Hura Nanki, Yi Julie S, Lin Sandra Y, Roxbury Christopher R
Department of Otolaryngology - Head and Neck Surgery, 1500The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Department of Otolaryngology - Head and Neck Surgery, 6595University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
Am J Rhinol Allergy. 2022 Sep;36(5):668-683. doi: 10.1177/19458924221096913. Epub 2022 May 18.
Patients with acquired, idiopathic olfactory dysfunction (OD) commonly undergo magnetic resonance imaging (MRI) evaluation to rule out intracranial pathologies. This practice is highly debated given the expense of MRI relative to the probability of detecting a treatable lesion. This, combined with the increasing use of MRI in research to investigate the mechanisms underlying OD, provided the impetus for this comprehensive review.
The purpose of this systematic review was to both assess the utility of MRI in diagnosis of idiopathic OD and to describe MRI findings among mixed OD etiologies to better understand its role as a research tool in this patient population.
A literature search of PubMed, Embase, Cochrane, Web of Science, and Scopus for studies with original MRI data for patients with OD was completed. Studies exclusively investigating patients with neurocognitive deficits or those studying traumatic or congenital etiologies of OD were excluded.
From 1758 candidate articles, 33 studies were included. Four studies reviewed patients with idiopathic OD for structural pathologies on MRI, of which 17 of 372 (4.6%) patients had a potential central cause identified, and 3 (0.8%) had an olfactory meningioma or olfactory neuroblastoma. Fourteen studies (42.4%) reported significant correlation between olfactory bulb volume and olfactory outcomes, and 6 studies (18.8%) reported gray matter volume reduction, specifically in the orbitofrontal cortex, anterior cingulate cortex, insular cortex, parahippocampal, and piriform cortex areas, in patients with mixed OD etiologies. Functional MRI studies reported reduced brain activation and functional connectivity in olfactory network areas.
MRI uncommonly detects intracranial pathology in patients with idiopathic OD. Among patients with mixed OD etiologies, reduced olfactory bulb and gray matter volume are the most common abnormal findings on MRI. Further research is required to better understand the role of MRI and its cost-effectiveness in patients with acquired, idiopathic OD.
获得性特发性嗅觉功能障碍（OD）患者通常会接受磁共振成像（MRI）评估，以排除颅内病变。鉴于MRI的费用与检测出可治疗病变的概率相比，这种做法备受争议。再加上MRI在研究中越来越多地用于探究OD的潜在机制，这为本次全面综述提供了动力。
本系统综述的目的是评估MRI在特发性OD诊断中的效用，并描述混合性OD病因患者的MRI表现，以更好地理解其在该患者群体中作为研究工具的作用。
通过检索PubMed、Embase、Cochrane、Web of Science和Scopus数据库，完成了对有OD患者原始MRI数据研究的文献检索。专门研究神经认知缺陷患者或研究OD创伤性或先天性病因的研究被排除。
从1758篇候选文章中，纳入了33项研究。四项研究对特发性OD患者的MRI结构病变进行了综述，其中372例患者中有17例（4.6%）发现了潜在的中枢病因，3例（0.8%）患有嗅沟脑膜瘤或嗅神经母细胞瘤。十四项研究（42.4%）报告嗅球体积与嗅觉结果之间存在显著相关性，六项研究（18.8%）报告了混合性OD病因患者的灰质体积减少，特别是在眶额皮质、前扣带回皮质、岛叶皮质、海马旁回和梨状皮质区域。功能MRI研究报告嗅觉网络区域的脑激活和功能连接减少。
MRI很少能检测出特发性OD患者的颅内病变。在混合性OD病因患者中，嗅球和灰质体积减少是MRI上最常见的异常表现。需要进一步研究以更好地理解MRI在获得性特发性OD患者中的作用及其成本效益。
