Diffusion-weighted imaging measurements of central smell regions in COVID-19 patients: insular gyrus, corpus amygdala, and thalamus

OBJECTIVE

The aim of this study was to investigate central smell centers with cranial magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) in COVID-19.

PATIENTS AND METHODS

This retrospective study evaluated cranial MRI images of 54 adults. The experimental group (Group 1), consisting of 27 patients with positive COVID-19 real-time polymerase chain reaction (RT-PCR) assays, was compared to the control group (Group 2), comprising 27  healthy controls without COVID-19. The apparent diffusion coefficient (ADC) values were measured in the corpus amygdala, thalamus, and insular gyrus in both groups.

RESULTS

Thalamus ADC values of the COVID-19 group were significantly lower compared to the control group bilaterally. However, no differences were found in the insular gyrus and corpus amygdala ADC values between the two groups. Positive correlations were observed between the insular gyrus and corpus amygdala ADC values and the thalamus ADC values. Insular gyrus ADC values (right) were higher in females. Left insular gyrus and corpus amygdala ADC values were higher in COVID-19 patients with smell loss. Right insular gyrus and left corpus amygdala ADC values were lower in COVID-19 patients with lymphopenia.

CONCLUSIONS

Diffusion restriction in olfactory areas can be considered an obvious indicator that the COVID-19 virus affects and damages the immune system at the neuronal level. Given the urgency and lethality of the current pandemic, acute onset odor loss should be considered a high suspicion-adhesive index for patients with SARS-CoV-2 infection. Therefore, the sense of smell should be considered and evaluated simultaneously with other neurological symptoms. DWI should be widely used as an early imaging method for central nervous system (CNS) infections, especially in relation to COVID-19.

Preoperative and postoperative ultrasound elastography findings of the sciatic nerve in patients with unilateral lumbar foraminal disc herniation: a pre-test and post-test design

OBJECTIVE

The aim of this study was to compare preoperative and postoperative findings of the sciatic nerve by using B-mode ultrasound, strain elastography (SE), and shear wave elastography (SWE) in patients with unilateral lumbar foraminal disc herniation.

PATIENTS AND METHODS

In this prospective study group, patients with complaints of foraminal disc herniation due to one level (L4-5 or L5-S1) were included. Preoperative and postoperative (one month after surgery) B-mode ultrasound, SE, and SWE findings of the affected sciatic nerve in patients who underwent unilateral spinal decompression surgery were compared. Evaluations were performed on the axial plane from the gluteal region using a convex probe of 5-9L MHz. The reference method used to assess nerve root compression was 1.5-T Magnetic Resonance Imaging (MRI).

RESULTS

A total of 20 patients (9 males, 11 females) with a mean age of 46.2±13.1 years were included. The cross-sectional area (CSA), diameter, SWE values of the sciatic nerve were significantly higher in the affected side compared to those of the non-affected side (all for p<0.05). Blue and blue-green were the most common color codes in the affected side while green and green-yellow-red were the most common color codes in the non-affected side. The CSA, diameter, and SWE values of the sciatic nerve decreased after the surgery in the affected side (all for p<0.05), nonetheless. those did not differ in the non-affected side (all for p>0.05).

CONCLUSIONS

Lumbar decompression surgery decreases the sciatic nerve diameter, CSA, and stiffness of the sciatic nerve.

Brain diffusion-weighted imaging in diabetic patients with retinopathy

OBJECTIVE

Our aim was to detect whether there is any change in apparent diffusion coefficients (ADC) levels in different sites of the brain, particularly in areas associated with the vision, in diabetic patients with retinopathy by measuring diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

Conventional magnetic resonance imaging (MRI) and DWI of the brain were obtained from 45 diabetic patients (15 patients with proliferative diabetic retinopathy (group 1), 15 patients with nonproliferative diabetic retinopathy (group 2), 15 diabetic patients without retinopathy (group 3) and from 15 age-matched healthy volunteers (group 4). ADC values of visual cortex, cingulate gyrus, orbitofrontal, dorsomedial and dorsolateral frontal, corona radiate, and thalamus were obtained.

RESULTS

The ADC values of visual cortex, cingulate gyrus and orbitofrontal cortex significantly increased in groups 1 and 2 compared to groups 3 and 4 (p < 0.001). The ADC values of visual cortex significantly increased in group 1 compared to group 2 (p < 0.001). The duration of disease and value of HbAlc positively correlated with ADC values of the visual and orbitofrontal cortexes, and cingulate gyrus.

CONCLUSIONS

We found an increase in ADC values supporting the neuronal loss in some regions, especially in visual center by DWI in the diabetic patients with retinopathy. This result supports the association between diabetic retinopathy and brain injury.