ( ⩽ 0.5 mm ) to CT-CBCT.

CONCLUSIONS

MR-CBCT soft-tissue matching is not significantly different to CT-CBCT. Relabelling the MR as a 'CT' does not appear to change the automatic registration. This suggests that MR-CBCT soft-tissue matching is feasible and accurate.

A novel framework for MR image segmentation and quantification by using MedGA

BACKGROUND AND OBJECTIVES

Image segmentation represents one of the most challenging issues in medical image analysis to distinguish among different adjacent tissues in a body part. In this context, appropriate image pre-processing tools can improve the result accuracy achieved by computer-assisted segmentation methods. Taking into consideration images with a bimodal intensity distribution, image binarization can be used to classify the input pictorial data into two classes, given a threshold intensity value. Unfortunately, adaptive thresholding techniques for two-class segmentation work properly only for images characterized by bimodal histograms. We aim at overcoming these limitations and automatically determining a suitable optimal threshold for bimodal Magnetic Resonance (MR) images, by designing an intelligent image analysis framework tailored to effectively assist the physicians during their decision-making tasks.

METHODS

In this work, we present a novel evolutionary framework for image enhancement, automatic global thresholding, and segmentation, which is here applied to different clinical scenarios involving bimodal MR image analysis: (i) uterine fibroid segmentation in MR guided Focused Ultrasound Surgery, and (ii) brain metastatic cancer segmentation in neuro-radiosurgery therapy. Our framework exploits MedGA as a pre-processing stage. MedGA is an image enhancement method based on Genetic Algorithms that improves the threshold selection, obtained by the efficient Iterative Optimal Threshold Selection algorithm, between the underlying sub-distributions in a nearly bimodal histogram.

RESULTS

The results achieved by the proposed evolutionary framework were quantitatively evaluated, showing that the use of MedGA as a pre-processing stage outperforms the conventional image enhancement methods (i.e., histogram equalization, bi-histogram equalization, Gamma transformation, and sigmoid transformation), in terms of both MR image enhancement and segmentation evaluation metrics.

CONCLUSIONS

Thanks to this framework, MR image segmentation accuracy is considerably increased, allowing for measurement repeatability in clinical workflows. The proposed computational solution could be well-suited for other clinical contexts requiring MR image analysis and segmentation, aiming at providing useful insights for differential diagnosis and prognosis.

[First Cases of Multiple Sclerosis in Niger]

We report the first two cases of clinically definite multiple sclerosis in Niger over a period of 20 years (1996-2016). They were a 19-year-old woman and a 46-year-old man, native from Niger, who had never left the country and had recurrently presented sensory and motor disorders and ophthalmologic disorders. The cerebrospinal magnetic resonance imaging had revealed suggestive lesions of multiple sclerosis. After ruling out other etiologies with similar clinical pictures, the diagnosis of multiple sclerosis had been considered in our two patients according to the revised criteria of McDonald 2010.

Applying a commercial atlas-based synthetic Computed Tomography algorithm to patients with hip prostheses for prostate Magnetic Resonance-only radiotherapy

BACKGROUND AND PURPOSE

Magnetic Resonance (MR)-only prostate radiotherapy has recently been clinically implemented using commercial synthetic Computed Tomography (sCT) algorithms. However patients with hip prostheses have been excluded from all MR-only research to date and assumed to require dedicated sCT algorithms. This study aimed to investigate the dosimetric accuracy of applying a commercial sCT algorithm, based on an atlas of patients without hip prostheses, to patients with prostheses.

MATERIALS AND METHODS

18 patients with unilateral hip prostheses received MR and CT scans in the radiotherapy position. sCTs were generated from the MR using a commercial algorithm. The clinical Volumetric Modulated Arc Therapy (VMAT) plan, consisting of partial arcs which avoided the prosthesis, was recalculated using the sCT and the dose distribution compared.

RESULTS

The mean isocentre dose difference was ΔD = (-0.4 ± 0.2)% (mean ± standard error of the mean (sem), range - 1.9%, 1.1%) and the mean differences in Planning Target Volume, bladder and rectum mean doses were ≤0.3%. The 3D global gamma pass rate with dose difference 1% and distance to agreement 1 mm within the body was Γ_Body^1/1 = (95.0 ± 0.5)% (sem) and within the 50% isodose volume, which excluded the prosthesis, was Γ_50%^1/1 = (98.5 ± 0.4)% (sem). The pass rate within the PTV was Γ_PTV^2/2 ≥ 99.7% for all patients, although for PTVs close (≤3.5 cm) to the prosthesis Γ_PTV^1/1 < 85% for three patients. The sCT did not accurately represent the prosthesis with a mean difference in radiological isocentre depth near the prosthesis of Δd_Outside^Rad = (15.8 ± 2.6) mm (sem). However inside the treatment plan arc the difference was Δd_Inside^Rad = (-1.8 ± 0.5) mm (sem).

CONCLUSIONS

Using a commercial prostate sCT algorithm for patients with unilateral hip prostheses is dosimetrically accurate (<0.5%) as long as the routine prosthesis-avoidance treatment planning approach is used and the PTV is >3.5 cm from the prosthesis. This suggests MR-only prostate radiotherapy can be extended to patients with hip prostheses without requiring a specific sCT algorithm.

