Interrater and intrarater agreements of magnetic resonance imaging findings in the lumbar spine: significant variability across degenerative conditions

Background context

Magnetic resonance imaging (MRI) is frequently used in the evaluation of degenerative conditions in the lumbar spine. The relative interrater and intrarater agreements of MRI findings across different pathologic conditions are underexplored, as most studies are focused on specific findings.

Purpose

The purpose of this study was to characterize the interrater and intrarater agreements of MRI findings used to assess the degenerative lumbar spine.

Study design

A retrospective diagnostic study at a large academic medical center was undertaken with a panel of orthopedic surgeons and musculoskeletal radiologists to assess lumbar MRIs using standardized criteria.

Patient sample

Seventy-five subjects who underwent routine lumbar spine MRI at our institution were included.

Outcome measures

Each MRI study was assessed for 10 lumbar degenerative findings using standardized criteria. Lumbar vertebral levels were assessed independently, where applicable, for a total of 52 data points collected per study.

Methods

T2-weighted axial and sagittal MRI sequences were presented in random order to the four reviewers (two orthopedic spine surgeons and two musculoskeletal radiologists) independently to determine interrater agreement. The first 10 studies were reevaluated at the end to determine intrarater agreement. Images were assessed using standardized and pilot-tested criteria to assess disc degeneration, stenosis, and other degenerative changes. Interrater and intrarater absolute percent agreements were calculated. To highlight the most clinically important MRI disagreements, a modified agreement analysis was also performed (in which disagreements between the lowest two severity grades for applicable conditions were ignored). Fleiss kappa coefficients for interrater agreement were determined.

Results

The overall absolute and modified interrater agreements were 76.9% and 93.5%, respectively. The absolute and modified intrarater agreements were 81.3% and 92.7%, respectively. Average Fleiss kappa coefficient was 0.431, suggesting moderate overall agreement. However, when stratified by condition, absolute interrater agreement ranged from 65.1% to 92.0%. Disc hydration, disc space height, and bone marrow changes exhibited the lowest absolute interrater agreements. The absolute intrarater agreement had a narrower range, from 74.5% to 91.5%. Fleiss kappa coefficients ranged from fair-to-substantial agreement (0.282–0.618).

Conclusions

Even in a study using standardized evaluation criteria, there was significant variability in the interrater and intrarater agreements of MRI in assessing different degenerative conditions of the lumbar spine. Clinicians should be aware of the condition-specific diagnostic limitations of MRI interpretation.     

Nicotinic acid treatment for Paralepistopsis acromelalga intoxication: assessment using magnetic resonance imaging

Context: Paralepistopsis acromelalga, formerly known as Clitocybe acromelalga, is a rare poisonous mushroom. The mycotoxins in this mushroom cause symptoms resembling those of erythromelalgia; however, its pathogenesis remains unclear. In this report, a patient who received nicotinic acid treatment for P. acromelalga poisoning and radiological evaluation for erythromelalgia has been presented.

Case detail: A 59-year-old woman was hospitalized for redness, swelling, and burning pain in her extremities that rendered difficulty in walking, and a diagnosis of P. acromelalga poisoning was made by detailed interview and mushroom identification. She was treated with intravenous nicotinic acid for 17 days followed by oral nicotinic acid amide for 2 months. She exhibited rapid symptomatic improvement and walked independently after 11 days of initial treatment. Initial MRI of her feet revealed toe-dominated subcutaneous thickening. After nicotinic acid treatment, those radiological findings improved dramatically.

Discussion: The subcutaneous thickening evident on MRI indicated P. acromelalga poisoning-induced erythromelalgia involved subcutaneous inflammatory edema. The typical duration of edema without treatment is more than a month. The improvement on MRI after nicotinic acid treatment indicated that the adequate vasodilation induced by nicotinic acid contributed to resolution of the symptoms. Nicotinic acid was associated with the improvement of the edematous changes caused by the P. acromelalga intoxication.     

磁共振引导高强度聚焦超声犬去肾交感神经化的可行性研究

目的 探讨磁共振成像（magnetic resonance imaging, MRI）引导高强度聚焦超声（high intensity focused ultrasound,HIFU）犬模型去肾交感神经化的可行性。方法 健康杂种犬10只,随机均分成实验组（n=5）和对照组(n=5)。HIFU治疗焦点在MRI引导下对实验组犬右侧的肾交感神经行多个点状的消融（声功率300W,辐照时间2s,600J,矢状位2个层面）,对照组与实验组进行相同实验流程,但不做消融处理。所有犬在消融后第6天监测动脉血压后处死;对右侧肾动脉、周围交感神经进行大体肉眼观察和病理学检查;以右肾实质内去甲肾上腺素浓度来分析去交感神经化的效果。结果 HIFU消融后第六天,实验组犬右侧肾动脉外膜周围交感神经所在区域出现凝固的红色点, HE染色光镜下检查可见神经纤维出现破坏,雪旺氏细胞损伤,而对照组犬肉眼观和病理组织学未见明显异常;实验组犬右侧肾实质中去甲肾上腺素与对照组相比显著降低（p<0.05）;两组犬的动脉血压在消融后第6天对比无明显差异 (p>0.05)。结论 本研究表明MRI引导HIFU肾去交感神经化在犬模型中是可行的。     

Fluorescent-tilmanocept for tumor margin analysis in the mouse model

Background

Dendritic cells (DC) are localized in close proximity to cancer cells in many well-known tumors, and thus maybe a useful target for tumor margin assessment.

Materials and methods

[^99mTc]- cyanine 7 (Cy7)-tilmanocept was synthesized and in vitro binding assays to bone marrow-derived DC were performed. Fifteen mice, implanted with either 4T1 mouse mammary or K1735 mouse melanoma tumors, were administered 1.0 nmol of [^99mTc]-Cy7-tilmanocept via tail vein injection. After fluorescence imaging 1 or 2 h after injection, the tumor, muscle, and blood were assayed for radioactivity to calculate percent-injected dose. Digital images of the tumors after immunohistochemical staining for DC were analyzed to determine DC density.

Results

In vitro binding demonstrated subnanomolar affinity of [^99mTc]-Cy7-tilmanocept to DC (K_A = 0.31 ± 0.11 nM). After administration of [^99mTc]-Cy7-tilmanocept, fluorescence imaging showed a 5.5-fold increase in tumor signal as compared with preinjection images and a 3.3-fold difference in fluorescence activity when comparing the tumor with the surgical bed after tumor excision. Immunohistochemical staining analysis demonstrated that DC density positively correlated with tumor percent of injected dose per gram (r = 0.672, P = 0.03), and higher DC density was observed at the periphery versus center of the tumor (186 ± 54 K versus 64 ± 16 K arbitrary units, P = 0.001).

Conclusions

[^99mTc]-Cy7-tilmanocept exhibits in vitro and in vivo tumor-specific binding to DC and maybe useful as a tumor margin targeting agent.     

磁共振颈动脉斑块成像技术的现状 与进展

颈动脉是动脉粥样硬化斑块易发部位,其脱落会导致下游血管的阻塞并引发卒中。由于优
秀的软组织对比度和较高的空间分辨率,磁共振影像可以提供颈动脉斑块易损性的直接证据。本文
将从临床应用需求的角度出发介绍磁共振颈动脉斑块成像和图像处理的关键技术,希望有助于从事
斑块的临床和研究的人员了解目前的成像方法和未来趋势。