Vocal tract physiology and its MRI evaluation

Introduction. The rapid technological evolution in Magnetic Resonance Imaging (MRI) has recently offered a great opportunity for the analysis of voice production. Objectives. This article is aimed to describe main physiological principles at the base of voice production (in particular of vocal tract), and an overview about literature on MRI of the vocal tract. This is presented in order to analyze both present results and future perspectives. Method. A narrative review was performed by searching the MeSH terms “vocal tract” and “MRI” in PubMed database. Then, the obtained studies were subsequently selected by relevancy. Results. Main fields described in literature concern technical feasibility and optimization of MRI sequences, modifications of vocal tract in vowel or articulatory phonetics, modifications of vocal tract in singing, 3D reproduction of vocal tract and segmentation, and describing vocal tract in pathological conditions. Conclusions. MRI is potentially the best method to study the vocal tract physiology during voice production. Most recent studies have achieved good results in representation of changes in the vocal tract during emission of vowels and singing. Further developments in MR technique are necessary to allow an equally detailed study of faster movements that participate in the articulation of speaking, which will allow fascinating perspectives in clinical use.

Comparison of Plain X-ray and MRI Findings By Determining The Sensitivity and Specificity in the Diagnosis of Lumbar Spinal Stenosis

Background: Lumbar spinal stenosis is the most frequent indication for spine surgery. The X-ray and MRI are the choice of investigation. Justified use of radiography can be cost effective in the management of lumbar spinal stenosis. Objective: To evaluate and compare the sensitivity and specificity of the plain X-ray and MRI in the diagnosis of the lumbar spinal stenosis. Materials and Methods: A multicenter cross sectional analytical study was carried out from January 2014 to December 2015 on 70 patients of both sexes aged more than 25 years with chronic low back pain. Plain x-ray and MRI were done in all patients. The interval between plain x-ray and MRI was less than 3 months. A descriptive analysis was performed for all data. Results: The mean age (+ SD) was 45.1 (+ 5.4) years. Forty two (60%) were male and 28 (40%) were female. In plain x-ray of the lumbosacral spine, 30 (42.9%) had diskogenic spinal canal stenosis and 22 (31.4%) had both diskogenic and non diskogenic spinal canal stenosis. In the MRI, 35 (50.0%) cases had diskogenic spinal canal stenosis and 24 (34.3%) had both diskogenic and non diskogenic spinal canal stenosis. The validity of MRI evaluation for only diskogenic spinal canal stenosis was correlated, where the calculated values of plain x-ray were: sensitivity 80.0%, specificity 60.0%, accuracy 77.5%, positive predictive value 93.3% and negative predictive value 30.0%. The validity of MRI evaluation for both diskogenic and non diskogenic spinal canal stenosis was correlated, where the calculated values of plain x-ray were: sensitivity 83.3%, specificity 66.7%, accuracy 80.0%, positive predictive value 90.9% and negative predictive value 50.0%. Conclusion: Plain x-ray is a useful and reliable diagnostic modality for the evaluation, assessment and the subsequent appropriate management of lumbar spinal stenosis. KYAMC Journal. 2021;12(3): 161-165

P.173 Evaluation of Arterial Spin Labeling (ASL) Perfusion Imaging in Poorly-Defined Focal Epilepsy in Children

Background: Poorly-defined cases (PDCs) of focal epilepsy are cases with no/subtle MRI abnormalities or have abnormalities extending beyond the lesion visible on MRI. Here, we evaluated the utility of Arterial Spin Labeling (ASL) MRI perfusion in PDCs of pediatric focal epilepsy. Methods: ASL MRI was obtained in 25 consecutive children presenting with poorly-defined focal epilepsy (20 MRI- positive, 5 MRI-negative). Qualitative visual inspection and quantitative analysis with asymmetry and Z-score maps were used to detect perfusion abnormalities. ASL results were compared to the hypothesized epileptogenic zone (EZ) derived from other clinical/imaging data and the resection zone in patients with Engel I/II outcome and >18 month follow-up. Results: Qualitative analysis revealed perfusion abnormalities in 17/25 total cases (68%), 17/20 MRI-positive cases (85%) and none of the MRI-negative cases. Quantitative analysis confirmed all cases with abnormalities on qualitative analysis, but found 1 additional true-positive and 4 false-positives. Concordance with the surgically-proven EZ was found in 10/11 cases qualitatively (sensitivity=91%, specificity=50%), and 11/11 cases quantitatively (sensitivity=100%, specificity=23%). Conclusions: ASL perfusion may support the hypothesized EZ, but has limited localization benefit in MRI-negative cases. Nevertheless, owing to its non-invasiveness and ease of acquisition, ASL could be a useful addition to the pre-surgical MRI evaluation of pediatric focal epilepsy.

Prevalence of Macroprolactinemia in Patients with Hyperprolactinemia Using Roche Elecsys Platform in a Large Tertiary Referral Center in UAE

<b><i>Objectives:</i></b> Macroprolactin (macroPRL) excess is an important cause of hyperprolactinemia. Several prolactin assays have high reactivity to macroPRL. However, macroPRL screening is not routinely performed in many labs. This study aimed to evaluate the prevalence of macroprolactinemia (MP) in patients with elevated prolactin using the Roche Elecsys assay in a large tertiary center in UAE. <b><i>Materials and Methods:</i></b> Consecutive samples of patients with elevated prolactin presenting to Tawam Hospital from June to August 2018 were evaluated for MP. Polyethylene glycol (PEG) was used to precipitate macroPRL. Monomeric prolactin recovery cutoff ≤50% was used to determine the prevalence of MP. <b><i>Results:</i></b> A total of 180 patients with elevated prolactin were included in the study with a mean age of 33.1 ± 11.9 years. The majority were women (87.2%), and about 77.8% were newly diagnosed patients with hyperprolactinemia. The main indications for prolactin testing were menstrual irregularity (<i>n</i> = 121), infertility (<i>n</i> = 11), galactorrhea (<i>n</i> = 11), and sellar masses (<i>n</i> = 12). MP was present in 8.3% of the patients. The median (IQR) of total prolactin level was 740.5 (579–1,085) IU/m before PEG precipitation and was not significantly different between MP and true hyperprolactinemia cases. Three patients with MP had pituitary MRI evaluation, which was normal. Eight patients with MP were treated with cabergoline. <b><i>Conclusion:</i></b> One in 12 patients with hyperprolactinemia had MP on the Roche Elecsys assay defined as the cutoff recovery of ≤50% post-PEG precipitation. Physicians should be aware of the prolactin assay used in their labs, and we recommend routine macroPRL assessment in mild hyperprolactinemia samples in labs using the Roche Elecsys platform.