3D Fast Spin-Echo T1 Black-Blood Imaging for the Preoperative Detection of Venous Sinus Invasion by Meningioma : Comparison with Contrast-Enhanced MRV

OBJECTIVES

To prospectively evaluate the diagnostic value of 3D fast spin-echo (FSE) T1 black-blood magnetic resonance (MR) imaging (3D CUBE T1WI) in comparison with contrast-enhanced MR venography (CE-MRV) in the detection of sinus invasion by meningiomas.

METHODS

In this study forty consecutive patients with suspected meningiomas adjacent to venous sinus underwent conventional MR imaging, CE-MRV and 3D CUBE T1WI scans. Images obtained by each technique were assessed independently by two neuroradiologists for (1) wall invasion and (2) lumen occlusion of the target venous sinus.

RESULTS

The use of 3D CUBE T1W imaging was found to provide an easy way to detect the venous wall invasion by para-sinus lesions. The interobserver agreement was excellent (κ = 0.843; 95% confidence interval CI 0.757-0.929) and the result was highly consistent with the surgical findings (sensitivity 90.48%, specificity 94.12%). In the analysis of the lumen occlusion, the interobserver agreement obtained by 3D CUBE T1WI sequence was excellent (κ = 0.956; 95% CI, 0.913-0.999) with a diagnostic accuracy of 94.74%, which surpassed CE-MRV not only in interobserver agreement (κ = 0.736; 95% CI, 0.639-0.833) but also in diagnostic value (accuracy = 68.42%). Among 38 patients with meningiomas, the existence and extent of peritumoral edema did not correlate with the invasion of adjacent venous sinus.

CONCLUSION

Currently, 3D CUBE T1WI sequence is a reliable technique to provide accurate assessment about the venous sinus invasion by meningioma. Meanwhile, CE-MRV is more suitable in the evaluation of the bypass draining veins around the tumor.

Differentiation of Deep Subcortical Infarction Using High-Resolution Vessel Wall MR Imaging of Middle Cerebral Artery

Objective

To evaluate the utility of high-resolution vessel wall imaging (HR-VWI) of middle cerebral artery (MCA), and to compare HR-VWI findings between striatocapsular infarction (SC-I) and lenticulostriate infarction (LS-I).

Materials and Methods

This retrospective study was approved by the Institutional Review Board, and informed consent was waived. From July 2009 to February 2012, 145 consecutive patients with deep subcortical infarctions (SC-I, n = 81; LS-I, n = 64) who underwent HR-VWI were included in this study. The degree of MCA stenosis and the characteristics of MCA plaque (presence, eccentricity, location, extent, T2-high signal intensity [T2-HSI], and plaque enhancement) were analyzed, and compared between SC-I and LS-I, using Fisher's exact test.

Results

Stenosis was more severe in SC-I than in LS-I (p = 0.040). MCA plaque was more frequent in SC-I than in LS-I (p = 0.028), having larger plaque extent (p = 0.001), more T2-HSI (p = 0.001), and more plaque enhancement (p = 0.002). The eccentricity and location of the plaque showed no significant difference between the two groups.

Conclusion

Both SC-I and LS-I have similar HR-VWI findings of the MCA plaque, but SC-I had more frequent, larger plaques with greater T2-HSI and enhancement. This suggests that HR-VWI may have a promising role in assisting the differentiation of underlying pathophysiological mechanism between SC-I and LS-I.

Prognostic factors of recurrence and neck metastasis in oral carcinomas

Objective:

To assess the effects of tumor size, proximity to midline and invasion depth of oral cancer of the tongue (TC) on neck metastasis and recurrence.

Methods:

In this retrospective observational study, was conducted through a chart review of the 11 male and 9 female patients who underwent surgeries with the diagnosis of tongue squamous cell carcinoma and at least one side neck dissection. We wanted to assess effects of tumor size, proximity to midline, and invasion depth of TC, according to the surgical specimens and pre-operative magnetic resonance imaging, on neck metastasis and recurrence between 2007 and 2014. The study was conducted in a training hospital-based otorhinolaryngology clinic. Statistical analyses were performed to determine possible relationship between such tumor features and tumor recurrence and neck metastasis.

Results:

Statistically significant relationship were detected between recurrence and the proximity of tumor to midline (p=0.031) and between invasion depth and neck metastasis (p=0.017). No relationship was found between tumor size and recurrence and neck metastasis (p=0.721 and p=0.827, respectively).

Conclusions:

Parameters like invasion depth and tumor proximity to midline might provide useful information about prognosis and may help to determine a treatment schedule in patients suffering fdrom cancer of the tongue. The present TNM classification might not be sufficient to provide enough information to determine prognosis and staging adequately in these patients.

Cervical vagal schwannoma. A case report

Schwannoma originating from the cervical vagus nerve is an extremely rare neoplasm. Vagal nerve schwannoma usually occurs between the third and fifth decades of life, it does not show sex predilection both sexes being equally affected and it most often presents as a painless, slow-growing, lateral neck mass. The treatment of choice is complete surgical excision with preservation of the neural pathway, when it is possible. These tumours, in fact, are almost always benign and a conservative surgical approach is emphasized by most of the Authors. A case of a cervical vagal schwannoma, in a 33-year old male with a previous medical history of malignant lymphoma, is described. The clinical features, diagnosis, management and pathological findings of cervical vagal schwannoma are discussed.