Comparative Evaluation of Contrast-Enhanced MRI and FDG-PET/CT in Spinal Pathology: Image Quality and Short-Term Renal-Hematologic Safety

Background and Rationale

Magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) are widely used imaging modalities for the evaluation of cervical and lumbar spinal disorders. MRI primarily provides high-resolution anatomical information, whereas FDG-PET/CT provides metabolic and functional information that may assist in the assessment of inflammatory, infectious, degenerative, and neoplastic spinal conditions. Although both modalities are routinely used in clinical practice, differences in image quality characteristics and short-term physiological effects associated with imaging procedures remain areas of interest.

Study Design

This study is a prospective comparative observational study designed to evaluate image quality characteristics and short-term physiological effects associated with contrast-enhanced MRI and FDG-PET/CT in adult patients with cervical or lumbar spinal pathologies. A total of 120 participants are included, with 60 participants undergoing contrast-enhanced MRI and 60 participants undergoing FDG-PET/CT according to routine clinical indications and standard institutional workflows.

The study is non-interventional. No experimental treatments, investigational drugs, or deviations from standard clinical care are introduced. All imaging procedures are performed according to established institutional protocols and manufacturer recommendations.

Study Population

Eligible participants are adults with clinically suspected or confirmed cervical or lumbar spinal pathology requiring advanced imaging evaluation. Conditions may include degenerative, inflammatory, infectious, neoplastic, traumatic, or post-surgical spinal disorders.

Imaging Procedures

MRI examinations are performed using a 3 Tesla scanner equipped with a dedicated spinal coil. Standard spinal imaging protocols include sagittal and axial T1-weighted and T2-weighted sequences. Intravenous gadolinium-based contrast administration is performed according to institutional guidelines and standard clinical practice.

FDG-PET/CT examinations are performed following standard patient preparation procedures, including fasting requirements and blood glucose assessment. Intravenous administration of 18F-fluorodeoxyglucose (FDG) is followed by image acquisition using routine clinical PET/CT protocols. CT acquisition is used for attenuation correction and anatomical localization according to institutional practice.

Image Quality Assessment

Quantitative image quality assessment includes measurement of signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) using standardized regions of interest. Measurements are performed using predefined image analysis procedures to ensure consistency across participants.

Qualitative image quality assessment is performed using Visual Grading Analysis (VGA). Independent blinded radiologists evaluate image quality using predefined criteria related to anatomical detail, tissue contrast, lesion conspicuity, image noise, and overall diagnostic usability.

Physiological and Safety Assessments

Short-term physiological effects associated with imaging procedures are evaluated using laboratory measurements obtained before imaging and 48 hours after imaging. Laboratory assessments include blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), and hemoglobin concentration.

Routine safety monitoring is performed according to institutional standards. Adverse events associated with contrast administration or imaging procedures are documented and managed according to standard clinical protocols.

Subgroup Analyses

Prespecified subgroup analyses evaluate image quality metrics according to spinal region (cervical versus lumbar) and age group (50 years or younger versus older than 50 years). These analyses are intended to explore potential differences in imaging performance across clinically relevant patient subgroups.

Study Objectives

The primary objectives are to compare quantitative image quality metrics between contrast-enhanced MRI and FDG-PET/CT and to evaluate qualitative image quality using blinded radiologist assessment.

Secondary objectives include assessment of short-term changes in renal and hematologic laboratory parameters following imaging procedures performed as part of routine clinical care.

Ethics

The study is conducted in accordance with applicable ethical principles, institutional policies, and approved research protocols. Institutional Review Board approval has been obtained, and informed consent procedures are implemented as required by the approved protocol and applicable regulations.